WorldWideScience

Sample records for anoxia

  1. Interventional anoxia therapy

    International Nuclear Information System (INIS)

    The book on interventional anoxia therapy covers the following issues: (1) Neuroradiologic diagnostics: Closure of the carotid artery; closure of the cerebral arteries, vertebrobasilary closure; dissections, sinus and brain vein thrombosis; (2) therapy of the acute ischemic anoxia: thrombolysis; intra-arterial thrombolysis, mechanical re-channelization materials; stroke-stent; therapy concepts and results; (3) therapy for acute venous obliterations; (4) therapy for extra and intra-cranial artery stenosis: stents, filters, balloons; extra-cranial carotid stenosis; intra-cranial stenosis; sub-clavian Steal syndrome; proximal vertebral artery stenosis; aortic arch stenosis.

  2. 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

  3. Eelgrass (Zostera marina) tolerance to anoxia

    DEFF Research Database (Denmark)

    Pulido Pérez, Cristina; Borum, Jens

    The tolerance of eelgrass (Zostera marina L.) to anoxia was assessed experimentally to evaluate the potential role of short-term anoxia on eelgrass performance. Eelgrass ramets (terminal leaf bundles with rhizomes and roots) were submerged in anoxic seawater for variable periods of time (0.5 to 48...

  4. CORRECTION ON "CHRONIC INTERMITTENT ANOXIA...".

    Science.gov (United States)

    Halstead, W C

    1945-08-10

    The writer is embarrassed by his discovery that in revising a manuscript entitled "Chronic Intermittent Anoxia and Impairment of Peripheral Vision," an important paragraph was inadvertently omitted from the version which appeared in Science for June 15, 1945. In checking back it becomes evident that the omission arose in the author's final copy, and that the editors of Science are in no way responsible. The paragraph which should have been inserted between the two paragraphs of column 2, page 615, is as follows: Serial determinations of alveolar gas tensions for each visual test day were carried out on sixteen of the twenty subjects by Dr. Wright Adams, but no relationship could be established with the impairment of peripheral vision. Similarly, in a smaller number of subjects no clear relationship could be established between the visual effect and renal vascular changes (Dr. Alf S. Alving), cardio-vascular changes (Dr. Emmet B. Bay), blood chemistry (Dr. Guzmán E. S. Barrón), psychiatric changes (Dr. Hugh T. Carmichael), electroencephalograms (Dr. Theodore Case), peripheral blood flow (Dr. Milton Landowne), certain metabolic effects (Drs. Henry T. Ricketts and A. Hughes Bryan), and certain additional neuropsychological indicators. Through omission of the above paragraph, inadequate representation was given to the scope of the total war research project in which the psychological studies carried out by the writer constituted one aspect. In addition to their particular lines of investigation, each of the above men contributed generously of specialized knowledge and of time and energy to insure adequate clinical supervision of the experimental subjects and a valid interpretation of the impairment of peripheral vision as reported. PMID:17802440

  5. Nitric oxide metabolites during anoxia and reoxygenation in the anoxia-tolerant vertebrate Trachemys scripta

    DEFF Research Database (Denmark)

    Jensen, Frank Bo; Hansen, Marie Niemann; Montesanti, Gabriella; Wang, Tobias

    2014-01-01

    mechanism by up-regulating nitrite and other nitrite/NO metabolites (S-nitroso and iron-nitrosyl compounds) in several tissues when exposed to anoxia. We investigated whether this is a common strategy amongst anoxia-tolerant vertebrates by evaluating NO metabolites in red-eared slider turtles during long......-regulation of nitrite and other NO metabolites could be a general cytoprotective strategy amongst anoxia-tolerant vertebrates. The possible mechanisms of nitrite-derived NO and S-nitrosation in protecting cells from destructive Ca2+ influx during anoxia and in limiting ROS formation during reoxygenation are...

  6. Foraminiferal survival after long term experimentally induced anoxia

    Directory of Open Access Journals (Sweden)

    D. Langlet

    2013-06-01

    Full Text Available Anoxia has been successfully induced in four benthic chambers installed on the Northern Adriatic seafloor from 1 week to 10 months. To accurately determine whether benthic foraminifera can survive experimentally induced prolonged anoxia, the CellTrackerGreen method has been applied. Numerous individuals have been found living at all sampling times and at all sampling depths, showing that benthic foraminifera can survive up to 10 months of anoxia with co-occurring hydrogen sulphides. However, foraminiferal standing stocks decrease with sampling time in an irregular way. A large difference in standing stock between two cores samples in initial conditions indicates the presence of a large spatial heterogeneity of the foraminiferal faunas. An unexpected increase in standing stocks after 1 month is tentatively interpreted as a reaction to increased food availability due to the massive mortality of infaunal macrofaunal organisms. After this, standing stocks decrease again in a core sampled after 2 months of anoxia, to attain a minimum in the cores sampled after 10 months. We speculate that the trend of overall decrease of standing stocks is not due to the adverse effects of anoxia and hydrogen sulphides, but rather due to a continuous diminution of labile organic matter.

