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Sample records for anoxia

  1. EFFECTS OF ANOXIA ON WHEAT SEEDLINGS .1. INTERACTION BETWEEN ANOXIA AND OTHER ENVIRONMENTAL-FACTORS

    NARCIS (Netherlands)

    WATERS, [No Value; KUIPER, PJC; WATKIN, E; GREENWAY, H

    1991-01-01

    Anoxia was imposed on 4-6-d-old, intact wheat seedlings, after the roots had first been exposed for 1 d to O2 concentrations between 0.016 and 0.06 mol m-3. Apices of the main axis of the seminal roots were considered to have tolerated anoxia if elongation occurred after return from anoxia to air, h

  2. Experimental evidence for foraminiferal calcification under anoxia

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    M. P. Nardelli

    2014-03-01

    Full Text Available Benthic foraminiferal tests are widely used for paleoceanographic reconstructions. There is ample evidence that foraminifera can live in anoxic sediments. For some species, this is explained by a switch to facultative anaerobic metabolism (i.e. denitrification. Here we show for the first time that adult specimens of three benthic foraminiferal species are not only able to survive but are also able to calcify in anoxic conditions, at various depths in the sediment, with and without nitrates. This demonstrates ongoing metabolic processes, even in micro-environments where denitrification is not possible. Earlier observations suggest that the disappearance of foraminiferal communities after prolonged anoxia is not due to instantaneous or strongly increased adult mortality. Here we show that it cannot be explained by an inhibition of growth through chamber addition either. Our observations of ongoing calcification under anoxic conditions means that geochemical proxy data obtained from benthic foraminifera in settings experiencing intermittent anoxia have to be reconsidered. The analysis of whole single specimens or of their successive chambers may provide essential information about short-term environmental variability and/or the causes of anoxia.

  3. Investigation of two different anoxia models by 2-dimensional gel electrophoresis

    DEFF Research Database (Denmark)

    Wulff, Tune; Jessen, Flemming; Hoffmann, Else Kay

    2006-01-01

    This study presents a broad investigation of the effects of different types of anoxia in the Rainbow Trout Hypodermal Fibroblasts cell line, including a comparison of two widely used anoxia models. Anoxia was obtained either by flushing with N2 (FN) or by adding NaN3 to the medium, since chemical...... of molecular masses from 10 to 120 kDa and pI values from 4 to 7. In response to 24 h of anoxia obtained by FN we found that the sexpression of more than 30 proteins changed, including proteins involved in cell metabolism as well as protective proteins. Chemical anoxia for 30 minutes and subsequent...

  4. Characterization of sub-nuclear changes in Caenorhabditis elegans embryos exposed to brief, intermediate and long-term anoxia to analyze anoxia-induced cell cycle arrest

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    Trejo Jesus

    2005-12-01

    Full Text Available Abstract Background The soil nematode C. elegans survives oxygen-deprived conditions (anoxia; 2 by entering into a state of suspended animation in which cell cycle progression reversibly arrests. The majority of blastomeres of embryos exposed to anoxia arrest at interphase, prophase and metaphase. The spindle checkpoint proteins SAN-1 and MDF-2 are required for embryos to survive 24 hours of anoxia. To further investigate the mechanism of cell-cycle arrest we examined and compared sub-nuclear changes such as chromatin localization pattern, post-translational modification of histone H3, spindle microtubules, and localization of the spindle checkpoint protein SAN-1 with respect to various anoxia exposure time points. To ensure analysis of embryos exposed to anoxia and not post-anoxic recovery we fixed all embryos in an anoxia glove box chamber. Results Embryos exposed to brief periods to anoxia (30 minutes contain prophase blastomeres with chromosomes in close proximity to the nuclear membrane, condensation of interphase chromatin and metaphase blastomeres with reduced spindle microtubules density. Embryos exposed to longer periods of anoxia (1–3 days display several characteristics including interphase chromatin that is further condensed and in close proximity to the nuclear membrane, reduction in spindle structure perimeter and reduced localization of SAN-1 at the kinetochore. Additionally, we show that the spindle checkpoint protein SAN-1 is required for brief periods of anoxia-induced cell cycle arrest, thus demonstrating that this gene product is vital for early anoxia responses. In this report we suggest that the events that occur as an immediate response to brief periods of anoxia directs cell cycle arrest. Conclusion From our results we conclude that the sub-nuclear characteristics of embryos exposed to anoxia depends upon exposure time as assayed using brief (30 minutes, intermediate (6 or 12 hours or long-term (24 or 72 hours exposures

  5. Diurnal effects of anoxia on the metabolome of the seagrass Zostera marina

    DEFF Research Database (Denmark)

    Hasler-Sheetal, Harald; Fragner, Lena; Holmer, Marianne;

    2015-01-01

    spectrometry (GC–MS). During anoxia and light exposure the roots showed an altered metabolome whereas the leaves were only marginally affected, indicating that photosynthetically derived oxygen could satisfy the oxygen demand in the leaves but not in the roots. Nocturnal anoxia caused a biphasic shift...... in the metabolome of roots and leaves. The first phase, after 15 h under anoxia and 3 h of darkness showed a fast increase of lactate, pyruvate, GABA (γ-aminobutyric acid), succinate, alanine and a decrease in glutamate and glutamine. The second phase, after 21 h under anoxia and 9 h of darkness showed a decrease...... shunt as such mitigation mechanisms that alleviate pyruvate levels and lead to carbon and nitrogen storage during anoxia. This work demonstrates the applicability of metabolomics to assess low oxygen stress responses of Z. marina and allows us to propose an anoxia recovery model....

  6. Effects of postnatal anoxia on striatal dopamine metabolism and prepulse inhibition in rats

    DEFF Research Database (Denmark)

    Sandager-Nielsen, Karin; Andersen, Maibritt B; Sager, Thomas N;

    2004-01-01

    Various evidence indicate that schizophrenia is a neurodevelopmental disorder. Epidemiological observations point to oxygen deficiencies during delivery as one of the early risk factors for developing schizophrenia. The aim of the present study was to examine the effect of postnatal anoxia in rat...... to postnatal anoxia in the rat does not show clear-cut phenomenological similarities with the disorder....

  7. Selective extinction among Early Jurassic bivalves: A consequence of anoxia

    Science.gov (United States)

    Aberhan, Martin; Baumiller, Tomasz K.

    2003-12-01

    Analyses of taxonomically standardized data sets demonstrate several statistically robust extinction patterns in Early Jurassic bivalve species from northwest Europe and the Andean basins of South America. In both regions, extinction intensities were significantly enhanced in late Pliensbachian and early Toarcian time as compared to all other time intervals. The same intervals (except for the early Toarcian of South America) also represent times of unusual extinction selectivity, with infaunal taxa suffering distinctly more than epifaunal forms. As infaunal suspension feeders are extremely rare components of Early Jurassic oxygen-controlled macrofaunas, these results are entirely compatible with sedimentological and geochemical data suggesting that widespread anoxia was a principal cause of the diversity crisis. Although many biotic traits that enhance survivorship during background times seem to be irrelevant during major mass extinctions, patterns of survivorship selectivity may provide more distinct clues to the causes of less severe mass extinctions.

  8. Dramatic increase of nitrite levels in hearts of anoxia-exposed crucian carp supporting a role in cardioprotection

    DEFF Research Database (Denmark)

    Sandvik, Guro K.; Nilsson, Göran E.; Jensen, Frank Bo

    2012-01-01

    anoxia-tolerance of this fish by measuring NO metabolites in normoxic, anoxic and reoxygenated crucian carp. We also cloned and sequenced crucian carp NO synthase variants and quantified their mRNA levels in several tissues in normoxia and anoxia. Despite falling levels of blood plasma nitrite, the....... We conclude that nitrite is shifted into the tissues where it acts as NO donor during anoxia, inducing cytoprotection under anoxia/reoxygenation. This can be especially important in the crucian carp heart, which maintains output in anoxia. Nitrite is currently tested as a therapeutic drug against...

  9. Foraminiferal species responses to in situ experimentally induced anoxia in the Adriatic Sea

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    D. Langlet

    2013-07-01

    Full Text Available Anoxia was successfully induced in four benthic chambers installed at 24 m depth in the northern Adriatic Sea, for periods varying from 9 days to 10 months. During the 10 months period, species richness significantly decreased. Although no significant change in Shannon diversity and Evenness is observed, the composition of the foraminiferal assemblages changes with time. This change is due to interspecific differences in tolerance with respect to anoxia and free sulphides. Leptohalysis scottii, Textularia agglutinans and Quinqueloculina cf. stelligera all showed a significant decrease with time, strongly suggesting they are sensitive to the anoxia and sulphides. Conversely, Eggerella scabra, Bulimina marginata, Lagenammina atlantica, Hopkinsina pacifica and Bolivina pseudoplicata appear to be resistant to the experimental conditions. Quinqueloculina seminula also appears to be sensitive to anoxia but shows a clear standing stock increase during the first month of the experiment, which we interpret as an opportunistic response to increasing organic matter availability due to the degradation of the dead macrofaunal organisms. It appears that none of the anoxia sensitive species is capable to accumulate intracellular nitrates. Such a capacity could be shown for some tested specimens of the dominant anoxia tolerant species E. scabra and B. marginata. However, tests on the denitrification capacity of these taxa yielded negative results, suggesting that their resistance to long-term anoxia is not due to a capacity to denitrify.

  10. Mitochondrial DNA Sequence and Lack of Response to Anoxia in the Annual Killifish Austrofundulus limnaeus

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    Wagner, Josiah T.; Herrejon Chavez, Florisela; Podrabsky, Jason E.

    2016-01-01

    The annual killifish Austrofundulus limnaeus inhabits ephemeral ponds in regions of Venezuela, South America. Permanent populations of A. limnaeus are maintained by production of stress-tolerant embryos that are able to persist in the desiccated sediment. Previous work has demonstrated that A. limnaeus have a remarkable ability to tolerate extended periods of anoxia and desiccating conditions. After considering temperature, A. limnaeus embryos have the highest known tolerance to anoxia when compared to any other vertebrate yet studied. Oxygen is completely essential for the process of oxidative phosphorylation by mitochondria, the intracellular organelle responsible for the majority of adenosine triphosphate production. Thus, understanding the unique properties of A. limnaeus mitochondria is of great interest. In this work, we describe the first complete mitochondrial genome (mtgenome) sequence of a single adult A. limnaeus individual and compare both coding and non-coding regions to several other closely related fish mtgenomes. Mitochondrial features were predicted using MitoAnnotator and polyadenylation sites were predicted using RNAseq mapping. To estimate the responsiveness of A. limnaeus mitochondria to anoxia treatment, we measure relative mitochondrial DNA copy number and total citrate synthase activity in both relatively anoxia-tolerant and anoxia-sensitive embryonic stages. Our cross-species comparative approach identifies unique features of ND1, ND5, ND6, and ATPase-6 that may facilitate the unique phenotype of A. limnaeus embryos. Additionally, we do not find evidence for mitochondrial degradation or biogenesis during anoxia/reoxygenation treatment in A. limnaeus embryos, suggesting that anoxia-tolerant mitochondria do not respond to anoxia in a manner similar to anoxia-sensitive mitochondria.

  11. Physiological responses to hypoxia and anoxia in Balanus amphitrite (Cirripedia: Thoracica)

    Digital Repository Service at National Institute of Oceanography (India)

    Desai, D.V.; Prakash, S.

    (hypoxia) and no oxygen (anoxia) on B. amphitrite adults and nauplii was assessed. Their response was evaluated by estimating the levels of the antioxidant enzymes catalase and superoxide dismutase. The impact of desiccation on antioxidant enzymes in adult...

  12. Ocean anoxia did not cause the Latest Permian Extinction

    Science.gov (United States)

    Proemse, Bernadette C.; Grasby, Stephen E.; Wieser, Michael E.; Mayer, Bernhard; Beauchamp, Benoit

    2014-05-01

    The Latest Permian Extinction (LPE, ~252 million years ago) was a turning point in the history of life on Earth with a loss of ~96% of all marine species and ~70% of all terrestrial species. While, the event undoubtedly shaped the evolution of life its cause remains enigmatic. A leading hypothesis is that the global oceans became depleted in oxygen (anoxia). In order to test this hypothesis we investigated a proxy for marine oxygen levels (molybdenum isotopic composition) in shale across the LPE horizon located on the subtropical northwest margin of Pangea at that time. We studied two sedimentary records in the Sverdrup basin, Canadian High Arctic: Buchanan Lake (eastern Axel Heiberg Island; 79° 26.1'N, 87° 12.6'W), representing a distal deep-water slope environment, and West Blind Fiord (southwest Ellesmere Island; 78° 23.9'N, 85° 57.2'W), representing a deep outer shelf environment (below storm wave base). The molybdenum isotopic composition (δ98/95Mo) of sediments has recently become a powerful tool as a paleo-oceanographic proxy of marine oxygen levels. Sample preparation was carried out in a metal-free clean room facility in the isotope laboratory of the Department of Physics and Astronomy, University of Calgary, Canada, that is supplied by HEPA-filtered air. Molybdenum isotope ratios were determined on a Thermo Scientific multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) with an uncertainty better than ±0.10o for δ98/95Mo values. Results from the Buchanan Lake section show a large shift in δ98/95Mo values from 2.02o to +2.23o at the extinction horizon, consistent with onset of euxinic conditions. In contrast, West Blind Fiord shales, representing the sub-storm wave base shelf environment, show little change in the molybdenum isotopic composition (1.34o to +0.05), indicating ongoing oxic conditions across the LPE (Proemse et al., 2013). Our results suggest that areas of the Pangea continental shelf (North West Pangea) experienced

  13. Environmental and Genetic Preconditioning for Long-Term Anoxia Responses Requires AMPK in Caenorhabditis elegans

    OpenAIRE

    LaRue, Bobby L.; Padilla, Pamela A

    2011-01-01

    Background Preconditioning environments or therapeutics, to suppress the cellular damage associated with severe oxygen deprivation, is of interest to our understanding of diseases associated with oxygen deprivation. Wildtype C. elegans exposed to anoxia enter into a state of suspended animation in which energy-requiring processes reversibly arrest. C. elegans at all developmental stages survive 24-hours of anoxia exposure however, the ability of adult hermaphrodites to survive three days of a...

  14. Influence of short anoxia treatment and maturity on quality and storage life of tomatoes

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    Mojević Mirjana V.

    2011-01-01

    Full Text Available The influence of short anoxia treatment on physical, chemical and sensory attributes of mature green and pink red tomatoes during storage was investigated. Matured green and pink red fruits were kept for 24 hrs under humidified pure N2, while the control was not treated. Subsequently, the fruits were stored at 12°C and 20°C for 14 days. Quality parameters including weight loss, firmness, total soluble solids, colour, sensory and decay were analyzed. Generally, weight loss increased after 14 days of storage and depending on anoxia treatment, maturity and storage temperature. Tomato fruit treated with anoxia and kept at 12°C showed a minimal deterioration of the quality attributes and could be stored for longer periods compared to those stored at 20°C. Results for TSS were higher in tomato fruit treated with anoxia. However, pink red fruit stored at 20°C showed lower TSS than untreated fruit. Untreated and anoxia-pretreated mature green tomatoes showed higher sourness and off-flavour scores than those stored at 20°C. However, mature green and pink red tomatoes kept at 20°C showed higher acceptance (% than those stored at 12°C. Therefore, combined effect of anoxia and low temperature could have delayed the ripening of the tomatoes.

  15. Environmental and genetic preconditioning for long-term anoxia responses requires AMPK in Caenorhabditis elegans.

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    Bobby L LaRue

    Full Text Available BACKGROUND: Preconditioning environments or therapeutics, to suppress the cellular damage associated with severe oxygen deprivation, is of interest to our understanding of diseases associated with oxygen deprivation. Wildtype C. elegans exposed to anoxia enter into a state of suspended animation in which energy-requiring processes reversibly arrest. C. elegans at all developmental stages survive 24-hours of anoxia exposure however, the ability of adult hermaphrodites to survive three days of anoxia significantly decreases. Mutations in the insulin-like signaling receptor (daf-2 and LIN-12/Notch (glp-1 lead to an enhanced long-term anoxia survival phenotype. METHODOLOGY/PRINCIPAL FINDINGS: In this study we show that the combined growth environment of 25°C and a diet of HT115 E. coli will precondition adult hermaphrodites to survive long-term anoxia; many of these survivors have normal movement after anoxia treatment. Animals fed the drug metformin, which induces a dietary-restriction like state in animals and activates AMPK in mammalian cell culture, have a higher survival rate when exposed to long-term anoxia. Mutations in genes encoding components of AMPK (aak-2, aakb-1, aakb-2, aakg-2 suppress the environmentally and genetically induced long-term anoxia survival phenotype. We further determine that there is a correlation between the animals that survive long-term anoxia and increased levels of carminic acid staining, which is a fluorescent dye that incorporates in with carbohydrates such as glycogen. CONCLUSIONS/SIGNIFICANCE: We conclude that small changes in growth conditions such as increased temperature and food source can influence the physiology of the animal thus affecting the responses to stress such as anoxia. Furthermore, this supports the idea that metformin should be further investigated as a therapeutic tool for treatment of oxygen-deprived tissues. Finally, the capacity for an animal to survive long bouts of severe oxygen

  16. Structural and functional responses of harpacticoid copepods to anoxia in the Northern Adriatic: an experimental approach

    Science.gov (United States)

    De Troch, M.; Roelofs, M.; Riedel, B.; Grego, M.

    2013-06-01

    Combined in situ and laboratory studies were conducted to document the effects of anoxia on the structure and functioning of meiobenthic communities, with special focus on harpacticoid copepods. In a first step, anoxia was created artificially by means of an underwater chamber at 24 m depth in the Northern Adriatic, Gulf of Trieste (Mediterranean). Nematodes were found as the most abundant taxon, followed by harpacticoid copepods. While nematode densities were not affected by treatment (anoxia/normoxia) or sediment depth, these factors had a significant impact on copepod abundances. Harpacticoid copepod family diversity, in contrast, was not affected by anoxic conditions, only by depth. Ectinosomatidae and Cletodidae were most abundant in both normoxic and anoxic samples. The functional response of harpacticoid copepods to anoxia was studied in a laboratory tracer experiment by adding 13C pre-labelled diatoms to sediment cores in order to test (1) if there is a difference in food uptake by copepods under normoxic and anoxic conditions and (2) whether initial (normoxia) feeding of harpacticoid copepods on diatoms results in a better survival of copepods in subsequent anoxic conditions. Independent of the addition of diatoms, there was a higher survival rate in normoxia than anoxia. The supply of additional food did not result in a higher survival rate of copepods in anoxia, which might be explained by the presence of a nutritionally better food source and/or a lack of starvation before adding the diatoms. However, there was a reduced grazing pressure by copepods on diatoms in anoxic conditions. This resulted in a modified fatty acid composition of the sediment. We concluded that anoxia not only impacts the survival of consumers (direct effect) but also of primary producers (indirect effect), with important implications for the recovery phase.

  17. Structural and functional responses of harpacticoid copepods to anoxia in the Northern Adriatic: an experimental approach

    Directory of Open Access Journals (Sweden)

    M. De Troch

    2013-02-01

    Full Text Available Combined in situ and laboratory studies were conducted to document the effects of anoxia on the structure and functioning of meiobenthic communities, with special focus on harpacticoid copepods. In a first step, anoxia was created artificially by means of an underwater chamber at 24 m depth in the Northern Adriatic, Gulf of Trieste (Mediterranean. Nematodes were found as most abundant taxon, followed by harpacticoid copepods. While nematode densities were not affected by treatment (anoxia/normoxia or sediment depth, these factors had a significant impact on copepod abundances. Harpacticoid copepod family diversity, in contrast, was not affected by anoxic conditions, only by depth. Ectinosomatidae and Cletodidae were most abundant in both normoxic and anoxic samples. The functional response of harpacticoid copepods to anoxia was studied in a laboratory tracer experiment by adding 13C pre-labelled diatoms to sediment cores in order to test (1 if there is a difference in food uptake by copepods under normoxic and anoxic conditions and (2 whether initial (normoxia feeding of harpacticoid copepods on diatoms results in a better survival of copepods in subsequent anoxic conditions. Independent of the addition of diatoms, there was a higher survival rate in normoxia than anoxia. The supply of additional food did not result in a higher survival rate of copepods in anoxia, which might be explained by the presence of a nutritionally better food source and/or a lack of starvation before adding the diatoms. However, there was a reduced grazing pressure by copepods on diatoms in anoxic conditions. This resulted in a modified fatty acid composition of the sediment. We concluded that anoxia not only impacts the survival of consumers (direct effect but also of primary producers (indirect effect, with important implications for the recovery phase.

  18. Structural and functional responses of harpacticoid copepods to anoxia in the Northern Adriatic: an experimental approach

    Directory of Open Access Journals (Sweden)

    M. De Troch

    2013-06-01

    Full Text Available Combined in situ and laboratory studies were conducted to document the effects of anoxia on the structure and functioning of meiobenthic communities, with special focus on harpacticoid copepods. In a first step, anoxia was created artificially by means of an underwater chamber at 24 m depth in the Northern Adriatic, Gulf of Trieste (Mediterranean. Nematodes were found as the most abundant taxon, followed by harpacticoid copepods. While nematode densities were not affected by treatment (anoxia/normoxia or sediment depth, these factors had a significant impact on copepod abundances. Harpacticoid copepod family diversity, in contrast, was not affected by anoxic conditions, only by depth. Ectinosomatidae and Cletodidae were most abundant in both normoxic and anoxic samples. The functional response of harpacticoid copepods to anoxia was studied in a laboratory tracer experiment by adding 13C pre-labelled diatoms to sediment cores in order to test (1 if there is a difference in food uptake by copepods under normoxic and anoxic conditions and (2 whether initial (normoxia feeding of harpacticoid copepods on diatoms results in a better survival of copepods in subsequent anoxic conditions. Independent of the addition of diatoms, there was a higher survival rate in normoxia than anoxia. The supply of additional food did not result in a higher survival rate of copepods in anoxia, which might be explained by the presence of a nutritionally better food source and/or a lack of starvation before adding the diatoms. However, there was a reduced grazing pressure by copepods on diatoms in anoxic conditions. This resulted in a modified fatty acid composition of the sediment. We concluded that anoxia not only impacts the survival of consumers (direct effect but also of primary producers (indirect effect, with important implications for the recovery phase.

  19. Marine anoxia and delayed Earth system recovery after the end-Permian extinction.

    Science.gov (United States)

    Lau, Kimberly V; Maher, Kate; Altiner, Demir; Kelley, Brian M; Kump, Lee R; Lehrmann, Daniel J; Silva-Tamayo, Juan Carlos; Weaver, Karrie L; Yu, Meiyi; Payne, Jonathan L

    2016-03-01

    Delayed Earth system recovery following the end-Permian mass extinction is often attributed to severe ocean anoxia. However, the extent and duration of Early Triassic anoxia remains poorly constrained. Here we use paired records of uranium concentrations ([U]) and (238)U/(235)U isotopic compositions (δ(238)U) of Upper Permian-Upper Triassic marine limestones from China and Turkey to quantify variations in global seafloor redox conditions. We observe abrupt decreases in [U] and δ(238)U across the end-Permian extinction horizon, from ∼3 ppm and -0.15‰ to ∼0.3 ppm and -0.77‰, followed by a gradual return to preextinction values over the subsequent 5 million years. These trends imply a factor of 100 increase in the extent of seafloor anoxia and suggest the presence of a shallow oxygen minimum zone (OMZ) that inhibited the recovery of benthic animal diversity and marine ecosystem function. We hypothesize that in the Early Triassic oceans-characterized by prolonged shallow anoxia that may have impinged onto continental shelves-global biogeochemical cycles and marine ecosystem structure became more sensitive to variation in the position of the OMZ. Under this hypothesis, the Middle Triassic decline in bottom water anoxia, stabilization of biogeochemical cycles, and diversification of marine animals together reflect the development of a deeper and less extensive OMZ, which regulated Earth system recovery following the end-Permian catastrophe. PMID:26884155

  20. BH3 Mimetics Reactivate Autophagic Cell Death in Anoxia-Resistant Malignant Glioma Cells

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    Holger Hetschko

    2008-08-01

    Full Text Available Here, we investigated the specific roles of Bcl-2 family members in anoxia tolerance of malignant glioma. Flow cytometry analysis of cell death in 17 glioma cell lines revealed drastic differences in their sensitivity to oxygen withdrawal (<0.1% O2. Cell death correlated with mitochondrial depolarization, cytochrome C release, and translocation of green fluorescent protein (GFP-tagged light chain 3 to autophagosomes but occurred in the absence of caspase activation or phosphatidylserine exposure. In both sensitive and tolerant glioma cell lines, anoxia caused a significant up-regulation of BH3-only genes previously implicated in mediating anoxic cell death in other cell types (BNIP3, NIX, PUMA, and Noxa. In contrast, we detected a strong correlation between anoxia resistance and high expression levels of antiapoptotic Bcl-2 family proteins Bcl-xL, Bcl-2, and Mcl-1 that function to neutralize the proapoptotic activity of BH3-only proteins. Importantly, inhibition of both Bcl-2 and Bcl-xL with the small-molecule BH3 mimetics HA14-1 and BH3I-2′ and by RNA interference reactivated anoxia-induced autophagic cell death in previously resistant glioma cells. Our data suggest that endogenous BH3-only protein induction may not be able to compensate for the high expression of antiapoptotic Bcl-2 family proteins in anoxia-resistant astrocytomas. They also support the conjecture that BH3 mimetics may represent an exciting new approach for the treatment of malignant glioma.

  1. Opening Pandora's Box: The impact of open system modeling on interpretations of anoxia

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    Hotinski, Roberta M.; Kump, Lee R.; Najjar, Raymond G.

    2000-06-01

    The geologic record preserves evidence that vast regions of ancient oceans were once anoxic, with oxygen levels too low to sustain animal life. Because anoxic conditions have been postulated to foster deposition of petroleum source rocks and have been implicated as a kill mechanism in extinction events, the genesis of such anoxia has been an area of intense study. Most previous models of ocean oxygen cycling proposed, however, have either been qualitative or used closed-system approaches. We reexamine the question of anoxia in open-system box models in order to test the applicability of closed-system results over long timescales and find that open and closed-system modeling results may differ significantly on both short and long timescales. We also compare a scenario with basinwide diffuse upwelling (a three-box model) to a model with upwelling concentrated in the Southern Ocean (a four-box model). While a three-box modeling approach shows that only changes in high-latitude convective mixing rate and character of deepwater sources are likely to cause anoxia, four-box model experiments indicate that slowing of thermohaline circulation, a reduction in wind-driven upwelling, and changes in high-latitude export production may also cause dysoxia or anoxia in part of the deep ocean on long timescales. These results suggest that box models must capture the open-system and vertically stratified nature of the ocean to allow meaningful interpretations of long-lived episodes of anoxia.

  2. Oxygen sensing neurons and neuropeptides regulate survival after anoxia in developing C. elegans.

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    Flibotte, John J; Jablonski, Angela M; Kalb, Robert G

    2014-01-01

    Hypoxic brain injury remains a major source of neurodevelopmental impairment for both term and preterm infants. The perinatal period is a time of rapid transition in oxygen environments and developmental resetting of oxygen sensing. The relationship between neural oxygen sensing ability and hypoxic injury has not been studied. The oxygen sensing circuitry in the model organism C. elegans is well understood. We leveraged this information to investigate the effects of impairments in oxygen sensing on survival after anoxia. There was a significant survival advantage in developing worms specifically unable to sense oxygen shifts below their preferred physiologic range via genetic ablation of BAG neurons, which appear important for conferring sensitivity to anoxia. Oxygen sensing that is mediated through guanylate cyclases (gcy-31, 33, 35) is unlikely to be involved in conferring this sensitivity. Additionally, animals unable to process or elaborate neuropeptides displayed a survival advantage after anoxia. Based on these data, we hypothesized that elaboration of neuropeptides by BAG neurons sensitized animals to anoxia, but further experiments indicate that this is unlikely to be true. Instead, it seems that neuropeptides and signaling from oxygen sensing neurons operate through independent mechanisms, each conferring sensitivity to anoxia in wild type animals.

  3. Anoxia- and hypoxia-induced expression of LDH-A* in the Amazon Oscar, Astronotus crassipinis

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    Vera Maria Fonseca Almeida-Val

    2011-01-01

    Full Text Available Adaptation or acclimation to hypoxia occurs via the modulation of physiologically relevant genes, such as erythropoietin, transferrin, vascular endothelial growth factor, phosphofructokinase and lactate dehydrogenase A. In the present study, we have cloned, sequenced and examined the modulation of the LDH-A gene after an Amazonian fish species, Astronotus crassipinis (the Oscar, was exposed to hypoxia and anoxia. In earlier studies, we have discovered that adults of this species are extremely tolerant to hypoxia and anoxia, while the juveniles are less tolerant. Exposure of juveniles to acute hypoxia and anoxia resulted in increased LDH-A gene expression in skeletal and cardiac muscles. When exposed to graded hypoxia juveniles show decreased LDH-A expression. In adults, the levels of LDH-A mRNA did not increase in hypoxic or anoxic conditions. Our results demonstrate that, when given time for acclimation, fish at different life-stages are able to respond differently to survive hypoxic episodes.

  4. Linear and nonlinear heart-rate analysis in a rat model of acute anoxia

    International Nuclear Information System (INIS)

    The objective of this study was the assessment of heart-rate (HR) dynamics with linear and nonlinear methods during episodes of mechanical ventilation and acute anoxia in rats. Namely, to assess whether linear and nonlinear HR analysis was able to discriminate acute anoxia from baseline in rats and if this was consistent with human foetal and adult studies. Five HR segments of 1 min duration, during baseline recording, mechanical ventilation and first, second and third minutes of induced acute anoxia, were analysed in ten adult Wistar rats. Linear time and frequency domain and nonlinear methods were used, namely mean HR (mHR), long-term irregularity (LTI), interval index (II), low frequency (LF) and high frequency (HF), approximate entropy (ApEn) and sample entropy (SampEn). New parameters for the entropy indices are proposed for the analysis of rats' HR. Bootstrap percentile confidence intervals and nonparametric statistical tests were used in the evaluation of the differences between segments. During mechanical ventilation a clear spectral band was detectable at the ventilation rate, but mHR, II and the 'new' entropy indices were the only significantly changed indices. In the transition from baseline–mechanical-ventilation to mechanical-ventilation–induced anoxia, a statistically significant decrease of mHR, II and entropy indices was observed, clearly discriminating these two instances, whereas most linear indices increased. With continued anoxia, most linear indices decreased significantly, whereas entropy remained stably low. These results are consistent with other foetal human and non-human studies and evidence that the rat model may be used for further research on linear and nonlinear analysis of heart-rate dynamics. The transition from baseline to acute anoxia was encompassed by signs of increased activation of the autonomic nervous system sympathetic branch, and decreased or blunted activity of the HR complexity regulatory centres

  5. Isoflurane preserves energy balance in isolated hepatocytes during in vitro anoxia/reoxygenation

    Institute of Scientific and Technical Information of China (English)

    Quan Li; Wei-Feng Yu; Mai-Tao Zhou; Xin Lu; Li-Qun Yang; Ming Zhu; Jian-Gang Song; Jun-Hua Lu

    2005-01-01

    AIM: To investigate the protective effect of isoflurane on energy balance in isolated hepatocytes during in vitro anoxia/reoxygenation, and to compare isoflurane with halothane.METHODS: Hepatocytes freshly isolated from fed rats were suspended in Krebs-Henseleit buffer, and incubated in sealed flasks under O2/CO2 or N2/CO2 (95%/5%, V/V)for 30 or 60 min, followed by 5 or 10 min of reoxygenation,with an added volatile anesthetic or not. ATP, ADP, and adenosine monophosphate in hepatocytes were determined by high performance liquid chromatography, and energy charge was calculated.RESULTS: During 30 min of anoxia, the energy charge and total adenine nucleotide steadily increased with the isoflurane dose from 0 to 2 minimum alveolar anesthetic concentration (MAC), then decreased from 2 to 3 MAC.In short incubations (30-35 min) at 1 MAC isoflurane, energy charge modestly decreased during anoxia, which was partially prevented by isoflurane and completely reversed by reoxygenation, and total adenine nucleotide did not decrease. In long incubations (60-70 min), both energy charge and total adenine nucleotide greatly decreased during anoxia, with partial and no reversal by reoxygenation,respectively. Isoflurane partly prevented decreases in both energy charge and total adenine nucleotide during anoxia and reoxygenation. In addition, 1 MAC isoflurane obviously increased ATP/ADP, which could not be changed by 1MAC halothane.CONCLUSION: Isoflurane partially protects isolated hepatocytes against decreases in both energy charge and total adenine nucleotide during short (reversible) or long (irreversible) anoxia.

  6. Tribute to P.L. Lutz: cardiac performance and cardiovascular regulation during anoxia/Hypoxia in freshwwater turtles

    DEFF Research Database (Denmark)

    Overgaard, J.; Gesser, Hans; Wang, Tobias

    2007-01-01

    . The pronounced anoxia tolerance of the turtle heart is based on the ability to match energy consumption with the low anaerobic ATP production during anoxia. Together with a well-developed temporal and spatial energy buffering by creatine kinase, this allows for cellular energy charge to remain high...

  7. Physiological, biochemical, and morphological characteristics of myocardial anoxia: the use of a semi-perfusion canine preparation.

    Science.gov (United States)

    Bornet, E P; Wood, J M; Goldstein, M A; Entman, M L; Lewis, R M; Dunn, F A; Schwartz, A

    1977-11-01

    Regional myocardial anoxia was produced in dogs by perfusion of the left circumflex artery (LCA) with deoxygenated blood. Isolated sarcoplasmic reticulum fragments (cardiac relaxing system) showed decreased Ca2+ binding and uptake. The ability of isolated mitochondria to utilise long-chain fatty acids was markedly reduced. This model has revealed inherent biochemical differences between ischaemia and anoxia. PMID:603880

  8. Response of the Ubiquitous Pelagic Diatom Thalassiosira weissflogii to Darkness and Anoxia

    DEFF Research Database (Denmark)

    Kamp, Anja; Stief, Peter; Knappe, Jan;

    2013-01-01

    rather than assimilatory pathway. Nitrite and the greenhouse gas nitrous oxide were produced at rates 2-3 orders of magnitude lower than the ammonium production rate. While DNRA activity was restricted to the first few hours of darkness and anoxia, the subsequent degradation of photopigments took weeks...... to months, supporting the earlier finding that diatoms resume photosynthesis even after extended exposure to darkness and anoxia. Considering the high global abundance of T. weissflogii, its production of ammonium and nitrous oxide might be of ecological importance for oceanic oxygen minimum zones...

  9. Effects of postnatal anoxia on striatal dopamine metabolism and prepulse inhibition in rats

    DEFF Research Database (Denmark)

    Sandager-Nielsen, Karin; Andersen, Maibritt B; Sager, Thomas N;

    2004-01-01

    . Anoxia was experimentally induced by placing 9-day-old rat pups for 6 min in a chamber saturated with 100% nitrogen (N(2)). Exposure to anoxia on postnatal day (PND) 9 resulted in significantly reduced subcortical dopamine metabolism and turnover, as measured by striatal 3,4-dihydroxyphenylacetic acid...... (DOPAC) and homovanillic acid (HVA) concentrations. Furthermore, in the anoxic group only, striatal HVA concentrations were negatively correlated to prefrontal cortical N-acetylaspartate (NAA) levels. Similar findings of distorted prefrontal-subcortical interactions have recently been reported...

  10. Comparison of two anoxia models in rainbow trout cells by a 2-DE and MS/MS-based proteome approach

    DEFF Research Database (Denmark)

    Wulff, Tune; Hoffmann, E.K.; Roepstorff, P.;

    2008-01-01

    In the literature, a variety of ways have been used to obtain anoxia, and most often results are compared between studies without taking into consideration how anoxia has been obtained. Here, we provide a comprehensive study of two types of anoxia, using a proteomics approach to compare changes...... in protein expression. The two investigated situations were 30 min of chemical anoxia (10 mM NaN3) followed by reoxygenation overnight (CR) and 2 h of N-2-induced anoxia (achieved by flushing with N-2) followed by reoxygenation. overnight (NR), after which samples were resolved by 2-DE. Forty-five protein...... spots changed their abundance in response to CR and 35 protein spots changed their abundance in response to NR, but only six proteins changed their abundance in response to both stimuli. By the means of MS/MS, 40 protein spots were identified including proteins involved in processes like cell protection...

  11. Deoxidant-induced anoxia as a physical measure for controlling spider mites (Acari: Tetranychidae).

    Science.gov (United States)

    Suzuki, Takeshi; Wang, Chih-Hung; Gotoh, Tetsuo; Amano, Hiroshi; Ohyama, Katsumi

    2015-03-01

    Tiny agricultural pests such as spider mites (Acari: Tetranychidae) attached to seedlings grown outdoors often invade greenhouses, thereby triggering pest outbreaks. To solve the problem, we examined whether differences in anoxia tolerance between animals and plants would permit the application of an anoxic environment to control spider mites without the aid of acaricides. Under an anoxic environment created by using a commercial deoxidant at 25 °C, the time for 50 % mortality of eggs, non-diapausing adults (summer form), and diapausing adults (winter form) were 6.1, 5.5, and 23.6 h, respectively, for Tetranychus urticae Koch and 5.4, 3.9, and 23.2 h, respectively, for Tetranychus kanzawai Kishida. With anoxia for 12 h, no eggs and non-diapausing adults survived in either species, whereas most diapausing adults (98 % for T. urticae and 88 % for T. kanzawai) survived. Under this treatment, host Phaseolus vulgaris L. seedlings showed serious physiological disorders in their primary leaves and apical buds, and unusual lateral buds developed in the cotyledon axils. The spider mites acquire anoxia tolerance during diapause, but anoxia can potentially control them during the summer if no negative effects are observed in the treated seedlings.

  12. Conversion of phosphoenolpyruvate in Venus gallina and Scapharca inaequivalvis at anoxia stress I. Time dependency

    NARCIS (Netherlands)

    De Zwaan, A.; Isani, G.; Cortesi, P.; Cattani, O.; Putzer, V.M.

    1993-01-01

    1. 1. The origin of carbon incorporated in succinate in the first 12 hr of environmental anoxia was studied in two bivalve species of the Northern Adriatic Sea. 2. 2. Posterior adductor muscles were excised after various periods of exposure to anoxic seawater and incubated under nitrogen in the pres

  13. Prolonged and recurrent global seafloor anoxia in the Early Triassic from uranium isotopic evidence

    Science.gov (United States)

    Lau, K. V.; Maher, K.; Kelley, B. M.; Yu, M.; Lehrmann, D. J.; Payne, J.

    2013-12-01

    The end-Permian extinction and prolonged Early Triassic recovery of marine ecosystems have been attributed in part to marine anoxia. However, the spatial and temporal extent of anoxic waters during Early Triassic time remains poorly understood. To better constrain the evolution of seawater conditions, we present a record of δ238/235U and uranium concentrations collected from the Great Bank of Guizhou, a Late Permian to Late Triassic isolated carbonate platform in the Nanpanjiang Basin, South China. The isotopic composition and concentration of uranium are independent constraints on paleoredox conditions and can be used as indicators for the global extent of ocean anoxia. Our δ238/235U results demonstrate that two large negative excursions of up to ~-0.4‰ occurred in the Induan and in the Spathian, before stabilizing in the Middle Triassic at Late Permian values. Uranium concentrations mirror the isotopic trends, reaching sustained minima of less than 0.2 ppm that correspond to the most negative isotopic values. By placing these observational constraints on a box model of the geological uranium cycle, we calculate that up to half of the continental shelves may have been affected during the two pulses of bottom-water anoxia. The expansion, contraction, and re-expansion of extreme low-oxygen conditions could explain many unresolved aspects of the prolonged recovery of marine ecosystems. The recurrence of widespread anoxia during Spathian time may have interrupted the recovery of marine organisms that began in the more oxic waters of the Smithian. These episodes of significant and prolonged bottom-water anoxia coincide with the most negative δ13C values, suggesting that Early Triassic perturbations to the global carbon cycle were tightly coupled to changes in ocean redox chemistry.

  14. Glucose-6-Phosphate Dehydrogenase Regulation in Anoxia Tolerance of the Freshwater Crayfish Orconectes virilis

    Directory of Open Access Journals (Sweden)

    Benjamin Lant

    2011-01-01

    Full Text Available Glucose-6-phosphate dehydrogenase (G6PDH, the enzyme which catalyzes the rate determining step of the pentose phosphate pathway (PPP, controls the production of nucleotide precursor molecules (R5P and powerful reducing molecules (NADPH that support multiple biosynthetic functions, including antioxidant defense. G6PDH from hepatopancreas of the freshwater crayfish (Orconectes virilis showed distinct kinetic changes in response to 20 h anoxic exposure. Km values for both substrates decreased significantly in anoxic crayfish; Km NADP+ dropped from 0.015±0.008 mM to 0.012±0.008 mM, and Km G6P decreased from 0.13±0.02 mM to 0.08±0.007 mM. Two lines of evidence indicate that the mechanism involved is reversible phosphorylation. In vitro incubations that stimulated protein kinase or protein phosphatase action mimicked the effects on anoxia on Km values, whereas DEAE-Sephadex chromatography showed the presence of two enzyme forms (low- and high-phosphate whose proportions changed during anoxia. Incubation studies implicated protein kinase A and G in mediating the anoxia-responsive changes in G6PDH kinetic properties. In addition, the amount of G6PDH protein (measured by immunoblotting increased by ∼60% in anoxic hepatopancreas. Anoxia-induced phosphorylation of G6PDH could contribute to modifying carbon flow through the PPP under anoxic conditions, potentially maintaining NADPH supply for antioxidant defense during prolonged anoxia-induced hypometabolism.

  15. Carbohydrate metabolism in germinating caryopses of Oryza sativa L. exposed to prolonged anoxia.

    Science.gov (United States)

    Pompeiano, Antonio; Guglielminetti, Lorenzo

    2016-09-01

    Anoxia tolerance can be evaluated not only in terms of growth or survival of plant organs during oxygen deprivation, but also in relation to carbohydrate utilization in the context of a well-modulated fermentative metabolism. Rice (Oryza spp.) is unique among cereals, in that it has the distinctive ability to germinate under complete anaerobiosis by using the starchy reserves in its seeds to fuel the anaerobic metabolism. The aim of the present study was to evaluate the ability of germinating rice seedlings to survive a long-term oxygen deficiency [40 days after sowing (DAS)] and the effects on sugar metabolism, focusing on starch degradation as well as soluble sugars transport and storage under anoxia. No significant decline in vitality occurred until 30 DAS though no recovery was detected following longer anoxic treatments. Growth arrest was observed following anoxic treatments longer that 20 DAS, in concomitance with considerably lower ethanol production. Amylolytic activity in embryos and endosperms had similar responses to anoxia, reaching maximum content 30 days after the onset of stress, following which the levels declined for the remainder of the experiment. Under anoxia, average amylolytic activity was twofold higher in embryos than endosperms. Efficient starch degradation was observed in rice under anoxia at the onset of the treatment but it decreased over time and did not lead to a complete depletion. Our analysis of α-amylase activity did not support the hypothesis that starch degradation plays a critical role in explaining differences in vitality and coleoptile growth under prolonged oxygen deprivation. PMID:27289587

  16. Effects of β₂-agonists on force during and following anoxia in rat extensor digitorum longus muscle

    DEFF Research Database (Denmark)

    Fredsted, A; Gissel, H; Ortenblad, N;

    2012-01-01

    and K(+) content indicating stimulation of the Na(+),K(+) - pumps. In fatigued muscles salbutamol induced recovery of excitability. Thus, β(2)-agonists reduce the anoxia-induced loss of force leading to partial force recovery. These data strongly suggest that this effect is mediated by cAMP stimulation......Electrical stimulation of isolated muscles may lead to membrane depolarization, gain of Na(+), loss of K(+) and fatigue. These effects can be counteracted with β(2)-agonists possibly via activation of the Na(+),K(+)- pumps. Anoxia induces loss of force; however, it is not known whether β(2...... stimulation (15-30 min) clearly increased loss of force during anoxia and reduced force recovery during reoxygenation. The β(2)-agonists salbutamol (10(-7) - 10(-5) M) and salmeterol (10(-6) M) improved force development during anoxia (25%) and force recovery during reoxygenation (55-262%). The effects...

  17. Circulating nitric oxide metabolites and cardiovascular changes in the turtle Trachemys scripta during normoxia, anoxia and reoxygenation

    DEFF Research Database (Denmark)

    Jacobsen, Søren B.; Hansen, Marie Niemann; Jensen, Frank Bo;

    2012-01-01

    Turtles of the genus Trachemys show a remarkable ability to survive prolonged anoxia. This is achieved by a strong metabolic depression, redistribution of blood flow and high levels of antioxidant defence. To understand whether nitric oxide (NO), a major regulator of vasodilatation and oxygen...... consumption, may be involved in the adaptive response of Trachemys to anoxia, we measured NO metabolites (nitrite, S-nitroso, Fe-nitrosyl and N-nitroso compounds) in the plasma and red blood cells of venous and arterial blood of Trachemys scripta turtles during normoxia and after anoxia (3 h......-nitroso compounds were present at high micromolar levels under normoxia and increased further after anoxia and reoxygenation, suggesting NO generation from nitrite catalysed by deoxygenated haemoglobin, which in turtle had a higher nitrite reductase activity than in hypoxia-intolerant species. Taken together...

  18. Commercially Available Gas-Permeable Cell Culture Bags May Not Prevent Anoxia in Cultured or Shipped Islets

    OpenAIRE

    Avgoustiniatos, E.S.; Hering, B.J.; Rozak, P.R.; Wilson, J.R.; Tempelman, L.A.; Balamurugan, A.N.; Welch, D.P.; Weegman, B. P.; Suszynski, T.M.; Papas, K.K.

    2008-01-01

    Prolonged anoxia has deleterious effects on islets. Gas-permeable cell culture devices can be used to minimize anoxia during islet culture and especially during shipment when elimination of gas-liquid interfaces is required to prevent the formation of damaging gas bubbles. Gas-permeable bags may have several drawbacks, such as propensity for puncture and contamination, difficult islet retrieval, and significantly lower oxygen permeability than silicone rubber membranes (SRM). We hypothesized ...

  19. Chondrites isp. Indicating Late Paleozoic Atmospheric Anoxia in Eastern Peninsular India

    Directory of Open Access Journals (Sweden)

    Biplab Bhattacharya

    2014-01-01

    Full Text Available Rhythmic sandstone-mudstone-coal succession of the Barakar Formation (early Permian manifests a transition from lower braided-fluvial to upper tide-wave influenced, estuarine setting. Monospecific assemblage of marine trace fossil Chondrites isp. in contemporaneous claystone beds in the upper Barakar succession from two Gondwana basins (namely, the Raniganj Basin and the Talchir Basin in eastern peninsular India signifies predominant marine incursion during end early Permian. Monospecific Chondrites ichnoassemblage in different sedimentary horizons in geographically wide apart (~400 km areas demarcates multiple short-spanned phases of anoxia in eastern India. Such anoxia is interpreted as intermittent falls in oxygen level in an overall decreasing atmospheric oxygenation within the late Paleozoic global oxygen-carbon dioxide fluctuations.

  20. The first case of anoxia in waters of the Far East Marine Biosphere Reserve

    Science.gov (United States)

    Stunzhas, P. A.; Tishchenko, P. Ya.; Ivin, V. V.; Barabanshchikov, Yu. A.; Volkova, T. I.; Vyshkvartsev, D. I.; Zvalinskii, V. I.; Mikhailik, T. A.; Semkin, P. Ju.; Tishchenko, P. P.; Khodorenko, N. D.; Shvetsova, M. G.; Golovchenko, F. M.

    2016-03-01

    In August 2013, anoxia of the bottom waters was established in the southern region of the Far East Marine Biosphere Reserve, Far East Branch, Russian Academy of Science, in the depression between Furugelm Island and coastal waters. Death of the benthic community was registered using a remotely operated underwater vehicle. The hydrochemical studies revealed that the area of the absence and/or presence of low oxygen contents corresponds to an area of anomalously high contents of ammonium, phosphates, and silicates, a high partial pressure of carbon dioxide and normalized alkalinity, and the presence of hydrogen sulfide. The microbiological decomposition of diatoms precipitated on the seafloor in the absence of oxygen regeneration was the reason for anoxia. Its formation in summer of 2013 was caused by anomalously abundant precipitates in the Far East.

  1. Effects of anoxia on 31P NMR spectra of Phycomyces blakesleeanus during development

    Directory of Open Access Journals (Sweden)

    Stanić Marina

    2009-01-01

    Full Text Available The method of 31P NMR spectroscopy was used to investigate the effects of anoxia on Phycomyces blakesleea­nus mycelium during development. The greatest changes were recorded in the PPc, NADH, and α-ATP signals. Decrease of PPc signal intensity is due to chain length reduction and reduction in number of PPn molecules. Smaller decrease of β-ATP compared to α-ATP signal intensity can be attributed to maintenance of ATP concentration at the expense of PPn hydrolysis. Sensitivity to anoxia varies with the growth stage. It is greatest in 32-h and 44-h mycelium, in which PPn is used as an additional energy source, while the smallest effect was noted for 36-h fungi.

  2. Long term anoxia in rainbow trout investigated by 2-DE and MS/MS

    DEFF Research Database (Denmark)

    Wulff, Tune; Jessen, Flemming; Roepstorff, P.;

    2008-01-01

    Twenty-four hours of N-2 induced anoxia induced global perturbations on protein expression in rainbow trout hypodermal fibroblasts cell line. Anoxia was obtained by depleting the medium of O-2 by flushing with N-2, and protein changes were studied by 2-DE coupled with MS providing quantitative...... measurements of a large number of proteins in one single study. The anoxic insult changed the level of 33 protein spots: 22 of these were up-regulated compared to the control situation and 11 were down-regulated. Using MS/MS sequencing 19 of the 33 protein spots that changed were identified, corresponding...... to a success rate of more than 50%. The identified proteins included two proteins involved in energy metabolism namely phosphoglycerate mutase and isocitrate dehydrogenase. In addition we observed the up-regulation of a cluster of proteins that contribute to cytoskeleton function. These are calpain, EB1...

  3. Human neocortical excitability is decreased during anoxia via sodium channel modulation.

    OpenAIRE

    Cummins, T R; Jiang, C.; Haddad, G G

    1993-01-01

    When the central nervous system in humans is deprived of oxygen, the effects are potentially disastrous. Electroencephalographic activity is lost and higher brain function ceases rapidly. Despite the importance of these effects, the mechanisms underlying the loss of cortical activity are poorly understood. Using intracellular recordings of human neocortical neurons in tissue slices, we show that, whereas anoxia produces a relatively small depolarization and modest alterations in passive prope...

  4. Depression of nuclear transcription and extension of mRNA half-life under anoxia in Artemia franciscana embryos.

    Science.gov (United States)

    van Breukelen, F; Maier, R; Hand, S C

    2000-04-01

    Transcriptional activity, as assessed by nuclear run-on assays, was constant during 10 h of normoxic development for embryos of the brine shrimp Artemia franciscana. Exposure of embryos to only 4 h of anoxia resulted in a 79.3+/-1 % decrease in levels of in-vivo-initiated transcripts, and transcription was depressed by 88. 2+/-0.7 % compared with normoxic controls after 24 h of anoxia (means +/- s.e.m., N=3). Initiation of transcription was fully restored after 1 h of normoxic recovery. Artificially lowering the intracellular pH of aerobic embryos to the value reflective of anoxia (pH 6.7) showed that acidification alone explained over half the transcriptional arrest. Initiation of transcription was not rescued by application of 80 % carbon monoxide under anoxia, which suggests that heme-based oxygen sensing is not involved in this global arrest. When these transcriptional data are combined with the finding that mRNA levels are unchanged for at least 6 h of anoxia, it is clear that the half-life of mRNA is extended at least 8.5-fold compared with that in aerobic embryos. In contrast to the activation of compensatory mechanisms to cope with anoxia that occurs in mammalian cells, A. franciscana embryos enter a metabolically depressed state in which gene expression and mRNA turnover are cellular costs apparently not compatible with survival and in which extended tolerance supercedes the requirement for continued metabolic function. PMID:10708633

  5. The effect of induced anoxia and reoxygenation on benthic fluxes of organic carbon, phosphate, iron, and manganese.

    Science.gov (United States)

    Skoog, Annelie C; Arias-Esquivel, Victor A

    2009-11-15

    Eutrophication causes seasonally anoxic bottom waters in coastal environments, but we lack information on effects of onset of anoxia and subsequent reoxygenation on benthic fluxes of redox-sensitive minerals and associated organic carbon (OC). As the first study, we determined the effect of inducing anoxia and subsequently restoring oxic conditions in mesocosms with surface sediment and water from a coastal environment. These concentration changes were compared with those in an oxygenated control. We determined water column concentrations of dissolved organic carbon (DOC), particulate organic carbon (POC), iron, manganese, and phosphate. Benthic fluxes of DOC, POC, and iron increased at the onset of anoxia in oxygen-depleted treatments. DOC and iron concentrations increased concomitantly towards maxima, which may have indicated reductive dissolution of FeOOH and release of associated OC. The subsequent concomitant concentration decreases may have been the result of coprecipitation of OC with iron-containing minerals. In contrast, the phosphate-concentration increase occurred several days after the onset of anoxia and the manganese concentration was not affected by the onset of anoxia. Restoring oxic conditions resulted in a decrease in DOC, POC, and phosphate concentrations, which may indicate coprecipitation of OC with phosphate-containing minerals. The high DOC fluxes at the onset of anoxia indicate that redox oscillations may be important in OC degradation. Further, our results indicate a close coupling between OC cycling and dissolution/precipitation of iron-containing minerals in intermittently anoxic sediments.

  6. Response of the ubiquitous pelagic diatom Thalassiosira weissflogii to darkness and anoxia.

    Directory of Open Access Journals (Sweden)

    Anja Kamp

    Full Text Available Thalassiosira weissflogii, an abundant, nitrate-storing, bloom-forming diatom in the world's oceans, can use its intracellular nitrate pool for dissimilatory nitrate reduction to ammonium (DNRA after sudden shifts to darkness and anoxia, most likely as a survival mechanism. T. weissflogii cells that stored 4 mM (15N-nitrate consumed 1.15 (±0.25 fmol NO3 (- cell(-1 h(-1 and simultaneously produced 1.57 (±0.21 fmol (15NH4 (+ cell(-1 h(-1 during the first 2 hours of dark/anoxic conditions. Ammonium produced from intracellular nitrate was excreted by the cells, indicating a dissimilatory rather than assimilatory pathway. Nitrite and the greenhouse gas nitrous oxide were produced at rates 2-3 orders of magnitude lower than the ammonium production rate. While DNRA activity was restricted to the first few hours of darkness and anoxia, the subsequent degradation of photopigments took weeks to months, supporting the earlier finding that diatoms resume photosynthesis even after extended exposure to darkness and anoxia. Considering the high global abundance of T. weissflogii, its production of ammonium and nitrous oxide might be of ecological importance for oceanic oxygen minimum zones and the atmosphere, respectively.

  7. Human neocortical excitability is decreased during anoxia via sodium channel modulation.

    Science.gov (United States)

    Cummins, T R; Jiang, C; Haddad, G G

    1993-02-01

    When the central nervous system in humans is deprived of oxygen, the effects are potentially disastrous. Electroencephalographic activity is lost and higher brain function ceases rapidly. Despite the importance of these effects, the mechanisms underlying the loss of cortical activity are poorly understood. Using intracellular recordings of human neocortical neurons in tissue slices, we show that, whereas anoxia produces a relatively small depolarization and modest alterations in passive properties, it causes a major decrease in excitability. Whole-cell voltage-clamp studies of acutely isolated human neocortical pyramidal neurons demonstrate that anoxia and metabolic inhibition produce a large negative shift in the steady-state inactivation [h infinity (V)] curve for the voltage-dependent sodium current (INa). Inclusion of ATP in the patch pipette decreased the shift of the h infinity (V) curve by two-thirds. Because increased inactivation of INa decreases cellular metabolic demand, we postulate that this promotes neuronal survival during periods of oxygen deprivation. These data show a novel mechanism by which anoxia links metabolism to membrane ionic conductances in human cortical neurons. PMID:8381823

  8. Forever Young: Mechanisms of Natural Anoxia Tolerance and Potential Links to Longevity

    Directory of Open Access Journals (Sweden)

    Anastasia Krivoruchko

    2010-01-01

    Full Text Available While mammals cannot survive oxygen deprivation for more than a few minutes without sustaining severe organ damage, some animals have mastered anaerobic life. Freshwater turtles belonging to the Trachemys and Chrysemys genera are the champion facultative anaerobes of the vertebrate world, often surviving without oxygen for many weeks at a time. The physiological and biochemical mechanisms that underlie anoxia tolerance in turtles include profound metabolic rate depression, post-translational modification of proteins, strong antioxidant defenses, activation of specific stress-responsive transcription factors, and enhanced expression of cyto-protective proteins. Turtles are also known for their incredible longevity and display characteristics of “negligible senescence.” We propose that the robust stress-tolerance mechanisms that permit long term anaerobiosis by turtles may also support the longevity of these animals. Many of the mechanisms involved in natural anoxia tolerance, such as hypometabolism or the induction of various protective proteins/pathways, have been shown to play important roles in mammalian oxygen-related diseases and improved understanding of how cells survive without oxygen could aid in the understanding and treatment of various pathological conditions that involve hypoxia or oxidative stress. In the present review we discuss the recent advances made in understanding the molecular nature of anoxia tolerance in turtles and the potential links between this tolerance and longevity.

  9. Effects of hypoxia, anoxia, and endogenous ethanol on thermoregulation in goldfish, Carassius auratus.

    Science.gov (United States)

    Rausch, R N; Crawshaw, L I; Wallace, H L

    2000-03-01

    Effects of hypoxia, anoxia, and endogenous ethanol (EtOH) on selected temperature (T(sel)) and activity in goldfish were evaluated. Blood and brain EtOH concentrations ([EtOH]) and brain oxygen partial pressure (PO(2)) were quantified at crucial ambient oxygen pressures. Below a threshold value near 31 Torr, T(sel) decreased as a function of environmental PO(2). T(sel) of 15 degrees C-acclimated fish was approximately 10 degrees C at the onset of anoxia and changed little over 2 h. Activity showed a similar response pattern. Brain [EtOH] was significantly elevated above control levels after 1 h anoxia. In normoxic water, T(sel) remained different in previously anoxic and normoxic control fish for approximately 20 min. Blood [EtOH] of previously anoxic fish remained significantly elevated ([EtOH] >4.0 micromol/g blood), and activity was significantly depressed at 20 min. Brain PO(2) reached normal levels in <3 min. We conclude that [EtOH] (brain or blood) and brain PO(2) are not proximal causes of either behavioral anapyrexia (hypothermia) or inactivity in goldfish exposed to oxygen-depleted environments.

  10. Profundal benthic invertebrates in an oligotrophic tropical lake: different strategies for coping with anoxia

    Directory of Open Access Journals (Sweden)

    María del Carmen Hernández

    2014-05-01

    Full Text Available The deep benthic communities of tropical lakes are poorly understood with respect to their composition, abundance, biomass and regulatory factors. Whereas the hypolimnia of temperate oligotrophic lakes remain oxygenated, the higher temperatures in tropical lakes frequently lead to the rapid development of hypolimnetic anoxia independent of trophic status. The deep benthic communities of tropical lakes must therefore develop strategies to respond to anoxic conditions. The dynamics of the deep benthic community of Lake Alchichica were studied over 15 months. We hypothesized that the sedimentation of the winter diatom bloom constitutes an input of high-quality food that contributes to the establishment and development of the deep benthic community. However, the remineralization of this organic matter leads to the prompt development of hypolimnetic anoxia, thus limiting the establishment and/or persistence of the deep benthic community. In contrast with the diverse littoral benthic community (50 taxa in Lake Alchichica, only two species constitute its deep benthic community, the ostracod Candona cf. patzcuaro and the chironomid Chironomus cf. austini, which combined exhibit a low density (1197±1976 ind m-2 and biomass (16.13±30.81 mg C m-2. C. patzcuaro is dominant and is present throughout the year, whereas Ch. austini is recorded only when the bottom water of the lake is oxygenated. A comparison with the analogous but temperate Lake Mergozzo in Italy illustrates the role that anoxia plays in tropical lakes by diminishing not only taxonomic richness (13 versus 2 spp. in temperate versus tropical lakes, respectively but also abundance (1145 versus 287 ind m-2, respectively. C. patzcuaro is found throughout the annual cycle of the lake’s profundal zone, entering into diapause during the anoxic period and recovering as soon as the profundal zone reoxygenates. Ch. austini has adjusted its life cycle to use the habitat and available resources while

  11. Anoxia-induced elevation of cytosolic Ca2+ concentration depends on different Ca2+ sources in rice and wheat protoplasts.

    Science.gov (United States)

    Yemelyanov, Vladislav V; Shishova, Maria F; Chirkova, Tamara V; Lindberg, Sylvia M

    2011-08-01

    The anoxia-dependent elevation of cytosolic Ca(2+) concentration, [Ca(2+)](cyt), was investigated in plants differing in tolerance to hypoxia. The [Ca(2+)](cyt) was measured by fluorescence microscopy in single protoplasts loaded with the calcium-fluoroprobe Fura 2-AM. Imposition of anoxia led to a fast (within 3 min) significant elevation of [Ca(2+)](cyt) in rice leaf protoplasts. A tenfold drop in the external Ca(2+) concentration (to 0.1 mM) resulted in considerable decrease of the [Ca(2+)](cyt) shift. Rice root protoplasts reacted upon anoxia with higher amplitude. Addition of plasma membrane (verapamil, La(3+) and EGTA) and intracellular membrane Ca(2+)-channel antagonists (Li(+), ruthenium red and cyclosporine A) reduced the anoxic Ca(2+)-accumulation in rice. Wheat protoplasts responded to anoxia by smaller changes of [Ca(2+)](cyt). In wheat leaf protoplasts, the amplitude of the Ca(2+)-shift little depended on the external level of Ca(2+). Wheat root protoplasts were characterized by a small shift of [Ca(2+)](cyt) under anoxia. Plasmalemma Ca(2+)-channel blockers had little effect on the elevation of cytosolic Ca(2+) in wheat protoplasts. Intact rice seedlings absorbed Ca(2+) from the external medium under anoxic treatment. On the contrary, wheat seedlings were characterized by leakage of Ca(2+). Verapamil abolished the Ca(2+) influx in rice roots and Ca(2+) efflux from wheat roots. Anoxia-induced [Ca(2+)](cyt) elevation was high particularly in rice, a hypoxia-tolerant species. In conclusion, both external and internal Ca(2+) stores are important for anoxic [Ca(2+)](cyt) elevation in rice, whereas the hypoxia-intolerant wheat does not require external sources for [Ca(2+)](cyt) rise. Leaf and root protoplasts similarly responded to anoxia, independent of their organ origin.

  12. Life without oxygen: gene regulatory responses of the crucian carp (Carassius carassius heart subjected to chronic anoxia.

    Directory of Open Access Journals (Sweden)

    Kåre-Olav Stensløkken

    Full Text Available Crucian carp are unusual among vertebrates in surviving extended periods in the complete absence of molecular oxygen. During this time cardiac output is maintained though these mechanisms are not well understood. Using a high-density cDNA microarray, we have defined the genome-wide gene expression responses of cardiac tissue after exposing the fish at two temperatures (8 and 13 °C to one and seven days of anoxia, followed by seven days after restoration to normoxia. At 8 °C, using a false discovery rate of 5%, neither anoxia nor re-oxygenation elicited appreciable changes in gene expression. By contrast, at 13 °C, 777 unique genes responded strongly. Up-regulated genes included those involved in protein turnover, the pentose phosphate pathway and cell morphogenesis while down-regulated gene categories included RNA splicing and transcription. Most genes were affected between one and seven days of anoxia, indicating gene regulation over the medium term but with few early response genes. Re-oxygenation for 7 days was sufficient to completely reverse these responses. Glycolysis displayed more complex responses with anoxia up-regulated transcripts for the key regulatory enzymes, hexokinase and phosphofructokinase, but with down-regulation of most of the non-regulatory genes. This complex pattern of responses in genomic transcription patterns indicates divergent cardiac responses to anoxia, with the transcriptionally driven reprogramming of cardiac function seen at 13 °C being largely completed at 8 °C.

  13. Late holocene trends of phytoplankton productivity and anoxia as inferred from diatom and geochemical proxies in Lake Victoria, Eastern Africa

    Science.gov (United States)

    Andama, M.; Lejju, J. B.; Tolo, C. U.

    2013-11-01

    Lake Victoria ecosystem has undergone major ecological changes in the recent decades. Sedimentary diatom analysis and Fe / Mn determined by Energy Dispersive X-ray Fluorescence (EDXRF) have provided phytoplankton (diatom) productivity and the resultant anoxia (Fe / Mn) in Lake Victoria at Napoleon Gulf during the late Holocene (1778 cal yr BP (calibrated years before present) to 2008 AD) with radiocarbon dates determined using Accelerator Mass Spectrometry standard method. The results showed that increased total diatom counts in Napoleon Gulf during the late Holocene correspond with increased Fe / Mn ratio (anoxia) in some of the profiles and not in others and in most cases those that correspond correlate very well with increased eutrophication from nitrate input (Total Nitrogen, TN). Therefore slightly increased anoxia not related to increased diatom productivity was recorded in Lake Victoria at Napoleon Gulf from the period 1778 to 1135 cal yr BP. There was slightly increased diatom productivity at Napoleon Gulf from the period 857 to 758 cal yr BP but it did not increase anoxia in the lake. The period 415 cal yr BP to 2008 AD recorded increased anoxia at Napoleon Gulf related to high diatom productivity especially from 415 to 390 cal yr BP and 191 cal yr BP to 2008 AD.

  14. Regulation of Methane Oxidation in a Freshwater Wetland by Water Table Changes and Anoxia

    Science.gov (United States)

    Roslev, Peter; King, Gary M.

    1996-01-01

    The effects of water table fluctuations and anoxia on methane emission and methane oxidation were studied in a freshwater marsh. Seasonal aerobic methane oxidation rates varied between 15% and 76% of the potential diffusive methane flux (diffusive flux in the absence of aerobic oxidation). On an annual basis, approximately 43% of the methane diffusing into the oxic zone was oxidized before reaching the atmosphere. The highest methane oxidation was observed when the water table was below the peat surface. This was confirmed in laboratory experiments where short-term decreases in water table levels increased methane oxidation but also net methane emission. Although methane emission was generally not observed during the winter, stems of soft rush (Juncus effusus) emitted methane when the marsh was ice covered. Indigenous methanotrophic bacteria from the wetiand studied were relatively anoxia tolerant. Surface peat incubated under anoxic conditions maintained 30% of the initial methane oxidation capacity after 32 days of anoxia. Methanotrophs from anoxic peat initiated aerobic methane oxidation relatively quickly after oxygen addition (1-7 hours). These results were supported by culture experiments with the methanotroph Methylosinus trichosporium OB3b. This organism maintained a greater capacity for aerobic methane oxidation when starved under anoxic compared to oxic conditions. Anoxic incubation of M. trichosporium OB3b in the presence of sulfide (2 mM) and a low redox potential (-110 mV) did not decrease the capacity for methane oxidation relative to anoxic cultures incubated without sulfide. The results suggest that aerobic methane oxidation was a major regulator of seasonal methane emission front the investigated wetland. The observed water table fluctuations affected net methane oxidation presumably due to associated changes in oxygen gradients. However, changes from oxic to anoxic conditions in situ had relatively little effect on survival of the methanotrophic

  15. Marine hypoxia/anoxia as a source of CH4 and N2O

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Bange, H.W.; Farias, L.; Monteiro, P.M.S.; Scranton, M.I.; Zhang, J.

    of natural origin. The most important oceanic O2-deficient environments are formed naturally and have existed with varying intensities through geological times (Neretin, 2006). Today, a num- ber of semi-enclosed/land-locked seas and fjords experience anoxia...) and it is the relative contribution from these sources that controls the variability of O2 deficiency at any given site on seasonal as well as inter-annual time scales (Monteiro et al., 2006, 2008). The region is important for redox nitrogen transformations (Kuypers et...

  16. Diurnal effects of anoxia on the metabolome of the seagrass Zostera marina

    DEFF Research Database (Denmark)

    Hasler-Sheetal, Harald; Holmer, Marianne; Weckwerth, Wolfram;

    2014-01-01

    -molecule metabolites). Night time water column anoxia caused a shift in metabolic composition and concentration (trajectories of PLS-DA) in particular an increase in pyruvate and lactate indicating an activation of fermentation in the plant. Concurrent increase of alanine, succinate and GABA suggests the presence...... of the GABA shunt pathway, a strategy to decrease pyruvate levels by transamination. The down regulation of TCA cycle intermediates illustrates the inactivity of TCA due to lack of oxygen, which results in an accumulation of pyruvate and followed by fermentation to lactic acid. We demonstrate...

  17. Rhizosphere properties of rice genotypes as influenced by anoxia and availability of zinc and iron Propriedades da rizosfera de genótipos de arroz submetidos à anoxia e a diferentes disponibilidades de zinco e ferro

    OpenAIRE

    Roghieh Hajiboland; Naier Beiramzadeh

    2008-01-01

    The objective of this work was to study possible mechanisms involved in root-induced changes of rhizosphere physicochemical properties of rice genotypes, under anoxia and low supply of Zn and Fe. Two rice genotypes, including an upland and a lowland ones, were grown in hydroponic medium under adequate and low supply of Zn and Fe, with or without aeration. Anoxia increased shoot dry weight, root length and uptake of Zn and Fe in lowland Amol genotype, but reduced these parameters in upland Gas...

  18. [Changes in the biochemical composition, structure, and function of pea leaf chloroplasts in iron deficiency and root anoxia].

    Science.gov (United States)

    Ladygin, V G

    2004-01-01

    A combined effect of iron deficiency and root anoxia on the biochemical composition, function, and structure of pea leaf chloroplasts was studied. It was found that the chlorosis of apical leaves in response to iron deficiency was determined by the reduction of light-harvesting complexes I and II. Under root anoxia, complexes of the reaction centers of photosystems I and II degraded first. Weak activity was preserved even in yellow and white leaves under the effect of both factors. The ultrastructure of leaf chloroplasts gradually degraded. Initially, intergranal thylakoid sites were reduced, and the longitudinal orientation of grana was disturbed. However, yellow and white leaves still retained small thylakoids and grana. It is concluded that the degrading effects of iron deficiency and root anoxia on the complex composition and leaf chloroplast structure and function are additive because of their autonomous mechanisms. PMID:15553792

  19. IMPAIRED LEARNING AND ABNORMAL OPEN-FIELD BEHAVIORS OF RATS AFTER EARLY POSTNATAL ANOXIA AND THE BENEFICIAL EFFECT OF THE CALCIUM-ANTAGONIST NIMODIPINE

    NARCIS (Netherlands)

    NYAKAS, C; MARKEL, E; SCHUURMAN, T; LUITEN, PGM

    1991-01-01

    Perinatal anoxia/hypoxia is considered a serious risk factor for normal brain development. Anoxia induced by repeated asphyxia at 2 and 4 days after birth resulted in a transient hyperactivity in the small open-field, and a behavioural depression in adult open-field activity of male Wistar rats. The

  20. The Mitochondrial Unfolded Protein Response Protects against Anoxia in Caenorhabditis elegans

    Science.gov (United States)

    Peña, Salvador; Sherman, Teresa; Brookes, Paul S.; Nehrke, Keith

    2016-01-01

    The mitochondrial unfolded protein response (UPRmt) is a surveillance pathway that defends proteostasis in the “powerhouse” of the cell. Activation of the UPRmt protects against stresses imposed by reactive oxygen species, respiratory chain deficits, and pathologic bacteria. Consistent with the UPRmt’s role in adaption, we found that either its pharmacological or genetic activation by ethidium bromide (EtBr) or RNAi of the mitochondrial AAA-protease spg-7 was sufficient to reduce death in an anoxia-based Caenorhabditis elegans model of ischemia-reperfusion injury. The UPRmt-specific transcription factor atfs-1 was necessary for protection and atfs-1 gain-of-function (gf) mutants were endogenously protected from both death and dysfunction. Neurons exhibited less axonal degeneration following non-lethal anoxia-reperfusion (A-R) when the UPRmt was pre-activated, and consistent with the concept of mitochondrial stress leading to cell non-autonomous (ie. “remote”) effects, we found that restricted activation of the UPRmt in neurons decreased A-R death. However, expression of the atfs-1(gf) mutant in neurons, which resulted in a robust activation of a neuronal UPRmt, did not upregulate the UPRmt in distal tissues, nor did it protect the worms from A-R toxicity. These findings suggest that remote signaling requires additional component(s) acting downstream of de facto mitochondrial stress. PMID:27459203

  1. Effect of hypoxia and anoxia on invertebrate behaviour: ecological perspectives from species to community level

    Science.gov (United States)

    Riedel, B.; Pados, T.; Pretterebner, K.; Schiemer, L.; Steckbauer, A.; Haselmair, A.; Zuschin, M.; Stachowitsch, M.

    2014-03-01

    Coastal hypoxia and anoxia have become a global key stressor to marine ecosystems, with almost 500 dead zones recorded worldwide. By triggering cascading effects from the individual organism to the community- and ecosystem level, oxygen depletions threaten marine biodiversity and can alter ecosystem structure and function. By integrating both physiological function and ecological processes, animal behaviour is ideal for assessing the stress state of benthic macrofauna to low dissolved oxygen. The initial response of organisms can serve as an early warning signal, while the successive behavioural reactions of key species indicate hypoxia levels and help assess community degradation. Here we document the behavioural responses of a representative spectrum of benthic macrofauna in the natural setting in the Northern Adriatic Sea (Mediterranean). We experimentally induced small-scale anoxia with a benthic chamber in 24 m depth to overcome the difficulties in predicting the onset of hypoxia, which often hinders full documentation in the field. The behavioural reactions were documented with a time-lapse camera. Oxygen depletion elicited significant and repeatable changes in general (visibility, locomotion, body movement and posture, location) and species-specific reactions in virtually all organisms (302 individuals from 32 species and 2 species groups). Most atypical (stress) behaviours were associated with specific oxygen thresholds: arm-tipping in the ophiuroid Ophiothrix quinquemaculata, for example, with the onset of mild hypoxia (structure and ecosystem functioning. This integrated approach can transport complex ecological processes to the public and decision-makers and help define specific monitoring, assessment and conservation plans.

  2. Bistability of mitochondrial respiration underlies paradoxical reactive oxygen species generation induced by anoxia.

    Directory of Open Access Journals (Sweden)

    Vitaly A Selivanov

    2009-12-01

    Full Text Available Increased production of reactive oxygen species (ROS in mitochondria underlies major systemic diseases, and this clinical problem stimulates a great scientific interest in the mechanism of ROS generation. However, the mechanism of hypoxia-induced change in ROS production is not fully understood. To mathematically analyze this mechanism in details, taking into consideration all the possible redox states formed in the process of electron transport, even for respiratory complex III, a system of hundreds of differential equations must be constructed. Aimed to facilitate such tasks, we developed a new methodology of modeling, which resides in the automated construction of large sets of differential equations. The detailed modeling of electron transport in mitochondria allowed for the identification of two steady state modes of operation (bistability of respiratory complex III at the same microenvironmental conditions. Various perturbations could induce the transition of respiratory chain from one steady state to another. While normally complex III is in a low ROS producing mode, temporal anoxia could switch it to a high ROS producing state, which persists after the return to normal oxygen supply. This prediction, which we qualitatively validated experimentally, explains the mechanism of anoxia-induced cell damage. Recognition of bistability of complex III operation may enable novel therapeutic strategies for oxidative stress and our method of modeling could be widely used in systems biology studies.

  3. Effect of hypoxia and anoxia on invertebrate behaviour: ecological perspectives from species to community level

    Directory of Open Access Journals (Sweden)

    B. Riedel

    2013-08-01

    Full Text Available Coastal hypoxia and anoxia have become a global key stressor to marine ecosystems, with almost 500 dead zones recorded wordwide. By triggering cascading effects from the individual organism to the community and ecosystem-level, oxygen depletions threat marine biodiversity and can alter ecosystem structure and function. By integrating both physiological function and ecological processes, animal behaviour is ideal for assessing the stress state of benthic macrofauna to low dissolved oxygen. The initial response of organisms can serve as an early-warning signal, while the successive behavioural reactions of key species indicate hypoxia levels and help assess community degradation. Here we document the behavioural responses of a representative spectrum of benthic macrofauna in the natural setting in the Northern Adriatic Sea, Mediterranean. We experimentally induced small-scale anoxia with a benthic chamber in 24 m depth to overcome the difficulties in predicting the onset of hypoxia, which often hinders full documentation in the field. The behavioural reactions were documented with a time-lapse camera. Oxygen depletion elicited significant and repeatable changes in general (visibility, locomotion, body movement and posture, location and species-specific reactions in virtually all organisms (302 individuals from 32 species and 2 species groups. Most atypical (stress behaviours were associated with specific oxygen thresholds: arm-tipping in the ophiuroid Ophiothrix quinquemaculata, for example, with the onset of mild hypoxia (2 L−1, the emergence of polychates on the sediment surface with moderate hypoxia (2 L−1, the emergence of the infaunal sea urchin Schizaster canaliferus on the sediment with severe hypoxia (2 L−1 and heavy body rotations in sea anemones with anoxia. Other species changed their activity patterns, i.e. circadian rhythm in the hermit crab Paguristes eremita or the bioherm-associated crab Pisidia longimana. Intra- and

  4. Effect of emulsified isoflurane on apoptosis of anoxia-reoxygenation neonatal rat cardiomyocytes

    Institute of Scientific and Technical Information of China (English)

    Xiao Liu; Qu-Lian Guo; Zhong Zhang; Long Long; Yang Yang

    2013-01-01

    Objective:To explore the effect of emulsified isoflurane(EI) on apoptosis of anoxia-reoxygenation neonatal rat cardiomyocytes and relevant protein expression.Methods:Cardiac muscle anoxia-reoxygenation damage model was established with culture in vitro neonatal rat cardiomyocytes. The cardiomyocytes were divided into control group, model group, fat emulsion group andEI group.The cardiomyocytes apoptosis rates and lactic dehydrogenase(LDH), superoxide dismutase (SOD) and malondialdehyde(MDA) index standardization were detected after relevant treatment. The expression of apoptosis-related proteinsBel-2,Bax andCaspase-3 were detected with Western blot approach.Results:After hypoxia/reoxygenation(H/R) model was treated byEI, the cells apoptosis rate decreased and was dramatically below the fat emulsion group(P<0.05). Cardiomyocytes biochemical index detection presented that, compared with the control group that theLDH activity andMDA content dramatically increased(P<0.05), while theSOD activity notably decreased(P<0.05); compared with theH/R group, theSOD activity of the fat emulsion group and EI group increased(P<0.05); while theLDH activity andMDA content decreased(P<0.05).And the change of theEI group was more remarkable than the fat emulsion group(P<0.05).TheWestern blot analysis presented that, compared with the control group, theBcl-2 protein expression of the other groups significantly decreased(P<0.05), the expressions ofBax protein andCaspase-3 protein increased significantly(P<0.05); compared withH/R group, cardiomyocytesBcl-2 protein expression ofEI group increased significantly(P<0.05), the expressions ofBax protein andCaspase-3 protein decreased significantly(P<0.05), and the change ofEI group was more remarkable than the fat emulsion group(P<0.05).Conclusions:EI can inhabit the apoptosis of anoxia-reoxygenation damage model cardiomyocytes, and may be related to the up-regulation of expression ofBcl-2 and down-regulation of expression ofCaspase-3 protein.

  5. Na+-K+-ATPase trafficking induced by heat shock pretreatment correlates with increased resistance to anoxia in locusts

    Science.gov (United States)

    Hou, Nicholas; Armstrong, Gary A. B.; Chakraborty-Chatterjee, Munmun; Sokolowski, Marla B.

    2014-01-01

    The sensitivity of insect nervous systems to anoxia can be modulated genetically and pharmacologically, but the cellular mechanisms responsible are poorly understood. We examined the effect of a heat shock pretreatment (HS) on the sensitivity of the locust (Locusta migratoria) nervous system to anoxia induced by water immersion. Prior HS made locusts more resistant to anoxia by increasing the time taken to enter a coma and by reducing the time taken to recover the ability to stand. Anoxic comas were accompanied by surges of extracellular potassium ions in the neuropile of the metathoracic ganglion, and HS reduced the time taken for clearance of excess extracellular potassium ions. This could not be attributed to a decrease in the activity of protein kinase G, which was increased by HS. In homogenates of the metathoracic ganglion, HS had only a mild effect on the activity of Na+-K+-ATPase. However, we demonstrated that HS caused a threefold increase in the immunofluorescent localization of the α-subunit of Na+-K+-ATPase in metathoracic neuronal plasma membranes relative to background labeling of the nucleus. We conclude that HS induced trafficking of Na+-K+-ATPase into neuronal plasma membranes and suggest that this was at least partially responsible for the increased resistance to anoxia and the increased rate of recovery of neural function after a disturbance of K+ homeostasis. PMID:24848469

  6. Characterization of a novel fibroblast-like cell line from rainbow trout and responses to sublethal anoxia

    DEFF Research Database (Denmark)

    Ossum, Carlo Gunnar; Hoffmann, Else Kay; Vijayan, M.M.;

    2004-01-01

    A novel fibroblast-like cell line RTHDF was established from hypodermal connective tissue of rainbow trout Oncorhynchus mykiss and telomerase activity was demonstrated early and late in cell line development. When RTHDF cells were exposed to bioenergetic stress, i.e. anoxia, activation...... suggests that RTHDF can be useful in studying biochemical responses of teleost cells to environmental stress....

  7. Delayed recovery from the end-Triassic extinction due to an increase in the extent of ocean anoxia

    Science.gov (United States)

    Jost, A. B.; Bachan, A.; van de Schootbrugge, B.; Lau, K. V.; Weaver, K. L.; Maher, K.; Payne, J.