  7. The injury effects of anoxia and continual γ irradiation on mice

    International Nuclear Information System (INIS)

    Anoxia, continual γ-irradiation or anoxia in combination with continual γ-irradiation could increase the LPO contents of livers, spleens and hearts of mice. The enhancements of SOD activities of livers, spleens and hearts of mice in anoxia group and γ-irradiation group were observed. Anoxia in combination with continual γ-irradiation could result in the decrease of SOD activities of livers, spleens and hearts of mice

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

    DEFF Research Database (Denmark)

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

    anoxia obtained by NaN3 is a widely used model for simulating anoxia (Ossum et al., 2004). The effects of anoxia were studied by protein expression analysis using 2-dimensional gel electrophoresis followed by MS/MS. In this way we were able to separate more than 1500 protein spots with an apparent range...

  9. Protective effects of some creatine derivatives in brain tissue anoxia.

    Science.gov (United States)

    Perasso, Luisa; Lunardi, Gian Luigi; Risso, Federica; Pohvozcheva, Anna V; Leko, Maria V; Gandolfo, Carlo; Florio, Tullio; Cupello, Aroldo; Burov, Sergey V; Balestrino, Maurizio

    2008-05-01

    Some derivatives more lipophylic than creatine, thus theoretically being capable to better cross the blood-brain barrier, were studied for their protective effect in mouse hippocampal slices. We found that N-amidino-piperidine is harmful to brain tissue, and that phosphocreatine is ineffective. Creatine, creatine-Mg-complex (acetate) and phosphocreatine-Mg-complex (acetate) increased the latency to population spike disappearance during anoxia. Creatine and creatine-Mg-complex (acetate) also increased the latency of anoxic depolarization, while the delay induced by phosphocreatine-Mg-complex (acetate) was of borderline significance (P = 0.056). Phosphocreatine-Mg-complex (acetate) significantly reduced neuronal hyperexcitability during anoxia, an effect that no other compound (including creatine itself) showed. For all parameters except reduced hyperexcitability the effects statistically correlated with tissue levels of creatine or phosphocreatine. Summing up, exogenous phosphocreatine and N-amidino piperidine are not useful for brain protection, while chelates of both creatine and phosphocreatine do replicate some of the known protective effects of creatine. In addition, phosphocreatine-Mg-complex (acetate) also reduced neuronal hyperexcitability during anoxia. PMID:17940889

  10. The induction of proteinases in corn and soybean by anoxia

    International Nuclear Information System (INIS)

    This study characterized the anaerobic changes in proteinase activities in corn and soybean roots and to investigate the possibility that these changes might contribute to the differential anaerobiosis tolerance of the two species. After 24 h of anoxia, crude protein extracts from H60 corn and Keller soybean root tips (10cm) were assayed for proteinase activities at pH range from 4.5 to 9.5. Turnover of aberrant proteins was studied in seedlings labelled with 3H-leucine for 12 h under: (a) puromycin (0.64 mM) in air, (b) ethanol (1%) in air, (c) nitrogen and (d) air. After the treatment, the labelled proteins remaining in roots were determined every 2 h for 6 h. In both corn and soybean, activities of alkali proteinases increased, and activities of acid proteinases declined under anoxia. Neutral proteinases increase in anoxic corn roots, but decline in anoxic soybean roots. The protein turnover rate in corn treated with puromycin, ethanol and nitrogen was much higher than in control roots. The protein turnover rate in soybean roots treated with puromycin, ethanol was similar to the rate of the control. The results indicated that: (a) anoxic corn can degrade aberrant proteins, but anoxic soybean cannot, (b) the degradation of aberrant proteins in anoxic corn is accomplished by neutral proteinases, and (c) the accumulation of aberrant proteins in soybean might contribute to the susceptibility of this species to anoxia

  11. 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

    We investigated the response, adaptation and tolerance mechanisms of the temperate seagrass Zostera marina to water column anoxia. We exposed Z. marina to a diurnal light/dark cycle under anoxia and assessed the metabolic response by measuring the metabolome with gas chromatography coupled to mass...... in lactate and pyruvate and an increase in alanine, GABA and succinate. This reprogramming of the metabolome after 21 h under anoxia indicates a possible mitigation mechanism to avoid the toxic effects of anoxia. A pathway enrichment analysis proposes the alanine shunt, the GABA shunt and the 2...