    2015-12-01

    The end-Triassic mass extinction was likely triggered by a rapid rise in pCO2 associated with the emplacement of the Central Atlantic Magmatic Province (CAMP) ca. 201 Ma. Shallow-marine anoxia has long been hypothesized to have caused the extinction and/or delayed the recovery of marine life. However, due to a lack of proxy data, the effects of CAMP emplacement on seawater chemistry remain poorly constrained. Local proxies for anoxia may not reflect widespread ocean redox conditions. However, coupled records of U concentration and isotopic composition (δ238U) in CaCO3 sediments precipitated beneath well-oxygenated bottom waters can potentially serve as a proxy for the global extent of anoxia due to fractionation of U during reduction and associated imbalances in the marine U cycle due to redox changes. We measured δ238U and Th/U values in shallow marine limestones from two stratigraphic sections in the Lombardy Basin, northern Italy, spanning over 400 m, to quantify the change in the extent of ocean anoxia during the end-Triassic extinction. We observe a ca. 0.6‰ negative excursion in δ238U beginning in the lowermost Jurassic, coeval with the onset of the negative δ13C excursion and persisting for the duration of subsequent high δ13C values in the lower-middle Hettangian (earliest Jurassic). Th/U values are generally low at the T/J boundary, peak near the nadir of the δ238U excursion, and steadily return to pre-event values by the end of the measured section. Using a numerical model of the U cycle, we demonstrate that this excursion corresponds to a thirty-fold increase in the extent of anoxia worldwide and a simultaneous increase in the riverine U flux, consistent with increased weathering and eutrophication following massive CO2 injection from CAMP volcanism. Scenarios involving an increase in marine anoxia would also predict higher rates of organic C burial, explaining the large protracted positive δ13C excursion in the lower-mid Hettangian. Recovery of

  8. Studies of ribonucleotide reductase in crucian carp-an oxygen dependent enzyme in an anoxia tolerant vertebrate.

    Directory of Open Access Journals (Sweden)

    Guro K Sandvik

    Full Text Available The enzyme ribonucleotide reductase (RNR catalyzes the conversion of ribonucleotides to deoxyribonucleotides, the precursors for DNA. RNR requires a thiyl radical to activate the substrate. In RNR of eukaryotes (class Ia RNR, this radical originates from a tyrosyl radical formed in reaction with oxygen (O(2 and a ferrous di-iron center in RNR. The crucian carp (Carassius carassius is one of very few vertebrates that can tolerate several months completely without oxygen (anoxia, a trait that enables this fish to survive under the ice in small ponds that become anoxic during the winter. Previous studies have found indications of cell division in this fish after 7 days of anoxia. This appears nearly impossible, as DNA synthesis requires the production of new deoxyribonucleotides and therefore active RNR. We have here characterized RNR in crucian carp, to search for adaptations to anoxia. We report the full-length sequences of two paralogs of each of the RNR subunits (R1i, R1ii, R2i, R2ii, p53R2i and p53R2ii, obtained by cloning and sequencing. The mRNA levels of these subunits were measured with quantitative PCR and were generally well maintained in hypoxia and anoxia in heart and brain. We also report maintained or increased mRNA levels of the cell division markers proliferating cell nuclear antigen (PCNA, brain derived neurotrophic factor (BDNF and Ki67 in anoxic hearts and brains. Electron paramagnetic resonance (EPR measurements on in vitro expressed crucian carp R2 and p53R2 proteins gave spectra similar to mammalian RNRs, including previously unpublished human and mouse p53R2 EPR spectra. However, the radicals in crucian carp RNR small subunits, especially in the p53R2ii subunit, were very stable at 0°C. A long half-life of the tyrosyl radical during wintertime anoxia could allow for continued cell division in crucian carp.

  9. Anoxia and export productivity - Resolving the chicken and egg paradox (Invited)

    Science.gov (United States)

    Paytan, A.

    2013-12-01

    Elevated sedimentary organic carbon, pyrite and trace metals (Mo, Re, U, V, I); isotopes of Mo, Fe, S and C; organic biomarkers such as Isorenieratane, are all robust indicators of anoxia, however these proxies do not reveal the causes for low oxygen concentrations in seawater and/or the sediments. Two (not mutually exclusive) mechanisms can lower the oxygen levels in the oceanic water column - stratification and sluggish circulation which result in long residence time of water masses that are not in contact with the atmosphere, and/or increased oxygen consumption by microorganisms in the process of organic matter regeneration (increased export production and regeneration). Marine barite formation in the water column and accumulation in sediments is not sensitive to oxygen content yet they directly respond to organic matter delivery and regeneration within the ocean twilight zone and may shed light on causes of anoxic events in the geological record. Examples from two prominent wide spread anoxic events will be presented.

  10. Hypoxia and anoxia effects on alcohol dehydrogenase activity and hemoglobin content in Chironomus riparius Meigen, 1804

    Directory of Open Access Journals (Sweden)

    Valentina Grazioli

    2016-02-01

    Full Text Available The metabolic effects of low oxygen content on alcohol-dehydrogenase (ADH activity and hemoglobin (Hb concentration were investigated in IV-instar larvae of Chironomus riparius (Diptera: Chironomidae from an Italian stream. Two series of short-term (48 h experiments were carried out: exposure to (1 progressive hypoxia (95 to 5% of oxygen saturation and (2 anoxia (at <5% of oxygen saturation. In (1, Hb amount increased with increasing oxygen depletion up to a critical value of oxygenation (about 70% of oxygen saturation. Below this percentage, the Hb amount declined to values comparable with those present in the control. The respiration rate (R remained almost constant at oxygen saturation >50% and decreased significantly only after 48 h of treatment (= <5% of oxygen saturation reaching values <100 mmolO2 gAFDW-1 h-1. ADH activity showed two phases of growth, within the first 14 h and over 18 h of exposure. Overall, we inferred that i Hb might function as short-term oxygen storage, enabling animals to delay the on-set of anaerobiosis; and ii alcoholic fermentation co-occurs for a short time with aerobic respiration, becoming the prevalent metabolic pathway below 5% of oxygen saturation (<1 mg L-1. These considerations were supported also by results from anoxia exposure (2. In such condition, larvae were visibly stressed, becoming immobile after few minutes of incubation, and ADH reached higher values than in the hypoxia treatment (2.03±0.15 UADH mg prot-1. Overall, this study showed a shift from aerobic to anaerobic activity in C. riparius larvae exposed to poorly oxygenated water with an associated alteration of ADH activity and the Hb amount. Such metabolites might be valid candidate biomarkers for the environmental monitoring of running waters.

  11. A 25 years-long record of anoxia in a semi-enclosed sea. A case study: the NW Adriatic Shelf, Italy.

    OpenAIRE

    Francesca ALVISI; Cozzi, Stefano; Sparnocchia, Stefania

    2011-01-01

    Hypoxia and anoxia have occurred in the Northern Adriatic in both offshore and coastal waters, at least since the beginning of 1900. Despite several specific studies on these events are available, an overall long-term analysis of their recurrence and triggering mechanisms may provide a tool for a better understanding of ecosystem present evolution. A compilation and analysis of historical information on the occurrence of hypoxia and anoxia in the North Adriatic was therefore done, focusing on...

  12. Rapid oxygen exchange across the leaves of Littorella uniflora provides tolerance to sediment anoxia

    DEFF Research Database (Denmark)

    Møller, Claus Lindskov; Jensen, Kaj Sand

    2012-01-01

    . Frequent non-destructive sampling of sediment pore water was used to track changes in sediment biogeochemistry. 3. Addition of organic matter triggered O2 depletion and accumulation of , Fe2+ and CO2 in sediments. Gas exchange across leaf surfaces was 1316 times higher for L.similar to uniflora than for L...... from water and underlies its greater tolerance to sediment anoxia following organic enrichment. 2. We studied plant response to varying sediment O2 demand and biogeochemistry by measuring photosynthesis, gas exchange across leaves and O2 dynamics in plants during long-term laboratory and field studies.......similar to dortmanna. Oxygen in the leaf lacunae of L.similar to uniflora remained above 10 kPa late at night on anoxic sediments despite organic enrichment. Leaf content of N and P of L.similar to uniflora remained sufficient to keep up photosynthesis despite prolonged sediment anoxia, whereas nutrient content...

  13. The impact of global warming and anoxia on marine benthic community dynamics: an example from the Toarcian (Early Jurassic.

    Directory of Open Access Journals (Sweden)

    Silvia Danise

    Full Text Available The Pliensbachian-Toarcian (Early Jurassic fossil record is an archive of natural data of benthic community response to global warming and marine long-term hypoxia and anoxia. In the early Toarcian mean temperatures increased by the same order of magnitude as that predicted for the near future; laminated, organic-rich, black shales were deposited in many shallow water epicontinental basins; and a biotic crisis occurred in the marine realm, with the extinction of approximately 5% of families and 26% of genera. High-resolution quantitative abundance data of benthic invertebrates were collected from the Cleveland Basin (North Yorkshire, UK, and analysed with multivariate statistical methods to detect how the fauna responded to environmental changes during the early Toarcian. Twelve biofacies were identified. Their changes through time closely resemble the pattern of faunal degradation and recovery observed in modern habitats affected by anoxia. All four successional stages of community structure recorded in modern studies are recognised in the fossil data (i.e. Stage III: climax; II: transitional; I: pioneer; 0: highly disturbed. Two main faunal turnover events occurred: (i at the onset of anoxia, with the extinction of most benthic species and the survival of a few adapted to thrive in low-oxygen conditions (Stages I to 0 and (ii in the recovery, when newly evolved species colonized the re-oxygenated soft sediments and the path of recovery did not retrace of pattern of ecological degradation (Stages I to II. The ordination of samples coupled with sedimentological and palaeotemperature proxy data indicate that the onset of anoxia and the extinction horizon coincide with both a rise in temperature and sea level. Our study of how faunal associations co-vary with long and short term sea level and temperature changes has implications for predicting the long-term effects of "dead zones" in modern oceans.

  14. Hypersaline and anoxia in the Devonian Frasnian-Famennian transition :Molecular fossil and mineralogical evidence from Guangxi ,South China

    Institute of Scientific and Technical Information of China (English)

    GONG Yiming; XU Ran; FENG Qi; ZHANG Lijun; MA Huizhen; ZENG Jianwei

    2007-01-01

    Abundant normal alkanes,isoprenoid hydrocarbons,terpanes and steranes were detected in 23 samples taken from the carbonate platform to basin facies in the Devonian Frasnian-Famennian (F-F) transition of Guangxi,South China.They were mainly derived from the phytoplankton or bacteria and algae.Molecular stratigraphic parameters,abundant micron gypsums and pyrite framboids show that hypersaline and anoxia prevailed in the F-F transition,the highly stressed environments occurred near the F-F boundary.Orbital cyclostratigraphic studies indicate that the hypersaline and anoxia prevailed in the F-F transition spanned an interval at least from the Palmatolepis linguiformis conodont Zone to the Middle Palmatolepis triangularis conodont Zone and lasted about 1.2 Ma.The Devonian marine ecosystem underwent Early Devonian gradual optimization,Middle Devonian to the F-F transitional stepwise deterioration and late Famennian recovery.A positive feedback among higher surface ocean temperatures,hypersaline,water column anoxia, enhanced nutrient regeneration,phytoplankton productivity and eutrophication was probably substantial in the F-F transition in Guangxi,South China,even in other regions of the world,such as Holy Cross Mountains of Poland,Montagne Noire in southern France,Alberta in Canada.The point that should be emphasized is that the decisive and direct causes of the F-F transitional mass extinction would be the stepwise deterioration of the marine ecosystem since the Middle Devonian other than a bolide impact on the earth.The hypersaline and anoxia prevailed in the F-F transition favor the formation and preservation of hydrocarbon source rocks in South China.

  15. NITRIC OXIDE (NO, CITRULLINE - NO CYCLE ENZYMES, GLUTAMINE SYNTHETASE AND OXIDATIVE STRESS IN ANOXIA (HYPOBARIC HYPOXIA AND REPERFUSION IN RAT BRAIN

    Directory of Open Access Journals (Sweden)

    M. Swamy, Mohd Jamsani Mat Salleh, K. N .S. Sirajudeen, Wan Roslina Wan Yusof, G. Chandran

    2010-01-01

    Full Text Available Nitric oxide is postulated to be involved in the pathophysiology of neurological disorders due to hypoxia/ anoxia in brain due to increased release of glutamate and activation of N-methyl-D-aspartate receptors. Reactive oxygen species have been implicated in pathophysiology of many neurological disorders and in brain function. To understand their role in anoxia (hypobaric hypoxia and reperfusion (reoxygenation, the nitric oxide synthase, argininosuccinate synthetase, argininosuccinate lyase, glutamine synthetase and arginase activities along with the concentration of nitrate /nitrite, thiobarbituric acid reactive substances and total antioxidant status were estimated in cerebral cortex, cerebellum and brain stem of rats subjected to anoxia and reperfusion. The results of this study clearly demonstrated the increased production of nitric oxide by increased activity of nitric oxide synthase. The increased activities of argininosuccinate synthetase and argininosuccinate lyase suggest the increased and effective recycling of citrulline to arginine in anoxia, making nitric oxide production more effective and contributing to its toxic effects. The decreased activity of glutamine synthetase may favor the prolonged availability of glutamic acid causing excitotoxicity leading to neuronal damage in anoxia. The increased formation of thiobarbituric acid reactive substances and decreased total antioxidant status indicate the presence of oxidative stress in anoxia and reperfusion. The increased arginase and sustained decrease of GS activity in reperfusion group likely to be protective.

  16. Arsenic speciation in Mono Lake, California: Response to seasonal stratification and anoxia

    Science.gov (United States)

    Hollibaugh, James T.; Carini, Steve; Gürleyük, Hakan; Jellison, Robert; Joye, Samantha B.; LeCleir, Gary; Meile, Christof; Vasquez, Lydia; Wallschläger, Dirk

    2005-04-01

    Mono Lake is a closed-basin, alkaline, hypersaline lake located at the western edge of the Great Basin in eastern California. We studied the distribution of arsenic (As) species in the water column of Mono Lake between February and November, 2002. This period captured the seasonal progression from winter mixing, through summer thermal stratification, to autumn overturn. Arsenic speciation was determined by ion chromatography-inductively coupled-plasma-mass spectrometry of samples preserved in the field by flash-freezing in liquid nitrogen. We found that arsenic speciation was dominated (>90%) by arsenate when oxygen was detectable. Once levels fell below 6 μmol/L O 2, arsenic speciation shifted to dominance by reduced species. Arsenate and arsenite co-occurred in a transition zone immediately below the base of the oxycline and low but significant concentrations of arsenate were occasionally detected in sulfidic hypolimnion samples. Thio-arsenic species were the dominant form of As found in sulfidic waters. Maxima of thio-arsenic species with stoichiometries consistent with mono-, di- and trithio-arsenic occurred in succession as sulfide concentration increased. A compound with a stoichiometry consistent with trithio-arsenic was the dominant As species (˜50% of total As) in high sulfide (2 mmol/L) bottom water. Lower concentrations of total As in bottom water relative to surface water suggest precipitation of As/S mineral phases in response to sulfide accumulation during prolonged anoxia.

  17. Quantitative Trait Loci and Epistatic Analysis of Seed Anoxia Germinability in Rice (Oryza sativa)

    Institute of Scientific and Technical Information of China (English)

    LI Xi-ming; JIANG Ling; ZHAI Hu-qu; HOU Ming-yu; WAN Jian-min; WANG Chun-ming; MA Liang-yong; WAN Jian-min; ZHUANG Jie-yun; LIU Guang-jie; YANG Chang-deng

    2004-01-01

    Anoxia germinability (AG) of 35 rice varieties was evaluated under different temperature and water submergence conditions.The shoot (including coleoptile) length of seedlings germinating under 30℃, 0.2 m water submergence for 5 days could be used as an optimal criterion for the AG evaluation of all the varieties. Differences were observed among the AGs of 359 varieties from different regions and subspecies with the optimized method. Moreover, 81 recombinant inbred lines derived from a cross of Kinmaze(japonica)/DV85 (indica) were used to detect quantitative trait loci (QTLs) conferring AG. A total of five QTLs for AG in the recombinant inbred population were detected on chromosomes 1, 2, 5 and 7, respectively. Phenotypic variations explained by each QTL ranged from 10.5% to 19.6%. Based on the directions of the additive effects, the alleles at three loci qAG-1, qAG-2 and qAG-7from Kinmaze increased AG, while alleles at loci qAG-5a and qAG-5b from DV85 increased AG. Meanwhile, three pairs of epistatic loci were found to be located on chromosomes 2, 3, 5 and 11 with significant effects ranging from 16.7% to 48.8%, and the highest one 48.78%, was detected between C563-X182 on chromosome 3 and R830-X208 on chromosome 5.

  18. Purification and characterization of a protein phosphatase that dephosphorylates pyruvate kinase in an anoxia tolerant animal.

    Science.gov (United States)

    Brooks, S P; Storey, K B

    1996-05-01

    A protein phosphatase that dephosphorylates pyruvate kinase (PK) in vitro was purified and characterized from the foot muscle of the anoxia tolerant gastropod mollusc Busycon canaliculatum. Purification involved three steps: negative chromatography through Blue Dextran and CM Sephadex, affinity chromatography on DEAE Sephadex and gel exclusion chromatography on Sephacryl S-400. Pyruvate kinase phosphatase (PK-Pase) activity was monitored by following changes in PK I50 values for L-alanine that had previously been linked to changes in the degree of PK phosphorylation. The purified PK-Pase gave a single band on SDS-polyacrylamide gel electrophoresis with a molecular weight of 41 +/- 1 kdaltons. Isoelectric focusing analysis showed that the PK-Pase had an isoelectric point of 4.2 +/- 0.1. Kinetic analysis showed that the enzyme was a Type 2C protein phosphatase with a pH optimum of 6.5. Maximal activity required the presence of magnesium ions (KM = 7.9 +/- 0.6 microM) although high concentrations of Mg2+ were inhibitory (I50 = 2.3 +/- 0.4 mM). The protein phosphatase activity was not affected by either spermine, cAMP, cGMP, potassium phosphate, tartrate, NaF, HgCl2, citrate or concentrations of CaCl2 less than 10 mM. The enzyme could also use ATP, ADP, and GTP as substrates. PMID:8739044

  19. An episode of widespread ocean anoxia during the latest Ediacaran Period revealed by light U isotope compositions in carbonates

    Science.gov (United States)

    Zhang, F.

    2015-12-01

    Reconstruction of ocean redox chemistry during the Ediacaran Period is important for understanding the causal relationship between environmental oxygen levels and early metazoan evolution. Geochemical data (e.g., high Mo and U concentrations and/or heavy Mo and U isotope compositions from sedimentary rocks) provide evidence of extensive ocean oxygenation shortly after the Marinoan glaciation at ca. 632 Ma [1], during the late Ediacaran Period at ca. 560-551 Ma [2], and multiple times during the early Cambrian Period [3, 4]. These episodes of oxygenation may have been separated by intervals of less oxygenated conditions [1, 2]. However, the global redox state of the ocean during the terminal Ediacaran period (ca. 551-541 Ma) is poorly constrained. We address this knowledge gap by measuring carbonate U isotope compositions (δ238U) - a novel global ocean redox proxy - of the Gaojiashan Member of the late Ediacaran Dengying Formation (ca. 551-541 Ma) in South China. An abrupt negative shift in δ238U from values scattering around -0.45‰ to values averaging -0.95‰ (±0.20‰, 2sd) was observed in the middle Gaojiashan Member, suggesting a globally widespread expansion of ocean anoxia during the terminal Ediacaran Period. The negative δ238U shift coincides with the onset of a pronounced positive carbon isotope excursion (from 0‰ to +6‰), suggesting that ocean anoxia is the major driving force behind enhanced organic carbon burial that led to the carbon isotope excursion. The widespread anoxia recorded by the Gaojiashan Member is bracketed by known intervals of extensive ocean oxygenation, thus indicating that the Precambrian-Phanerozoic transition was characterized by oscillating ocean redox conditions. The Ediacara biota (ca. 541 Ma) [5] disappeared shortly after the widespread ocean anoxia, suggesting that an expansion of ocean anoxia may have triggerred the onset of a mass extinction in the latest Ediacaran time. References: [1] Sahoo, et al. (2012), Nature

  20. Hypergravity Alters the Susceptibility of Cells to Anoxia-Reoxygenation Injury

    Science.gov (United States)

    McCloud, Henry; Pink, Yulondo; Harris-Hooker, Sandra A.; Melhado, Caroline D.; Sanford, Gary L.

    1997-01-01

    Gravity is a physical force, much like shear stress or mechanical stretch, and should affect organ and cellular function. Researchers have shown that gravity plays a role in ventilation and blood flow distribution, gas exchange, alveolar size and mechanical stresses within the lung. Short exposure to microgravity produced marked alterations in lung blood flow and ventilation distribution while hypergravity exaggerated the regional differences in lung structure and function resulting in reduced ventilation at the base and no ventilation of the upper half of the lung. Microgravity also decreased metabolic activity in cardiac cells, WI-38 embryonic lung cells, and human lymphocytes. Rats, in the tail-suspended head-down tilt model, experienced transient loss of lung water, contrary to an expected increase due to pooling of blood in the pulmonary vasculature. Hypergravity has also been found to increase the proliferation of several different cell lines (e.g., chick embryo fibroblasts) while decreasing cell motility and slowing liver regeneration following partial hepatectomy. These studies show that changes in the gravity environment will affect several aspects of organ and cellular function and produce major change in blood flow and tissue/organ perfusion. However, these past studies have not addressed whether ischemia-reperfusion injury will be exacerbated or ameliorated by changes in the gravity environment, e.g., space flight. Currently, nothing is known about how gravity will affect the susceptibility of different lung and vascular cells to this type of injury. We conducted studies that addressed the following question: Does the susceptibility of lung fibroblasts, vascular smooth muscle, and endothelial cells to anoxia/reoxygenation injury change following exposure to hypergravity conditions?

  1. Diagenesis and benthic fluxes of nutrients and metals during experimentally induced anoxia in the Gulf of Trieste (northern Adriatic Sea

    Directory of Open Access Journals (Sweden)

    N. Koron

    2013-07-01

    Full Text Available Sequential nutrient regeneration and organic matter (OM degradation in surface sediments of the Gulf of Trieste (northern Adriatic Sea were examined using in situ benthic chambers under normoxic, anoxic and reoxic conditions. Intensive NH4+ and PO4− anoxic regeneration was subsequently slower in prolonged anoxia. NH4+ production was probably also a consequence of dissimilatory nitrate reduction to NH4+. The presence of anammox and laterally pumping of oxygenated water by benthic infauna explained the presence of NO3− in anoxia. Anoxic phases were characterized by enhanced dissolution of Sibiog, decreasing pore water Ca and Mg concentrations indicating carbonate precipitation and higher Fe and Mn concentrations as a result of reduction/respiration. Reoxygenation was characterized by enhanced bioturbation. Nitrification caused NH4+ decrease and P precipitated quickly as carbonate fluorapatite and FePO4. In addition adsorption of P onto Fe-hydroxides could also occur since Fe (and Mn reoxidized quickly. Increased Ca levels suggested enhanced carbonate dissolution. Diffusive fluxes at the sediment–water interface (SWI, calculated from pore water modelling using diffusion-reaction model, revealed high anoxic NH4+ effluxes and Ca (and Mg influxes. PO4− fluxes were very low and high NH4+/PO4− flux ratios in anoxic and reoxic phases suggested an excess of benthic inorganic N. Nutrient budgets at the SWI showed intensive anoxic recycling of inorganic N but low P and Si cycling in all redox phases.

  2. Pushing the limit: examining factors that affect anoxia tolerance in a single genotype of adult D. melanogaster.

    Science.gov (United States)

    Benasayag-Meszaros, Raquel; Risley, Monica G; Hernandez, Priscilla; Fendrich, Margo; Dawson-Scully, Ken

    2015-01-01

    Drosophila melanogaster is a promiscuous species that inhabits a large range of harsh environments including flooded habitats and varying temperature changes. To survive these environments, fruit flies have adapted mechanisms of tolerance that allow them to thrive. During exposure to anoxic stress, fruit flies and other poikilotherms enter into a reversible, protective coma. This coma can be manipulated based on controlled environmental conditions inside the laboratory. Here we utilize a common laboratory raised strain of D. melanogaster to characterize adaptation abilities to better understand coma recovery and survival limitations. Our goal is to mimic the fly's natural environments (wet anoxia) and relate findings to a typical gas induced environment (dry anoxia) that is commonly used in a laboratory. Despite the abundance of research regarding acute and chronic anoxic exposure and cold stress, the literature is lacking evidence linking anoxic stress with variable environmental conditions such as animal age and stress duration. We present novel ways to assess coma recovery and survival using readily available laboratory tools. Our findings suggest that younger age, exposure to colder temperatures and wet environments increase resistance to anoxic stress. PMID:25777190

  3. Relationships between ocean anoxia, the biological pump, and marine animal life during the Permian-Triassic mass extinction (Invited)

    Science.gov (United States)

    Meyer, K. M.; Schaal, E. K.; Payne, J.

    2013-12-01

    Ocean anoxia/euxinia and carbon cycle instability have long been linked to the end-Permian mass extinction and the Early Triassic interval of delayed or interrupted biotic recovery. Many hypotheses to explain this extinction event invoke the release of greenhouse gases during the emplacement of the Siberian Traps, which likely triggered abrupt changes in marine biogeochemical cycling, atmospheric chemistry, and biodiversity. However, the precise ways in which volcanism and these perturbations are linked and how they governed the tempo and mode of biotic recovery remain poorly understood. Here we highlight new C, Ca, and Sr isotopic data that serve to link volcanic CO2 inputs to changes in marine biogeochemistry and environmental change. We then examine the relationship between ocean biogeochemistry, the biological pump, and marine animal ecosystems during the end-Permian mass extinction and Early Triassic recovery. Finally, we use numerical simulations to probe whether these relationships also explain broad Phanerozoic trends in ocean nutrient status, anoxia, and productivity of marine ecosystems.

  4. Coastal hypoxia/anoxia as a source of CH4 and N2O

    Directory of Open Access Journals (Sweden)

    M. I. Scranton

    2009-10-01

    Full Text Available We review here available information on distributions of methane (CH4 and nitrous oxide (N2O from major, mostly coastal, oxygen (O2-deficient zones produced due to both natural processes and human activities (mainly eutrophication. Concentrations of both gases in subsurface waters are affected by ambient O2 levels. In the case of CH4, bottom-water O2 content probably affects emission from sediments, believed to be the main source of water-column CH4, as well as its oxidative loss in water itself. Highest CH4 accumulation (several μM occurs in silled basins having anoxic deep waters such as the Black Sea and the Cariaco Basin. One to two orders of magnitude smaller, but still significant, accumulation also occurs in bottom waters of open margins experiencing anoxia and in silled basins containing suboxic/severely hypoxic waters. In highly eutrophic waters over open continental shelves (such as the upwelling zone off Namibia and the "dead zone" in the Gulf of Mexico high CH4 concentrations (several hundred nM may occur in non-sulphidic waters as well, but in these regions it is difficult to differentiate the hypoxia-induced enhancement from in situ production of CH4 in the water column and, sometimes, large inputs of CH4 associated with freshwater runoff or seepage from sediments. Despite the observed CH4 build-up in low-O2 bottom waters, methanotrophic activity severely restricts its emission from the ocean. As a result, an intensification or expansion of coastal hypoxic zones will probably not drastically change the present status where emission from the ocean as a whole forms an insignificant term in the atmospheric CH4 budget. The situation is different for N2O, the production of which is greatly enhanced in severely hypoxic waters, and although it is lost through denitrification in most suboxic and anoxic environments, the peripheries of such environments offer most suitable conditions for its production, with the exception of semi

  5. Hormonal regulation of dipeptide transporter (PepT1) in Caco-2 cells with normal and anoxia/reoxygenation management

    Institute of Scientific and Technical Information of China (English)

    Bing-Wei Sun; Xiao-Chen Zhao; Guang-Ji Wang; Ning Li; Jie-Shou Li

    2003-01-01

    AIM: To determine the regulation effects of recombinant human growth hormone (rhGH) on dipeptide transporter (PepT1) in Caco-2 cells with normal culture and anoxia/reoxygenation injury.METHODS: A human intestinal cell monolayer (Caco-2) was used as the in vitro model of human small intestine and cephalexin as the model substrate for dipeptide transporter (PepT1). Caco-2 cells grown on Transwell membrane filters were preincubated in the presence of rhGH in the culture medium for 4 d, serum was withdrawn from monolayers for 24 h before each experiment. The transport experiments of cephalexin across apical membromes were then conducted;Caco-2 cells grown on multiple well dishes (24 pore) with normal culture or anoxia/reoxygenation injury were preincubated with rhGH as above and uptake of cephalexin was then measured.RESULTS: The transport and uptake of cephelaxin across apical membranes of Caco-2 cells after preincubation with rhGH were significantly increased compared with controls (P=0.045, 0.0223). Also, addition of rhGH at physiological concentration (34 nM) to incubation medium greatly stimulates cephalexin uptake by anoxia/reoxygenation injuried Caco-2 cells (P=0.0116), while the biological functions of PepT1 in injured Caco-2 cells without rhGH were markedly downregulated. Northem blot analysis showed that the level of PepT1 mRNA of rhGH-treated injured Caco-2cells was greatly increased compared to controls.CONCLUSION: The present results of rhGH stimulating the uptake and transport of cephalexin indicated that rhGH greatly upregulates the physiological effects of dipeptide transporters of Caco-2 cells. The alteration in the gene expression may be a mechanism of regulation of PepT1. In addition, Caco-2 cells take up cephalexin by the Proton-dependent dipeptide transporters that closely resembles the transporters present in the intestine. Caco-2 cells represent an ideal cellular model for future studies of the dipeptide transporter.

  6. Proton Gradient Regulation5-Like1-Mediated Cyclic Electron Flow Is Crucial for Acclimation to Anoxia and Complementary to Nonphotochemical Quenching in Stress Adaptation

    DEFF Research Database (Denmark)

    Kukuczka, Bernadeta; Magneschi, Leonardo; Petroutsos, Dimitris;

    2014-01-01

    for cyclic electron flow (CEF) in pgrl1. Under anoxia, where CEF is induced, quantitative proteomics evidenced severe down-regulation of photosystems but up-regulation of the chloroplast NADH dehydrogenase complex, plastocyanin, and Ca2+ sensors in the mutant, indicating that the absence of PGRL1 triggered...

  7. Short-term post-mortality predation and scavenging and longer-term recovery after anoxia in the northern Adriatic Sea

    Directory of Open Access Journals (Sweden)

    M. Blasnig

    2013-03-01

    Full Text Available In the Mediterranean, the northern Adriatic Sea shows most features known to promote late-summer hypoxia and anoxia. These features, along with anthropogenic eutrophication and marine snow events, have led to repeated benthic mortalities here. The present study was designed to document the post-anoxia macrofauna dynamics. We deployed an underwater instrument to induce small-scale anoxia in situ (total area 0.5 m2. Two time-lapse camera deployments examined short-term scavenging of the moribund and dead organisms (multi-species clumps consisting of sponges and ascidians over a 3-day period (August 2008: 71.5 h, September 2008: 67.5 h. Longer-term recovery (2 yr in the same two plots was examined with an independent photo-series. Predators and scavengers arrived in a distinct sequence. The first to arrive were demersal (Gobius niger, Serranus hepatus and benthopelagic fishes (Diplodus vulgaris, Pagellus erythrinus, followed by hermit crabs (Paguristes eremita, showing a clear day/night rhythm in presence and gastropods (Hexaplex trunculus. This sequence of arrival is attributed to the relative speeds of the organisms and their densities. The scavengers remained in dense aggregations (e.g. up to 33 P. eremita individuals at one time as long as the dead organisms were available. The whole sessile fauna was largely removed or consumed within 7 (August plot and 13 (September plot days after anoxia. No macroepibenthic recovery took place in the experimental plots one and two years after anoxia. This study underlines the sensitivity of this soft-bottom community and supports calls for reducing additional anthropogenic disturbances such as damaging commercial fishing practices that impede recolonization and threaten benthic community structure and function over the long-term.

  8. The involvement of hydrogen-producing and ATP-dependent NADPH-consuming pathways in setting the redox poise in the chloroplast of Chlamydomonas reinhardtii in anoxia.

    Science.gov (United States)

    Clowez, Sophie; Godaux, Damien; Cardol, Pierre; Wollman, Francis-André; Rappaport, Fabrice

    2015-03-27

    Photosynthetic microalgae are exposed to changing environmental conditions. In particular, microbes found in ponds or soils often face hypoxia or even anoxia, and this severely impacts their physiology. Chlamydomonas reinhardtii is one among such photosynthetic microorganisms recognized for its unusual wealth of fermentative pathways and the extensive remodeling of its metabolism upon the switch to anaerobic conditions. As regards the photosynthetic electron transfer, this remodeling encompasses a strong limitation of the electron flow downstream of photosystem I. Here, we further characterize the origin of this limitation. We show that it stems from the strong reducing pressure that builds up upon the onset of anoxia, and this pressure can be relieved either by the light-induced synthesis of ATP, which promotes the consumption of reducing equivalents, or by the progressive activation of the hydrogenase pathway, which provides an electron transfer pathway alternative to the CO2 fixation cycle. PMID:25691575

  9. Anti-apoptotic effect of morphine-induced delayed preconditioning on pulmonary artery endothelial cells with anoxia/reoxygenation injury

    Institute of Scientific and Technical Information of China (English)

    DING Weng-ang; ZHOU Hua-cheng; CUI Xiao-guang; LI Wen-zhi; GUO Yue-ping; ZHANG Bing; LIU Wei

    2008-01-01

    Background Opioid preconditioning (PC) reduces anoxiaJreoxygenation (NR) injury to various cells. However, it remains unclear whether opioid-induced delayed PC would show anti-apoptotic effects on pulmonary artery endothelial cells (PAECs) suffering from A/R injury. The present study was conducted to elucidate this issue and to investigate the potential mechanism of opioid-induced delayed PC.Methods Cultured porcine PAECs underwent 16-hour anoxia followed by 1-hour reoxygenation 24 hours after pretreatment with saline (NaCI; 0.9%) or morphine (1 μmol/L). To determine the underlying mechanism, a non-selective KATP channel inhibitor glibenclamide (Glib; 10 μmol/L), a nitric oxide (NO) synthase blocker NG-nitro-L-arginine methyl ester (L-NAME; 100 μmol/L), and an opioid receptor antagonist naloxone (Nal; 10 pmol/L) were given 30 minutes before the A/R load. The percentage of apoptotic cells was assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining, eNOS mRNA level was measured by real-time polymerase chain reaction (PCR). NO content of PAECs supernatants was measured with the Griess reagent.Results Compared to the A/R PAECs, morphine-induced delayed PC significantly reduced PAECs apoptosis ((18.1±1.9)% vs (5.5±0.3)%; P <0.05), increased NO release ((11.4±1.3) μmol/L vs (20.5±2.1) μmol/L, P <0.05), and up-regulated eNOS gene expression nearly 9 times (P<0.05). The anti-apoptosis effect of morphine was abolished by pretreatment with Glib, L-NAME and Nal, but the three agent-selves did not aggravate the A/R injury. Furthermore, L-NAME and Nal offset the enhanced release of NO caused by pretreatment with morphine.Conclusions Morphine-induced delayed PC prevents A/R injury of PAECs. This effect may be mediated by activation of KATP channel via opioid receptor and NO signaling pathways.

  10. A Stable U Isotopic Perspective on the U Budget and Global Extent of Modern Anoxia in the Ocean.

    Science.gov (United States)

    Tissot, F.; Dauphas, N.

    2015-12-01

    Isotopic fractionation between U4+ and U6+makes U stable isotopes potential tracers of global paleoredox conditions. In this work [1], we put the U-proxy up to a test against a highly constrained system: the modern ocean. We measured a large number of seawater samples from geographically diverse locations and found that the open ocean has a homogenous isotopic composition at δ238USW= -0.392 ± 0.005 ‰ (rel. to CRM-112a). From our measurement of rock samples (n=64) and compilations of literature data (n=380), we then estimated the U isotopic compositions of the various reservoirs involved in the modern oceanic U budget, as well as the fractionation factors associated with U incorporation into those reservoirs. Using a steady-state model, we compared the isotopic composition of the seawater predicted by the four most recent U oceanic budgets [2-5] to the modern seawater value we measured. Three of these budgets [2-4] predict a seawater isotopic composition in very good agreement with the observed δ238USW, which strengthens our confidence in the isotopic fractionation factors associated with each deposition environment and the fact that U is at steady-state in the modern ocean. The U oceanic budget of Henderson and Anderson (2003) does not reproduce the observed seawater composition because the U flux to anoxic/euxinic sediments relative to the total U flux out of the ocean is high in their model, which our analysis shows cannot be correct. The U isotopic composition of seawater is used to constrain the extent of anoxia in the modern ocean (% of seafloor covered by anoxic/euxinic sediments), which is 0.21 ± 0.09 %. This work demonstrates that stable isotopes of U can indeed trace the extent of anoxia in the modern global ocean, thereby validating the application of U isotope measurements to paleoredox reconstructions. Based on the above work, we will present the best estimate of the modern oceanic U budget. [1] Tissot F.L.H., Dauphas N. (2015) Geochim Cosmochim

  11. New 3′,8′′-Linked Biflavonoids from Selaginella uncinata Displaying Protective Effect against Anoxia

    Directory of Open Access Journals (Sweden)

    Ming Fan

    2011-07-01

    Full Text Available Seven 3′,8′′-linked bioflavonoids, including one new compound, (2′′S-2′′, 3′′-dihydroamentoflavone-4′-methyl ether (1 and six known compounds: (2S-2,3- dihydroamentoflavone-4′-methyl ether (2, (2S,2′′S-2,3,2′′,3′′-tetrahydroamento- flavone-4′-methyl ether (3, (2S,2′′S-tetrahydroamentoflavone (4, (2S-2,3-dihydro- amentoflavone (5 and (2′′S-2′′,3′′-dihydroamentoflavone (6 and amentoflavone (7, were isolated from the 60% ethanolic extract of Selaginella uncinata (Desv. Spring. The structures of these compounds were elucidated mainly by analysis of their 1D and 2D NMR spectroscopic data, and their absolute configurations were determined by circular-dichroism (CD spectroscopy. All the seven compounds showed protective effect against anoxia in the anoxic PC12 cells assay, in which compound 6 displayed particularly potent activity.

  12. Formation of anoxia and denitrification in the bottom waters of a tropical estuary, southwest coast of India

    Directory of Open Access Journals (Sweden)

    G. D. Martin

    2010-03-01

    Full Text Available Hydrographic characteristics of the southwest coast of India and its adjoining Cochin backwaters (CBW were studied during the summer monsoon period. Anomalous formation of anoxia and denitrification were observed in the bottom layers of CBW, which have not been previously reported elsewhere in any tropical estuarine systems. The prevalent upwelling in the Arabian Sea (AS brought cool, high saline, oxygen deficient and nutrient-rich waters towards the coastal zone and bottom layers of CBW during the high tide. High freshwater discharge in the surface layers brought high amount of nutrients and makes the CBW system highly productive. Intrusion of AS waters seems to be stronger towards the upstream end (~15 km, than had been previously reported, as a consequence of the lowering of river discharges and deepening of channels in the estuary. Time series measurements in the lower reaches of CBW indicated a low mixing zone with increased stratification, 3 h after the high tide (highest high tide and high variation in vertical mixing during the spring and neap phases. The upwelled waters (O2≤40 μM intruded into the estuary was found to lose more oxygen during the neap phase (suboxic O2≤4 μM than spring phase (hypoxic O2≤10 μM. Increased stratification coupled with low ventilation and presence of high organic matter have resulted in an anoxic condition (O2=0, 2–6 km away from barmouth of the estuary and leads to the formation of hydrogen sulphide. The reduction of nitrate and formation of nitrite within the oxygen deficient waters indicated strong denitrification intensity in the estuary. The expansion of oxygen deficient zone, denitrification and formation of hydrogen sulphide may lead to a destruction of biodiversity and an increase of green house gas emissions from this region.

  13. Protective Effects of Isorhamnetin on Cardiomyocytes Against Anoxia/Reoxygenation-induced Injury Is Mediated by SIRT1.

    Science.gov (United States)

    Huang, Liqing; He, Huan; Liu, Zhantu; Liu, Dan; Yin, Dong; He, Ming

    2016-06-01

    It has been reported that apoptosis plays a very important role on anoxia/reoxygenation (A/R)-induced injury, and human silent information regulator type 1 (SIRT1) can inhibit the apoptosis of cardiomyocytes. It has been proved that isorhamnetin (IsoRN), 3'-O-methyl-quecetin, can protect the cardiomyocytes, but the mechanism is still not clear. The aim of the study was to explore whether the protective effects of IsoRN on the cardiomyocytes against the A/R-induced injury are mediated by SIRT1. The effects of IsoRN on cardioprotection against A/R injury in neonatal rat cardiomyocytes were monitored by cell viability, the levels of mitochondrial membrane potential (Δψm), apoptosis, and intracellular reactive oxygen species (ROS), the levels of lactate dehydrogenase (LDH), creatine phosphokinase (CPK) and mitochondrial permeability transition pores (mPTP). The effects on protein expression were measured by western blot assay. The results showed that IsoRN can reduce A/R-induced injury by decreasing the level of lactate dehydrogenase and creatine phosphokinase release from the cardiomyocytes, increasing cell viability and expression of SIRT1, reducing the generation of reactive oxygen species, inhibiting opening of mitochondrial permeability transition pores and loss of Δψm and activation of caspase-3, and decreasing the release of cytochrome c, and reducing apoptosis. In addition, sirtinol, a SIRT1 inhibitor, drastically reduced the protective effects of IsoRN on cardioprotective effects in cardiomocytes. In conclusion, we firstly demonstrated that SIRT1 may be involved in the protective effects of IsoRN on cardiomocytes against the A/R-induced injury. PMID:26859194

  14. The soy phytoestrogens genistein and daidzein as neuroprotective agents against anoxia-glucopenia and reperfusion damage in rat urinary bladder.

    Science.gov (United States)

    Valeri, A; Fiorenzani, P; Rossi, R; Aloisi, A M; Valoti, M; Pessina, F

    2012-10-01

    Some bladder disorders, such as obstructive bladder and hyperactivity, may be caused partly by ischemia/reperfusion injury (I/R). The neuroprotective effects of estrogens were demonstrated in in vitro studies and a great interest in soy isoflavones (genistein and daidzein) as alternative to the synthetic estrogen receptor modulators for therapeutic use has been pointed out. The aim of this study was to investigate the effect of genistein and daidzein, on rat detrusor smooth muscle contractility and their possible neuroprotective role against I/R-like condition. Whole rat urinary bladders were subjected to in vitro anoxia-glucopenia (A-G) and reperfusion (R) in the absence or presence of drugs and response to electrical field stimulation (EFS) of intrinsic nerves evaluated. Furthermore rats were treated in vivo for 1 week with the phytoestrogens and the same in vitro protocol was applied to the ex vivo bladders. Antioxidant activity of genistein and daidzein on the A-G/R model was determined by measuring malonyldialdehyde (MDA). Moreover, hormones plasma levels were determined by radioimmunoassay. Genistein and daidzein administered either in vitro or in vivo showed significant neuroprotective effect and antioxidant activity. Testosterone and 17β-estradiol plasma levels were not modified by daidzein, while a significant decrease of testosterone in genistein treated rats was evident. Moreover both phytoestrogens significantly decreased detrusor contractions induced by EFS in a concentration-dependent manner. For being either neuroprotective and myorelaxant, genistein and daidzein could be considered a good lead for new therapeutic agents to protect the urinary bladder from hyperactivity and nerve damage. PMID:22743170

  15. CellTracker Green labelling vs. rose bengal staining: CTG wins by points in distinguishing living from dead anoxia-impacted copepods and nematodes

    Directory of Open Access Journals (Sweden)

    M. Grego

    2013-07-01

    Full Text Available Hypoxia and anoxia have become a key threat to shallow coastal seas. Much is known about their impact on macrofauna, less on meiofauna. In an attempt to shed more light on the latter group, in particular from a process-oriented view, we experimentally induced short-term anoxia (1 week in the northern Adriatic Sea (Mediterranean and examined the two most abundant meiofauna taxa – harpacticoid copepods and nematodes. Both taxa also represent different ends of the tolerance spectrum, with copepods being the most sensitive and nematodes among the most tolerant. We compared two methods: CellTracker Green (CTG – new labelling approach for meiofauna – with the traditional rose bengal (RB staining method. CTG binds to active enzymes and therefore colours live organisms only. The two methods show considerable differences in the number of living and dead individuals of both meiofauna taxa. Generally, RB will stain dead but not yet decomposed copepods and nematodes equally as it does live ones. Specifically, RB significantly overestimated the number of living copepods in all sediment layers in anoxic samples, but not in any normoxic samples. In contrast, for nematodes, the methods did not show such a clear difference between anoxia and normoxia. RB overestimated the number of living nematodes in the top sediment layer of normoxic samples, which implies an overestimation of the overall live nematofauna. For monitoring and biodiversity studies, the RB method might be sufficient, but for more precise quantification of community degradation, especially after an oxygen depletion event, CTG labelling is a better tool. Moreover, it clearly highlights the surviving species within the copepod or nematode community. As already accepted for foraminiferal research, we demonstrate that the CTG labelling is also valid for other meiofauna groups.

  16. Effect of high glucose and anoxia on Amot expression in vascular endothelial cells with regard to its function in promoting angiogenesis

    Institute of Scientific and Technical Information of China (English)

    禇月颉

    2014-01-01

    Objective To observe the effects of high glucose and anoxia on Amot expression in vascular endothelial cells(VECs),and explore its role in angiogenesis.Methods VECs were incubated with different glucose concentrations for 48 h,and then cultured at normal oxygen concentration or anaerobic condition for 24 h.The protein expressions of p130-Amot and p80-Amot were detected by Western blot.After Amot expression was downregulated in VECs by siRNA,wound healing experiments and angiogenesis experiments were performed to test the effect

  17. Roles of Na+/H+ exchange in regulation of p38 mitogen-activated protein kinase activity and cell death after chemical anoxia in NIH3T3 fibroblasts

    DEFF Research Database (Denmark)

    Rentsch, Maria L; Ossum, Carlo G; Hoffmann, Else K;

    2007-01-01

    , p38 mitogen-activated protein kinase (MAPK), ERK1/2, p53, and Akt activity, and cell death, after chemical anoxia in NIH3T3 fibroblasts. The NHE1 inhibitor 5'-(N-ethyl-N-isopropyl) amiloride (EIPA) (5 muM), as well as removal of extracellular Na(+) [replaced by N-methyl-D: -glucamine (NMDG......) and extracellular signal-regulated kinase (ERK) (PD98059). In contrast, chemical anoxia activated p38 MAPK in an NHE-dependent manner, while ERK1/2 activity was unaffected. Anoxia-induced cell death was caspase-3-independent, mildly attenuated by EIPA, potently exacerbated by SB203580, and unaffected by PD98059...

  18. Investigation of the combined effects of acetate and photobioreactor illuminated fraction in the induction of anoxia for hydrogen production by Chlamydomonas reinhardtii

    Energy Technology Data Exchange (ETDEWEB)

    Degrenne, Benoit; Pruvost, Jeremy; Cogne, Guillaume; Legrand, Jack [Nantes Universite, CNRS, GEPEA UMR-CNRS 6144, Bd de l' Universite, CRTT-BP 406, 44602 Saint-Nazaire Cedex (France); Christophe, Gwendoline; Cornet, Jean Francois [Clermont Universite - ENSCCF, LGCB, 9 Rue Kessler, BP 10448, F-63012 Clermont-Ferrand Cedex 1 (France)

    2010-10-15

    In the context of hydrogen production by microalgae, the growth of Chlamydomonas reinhardtii was characterized under autotrophic and mixotrophic conditions in a fully controlled photobioreactor (PBR). The combined effect of light transfer conditions, as represented by the illuminated fraction {gamma}, with acetate consumption was observed upon establishment of anoxia. Anoxia was reached in batch cultures when {gamma} was close to 1 (almost fully illuminated culture) in mixotrophic conditions while a value of {gamma} {approx} 0.46 in autotrophic conditions was not sufficient. Based on these results, continuous hydrogen production was established in a cylindrical PBR operated in luminostat with constant illumination and in mixotrophic conditions. Maximum hydrogen gas production was equal to 1.4 {+-} 0.1 ml{sub H2} l{sup -1} h{sup -1} for photon flux density of 110 {mu}mol m{sup -2} s{sup -1} and reactor illuminated fraction of {gamma} = 0.5. Carbon mass balance was realized, emphasizing the necessity to work in strictly autotrophic conditions for hydrogen production with no concomitant CO{sub 2} release. (author)

  19. Induction of Photosynthetic Carbon Fixation in Anoxia Relies on Hydrogenase Activity and Proton-Gradient Regulation-Like1-Mediated Cyclic Electron Flow in Chlamydomonas reinhardtii1

    Science.gov (United States)

    Bailleul, Benjamin; Berne, Nicolas

    2015-01-01

    The model green microalga Chlamydomonas reinhardtii is frequently subject to periods of dark and anoxia in its natural environment. Here, by resorting to mutants defective in the maturation of the chloroplastic oxygen-sensitive hydrogenases or in Proton-Gradient Regulation-Like1 (PGRL1)-dependent cyclic electron flow around photosystem I (PSI-CEF), we demonstrate the sequential contribution of these alternative electron flows (AEFs) in the reactivation of photosynthetic carbon fixation during a shift from dark anoxia to light. At light onset, hydrogenase activity sustains a linear electron flow from photosystem II, which is followed by a transient PSI-CEF in the wild type. By promoting ATP synthesis without net generation of photosynthetic reductants, the two AEF are critical for restoration of the capacity for carbon dioxide fixation in the light. Our data also suggest that the decrease in hydrogen evolution with time of illumination might be due to competition for reduced ferredoxins between ferredoxin-NADP+ oxidoreductase and hydrogenases, rather than due to the sensitivity of hydrogenase activity to oxygen. Finally, the absence of the two alternative pathways in a double mutant pgrl1 hydrogenase maturation factor G-2 is detrimental for photosynthesis and growth and cannot be compensated by any other AEF or anoxic metabolic responses. This highlights the role of hydrogenase activity and PSI-CEF in the ecological success of microalgae in low-oxygen environments. PMID:25931521

  20. Induction of Photosynthetic Carbon Fixation in Anoxia Relies on Hydrogenase Activity and Proton-Gradient Regulation-Like1-Mediated Cyclic Electron Flow in Chlamydomonas reinhardtii.

    Science.gov (United States)

    Godaux, Damien; Bailleul, Benjamin; Berne, Nicolas; Cardol, Pierre

    2015-06-01

    The model green microalga Chlamydomonas reinhardtii is frequently subject to periods of dark and anoxia in its natural environment. Here, by resorting to mutants defective in the maturation of the chloroplastic oxygen-sensitive hydrogenases or in Proton-Gradient Regulation-Like1 (PGRL1)-dependent cyclic electron flow around photosystem I (PSI-CEF), we demonstrate the sequential contribution of these alternative electron flows (AEFs) in the reactivation of photosynthetic carbon fixation during a shift from dark anoxia to light. At light onset, hydrogenase activity sustains a linear electron flow from photosystem II, which is followed by a transient PSI-CEF in the wild type. By promoting ATP synthesis without net generation of photosynthetic reductants, the two AEF are critical for restoration of the capacity for carbon dioxide fixation in the light. Our data also suggest that the decrease in hydrogen evolution with time of illumination might be due to competition for reduced ferredoxins between ferredoxin-NADP(+) oxidoreductase and hydrogenases, rather than due to the sensitivity of hydrogenase activity to oxygen. Finally, the absence of the two alternative pathways in a double mutant pgrl1 hydrogenase maturation factor G-2 is detrimental for photosynthesis and growth and cannot be compensated by any other AEF or anoxic metabolic responses. This highlights the role of hydrogenase activity and PSI-CEF in the ecological success of microalgae in low-oxygen environments. PMID:25931521

  1. Anoxia tolerance in the aquatic monocot Potamogeton pectinatus absence of oxygen stimulates elongation in association with an unusually large pasteur effect.

    Science.gov (United States)

    Summers, J E; Ratcliffe, R G; Jackson, M B

    2000-08-01

    Elongation by stems of overwintered tubers of Potamogeton pectinatus (L.) is strongly promoted over several days by oxygen-free conditions. Characteristics of the respiration underpinning this unusual response were examined. Anaerobic plants produced ethanol and CO(2) in approximately equimolar amounts, indicating that glycolysis coupled to alcoholic fermentation was the principal CO(2)-producing respiratory pathway. Rates of CO(2) evolution by aerobic and anaerobic whole plants (shoot and tuber) were similar, suggesting a rate of glycolysis three times that of aerobic plants, i.e. a strong Pasteur effect. In the shoot alone, anaerobic CO(2) production was twice the aerobic rate indicating a 6-fold increase in the rate of glycolysis in this tissue. Anoxic stems contained more sucrose at a stronger concentration than slower-growing aerobic stems or anaerobic leaves, demonstrating that sugar supply to the site of most rapid growth exceeded demand in the absence of oxygen. Concentrations of potentially toxic acetaldehyde in the external medium were small (approximately 0.2 mol m(-3)) during anoxia and on return to aerated conditions. Lactic acid was undetectable under anaerobic conditions and in vivo (31)P-NMR analysis of shoots revealed a cytoplasmic acidification of only anoxia-intolerant species, showed much stronger cytoplasmic acidification when transferred to oxygen-free conditions.

  2. Effects of chemical anoxia on NHE1, p38 MAPK, p53, Akt and ERM proteins in NIH3T3 fibroblasts: evidence for a role of NHE1 upstream of p38 MAPK

    DEFF Research Database (Denmark)

    Rentsch, M. L.; Hoffmann, E. K.; Pedersen, Stine Helene Falsig

    2006-01-01

    Activation of the plasma membrane Na+/H+ exchanger NHE1 contributes importantly to ischemic/anoxic cell damage, yet the mechanisms involved are unclear. In NIH3T3 cells, PCR studies confirmed the expression of NHE1 and -8, yet not NHE2, -3, and -4. Chemical anoxia (10 mM azide, 10 min) was associ......Activation of the plasma membrane Na+/H+ exchanger NHE1 contributes importantly to ischemic/anoxic cell damage, yet the mechanisms involved are unclear. In NIH3T3 cells, PCR studies confirmed the expression of NHE1 and -8, yet not NHE2, -3, and -4. Chemical anoxia (10 mM azide, 10 min......) was associated with a decrease in pHi which was exacerbated by the NHE1 inhibitor EIPA (5 µM). Reperfusion (azide washout) elicited a rapid, EIPA-sensitive alkalinization to 7.60 ± 0.057 (n=6), compared to a starting pHi of 7.49 ± 0.032 (n=6). Cell survival was reduced by prolonged chemical anoxia (to 87% at 3 h...... and 41% at 24 h, MTT assay), an effect counteracted by EIPA at early ( 6 h) time points. Chemical anoxia was furthermore associated with: (i) a rapid ( 10 min) and transient phosphorylation of p38 MAPK, which was abolished by NHE1 inhibitors (EIPA, cariporide, 5 µM); (ii) increased phosphorylation...

  3. Detection of anoxia-reponsive genes in cultured cells of the rainbow trout Oncorhynchus mykiss (Walbaum), using an optimized, genome-wide oligoarray

    DEFF Research Database (Denmark)

    Olohan, L.A.; Li, W; Wulff, Tune;

    2008-01-01

    , this offers a highly cost-effective route to array experiments even for non-model species. The authors have validated this new microarray by investigating the in vitro responses of cultured rainbow trout cells following anoxia exposure for up to 24 h. The array displays a dynamic range of 104, which greatly....... The authors describe simple optimization procedures to compare the performance of different oligonucleotide probes predicted to hybridize to each of the trout sequences, so that the best performing probe could be selected. The collection of optimized probes was then submitted to a commercial oligoarray...... fabrication platform and the arrays used for specific experiments. This design approach leverages publicly available sequence data, thereby dramatically reducing production costs. Given an ability to incorporate additional sequence data, and inexpensively commissioning the updated oligoarray designs...

  4. Uranium isotopic compositions of the crust and ocean: Age corrections, U budget and global extent of modern anoxia

    Science.gov (United States)

    Tissot, François L. H.; Dauphas, Nicolas

    2015-10-01

    The 238U/235U isotopic composition of uranium in seawater can provide important insights into the modern U budget of the oceans. Using the double spike technique and a new data reduction method, we analyzed an array of seawater samples and 41 geostandards covering a broad range of geological settings relevant to low and high temperature geochemistry. Analyses of 18 seawater samples from geographically diverse sites from the Atlantic and Pacific oceans, Mediterranean Sea, Gulf of Mexico, Persian Gulf, and English Channel, together with literature data (n = 17), yield a δ238U value for modern seawater of -0.392 ± 0.005‰ relative to CRM-112a. Measurements of the uranium isotopic compositions of river water, lake water, evaporites, modern coral, shales, and various igneous rocks (n = 64), together with compilations of literature data (n = 380), allow us to estimate the uranium isotopic compositions of the various reservoirs involved in the modern oceanic uranium budget, as well as the fractionation factors associated with U incorporation into those reservoirs. Because the incorporation of U into anoxic/euxinic sediments is accompanied by large isotopic fractionation (ΔAnoxic/Euxinic-SW = +0.6‰), the size of the anoxic/euxinic sink strongly influences the δ238U value of seawater. Keeping all other fluxes constant, the flux of uranium in the anoxic/euxinic sink is constrained to be 7.0 ± 3.1 Mmol/yr (or 14 ± 3% of the total flux out of the ocean). This translates into an areal extent of anoxia into the modern ocean of 0.21 ± 0.09% of the total seafloor. This agrees with independent estimates and rules out a recent uranium budget estimate by Henderson and Anderson (2003). Using the mass fractions and isotopic compositions of various rock types in Earth's crust, we further calculate an average δ238U isotopic composition for the continental crust of -0.29 ± 0.03‰ corresponding to a 238U/235U isotopic ratio of 137.797 ± 0.005. We discuss the implications of

  5. Evidence for the Cellular Basis of Intestinal Death in Mice, from an Analysis of Dose-Effect Relationships Modified by Quality of Radiation, Dose Rate, Fractionation and Anoxia

    International Nuclear Information System (INIS)

    When animals are killed by radiation, as by other toxic agents, the dose-effect relationship may be characterized by the LD50 together with the 'spread' or variance of the observations. It is generally accepted that the type of dose-effect curve (a probability curve) obtained in such experiments is to be ascribed to subtle and uncontrollable biological variations within any group of experimental animals. Conditions of irradiation have been used such that the values of LD50 might be widely different, e.g. for intestinal death (at 4-5 days) the LD50 for animals exposed to fast electrons while breathing oxygen was 1020 rad, while for animals breathing nitrogen it was 2800 rad. In that example, the variances of the two sets of data were in exactly the same ratio as the LD50 values, so that the anoxia operated as a dose-modifying agent. For other methods of modifying the LD50, however, this was not true: for example when the LD50 was increased from 1200 to 1600 rad by fractionation the variance remained constant. A computer programme was set up to perform probit analyses on animal survival curves, and to test whether 'dose modification' or 'parallel slopes' (i.e. variances proportional to LD50 values, or constant variances) provides the better model for the comparison of the results of irradiation in any two sets of conditions. It was found , in general, that conditions which give true dose modification of cell survival curves (e.g. anoxia) are also dose-modifying for the animal survival curves, whereas conditions which act as if to change the shoulder of a cell survival curve, but not its slope (e.g. dose fractionation) act similarly in respect of animal survival curves. Thus the biological variability which expresses itself in the probability curve for animal survival seems to be closely linked with the survival curve for the particular cell population the depletion of which leads to the gastro-intestinal • syndrome. (author)

  6. An abrupt extinction in the Middle Permian (Capitanian) of the Boreal Realm with a causal link to anoxia, acidification and mercury poisoning

    Science.gov (United States)

    Bond, David; Wignall, Paul; Joachimski, Michael; Sun, Yadong; Savov, Ivan; Grasby, Stephen; Beauchamp, Benoit; Blomeier, Dierk

    2016-04-01

    The controversial Capitanian (Middle Permian, 262 Ma) extinction event is mostly known from equatorial latitudes and consequently its global extent is poorly resolved. We demonstrate that there were two, severe extinctions amongst brachiopods in northern Boreal latitudes (Spitsbergen), in the Middle to Late Permian, separated by a recovery phase. New age dating of the Kapp Starostin Formation of Spitsbergen using strontium and carbon isotopic trends suggests that the first crisis occurred in the Capitanian. This age assignment indicates that this Middle Permian extinction is manifest at higher latitudes. Redox proxies (pyrite framboids and trace metals) show that the Boreal crisis coincided with an intensification of oxygen depletion, implicating anoxia in the extinction scenario. The highly toxic metal mercury becomes enriched in strata at the Middle Permian extinction level implicating death-by-toxicity (and a possible link to volcanism). Finally, the near-total loss of carbonates across the Boreal Realm in the Middle to Late Permian also suggests a role for acidification. New in prep. data from Ellesmere Island, Arctic Canada (samples collected July 2015) tentatively suggests that this potent "three strikes and you're out" extinction mechanism was a Boreal-wide phenomenon. The Late Permian recovery interval saw the appearance of new brachiopod and bivalve taxa alongside survivors, and an increased mollusk dominance, resulting in an assemblage reminiscent of younger Mesozoic assemblages. The subsequent end-Permian mass extinction terminated this Late Permian radiation.

  7. Cytoprotective effects of quercetin and its sugar-containing natural congeners in cultured HEK293 cells injured by anoxia/hypoglycemia and the structure-effect relationship thereto

    Institute of Scientific and Technical Information of China (English)

    JIN Yue; LV Yong; HAN Guo-zhu; YU Hong-shan; JIN Feng-xie

    2008-01-01

    Objective To comparatively study anti-free radical and cytoprotective effects of quercetin(Q) and its monoglucoside isoquercetin(I), diglucoside rutin(R), which differs only in glycosyl-substitution at C-3 position of the molecules, using anoxia/hypoglycemia-induced cell injury model and thereby to explore the structure-effect relationship thereto. Methods The cell injury model was established by HEK293 cells cultured in vitro with Na2S2O3 plus sugar-free Earle's fluid as incubation medium; Cell survival rate (CSR), total antioxidant capacity (TAC), SOD and LDH levels were determined; The effect intensity of the 3 flavonoids were compared by means of IC50, the concentration required to achieve 50% inhibition of the changes in the above indices in injured cells. Results Q, I and R all concentration-dependently elevated CSR, TAC and SOD, and reduced LDH level; the all of IC50s for the above indices were ranked in order of IC50,Q < IC50,I< IC50,R, namely, the effect intensity should be Q I R. Conclusions The 3 structurally similar flavoloids all have significant and concentration-dependent anti-free radical and cyto-protective effects with the intensity being in order of aglycone monoglucoside diglucoside; the substitution of -OH by sugar group at C-3 position of flavoloids and increase in the sugar -substituent number are associated with the effect intensity reduced;namely, the intensity of these effects of flavonoids is negatively related the substutution by sugar group at C-3 position.

  8. Salinization forced anoxia in the Sea of Aral, the Dead Sea and the Urmia Lake: a temporal feature of the salt lakes development under the Global Change?

    Science.gov (United States)

    Yakushev, Evgeniy; Ghaffari, Peygham; Zavialov, Petr; Kurbaniyazov, Abilgazi

    2016-04-01

    The Sea of Aral is undergone a process of its volume decrease and salinization started about 30 years ago. In the remained now lake in the former deepest part of the Sea the salinity increased from about 8 PSU in 1990 to 120 PSU in the surface layer, and 240 PSU in the bottom layer in 2015. On top of an increase of salinity, there was formed a sulfidic zone in the bottom layer, that was separated from the upper layer by an extremely strong halocline (more than 50 PSU in 100 cm). The reason of this halocline might be an influx of the heavy high salinity water formed in summer in the shallower part of the Aral Sea to the bottom layer of the deeper part of the Sea through a strait between them. The similar processes could take place in the Urmia Lake, where salinity increased from 120 PSU in 2000 to about 350-400 PSU in 2015. This lake also consists from a shallow and deep parts connected by a channel in the dam, and where there was also reported anoxia. And finally, the Dead Sea demonstrates a further development happened after the shallower Southern part of the Sea was totally evaporated. After 1993 the vertical mixing started to occur down to the bottom layer, and the lake regime changed from meromictic to monomictic, that resulted in aeration of the bottom layer. In this work we compare interannual changes of the main salinity components in the 3 water bodies and analyze results of the vertical chemical structure of the Sea of Aral studied in 2015.

  9. No evidence for anoxia during the Valanginian carbon isotope event—An organic-geochemical study from the Vocontian Basin, SE France

    Science.gov (United States)

    Kujau, Ariane; Heimhofer, Ulrich; Ostertag-Henning, Christian; Gréselle, Benjamin; Mutterlose, Jörg

    2012-07-01

    deposition under less oxygenated conditions for the Barrande layers. However, their occurrence clearly predates the onset of the positive δ13Ccarb shift (by about 180 kyrs). Contrary to the subsequent mid-Cretaceous CIEs, the occurrence of widespread anoxia associated with the Valanginian CIE cannot be confirmed for the Vocontian Basin.

  10. INFLUENCES OF HERBA CISTANCHE TEA ON THE ABILITY OF ANTI-FATIGUE AND ANOXIA ENDURANCE IN MICE%肉苁蓉茶对小鼠抗疲劳和耐缺氧能力的影响

    Institute of Scientific and Technical Information of China (English)

    彭亮; 覃辉艳; 赵鹏; 杨俊峰; 李彬; 张洁宏

    2011-01-01

    [Objective] To study the effects of Herba Cistanche tea on the ability of anoxia endurance and anti-fatigue in mice. [Methods] The extract of Herba Cistanche tea were consecutively orally give to mice with the doses of 3 333, 1 667 and 833 mg/kgBW (according to dry sample) for 35 days. Test of burdened swimming, lactic acid and usea nitrogen detecting were used to assess the function of anti-fatigue. Tests of anoxia endurance under normal pressure, being poisoned by sodium nitrite and acute lack of blood (cutting head) were used to assess the function of anoxia endurance. [Results] On the test condition, Herba Cistanche tea can prolong the time of burdened swimming, increase the hepatic glycogen reserve and decrease the lactic acid after swimming in mice. No significantly effect on usea nitrogen was observed in exhausted mice. It can prolong the survived time under anoxia condition and survived time after poisoned by sodium nitrite in mice. No significantly effect on the breathing time after head being cut was observed. [Conclusion] Herba Cistanche tea can enhance the function of anti-fatigue and anoxia endurance in mice.%[目的]研究内苁蓉茶对小鼠抗疲劳和耐缺氧能力的影响.[方法]分别以3 333、1 667、833 mg/kgBw剂量(以茶颗粒干品计)的肉苁蓉茶提取液,给小鼠连续灌胃35 d,通过负重游泳试验、尿素氮和肝糖原测定评价其抗疲劳功能,通过常压耐缺氧试验、亚硝酸钠中毒试验和急性脑缺血(断头)试验评价其耐缺氧功能.[结果]在本实验条件下,肉苁蓉茶能够延长小鼠的负重游泳时间,增加小鼠的肝糖原的储备量,减小小鼠运动后的血乳酸量,对疲劳小鼠的血清尿素氮无明显影响:肉苁蓉茶能够延长小鼠在常压下缺氧存活时间及硝酸钠中毒后的存活时间,对急性脑缺血(断头)后张口喘气时间无明显影响.[结论]肉苁蓉茶可以提高小鼠的抗疲劳能力和常压耐缺氧能力.

  11. 红景天功能饮料对小鼠抗疲劳和耐缺氧能力的影响%Effect of Functional Beverages of Rhodiola on Ability of Anti-Fatigue and Anoxia Endurance in Mice

    Institute of Scientific and Technical Information of China (English)

    王彦武; 赵鹏; 张洁宏; 李彬; 彭亮; 覃光球

    2014-01-01

    Objective To study the effect of functional beverages of rhodiola on the ability of anti-fatigue and anoxia endurance in mice .Methods Functional beverages of rhodiola was consecutively orally given to mice with the doses of 160,80 and 40 ml/kg for 30 days respectively.Test of burdened swimming ,and urea,hepatic glycogen and lactic acid determination were used to assess the function of anti-fatigue of mice .Tests of anoxia endurance under normal pressure ,sodium nitrite poisoning and acute cerebral ischemia ( decapitation ) were used to assess the function of anoxia endurance of mice .Results Compared with control group ,the mice in the high and middle dose groups showed a longer burdened swimming time(P<0.05);The serum urea content of mice decreased significantly (P<0.05),but the hepatic glycogen content increased in the high dose group (P<0.05).The area under curve of blood lactic acid all decreased in the three dose groups ( P<0 .05 ) .The mice in the high and middle dose groups showed a longer survival time under anoxia condition and a longer survival time after being poisoned by sodium nitrite ( P<0 .05 ) .The mice in the high dose group showed a longer breathing time after decapitation (P<0.01).Conclusion Functional beverages of rhodiola can contribute to imporve the function of anti-fatigue and anoxia endurance in mice .%目的:探讨红景天功能饮料对小鼠抗疲劳和耐缺氧能力的影响。方法分别以160、80、40 ml/kg剂量的红景天功能饮料给小鼠连续灌胃30 d ,通过负重游泳试验及检测血尿素、肝糖原和血乳酸水平评价各组小鼠的抗疲劳功能;通过常压耐缺氧实验、亚硝酸钠中毒实验和急性脑缺血(断头)实验评价各组小鼠耐缺氧功能。结果与给予纯水灌胃的对照组相比,高、中剂量组小鼠负重游泳时间明显延长(P<0.05);高剂量组小鼠的血清尿素含量显著降低(P<0.05),肝糖原含量增高(P<0.05);3

  12. 绕颈脐带螺距增加率与宫内缺氧三维彩超研究%The search on the increasing rate of pitch of screws of nuchal circular umbilical cord and fetal intrauterine anoxia by Three-dimension colour Doppler ultrasonography

    Institute of Scientific and Technical Information of China (English)

    刘天鑫; 武周燕; 王晓云; 王利平

    2011-01-01

    Objective: To evaluate the relation between the increased ratio of pitch of screws of nuchal circular umbilical cord and fetal intrauterine anoxia by detected the increased ratio of pitch of screws of nuchal circular umbilical cord with Three-dimension dolour Doppler ultrasonography. Methods: 115 fetuses with nuchal circular umbilical cord were examined the pitch of screws of nuchal circular umbilical cord and dissociated umbilical cord, the increased ratio between them were calculated. All fetuses were divided into anoxia group (42 cases) and non-anoxia group (73 cases) according to NST Score. The fetuses were tested by non stress test (NST) in order to observe the amniotic fluid and the fetal heart rate in the course of parturition after post partum. Results: The increased ratio of anoxia group [(0.37±0.07)%] was much more than the non-anoxia group [(0.20±0.01)%] (P<0.01). There also were significant differences in umbilical artery blood flow parameter S/D [anoxia group was (3.23±0.08), non-anoxia group was (2.27±0.11)], abnormal fetal heart rate and amniotic fluid [anoxia group had 23 cases (54.8%), non-anoxia group had 13 cases (17.8%)] between the two groups (all P<0.05). Conclusion: The increasing ratio of pitch of screws of nuchal circular umbilical cord detected by Three-dimension colour Doppler ultrasonography can imply fetal intrauterine anoxia in time, and can provide help for clinical early diagnosis and timely treatment.%目的:应用三维彩色多普勒超声检测绕颈脐带螺距增加率,探讨胎儿宫内缺氧与之相关性.方法:对我院115例脐带绕颈胎儿颈部及游离部脐带螺距进行测量,计算增加率.依据胎儿监护将胎儿分为缺氧组(42例)和非缺氧组(73例).胎儿行无应激试验,产后追踪羊水性状及产程中胎心率变化.结果:缺氧组和非缺氧组脐带螺距增加率分别为(0.37±0.07)%、(0.20±0.01)%,两者比较差异有高度统计学意义(P<0.01);缺氧组脐动脉血流收缩

  13. 疲消乐口服液对小鼠抗疲劳和耐缺氧作用的实验研究%Experimental Study of Pixiaole Oral Liquid on Anti-fatigue and Anti-anoxia Effects

    Institute of Scientific and Technical Information of China (English)

    李云宁; 程仁丽; 程静

    2012-01-01

    目的:研究疲消乐口服液抗疲劳和耐缺氧作用.方法:将昆明种小鼠随机分为疲消乐口服液高剂量组(50.50 g/kg)、中剂量组(16.84 g/kg)、低剂量组(8.42 g/kg)和空白对照组(等体积蒸馏水);疲消乐口服液高、中、低剂量组分别按生药剂量50.50、16.84、8.42 g/kg分组灌胃给药,空白对照组灌胃等体积蒸馏水,分别观察小鼠负重游泳持续时间;血清尿素氮及肝糖原、血乳酸的含量;常压耐缺氧小鼠存活时间.结果:疲消乐口服液高、中剂量组能明显延长小鼠负重游泳时间,与空白对照组比较,差异有统计学意义(P<0.05);疲消乐口服液高剂量组能明显降低小鼠运动时血清尿素氮和血乳酸的含量、升高肝糖原含量,与空白对照组比较,差异有统计学意义(P<0.05);疲消乐口服液高、中剂量组能明显延长小鼠常压耐缺氧的存活时间,与空白对照组比较,差异有统计学意义(P<0.05).结论:疲消乐口服液能延长小鼠负重游泳时间、降低小鼠运动时血清尿素氮和血乳酸的含量、升高肝糖原含量以及延长小鼠常压耐缺氧的存活时间.%Objective: To study the anti-fatigue and anti-anoxia effects of Pixiaole oral liquid. Methods: Kunming mice were randomly divided into Pixiaole Oral Liquid high-dose group (50.50 g/kg), middle-dose group (16.84 g/kg), low-dose group (8.42 g/kg) and blank control group (the same volume of distilled water), which were given Pixiaole oral liquid 50.50 g/kg, 16.84 g/kg, 8.42 g/kg and the same volume of distilled water respectively according to intragastric administration; and the loaded swimming duration, serum urea nitrogen and liver glycogen, blood lactic acid and hypoxia tolerance survival time of mice were observed. Results: The Pixiaole oral liquid high-dose group and middle-dose group can significantly prolong the loaded swimming time in mice(P<0.05); the high-dose group can reduce the content of serum urea

  14. Anti-free radical and cytoprotective effects of quercetin and its sugar-containing natural congeners in cultured HEK293 cells injured by anoxia/hypoglycemia and the structure-effect relationship thereto

    Institute of Scientific and Technical Information of China (English)

    JIN Yue; LU Yong; HAN Guo-zhu; YU Hong; JING Fong

    2008-01-01

    Objective To comparatively study anti-free radical and cytoprotective effects of quercetin (Q) and its monoglucoside isoquercetin (I), diglucoside rutin (R), which differs only in glycosyl-substitution at C-3 position of the molecules, using anoxia/hypoglycemia-induced cell injury model and thereby to explore the structure-effect relationship thereto. Methods The cell injury model was established by HEK293 cells cultured in vitro with Na2S2O3 plus sugar-free Earle's fluid as incubation medium. Cell survival rate (CSR), total antioxidant capacity (TAC), SOD and LDH levels were determined. The effect intensity of the 3 flavonoids was compared by means of IC50, the concentration required to achieve 50 % inhibition of the changes in the above indices in injured cells. Results Q, I and R all concentration-dependently elevated CSR, TAC and SOD and reduced LDH level. The all of IC50s for the above indices were ranked in order of IC50,QI>R. Conclusions The 3 structurally similar flavoloids all have significant and concentration-dependent anti-free radical and cyto-protective effects with the intensity being in order of aglycone>monoglucoside> diglucoside; the substitution of -OH by sugar group at C-3 position of flavoloids and increase in the sugar-substituent number are associated with the effect intensity reduced;namely, the intensity of these effects of flavonoids is negatively related the substutution by sugar group at C-3 position.

  15. 氯胺酮对缺氧诱导胎鼠大脑皮层神经元特异性烯醇化酶的影响%Effects of ketamine on anoxia induced neurone specific enolase release from cerebral cortex neurons of fetal rats

    Institute of Scientific and Technical Information of China (English)

    王惠军; 薛玉良; 李兰英; 高春霖

    2011-01-01

    concentrations of ketamine. Results With the extension of anoxia, the extracellular levels of NSE increased significantly , the intracellular increased significantly ( P < 0. 01). As for the one-hour oxygen-gluose deprivation group, the extracellular concentration of NSE decreased[anoxia 1 h group (4. 95 ±0.41) μg/L, anoxia 1 h + ketamine 1μmol/L group(4.43 ±0.36)μg/L, anoxia 1 h+ ketamine 20 μmol/L group (353 ±0. 46) μg/L, anoxia 1 h + ketamine 100 μmol/L(3.17 ±0.23) μg/L] , but the intracellular concentration NSE increased significantly with the increase of pretreated concentration of ketamine [anoxia 1 h group (22. 0 ±0. 76) μg/L, anoxia 1 h + ketamine 1 (μmol/L group(24.7 ±0. 84)(μg/L, anoxia 1 h+ ketamine 20μmol/L group(28. 8 ±0. 91) μg/L, anoxia 1 h + ketamine 100 (μmol/L (6. 39 ±0.92) μg/L] .presented a dose dependent. Until the maximum concentration of ketamine ( 100 μmol/L) , all of these indexes went back to close to normal level. With the extension of anoxia, the expression of NSE mRNA increased significantly ( relative expression quantity of NSE in control group was 0.15, oxygen 0. 5 h group 0. 65, P < 0. 01 ). After pretreated with different concentrations of ketamine ( 1 μmol/L and 20 μmol/L) , the value of each group went down( relative expression quantity of NSE were 0. 53 ,0. 28,respectively, P<0.01). All of these had significantly differences with control group(P< 0.01). Conclusion The results indicate that ketamine plays a protective role in neuron ischemic injury, which may be related to the protection of cell membrane and the regulation of expressions of NSE at transcriptional level.

  16. O uso de procedimentos de estruturação de rotina em indivíduos com anóxia cerebral: relato de caso Procedures to improve daily activities performance in individuals with cerebral anoxia: case report

    Directory of Open Access Journals (Sweden)

    PAULA A. R. GOUVEIA

    2000-06-01

    Full Text Available OBJETIVO: Apresentar um estudo de caso de reabilitação com procedimentos de estruturação de rotina para realização das atividades de vida diária (AVDs. PACIENTE: Quadro de anóxia cerebral, com déficit de memória verbal e visual, desorientação temporal, abulia e bradipsiquismo. MÉTODO: Estruturação de horários fixos na rotina diária; exposição a um calendário 3 vezes ao dia; caminhadas diárias; monitorização do familiar na execução de tarefas de auto cuidado, fornecendo auxílio mediante comandos verbais curtos e pistas específicas. RESULTADOS: Foram observados aumento da iniciativa, maior autonomia nas AVDs, diminuição do período de latência para qualquer resposta, melhora da atenção, orientação temporal e bradipsiquismo. CONCLUSÕES: Estratégias de controle do comportamento trazem ganhos e limitações para pacientes e familiares. Embora obriguem a adaptação a uma rotina pouco flexível, promovem o aprendizado através da automatização de procedimentos que se valem de mecanismos de memória implícita preservados. Estes recursos podem elevar o grau de autonomia do paciente em casa.OBJECTIVE: To present a rehabilitation case study; procedures to improve the performance on daily activities were used by the caregiver. PATIENT: Cerebral anoxia due to cardiac arrest. He presented memory deficits for both visual and verbal material, temporal disorientation, abulia, psychomotor slowing and bradypsychism. METHODS: daily activities were developed in fixed hours; calendar was presented 3 times a day ; daily walks were performed; self-care activities were performed by the patient with short verbal commands and cues from the caregiver. RESULTS: We observed improvement on initiative and autonomy for daily activities, attention, temporal orientation and bradypsychism. There was also reduction on response time. CONCLUSIONS: Behavioral control strategies result on improvement for patients and their family although limit

  17. sICAM- 1 and sVCAM- 1 levels in blood serum and gingival tissues in rabbits with periodontitis in analogic high altitude anoxia environment%模拟高原低氧兔牙周炎模型血清和牙龈组织中sICAM-1及sVCAM-1的含量

    Institute of Scientific and Technical Information of China (English)

    武曦; 黄镜静; 张纲; 谭颖徽; 高钰琪

    2012-01-01

    Objective: To investigate the expression of soluble inter-cellular adhesion molecules-1( sICAM-1 ) and soluble vascular adhesion molecular-1( sVCAM-1 ) in blood serum and gingival tissues in rabbits with periodontitis in high altitude anoxia environment. Methods: 40 male rabbits were randomly divided into four groups( n = 10 ): control and periodontitis groups in plain, control and periodontitis groups in plateau. The periodontitis models were established by ligation technique on the two central incisors of mandible and periodontitis diet. The anoxia groups were raised in a established condition of altitude at 5 000 meteres above sea level for eight weeks. sICAM-1 and sVCAM-1 levels in blood serum and gingival tissues were detected by ELISA. The morphology of the periodontal tissues were histologicaly observed. Results: More severe periodontitis was observed in anoxia periodontits groups. The concentrations of sl-CAM-1 and sVCAM-1 in anoxia periodontitis group were significantly higher than those in the other groups( P <0. 05 ), and the levels in gingival tissues were higher in blood serum. Conclusion: Cellular adhesion molecules are upregulated in anoxia environment at high altitude and may promotes the destruction of periodontal tissues and diffusion of inflammation into the peripheral blood vessels.%目的:探讨血清和牙龈组织中可溶性细胞间黏附分子- 1(sICAM- 1)、可溶性血管黏附分子- 1(sVCAM- 1)在高原牙周病炎症反应中的作用.方法:将40 只雄兔随机分为常氧对照组、常氧实验组、低氧对照组、低氧实验组,每组10 只,采用正畸丝结扎下颌中切牙与牙周炎食谱的方法建立牙周炎模型,常氧组和低氧组分别在平原和模拟海拔5 000 m条件下饲养8 周,对牙周组织取材进行组织学观察,用ELISA法检测各组实验动物血清和牙龈组织中sICAM- 1、sVCAM- 1表达情况.结果:低氧实验组sICAM- 1、sVCAM- 1浓度显著高于其余各组(P<0.05),且牙龈组

  18. Oceanic anoxia during the Late Permian: Evidence from pyrite morphology%二叠纪末期海洋缺氧:来自黄铁矿形态的证据

    Institute of Scientific and Technical Information of China (English)

    遇昊; 陈代钊; 韦恒叶; 汪建国; 常华进

    2011-01-01

    deposited from the extremely anoxic (even sulfidic )water columns within the intra-shelf basins (or depressions). The subsequent Permian-Triassic mass extinction could have been triggered by this extreme anoxia from the late Changxingian stage.

  19. 促红细胞生成素对大鼠脊髓运动神经元缺氧性损伤的保护作用%Protective Effect of Erythropoietin on Anoxia of Motoneurons after Spinal Cord Injury in Rats

    Institute of Scientific and Technical Information of China (English)

    胡杨; 秦文; 廉凯

    2014-01-01

    Objective To observe the protective effect of erythropoietin (EPO) on anoxia of motoneurons after spinal cord injury in rats. Methods The motoneuron was dissociated from neonate Wistar rats and cultivated in vitro with deprivation of oxygen in the medium. The changes of morphology were observed by phase-contrast microscopy, and the expression of EPO receptor (EPOR) was detected with West-ern blotting. The survival rate of motoneuron was measured with methyl thiazolyl tetrazolium (MTT) assay, and the level of lactate dehydro-genase (LDH) was observed. Results Compared with the control group, the expression of EPOR and the level of LDH increased (P<0.01), and the survival rate of motoneuron decreased (P<0.01) in the anoxia group. Compared with the anoxia group, the expression of EPOR and the level of LDH decreased (P<0.05), and the survival rate of motoneuron increased (P<0.01) in the EPO group, which was related with the level of EPO. Conclusion EPO could relieve the damage of motoneuron caused by anoxia, especially by upregulating EPOR.%目的:观察重组红细胞生成素(EPO)对大鼠脊髓运动神经元细胞缺氧性损伤的保护作用。方法对Wistar乳鼠脊髓运动神经元细胞进行原代分离培养,通过去除培养液中氧气来模拟脊髓缺氧。倒置显微镜下观察细胞形态变化,Western blotting检测EPO受体(EPOR)蛋白的表达,噻唑蓝(MTT)比色法及乳酸盐脱氢酶(LDH)活力测定观察加入不同浓度EPO对神经元细胞的保护作用。结果与正常对照组比较,缺氧组脊髓运动神经元缺氧后EPOR表达及LDH浓度明显增加(P<0.01),细胞存活率明显降低(P<0.01);与缺氧组比较, EPO组EPOR表达及LDH浓度降低(P<0.05),细胞存活率明显增强(P<0.01),且与浓度相关。结论EPO可减轻缺氧对运动神经元的损害,而EPOR表达上调可能是EPO发挥其对缺氧神经元保护作用的重要途径之一。

  20. Akt信号途径参与二氮嗪预处理抑制缺氧复氧损伤大鼠海马神经元的凋亡%Akt involved in diazoxide preconditioning against rat hippocampal neuronal apoptosis induced by anoxia-reoxygenation injury

    Institute of Scientific and Technical Information of China (English)

    刘荣国; 宋娜; 李捷萌; 崔翔; 陈彦青

    2010-01-01

    Objective Investigate whether preconditioning with diazoxide(DZ),a mitochondrial ATP-sensitive potassium channel opener,could enhance Akt protein to up-regulate Bcl-2/Bax protein ratio against apoptosis.Methods Cultured for 9-10 d in vitro,the hippocampat neurons of Sprague-Dawley rats were assigned to the following 5 groups randomly:Control(Group A),Anoxia(Group B),Anoxia+DZ100 μmoL/L(Group C),Anoxia+DZ100 μmol/L+5-hydroxydecanoate(Group D),Anoxia+DZ100 μmol/L+LY294002 50 μmol/L(Group E).Prior to oxygen deprivation,the hippocampal neurons were treated with DZ for 1 h per day and this treatment was persisted for 3 d.Each experiment was repeated for three times and each group contained 16 wells or 2 dishes of neurons for each time.Thereafter,neurons were derived of oxygen for 4 h.At 48 h of reoxygenation the neuronal optical density(A)were measured by MTT method,while the apoptotic rates were assayed by annexin V-FITC staining.The expressions of Akt,Bcl-2 and Bax proteins were detected and evaluated by Western blot.Results Compared with other pretreatment,DZ 100 μmoL/L led to the elevation of A,whereas promoted the decrease of apoptotic rate(P < 0.05).Compared with those in other anoxic groups,the expressions of Akt protein and Bcl-2 protein in Group C were increased significantly(P <0.05),whereas the Bax density were reduced significantly(P < 0.05).Preceding administration of 100 μmol/L DZ took protective effects on the neurons induced by anoxia-reoxygenation.Conclusions DZ 100 μmol/L increased Akt protein to up-regulate Bcl-2/Bax protein ratio against apoptosis induced by anoxia-reoxygenation.%目的 探讨二氮嗪(DZ)预处理能否通过上调Akt信号增强Bcl-2表达、抑制Bax表达发挥抗凋亡作用.方法 离体培养9~10 d SD大鼠海马神经元分为正常对照组(A组)、缺氧组(B组)、缺氧+DZ 100 μmol/L组(c组)、缺氧+DZ 100 μmol/L+5-羟癸酸100 μmol/L组(D组)、缺氧+DZ 100 μmol/L+LY294002 50

  1. Animal experiment of the fatigue-resisting and anoxia-resisting actions of pholidota chinensis lindl%石仙桃抗疲劳和耐缺氧作用的动物实验

    Institute of Scientific and Technical Information of China (English)

    刘建新; 周俐; 周青; 连其深

    2006-01-01

    BACKGROUND: Pholidota chinensis lindl (PCL) has been used in folk medicine to treat pulmonary edema, resolve phlegm, relieve cough and resist fatigue. However, its pharmacological effects on hypoxic-ischemic heart and brain damage remain to be unclear.OBJECTIVE: To investigate the effects of PCL extract on survival duration of 5 kinds of anoxia models as well as anti-fatigue and anti-hypoxia actions.DESIGN: Randomized and controlled experiment.SETTING: Pharmacological Department of Garnnan Medical College.MATERIALS: The experiment was performed in the Pharmacological Department of Gannan Medical College frgm March to June 2004. A total of 170 Kunming mice, 25 males and 95 females, weighing (20±2) g, were provided by the Experimental Animal Center of Gannan Medical College.METHODS:①Hypoxia-resisting test:Totally 40 mice were randomly divided into 4 groups: normal saline group, hydrochloric propranolol group (0.02 g/kg), and 5 g/kg and 10 g/kg PCL extract groups, with 10 in each group. Twenty minutes after administration, the mice were put into hypoxic wide-mouthed bottles of 250 mL volume with sodalime for recording survival time with stopwatch. ② Test of specific anoxic myocardium: Totally 30 mice were randomly divided into 3 groups with 10 in each, namely normal saline + isoproterenol group, 10 g/kg PCL extract + isoproterenol group, and hydrochloric propranolol (0.02 g/kg) + isoproterenol group.0.015 g/kg isoproterenol was given to mice in each group. Forty minutes after administration, the mice were put into hypoxic wide-mouthed bottles of 250 mL volume with sodalime for recording survival time with stopwatch. ③ Test of NaNO2-induced hypoxia: Forty mice were randomly divided into 4 groups: normal saline group, hydrochloric propranolol group (0.02 g/kg), 5 g/kg and 10 g/kg PCL extract groups, with 10 in each group. Forty minutes after administration, the mice were intraperitoneally injected with 200 mg/kg NaNO2. The survival time was recorded.④Test of

  2. The Effects of Shenhua Tablet Compound on the Location of NaDC1 in Renal Tubular Epithelial Cells with Anoxia/reoxygenation%复方肾华片对缺氧/复氧肾小管上皮细胞NaDC1转运蛋白定位的影响

    Institute of Scientific and Technical Information of China (English)

    魏日胞; 杨悦; 张雪光; 方谦; 张玉强

    2013-01-01

    Objective:To observe the effect of the Shenhua-containing serum on the location of Sodium-dependent dicarboxylate transporter 1 (NaDC1) in the renal tubular epithelial cells of rats.Methods:After 3 days of continuous intragastric drug administration,male Wistar rats were sacrificed and Shenhua-containing serum has been prepared and separated.Renal tubular epithelial cells (RTECs) were divided into a normal serum-GFP-empty plasmid group,a normal serum-GFP-NaDC1 plasmid group,a Shenhua-containing serum-GFP-empty plasmid group and a Shenhua-containing serum-GFP-NaDC1 plasmid group.After anoxia/reoxygenation,immunofluorescence and immunoblot were performed.Results:Immunofluorescence examinations revealed a widened distribution of NaDC1 in normal serum-GFP-empty plasmid group,normal serum-GFP-NaDC1 plasmid group and Shenhua-containing serum-GFP-empty plasmid group,in Shenhua-containing serum-GFP-NaDC1 plasmid group,NaDC1 was distributed at membrane.Immunoblot show that approximately 90% of the NaDC1 was expressed at the basolateral membrane of RTECs in Shenhua-containing serum-GFP-NaDC1 plasmid group,whereas other three groups were expressed on the apical and basolateral surfaces at the nearly equal level.Conclusion:The Shenhua-containing serum effectively promoted the recovery of the polarity of RTECs caused by anoxia/reoxygenation.%目的:观察复方肾华含药血清对缺氧/复氧模型肾小管上皮细胞钠/二羧酸协同转运蛋白1(NaDC1)的定位影响.方法:雄性wistar大鼠,灌胃给药3d后处死,分离含药血清备用.分离培养大鼠肾小管上皮细胞,随机分4组:正常血清GFP空质粒组、正常血清GFP-NaDC1质粒组、肾华含药血清GFP空质粒组和肾华含药血清GFP-NaDC1质粒组,分别进行质粒转染后,在正常培养基或肾华含药血清培养基中培养,进行缺氧/复氧处理后应用免疫荧光和生物素化免疫印迹技术观察肾小管上皮细胞NaDC1的分布变化及表达.结果:免疫荧光结

  3. Seasonal anoxia over the western Indian continental shelf

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Naik, H.; Jayakumar, A.; Pratihary, A.K.; Narvenkar, G.; Kurian, S.; Agnihotri, R.; Shailaja, M.S.; Narvekar, P.V.

    . An examination of data sub- sequently collected by the National Institute of Oceanogra- phy (presented as Supplementary Information in Naqvi et al. [2000]) also shows that the subsurface environment was denitrifying but not sulfate reducing at least until... by the phytoplankton, thus allowing their ex- port to open coastal waters, supplementing supply through upwelling and contributing to the high PP over the inner and mid-shelf regions [Naqvi et al., 2006b]. The DIN concentra- tion in rainwater in Goa is of a similar...

  4. Tissue anoxia - a key factor in seagrass mortality?

    DEFF Research Database (Denmark)

    Borum, Jens; Zieman, Jay; Frankovich, Tom M;

    Abstractet er offentliggjort i Schedule and Abstracts til det 7. international seagrass biology workshop - er ikke tilgængelig online.......Abstractet er offentliggjort i Schedule and Abstracts til det 7. international seagrass biology workshop - er ikke tilgængelig online....

  5. SAR11 bacteria linked to ocean anoxia and nitrogen loss

    DEFF Research Database (Denmark)

    Tsementzi, Despina; Wu, Jieying; Deutsch, Samuel;

    2016-01-01

    Bacteria of the SAR11 clade constitute up to one half of all microbial cells in the oxygen-rich surface ocean. SAR11 bacteria are also abundant in oxygen minimum zones (OMZs), where oxygen falls below detection and anaerobic microbes have vital roles in converting bioavailable nitrogen to N2 gas...... activity. These results link SAR11 to pathways of ocean nitrogen loss, redefining the ecological niche of Earth’s most abundant organismal group....

  6. Large Igneous Province Volcanism, Ocean Anoxia and Marine Mass Extinction

    DEFF Research Database (Denmark)

    Ruhl, Micha; Bjerrum, Christian J.; Canfield, Donald;

    2013-01-01

    T) and (FePY/ FeHR)] and redox-sensitive trace element concentrations (e.g. Mo, V etc.) show that the Triassic-Jurassic marine mass extinction directly coincides with a rapid shift to anoxic and euxinic conditions at the onset of CAMP volcanism and increased atmospheric pCO2. Biotic recovery after...... the extinction event only commences when redox-conditions return from a euxinic to a ferruginous state and stabilization of marine ecosystems only commences after decreasing atmospheric pCO2 and a return to more oxic marine conditions. Iron-speciation at both the Triassic-Jurassic and Permian-Triassic mass...

  7. SAR11 bacteria linked to ocean anoxia and nitrogen loss

    DEFF Research Database (Denmark)

    Tsementzi, Despina; Wu, Jieying; Deutsch, Samuel;

    2016-01-01

    Bacteria of the SAR11 clade constitute up to one half of all microbial cells in the oxygen-rich surface ocean. SAR11 bacteria are also abundant in oxygen minimum zones (OMZs), where oxygen falls below detection and anaerobic microbes have vital roles in converting bioavailable nitrogen to N2 gas....... Anaerobic metabolism has not yet been observed in SAR11, and it remains unknown how these bacteria contribute to OMZ biogeochemical cycling. Here, genomic analysis of single cells from the world’s largest OMZ revealed previously uncharacterized SAR11 lineages with adaptations for life without oxygen...

  8. DNA damage in human endothelial cells after irradiation in anoxia

    International Nuclear Information System (INIS)

    Endothelial cells and fibroblasts have been reported to respond differently to oxidative stress. Both the effects of high oxygen tension and radiation involve the action of free radicals. DNA damage (single strand breaks, SSB, and double strand breaks, DSB) was assayed in human umbilical cord vein (HUV) cells and in Chinese hamster fibroblasts (V79) after irradiation under oxic or anoxic conditions. The cells were exposed to single doses in the range of 2-18 Gy of γ-radiation from 60Co. Significantly more DNA damage was induced in the V79 cells than in the HUV cells. As a consequence, a higher oxygen enhancement ratio was obtained for the HUV cells (6.3) as compared to the V79 cells (2.8). The repair of SSB was slower in the HUV cells than in the V79 cells, irrespective of oxic state. For the higher doses, the damage remaining at 60 min after anoxic irradiation, i.e. DSB, was only detected in the V79 cells. (orig.)

  9. Production of dimethylsulphide during the seasonal anoxia off Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Shenoy, D.M.; Sujith, K.B.; Gauns, M.; Patil, S.; Sarkar, Amit; Naik, H.; Narvekar, P.V.; Naqvi, S.W.A.

    of hydrogen sulphide. However, total dimethylsulphoniopropionate, total dimethylsulphoxide and methanethiol concentrations were quite low and unlikely to account for the DMS build-up through presently known pathways of DMS production. While there are several...

  10. SAR11 bacteria linked to ocean anoxia and nitrogen loss

    Science.gov (United States)

    Tsementzi, Despina; Wu, Jieying; Deutsch, Samuel; Nath, Sangeeta; Rodriguez-R, Luis M.; Burns, Andrew S.; Ranjan, Piyush; Sarode, Neha; Malmstrom, Rex R.; Padilla, Cory C.; Stone, Benjamin K.; Bristow, Laura A.; Larsen, Morten; Glass, Jennifer B.; Thamdrup, Bo; Woyke, Tanja; Konstantinidis, Konstantinos T.; Stewart, Frank J.

    2016-08-01

    Bacteria of the SAR11 clade constitute up to one half of all microbial cells in the oxygen-rich surface ocean. SAR11 bacteria are also abundant in oxygen minimum zones (OMZs), where oxygen falls below detection and anaerobic microbes have vital roles in converting bioavailable nitrogen to N2 gas. Anaerobic metabolism has not yet been observed in SAR11, and it remains unknown how these bacteria contribute to OMZ biogeochemical cycling. Here, genomic analysis of single cells from the world’s largest OMZ revealed previously uncharacterized SAR11 lineages with adaptations for life without oxygen, including genes for respiratory nitrate reductases (Nar). SAR11 nar genes were experimentally verified to encode proteins catalysing the nitrite-producing first step of denitrification and constituted ~40% of OMZ nar transcripts, with transcription peaking in the anoxic zone of maximum nitrate reduction activity. These results link SAR11 to pathways of ocean nitrogen loss, redefining the ecological niche of Earth’s most abundant organismal group.

  11. Oceanic anoxia at the Precambrian-Cambrian boundary

    Science.gov (United States)

    Kimura, Hiroto; Watanabe, Yoshio

    2001-11-01

    The Precambrian-Cambrian (PC-C) boundary separates fossils representing two discrete evolutionary phases: the Neoproterozoic soft-bodied Ediacarian biotas and Cambrian small shelly faunas. The biological discontinuity is suspected to have been a result of mass extinction; however, recent discoveries of the Ediacarian biotas in Cambrian sediments have led to an understanding that the faunal change was gradual through the PC-C transition. Th/U ratios, which are high in oxidizing conditions and low in reducing conditions, show a considerable positive correlation with δ13C values at all studied sites of the PC-C boundary. This correlation indicates that reported δ13C variation across the PC-C boundary from numerous localities corresponds to redox variation in the depositional environment. The negative δ13C anomaly that occurs worldwide at the PC-C boundary, therefore, corresponds to the widespread development of an oxygen-deficient shallow marine environment. This finding suggests that widespread oceanic oxygen deficiency, which has been interpreted to reflect Phanerozoic mass extinction events, also occurred immediately before the Cambrian explosion.

  12. Effect of calcitonin gene-related peptide on anoxia-reoxygenation induced injury to neonatal rat cardiomyocytes incubated in high glucose medium%降钙素基因相关肽对高糖下新生大鼠心肌细胞缺氧复氧损伤的影响

    Institute of Scientific and Technical Information of China (English)

    陈璐; 赵鑫; 郭政

    2014-01-01

    each):normal glucose medium control group (NG group),high glucose medium group (HG group),high glucose medium + A/R group (HG+ A/R group),high glucose medium + A/R + CGRP group (HG + A/R + CGRP group),and high glucose medium + A/R + CGRP+ CGRP8-37 group (HG + A/R + CGRP + CGRP8-37 group).The cells were incubated in normal glucose (5.5 mmol/L) medium for 72 h in NG group.In HG group,the cells were incubated in high glucose (25.0 mmol/L) medium for 72 h.In HG + A/ R group,the cells were incubated in high glucose medium for 72 h and then exposed to 3 h of anoxia followed by 2 h of reoxygenation.In group HG + A/R + CGRP,the cells were incubated in high glucose medium for 72 h,CGRP (final concentration 10-8 mol/L) was then added to the culture media and the cells were incubated for 1 h and then underwent A/R.In HG + A/R + CGRP + CGRP8-37 group,the cells were incubated in high glucose medium for 72 h,CGRP (final concentration 10 8 mol/L) was then added to the culture media and the cells were incubated for 1 h and then underwent A/R.In HG + A/R + CGRP + CGRP8-37 group,the cells were incubated in high glucose medium for 72 h,CGRP8-37 (final concentration 10-8 mol/L) and CGRP8-37 (CGRP receptor antagonist,final concentration 10-7 mol/L) was then added to the culture media and the cells were incubated for 1 h and then underwent A/R.Apoptosis in cardiomyocytes was detected using TUNEL and apoptosis index (AI) was calculated.The lactate dehydrogenase (LDH) activity in the culture medium was analyzed.Results AI and LDH activity were significantly higher in HG group than in NG group,and in HG + A/R group than in HG group.Compared with HG + A/R group,AI and LDH activity were significantly decreased in HG + A/R + CGRP group,while no significant changes were found in HG + A/R + CGRP + CGRP8-37 group.Compared with HG + A/R + CGRP group,AI and LDH activity were significantly increased in HG + A/R + CGRP + CGRP8-37 group.Conclusion CGRP attenuates A/R-induced injury to neonatal rat

  13. Anoxia over the western continental shelf of India: Bacterial indications of intrinsic nitrification feeding denitrification

    Digital Repository Service at National Institute of Oceanography (India)

    Krishnan, K.P.; Fernandes, S.O.; LokaBharathi, P.A.; KrishnaKumari, L.; Nair, S.; Pratihary, A.K.; Rao, B.R.

    .98, p is less than 0.001, n = 122) was significant compared to the latter with nitrite and nitrate. The occurrence of high ammonium under low phosphate conditions corroborates our observations that ammonium does not appear to be locked under low oxygen...

  14. Phloem unloading in tobacco sink leaves: insensitivity to anoxia indicates a symplastic pathway.

    Science.gov (United States)

    Turgeon, R

    1987-05-01

    Phloem unloading in transition sink leaves of tobacco (Nicotiana tabacum L.) was analyzed by quantitative autoradiography. Detectable levels of labeled photoassimilates entered sink leaves approx. 1 h after source leaves were provided with (14)CO2. Samples of tissue were removed from sink leaves when label was first detected and further samples were taken at the end of an experimental phloem-unloading period. The amount of label in veins and in surrounding cells was determined by microdensitometry of autoradiographs using a microspectrophotometer. Photoassimilate unloaded from first-, second-and third-order veins but not from smaller veins. Import termination in individual veins was gradual. Import by the sink leaf was completely inhibited by exposing the sink leaf to anaerobic conditions, by placing the entire plant in the cold, or by steam-girdling the sink-leaf petiole. Phloem unloading was completely inhibited by cold; however, phloem unloading continued when the sink-leaf petiole was steam girdled or when the sink leaf was exposed to a N2 atmosphere. Compartmental efflux-analysis indicated that only a small percentage of labeled nutrients was present in the free space after unloading from sink-leaf veins in a N2 atmosphere. The results are consistent with passive symplastic transfer of photoassimilates from phloem to surrounding cells. PMID:24227272

  15. Zn and Ni Isotope Systematics in the Black Sea, an Analogue for Past Ocean Anoxia

    Science.gov (United States)

    Little, S. H.; Vance, D.; Cameron, V.; Rijkenberg, M. J. A.; Andersen, M. B.; Lyons, T. W.

    2014-12-01

    Organic rich sediments, indicators of low bottom water oxygen, are often enriched in trace metals. Their concentrations in such sediments are thus used to probe past Earth surface conditions. Enrichment mechanisms are difficult to distinguish from concentrations alone, however. A range of processes fractionate metal stable isotopes, offering the potential to unpick these controls. The Black Sea is the classic modern analogue for past euxinia. Deep euxinic waters (dissolved sulfide ≤380mM) underlie a surface oxic layer and redoxcline at 80-250m. It is an ideal starting point to explore the behaviour of metal stable isotopes in low oxygen conditions. We report water column and sedimentary Zn and Ni data. A maximum in dissolved Zn (~3nM) occurs at the upper boundary of the redoxcline, probably reflecting cellular uptake above and sulfide co-precipitation below. Water column dissolved Ni concentrations remain within a narrow range throughout (9-12nM), with subtle variations in the redoxcline associated with Fe-Mn cycling and interaction with sulfide. Significant Zn and Ni isotopic variation (ca 1.5‰) is observed associated with these concentration variations. In the strongly sulfidic deep waters, Zn and Ni are homogeneous and isotopically heavy: [Zn] = 0.40 ± 0.05nM, δ66Zn = 0.96 ± 0.05‰, [Ni] = 10.7 ± 0.7nM, δ58Ni = 1.86 ± 0.16‰ (n=6, 1sd), suggesting preferential removal of light isotopes to the particulate phase. Sediments underlying oxic waters show no authigenic enrichment and isotope ratios close to crustal values (δ60Ni ~ 0.2‰, δ66Zn ~ 0.3‰). In contrast, Ni and Zn are enriched in sediments underlying the euxinic portion of the water column (by factors of 2-3). Authigenic Ni isotope values are light (δ60Niauth = 0.30 ± 0.21‰, n=13, 1sd) compared to the deep Black Sea water column, consistent with removal of light isotopes to the particulate phase. This may reflect sorption to Mn oxides, or co-precipitation with sulfide. Authigenic Zn isotope values in these sediments are also light (δ66Znauth = 0.57 ± 0.07‰) compared to the deep Black Sea dissolved pool. Unlike Ni, however, removal of Zn is close to quantitative. This is seen in low Zn concentrations in deep waters and in the similarity of the euxinic sedimentary Zn isotopic composition to the likely dominant input, open ocean seawater (at ~0.5‰).

  16. Effects of anoxia during gamma irradiation of face fly fertility and viability (Diptera: Muscidae)

    International Nuclear Information System (INIS)

    Irradiating 6-d-old Musca autumnalis DeGeer pupae in nitrogen with 500-2.500 rads did not affect adult emergence, female fecundity, or male competitiveness. Male and female fertility decreased with increased dose, reaching about 1% at 2.500 rads. Egg to adult survival upon back crossing irradiated males or females to unirradiated flies was only 7% at 1.500 rads and 0.7% at 2.000 rads. Doses of up to 2.000 rads did not affect male survival, but males treated with 2.500 rads had reduced survival rates. These results are better than those with irradiation in air and indicate that irradiation with 1.800-2.000 rads in nitrogen would maximize dominate lethality and minimize fitness loss. (author). 28 refs. 4 tbs. 2 figs

  17. Early Triassic alternative ecological states driven by anoxia, hyperthermals, and erosional pulses following the end-Permian mass extinction

    Science.gov (United States)

    Pietsch, C.; Petsios, E.; Bottjer, D. J.

    2015-12-01

    The end-Permian mass extinction, 252 million years ago, was the most devastating loss of biodiversity in Earth's history. Massive volcanic eruptions of the Siberian Traps and the concurrent burning of coal, carbonate, and evaporite deposits emplaced greenhouse and toxic gasses. Hyperthermal events of the surface ocean, up to 40°C, led to reduced gradient-driven ocean circulation which yielded extensive equatorial oxygen minimum zones. Today, anthropogenic greenhouse gas production is outpacing carbon input modeled for the end-Permian mass extinction, which suggests that modern ecosystems may yet experience a severe biotic crisis. The Early Triassic records the 5 million year aftermath of the end-Permian mass extinction and is often perceived as an interval of delayed recovery. We combined a new, high resolution carbon isotope record, sedimentological analysis, and paleoecological collections from the Italian Werfen Formation to fully integrate paleoenvironmental change with the benthic ecological response. We find that the marine ecosystem experienced additional community restructuring events due to subsequent hyperthermal events and pulses of erosion. The benthic microfauna and macrofauna both contributed to disaster communities that initially rebounded in the earliest Triassic. 'Disaster fauna' including microbialites, microconchids, foraminifera, and "flat clams" took advantage of anoxic conditions in the first ~500,000 years, dominating the benthic fauna. Later, in the re-oxygenated water column, opportunistic disaster groups were supplanted by a more diverse, mollusc-dominated benthic fauna and a complex ichnofauna. An extreme temperature run-up beginning in the Late Dienerian led to an additional hyperthermal event in the Late-Smithian which co-occurred with increased humidity and terrestrial run-off. Massive siliciclastic deposits replaced carbonate deposition which corresponds to the infaunalization of the benthic fauna. The disaster taxa dominated community may represent an alternative ecological state. However, subsequent environmental changes including the return of an oxygenated water column, increased sea surface temperatures, and sedimentary influx led to continued restructuring of the benthic fauna throughout the Early Triassic.

  18. Paleoredox chemistry of Cenomanian–Coniacian black shales at high paleolatitudes: Implications for the extent of anoxia during OAE2

    DEFF Research Database (Denmark)

    Lenniger, Marc; Nøhr-Hansen, Henrik; Hills, Len V;

    2013-01-01

    is reflected by a positive carbon isotope excursion (CIE) in the terrestrial and marine record. Whereas the paleoredox conditions in low and mid-paleolatitudes are well constrained for OAE2, data from high paleolatitudes are still scarce. The paleoceanographic response at high paleolatitudes during OAE2...... was intermittently suboxic to anoxic (ferruginous) throughout most of the latest Cenomanian–Coniacian. Despite very high TOC (>10%) and hydrogen index values, molybdenum concentrations are relatively low during OAE2 but increase after the event. This suggests a global drawdown of the seawater molybdenum reservoir...

  19. Evolution and Production of Calcareous Nannoplankton During the Cretaceous as Proxies of LIP-induced Oceanic Fertilization, Acidification and Anoxia

    Science.gov (United States)

    Erba, E.; Bottini, C.; Tiraboschi, D.

    2008-12-01

    Through the Phanerozoic, biota have been intimately linked to Earth's degassing inducing major changes in composition and structure of the ocean-atmosphere system. Emplacement of large igneous provinces (LIPs) has been the primary natural source of atmCO2 with dramatic consequences on climate and ecosystems. During the mid-Cretaceous the Ontong Java-Manihiki and Caribbean Plateaus LIPs are recognized as responsible of pCO2 as high as 2000 ppm. Coeval biocalcification crises occurred in pelagic and neritic settings, suggesting a causal link between high concentrations of carbon dioxide and drops in benthic and planktonic calcifiers' efficiency. Within the oceanic biosphere, calcareous nannoplankton play a key-role as: (1) is widespread and consists of cosmopolitan and endemic taxa; (2) has a 220 My-long evolutionary history; (3) is one the most effective calcite producers; (4) is relevant for the C cycle; (5) is extremely sensitive to environmental variations. Diversity pulses of Cretaceous calcareous nannoplankton are grossly coeval with LIP construction, climate and sea-level changes, variations in ocean structure and composition, suggesting that evolutionary patterns are closely linked to environmental modifications. We explored time-intervals of LIP formation marked by nannoplankton adaptation/evolution, quantifying evolutionary rates, species richness, abundance, calcite production and morphometry. High-resolution investigations of the initial phase of both early Aptian oceanic anoxic event (OAE) 1a and latest Cenomanian OAE 2 pointed out major evolutionary changes, decreases in heavily calcified nannoliths and occurrence of dwarf coccoliths. Nannoplankton calcification crises and dwarfism is here interpreted as forced by rapidly increasing pCO2 during formation of the Ontong Java-Maniniki and Caribbean Plateaus. Alternatively or concurrently, calcification crash and dwarfism might result from enhanced fertility associated to OAE1a and OAE2 regardless of ocean alkalinity. However, such global nutrification episodes must be linked as well to LIP construction via supply of biolimiting metals. Contrary to common reasoning, we stress the fact that emplacement of Cretaceous LIPs did not cause extinctions among calcareous nannoplankton.

  20. Metabolic-State-Dependent Remodeling of the Transcriptome in Response to Anoxia and Subsequent Reoxygenation in Saccharomyces cerevisiae†

    OpenAIRE

    Lai, Liang-Chuan; Kosorukoff, Alexander L.; Burke, Patricia V.; Kwast, Kurt E.

    2006-01-01

    We conducted a comprehensive genomic analysis of the temporal response of yeast to anaerobiosis (six generations) and subsequent aerobic recovery (≈2 generations) to reveal metabolic-state (galactose versus glucose)-dependent differences in gene network activity and function. Analysis of variance showed that far fewer genes responded (raw P value of ≤10−8) to the O2 shifts in glucose (1,603 genes) than in galactose (2,388 genes). Gene network analysis reveals that this difference is due large...

  1. Studies on the causes of mortality of the estuarine bivalve Macoma balthica under conditions of (near) anoxia

    NARCIS (Netherlands)

    De Zwaan, A.; Babarro, J.M.F.

    2001-01-01

    Survival of the bivalve Macoma balthica in (near) anoxic seawater was studied in a static system and a flow-through system and compared with emersed exposure to air and NZ In the static system, a decrease in pH and exponential accumulation of sulphide in the incubation medium were observed, indicati

  2. Pushing the limit: Examining factors that affect anoxia tolerance in a single genotype of adult D. melanogaster

    OpenAIRE

    Raquel Benasayag-Meszaros; Monica G. Risley; Priscilla Hernandez; Margo Fendrich; Ken Dawson-Scully

    2015-01-01

    Drosophila melanogaster is a promiscuous species that inhabits a large range of harsh environments including flooded habitats and varying temperature changes. To survive these environments, fruit flies have adapted mechanisms of tolerance that allow them to thrive. During exposure to anoxic stress, fruit flies and other poikilotherms enter into a reversible, protective coma. This coma can be manipulated based on controlled environmental conditions inside the laboratory. Here we utilize a comm...

  3. Increased marine production of N sub(2)O due to intensifying anoxia on the Indian continental shelf

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Jayakumar, D.A.; Narvekar, P.V.; Naik, H.; Sarma, V.V.S.S.; DeSouza, W.; Joseph, S.; George, M.D.

    . The intensification of one of the largest low-oxygen zones in the ocean, which develops naturally over the western Indian continental shelf during late summer and autumn is reported here. The highest accumulations yet observed of hydrogen sulphide (H sub(2)S...

  4. Paleogene biomarker records from the central Arctic Ocean (Integrated Ocean Drilling Program Expedition 302): Organic carbon sources, anoxia, and sea surface temperature

    Science.gov (United States)

    Weller, Petra; Stein, Ruediger

    2008-03-01

    During Integrated Ocean Drilling Program Expedition 302 (Arctic Coring Expedition (ACEX)) a more than 200 m thick sequence of Paleogene organic carbon (OC)-rich (black shale type) sediments was drilled. Here we present new biomarker data determined in ACEX sediment samples to decipher processes controlling OC accumulation and their paleoenvironmental significance during periods of Paleogene global warmth and proposed increased freshwater discharge in the early Cenozoic. Specific source-related biomarkers including n-alkanes, fatty acids, isoprenoids, carotenoids, hopanes/hopenes, hopanoic acids, aromatic terpenoids, and long-chain alkenones show a high variability of components, derived from marine and terrestrial origin. The distribution of hopanoic acid isomers is dominated by compounds with the biological 17β(H), 21β(H) configuration indicating a low level of maturity. On the basis of the biomarker data the terrestrial OC supply was significantly enriched during the late Paleocene and part of the earliest Eocene, whereas increased aquatic contributions and euxinic conditions of variable intensity were determined for the Paleocene-Eocene thermal maximum and Eocene thermal maximum 2 events as well as the middle Eocene time interval. Furthermore, samples from the middle Eocene are characterized by the occurrence of long-chain alkenones, high proportions of lycopane, and high ratios (>0.6) of (n-C35 + lycopane)/n-C31. The occurrence of C37-alkenenones, which were first determined toward the end of the Azolla freshwater event, indicates that the OC becomes more marine in origin during the middle Eocene. Preliminary U37K'-based sea surface temperature (SST) values display a long-term temperature decrease of about 15°C during the time interval 49-44.5 Ma (25° to 10°C), coinciding with the global benthic δ18O cooling trend after the early Eocene climatic optimum. At about 46 Ma, parallel with onset of ice-rafted debris, SST (interpreted as summer temperatures) decreased to values <15°C. For the late early Miocene a SST of 11°-15°C was determined. Most of the middle Eocene ACEX sediments are characterized by a smooth short-chain n-alkane distribution, which may point to natural oil-type hydrocarbons from leakage of petroleum reservoirs or erosion of related source rocks and redeposition.

  5. Combined marine δ88/86Sr and 87Sr/86Sr record supports global anoxia as a cause for P/T mass extinction

    Science.gov (United States)

    Vollstaedt, H.; Eisenhauer, A.; Boehm, F.; Fietzke, J.; Krabbenhöft, A.; Liebetrau, V.; Wallmann, K. J.; Farkas, J.

    2011-12-01

    The biggest mass extinction within the Phanerozoic Eon occurred at the Permian/Triassic (P/T) boundary and is characterized by up to 96% loss in species accompanied with the demise of the Paleozoic faunal community. Recently, five major mechanisms are consulted to explain the mass extinction in terrestrial and marine environment. However, a geochemical quantification of carbonate burial rates during this biotic turnover is still remaining. By extending the conventional radiogenic isotope system by a simultaneous measurement of radiogenic and stable strontium (Sr) isotopes (δ88/86Sr) we are able to add new constraints to the seawater chemistry including quantitative information about the Sr output flux of the ocean, mainly represented by marine carbonates. Consequently, variations in δ88/86Sr becoming a suitable tool to investigate in the global carbonate budget in earth's history including the biotic turnover of calcifying organisms at stratigraphic boundaries which are expected to have a large influence on Sr geochemistry and isotope composition of seawater. In order to examine variations in the marine Sr isotope composition through Earth's history paired 88Sr/86Sr-87Sr/86Sr-ratios of 104 Phanerozoic brachiopods, belemnites and carbonate matrix samples are determined. Applying the fractionation factor of our carbonate recording phase we constructed a δ88/86Srseawater record. The most noteworthy observation is the occurrence of the two global extrema in δ88/86Sr values of the whole Phanerozoic within the last 20Ma years of the Paleozoic prior to the P/T boundary. This corresponds to an increase of δ88/86Srseawater of 0.000249 Ma-1 in the latest Permian indicating a strong disturbance in the Sr budget of the ocean. To interpret our observations and to compare them to existing scenarios for the P/T boundary we applied a one-box, isotope mass balance model of the oceanic Sr cycle connected to a mass balance model of Ca. Our results show a high strontium output flux from the ocean by marine carbonates and sulfates corresponding to an excess calcium output flux of 2.2x1019mol within the last 13Ma of the Permian period. This is explained by enhanced evaporate deposition and carbonate precipitation from hydrogen carbonate derived by Bacterial Sulfate Reduction (BSR) in an anoxic and stratified ocean. The model results support a kill mechanism triggered by an overturn of anoxic deep waters in a stratified ocean.

  6. Organic matter provenance, palaeoproductivity and bottom water anoxia during the Cenomanian/Turonian oceanic anoxic event in the Newfoundland Basin (northern proto North Atlantic Ocean)

    NARCIS (Netherlands)

    van Bentum, E.C.; Reichart, G.J.; Sinninghe Damsté, J.S.

    2012-01-01

    Free and sulfur-bound biomarkers in sediments deposited in the northern proto North Atlantic (Newfoundland Basin, ODP Site 1276) during the Cenomanian-Turonian oceanic anoxic event 2 (OAE-2) were studied. The delta C-13 records of phytane and lycopane confirmed the stratigraphic position of the posi

  7. Organic matter provenance, palaeoproductivity and bottom water anoxia during the Cenomanian/Turonian oceanic anoxic event in the Newfoundland Basin (northern proto North Atlantic Ocean)

    NARCIS (Netherlands)

    Bentum, E.C. van; Reichart, G.-J.; Sinninghe Damsté, J.S.

    2012-01-01

    Free and sulfur-bound biomarkers in sediments deposited in the northern proto North Atlantic (Newfoundland Basin, ODP Site 1276) during the Cenomanian-Turonian oceanic anoxic event 2 (OAE-2) were studied. The δ 13C records of phytane and lycopane confirmed the stratigraphic position of the positive

  8. Study on effects of anti-anoxia of baikal skullcap root%中药黄芩抗缺氧作用研究

    Institute of Scientific and Technical Information of China (English)

    高卫; 蒋秀芳; 范春梅; 郑菊花; 王丹

    2006-01-01

    目的:为探讨黄芩水提物的抗缺氧作用,用小鼠制备模型进行耐缺氧研究.方法:采用小鼠常压缺氧模型、对抗异丙肾上腺素模型、对抗亚硝酸钠动物模型,腹腔注射黄芩水提物,测定其存活时间.结果:黄芩水提物能显著延长常压缺氧条件下小鼠的存活时间(P<0.01);能显著延长腹腔注射异丙肾上腺素小鼠在常压缺氧条件下的存活时间(P<0.01);对小鼠亚硝酸钠中毒无明显的缓解作用(P>0.05).结论:黄芩水提物具有增强小鼠耐缺氧能力的作用.

  9. Water column anoxia, enhanced productivity, and concomitant changes in δ13C and δ34S across the Frasnian-Famennian boundary (Kowala - Holy Cross Mountains/Poland)

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Joachimski, M.M.; Ostertag-Henning, C.; Pancost, R.D.; Strauss, H.; Freeman, K.; Littke, R.; Racki, G.

    2001-01-01

    The investigation of the trace element and organic geochemistry of the Frasnian Famennian boundary section at Kowala (Holy Cross Mountains/Poland) shows that the lower water column was oxygen-deficient during late Frasnian and early Famennian times. The abundance and carbon isotopic composition of d

  10. Effects of Anoxia and Post-Anoxia on Reactive Oxygen Species (ROS) and Antioxidant Enzymes in Tuber Mitochondria of Potato (Solanum tuberosum L.)%缺氧及氧恢复对马铃薯块茎线粒体中活性氧及抗氧化酶的影响

    Institute of Scientific and Technical Information of China (English)

    王芳; 孙周平; 刘义玲

    2014-01-01

    选用马铃薯‘Favorita,品种,采用淹水及淹水后恢复通气的方法,研究了缺氧及氧恢复条件对马铃薯块茎亚细胞水平线粒体中活性氧(ROS)及抗氧化酶的影响.结果表明:缺氧胁迫会导致块茎线粒体中超氧阴离子(O2-)的发生速率、过氧化氢(H2O2)及丙二醛(MDA)的含量先升高后下降,其中在缺氧第1天时分别比对照升高43.95%、49.18%、69.20%,在缺氧第3天时各项指标均达到最大值;而缺氧胁迫下超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)、过氧化氢酶(CAT)活性呈现先降低、后升高、再降低的趋势,其中缺氧第1天分别比对照降低28.35%、31.48%、37.36%.氧恢复时O;发生速率,H2O2及MDA含量,SOD、APX、CAT的活性同样呈现先升高后降低的趋势,其中与缺氧ld未恢复对照相比,氧恢复1d分别提高144.69%、63.45%、59.07%、39.29%、11.45%、2.88%.另外,上述各项指标因缺氧胁迫与氧恢复时间的不同而有较大的变化.由此推测:氧恢复比缺氧胁迫更能促进马铃薯块茎线粒体ROS的爆发,加剧膜脂过氧化,并增强线粒体抗氧化酶的短时防御性能.

  11. Reactive oxygen species are important mediators of taurine release from skeletal muscle cells

    DEFF Research Database (Denmark)

    Ørtenblad, Niels; Feveile Young, Jette; Oksbjerg, Niels;

    2003-01-01

    C2C12, calcium, cell volume regulation, 5-lipoxygenase, melittin, anoxia, secretory phospholipase A2......C2C12, calcium, cell volume regulation, 5-lipoxygenase, melittin, anoxia, secretory phospholipase A2...

  12. TREATMENT OF DYEING WASTEWATER BY PROCESS OF ANOXIA-AEROBE-PRESS FILTRATION-OXYGEN ENRICHED BIOCARBON%缺氧-好氧-亚滤-富氧生物炭工艺处理印染废水

    Institute of Scientific and Technical Information of China (English)

    肖利; 刘振鸿; 陈季华

    2002-01-01

    简要介绍了采用缺氧-好氧-亚滤-富氧生物炭工艺对上海某漂染厂印染废水处理工程进行技改的情况.处理量2 500m3/d,进水CODCr 600~1 200mg/L、色度300~600倍、pH 11~13.经过一年多的运行结果说明了该工艺处理效果稳定、耐冲击负荷,对难生化的印染废水处理及老工艺工程改造是合理可行的.

  13. 鲁斯可皂苷元对小鼠脑缺血缺氧的保护作用%Protective Effect of Ruscogenin on Cerebral Anoxia and Ischemia-reperfusion Injury in Mice

    Institute of Scientific and Technical Information of China (English)

    颜景峰; 李金平; 寇俊萍; 余伯阳

    2010-01-01

    目的 研究鲁斯可皂苷元(Ruscogenin,Rus)对小鼠脑缺血缺氧的保护作用.方法 采用小鼠断头致全脑缺血缺氧模型,通过观察小鼠断头呼吸维持时间,考察鲁斯可皂苷元抗脑缺氧活性及其量效时效关系;采用双侧颈总动脉结扎再灌注模型,考察鲁斯可皂苷元对脑组织含水量、丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性及Na+-K+-ATP酶活性、Ca2+-ATP酶活性等生化指标的影响.结果 Rus 3~27 mg/kg灌胃给药1次,可显著延长小鼠断头后呼吸维持时间;给予Rus 9 mg/kg时,1 h即可明显延长小鼠断头后呼吸维持时间,2 h达到作用高峰,保护作用持续到8 h;Rus可明显降低反复缺血再灌注模型小鼠脑含水量,减少脑组织MDA含量,增加SOD活性、Na+-K+-ATPase活性和Ca2+-ATPase活性.结论 Rus在一定剂量范围内,明显改善小鼠脑缺血缺氧损伤,减轻缺血再灌注导致的脑水肿、氧化损伤和能量代谢障碍,具有起效较快,维持时间较长的作用特点.

  14. Study on Extraction of Polysaccharides from Saffron and Anti-anoxia Ability%番红花多糖的提取及耐缺氧能力研究

    Institute of Scientific and Technical Information of China (English)

    陈波

    2014-01-01

    以番红花为原料,研究番红花多糖的响应面提取优化及耐缺氧能力.结果表明:番红花多糖提取最佳工艺条件为超声波功率为253.5 W,超声波时间为31.9 min,乙醇质量分数为83.9%,液料比值为16.4 (mL/g).同时,番红花多糖低剂量组、中剂量组和高剂量组与对照组比较,在常压缺氧条件下,小鼠存活时间分别延长了7.79%,10.9%和16.66%;在亚硝酸钠所致缺氧条件下,小鼠存活时间分别延长了20.71%,26.31%和37.06%,表明番红花多糖具有较好的耐缺氧能力.

  15. Geochemical characterisation of Tithonian-Berriasian Chia Gara organic-rich rocks in northern Iraq with an emphasis on organic matter enrichment and the relationship to the bioproductivity and anoxia conditions

    Science.gov (United States)

    Mohialdeen, Ibrahim M. J.; Hakimi, Mohammed Hail

    2016-02-01

    Tithonian-Berriasian Chia Gara organic-rich rocks, located in Kurdistan (northern Iraq), were analysed based on inorganic and organic geochemistry to define the origin, type of organic matter, and the influencing factors of organic matter (OM) enrichment, including the OM input and preservation, and their relationship to the paleoenvironment conditions. The δ13Corg values of the Chia Gara rocks range from -29.99‰ to -26.93‰, with average values of approximately -28.8‰, indicating that the organic matter has a predominantly marine origin. Enhanced biological productivity within the photic zone of the water column during deposition of the Chia Gara Fm. is indicated by consistently high organic carbon content in most samples (average 3 wt.%), as well as by bulk geochemical and biomarker characteristics. Major contributions by aquatic algae and microorganisms with a minor terrigenous organic matter contribution are indicated by the n-alkane distribution patterns and the composition of the hopanoids, steroids, and tricyclic terpenoids. Strongly reducing bottom water is indicated by low pristane/phytane ratios, homohopane distribution patterns, and the redox-sensitive trace elements geochemistry. Salinity stratification with alkaline bottom waters is indicated by high Sr/Ba ratios and the presence of gammacerane in the analysed Chia Gara samples. These data indicate that OM enrichment in the Tithonian-Berriasian Chia Gara rocks results from the combination of enhanced biological productivity and salinity stratification with anoxic bottom water conditions, which favoured OM preservation.

  16. Sediment features, macrozoobenthic assemblages and trophic relationships ({delta}{sup 13}C and {delta}{sup 15}N analysis) following a dystrophic event with anoxia and sulphide development in the Santa Giusta lagoon (western Sardinia, Italy)

    Energy Technology Data Exchange (ETDEWEB)

    Magni, P. [CNR-IAMC National Research Council - Institute for Coastal Marine Environment c/o IMC - International Marine Centre, Loc. Sa Mardini, Torregrande, 09072 Oristano (Italy); IMC - International Marine Centre, Loc. Sa Mardini, Torregrande, 09072 Oristano (Italy)], E-mail: paolo.magni@iamc.cnr.it; Rajagopal, S. [Department of Animal Ecology and Ecophysiology, Institute for Water and Wetland Research, Radboud University Nijmegen, Toernooiveld, 6525 ED Nijmegen (Netherlands); Velde, G. van der [Department of Animal Ecology and Ecophysiology, Institute for Water and Wetland Research, Radboud University Nijmegen, Toernooiveld, 6525 ED Nijmegen (Netherlands); National Museum of Natural History Naturalis, P.O. Box 9517, 2300 RA Leiden (Netherlands); Fenzi, G. [IMC - International Marine Centre, Loc. Sa Mardini, Torregrande, 09072 Oristano (Italy); Kassenberg, J. [Department of Animal Ecology and Ecophysiology, Institute for Water and Wetland Research, Radboud University Nijmegen, Toernooiveld, 6525 ED Nijmegen (Netherlands); Vizzini, S.; Mazzola, A. [Dipartimento di Biologia Animale, Universita di Palermo, via Archirafi 18, 90123 Palermo (Italy); Giordani, G. [Dipartimento di Scienze Ambientali, Universita di Parma, Via Usberti 33/A, 43100 Parma (Italy)

    2008-07-01

    Macrozoobenthic assemblages and stable carbon ({delta}{sup 13}C) and nitrogen ({delta}{sup 15}N) isotope values of various primary producers (macroalgae and angiosperms) and consumers (macroinvertebrate filter/suspension feeders, deposit feeders, detritivores/omnivores and carnivores and fishes) were studied in the Santa Giusta lagoon (Sardinia, Italy) before (spring) and after (autumn) a dystrophic event which occurred in the summer of 2004. A few days after the dystrophy, the physico-chemical characteristics of sediments and macrozoobenthic assemblages were also investigated. In the latter occasion, high total organic carbon (3.9%) and organic matter (15.9%) contents of surface sediments went together with peaks in acid-volatile sulphide concentrations. Certain immediate effects were quite extreme, such as the drastic reduction in macrozoobenthos and the massive fish kill in August 2004. Among the macrozoobenthos, there were few individuals of chironomid larvae and Capitella cf. capitata left. However, by October, chironomid larvae were numerous, indicating a lack of predators (e.g. fish) and competitors. In addition, some bivalve species and polychaetes which were absent, or present in small numbers before the event, became relatively numerous. The results are discussed based on a knowledge of the sulphide tolerance of these species. Stable isotope analysis clearly showed that the basal level of the food web for most consumers consisted mainly of macroalgae and sedimentary organic matter, and that the values before and after the dystrophic event were not significantly different from one another. This indicates that the relations among different trophic levels were quickly restored following the dystrophic event.

  17. Sediment features, macrozoobenthic assemblages and trophic relationships (delta13C and delta15N analysis) following a dystrophic event with anoxia and sulphide development in the Santa Giusta lagoon (western Sardinia, Italy).

    Science.gov (United States)

    Magni, P; Rajagopal, S; van der Velde, G; Fenzi, G; Kassenberg, J; Vizzini, S; Mazzola, A; Giordani, G

    2008-01-01

    Macrozoobenthic assemblages and stable carbon (delta(13)C) and nitrogen (delta(15)N) isotope values of various primary producers (macroalgae and angiosperms) and consumers (macroinvertebrate filter/suspension feeders, deposit feeders, detritivores/omnivores and carnivores and fishes) were studied in the Santa Giusta lagoon (Sardinia, Italy) before (spring) and after (autumn) a dystrophic event which occurred in the summer of 2004. A few days after the dystrophy, the physico-chemical characteristics of sediments and macrozoobenthic assemblages were also investigated. In the latter occasion, high total organic carbon (3.9%) and organic matter (15.9%) contents of surface sediments went together with peaks in acid-volatile sulphide concentrations. Certain immediate effects were quite extreme, such as the drastic reduction in macrozoobenthos and the massive fish kill in August 2004. Among the macrozoobenthos, there were few individuals of chironomid larvae and Capitella cf. capitata left. However, by October, chironomid larvae were numerous, indicating a lack of predators (e.g. fish) and competitors. In addition, some bivalve species and polychaetes which were absent, or present in small numbers before the event, became relatively numerous. The results are discussed based on a knowledge of the sulphide tolerance of these species. Stable isotope analysis clearly showed that the basal level of the food web for most consumers consisted mainly of macroalgae and sedimentary organic matter, and that the values before and after the dystrophic event were not significantly different from one another. This indicates that the relations among different trophic levels were quickly restored following the dystrophic event. PMID:18093619

  18. 牛磺酸对小鼠的抗缺氧作用和红细胞保护作用初探%Effect of Taurine on Anti-anoxia and Erythrocyte Protection of Mice

    Institute of Scientific and Technical Information of China (English)

    刘淑英; 曹雯; 魏智清

    2007-01-01

    采用常压密闭缺氧及化学性缺氧模型,研究了牛磺酸对小鼠的抗缺氧作用,并测定了牛磺酸对血红蛋白含量和红细胞数的影响,同时就牛磺酸对H2O2诱导的小鼠红细胞溶血作用的影响做了初步探讨.结果表明,牛磺酸能显著延长常压密闭缺氧小鼠的存活时间,但不能延长氰化钾、亚硝酸钠中毒缺氧小鼠的存活时间.牛磺酸对小鼠血红蛋白含量与红细胞数均无影响,但对H2O2诱导的小鼠红细胞溶血具有明显的抑制作用.

  19. Neuronas y ganglios vegetativos

    OpenAIRE

    Iglesias Rozas, José Rafael, 1942-

    1982-01-01

    Tres imágenes de ganglios y neuronas en las meninges. Se incluye una imagen de hemorragia subaracnoidea con anoxia. Three pictures of ganglia and nerve cells in the meninges. There is also a picture of a subarachnoidal hemorrhage with anoxia.

  20. Direct observation of the phosphate acceptor and phosphagen pool sizes in vivo

    NARCIS (Netherlands)

    Van Waarde, A; van den Thillart, G; Verhagen, M; Erkelens, C; Addink, A; Lugtenburg, J

    1990-01-01

    Earthworms were subjected to environmental anoxia (200 min) and electrical stimulation (5 min, 6 V, 50 Hz). The levels of high-energy phosphate compounds and the intracellular pH were monitored during anoxia, muscular contraction, and recovery by in vivo phosphorus-31 nuclear magnetic resonance (31P

  1. Effects of GDNF and HSV-GDNF on Bcl-2 expression of rat spinal cord motoneurons after anoxia%GDNF和HSV-GDNF对培养的大鼠脊髓运动神经元缺氧后的Bcl-2表达的影响

    Institute of Scientific and Technical Information of China (English)

    鄂玲玲; 周长满; 徐忠涛

    2002-01-01

    目的:观察细胞胶质源性神经营养因子(Glial cell line-derived neurotrophicfactor,GDNF)和单纯疱疹病毒介导的GDNF(GDNF transfomed bv herpes simplex virus vector,HSV-GDNF)对体外培养的大鼠脊髓运动神经元缺氧复氧时的作用和Bcl-2表达的影响.方法:观察缺氧2 h、4 h和缺氧4 h后恢复供氧24、72 h时,脊髓运动神经元存活数,并用抗Bcl-2抗血清行免疫组织化学染色,对Bcl-2免疫反应阳性神经元作平均光密度分析.结果:经GDNF、HSV-GDNF孵育的脊髓运动神经元缺氧-复氧后Bcl-2表达较对照组明显增强,神经元损伤程度减轻,神经元存活数明显高于对照组,且HSV-GDNF组的效果更好.结论:GDNF、HSV-GDNF对缺氧-复氧的大鼠脊髓运动神经元有保护作用,HSV-GDNF比GDNF更能增强缺氧-复氧后脊髓运动神经元Bcl-2的表达,提高神经元存活数,抑制缺氧后神经元的死亡.

  2. EXPERIMENTAL RESEARCH ON CO-CULTIVATION OF BONE MARROW MESENCHYMAL STEM CELLS MODIFIED BY GDNF GENE AND NEURONS SUBJECTED TO ANOXIA-REOXYGENATION%在GDNF基因修饰的骨髓基质细胞与缺氧复氧神经细胞的共培养中神经细胞凋亡的变化

    Institute of Scientific and Technical Information of China (English)

    熊怀林; 杨朝鲜; 高小青; 邓莉

    2011-01-01

    目的:探讨胶质源性神经营养因子(GDNF)基因修饰的骨髓基质细胞(BMSCs)对缺氧复氧神经细胞的保护作用.方法:GDNF基因修饰的BMSCs(BMSCs/GDNF)经诱导后与缺氧复氧神经细胞共培养,采用Hoechst33258检测神经细胞凋亡在共培养细胞中的表达.结果:BMSCs/GDNF组的神经细胞凋亡率显著低于BMSCs组和缺氧组(P<0.05).结论:BMSCs/GDNF通过抑制缺氧复氧神经细胞凋亡发挥神经保护作用.

  3. Correlation of cardiac performance with cellular energetic components in the oxygen-deprived turtle heart

    DEFF Research Database (Denmark)

    Stecyk, Jonathan; Bock, Christian; Overgaard, Johannes;

    2009-01-01

    of an anoxia-tolerant vertebrate, the freshwater turtle (Trachemys scripta) during long-term anoxia exposure ( 3 h at 21°C and 11 days at 5°C). During anoxia, phosphocreatine (PCr), unbound levels of inorganic phosphate (effective Pi2–), intracellular pH (pHi), and free energy of ATP hydrolysis (d......G/d ) exhibited asymptotic patterns of change, indicating that turtle myocardial high-energy phosphate metabolism and energetic state are reset to new, reduced steady states during long-term anoxia exposure. At 21°C, anoxia caused a reduction in pHi from 7.40 to 7.01, a 69% decrease in PCr and a doubling...

  4. Palaeoclimate: Aptian mystery solved

    Science.gov (United States)

    Stoll, Heather M.

    2016-02-01

    The volcanic eruption that created the Ontong Java Plateau released large quantities of carbon dioxide. A reconstruction of CO2 concentrations suggests that the eruption promoted climate change and the expansion of ocean anoxia.

  5. Hypoxia and Hydrogen Sulfide (H2S) in Padilla Bay, WA from 2014-07-09 to 2014-09-30 (NCEI Accession 0156596)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Hypoxia has the potential to be a stressor to eelgrass as it can lead to tissue anoxia at night. These tissues then must undergo anaerobic metabolism, which is less...

  6. Acute mountain sickness

    Science.gov (United States)

    High altitude cerebral edema; Altitude anoxia; Altitude sickness; Mountain sickness; High altitude pulmonary edema ... Acute mountain sickness is caused by reduced air pressure and lower oxygen levels at high altitudes. The faster you ...

  7. Variability of subsurface denitrification and surface productivity in the coastal eastern Arabian Sea over the past seven centuries

    Digital Repository Service at National Institute of Oceanography (India)

    Agnihotri, R.; Kurian, S.; Fernandes, M.; Reshma, K.; DeSouza, W.; Naqvi, S.W.A

    Temporal variations over the last approx. 700 years in surface productivity and subsurface denitrification in the coastal eastern Arabian Sea (off Goa, India), a hydrographically unique environment that experiences seasonal near-bottom anoxia, have...

  8. Cerebral Hypoxia

    Science.gov (United States)

    ... Enhancing Diversity Find People About NINDS NINDS Cerebral Hypoxia Information Page Synonym(s): Hypoxia, Anoxia Table of Contents ( ... Trials Organizations Publicaciones en Español What is Cerebral Hypoxia? Cerebral hypoxia refers to a condition in which ...

  9. Heterogeneous oxygenation resulting from active and passive flow in two Mediterranean sponges, Dysidea avara and Chondrosia reniformis

    NARCIS (Netherlands)

    Schlappy, M.L.; Weber, M.; Mendola, D.; Hoffmann, F.; Beer, de D.

    2010-01-01

    The oxygen dynamics and pumping behavior in Dysidea avara and Chondrosia reniformis (Porifera, Demospongiae) were investigated using oxygen microelectrodes and heated thermistor flow sensors. Both field and laboratory experiments showed the common occurrence of low oxygenation approaching anoxia in

  10. Deferoxamine prevents cerebral glutathione and vitamin E depletions in asphyxiated neonatal rats: role of body temperature.

    Science.gov (United States)

    Kletkiewicz, Hanna; Nowakowska, Anna; Siejka, Agnieszka; Mila-Kierzenkowska, Celestyna; Woźniak, Alina; Caputa, Michał; Rogalska, Justyna

    2016-01-01

    Hypoxic-ischaemic brain injury involves increased oxidative stress. In asphyxiated newborns iron deposited in the brain catalyses formation of reactive oxygen species. Glutathione (GSH) and vitamin E are key factors protecting cells against such agents. Our previous investigation has demonstrated that newborn rats, showing physiological low body temperature as well as their hyperthermic counterparts injected with deferoxamine (DF) are protected against iron-mediated, delayed neurotoxicity of perinatal asphyxia. Therefore, we decided to study the effects of body temperature and DF on the antioxidant status of the brain in rats exposed neonatally to critical anoxia. Two-day-old newborn rats were exposed to anoxia in 100% nitrogen atmosphere for 10 min. Rectal temperature was kept at 33 °C (physiological to rat neonates), or elevated to the level typical of healthy adult rats (37 °C), or of febrile adult rats (39 °C). Half of the rats exposed to anoxia under extremely hyperthermic conditions (39 °C) were injected with DF. Cerebral concentrations of malondialdehyde (MDA, lipid peroxidation marker) and the levels of GSH and vitamin E were determined post-mortem, (1) immediately after anoxia, (2) 3 days, (3) 7 days, and (4) 2 weeks after anoxia. There were no post-anoxic changes in MDA, GSH and vitamin E concentrations in newborn rats kept at body temperature of 33 °C. In contrast, perinatal anoxia at elevated body temperatures intensified oxidative stress and depleted the antioxidant pool in a temperature-dependent manner. Both the depletion of antioxidants and lipid peroxidation were prevented by post-anoxic DF injection. The data support the idea that hyperthermia may extend perinatal anoxia-induced brain lesions.

  11. Quiescence in Artemia franciscana embryos: reversible arrest of metabolism and gene expression at low oxygen levels.

    Science.gov (United States)

    Hand, S C

    1998-04-01

    Depression of the production and consumption of cellular energy appears to be a prerequisite for the survival of prolonged bouts of anoxia. A correlation exists between the degree of metabolic depression under anoxia and the duration of anoxia tolerance. In the case of brine shrimp (Artemia franciscana) embryos, oxygen deprivation induces a reversible quiescent state that can be tolerated for several years with substantial survivorship. A global arrest of cytoplasmic translation accompanies the transition into anoxia, and rates of protein synthesis in mitochondria from these embryos appears to be markedly reduced in response to anoxia. Previous evidence suggests that the acute acidification of intracellular pH (pHi) by over 1.0 unit during the transition into anoxia contributes to the depression of biosynthesis, but message limitation does not appear to play a role in the down-regulation in either cellular compartment. The ontogenetic increase in mRNA levels for a mitochondrial-encoded subunit of cytochrome c oxidase (COX I) and for nuclear-encoded actin is blocked by anoxia and aerobic acidosis (artificial quiescence imposed by intracellular acidification under aerobic conditions). Further, the levels of COX I and actin mRNA do not decline appreciably during 6 h bouts of quiescence, even though protein synthesis is acutely arrested across this same period. Thus, the constancy of mRNA levels during quiescence indicates that reduced protein synthesis is not caused by message limitation but, instead, is probably controlled at the translational level. This apparent stabilization of mRNA under anoxia is mirrored in an extension of protein half-life. The ubiquitin-dependent pathway for protein degradation is depressed under anoxia and aerobic acidosis, as judged by the acute drop in levels of ubiquitin-conjugated proteins. Mitochondrial protein synthesis is responsive to both acidification of pHi and removal of oxygen per se. Matrix pH declines in parallel with pHi, and

  12. The Influence of the Biological Pump on Marine Redox Conditions During Earth History

    Science.gov (United States)

    Meyer, K. M.; Ridgwell, A.; Payne, J.

    2015-12-01

    Evidence for bottom-water anoxia on the continental shelves waned over the course of the Phanerozoic, which may be influenced by secular changes in the biological pump that led to weaker positive feedbacks within the oceans. The biological pump describes the transfer of carbon from the atmosphere to the deep ocean, which creates vertical gradients in nutrients and oxygen, both important influences in the structure of marine ecosystems. We used the cGENIE Earth system model to quantitatively test the hypothesis that reductions in the efficiency of the nutrient recycling loop of the biological pump during the past 550 Ma reduced the extent of anoxia on the shelves and acted as an important control on marine animal ecosystems. When the modeled remineralization depth is shallow relative to the modern ocean, anoxia tends to be more widespread at continental shelf depths. As the modeled remineralization depth increases toward modern conditions, anoxia is less prevalent and occurs at depths below the continental shelves. Reduced marine productivity in the closed system configuration of cGENIE cannot produce the frequent bottom-water anoxia conditions envisioned for the Paleozoic. We hypothesize that evidence for greater animal abundance and metabolic demand during the Phanerozoic was driven by progressive oxygenation of shelf environments related to changes in the biological pump rather than greater food availability. In general, these model simulations suggest changes in the depth distribution of organic carbon remineralization may have controlled observed shifts in ocean chemistry, biogeochemical cycling, and ecosystem structure during the Phanerozoic.

  13. Glycogen Fuels Survival During Hyposmotic-Anoxic Stress in Caenorhabditis elegans.

    Science.gov (United States)

    LaMacchia, John C; Frazier, Harold N; Roth, Mark B

    2015-09-01

    Oxygen is an absolute requirement for multicellular life. Animals that are deprived of oxygen for sufficient periods of time eventually become injured and die. This is largely due to the fact that, without oxygen, animals are unable to generate sufficient quantities of energy. In human diseases triggered by oxygen deprivation, such as heart attack and stroke, hyposmotic stress and cell swelling (edema) arise in affected tissues as a direct result of energetic failure. Edema independently enhances tissue injury in these diseases by incompletely understood mechanisms, resulting in poor clinical outcomes. Here, we present investigations into the effects of osmotic stress during complete oxygen deprivation (anoxia) in the genetically tractable nematode Caenorhabditis elegans. Our findings demonstrate that nematode survival of a hyposmotic environment during anoxia (hyposmotic anoxia) depends on the nematode's ability to engage in glycogen metabolism. We also present results of a genome-wide screen for genes affecting glycogen content and localization in the nematode, showing that nematode survival of hyposmotic anoxia depends on a large number of these genes. Finally, we show that an inability to engage in glycogen synthesis results in suppression of the enhanced survival phenotype observed in daf-2 insulin-like pathway mutants, suggesting that alterations in glycogen metabolism may serve as a basis for these mutants' resistance to hyposmotic anoxia.

  14. Aquaporins-2 and -4 regulate glycogen metabolism and survival during hyposmotic-anoxic stress in Caenorhabditis elegans.

    Science.gov (United States)

    LaMacchia, John C; Roth, Mark B

    2015-07-15

    Periods of oxygen deprivation can lead to ion and water imbalances in affected tissues that manifest as swelling (edema). Although oxygen deprivation-induced edema is a major contributor to injury in clinical ischemic diseases such as heart attack and stroke, the pathophysiology of this process is incompletely understood. In the present study we investigate the impact of aquaporin-mediated water transport on survival in a Caenorhabditis elegans model of edema formation during complete oxygen deprivation (anoxia). We find that nematodes lacking aquaporin water channels in tissues that interface with the surrounding environment display decreased edema formation and improved survival rates in anoxia. We also find that these animals have significantly reduced demand for glycogen as an energetic substrate during anoxia. Together, our data suggest that reductions in membrane water permeability may be sufficient to induce a hypometabolic state during oxygen deprivation that reduces injury and extends survival limits.

  15. Ischemia/reperfusion mediated oxygen free radical production in rat brain endothelium

    Energy Technology Data Exchange (ETDEWEB)

    Grammas, P.; Wood, K. (Univ. of Oklahoma, Oklahoma City (United States)); Liu, G.J.; Floyd, R.A. (Oklahoma Medical Research Foundation, Oklahoma City (United States)); Wood, K. (Univ. of Oklahoma Health Sciences Center, Oklahoma City (United States) Oklahoma Medical Research Foundation, Oklahoma City (United States))

    1991-03-11

    Oxygen free radicals have been increasingly implicated in ischemia/reperfusion mediated injury to tissue. Recent methods of assessing tissue oxygen free radical flux including spin trapping, salicylate hydroxylation, protein oxidation and specific enzymatic activity loss have clearly shown that ischemia/reperfusion mediates oxidative damage in brain. Vascular endothelia cells are increasingly implicated in inactivating oxidative damage. The authors have used salicylate to assess hydroxyl free radical flux during an anoxia-reoxygenation insult in isolated brain microvessels. Brain microvessels that were subjected to a 20 min anoxia period and then reoxygenated for 20 min hydroxylated salicylate to form tissue localized 2,3-dihydroxybenzoic acid (2,3-DHBA) whereas microvessels that remained oxygenated throughout contained very little 2,3-DHBA. The data suggest that anoxia/reoxygenation of microvessels produces tissue localized hydroxyl free radical flux.

  16. Scavenging ROS dramatically increase NMDA receptor whole-cell currents in painted turtle cortical neurons.

    Science.gov (United States)

    Dukoff, David James; Hogg, David William; Hawrysh, Peter John; Buck, Leslie Thomas

    2014-09-15

    Oxygen deprivation triggers excitotoxic cell death in mammal neurons through excessive calcium loading via over-activation of N-methyl-d-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. This does not occur in the western painted turtle, which overwinters for months without oxygen. Neurological damage is avoided through anoxia-mediated decreases in NMDA and AMPA receptor currents that are dependent upon a modest rise in intracellular Ca(2+) concentrations ([Ca(2+)]i) originating from mitochondria. Anoxia also blocks mitochondrial reactive oxygen species (ROS) generation, which is another potential signaling mechanism to regulate glutamate receptors. To assess the effects of decreased intracellular [ROS] on NMDA and AMPA receptor currents, we scavenged ROS with N-2-mercaptopropionylglycine (MPG) or N-acetylcysteine (NAC). Unlike anoxia, ROS scavengers increased NMDA receptor whole-cell currents by 100%, while hydrogen peroxide decreased currents. AMPA receptor currents and [Ca(2+)]i concentrations were unaffected by ROS manipulation. Because decreases in [ROS] increased NMDA receptor currents, we next asked whether mitochondrial Ca(2+) release prevents receptor potentiation during anoxia. Normoxic activation of mitochondrial ATP-sensitive potassium (mKATP) channels with diazoxide decreased NMDA receptor currents and was unaffected by subsequent ROS scavenging. Diazoxide application following ROS scavenging did not rescue scavenger-mediated increases in NMDA receptor currents. Fluorescent measurement of [Ca(2+)]i and ROS levels demonstrated that [Ca(2+)]i increases before ROS decreases. We conclude that decreases in ROS concentration are not linked to anoxia-mediated decreases in NMDA/AMPA receptor currents but are rather associated with an increase in NMDA receptor currents that is prevented during anoxia by mitochondrial Ca(2+) release.

  17. Hypoxia inducible factor-1α mediates protective effects of ischemic preconditioning on ECV-304 endothelial cells

    Institute of Scientific and Technical Information of China (English)

    Liu-Bin Shi; Jian-Hua Huang; Bao-San Han

    2007-01-01

    AIM: To investigate whether hypoxia inducible factor-1α (HIF-1α) is linked to the protective effects of ischemic preconditioning (IP) on sinusoidal endothelial cells against ischemia/reperfusion injury.METHODS: Sinusoidal endothelial cell lines ECV-304 were cultured and divided into four groups: control group, cells were cultured in complete DMEM medium; cold anoxia/warm reoxygenation (A/R) group, cells were preserved in a 4℃ UW solution in a mixture of 95% N2 and 5% CO2 for 24 h; anoxia-preconditioning (ARC) group, cells were treated with 4 cycles of short anoxia and reoxygenation before prolonged anoxia-preconditioning treatment; and anoxia-preconditioning and hypoxia inducible factor-1α (HIF-1α) inhibitor (I-HIF-1) group, cells were pretreated with 5 μm of HIF-1α inhibitor NS398 in DMEM medium before subjected to the same treatment as group ARC. After the anoxia treatment, each group was reoxygenated in a mixture of 95% air and 5% CO2 incubator for 6 h. Cytoprotections were evaluated by cell viabilities from Trypan blue, lactate dehydrogenase (LDH) release rates, and intracellular cell adhesion molecule-1 (ICAM-1) expressions. Expressions of HIF-1α mRNA and HIF-1α protein from each group were determined by the RT-PCR method and Western blotting, respectively.RESULTS: Ischemia preconditioning increased cell viability, and reduced LDH release and ICAM-1 expressions. Ischemia preconditioning also upregulated the HIF-1α mRNA level and HIF-1α protein expression. However, all of these changes were reversed by HIF-1α inhibitor NS398.CONCLUSION: Ischemia preconditioning effectively inhibited cold hypoxia/warm reoxygenation injury to endothelial cells, and the authors showed for the first time HIF-1α is causally linked to the protective effects of ischemic preconditioning on endothelial cells.

  18. Simultaneous recording of ATP-sensitive K+ current and intracellular Ca2+ in anoxic rat ventricular myocytes. Effects of glibenclamide.

    Science.gov (United States)

    Russ, U; Englert, H; Schölkens, B A; Gögelein, H

    1996-05-01

    We investigated the temporal relationship between the adenosine triphosphate-sensitive K current (KATP current), hypoxic shortening and Ca accumulation in cardiomyocytes exposed to anoxia or metabolic inhibition. Whole-cell, patch-clamp experiments were performed with nonstimulated isolated rat heart ventricular muscle cells loaded with the Ca-sensitive fluorescent dye 1-[2-(5-carboxyoxazol-2-yl)-6-aminobenzofuran-5-oxy]-2-(2'- amino-5'-methylphenoxy) ethane-N,N,N',N'-tetraacetic acid (fura-2) via the patch pipette. After approximately 8 min anoxia, the KATP current started to rise and reached a maximum of 21.3 +/- 3.7 nA (n = 5, recorded at 0 mV clamp potential) within 1-3 min. At that time hypoxic contracture also occurred. Resting cytoplasmic free calcium (Cai) did not change significantly before hypoxic shortening. After hypoxic contracture, the KATP current decreased and Cai started to rise, reaching about 1 micromol/l. The presence of glibenclamide (10 micromol/l) in the bath reduced the anoxia-induced KATP current by more than 50%, but did not significantly influence the time dependence of current, hypoxic shortening and Cai, or the magnitude of Cai. Metabolic inhibition with 1.5 mmol/l CN resulted in KATP current increase and hypoxic shortening, occurring somewhat earlier than under anoxia, but all other parameters were comparable. In non-patch-clamped cells loaded with fura-2 AM ester and field-stimulated with 1 Hz, 1 micronol/l glibenclamide had no significant effect on the magnitude of the Cai increase caused by exposure of the cells to 1.5 mmol/l CN-. After CN- wash-out in non-patch-clamped cells, Cai declined, oscillated and finally returned to control values. It can be concluded that glibenclamide inhibits anoxia-induced KATP currents only partially and has no significant effect on anoxia-induced rise in resting Cai.

  19. Vasoactivity of hydrogen sulfide in normoxic and anoxic turtles (Trachemys scripta)

    DEFF Research Database (Denmark)

    Stecyk, Jonathan A.W.; Jensen, Nini Skovgaard; Nilsson, Göran E.;

    2010-01-01

    Systemic vascular resistance (Rsys) of freshwater turtles increases substantially during anoxia, but the underlying mechanisms are not fully understood. We investigated whether hydrogen sulfide (H2S), an endogenously produced metabolite believed to be an O2 sensor/transducer of vasomotor tone...... of plasma acid-labile sulfide concentration, likely increased by 3- and 4-fold during anoxia at 21°C, and 5°C, respectively. Yet, blockade of endogenous H2S production by DL-propargylglycine or hydroxylamine (0.44 mmol/kg) partially reversed the decreased systemic conductance (Gsys) exhibited by 5°C anoxic...

  20. Controlling benthic release of phosphorus in different Baltic Sea scales

    DEFF Research Database (Denmark)

    Pitkänen, Heikki; Bendtsen, Jørgen; Hansen, Jørgen L. S.;

    The general aim of the PROPPEN project was to study whether it is possible to counteract near-bottom anoxia and excess benthic nutrient release ("internal loading") in the Baltic Sea by artificial oxygenation in cost-efficient and socio-economically beneficial ways. Two pilot sites were selected ...... to counteract anoxia and benthic release of nutrients in coastal marine conditions in the Baltic Sea. The project undertook monitoring of the pilot tests, modelling of effects at different scales, risk management, cost effectiveness and cost benefit analysis....

  1. Anoxic aggregates - an ephemeral phenomenon in the pelagic environment? RID A-1977-2009

    DEFF Research Database (Denmark)

    Ploug, H.; Kuhl, M.; BuchholzCleven, B.;

    1997-01-01

    of heterotrophic processes would limit anoxic conditions to occurring only over a few hours, depending on the size of the aggregates. Therefore slow-growing obligate anaerobic microorganisms such as sulfate reducing bacteria and methanogenic bacteria may be limited by the relatively short persistence of anoxia...

  2. A long-term study of the recovery of the macrozoobenthos on large defaunated plots on a tidal flat in the Wadden Sea

    NARCIS (Netherlands)

    Beukema, J.J.; Flach, E.; Dekker, R.; Starink, Mathieu

    1999-01-01

    The process of recovery of the macrozoobenthos community on tidal Rats after disturbance by anoxia was studied by monitoring changes in the macrozoobenthos over periods of up to 4.5 year within and around eleven defaunated squares of about 120 m(2) each. Regardless of the season, nearly all species

  3. Investigating Extreme Lifestyles through Mangrove Transcriptomics

    Science.gov (United States)

    Dassanayake, Maheshi

    2009-01-01

    Mangroves represent phylogenetically diverse taxa in tropical coastal terrestrial habitats. They are extremophiles, evolutionarily adapted to tolerate flooding, anoxia, high temperatures, wind, and high and extremely variable salt conditions in typically resource-poor environments. The genetic basis for these adaptations is, however, virtually…

  4. The Role of Drugs, Diet, and Food Additives in Hyperactivity.

    Science.gov (United States)

    Harshbarger, Mary E.

    A variety of causes have been suggested for hyperactivity: anoxia and other adverse birth conditions, genetic factors, delayed maturation, maternal smoking and drinking during pregnancy, interaction of temperament and environment, lead poisoning, radiation stress, allergy and food additives, and deprivation of required stimulation. Treatments…

  5. Postanoxic oxidative injury in rat hepatocytes: lactate-dependent protection against tert-butylhydroperoxide.

    Science.gov (United States)

    Kowalski, D P; Aw, T Y; Park, Y; Jones, D P

    1992-01-01

    Previous studies in this laboratory showed that hypoxia and anoxia enhance the susceptibility of hepatocytes to tert-butylhydroperoxide (TBH)-induced oxidative injury. To determine whether preceding exposure to anoxia affects postanoxic sensitivity to oxidative injury, viability was studied in hepatocytes incubated under anoxic conditions followed by reoxygenation without or with tert-butylhydroperoxide addition. Results showed that a preceding exposure to 60 min of anoxia substantially increased the vulnerability of cells to injury by the oxidant. Because substantial tissue lactate can accumulate during anoxia, the effect of increased lactate on postanoxic injury due to TBH was determined. Results showed that added lactate protected in a concentration-dependent manner. The TBH elimination rate was stimulated by lactate, and the pyruvate production rate approached the rate of TBH elimination. Thus, lactate protects against postanoxic oxidative injury by supplying reducing equivalents for peroxide reduction. This suggests that lactate accumulation during ischemia may be beneficial and that supplementation with lactate could be considered as a means to protect against postischemic injury. PMID:1563646

  6. Dissimilatory nitrate reduction by Aspergillus terreus isolated from the seasonal oxygen minimum zone in the Arabian Sea

    NARCIS (Netherlands)

    Stief, Peter; Fuchs-Ocklenburg, Silvia; Kamp, Anja; Manohar, Cathrine-Sumathi; Houbraken, Jos; Boekhout, Teun; de Beer, Dirk; Stoeck, Thorsten

    2014-01-01

    BACKGROUND: A wealth of microbial eukaryotes is adapted to life in oxygen-deficient marine environments. Evidence is accumulating that some of these eukaryotes survive anoxia by employing dissimilatory nitrate reduction, a strategy that otherwise is widespread in prokaryotes. Here, we report on the

  7. A simple and fast method in testing a radiosensitizer in vivo by the study of hair dysplasia in the young mouse

    International Nuclear Information System (INIS)

    The study of radiation induced hair dysplasia in 8 day old mice allows investigations of the radiosensitizing power of a drug as early as the third day after irradiation without complicated equipment. The results being quantitative, they allow easy determination of the ER of a drug. In this study the method was applied to the action of metronidazol under anoxia

  8. Short-term anoxic conditioning hormesis boosts antioxidant defenses, lowers oxidative damage following irradiation and enhances male sexual performance in the Caribbean fruit fly, Anastrepha suspensa

    International Nuclear Information System (INIS)

    Most organisms are repeatedly exposed to oxidative stress from multiple sources throughout their lifetimes, potentially affecting all aspects of organismal performance. Here we test whether exposure to a conditioning bout of anoxia early in adulthood induces a hormetic response that confers resistance to oxidative stress and enhances male sexual performance later in life in the Caribbean fruit fly, Anastrepha suspensa. Anoxic conditioning of adults prior to emergence led to an increase in antioxidant capacity driven by mitochondrial superoxide dismutase and glutathione peroxidase. When exposed to gamma irradiation, a strong oxidative stressor, males that received anoxic conditioning had lower lipid and protein oxidative damage at sexual maturity. Anoxia conditioning led to greater male sexual competitiveness compared with unconditioned males when both were irradiated, although there was no effect of anoxia conditioning on mating competitiveness in unirradiated males. Anoxia also led to higher adult emergence rates and greater flight ability in irradiation-stressed flies while preserving steriity. Thus, hormetic treatments that increased antioxidant enzyme activity also improved male performance after irradiation, suggesting that antioxidant enzymes play an important role in mediating the relationship between oxidative stress and sexual selection. Furthermore, our work has important applied implications for the sterile insect technique (SIT), an environmentally friendly method of insect pest control where males are sterilized by irradiation and deployed in the field to disrupt pest populations via mating. We suggest that hormetic treatments specifically designed to enhance antioxidant activity may produce more sexually competitive sterile males, thus improving the efficacy and economy of SIT programs. (author)

  9. End Ordovician extinctions

    DEFF Research Database (Denmark)

    Harper, David Alexander Taylor; Hammarlund, Emma U.; Rasmussen, Christian Mac Ørum

    2014-01-01

    -global anoxia associated with a marked transgression during the Late Hirnantian. Most recently, however, new drivers for the extinctions have been proposed, including widespread euxinia together with habitat destruction caused by plate tectonic movements, suggesting that the end Ordovician mass extinctions were...

  10. Anoxic survival potential of bivalves: (arte)facts

    NARCIS (Netherlands)

    De Zwaan, A.; Babarro, J.M.F.; Monari, M.; Cattani, O.

    2002-01-01

    The anoxic survival time of the bivalves Chamelea gallina, Cerastoderma edule and Scapharca inaequivalvis from two different ecosystems and differing anoxia tolerances was studied in static (closed) and flow-through systems. The antibiotics chloramphenicol, penicillin and polymyxin were added, and m

  11. Spatial extent and degree of oxygen depletion in the deep proto-North Atlantic basin during Oceanic Anoxic Event 2

    NARCIS (Netherlands)

    van Helmond, Niels A. G. M.; Ruvalcaba Baroni, Itzel; Sluijs, Appy; Sinninghe Damste, Jaap S.; Slomp, Caroline P.

    2014-01-01

    Massive organic matter burial due to widespread ocean anoxia across the Cenomanian/Turonian boundary event (∼94 Ma) resulted in a major perturbation of the global carbon cycle: the so-called Oceanic Anoxic Event 2 (OAE2). The characteristics and spatial distribution of the OAE2 deposits that forme

  12. Human exercise physiology

    DEFF Research Database (Denmark)

    Volianitis, Stefanos; Secher, Niels H.

    2009-01-01

    that relates to the occurrence of hypoxia/anoxia in the natural life of the animal. The hypoxic/anoxic performance of the heart muscle correlates positively with the glycolytic capacity relative to the aerobic capacity, and this performance also tends to be high in hearts having a low aerobic or maximal...

  13. Evidence for a negative Pasteur effect in articular cartilage.

    Science.gov (United States)

    Lee, R B; Urban, J P

    1997-01-01

    Uptake of external glucose and production of lactate were measured in freshly-excised bovine articular cartilage under O2 concentrations ranging from 21% (air) to zero (N2-bubbled). Anoxia (O2 concentration Pasteur effect in bovine articular cartilage. Anoxia also suppressed glycolysis in articular cartilage from horse, pig and sheep. Inhibitors acting on the glycolytic pathway (2-deoxy-D-glucose, iodoacetamide or fluoride) strongly decreased aerobic lactate production and ATP concentration, consistent with the belief that articular cartilage obtains its principal supply of ATP from substrate-level phosphorylation in glycolysis. Azide or cyanide lowered the ATP concentration in aerobic cartilage to approximately the same extent as did anoxia but, because glycolysis (lactate production) was also inhibited by these treatments, the importance of any mitochondrial ATP production could not be assessed. A negative Pasteur effect would make chondrocytes particularly liable to suffer a shortage of energy under anoxic conditions. Incorporation of [35S]sulphate into proteoglycan was severely curtailed by treatments, such as anoxia, which decreased the intracellular concentration of ATP.

  14. Physiological responses to low atmospheric pressure stunning and the implications for welfare

    NARCIS (Netherlands)

    Mckeegan, D.E.F.; Sandercock, D.A.; Gerritzen, M.A.

    2013-01-01

    In low atmospheric pressure stunning (LAPS), poultry are rendered unconscious before slaughter by gradually reducing oxygen tension in the atmosphere to achieve a progressive anoxia. The effects of LAPS are not instantaneous, so there are legitimate welfare concerns around the experience of birds be

  15. Dissimilatory nitrate reduction by Aspergillus terreus isolated from the seasonal oxygen minimum zone in the Arabian Sea

    DEFF Research Database (Denmark)

    Stief, Peter; Fuchs-Ocklenburg, Silvia; Kamp, Anja;

    2014-01-01

    Background: A wealth of microbial eukaryotes is adapted to life in oxygen-deficient marine environments. Evidence is accumulating that some of these eukaryotes survive anoxia by employing dissimilatory nitrate reduction, a strategy that otherwise is widespread in prokaryotes. Here, we report...