  12. Effect of postirradiation anoxia on radiosensitivity of lymphocytes

    International Nuclear Information System (INIS)

    Radiosensitivity was measured by viable-lymphocyte counts and by uridine uptake. The viability of the lymphocytes was based on morphologic characteristics visualized by phase contrast microscopy of the cells in a special slide chamber. Low doses of x rays (10 to 1000 R) and incubation at 370C killed lymphocytes in interphase with the production of pyknotic nuclei (nuclear death), and large doses (6000 R) produced nuclei with clear nucleoplasm (cytoplasmic death). Nuclear, but not cytoplasmic, death was inhibited by incubation of the irradiated cells at 270C. Postirradiation anoxia had no effect on development of the nuclear and cytoplasmic death of lymphocytes irradiated with 100 to 6000 R. Anoxia had no effect on the early response of lymphocytes to phytohemagglutinin (PHA) [increase in ribonucleic acid (RNA) and protein synthesis] but inhibited completely the late effects [increase in deoxyribonucleic acid (DNA) synthesis and transformation into lymphoblastoid cells]. The PHA caused relative radioresistance of lymphocytes under aerobic conditions and, to a lesser extent, under anaerobic conditions. The slight radioresistance induced by PHA in anoxic lymphocytes apparently did not depend on an increase in DNA synthesis or on the transformation to lymphoblastoid cells

  13. Nitrate reductase regulation in tomato roots by exogenous nitrate: a possible role in tolerance to long-term root anoxia

    OpenAIRE

    Allègre, Adeline; Silvestre, Jérôme; Morard, Philippe; Kallerhoff, Jean; Pinelli, Eric

    2004-01-01

    The mechanism of nitrate reductase (NR) regulation under long-term anoxia in roots of whole plants and the putative role of nitrate in anoxia tolerance have been addressed. NR activity in tomato roots increased significantly after 24 h of anaerobiosis and increased further by 48 h, with a concomitant release of nitrite into the culture medium. Anoxia promoted NR activation through dissociation of the 14-3-3 protein inhibitor and NR dephosphorylation. After 24 h of anoxia, the total amount of ...

  14. 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...

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

    Directory of Open Access Journals (Sweden)

    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.

  16. 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.

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

    Science.gov (United States)

    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.

  18. 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; Werge, Thomas; Scheel-Krüger, Jørgen

    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 rats....... 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...... schizophrenic patients. There was no effect of postnatal anoxia on either baseline or d-amphetamine-induced deficit in the prepulse inhibition (PPI) paradigm in adulthood. Accordingly, although oxygen deficiency early in life has been discussed as vulnerability factor in developing schizophrenia, exposure to...

  19. 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

  20. Effects of anoxia and ischemia on thallium exchange in rabbit myocardium

    International Nuclear Information System (INIS)

    The isolated, arterially perfused rabbit interventricular septum was used to study the effects of anoxia and ischemia on thallium (Tl-201) exchange. Anoxia or ischemia was introduced for periods of 20, 40, or 60 minutes during either uptake or washout of Tl-201. These interventions were followed by a reperfusion period. Effluent samples were collected during washout experiments. Anoxia lasting 20, 40, or 60 minutes during uptake resulted in a decrease in net Tl-201 uptake, which was promptly reversed upon reoxygenation. Effluent washout curves demonstrated that an increased efflux of Tl-201 occurred during 20 and 40 minutes of anoxia. Surprisingly, comparison of the Tl loss due to anoxia during uptake with the loss of Tl during washout was consistent with an increased influx of Tl-201 during the first 40 minutes of anoxia. Between 40 and 60 minutes of anoxia, the increased efflux of Tl-201 was reversed and the increase in Tl-201 influx was absent. Total ischemia for 20, 40, or 60 minutes during uptake was followed by continued accumulation of Tl-201 in 8 of 9 septa. Total ischemia during washout was followed by an immediate rapid washout of Tl-201 before a new steady-rate was achieved. The authors conclude that these results represent important differences from those reported previously using K-42. Anoxia did not increase the influx of K-42 observed with Tl-201. Also, 60 minutes of ischemia did not result in progressive loss of TL-201 as previously noted for K-42. This implies there are different sensitivities and/or mechanisms for Tl as compared to K uptake

  1. 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...

  2. Tourette's syndrome and neonatal anoxia: further evidence of an organic etiology.

    OpenAIRE

    Burnstein, M H

    1992-01-01

    Studies of Tourette's syndrome have indicated that the etiology may be either primary or secondary. Secondary Tourette's syndrome has been reported in association with numerous neurological conditions, but there have been no previous reports of Tourette's syndrome and its relationship to neonatal anoxia. This report presents the case of a 15-year-old boy with a history of Tourette's syndrome and neonatal anoxia and examines whether or not there is a connection between the two. To test the hyp...