  16. ANAEROBIC GLYCOLYSIS AND POSTANOXIC RECOVERY OF RESPIRATION OF RAT CORTICAL SYNAPTOSOMES ARE REDUCED BY SYNAPTOSOMAL SODIUM LOAD

    NARCIS (Netherlands)

    GLEITZ, J; BEILE, A; KHAN, S; WILFFERT, B; TEGTMEIER, F

    1993-01-01

    Synaptosomes of rat cerebral cortex were used to study the effect of veratridine-induced Na+ load on postanoxic recovery of respiration and on aerobic and anaerobic ATP turnover, calculated from rates of oxygen consumption and lactate production. Non-stimulated synaptosomes: after onset of anoxia la

  17. RhoA/ROCK pathway regulates hypoxia-induced myocardial cell apoptosis

    Institute of Scientific and Technical Information of China (English)

    Yi Huang; Jiang-bin Chen; Bo Yang; Hui Shen; Jin-Jun Liang; Qiong Luo

    2014-01-01

    Objective:To observe the regulatory effects of RhoA/ROCK pathway on the apoptosis of cardiac myocyte induced by anoxia and its mechanism. Methods:The model of cardiac myocyte anoxia was established. The beat pulsations and apoptosis rates after 1 h, 3 h, 6 h, 9 h and 12 h of anoxia were recorded and the expressions of RhoA, ROCK1/2, p-PI3K, p-AKT and caspae-3 were detected, too. The apoptosis and the expressions of related proteins were detected after RNAi of RhoA and the inhibition of ROCK by Y-27632. Results:The beat pulsations after 1 h, 3 h, 6 h, 9 h and 12 h decreased gradually but the apoptosis rates increased gradually, and the expressions of RhoA, ROCK1/2, p-PI3K, p-AKT and caspase-3 were increasing along with the increasing duration of anoxia. The apoptotic rates after 1 h, 3 h, 6 h, 9 h and 12 h of anoxia were (4.36±0.98)%, (8.36±2.12)%, (15.32±3.62)%, (18.68±4.83)%and (24.56±6.22)%, respectively and decreased more significantly than control group in different time points of anoxia (P<0.05), and the expressions of RhoA, ROCK1/2, p-PI3K, p-AKT and caspase-3 decreased significantly (P<0.05). The apoptosis rate and the expressions of RhoA, ROCK1/2, p-PI3K, p-AKT and caspase-3 decreased significantly (P<0.05) after the inhibition of ROCK by Y-27632 (P<0.05). Conclusions:RhoA/ROCK pathway plays a critical role in the regulation of the apoptosis of cardiac myocyte induced by anoxia, which may be accompanied by regulating the activity of PI3K/AKT/Caspase-3 pathway.

  18. Adaptation to Temporally Fluctuating Environments by the Evolution of Maternal Effects.

    Directory of Open Access Journals (Sweden)

    Snigdhadip Dey

    2016-02-01

    Full Text Available All organisms live in temporally fluctuating environments. Theory predicts that the evolution of deterministic maternal effects (i.e., anticipatory maternal effects or transgenerational phenotypic plasticity underlies adaptation to environments that fluctuate in a predictably alternating fashion over maternal-offspring generations. In contrast, randomizing maternal effects (i.e., diversifying and conservative bet-hedging, are expected to evolve in response to unpredictably fluctuating environments. Although maternal effects are common, evidence for their adaptive significance is equivocal since they can easily evolve as a correlated response to maternal selection and may or may not increase the future fitness of offspring. Using the hermaphroditic nematode Caenorhabditis elegans, we here show that the experimental evolution of maternal glycogen provisioning underlies adaptation to a fluctuating normoxia-anoxia hatching environment by increasing embryo survival under anoxia. In strictly alternating environments, we found that hermaphrodites evolved the ability to increase embryo glycogen provisioning when they experienced normoxia and to decrease embryo glycogen provisioning when they experienced anoxia. At odds with existing theory, however, populations facing irregularly fluctuating normoxia-anoxia hatching environments failed to evolve randomizing maternal effects. Instead, adaptation in these populations may have occurred through the evolution of fitness effects that percolate over multiple generations, as they maintained considerably high expected growth rates during experimental evolution despite evolving reduced fecundity and reduced embryo survival under one or two generations of anoxia. We develop theoretical models that explain why adaptation to a wide range of patterns of environmental fluctuations hinges on the existence of deterministic maternal effects, and that such deterministic maternal effects are more likely to contribute to

  19. Adaptation to Temporally Fluctuating Environments by the Evolution of Maternal Effects.

    Science.gov (United States)

    Dey, Snigdhadip; Proulx, Stephen R; Teotónio, Henrique

    2016-02-01

    All organisms live in temporally fluctuating environments. Theory predicts that the evolution of deterministic maternal effects (i.e., anticipatory maternal effects or transgenerational phenotypic plasticity) underlies adaptation to environments that fluctuate in a predictably alternating fashion over maternal-offspring generations. In contrast, randomizing maternal effects (i.e., diversifying and conservative bet-hedging), are expected to evolve in response to unpredictably fluctuating environments. Although maternal effects are common, evidence for their adaptive significance is equivocal since they can easily evolve as a correlated response to maternal selection and may or may not increase the future fitness of offspring. Using the hermaphroditic nematode Caenorhabditis elegans, we here show that the experimental evolution of maternal glycogen provisioning underlies adaptation to a fluctuating normoxia-anoxia hatching environment by increasing embryo survival under anoxia. In strictly alternating environments, we found that hermaphrodites evolved the ability to increase embryo glycogen provisioning when they experienced normoxia and to decrease embryo glycogen provisioning when they experienced anoxia. At odds with existing theory, however, populations facing irregularly fluctuating normoxia-anoxia hatching environments failed to evolve randomizing maternal effects. Instead, adaptation in these populations may have occurred through the evolution of fitness effects that percolate over multiple generations, as they maintained considerably high expected growth rates during experimental evolution despite evolving reduced fecundity and reduced embryo survival under one or two generations of anoxia. We develop theoretical models that explain why adaptation to a wide range of patterns of environmental fluctuations hinges on the existence of deterministic maternal effects, and that such deterministic maternal effects are more likely to contribute to adaptation than

  20. Adaptation to Temporally Fluctuating Environments by the Evolution of Maternal Effects.

    Science.gov (United States)

    Dey, Snigdhadip; Proulx, Stephen R; Teotónio, Henrique

    2016-02-01

    All organisms live in temporally fluctuating environments. Theory predicts that the evolution of deterministic maternal effects (i.e., anticipatory maternal effects or transgenerational phenotypic plasticity) underlies adaptation to environments that fluctuate in a predictably alternating fashion over maternal-offspring generations. In contrast, randomizing maternal effects (i.e., diversifying and conservative bet-hedging), are expected to evolve in response to unpredictably fluctuating environments. Although maternal effects are common, evidence for their adaptive significance is equivocal since they can easily evolve as a correlated response to maternal selection and may or may not increase the future fitness of offspring. Using the hermaphroditic nematode Caenorhabditis elegans, we here show that the experimental evolution of maternal glycogen provisioning underlies adaptation to a fluctuating normoxia-anoxia hatching environment by increasing embryo survival under anoxia. In strictly alternating environments, we found that hermaphrodites evolved the ability to increase embryo glycogen provisioning when they experienced normoxia and to decrease embryo glycogen provisioning when they experienced anoxia. At odds with existing theory, however, populations facing irregularly fluctuating normoxia-anoxia hatching environments failed to evolve randomizing maternal effects. Instead, adaptation in these populations may have occurred through the evolution of fitness effects that percolate over multiple generations, as they maintained considerably high expected growth rates during experimental evolution despite evolving reduced fecundity and reduced embryo survival under one or two generations of anoxia. We develop theoretical models that explain why adaptation to a wide range of patterns of environmental fluctuations hinges on the existence of deterministic maternal effects, and that such deterministic maternal effects are more likely to contribute to adaptation than

  1. Effects of cadmium on anaerobic energy metabolism and mRNA expression during air exposure and recovery of an intertidal mollusk Crassostrea virginica

    International Nuclear Information System (INIS)

    Marine organisms are exposed to periodical oxygen deficiency and pollution stress in estuarine and coastal zones which may strongly affect their performance and survival. We studied the combined effects of exposure to a common pollutant, cadmium (Cd), and intermittent anoxia on anaerobic metabolism, energy status and mRNA expression of 13 genes involved in and/or controlled by the hypoxia inducible factor-1 (HIF-1) pathway in hepatopancreas of an intertidal bivalve, the eastern oyster Crassostrea virginica. In control oysters, prolonged anoxia resulted in a selective suppression of nitric oxide synthase (NOS) and upregulation of cytochrome c oxidase subunit IV (COX4) while the levels of other transcripts remained unchanged. During post-anoxic recovery, mRNA expression of hypoxia inducible factor-1α (HIF-1α) was elevated, phosphoenolpyruvate carboxykinase (PEPCK), NOS and LON protease suppressed, and mRNA expression of other studied genes not changed. Notably, most of the key glycolytic genes that are stimulated by HIF-1 in mammals, either remained unchanged or were downregulated in anoxic oysters suggesting a different mechanism of molecular response to oxygen deficiency. Patterns of transcriptional response during anoxia and reoxygenation were significantly altered by Cd exposure in a gene-specific manner. Anaerobic metabolism (indicated by accumulation of L-alanine, succinate and acetate during anoxia) was also suppressed in Cd-exposed oysters. In control oysters, ATP turnover rate (MATP) during anoxia was mostly sustained by anaerobic glycolysis with negligible contributions from ATP and PLA breakdown. In contrast, in Cd-exposed oysters ATP breakdown contributed significantly to anaerobic MATP. Thus, while control oysters could efficiently defend the ATP levels and tissue energy status during prolonged anoxia, Cd-exposed oysters experienced a disturbance in tissue energy balance indicated by the depletion of ATP, a rapid decline in adenylate energy charge and

  2. Influence of glyphosate in planktonic and biofilm growth of Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Ilana Schneider Lima

    2014-09-01

    Full Text Available This study evaluated the impact of different concentrations of glyphosate (Rondup® on planktonic and biofilm growth of P. aeruginosa. Aerobic and anaerobic cultures of P. aeruginosa ATCC®15442 inoculated in MHB + glyphosate (0.845 ppm, 1.690 ppm, 8.45 ppm, 16.90 ppm, 84.50 ppm, 169 ppm, 845 ppm, and 1690 ppm and cultured in normoxia and anoxia, following their OD560nm every hour for 24 h. Biofilms of adapted cells were formed in the presence of glyphosate (0.845 to 1690 ppm in normoxia and anoxia for 36 h. Glyphosate at concentrations higher than 84.5 ppm reduces the cell density of planktonic aerobic cultures (p 0.05, and more pronounced over 169 ppm. Anaerobic biofilms have their growth more readily favored (p < 0.05, regardless of concentration. In a concentration-dependent manner, glyphosate interferes with the growth ability of P. aeruginosa ATCC®15442.

  3. Changes in environmental conditions as the cause of the marine biota Great Mass Extinction at the Triassic-Jurassic boundary

    Science.gov (United States)

    Barash, M. S.

    2016-02-01

    In the interval of the Triassic-Jurassic boundary, 80% of the marine species became extinct. Four main hypotheses about the causes of this mass extinction are considered: volcanism, climatic oscillations, sea level variations accompanied by anoxia, and asteroid impact events. The extinction was triggered by an extensive flooding of basalts in the Central Atlantic Magmatic Province. Furthermore, a number of meteoritic craters have been found. Under the effect of cosmic causes, two main sequences of events developed on the Earth: terrestrial ones, leading to intensive volcanism, and cosmic ones (asteroid impacts). Their aftermaths, however, were similar in terms of the chemical compounds and aerosols released. As a consequence, the greenhouse effect, dimming of the atmosphere (impeding photosynthesis), ocean stagnation, and anoxia emerged. Then, biological productivity decreased and food chains were destroyed. Thus, the entire ecosystem was disturbed and a considerable part of the biota became extinct.

  4. Arctic black shale formation during Cretaceous Oceanic Anoxic Event 2

    DEFF Research Database (Denmark)

    Lenniger, Marc; Nøhr-Hansen, Henrik; Hills, Len V.;

    2014-01-01

    The Late Cretaceous Oceanic Anoxic Event 2 (OAE2) represents a major perturbation of the global carbon cycle caused by the widespread deposition of organic-rich black shales. Although the paleoceanographic response and the spatial extent of bottom-water anoxia in low and mid-paleolatitudes are re......The Late Cretaceous Oceanic Anoxic Event 2 (OAE2) represents a major perturbation of the global carbon cycle caused by the widespread deposition of organic-rich black shales. Although the paleoceanographic response and the spatial extent of bottom-water anoxia in low and mid...... caused massive organic-carbon burial on the Arctic shelf in general, with important implications for hydrocarbon source-rock distribution in the Arctic region....

  5. Function of the chloroplast hydrogenase in the microalga Chlamydomonas: the role of hydrogenase and state transitions during photosynthetic activation in anaerobiosis.

    Directory of Open Access Journals (Sweden)

    Bart Ghysels

    Full Text Available Like a majority of photosynthetic microorganisms, the green unicellular alga Chlamydomonas reinhardtii may encounter O2 deprived conditions on a regular basis. In response to anaerobiosis or in a respiration defective context, the photosynthetic electron transport chain of Chlamydomonas is remodeled by a state transition process to a conformation that favours the photoproduction of ATP at the expense of reductant synthesis. In some unicellular green algae including Chlamydomonas, anoxia also triggers the induction of a chloroplast-located, oxygen sensitive hydrogenase, which accepts electrons from reduced ferredoxin to convert protons into molecular hydrogen. Although microalgal hydrogen evolution has received much interest for its biotechnological potential, its physiological role remains unclear. By using specific Chlamydomonas mutants, we demonstrate that the state transition ability and the hydrogenase function are both critical for induction of photosynthesis in anoxia. These two processes are thus important for survival of the cells when they are transiently placed in an anaerobic environment.

  6. Function of the chloroplast hydrogenase in the microalga Chlamydomonas: the role of hydrogenase and state transitions during photosynthetic activation in anaerobiosis.

    Science.gov (United States)

    Ghysels, Bart; Godaux, Damien; Matagne, René F; Cardol, Pierre; Franck, Fabrice

    2013-01-01

    Like a majority of photosynthetic microorganisms, the green unicellular alga Chlamydomonas reinhardtii may encounter O2 deprived conditions on a regular basis. In response to anaerobiosis or in a respiration defective context, the photosynthetic electron transport chain of Chlamydomonas is remodeled by a state transition process to a conformation that favours the photoproduction of ATP at the expense of reductant synthesis. In some unicellular green algae including Chlamydomonas, anoxia also triggers the induction of a chloroplast-located, oxygen sensitive hydrogenase, which accepts electrons from reduced ferredoxin to convert protons into molecular hydrogen. Although microalgal hydrogen evolution has received much interest for its biotechnological potential, its physiological role remains unclear. By using specific Chlamydomonas mutants, we demonstrate that the state transition ability and the hydrogenase function are both critical for induction of photosynthesis in anoxia. These two processes are thus important for survival of the cells when they are transiently placed in an anaerobic environment. PMID:23717558

  7. Refractory Case of Paroxysmal Autonomic Instability With Dystonia Syndrome Secondary to Hypoxia.

    Science.gov (United States)

    Kern, John; Bodek, Daniel; Niazi, Osama Tariq; Maher, James

    2016-02-01

    Paroxysmal autonomic instability with dystonia (PAID) is a syndrome commonly related to traumatic brain injury (TBI) and rarely to anoxia associated with symptoms of dystonia, tachycardia, tachypnea, and diaphoresis. This is a case of a 20-year-old man who was stabbed in the heart. He underwent surgical repair of a ventricular septal defect and mitral valve replacement. Postoperatively, he developed dystonia with tachycardia and tachypnea consistent with PAID syndrome, secondary to prolonged hypoxia. Traditionally, this poorly understood syndrome is treated with morphine, clonazepam, and nonselective β-blockers. Second-line medications commonly used are baclofen, dantrolene, and gabapentin, which are aimed at the dystonia itself. In this case, both first- and second-line agents were ineffective. A 72-hour dexmedetomidine infusion resulted in complete resolution of symptoms. This is the first case of anoxia-induced PAID syndrome to be effectively treated with dexmedetomidine, which was previously used in a case induced by TBI. PMID:26867852

  8. Health assessment document for hydrogen sulfide: review draft

    Energy Technology Data Exchange (ETDEWEB)

    Ammann, H.M.; Bradow, F.; Fennell, D.; Griffin, R.; Kearney, B.

    1986-08-01

    Hydrogen sulfide is a highly toxic gas which is immediately lethal in concentrations greater than 2000 ppm. The toxic end-point is due to anoxia to brain and heart tissues which results from its interaction with the celluar enzyme cytochrome oxidase. Inhibition of the enzyme halts oxidative metabolism which is the primary energy source for cells. A second toxic end-point is the irritative effect of hydrogen sulfide on mucous membranes, particularly edema at sublethal doses (250 to 500 ppm) in which sufficient exposure occurs before conciousness is lost. Recovered victims of exposure report neurologic symptoms such as headache, fatigue, irritability, vertigo, and loss of libido. Long-term effects are similar to those caused by anoxia due to other toxic agents like CO, and probably are not due to specific H/sub 2/S effects. H/sub 2/S is not a cumulative poison. No mutagenic, carcinogenic, reproductive, or teratogenic effects have been reported in the literature.

  9. AN EXPERIMENTAL STUDY ON THE INDUCTION MECHANISM OF SUPEROXIDE DISMUTASE IN CULTURED CARDIOMYOCYTES DURING HEAT SHOCK

    Institute of Scientific and Technical Information of China (English)

    朱洪生; 王胜; 沈莉; 谢芳; 魏丕敬

    2000-01-01

    Objective To explore the role of reaction oxygen species (ROS) in heat shock (HS) on the tolerance of cardiomyocytes to anoxia - reoxygenation (AO - RO) injury and on the activity of superoxide dismutase (SOD).Methods Cultured neonatal myocytes of rats were divided into 5 groups: normal control, anoxic control, HS,HS- SOD pretreated and exogenous ROS pretreated (n= 6). Results Compared with the 2 control groups, ROS release in HS and ROS pretreated groups increased mildly, but after experiencing 3h anoxia/lh reoxygenation 24hlater, ROS release of the two groups decreased significantly, which was accompanied by enhanced SOD activities and less myocytes damage. Opposite results were found when SOD was insituted during HS. Conclusion HS did enhance myocardial tolerance to AO-RO injury. The mild release of ROS during HS may trigger delayed myocardial protection by altering SOD activity.

  10. Combined impact of water column oxygen and temperature on internal oxygen status and growth of Zostera marina seedlings and adult shoots

    DEFF Research Database (Denmark)

    Raun, Ane-Marie Løvendahl; Borum, Jens

    2013-01-01

    Eelgrass (Zostera marina L.) occasionally experiences severe die-offs during warm summer periods with variable water column oxygen partial pressures (pO). Eelgrass is known to be very intolerant to tissue anoxia with reduced growth and increasing mortality after ≤12h anoxia in the dark at...... temperatures of ≥25°C. In the present study we experimentally examine the impact of combined water column oxygen and temperature on oxygen dynamics in leaf meristems of seedlings and adult shoots to better understand how stressful environmental conditions affect eelgrass oxygen dynamics and subsequent growth...... and mortality. There was a strong interaction between water column oxygen and temperature on meristem pO implying that eelgrass is rather resistant to unfavorable oxygen conditions in winter but becomes increasingly vulnerable in summer, especially at high temperatures. At 25°C meristems became anoxic...

  11. Life-history strategies affect aphid preference for yellowing leaves

    OpenAIRE

    Holopainen, Jarmo K.; Semiz, Gürkan; Blande, James D

    2009-01-01

    According to the nutrient-translocation hypothesis, yellowing tree leaves are colonized by aphids at the end of the growing season owing to improved availability of nutrients in the phloem sap after chlorophyll degradation. We measured aphid densities on potted Betula pendula seedlings in a field site where a small proportion of foliage rapidly turned yellow before normal autumn coloration as a consequence of root anoxia. The number of adults and nymphs of the birch-feeding specialist aphids ...

  12. High sea-surface temperatures during the early Aptian Oceanic Anoxic Event 1a in the Boreal Realm

    OpenAIRE

    J. Mutterlose; Bottini, C.; Schouten, S.; Sinninghe Damsté, J.S.

    2014-01-01

    The early Aptian was characterized by the widespread occurrence of anoxia in the oceans, known as Oceanic Anoxic Event (OAE) 1a. Intense degassing from submarine volcanic plateaus presumably resulted in high atmospheric CO2 concentrations, culminating in greenhouse conditions. OAE 1a can, therefore, be considered as a past “natural experiment” important to understand the future evolution of our climate. Paleotemperature estimates for OAE 1a are, however, predominantly based on bulk oxygen iso...

  13. The meiofauna of two protected wetlands on the Slovene coast: the Škocjan Inlet and the Strunjan Lagoon:

    OpenAIRE

    Vrišer, Borut

    2002-01-01

    The paper presents ecological and meiofaunal comparisons between two extremely shallow intracoastal formations along the Slovene part of the Adriatic Sea, i.e. the Škocjan Inlet in the Bay of Koper and the somewhat smaller Stjuža Lagoon near the salt-pans of Strunjan. The Inlet is a highly degraded, isolated and stagnant neritic environment, affected with temporary summer anoxias...

  14. Controls on oxygen dynamics in a riverine salt-wedge estuary – a three-dimensional model of the Yarra River estuary, Australia

    OpenAIRE

    L. C. Bruce; Cook, P. L. M.; I. Teakle; M. R. Hipsey

    2013-01-01

    Oxygen depletion in estuarine waters is an important factor governing water quality and ecological health. A complex and dynamic balance of physical and biogeochemical factors drive the extent and persistence of hypoxia and anoxia making it difficult to predict. An increased understanding of the effect of changing flow regimes and temperature on patterns of estuarine oxygen depletion is required to support ongoing management. Coupled physical and biogeochemical models have been applied to stu...

  15. Postnatal loss of brainstem serotonin neurones compromises the ability of neonatal rats to survive episodic severe hypoxia.

    Science.gov (United States)

    Cummings, Kevin J; Hewitt, Julie C; Li, Aihua; Daubenspeck, John A; Nattie, Eugene E

    2011-11-01

    Pet-1(-/-) mice with a prenatal, genetically induced loss of 5-hydroxytryptamine (5-HT, serotonin) neurones are compromised in their ability to withstand episodic environmental anoxia via autoresuscitation. Given the prenatal role of 5-HT neurones in the development of neural networks, here we ask if a postnatal loss of 5-HT neurones also compromises autoresuscitation. We treated neonatal rat pups at postnatal day (P)2-3 with an intra-cisternal injection of 5,7-dihydroxytryptamine (5,7-DHT; ~40 μg; n = 8) to pharmacologically lesion the 5-HT system, or vehicle (control; n = 14). At P7-10 we exposed unanaesthetized treated and control pups to 15 episodes of environmental anoxia (97% N(2), 3% CO(2)). Medullary 5-HT content was reduced 80% by 5,7-DHT treatment (P rate (V(O(2))), ventilatory equivalent (V(E)/V(O(2))), heart rate (HR), heart rate variability (HRV) and arterial haemoglobin saturation (S(aO(2))) were no different in 5-HT-deficient pups compared to controls. However, only 25% of 5-HT-deficient pups survived all 15 episodes of environmental anoxia, compared to 79% of control littermates (P = 0.007). High mortality of 5,7-DHT-treated pups was associated with delayed onset of gasping (P pups this increase occurred immediately prior to death. We conclude that a postnatal loss of brainstem 5-HT content compromises autoresuscitation in response to environmental anoxia. This report provides new evidence in rat pups that 5-HT neurones serve a physiological role in autoresuscitation. Our data may be relevant to understanding the aetiology of the sudden infant death syndrome (SIDS), in which there is medullary 5-HT deficiency and in some cases evidence of severe hypoxia and failed autoresuscitation. PMID:21911619

  16. Optical assessment of intravascular and intracellular parameters related to tissue viability

    Science.gov (United States)

    Mayevsky, Avraham; Sherman, Efrat; Cohen-Kashi, Meir; Dekel, Nava; Pewzner, Eliyahu

    2007-02-01

    Tissue viability represents the balance between O II supply and demand. In our previous paper (Mayevsky et al; Proc.SPIE 6083 : z1-z10, 2006) the HbO II was added to the multiparametric tissue spectroscope (Mayevsky et al J.Biomedical Optics 9:1028-1045,2004). This parameter provides relative values of microcirculatory blood oxygenation (MC-HbO II) evaluated by the 2 wavelength reflectometry principle. The advantage of this approach as compared to pulse oximetry is that the measurement is not dependent of the existence of the pulse of the heart. Also in the MC-HbO II the information is collected from small vessels providing O II to the mitochondria as compared to the pulse oximeter indicating blood oxygenation by the respiratory and cardiovascular systems. In the present study we compared the level of blood oxygenation measured by the pulse oximeter to that measured by the CritiView in the brain exposed to various systemic and localized perturbations of O II supply or demand. We exposed gerbils to anoxia, hypoxia, ischemia and terminal anoxia. In addition we measured mitochondrial NADH (surface fluorometry), tissue reflectance, tissue blood flow (laser Doppler flowmetry) from the same site of MC-HbO II measurement. A clear connection was found between the two blood oxygenation parameters only when systemic perturbations were used (anoxia, hypoxia and terminal anoxia). Under local events (ischemia) the MC-HbO II was responsive while the systemic oxygenation was unchanged. We concluded that MC-HbO II has a significant value in interpretation of tissue energy metabolism under pathophysiological conditions.

  17. The influence of the biological pump on ocean chemistry: implications for long-term trends in marine redox chemistry, the global carbon cycle, and marine animal ecosystems.

    Science.gov (United States)

    Meyer, K M; Ridgwell, A; Payne, J L

    2016-05-01

    The net export of organic matter from the surface ocean and its respiration at depth create vertical gradients in nutrient and oxygen availability that play a primary role in structuring marine ecosystems. Changes in the properties of this 'biological pump' have been hypothesized to account for important shifts in marine ecosystem structure, including the Cambrian explosion. However, the influence of variation in the behavior of the biological pump on ocean biogeochemistry remains poorly quantified, preventing any detailed exploration of how changes in the biological pump over geological time may have shaped long-term shifts in ocean chemistry, biogeochemical cycling, and ecosystem structure. Here, we use a 3-dimensional Earth system model of intermediate complexity to quantitatively explore the effects of the biological pump on marine chemistry. We find that when respiration of sinking organic matter is efficient, due to slower sinking or higher respiration rates, anoxia tends to be more prevalent and to occur in shallower waters. Consequently, the Phanerozoic trend toward less bottom-water anoxia in continental shelf settings can potentially be explained by a change in the spatial dynamics of nutrient cycling rather than by any change in the ocean phosphate inventory. The model results further suggest that the Phanerozoic decline in the prevalence ocean anoxia is, in part, a consequence of the evolution of larger phytoplankton, many of which produce mineralized tests. We hypothesize that the Phanerozoic trend toward greater animal abundance and metabolic demand was driven more by increased oxygen concentrations in shelf environments than by greater food (nutrient) availability. In fact, a lower-than-modern ocean phosphate inventory in our closed system model is unable to account for the Paleozoic prevalence of bottom-water anoxia. Overall, these model simulations suggest that the changing spatial distribution of photosynthesis and respiration in the oceans has

  18. Distinct Mechanisms Regulating Gene Expression Coexist within the Fermentative Pathways in Chlamydomonas reinhardtii

    OpenAIRE

    Larisa Angela Swirsky Whitney; Giacomo Novi; Pierdomenico Perata; Elena Loreti

    2012-01-01

    Under dark anoxia, the unicellular green algae Chlamydomonas reinhardtii may produce hydrogen by means of its hydrogenase enzymes, in particular HYD1, using reductants derived from the degradation of intercellular carbon stores. Other enzymes belonging to the fermentative pathways compete for the same reductants. A complete understanding of the mechanisms determining the activation of one pathway rather than another will help us engineer Chlamydomonas for fermentative metabolite production, ...

  19. In-vitro anti-atherothrombosis activity of four Bangladeshi plants

    OpenAIRE

    Irin Sultana; Md. Abdun Noor; Joy Barua; Ayesha Mahmood; Mishon Chandra Das; Md. Torequl Islam; Mohammed Ibrahim; M Mohi Uddin Chowdhury

    2012-01-01

    Thrombous formation inside the blood vessels obstructs blood flow through the circulatory system leading hypertension, stroke to the heart, anoxia and so on. The complete deprivation of oxygen and infarction is a mode of cell death. Crude biologicals and their components possessing anti-thrombotic activity have been reported before. This study was aimed to investigate thrombolytic activity of ethanol extracts of four traditionally used medicinal plants. For this an in-vitro thrombolytic study...

  20. Early adenosine release contributes to hypoxia-induced disruption of stimulus-induced sharp wave-ripple complexes in rat hippocampal area CA3.

    Science.gov (United States)

    Jarosch, Marlene S; Gebhardt, Christine; Fano, Silvia; Huchzermeyer, Christine; Ul Haq, Rizwan; Behrens, Christoph J; Heinemann, Uwe

    2015-07-01

    We investigated the effects of hypoxia on sharp wave-ripple complex (SPW-R) activity and recurrent epileptiform discharges in rat hippocampal slices, and the mechanisms underlying block of this activity. Oxygen levels were measured using Clark-style oxygen sensor microelectrodes. In contrast to recurrent epileptiform discharges, oxygen consumption was negligible during SPW-R activity. These network activities were reversibly blocked when oxygen levels were reduced to 20% or less for 3 min. The prolongation of hypoxic periods to 6 min caused reversible block of SPW-Rs during 20% oxygen and irreversible block when 0% oxygen (anoxia) was applied. In contrast, recurrent epileptiform discharges were more resistant to prolonged anoxia and almost fully recovered after 6 min of anoxia. SPW-Rs were unaffected by the application of 1-butyl-3-(4-methylphenylsulfonyl) urea, a blocker of KATP channels, but they were blocked by activation of adenosine A1 receptors. In support of a modulatory function of adenosine, the amplitude and incidence of SPW-Rs were increased during application of the A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). Interestingly, hypoxia decreased the frequency of miniature excitatory post-synaptic currents in CA3 pyramidal cells, an effect that was converted into increased frequency by the adenosine A1 agonist DPCPX. In addition, DPCPX also delayed the onset of hypoxia-mediated block of SPW-Rs. Our data suggest that early adenosine release during hypoxia induces a decrease in pre-synaptic glutamate release and that both might contribute to transient block of SPW-Rs during hypoxia/anoxia in area CA3. PMID:25959377

  1. Screening of Psidium guajava Leaf Extracts for Antistress Activity in Different Experimental Animal Models

    OpenAIRE

    Lakshmi, B. V. S.; Sudhakar, M.

    2009-01-01

    Ethanolic extract of leaves of Psidium guajava was investigated on anoxia stress tolerance test in Swiss mice. The animals were also subjected to acute physical stress (swimming endurance test) and acute heat induced stress to gauge the antistress potential of the extract. Further to evaluate the antistress activity of Psidium guajava in chronic stress condition, fresh Wistar rats were subjected to cold restraint stress (4° for 2 h) for 10 days. Stimulation of hypothalamus pituitary adrenal a...

  2. Flexibility in Anaerobic Metabolism as Revealed in a Mutant of Chlamydomonas reinhardtii Lacking Hydrogenase Activity*S⃞

    OpenAIRE

    Dubini, Alexandra; Mus, Florence; Seibert, Michael; Grossman, Arthur R.; Posewitz, Matthew C.

    2009-01-01

    The green alga Chlamydomonas reinhardtii has a network of fermentation pathways that become active when cells acclimate to anoxia. Hydrogenase activity is an important component of this metabolism, and we have compared metabolic and regulatory responses that accompany anaerobiosis in wild-type C. reinhardtii cells and a null mutant strain for the HYDEF gene (hydEF-1 mutant), which encodes an [FeFe] hydrogenase maturation protein. This mutant has no hydrogenase activity...

  3. A continuum model for metabolic gas exchange in pear fruit.

    OpenAIRE

    Q Tri Ho; Pieter Verboven; Verlinden, Bert E.; Jeroen Lammertyn; Stefan Vandewalle; Nicolaï, Bart M.

    2008-01-01

    Exchange of O(2) and CO(2) of plants with their environment is essential for metabolic processes such as photosynthesis and respiration. In some fruits such as pears, which are typically stored under a controlled atmosphere with reduced O(2) and increased CO(2) levels to extend their commercial storage life, anoxia may occur, eventually leading to physiological disorders. In this manuscript we have developed a mathematical model to predict the internal gas concentrations, including permeation...

  4. Using paleolimnology to find restoration solutions: the case of Lake Muzzano, Switzerland

    Directory of Open Access Journals (Sweden)

    Isabelle eLarocque-Tobler

    2015-07-01

    Full Text Available Lake Muzzano (45°59′50″N 8°55′41″E, 337 m a.s.l. is a hyper-eutrophied lake located in the Tessin region of Switzerland. Almost every year, algal blooms (Microcystis cover the lake with a thickness of 1-2 cm. These blooms associated with periods of anoxia in summer have led to fish kills in 1967 and 1994. In the hope of avoiding these blooms, a bypass bringing water away from the lake has been established in 1999. This solution was not adequate as blooms kept reoccurring. Sediment removal was then proposed by the Tessin Canton as a possible remediation technique and The L.A.K.E.S Institute had a mandate in 2010 to study the lake (present and past state to determine the reasons creating anoxia and algal blooms. The present state of the lake shows that anoxia is still occurring when the algal bloom covers the lake’s surface. Subfossil diatom and chironomid analyses show that the baseline conditions were those found before 1922 AD when the lake was oligotrophic and supported a diversified community of chironomids suggesting good oxygenation. After 1922 AD, circulation to the lake was cut out and nutrients accumulated in the lake leading to anoxia and the establishment of Microcystis. Heavy metal analysis in the sediment shows that the concentration is above the national recommendation and thus sediment should not be removed or should be stored with hazardous material. Based on the present status of the lake and paleolimnological results, two solutions are proposed: to further decrease the nutrients coming in the lake (possibly using filtrating plants followed by flushing to increase lake water circulation. Physical capping of the sediment to avoid exchange of heavy metals and phosphorus release at the water/sediment interface could also be envisaged once the two prime solutions are in place.

  5. Seagrasses in the Age of Sea Turtle Conservation and Shark Overfishing

    OpenAIRE

    Heithaus, Michael R.; Teresa eAlcoverro; Rohan eArthur; Burkholder, Derek A.; Coates, Kathryn A.; Christianen, Marjolijn J. A.; Nachiket eKelkar; Manuel, Sarah A.; Wirsing, Aaron J.; W. Judson Kenworthy; Fourqurean, James W.

    2014-01-01

    Efforts to conserve globally declining herbivorous green sea turtles have resulted in promising growth of some populations. These trends could significantly impact critical ecosystem services provided by seagrass meadows on which turtles feed. Expanding turtle populations could improve seagrass ecosystem health by removing seagrass biomass and preventing of the formation of sediment anoxia. However, overfishing of large sharks, the primary green turtle predators, could facilitate turtle popul...

  6. Seagrasses in the age of sea turtle conservation and shark overfishing

    OpenAIRE

    Heithaus, Michael R.; Alcoverro, Teresa; Arthur, Rohan; Burkholder, Derek A.; Coates, Kathryn A.; Christianen, Marjolijn J. A.; Kelkar, Nachiket; Manuel, Sarah A.; Wirsing, Aaron J.; Kenworthy, W. Judson; Fourqurean, James W.

    2014-01-01

    Efforts to conserve globally declining herbivorous green sea turtles have resulted in promising growth of some populations. These trends could significantly impact critical ecosystem services provided by seagrass meadows on which turtles feed. Expanding turtle populations could improve seagrass ecosystem health by removing seagrass biomass and preventing of the formation of sediment anoxia. However, overfishing of large sharks, the primary green turtle predators, could facilita...

  7. Tree-mediated methane emissions from tropical and temperate peatlands

    OpenAIRE

    S. R. Pangala; V. Gauci; E. R. C. Hornibrook; Gowing, D.J.

    2012-01-01

    Methane production and transport processes in peatlands are fairly well understood, but growing evidence for emission of methane through trees has highlighted the need to revisit methane transport processes. In wetland trees, morphological adaptations such as development of hypertrophied lenticels, aerenchyma and adventitious roots in response to soil anoxia mediates gas transport, transporting both oxygen from the atmosphere to oxygen-deprived roots and soil-produced methane from the root-zo...

  8. The physiological tolerance of the grey carpet shark (Chiloscyllium punctatum) and the epaulette shark (Hemiscyllium ocellatum) to anoxic exposure at three seasonal temperatures.

    Science.gov (United States)

    Chapman, Clint A; Harahush, Blake K; Renshaw, Gillian M C

    2011-09-01

    The epaulette shark (Hemiscyllium ocellatum) and the grey carpet shark (Chiloscyllium punctatum) are commonly found in periodically hypoxic environments. The ecophysiological time available for these animals to safely exploit these niches during different seasonal temperatures was examined. The time to loss of righting reflex (T (LRR)) was examined in response to an open ended anoxic challenge at three seasonal temperatures (23, 25 and 27°C). Ventilation rates were measured in an open ended anoxic challenge at 23°C and during 1.5 h of anoxia followed by 2 h of re-oxygenation at 23 and 25°C. The mean T (LRR) of epaulette and grey carpet sharks was inversely proportional to temperature. The T (LRR) was similar between species at 23°C; however, grey carpet sharks had significantly reduced T (LRR) at higher temperatures. During the standardised anoxic challenge, epaulette sharks entered into ventilatory depression significantly earlier at 25°C. During re-oxygenation, epaulette sharks exposed to anoxia at 23°C had no significant increase in ventilation rates. However, after anoxic challenge and re-oxygenation at 25°C, epaulette sharks showed a significant increase in ventilation rates during re-oxygenation. Grey carpet sharks displayed no evidence of ventilatory depression during anoxia. However, during re-oxygenation, grey carpet sharks had significantly elevated ventilation rates above pre-experimental levels and control animals. These data demonstrate that the anoxia tolerance times of both species were temperature dependent, with a significant reduction in the T (LRR) occurring at higher temperatures. Epaulette sharks had a significantly greater T (LRR) at higher temperatures than grey carpet sharks, which did not enter into a ventilatory depression.

  9. Comparative physiological selectivity of Pennsylvanian to Jurassic extinction in bony fish, sharks and invertebrates

    OpenAIRE

    Vazquez, Priscilla Rose

    2015-01-01

    The end-Permian and end-Triassic extinctions coincided with flood basalt eruptions that would have released large quantities of CO2 into the atmosphere, leading to ocean warming, anoxia, and perhaps acidification. Multiple stresses present during these extinction events provide analogues for anthropogenic CO2 emissions and can help us understand which taxonomic groups will be threatened by ocean acidification and warming. Bony fish and sharks (Actinoptyergii and Chondrichthyes) have cellular ...

  10. Acute effects of electromagnetic stimulation of the brain on cortical activity, cortical blood flow, blood pressure and heart rate in the cat: an evaluation of safety.

    OpenAIRE

    Eyre, J A; Flecknell, P. A.; Kenyon, B R; Koh, T H; Miller, S.

    1990-01-01

    The influence of repeated high intensity electromagnetic stimulation of the brain on cortical activity, cortical blood flow, blood pressure and heart rate has been investigated in the cat, to evaluate the safety of the method. The observations have been made in preparations under propofol anaesthesia before, during and after periods of anoxia. Electromagnetic stimulation of the brain evoked activity in descending motor pathways and was recorded by activity in the median nerve and by muscle tw...

  11. Disentangling direct and indirect effects of water table drawdown on above and belowground plant litter decomposition: Consequences for accumulation of organic matter in boreal peatlands.

    OpenAIRE

    Strakova, Petra; PenttilÀ, Timo; Laine, Jukka; Laiho, Raija

    2012-01-01

    Pristine peatlands are carbon (C) accumulating wetland ecosystems sustained by a high water table (WT) and consequent anoxia that slows down decomposition. Persistent WT drawdown as a response to climate and/or land-use change affects decomposition either directly through environmental factors such as increased oxygenation, or indirectly through changes in plant community composition. This study attempts to disentangle the direct and indirect effects of WT drawdown by measuring the relative i...

  12. Perspectives in Cell Cycle Regulation: Lessons from an Anoxic Vertebrate

    OpenAIRE

    Biggar, Kyle K.; Storey, Kenneth B.

    2009-01-01

    The ability of an animal, normally dependent on aerobic respiration, to suspend breathing and enter an anoxic state for long term survival is clearly a fascinating feat, and has been the focus of numerous biochemical studies. When anoxia tolerant turtles are faced with periods of oxygen deprivation, numerous physiological and biochemical alterations take place in order to facilitate vital reductions in ATP consumption. Such strategies include reversible post-translational modifications as wel...

  13. In Situ Hydrogen and Nitrous Oxide as Indicators of Concomitant Fermentation and Denitrification in the Alimentary Canal of the Earthworm Lumbricus terrestris▿

    OpenAIRE

    Wüst, Pia K.; Horn, Marcus A.; Drake, Harold L

    2009-01-01

    The earthworm gut is a unique microzone in aerated soils that has been proposed to selectively stimulate ingested soil microorganisms by its in situ conditions, which include anoxia, high water content, a near-neutral pH, and high concentrations of organic compounds. The central objective of this study was to resolve potential links between in situ conditions and anaerobic microbial activities during the gut passage of Lumbricus terrestris. Both H2 and N2O were emitted by living earthworms, a...

  14. The influence of the biological pump on ocean chemistry: implications for long-term trends in marine redox chemistry, the global carbon cycle, and marine animal ecosystems.

    Science.gov (United States)

    Meyer, K M; Ridgwell, A; Payne, J L

    2016-05-01

    The net export of organic matter from the surface ocean and its respiration at depth create vertical gradients in nutrient and oxygen availability that play a primary role in structuring marine ecosystems. Changes in the properties of this 'biological pump' have been hypothesized to account for important shifts in marine ecosystem structure, including the Cambrian explosion. However, the influence of variation in the behavior of the biological pump on ocean biogeochemistry remains poorly quantified, preventing any detailed exploration of how changes in the biological pump over geological time may have shaped long-term shifts in ocean chemistry, biogeochemical cycling, and ecosystem structure. Here, we use a 3-dimensional Earth system model of intermediate complexity to quantitatively explore the effects of the biological pump on marine chemistry. We find that when respiration of sinking organic matter is efficient, due to slower sinking or higher respiration rates, anoxia tends to be more prevalent and to occur in shallower waters. Consequently, the Phanerozoic trend toward less bottom-water anoxia in continental shelf settings can potentially be explained by a change in the spatial dynamics of nutrient cycling rather than by any change in the ocean phosphate inventory. The model results further suggest that the Phanerozoic decline in the prevalence ocean anoxia is, in part, a consequence of the evolution of larger phytoplankton, many of which produce mineralized tests. We hypothesize that the Phanerozoic trend toward greater animal abundance and metabolic demand was driven more by increased oxygen concentrations in shelf environments than by greater food (nutrient) availability. In fact, a lower-than-modern ocean phosphate inventory in our closed system model is unable to account for the Paleozoic prevalence of bottom-water anoxia. Overall, these model simulations suggest that the changing spatial distribution of photosynthesis and respiration in the oceans has

  15. Uranium isotopes distinguish two geochemically distinct stages during the later Cambrian SPICE event

    OpenAIRE

    Dahl, Tais W.; Boyle, Richard A.; Donald E Canfield; Connelly, James N.; Gill, Benjamin C.; Lenton, Timothy M.; Bizzarro, Martin

    2014-01-01

    Anoxic marine zones were common in early Paleozoic oceans (542–400 Ma), and present a potential link to atmospheric pO2 via feedbacks linking global marine phosphorous recycling, primary production and organic carbon burial. Uranium (U) isotopes in carbonate rocks track the extent of ocean anoxia, whereas carbon (C) and sulfur (S) isotopes track the burial of organic carbon and pyrite sulfur (primary long-term sources of atmospheric oxygen). In combination, these proxies therefore reveal the ...

  16. Care of diabetes complicated with bedsore%糖尿病合并压疮的护理

    Institute of Scientific and Technical Information of China (English)

    于淑英; 赵敏; 徐书卉

    2003-01-01

    @@ INTRODUCTION Bed score is formed due to continuous compression on local tissues and poor blood circulation.Local tissues were ischemia,anoxia and nutritious metabolism disorder and degeneration occurred.Because of low immunology function, poor nutritious status and hyperglycemia of diabetes patients,specificity of skin was increased to stimulations. Once injured, the wound is difficult to heal and thus care is difficult,as well.

  17. Phloem flow and sugar transport in Ricinus communis L. is inhibited under anoxic conditions of shoot or roots.

    Science.gov (United States)

    Peuke, Andreas D; Gessler, Arthur; Trumbore, Susan; Windt, Carel W; Homan, Natalia; Gerkema, Edo; VAN As, Henk

    2015-03-01

    Anoxic conditions should hamper the transport of sugar in the phloem, as this is an active process. The canopy is a carbohydrate source and the roots are carbohydrate sinks. By fumigating the shoot with N2 or flooding the rhizosphere, anoxic conditions in the source or sink, respectively, were induced. Volume flow, velocity, conducting area and stationary water of the phloem were assessed by non-invasive magnetic resonance imaging (MRI) flowmetry. Carbohydrates and δ(13) C in leaves, roots and phloem saps were determined. Following flooding, volume flow and conducting area of the phloem declined and sugar concentrations in leaves and in phloem saps slightly increased. Oligosaccharides appeared in phloem saps and after 3 d, carbon transport was reduced to 77%. Additionally, the xylem flow declined and showed finally no daily rhythm. Anoxia of the shoot resulted within minutes in a reduction of volume flow, conductive area and sucrose in the phloem sap decreased. Sugar transport dropped to below 40% by the end of the N2 treatment. However, volume flow and phloem sap sugar tended to recover during the N2 treatment. Both anoxia treatments hampered sugar transport. The flow velocity remained about constant, although phloem sap sugar concentration changed during treatments. Apparently, stored starch was remobilized under anoxia. PMID:24995994

  18. Killing of Brain Tumor Cells by Hypoxia-Responsive Element Mediated Expression of BAX

    Directory of Open Access Journals (Sweden)

    Hangjun Ruan

    1999-11-01

    Full Text Available The presence of radioresistant hypoxic cells in human brain tumors limits the overall effectiveness of conventional fractionated radiation therapy. Tumor-specific therapies that target hypoxic cells are clearly needed. We have investigated the expression of suicide genes under hypoxia by a hypoxia-responsive element (HRE, which can be activated through hypoxia-inducible factor-1 (HIF-1. We transfected plasmids containing multiple copies of HIRE into U-87 MG and U-251 MG-NCI human brain tumor cells and tested their ability to induce LacZ gene expression under anoxia. Gene expression under anoxia versus oxia was increased about 12-fold for U-87 MG cells and about fourfold for U-251 MG-NCI cells. At intermediate hypoxic conditions, increased LacZ gene expression in U-87 MG cells was induced by the plasmid that contained three HREs, but not by the plasmid with two HREs. Lastly, when we placed a suicide gene BAX under the control of HREs, cells transfected with the BAX plasmids were preferentially killed through apoptosis under anoxia. Our studies demonstrate that HRE-regulated gene expression is active in brain tumor cells, and that the amount of increased gene expression obtained is dependent on the cell line, the HIRE copy number, and the degree of hypoxia.

  19. Response of the JAK-STAT signaling pathway to oxygen deprivation in the red eared slider turtle, Trachemys scripta elegans.

    Science.gov (United States)

    Bansal, Saumya; Biggar, Kyle K; Krivoruchko, Anastasia; Storey, Kenneth B

    2016-11-15

    The red-eared slider turtle, Trachemys scripta elegans, is a model organism commonly used to study the environmental stress of anoxia. It exhibits multiple biochemical adaptations to ensure its survival during the winter months where quantities of oxygen are largely depleted. We proposed that JAK-STAT signaling would display stress responsive regulation to mediate the survival of the red-eared slider turtle, Trachemys scripta elegans, during anoxic stress. Importantly, the JAK-STAT signaling pathway is involved in transmitting extracellular signals to the nucleus resulting in the expression of select genes that aid cell survival and growth. Immunoblotting was used to compare the relative phosphorylation levels of JAK proteins, STAT proteins, and two of its inhibitors, SOCS and PIAS, in response to anoxia. A clear activation of the JAK-STAT pathway was observed in the liver tissue while no significant changes were found in the skeletal muscle. To further support our findings we also found an increase in mRNA transcripts of downstream targets of STATs, namely bcl-xL and bcl-2, using PCR analysis in the liver tissues. These findings suggest an important role for the JAK-STAT pathway in exhibiting natural anoxia tolerance by the red-eared slider turtle.

  20. Sensing and surviving hypoxia in vertebrates.

    Science.gov (United States)

    Jonz, Michael G; Buck, Leslie T; Perry, Steve F; Schwerte, Thorsten; Zaccone, Giacomo

    2016-02-01

    Surviving hypoxia is one of the most critical challenges faced by vertebrates. Most species have adapted to changing levels of oxygen in their environment with specialized organs that sense hypoxia, while only few have been uniquely adapted to survive prolonged periods of anoxia. The goal of this review is to present the most recent research on oxygen sensing, adaptation to hypoxia, and mechanisms of anoxia tolerance in nonmammalian vertebrates. We discuss the respiratory structures in fish, including the skin, gills, and air-breathing organs, and recent evidence for chemosensory neuroepithelial cells (NECs) in these tissues that initiate reflex responses to hypoxia. The use of the zebrafish as a genetic and developmental model has allowed observation of the ontogenesis of respiratory and chemosensory systems, demonstration of a putative intracellular O2 sensor in chemoreceptors that may initiate transduction of the hypoxia signal, and investigation into the effects of extreme hypoxia on cardiorespiratory development. Other organisms, such as goldfish and freshwater turtles, display a high degree of anoxia tolerance, and these models are revealing important adaptations at the cellular level, such as the regulation of glutamatergic and GABAergic neurotransmission in defense of homeostasis in central neurons. PMID:25959851

  1. Cyanide toxicity in hepatocytes under aerobic and anaerobic conditions.

    Science.gov (United States)

    Aw, T Y; Jones, D P

    1989-09-01

    The effect of cyanide on cell viability and mitochondrial function was studied in hepatocytes exposed to air or argon. Cells were more susceptible to cyanide toxicity under air than under argon. Analysis of the disposition of cyanide showed that the difference in susceptibility to KCN was not due to O2-dependent differences in cyanide metabolism or elimination. Studies of mitochondrial function revealed that cyanide under aerobic conditions resulted in substantial swelling of the mitochondria, which corresponded to a matrix loading of phosphate. In addition, cyanide caused a loss of the mitochondrial protonmotive force. This was in contrast to the results for cells exposed to 30 min of anoxia alone in which there was no loss of mitochondrial delta pH, no detectable change in mitochondrial volume, and little matrix loading of phosphate. These results show that at least some of the protective mechanisms elicited by anoxia (B. S. Andersson, T. Y. Aw, and D. P. Jones. Am. J. Physiol. 252 (Cell Physiol. 21): C349-C355, 1987) are not elicited by cyanide alone. Thus cyanide under aerobic conditions does not provide a completely valid model for simple anoxia. Moreover, the results suggest that the molecular sensor necessary to signal suppression of metabolic and transport functions during neahypoxia is dependent on O2 and is neither stimulated nor antagonized by KCN. PMID:2782387

  2. Biogeochemical effects of atmospheric oxygen concentration, phosphorus weathering, and sea-level stand on oceanic redox chemistry: Implications for greenhouse climates

    Science.gov (United States)

    Ozaki, Kazumi; Tajika, Eiichi

    2013-07-01

    Understanding the key factors influencing the global oceanic redox system is crucial to fully explaining the variations in oceanic chemical dynamics that have occurred throughout the Earth's history. In order to elucidate the mechanisms behind these variations on geological timescales, numerical sensitivity experiments were conducted with respect to the partial pressure of atmospheric molecular oxygen (pO2), the continental shelf area (Acs), and the riverine input rate of reactive phosphorus to the oceans (RP). The sensitivity experiment for atmospheric pO2 indicates that pervasive oceanic anoxia and euxinia appear when pO2oxygenation states by changing marine biogeochemical cycling; a large continental shelf acts as an efficient buffer against oceanic eutrophication and prevents the appearance of ocean anoxia/euxinia. We also found that an enhanced RP is an important mechanism for generation of widespread anoxia/euxinia via expansion of both the oxygen minimum zone and coastal deoxygenation, although the critical RP value depends significantly on pO2, Acs, and the redox-dependent burial efficiency of phosphorus at the sediment--water interface. Our systematic examination of the oceanic redox state under Cretaceous greenhouse climatic conditions also supports the above results.

  3. Antioxidant defences role during post anoxic recovery in bivalve mollusc Scapharca inaequivalvis

    Directory of Open Access Journals (Sweden)

    J. Foschi

    2011-01-01

    Full Text Available Euryoxic organisms are able to withstand hypoxic conditions until the restoration of normal O2 levels, when the re-introduction of oxygen causes a decisive burst in reactive oxygen species (ROS. The consequent oxidative damage is countered by defence systems constituted by antioxidant enzymes, such as SOD, CAT, Se-GPx and G6PDH. Specimens of Scapharca inaequivalvis were exposed to anoxia for 3, 6 and 24 hours and subsequent reoxygenation for 1, 3, 5 and 24 hours. It has been investigated SOD, CAT, Se-GPx and G6PDH activity and MnSOD and CuZnSOD expression in the digestive gland. The results showed SODs activity to be high during both anoxia and reoxygenation. CAT and Se-GPx increase significantly overall during recovery. Only CuZnSOD expression was greater after 6 and 24 hours of anoxia. The presence of high levels of antioxidant enzymes during anozia suggests that the response of S. inaequivalvis is typical of euryoxic animals and represents an interesting model for studying the processes of ischaemia/reperfusion in mammals.

  4. Attenuation of acute and chronic restraint stress-induced perturbations in experimental animals by Zingiber officinale Roscoe.

    Science.gov (United States)

    Lakshmi, B V S; Sudhakar, M

    2010-02-01

    Ethanolic extract of rhizomes of Zingiber officinale was investigated on anoxia stress tolerance test in Swiss mice. The animals were also subjected to acute physical stress (swimming endurance test) to gauge the anti-stress potential of the extract. Further to evaluate the anti-stress activity of Z. officinale in chronic stress condition, fresh Wistar rats were subjected to cold restraint stress (4 degrees for 2 h) for 10 days. Stimulation of hypothalamus pituitary adrenal axis in stressful condition alters plasma glucose, triglyceride, cholesterol, BUN and corticosterone levels. There is also alteration in the blood cell counts. Pretreatment with the extract significantly ameliorated the stress-induced variations in these biochemical levels and blood cell counts in both acute and chronic stress models. The extract treated animals showed increase in swimming endurance time and increase in anoxia tolerance time in physical and anoxia stress models, respectively. Treatment groups also reverted back increase in liver, adrenal gland weights and atrophy of spleen caused by cold chronic stress and swimming endurance stress models. The results indicate that ethanolic extract of Z. officinale has significant adaptogenic activity against a variety of biochemical and physiological perturbations in different stress models. PMID:19909780

  5. Changes in depth-transect redox conditions spanning the end-Permian mass extinction and their impact on the marine extinction: Evidence from biomarkers and sulfur isotopes

    Science.gov (United States)

    Kaiho, Kunio; Oba, Masahiro; Fukuda, Yoshihiko; Ito, Kosuke; Ariyoshi, Shun; Gorjan, Paul; Riu, Yuqing; Takahashi, Satoshi; Chen, Zhong-Qiang; Tong, Jinnan; Yamakita, Satoshi

    2012-08-01

    Changes in redox conditions during the Changhsingian to Griesbachian spanning the end-Permian mass extinction were recently reported based on analyses of organic molecules. We provide more precise organic-molecular data, that detail redox conditions spanning the end-Permian mass extinction at different palaeowater depths in the neritic Palaeotethys (estimated water depths: 10, 40, 100, and 200 m; Bulla, Huangzhishan, Meishan, and Chaohu sections, respectively) during this period. Here we propose that a change from occasional euxinia to anoxia in the shallow Palaeotethys occurred at the time of the mass extinction intercalated with oxic pulses. The second extinction at 0.7 myr after the main extinction was also caused by anoxia. New and published sulfur-isotope ratios (34S/32S) measured in carbonate-associated sulfate from the neritic Palaeotethys and in sulfide from pelagic central Panthalassa sediments show high values during the Changhsingian, consistent with the development of euxinia. The mass extinction coincided with a global fall in δ34S values, as well as a shift in δ13C values, indicating a global oxidation of H2S. This organic and isotopic geochemistry implies that accumulation of hydrogen sulfide in intermediate and deep waters followed by oxidation of hydrogen sulfide led to dissolved oxygen consumption, surface-water anoxia, and acidification, resulting in the end-Permian mass extinction in the seas.

  6. ''Live'' Prussian blue fading by time-resolved X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gervais, Claire [Smithsonian Institution Museum Conservation Institute, Suitland, MD (United States); Bern University of the Arts, Bern (Switzerland); Languille, Marie-Angelique [Synchrotron SOLEIL, IPANEMA, USR 3461 CNRS/MCC, Gif-sur-Yvette (France); Reguer, Solenn [Synchrotron SOLEIL, DiffAbs beamline, Gif-sur-Yvette (France); Gillet, Martine [Museum national d' histoire naturelle, Centre de Recherche sur la Conservation des Collections, Paris (France); Vicenzi, Edward P. [Smithsonian Institution Museum Conservation Institute, Suitland, MD (United States); Chagnot, Sebastien; Baudelet, Francois [Synchrotron SOLEIL, ODE beamline, Gif-sur-Yvette (France); Bertrand, Loic [Synchrotron SOLEIL, IPANEMA, USR 3461 CNRS/MCC, Gif-sur-Yvette (France); Synchrotron SOLEIL, Gif-sur-Yvette (France)

    2013-04-15

    Prussian blue (PB) is an artists' pigment that has been frequently used in many artworks but poses several problems of conservation because of its fading under light and anoxia treatment. PB fading is due to the reduction of iron(III) into iron(II) and depends a lot on the object investigated. Due to the complexity of the structure, the precise physico-chemical mechanisms behind the redox process remain obscure. In this paper, we present a procedure to investigate light- and anoxia-induced fading of PB-paper samples by means of time resolved X-ray absorption spectroscopy performed at the Fe K-edge. A system composed of a visible light source and a flux-controlled environmental cell allowed light, gas and humidity to be modified in situ. The synchrotron X-ray beam was evidenced to induce a reduction of PB and to play a major role in the kinetics. The analysis of the PB fading kinetics of a sample submitted to various gas and light environments showed that both synchrotron beam and anoxia were influencing PB reduction in a correlated way. In comparison, light was found to play a minor role. Finally, we have demonstrated that the type of paper substrate could influence significantly the kinetics of reduction. Several hypotheses to explain the correlation between PB reduction mechanism and substrate are presented. (orig.)

  7. Sensing and surviving hypoxia in vertebrates.

    Science.gov (United States)

    Jonz, Michael G; Buck, Leslie T; Perry, Steve F; Schwerte, Thorsten; Zaccone, Giacomo

    2016-02-01

    Surviving hypoxia is one of the most critical challenges faced by vertebrates. Most species have adapted to changing levels of oxygen in their environment with specialized organs that sense hypoxia, while only few have been uniquely adapted to survive prolonged periods of anoxia. The goal of this review is to present the most recent research on oxygen sensing, adaptation to hypoxia, and mechanisms of anoxia tolerance in nonmammalian vertebrates. We discuss the respiratory structures in fish, including the skin, gills, and air-breathing organs, and recent evidence for chemosensory neuroepithelial cells (NECs) in these tissues that initiate reflex responses to hypoxia. The use of the zebrafish as a genetic and developmental model has allowed observation of the ontogenesis of respiratory and chemosensory systems, demonstration of a putative intracellular O2 sensor in chemoreceptors that may initiate transduction of the hypoxia signal, and investigation into the effects of extreme hypoxia on cardiorespiratory development. Other organisms, such as goldfish and freshwater turtles, display a high degree of anoxia tolerance, and these models are revealing important adaptations at the cellular level, such as the regulation of glutamatergic and GABAergic neurotransmission in defense of homeostasis in central neurons.

  8. Phloem flow and sugar transport in Ricinus communis L. is inhibited under anoxic conditions of shoot or roots.

    Science.gov (United States)

    Peuke, Andreas D; Gessler, Arthur; Trumbore, Susan; Windt, Carel W; Homan, Natalia; Gerkema, Edo; VAN As, Henk

    2015-03-01

    Anoxic conditions should hamper the transport of sugar in the phloem, as this is an active process. The canopy is a carbohydrate source and the roots are carbohydrate sinks. By fumigating the shoot with N2 or flooding the rhizosphere, anoxic conditions in the source or sink, respectively, were induced. Volume flow, velocity, conducting area and stationary water of the phloem were assessed by non-invasive magnetic resonance imaging (MRI) flowmetry. Carbohydrates and δ(13) C in leaves, roots and phloem saps were determined. Following flooding, volume flow and conducting area of the phloem declined and sugar concentrations in leaves and in phloem saps slightly increased. Oligosaccharides appeared in phloem saps and after 3 d, carbon transport was reduced to 77%. Additionally, the xylem flow declined and showed finally no daily rhythm. Anoxia of the shoot resulted within minutes in a reduction of volume flow, conductive area and sucrose in the phloem sap decreased. Sugar transport dropped to below 40% by the end of the N2 treatment. However, volume flow and phloem sap sugar tended to recover during the N2 treatment. Both anoxia treatments hampered sugar transport. The flow velocity remained about constant, although phloem sap sugar concentration changed during treatments. Apparently, stored starch was remobilized under anoxia.

  9. Effects of elevated carbon dioxide concentrations on survivorship in zebra mussels (Dreissena polymorpha) and Asian clams (Corbicula fluminea)

    Energy Technology Data Exchange (ETDEWEB)

    McMahon, R.F.; Matthews, M.A.; Shaffer, L.R.; Johnson, P.D. [Univ. of Texas, Arlington, TX (United States)

    1995-06-01

    In order to determine their tolerance to elevated concentrations of carbon dioxide, Asian clams and zebra mussels were collected. Subsamples of both species were acclimated to 25{degrees}C>14 days and then exposed in water at 25{degrees}C to various concentrations of CO{sub 2} and survivorship recorded. Zebra mussels were allowed to byssally attach prior to testing. Media CO{sub 2} concentrations were maintained by continuous bubbling with appropriate gas mixtures. Gas treatment included: (1) anoxia; (2) hypercapnic anoxia; and (3) hypercapnic normoxia. Deaths were recorded in subsamples of both species every 12-24 h until 100% mortality was achieved. No significant mortality occurred among specimens of either species in air bubbled control media in any experiment. Mortality time of zebra mussels exposed to anoxia under 100% N{sub 2} was 103.7 h and of Asian clams, 349.7 h. Mortality was more rapid among samples of both species exposed to anoxia under 100% CO{sub 2}, mean time to death being 43.6 h for zebra mussels and 46.3 h for Asian clams. There was no difference in the survivorship of samples of either species under atmospheres of either 5% CO{sub 2} and 95% N{sub 2} or 100% N{sub 2}, however, Asian clams survived anoxia under either atmosphere 4 to 5 times longer than did zebra mussels. There was no significant mortality among Asian clam or zebra mussel samples after a 39 day exposure to hypercapnic normoxia. While exposure to hypercapnic normoxia under an atmosphere of 5% CO{sub 2}:19% O{sub 2}:76% N{sub 2} did not induce mortality in zebra mussel samples, it completely suppressed all byssal thread production after 7 days of exposure and induced all sampled individuals to release from their byssal attachments within 10 days of exposure. These results indicate that CO{sub 2} injection may be an easily applied, cost-effective, environmentally acceptable molluscicide for mitigation and control of raw water system macrofouling by Asian clams and zebra mussels.

  10. Controls on oxygen dynamics in a riverine salt-wedge estuary – a three-dimensional model of the Yarra River estuary, Australia

    Directory of Open Access Journals (Sweden)

    L. C. Bruce

    2013-07-01

    Full Text Available Oxygen depletion in estuarine waters is an important factor governing water quality and ecological health. A complex and dynamic balance of physical and biogeochemical factors drive the extent and persistence of hypoxia and anoxia making it difficult to predict. An increased understanding of the effect of changing flow regimes and temperature on patterns of estuarine oxygen depletion is required to support ongoing management. Coupled physical and biogeochemical models have been applied to study the interaction of physical processes and seasonal hypoxia, however, application to riverine estuaries with tight curvature and more sporadic periods of oxygen depletion is rare. In this study we apply a finite volume 3-D hydrodynamic-biogeochemical model (TUFLOW-FV–FABM to the Yarra River estuary, Australia, in order to predict the extent of salt-wedge intrusion and consequent patterns of oxygen depletion. The predictive capacity of the model was evaluated using a series of model verification metrics and the results evaluated to determine the dominant mechanisms affecting salt-wedge position and the extent and persistence of anoxia and hypoxia. Measures of model fit indicated that the model reasonably captured the strength of stratification and the position and extent of the salt wedge (r2 ~ 0.74. The extent of the salt wedge intrusion was controlled by riverine flow and the strength of stratification or mixing dominated by topographical features corresponding to areas of tight curvature ("horseshoe" bends. The model predicted that the extent of anoxic waters generally mimicked the extent of the salt wedge (r2 ~ 0.65 increasing during periods of low flow and reduced following episodic high flow events. The results showed two sporadically isolated "hot spots" of anoxia, the first downstream of the horseshoe bend and the second downstream of a sill. Simulated oxygen concentrations indicated that whilst a threshold salt wedge intrusion was a requirement

  11. Effects of cross-channel bathymetry and wind direction on destratification and hypoxia reduction in the Chesapeake Bay

    Science.gov (United States)

    Wang, Ping; Wang, Harry; Linker, Lewis; Tian, Richard

    2016-09-01

    A coupled estuarine hydrodynamic model and water quality model were used to analyze differences in destratification and anoxia/hypoxia reduction by wind directions in the north-south oriented Chesapeake estuary, USA. The predominant cross-channel bathymetry in the Bay's anoxic center is asymmetric with a steeper and narrower shoal on the eastern shore than on the western shore, which modifies wind-induced circulation differently for two opposite wind directions. Model experiments of winds for 2-day at 8 m/s indicated that, for a stratified water over the aforementioned asymmetric bottom topography, the easterly wind caused greater destratification and hypoxia reduction than the westerly wind. This is a result of differential modulations on the two wind-induced cross-channel circulations by the asymmetric cross channel bathymetry. The downwelling along the gentle slope in the easterly wind was characterized with stronger baroclinicity than the downwelling along the steep slope (nearly perpendicular to surfaces of constant density) in the westerly wind. On the broad slope, there undergo greater contrasting density readjustments to the vorticity changes around the bottom boundary layer (BBL) during upslope and downslope motions. During the upslope condition, the flow in BBL tends to decelerate under adverse pressure gradient which leads to a stable condition in the outer layer; whereas, during the downslope condition, the BBL tends to accelerate under favourable pressure gradient, which leads to unstable condition in the outer layer of the large scale flow. Overall, the easterly wind caused greater anoxia reduction than the westerly wind during the entire wind period. A similar case was found for northerly versus southerly winds in the early stages of the wind period; modulated by the aforementioned bathymetry on the wind-induced cross-channel circulation, the northerly wind caused greater anoxia reduction than the southerly wind. However, as wind continues, the wind

  12. Protein disulfide isomerase as a novel target for cyclopentenone prostaglandins: implications for hypoxic ischemic injury

    Science.gov (United States)

    Liu, Hao; Chen, Jie; Li, Wenjin; Rose, Marie E.; Shinde, Sunita N.; Balasubramani, Manimalha; Uechi, Guy T.; Mutus, Bülent; Graham, Steven H.; Hickey, Robert W.

    2016-01-01

    Cyclooxygenase-2 (COX-2) is an important contributor to ischemic brain injury. Identification of the downstream mediators of COX-2 toxicity may allow the development of targeted therapies. Of particular interest is the cyclopentenone family of prostaglandin metabolites. Cyclopentenone prostaglandins (CyPGs) are highly reactive molecules that form covalent bonds with cellular thiols. Protein disulfide isomerase (PDI) is an important molecule for the restoration of denatured proteins following ischemia. Because PDI has several thiols, including thiols within the active thioredoxin-like domain, we hypothesized that PDI is a target of CyPGs and that CyPG binding of PDI is detrimental. CyPG–PDI binding was detected in vitro via immunoprecipitation and MS. CyPG–PDI binding decreased PDI enzymatic activity in recombinant PDI treated with CyPG, and PDI immunoprecipitated from neuronal culture treated with CyPG or anoxia. Toxic effects of binding were demonstrated in experiments showing that: (a) pharmacologic inhibition of PDI increased cell death in anoxic neurons, (b) PDI overexpression protected neurons exposed to anoxia and SH-SY5Y cells exposed to CyPG, and (c) PDI overexpression in SH-SY5Y cells attenuated ubiquitination of proteins and decreased activation of pro-apoptotic caspases. In conclusion, CyPG production and subsequent binding of PDI is a novel and potentially important mechanism of ischemic brain injury. We show that CyPGs bind to PDI, cyclopentenones inhibit PDI activity, and CyPG–PDI binding is associated with increased neuronal susceptibility to anoxia. Additional studies are necessary to determine the relative role of CyPG-dependent inhibition of PDI activity in ischemia and other neurodegenerative disorders. PMID:25754985

  13. Glucose induces sensitivity to oxygen deprivation and modulates insulin/IGF-1 signaling and lipid biosynthesis in Caenorhabditis elegans.

    Science.gov (United States)

    Garcia, Anastacia M; Ladage, Mary L; Dumesnil, Dennis R; Zaman, Khadiza; Shulaev, Vladimir; Azad, Rajeev K; Padilla, Pamela A

    2015-05-01

    Diet is a central environmental factor that contributes to the phenotype and physiology of individuals. At the root of many human health issues is the excess of calorie intake relative to calorie expenditure. For example, the increasing amount of dietary sugars in the human diet is contributing to the rise of obesity and type 2 diabetes. Individuals with obesity and type 2 diabetes have compromised oxygen delivery, and thus it is of interest to investigate the impact a high-sugar diet has on oxygen deprivation responses. By utilizing the Caenorhabditis elegans genetic model system, which is anoxia tolerant, we determined that a glucose-supplemented diet negatively impacts responses to anoxia and that the insulin-like signaling pathway, through fatty acid and ceramide synthesis, modulates anoxia survival. Additionally, a glucose-supplemented diet alters lipid localization and initiates a positive chemotaxis response. Use of RNA-sequencing analysis to compare gene expression responses in animals fed either a standard or glucose-supplemented diet revealed that glucose impacts the expression of genes involved with multiple cellular processes including lipid and carbohydrate metabolism, stress responses, cell division, and extracellular functions. Several of the genes we identified show homology to human genes that are differentially regulated in response to obesity or type 2 diabetes, suggesting that there may be conserved gene expression responses between C. elegans fed a glucose-supplemented diet and a diabetic and/or obesity state observed in humans. These findings support the utility of the C. elegans model for understanding the molecular mechanisms regulating dietary-induced metabolic diseases. PMID:25762526

  14. Mechanisms of damage to corals exposed to sedimentation.

    Science.gov (United States)

    Weber, Miriam; de Beer, Dirk; Lott, Christian; Polerecky, Lubos; Kohls, Katharina; Abed, Raeid M M; Ferdelman, Timothy G; Fabricius, Katharina E

    2012-06-12

    We investigated the mechanisms leading to rapid death of corals when exposed to runoff and resuspended sediments, postulating that the killing was microbially mediated. Microsensor measurements were conducted in mesocosm experiments and in naturally accumulated sediment on corals. In organic-rich, but not in organic-poor sediment, pH and oxygen started to decrease as soon as the sediment accumulated on the coral. Organic-rich sediments caused tissue degradation within 1 d, whereas organic-poor sediments had no effect after 6 d. In the harmful organic-rich sediment, hydrogen sulfide concentrations were low initially but increased progressively because of the degradation of coral mucus and dead tissue. Dark incubations of corals showed that separate exposures to darkness, anoxia, and low pH did not cause mortality within 4 d. However, the combination of anoxia and low pH led to colony death within 24 h. When hydrogen sulfide was added after 12 h of anoxia and low pH, colonies died after an additional 3 h. We suggest that sedimentation kills corals through microbial processes triggered by the organic matter in the sediments, namely respiration and presumably fermentation and desulfurylation of products from tissue degradation. First, increased microbial respiration results in reduced O(2) and pH, initiating tissue degradation. Subsequently, the hydrogen sulfide formed by bacterial decomposition of coral tissue and mucus diffuses to the neighboring tissues, accelerating the spread of colony mortality. Our data suggest that the organic enrichment of coastal sediments is a key process in the degradation of coral reefs exposed to terrestrial runoff. PMID:22615403

  15. Plant water stress: Associations between ethylene and abscisic acid response

    Directory of Open Access Journals (Sweden)

    Carolina Salazar

    2015-08-01

    Full Text Available Agriculture is severely impacted by water stress due either to excess (hypoxia/anoxia or deficit of water availability. Hypoxia/anoxia is associated with oxygen (O2 deficiency or depletion, inducing several anatomical, morphological, physiological, and molecular changes. The majority of these alterations are adaptive mechanisms to cope with low O2 availability; among them, alterations in shoot length, aerenchyma formation and adventitious roots have been described in several studies. The aim of this review was to address the association between abscisic acid (ABA and ethylene in function of water availability in plants. The major physiological responses to low O2 are associated with changes in root respiration, stomatal conductance, photosynthesis, and fermentation pathways in roots. In addition, several changes in gene expression have been associated with pathways that are not present under normal O2 supply. The expression of ethylene receptor genes is up-regulated by low O2, and ethylene seems to have a crucial role in anatomical and physiological effects during hypoxia/anoxia. During O2 depletion, ethylene accumulation down-regulates ABA by inhibiting rate-limiting enzymes in ABA biosynthesis and by activating ABA breakdown to phaseic acid. With regard to water deficit, drought is primarily sensed by the roots, inducing a signal cascade to the shoots via xylem causing physiological and morphological changes. Several genes are regulated up or down with osmotic stress; the majority of these responsive genes can be driven by either an ABA-dependent or ABA-independent pathway. Some studies suggest that ethylene shuts down leaf growth very fast after the plant senses limited water availability. Ethylene accumulation can antagonize the control of gas exchange and leaf growth upon drought and ABA accumulation.

  16. Molecular, physiological and morphological analysis of waterlogging tolerance in clonal genotypes of Theobroma cacao L.

    Science.gov (United States)

    Bertolde, Fabiana Zanelato; De Almeida, Alex-Alan Furtado; Corrêa, Ronan Xavier; Gomes, Fábio Pinto; Gaiotto, Fernanda Amato; Baligar, Virupax C; Loguercio, Leandro Lopes

    2010-01-01

    In soil, anoxia conditions generated by waterlogging induce changes in genetic, morphological and physiological processes, altering the growth and development of plants. Mass propagation of cacao (Theobroma cacao L.) plantlets (clones) is affected by waterlogging caused by heavy rains and irrigation methods used to induce rooting. An experiment was undertaken to assess the effects of a 45-day flooding (anoxia) on physiological and morphological traits of 35 elite cacao genotypes, aiming at potentially identifying those with greater tolerance to flooding of the growth substrate. Eighteen fluorochrome-labeled microsatellite (SSR) primer pairs were used to assess genetic variability among clones, with 248 alleles being amplified and used to calculate similarity coefficients. The resulting dendrogram indicated the presence of four major groups, in which two represented 60% and 31% of the genotypes tested. A general trend toward high levels of heterozygosity was also found for physiological and morphological traits. The survival index (IS) for flood tolerance observed varied from 30 to 96%. Clones TSA-654, TSA-656, TSA-792, CA-1.4, CEPEC-2009 and PH-17 showed an IS value above 94%, whereas CEPEC-2010, CEPEC-2002, CA-7.1 and VB-903 clones were those mostly affected by waterlogging, with IS value below 56%. All genotypes displayed lenticel and adventitious root formation in response to waterlogging, although with different intensities. To determine whether patterns of physiological response could be associated with tolerance to anoxia, a similarity-grouping analysis was performed using the ratio between waterlogged and control values obtained for a series of physiological variables assessed. No specific pattern of physiological and morphological responses to waterlogging was strictly associated with survival of plantlets. However, results revealed by the dendrogram suggest that absence of leaf chlorosis may be a proper trait to indicate cacao clones with higher survival

  17. Profiles of nuclear and mitochondrial encoded mRNAs in developing and quiescent embryos of Artemia franciscana.

    Science.gov (United States)

    Hardewig, I; Anchordoguy, T J; Crawford, D L; Hand, S C

    1996-05-24

    Embryos of the brine shrimp Artemia franciscana are able to withstand long bouts of environmental anoxia by entering a quiescent state during which metabolism is greatly depressed. Recent evidence supports a global arrest of protein synthesis during quiescence. In this study we measured the amounts of mRNA for a mitochondrial-encoded subunit of cytochrome c oxidase (COX I) and for nuclear-encoded actin during aerobic development, anaerobiosis, and aerobic acidosis (artificial quiescence imposed by intracellular acidification under aerobic conditions). The levels of both COX I and actin transcripts increased significantly during aerobic development. COX I mRNA levels were tightly correlated with previous measures of COX catalytic activity, which suggests that COX synthesis could be regulated by message concentration during aerobic development. The ontogenetic increase for these mRNAs was blocked by anoxia and aerobic acidosis. Importantly, the levels of COX I and actin mRNA did not decline appreciably during the 6 h bouts of quiescence, even though protein synthesis is acutely arrested by these same treatments. Thus, the constancy of mRNA levels during quiescence indicate that reduced protein synthesis is not caused by message limitation, but rather, is likely controlled at the translational level. One advantage of this regulatory mechanism is the conservation of mRNA molecules during quiescence, which would potentially favor a quick resumption of translation as soon as oxygen is returned to the embryos. Finally, because anoxia and aerobic acidosis are both characterized by acidic intracellular pH, the reduction in pH may serve, directly or indirectly, as one signal regulating levels of mRNA in this embryo during quiescence. PMID:8817476

  18. Oxygen, pHi and arrest of biosynthesis in brine shrimp embryos.

    Science.gov (United States)

    Hand, S C

    1997-12-01

    Embryos of the brine shrimp Artemia franciscana are able to withstand bouts of environmental anoxia for several years by entering a quiescent state, during which time metabolism is greatly depressed. Within minutes of oxygen removal, intracellular pH (pHi) drops at least 1.0 unit. This acidification has been strongly implicated in the arrest of both catabolic and anabolic processes in the cytoplasm. A global arrest of cytoplasmic translation accompanies the transition into anoxia or into aerobic acidosis (artificial quiescence imposed by intracellular acidification with CO2 in the presence of oxygen). Similarly, protein synthesis in isolated mitochondria from these embryos is also reduced markedly in response to acidic pH (80% reduction) or anoxia (79% reduction). The constancy of mRNA levels during quiescence indicates that protein synthesis is likely to be controlled at the translational level. Mitochondrial matrix pH is 8.2 during protein synthesis assays performed at the extramitochondrial pH optimum of 7.5. When this proton gradient is abolished with the K+/H+ ionophore nigericin, the extramitochondrial pH optimum for protein synthesis displays an alkaline shift of approximately 0.7 pH unit. These data suggest the presence of proton-sensitive translational components within the mitochondrion. The oxygen dependency of mitochondrial protein synthesis is not explained simply by blockage of the electron transport chain or by the increased redox state. Whereas oxygen deprivation substantially depresses protein synthesis by 77% after 1 h, normoxic incubations with saturating concentrations of cyanide or antimycin A have only a modest effect (36% reduction, cyanide; 20%, antimycin A). This cyanide- and antimycin-insensitive, but hypoxia-sensitive, inhibitory signature for the arrest of protein synthesis suggests the presence of a molecular oxygen sensor within the mitochondrion. PMID:9429663

  19. Effect of Cretaceous oceanic anoxic events on the evolutionary trend of planktonic foraminifera

    Science.gov (United States)

    Kuroyanagi, A.; Ozaki, K.; Kawahata, H.

    2014-12-01

    It is widely thought that oceanic redox state is essential for the evolutionary history of life on the earth, and "anoxic events" have been proposed as one of the causal mechanisms for mass extinctions. During mid-Cretaceous, widely known as the extremely warm period, oceanic anoxic events (OAEs) occurred several times and they would have caused a substantial impact on the biosphere. Planktonic foraminifera are marine planktons with calcite tests and their productions constitute ~30-80% of the modern deep-marine calcite budget, thus they play an important role in the global carbon cycle. Previous study reported that planktonic foraminifera displayed the high turnover (extinction and speciation) rate at or near the major OAEs. However, the impact of Cretaceous OAEs on the evolutionary trend of planktonic foraminifera remains obscure. In this study, we investigated the role of spatiotemporal extent of anoxia on the evolutionary trend of planktonic foraminifera by assessing the extinction/speciation rate of planktonic foraminifera around Cretaceous OAEs. The number of foraminiferal species increased across the OAE1a and then showed a peak after this episode. Around OAE2, several planktonic foraminifera species became extinct and several speciated, however, long-term trends in foraminiferal evolution showed no drastic changes near the event. Therefore these results suggest that the ocean surface environment at OAEs would not have a direct effect on foraminiferal extinction/speciation. This interpretation is reinforced when considering the recent culturing results, which demonstrate that modern planktonic foraminifera have a high tolerance to extremely low dissolved oxygen levels than expected. Accumulating geochemical data also suggest a spatial heterogeneity of oceanic anoxia/euxinia during OAE2. These results lead us to conclude that Cretaceous OAEs would not directly related to planktonic foraminiferal extinction due to regional distribution of anoxia/euxinia.

  20. Comparison of Nitrogen Oxide Metabolism among Diverse Ammonia-Oxidizing Bacteria

    Science.gov (United States)

    Kozlowski, Jessica A.; Kits, K. Dimitri; Stein, Lisa Y.