  3. Exceptional cardiac anoxia tolerance in tilapia (Oreochromis hybrid).

    Science.gov (United States)

    Lague, Sabine L; Speers-Roesch, Ben; Richards, Jeffrey G; Farrell, Anthony P

    2012-04-15

    Anoxic survival requires the matching of cardiac ATP supply (i.e. maximum glycolytic potential, MGP) and demand (i.e. cardiac power output, PO). We examined the idea that the previously observed in vivo downregulation of cardiac function during exposure to severe hypoxia in tilapia (Oreochromis hybrid) represents a physiological strategy to reduce routine PO to within the heart's MGP. The MGP of the ectothermic vertebrate heart has previously been suggested to be ∼70 nmol ATP s(-1) g(-1), sustaining a PO of ∼0.7 mW g(-1) at 15°C. We developed an in situ perfused heart preparation for tilapia (Oreochromis hybrid) and characterized the routine and maximum cardiac performance under both normoxic (>20 kPa O(2)) and severely hypoxic perfusion conditions (tilapia heart maintained a routine normoxic cardiac output (Q) and PO under all hypoxic conditions, a result that contrasts with the hypoxic cardiac downregulation previously observed in vivo under less severe conditions. Thus, we conclude that the in vivo downregulation of routine cardiac performance in hypoxia is not needed in tilapia to balance cardiac energy supply and demand. Indeed, the MGP of the tilapia heart proved to be quite exceptional. Measurements of myocardial lactate efflux during severe hypoxia were used to calculate the MGP of the tilapia heart. The MGP was estimated to be 172 nmol ATP s(-1) g(-1) at 22°C, and allowed the heart to generate a PO(max) of at least ∼3.1 mW g(-1), which is only 30% lower than the PO(max) observed with normoxia. Even with this MGP, the additional challenge of acidosis during severe hypoxia decreased maximum ATP turnover rate and PO(max) by 30% compared with severe hypoxia alone, suggesting that there are probably direct effects of acidosis on cardiac contractility. We conclude that the high maximum glycolytic ATP turnover rate and levels of PO, which exceed those measured in other ectothermic vertebrate hearts, probably convey a previously unreported anoxia tolerance

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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

  6. Protection against cardiac anoxia--role and limitations of increased glycogen reserves in the isolated rat right ventricular strip.

    Science.gov (United States)

    Towart, R; Schlossmann, K; Kazda, S

    1981-01-01

    The effects of drugs on rat cardiac glycogen reserves in vivo, and on the subsequent in vitro sensitivity of the right ventricular strip preparation to anoxia have been investigated. Isoproterenol (0.2 mg/kg i.p.) causes immediate cardiac stimulation and reduction of glycogen reserves, coupled with an increased susceptibility to anoxia. Several hours after administration, glycogen levels are found to be greatly (100-200%) increased, by a "supercompensation" mechanism, and a marked tolerance to anoxia can be simultaneously demonstrated. In contrast, large doses of corticosteroids (dexamethasone, 8 mg/kg i.m.) increase glycogen levels without initial stimulation and glycogen depletion; increased myocardial tolerance to anoxia parallels the increase in glycogen reserves in vivo. We conclude that the myocardial tolerance to anoxia in this model is related to increased glycogen reserves, which increase the rate and/or duration of anaerobic glycolysis during anoxia. PMID:7332516

  7. 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.

  8. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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.

  11. 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

  12. Mitochondrial responses to prolonged anoxia in brain of red-eared slider turtles.

    Science.gov (United States)

    Pamenter, Matthew E; Gomez, Crisostomo R; Richards, Jeffrey G; Milsom, William K

    2016-01-01

    Mitochondria are central to aerobic energy production and play a key role in neuronal signalling. During anoxia, however, the mitochondria of most vertebrates initiate deleterious cell death cascades. Nonetheless, a handful of vertebrate species, including some freshwater turtles, are remarkably tolerant of low oxygen environments and survive months of anoxia without apparent damage to brain tissue. This tolerance suggests that mitochondria in the brains of such species are adapted to withstand prolonged anoxia, but little is known about potential neuroprotective responses. In this study, we address such mechanisms by comparing mitochondrial function between brain tissues isolated from cold-acclimated red-eared slider turtles (Trachemys scripta elegans) exposed to two weeks of either normoxia or anoxia. We found that brain mitochondria from anoxia-acclimated turtles exhibited a unique phenotype of remodelling relative to normoxic controls, including: (i) decreased citrate synthase and F1FO-ATPase activity but maintained protein content, (ii) markedly reduced aerobic capacity, and (iii) mild uncoupling of the mitochondrial proton gradient. These data suggest that turtle brain mitochondria respond to low oxygen stress with a unique suite of changes tailored towards neuroprotection. PMID:26763217

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

    Directory of Open Access Journals (Sweden)

    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.

  14. Sex differences in the effects of perinatal anoxia on dopamine function in rats.

    Science.gov (United States)

    Laplante, François; Brake, Wayne G; Chehab, Sara L; Sullivan, Ron M

    2012-01-01

    Birth complications involving reduced oxygen to the fetus pose risks for neurodevelopmental disorders like schizophrenia and ADHD, which involve central dopamine (DA) dysfunction and also show gender differences in incidence or severity. Here, we examine possible sex differences in the long-term consequences of perinatal anoxia in the rat, on central DA systems and DA-mediated behaviour. As adults, sensorimotor gating (prepulse inhibition, PPI) was differentially affected by anoxia in males and females, tending to be impaired only in males. Apomorphine-induced suppression of PPI was especially pronounced in males. Anoxia caused increases in amygdala DA levels in both sexes. However, sex-specific changes in DA and metabolite levels in prefrontal cortex and nucleus accumbens were found, suggesting a possible basis for some of the observed gender biases in certain neurodevelopmental disorders, sensitive to birth hypoxia. PMID:22061835

  15. 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.

  16. 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

  17. 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...

  18. 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.; Jessen, Flemming

    2008-01-01

    and protein synthesis. It was also revealed that the level of a number of keratins was down-regulated. This study therefore provides a valuable comparison of two different anoxia models and shows that great care should be taken when comparing the effects of anoxia in studies that have used different...

  19. Anoxia duirng the Late Permian Binary Mass Extinction and Dark Matter

    CERN Document Server

    Abbas, S; Mohanty, S; Abbas, Samar; Abbas, Afsar; Mohanty, Shukadev

    2000-01-01

    Recent evidence quite convincingly indicates that the Late Permian biotic crisis was in fact a binary extinction with a distinct end-Guadalupian extinction pulse preceding the major terminal end-Permian Tartarian event by 5 million years. In addition anoxia appears to be closely associated with each of these end-Paleozoic binary extinctions. Most leading models cannot explain both anoxia and the binary characteristic of this crisis. In this paper we show that the recently proposed volcanogenic dark matter scenario succeeds in doing this.

  20. 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.

    degrees 40 minutes E to 15 degrees 30 minutes N, 72 degrees 59 minutes E) to understand the processes that mediate the changes in various inorganic nitrogen species in the water column during anoxia. Water column chemistry showed a clear distinct oxic...

  1. Effects of anoxia and ischemia on thallium exchange in rabbit myocardium

    International Nuclear Information System (INIS)

    The authors investigated the effects of anoxia and ischemia on thallium (201Tl) exchange using isolated rabbit interventricular septa. Anoxia for 20 or 40 min caused a decrease in 201Tl tissue uptake due to an increased efflux of 201Tl with a smaller increase in 201Tl influx. Between 40 and 60 min of anoxia, the increased efflux of 201Tl was reversed and the increase in 201Tl influx was absent. After 60 min of reoxygenation, septa made anoxic for 20-60 min recovered at least 95% of the Tl lost. Mechanical recovery, however, was still significantly depressed. Reperfusion after total ischemia for 20-60 min was followed by resumption of 201Tl uptake despite continued mechanical dysfunction. Efflux rates during reperfusion after ischemia were significantly different from preischemic values but not in a predictable way. This unpredictability complicates interpretation of clinical 201Tl redistribution studies. These results represent important differences from those reported previously using 42K. Anoxia did not increase the influx of 42K. Also, 60 min of ischemia resulted in progressive losses of 42K. This implies there are different sensitivities and/or mechanisms for Tl compared with K uptake. These results are consistent with 201Tl uptake by severely damaged and nonviable cells

  2. 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.

  3. The role of DNA methylation during anoxia tolerance in a freshwater turtle (Trachemys scripta elegans).

    Science.gov (United States)

    Wijenayake, Sanoji; Storey, Kenneth B

    2016-04-01

    Oxygen deprivation is a lethal stress that only a few animals can tolerate for extended periods. This study focuses on analyzing the role of DNA methylation in aiding natural anoxia tolerance in a champion vertebrate anaerobe, the red-eared slider turtle (Trachemys scripta elegans). We examined the relative expression and total enzymatic activity of four DNA methyltransferases (DNMT1, DNMT2, DNMT3a and DNMT3b), two methyl-binding domain proteins (MBD1 and MBD2), and relative genomic levels of 5-methylcytosine under control, 5 h anoxic, and 20 h anoxic conditions in liver, heart, and white skeletal muscle (n = 4, p anoxia submergence resulted in a 1.4-fold increase in DNMT3a levels and a significant decrease in MBD1 and MBD2 levels to ~30 % of control values. In white muscle, DNMT3a and DNMT3b increased threefold and MBD1 levels increased by 50 % in response to 5 h anoxia. Total DNMT activity rose by 0.6-2.0-fold in liver and white muscle and likewise global 5mC levels significantly increased in liver and white muscle under 5 and 20 h anoxia. The results demonstrate an overall increase in DNA methylation, DNMT protein expression and enzymatic activity in response to 5 and 20 h anoxia in liver and white muscle indicating a potential downregulation of gene expression via this epigenetic mechanism during oxygen deprivation. PMID:26843075

  4. 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

  5. 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 ...

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

    DEFF Research Database (Denmark)

    Kamp, Anja; Stief, Peter; Knappe, Jan; de Beer, Dirk

    2013-01-01

    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 N-15-nitrate consumed 1.15 (+/- 0.25) fmol NO3- cell(-1) h(-1) and simultaneously produced 1.57 (+/- 0.21) fmol (NH4+)-N-15 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...