    2016-01-01

    Ammonia-oxidizing bacteria (AOB) have well characterized genes that encode and express nitrite reductases (NIR) and nitric oxide reductases (NOR). However, the connection between presence or absence of these and other genes for nitrogen transformations with the physiological production of nitric oxide (NO) and nitrous oxide (N2O) has not been tested across AOB isolated from various trophic states, with diverse phylogeny, and with closed genomes. It is therefore unclear if genomic content for nitrogen oxide metabolism is predictive of net N2O production. Instantaneous microrespirometry experiments were utilized to measure NO and N2O emitted by AOB during active oxidation of ammonia (NH3) or hydroxylamine (NH2OH) and through a period of anoxia. This data was used in concert with genomic content and phylogeny to assess whether taxonomic factors were predictive of nitrogen oxide metabolism. Results showed that two oligotrophic AOB strains lacking annotated NOR-encoding genes released large quantities of NO and produced N2O abiologically at the onset of anoxia following NH3-oxidation. Furthermore, high concentrations of N2O were measured during active O2-dependent NH2OH oxidation by the two oligotrophic AOB in contrast to non-oligotrophic strains that only produced N2O at the onset of anoxia. Therefore, complete nitrifier denitrification did not occur in the two oligotrophic strains, but did occur in meso- and eutrophic strains, even in Nitrosomonas communis Nm2 that lacks an annotated NIR-encoding gene. Regardless of mechanism, all AOB strains produced measureable N2O under tested conditions. This work further confirms that AOB require NOR activity to enzymatically reduce NO to N2O in the nitrifier denitrification pathway, and also that abiotic reactions play an important role in N2O formation, in oligotrophic AOB lacking NOR activity. PMID:27462312

  1. Phosphorus recycling and burial in Baltic Sea sediments with contrasting redox conditions

    DEFF Research Database (Denmark)

    Mort, Haydon P; Slomp, Caroline P; Gustafson, Bo G;

    2010-01-01

    . Most burial of P takes place as organic P. We find no evidence for significant authigenic Ca–P formation or biogenic Ca–P burial. The lack of major inorganic P burial sinks makes the Baltic Sea very sensitive to the feedback loop between increased hypoxia, enhanced regeneration of P and increased...... primary productivity. Historical records of bottom water oxygen at two sites (Bornholm, Northern Gotland) show a decline over the past century and are accompanied by a rise in values for typical sediment proxies for anoxia (total sulfur, molybdenum and organic C/P ratios). While sediment reactive P...

  2. Scandinavian clinical practice guidelines for therapeutic hypothermia and post-resuscitation care after cardiac arrest

    DEFF Research Database (Denmark)

    Castrén, M; Silfvast, T; Rubertsson, S;

    2009-01-01

    of Anaesthesiology and Intensive Care Medicine (SSAI). METHODS: Relevant studies were identified after two consensus meetings of the SSAI Task Force on Therapeutic Hypothermia (SSAITFTH) and via literature search of the Cochrane Central Register of Controlled Trials and Medline. Evidence was assessed and consensus...... fibrillation (GOR A), the SSAITFTH also recommend MTH after restored spontaneous circulation, if active treatment is chosen, in patients with initial pulseless electrical activity and asystole (GOR D). Normal ethical considerations, premorbid status, total anoxia time and general condition should decide...

  3. Paleocene–Eocene warming and biotic response in the epicontinental West Siberian Sea

    OpenAIRE

    Frieling, J.; Iakovleva, A.I.; Reichart, G.-J.; Aleksandrova, G.N.; Gnibidenko, Z.N.; Schouten, S.; A. Sluijs

    2014-01-01

    We present a Paleocene–Eocene (ca. 60–52 Ma) sea-surface temperature record from sediments deposited in the epicontinental West Siberian Sea. TEX86 paleothermometry indicates long-term late Paleocene (~17 °C ca. 59 Ma) to early Eocene (26 °C at 52 Ma) sea-surface warming, consistent with trends previously observed for the Southern Ocean and deep oceans. Photic zone and seafloor anoxia developed as temperatures rose by 7 °C to ~27 °C during the Paleocene–Eocene Thermal Maximum (PETM). Based on...

  4. Hidden biosphere in an oxygen-deficient Atlantic open ocean eddy: future implications of ocean deoxygenation on primary production in the eastern tropical North Atlantic

    Science.gov (United States)

    Loescher, Carolin; Fischer, Martin; Neulinger, Sven; Fiedler, Björn; Philippi, Miriam; Schütte, Florian; Singh, Arvind; Hauss, Helena; Karstensen, Johannes; Körtzinger, Arne; Schmitz, Ruth

    2016-04-01

    The eastern tropical North Atlantic (ETNA) is characterized by a highly productive coastal upwelling system and a moderate oxygen minimum zone with lowest open ocean oxygen (O2) concentrations of approximately 40 μmol kg-1. The recent discovery of re-occurring mesoscale eddies with close to anoxic O2 concentrations (promoted transcription of the key gene for denitrification, nirS. This process is usually absent from the open ETNA waters. In light of future projected ocean deoxygenation, our results show that even distinct events of anoxia have the potential to alter microbial community structure with critical impacts on primary productivity and biogeochemical processes of oceanic water bodies.

  5. Restoration of nucleic acid biosynthesis after clinical death and factors stimulating the process in vivo.

    Science.gov (United States)

    Konikova, A S; Petukhova, L M; Pogossova, A V; Vinarskaya, A A; Nikulin, V I

    1975-01-01

    The biosynthesis of RNA and DNA falls almost to zero in 60 min after the death of rabbits from anoxia, in all the organs of the body. Rapid artificial cooling of the rabbits to 20 degrees C undertaken within 10 min after death preserved nucleic acid biosynthesis and permitted restoration of life 3-4 h after death, with recovery beginning in 60 min. During the reanimation the addition of ATP to the blood stimulated the restoration of RNA biosynthesis in the spinal cord to a considerable extent; the addition of cocarboxylase to the blood promoted cardiac RNA biosynthesis as well as cardiac and pancreatic DNA biosynthesis during recovery. PMID:1197938

  6. [Importance of cooling after death for restoration of metabolism during resuscitation].

    Science.gov (United States)

    Pogosova, A V; Petukhova, L M; Nikulin, V I; Konikova, A S

    1978-01-01

    Incorporation of labelled metabolites into proteins, RNA and DNA was completely inhibited in rabbit tissues under conditions of prolonged hypothermia (10 degrees). The incorporation of labelled metabolites into all the biopolymers studied was restored after subsequent warming up to 38 degrees. Within 60-90 min after death of the animals due to acute anoxia, the labelled metabolites did not incorporate into protein, RNA and DNA. Artificial postmortal hypothermia (20 degrees) increased (by about 2.5-3-fold) the period of viability, during which reanimation is possible. The hypothermia enables subsequent restoration of the anabolic processes from the zero level. PMID:734984

  7. Evaluación de la varazón y contaminación en la Bahía Paracas – Pisco

    OpenAIRE

    Jacinto, María Elena; Martínez, Carlos; Sánchez, Sonia; Flores, Georgina; Pizarro, Luis

    1996-01-01

    Presenta los resultados de las prospecciones realizadas el 29 de abril y el 4-7 de mayo de 1995 como consecuencia de la varazón de lizas acaecido el 25 de abril en las playas de Santo Domingo, Pisco-Perú. Durante el operativo se realizó una evaluación, física, química y biológica del ecosistema marino costero el cual incluyó la cuantificación de hidrocarburos de petróleo. Los resultados demostraron condiciones críticas en el ambiente acuático (anoxia, sulfuros elevados, grandes cantidades de ...

  8. Was ocean acidification responsible for history's greatest extinction?

    Science.gov (United States)

    Schultz, Colin

    2011-11-01

    Two hundred fifty million years ago, the world suffered the greatest recorded extinction of all time. More than 90% of marine animals and a majority of terrestrial species disappeared, yet the cause of the Permian-Triassic boundary (PTB) dieoff remains unknown. Various theories abound, with most focusing on rampant Siberian volcanism and its potential consequences: global warming, carbon dioxide poisoning, ocean acidification, or the severe drawdown of oceanic dissolved oxygen levels, also known as anoxia. To narrow the range of possible causes, Montenegro et al. ran climate simulations for PTB using the University of Victoria Earth System Climate Model, a carbon cycle-climate coupled general circulation model.

  9. Late Devonian red tide and mass extinction

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Molecular stratigraphical, carbonate carbon isotopic, stratigraphical and paleontological data show that algal booming, eutrophication, anoxia, hypersalinity, positive ( 13C excursion and biomass decreasing occurred in the offshore carbonate environments of the Frasnian-Famennian (F-F) transition, which hints that red tide might frequently take place in the F-F transition of Guangxi, South China. We suggest that the mass extinction of the reef ecosystems and the shallow-water marine organisms in the F-F transition of the lower-middle latitudes may be related to the frequent occurrence of red tide in that time.

  10. Variaciones sedimentarias, mineralógicas, geoquímicas y bióticas en el Triásico Inferior - Medio ( en facies Buntsandstein) de las Cordilleras Ibérica y Costero Catalana: implicaciones en la recuperación de la crisis permo-triásica

    OpenAIRE

    Galán Abellán, Ana Belén

    2011-01-01

    La crisis de la transición Pérmico-Triásico produjo la desaparición del 75-95% de la especies, tanto en ambientes terrestres como en los océanos. Las emisiones de gases producidas por erupciones volcánicas, junto con la liberación de CH4 en los fondos oceánicos, principalmente, dieron lugar a un importante deterioro ambiental. Sus consecuencias, como lluvia ácida, anoxia en los fondos marinos y el calentamiento global, favorecieron la aparición de unas condiciones adversas para el desarrol...

  11. Participación de los canales de calcio dependientes de voltaje en el desarrollo de la epilepsia

    OpenAIRE

    Jesús Servando Medel Matus; Fernando Rafael Ramos Morales; José Correa Basurto; Jesús Samuel Cruz Sánchez; Margarita Virginia Saavedra Vélez; Vicente Velásquez Melgarejo

    2010-01-01

    La epilepsia es una afección crónica producida por diferentes etiologías, caracterizada por la repetición de crisis debidas a una descarga excesiva de las neuronas cerebrales asociadas a síntomas clínicos o paraclínicos. Se debe a una despolarización rápida, en la membrana, de iones en una población de neuronas susceptibles, es decir, un cambio repentino en la carga intracelular negativa a positiva. Las causas más conocidas son: alteraciones genéticas, anoxia perinatal, traumatismos, tumores,...

  12. Multiple regulatory mechanisms in the chloroplast of green algae: relation to hydrogen production.

    Science.gov (United States)

    Antal, Taras K; Krendeleva, Tatyana E; Tyystjärvi, Esa

    2015-09-01

    A complex regulatory network in the chloroplast of green algae provides an efficient tool for maintenance of energy and redox balance in the cell under aerobic and anaerobic conditions. In this review, we discuss the structural and functional organizations of electron transport pathways in the chloroplast, and regulation of photosynthesis in the green microalga Chlamydomonas reinhardtii. The focus is on the regulatory mechanisms induced in response to nutrient deficiency stress and anoxia and especially on the role of a hydrogenase-mediated reaction in adaptation to highly reducing conditions and ATP deficiency in the cell. PMID:25986411

  13. Hypoxic conditions and oxygen supply in nests of the mangrove ant, Camponotus anderseni, during and after inundation

    DEFF Research Database (Denmark)

    Nielsen, Mogens Gissel; Christian, K.; Malte, H.

    2009-01-01

    The small ant Camponotus anderseni lives exclusively in twigs of the mangrove tree Sonneratia alba, and during inundation, the entrance hole is blocked with a soldier's head which effectively prevents flooding. The nests can be very crowded, with the ants and coccids filling up to 50% of the volume...... is to avoid drowning without suffering anoxia or hypercapnia, and they show a remarkable ability to adapt to the extreme conditions in the mangrove and exploit a niche where the density of other ants is insignificant....

  14. Metabolic responses to hypoxia of Lycenchelys verrillii (wolf eelpout) and Glyptocephalus cynoglossus (witch flounder): Sedentary bottom fishes of the Hatteras/Virginia middle slope

    Science.gov (United States)

    Moser, M.L.; Ross, S.W.; Sulak, K.J.

    1996-01-01

    We collected wolf eelpouts Lycenchelys verrillii and witch flounder Glyptocephalus cynoglossus from Hatteras (North Carolina, USA) and Virginia (USA) Middle Slope sites using a submersible, and made shipboard measurements of their respiration rates and survival in hypoxic (Virginia site maintained a constant respiration rate until oxygen saturation dropped below 20%. Moreover, eelpouts from the Hatteras site were significantly more tolerant of hypoxic conditions than fish from the Virginia site and survived anoxia for short periods. These results and our submersible observations of fish behavior support the hypothesis that the Hatteras Middle Slope fauna is exposed to short-term hypoxia events.

  15. Spatial oxygen distribution and nitrous oxide emissions from soil after manure application

    DEFF Research Database (Denmark)

    Zhu, Kun; Bruun, Sander; Larsen, Morten;

    2014-01-01

    The availability and spatial distribution of oxygen (O2) in agricultural soil are controlling factors in the production and emission of nitrous oxide (N2O) to the atmosphere, but most experiments investigating the effects of various factors on N2O emissions in soil have been conducted without...... anoxia. Nitrous oxide emissions increased immediately after depletion of O2 in the manure-amended treatments. Greater understanding and improved knowledge of the spatial distribution of O2 is clearly beneficial and can be used to devise improved application strategies for mitigating N2O emissions from...

  16. Hemorragia pulmonar masiva presentada como muerte súbita neonatal Massive pulmonary haemorrhage presented as sudden neonatal death

    OpenAIRE

    J. Blanco Pampín; S. García Rivero

    2003-01-01

    La hemorragia pulmonar masiva en los recién nacidos, es una patología grave con una elevada tasa de mortalidad. En el presente artículo, se describe el caso de una recién nacida que fallece súbitamente, tras un intervalo de vida de 4 días, sin signos patológicos ni manifestaciones clínicas previas. Durante el parto había sufrido una severa anoxia. Repentinamente, presenta un cuadro de disnea progresiva y hemoptisis. Tras varios intentos infructuosos de reanimación, fallece al cabo de una hora...

  17. HPLC Fingerprint and LC/MS/MS Identification of the Active Components in Radix Salviae Miltiorrhizae

    Institute of Scientific and Technical Information of China (English)

    HU,Ping; LIANG,Qiong-Lin; LUO,Guo-An; JIANG,Zhi-Hong

    2004-01-01

    @@ Radix Salviae Miltiorrhizae (丹参, RSM), an important Chinese Materia Medica, is widely used for cardiovascular diseases in China. Phenolic compounds[1] and diterpenoids[2] which are the major constituents of RSM have been reported to protect myocardium against ischemia-induced derangement, protect neural cells against injuries caused by anoxia,inhibit platelet aggregation, reduce hepatic fibrosis and depress the activities of HIV-1.[3] For the purposes of establishing quality standard of RSM and studying the relationship between the pharmacological activities and quantities of constituents, we conducted studies on HPLC fingerprint and LC-MS-MS identification of the active constituents of RSM.

  18. Visual patch clamp recording of neurons in thick portions of the adult spinal cord

    DEFF Research Database (Denmark)

    Munch, Anders Sonne; Smith, Morten; Moldovan, Mihai;

    2010-01-01

    The study of visually identified neurons in slice preparations from the central nervous system offers considerable advantages over in vivo preparations including high mechanical stability in the absence of anaesthesia and full control of the extracellular medium. However, because of their relative...... thinness, slices are not appropriate for investigating how individual neurons integrate synaptic inputs generated by large numbers of neurons. Here we took advantage of the exceptional resistance of the turtle to anoxia to make slices of increasing thicknesses (from 300 to 3000 microm) from the lumbar...

  19. Evolution of respiratory adaptations in hydrothermal vent scale-worms (Polynoidae)

    OpenAIRE

    Projecto‑Garcia, Joana Cristina

    2009-01-01

    Hydrothermal vents are deep-sea ecosystems that are characterized by widely changing chemical and physical characteristics that are the result of the chaotic mixing of the hydrothermal fluid, rich in toxic compounds, such as sulfide and heavy metals, with low pH, high temperature and no oxygen; with the deep-sea water that contains no heavy metals, has a pH of ~7.8, low temperature and normal oxygen concentrations. Among others constraints, hypoxia and anoxia pose a serious problem for the fa...

  20. Triterpenoid saponins from Clematis tangutica and their cardioprotective activities.

    Science.gov (United States)

    Zhang, Wei; Wang, Xiaoyang; Tang, Haifeng; Wang, Minchang; Ji, Lanju; Wen, Aidong; Wang, Jianbo

    2013-01-01

    Phytochemical investigation of the whole plants of Clematis tangutica led to the isolation of three new triterpenoid saponins (1-3), together with four known saponins (4-7). Their structures were determined by extensive spectral analysis and chemical evidences. Compounds 1-7 were evaluated for their cardioprotective activities in cardiomyocytes anoxia/reoxygenation (A/R) model. The results showed that those saponins exhibited cardioprotective effects by decreasing the levels of creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH). PMID:23266737

  1. Authigenic Carbonate and the History of the Global Carbon Cycle

    Science.gov (United States)

    Schrag, Daniel P.; Higgins, John. A.; Macdonald, Francis A.; Johnston, David T.

    2013-02-01

    We present a framework for interpreting the carbon isotopic composition of sedimentary rocks, which in turn requires a fundamental reinterpretation of the carbon cycle and redox budgets over Earth's history. We propose that authigenic carbonate, produced in sediment pore fluids during early diagenesis, has played a major role in the carbon cycle in the past. This sink constitutes a minor component of the carbon isotope mass balance under the modern, high levels of atmospheric oxygen but was much larger in times of low atmospheric O2 or widespread marine anoxia. Waxing and waning of a global authigenic carbonate sink helps to explain extreme carbon isotope variations in the Proterozoic, Paleozoic, and Triassic.

  2. Variability of the North Atlantic Oscillation over the past 5,200 years

    DEFF Research Database (Denmark)

    Olsen, Jesper; Anderson, N. John; Knudsen, Mads Faurschou

    2012-01-01

    index is positive, Europe and the eastern US are mild and wet, whereas Greenland and northern Canada are cold and dry. A negative index is associated with the reverse pattern. Reconstructions of the NAO have so far been limited to the past 900 years(3). Here we analyse a 5,200-year-long, high......-resolution lake sediment record from southwestern Greenland to reconstruct lake hypolimnic anoxia, and link the results to an existing reconstruction of the NAO index from tree rings and speleothems(3). Using the relationship between the two records, we find that around 4,500 and 650 years ago-around the end of...

  3. Growth Induction and Low-Oxygen Apoptosis Inhibition of Human CD34+ Progenitors in Collagen Gels

    Directory of Open Access Journals (Sweden)

    Daniele Avitabile

    2013-01-01

    Full Text Available Various reports have indicated low survival of injected progenitors into unfavorable environments such as the ischemic myocardium or lower limb tissues. This represents a major bottleneck in stem-cell-based cardiovascular regenerative medicine. Strategies to enhance survival of these cells in recipient tissues have been therefore sought to improve stem cell survival and ensure long-term engraftment. In the present contribution, we show that embedding human cord blood-derived CD34+ cells into a collagen I-based hydrogel containing cytokines is a suitable strategy to promote stem cell proliferation and protect these cells from anoxia-induced apoptosis.

  4. Denitrification Response Patterns during the Transition to Anoxic Respiration and Posttranscriptional Effects of Suboptimal pH on Nitrogen Oxide Reductase in Paracoccus denitrificans▿ †

    OpenAIRE

    Bergaust, Linda; Mao, Yuejian; Bakken, Lars R.; Frostegård, Åsa

    2010-01-01

    Denitrification in soil is a major source of atmospheric N2O. Soil pH appears to exert a strong control on the N2O/N2 product ratio (high ratios at low pH), but the reasons for this are not well understood. To explore the possible mechanisms involved, we conducted an in-depth investigation of the regulation of denitrification in the model organism Paracoccus denitrificans during transition to anoxia both at pH 7 and when challenged with pHs ranging from 6 to 7.5. The kinetics of gas transform...

  5. The kinetics of denitrification in permeable sediments

    DEFF Research Database (Denmark)

    Evrard, Victor; Glud, Ronnie N.; Cook, Perran L. M.

    2013-01-01

    to study experimentally. The realistic implementation of such models requires reliable experimentally derived data on the kinetics of denitrification. Here we undertook measurements of denitrification kinetics as a function of nitrate concentration in carefully controlled flow through reactor experiments...... on sediments taken from six shallow coastal sites in Port Phillip Bay, Victoria, Australia. The results showed that denitrification commenced rapidly (within 30 min) after the onset of anoxia and the kinetics could be well described by Michaelis-Menten kinetics with half saturation constants (apparent K...

  6. What happens to plant mitochondria under low oxygen? An omics review of the responses to low oxygen and reoxygenation.

    Science.gov (United States)

    Shingaki-Wells, Rachel; Millar, A Harvey; Whelan, James; Narsai, Reena

    2014-10-01

    Floods can rapidly submerge plants, limiting oxygen to the extent that oxidative phosphorylation no longer generates adequate ATP supplies. Low-oxygen tolerant plants, such as rice, are able to adequately respond to low oxygen by successfully remodelling primary and mitochondrial metabolism to partially counteract the energy crisis that ensues. In this review, we discuss how plants respond to low-oxygen stress at the transcriptomic, proteomic, metabolomic and enzyme activity levels, particularly focusing on mitochondria and interacting pathways. The role of reactive oxygen species and nitrite as an alternative electron acceptor as well as their links to respiratory chain components is discussed. By making intra-kingdom as well as cross-kingdom comparisons, conserved mechanisms of anoxia tolerance are highlighted as well as tolerance mechanisms that are specific to anoxia-tolerant rice during germination and in coleoptiles. We discuss reoxygenation as an often overlooked, yet essential stage of this environmental stress and consider the possibility that changes occurring during low oxygen may also provide benefits upon re-aeration. Finally, we consider what it takes to be low-oxygen tolerant and argue that alternative mechanisms of ATP production, glucose signalling, starch/sucrose signalling as well as reverse metabolism of fermentation end products promote the survival of rice after this debilitating stress.

  7. The biological consequences of flood basalt volcanism

    Science.gov (United States)

    Clapham, M.

    2012-12-01

    Flood basalt eruptions are among the largest environmental perturbations of the Phanerozoic. The rapid release of CO2 from a large igneous province would have triggered a chain of events that can include climate warming, ocean acidification, reduced seawater carbonate saturation, and expanded oceanic anoxia. Those stressors have widely negative impacts on marine organisms, especially on calcified taxa, by affecting their respiratory physiology and reducing energy available for growth and reproduction. Many Phanerozoic extinctions, most notably the end-Permian and end-Triassic mass extinctions, coincided with flood basalt eruptions and shared distinctive patterns of taxonomic and ecological selectivity. In these extinctions, highly active organisms were more likely to survive because they possess physiological adaptations for maintaining internal pH during activity, which also proves useful when buffering pH against ocean acidification. In contrast, species that did not move and had low metabolic rates, such as brachiopods and sponges, suffered considerable losses during these extinctions. Heavily-calcified organisms, especially corals, were particularly vulnerable; as a result, ocean acidification and saturation state changes from flood basalt eruptions often triggered crises in reef ecosystems. This characteristic pattern of selectivity during "physiological" extinctions that closely coincided with flood basalts provides a template for assessing the causes of other extinction events. Because these crises also provide deep time analogues for the ongoing anthropogenic crisis of warming, ocean acidification, and expanded anoxia, the selectivity patterns can also help constrain "winners" and "losers" over upcoming decades.

  8. 中长跑预缺氧与预缺氧适应性训练综述%A Summary of Hypoxic Preconditioning and Adaptable Training in Middle-distance Race

    Institute of Scientific and Technical Information of China (English)

    李开文

    2012-01-01

    文章主要采用文献综述法,综述中长跑男性运动员在不同海拔环境下进行缺氧或低氧训练,机体以逐渐适应的方式来提高对低氧的适应和耐受能力,通过不断的适应,机体能够对长时间缺氧或者严重缺氧性损伤产生强大的抵御和保护效应,进而提高中长跑的高原训练效果.%The paper summarizes that anoxia or hypoxia training in different elevation and environment for the middle-distance male runners by literature review. The organisms are able to produce strong defensive and protective effect to the injury of long time anoxia and severe depletion of oxygen through the way of gradual adaptability and tolerance ability to hypoxia in the training and plateau training effect can be improved.

  9. Simulating Late Ordovician deep ocean O2 with an earth system climate model. Preliminary results.

    Science.gov (United States)

    D'Amico, Daniel F.; Montenegro, Alvaro

    2016-04-01

    The geological record provides several lines of evidence that point to the occurrence of widespread and long lasting deep ocean anoxia during the Late Ordovician, between about 460-440 million years ago (ma). While a series of potential causes have been proposed, there is still large uncertainty regarding how the low oxygen levels came about. Here we use the University of Victoria Earth System Climate Model (UVic ESCM) with Late Ordovician paleogeography to verify the impacts of paleogeography, bottom topography, nutrient loading and cycling and atmospheric concentrations of O2 and CO2 on deep ocean oxygen concentration during the period of interest. Preliminary results so far are based on 10 simulations (some still ongoing) covering the following parameter space: CO2 concentrations of 2240 to 3780 ppmv (~8x to 13x pre-industrial), atmospheric O2 ranging from 8% to 12% per volume, oceanic PO4 and NO3 loading from present day to double present day, reductions in wind speed of 50% and 30% (winds are provided as a boundary condition in the UVic ESCM). For most simulations the deep ocean remains well ventilated. While simulations with higher CO2, lower atmospheric O2 and greater nutrient loading generate lower oxygen concentration in the deep ocean, bottom anoxia - here defined as concentrations concentrations.

  10. Phenotypic Diversity of Hydrogen Production in Chlorophycean Algae Reflects Distinct Anaerobic Metabolisms

    Energy Technology Data Exchange (ETDEWEB)

    Meuser, J. E.; Ananyev, G.; Wittig, L. E.; Kosourov, S.; Ghirardi, M. L.; Seibert, M.; Dismukes, G. C.; Posewitz, M. C.

    2009-01-01

    Several species of green algae use [FeFe]-hydrogenases to oxidize and/or produce H{sub 2} during anoxia. To further define unique aspects of algal hydrogenase activity, the well-studied anaerobic metabolisms of Chlamydomonas reinhardtii were compared with four strains of Chlamydomonas moewusii and a Lobochlamys culleus strain. In vivo and in vitro hydrogenase activity, starch accumulation/degradation, and anaerobic end product secretion were analyzed. The C. moewusii strains showed the most rapid induction of hydrogenase activity, congruent with high rates of starch catabolism, and anoxic metabolite accumulation. Intriguingly, we observed significant differences in morphology and hydrogenase activity in the C. moewusii strains examined, likely the result of long-term adaptation and/or genetic drift during culture maintenance. Of the C. moewusii strains examined, SAG 24.91 showed the highest in vitro hydrogenase activity. However, SAG 24.91 produced little H{sub 2} under conditions of sulfur limitation, which is likely a consequence of its inability to utilize exogenous acetate. In L. culleus, hydrogenase activity was minimal unless pulsed light was used to induce significant H2 photoproduction. Overall, our results demonstrate that unique anaerobic acclimation strategies have evolved in distinct green algae, resulting in differential levels of hydrogenase activity and species-specific patterns of NADH reoxidation during anoxia.

  11. DNA damage in the gill cells of the marine scallop Mizuhopecten yessoensis during anoxic stress and aerobic recovery

    Science.gov (United States)

    Slobodskova, Valentina V.; Zhukovskaya, Avianna F.; Chelomin, Victor P.

    2012-06-01

    Anoxia-induced DNA damage in the gill cells of the marine scallop Mizuhopecten yessoensis was assessed with the alkaline comet assay (single-cell gel electrophoresis). The alkaline comet assay method for detecting DNA strand breaks and alkali labile sites in individual cells. DNA damage was determened in the scallops ( M. yessoensis) gill cells. The scallops were exposed to air for 8 h showing a clear increase in the levels of DNA damage. After the air exposure, M. yessoensis were re-submersed for a period of 12 h, leading values to return to a pre-aerial exposure level. Control animals were kept immersed during the whole period. The resulting data demonstrate that natural influences, such as oxygen depletion (anoxia) in seawater, can be responsible for the induction of DNA damage. If the scallops were re-immersed in oxic conditions, the anoxically induced breaks were repaired. The main mechanisms influencing the integrity of the DNA structure are discussed in this paper.

  12. Computational modelling of the piglet brain to simulate near-infrared spectroscopy and magnetic resonance spectroscopy data collected during oxygen deprivation.

    Science.gov (United States)

    Moroz, Tracy; Banaji, Murad; Robertson, Nicola J; Cooper, Chris E; Tachtsidis, Ilias

    2012-07-01

    We describe a computational model to simulate measurements from near-infrared spectroscopy (NIRS) and magnetic resonance spectroscopy (MRS) in the piglet brain. Piglets are often subjected to anoxic, hypoxic and ischaemic insults, as experimental models for human neonates. The model aims to help interpret measurements and increase understanding of physiological processes occurring during such insults. It is an extension of a previous model of circulation and mitochondrial metabolism. This was developed to predict NIRS measurements in the brains of healthy adults i.e. concentration changes of oxyhaemoglobin and deoxyhaemoglobin and redox state changes of cytochrome c oxidase (CCO). We altered and enhanced the model to apply to the anaesthetized piglet brain. It now includes metabolites measured by (31)P-MRS, namely phosphocreatine, inorganic phosphate and adenosine triphosphate (ATP). It also includes simple descriptions of glycolysis, lactate dynamics and the tricarboxylic acid (TCA) cycle. The model is described, and its simulations compared with existing measurements from piglets during anoxia. The NIRS and MRS measurements are predicted well, although this requires a reduction in blood pressure autoregulation. Predictions of the cerebral metabolic rate of oxygen consumption (CMRO(2)) and lactate concentration, which were not measured, are given. Finally, the model is used to investigate hypotheses regarding changes in CCO redox state during anoxia.

  13. The pore region of the Kv1.2alpha subunit is an important component of recombinant Kv1.2 channel oxygen sensitivity.

    Science.gov (United States)

    Conforti, Laura; Takimoto, Koichi; Petrovic, Milan; Pongs, Olaf; Millhorn, David

    2003-06-27

    Oxygen-sensitive K(+) channels are important elements in the cellular response to hypoxia. Although much progress has been made in identifying their molecular composition, the structural components associated to their O(2)-sensitivity are not yet understood. Recombinant Kv1.2 currents expressed in Xenopus oocytes are inhibited by a decrease in O(2) availability. On the contrary, heterologous Kv2.1 channels are O(2)-insensitive. To elucidate the protein segment responsible for the O(2)-sensitivity of Kv1.2 channels, we analyzed the response to anoxia of Kv1.2/Kv2.1 chimeric channels. Expression of chimeric Kv2.1 channels each containing the S4, the S1-S3 or the S6-COOH segments of Kv1.2 polypeptide resulted in a K(+) current insensitive to anoxia. In contrast, transferring the S5-S6 segment of Kv1.2 into Kv2.1 produced an O(2)-sensitive K(+) current. Finally, mutating a redox-sensitive methionine residue (M380) of Kv1.2 polypeptide did not affect O(2)-sensitivity. Thus, the pore and its surrounding regions of Kv1.2 polypeptide confer its hypoxic inhibition. This response is independent on the redox modulation of methionine residues in this protein segment. PMID:12804584

  14. Nitric oxide availability in deeply hypoxic crucian carp

    DEFF Research Database (Denmark)

    Hansen, Marie Niemann; Gerber, Lucie; Jensen, Frank Bo

    2016-01-01

    Recent research suggest that anoxia-tolerant fish transfer extracellular nitrite into the tissues, where it is used for nitric oxide (NO) generation, iron-nitrosylation and S-nitrosation of proteins as part of the cytoprotective response towards prolonged oxygen lack and subsequent re-oxygenation......Recent research suggest that anoxia-tolerant fish transfer extracellular nitrite into the tissues, where it is used for nitric oxide (NO) generation, iron-nitrosylation and S-nitrosation of proteins as part of the cytoprotective response towards prolonged oxygen lack and subsequent re......(yl)ated compounds either increased or stayed constant, depending on O2 level and tissue type. Nitrite was notably increased in the heart during deep hypoxia, and the increase was amplified by elevated ambient [nitrite]. Raised nitrite also increased gill [nitrite] and decreased mRNA expression of an inducible...... nitric oxide synthase-2 gene variant. The data support that ambient nitrite is taken up across the gills to be distributed via the blood to tissues, particularly the heart, where it assists in cytoprotection and other functions. Cardiac nitrite was not elevated in acutely exposed fish, revealing...

  15. Birth and death of the Late Cretaceous ``La Luna Sea'', and origin of the Tres Esquinas phosphorites

    Science.gov (United States)

    Erlich, R. N.; Macsotay I., O.; Nederbragt, A. J.; Lorente, M. Antonieta

    2000-05-01

    Deposition of organic carbon-rich intervals of the La Luna and Navay formations of northwestern Venezuela was governed by the development of key paleobathymetric barriers (Santa Marta and Santander massifs, Paraguana Block, and ancestral Mérida Andes). These enhanced the development of anoxia in the "La Luna Sea" by causing poor circulation and limited ventilation. Anoxia was also promoted by high evaporation and low precipitation rates (high salinity bottom water), and high levels of marine algal productivity (high organic matter flux). Nutrient supply was augmented by infrequent fluvial sources. Bottom water oxygen levels increased from the Late Santonian through the end of the Cretaceous. Ventilation of anoxic bottom waters may have been enhanced by more frequent or intense seasonal upwelling (caused by higher wind stress) and catastrophic overturn, as well as the removal of a key paleobathymetric barrier. Common byproducts of overturn events were massive phytoplankton blooms, which produced red tides. Fish and marine reptile bone beds within the Tres Esquinas Member (La Luna Formation) are attributed to massive mortality during these events, and are correlative with similar Campanian units in eastern Colombia. During the Maastrichtian, increasing ventilation, combined with siliciclastic dilution, ultimately produced sediments with lower total organic carbon (TOC) content.

  16. The Siberian Traps and the End-Permian mass extinction: a critical review

    Institute of Scientific and Technical Information of China (English)

    Andy SAUNDERS; Marc REICHOW

    2009-01-01

    The association between the Siberian Traps,the largest continental flood basalt province,and thelargest-known mass extinction event at the end of the Permian period,has been strengthened by re-cently-published high-precision 40Ar/39Ar dates from widespread localities across the Siberian prov-ince[i].We argue that the impact of the volcanism was amplified by the prevailing late Permian envi-ronmental conditions-in particular,the hothouse climate,with sluggish oceanic circulation,that wasleading to widespread oceanic anoxia.Volcanism released large masses of sulphate aerosols andcarbon dioxide,the former triggering short-duration volcanic winters,the latter leading to long-termwarming.Whilst the mass of CO2 released from individual eruptions was small compared with the totalmass of carbon in the atmosphere-ocean system,the long 'mean lifetime' of atmospheric C02,com-pared with the eruption flux and duration,meant that significant accumulation could occur over periodsof 10s years.Compromise of the carbon sequestration systems (by curtailment of photosynthesis,de-struction of biomass,and warming and acidification of the oceans) probably led to rapid atmosphericCO2 build-up,warming,and shallow-water anoxia,leading ultimately to mass extinction.

  17. Analysis of gene expression and proteomic profiles of clonal genotypes from Theobroma cacao subjected to soil flooding.

    Directory of Open Access Journals (Sweden)

    Fabiana Z Bertolde

    Full Text Available Soil flooding causes changes in gene transcription, synthesis and degradation of proteins and cell metabolism. The main objective of this study was to understand the biological events of Theobroma cacao during soil flooding-induced stress, using the analyses of gene expression and activity of key enzymes involved in fermentation, as well as the identification of differentially expressed proteins by mass spectrometry in two contrasting genotypes for flooding tolerance (tolerant - TSA-792 and susceptible - TSH-774. Soil anoxia caused by flooding has led to changes in the expression pattern of genes associated with the biosynthesis of alcohol dehydrogenase (ADH, pyruvate decarboxylase (PDC and lactate dehydrogenase (LDH in leaves and roots of the two evaluated genotypes. Significant differences were observed between the enzyme activities of the two genotypes. Leaves and roots of the TSA-792 genotype showed higher ADH activity as compared to the TSH-774 genotype, whereas the activities of PDC and LDH have varied over the 96 h of soil flooding, being higher for TSA-792 genotype, at the initial stage, and TSH-774 genotype, at the final stage. Some of the identified proteins are those typical of the anaerobic metabolism-involved in glycolysis and alcoholic fermentation-and different proteins associated with photosynthesis, protein metabolism and oxidative stress. The ability to maintain glycolysis and induce fermentation was observed to play an important role in anoxia tolerance in cacao and may also serve to distinguish tolerant and susceptible genotypes in relation to this stressor.

  18. Modeling evidences for global warming, Arctic seawater freshening, and sluggish oceanic circulation during the Early Toarcian anoxic event

    Science.gov (United States)

    Dera, Guillaume; Donnadieu, Yannick

    2012-06-01

    The paleoecological disturbances recorded during the Early Toarcian warming event (183 Myr ago), including marine anoxia, sea level rise, seawater acidification, carbonate production crisis, and species extinctions, are often regarded as past examples of Earth's possible responses to the rapid emergence of super greenhouse conditions. However, physical mechanisms explaining both the global and local expressions of paleoenvironmental events are still highly debated. Here we analyze the paleoclimatic and paleoceanographic consequences of increases in atmospheric pCO2 levels at a multiscale resolution using a fully coupled ocean-atmosphere model (FOAM). We show that, in association with stronger high-latitude precipitation rates and enhanced continental runoff, the demise of polar sea ice due to the global warming event involved a regional freshening of Arctic surface seawaters. These disturbances lead to progressive slowdowns of the global oceanic circulation accountable for widespread ocean stratification and bottom anoxia processes in deep oceanic settings and epicontinental basins. In agreement with very negative oxygen isotope values measured on fossil shells from the NW Tethys, our simulations also show that recurrent discharges of brackish and nutrient-rich Arctic surface waters through the Viking Corridor could have led to both vertical and geographical gradients in salinity and seawater δ18O in the NW Tethyan seas. Locally contrasted conditions in water mass density and rises in productivity rates due to strong nutrient supplies could partly explain the regional severity of the anoxic event in the restricted Euro-boreal domains, as it has been previously suggested and modeled regionally.

  19. Dynamic anoxic ferruginous conditions during the end-Permian mass extinction and recovery

    Science.gov (United States)

    Clarkson, M. O.; Wood, R. A.; Poulton, S. W.; Richoz, S.; Newton, R. J.; Kasemann, S. A.; Bowyer, F.; Krystyn, L.

    2016-07-01

    The end-Permian mass extinction, ~252 million years ago, is notable for a complex recovery period of ~5 Myr. Widespread euxinic (anoxic and sulfidic) oceanic conditions have been proposed as both extinction mechanism and explanation for the protracted recovery period, yet the vertical distribution of anoxia in the water column and its temporal dynamics through this time period are poorly constrained. Here we utilize Fe-S-C systematics integrated with palaeontological observations to reconstruct a complete ocean redox history for the Late Permian to Early Triassic, using multiple sections across a shelf-to-basin transect on the Arabian Margin (Neo-Tethyan Ocean). In contrast to elsewhere, we show that anoxic non-sulfidic (ferruginous), rather than euxinic, conditions were prevalent in the Neo-Tethys. The Arabian Margin record demonstrates the repeated expansion of ferruginous conditions with the distal slope being the focus of anoxia at these times, as well as short-lived episodes of oxia that supported diverse biota.

  20. A rapid procedure for the determination of thorium, uranium, cadmium and molybdenum in small sediment samples by inductively coupled plasma-mass spectrometry: Application in Chesapeake Bay

    Science.gov (United States)

    Zheng, Yen; Weinman, B.; Cronin, T.; Fleisher, M.Q.; Anderson, Robert F.

    2003-01-01

    This paper describes a rapid procedure that allows precise analysis of Mo, Cd, U and Th in sediment samples as small as 10 mg by using a novel approach that utilizes a "pseudo" isotope dilution for Th and conventional isotope dilution for Mo, Cd and U by ICP-MS. Long-term reproducibility of the method is between 2.5 and 5% with an advantage of rapid analysis on a single digestion of sediment sample and the potential of adding other elements of interest if so desired. Application of this method to two piston cores collected near the mouth of the Patuxent River in Chesapeake Bay showed that the accumulation of authigenic Mo and Cd varied in response to the changing bottom water redox conditions, with anoxia showing consistent oscillations throughout both pre-industrial and industrial times. Accumulation of authigenic U shows consistent oscillations as well, without any apparent increase in productivity related to anoxic trends. Degrees of Mo and Cd enrichment also inversely correlate to halophilic microfaunal assemblages already established as paleoclimate proxies within the bay indicating that bottom water anoxia is driven in part by the amount of freshwater discharge that the area receives. ?? 2002 Elsevier Science Ltd. All rights reserved.

  1. Acetate versus sulfur deprivation role in creating anaerobiosis in light for hydrogen production by Chlamydomonas reinhardtii and Spirulina platensis: two different organisms and two different mechanisms.

    Science.gov (United States)

    Morsy, Fatthy Mohamed

    2011-01-01

    This work was devoted to separate acetate role in creating anaerobiosis from that of sulfur deprivation. Chlamydomonas reinhardtii grown in TAP (Tris-acetate-phosphate) medium was resuspended in sulfur-replete or -deprived medium in sealed or nonsealed cultures. Sulfur deprivation was substantial for starch accumulation and hydrogen evolution; however, acetate induced anaerobiosis in the presence or absence of sulfur in only sealed cultures. In nonsealed cultures, Chlamydomonas did not lose its photosynthetic activity; however, it was arrested in anoxia with no photosynthetic activity as long as the culture was sealed. The sealed cultures resumed photosynthesis upon unsealing overnight unless the cells died by anoxia at late stage of the experiment. These results indicate that the enhanced oxygen consumption for the enormous acetate respiration and inhibition of the external oxygen supply in sealed cultures of Chlamydomonas are the main reasons for the steady anaerobic conditions. Although acetate was substantial for creating anaerobiosis in Chlamydomonas, sulfur deprivation alone could create anaerobiosis in Spirulina platensis grown autotrophically. Hydrogen evolution and glycogen accumulation were induced under such conditions. Severely reduced phycocyanin, chlorophyll and photosynthesis, while respiration had increased, induced anaerobiosis in Spirulina. This study reports for the first time anaerobiosis under autotrophic conditions in a cyanobacterium.

  2. Methane seeps, methane hydrate destabilization, and the late Neoproterozoic postglacial cap carbonates

    Institute of Scientific and Technical Information of China (English)

    JIANG Ganqing; SHI Xiaoying; ZHANG Shihong

    2006-01-01

    Methane hydrates constitute the largest pool of readily exchangeable carbon at the Earth's sedimentary carapace and may destabilize, in some cases catastrophically, during times of global-scale warming and/or sea level changes. Given the extreme cold during Neoproterozoic ice ages, the aftermath of such events is perhaps amongst the most likely intervals in Earth history to witness a methane hydrate destabilization event. The coincidence of localized but widespread methane seep-like structures and textures, methane-derived isotopic signal,low sulfate concentration, marine barites, and a prominent, short-lived carbon isotope excursion (δ13C≤-5‰) from the post-Marinoan cap carbonates (~635 Ma) provides strong evidence for a methane hydrate destabilization event during the late Neoproterozoic postglacial warming and transgression. Methane release from hydrates could cause a positive feedback to global warming and oxidation of methane could result in ocean anoxia and fluctuation of atmospheric oxygen, providing an environmental force for the early animal evolution in the latest Neoproterozoic. The issues that remain to be clarified for this event include the trigger of methane hydrate destabilization, the time of initial methane release, the predicted ocean anoxia event and its relationship with the biological innovation, additional geochemical signals in response to methane release, and the regional and global synchrony of cap carbonate precipitation. The Doushantuo cap carbonate in South China provides one of the best examples of its age for a better understanding of these issues.

  3. Magnetic quantification of Fe and S bound as magnetosomal greigite in laminated sapropels in deeper basins of the Baltic Sea

    Science.gov (United States)

    Reinholdsson, M.; Snowball, I.

    2014-01-01

    Magnetotactic bacteria (MTB) biomineralize magnetite and/or greigite for navigation purposes and it have been suggested that their magnetosomes make a significant contribution to the burial of Fe (and S and O) in sedimentary environments. To test this hypothesis and improve our understanding of MTBs impact on the rate of burial of these two elements we have quantified the abundance of Fe and S bound as greigite magnetofossils in laminated Baltic Sea sapropels, which were formed during periods of hypoxia and anoxia, using mineral magnetic measurements. Fluxes of Fe and S in the form of preserved greigite magnetofossils were calculated for three sedimentary sequences. The magnetosomal Fe (and S) fluxes range between 0.19 and 1.46 × 10-6 g cm-2 yr-1 (0.15 and 1.12 × 10-6 g cm-2 yr-1), and varied in time and space. The contribution of magnetosomal Fe to total Fe fluxes is relatively low, < 0.2%, although its contribution can be important in other stratified waters that suffer from hypoxia/anoxia. We show that the magnetosomal fluxes of Fe in the Baltic Sea are, however, similar to fluxes of Fe derived from mineral magnetic studies of magnetite magnetosomes in organic rich, varved freshwater lake sediments in Sweden.

  4. Magnetic quantification of Fe and S bound as magnetosomal greigite in laminated sapropels in deeper basins of the Baltic Sea

    Directory of Open Access Journals (Sweden)

    M. Reinholdsson

    2014-01-01

    Full Text Available Magnetotactic bacteria (MTB biomineralize magnetite and/or greigite for navigation purposes and it have been suggested that their magnetosomes make a significant contribution to the burial of Fe (and S and O in sedimentary environments. To test this hypothesis and improve our understanding of MTBs impact on the rate of burial of these two elements we have quantified the abundance of Fe and S bound as greigite magnetofossils in laminated Baltic Sea sapropels, which were formed during periods of hypoxia and anoxia, using mineral magnetic measurements. Fluxes of Fe and S in the form of preserved greigite magnetofossils were calculated for three sedimentary sequences. The magnetosomal Fe (and S fluxes range between 0.19 and 1.46 × 10−6 g cm−2 yr−1 (0.15 and 1.12 × 10−6 g cm−2 yr−1, and varied in time and space. The contribution of magnetosomal Fe to total Fe fluxes is relatively low, < 0.2%, although its contribution can be important in other stratified waters that suffer from hypoxia/anoxia. We show that the magnetosomal fluxes of Fe in the Baltic Sea are, however, similar to fluxes of Fe derived from mineral magnetic studies of magnetite magnetosomes in organic rich, varved freshwater lake sediments in Sweden.

  5. Investigations of aroma volatile biosynthesis under anoxic conditions and in different tissues of "Redchief Delicious" apple fruit (Malus domestica Borkh.).

    Science.gov (United States)

    Rudell, D R; Mattinson, D S; Mattheis, J P; Wyllie, S G; Fellman, J K

    2002-04-24

    Disks from different tissues were obtained from "Redchief Delicious" apple fruit (Malus domestica Borkh.) and analyzed for the ability to metabolize 1-pentanol as well as synthesize constitutive esters and alcohols under anoxic and aerobic conditions. The skin tissue displayed a greater capacity to synthesize pentanal, pentyl acetate, pentyl propionate, pentyl butyrate, and pentyl hexanoate than the hypanthial and carpellary tissues during incubation with 1-pentanol. With the exception of pentyl acetate and pentyl propionate biosynthesis, the hypanthial tissue synthesized these compounds at a higher rate than the carpellary tissue. Anoxia inhibited both constituent and 1-pentanol-derived ester biosynthesis. While anoxia inhibited ester biosynthesis, ethanol biosynthesis increased at a greater rate in tissue disks held under these conditions. Biosynthesis of 1-butanol, 2-methyl-1-butanol, and 1-hexanol was greater in tissue disks held in air during the first part of the measurement period and dropped off more rapidly than those transpiring in tissue disks held under anoxic conditions. The biosynthetic rates of all esters, both constituent and 1-pentanol-derived, increased as a result of air exposure. While hypoxic or anoxic conditions may promote ethanol synthesis, these conditions also appear to inhibit the formation of the ethanol-derived esters partially responsible for the off-flavor in apples attributed to ultralow O(2) controlled atmosphere storage. PMID:11958633

  6. Characterization of the phosphofructokinase gene family in rice and its expression under oxygen deficiency stress

    Directory of Open Access Journals (Sweden)

    Angelika eMustroph

    2013-05-01

    Full Text Available Plants possess two types of phosphofructokinase proteins for phosphorylation of fructose-6-phosphate, the ATP-dependent phosphofructokinase (PFK and the pyrophosphate-(PPi dependent pyrophosphate-fructose-6-phosphate-phosphotransferase (PFP. During oxygen deficiency ATP levels in rice seedlings are severely reduced, and it is hypothesized that PPi is used as an alternative energy source for the phosphorylation of fructose-6-phosphate during glycolysis. In this study, we analyzed the expression of 15 phosphofructokinase-encoding genes in roots and aerial tissues of anoxia-tolerant rice seedlings in response to anoxic stress and compared our data with transcript profiles obtained from microarray analyses. Furthermore, the intracellular localization of rice PFK proteins was determined, and the PFK and PFP isoforms were grouped in a phylogenetic tree. Two PFK and two PFP transcripts accumulated during anoxic stress, whereas mRNA levels of four PFK and three PFP genes were decreased. The total specific activity of both PFK and PFP changed only slightly during a 24 h anoxia treatment. It is assumed that expression of different isoforms and their catalytic properties differ during normoxic and anoxic conditions and contribute to balanced glycolytic activity during the low oxygen stress. These characterizations of phosphofructokinase genes and the comparison to other plant species allowed us to suggest candidate rice genes for adaptation to anoxic stress.

  7. Running hotter, faster, shallower: acceleration of the marine nitrogen cycle from the Last Glacial Maximum to the pre-industrial, and implications for the future

    Science.gov (United States)

    Galbraith, E. D.

    2015-12-01

    Biologically-available nitrogen is the primary limiting nutrient in the global ocean. The complex physical-biological interdependencies of nitrogen fixation and denitrification, the source and sink of bioavailable nitrogen, have led to uncertainty over their future trajectories under higher CO2. Sedimentary nitrogen isotope evidence suggests that the global rate of denitrification was on the order of 50% lower during the last glacial maximum, and reveals that significant changes in denitrification have occurred on a decadal-centennial timescale. Coupled atmosphere-ocean-biogeochemistry models simulate similar changes, through physically-driven changes in anoxia, which then feed back on nitrogen fixation through the availability of phosphorus to diazotrophs. In addition, diazotroph culture experiments suggest that nitrogen fixation was further limited during glacial maxima by low CO2, causing an additional slowdown of the nitrogen cycle. The emergent picture suggests that deglaciation accelerated both sides of the N cycle, with more rapid loss encouraged by expanded shallow anoxia, and more rapid gain encouraged by higher CO2. It will be argued that the net effect on the nitrogen inventory can be approximated by knowing the distribution of surface ocean PO4, given the observed correlation of surface PO4 concentrations on the P:C ratio of exported organic matter.

  8. A rapid procedure for the determination of thorium, uranium, cadmium and molybdenum in small sediment samples by inductively coupled plasma-mass spectrometry: application in Chesapeake Bay

    International Nuclear Information System (INIS)

    This paper describes a rapid procedure that allows precise analysis of Mo, Cd, U and Th in sediment samples as small as 10 mg by using a novel approach that utilizes a 'pseudo' isotope dilution for Th and conventional isotope dilution for Mo, Cd and U by ICP-MS. Long-term reproducibility of the method is between 2.5 and 5% with an advantage of rapid analysis on a single digestion of sediment sample and the potential of adding other elements of interest if so desired. Application of this method to two piston cores collected near the mouth of the Patuxent River in Chesapeake Bay showed that the accumulation of authigenic Mo and Cd varied in response to the changing bottom water redox conditions, with anoxia showing consistent oscillations throughout both pre-industrial and industrial times. Accumulation of authigenic U shows consistent oscillations as well, without any apparent increase in productivity related to anoxic trends. Degrees of Mo and Cd enrichment also inversely correlate to halophilic microfaunal assemblages already established as paleoclimate proxies within the bay indicating that bottom water anoxia is driven in part by the amount of freshwater discharge that the area receives

  9. Short-term variations of methane concentrations and methanotrophic activity in a coastal inlet (Eckernförde Bay, Germany)

    Science.gov (United States)

    Niemann, Helge; Richner, Dominik; Steinle, Lea; Schneider von Deimling, Jens; Urban, Peter; Hoffmann, Jasper; Schmidt, Mark; Treude, Tina; Lehmann, Moritz F.

    2015-04-01

    Large quantities of the greenhouse gas methane are produced in anoxic sediments of continental margins and may be liberated into the overlying water column and, potentially, into the atmosphere where it further contributes to global warming. However, a sequence of microbially mediated methane oxidation pathways in sediments and the water column mitigate the contribution of oceans to the atmospheric methane budget. In anoxic sediments, specialised archaea oxidise methane with sulphate in a process that has been termed the anaerobic oxidation of methane (AOM). In addition, aerobic bacteria at the sediment surface and the water column have the potential to consume methane (aerobic oxidation of methane; MOx) that has by passed the benthic, microbial filter. However methane cycling in (aerobic) marine waters is not well constrained. Particularly little is known about spatiotemporal aspects of MOx activity and the underlying key physical, chemical and biological factors. Here we show results from our investigations on methane dynamics on very short time scales of hours to days in the Eckernförde Bay (E-Bay), a costal inlet of the Baltic Sea in northern Germany featuring seasonal bottom water hypoxia/anoxia. In autumn 2014, we observed high spatiotemporal variations in water column methane contents and MOx activity: Anoxic bottom waters in a trough in the northern part of the bay contained extremely high methane concentrations of up to 800 nM, which sharply declined at the midwater redox interface (though methane remained supersaturated with respect to the atmospheric equilibrium throughout the water column at all times). The methane decrease at the redox interface was related to highly active MOx communities consuming methane under microoxic conditions at rates of up 40 nM/d. About 12 hours later, the methane content and the extent of bottom water anoxia was much lower and MOx activity was highly reduced in the northern part but strongly elevated in the southern part of

  10. A biomarker record of Lake El'gygytgyn, Far East Russian Arctic: investigating sources of organic matter and carbon cycling during marine isotope stages 1–3

    Directory of Open Access Journals (Sweden)

    A. R. Holland

    2013-01-01

    Full Text Available Arctic paleoenvironmental archives serve as sensitive recorders of past climate change. Lake El'gygytgyn (Far East Russian Arctic is a high-latitude crater impact lake that contains a continuous sediment record influenced by neither glaciation nor glacial erosion since the time of impact 3.58 Ma ago. Prior research on sediments collected from Lake El'gygytgyn suggest times of permanent ice cover and anoxia corresponding to global glacial intervals, during which the sediments are laminated and are characterized by the co-occurrence of high total organic carbon, microscopic magnetite grains that show etching and dissolution, and negative excursions in bulk sediment organic matter carbon isotope (δ13C values. Here we investigate the abundance and carbon isotopic composition of lipid biomarkers recovered from Lake El'gygytgyn sediments spanning marine isotope stages 1–3 to identify key sources of organic matter (OM to lake sediments, to establish which OM sources drive the negative δ13C excursion exhibited by bulk sediment OM, and to explore if there are molecular and isotopic signatures of anoxia in the lake during glaciation. We find that during marine isotope stages 1–3, direct evidence for water column anoxia is lacking. A ~4‰ negative excursion in bulk sediment δ13C values during the Local Last Glacial Maximum (LLGM is accompanied by more protracted, higher magnitude negative excursions in n-alkanoic acid and n-alkanol δ13C values that begin 20 kyr in advance of the LLGM. In contrast, n-alkanes and the C30 n-alkanoic acid do not exhibit a negative δ13C excursion at this time. Our results indicate that the C24, C26 and C28 n-alkanoic acids do not derive entirely from terrestrial OM sources, while the C30 n-alkanoic acid at Lake El'gygytgyn is a robust indicator of terrestrial OM contributions. Overall, our results strongly support the presence of a nutrient-poor water column, which is mostly isolated from atmospheric carbon dioxide

  11. Dysoxic/anoxic episodes in the Aptian-Albian (Early Cretaceous)

    Science.gov (United States)

    Bralower, Timothy J.; Sliter, William V.; Arthur, Michael A.; Leckie, R. Mark; Allard, David; Schlanger, Seymour O.

    New biostratigraphic data suggest, for the first time, that the long Aptian-Albian Oceanic Anoxic Event was marked by at least three distinct, relatively brief episodes of widespread dysoxia/anoxia which interrupted generally oxygenated conditions. The high-resolution, integrated foraminiferal and nannofossil biostratigraphy derived here allows recognition of an apparently ocean-wide dysoxic/anoxic episode in the early Aptian (Globigerinelloides blowi foraminiferal Zone, Chiastozygus litterarius nannofossil Zone, Conusphaera rothii nannofossil Subzone, shortly after magnetic Chron CMO). Equally widespread, but distributionally patchier dysoxic/anoxic episodes occurred in the early Albian (Hedbergella planispira foraminiferal Zone, Prediscosphaera columnata nannofossil Zone, subzone NC8B) and early late Albian (Biticinella breggiensis foraminiferal Zone, Axopodorhabdus albianus nannofossil Zone, subzone NC9B). These episodes can be best recognized in highly carbonaceous sediments deposited in epicontinental basins, now exposed on land, including the lower Aptian "Livello Selli" of the Italian Apennines, the lower Albian "Niveau Paquier" of the Fosse Vocontienne, France, and the lower upper Albian Toolebuc Formation of the Eromanga Basin, Queensland, Australia. Our data indicate that these horizons correlate at the nannofossil subzonal level to carbonaceous intervals in DSDP/ODP sites which were deposited in pelagic and hemipelagic oceanic settings. Although none of these episodes is associated with major biotic extinctions, they are characterized by changes, of variable magnitude, in the community structure of planktonic foraminifera, which commonly consist of a low-diversity assemblage of opportunistic taxa or are entirely absent. Nannofossil taxa in these horizons do not change as radically, but in some sites show marked nearshore affinities or, in other sequences, are possibly replaced by other phytoplankton. Dissolution events cannot be entirely ruled out as a

  12. Brain stem death as the vital determinant for resumption of spontaneous circulation after cardiac arrest in rats.

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    Alice Y W Chang

    Full Text Available BACKGROUND: Spontaneous circulation returns to less than half of adult cardiac arrest victims who received in-hospital resuscitation. One clue for this disheartening outcome arises from the prognosis that asystole invariably takes place, after a time lag, on diagnosis of brain stem death. The designation of brain stem death as the point of no return further suggests that permanent impairment of the brain stem cardiovascular regulatory machinery precedes death. It follows that a crucial determinant for successful revival of an arrested heart is that spontaneous circulation must resume before brain stem death commences. Here, we evaluated the hypothesis that maintained functional integrity of the rostral ventrolateral medulla (RVLM, a neural substrate that is intimately related to brain stem death and central circulatory regulation, holds the key to the vital time-window between cardiac arrest and resumption of spontaneous circulation. METHODOLOGY/PRINCIPAL FINDINGS: An animal model of brain stem death employing the pesticide mevinphos as the experimental insult in Sprague-Dawley rats was used. Intravenous administration of lethal doses of mevinphos elicited an abrupt cardiac arrest, accompanied by elevated systemic arterial pressure and anoxia, augmented neuronal excitability and enhanced microvascular perfusion in RVLM. This period represents the vital time-window between cardiac arrest and resumption of spontaneous circulation in our experimental model. Animals with restored spontaneous circulation exhibited maintained neuronal functionality in RVLM beyond this critical time-window, alongside resumption of baseline tissue oxygen and enhancement of local blood flow. Intriguingly, animals that subsequently died manifested sustained anoxia, diminished local blood flow, depressed mitochondrial electron transport activities and reduced ATP production, leading to necrotic cell death in RVLM. That amelioration of mitochondrial dysfunction and

  13. Effects of soil erosion and anoxic-euxinic ocean in the Permian-Triassic marine crisis.

    Science.gov (United States)

    Kaiho, Kunio; Saito, Ryosuke; Ito, Kosuke; Miyaji, Takashi; Biswas, Raman; Tian, Li; Sano, Hiroyoshi; Shi, Zhiqiang; Takahashi, Satoshi; Tong, Jinnan; Liang, Lei; Oba, Masahiro; Nara, Fumiko W; Tsuchiya, Noriyoshi; Chen, Zhong-Qiang

    2016-08-01

    The largest mass extinction of biota in the Earth's history occurred during the Permian-Triassic transition and included two extinctions, one each at the latest Permian (first phase) and earliest Triassic (second phase). High seawater temperature in the surface water accompanied by euxinic deep-intermediate water, intrusion of the euxinic water to the surface water, a decrease in pH, and hypercapnia have been proposed as direct causes of the marine crisis. For the first-phase extinction, we here add a causal mechanism beginning from massive soil and rock erosion and leading to algal blooms, release of toxic components, asphyxiation, and oxygen-depleted nearshore bottom water that created environmental stress for nearshore marine animals. For the second-phase extinction, we show that a soil and rock erosion/algal bloom event did not occur, but culmination of anoxia-euxinia in intermediate waters did occur, spanning the second-phase extinction. We investigated sedimentary organic molecules, and the results indicated a peak of a massive soil erosion proxy followed by peaks of marine productivity proxy. Anoxic proxies of surface sediments and water occurred in the shallow nearshore sea at the eastern and western margins of the Paleotethys at the first-phase extinction horizon, but not at the second-phase extinction horizon. Our reconstruction of ocean redox structure at low latitudes indicates that a gradual increase in temperature spanning the two extinctions could have induced a gradual change from a well-mixed oxic to a stratified euxinic ocean beginning immediately prior to the first-phase extinction, followed by culmination of anoxia in nearshore surface waters and of anoxia and euxinia in the shallow-intermediate waters at the second-phase extinction over a period of approximately one million years or more. Enhanced global warming, ocean acidification, and hypercapnia could have caused the second-phase extinction approximately 60 kyr after the first

  14. Effects of temperature and extracellular pH on metabolites: kinetics of anaerobic metabolism in resting muscle by 31P- and 1H-NMR spectroscopy.

    Science.gov (United States)

    Vezzoli, Alessandra; Gussoni, Maristella; Greco, Fulvia; Zetta, Lucia

    2003-09-01

    Environmental stress, such as low temperature, extracellular acidosis and anoxia, is known to play a key role in metabolic regulation. The aim of the present study was to gain insight into the combined temperature-pH regulation of metabolic rate in frog muscle, i.e. an anoxia-tolerant tissue. The rate of exergonic metabolic processes occurring in resting isolated muscles was determined at 15 degrees C and 25 degrees C as well as at extracellular pH values higher (7.9), similar (7.3) and lower (7.0) than the physiological intracellular pH. (31)P and (1)H nuclear magnetic resonance spectroscopy high-resolution measurements were carried out at 4.7 T in isolated frog (Rana esculenta) gastrocnemius muscle during anoxia to assess, by means of reference compounds, the concentration of all phosphate metabolites and lactate. Intra- and extracellular pH was also determined. In the range of examined temperatures (15-25 degrees C), the temperature dependence of anaerobic glycolysis was found to be higher than that of PCr depletion (Q(10)=2.3). High-energy phosphate metabolism was confirmed to be the initial and preferential energy source. The rate of phosphocreatine hydrolysis did not appear to be affected by extracellular pH changes. By contrast, independent of the intracellular pH value, at the higher temperature (25 degrees C) a lowering of the extracellular pH from 7.9 to 7.0 caused a depression in lactate accumulation. This mechanism was ascribed to the transmembrane proton concentration gradient. This parameter was demonstrated to regulate glycolysis, probably through a reduced lactate efflux, depending on the activity of the lactate-H(+) co-transporter. The calculated intracellular buffer capacity was related to intra- and extracellular pH and temperature. At the experimental extracellular pH of 7.9 and at a temperature of 15 degrees C and 25 degrees C, calculated intracellular buffering capacity was 29.50 micromol g(-1) pH unit(-1) and 69.98 micromol g(-1) pH unit(-1

  15. Global Warmth and Nutrient Trapping Enhance End-Paleozoic Euxinia in an Earth System Model

    Science.gov (United States)

    Meyer, K. M.; Kump, L. R.; Ridgwell, A.

    2007-12-01

    The end-Permian mass extinction occurred during an interval characterized by global warmth and falling atmospheric oxygen levels. Although the cause of the extinction remains unresolved, geochemical evidence suggests that the event coincided with widespread anoxia and possible euxinia (anoxic and sulfidic waters). A combination of warm surface ocean temperatures, low atmospheric oxygen content, and high O2 demand in the deep ocean likely induced anoxia. Anaerobic organic matter remineralization by bacterial sulfate reduction then produced euxinic conditions. Phosphate release from surface sediments and decreased phosphate burial under a sulfidic water column further enhanced oceanic euxinia through positive feedbacks to primary productivity. We hypothesize that late Paleozoic climate and geography favored marine euxinia, a potential kill mechanism for the extinction event. Here we use earth system modelling to explore the physical and biogeochemical conditions necessary for the development of intense euxinia during the end-Permian. We use the end-Permian configuration of GENIE (www.genie.ac.uk), an energy-moisture-balance atmospheric model coupled to a 3-D, non-eddy-resolving, frictional geostrophic model to investigate the transition to marine anoxia and euxinia in a greenhouse world. Equilibrium model simulations over a range of oceanic phosphate concentrations relate oceanic nutrient status to the buildup of euxinia and attendant hydrogen sulfide release to the atmosphere. Addition of a marine nitrogen cycle suggests that microbial denitrification reduces, but does not prevent H2S buildup. Deep-ocean hydrogen sulfide appears with a doubling of phosphate, and localized photic zone euxinia develops with a tripling of phosphate. The greatest surface water H2S concentrations are observed in upwelling zones and in the Paleo-Tethys Ocean, where nutrient trapping results in elevated phosphate concentrations. Significant hydrogen sulfide fluxes to the atmosphere result

  16. Zinc finger nuclease mediated knockout of ADP-dependent glucokinase in cancer cell lines: effects on cell survival and mitochondrial oxidative metabolism.

    Directory of Open Access Journals (Sweden)

    Susan Richter

    Full Text Available Zinc finger nucleases (ZFN are powerful tools for editing genes in cells. Here we use ZFNs to interrogate the biological function of ADPGK, which encodes an ADP-dependent glucokinase (ADPGK, in human tumour cell lines. The hypothesis we tested is that ADPGK utilises ADP to phosphorylate glucose under conditions where ATP becomes limiting, such as hypoxia. We characterised two ZFN knockout clones in each of two lines (H460 and HCT116. All four clones had frameshift mutations in all alleles at the target site in exon 1 of ADPGK, and were ADPGK-null by immunoblotting. ADPGK knockout had little or no effect on cell proliferation, but compromised the ability of H460 cells to survive siRNA silencing of hexokinase-2 under oxic conditions, with clonogenic survival falling from 21±3% for the parental line to 6.4±0.8% (p = 0.002 and 4.3±0.8% (p = 0.001 for the two knockouts. A similar increased sensitivity to clonogenic cell killing was observed under anoxia. No such changes were found when ADPGK was knocked out in HCT116 cells, for which the parental line was less sensitive than H460 to anoxia and to hexokinase-2 silencing. While knockout of ADPGK in HCT116 cells caused few changes in global gene expression, knockout of ADPGK in H460 cells caused notable up-regulation of mRNAs encoding cell adhesion proteins. Surprisingly, we could discern no consistent effect on glycolysis as measured by glucose consumption or lactate formation under anoxia, or extracellular acidification rate (Seahorse XF analyser under oxic conditions in a variety of media. However, oxygen consumption rates were generally lower in the ADPGK knockouts, in some cases markedly so. Collectively, the results demonstrate that ADPGK can contribute to tumour cell survival under conditions of high glycolytic dependence, but the phenotype resulting from knockout of ADPGK is cell line dependent and appears to be unrelated to priming of glycolysis in these lines.

  17. Zinc Finger Nuclease Mediated Knockout of ADP-Dependent Glucokinase in Cancer Cell Lines: Effects on Cell Survival and Mitochondrial Oxidative Metabolism

    Science.gov (United States)

    Richter, Susan; Morrison, Shona; Connor, Tim; Su, Jiechuang; Print, Cristin G.; Ronimus, Ron S.; McGee, Sean L.; Wilson, William R.

    2013-01-01

    Zinc finger nucleases (ZFN) are powerful tools for editing genes in cells. Here we use ZFNs to interrogate the biological function of ADPGK, which encodes an ADP-dependent glucokinase (ADPGK), in human tumour cell lines. The hypothesis we tested is that ADPGK utilises ADP to phosphorylate glucose under conditions where ATP becomes limiting, such as hypoxia. We characterised two ZFN knockout clones in each of two lines (H460 and HCT116). All four clones had frameshift mutations in all alleles at the target site in exon 1 of ADPGK, and were ADPGK-null by immunoblotting. ADPGK knockout had little or no effect on cell proliferation, but compromised the ability of H460 cells to survive siRNA silencing of hexokinase-2 under oxic conditions, with clonogenic survival falling from 21±3% for the parental line to 6.4±0.8% (p = 0.002) and 4.3±0.8% (p = 0.001) for the two knockouts. A similar increased sensitivity to clonogenic cell killing was observed under anoxia. No such changes were found when ADPGK was knocked out in HCT116 cells, for which the parental line was less sensitive than H460 to anoxia and to hexokinase-2 silencing. While knockout of ADPGK in HCT116 cells caused few changes in global gene expression, knockout of ADPGK in H460 cells caused notable up-regulation of mRNAs encoding cell adhesion proteins. Surprisingly, we could discern no consistent effect on glycolysis as measured by glucose consumption or lactate formation under anoxia, or extracellular acidification rate (Seahorse XF analyser) under oxic conditions in a variety of media. However, oxygen consumption rates were generally lower in the ADPGK knockouts, in some cases markedly so. Collectively, the results demonstrate that ADPGK can contribute to tumour cell survival under conditions of high glycolytic dependence, but the phenotype resulting from knockout of ADPGK is cell line dependent and appears to be unrelated to priming of glycolysis in these lines. PMID:23799003

  18. Desflurane preconditioning induces oscillation of NF-κB in human umbilical vein endothelial cells.

    Directory of Open Access Journals (Sweden)

    Juan Yi

    Full Text Available BACKGROUND: Nuclear factor kappa B (NF-κB has been implicated in anesthetic preconditioning (APC induced protection against anoxia and reoxygenation (A/R injury. The authors hypothesized that desflurane preconditioning would induce NF-κB oscillation and prevent endothelial cells apoptosis. METHODS: A human umbilical vein endothelial cells (HUVECs A/R injury model was used. A 30 minute desflurane treatment was initiated before anoxia. NF-κB inhibitor BAY11-7082 was administered in some experiments before desflurane preconditioning. Cells apoptosis was analyzed by flow cytometry using annexin V-fluorescein isothiocyanate staining and cell viability was evaluated by modified tertrozalium salt (MTT assay. The cellular superoxide dismutases (SOD activitiy were tested by water-soluble tetrazolium salt (WST-1 assay. NF-κB p65 subunit nuclear translocation was detected by immunofluorescence staining. Expression of inhibitor of NF-κB-α (IκBα, NF-κB p65 and cellular inhibitor of apoptosis 1 (c-IAP1, B-cell leukemia/lymphoma 2 (Bcl-2, cysteine containing aspartate specific protease 3 (caspases-3 and second mitochondrial-derived activator of caspase (SMAC/DIABLO were determined by western blot. RESULTS: Desflurane preconditioning caused phosphorylation and nuclear translocation of NF-κB before anoxia, on the contrary, induced the synthesis of IκBα and inhibition of NF-κB after reoxygenation. Desflurane preconditioning up-regulated the expression of c-IAP1 and Bcl-2, blocked the cleavage of caspase-3 and reduced SMAC release, and decreased the cell death of HUVECs after A/R. The protective effect was abolished by BAY11-7082 administered before desflurane. CONCLUSIONS: The results demonstrated that desflurane activated NF-κB during the preconditioning period and inhibited excessive activation of NF-κB in reperfusion. And the oscillation of NF-κB induced by desflurane preconditioning finally up-regulated antiapoptotic proteins expression and

  19. Profiling the anaerobic response of C. elegans using GC-MS.

    Directory of Open Access Journals (Sweden)

    Jeffrey A Butler

    Full Text Available The nematode Caenorhabditis elegans is a model organism that has seen extensive use over the last four decades in multiple areas of investigation. In this study we explore the response of the nematode Caenorhabditis elegans to acute anoxia using gas-chromatography mass-spectrometry (GC-MS. We focus on the readily-accessible worm exometabolome to show that C. elegans are mixed acid fermenters that utilize several metabolic pathways in unconventional ways to remove reducing equivalents - including partial reversal of branched-chain amino acid catabolism and a potentially novel use of the glyoxylate pathway. In doing so, we provide detailed methods for the collection and analysis of excreted metabolites that, with minimal adjustment, should be applicable to many other species. We also describe a procedure for collecting highly volatile compounds from C. elegans. We are distributing our mass spectral library in an effort to facilitate wider use of metabolomics.

  20. Spatial Patterns of Soil Development, Methane Oxidation, and Methanotrophic Diversity along a Receding Glacier Forefield, Southeast Greenland

    DEFF Research Database (Denmark)

    Barcena, Teresa Gomez; Finster, Kai; Yde, Jacob Clement

    2011-01-01

    Increasing global annual temperature leads to massive loss of ice cover worldwide. Consequently, glaciers retreat and ice-covered areas become exposed. We report on a study from the Mittivakkat Gletscher forefield in Southeast Greenland with special focus on methanotrophy in relation to exposure...... time to the atmosphere. The Mittivakkat Gletscher has receded since the end of the Little Ice Age (LIA; about AD 1850) and has left behind a series of deposits of decreasing age concurrently with its recession. Soil samples from this chronosequence were examined in order to elucidate main soil...... methanotrophs were at very low abundance and diversity during glaciation probably due to anoxia at the ice-sediment interface and that colonization after deglaciation is not completed yet. More detailed studies are required to explain the causes of discrepancy between activity and presence of high...

  1. Effects of fish farm waste on Posidonia oceanica meadows: Synthesis and provision of monitoring and management tools

    Energy Technology Data Exchange (ETDEWEB)

    Holmer, Marianne [Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark)], E-mail: holmer@biology.sdu.dk; Argyrou, Marina [Marine Environment Division, Department of Fisheries and Marine Research, Ministry of Agriculture, Natural Resources and Environment, 101 Bethleem Street, 1416 Nicosia (Cyprus); Dalsgaard, Tage [Department of Marine Ecology, National Environmental Research Institute, Aarhus University, Vejlsovej 25, P.O. Box 314, DK-8600 Silkeborg (Denmark); Danovaro, Roberto [Department of Marine Science, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona (Italy); Diaz-Almela, Elena; Duarte, Carlos M. [IMEDEA (CSIC-UIB), Miquel Marques 21, 07190 Esporles (Illes Balears) (Spain); Frederiksen, Morten [Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark); Grau, Antoni [Direccio General de Pesca, Conselleria d' Agricultura i Pesca, Govern de les Illes Balears, Foners 10, 07006 Palma de Mallorca (Illes Balears) (Spain); Karakassis, Ioannis [Marine Ecology Laboratory, Biology Department, University of Crete, Heraklion, 71409 Crete (Greece); Marba, Nuria [IMEDEA (CSIC-UIB), Miquel Marques 21, 07190 Esporles (Illes Balears) (Spain); Mirto, Simone [Institute for the Marine Coastal Environment, National Council of Research, Spianata S. Raineri, 86, 98122 Messina (Italy); Perez, Marta [Departament d' Ecologia, Universitat de Barcelona, Av. Diagonal 645, 08028 Barcelona (Spain); Pusceddu, Antonio [Department of Marine Science, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona (Italy); Tsapakis, Manolis [Institute of Oceanography, Hellenic Center for Marine Research, P.O. Box 2214, GR 71003 Heraklion, Crete (Greece)

    2008-09-15

    This paper provides a synthesis of the EU project MedVeg addressing the fate of nutrients released from fish farming in the Mediterranean with particular focus on the endemic seagrass Posidonia oceanica habitat. The objectives were to identify the main drivers of seagrass decline linked to fish farming and to provide sensitive indicators of environmental change, which can be used for monitoring purposes. The sedimentation of waste particles in the farm vicinities emerges as the main driver of benthic deterioration, such as accumulation of organic matter, sediment anoxia as well as seagrass decline. The effects of fish farming on P. oceanica meadows are diverse and complex and detected through various metrics and indicators. A safety distance of 400 m is suggested for management of P. oceanica near fish farms followed by establishment of permanent seagrass plots revisited annually for monitoring the health of the meadows.

  2. Seagrasses in the Age of Sea Turtle Conservation and Shark Overfishing

    Directory of Open Access Journals (Sweden)

    Michael R Heithaus

    2014-08-01

    Full Text Available Efforts to conserve globally declining herbivorous green sea turtles have resulted in promising growth of some populations. These trends could significantly impact critical ecosystem services provided by seagrass meadows on which turtles feed. Expanding turtle populations could improve seagrass ecosystem health by removing seagrass biomass and preventing of the formation of sediment anoxia. However, overfishing of large sharks, the primary green turtle predators, could facilitate turtle populations growing beyond historical sizes and trigger detrimental ecosystem impacts mirroring those on land when top predators were extirpated. Experimental data from multiple ocean basins suggest that increasing turtle populations can negatively impact seagrasses, including triggering virtual ecosystem collapse. Impacts of large turtle populations on seagrasses are reduced in the presence of intact shark populations. Healthy populations of sharks and turtles, therefore, are likely vital to restoring or maintaining seagrass ecosystem structure, function, and their value in supporting fisheries and as a carbon sink.

  3. Geochemical records of salt-water inflows into the deep basins of the Baltic Sea

    DEFF Research Database (Denmark)

    Neumann, T.; Christiansen, C.; Clasen, S.;

    1997-01-01

    +) accumulating in the deep, anoxic water body. Inflow of oxygenated water causes oxidation of Mn2+ to Mn4+ and precipitation of MnO2, which accumulates in Mn-rich layers at the sediment surface. When the bottom water becomes anoxic again, MnO2 degradation release Mn2+ into the pore water, and alkalinity......The estuarine circulation system of the Baltic Sea promotes stable stratification and bottom water anoxia in sedimentary basins of the Baltic proper. Ingressions of saline, oxygen-rich waters from the North Sea replace the oxygen depleted deep water. Timing and extent of the ingressions vary...... on time-scales of years to decades, and are largely determined by wind-strength and storm frequency over the North Atlantic Ocean and Europe. Mn/Fe-ratios in sediments from a dated sediment core of the Gotland Deep (250 m water depth) record variations in redox conditions that can be linked to historical...

  4. Abiotic causes of the great mass extinction of marine biota at the Triassic-Jurassic boundary

    Science.gov (United States)

    Barash, M. S.

    2015-05-01

    In the interval of the Triassic-Jurassic boundary up to 80% of marine species became extinct. The main hypotheses on the causes of this mass extinction are reviewed. The extinction was triggered by a powerful eruption of basalts in the Central Atlantic Magmatic Province. In addition, several impact craters have been found. Extraterrestrial factors resulted in two main sequences of events: terrestrial, leading to strong volcanism, and extraterrestrial (impact events). They produced similar effects: emissions of harmful chemical compounds and aerosols. Consequences included the greenhouse effect, darkening of the atmosphere (which prevented photosynthesis), stagnation of the oceans, and anoxia. Biological productivity decreased; food chains collapsed. As a result, all vital processes were disturbed, and a large portion of the biota went extinct.

  5. Oxygen effect in bacteriophages irradiated in different media. 1. Irradiation in salt solution

    Energy Technology Data Exchange (ETDEWEB)

    Korystov, Yu.N.; Veksler, F.B. (AN SSSR, Pushchino-na-Oke. Inst. Biologicheskoj Fiziki)

    1983-09-14

    The oxygen effect (OE) on bacteriophage T4 in a salt solution was studied. It is shown that the sign and magnitude of OE depend on the conditions of the postirradiation incubation of the phage in irradiated medium. The direct OE is due to postirradiation lesion of the phage by hydrogen peroxide which is formed in greater amounts after irradiation in oxygen than in anoxia. The addition of catalase is shown to eliminate the postirradiation inactivation of the phage. In this case an opposite OE is observed. The mechanism of this effect is a scavenge of hydrogen atoms which damage the phage by oxygen. In the presence of catalase the OE depends also on pH of the solution. It is suggested that the hydroxyl radical arising from the reaction of H/sub 2/O/sub 2/ with Fe/sup 2 +/ is responsible for the damaging effect of H/sub 2/O/sub 2/.

  6. PALAEOECOLOGICAL CHANGES AFTER THE END-PERMIAN MASS EXTINCTION: EARLY TRIASSIC OSTRACODS FROM NORTHWESTERN GUANGXI PROVINCE,SOUTH CHINA

    Directory of Open Access Journals (Sweden)

    SYLVIE CRASQUIN-SOLEAU

    2006-03-01

    Full Text Available Early Triassic (Griesbachian to Spathian ostracod faunas are here first discovered and described form the Guangxi Province, South China. Thirty-seven species belonging to fourteen genera are recognized. Seven species are new: Bairdia fengshanensis n.sp., Bairdia wailiensis n.sp., Liuzhinia guangxiensis n.sp., Ptychobairdia luciaae n.sp., Ptychobairdia aldaae n.sp., Paracypris jinyaensis n.sp. and Paracypris gaetanii n.sp. The Griesbachian assemblage from the basal microbial limestone is well diversified and does not suggest any abnormal palaeoenvironmental conditions in terms of salinity, temperature or oxygen content. Particularly, the ostracods are typical of well oxygenated water and do not reflect any anoxia. Dienerian and Smithian ostracods are evidenced for the first time and the assemblages suggest less favourable palaeoenviromental conditions. Diversity and abundance of ostracod assemblages recovered from the Spathian on. The main taxonomic turnover among ostracod assemblages occurred seemingly between the Griesbachian and the Spathian.

  7. Protein degradation to low-molecular compounds after death and during reanimation.

    Science.gov (United States)

    Konikova, A S; Vinarskaya, A A; Nikulin, V I; Pogossova, A V; Petukhova, L M

    1975-09-11

    The process of protein degradation to amino acids and peptides in rabbits following death and during reanimation in terms of the effects of artificial postmortem cooling on that process has been studied. Protein degradation was judged by increase of low-molecular nitrogenous compounds in serum and in organs by increase in soluble radioactivity with time in animals the proteins of which had been marked in vivo with radioisotopes. It has been found that immediately after death resulting from acute anoxia the processes of protein degradation to amino acids as well as synthesis stops in liver, skeletal and cardiac muscles, spleen, brain and spinal cord. Similar phenomenon takes place in the case of deep hypothermy. During reanimation the process of protein degradation to low-molecular compounds in organs restores. PMID:809921

  8. Core sediment biogeochemistry in specific zones of Cochin Estuarine System (CES)

    Indian Academy of Sciences (India)

    P S Akhil; Manju P Nair; C H Sujatha

    2013-12-01

    Geochemical composition is a set of data for predicting the climatic condition existing in an ecosystem. Both the surficial and core sediment geochemistry are helpful in monitoring, assessing and evaluating the marine environment. The aim of the research work is to assess the relationship between the biogeochemical constituents in the Cochin Estuarine System (CES), their modifications after a long period of anoxia and also to identify the various processes which control the sediment composition in this region, through a multivariate statistical approach. Therefore the study of present core sediment geochemistry has a critical role in unraveling the benchmark of their characterization. Sediment cores from four prominent zones of CES were examined for various biogeochemical aspects. The results have served as rejuvenating records for the prediction of core sediment status prevailing in the CES.

  9. Rogoznica Lake (Croatia), a unique anoxic seawater system on the Adriatic coast under the anthropogenic pressures

    Science.gov (United States)

    Ciglenečki, Irena; Bura-Nakić, Elvira; Marguš, Marija; Čanković, Milan; Carić, Marina; Viličić, Damir; Ljubešić, Zrinka; Kršinić, Frano; Batistić, Mirna; Janeković, Ivica; Plavčić, Filip

    2014-05-01

    Rogoznica Lake is a typical example of euxinic saline lake, situated on the eastern Adriatic coast (43o32'N 15o58'E). It is a karstic depression filled with seawater, with an area of 10276 m2 and a maximum depth of 15m The lake has circular shape and is surrounded with sheer, karstic cliffs (4-23 m high), which completely protect the lake from the influence of the wind. During the year the lake is thermally, densely and chemically stratified into oxic and anoxic layers. The surface water is well oxygenated, while hypoxia/anoxia occurs in the bottom layer. The mixolimnion varies seasonally and it is greatly influenced by meteorological conditions (temperature, wind, rainfall) which also influence the water layer mixing. Vertical mixing usually occurs during autumn/winter when cold, oxygen-rich water from the surface sinks downwards. Depending on the intensity of the mixing process anoxic conditions in the entire water column could appear. At the boundary oxia-anoxia usually a pinky colored chemocline layer, cca 50 cm thick develops. Anoxic deep water is characterized by high concentrations of reduced sulfur compounds (RSS up to 1mM, mainly in the form of sulfide), and nutrients (NH4+, up to 150 μM; PO43-, up to 22 μM; SiO44-, up to 400 μM) as well as dissolved organic carbon (DOC up to 6 mg l-1) indicating the pronounced remineralization of allochthonous organic matter produced in the surface water The eutrophication of the lake is strongly influenced by nutrient recycling under anaerobic conditions. Due to the extreme ecological conditions which prevail in this lake, phyto- and zooplankton populations are represented by a relatively small number of species, some of them, however, in the populations denser than those in the surrounding sea. After the period of total anoxia appearance, the number of species and their abundance are significantly reduced in comparison with the pre-anoxia values. Diatoms were found to be the dominant microphytoplankton group while

  10. Anaerobic nitrogen turnover by sinking diatom aggregates at varying ambient oxygen levels

    DEFF Research Database (Denmark)

    Stief, Peter; Kamp, Anja; Thamdrup, Bo;

    2016-01-01

    anaerobic nitrogen cycling at ambient oxygen levels well above the hypoxic threshold. Aggregates were produced from the ubiquitous diatom Skeletonema marinoi and the natural microbial community of seawater. Microsensor profiling through the center of sinking aggregates revealed internal anoxia at ambient 40......% air saturation (∼100 μmol O2 L-1) and below. Accordingly, anaerobic nitrate turnover inside the aggregates was evident within this range of ambient oxygen levels. In incubations with 15N-labeled nitrate, individual Skeletonema aggregates produced NO2- (up to 10.7 nmol N h-1 per aggregate), N2 (up to 7.......1 nmol N h-1), NH4+ (up to 2.0 nmol N h-1), and N2O (up to 0.2 nmol N h-1). Intriguingly, nitrate stored inside the diatom cells served as an additional, internal nitrate source for dinitrogen production, which may partially uncouple anaerobic nitrate turnover by diatom aggregates from direct ambient...

  11. Vulcanization of lipidic organic matter in reactive-iron deficient environments: a possible enhancement for the storage of hydrogen-rich organic matter

    Energy Technology Data Exchange (ETDEWEB)

    Tribovillard, N.P.; Desprairies, A. (Paris-11 Univ., 91 - Orsay (France)); Lallier-Verges, E. (Orleans Univ., 45 (France)); Bertrand, P. (Bordeaux-1 Univ., 33 - Talence (France))

    1994-11-01

    Geochemists have highlighted an important mechanism for kerogen formation: the early, HS[sup -]/H[sub 2]S - induced, vulcanization which protects organic-sulfur compounds from bacterial degradation. We base our study on two formations in which organic-matter accumulation is thought to result principally from organic-walled-plankton productivity. When reactive iron was a limiting factor for Fe-sulfide formation, organic matter was enriched in sulfur, and TOC and HI values were higher. We suggest the lack of reactive iron could promote vulcanization of organic matter, helping its storage and keeping HI at high values. Bottom-water anoxia could promote this mechanism (positive feedback effect). (authors). 11 refs., 2 figs., 1 tab.

  12. Assessing potential impacts of climate change and variability on the Great Lakes-St. Lawrence Basin: A binational approach

    International Nuclear Information System (INIS)

    The potential impacts of climate change and variability on the Great Lakes environment are serious and complex. The Great Lakes-St. Lawrence Basin is home to 42.5 million US and Canadian citizens and is the industrial and commercial heartland of both nations. The region is rich in human and natural resources, with diverse economic activities and substantial infrastructure which would be affected by major shifts in climate. For example, water level changes could affect wetland distribution and functioning; reductions in streamflow would alter assimilative capacities while warmer water temperatures would influence spring and fall turnover and incidence of anoxia. A binational program has been initiated to conduct interdisciplinary, integrated impact assessments for the Great Lakes-St. Lawrence River Basin. The goal of this program is to undertake interdisciplinary, integrated studies to improve the understanding of the complex interactions between climate, the environment, and socioeconomic systems in order to develop informed regional adaptation responses

  13. Regulation of bacterial sulfate reduction and hydrogen sulfide fluxes in the central Namibian coastal upwelling zone

    DEFF Research Database (Denmark)

    Bruchert, V.; Jørgensen, BB; Neumann, K.;

    2003-01-01

    and the low capacity to oxidize and trap sulfide. The inner shelf break marks the seaward border of sulfidic bottom waters, and separates two different regimes of bacterial sulfate reduction. In the sulfidic bottom waters on the shelf, up to 55% of sulfide oxidation is mediated by the large nitrate......The coastal upwelling system off central Namibia is one of the most productive regions of the oceans and is characterized by frequently occurring shelf anoxia with severe effects for the benthic life and fisheries. We present data on water column dissolved oxygen, sulfide, nitrate and nitrite, pore...... water profiles for dissolved,sulfide and sulfate, S-35-sulfate reduction rates, as well as bacterial counts of large sulfur bacteria from 20 stations across the continental shelf and slope. The stations covered two transects and included the inner shelf with its anoxic and extremely oxygen...

  14. Sulfide intrusion and detoxification in Zostera marina

    DEFF Research Database (Denmark)

    Hasler-Sheetal, Harald; Holmer, Marianne

    2014-01-01

    Sulfide intrusion in seagrasses represents a global threat to seagrasses. In contrast seegrasses grow in hostile sediments, where they are constantly exposed to sulfide intrusion. Little is known about the strategies to survive sulfide intrusion, if there are detoxification mechanisms and sulfur...... nutrition in general. By a global review of sulfide intrusion, coupled with a series of field studies and in situ experiments we elucidate sulfide intrusion and different strategies of seagrasses to sustain sulfide intrusion. Using stable isotope tracing, scanning electron microscopy with x-ray analysis...... to trace sulfur compounds and as well as metabolomics upon sulfide and anoxia exposure we identified different strategies to cope with sulfidic sediments. 1) Avoidance, by reoxidation of gaseous sulfide in the arenchyma to elemental sulfur and sulfate; where precipitation of sulfide occurred as non...

  15. Corneal endothelial changes in superficial epithelial keratopathy.

    Science.gov (United States)

    Brooks, A M; Grant, G; Gillies, W E

    1986-05-01

    A series of five cases is described in which superficial punctate keratopathy was associated with endothelial cell changes. The most striking change was the presence of dark areas or blebs, usually two to four cell diameters in extent. There was also distortion and crumpling of the corneal endothelium, mild pleomorphism and polymegathism of the endothelial cells, with a reduced cell count in some cases. These blebs have previously been reported in hard and soft contact lens wearers and are due to intercellular oedema with separation of endothelial cells from Descemet's membrane. Anoxia and interference with osmosis have been proposed as possible mechanisms for the production of these blebs, but our cases demonstrate that fine disruption of the corneal epithelium can affect the integrity of the corneal endothelium and may lead to significant damage over a long period of time. PMID:3801208

  16. Cardiac hypertrophy and failure--a disease of adaptation. Modifications in membrane proteins provide a molecular basis for arrhythmogenicity.

    Science.gov (United States)

    Moalic, J M; Charlemagne, D; Mansier, P; Chevalier, B; Swynghedauw, B

    1993-05-01

    Cardiac hypertrophy is the physiological adaptation of the heart to chronic mechanical overload. Cardiac failure indicates the limits of the process. Cardiac hypertrophy is only one example of biological adaptation and results from the induction of several changes in gene expression, mostly of the fetal type, including those coding for the myosin heavy chain or the alpha-subunit of the Na+,K(+)-ATPase. From a thermodynamic point of view, the decrease in Vmax allows the heart to produce a normal tension at a lower cost. This process results from changes both in the sarcomere and in the expression of certain membrane proteins. The decrease in calcium transient is determined by several changes in membrane proteins that result in a rather fragile equilibrium in terms of calcium homeostasis. Any abnormal input in calcium will have exaggerated detrimental consequences on a hypertrophied myocyte and may cause automaticity and arrhythmias or an exaggerated response to anoxia in terms of compliance. PMID:8485830

  17. Resistance of Lophelia pertusa to coverage by sediment and petroleum drill cuttings.

    Science.gov (United States)

    Allers, Elke; Abed, Raeid M M; Wehrmann, Laura M; Wang, Tao; Larsson, Ann I; Purser, Autun; de Beer, Dirk

    2013-09-15

    In laboratory experiments, the cold-water coral Lophelia pertusa was exposed to settling particles. The effects of reef sediment, petroleum drill cuttings and a mix of both, on the development of anoxia at the coral surface were studied using O2, pH and H2S microsensors and by assessing coral polyp mortality. Due to the branching morphology of L. pertusa and the release of coral mucus, accumulation rates of settling material on coral branches were low. Microsensors detected H2S production in only a few samples, and sulfate reduction rates of natural reef sediment slurries were low (coral's accessibility to oxygen, L. pertusa tolerated both partial low-oxygen and anoxic conditions without any visible detrimental short-term effect, such as tissue damage or death. However, complete burial of coral branches for >24 h in reef sediment resulted in suffocation. PMID:23915980

  18. Improvement of quality of life in patients with advanced tumor underwent chemotherapy after middle dose medroxyprogesterone administered%晚期肿瘤化疗病人服用中等剂量量甲孕酮对提高生活质量的作用

    Institute of Scientific and Technical Information of China (English)

    江澜; 江咏梅; 奚昊

    2002-01-01

    Objective To study the effect of medroxyprogesterone on body weight loss,myelosuppression, anorexia and quality of life (QOL) in patients with advanced neoplasm.Method 37 patients in group A received 200 mg domestic medroxyprogesterone capsule,three times a day for 4 consecutive weeks.37 patients in group B received 500 mg tablet of import medroxyprogesterone,once a day for 4 consecutive weeks. Result Therapeutic effect of domestic and import medroxyprogesterone was similar of group A and B in terms of anoxia,body weight loss,QOL(P >0.05).Side effects included abnormal liver function,edema,and moon shaped face.Conclusion Medroxyprogesterone belongs to supportive therapy for patients with advanced tumor,which can improve QOL.Therapeutic effect of middle dose medroxyprogesterone is satisfying.

  19. Pregnancy in women with thalassemia: challenges and solutions

    Directory of Open Access Journals (Sweden)

    Petrakos G

    2016-09-01

    Full Text Available George Petrakos, Panagiotis Andriopoulos, Maria Tsironi Department of Nursing, University of Peloponnese, Sparta, Greece Abstract: Advances in treatment of thalassemia have led to the aging of thalassemic patients, and consequently concern about successful reproductive outcome is augmented. Although women with thalassemia intermedia only were considered competent of achieving pregnancy, case series reveal the willingness of both thalassemia major and thalassemia intermedia women to have a family. Pregnancy in general is characterized by dynamic multiple-system changes and increased susceptibility to oxidative stress, while homozygous, transfusion-dependent, β-thalassemia patients manifest cardiac, hepatic, endocrine, and metabolic disorders attributable to chronic anoxia and iron overload and thalassemia intermedia, usually nontransfused, is associated with augmented risk of thromboembolic events. Pregnancy in thalassemia should be considered a high risk for both mother and fetus, and favorable outcomes are the result of continuous preconception, antenatal, and postpartum assessment and management by a team of thalassemia experts. Keywords: thalassemia, pregnancy, chelation, transfusion, iron

  20. Late Pliensbachian-early Toarcian paleoenvironmental changes in the Cleveland Basin: new clues from high-resolution trace element analysis

    Science.gov (United States)

    Thibault, N.; Ruhl, M.; Ullmann, C. V.; Korte, C.; Kemp, D. B.; Hesselbo, S. P.

    2013-12-01

    The early Toarcian (~183 Ma ago) was characterized by massive carbon burial and a pronounced negative carbon-isotope excursion (CIE) in marine carbonate and marine and terrestrial organic matter. These features along with the high abundance of redox sensitive trace metals in that interval led to the recognition of a major oceanic anoxic event (OAE). More recently, an earlier companion of the early Toarcian CIE has been documented at the Pliensbachian/Toarcian (Pl/To) boundary in sections of NW Europe, but its expression in the sediment and possible causes are less constrained. One of the most studied areas for this interval is the Cleveland Basin, UK, which is well-studied for litho-, bio- and chemostratigraphy. Here, we present a new dataset of high-resolution element data produced by hand-held X-ray fluorescence analysis to test for the expression of redox-sensitive trace metals and detrital elements across the late Pliensbachian to middle Toarcian of the Cleveland Basin. The Pl/To boundary CIE is associated with low Total Organic Carbon (TOCoxygenation events that prevented massive deposition of organic matter. Trends from redox-sensitive elements such as Fe, V, Mo and U are in agreement with previous findings and scenarios of basin restriction across and after the early Toarcian OAE (McArthur et al., 2008). An interval of maximum enrichment in these elements immediately after the CIE is a feature very similar to the recent observations of Hermoso et al. (2013) in the Paris Basin. This suggests a similar tempo of regional anoxia and black shale deposition in NW Europe. These results also shed light on the behaviour of elements associated with organic matter and the sulphur cycle such as Ni, Cu, Zn and As. Cu is well-correlated to the TOC whereas As shows an enrichment in the interval of black shale deposition after the CIE and two distinct correlation lines with sulphur, one before and during the event, and one after the CIE. This suggests that more As could be

  1. Combination of upflow anaerobic sludge blanket (UASB) reactor and partial nitritation/anammox moving bed biofilm reactor (MBBR) for municipal wastewater treatment.

    Science.gov (United States)

    Malovanyy, Andriy; Yang, Jingjing; Trela, Jozef; Plaza, Elzbieta

    2015-03-01

    In this study the combination of an upflow anaerobic sludge blanket (UASB) reactor and a deammonification moving bed biofilm reactor (MBBR) for mainstream wastewater treatment was tested. The competition between aerobic ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) was studied during a 5months period of transition from reject water to mainstream wastewater followed by a 16months period of mainstream wastewater treatment. The decrease of influent ammonium concentration led to a wash-out of suspended biomass which had a major contribution to nitrite production. Influence of a dissolved oxygen concentration and a transient anoxia mechanism of NOB suppression were studied. It was shown that anoxic phase duration has no effect on NOB metabolism recovery and oxygen diffusion rather than affinities of AOB and NOB to oxygen determine the rate of nitrogen conversion in a biofilm system. Anammox activity remained on the level comparable to reject water treatment systems.

  2. Protective effects of Ginkgo biloba extract 761 against glutamate-induced neurotoxicity in cultured retinal neuron

    Institute of Scientific and Technical Information of China (English)

    WANG Yun-song; XU Liang; MA Ke; WANG Shuang; WANG Jin-jin

    2005-01-01

    @@ A large part of neuronal death is the result of episodes of anoxia and ischaemia in the retina and other eye diseases, such as anterior ischemic optic neuropathy, glaucoma. The neuronal death is due to the accumulation of glutamate in the extracellular space. Glutamate is the primary excitatory neurotransmitter in the retina. However, excessive overactivation of glutamate receptors leads to excitotoxic neuronal cell death. Glutamate induces cell death by increasing the levels of intracellular Ca2+ in neurons, thereby leading to generation of free radicals and activation proteases, as well as transcriptional activation of specific cell death programs. Glutamate excitoxicity can also cause neuronal mitochondrial membrane potential (MMP) loss, which is associated with changes in mitochondrial function leading to a neuronal dysfunction.

  3. Ten years of Integrated Pest Management (IPM at the Kunsthistorisches Museum in Wien

    Directory of Open Access Journals (Sweden)

    Pascal Querner

    2011-08-01

    Full Text Available The Kunsthistorisches Museum Wien is one of the largest fine arts collections worldwide, comprising the Kunsthistorisches Museum, the Austrian Theater Museum, the Museum of Ethnology, all placed in Vienna, and Schloß Ambras in Tirol. We present results from up to 10 years of insect pest monitoring in different collections and the implementation of an Integrated Pest Management (IPM concept. The Kunsthistorisches Museum was the first museum in Vienna to introduce such a concept. We also present specific insect pest problems such as a biscuit beetle (Stegobium paniceum infestation of paintings lined with starch paste backings (linings or the webbing clothes moth (Tineola bisselliella infestation at the Museum of Carriages, both repeatedly occurring problems in the museum. With the help of the insect pest monitoring programs, these and other problems were found and the infested objects treated, usually with anoxia (nitrogen.

  4. Effects of transient soil waterlogging and its importance for rootstock selection

    Directory of Open Access Journals (Sweden)

    Michelle Morales-Olmedo

    2015-08-01

    Full Text Available Under transient waterlogging, a number of transformations in the soil are generated associated with lack of aeration, seriously affecting the root system. Significant progress has been reported on understanding the effects of lack of oxygen on the metabolism of the roots, although few studies have examined changes in the soil. Diverging conclusions about the degree of tolerance exhibited by plants exclude the effects of hypoxia and anoxia on physical-chemical soil properties under plant experiments. This review examines the main changes occurring in soil and roots due to transient soil waterlogging conditions. Parameters such as antioxidant capacity, nutrient uptake dynamics and regeneration and distribution of the root system are relevant for selecting rootstocks tolerant to soil waterlogging.

  5. [Report of a patient with Lesch-Nyhan syndrome caused by total deficiency of HGPRT and with normal activity in female family members].

    Science.gov (United States)

    Ferrández, A; Mayayo, E; Nyhan, W L; Bakay, B

    1982-07-01

    Authors present a 10 year old boy with Lesch-Nyhan syndrome with self-inflicted mutilations to the lips, tongue and interior cheek wall, partially avoided by tooth extraction. Hand lesions were prevented by arm restriction. Born with anoxia and in spite of seizures for several years and a marked muscle stiffness, he is relatively aware of his surroundings. HGPRT activity in blood and hair was nil, while the APRT activity was increased. The mother, a maternal aunt and grandmother are not carriers. Hyperuricemia measured several times and treated with allopurinol is kept between 3 and 4 mg/dl and lastly under 3 mg after increasing dosage. Some years ago, elimination of acid uric stones in urine was observed without hematuria. It seems that recently stone elimination produced pain difficult to evaluate in this patient. PMID:7137725

  6. Interactions between X-rays and antimitotic drugs: cellular effects

    International Nuclear Information System (INIS)

    The interactions between three drugs and X-rays were examined in rat hepatoma cells in vitro. Incubation with Daunomycine or 9-hydroxy ellipticine decreases the survival of both exponential and plateau phase cells, whereas cis-Pt (II) decreases the survival of plateau cells, especially irradiated in anoxia. The decrease in the Do was greater when the cells were incubated with the drugs prior to X-irradiation, and was greater in the case of plateau cells than in the case of exponential cells. The repair of potentially lethal damages was inhibited by these three compounds. However, the repair of sublethal damages was inhibited by cis-Pt II, but was modified neither by Daunomycine nor 9-hydroxy ellipticine

  7. A 3D hydrodynamic fate and transport model for herbicides in Sacca di Goro coastal lagoon (Northern Adriatic).

    Science.gov (United States)

    Carafa, R; Marinov, D; Dueri, S; Wollgast, J; Ligthart, J; Canuti, E; Viaroli, P; Zaldívar, J M

    2006-10-01

    Sacca di Goro is a shallow coastal microtidal lagoon with a surface area of 26 km2, and an average depth of about 1.5m. Fresh water pollutant loads from Po River branches and several drainage canals lead to anthropogenic eutrophication, frequent summer anoxia crises and chemical contamination. Such events not only affect the lagoon ecosystem but also cause serious economic losses, the lagoon being the second largest producer of clams in Italy. The present work aims at using a fate model coupled with COHERENS 3D hydrodynamic model to simulate and to explain the spatial distribution and temporal variations of s-triazines herbicides in the Sacca di Goro lagoon. The simulation results of spatial and temporal dynamic behaviour of atrazine, simazine and terbuthylazine have been compared with experimental data obtained during an annual monitoring programme. PMID:16643962

  8. Effects of filamentous macroalgae on growth and survival of eelgrass, Zostera marina, seedlings

    DEFF Research Database (Denmark)

    Rasmussen, Jonas; Krause-Jensen, Dorte; Olesen, Birgit

    Seedling survival and patch establishment is a major bottle-neck for eelgrass (Zostera marina) re-colonization as mortality rates among the young seedlings are high, even in areas where conditions should support survival. We here focus on the potential negative effects of drifting macroalgal mats...... the mat and periods of anoxia in the lower parts can possibly be followed by release of sulphide from the sediments. We assessed the impact of algae mats on seedling performance and evaluated the relative importance of light attenuation and low oxygen concentrations for seedling growth and survival based...... on a 2-factorial laboratory experiment. Eelgrass seedlings were grown with three different heights and two different types of algae mats: Chaetomorpha linum and artificial macroalgae. The two types of mats were used to separate the physical and metabolic effects of algal presence. Concentrations...

  9. Combination of upflow anaerobic sludge blanket (UASB) reactor and partial nitritation/anammox moving bed biofilm reactor (MBBR) for municipal wastewater treatment.

    Science.gov (United States)

    Malovanyy, Andriy; Yang, Jingjing; Trela, Jozef; Plaza, Elzbieta

    2015-03-01

    In this study the combination of an upflow anaerobic sludge blanket (UASB) reactor and a deammonification moving bed biofilm reactor (MBBR) for mainstream wastewater treatment was tested. The competition between aerobic ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) was studied during a 5months period of transition from reject water to mainstream wastewater followed by a 16months period of mainstream wastewater treatment. The decrease of influent ammonium concentration led to a wash-out of suspended biomass which had a major contribution to nitrite production. Influence of a dissolved oxygen concentration and a transient anoxia mechanism of NOB suppression were studied. It was shown that anoxic phase duration has no effect on NOB metabolism recovery and oxygen diffusion rather than affinities of AOB and NOB to oxygen determine the rate of nitrogen conversion in a biofilm system. Anammox activity remained on the level comparable to reject water treatment systems. PMID:25600011

  10. Rapid formation of Ontong Java Plateau by Aptian mantle plume volcanism

    International Nuclear Information System (INIS)

    The timing of flood basalt volcanism associated with formation of the Ontong Java Plateau (OJP) is estimated from paleomagnetic and paleontologic data. Much of OJP formed rapidly in less than 3 million years during the early Aptial, at the beginning of the Cretaceous Normal Polarity Superchron. Crustal emplacement rates are inferred to have been several times those of the Deccan Traps. These estimates are consistent with an origin of the OJP by impingement at the base of the oceanic lithosphere by the head of a large mantle plume. Formation of the OJP may have led to a rise in sea level that induced global oceanic anoxia. Carbon dioxide emissions likely contributed to the mid-Cretaceous greenhouse climate but did not provoke major biologic extinctions

  11. Consciousness, unconsciousness and death in the context of slaughter. Part I. Neurobiological mechanisms underlying stunning and killing.

    Science.gov (United States)

    Terlouw, Claudia; Bourguet, Cécile; Deiss, Véronique

    2016-08-01

    This review describes the neurobiological mechanisms that are relevant for the stunning and killing process of animals in the abattoir. The mechanisms underlying the loss of consciousness depend on the technique used: mechanical, electrical or gas stunning. Direct exsanguination (without prior stun) causes also a loss of consciousness before inducing death. The underlying mechanisms may involve cerebral anoxia or ischemia, or the depolarisation, acidification and/or the destruction of brain neurons. These effects may be caused by shock waves, electrical fields, the reduction or arrest of the cerebral blood circulation, increased levels of CO2 or low levels of O2 in the inhaled air, or the mechanical destruction of neurons. The targeted brain structures are the reticular formation, the ascending reticular activating system or thalamus, or the cerebral hemispheres in a general manner. Some of the techniques, when properly used, induce an immediate loss of consciousness; other techniques a progressive loss of consciousness. PMID:27103547

  12. Echoes from the past: a healthy Baltic Sea requires more effort.

    Science.gov (United States)

    Kotilainen, Aarno T; Arppe, Laura; Dobosz, Slawomir; Jansen, Eystein; Kabel, Karoline; Karhu, Juha; Kotilainen, Mia M; Kuijpers, Antoon; Lougheed, Bryan C; Meier, H E Markus; Moros, Matthias; Neumann, Thomas; Porsche, Christian; Poulsen, Niels; Rasmussen, Peter; Ribeiro, Sofia; Risebrobakken, Bjørg; Ryabchuk, Daria; Schimanke, Semjon; Snowball, Ian; Spiridonov, Mikhail; Virtasalo, Joonas J; Weckström, Kaarina; Witkowski, Andrzej; Zhamoida, Vladimir

    2014-02-01

    Integrated sediment multiproxy studies and modeling were used to reconstruct past changes in the Baltic Sea ecosystem. Results of natural changes over the past 6000 years in the Baltic Sea ecosystem suggest that forecasted climate warming might enhance environmental problems of the Baltic Sea. Integrated modeling and sediment proxy studies reveal increased sea surface temperatures and expanded seafloor anoxia (in deep basins) during earlier natural warm climate phases, such as the Medieval Climate Anomaly. Under future IPCC scenarios of global warming, there is likely no improvement of bottom water conditions in the Baltic Sea. Thus, the measures already designed to produce a healthier Baltic Sea are insufficient in the long term. The interactions between climate change and anthropogenic impacts on the Baltic Sea should be considered in management, implementation of policy strategies in the Baltic Sea environmental issues, and adaptation to future climate change. PMID:24414805

  13. Batroxobin Against Anoxic Damage of Rat Hippocampal Neurons in Culture: Morphological Changes and Hsp70 Expression

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@Batroxobin,the thrombin-like enzyme,is used for therapeutic defibrination. We have found that batroxobin has good therapeutic effect in ischemic reperfusion rats and clinical practices in vivo. But we have not studied the neuroprotective effect of batroxobin on anoxic hippocampal neurons in vitro. The purpose of this study was to obtain further information on the mechanism of the batroxobin-induced neuroprotection and examine the neuroprotective effect on neurons exposed to anoxia. The effect of batroxobin on anoxic damages in cultured hippocampal neurons of neonatal rats was investigated by using morphological changes and heat shock protein 70Kd (Hsp70) immunoreactive expression as indicators. The results indicate that batroxobin, besides its defibrination, may have a direct neuroprotective effect on anoxic damage of hippocampal neurons.

  14. The Fish may be Used in the Space System

    Science.gov (United States)

    Liu, Chungchu; Liu, Xiaofeng; Lin, Zhongning

    Scientists in Space area like to grow fish in the biosphere, but they worry about that fish will contest oxygen with humans. Therefore growing low-oxygen-needing fish is very important. After research, we found a fish which may be a promising fish used in space system. This fish can grow normally under 1mg O2/1000 mg water oxygen condition while other species of fish die away. How to keep astronauts healthy and having delicious food are problem to raise life qualities of astronauts in space. Our pharmacological test shows that this chosen fish, with high DHA and EPA, in general, other fresh-water fish has low DHA and EPA. It has functions of anti-radiation and anti-tumor. It can also prolong cruor time, anoxia-tolerating, and swimming time after the mice feeding with the fish's meat.

  15. Age, transvestism, bondage, and concurrent paraphilic activities in 117 fatal cases of autoerotic asphyxia.

    Science.gov (United States)

    Blanchard, R; Hucker, S J

    1991-09-01

    Autoerotic asphyxia is the practice of self-inducing cerebral anoxia, usually by hanging, strangulation, or suffocation, during masturbation. This study investigated the relationships between: asphyxiators' ages; two paraphilias commonly accompanying autoerotic asphyxia, bondage and transvestism; and various other types of simultaneous sexual behaviour. Subjects were two concurrent series totalling 117 males aged 10-56 who died accidentally during autoerotic asphyxial activities. Data concerning sexual paraphernalia at the scene of death or among the deceased's effects were extracted from coronors' files using standardised protocols. Anal self-stimulation with dildos, etc., and self-observation with mirrors or cameras were correlated with transvestism. Older asphyxiators were more likely to have been simultaneously engaged in bondage or transvestism, suggesting elaboration of the masturbatory ritual over time. The greatest degree of transvestism was associated with intermediate rather than high levels of bondage, suggesting that response competition from bondage may limit asphyxiators' involvement in a third paraphilia like transvestism. PMID:1958948

  16. Heterogeneity of O2 dynamics in soil amended with animal manure and implications for greenhouse gas emissions

    DEFF Research Database (Denmark)

    Zhu, Kun; Bruun, Sander; Larsen, Morten Kobæk;

    2015-01-01

    ) from soil at high temporal resolution were monitored. At the end of the incubations, vertical profiles of mineral nitrogen (ammonium and nitrate) in the soil matrix were quantified. The optode results revealed that anoxia rapidly developed in zones with manure addition and gradually expanded......Soil oxygen (O2) availability influences nitrification and denitrification, the major biological processes responsible for nitrous oxide (N2O) production and missions from soil. In this study O2-specific planar optodes were used to visualise O2 distribution with high spatial and temporal resolution...... in soils in which the same amount of solid fraction of pig manure had been distributed in three different ways (mixed, layered, single patch) and which were maintained at awater potential of 5 kPa (corresponding to 91% of water-filled pore space). In parallel, the greenhouse gas emissions (N2O, CO2 and CH4...

  17. [Postoperative medical icterus].

    Science.gov (United States)

    Cerf, M

    1978-06-01

    The onset of jaundice following a surgical operation sometimes raises difficult problems. It is rarely due to hemolysis, infective hepatitis or decomposated cirrhosis of the liver. One should seek as a routine hepatitis due to halotane. However the most frequent cause is "benign postoperative cholestasis". This variety of jaundice presents in the form of an icterus due to conjugated bilirubine with often a large increase in alkaline phosphatase levels. The ocurse is variable. Almost always due to severe surgical or septic trauma, accompanied by shock and/or anoxia, it raises difficult diagnostic problems. The clinical and physiopathological aspects of benign postoperative cholestasis are recalled. One should remember, above all, that this is not an autonomous clinical entity but the sign of local or general complications which should be sought carefully.

  18. Hemoglobin isoform differentiation and allosteric regulation of oxygen binding in the turtle, Trachemys scripta

    DEFF Research Database (Denmark)

    Damsgaard, Christian; Storz, Jay F.; Hoffmann, Federico G.;

    2013-01-01

    When freshwater turtles acclimatize to winter hibernation, there is a gradual transition from aerobic to anaerobic metabolism, which may require adjustments of blood O2 transport before turtles become anoxic. Here, we report the effects of protons, anionic cofactors, and temperature on the O2......-binding properties of isolated hemoglobin (Hb) isoforms, HbA and HbD, in the turtle Trachemys scripta. We determined the primary structures of the constituent subunits of the two Hb isoforms, and we related the measured functional properties to differences in O2 affinity between untreated hemolysates from...... turtles that were acclimated to normoxia and anoxia. Our data show that HbD has a consistently higher O2 affinity compared with HbA, whereas Bohr and temperature effects, as well as thiol reactivity, are similar. Although sequence data show amino acid substitutions at two known β-chain ATP-binding site...

  19. The shell vasculature of Trachemys turtles investigated by modern 3D imaging techniques

    DEFF Research Database (Denmark)

    Hansen, Kasper; Thygesen, Jesper; Nielsen, Tobias Wang;

    Many freshwater turtles are extremely tolerant to the lack of oxygen and can survive the winter submerged in anoxic mud in ice-covered lakes. The pronounced anoxia-tolerance resides with a considerable depression of cellular metabolism and the ability to use the shell to buffer the acidosis arising...... from anaerobic metabolism (1). Infusion of microspheres has shown that the shell receives almost half of the cardiac output in turtles made anoxic at low temperatures (2). However, the vasculature of the turtle shell remains to be described. To visualise the vasculature within the carapace and plastron...... of the turtle Trachemys scripta, we perfused terminally anaesthetised turtles with different contrast enhancing agents (Microfil [lead n/a]), barium sulphate [250 mg/kg], and iodine [15-250 mg/kg]), and the animals were then scanned by both single source as well as dual energy Computed Tomographic systems...

  20. Periodic anoxic shelf in the Early-Middle Ordovician transition: ichnosedimentologic evidence from west-central Utah, USA

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Ichnosedimentologic evidence of periodic anoxic shelf in the Early-Middle Ordovician transition includes lower ichnodiversity, shallower bioturbation and burrowing depth (<4 cm ), rare domichnia, tiny Chondrites occupying shallower or shallowest tiering, widely distributed nodules of limonite pseudomorphs after pyrite, occurrence of trace fossils being closely associated with the storm event layers, and stratigraphic successions with orbital cyclostratigraphic architecture. It is suggested that lower atmospheric oxygen level during the Early Paleozoic, the Ordovician radiation, dramatic transgression and warmer temperatures would result in the periodic anoxia in the Early-Middle Ordovician transition. This episode began at the later Early Ordovician and lasted about 3.4 Ma on the basis of orbital cyclostratigraphy.

  1. Paleoredoc and pyritization of soft-bodied fossils in the Ordovician Frankfort Shale of New York

    DEFF Research Database (Denmark)

    Farrell, Una C.; Briggs, Derek E. G.; Hammarlund, Emma U.;

    2013-01-01

    not exclude brief episodes of water-column anoxia characterized by a ferruginous rather than an euxinic state. However, the highest Fe-HR/FeT values and redox-sensitive trace element enrichments occur in siltstone portions of turbidite beds and in concretions, suggesting that subsequent diagenesis had......Multiple beds in the Frankfort Shale (Upper Ordovician, New York State), including the original "Beecher's Trilobite Bed," yield fossils with pyritized soft-tissues. A bed-by-bed geochemical and sedimentological analysis was carried out to test previous models of soft-tissue pyritization...... a significant effect on the distribution of redox-sensitive elements in this succession. Moderately high Fe-HR/FeT and FeP/Fe-HR, low organic carbon, enriched delta S-34, and the frequent presence of iron-rich carbonate concretions in beds with soft tissue preservation confirm that pyritization was favored...

  2. Nitric oxide availability in deeply hypoxic crucian carp: acute and chronic changes and utilization of ambient nitrite reservoirs.

    Science.gov (United States)

    Hansen, Marie N; Gerber, Lucie; Jensen, Frank B

    2016-03-15

    Recent research suggest that anoxia-tolerant fish transfer extracellular nitrite into the tissues, where it is used for nitric oxide (NO) generation, iron-nitrosylation, and S-nitrosation of proteins, as part of the cytoprotective response toward prolonged hypoxia and subsequent reoxygenation. We hypothesized that crucian carp take up ambient nitrite and use it as a source of cellular NO availability during hypoxia. Fish were exposed for 1 day to normoxia (Po2 > 140 mmHg) and deep hypoxia (1 nitric oxide synthase-2 gene variant. The data support that ambient nitrite is taken up across the gills to be distributed via the blood to the tissues, particularly the heart, where it assists in cytoprotection and other functions. Cardiac nitrite was not elevated in acutely exposed fish, revealing that the response requires time. NO metabolite levels were higher during acute than chronic exposures, possibly caused by increased swimming activity and stress in acutely exposed fish.

  3. Glial Hsp70 Protects K+ Homeostasis in the Drosophila Brain during Repetitive Anoxic Depolarization

    Science.gov (United States)

    Armstrong, Gary A. B.; Xiao, Chengfeng; Krill, Jennifer L.; Seroude, Laurent; Dawson-Scully, Ken; Robertson, R. Meldrum

    2011-01-01

    Neural tissue is particularly vulnerable to metabolic stress and loss of ion homeostasis. Repetitive stress generally leads to more permanent dysfunction but the mechanisms underlying this progression are poorly understood. We investigated the effects of energetic compromise in Drosophila by targeting the Na+/K+-ATPase. Acute ouabain treatment of intact flies resulted in subsequent repetitive comas that led to death and were associated with transient loss of K+ homeostasis in the brain. Heat shock pre-conditioned flies were resistant to ouabain treatment. To control the timing of repeated loss of ion homeostasis we subjected flies to repetitive anoxia while recording extracellular [K+] in the brain. We show that targeted expression of the chaperone protein Hsp70 in glial cells delays a permanent loss of ion homeostasis associated with repetitive anoxic stress and suggest that this is a useful model for investigating molecular mechanisms of neuroprotection. PMID:22174942

  4. Glial Hsp70 protects K+ homeostasis in the Drosophila brain during repetitive anoxic depolarization.

    Directory of Open Access Journals (Sweden)

    Gary A B Armstrong

    Full Text Available Neural tissue is particularly vulnerable to metabolic stress and loss of ion homeostasis. Repetitive stress generally leads to more permanent dysfunction but the mechanisms underlying this progression are poorly understood. We investigated the effects of energetic compromise in Drosophila by targeting the Na(+/K(+-ATPase. Acute ouabain treatment of intact flies resulted in subsequent repetitive comas that led to death and were associated with transient loss of K(+ homeostasis in the brain. Heat shock pre-conditioned flies were resistant to ouabain treatment. To control the timing of repeated loss of ion homeostasis we subjected flies to repetitive anoxia while recording extracellular [K(+] in the brain. We show that targeted expression of the chaperone protein Hsp70 in glial cells delays a permanent loss of ion homeostasis associated with repetitive anoxic stress and suggest that this is a useful model for investigating molecular mechanisms of neuroprotection.

  5. Permian-Triassic boundary interval as a model for forcing marine ecosystem collapse by long-term atmospheric oxygen drop

    Science.gov (United States)

    Weidlich, O.; Kiessling, W.; Flügel, E.

    2003-11-01

    Ecological traits of reefs across the Permian-Triassic boundary interval coincide with a modeled decline of atmospheric oxygen throughout the Permian Period. Selective extinction and recovery patterns within the reef system are observed both at the end of the middle Permian (end-Guadalupian) and at the Permian-Triassic boundary. The end-Guadalupian event selectively affected corals and broke down the cool-water carbonate factory. Sponges, however, were largely unaffected and bloomed in reefs toward the end of the Permian. The end-Permian total destruction of the metazoan reef system only left behind poorly diverse microbial communities. The temporal reef patterns are thus similar to spatial patterns of modern benthic communities approaching oxygen minimum zones. This observation suggests that a decline in oxygen concentrations was at least partly involved in the destruction of reefs, even where there is no direct evidence of oceanic anoxia.

  6. Effects of fish farm waste on Posidonia oceanica meadows: Synthesis and provision of monitoring and management tools

    International Nuclear Information System (INIS)

    This paper provides a synthesis of the EU project MedVeg addressing the fate of nutrients released from fish farming in the Mediterranean with particular focus on the endemic seagrass Posidonia oceanica habitat. The objectives were to identify the main drivers of seagrass decline linked to fish farming and to provide sensitive indicators of environmental change, which can be used for monitoring purposes. The sedimentation of waste particles in the farm vicinities emerges as the main driver of benthic deterioration, such as accumulation of organic matter, sediment anoxia as well as seagrass decline. The effects of fish farming on P. oceanica meadows are diverse and complex and detected through various metrics and indicators. A safety distance of 400 m is suggested for management of P. oceanica near fish farms followed by establishment of permanent seagrass plots revisited annually for monitoring the health of the meadows

  7. High sensitivity of Lobelia dortmanna to sediment oxygen depletion following organic enrichment

    DEFF Research Database (Denmark)

    Møller, Claus Lindskov; Jensen, Kaj Sand

    2011-01-01

    • Lobelia dortmanna thrives in oligotrophic, softwater lakes thanks to O(2) and CO(2) exchange across roots and uptake of sediment nutrients. We hypothesize that low gas permeability of leaves constrains Lobelia to pristine habitats because plants go anoxic in the dark if O(2) vanishes from...... sediments. • We added organic matter to sediments and followed O(2) dynamics in plants and sediments using microelectrodes. To investigate plant stress, nutrient content and photosynthetic capacity of leaves were measured. • Small additions of organic matter triggered O(2) depletion and accumulation of NH(4...... thresholds for cell function in enriched sediments and was accompanied by critically low chlorophyll and photosynthesis. • We propose that anoxic stress restricts ATP formation and constrains transfer of nutrients to leaves. Brief anoxia in sediments and leaf lacunae late at night is a recurring summer...

  8. Respiratory allocation and standard rate of metabolism in the African lungfish, Protopterus aethiopicus.

    Science.gov (United States)

    Seifert, Ashley W; Chapman, Lauren J

    2006-01-01

    This paper quantifies the relationship between respiratory allocation (air vs. water) and the standard rate of metabolism (SMR) in the primitive air-breathing lungfish, Protopterus aethiopicus. Simultaneous measurements of oxygen consumed from both air and water were made to determine the SMR at ecologically relevant aquatic oxygen levels for juveniles 2 to 221 g. Total metabolic rate was positively correlated with body mass with a scaling exponent of 0.78. Aerial oxygen consumption averaged 98% (range=94% to 100%) of total respiratory allocation under low aquatic oxygen levels. Measurements of oxygen consumption made across a gradient of dissolved oxygen from normoxia to anoxia showed that P. aethiopicus maintains its SMR despite a change in respiratory allocation between water and air. PMID:16380279

  9. Heterologous expression and purification of membrane-bound pyrophosphatases

    DEFF Research Database (Denmark)

    Kellosalo, J.; Kajander, T.; Palmgren, Michael Broberg;

    2011-01-01

    to obtain structural information for drug design. We have tested the expression of eight integral membrane pyrophosphatases in Saccharomyces cerevisiae, six from bacterial and archaeal sources and two from protozoa. Two proteins originating from hyperthermophilic organisms were purified in dimeric......Membrane-bound pyrophosphatases (M-PPases) are enzymes that couple the hydrolysis of inorganic pyrophosphate to pumping of protons or sodium ions. In plants and bacteria they are important for relieving stress caused by low energy levels during anoxia, drought, nutrient deficiency, cold and low...... light intensity. While they are completely absent in mammalians, they are key players in the survival of disease-causing protozoans making these proteins attractive pharmacological targets. In this work, we aimed at the purification of M-PPases in amounts suitable for crystallization as a first step...

  10. Effect of a Jurassic oceanic anoxic event on belemnite ecology and evolution

    DEFF Research Database (Denmark)

    Ullmann, Clemens Vinzenz; Thibault, Nicolas Rudolph; Ruhl, Micha;

    2014-01-01

    The Toarcian oceanic anoxic event (T-OAE; ∼183 million y ago) is possibly the most extreme episode of widespread ocean oxygen deficiency in the Phanerozoic, coinciding with rapid atmospheric pCO2 increase and significant loss of biodiversity in marine faunas. The event is a unique past tipping...... point in the Earth system, where rapid and massive release of isotopically light carbon led to a major perturbation in the global carbon cycle as recorded in organic and inorganic C isotope records. Modern marine ecosystems are projected to experience major loss in biodiversity in response to enhanced...... to environmental change by shifting their habitat from cold bottom waters to warm surface waters in response to expanded seafloor anoxia....

  11. Bacterial Modulation of Plant Ethylene Levels.

    Science.gov (United States)

    Gamalero, Elisa; Glick, Bernard R

    2015-09-01

    A focus on the mechanisms by which ACC deaminase-containing bacteria facilitate plant growth.Bacteria that produce the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, when present either on the surface of plant roots (rhizospheric) or within plant tissues (endophytic), play an active role in modulating ethylene levels in plants. This enzyme activity facilitates plant growth especially in the presence of various environmental stresses. Thus, plant growth-promoting bacteria that express ACC deaminase activity protect plants from growth inhibition by flooding and anoxia, drought, high salt, the presence of fungal and bacterial pathogens, nematodes, and the presence of metals and organic contaminants. Bacteria that express ACC deaminase activity also decrease the rate of flower wilting, promote the rooting of cuttings, and facilitate the nodulation of legumes. Here, the mechanisms behind bacterial ACC deaminase facilitation of plant growth and development are discussed, and numerous examples of the use of bacteria with this activity are summarized. PMID:25897004

  12. Evolutionary patterns of Productida (Brachiopoda) morphology during the Permian in South China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The evolutionary patterns of Productida (brachiopod) morphology throughout the Permian show that while the percentage proportion of Productida (brachiopod) with strongly concentric and radial ornamentation declined from the Cisuralian to the Guadalupian, and then increased towards the Changhsingian via Wuchiapingian, the percentage proportion of Productida (brachiopod) with fine concentric and radial ornamentation distinctly increased from the Cisuralian to the Guadalupian, slightly declined towards the Wuchiapingian, and then increased towards the Changhsingian. From the Cisuralian to the Changhsingian, the percentage proportion of brachiopods with spinose ornamentation shows a persistent declining trend. The shell size generally indicates a miniaturization trend at species level during the Wuchiapingian to Changhsingian (including the transitional bed). These evolutionary patterns of brachiopod ornamentation and size are possibly related to the anoxia, food shortage, sea-level fluctuation, and change of substrate in the Permian (including the Permian-Triassic transitional interval) in South China.

  13. Investigating the link between fermentative metabolism and hydrogen production in the unicellular green alga Chlamydomonas reinhardtii

    Energy Technology Data Exchange (ETDEWEB)

    Burgess, S.J.; Nixon, P.J. [Imperial College London (United Kingdom)

    2010-07-01

    In the model green alga Chlamydomonas reinhardtii, the electrons required for hydrogen production can come from both the biophotolysis of water and from the fermentation of carbohydrate reserves. Anoxia leads to the activation of several fermentative pathways, which produce a number of end products including formic, malic and acetic acid along with ethanol, carbon dioxide and hydrogen. It has been proposed that by switching off competing fermentative pathways hydrogen production can be increased. Therefore the aim of this study was to devise an experimental strategy to down-regulate the expression of enzymes thought to control C. reinhardtii's fermentative metabolism. We demonstrate here that it is possible to use artificial microRNA (amiRNA) technology to generate knock-down mutants with reduced expression of pyruvate formate lyase (PFL1), a key fermentative enzyme in C. reinhardtii. This work opens up new possibilities to improve hydrogen yields through metabolic engineering. (orig.)

  14. Heat stress of two tropical seagrass species during low tides - impact on underwater net photosynthesis, dark respiration and diel in situ internal aeration.

    Science.gov (United States)

    Pedersen, Ole; Colmer, Timothy D; Borum, Jens; Zavala-Perez, Andrea; Kendrick, Gary A

    2016-06-01

    Seagrasses grow submerged in aerated seawater but often in low O2 sediments. Elevated temperatures and low O2 are stress factors. Internal aeration was measured in two tropical seagrasses, Thalassia hemprichii and Enhalus acoroides, growing with extreme tides and diel temperature amplitudes. Temperature effects on net photosynthesis (PN ) and dark respiration (RD ) of leaves were evaluated. Daytime low tide was characterized by high pO2 (54 kPa), pH (8.8) and temperature (38°C) in shallow pools. As PN was maximum at 33°C (9.1 and 7.2 μmol O2  m(-2) s(-1) in T. hemprichii and E. acoroides, respectively), the high temperatures and reduced CO2 would have diminished PN , whereas RD increased (Q10 of 2.0-2.7) above that at 33°C (0.45 and 0.33 μmol O2  m(-2)  s(-1) , respectively). During night-time low tides, O2 declined resulting in shoot base anoxia in both species, but incoming water containing c. 20 kPa O2 relieved the anoxia. Shoots exposed to 40°C for 4 h showed recovery of PN and RD , whereas 45°C resulted in leaf damage. These seagrasses are 'living near the edge', tolerant of current diel O2 and temperature extremes, but if temperatures rise both species may be threatened in this habitat. PMID:26914396

  15. Artificially induced migration of redox layers in a coastal sediment from the Northern Adriatic

    Directory of Open Access Journals (Sweden)

    E. Metzger

    2013-07-01

    Full Text Available Long term experimental studies suggest that, under anoxic transient conditions, redox fronts within the sediment shift upwards causing sequential rise and fall of benthic fluxes of reduced species (Mn(II, Fe(II than S(−II. Infaunal benthic organisms are associated to different redox fronts as micro-habitats and must be affected by such changes during natural hypoxia events. In order to document geochemical evolution of the sediment during prolonged anoxia in a realistic system, benthic chambers were deployed on the seafloor of the Northern Adriatic and sampled after 9, 30 and 315 days of incubation. Oxygen and sulfide were measured continuously in the early stages of the experiment (during 9 days. High-resolution porewater profiles were sampled by DET probes and redox sensitive species were analysed (alkalinity, SO42–, Mn2+, Fe2+. After 7 days, anoxia was reached within the chambers. Mn and Fe started diffusing towards the water column giving a rusty color to the seafloor. Infaunal species appeared at the surface. After 20 days, all macro-organisms were dead. Macro-organisms decomposition laying on the seafloor generated important production of sulfides within the chamber generating a downward flux of sulfide towards the sediment where sulfides were quickly oxidized by metallic oxides or precipitated as FeS. Sulfide was no more detectable in the water column and porewaters at the end of the experiment. Therefore, our results suggest that sulfide enrichment in the water column in coastal systems is strongly controlled by the biomass of benthic macrofauna and its decay during hypoxia while its residence time in water column is controlled by iron content (as solid oxides or as dissolved reduced cation within the sediment, even without water circulation.

  16. Global climatic changes during the Devonian-Mississippian: Stable isotope biogeochemistry of brachiopods

    Science.gov (United States)

    Brand, Uwe

    1989-12-01

    A progressive trend towards heavier δ 13C values of Devonian-Mississippian brachiopods from North America, Europe, Afghanistan and Algeria probably reflects expansion of the terrestrestrial and/or marine biomass and/or burial of carbon in soils/sediments. Oceanic Productivity crises, based on perturbations in the overall δ 13C trend, are recognized for the Mid Givetian, Early Famennian, Late Kinderhookian, Late Osagean and Early and Late Meramecian. The Givetian productivity crisis was probably accompanied by massive overturn of biologically toxic deep-ocean water. Temperature data, adjusted for the possible secular variation of seawater, support the hypothesis of global greenhouse conditions for the Devonian (mean of 30°C, mean of 26°C if extrinsic data are deleted) and icehouse conditions for the Mississippian (mean of 17°C). During the Mid Givetian, Frasnian and Early Famennian calculated water temperatures for tropical epeiric seas were generally above the thermal threshold limit (˜ 38°C) of most marine invertebrates or epeiric seawater was characterized by unusually low salinities (˜ pp ppt) or a combination of the two. These elevated water temperatures and/or low salinities, in conjunction with the postulated productivity crises and overturning of toxic deep waters are considered prime causes for the biotic crisis of the Late Devonian. In addition, a presumed expanding oxygen-minimum zone and general anoxia in the oceans prevented shallow-water organisms from escaping these inhospitable conditions. Re-population of the tropical seas occurred, after either water temperatures had dropped below the thermal threshold limit and/or salinities were back to normal, and oceanic productivity had increased due to more vigorous oceanic circulation, sometime during the Mid-Late Famennian. Migration of eurythermal, shallow- and deeper-water organisms into the vacant niches of the shallow seas was possible because of, generally, slightly lower sea levels, but, more

  17. Source of arsenic-bearing pyrite in southwestern Vermont, USA: Sulfur isotope evidence

    International Nuclear Information System (INIS)

    Arsenic-bearing pyrite is the source of arsenic in groundwater produced in late Cambrian and Ordovician gray and black slates and phyllites in the Taconic region of southwestern Vermont, USA. The aim of this study is to analyze the sulfur isotopic composition of this pyrite and determine if a relationship exists between pyrite δ34S and arsenic content. Pyrite occurs in both sedimentary/diagenetic (bedding-parallel layers and framboids) and low-grade metamorphic (porphyroblast) forms, and contains up to > 2000 ppm As. The sulfur isotopic composition of arsenic-bearing pyrite ranges from − 5.2‰ to 63‰. In the marine environment, the sulfur in sedimentary pyrite becomes increasingly enriched in 34S as the geochemical environment becomes increasingly anoxic. There is a positive correlation between δ34S and arsenic content in the Taconic pyrite, suggesting that uptake of arsenic by pyrite increased as the environment became more reducing. This increased anoxia may have been due to a rise in sea level and/or tectonic activity during the late Cambrian and Ordovician. Low-grade metamorphism appears to have little effect on sulfur isotope composition, but does correlate with lower arsenic content in pyrite. New groundwater wells drilled in this region should therefore avoid gray and black slates and phyllites that contain sedimentary/diagenetic pyrite with heavy δ34S values. - Highlights: • Pyrite is the source of arsenic in groundwater in the Taconic region of Vermont, USA. • As-bearing pyrite δ34S = – 5.2 to 63‰ with higher 34S as environment becomes more anoxic. • High sea level, tectonic activity create anoxia, with incorporation of As into pyrite. • New wells should avoid slate/phyllite containing sedimentary pyrite with heavy δ34S

  18. Photoassimilate-transport characteristics of nonchlorophyllous and green tissue in variegated leaves of Coleus blumei Benth.

    Science.gov (United States)

    Weisberg, L A; Wimmers, L E; Turgeon, R

    1988-07-01

    The nonchlorophyllous (albino) tissue of mature C. blumei leaves is a sink for photoassimilate. Transport from the green to the albino region of the same leaf was inhibited by cold and anoxia. When the green tissue of mature leaves was removed, the remaining albino portion imported labeled translocate from other mature leaves in the phloem. Photoassimilate unloading in the albino region of mature leaves was studied by quantitative autoradiography. The unloading was inhibited by cold but not by anoxia. No labeled photoassimilate could be detected in the free space of mature albino tissue by compartmental efflux analysis as phloem unloading proceeded in a N2 atmosphere, indicating that unloading, may occur by a symplastic pathway as it apparently does in sink leaves of other species. The minor veins of mature albino leaf tissue did not accumulate exogenous [(14)C]sucrose. Minor veins of green tissue in the same leaves accumulated [(14)C]sucrose but, in contrast to other species studied to date, this accumulation was insensitive to the inhibitor p-chloromercuribenzensulfonic acid (PCMBS).In its capacity to import and unload photoassimilate, and in the inability, of the minor veins to accumulate exogenous sucrose, the albino region of the mature C. blumei lamina differs from mature albino tobacco leaves and darkened mature leaves of other species. This, together with evidence indicating that phloem loading in C. blumei and other species may occur by different routes and with different sensitivity to PCMBS, indicates that the mechanism of transfer of photoassimilates between veins and surrounding tissues, and the mechanism of the sink-source transition, may not be the same in the leaves of all species. It is speculated that the unusual properties of the C. blumei leaf may be a consequence of the presence, in the minor veins, of "intermediary cells", large companion cells connected to the bundle sheath by abundant plasmodesmata. PMID:24221622

  19. Carbon isotope evidence for a vigorous biological pump in the wake of end-Permian mass extinction

    Science.gov (United States)

    Meyer, K. M.; Yu, M.; Jost, A. B.; Payne, J.

    2009-12-01

    Ocean anoxia and euxinia have long been linked to the end-Permian mass extinction and the subsequent Early Triassic interval of delayed biotic recovery. This anoxic, sulfidic episode has been ascribed to both low- and high-productivity states in the marine water column, leaving the causes of euxinia and the mechanisms underlying delayed recovery poorly understood. To examine the nature of the end-Permian and Early Triassic biological production, we measured the carbon isotopic composition of carbonates from an exceptionally preserved carbonate platform in the Nanpanjiang Basin of south China. 13C of limestones from 5 stratigraphic sections displays a gradient of approximately 4‰ from shallow to deep water within the Lower Triassic. The limestones are systematically enriched in the platform interior relative to coeval slope and basin margin deposits by 2-4‰ at the peaks of correlative positive and negative δ13C excursions. This gradient subsequently collapses to less than 1‰ in the Middle Triassic, coincident with accelerated biotic recovery and cessation of δ13C excursions. Based on the relationship between δ18O and δ13C, trace metal analyses, and lithostratigraphic context, we conclude that the carbon isotope gradient is unlikely to reflect meteoric diagenesis, organic matter remineralization, or changes in the mixing ratio of sediment sources and minerals across the platform. Instead, we interpret the relatively depleted δ13C values toward the basin as reflecting DIC input from 13C-depleted deep waters during early diagenesis in a nutrient-rich, euxinic ocean. These observations suggest that a vigorous prokaryote-driven biological pump sustained Early Triassic ocean anoxia and inhibited recovery of animal ecosystems.

  20. Marine Carbonate δ53Cr Values Reflect Inputs From LIP Volcanism During OAE 2

    Science.gov (United States)

    Holmden, C. E.; Jacobson, A. D.; Sageman, B. B.; Hurtgen, M.

    2014-12-01

    Cr stable isotopes record mass dependent fractionations that reflect changes in the element's oxidation state. Weathering of igneous rocks on the continents releases Cr(III), which then reacts with manganese dioxide minerals to form Cr(VI) under oxidizing conditions. Cr(VI) is both soluble and mobile in continental weathering environments and eventually accumulates in the oceans. Laboratory experiments show that reduction of Cr(VI) causes light Cr isotopes to partition into the reduced Cr(III), which is insoluble, thus leaving the unreacted pool of soluble Cr(VI) enriched in the heavy isotopes. As Cr(VI) is the thermodynamically favoured species in oxygenated seawater, this leads to the hypothesis that drawdown of seawater Cr(VI) during ocean anoxic events should correlate with positive shifts in seawater derived Cr isotope values in marine sedimentary successions, if the fractionation factor and the various Cr input fluxes remained constant. To test this hypothesis, we measured seawater δ53Cr values preserved in pelagic carbonate sediment deposited in the Western Interior Seaway during OAE 2. Our results show that the onset of ocean anoxia correlates with a decrease in sedimentary δ53Cr, which is opposite to the model prediction. The discrepancy may be reconciled if the sedimentation flux of light Cr isotopes into anoxic sediment was offset by an increase in the input flux of light Cr isotopes to the oceans. Eruption and weathering of the Caribbean Large Igneous Province (LIP) provides one such source.. Other studies have implicated LIP volcanism as a source of anomalously high trace metal abundances in the studied carbonates, as well as mantle-like initial Os isotope ratios in related black shales. We conclude similarly that the increased input of light Cr isotopes to the oceans during OAE 2 masked the expected isotopic response of the ocean Cr cycle to increased ocean anoxia.

  1. Cr Isotope Response to Ocean Anoxic Event 2

    Science.gov (United States)

    Holmden, C. E.; Jacobson, A. D.; Sageman, B. B.; Hurtgen, M.

    2015-12-01

    The element Cr offers a redox sensitive isotopic proxy with potential for tracing past oxygen levels in the oceans. We examine this potential in a marine carbonate section deposited during Cretaceous Ocean Anoxic Event 2 (OAE 2) in the Western Interior Seaway, Colorado. Redox changes are the main source of Cr isotope fractionation in Earth surface environments. Cr(VI), in the form of the chromate oxyanion, is the thermodynamically favoured species in oxygenated seawater. Reduction of Cr(VI) causes light isotopes to partition into Cr(III), which is reactive and susceptible to removal into marine sediment. Therefore, widespread ocean anoxia should correlate with positive shifts in seawater chromate Cr isotope values (δ53Cr), assuming that all Cr input fluxes remained constant during the event. We find instead that inferred seawater δ53Cr values decreased during OAE 2. The minima of the sedimentary δ53Cr excursion coincides with the peak interval of anomalously enriched concentrations of Cr and other trace metals of basaltic affinity attributed to eruption of the Caribbean Large Igneous Province (CLIP). We propose that an anoxic, hydrothermal plume enriched in Cr(III) with low δ53Cr values characteristic of igneous rocks moved from deep waters of the CLIP eruption site in the eastern Pacific into deep waters of the proto-North Atlantic through an oceanic gateway in the Central Americas. Once inside, metal-rich waters upwelled against the surrounding continental margins. CLIP volcanism delivered a submarine weathering flux of Cr to the oceans during OAE 2 that was large enough to mask the expected isotopic response of the ocean Cr cycle to increasing anoxia, particularly in the proto-North Atlantic Ocean.

  2. Oxygenation of Stratified Reservoir Using Air Bubble Plume

    Science.gov (United States)

    Schladow, S. G.

    2006-12-01

    Excess nutrients loading from urban area and watershed into lakes and reservoirs increases the content of organic matter, which, through decomposition, needs increased dissolve oxygen (DO). Many eutrophic reservoirs and lakes cannot meet the DO requirement during stratified season and suffers from the hypolimnetic anoxia. As a result, benthic sediment produces anoxic products such as methane, hydrogen sulphide, ammonia, iron, manganese, and phosphorus. In order to address the hypolimnetic anoxia, oxygen is artificially supplied into reservoir using an aeration system (i.e., bubbler). The most common result of lake/reservoir aeration is to destratify the reservoir so that the water body may completely mix under natural phenomena and remain well oxygenated throughout. Other advantages of destratification are: (1) allows warm- water fish to inhabit the entire reservoir, (2) suppress the nutrient release from sediment, and (3) decreases the algal growth by sending them to the darker zone. A one-dimensional reservoir-bubbler model is developed and applied to examine the effects of an aeration system on mixing and dissolved oxygen dynamics in the Upper Peirce Reservoir, Singapore. After introduction of the aeration system in the reservoir, it was found that the hypolimnetic DO increased significantly, and the concentration of algae, soluble manganese and iron substantially reduced. It is found that the reservoir-bubbler model predicts the mixing (temperature as mixing parameter) and dissolved oxygen concentration in the reservoir with acceptable accuracy. It is shown in terms of bubbler mechanical efficiency (i.e., operating cost) and total DO contribution from the aeration system into the reservoir that the selections of airflow rate per diffuser, air bubble radius, and total number of diffusers are important design criteria of a bubbler system. However, the overall bubbler design also depends on the reservoir size and stratified area of interest, ambient climate, and

  3. Fiddler crabs facilitate Spartina alterniflora growth, mitigating periwinkle overgrazing of marsh habitat.

    Science.gov (United States)

    Gittman, Rachel K; Keller, Danielle A

    2013-12-01

    Ecologists have long been interested in identifying and testing factors that drive top-down or bottom-up regulation of communities. Most studies have focused on factors that directly exert top-down (e.g., grazing) or bottom-up (e.g., nutrient availability) control on primary production. For example, recent studies in salt marshes have demonstrated that fronts of Littoraria irrorata periwinkles can overgraze Spartina alterniflora and convert marsh to mudflat. The importance of indirect, bottom-up effects, particularly facilitation, in enhancing primary production has also recently been explored. Previous field studies separately revealed that fiddler crabs, which burrow to depths of more than 30 cm, can oxygenate marsh sediments and redistribute nutrients, thereby relieving the stress of anoxia and enhancing S. alterniflora growth. However, to our knowledge, no studies to date have explored how nontrophic facilitators can mediate top-down effects (i.e., grazing) on primary-producer biomass. We conducted a field study testing whether fiddler crabs can facilitate S. alterniflora growth sufficiently to mitigate overgrazing by periwinkles and thus sustain S. alterniflora marsh. As inferred from contrasts to experimental plots lacking periwinkles and fiddler crabs, periwinkles alone exerted top-down control of total aboveground biomass and net growth of S. alterniflora. When fiddler crabs were included, they counteracted the effects of periwinkles on net S. alterniflora growth. Sediment oxygen levels were greater and S. alterniflora belowground biomass was lower where fiddler crabs were present, implying that fiddler crab burrowing enhanced S. alterniflora growth. Consequently, in the stressful interior S. alterniflora marsh, where subsurface soil anoxia is widespread, fiddler crab facilitation can mitigate top-down control by periwinkles and can limit and possibly prevent loss of biogenically structured marsh habitat and its ecosystem services.

  4. The kinetics of denitrification in permeable sediments

    Science.gov (United States)

    Evrard, Victor; Glud, Ronnie N.; Cook, Perran L. M.

    2013-04-01

    Permeable sediments comprise the majority of shelf sediments, yet the rates of denitrification remain highly uncertain in these environments. Computational models are increasingly being used to understand the dynamics of denitrification in permeable sediments, which are complex environments to study experimentally. The realistic implementation of such models requires reliable experimentally derived data on the kinetics of denitrification. Here we undertook measurements of denitrification kinetics as a function of nitrate concentration and in the presence and absence of oxygen, in carefully controlled flow through reactor experiments on sediments taken from six shallow coastal sites in Port Phillip Bay, Victoria, Australia. The results showed that denitrification commenced rapidly (within 30 min) after the onset of anoxia and the kinetics could be well described by Michaelis-Menten kinetics with half saturation constants (apparent Km) ranging between 1.5 and 19.8 μM, and maximum denitrification rate (Vmax) were in the range of 0.9-7.5 nmol mL-1 h-1. The production of N2 through anaerobic ammonium oxidation (anammox) was generally found to be less than 10% that of denitrification. Vmax were in the same range as previously reported in cohesive sediments despite organic carbon contents one order of magnitude lower for the sediments studied here. The ratio of sediment O2 consumption to Vmax was in the range of 0.02-0.09, and was on average much lower than the theoretical ratio of 0.8. The most likely explanation for this is that the microbial community is not able to instantaneously shift or optimally use a particular electron acceptor in the highly dynamic redox environment experienced in permeable sediments. Consistent with this explanation, subsequent longer-term experiments over 5 days showed that denitrification rates increased by a factor of 10 within 3 days of the permanent onset of anoxia. In contrast to previous studies, we did not observe any significant

  5. Source of arsenic-bearing pyrite in southwestern Vermont, USA: Sulfur isotope evidence

    Energy Technology Data Exchange (ETDEWEB)

    Mango, Helen, E-mail: helen.mango@castleton.edu [Department of Natural Sciences, Castleton State College, 233 South Street, Castleton, VT 05735 (United States); Ryan, Peter, E-mail: pryan@middlebury.edu [Department of Geology, Middlebury College, 276 Bicentennial Way, Middlebury, VT 05753 (United States)

    2015-02-01

    Arsenic-bearing pyrite is the source of arsenic in groundwater produced in late Cambrian and Ordovician gray and black slates and phyllites in the Taconic region of southwestern Vermont, USA. The aim of this study is to analyze the sulfur isotopic composition of this pyrite and determine if a relationship exists between pyrite δ{sup 34}S and arsenic content. Pyrite occurs in both sedimentary/diagenetic (bedding-parallel layers and framboids) and low-grade metamorphic (porphyroblast) forms, and contains up to > 2000 ppm As. The sulfur isotopic composition of arsenic-bearing pyrite ranges from − 5.2‰ to 63‰. In the marine environment, the sulfur in sedimentary pyrite becomes increasingly enriched in {sup 34}S as the geochemical environment becomes increasingly anoxic. There is a positive correlation between δ{sup 34}S and arsenic content in the Taconic pyrite, suggesting that uptake of arsenic by pyrite increased as the environment became more reducing. This increased anoxia may have been due to a rise in sea level and/or tectonic activity during the late Cambrian and Ordovician. Low-grade metamorphism appears to have little effect on sulfur isotope composition, but does correlate with lower arsenic content in pyrite. New groundwater wells drilled in this region should therefore avoid gray and black slates and phyllites that contain sedimentary/diagenetic pyrite with heavy δ{sup 34}S values. - Highlights: • Pyrite is the source of arsenic in groundwater in the Taconic region of Vermont, USA. • As-bearing pyrite δ{sup 34}S = – 5.2 to 63‰ with higher {sup 34}S as environment becomes more anoxic. • High sea level, tectonic activity create anoxia, with incorporation of As into pyrite. • New wells should avoid slate/phyllite containing sedimentary pyrite with heavy δ{sup 34}S.

  6. Metabolic signaling between photoreceptors and glial cells in the retina of the drone (Apis mellifera).

    Science.gov (United States)

    Brazitikos, P D; Tsacopoulos, M

    1991-12-13

    Experimental evidence showing metabolic interaction and signaling between photoreceptors-neurons and glial cells of the honeybee drone retina is presented. In this tissue [3H]2-deoxyglucose ([3H]2DG) in the dark and during repetitive light stimulation is phosphorylated to [3H]2-deoxyglucose-6P ([3H]2DG-6P) almost exclusively in the glial cells. Hence, stimulus-induced changes in the rate of formation of [3H]2DG-6P occurs predominantly in the glial cells. Repetitive stimulation of the photoreceptors with light flashes induced about a 47% rise in the rate of formation of [3H]2DG-6P in the glial cells and this effect is probably due to the activation of hexokinase. The potent inhibitor of glycolysis iodoacetic acid (IAA), inhibited this phosphorylation by about 75%. Probably this was largely due to an about 70% decrease of adenosine triphosphate (ATP). Exposure of the retina to IAA suppressed the transient rise in oxygen consumption (delta QO2) in the photoreceptors and subsequently the light-induced receptor potential. This indicates that the supply of a glycolytic substrate by glial cells to the photoreceptors is greatly reduced by IAA. Anoxia, by rapidly suppressing QO2, abolished the receptor potential of the photoreceptors and caused a rapid drop of about 50% in the ATP content of the retina. At the same time the formation of [3H]2DG-6P was inhibited by about 30%. This indicates that respiring photoreceptors send a metabolic signal to glial cells which is suppressed by anoxia. PMID:1815828

  7. Do High-elevation Lakes Record Variations in Snowfall and Atmospheric Rivers in the Sierra Nevada of California?

    Science.gov (United States)

    Ashford, J.; Sickman, J. O.; Lucero, D. M.

    2014-12-01

    Understanding the underlying causes of interannual variation in snowfall and extreme hydrologic events in the Sierra Nevada is hampered by short instrumental records and the difficulties in reconstructing climate using a traditional paleo-record such as tree-rings. New paleo proxies are needed to provide a record of snowpack water content and extreme precipitation events over millennial timescales which can be used to test hypotheses regarding teleconnections between Pacific climate variability and water supply and flood risk in California. In October 2013 we collected sediment cores from Pear Lake (z = 27 m), an alpine lake in Sequoia National Park. The cores were split and characterized by P-wave velocity, magnetic susceptibility and density scanning. Radiocarbon dates indicate that the Pear Lake cores contain a 13.5K yr record of lake sediment. In contrast to other Sierra Nevada lakes previously cored by our group, high-resolution scanning revealed alternating light-dark bands (~1 mm to 5 mm thick) for most of the Pear Lake core length. This pattern was interrupted at intervals by homogenous clasts (up to 75 mm thick) ranging in grain size from sand to gravel up to 1 cm diameter. We hypothesize that the light-dark banding results from the breakdown of persistent hypolimnetic anoxia during spring snowmelt and autumn overturn. We speculate that the thicknesses of the dark bands are controlled by the duration of anoxia which in turn is controlled by the volume and duration of snowmelt. The sand to gravel sized clasts are most likely associated with extreme precipitation events resulting from atmospheric rivers intersecting the southern Sierra Nevada. We hypothesize that centimeter-sized clasts are deposited in large avalanches and that the sands are deposited in large rain events outside of the snow-cover period.

  8. Low probability of initiating nirS transcription explains observed gas kinetics and growth of bacteria switching from aerobic respiration to denitrification.

    Directory of Open Access Journals (Sweden)

    Junaid Hassan

    2014-11-01

    Full Text Available In response to impending anoxic conditions, denitrifying bacteria sustain respiratory metabolism by producing enzymes for reducing nitrogen oxyanions/-oxides (NOx to N2 (denitrification. Since denitrifying bacteria are non-fermentative, the initial production of denitrification proteome depends on energy from aerobic respiration. Thus, if a cell fails to synthesise a minimum of denitrification proteome before O2 is completely exhausted, it will be unable to produce it later due to energy-limitation. Such entrapment in anoxia is recently claimed to be a major phenomenon in batch cultures of the model organism Paracoccus denitrificans on the basis of measured e(--flow rates to O2 and NOx. Here we constructed a dynamic model and explicitly simulated actual kinetics of recruitment of the cells to denitrification to directly and more accurately estimate the recruited fraction (Fden. Transcription of nirS is pivotal for denitrification, for it triggers a cascade of events leading to the synthesis of a full-fledged denitrification proteome. The model is based on the hypothesis that nirS has a low probability (rden, h(-1 of initial transcription, but once initiated, the transcription is greatly enhanced through positive feedback by NO, resulting in the recruitment of the transcribing cell to denitrification. We assume that the recruitment is initiated as [O2] falls below a critical threshold and terminates (assuming energy-limitation as [O2] exhausts. With rden = 0.005 h(-1, the model robustly simulates observed denitrification kinetics for a range of culture conditions. The resulting Fden (fraction of the cells recruited to denitrification falls within 0.038-0.161. In contrast, if the recruitment of the entire population is assumed, the simulated denitrification kinetics deviate grossly from those observed. The phenomenon can be understood as a 'bet-hedging strategy': switching to denitrification is a gain if anoxic spell lasts long but is a waste

  9. Induction of ischemic tolerance in rat liver via reduced nicotinamide adenine dinucleotide phosphate oxidase in Kupffer cells

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    AIM: To elucidate the mechanisms of hepatocyte preconditioning by H2O2 to better understand the pathophysiology of ischemic preconditioning.METHODS: The in vitro effect of H2O2 pretreatment was investigated in rat isolated hepatocytes subjected to anoxia/reoxygenation. Cell viability was assessed with propidium iodide fluorometry. In other experiments, rat livers were excised and subjected to warm ischemia/reperfusion in an isolated perfused liver system to determine leakage of liver enzymes. Preconditioning was performed by H2O2 perfusion, or by stopping the perfusion for 10 min followed by 10 min of reperfusion.To inhibit Kupffer cell function or reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase,gadolinium chloride was injected prior to liver excision, or diphenyleneiodonium, an inhibitor of NADPH oxidase, was added to the perfusate, respectively. Histological detection of o~gen radical formation in Kupffer cells was performed by perfusion with nitro blue tetrazolium.RESULTS: Anoxia/reoxygenation decreased hepatocyte viability compared to the controls. Pretreatment with H2O2 did not improve such hepatocyte injury. In liver perfusion experiments, however, H2O2 preconditioning reduced warm ischemia/reperfusion injury, which was reversed by inhibition of Kupffer cell function or NADPH oxidase. Histological examination revealed that H2O2 preconditioning induced oxygen radical formation in Kupffer cells. NADPH oxidase inhibition also reversed hepatoprotection by ischemic preconditioning.CONCLUSION: H2O2 preconditioning protects hepatocytes against warm ischemia/reperfusion injury via NADPH oxidase in Kupffer cells, and not directly. NADPH oxidase also mediates hepatoprotection by ischemic preconditioning.

  10. Differential contribution of key metabolic substrates and cellular oxygen in HIF signalling

    Energy Technology Data Exchange (ETDEWEB)

    Zhdanov, Alexander V., E-mail: a.zhdanov@ucc.ie [School of Biochemistry and Cell Biology, University College Cork, Cavanagh Pharmacy Building, College Road, Cork (Ireland); Waters, Alicia H.C. [School of Biochemistry and Cell Biology, University College Cork, Cavanagh Pharmacy Building, College Road, Cork (Ireland); Golubeva, Anna V. [Alimentary Pharmabiotic Centre, University College Cork, Bioscience Institute, Western Road, Cork (Ireland); Papkovsky, Dmitri B. [School of Biochemistry and Cell Biology, University College Cork, Cavanagh Pharmacy Building, College Road, Cork (Ireland)

    2015-01-01

    Changes in availability and utilisation of O{sub 2} and metabolic substrates are common in ischemia and cancer. We examined effects of substrate deprivation on HIF signalling in PC12 cells exposed to different atmospheric O{sub 2}. Upon 2–4 h moderate hypoxia, HIF-α protein levels were dictated by the availability of glutamine and glucose, essential for deep cell deoxygenation and glycolytic ATP flux. Nuclear accumulation of HIF-1α dramatically decreased upon inhibition of glutaminolysis or glutamine deprivation. Elevation of HIF-2α levels was transcription-independent and associated with the activation of Akt and Erk1/2. Upon 2 h anoxia, HIF-2α levels strongly correlated with cellular ATP, produced exclusively via glycolysis. Without glucose, HIF signalling was suppressed, giving way to other regulators of cell adaptation to energy crisis, e.g. AMPK. Consequently, viability of cells deprived of O{sub 2} and glucose decreased upon inhibition of AMPK with dorsomorphin. The capacity of cells to accumulate HIF-2α decreased after 24 h glucose deprivation. This effect, associated with increased AMPKα phosphorylation, was sensitive to dorsomorphin. In chronically hypoxic cells, glutamine played no major role in HIF-2α accumulation, which became mainly glucose-dependent. Overall, the availability of O{sub 2} and metabolic substrates intricately regulates HIF signalling by affecting cell oxygenation, ATP levels and pathways involved in production of HIF-α. - Highlights: • Gln and Glc regulate HIF levels in hypoxic cells by maintaining low O{sub 2} and high ATP. • HIF-α levels under anoxia correlate with cellular ATP and critically depend on Glc. • Gln and Glc modulate activity of Akt, Erk and AMPK, regulating HIF production. • HIF signalling is differentially inhibited by prolonged Glc and Gln deprivation. • Unlike Glc, Gln plays no major role in HIF signalling in chronically hypoxic cells.

  11. Gene expression and physiological changes of different populations of the long-lived bivalve Arctica islandica under low oxygen conditions.

    Directory of Open Access Journals (Sweden)

    Eva E R Philipp

    Full Text Available The bivalve Arctica islandica is extremely long lived (>400 years and can tolerate long periods of hypoxia and anoxia. European populations differ in maximum life spans (MLSP from 40 years in the Baltic to >400 years around Iceland. Characteristic behavior of A. islandica involves phases of metabolic rate depression (MRD during which the animals burry into the sediment for several days. During these phases the shell water oxygen concentrations reaches hypoxic to anoxic levels, which possibly support the long life span of some populations. We investigated gene regulation in A. islandica from a long-lived (MLSP 150 years German Bight population and the short-lived Baltic Sea population, experimentally exposed to different oxygen levels. A new A. islandica transcriptome enabled the identification of genes important during hypoxia/anoxia events and, more generally, gene mining for putative stress response and (anti- aging genes. Expression changes of a antioxidant defense: Catalase, Glutathione peroxidase, manganese and copper-zinc Superoxide dismutase; b oxygen sensing and general stress response: Hypoxia inducible factor alpha, Prolyl hydroxylase and Heat-shock protein 70; and c anaerobic capacity: Malate dehydrogenase and Octopine dehydrogenase, related transcripts were investigated. Exposed to low oxygen, German Bight individuals suppressed transcription of all investigated genes, whereas Baltic Sea bivalves enhanced gene transcription under anoxic incubation (0 kPa and, further, decreased these transcription levels again during 6 h of re-oxygenation. Hypoxic and anoxic exposure and subsequent re-oxygenation in Baltic Sea animals did not lead to increased protein oxidation or induction of apoptosis, emphasizing considerable hypoxia/re-oxygenation tolerance in this species. The data suggest that the energy saving effect of MRD may not be an attribute of Baltic Sea A. islandica chronically exposed to high environmental variability (oxygenation

  12. Effect of Shengdeye on anti-fatigue and the memory in mice

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    AIM: Shengdeye is a kind of medicinal wine. It is fermented with 30 kinds of medicinal herbs such as glossy ganoderma, pilose antler, panax, medlar and sorghum. This study aimed to observe the effects of Shengdeye on anti-fatigue and memory in mice.METHODS: The mice were fed with Shengdeye 5 ml*kg-1 and 2.5 ml*kg-1 2 times per day. After 7 days, the mice were examined on anoxia-resistant and swimming test for anti-fatigue and step down test for memory.RESULTS: The anoxia-resistant of shengdege group was apparently longer than that of the control group [(29.60±1.36) min vs (24.40±3.13) min, P<0.01], and the swimming time was sharply increased [(142.6±53.8) min for 2.5 ml*kg-1 and (162.9±43.5) min for 5 ml*kg-1 vs (94.9±39.1) min, P<0.05]. The error times of shengdege group was lower than that of the control [(1.5±1.4) times and (2.3±1.3) times vs (3.7±1.1) times, P<0.01]. The delitescence of two group were sharply prolonged [(136.8±50.1) s, and (128.0±41.5) s vs (50.2±42.9) s, P<0.01].CONCLUSION: The results indicated that Shengdeye had an anti-fatigne effect and increased the faculty of memory. The experiment of acute toxicity showed that the medicinal herbs in Shyengdeye were safe.

  13. Last interglacial East Mediterranean sapropels: Testing the freshwater hypothesis using coastal proxy records

    Science.gov (United States)

    Mauz, Barbara; Elmejdoub, Noureddine; Rogerson, Mike

    2016-04-01

    Current understanding of sapropel formation in the Eastern Mediterranean suggests a combination of anoxia and enhanced primary productivity. Enhanced anoxia is thought to have resulted from freshwater input into the Eastern Mediterranean most likely originating from the Nile and from wadis draining Saharan lakes. We investigated Mediterranean sediment sequences on the coasts of North Africa and Levant using conventional sedimentological and optical dating techniques in order to understand the coastal response to external forcing when sapropels S5, S4 and S3 formed at ~125 ka, ~105 ka and ~83 ka in various East Mediterranean sub-basins. The sediment sequences show sharp switches between siliciclastic and carbonate dominated nearshore environment where carbonate-rich sediments are composed of oolitic grainstones. The oolitic sediments represent a period of elevated annual sea-surface temperature and lack of fluvial discharge at ~113 ka on the Levant coast, at ~110 ka on the coast west of the Nile delta (El Asmar and Wood 2000) and at ~80 ka on the north Saharan coast. Both the timing and duration of the arid period are different on each coast owing to the interplay between local processes and external forcing. For the Levantine Sea these differences confirm the dominant role of the Nile discharge in generating conditions for sapropels to form. For the central east Mediterranean the differences indicate dominant external forcing after ~110 ka, exerted by the Atlantic meridional overturning circulation, because arid shorelines existed contemporaneously with the formation of S4 andS3. While it is hard to find the unequivocal evidence, we feel our data rule out a Saharan lakes source of freshwater for the central East Mediterranean Sea after ~110 ka and thereby implicitly, a spatial and temporal varying freshwater input.