  7. 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.

  8. Anoxia pre-dates Frasnian-Famennian boundary mass extinction horizon in the Great Basin, USA

    Science.gov (United States)

    Bratton, John F.; Berry, William B.N.; Morrow, Jared R.

    1999-01-01

    Major and trace metal results from three Great Basin stratigraphic sections with strong conodont biostratigraphy identify a distinct anoxic interval that precedes, but ends approximately 100 kyr before, the Frasnian–Famennian (F–F, mid-Late Devonian) boundary mass extinction horizon. This horizon corresponds to the final and most severe step of a more protracted extinction period. These results are inconsistent with data reported by others from the upper Kellwasser horizon in Europe, which show anoxia persisting up to the F–F boundary in most sections. Conditions returned to fully oxygenated prior to the F–F boundary in the study area. These data indicate that the worst part of the F–F extinction was not related directly to oceanic anoxia in this region and potentially globally.

  9. 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.

  10. 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.

  11. Centennial changes in North Pacific anoxia linked to tropical trade winds

    Science.gov (United States)

    Deutsch, Curtis; Berelson, William; Thunell, Robert; Weber, Thomas; Tems, Caitlin; McManus, James; Crusius, John; Ito, Taka; Baumgartner, Timothy; Ferreira, Vicente; Mey, Jacob; van Geen, Alexander

    2014-01-01

    Climate warming is expected to reduce oxygen (O2) supply to the ocean and expand its oxygen minimum zones (OMZs). We reconstructed variations in the extent of North Pacific anoxia since 1850 using a geochemical proxy for denitrification (δ15N) from multiple sediment cores. Increasing δ15N since ~1990 records an expansion of anoxia, consistent with observed O2 trends. However, this was preceded by a longer declining δ15N trend that implies that the anoxic zone was shrinking for most of the 20th century. Both periods can be explained by changes in winds over the tropical Pacific that drive upwelling, biological productivity, and O2 demand within the OMZ. If equatorial Pacific winds resume their predicted weakening trend, the ocean’s largest anoxic zone will contract despite a global O2 decline.

  12. 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

    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, and...... Rho GDP dissociation inhibitor (GDI). The up-regulation of Rho GDI was shown to develop in a time dependent manner with no significant increase for up to 8 h of anoxia. In conclusion, this study provides a thorough investigation of the effect of anoxia in a cell line from rainbow trout....

  13. 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

  14. 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...

  15. Organic-matter production and preservation and evolution of anoxia in the Holocene Black Sea

    Science.gov (United States)

    Arthur, M.A.; Dean, W.E.

    1998-01-01

    Dating of sediments collected in gravity cores during Leg 1 of the 1988 R/V Knorr expedition to the Black Sea suggests that the onset of water-column anoxia at ???7.5 ka was virtually synchronous across the basin over a depth range of ???200 - 2250 m. A finely laminated, organic carbon (OC) rich sapropel (unit II) was produced as a result of this anoxia. The trigger for increased OC production and development of anoxia was the spillover of saline waters through the Bosporus that probably began at ???9.0 ka and peaked between ???7.0 and 5.5 ka. This spillover enhanced vertical mixing and nutrient cycling and caused a short-term (2-3 kyr) burst in surface-water productivity during the early part of unit II deposition. Continued incursion of saline waters enhanced vertical stability and inhibited mixing of nutrients into surface waters, thus limiting primary production and decreasing the OC flux to sediments beginning ???5.5 ka. Concentration, accumulation rate, and degree of preservation of organic matter all decreased in the upper part of unit II as a result of decreasing productivity, but anoxia persisted throughout most of the water column. The end of unit II sapropel deposition was synchronous across the Black Sea as the result of the first blooms of the coccolith Emiliania huxleyi, which presumably marked an increase in surface-water salinity above 11 and the beginning of unit I deposition. The high coccolith-carbonate fluxes that occurred during deposition of unit I diluted the OC concentration in the sediments, but OC accumulation rates are about the same as those in upper part of unit II.

  16. Protective effect of hypothermia on brain potassium homeostasis during repetitive anoxia in Drosophila melanogaster.

    Science.gov (United States)

    Rodríguez, Esteban C; Robertson, R Meldrum

    2012-12-01

    Oxygen deprivation in nervous tissue depolarizes cell membranes, increasing extracellular potassium concentration ([K(+)](o)). Thus, [K(+)](o) can be used to assess neural failure. The effect of temperature (17, 23 or 29°C) on the maintenance of brain [K(+)](o) homeostasis in male Drosophila melanogaster (w1118) individuals was assessed during repeated anoxic comas induced by N(2) gas. Brain [K(+)](o) was continuously monitored using K(+)-sensitive microelectrodes while body temperature was changed using a thermoelectric cooler (TEC). Repetitive anoxia resulted in a loss of the ability to maintain [K(+)](o) baseline at 6.6±0.3 mmol l(-1). The total [K(+)](o) baseline variation (Δ[K(+)](o)) was stabilized at 17°C (-1.1±1.3 mmol l(-1)), mildly rose at 23°C (17.3±1.4 mmol l(-1)), and considerably increased at 29°C (332.7±83.0 mmol l(-1)). We conclude that (1) reperfusion patterns consisting of long anoxia, short normoxia and high cycle frequency increase disruption of brain [K(+)](o) baseline maintenance, and (2) hypothermia has a protective effect on brain K(+) homeostasis during repetitive anoxia. Male flies are suggested as a useful model for examining deleterious consequences of O(2) reperfusion with possible application for therapeutic treatment of stroke or heart attack. PMID:22899531

  17. 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

  18. Impact of neonatal anoxia on adult rat hippocampal volume, neurogenesis and behavior.

    Science.gov (United States)

    Takada, Silvia Honda; Motta-Teixeira, Lívia Clemente; Machado-Nils, Aline Vilar; Lee, Vitor Yonamine; Sampaio, Carlos Alberto; Polli, Roberson Saraiva; Malheiros, Jackeline Moraes; Takase, Luiz Fernando; Kihara, Alexandre Hiroaki; Covolan, Luciene; Xavier, Gilberto Fernando; Nogueira, Maria Inês

    2016-01-01

    Neonates that suffer oxygen deprivation during birth can have long lasting cognitive deficits, such as memory and learning impairments. Hippocampus, one of the main structures that participate in memory and learning processes, is a plastic and dynamic structure that conserves during life span the property of generating new cells which can become neurons, the so-called neurogenesis. The present study investigated whether a model of rat neonatal anoxia, that causes only respiratory distress, is able to alter the hippocampal volume, the neurogenesis rate and has functional implications in adult life. MRI analysis revealed significant hippocampal volume decrease in adult rats who had experienced neonatal anoxia compared to control animals for rostral, caudal and total hippocampus. In addition, these animals also had 55.7% decrease of double-labelled cells to BrdU and NeuN, reflecting a decrease in neurogenesis rate. Finally, behavioral analysis indicated that neonatal anoxia resulted in disruption of spatial working memory, similar to human condition, accompanied by an anxiogenic effect. The observed behavioral alterations caused by oxygen deprivation at birth might represent an outcome of the decreased hippocampal neurogenesis and volume, evidenced by immunohistochemistry and MRI analysis. Therefore, based on current findings we propose this model as suitable to explore new therapeutic approaches. PMID:26416672

  19. 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.

  20. 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

  1. Orbital control on the timing of oceanic anoxia in the Late Cretaceous

    Science.gov (United States)

    Batenburg, Sietske; De Vleeschouwer, David; Sprovieri, Mario; Hilgen, Frederik; Gale, Andrew; Singer, Brad; Koeberl, Christian; Cocioni, Rodolfo; Claeys, Philippe; Montanari, Alessandro

    2015-04-01

    The oceans of the Cenomanian-Turonian transition, at the height of the Cretaceous greenhouse, were abruptly disturbed by a period of oceanic anoxia. This led to the brief but widespread deposition of black organic-rich shales in the world's oceans, such as the Livello Bonarelli in the Umbria-Marche Basin (Italy). However, the origin and exact timing of the onset of oceanic anoxia are debated. We present a 6-Myr-long astronomically-tuned timescale across the Cenomanian-Turonian Oceanic Anoxic Event 2 (OAE2), obtained from the Furlo and Bottaccione sections in the Umbria-Marche Basin. The cyclic climatic imprint on lithological, geophysical and stable isotope records allows us to decipher the relationship between orbital forcing and the Late Cretaceous carbon cycle. The deposition of black shales and cherts, as well as the onset of oceanic anoxia, is related to maxima in the 405-thousand year cycle of eccentricity modulated precession. In this study, we also present a new radioisotopic Ar/Ar age for the Thatcher bentonite occurring within the mid-Cenomanian carbon isotope event in the Western Interior of the USA. We correlate our astrochronology from the Umbria-Marche Basin to this new and recent radioisotopic ages, and we come to an unprecedented age control for European successions. The most likely tuned age for the Livello Bonarelli base is 94.22 Ma, however a 405-kyr older age cannot be excluded due to increasing uncertainties in stratigraphic correlation, radioisotopic dating, and orbital configuration. Although volcanism was probably the ultimate driver of OAE2, the cyclicity of the Umbria-Marche successions reveals that the exact timing of carbon cycle perturbations in the Late Cretaceous was determined by orbital periodicities.