  14. Effects of glyphosate-resistant transgenic soybean on physical enginery of male mice%抗草甘膦转基因大豆粕对雄鼠运动机能的影响

    Institute of Scientific and Technical Information of China (English)

    芦春斌; 林泽斌; 张雁; 陈博慧; 吴家乐; 刘标

    2016-01-01

    The effects of glyphosate-resistant transgenic soybean on physical enginery were evaluated in male Kun-ming mice after being fed for 30 d with glyphosate-resistant transgenic soybean and non-transgenic soybean , respec-tively.The locomotive ability , anti-fatigue and anti-anoxia ability were comparatively studied in both groups under normal physiological condition .The physical enginery was also tested in CP-induced pathological model of mice .Re-sults showed that there were no significant differences of locomotive ability , anti-fatigue and anti-anoxia ability in both animal groups under normal physiological condition .Furthermore, compared with animals fed with traditional soybean, no significant differences of locomotive ability , anti-fatigue and anti-anoxia ability were observed in CP-treated pathological model animals fed for 30 d with glyphosate-resistant transgenic soybean .In conclusion , there were no adverse toxicological effects of glyphosate-resistant transgenic soybean fed for 30 d on physical enginery in male mice.%在正常生理条件下,分别以抗草甘膦转基因大豆饲料和非转基因大豆饲料喂食雄性昆明小鼠,至30 d检测其运动能力、耐疲劳能力和耐缺氧能力,探讨抗草甘膦转基因大豆对雄鼠运动机能的影响。同时以环磷酰胺处理建立小鼠病理模型,探讨病理条件下抗草甘膦转基因大豆对雄鼠运动能力、耐疲劳能力和耐缺氧能力的作用。结果显示,在正常生理条件下,与非转基因对照组相比,喂食30 d抗草甘膦转基因大豆饲料组雄鼠的运动能力、耐疲劳能力和耐缺氧能力均无统计学差异( P>0.05);同样,在环磷酰胺诱导的病理条件下,喂食抗草甘膦转基因大豆饲料30 d也不会对雄鼠运动能力、耐疲劳能力和耐缺氧能力造成不良影响。结果表明,喂食抗草甘膦转基因大豆饲料30 d对雄鼠运动机能无毒性效应。

  15. Limnological characteristics and environmental effects of the Baihua Reservoir in Guizhou Plateau,China%贵州高原百花湖水库湖沼学变量特征及环境效应

    Institute of Scientific and Technical Information of China (English)

    夏品华; 李秋华; 林陶; 胡继伟

    2011-01-01

    In order to find out the limnological characteristics and the relationship with the paroxysmal deterioration of water quality in Baihua Reservior of Guizhou Province,China,hydrological and environmental factors were investigated from August 2008 to August 2009.From April to September,the thermal stratification was monomictic,leading to chemical stratification that affected the water quality.The mean concentrations of TN,TP,Chl.a and SD were 1.60 mg · L-1,0.067 mg · L-1,18.9 μg · L-1 and 1.4 m respectively,indicating that the reservoir was a meso-eutrophic system.Physical and chemical factors in the river zone were higher than those in the transitional and lacustrine zones.In the wet season(May to September),all nutrient concentrations were significantly higher than those in the other periods.It was confirmed that surface runoff was the main path for nutrient loading into the reservoir.The ratios of TN/TP were from 2 to 120 in Baihua Reservior,and the dissolved oxygen was between 0.3 to 8.0 mg · L-1,meaning that the reservoir was characterized by high concentrations of nitrogen and phosphorus limitation and by seasonal anoxia in hypolimnion.The high N/P ratio was attributed to the local soil containing rich iron.Water stratificaton was responsible for seasonal anoxia at the lake bottom,which was intensified by the water eutrophication.The paroxysmal deterioration of water quality was relevant to water stratification,eutrophication,and the gravitational instability of the thermal stratification caused by surface cooling of water when the air temperature decreased abruptly in early fall,leading to a mixing of the upper and lower layer water and anoxia in the whole water body.%为了揭示贵州高原百花湖水库湖沼学变量特征及其与突发性水质恶化的关系,对百花湖水库的水文、营养盐及相关理化因子进行了调查.结果表明:百花湖水库表层水温在10.2~27.0℃之间,4—9月形成分层,水体分层结构为单

  16. Hemorragia pulmonar masiva presentada como muerte súbita neonatal Massive pulmonary haemorrhage presented as sudden neonatal death

    Directory of Open Access Journals (Sweden)

    J. Blanco Pampín

    2003-04-01

    Full Text Available La hemorragia pulmonar masiva en los recién nacidos, es una patología grave con una elevada tasa de mortalidad. En el presente artículo, se describe el caso de una recién nacida que fallece súbitamente, tras un intervalo de vida de 4 días, sin signos patológicos ni manifestaciones clínicas previas. Durante el parto había sufrido una severa anoxia. Repentinamente, presenta un cuadro de disnea progresiva y hemoptisis. Tras varios intentos infructuosos de reanimación, fallece al cabo de una hora en el Servicio de Urgencias. La autopsia reveló fundamentalmente, la existencia de una hemorragia pulmonar masiva difusa. Macroscópicamente, el tamaño de los pulmones era normal, existiendo un incremento ponderal de los mismos y una consistencia carnosa con amplias e intensas áreas hemorrágicas. La tráquea y los bronquios principales se encontraban ocupados por sangre líquida. Microscópicamente, se apreciaron infiltrados hemorrágicos pulmonares intraalveolares e intersticiales, así como en el hígado y en ambos riñones. La investigación toxicológica fue negativa. No se observaron otras alteraciones patológicas. Teniendo en cuenta los datos de la historia clínica obstétrica y los hallazgos anatomopatológicos, se llegó a la conclusión de que el fallecimiento se produjo por un una hemorragia pulmonar masiva, relacionada con la anoxia desarrollada durante el trabajo de parto.Massive pulmonary haemorrhage in newborns is a catastrophic event with a high rate of mortality. A case of unexpected death in a four-day-old female newborn, who died after a period without previous pathological signs and clinical manifestations, is described. She had suffered severe asphyxia atbirth. Suddenly, she presented increasing dyspnea and haemoptysis. After an unsuccessful attempt at resuscitation, she died 1 hour after admission to the Emergency Department. At autopsy a massive and diffuse intrapulmonary haemorrhage was found. On gross examination the

  17. Biomarker characterization of the record of the OAE1a (early Aptian) in Betic and Cantabrian basins (Spain)-Sedimentary implications

    Science.gov (United States)

    Quijano, María. Luisa; Castro, José Manuel; Pancost, Richard D.; de Gea, Ginés. A.; Najarro, María.; Aguado, Roque; Rosales, Idoia; Martín-Chivelet, Javier

    2010-05-01

    Molecular analyses of sedimentary organic matter are powerful tools in assessing the origin of organic matter and its thermal maturity as well as constraining ancient environmental conditions, such as as marine productivity, anoxia in bottom waters or the photic zone and sea surface temperatures. This communication presents the study of four sections recording the OAE1a (early Aptian) in Spain, which are located in two broad basins respectively located in the South and the North of Iberia: the Southern Iberian Palaeomargin (Carbonero - CAB, La Frontera - XF and Cau - CAU sections) and the Cantabrian Basin (Puente Nansa - PN section). These sections represent depositional settings ranging from platform (CAU, PN) to pelagic environments (CAB, XF). C-isotope profiles and biostratigraphic data are used to define the interval corresponding to the OAE 1a. Here we focus on the biomarker composition of the organic-rich facies, and the integration of these data with the sedimentology, stratigraphy and paleogeography. The study has been based mainly upon the analysis of samples with Gas Chromatography-Mass Spectrometry (GCMS). Four main groups of compounds are present in all sections: n-alkanes, isoprenoids, hopanes and steranes. n-Alkanes and isoprenoids (pristane and phytane) are dominant in most samples. To facilitate interpretation of these distributions, we have calculated the TAR (terrestrial aquatic ratio derived from the ratio of long to short chain compounds) and also the OEP (odd over even predominance of n-alkanes). The ratio of pristane to phytane and various isoprenoid/n-alkanes ratios have also been calculated. The hopanes are represented by a range of C27 to C35 components, with the specific isomers varying amongst the sections due to differences in thermal maturity. Steranes occur as a range of C27, C28 and C29 isomers, whereas diasteranes only occur in the most thermally mature section (CAB). Other compounds of interest include gammacerane and dinosterane

  18. Metabolic depression in animals: physiological perspectives and biochemical generalizations.

    Science.gov (United States)

    Guppy, M; Withers, P

    1999-02-01

    Depression of metabolic rate has been recorded for virtually all major animal phyla in response to environmental stress. The extent of depression is usually measured as the ratio of the depressed metabolic rate to the normal resting metabolic rate. Metabolic rate is sometimes only depressed to approx. 80% of the resting value (i.e. a depression of approx. 20% of resting); it is more commonly 5-40% of resting (i.e. a depression of approx. 60-95% of resting); extreme depression is to 1% or less of resting, or even to an unmeasurably low metabolic rate (i.e. a depression of approx. 99-100% of resting). We have examined the resting and depressed metabolic rate of animals as a function of their body mass, corrected to a common temperature. This allometric approach allows ready comparison of the absolute level of both resting and depressed metabolic rate for various animals, and suggests three general patterns of metabolic depression. Firstly, metabolic depression to approx. 0.05-0.4 of rest is a common and remarkably consistent pattern for various non-cryptobiotic animals (e.g. molluscs, earthworms, crustaceans, fishes, amphibians, reptiles). This extent of metabolic depression is typical for dormant animals with 'intrinsic' depression, i.e. reduction of metabolic rate in anticipation of adverse environmental conditions but without substantial changes to their ionic or osmotic status, or state of body water. Some of these types of animal are able to survive anoxia for limited periods, and their anaerobic metabolic depression is also to approx. 0.05-0.4 of resting. Metabolic depression to much less than 0.2 of resting is apparent for some 'resting', 'over-wintering' or diapaused eggs of these animals, but this can be due to early developmental arrest so that the egg has a low 'metabolic mass' of developed tissue (compared to the overall mass of the egg) with no metabolic depression, rather than having metabolic depression of the entire cell mass. A profound decrease in

  19. Growth characteristics of bone marrow stromal stem cells in neonatal rats with hypoxic-ischemic encephalopathy%新生鼠缺氧缺血性脑病时骨髓基质干细胞的生长特性

    Institute of Scientific and Technical Information of China (English)

    张谊; 姚笠

    2011-01-01

    背景:骨髓基质干细胞用于缺氧缺血性脑病治疗,其生长特性是否稳定尚需观察.目的:探讨急性脑缺氧缺血新生大鼠骨髓基质干细胞移植后的生长状态及理化性质的改变.方法:结扎新生7 d Wistar大鼠双侧颈总动脉制成缺血模型,恢复2 h后,吸入体积分数8%O2、92%N2的混合气体制成缺氧缺血性脑病模型.分为轻度(缺氧1 h)、中度(缺氧1.5 h)、重度(缺氧2.5 h)缺氧缺血性脑病组及假手术组(仅结扎左侧颈总动脉).观察各组骨髓基质干细胞的生长状态.结果与结论:假手术组及轻度缺氧缺血性脑病组骨髓基质干细胞在提取培养3 h即可贴壁生长,而中、重度组骨髓基质干细胞贴壁较晚且生长状态较差,假手术组、轻、中度组细胞形态可逐渐恢复.假手术组及轻度组细胞凋亡率基本相同,中、重度组细胞凋亡率明显增高.轻度及中度组培养上清液乳酸脱氢酶有不同程度的增高.提示轻、中度缺氧缺血对骨髓基质干细胞的影响是可逆的,骨髓基质干细胞生长旺盛,对于损伤恢复功能较强.%BACKGROUND: The growth features of bone marrow stromal stem cells (BMSCs) for hypoxia ischemic encephalopathy is unclear.OBJECTIVE: To observe growth characteristics and physical and chemical characters of BMSCs in treatment of acute anoxic-ischemia newborn rats.METHODS: Seven-day-old rats were selected to ligate the bilateral carotid arteries to prepare ischemic models. After 2 hours, the neonatal rats deeply suffered from hypoxia (8% O2 and 92% N2) for 1-2.5 hours. The rats were divided into mild group (ischemia for 1 hour), moderate group (ischemia for 1.5 hours), severe group (ischemia for 2.5 hours), anoxia-ischemia group and sham operation group (only ligation of the left carotid artery). The growth condition of BMSCs was observed.RESULTS : After 3-hour cultu re, BMSCs grew adherently in the sham operation and anoxia-ischemia groups, superior to

  20. Oceanic ecosystem dynamics during gigantic volcanic episodes: the Ontong Java and Manihiki Plateaus recorded by calcareous nannoplankton. (Invited)

    Science.gov (United States)

    Erba, E.

    2010-12-01

    Earth's volcanic activity introduces environmental stress that biota are forced to survive. There is a general consensus on the role of volcanogenic carbon dioxide increases, and implicit tectonic-igneous events, triggering major climate changes and profound variations in chemical, physical and trophic characteristics of the oceans through the Phanerozoic. Cretaceous geological records indicate conditions of excess atmCO2 (up to 2000-3000 ppm) derived from construction of Large Igneous Provinces (LIPs). In such “high CO2 world” and greenhouse conditions, the deep ocean became depleted of oxygen promoting the accumulation and burial of massive amounts of organic matter; such episodes are recognized as Oceanic Anoxic Events (OAEs) and their geological records merit careful examination of how the Earth system, and Life in particular, can overcome extreme experiments of global change. The Early Aptian (˜ 120 million years ago) OAE1a is a complex example of volcanicCO2-induced environmental stress. There is a general consensus on the causes of this case-history, namely excess CO2 derived from the construction of the Ontong Java-Manihiki LIP. Multi- and inter-disciplinary studies of the OAE1a have pointed out C, O, Os, Sr isotopic anomalies, a biocalcification crisis in pelagic and neritic settings, enhanced fertility and primary productivity, as well as ocean acidification. Available cyclochronology allows high-resolution dating of biotic and environmental fluctuations, providing the precision necessary for understanding the role of volcanogenic CO2 on nannoplankton biocalcification, adaptations, evolutionary innovation and/or extinctions. The reconstructed sequence of volcanogenic CO2 pulses, and perhaps some clathrate melting, triggered a climate change to supergreenhouse conditions, anoxia and ocean acidification. The demise of heavily calcified nannoconids and reduced calcite paleofluxes marks beginning of the pre-OAE1a calcification crisis. Ephemeral coccolith

  1. Fjord water circulation patterns and dysoxic/anoxic conditions in a Mediterranean semi-enclosed embayment in the Amvrakikos Gulf, Greece

    Science.gov (United States)

    Ferentinos, George; Papatheodorou, George; Geraga, Maria; Iatrou, Margarita; Fakiris, Elias; Christodoulou, Dimitris; Dimitriou, Evagelos; Koutsikopoulos, Constantin

    2010-08-01

    Oceanographic research in the Amvrakikos Gulf in Western Greece, a semi-enclosed embayment isolated from the Ionian Sea by a narrow, shallow sill, has shown that it is characterised by a fjord-like oceanographic regime. The Gulf is characterised by a well-stratified two layer structure in the water column made up of a surface layer and a bottom layer that are separated by a strong pycnocline. At the entrance over the sill, there is a brackish water outflow in the surface water and a saline water inflow in the near-bed region. This morphology and water circulation pattern makes the Amvrakikos Gulf the only Mediterranean Sea fjord. The investigations have also shown that the surface layer is well oxygenated, whereas in the pycnocline, the dissolved oxygen (DO) declines sharply and finally attains a value of zero, thus dividing the water column into oxic, dysoxic and anoxic environments. At the dysoxic/anoxic interface, at a depth of approximately 35 m, a sharp redox cline develops with Eh values between 0 and 120 mV occurring above and values between 0 and -250 mV occurring below, where oxic and anoxic biochemical processes prevail, respectively. On the seafloor underneath the anoxic waters, a black silt layer and a white mat cover resembling Beggiatoa-like cells are formed. The dysoxic/anoxic conditions appeared during the last 20 to 30 years and have been caused by the excessive use of fertilisers, the increase in animal stocks, intensive fish farming and domestic effluents. The inflicted dysoxia/anoxia has resulted in habitat loss on the seafloor over an area that makes up just over 50% of the total Gulf area and approximately 28% of the total water volume. Furthermore, anoxia is also considered to have been responsible for the sudden fish mortality which occurred in aquaculture rafts in the Gulf in February 2008. Therefore, anoxic conditions can be considered to be a potential hazard to the ecosystem and to the present thriving fishing and mariculture industry in

  2. Warming, euxinia and sea level rise during the Paleocene-Eocene Thermal Maximum on the Gulf Coastal Plain: implications for ocean oxygenation and nutrient cycling

    Science.gov (United States)

    Sluijs, A.; van Roij, L.; Harrington, G. J.; Schouten, S.; Sessa, J. A.; LeVay, L. J.; Reichart, G.-J.; Slomp, C. P.

    2014-07-01

    The Paleocene-Eocene Thermal Maximum (PETM, ~ 56 Ma) was a ~ 200 kyr episode of global warming, associated with massive injections of 13C-depleted carbon into the ocean-atmosphere system. Although climate change during the PETM is relatively well constrained, effects on marine oxygen concentrations and nutrient cycling remain largely unclear. We identify the PETM in a sediment core from the US margin of the Gulf of Mexico. Biomarker-based paleotemperature proxies (methylation of branched tetraether-cyclization of branched tetraether (MBT-CBT) and TEX86) indicate that continental air and sea surface temperatures warmed from 27-29 to ~ 35 °C, although variations in the relative abundances of terrestrial and marine biomarkers may have influenced these estimates. Vegetation changes, as recorded from pollen assemblages, support this warming. The PETM is bracketed by two unconformities. It overlies Paleocene silt- and mudstones and is rich in angular (thus in situ produced; autochthonous) glauconite grains, which indicate sedimentary condensation. A drop in the relative abundance of terrestrial organic matter and changes in the dinoflagellate cyst assemblages suggest that rising sea level shifted the deposition of terrigenous material landward. This is consistent with previous findings of eustatic sea level rise during the PETM. Regionally, the attribution of the glauconite-rich unit to the PETM implicates the dating of a primate fossil, argued to represent the oldest North American specimen on record. The biomarker isorenieratene within the PETM indicates that euxinic photic zone conditions developed, likely seasonally, along the Gulf Coastal Plain. A global data compilation indicates that O2 concentrations dropped in all ocean basins in response to warming, hydrological change, and carbon cycle feedbacks. This culminated in (seasonal) anoxia along many continental margins, analogous to modern trends. Seafloor deoxygenation and widespread (seasonal) anoxia likely

  3. Relationships between bacterial-algal proliferating and mass extinction in the Late Devonian Frasnian-Famennian transition: Enlightening from carbon isotopes and molecular fossils

    Institute of Scientific and Technical Information of China (English)

    GONG Yiming; XU Ran; TANG Zhongdao; SI Yuanlan; LI Baohua

    2005-01-01

    Studies show positive shifts of inorganic and organic carbon isotope values (δ13Ccarb and δ 13Ckerogen) from +0.43 (‰ V-PDB) to +3.54 (‰ V-PDB) and from -29.38 (‰ V-PDB) to -24.14 (‰ V-PDB), respectively, B* (Ba* = Ba/ (Al2O3 X 15%)) values from 0.015 to 0.144, TOC values from 0.02% to 0.21%, V/Cr values from 0.3 to 2.0, Sr/Ba values from 3.20 to 49.50 in the Late Devonian Frasnian Upper rhenana zone to the top linguiformis zone of the Yangdi section deposited in carbonate slope facies of Guilin, Guangxi, South China, which indicates that biomass, productivity, organic carbon burial and salinity increase and that oxygenation near the boundary between sediments and waters decreases from the Late Devonian Frasnian Upper rhenana zone to the top linguiformis zone. Abundance of molecular fossils increases and normal alkanes, isoprenoid hydrocarbon, terpanes and steranes are dominated from the Late Devonian Frasnian to the bottom of Famennian, which shows that the predecessors of molecular fossils of the Frasnian-Famennian (F-F) transition are dominated by marine phytoplankton, zooplankton and benthic bacteria with no photosynthesis. Therefore, it is considered that the F-F transitional mass extinction with a multistage, selection and global synchronizing was caused by bacterial-algal proliferating, continuing deterioration of the shallow marine ecoenvironment of the middle-lower latitudes. A simple cause and effect chain can be expressed as: appearance of seed plants and multi-storied forests → Enhanced chemical and biochemical weathering and pedogenesis→ Wide development of soils → Increasing riverine nutrient fluxes in epicontinental sea → From superoligotrophic to eutrophic in epicontinental sea →Proliferating of marine phytoplankton and zooplankton → Frequent red tide and anoxia → Mass extinction of shallow marine organisms in the middle-lower latitudes. It is worth notice that the factor drawdown of atmospheric Pco2, climatic cooling and sea

  4. Rock magnetic and geochemical proxies for iron mineral diagenesis in a tropical lake: Lago Verde, Los Tuxtlas, East Central Mexico

    Science.gov (United States)

    Ortega, Beatriz; Caballero, Margarita; Lozano, Socorro; Vilaclara, Gloria; Rodríguez, Alejandro

    2006-10-01

    Magnetic and non-magnetic mineral analyses were conducted on a lacustrine sequence from Lago Verde in the tropical coast along the Gulf of Mexico that covers the last 2000 years. The site witnessed the transformation of the environment since the early Olmec societies until forest clearance in the last century. Through these analyses we investigated the processes that affected the magnetic mineralogy in order to construct a model of past environmental changes, and compare this model with the archeological record and inferred climatic changes in the northern hemisphere of tropical America. Volcanic activity has played a major influence on sediment magnetic properties, as a purveyor of Ti-magnetites/Ti-maghemites, and as a factor of instability in the environment. Anoxic reductive conditions are evident in most of Lago Verde's sedimentary record. Direct observations of magnetic minerals and ratios of geochemical (Fe, Ti), and ferrimagnetic ( χf) and paramagnetic ( χp) susceptibility ( χ) data, are used as parameters for magnetite dissolution ( χp/ χ, Fe/ χf), and precipitation ( χf/Ti) of magnetic minerals. Intense volcanic activity and anoxia are recorded before A.D. 20, leading to the formation of framboidal pyrite. Increased erosion, higher evaporation rates, lower lake levels, anoxia and reductive diagenesis in non-sulphidic conditions are inferred for laminated sediments between A.D. 20-850. This deposit matches the period of historical crisis and multiyear droughts that contributed to the collapse of the Maya civilization. Dissolution of magnetite, a high organic content and framboidal pyrite point to anoxic, sulphidic conditions and higher lake levels after A.D. 850. Higher lake levels in Lago Verde broadly coincide with the increased precipitation documented during the Medieval Warm Period (A.D. 950-1350) in the northern tropical and subtropical regions of the American continent. For the Little Ice Age (A.D. 1400-1800), the relatively moist conditions

  5. Redox Conditions and Related Color Change in Eastern Equatorial Pacific Sediments: IODP Site U1334

    Science.gov (United States)

    Kordesch, W. E.; Gussone, N. C.; Hathorne, E. C.; Kimoto, K.; Delaney, M. L.

    2011-12-01

    This study was prompted by a 65 m thick brown-green color change in deep-sea sediments of IODP Site U1334 (0-38 Ma, 4799 m water depth) that corresponds to its equatorial crossing (caused by the Northward movement of the pacific plate). Green sediment is a visual indicator of reducing conditions in sediment due to enhanced organic matter deposition and burial. Here we use geochemical redox indicators to characterize the effect of equatorial upwelling on bottom water. The modern redox signal is captured in porewater profiles (nitrate, manganese, iron, sulfate) while trace metal Enrichment Factors (EF) in bulk sediment (manganese, uranium, molybdenum, rhenium) normalized to the detrital component (titanium) record redox state at burial. To measure export productivity we also measure biogenic barium. Porewater profiles reveal suboxic diagenesis; profiles follow the expected sequence of nitrate, manganese oxide, and iron oxide reduction with increasing depth. Constant sulfate (~28 μM) implies anoxia has not occurred. Bulk sediment Mn EF are enriched (EF > 1) throughout the record (Mn EF = 15-200) while U and Mo enrichment corresponds to green color and equatorial proximity (U EF = 4-19; Mo EF = 0-7). Constant Mn enrichment implies continuous oxygenation. Uranium and Mo enrichment near the equator represents suboxic conditions also seen in the porewater. Low Re concentrations (below detection) provide additional evidence against anoxia. A comparison of Mn EF from total digestions to samples treated with an additional reductive cleaning step distinguishes between Mn-oxides and Mn-carbonates, indicating oxygenated and reducing conditions respectively. Mn-carbonate occurrence agrees with U and Mo EF; conditions were more reducing near the equator. Bio-Ba shows significant variability over this interval (22-99 mmol g-1). Our geochemical results indicate that bottom waters became suboxic at the equator as a result of equatorial upwelling-influenced increases in organic

  6. The Paleocene-Eocene "Greenhouse" Arctic Ocean paleoenvironment: Implications from biomarker results from IODP Expedition 302 (ACEX)

    Science.gov (United States)

    Weller, P.; Stein, R.

    2006-12-01

    In order to reconstruct the long-term Cenozoic climate history of the central Arctic Ocean and its role in earth's transition from Paleogene greenhouse to the Neogene icehouse conditions, IODP Expedition 302 (Arctic Ocean Coring Experiment ACEX) visited the Lomonosov Ridge in August 2004. Here, we present new data of organic-geochemical compounds determined in ACEX sediment samples to identify organic matter sources and biomarker proxies to decipher processes controlling organic-carbon accumulation and their paleo- environmental significance. Of special interest was the reconstruction of organic carbon composition, preservation and accumulation (i.e. high productivity vs. anoxia vs. terrigenous input) during periods of extreme global warmth and proposed increased freshwater discharge in the early Cenozoic. Specific source-related biomarkers (e.g. n-alkanes, fatty acids, isoprenoids, carotenoids, steranes/sterenes, hopanes/hopenes, hopanoic acids, aromatic terpenoids, benzohopanes, long-chain alkenones, organic sulfur compounds) and Rock-Eval parameters were determined in the ACEX sediment samples, ranging from the late Paleocene to the middle Miocene in age. The records show highly variable TOC-contents and a large variety and variability of compounds derived from marine, terrestrial and bacterial origin. The distribution of hopanoic acid isomers was dominated by compounds with the biological 17 beta (H), 21 beta (H) configuration indicating a low level of maturity, which was in good agreement with the data from Rock-Eval pyrolysis. Based on the biomarker data, the terrestrial organic matter supply was significantly enriched during the late Paleocene and part of the early Eocene, whereas n-alkanes and n-fatty acids in samples from the PETM and Elmo events as well as the middle Eocene indicate increased aquatic contributions. Furthermore samples from the middle Eocene were characterized by the occurrence of long-chain alkenones, high proportions of lycopane and high

  7. First report on Cretaceous paleoweathering rates in western Panthalassa: Evidence of global enhancement of continental weathering during OAE 2

    Science.gov (United States)

    Ohta, T.

    2013-12-01

    Mid-Cretaceous is characterized by intensified oceanic anoxia (Oceanic Anoxic Events: OAEs) that raised global deposition of organic black shales. Several models have been proposed to explain the cause of the OAEs in conjunction with Cretaceous global warmth, active volcanism, sea-level changes and others. For example, Weissert et al. (1998) proposed a mechanism called 'weathering hypothesis'. In this model, the cause of the OAEs is explained in a following chain reaction, (1) global warmth and increase in atmospheric CO2 enhanced weathering of continental crust, (2) enhanced land weathering led excessive influx of nutrients from continents to oceans, (3) eutrophication enhanced primary productivity, (4) the excessive primary producers consumed dissolved oceanic oxygen that finally led to the OAEs. Several studies, in fact, revealed a causal relation between enhanced weathering and OAEs in northern Tethys region. However, it is necessary to collect worldwide information to unravel the global response of weathering hypothesis as a cause of OAEs. For such reason, the present contribution conducted measurements of the degree of hinterland paleoweathering during OAEs in northern Japan, for the purpose to provide a first report on the relation between continental weathering and OAEs in open ocean, the western Panthalassa Ocean. Aptian to Campanian forearc basin mudstones (Yezo Group) were analyzed by XRF and the degree of hinterland weathering was evaluated by geochemical weathering index (W index; Ohta and Arai, 2007). The W values obtained for the Yezo Group are 30~50, which is equivalent to the W values of recent soils developed in temperate mid-latitude climate. The W values show a fluctuation pattern that is concordant with the Cretaceous paleotemperature changes. This match indicates that the change in paleotemperature governed the weathering rates of East Asian continental crust. In addition, hinterland weathering rates show instantaneous increase during the OAE

  8. Aerobic methanotrophs drive the formation of a seasonal anoxic benthic nepheloid layer in monomictic Lake Lugano

    Science.gov (United States)

    Blees, Jan; Niemann, Helge; Wenk, Christine B.; Zopfi, Jacob; Schubert, Carsten J.; Jenzer, Joël S.; Veronesi, Mauro L.; Lehmann, Moritz F.

    2014-05-01

    In the southern basin of Lake Lugano, thermal stratification of the water column during summer and autumn leads to a lack of exchange between surface and deep water masses, and consequently to seasonal bottom water anoxia, associated with high methane concentrations. With the onset of bottom water anoxia, a dense layer of high particulate matter concentration - a so-called benthic nepheloid layer (BNL) - develops in the bottom waters. A sharp redox gradient marks the upper boundary of the BNL. At its maximum, the BNL extends 15 - 30 m from the sediment into the water column. We investigated the identity of the BNL and key environmental factors controlling its formation in the framework of a seasonal study. Compound specific C-isotope measurements and Fluorescence In Situ Hybridisation (FISH) of suspended particulate organic matter, radioactive tracer based measurements of methane oxidation, as well as investigation of geochemical water column parameters were performed in spring and autumn. Our analyses revealed that the microbial biomass within the BNL is dominated by methanotrophic bacteria. Aerobic methane oxidation (MOx) was restricted to a narrow zone at the top of the BNL, reaching maximum rates of up to 1.8 μM/day. The rates of MOx activity effectively consumed most (>99%) of the uprising methane, leading to the formation of a sharp CH4 concentration gradient and a strongly suppressed kinetic isotope effect (ɛ = -2.8o). CH4 oxidation was limited by the diffusive supply of O2 from the upper hypolimnion, implying that methanotrophy is the primary driver of the seasonal expansion of the anoxic bottom water volume, and explaining the vertical migration of the BNL in response to its own O2 consumption. The bulk organic matter extracted from the BNL was strongly depleted in 13C (δ13C methanotrophic. The cell size of methanotrophs was significantly larger than of other microbial cells, and an independent approach to quantify the contribution of methanotroph

  9. Black shale deposition during Toarcian super-greenhouse driven by sea level

    Directory of Open Access Journals (Sweden)

    M. Hermoso

    2013-07-01

    Full Text Available One of the most elusive aspects of the Toarcian Oceanic Anoxic Event (T-OAE is the paradox between carbon isotopes that indicate intense global primary productivity and organic carbon burial at a global scale, and the delayed expression of anoxia in Europe. During the earliest Toarcian, no black shales were deposited in the European epicontinental seaways, and most organic carbon enrichment of the sediments postdated the T-OAE (defined by the overarching positive trend in the carbon isotopes. In the present studied, we have attempted to establish a sequence stratigraphy framework for Early Toarcian deposits recovered from a core drilled in the Paris Basin using a combination of mineralogical (quartz and clay relative abundance and geochemical (Si, Zr, Ti and Al measurements. Combined with the evolution in redox sensitive elements (Fe, V and Mo, the data suggest that expression of anoxia was hampered in European epicontinental seas during most of the T-OAE due to insufficient water depth that prevented stratification of the water column. Only the first stratigraphic occurrence of black shales in Europe corresponds to the "global" event. This interval is characterised by > 10% Total Organic Carbon (TOC content that contains relatively low concentration of molybdenum compared to subsequent black shale horizons. Additionally, this first black shale occurrence is coeval with the record of the major negative Carbon Isotope Excursion (CIE, likely corresponding to a period of transient greenhouse intensification likely due to massive injection of carbon into the Atmosphere–Ocean system. As a response to enhanced weathering and riverine run-off, increased fresh water supply to the basin may have promoted the development of full anoxic conditions through haline stratification of the water column. In contrast, post T-OAE black shales were restricted to epicontinental seas (higher Mo to TOC ratios during a period of relative high sea level, and carbon

  10. Acoplamiento pelágico-bentónico: respuesta de la zona bentónica profunda a la sedimentación del florecimiento invernal de diatomeas en el lago oligotrófico Alchichica, Puebla, México Pelagic-benthic coupling: deep benthic zone response to winter diatom bloom sinking in oligotrophic Lake Alchichica, Puebla, Mexico

    Directory of Open Access Journals (Sweden)

    Javier Alcocer

    2008-08-01

    Full Text Available El objetivo del presente estudio es reconocer la existencia de un acoplamiento pelágico-bentónico en el lago oligotrófico tropical Alchichica evaluando la respuesta de la zona bentónica profunda a la sedimentación del florecimiento invernal de diatomeas. Se midió la biomasa fitoplanctónica en la columna de agua a lo largo de un ciclo anual, al igual que la concentración de clorofila a sedimentaria. Alchichica es un lago monomíctico cálido con un periodo de circulación invernal y estratificación el resto del año. La presencia de turbulencia y nutrimentos durante el periodo de circulación favorecen el desarrollo de un florecimiento de diatomeas compuesto por especies de talla grande (p. e., Cyclotella alchichicana, las cuales se sedimentan al no ser consumidas en su totalidad. La zona bentónica profunda del lago responde a la sedimentación del florecimiento invernal de diatomeas con el desarrollo y permanencia por un periodo prolongado de anoxia hipolimnética, lo que a su vez, impide el establecimiento y desarrollo de fauna bentónica en el Lago Alchichica, favorece la pérdida interna de nitrógeno por desnitrificación y consecuentemente, conlleva a que el nitrógeno sea el elemento que más frecuentemente límite el crecimiento fitoplanctónico.The aim of this study is to recognize the existence of a pelagic-benthic coupling in the oligotrophic, tropical Lake Alchichica through analysis of the response of the deep benthic zone to the winter diatom bloom deposition. The water column phytoplankton biomass and the sedimentary chlorophyll a were analyzed along an annual cycle. Alchichica is a warm monomictic lake circulating in winter and stratified over the rest of the year. The presence of turbulence and nutrient availability during the mixing period, favor the development of a diatom bloom composed by large species (e. g., Cyclotella alchichicana which are not totally consumed and settle down. The deep benthic zone responds to

  11. Fatty acid synthase plays a role in cancer metabolism beyond providing fatty acids for phospholipid synthesis or sustaining elevations in glycolytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Hopperton, Kathryn E., E-mail: kathryn.hopperton@mail.utoronto.ca [Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada M5S 3E2 (Canada); Duncan, Robin E., E-mail: robin.duncan@uwaterloo.ca [Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada M5S 3E2 (Canada); Bazinet, Richard P., E-mail: richard.bazinet@utoronto.ca [Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada M5S 3E2 (Canada); Archer, Michael C., E-mail: m.archer@utoronto.ca [Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada M5S 3E2 (Canada); Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, ON, Canada M5S 3E2 (Canada)

    2014-01-15

    Fatty acid synthase is over-expressed in many cancers and its activity is required for cancer cell survival, but the role of endogenously synthesized fatty acids in cancer is unknown. It has been suggested that endogenous fatty acid synthesis is either needed to support the growth of rapidly dividing cells, or to maintain elevated glycolysis (the Warburg effect) that is characteristic of cancer cells. Here, we investigate both hypotheses. First, we compared utilization of fatty acids synthesized endogenously from {sup 14}C-labeled acetate to those supplied exogenously as {sup 14}C-labeled palmitate in the culture medium in human breast cancer (MCF-7 and MDA-MB-231) and untransformed breast epithelial cells (MCF-10A). We found that cancer cells do not produce fatty acids that are different from those derived from exogenous palmitate, that these fatty acids are esterified to the same lipid and phospholipid classes in the same proportions, and that their distribution within neutral lipids is not different from untransformed cells. These results suggest that endogenously synthesized fatty acids do not fulfill a specific function in cancer cells. Furthermore, we observed that cancer cells excrete endogenously synthesized fatty acids, suggesting that they are produced in excess of requirements. We next investigated whether lipogenic activity is involved in the maintenance of high glycolytic activity by culturing both cancer and non-transformed cells under anoxic conditions. Although anoxia increased glycolysis 2–3 fold, we observed no concomitant increase in lipogenesis. Our results indicate that breast cancer cells do not have a specific qualitative or quantitative requirement for endogenously synthesized fatty acids and that increased de novo lipogenesis is not required to sustain elevations in glycolytic activity induced by anoxia in these cells. - Highlights: • Fatty acid synthase (FASN) is over-expressed in cancer but its function is unknown. • We compare

  12. Understanding Oceanic Anoxic Events: An Integrated Geochemical Approach

    Science.gov (United States)

    Cohen, A. S.; Coe, A. L.; Kemp, D. B.; Pearce, C. R.

    2007-12-01

    Discrete intervals of widespread organic carbon accumulation, termed Oceanic Anoxic Events (OAEs), occurred at a few relatively brief intervals during the Mesozoic. Recent studies have shown that these events took place at the same time as other substantial environmental changes that included global warming, ocean acidification, and unusually high levels of species extinctions. However, many factors relating to the behaviour of the Earth System during OAEs remain unclear. These include: The primary driving mechanism(s) - was there one common mechanism or were OAEs the result of different processes; the spatial and temporal extent of seawater anoxia during OAEs; the precise effects on marine and terrestrial biota; variations in atmospheric CO2 and global temperature; and the mechanism and timescale of Earth's recovery process. The records of environmental change during OAEs are best preserved in marine deposits, with continental shelf sections being particularly well studied. The combined use of geochemical, sedimentological and palaeontological observations indicates a complex interplay of factors. Significant advances in our understanding of OAEs have taken place in the last decade or so using new geochemical and isotopic proxies and a high- resolution, multidisciplinary approach. For example, Sr- and Os-isotope data indicate that rates of chemical weathering increased markedly during the Toarcian (Early Jurassic) OAE, whilst Mo-isotope data suggest that the areal extent of seawater anoxia fluctuated during the OAE despite the persistence of euxinic conditions in some regions. The pattern of Mo-isotope data for the Toarcian contrasts strongly with new Mo-isotope results from the Kimmeridge Clay Formation (Late Jurassic), when anoxic conditions were confined to European epicontinental seas and were likely to have resulted from very different primary causes. Cyclostratigraphic analysis has been used to provide a temporal framework for the timescale of OAEs at sub

  13. Observation of polyphosphate granules in cable bacteria

    Science.gov (United States)

    Yang, T.; Nielsen, L. P.; Risgaard-Petersen, N.

    2015-12-01

    Cable bacteria are long filamentous bacteria that capable for long distance electron transport: transporting electrons derived from oxidizing sulfide in anoxic layers, to oxygen at the sediment surface, over a distance of centimeters. Cable bacteria are found in many types of freshwater and marine sediment all over the world, with density of approximately thousands of kilometers per square meter. These long filaments are composed by individual cells closely related to Desulfobulbaceae, connected with a shared outer membrane inside which the strings structure are presumed to be highly conductive. The observed doubling time of cells within the filament is about 20 min, which is among the shortest compare to other bacteria. In these cable cells, we constantly observed polyphosphate granules (poly-P), regardless of cell dimension and shape. This is very interesting since it has long been recognized that the microbial polyP content is low during rapid growth and increases under unfavorable conditions, for example, increasing sulfide concentration and anoxia resulted in a decomposition of poly-P in Beggiatoa. Here, we investigated marine cable bacteria from Netherland and Aarhus Bay, focusing on the poly-P dynamics under various redox conditions. In poly-P stained cells, typically there are two big poly-P granules locate at each polar. In dividing cells, however, the morphology of poly-P changed to six small granules precisely arranged to two row. Moreover, the cells seem be able to continuously divide more than one time without elongation step. These varied poly-P morphologies demonstrate that poly-P is closely related to the cell growth and cell division, by an unknown mechanism. Individual cable filaments were picked up and were exposed to different redox conditions; our primary data indicated the cable cells could suffer anoxic condition better than oxic condition. We also detected decomposition of poly-P under anoxia. These results call for an in-depth examination

  14. Antioxidant defenses and metabolic depression. The hypothesis of preparation for oxidative stress in land snails.

    Science.gov (United States)

    Hermes-Lima, M; Storey, J M; Storey, K B

    1998-07-01

    The roles of enzymatic antioxidant defenses in the natural tolerance of environmental stresses that impose changes in oxygen availability and oxygen consumption on animals is discussed with a particular focus on the biochemistry of estivation and metabolic depression in pulmonate land snails. Despite reduced oxygen consumption and PO2 during estivation, which should also mean reduced production of oxyradicals, the activities of antioxidant enzymes, such as superoxide dismutase and catalase, increased in 30 day-estivating snails. This appears to be an adaptation that allows the snails to deal with oxidative stress that takes place during arousal when PO2 and oxygen consumption rise rapidly. Indeed, oxidative stress was indicated by increased levels of lipid peroxidation damage products accumulating in hepatopancreas within minutes after arousal was initiated. The various metabolic sites responsible for free radical generation during arousal are still unknown but it seems unlikely that the enzyme xanthine oxidase plays any substantial role in this despite being implicated in oxidative stress in mammalian models of ischemia/reperfusion. We propose that the activation of antioxidant defenses in the organs of Otala lactea during estivation is a preparative mechanism against oxidative stress during arousal. Increased activities of antioxidant enzymes have also observed under other stress situations in which the actual production of oxyradicals should decrease. For example, antioxidant defenses are enhanced during anoxia exposure in garter snakes Thamnophis sirtalis parietalis (10 h at 5 degrees C) and leopard frogs Rana pipiens (30 h at 5 degrees C) and during freezing exposure (an ischemic condition due to plasma freezing) in T. sirtalis parietalis and wood frogs Rana sylvatica. It seems that enhancement of antioxidant enzymes during either anoxia or freezing is used as a preparatory mechanism to deal with a physiological oxidative stress that occurs rapidly within the

  15. Seasonal occurrence of anoxygenic photosynthesis in Tillari and Selaulim reservoirs, Western India

    Directory of Open Access Journals (Sweden)

    S. Kurian

    2012-07-01

    Full Text Available Phytoplankton and bacterial pigment compositions were determined by high performance liquid chromatography (HPLC and liquid chromatography-mass spectrometry (LC-MS in two freshwater reservoirs (Tillari Dam and Selaulim Dam, which are located at the foothills of the Western Ghats in India. These reservoirs experience anoxia in the hypolimnion during summer. Water samples were collected from both reservoirs during anoxic periods while one of them (Tillari Reservoir was also sampled in winter, when convective mixing results in well-oxygenated conditions throughout the water column. During the period of anoxia (summer, bacteriochlorophyll (BChl e isomers and isorenieratene, characteristic of brown sulfur bacteria, were dominant in the anoxic (sulfidic layer of the Tillari Reservoir under low light intensities. The winter observations showed the dominance of small cells of Chlorophyll b-containing green algae and cyanobacteria, with minor presence of fucoxanthin-containing diatoms and peridinin-containing dinoflagellates. Using total BChl e concentration observed in June, the standing stock of brown sulfur bacteria carbon in the anoxic compartment of Tillari Reservoir was estimated to be 2.27 gC m−2, which is much higher than the similar estimate for carbon derived from oxygenic photosynthesis (0.82 gC m−2. The Selaulim Reservoir also displayed similar characteristics with the presence of BChl e isomers and isorenieratene in the anoxic hypolimnion during summer. Although sulfidic conditions prevailed in the water column below the thermocline, the occurrence of photo-autotrophic bacteria was restricted only to mid-depths (maximal concentration of BChl e isomers was detected at 0.2% of the surface incident light. This shows that the vertical distribution of photo-autotrophic sulfur bacteria is primarily controlled by light penetration in the water column where the presence of H2

  16. Seasonal occurrence of anoxygenic photosynthesis in Tillari and Selaulim reservoirs, Western India

    Directory of Open Access Journals (Sweden)

    S. Kurian

    2011-12-01

    Full Text Available Phytoplankton and bacterial pigment compositions were determined by high performance liquid chromatography (HPLC and liquid chromatography- mass spectrometry (LCMS in two freshwater reservoirs (Tillari Dam and Selaulim Dam, which are located at the foothills of the Western Ghats in India. These reservoirs experience anoxia in the hypolimnion during summer. Water samples were collected from both reservoirs during anoxic periods while one of them (Tillari Reservoir was also sampled in winter, when convective mixing results in well-oxygenated conditions throughout the water column. During the periods of anoxia (summer, bacteriochlorophyll (BChl e isomers and isoreneiratene, characteristic of brown sulfur bacteria, were dominant in the anoxic (sulfidic layer of the Tillari Reservoir under low light intensities. The winter observations showed the dominance of small cells of Chlorophyll-b containing green algae and cyanobacteria, with minor presence of fucoxanthin-containing diatoms and peridinin-containing dinoflagellates. Using total BChl-e concentration observed in June, the standing stock of brown sulfur bacteria carbon in the Tillari Reservoir was computed to be 2.4 gC m−2, which is much higher than the similar estimate for carbon derived from oxygenic photosynthesis (0.82 gC m−2. These results highlight the importance of anoxygenic photosynthetic biomass in tropical freshwater systems. The Selaulim Reservoir also displayed similar characteristics with the presence of BChl-e isomers and isorenieratene in the anoxic hypolimnion during summer. Although sulfidic conditions prevailed in the water column below the thermocline, the occurrence of photoautotrophic bacteria was restricted only to mid-depths (maximal concentration of BChl-e isomers was noted at 0.2 % of the surface incident light. This shows that the vertical distribution of photoautotrophic sulfur bacteria is primarily

  17. A model of biogeochemical cycling of phosphorus, nitrogen, oxygen, and sulphur in the ocean: One step toward a global climate model

    Science.gov (United States)

    Shaffer, Gary

    1989-02-01

    formation (for P limitation) and denitrification (for N limitation) can strongly constrain primary production and the development of anoxia. N limitation, i.e., negligable nitrogen fixation, practically precludes anoxia but is unlikely for very long times scales. For P limitation and no phosphorite formation the model indicates that the redox state of the ocean may be most sensitive to changes in ocean biology followed by changes in ocean circulation and mixing and finally by changes in ocean temperature.

  18. Climate variability and relationship with ocean fertility during the Aptian Stage

    Science.gov (United States)

    Bottini, C.; Erba, E.; Tiraboschi, D.; Jenkyns, H. C.; Schouten, S.; Sinninghe Damsté, J. S.

    2014-02-01

    Several studies have been conducted to reconstruct temperature variations across the Aptian Stage, particularly during the Early Aptian Oceanic Anoxic Event (OAE)1a. There is a general consensus that a major warming characterized the OAE 1a, although some studies have provided evidence for transient "cold snaps" or cooler intervals during the event. The climatic conditions for the middle-late Aptian are less constrained, and a complete record through the Aptian is not available. Here we present a reconstruction of surface-water palaeotemperature and fertility based on calcareous nannofossil records from the Cismon and Piobbico cores (Tethys) and DSDP Site 463 (Pacific Ocean). The data, integrated with oxygen-isotope and TEX86 records, provide a detailed picture of climatic and ocean fertility changes during the Aptian Stage, which are discussed in relation to the direct/indirect role of volcanism. Warm temperatures characterized the pre-OAE 1a interval followed by a maximum warming (of ~2-3 °C) during the early phase of anoxia under intense volcanic activity of the Ontong Java Plateau (OJP). A short-lived (~35 ky) cooling episode interrupted the major warming, following a rapid increase of weathering rates. Nannofossils indicate that eutrophic conditions were reached when temperatures were at their highest and OJP volcanism most intense, thus suggesting that continental runoff, together with increased input of hydrothermal metals, increased nutrient supply to the oceans. The latter part of OAE 1a was characterized by cooling events, probably promoted by CO2 sequestration during burial of organic matter. In this phase, high productivity was probably maintained by N2-fixing cyanobacteria while nannofossil taxa indicating high fertility were rare. The end of anoxia coincided with the cessation of volcanism and a pronounced cooling. The mid-Aptian was characterized by high surface-water fertility and progressively decreasing temperatures, probably resulting from

  19. Climate variability and ocean fertility during the Aptian Stage

    Science.gov (United States)

    Bottini, C.; Erba, E.; Tiraboschi, D.; Jenkyns, H. C.; Schouten, S.; Sinninghe Damsté, J. S.

    2015-03-01

    Several studies have been conducted to reconstruct temperature variations across the Aptian Stage, particularly during early Aptian Oceanic Anoxic Event (OAE) 1a. There is a general consensus that a major warming characterized OAE 1a, although some studies have provided evidence for transient "cold snaps" or cooler intervals during the event. The climatic conditions for the middle-late Aptian are less constrained, and a complete record through the Aptian is not available. Here we present a reconstruction of surface-water palaeotemperature and fertility based on calcareous nannofossil records from the Cismon and Piobbico cores (Tethys) and DSDP Site 463 (Pacific Ocean). The data, integrated with oxygen-isotope and TEX86 records, provide a detailed picture of climatic and ocean fertility changes during the Aptian Stage, which are discussed in relation to the direct/indirect role of volcanism. Warm temperatures characterized the pre-OAE 1a interval, followed by a maximum warming (of ~ 1.5-2 °C) during the early phase of anoxia under intense volcanic activity of the Ontong Java Plateau (OJP). A short-lived cooling episode interrupted the major warming, following a rapid increase in weathering rates. Nannofossils indicate that mesotrophic conditions were reached when temperatures were at their highest and OJP volcanism most intense, thus suggesting that continental runoff, together with increased input of hydrothermal metals, increased nutrient supply to the oceans. The latter part of OAE 1a was characterized by cooling events, probably promoted by CO2 sequestration during burial of organic matter. In this phase, high productivity was probably maintained by N2-fixing cyanobacteria, while nannofossil taxa indicating higher fertility were rare. The end of anoxia coincided with the cessation of volcanism and a pronounced cooling. The mid-Aptian was characterized by highest surface-water fertility and progressively decreasing temperatures, probably resulting from intense

  20. Chronic hypoxia reduces adenosine A2A receptor-mediated inhibition of calcium current in rat PC12 cells via downregulation of protein kinase A.

    Science.gov (United States)

    Kobayashi, S; Beitner-Johnson, D; Conforti, L; Millhorn, D E

    1998-10-15

    1. Adenosine has been shown to decrease Ca2+ current (ICa) and attenuate the hypoxia-induced enhancement of intracellular free Ca2+ ([Ca2+]i) in oxygen-sensitive rat phaeochromocytoma (PC12) cells. These effects are mediated via the adenosine A2A receptor and protein kinase A (PKA). The current study was undertaken to determine the effects of adenosine on Ca2+ current and hypoxia-induced change in [Ca2+]i during chronic hypoxia. 2. Whole cell patch-clamp studies revealed that the effect of adenosine on ICa was significantly reduced when PC12 cells were exposed to hypoxia (10 % O2) for 24 and 48 h. 3. Ca2+ imaging studies using fura-2 revealed that the anoxia-induced increase in [Ca2+]i was significantly enhanced when PC12 cells were exposed to 10 % O2 for up to 48 h. In contrast, the inhibitory effects of adenosine on anoxia-induced elevation of [Ca2+]i was significantly blunted in PC12 cells exposed to hypoxia for 48 h. 4. Northern blot analysis revealed that mRNA for the A2A receptor, which is the only adenosine receptor subtype expressed in PC12 cells, was significantly upregulated by hypoxia. Radioligand binding analysis with [3H]CGS21680, a selective A2A receptor ligand, showed that the number of adenosine A2A receptor binding sites was similarly increased during exposure to 10% O2 for 48 h. 5. PKA enzyme activity was significantly inhibited when PC12 cells were exposed to 10% O2 for 24 and 48 h. However, we found that hypoxia failed to induce change in adenosine- and forskolin-stimulated adenylate cyclase enzyme activity. Chronic hypoxia also did not alter the immunoreactivity level of the G protein Gsalpha, an effector of the A2 signalling pathway. 6. Whole cell patch-clamp analysis showed that the effect of 8-bromo-cAMP, an activator of PKA, on ICa was significantly attenuated during 48 h exposure to 10% O2.7. We conclude therefore that the reduced effect of adenosine on ICa and [Ca2+]i in PC12 cells exposed to chronic hypoxia is due to hypoxia

  1. Handling and Use of Oxygen by Pancrustaceans: Conserved Patterns and the Evolution of Respiratory Structures.

    Science.gov (United States)

    Harrison, Jon F

    2015-11-01

    The handling and use of oxygen are central to physiological function of all pancrustaceans. Throughout the Pancrustacea, ventilation is controlled by a central oxygen-sensitive pattern generator. The ancestral condition was likely to achieve ventilation of the gills via leg-associated or mouth-associated muscles, but in insects and some air-breathing crustaceans, new muscles were recruited for this purpose, including intersegmental muscles likely used previously for posture and locomotion. Many aspects of the sensing of oxygen and the occurrence of responses to hypoxia (increased ventilation, depressed growth and metabolic rate, developmental changes that enhance the delivery of oxygen) appear common across most pancrustaceans, but there is tremendous variation across species. Some of this can be explained by habitat (e.g., ventilation of the internal medium occurs in terrestrial species and of the external medium in aquatic species; rearing under hypoxia induces tracheal proliferation in terrestrial insects and hemocyanin production in aquatic crustaceans); some plausibly by evolutionary origin of some responses to hypoxia within the Pancrustacea (the most basal arthropods may lack a ventilatory response to hypoxia); and some by the availability of environmental oxygen (animals adapted to survive hypoxia turn on the response to hypoxia at a lower PO2). On average, crustaceans and insects have similar tolerances to prolonged anoxia, but species or life stages from habitats with a danger of being trapped in hypoxia can tolerate longer durations of anoxia. Lactate is the primary anaerobic end-product in crustaceans but some insects have evolved a more diverse array of anaerobic end-products, including ethanol, alanine, succinate, and acetate. Most clades of Pancrustacea are small and lack obvious respiratory structures. Gilled stem-pancrustaceans likely evolved in the Cambrian, and gills persist in large Ostracoda, Malacostraca, and Branchiopoda. Based on currently

  2. On the role of asymmetric feedbacks for the deglacial dynamics of the marine N-cycle

    Science.gov (United States)

    Gruber, N.; Eugster, O.; Deutsch, C. A.; Jaccard, S.; Payne, M. R.

    2012-12-01

    Marine N-cycle feedbacks play a crucial role in stabilizing the marine N inventory over millennial timescales and longer. Here we show that asymmetric feedbacks between N-fixation and denitrification in the water column and in the sediments may have caused a transient imbalance of the marine N-budget over the last deglacial, leading to a substantial drop of the marine N inventory of between 15 and 50% between the last glacial period and the late Holocene. These results are based on a geochemical box model study where we determined the deglacial changes in marine N-fixation and denitrification required to match the observed sedimentary δ15 N changes. This is achieved by optimizing a set of 7 parameters that describe the strengths of 3 ocean-internal N feedbacks and the response of the oceanic N-cycle to 4 external forcings. Scenarios that best match the δ15N constraints indicate a strong transient decrease in N-fixation in the early deglacial in response to the decrease in iron input by dust. During this period, denitrification in the water column and in the sediments continue largely unabated at their glacial rates due to a very weak diagnosed feedback to the decreasing N-inventory. In contrast, N-fixation reacted very sensitively to the abrupt increase in water column denitrification around 15 kyr BP caused by an expansion of anoxia at that time. This strong feedback of N-fixation to changes in denitrification lets N-fixation quickly rebound to the level required to balance the global losses by denitrification during the Holocene. This limits the extent to which denitrification can drive temporary imbalances. This asymmetry in the strengths of the marine N-feedbacks can be rationalized by recognizing that an excess inventory of N over that of PO4 may not lead to the necessary increase in export production required to increase anoxia, as rather quickly, PO4 will become the proximate limiting nutrient. In contrast, a deficiency in N over PO4 will create nearly

  3. Macroinvertebrados bentônicos como indicadores de qualidade de água na Barragem Santa Bárbara, Pelotas, RS, Brasil Zoobenthics as indicators of the water quality in the Santa Bárbara Dam, Pelotas, RS, Brazil

    Directory of Open Access Journals (Sweden)

    Sérgio Renato Noguez Piedras

    2006-04-01

    Full Text Available O objetivo deste trabalho foi estudar o impacto de dois afluentes da barragem Santa Bárbara sobre o ambiente da mesma, utilizando a ocorrência de invertebrados bentônicos e características químicas da água. Durante nove meses foram realizadas coletas e análises da água e de invertebrados bentônicos nos afluentes Sanga da Barbuda e Sanga do Passo do Cunha e também no interior da bacia de acumulação da barragem. Os resultados mostram que, embora a Sanga da Barbuda e a Sanga do Passo do Cunha apresentem características químicas abaixo do recomendável, no limite aceitável pela legislação que determina os padrões de qualidade da água para abastecimento público, estes afluentes estão, ainda, sendo diluídos de forma satisfatória na bacia de acumulação da barragem. O estudo das relações entre variáveis químicas e invertebrados bentônicos mostra haver correlação significativa entre os baixos níveis de oxigênio dissolvido e a presença de Oligochaeta, sendo que o aumento do número de Oligochaeta indica uma situação de anoxia na barragem Santa Bárbara.The objective of this work was to study the impact of two tributaries from the Santa Bárbara Dam on this environment using the occurrence of zoobenthics and some water chemical characteristics. Monthly gathering and analysis from the water and zoobenthics were done during nine months in the tributaries Sanga da Barbuda and Sanga Passo do Cunha as well as in the inner part of the accumulation basin in the Santa Barbara dam. The results demonstrate that, though Sanga da Barbuda and Sanga Passo do Cunha present chemical characteristics lower than the recommended but still in the limits acceptable by the law that regulates the water quality standards for the supply, these tributaries are being diluted in a satisfactory way in the accumulation basin in the Santa Barbara dam. The study of the relations between chemical variables and zoobenthics show a significant correlation

  4. Cdk1, PKCδ and calcineurin-mediated Drp1 pathway contributes to mitochondrial fission-induced cardiomyocyte death

    Energy Technology Data Exchange (ETDEWEB)

    Zaja, Ivan [Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226 (United States); Bai, Xiaowen, E-mail: xibai@mcw.edu [Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226 (United States); Liu, Yanan; Kikuchi, Chika; Dosenovic, Svjetlana; Yan, Yasheng; Canfield, Scott G. [Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226 (United States); Bosnjak, Zeljko J. [Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226 (United States); Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226 (United States)

    2014-10-31

    Highlights: • Drp1-mediated increased mitochondrial fission but not fusion is involved the cardiomyocyte death during anoxia-reoxygenation injury. • Reactive oxygen species are upstream initiators of mitochondrial fission. • Increased mitochondrial fission is resulted from Cdk1-, PKCδ-, and calcineurin-mediated Drp1 pathways. - Abstract: Myocardial ischemia–reperfusion (I/R) injury is one of the leading causes of death and disability worldwide. Mitochondrial fission has been shown to be involved in cardiomyocyte death. However, molecular machinery involved in mitochondrial fission during I/R injury has not yet been completely understood. In this study we aimed to investigate molecular mechanisms of controlling activation of dynamin-related protein 1 (Drp1, a key protein in mitochondrial fission) during anoxia-reoxygenation (A/R) injury of HL1 cardiomyocytes. A/R injury induced cardiomyocyte death accompanied by the increases of mitochondrial fission, reactive oxygen species (ROS) production and activated Drp1 (pSer616 Drp1), and decrease of inactivated Drp1 (pSer637 Drp1) while mitochondrial fusion protein levels were not significantly changed. Blocking Drp1 activity with mitochondrial division inhibitor mdivi1 attenuated cell death, mitochondrial fission, and Drp1 activation after A/R. Trolox, a ROS scavenger, decreased pSer616 Drp1 level and mitochondrial fission after A/R. Immunoprecipitation assay further indicates that cyclin dependent kinase 1 (Cdk1) and protein kinase C isoform delta (PKCδ) bind Drp1, thus increasing mitochondrial fission. Inhibiting Cdk1 and PKCδ attenuated the increases in pSer616 Drp1, mitochondrial fission, and cardiomyocyte death. FK506, a calcineurin inhibitor, blocked the decrease in expression of inactivated pSer637 Drp1 and mitochondrial fission. Our findings reveal the following novel molecular mechanisms controlling mitochondrial fission during A/R injury of cardiomyocytes: (1) ROS are upstream initiators of

  5. Analysis of high risk factors and head MRI in 249 children with spastic cerebral palsy%249例痉挛性脑瘫患儿高危因素与 MRI分析

    Institute of Scientific and Technical Information of China (English)

    廖小艳; 田新姿

    2014-01-01

    Objective:To sum up the common high risk factors of children with spastic cerebral palsy and different types of magnetic results. Methods:The clinical data of 249 children with spastic cerebral palsy were analyzed retrospectively. Results: The high risk factors of 80% children patients were multifactors. The common factors included:(1) prenatal:intrauterine distress, threat-ened abortion, cord around neck, medical history, and meconium contamination;(2) intrapartum:anoxia, premature birth, low body weight, premature rupture of placenta, and delayed delivery;and (3) postpartum:jaundice, intracranial hemorrhage, and pneumonia of newborn. The abnormal rate of head MRI result was 90. 7%, in which periventricular leukomalacia was the common type (50. 4%) . Conclusions: The common high risk factors of children with spastic cerebral palsy are anoxia, premature birth, low body weight, pathologic jaundice. The head MRI has a high probability to found the abnormal. Common risk factors for different types of magnetic results are different.%目的::总结痉挛型脑瘫患儿常见的高危因素及头颅MRI改变。方法:对249例痉挛型脑瘫患儿资料进行回顾性分析。结果:80%的患儿高危因素为多因素。最常见的有:①产前为胎儿宫内窘迫、先兆流产、脐带绕颈、用药史、胎粪污染;②产时依次为缺氧、早产、低体重、胎盘早破、产程延长;③产后为黄疸、颅内出血、新生儿肺炎。头颅MRI检查异常率为90.7%,其中脑室周围白质异常占50.4%。结论:痉挛型脑瘫患儿常见的高危因素为缺氧、早产、低体重、病理性黄疸,头颅MRI改变检出率高,且依致病因素不同而表现各异。

  6. Sedimentary Bacteriopheophytin a as an indicator of meromixis in varved lake sediments of Lake Jaczno, north-east Poland, CE 1891-2010

    Science.gov (United States)

    Butz, Christoph; Grosjean, Martin; Poraj-Górska, Anna; Enters, Dirk; Tylmann, Wojciech

    2016-09-01

    Trends in eutrophication and meromixis pose serious threats to water quality and biodiversity in freshwater ecosystems around the world. Because long-term observational data rarely exist, it is very difficult to assess whether meromixis is the result of anthropogenic impacts, climate variability, natural ecosystem development or a combination of these factors. Lake sediment proxy-data may help understand how and why eutrophication and meromixis occurred and disappeared in the past. In this study, we present a novel method and proxy to investigate past episodes of meromixis and hypolimnetic anoxia recorded in lake sediments. We use high-resolution (70 × 70 μm/pixel) calibrated hyperspectral imaging of a varved lake sediment core from meromictic Lake Jaczno (north-east Poland), to quantitatively map the spatial distribution of Bacteriopheophytin a (Bphe a) at very high sub-varve (i.e. seasonal) resolution. Bphe a is a bacterial pigment and stable degradation product of Bacteriochlorophyll a (Bchl a), which is produced by anoxygenic phototrophic bacteria (APBs) at the chemocline of meromictic lakes. Using sedimentary Bphe a we infer episodes of meromixis (i.e. long-term hypolimnetic anoxia) and changing mixing conditions (i.e. seasonal temperature, event-based water mixing) for the past ca. 120 years. Absence of meromixis occurred on several occasions. From the beginning of our record in CE 1891 until ca. CE 1918, meromixis was not observed. During this time, green pigments (mainly chlorophyll a [Chl a] and diagenetic products) produced by phototrophic algae were deposited while Bphe a was absent. This suggests that regular lake overturning prevented the formation of a persistent chemocline. Bphe a was identified before CE 1890 (Butz et al. 2015), but over the studied period 1891-2011, meromixis was established in CE 1918 and generally persisted through modern times. However, short-term interruptions of the chemocline were observed following events of rapid

  7. Monsoon driven changes in phytoplankton populations in the eastern Arabian Sea as revealed by microscopy and HPLC pigment analysis

    Science.gov (United States)

    Parab, Sushma G.; Prabhu Matondkar, S. G.; Gomes, H. do R.; Goes, J. I.

    2006-12-01

    Like the rest of the Arabian Sea, the west coast of India is subject to semi-annual wind reversals associated with the monsoon cycle that result in two periods of elevated phytoplankton productivity, one during the northeast (NE) monsoon (November-February) and the other during the southwest (SW) monsoon (June-September). Although the seasonality of phytoplankton biomass in these coastal waters is well known, the abundance and composition of phytoplankton populations associated with this distinct and predictable seasonal cycle is poorly known. Here we present for the first time, the results of a study on the community structure of phytoplankton for this region, derived from HPLC pigment analysis and microscopic cell counts. Our sampling strategy allowed for large spatial and temporal coverage over regions representative of the coastal and offshore waters, and over seasons that included the NE and the SW monsoon. Monthly observations at a fixed coastal station in particular, allowed us to follow changes in phytoplankton community structure associated with the development of anoxia. Together these measurements helped establish a pattern of seasonal change of three major groups of phytoplankton: diatoms, dinoflagellates and cyanobacteria that appeared to be tightly coupled with hydrographic and chemical changes associated with the monsoonal cycle. During the SW monsoon when nitrate concentrations were high, diatoms were dominant but prymnesiophytes were present as well. By October, as nitrate fell to below detection levels and anoxic conditions began to develop on the shelf below the shallow pycnocline, both diatom and prymensiophytes declined sharply giving way to dinoflagellates. In the well oxygenated surface waters, where both nitrate and ammonium were below detection limits, pico-cyanobacterial populations became dominant. During the NE monsoon, a mixed diatom-dinoflagellate population was quickly replaced by blooms of Trichodesmium erythraeum and Noctiluca

  8. Improved paleoenvironmental interpretations at the intersection between paleontology and biogeochemistry

    Science.gov (United States)

    Lyons, T. W.

    2012-04-01

    Paleoenviromental reconstructions, particularly those focused of oxygen levels in the ancient ocean, often rely on geochemical or paleoecological approaches but too infrequently exploit the added strength that comes with a combined approach. Trace metal, organic biomarker, and iron paleoredox proxies do well in distinguishing between ancient oxic water columns and anoxic, Fe-rich (ferruginous) and anoxic, sulfidic (euxinic) settings. Molybdenum isotope approaches may even allow us to estimate the amount of hydrogen sulfide in the ancient seawater. Where the challenges often arise are at intermediate redox states marked by episodes of only transient anoxia/euxinia where diagnostic geochemical end-member enrichments are muted. Unfortunately, rapid detrital sedimentation and depleted seawater metal inventories under anoxic/euxinic conditions on basin and ocean scales can yield similarly tempered metal enrichments. Intermediate geochemical signatures can also mark conditions of extremely low bottom-water oxygen (often referred to as 'suboxic') but with sulfide confined to the pore fluids and a lack of appreciable and persistent Fe availability in the water column. Also possible are protracted episodes of true anoxia that lack Fe or sulfide in the water column because of limited availability of the organic matter required to drive bacterial Fe and sulfate reduction. In contrast, benthic ecological relationships, both trace and body fossil, are very sensitive to redox fluctuations at the low oxygen end, even brief episodes of oxygenation, and across subtle spatiotemporal redox gradients, although they are not readily effective at distinguishing between ferruginous and euxinic bottom waters. The talk will explore the mechanistic underpinnings of some of the most important geochemical proxies and then view their relative strengths and weaknesses in light of the added insight gleaned via coupled paleoecological analysis. Beyond stronger interpretations of Phanerozoic

  9. Effect of transplanted mesenchymal stem cells from rats of different ages on the improvement of heart function after acute myocardial infarction

    Institute of Scientific and Technical Information of China (English)

    WANG Yi-qing; WANG Miao; ZHANG Peng; SONG Jing-jin; LI Yuan-peng; HOU Shu-hong; HUANG Cong-xin

    2008-01-01

    Background Mesenchymal stem cells (MSCs) transplantation is of therapeutic potential after ischemic injury in both experimental and clinical studies.Clinically,elderly patients are more vulnerable to acute myocardial infarction (AMI).But little is known about the characteristics of young donor-derived MSCs transplanted to old patients with AMI.The present study was designed to investigate the effect of transplanted MSCs from rats of different ages on the improvement of heart function after AMI.Methods MSCs from Sprague-Dawley (SD) rats were isolated and cultured in vitro.The apoptosis characteristics of MSCs were observed under conditions of ischemia and anoxia.SD rats underwent MI received intramyocardial injection of MSCs from young donor rats (n=8),old donor rats (n=8),respectively.AMI control group received equal volume physiological saline.Immunofluorescence was used to observe the differentiation of the grafted cells into cardiomyocytes.Four weeks after cell transplantation, reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry for vascular endothelial growth factor (VEGF),VIII-factor immunohistochemistry for vessel density,TUNEL,caspase-3 for cardiomyocyte apoptosis,echocardiography and hemodynamic detection for heart function were performed.Results The apoptosis rate of the old donor-derived MSCs group was significantly higher than that of the young donor-derived MSCs group under conditions of ischemia and anoxia (P <0.05).Engrafted MSCs survived,proliferated and differentiated into myocardium-like cells.VEGF gene expression and capillary density in the old donor-derived group were lower than those in the young donor-derived group but higher than those in the control group (P <0.05).The transplantation of old donor-derived MSCs attenuated apoptosis of cadiomyocytes in the peri-infract region compared with the control group and the effect was elevated in young donor-derived MSCs (P <0.05).The heart functions (left ventricle

  10. Monsoon variability in the northeastern Arabian Sea on orbital- and millennial scale during the past 200,000 years

    Science.gov (United States)

    Lückge, Andreas; Groeneveld, Jeroen; Steinke, Stephan; Mohtadi, Mahyar; Westerhold, Thomas; Schulz, Hartmut

    2016-04-01

    The Dansgaard-Oeschger oscillations and Heinrich events described in the Greenland ice cores and in North Atlantic and Western Mediterranean sediments are also expressed in the climate of the tropics, for example, as documented in Arabian Sea sediments. However, little is known about these fluctuations beyond the reach of the Greenland ice cores. Here, we present high-resolution geochemical, sedimentological as well as micropaleontological data from two cores (SO130-283KL, 987m water depth and SO130-289KL, 571m) off the coast of Pakistan, extending the monsoon record on orbital and millennial scales to the past 200,000 years. The stable oxygen isotope record of the surface-dwelling planktonic foraminifer G. ruber shows a strong correspondence to Greenland ice core δ18O, whereas the deepwater δ18O signal of benthic foraminifera (U. peregrina and G. affinis) reflects patterns recorded in ice cores from Antarctica. Strong shifts in benthic δ18O during stadials/Heinrich events are interpreted to show frequent advances of oxygen-rich intermediate water masses into the Arabian Sea originating from the southern ocean. Alkenone-derived SSTs varied between 23 and 28° C. Highest temperatures were encountered during interglacial MIS 5. Rapid SST changes of 2° C magnitude on millennial scale are overlain by long-term SST fluctuations. Interstadials (of glacial phases) and the cold phases of interglacials are characterized by sediments enriched in organic carbon (up to 4 % TOC) whereas sediments with low TOC contents (climate transitions, such as onsets of interstadials, were coeval with changes in productivity-related and anoxia-indicating proxies. Interstadial inorganic elemental data consistently show that enhanced fluxes of terrestrial-derived sediments are paralleled by productivity maxima, and are characterized by an increased fluvial contribution from the Indus River. In contrast, stadials are characterized by an increased contribution of aeolian dust probably from

  11. An Integrated Geochemical and Paleontological Investigation of Environmental and Biotic Change Associated with Late Devonian Mass Extinctions in the Appalachian Basin, USA

    Science.gov (United States)

    Haddad, E.; Love, G. D.; Boyer, D.; Droser, M. L.

    2012-12-01

    The Upper Kellwasser (uK) black shale, a global unit at the Frasnian-Famennian boundary, closely associated with the Late Devonian extinction event, is commonly linked to oxygen limitation in the water column. In spite of the significance of this time interval, the nature of the ocean redox geochemistry is poorly understood. Using a multi-proxy approach, this study tests the appropriateness of three distinct oceanographic models for ocean redox chemistry at this time: 1) an oxic setting with sub-oxic bottom waters but with sulfide production confined to sedimentary porewaters; 2) an expanded oxygen minimum zone within a highly stratified marine redox column with only intermittent photic zone (shallow water) euxinia; and 3) a persistently euxinic water column extending up into the photic zone. Bottom water oxygen conditions are described at a high resolution for 4 uK black shale localities in western New York State, using inorganic and organic geochemical proxies and trace fossils to constrain relative oxygen levels and identify signals of anoxia and euxinia in the Devonian Appalachian Basin. Mo concentrations typically range from crustal (2-3 ppm) to moderately enriched values suggestive of suboxic conditions (typically less than 30 ppm), with some higher values between 30 and 40 ppm perhaps suggesting intermittent euxinia, indicating that the uK black shale preserves reduced oxygen bottom water conditions. The levels of enrichment are muted, though, such that these are inconsistent with persistent anoxia or euxinia for the interval, especially as compared to other Phanerozoic euxinic black shale intervals. Other trace metals suggest similarly suboxic to intermittently anoxic bottom water conditions. Lipid biomarker patterns are typical for Paleozoic marine rocks, indicating that the biomarker molecules in the extracted bitumens are syndepositional and not significantly affected by contamination. Independent thermal maturity screening data indicating peak oil

  12. Supercontinent tectonics and biogeochemical cycle: A matter of 'life and death'

    Institute of Scientific and Technical Information of China (English)

    M. Santosh

    2010-01-01

    The formation and disruption of supercontinents have significantly impacted mantle dynamics, solid earth processes, surface environments and the biogeochemical cycle. In the early history of the Earth, the collision of parallel intra-oceanic arcs was an important process in building embryonic continents. Superdownwelling along Y-shaped triple junctions might have been one of the important processes that aided in the rapid assembly of continental fragments into closely packed supercontinents.Various models have been proposed for the fragmentation of supercontinents including thermal blanket and superplume hypotheses. The reassembly of supercontinents after breakup and the ocean closure occurs through "introversion", "extroversion" or a combination of both, and is characterized by either Pacific-type or Atlantic-type ocean closure. The breakup of supercontinents and development of hydrothermal system in rifts with granitic basement create anomalous chemical environments enriched in nutrients, which serve as the primary building blocks of the skeleton and bone of early modem life forms.A typical example is the rifting of the Rodinia supercontinent, which opened up an N-S oriented sea way along which nutrient enriched upwelling brought about a habitable geochemical environment. The assembly of supercontinents also had significant impact on life evolution. The role played by the Cambrian Gondwana assembly has been emphasized in many models, including the formation of 'Transgondwana Mountains' that might have provided an effective source of rich nutrients to the equatorial waters, thus aiding the rapid increase in biodiversity. The planet has witnessed several mass extinction events during its history, mostly connected with major climatic fluctuations including global cooling and warming events, major glaciations, fluctuations in sea level, global anoxia, volcanic eruptions,asteroid impacts and gamma radiation. Some recent models speculate a relationship between

  13. Linking sediment structure, hydrological functioning and biogeochemical cycling in disturbed coastal saltmarshes and implications for vegetation development

    Science.gov (United States)

    Spencer, Kate; Harvey, Gemma; James, Tempest; Simon, Carr; Michelle, Morris

    2014-05-01

    Saltmarsh restoration undoubtedly provides environmental enhancement, with vegetation quickly re-establishing following the breach of sea walls and subsequent tidal inundation of previously defended areas. Yet evidence increasingly suggests that the restored saltmarshes do not have the same biological characteristics as their natural counterparts (Mossman et al. 2012) and this may be in part be due to physicochemical parameters at the site including anoxia and poor drainage. Hence, restored saltmarshes may not offer the range and quality of ecosystem services anticipated. These environments will have been 'disturbed' by previous land use and there is little understanding of the impacts of this disturbance on the wider hydrogeomorphic and biogeochemical functioning in restored saltmarshes and the implications for saltmarsh vegetation development. This study examines linkages between physical sediment characteristics, sediment structure (using X-ray microtomography), sub-surface hydrology (using pressure transducers and time series analysis), and sediment and porewater geochemistry (major and trace elements, major anions) in sediment cores collected from undisturbed saltmarshes and those restored by de-embankment. Sub-surface sediments in restored saltmarshes have lower organic matter content, lower moisture content and higher bulk density than undisturbed sites. Using X-ray tomography a clear horizon can be observed which separates relict agricultural soils at depth with less dense and structureless sediments deposited since de-embankment. Ratios of open to closed pore space suggest that while undisturbed saltmarshes have the highest porosity, restored saltmarshes have larger void spaces, but limited pore connectivity. Sub-surface hydrological response to tidal flooding was subdued in the restored compared to the undisturbed site, suggesting that porewater flow may be impeded. Time series analysis indicated that flow pathways differ in restored saltmarsh sediments

  14. A novel proxy links CAMP volcanism with end-Triassic mass extinction and early Jurassic evolution

    Science.gov (United States)

    Ruhl, M.; Bjerrum, C. J.; Frei, R.

    2011-12-01

    resolution. End-Triassic changes in biodiversity and extinction and evolution of species is most severe in the marine realm. Reactive iron and trace element data (e.g. Mo, U) suggest strong changes in water column redox-conditions and anoxia and euxinia coinciding with CAMP volcanic activity. This suggests that the end-Triassic mass extinction in the marine realm maybe mostly related to marine anoxia, initiated by volcanism driven greenhouse gas release, in at least marginal marine basins.

  15. Long-term atmospheric oxygen decrease an underestimated factor forcing the Permian-Triassic mass extinction

    Science.gov (United States)

    Weidlich, O.; Kiessling, W.; Flügel, E.

    2003-04-01

    The Permian mass extinction encompasses the end-Guadalupian (Middle Permian) and the end-Lopingian (Late Permian) events, which sum up to the most severe Phanerozoic crisis. Berner (2002) evaluated popular hypotheses explaining the Permian mass extinction and suggested a synergistic combination of causes, notably various short-term perturbations of the carbon cycle and its far-reaching reorganization with a shift of the depo-center from the land to the sea. While massive volcanic eruptions, oceanic CO2-poisoning or anoxia, a bolide impact, and methane release have been considered as abrupt killing mechanisms, there has been little interest in how atmospheric oxygen variations affected the metazoan diversities. Differing from contemporary values of 21%, atmospheric oxygen reached maximum concentrations of about 35% during the late Carboniferous, gradually dropped to minimum concentrations possibly as low as 15% by the end of Permian, and increased during the Triassic to modelled values of about 18% (Berner &Canfield 1989). The possible links of these secular fluctuations to macroevolutionary processes are underexplored, but the stratigraphic coincidence of reconstructed atmospheric oxygen concentrations and biospheric perturbations suggest that this relation may be stronger than admitted. Although feedback mechanisms between decreasing atmospheric oxygen content and metazoan evolution have been ruled out, modern oxygen minimum zone inhabitants, directly respond to oxygen deficiency with opportunistic faunas. We analysed 30 million years Middle Permian to Middle Triassic reef distribution, reef carbonate production as well as reef builder extinction/recovery patterns and compared the results with the modeled atmospheric oxygen concentrations and the extinction data from terrestrial and deep-marine ecosystems. We propose that (i) the Permian double reef crisis resulted from long-term atmospheric O2 depletion in conjunction with abrupt killing mechanisms and that (ii

  16. Magnetic enhancement of Baltic Sea sapropels by greigite magnetofossils

    Science.gov (United States)

    Reinholdsson, M.; Snowball, I.; Zillén, L.; Lenz, C.; Conley, D. J.

    2013-03-01

    Magnetotactic bacteria (MTB) are known to biosynthesise single-domain magnetite (Fe3O4) for geomagnetic navigation and their relict magnetosomes (called magnetofossils) can control the magnetic properties of lake and marine sediments. Magnetotactic bacteria also produce greigite (Fe3S4) magnetosomes but, compared to those made of magnetite, relatively little is known about the sedimentary environments where they are produced and the magnetic properties of the preserved particles. We studied the magnetic properties of sediment cores from two basins (the North Central Baltic Proper and eastern Gotland Basin) that currently experience hypoxia and we discovered the magnetic enhancement of older laminated sapropels, which are a signal of past occurrences of anoxia and hypoxia in the Baltic Sea. Magnetic concentrates extracted from the laminated sapropels were characterised by transmission electron microscopy and energy dispersive X-ray spectrometry and we identified only single-domain greigite (Fe3S4) particles with a mean size of 55×75 nm, which we interpret as magnetofossils due to diagnostic chains of individual particles separated by an intact dividing membrane. The degree of magnetic enhancement in the laminated sapropels has a positive relationship with loss-on-ignition data, which indicates a link between the production of greigite magnetosomes, organic matter supply and preservation and redox conditions. The coercive force of collections of non-interacting greigite magnetofossils is ∼13 mT, which is considerably lower than the magnetite counterparts (∼30 mT) and strictly non-bacterial and larger greigite single-domain grains (∼60 mT). The values of the interparametric ratios of SIRM/χ, χARM/SIRM and χARM/χ that we obtain for our greigite magnetofossils overlap with those previously considered to be diagnostic of magnetosomal magnetite. The presence of bacterial greigite, which is easily detected by magnetic measurements, forms a proxy for hypoxia and

  17. Wide diversity in structure and expression profiles among members of the Caenorhabditis elegans globin protein family

    Directory of Open Access Journals (Sweden)

    Vinogradov Serge

    2007-10-01

    Full Text Available Abstract Background The emergence of high throughput genome sequencing facilities and powerful high performance bioinformatic tools has highlighted hitherto unexpected wide occurrence of globins in the three kingdoms of life. In silico analysis of the genome of C. elegans identified 33 putative globin genes. It remains a mystery why this tiny animal might need so many globins. As an inroad to understanding this complexity we initiated a structural and functional analysis of the globin family in C. elegans. Results All 33 C. elegans putative globin genes are transcribed. The translated sequences have the essential signatures of single domain bona fide globins, or they contain a distinct globin domain that is part of a larger protein. All globin domains can be aligned so as to fit the globin fold, but internal interhelical and N- and C-terminal extensions and a variety of amino acid substitutions generate much structural diversity among the globins of C. elegans. Likewise, the encoding genes lack a conserved pattern of intron insertion positioning. We analyze the expression profiles of the globins during the progression of the life cycle, and we find that distinct subsets of globins are induced, or repressed, in wild-type dauers and in daf-2(e1370/insulin-receptor mutant adults, although these animals share several physiological features including resistance to elevated temperature, oxidative stress and hypoxic death. Several globin genes are upregulated following oxygen deprivation and we find that HIF-1 and DAF-2 each are required for this response. Our data indicate that the DAF-2 regulated transcription factor DAF-16/FOXO positively modulates hif-1 transcription under anoxia but opposes expression of the HIF-1 responsive globin genes itself. In contrast, the canonical globin of C. elegans, ZK637.13, is not responsive to anoxia. Reduced DAF-2 signaling leads to enhanced transcription of this globin and DAF-16 is required for this effect

  18. Interactions of aquaculture and waste disposal in the coastal zone

    Science.gov (United States)

    Xuemei, Zhai; Hawkins, S. J.

    2002-04-01

    Throughout the world, the coastal zones of many countries are used increasingly for aquaculture in addition to other activities such as waste disposal. These activities can cause environmental problems and health problems where they overlap. The interaction between aquaculture and waste disposal, and their relationship with eutrophication are the subjects of this paper. Sewage discharge without adequate dispersion can lead to nutrient elevation and hence eutrophication which has clearly negative effects on aquaculture with the potential for toxic blooms. Blooms may be either toxic or anoxia-causing through the decay process or simply clog the gills of filter-feeding animals in some cases. With the development of aquaculture, especially intensive aquaculture, many environmental problems appeared, and have resulted in eutrophication in some areas. Eutrophication may destroy the health of whole ecosystem which is important for sustainable aquaculture. Sewage discharge may also cause serious public health problems. Filter-feeding shellfish growing in sewage-polluted waters accumulate micro-organims, including human pathogenic bacteria and viruses, and heavy metal ion, presenting a significant health risk. Some farmed animals may also accumulate heavy metals from sewage. Bivalves growing in areas affected by toxic algae blooms may accumulate toxins (such as PSP, DSP) which can be harmful to human beings.

  19. Vulnerability of pejerrey Odontesthes bonariensis populations to climate change in pampean lakes of Argentina.

    Science.gov (United States)

    Kopprio, G A; Freije, R H; Strüssmann, C A; Kattner, G; Hoffmeyer, M S; Popovich, C A; Lara, R J

    2010-11-01

    The vulnerability of the pejerrey Odontesthes bonariensis population in Lake Chasicó was assessed under different climate change conditions. During the sampling period, the water temperature was adequate for fish reproduction and to sustain an adequate sex ratio. Climate-driven higher temperatures, however, may severely distort population structure and cause drastic reduction or local extinction of stocks. Lake Chasicó can be classified as eutrophic with clear waters and cyanobacteria that regularly cause fish mortality were identified as Nodularia spumigena and Oscillatoria sp. Global warming may strengthen the effects of eutrophication (e.g. toxic blooms or anoxia). Since many Cyanophyta species tolerate higher temperatures better than other algae, toxic blooms could increase. Furthermore, cyanobacteria have low nutritional value and could decouple the low-diversity food web. Lake Chasicó has currently the salinity optimum (c. 20) for the development of the early life-history stages of O. bonariensis. Climate change, however, is likely to amplify the intensity of droughts or inundations. Floods can endanger O. bonariensis development due to its sub-optimal growth at low salinity and droughts could increase lake salinity and also temperature and nutrient concentration. In order to reduce some of the effects of climate change on the O. bonariensis population in Lake Chasicó, integrated basin management based on an eco-hydrological approach is proposed. PMID:21078095

  20. Cyanobacteria blooms: effects on aquatic ecosystems.

    Science.gov (United States)

    Havens, Karl E

    2008-01-01

    Cyanobacteria become increasingly dominant as concentrations of TP and TN increase during eutrophication of lakes, rivers and estuaries. Temporal dynamics of cyanobacteria blooms are variable--in some systems persistent blooms occur in summer to fall, whereas in other systems blooms are more sporadic. Cyanobacteria blooms have a wide range of possible biological impacts including potential toxic effects on other algae, invertebrates and fish, impacts to plants and benthic algae due to shading, and impacts to food web function as large inedible algae produce a bottleneck to C and energy flow in the plankton food web. In lakes with dense blooms of cyanobacteria, accumulation of organic material in lake sediments and increased bacterial activity also may lead to anoxic conditions that alter the structure of benthic macro-invertebrates. Diffusive internal P loading may increase, and hypolimnetic anoxia may lead to a loss of piscivorous fish that require a summer cold water refuge in temperate lakes. Ecosystem changes associated with frequent blooms may result in delayed response of lakes, rivers and estuaries to external nutrient load reduction. Despite numerous case studies and a vast literature on species-specific responses, community level effects of cyanobacterial blooms are not well understood--in particular the realized impacts of toxins and changes in food web structure/function. These areas require additional research given the prevalence of toxic blooms in the nation's lakes, rivers and coastal waters--systems that provide a wide range of valued ecosystem services. PMID:18461790

  1. Equatorward phytoplankton migration during a cold spell within the Late Cretaceous super-greenhouse

    Science.gov (United States)

    van Helmond, Niels A. G. M.; Sluijs, Appy; Papadomanolaki, Nina M.; Plint, A. Guy; Gröcke, Darren R.; Pearce, Martin A.; Eldrett, James S.; Trabucho-Alexandre, João; Walaszczyk, Ireneusz; van de Schootbrugge, Bas; Brinkhuis, Henk

    2016-05-01

    Oceanic Anoxic Event 2 (OAE2), a ˜ 600 kyr episode close to the Cenomanian-Turonian boundary (ca. 94 Ma), is characterized by relatively widespread marine anoxia and ranks amongst the warmest intervals of the Phanerozoic. The early stages of OAE2 are, however, marked by an episode of widespread transient cooling and bottom water oxygenation: the Plenus Cold Event. This cold spell has been linked to a decline in atmospheric pCO2, resulting from enhanced global organic carbon burial. To investigate the response of phytoplankton to this marked and rapid climate shift we examined the biogeographical response of dinoflagellates to the Plenus Cold Event. Our study is based on a newly generated geochemical and palynological data set from a high-latitude Northern Hemisphere site, Pratts Landing (western Alberta, Canada). We combine these data with a semi-quantitative global compilation of the stratigraphic distribution of dinoflagellate cyst taxa. The data show that dinoflagellate cysts grouped in the Cyclonephelium compactum-membraniphorum morphological plexus migrated from high to mid-latitudes during the Plenus Cold Event, making it the sole widely found (micro)fossil to mark this cold spell. In addition to earlier reports from regional metazoan migrations during the Plenus Cold Event, our findings illustrate the effect of rapid climate change on the global biogeographical dispersion of phytoplankton.

  2. Ischemia/reperfusion impairs mitochondrial energy conservation and triggers O2.- release as a byproduct of respiration.

    Science.gov (United States)

    Nohl, H; Koltover, V; Stolze, K

    1993-01-01

    The aim of the present study was to elucidate the role of mitochondria in the development of heart failure following ischemia/reperfusion. Although mitochondria were increasingly assumed to be responsible for the establishment of an oxidative stress situation the lack of suitable methods to prove it required new concepts for an evaluation of the validity of this hypothesis. The principal idea was to expose isolated mitochondria to metabolic conditions which are developed during ischemia/reperfusion in the cell (anoxia, lactogenesis) and study how they respond. Heart mitochondria treated in that way responded with an incomplete collapse of the transmembraneous proton gradient, thereby impairing respiration-linked ATP generation. The membrane effect affected also the proper control of e- transfer through redox-cycling ubisemiquinone. Electrons were found to leak at this site from its normal pathway to O2 suggesting that ubisemiquinone becomes an active O2.- generator. It was concluded from these observations that mitochondria are likely to play a pathogenetic role in the reperfusion injury of the heart both, by an impairment of energy conservation and their transition to a potent O2.(-)-radical generator. Furthermore, there is considerable evidence that the exogenous NADH-dehydrogenase of heart mitochondria is mainly responsible for functional changes of these organelles during ischemia/reperfusion. PMID:8319923

  3. Life-history strategies affect aphid preference for yellowing leaves.

    Science.gov (United States)

    Holopainen, Jarmo K; Semiz, Gürkan; Blande, James D

    2009-10-23

    According to the nutrient-translocation hypothesis, yellowing tree leaves are colonized by aphids at the end of the growing season owing to improved availability of nutrients in the phloem sap after chlorophyll degradation. We measured aphid densities on potted Betula pendula seedlings in a field site where a small proportion of foliage rapidly turned yellow before normal autumn coloration as a consequence of root anoxia. The number of adults and nymphs of the birch-feeding specialist aphids Euceraphis betulae, Betulaphis brevipilosa and Callipterinella tuberculata were counted from leaves on each of the 222 plants. Aphids were detected on 19 per cent of green leaves and on 41 per cent of yellow leaves. There was no indication of aphid avoidance of yellow leaves, and the number of winged (alate) viviparous E. betulae adults and their nymphs were significantly higher on yellow leaves than on green leaves, while the numbers of apterous B. brevipilosa and C. tuberculata did not differ between the leaf colour types. Our result suggests that only aphid species with alate generation during colour change can take advantage of yellowing leaves. This may explain the exceptional abundance of E. betulae compared with other aphid species on birches. PMID:19535364

  4. Facilitated transport of Mn2+ in sycamore (Acer pseudoplatanus) cells and excised maize root tips. A comparative 31P n.m.r. study in vivo.

    Science.gov (United States)

    Roby, C; Bligny, R; Douce, R; Tu, S I; Pfeffer, P E

    1988-06-01

    Movement of paramagnetic Mn2+ into sycamore (Acer pseudoplatanus) cells has been indirectly examined by observing the line broadening exhibited in its 31P n.m.r. spectra. Mn2+ was observed to pass into the vacuole, while exhibiting a very minor accumulation in the cytoplasm. With time, gradual leakage of phosphate from the vacuole to the cytoplasm was observed along with an increase in glucose-6-phosphate. Anoxia did not appear to affect the relative distribution of Mn2+ in the cytoplasm and vacuole. Under hypoxic conditions restriction of almost all movement of Mn2+ across the plasmalemma as well as the tonoplast was observed. In contrast, maize root tips showed entry and complete complexation of nucleotide triphosphate by Mn2+ during hypoxia. The rate of passage of Mn2+ across the tonoplast in both sycamore and maize root cells is approximately the same. However, the rates of facilitated movement across the respective plasma membranes appear to differ. More rapid movement of Mn2+ across the plasmalemma in maize root tip cells allows a gradual build-up of metal ion in the cytoplasm prior to its diffusion across the tonoplast. Sycamore cells undergo a slower uptake of Mn2+ into their cytoplasms (comparable with the rate of diffusion through the tonoplast), so little or no observable accumulation of Mn2+ is observed in this compartment.

  5. Establishment of a model for pregnancy-induced hypertension syndrome resuiting from cold-stress in rats

    Institute of Scientific and Technical Information of China (English)

    俞丽丽; 李力; 陈鸣; 吴国萍; 史景泉; 祝之明

    2004-01-01

    Objective: To establish a model for pregnancy-induced hypertension syndrome in rats. Methods: Adult female Wistar rats were randomized into non-pregnant control (NN), non-pregnant cold-stress control (NC), pregnant control (PN) and pregnant cold-stress (PC) groups. The rats of NN and PN groups were put under 25 ℃ and those of NC and PC groups under (4±2) ℃ for 4 h every morning respectively in the whole experimental period. The blood pressure, urine protein, body weight, haematocrit, weight of the placenta and weight and length of the fetus were recorded and the histological changes of the placenta and the kidneys were also studied. Results: The blood pressure and urine protein of the rats of the NC and PC groups after 2 weeks of cold-stress were more significantly increased than the rats of the NN and PN groups. In addition, the weight of the placenta and the weight and length of the fetus were more significantly lower in the former than the latter. Obvious changes of anoxia and ischemia were observed in the tissues of the kidneys and every layer of the placenta.Conclusion: Our findings of hypertension syndrome induced with repeated cold-stress in pregnant rats can be applied to illustrate the pathogenesis of pregnancy-induced hypertension syndrome in human beings.

  6. Guido Bonarelli, explorador y gelogo incansable: pionero en la prospeccin de hidrocarburos en la Argentina

    Directory of Open Access Journals (Sweden)

    Andrea Concheyro

    2011-09-01

    Full Text Available Guido Bonarelli es un personaje relevante en la geologa argentina y constituy uno de los pilares en la exploracin de hidrocarburos de nuestro pas. De origen italiano, naci en Ancona, el 25 de julio de 1871 y falleci en Montereano, el 11 de enero de 1951. Se destac en estratigrafa, relevamiento geolgico, geologa histrica y paleontologa, llegando a ser un especialista en la taxonoma de amonites jursicos y la estratigrafa de los Apeninos Centrales. Su tarea profesional comenz en Italia y sigui en el sudeste asitico, Amrica del Sur, Bolivia, Chile, Argentina y Uruguay. Entre 1911 y 1918, trabaj en la Direccin General de Minas, Geologa e Hidrografa de la Repblica Argentina. Defini las Sierras Subandinas como un complejo orogrfico trascendente y estableci la localizacin de yacimientos de petrleo y gas natural. Realiz investigaciones tambin en numerosas provincias argentinas y el litoral pacfico de Chile. Durante su segundo periodo de investigaciones (1923-1927, Guido Bonarelli organiz la seccin Geologa de Yacimientos Petrolferos Fiscales y desarroll la prospeccin de hidrocarburos en el noroeste argentino, Mendoza, Neuqun y Comodoro Rivadavia. Gener un ncleo de colaboradores, que se ocuparon de intensificar los estudios geolgicos con fines exploratorios en el pas. Curiosamente Bonarelli en 1891 descubri un horizonte sedimentario que posee enorme importancia, utilizado como nivel de referencia para caracterizar el evento de anoxia global del Cenomaniano-Turoniano. Dicho horizonte conocido mundialmente como Livello Bonarelli rinde un homenaje pstumo a su descubridor.

  7. THE MAIN NUTRIENTS CONCENTRATION FROM INTRA TISSUE WATER OF BENTHOS ORAGANISMS FROM MURES BASIN

    Directory of Open Access Journals (Sweden)

    DANA POPA

    2013-12-01

    Full Text Available In the hydrographic basin of Mures river, aboard an altitude gradient, were taken samples of intra tissue waters from benthonic organisms for research the nutrients concentrations. The reference point was represented by a dairy caw farm where the agricultural fields of this is applied the organic fertilization with manure. The intra tissue water samples from benthonic organisms were prelevated in spring and autumn and the prelevate dates are the same with spread manure dates. At the intra tissue water level, concentrations value of N and P are bigger at the second data prelevations than first data prelevations and we can conclude that the benthonic oligochetas activity increase, more than, they density increase in Mures basin. The high concentrations of NH4 show as that Mures basin is a zone characterized by high degree of anoxia and this fact is supported by significant differences between seasonal prelevations. The explication is the manifestation to the cumulated and at distance effects of introduction in water to some organic products, very probably washed from neighborhoods agricultural field. Were calculated values of Student test for seasonal comparisons and were founded significant differences between nutrients concentration values at first and second prelevations.

  8. Seasonal stratification and property distributions in a tropical estuary (Cochin estuary, west coast, India)

    Science.gov (United States)

    Shivaprasad, A.; Vinita, J.; Revichandran, C.; Reny, P. D.; Deepak, M. P.; Muraleedharan, K. R.; Naveen Kumar, K. R.

    2013-01-01

    The intratidal, spring-neap and seasonal variations in stratification were examined in the Cochin estuary. The observations established a strong connection with the distribution of chemical and biological properties. The influence of tides and river discharge forcing in water column stability was quantified using potential energy anomaly (PEA) and stratification parameter. Partially mixed (neap) and well-mixed (spring) conditions during low river discharge (dry) period were altered in monsoon by the salt wedge intrusions. The ecological impact of salt wedge propagation on high tides bringing upwelled water to the system was evident from the bottom hypoxic, high chlorophyll a and nutrient-rich conditions. Phosphate and nitrite concentrations were higher at the bottom saline conditions but silicate and nitrate were clearly supplied by river water. However, during ebb tide this front was driven out of the estuary. The periodic advance and retreat of the salt wedge was inevitable in making the system immune from extended hypoxia/anoxia and maintaining the health of the Cochin estuary. For the seasonally varying river flow in the estuary, salt intrusion receded with increasing river flow in monsoon and rebounded with decreasing river flow in dry season. During monsoon, the intense flushing and reduction in salinity field expansion seemed to be responsible for the limited chlorophyll a levels along the surface of the Cochin estuary.

  9. Brain SPECT in childhood; Temp cerebrale chez l'enfant

    Energy Technology Data Exchange (ETDEWEB)

    Tranquart, F.; Saliba, E.; Prunier, C.; Baulieu, F.; Besnard, J.C.; Guilloteau, D.; Baulieu, J.L. [Hopital Bretonneau, Service de Medecine Nucleaire, Unite Inserm 316, 37 - Tours (France)

    2001-04-01

    The modalities and the indications of perfusion and neurotransmission SPECT in childhood are presented. The perfusion as well as neurotransmission tracers have not yet authorization for use in children; they have to be used by prescription of magistral preparation or in research protocols. The radioprotection rules have to be strictly respected. The most frequent indication of perfusion SPECT is pharmacologically resistant epilepsy; the ictal SPECT before surgery allows the localization of the epileptogenic focus. Other indications are relevant in the prognosis of neonatal anoxia and encephalitis. In psychiatric disorders, especially in autism, the interest is the physiopathological approach of the brain dysfunctions. The neurotransmission SPECT is emerging as a consequence of the development of new radiotracer, as the dopaminergic system ligands. The decrease of the dopamine D2 receptors in the striatum can be imaged and quantified in the neonate. The lesions of dopamine system seem to be a consequence of the neonatal hypoxia-ischemia and it is predictive of motor sequelae. Brain SPECT should become a routine examination in child neurologic and psychiatric disorders. (authors)

  10. Ichnological record of the Frasnian-Famennian boundary interval: two examples from the Holy Cross Mts (Central Poland)

    Science.gov (United States)

    Stachacz, Michał; Uchman, Alfred; Rodríguez-Tovar, Francisco J.

    2016-03-01

    The Frasnian-Famennian (Late Devonian) boundary interval within the carbonate-siliciclastic series in the Kowala and Płucki sections (Holy Cross Mts, Central Poland) has been analysed to evaluate the influence of the Kellwasser event on the macrobenthic tracemaker community. The Upper Kellwasser event has a lithologically variable record, as horizons of flints (Kowala) and as a bed of bituminous, black, cephalopod limestone (Płucki). Both sections show mostly laminated, unbioturbated beds of marlstones or shales just above the Frasnian-Famennian boundary, which point to events of anoxia on the sea floor. However, the first anoxic horizon occurs below the Frasnian-Famennian boundary. The trace fossils and bioturbational structures are uncommon and poorly diversified. Trichichnus and Multina are the only frequent trace fossils in some beds. Moreover, one horizon above the Frasnian-Famennian boundary contains numerous Multina and a single ?Planolites. Such poorly diversified trace fossil assemblage suggests an unfavourable environment for most of burrowing organisms and fluctuations in oxygenation from anoxic, to dysoxic conditions. The occurrence of the trace fossils and bioturbational structures as spotted and mottled ichnofabrics from the 1.3 m above the Frasnian-Famennian boundary is interpreted as an improvement in bottom water oxygen conditions after the Upper Kellwasser event.

  11. Progress of burn research in metabolism and nutrition in China%我国烧伤代谢营养研究

    Institute of Scientific and Technical Information of China (English)

    汪仕良

    2008-01-01

    The achievements of burn metabolism and nutrition in China are briefly presented. Advance a new theory "Enterogenous Hypermetabolism". Develop a formula to calculate calorie needs in Chinese burn adults. Put forward new ideas on glucose absorption, neoglycogenesis, insulin resistance, and the use of hypoglycemic agent after burn inury. Observe the variation of plasma level of free aminoacids, investigate the changes and mechanisms of 26S proteasome and 19S regulator in skeletal muscle of burn trauma, and the clinical application and its mechanism of glutamine and arginine. Introduce the approach of 13 C NMR spectroscopy to investigate the alterations of hepatic anabolism functions in severely burned rats. Offer supplying the suitable dosage of vitamin A,C,E and microeiement of zinc, copper, ferrum for burn patients. Carry out serial studies of early enteral and parenteral nutrition, and compare enteral nutrition with parenteral nutrition. Early ehteral nutrition with synbiotics might be beneficial to the controlling of burn infection. Both glucagon like peptide-2(GLP-2) and intestinal trefoil factor(ITF) exhibit protective effect on intestinal mucosa in minimizing injury and protecting barrier function. The choice of suitable opportunity to use rhGH (growth hormone) is investigated. In addition, advance the view points of isehemia and anoxia in metabolism, anti-inflammatory immune and nutrition.

  12. Mass extinction of the marine biota at the Ordovician-Silurian transition due to environmental changes

    Science.gov (United States)

    Barash, M. S.

    2014-11-01

    The terminal Ordovician was marked by one of five great mass extinction events of the Phanerozoic (445.6-443.0 Ma ago), when up to 86% of the marine species became extinct. The rapid onset of the continental glaciation on Gondwana determined by its position in the South Pole area; the cooling; the hydrodynamic changes through the entire water column in the World Ocean; and the corresponding sea level fall, which was responsible for the reduction of shelf areas and shallow-water basins, i.e., the main ecological niche of the Ordovician marine biota, were main prerequisites of the stress conditions. Similar to other mass extinction events, these processes were accompanied by volcanism, impact events, a corresponding reduction of the photosynthesis and bioproductivity, the destruction of food chains, and anoxia. The appearance and development of terrestrial plants and microphytoplankton, which consumed atmospheric carbon dioxide, thus, diminishing the greenhouse effect and promoting the transition of the climatic system to the glacial mode, played a unique role in that period.

  13. Reductive off-odors in wines: Formation and release of H₂S and methanethiol during the accelerated anoxic storage of wines.

    Science.gov (United States)

    Franco-Luesma, Ernesto; Ferreira, Vicente

    2016-05-15

    In order to better understand the processes involved in the development of H2S and methanethiol (MeSH) along anoxic storage of wines, 24 wines were stored in strict anoxia at 50°C for 3weeks. Free and total forms of H2S and MeSH were measured at different times. Results showed that: (1) all wines contain relevant proportions of bonded forms of H2S and MeSH (93% and 47% on average); (2) such % decreases with age; (3) levels of total forms are related to wine metal composition; (4) anoxic storage brings about an increase of free forms, a strong decrease in the percentage of bonded forms, and except for H2S in red wines, an increase in total forms. Both de novo formation and release contribute to reductive off-odors. Release is predominant for reds and H2S, while at 50°C, de novo formation dominates for whites and rosés and MeSH.

  14. Transcriptional Coactivator and Chromatin Protein PC4 Is Involved in Hippocampal Neurogenesis and Spatial Memory Extinction.

    Science.gov (United States)

    Swaminathan, Amrutha; Delage, Hélène; Chatterjee, Snehajyoti; Belgarbi-Dutron, Laurence; Cassel, Raphaelle; Martinez, Nicole; Cosquer, Brigitte; Kumari, Sujata; Mongelard, Fabien; Lannes, Béatrice; Cassel, Jean-Christophe; Boutillier, Anne-Laurence; Bouvet, Philippe; Kundu, Tapas K

    2016-09-23

    Although the elaborate combination of histone and non-histone protein complexes defines chromatin organization and hence regulates numerous nuclear processes, the role of chromatin organizing proteins remains unexplored at the organismal level. The highly abundant, multifunctional, chromatin-associated protein and transcriptional coactivator positive coactivator 4 (PC4/Sub1) is absolutely critical for life, because its absence leads to embryonic lethality. Here, we report results obtained with conditional PC4 knock-out (PC4(f/f) Nestin-Cre) mice where PC4 is knocked out specifically in the brain. Compared with the control (PC4(+/+) Nestin-Cre) mice, PC4(f/f) Nestin-Cre mice are smaller with decreased nocturnal activity but are fertile and show no motor dysfunction. Neurons in different areas of the brains of these mice show sensitivity to hypoxia/anoxia, and decreased adult neurogenesis was observed in the dentate gyrus. Interestingly, PC4(f/f) Nestin-Cre mice exhibit a severe deficit in spatial memory extinction, whereas acquisition and long term retention were unaffected. Gene expression analysis of the dorsal hippocampus of PC4(f/f) Nestin-Cre mice revealed dysregulated expression of several neural function-associated genes, and PC4 was consistently found to localize on the promoters of these genes, indicating that PC4 regulates their expression. These observations indicate that non-histone chromatin-associated proteins like PC4 play a significant role in neuronal plasticity.

  15. Development of an oximeter for neurology

    Science.gov (United States)

    Aleinik, A.; Serikbekova, Z.; Zhukova, N.; Zhukova, I.; Nikitina, M.

    2016-06-01

    Cerebral desaturation can occur during surgery manipulation, whereas other parameters vary insignificantly. Prolonged intervals of cerebral anoxia can cause serious damage to the nervous system. Commonly used method for measurement of cerebral blood flow uses invasive catheters. Other techniques include single photon emission computed tomography (SPECT), positron emission tomography (PET), magnetic resonance imaging (MRI). Tomographic methods frequently use isotope administration, that may result in anaphylactic reactions to contrast media and associated nerve diseases. Moreover, the high cost and the need for continuous monitoring make it difficult to apply these techniques in clinical practice. Cerebral oximetry is a method for measuring oxygen saturation using infrared spectrometry. Moreover reflection pulse oximetry can detect sudden changes in sympathetic tone. For this purpose the reflectance pulse oximeter for use in neurology is developed. Reflectance oximeter has a definite advantage as it can be used to measure oxygen saturation in any part of the body. Preliminary results indicate that the device has a good resolution and high reliability. Modern applied schematics have improved device characteristics compared with existing ones.

  16. Influence of selected abiotic factors on the decomposition of chlorophylls

    Directory of Open Access Journals (Sweden)

    Gra¿yna Kowalewska

    2001-09-01

    Full Text Available The paper presents the results of experiments to determine the influence of selected physico-chemical factors - oxygen, visible light and temperature - on the decomposition of (1 chlorophylls a, b and c, chlorophyll a derivatives and beta-carotene in acetone solution, and (2 chlorophyll a and beta-carotene in axenic cultures of the blue-green algae Anabaena variabilis. The results indicate that both in acetone extracts and in blue-green algae cultures these pigments were most sensitive to light and oxygen; temperatures of up to 25oC had no marked influence on these compounds. Under anoxia in acetone solution, the stability towards light decreased in the order chlorophyll a, chlorophyll b, chlorophylls c. Chlorophyll a, moreover, was less stable than its derivatives - phaeophorbides, phaeophytins, pyrophaeophytins and steryl chlorins - but more stable than beta-carotene, in the last case also in the blue-green algae cultures. Decomposition of all the pigments proceeded mainly via the breakdown of the porphyrin macrocycle, since the decomposition products were not detected in the VIS range. On the basis of these experiments one can state that while light and oxygen may have a decisive direct influence on the distribution of chlorophylls and beta-carotene in sediments, in the natural environment, temperatures of up to 25oC may have very little immediate effect.

  17. Modulated expression and enzymatic activities of Darkbarbel catfish, Pelteobagrus vachelli for oxidative stress induced by acute hypoxia and reoxygenation.

    Science.gov (United States)

    Zhang, Guosong; Mao, Jianqiang; Liang, Fenfei; Chen, Jiawei; Zhao, Cheng; Yin, Shaowu; Wang, Li; Tang, Zhonglin; Chen, Shuqiao

    2016-05-01

    Large changes in oxygen availability in aquatic environments, ranging from anoxia through to hyperoxia, can lead to corresponding wide variation in the production of reactive oxygen species (ROS) by fish with aquatic respiration. In order to evaluate the effects of hypoxia and reoxygenation on oxidative stress in fish, the mRNA and protein expression of SODs (Cu/Zn-SOD and Mn-SOD) as well as indices (CP, LPO and MDA) and enzymatic activities (SOD, CAT, GPx, GR and GST) were analyzed in liver and brain tissues of Pelteobagrus vachelli. Predominant expression of PvSOD2 was detected in heart, brain, and liver. In contrast, PvSOD1 was highly expressed in liver. Based on the expression patterns of above parameters, we inferred that brain tissue of P. vachelli under 0.7 mg/L degree of acute hypoxia condition could experience hypometabolic states or no suffering stress, but brain tissue has effective mechanisms to minimize or prevent oxidative stress during the transition from hypoxia to reoxygenation. Our results also demonstrated an increased expression of SODs and enzymatic activities for oxidative stress in liver under hypoxic conditions, which supports the hypothesis that anticipatory preparation takes place in order to deal with the encountered oxidative stress during the recovery from hypoxia as proposed by M. Hermes-Lima. Therefore, this study will provide a clue to better understand the action mode of antioxidant genes and enzymes under oxidative stress in fish. PMID:26945243

  18. MR and CT imaging patterns in post-varicella encephalitis

    Energy Technology Data Exchange (ETDEWEB)

    Darling, C.F. [Div. of Neuroimaging, Children`s Memorial Center, Northwestern Univ. Medical School, Chicago, IL (United States); Larsen, M.B. [Div. of Neurology, Children`s Memorial Center, Northwestern Univ. Medical School, Chicago, IL (United States); Byrd, S.E. [Div. of Neuroimaging, Children`s Memorial Center, Northwestern Univ. Medical School, Chicago, IL (United States); Radkowski, M.A. [Div. of Neuroimaging, Children`s Memorial Center, Northwestern Univ. Medical School, Chicago, IL (United States); Palka, P.S. [Div. of Neuroimaging, Children`s Memorial Center, Northwestern Univ. Medical School, Chicago, IL (United States); Allen, E.D. [Div. of Neuroimaging, Children`s Memorial Center, Northwestern Univ. Medical School, Chicago, IL (United States)

    1995-06-01

    The aim of the investigation was to determine the patterns of cerebral involvement on computed tomography (CT) and magnetic resonance (MR) imaging in post-varicella encephalitis. Four children between the ages of 2 and 11 years presented over a 5-year period with a diagnosis of post-varicella encephalitis. Their imaging studies and clinical data were reviewed retrospectively. The medical histories of all four children were noncontributory except for recent bouts of chickenpox 1 week to 3 months prior to hospitalization. Three children presented with parkinsonian manifestations. Bilateral, symmetric hypodense, nonenhancing basal ganglia lesions were found on CT. These areas showed nonenhancing low signal intensity on T1-weighted images and high signal intensity on T2-weighted images on MR. One child presented with diffuse, multiple gray and white matter lesions of similar imaging characteristics; some lesions, however, did enhance. This child had no gait disturbances. Post-varicella encephalitis can produce two patterns of dramatic CT and MR findings. With an appropriate history and clinical findings, varicella as a cause of bilateral basal ganglia or diffuse cerebral lesions can be differentiated from other possible etiologies which include trauma, anoxia, metabolic disorders and demyelinating diseases. (orig.)

  19. Early monitoring of PtiO2, PtiCO2, pH and brain temperat ure in patients with brain injuries and the clinical significanc e

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Objective: To explore the regulation of early br ain tissue metabolic changing after brain injuries and the clinical significance .   Methods: There were 17 patients with brain injuries. Early dire ct monitoring of PtiO2, PtiCO2, pH and brain temperature, dynami c observation of the relation between various parameters and clinics after brai n injuries were performed.   Results: Early changes of PtiO2, PtiCO2 and pH we re closely correlated with outcome. The death rate obviously increased when P tiO2 was continuously lower than 9 mm?Hg within 24 hours after injuries. Secondary brain injury prolonged and aggravated brain tissue metabolic disturban ce. When intracerebral pressure was over 30 mm?Hg PtiO2 began to de crea se. The brain temperature in brain death patients was evidently lower than axill ary temperature.   Conclusions: The direct monitoring of PtiO2, PtiC O2, pH and brain temperature is safe and accurate and can find early anoxia da mage to brain tissue and provide reliable basis for clinical therapy. It ha s an instructive significance in selecting and studying a new treatment method i n brain injuries. And it can be taken as a criterion in clinical judging brain d eaths.

  20. High resolution integrated study of microfossil assemblages in Sapropel S1, S3 and S5: preliminary results

    Science.gov (United States)

    Negri, Alessandra; Morigi, Caterina; Sangiorgi, Francesca; Keller, Joerg

    2016-04-01

    The Eastern Mediterranean late Neogene to Quaternary sedimentary record is characterized by the widespread and distinctly periodical occurrence of organic carbon-rich layers, called sapropels. The deposition of sapropels is related to significant changes in climate, in the pattern of water circulation and in the biogeochemical cycles. The primary cause triggering the formation of sapropels has been debated ever since their discovery: productivity in the surface waters and organic matter preservation at the sea-floor due to hypoxia or anoxia have been indicated as the two major contributing factors operating either separately or combined. Moreover, each sapropel seems to have its own peculiar feature, likely attributed to the different climate forcing and the different response of productivity and preservation to the water column parameters. Here we present preliminary data from core M25/4 12, located in the Ionian Sea, containing a continuous record of the sapropels deposited in the last 330 ka (S1 to S10, excluding S2). We analysed the microfossil assemblages in sapropels S1 (10 ka BP), S3 (80 ka BP) and S5 (125 ka BP) at a multi-centennial time resolution to get insights into the climatic and oceanographical features leading to their deposition and the role of productivity and preservation.

  1. A Hypoxia-Regulated Adeno-Associated Virus Vector for Cancer-Specific Gene Therapy

    Directory of Open Access Journals (Sweden)

    Hangjun Ruan

    2001-01-01

    Full Text Available The presence of hypoxic cells in human brain tumors is an important factor leading to resistance to radiation therapy. However, this physiological difference between normal tissues and tumors also provides the potential for designing cancer-specific gene therapy. We compared the increase of gene expression under anoxia (<0.01% oxygen produced by 3, 6, and 9 copies of hypoxia-responsive elements (HRE from the erythropoietin gene (Epo, which are activated through the transcriptional complex hypoxia-inducible factor 1 (HIF-1. Under anoxic conditions, nine copies of HIRE (9XHRE yielded 27- to 37-fold of increased gene expression in U-251 MG and U-87 MG human brain tumor cell lines. Under the less hypoxic conditions of 0.3% and 1% oxygen, gene activation by 9XHRE increased expression 11- to 18-fold in these cell lines. To generate a recombinant adeno-associated virus (rAAV in which the transgene can be regulated by hypoxia, we inserted the DNA fragment containing 9XHRE and the LacZ reporter gene into an AAV vector. Under anoxic conditions, this vector produced 79- to 110-fold increase in gene expression. We believe this hypoxia-regulated rAAV vector will provide a useful delivery vehicle for cancer-specific gene therapy.

  2. Reversible and non-reversible enlargement of cerebral spinal fluid spaces in anorexia nervosa

    International Nuclear Information System (INIS)

    Brain CT studies of 35 patients with anoxia nervosa confirmed the observations of other authors: cerebral dystrophic changes correlate with weight loss and the reversibility of these changes also correlates with the normalization of body weight. Other corroborated facts are: the most numerous and most pronounced enlargements are of the cortical sulci and the interhemispheric fissure, moderate widening affects the ventricles and the rarest and most insignificant changes are those of the cerebellum. The reversibility of the changes showed a parallel to the extent of the changes themselves and to the duration of improvement of the body weight. The reversibility of the enlargement of the cortical sulci and of the distances between the frontal horns of the lateral ventricles was more often significant than that of the abnormal measurements of the cella media. This difference is based on minimal early acquired brain damage which occurs in 60% of our patients. This high incidence of early acquired minimal brain disease in patients with anorexia nervosa is here discussed as a nonspecific predisposing factor. Although there is no exact explanation of the etiology of the reversible enlargement of cerenral spinal fluid (CSF) spaces in anorexia nervosa, the changes resemble those in alcoholics. The mechanisms of brain changes in alcoholism, as shown experimentally, seem to us to throw light on the probable mechanism of reversible dystrophic brain changes in anorexia nervosa. (orig.)

  3. Influence of environmental factors on mercury release in hydroelectric reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, K.; Therien, N.

    1991-04-01

    Due to increased mercury concentrations in fish in hydro-electric reservoirs after flooding, a study was carried out to evaluate the release and transformation of mercury due to vegetation and soil flooded as a result of reservoir creation. Samples of vegetation and soils were immersed in water and concentrations of total mercury, methylmercury and nutrients were followed. The effects of anoxia, pH and temperature on release and transformation were examined. An existing dynamic model of decomposition of flooded materials in reservoirs was modified to include mercury release and transformation, and was calibrated to the experimental data. Amounts of mercury released by the different substrates was of the same order of magnitude. Tree species contributed to the greatest amounts of methylmercury per unit biomass, but the biomass used for these was twigs and foliage. Soil released significant amounts of mercury, but methylation was very low. The model was able to fit well for all substrates except lichen. The model can be adapted to proposed reservoirs to predict nutrient and mecury release and transformation. 175 refs., 38 figs., 38 tabs.

  4. Kinetic modeling of light limitation and sulfur deprivation effects in the induction of hydrogen production with Chlamydomonas reinhardtii: Part I. Model development and parameter identification.

    Science.gov (United States)

    Fouchard, Swanny; Pruvost, Jérémy; Degrenne, Benoit; Titica, Mariana; Legrand, Jack

    2009-01-01

    Chlamydomonas reinhardtii is a green microalga capable of turning its metabolism towards H2 production under specific conditions. However this H2 production, narrowly linked to the photosynthetic process, results from complex metabolic reactions highly dependent on the environmental conditions of the cells. A kinetic model has been developed to relate culture evolution from standard photosynthetic growth to H2 producing cells. It represents transition in sulfur-deprived conditions, known to lead to H2 production in Chlamydomonas reinhardtii, and the two main processes then induced which are an over-accumulation of intracellular starch and a progressive reduction of PSII activity for anoxia achievement. Because these phenomena are directly linked to the photosynthetic growth, two kinetic models were associated, the first (one) introducing light dependency (Haldane type model associated to a radiative light transfer model), the second (one) making growth a function of available sulfur amount under extracellular and intracellular forms (Droop formulation). The model parameters identification was realized from experimental data obtained with especially designed experiments and a sensitivity analysis of the model to its parameters was also conducted. Model behavior was finally studied showing interdependency between light transfer conditions, photosynthetic growth, sulfate uptake, photosynthetic activity and O2 release, during transition from oxygenic growth to anoxic H2 production conditions.

  5. Environmental Conditions in a Carpathian Deep Sea Basin During the Period Preceding Oceanic Anoxic Event 2 - A Case Study from the Skole Nappe

    Directory of Open Access Journals (Sweden)

    Bąk Krzysztof

    2015-01-01

    Full Text Available Hemipelagic green clayey shales and thin muddy turbidites accumulated in a deep sea environment below the CCD in the Skole Basin, a part of the Outer Carpathian realm, during the Middle Cenomanian. The hemipelagites contain numerous radiolarians, associated with deep-water agglutinated foraminifera. These sediments accumulated under mesotrophic conditions with limited oxygen concentration. Short-term periodic anoxia also occurred during that time. Muddy turbidity currents caused deposition of siliciclastic and biogenic material, including calcareous foramini-fers and numerous sponge spicules. The preservation and diversity of the spicules suggests that they originate from disarticulation of moderately diversified sponge assemblages, which lived predominantly in the neritic-bathyal zone. Analyses of radiolarian ecological groups and pellets reflect the water column properties during the sedimentation of green shales. At that time, surface and also intermediate waters were oxygenated enough and sufficiently rich in nutri-ents to enable plankton production. Numerous, uncompacted pellets with nearly pristine radiolarian skeletons inside show that pelletization was the main factor of radiolarian flux into the deep basin floor. Partly dissolved skeletons indicate that waters in the Skole Basin were undersaturated in relation to silica content. Oxygen content might have been depleted in the deeper part of the water column causing periodic anoxic conditions which prevent rapid bacterial degra-dation of the pellets during their fall to the sea floor.

  6. Expression of Angiogenic Factors in Hepatocellular Carcinoma after Transcatheter Arterial Chemoembolization

    Institute of Scientific and Technical Information of China (English)

    廖晓锋; 易继林; 李兴睿; 杨志芳; 邓巍; 田耕

    2003-01-01

    In order to investigate the changes of vascular endothelial growth factor (VEGF) andbasic fibroblast growth factor (bFGF) expression in residual hepatocellular carcinoma (HCC) aftertranscatheter arterial chemoembolization (TACE), the expression levels of VEGF and bFGF ex-pression in specimens surgically removed from 48 HCC patients were detected by immunohisto-chemical methods, and staining intensity of VEGF and bFGF was assessed by a computer-assistedimage-analyzer. Among the 48 patients, 25 underwent partial hepatectomy alone (single operatinggroup), and 23 were subjected to second stage surgical resection after TACE (TACE group) Theresults showed that the average absorbancevalue (A) of VEGF was higher in TACE group thanthat in single operating group (0. 152±0. 021 vs 0. 131±0. 012, P<0.01). The Average A of bF-GF in TACE group was 0. 127±0. 023, higher than in single operating group (0. 111±0. 016, P<0. 05). These results suggested that TACE of HCC can up-regulate the expression of VEGF andbFGF in HCC tissues possibly due to anoxia and ischemia.

  7. Role of oxygen in resuscitation

    Energy Technology Data Exchange (ETDEWEB)

    Bokeriya, L.A.; Sokolova, N.A.; Konikova, A.S.

    At the present time, improvement of the system of medical care of cosmonauts is an important problem. For this reason, there are plans for development of a set of resuscitation measures that would be necessary in the case of onset of acute hypoxic and anoxic states, which may occur in sudden emergency situations. The purpose of the experiment was to examine the mechanism of transition from life to death on the molecular level. Renewal of proteins and nucleic acids, and change in their conformation (spatial arrangement) were used as the main indicators of changes in metabolic processes in case of death due to anoxic anoxia (exsanguination). With this procedure it was possible to reflect some patterns of biopolymer conversions related to processes of dying and resuscitation. Processes examined were the intensity of synthesis and dissociation of proteins and nucleic acids in the basic organs and tissues of experimental animals: different parts of the brain, myocardium and skeletal muscles, liver, kidneys, lung, spleen, adrenals, thyroid and pancreas, blood, bile and urine.

  8. Kinetic modeling of light limitation and sulfur deprivation effects in the induction of hydrogen production with Chlamydomonas reinhardtii. Part II: Definition of model-based protocols and experimental validation.

    Science.gov (United States)

    Degrenne, B; Pruvost, J; Titica, M; Takache, H; Legrand, J

    2011-10-01

    Photosynthetic hydrogen production under light by the green microalga Chlamydomonas reinhardtii was investigated in a torus-shaped PBR in sulfur-deprived conditions. Culture conditions, represented by the dry biomass concentration of the inoculum, sulfate concentration, and incident photon flux density (PFD), were optimized based on a previously published model (Fouchard et al., 2009. Biotechnol Bioeng 102:232-245). This allowed a strictly autotrophic production, whereas the sulfur-deprived protocol is usually applied in photoheterotrophic conditions. Experimental results combined with additional information from kinetic simulations emphasize effects of sulfur deprivation and light attenuation in the PBR in inducing anoxia and hydrogen production. A broad range of PFD was tested (up to 500 µmol photons m(-2) s(-1) ). Maximum hydrogen productivities were 1.0 ± 0.2 mL H₂ /h/L (or 25 ± 5 mL H₂ /m(2) h) and 3.1 mL ± 0.4 H₂ /h L (or 77.5 ± 10 mL H₂ /m(2) h), at 110 and 500 µmol photons m(-2) s(-1) , respectively. These values approached a maximum specific productivity of approximately 1.9 mL ± 0.4 H₂ /h/g of biomass dry weight, clearly indicative of a limitation in cell capacity to produce hydrogen. The efficiency of the process and further optimizations are discussed.

  9. How electroshock weapons kill!

    Science.gov (United States)

    Lundquist, Marjorie

    2010-03-01

    Growing numbers of law enforcement officers now carry an electroshock weapon (ESW). Over 500 U.S. deaths have followed ESW use in the past 26 years; over 450 of these deaths followed use of an electromuscular disruptor in the past 9 years. Most training courses teach that ESWs are safe; that they can kill only by the direct effect of electric current on the heart; and that a death following use of an ESW always has some other cause. All these teachings are false! The last was disproved by Lundquist.^1 Williams^2 ruled out direct electrical effects as a cause of almost all the 213 deaths he studied, leaving disruption of normal physiological processes as the only alternative explanation. Careful study of all such deaths identifies 4 different ways that death has or could have been brought about by the ESW: kidney failure following rhabdomyolysis [rare]; cardiac arrest from hyperkalemia following rhabdomyolysis [undocumented]; lactic acid-induced ventricular fibrillation [conclusive proof impossible]; and [most common] anoxia from so much lactic acid in the circulating blood that it acts as an oxygen scavenger, continuously depleting the blood of oxygen until most of the lactate has been metabolized. ^1M. Lundquist, BAPS 54(1) K1.270(2009). ^2Howard E. Williams, Taser Electronic Control Devices and Sudden In-Custody Death, 2008.

  10. Perinatal asphyxia reduces dentate granule cells and exacerbates methamphetamine-induced hyperlocomotion in adulthood.

    Directory of Open Access Journals (Sweden)

    Tomoyasu Wakuda

    Full Text Available BACKGROUND: Obstetric complications have been regarded as a risk factor for schizophrenia later in life. One of the mechanisms underlying the association is postulated to be a hypoxic process in the brain in the offspring around the time of birth. Hippocampus is one of the brain regions implicated in the late-onset dopaminergic dysfunction associated with hypoxic obstetric complications. METHODOLOGY/PRINCIPAL FINDINGS: We used an animal model of perinatal asphyxia, in which rat pups were exposed to 15 min of intrauterine anoxia during Cesarean section birth. At 6 and 12 weeks after birth, the behavior of the pups was assessed using a methamphetamine-induced locomotion test. In addition, the histopathology of the hippocampus was examined by means of stereology. At 6 weeks, there was no change in the methamphetamine-induced locomotion. However, at 12 weeks of age, we found an elevation in methamphetamine-induced locomotor activity, which was associated with an increase of dopamine release in the nucleus accumbens. At the same age, we also found a reduction of the dentate granule cells of the hippocampus. CONCLUSIONS/SIGNIFICANCE: These results suggest that the dopaminergic dysregulation after perinatal asphyxia is associated with a reduction in hippocampal dentate granule cells, and this may partly contribute to the pathogenesis of schizophrenia.

  11. Reversible and non-reversible enlargement of cerebral spinal fluid spaces in anorexia nervosa

    Energy Technology Data Exchange (ETDEWEB)

    Artmann, H.; Grau, H.; Adelmann, M.; Schleiffer, R.

    1985-07-01

    Brain CT studies of 35 patients with anoxia nervosa confirmed the observations of other authors: cerebral dystrophic changes correlate with weight loss and the reversibility of these changes also correlates with the normalization of body weight. Other corroborated facts are: the most numerous and most pronounced enlargements are of the cortical sulci and the interhemispheric fissure, moderate widening affects the ventricles and the rarest and most insignificant changes are those of the cerebellum. The reversibility of the changes showed a parallel to the extent of the changes themselves and to the duration of improvement of the body weight. The reversibility of the enlargement of the cortical sulci and of the distances between the frontal horns of the lateral ventricles was more often significant than that of the abnormal measurements of the cella media. This difference is based on minimal early acquired brain damage which occurs in 60% of our patients. This high incidence of early acquired minimal brain disease in patients with anorexia nervosa is here discussed as a nonspecific predisposing factor. Although there is no exact explanation of the etiology of the reversible enlargement of cerenral spinal fluid (CSF) spaces in anorexia nervosa, the changes resemble those in alcoholics. The mechanisms of brain changes in alcoholism, as shown experimentally, seem to us to throw light on the probable mechanism of reversible dystrophic brain changes in anorexia nervosa.

  12. Growth and Physiological Responses to Water Depths in Carex schmidtii Meinsh.

    Directory of Open Access Journals (Sweden)

    Hong Yan

    Full Text Available A greenhouse experiment was performed to investigate growth and physiological responses to water depth in completely submerged condition of a wetland plant Carex schmidtii Meinsh., one of the dominant species in the Longwan Crater Lake wetlands (China. Growth and physiological responses of C. schmidtii were investigated by growing under control (non-submerged and three submerged conditions (5 cm, 15 cm and 25 cm water level. Total biomass was highest in control, intermediate in 5 cm treatment and lowest in the other two submerged treatments. Water depth prominently affected the first-order lateral root to main root mass ratio. Alcohol dehydrogenase (ADH activity decreased but malondialdehyde (MDA content increased as water depth increased. The starch contents showed no differences among the various treatments at the end of the experiment. However, soluble sugar contents were highest in control, intermediate in 5 cm and 15 cm treatments and lowest in 25 cm treatment. Our data suggest that submergence depth affected some aspects of growth and physiology of C. schmidtii, which can reduce anoxia damage not only through maintaining the non-elongation strategy in shoot part but also by adjusting biomass allocation to different root orders rather than adjusting root-shoot biomass allocation.

  13. 产程中的胎儿监护

    Institute of Scientific and Technical Information of China (English)

    王潇; 李笑天

    2015-01-01

    Fetal heart rate is under the control of autonomic nerves system and chemoreceptors , reflecting the fetus heart and medulla in response to the maternal-fetal blood supply , acidosis and anoxia . Electronic fetal monitoring during delivery is used to check the baby′s health in utero and the results are divided into 3 levels.According to the results of electronic fetal monitoring , level-to-level administration is applied for the patients , which is benefit of recognizing and treating fetus hypoxia and acidosis in utero timely and avoides fetal death .%胎心率受到自主神经系统、化学感受器等多因素影响,是胎儿心脏和延髓对母胎血供、酸中毒和缺氧情况的反映。产时胎心监护用于评估胎儿宫内情况,可分为三级胎心率。根据产时胎心监护对患者进行科学分级管理,将有利于及时识别和处理胎儿宫内缺氧和酸中毒,预防胎儿死亡。

  14. Brain caspase-3 and intestinal FABP responses in preterm and term rats submitted to birth asphyxia

    Science.gov (United States)

    Figueira, R.L.; Gonçalves, F.L.; Simões, A.L.; Bernardino, C.A.; Lopes, L.S.; Castro e Silva, O.; Sbragia, L.

    2016-01-01

    Neonatal asphyxia can cause irreversible injury of multiple organs resulting in hypoxic-ischemic encephalopathy and necrotizing enterocolitis (NEC). This injury is dependent on time, severity, and gestational age, once the preterm babies need ventilator support. Our aim was to assess the different brain and intestinal effects of ischemia and reperfusion in neonate rats after birth anoxia and mechanical ventilation. Preterm and term neonates were divided into 8 subgroups (n=12/group): 1) preterm control (PTC), 2) preterm ventilated (PTV), 3) preterm asphyxiated (PTA), 4) preterm asphyxiated and ventilated (PTAV), 5) term control (TC), 6) term ventilated (TV), 7) term asphyxiated (TA), and 8) term asphyxiated and ventilated (TAV). We measured body, brain, and intestine weights and respective ratios [(BW), (BrW), (IW), (BrW/BW) and (IW/BW)]. Histology analysis and damage grading were performed in the brain (cortex/hippocampus) and intestine (jejunum/ileum) tissues, as well as immunohistochemistry analysis for caspase-3 and intestinal fatty acid-binding protein (I-FABP). IW was lower in the TA than in the other terms (Pmechanical ventilation, varied with gestational age, with increased expression of caspase-3 and I-FABP biomarkers. PMID:27356106

  15. Effect of oxygen-radiosensitizer mixtures on the radiation response of Chinese hamster cells, line V-79-753B, in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Millar, B.C.; Fielden, E.M.; Steele, J.J.

    1980-07-01

    The present data show that the maximum yield of single-strand breaks (ssb) in the cellular DNA of Chinese hamster cells V-79-753B is produced at a concentration of oxygen that produces an enhancement ratio for cell survival of 1.9. The relationship between the oxygen concentration and enhancement ratio for survival in this cell line is biphasic with a plateau at ER = 1.9 over the range of 1.5 to 7 ..mu..M O/sub 2/. For concetrations of oxygen below 1.5 ..mu..M a linear relationship between 1/D/sub 0/ and the initial yield of ssb is found. Electron affinic and free radical radiosensitizers operate by different mechanisms which are reflected at the level of ssb production; electron affinic compounds increase the yield of ssb in anoxia and in the presence of low concentrations of oxygen, whereas free radical radiosensitizers do not. The observation that TMPN can compete with oxygen or misonidazole in reactions that lead to changes in radiosensitivity but not ssb production indicates that the relationship between the two parameters must be casual and not casual.

  16. Metal-induced malformations in early Palaeozoic plankton are harbingers of mass extinction.

    Science.gov (United States)

    Vandenbroucke, Thijs R A; Emsbo, Poul; Munnecke, Axel; Nuns, Nicolas; Duponchel, Ludovic; Lepot, Kevin; Quijada, Melesio; Paris, Florentin; Servais, Thomas; Kiessling, Wolfgang

    2015-01-01

    Glacial episodes have been linked to Ordovician-Silurian extinction events, but cooling itself may not be solely responsible for these extinctions. Teratological (malformed) assemblages of fossil plankton that correlate precisely with the extinction events can help identify alternate drivers of extinction. Here we show that metal poisoning may have caused these aberrant morphologies during a late Silurian (Pridoli) event. Malformations coincide with a dramatic increase of metals (Fe, Mo, Pb, Mn and As) in the fossils and their host rocks. Metallic toxins are known to cause a teratological response in modern organisms, which is now routinely used as a proxy to assess oceanic metal contamination. Similarly, our study identifies metal-induced teratology as a deep-time, palaeobiological monitor of palaeo-ocean chemistry. The redox-sensitive character of enriched metals supports emerging 'oceanic anoxic event' models. Our data suggest that spreading anoxia and redox cycling of harmful metals was a contributing kill mechanism during these devastating Ordovician-Silurian palaeobiological events. PMID:26305681

  17. Metabolic Flexibility: Hibernation, Torpor, and Estivation.

    Science.gov (United States)

    Staples, James F

    2016-04-01

    Many environmental conditions can constrain the ability of animals to obtain sufficient food energy, or transform that food energy into useful chemical forms. To survive extended periods under such conditions animals must suppress metabolic rate to conserve energy, water, or oxygen. Amongst small endotherms, this metabolic suppression is accompanied by and, in some cases, facilitated by a decrease in core body temperature-hibernation or daily torpor-though significant metabolic suppression can be achieved even with only modest cooling. Within some ectotherms, winter metabolic suppression exceeds the passive effects of cooling. During dry seasons, estivating ectotherms can reduce metabolism without changes in body temperature, conserving energy reserves, and reducing gas exchange and its inevitable loss of water vapor. This overview explores the similarities and differences of metabolic suppression among these states within adult animals (excluding developmental diapause), and integrates levels of organization from the whole animal to the genome, where possible. Several similarities among these states are highlighted, including patterns and regulation of metabolic balance, fuel use, and mitochondrial metabolism. Differences among models are also apparent, particularly in whether the metabolic suppression is intrinsic to the tissue or depends on the whole-animal response. While in these hypometabolic states, tissues from many animals are tolerant of hypoxia/anoxia, ischemia/reperfusion, and disuse. These natural models may, therefore, serve as valuable and instructive models for biomedical research. PMID:27065167

  18. Sink to Source Transition in Tendrils of a Semileafless Mutant, Pisum sativum cv Curly.

    Science.gov (United States)

    Côté, R; Gerrath, J M; Peterson, C A; Grodzinski, B

    1992-12-01

    Sink to source transition parallels loss of thigmotropic capacity in tendrils of a semileafless mutant, Pisum sativum cv Curly. Macroscopic tendril development is subdivided based on thigmotropic capacity. Stage I is the elongation stage and, although the rate of photosynthesis is similar to that of stage II and III tendrils, dark respiration rates are higher in stage I. During stage II, tendrils are thigmotropic and act as a sink. Even though stage II tendrils have CO(2) exchange characteristics similar to those of stage III tendrils, which are coiled, our fluorescein, (14)C-partitioning, and (11)C-translocation experiments suggest that stage I and II tendrils do not export carbon. Only stage III tendrils act as sources of newly fixed carbon. Export from them is blocked by cold, heat girdling of the petiole, or anoxia treatment of the tendrils. A late stage II tendril complex, in which coiling is occurring, may be exporting photoassimilates; however, this phenomenon can be attributed to the fact that the pea leaf is a compound structure and there may be one or more stage III tendrils, no longer thigmotropic, within the tendril complex. Photosynthetic maturity in pea tendrils occurs at stage III and is characterized by the ability of these tendrils to export photoassimilates. PMID:16653179

  19. Depositional Model of the Marcellus Shale in West Virginia Based on Facies Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Bruner, Kathy

    2011-11-14

    A lithologic analysis of well exposed Marcellus outcrops has identified six different facies in West Virginia and neighboring states: (1) light gray calcareous shale, (2) fossiliferous limestone, (3) black calcareous shale, (4) black noncalcareous shale, (5) dark gray noncalcareous shale, and (6) K-bentonite. Close interbedding of these rock types attests to a complex, ever-changing environment on the eastern foreland ramp of the Appalachian Basin. The environmental setting was clearly not a deep trough, permanently anoxic, salinity stratified, sediment starved, and populated exclusively by phytoplankton—the traditional depositional model. To the contrary, our sedimentary data suggest a rather shallow water depth, intermittent anoxia, normal-marine salinity, a fluctuating input of siliciclastic mud, and faunal communities of low and moderate diversity. Interbedding of the shale and limestone lithofacies as well as the vertical stacking of facies associations is explained most simply by fluctuations in water depth coupled with fluctuations in sediment supply. The sea floor was, at times, immediately below wave base (Facies 1 and 2), around the depth of the thermocline (Facies 2 and 3), or below the thermocline (Facies 4 and 5), relative sea level changing through two sequences of lowstand, transgression, and highstand. Simultaneously the supply of siliciclastic mud was greater at times of lowstand (increased erosion) and highstand (prograding shoreline), and the supply smaller during transgression (sediment stored in distant coastal plain).

  20. Metabolic potentiation of the radiosensitization of hypoxic bacterial cells afforded by nitroaromatic compounds

    International Nuclear Information System (INIS)

    Prolonged preirradiation incubation of nitroaromatic radiosensitizers with Escherichia coli cells has been found to increase the degree of radiosensitization of the cells in anoxia. Studies with E. coli strains which differ in their nitroreductase activity indicate that the increase in sensitization arises from the action of metabolites produced by the nitroreductase system of the cell. The metabolites alone appear to decrease the extrapolation number of irradiated hypoxic cells and when combined with the parent compound give a biphasic survival curve. The combination of misonidazole (1 mmole dm-3) and its metabolites (1 mmole dm-3) gave initial and final enhancement ratios of 2.4 and 1.4, respectively. The final enhancement ratio is that expected for 1 mmole dm-3 misonidazole alone, whereas the initial enhancement ratio indicates that the metabolites potentiate the action of misonidaxole. The preirradiation incubation effect is removed by dithiothreitol at concentrations which do not affect the radiosensitization level of the nitroaromatic sensitizer. This result indicates that the active metabolite probably depletes a certain amount of the free-thiol compounds inside the cell which assist in the repair of radiation-induced damage

  1. Cell volume regulation in goldfish intestinal mucosa.

    Science.gov (United States)

    Groot, J A

    1981-11-01

    1. Ion and water content of goldfish intestinal mucosa, stripped free from muscular layers were measured under various incubation conditions. 2. Ouabain induces an increase in cation content that is electrically compensated for by chloride. The increase in solute content is accompanied by an increase in water content. 3. When extracellular chloride is partially replaced by sulphate, ouabain does induce cell shrinkage. 4. Anoxia induces a rapid increase in cell volume that is restored by oxygenation of the incubation solution. Ouabain prevents the restoration of volume. 5. It is concluded that the classical ouabain-sensitive Na/K pump participates in the maintenance of cellular volume. We suggest that the constancy in volume after ouabain poisoning as is reported for many tissues might be due to a low chloride conductance of its membranes. 6. Anisotonic media (range: 0.6-1.2 isotonicity), made by variation on mannitol concentration, induce changes in cell water content that deviates from the simplified van't Hoff equation by about 10%. No change in water content after the initial increase was found. 7. We conclude that goldfish enterocytes do not possess a mechanism for rapid volume readjustment. PMID:7322833

  2. [Recent treatment of postischaemic anoxic brain damage after cardiac arrest by using therapeutic hypothermia].

    Science.gov (United States)

    Andjelić, Sladjana

    2008-01-01

    Organ injury caused by ischaemia and anoxia during prolonged cardiac arrest is compounded by reperfusion injury that occurs when spontaneous circulation is restored. Mild hypothermia (32-35 degrees C) is neuroprotective through several mechanisms, including suppression of apoptosis, reduced production of excitotoxins and free radicals, and anti-inflammatory actions. Experimental studies show that hypothermia is more effective the earlier it is started after return of spontaneous circulation (ROSC). Two randomised clinical trials show improved survival and neurological outcome in adults who remained comatose after initial resuscitation from prehospital VF cardiac arrest, and who were cooled after ROSC. Different strategies can be used to induce hypothermia. Optimal timing of therapeutic hypothermia for cardiac ischaemia is unknown. In patients who failed to respond to standard cardiopulmonary resuscitation, intra-arrest cooling using ice-cold intravenous (i.v.) fluid improved the chance of survival. Recently, fasudil, a Rho kinase inhibitor, was reported to prevent cerebral ischaemia in vivo by increasing cerebral blood flow and inhibiting inflammatory responses. In future, two different kinds of protective therapies, BCL-2 overexpression and hypothermia,will both inhibit aspects of apoptotic cell death cascades, and that combination treatment can prolong the temporal "therapeutic window" for gene therapy. PMID:19069351

  3. Recent treatment of postischaemic anoxic brain damage after cardiac arrest by using therapeutic hypothermia

    Directory of Open Access Journals (Sweden)

    Anđelić Slađana

    2008-01-01

    Full Text Available Organ injury caused by ischemia and anoxia during prolonged cardiac arrest is compounded by reperfusion injury that occurs when spontaneous circulation is restored. Mild hypothermia (32-35ºC is neuroprotective through several mechanisms, including suppression of apoptosis, reduced production of excitotoxins and free radicals, and anti-inflammatory actions. Experimental studies show that hypothermia is more effective the earlier it is started after return of spontaneous circulation (ROSC. Two randomized clinical trials show improved survival and neurological outcome in adults who remained comatose after initial resuscitation from prehospital VF cardiac arrest, and who were cooled after ROSC. Different strategies can be used to induce hypothermia. Optimal timing of therapeutic hypothermia for cardiac ischemia is unknown. In patients who failed to respond to standard cardiopulmonary resuscitation, intra-arrest cooling using ice-cold intravenous (i.v. fluid improved the chance of survival. Recently, fasudil, a Rho kinase inhibitor, was reported to prevent cerebral ischaemia in vivo by increasing cerebral blood flow and inhibiting inflammatory responses. In future, two different kinds of protective therapies, BCL-2 overexpression and hypothermia, will both inhibit aspects of apoptotic cell death cascades, and that combination treatment can prolong the temporal 'therapeutic window' for gene therapy.

  4. Nitrous oxide production in sputum from cystic fibrosis patients with chronic Pseudomonas aeruginosa lung infection

    DEFF Research Database (Denmark)

    Kolpen, Mette; Kühl, Michael; Bjarnsholt, Thomas;

    2014-01-01

    local anoxia by consuming the majority of O2 for production of reactive oxygen species (ROS). We hypothesized that P. aeruginosa acquires energy for growth in anaerobic endobronchial mucus by denitrification, which can be demonstrated by production of nitrous oxide (N2O), an intermediate in the...... denitrification pathway. We measured N2O and O2 with electrochemical microsensors in 8 freshly expectorated sputum samples from 7 CF patients with chronic P. aeruginosa infection. The concentrations of NO3(-) and NO2(-) in sputum were estimated by the Griess reagent. We found a maximum median concentration of 41.......8 µM N2O (range 1.4-157.9 µM N2O). The concentration of N2O in the sputum was higher below the oxygenated layers. In 4 samples the N2O concentration increased during the initial 6 h of measurements before decreasing for approximately 6 h. Concomitantly, the concentration of NO3(-) decreased in sputum...

  5. Biogeochemical weathering under ice: Size matters

    Science.gov (United States)

    Wadham, J. L.; Tranter, M.; Skidmore, M.; Hodson, A. J.; Priscu, J.; Lyons, W. B.; Sharp, M.; Wynn, P.; Jackson, M.

    2010-09-01

    The basal regions of continental ice sheets are gaps in our current understanding of the Earth's biosphere and biogeochemical cycles. We draw on existing and new chemical data sets for subglacial meltwaters to provide the first comprehensive assessment of sub-ice sheet biogeochemical weathering. We show that size of the ice mass is a critical control on the balance of chemical weathering processes and that microbial activity is ubiquitous in driving dissolution. Carbonate dissolution fueled by sulfide oxidation and microbial CO2 dominate beneath small valley glaciers. Prolonged meltwater residence times and greater isolation characteristic of ice sheets lead to the development of anoxia and enhanced silicate dissolution due to calcite saturation. We show that sub-ice sheet environments are highly geochemically reactive and should be considered in regional and global solute budgets. For example, calculated solute fluxes from Antarctica (72-130 t yr-1) are the same order of magnitude as those from some of the world's largest rivers and rates of chemical weathering (10-17 t km-2 yr-1) are high for the annual specific discharge (2.3-4.1 × 10-3 m). Our model of chemical weathering dynamics provides important information on subglacial biodiversity and global biogeochemical cycles and may be used to design strategies for the first sampling of Antarctic Subglacial Lakes and other sub-ice sheet environments for the next decade.

  6. Environmental Conditions in a Carpathian Deep Sea Basin During the Period Preceding Oceanic Anoxic Event 2 - A Case Study from the Skole Nappe

    Science.gov (United States)

    Bąk, Krzysztof; Bąk, Marta; Górny, Zbigniew; Wolska, Anna

    2015-01-01

    Hemipelagic green clayey shales and thin muddy turbidites accumulated in a deep sea environment below the CCD in the Skole Basin, a part of the Outer Carpathian realm, during the Middle Cenomanian. The hemipelagites contain numerous radiolarians, associated with deep-water agglutinated foraminifera. These sediments accumulated under mesotrophic conditions with limited oxygen concentration. Short-term periodic anoxia also occurred during that time. Muddy turbidity currents caused deposition of siliciclastic and biogenic material, including calcareous foramini-fers and numerous sponge spicules. The preservation and diversity of the spicules suggests that they originate from disarticulation of moderately diversified sponge assemblages, which lived predominantly in the neritic-bathyal zone. Analyses of radiolarian ecological groups and pellets reflect the water column properties during the sedimentation of green shales. At that time, surface and also intermediate waters were oxygenated enough and sufficiently rich in nutri-ents to enable plankton production. Numerous, uncompacted pellets with nearly pristine radiolarian skeletons inside show that pelletization was the main factor of radiolarian flux into the deep basin floor. Partly dissolved skeletons indicate that waters in the Skole Basin were undersaturated in relation to silica content. Oxygen content might have been depleted in the deeper part of the water column causing periodic anoxic conditions which prevent rapid bacterial degra-dation of the pellets during their fall to the sea floor.

  7. Alcohol dehydrogenase (ADH activity in soybean (Glycine max [L.] Merr. under flooding stress

    Directory of Open Access Journals (Sweden)

    Govinda Rizal and Shanta Karki

    2011-03-01

    Full Text Available Sowing time of soybean (Glycine max [L.] Merr. often coincides with the early onset of rainy season. Germinating seedsencounter a transient to prolonged period of water-logging that causes anoxia (absence of oxygen and hypoxia (insufficientoxygen resulting in poor germination. This reduces crop stability and yield. One of the factors responsible for flood tolerance isactivity of alcohol dehydrogenase (ADH during flood. The effect of ADH activity during flooding and difference in floodtolerance level were investigated using two soybean cultivars, Peking and Tamahomare, and their F9 recombinant inbred lines(RILs. Tamahomare showed higher ADH activity than Peking. There was a great variation in ADH activity among the RILs.QTL analysis detected five QTLs for ADH activity (qAas1-5 on five linkage groups, LG_A2, D1a, F, K and L. The QTL qAas4was close to a QTL for shoot damage and conductivity of germinating seeds after flooding treatment.

  8. Air-adapted Methanosarcina acetivorans shows high methane production and develops resistance against oxygen stress.

    Directory of Open Access Journals (Sweden)

    Ricardo Jasso-Chávez

    Full Text Available Methanosarcina acetivorans, considered a strict anaerobic archaeon, was cultured in the presence of 0.4-1% O2 (atmospheric for at least 6 months to generate air-adapted cells; further, the biochemical mechanisms developed to deal with O2 were characterized. Methane production and protein content, as indicators of cell growth, did not change in air-adapted cells respect to cells cultured under anoxia (control cells. In contrast, growth and methane production significantly decreased in control cells exposed for the first time to O2. Production of reactive oxygen species was 50 times lower in air-adapted cells versus control cells, suggesting enhanced anti-oxidant mechanisms that attenuated the O2 toxicity. In this regard, (i the transcripts and activities of superoxide dismutase, catalase and peroxidase significantly increased; and (ii the thiol-molecules (cysteine + coenzyme M-SH + sulfide and polyphosphate contents were respectively 2 and 5 times higher in air-adapted cells versus anaerobic-control cells. Long-term cultures (18 days of air-adapted cells exposed to 2% O2 exhibited the ability to form biofilms. These data indicate that M. acetivorans develops multiple mechanisms to contend with O2 and the associated oxidative stress, as also suggested by genome analyses for some methanogens.

  9. Extinction pattern of reef ecosystems in latest Permian

    Institute of Scientific and Technical Information of China (English)

    WU YaSheng; FAN JiaSong; JIANG HongXia; YANG Wan

    2007-01-01

    Studies of two Permian-Triassic boundary (PTB) sections on top of a Changhsingian reef in Ziyun, Guizhou Province, southwestern China indicate that the end-Permian mass extinction of reef ecosystems occurred in two steps. The first step is the extinction of all stenotropic organisms such as calcisponges and fusulinids in the latest Permian (in the Clarkina yini conodont zone). The biota after the first extinction is simple, comprising eurytropic organisms including microgastropods, ostracods, and some small burrowing organisms, or only algal mats. At the beginning of the Early Triassic (I.e. the beginning of the Hindeodus parvus zone), the environments became anoxic, and the microgastropod dominated biota or algal mats disappeared, which constituted the second episode of the mass extinction. The biota after the second extinction comprises small spherical microproblematica, some kinds of specialized organisms tolerant of anoxic or oxygen-poor conditions. As the environments became oxygenated, the specialized biota was replaced by a microgastropod-dominated simple biota. When the environmental conditions improved further, the simple biota was replaced by a diverse biota with normal-sized ammonoids, bivalves, and gastropods, representing restoration of normal oceanic conditions. Comparison with PTB sections in Dolomites, Italy and Meishan, Zhejiang Province shows that non-reef ecosystems had a similar first episode of mass extinction in the latest Permian. In the case that oceanic anoxia happened, non-reef ecosystems had a second extinction episode similar to that of reef ecosystems.

  10. Interactions of Aquaculture and Waste Disposal in the Coastal Zone

    Institute of Scientific and Technical Information of China (English)

    ZHAI Xuemei; Hawkins S.J.

    2002-01-01

    Throughout the world, the coastal zones of many countries are used increasingly for aquaculture in addition to other activities such as waste disposal. These activities can cause environmental problems and health problems where they overlap. The interaction between aquaculture and waste disposal, and their relationship with eutrophication are the subjects of this paper.Sewage discharge without adequate dispersion can lead to nutrient elevation and hence eutrophication which has clearly negative effects on aquaculture with the potential for toxic blooms. Blooms may be either toxic or anoxia-causing through the decay process or simply clog the gills of filter-feeding animals in some cases. With the development of aquaculture, especially intensive aquaculture, many environmental problems appeared, and have resulted in eutrophication in some areas. Eutrophication may destroy the health of whole ecosystem which is important for sustainable aquaculture.Sewage discharge may also cause serious public health problems. Filter-feeding shellfish growing in sewage-polluted waters accumulate micro-organisms, including human pathogenic bacteria and viruses, and heavy metal ion, presenting a significant health risk. Some farmed animals may also accumulate heavy metals from sewage. Bivalves growing in areas affected by toxic algae blooms may accumulate toxins (such as PSP, DSP) which can be harmful to human beings.

  11. What are the best animal models for testing early intervention in cerebral palsy?

    Directory of Open Access Journals (Sweden)

    Gavin John Clowry

    2014-12-01

    Full Text Available Interventions to treat cerebral palsy should be initiated as soon as possible in order to restore the nervous system to the correct developmental trajectory. One drawback to this approach is that interventions have to undergo exceptionally rigorous assessment for both safety and efficacy prior to use in infants. Part of this process should involve research using animals but how good are our animal models? Part of the problem is that cerebral palsy is an umbrella term that covers a number of conditions. There are also many causal pathways to cerebral palsy, such as periventricular white matter injury in premature babies, perinatal infarcts of the middle cerebral artery or generalised anoxia at the time of birth, indeed multiple causes, including intra-uterine infection or a genetic predisposition to infarction, may need to interact to produce a clinically significant injury. In this review we consider which animal models best reproduce certain aspects of the condition, and the extent to which the multifactorial nature of cerebral palsy has been modelled. The degree to which the corticospinal system of various animals models human corticospinal system function and development is also explored. Where attempts have already been made to test early intervention in animal models, the outcomes are evaluated in light of the suitability of the model.

  12. Sediment oxygen demand in a constructed lake in south-eastern Australia.

    Science.gov (United States)

    Wallace, Todd A; Ganf, George G; Brookes, Justin D

    2016-10-01

    The occurrence of hypoxia and anoxia in aquatic environments is increasing, driven by changes in land use and alteration of flow regimes. Periods of low oxygen impact biodiversity and water quality for both recreational and consumptive users. We use the Torrens Lake as a case study to assess pelagic, benthic and resuspended sediment oxygen demand, and the release of sediment bound phosphorus to determine the relative role of internal and external loading on water quality in a lake within a heavily urbanised landscape. Our results indicate temporal shifts in the dominant oxygen demanding process in the lake. During periods of no-inflow, sediment oxygen demand is the dominant process; during periods of inflow resulting from wet weather conditions, pelagic rather than sediment derived oxygen demand becomes the governing process. The inlet end of the lake is a depositional zone for stormwater borne sediments. Resuspended sediments at the inlet end of the lake exert a higher oxygen demand than those from the outlet, and represent a larger pool of potentially mobile phosphorus compared to sediments at the outlet end of the lake. However, external rather than internal loading appears to be the dominant driver of water quality in this lake. PMID:27420167

  13. A Prehistorical Record of Cultural Eutrophication from Crawford Lake, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, E J; Teranes, J; Guilderson, T; Turton, C L; McAndrews, J H; Wittkop, C A; Stoermer, E F

    2004-08-05

    Cultural eutrophication--the process by which human activities increase nutrient input rates to aquatic ecosystems and thereby cause undesirable changes in surface-water quality--is generally thought to have begun with the start of the industrial era. The prehistoric dimension of human impacts on aquatic ecosystems remains relatively undescribed, particularly in North America. Here we present fossil plankton data (diatoms and rotifers), organic and inorganic carbon accumulations, and carbon isotope ratios from a 1000-yr sediment core record from Crawford Lake, Ontario, Canada. The data documents increased nutrient input to Crawford Lake caused by Iroquoian horticultural activity from A.D. 1268 to 1486 and shows how this increased nutrient input elevated lake productivity, caused bottom-water anoxia, and irreversibly altered diatom community structure within just a few years. Iroquoian settlement in the region declined in the fifteenth century, yet diatom communities and lake circulation never recovered to the predisturbance state. A second phase of cultural eutrophication starting in A.D. 1867, initiated by Canadian agricultural disturbance, increased lake productivity but had comparatively less of an impact on diatom assemblages and carbon-storage pathways than the initial Iroquoian disturbance. This study deepens our understanding of the impact of cultural eutrophication on lake systems, highlights the lasting influence of initial environmental perturbation, and contributes to the debate on the ecological impacts of density and agricultural practices of native North American inhabitants.

  14. Towards A Modern Calibration Of The 238U/235U Paleoredox Proxy: Apparent Uranium Isotope Fractionation Factor During U(VI)-U(IV) Reduction In The Black Sea

    Science.gov (United States)

    Rolison, J. M.; Stirling, C. H.; Middag, R.; Rijkenberg, M. J. A.; De Baar, H. J. W.

    2015-12-01

    The isotopic compositions of redox-sensitive metals, including uranium (U), in marine sediments have recently emerged as powerful diagnostic tracers of the redox state of the ancient ocean-atmosphere system. Interpretation of sedimentary isotopic information requires a thorough understating of the environmental controls on isotopic fractionation in modern anoxic environments before being applied to the paleo-record. In this study, the relationship between ocean anoxia and the isotopic fractionation of U was investigated in the water column and sediments of the Black Sea. The Black Sea is the world's largest anoxic basin and significant removal of U from the water column and high U accumulation rates in modern underlying sediments have been documented. Removal of U from the water column occurs during the redox transition of soluble U(VI) to relatively insoluble U(IV). The primary results of this study are two-fold. First, significant 238U/235U fractionation was observed in the water column of the Black Sea, suggesting the reduction of U induces 238U/235U fractionation with the preferential removal of 238U from the aqueous phase. Second, the 238U/235U of underlying sediments is related to the water column through the isotope fractionation factor of the reduction reaction but is influenced by mass transport processes. These results provide important constraints on the use of 238U/235U as a proxy of the redox state of ancient oceans.

  15. Mitochondrial physiology and reactive oxygen species production are altered by hypoxia acclimation in killifish (Fundulus heteroclitus).

    Science.gov (United States)

    Du, Sherry N N; Mahalingam, Sajeni; Borowiec, Brittney G; Scott, Graham R

    2016-04-15

    Many fish encounter hypoxia in their native environment, but the role of mitochondrial physiology in hypoxia acclimation and hypoxia tolerance is poorly understood. We investigated the effects of hypoxia acclimation on mitochondrial respiration, O2kinetics, emission of reactive oxygen species (ROS), and antioxidant capacity in the estuarine killifish ( ITALIC! Fundulus heteroclitus). Killifish were acclimated to normoxia, constant hypoxia (5 kPa O2) or intermittent diel cycles of nocturnal hypoxia (12 h:12 h normoxia:hypoxia) for 28-33 days and mitochondria were isolated from liver. Neither pattern of hypoxia acclimation affected the respiratory capacities for oxidative phosphorylation or electron transport, leak respiration, coupling control or phosphorylation efficiency. Hypoxia acclimation also had no effect on mitochondrial O2kinetics, but ITALIC! P50(the O2tension at which hypoxia inhibits respiration by 50%) was lower in the leak state than during maximal respiration, and killifish mitochondria endured anoxia-reoxygenation without any impact on mitochondrial respiration. However, both patterns of hypoxia acclimation reduced the rate of ROS emission from mitochondria when compared at a common O2tension. Hypoxia acclimation also increased the levels of protein carbonyls and the activities of superoxide dismutase and catalase in liver tissue (the latter only occurred in constant hypoxia). Our results suggest that hypoxia acclimation is associated with changes in mitochondrial physiology that decrease ROS production and may help improve hypoxia tolerance. PMID:26896545

  16. Distinct Mechanisms Regulating Gene Expression Coexist within the Fermentative Pathways in Chlamydomonas reinhardtii

    Directory of Open Access Journals (Sweden)

    Larisa Angela Swirsky Whitney

    2012-01-01

    Full Text Available Under dark anoxia, the unicellular green algae Chlamydomonas reinhardtii may produce hydrogen by means of its hydrogenase enzymes, in particular HYD1, using reductants derived from the degradation of intercellular carbon stores. Other enzymes belonging to the fermentative pathways compete for the same reductants. A complete understanding of the mechanisms determining the activation of one pathway rather than another will help us engineer Chlamydomonas for fermentative metabolite production, including hydrogen. We examined the expression pattern of the fermentative genes PDC3, LDH1, ADH2, PFL1, and PFR1 in response to day-night cycles, continuous light, continuous darkness, and low or high oxygen availability, which are all conditions that vary on a regular basis in Chlamydomonas' natural environment. We found that all genes except PFL1 show daily fluctuations in expression, and that PFR1 differentiated itself from the others in that it is clearly responsive to low oxygen, where as PDC3, LDH1, and ADH2 are primarily under diurnal regulation. Our results provide evidence that there exist at least three different regulatory mechanisms within the fermentative pathways and suggest that the fermentative pathways are not redundant but rather that availability of a variety of pathways allows for a differential metabolic response to different environmental conditions.

  17. Metal-induced malformations in early Palaeozoic plankton are harbingers of mass extinction

    Science.gov (United States)

    Vandenbroucke, Thijs R. A.; Emsbo, Poul; Munnecke, Axel; Nuns, Nicolas; Duponchel, Ludovic; Lepot, Kevin; Quijada, Melesio; Paris, Florentin; Servais, Thomas; Kiessling, Wolfgang

    2015-08-01

    Glacial episodes have been linked to Ordovician-Silurian extinction events, but cooling itself may not be solely responsible for these extinctions. Teratological (malformed) assemblages of fossil plankton that correlate precisely with the extinction events can help identify alternate drivers of extinction. Here we show that metal poisoning may have caused these aberrant morphologies during a late Silurian (Pridoli) event. Malformations coincide with a dramatic increase of metals (Fe, Mo, Pb, Mn and As) in the fossils and their host rocks. Metallic toxins are known to cause a teratological response in modern organisms, which is now routinely used as a proxy to assess oceanic metal contamination. Similarly, our study identifies metal-induced teratology as a deep-time, palaeobiological monitor of palaeo-ocean chemistry. The redox-sensitive character of enriched metals supports emerging `oceanic anoxic event' models. Our data suggest that spreading anoxia and redox cycling of harmful metals was a contributing kill mechanism during these devastating Ordovician-Silurian palaeobiological events.

  18. δ 13C evidence that high primary productivity delayed recovery from end-Permian mass extinction

    Science.gov (United States)

    Meyer, K. M.; Yu, M.; Jost, A. B.; Kelley, B. M.; Payne, J. L.

    2011-02-01

    Euxinia was widespread during and after the end-Permian mass extinction and is commonly cited as an explanation for delayed biotic recovery during Early Triassic time. This anoxic, sulfidic episode has been ascribed to both low- and high-productivity states in the marine water column, leaving the causes of euxinia and the mechanisms underlying delayed recovery poorly understood. Here we use isotopic analysis to examine the changing chemical structure of the water column through the recovery interval and thereby better constrain paleoproductivity. The δ 13C of limestones from 5 stratigraphic sections in south China displays a negative gradient of approximately 4‰ from shallow-to-deep water facies within the Lower Triassic. This intense gradient declines within Spathian and lowermost Middle Triassic strata, coincident with accelerated biotic recovery and carbon cycle stabilization. Model simulations show that high nutrient levels and a vigorous biological pump are required to sustain such a large gradient in δ 13C, indicating that Early Triassic ocean anoxia and delayed recovery of benthic animal ecosystems resulted from too much productivity rather than too little.

  19. Hypoxic stress, tumor cell survival and /sup 31/P-NMR spectrometry

    International Nuclear Information System (INIS)

    The authors have studied the /sup 31/P-NMR spectral characteristics of a variety of transplantable tumors in situ. These tumors demonstrate the presence of phosphorylocholine, phosphorylethanolamine; inorganic phosphate; glycerolphosphorylcholine, glycerolphosphorylethanolamine; phosphocreatine; and, nucleoside di- and triphosphates. Sensitivity has been improved by use of a 15 mm id solenoidal coil which allows spectrometry of tumors of -- 300 mg. Two tumor models were used to assess the influence of N/sub 2/ asphyxiation and tumor cell survival. Mice bearing s.c. 16/C mammary adenocarcinoma were N/sub 2/ asphyxiated within the NMR spectrometer and tumors excised after various durations of hypoxia for endpoint dilution analysis. Similar protocols using the RIF-1 tumor and clonogenic assay were also employed. The TD/sub 50/ assay using the 16/C mammary tumor indicated that the tumorigenic cells were most vulnerable during the initial adaptation to anoxia (0-13 min). Further delay in tumor excision following N/sub 2/ asphyxiation or simple tumor excision and incubation at 370C was without effect (2 hrs). Cell yield from either tumor was not influenced by hypoxic stress. Trypan blue dye exclusion was suspect due to a detectable decline of intracellular high energy phosphates

  20. Suicidal insulin poisoning with nine day survival: recovery in bile at autopsy by radioimmunoassay

    International Nuclear Information System (INIS)

    The discovery of insulin fifty years ago enabled doctors to successfully treat an eleven year old boy dying from diabetes mellitus and thereby ushered in a new medical era. While millions of subsequent patients were thus able to lead productive lives, others turned this miraculous substance into self-destructive purposes, while a few attempted (and possibly succeeded in) carefully concealed homicidal undertakings. The first ''murder by insulin'' case, prosecuted with a conviction in Great Britain fifteen years ago, employed a laborious bioassay method to demonstrate the hormone at the site of injection. A recent series of insulin poisonings in California was dependent on pathological changes in the brain from anoxia (hypoglycemia) coupled with history and investigation rather than chemical measurements, although an immunoassay method was used for confirmation in the final case. Instances of suicidal attempts by self-administered insulin have been reported with analyses performed by radioimmunoassay, now employed in clinical laboratories to measure many hormonal and therapeutic substances. We have applied this principle from pathologic and toxicologic aspects in an effort to enhance the diagnostic capability of the forensic pathologist, who must examine and properly certify such deaths