  2. 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

  3. Computerized tomography of five cases with global cerebral ischemic-anoxia

    International Nuclear Information System (INIS)

    Among eight cases with global cerebral ischemic-anoxia which were monitored with a serial computerized tomography (CT) scan, five had characteristic CT findings. It was revealed by the CT scan that, after diffuse brain swelling which had occurred immediately or a week after injury, remarkable brain atrophy appeared in two cases; these cases remained in the persistent vegetative state. In three other cases which were resuscitated one hour or more after injury, the CT scan showed symmetric low-density areas of the bilateral basal ganglia, and their prognoses were very poor: two died, while one remained in a near-brain-death state. (author)

  4. Anoxia Treatment for Delaying Skin Browning, Inhibiting Disease Development and Maintaining the Quality of Litchi Fruit

    OpenAIRE

    Jiang, Yueming; Su, Xinguo; Duan, Xuewu; Lin, Wenbin; Li, Yuebiao

    2004-01-01

    Litchi fruit has a very short shelf life after harvest, so marketers and consumers alike desire longer periods of storage, transportation and distribution. To extend shelf life, anoxia treatments were used for the fruit. Litchi fruit were exposed to pure N2 for 0, 3, 6, 12 or 24 h. They were then kept individually in closed but vented containers for 6 days in the dark at 20 °C and 95–100 % relative humidity. Exposure of litchi fruit to N2 for 3 or 6 h markedly delayed skin browning, reduced r...

  5. Late Devonian Anoxia Events in the Central Asian Orogenic Belt: a Global Phenomenon

    Science.gov (United States)

    Carmichael, S. K.; Waters, J. A.; Suttner, T. J.; Kido, E.; DeReuil, A. A.; Moore, L. M.; Batchelor, C. J.

    2013-12-01

    Atmospheric CO2 values decreased dramatically during the Middle Devonian due to the rapid rise of land plants. These changing environmental conditions resulted in widespread anoxia and extinction events throughout the Late Devonian, including the critical Kellwasser and Hangenberg anoxia events, which are associated with major mass extinctions at both the beginning and end of the Famennian Stage of the Late Devonian. Fammenian sediments in northwestern Xinjiang Province, China, represent a highly fossiliferous shallow marine setting associated with a Devonian oceanic island arc complex. Analysis of multiple geochemical proxies (such as U/Th, Ba, normalized P2O5, V/Cr, Zr), magnetic susceptibility, and mineralogical data (biogenic apatite and pyrite framboids) indicates that these Famennian sequences record not only the Upper Kellwasser Anoxic Event at the Frasnian/Famennian (F/F) boundary but also the rebound from the F/F extinction event. Preliminary evidence suggests that the Hangenberg Anoxic Event can also be recognized in the same sequence, although our biostratigraphic control is less precise. Previous studies of the Kellwasser and Hangenberg Events have been performed on continental shelf environments of Laurussia, Gondwana, Siberia, and South China. The Devonian formations of northwest Xinjiang in this study, however, are part of the Central Asian Orogenic Belt (CAOB), which is thought to have formed as part of a complex amalgamation of intra-oceanic island arcs and continental fragments prior to the end of the latest Carboniferous. These results allow us to confirm the presence of the Kellwasser and Hangenberg Events in the open oceanic part of Paleotethys, indicating that both events were global in scope. The presence of an abundant diverse Famennian fauna between these anoxia/extinction events suggests that the shallow marine ecosystems in the CAOB were somewhat protected due to their tectonic location and relative isolation within an open ocean system

  6. History of water-column anoxia in the Black Sea indicated by pyrite framboid size distributions

    Science.gov (United States)

    Wilkin, R.T.; Arthur, M.A.; Dean, W.E.

    1997-01-01

    A detailed study of size distributions of framboidal pyrite in Holocene Black Sea sediments establishes the timing of a change from deposition under an oxic water column to deposition under an anoxic and sulfidic water column. In the most recent carbonate-rich sediments (Unit I) and in the organic carbon-rich sapropel (Unit II), framboid size distributions are remarkably uniform (mean diameter= 5 ??m); over 95% of the framboids in Unit I and Unit II are anoxia in the Black Sea coincided with the initiation of deposition of laminated Unit II sapropels.

  7. Constrictive responses of aorta in irradiated rats: influence of hypoxia and anoxia

    International Nuclear Information System (INIS)

    The amplification of constrictive responses of vessels after exposure of rats to a low dose gamma radiation (50 cGy at a dose rate of 2.8*10-7 Gy per sec) is defined mainly by decrease in relaxation influences of the endothelium. Vasoactive properties of endothelial cells are the deciding factor of changes of responses of aorta during the action of agonists of adrenergic receptors in conditions of hypoxia and anoxia. During insufficient oxygen supply, as opposed to conditions of oxygenation, post-radiation destabilization of endothelial mechanisms of adrenergic control of arterial vessels tone is observed. (authors)

  8. Enigmatic carbonates of the Ombombo Subgroup, Otavi Fold Belt, Namibia: A prelude to extreme Cryogenian anoxia?

    Science.gov (United States)

    Hood, A. v. S.; Wallace, M. W.; Reed, C. P.; Hoffmann, K.-H.; Freyer, E. E.

    2015-07-01

    The Ombombo Subgroup of the Otavi Fold Belt, Kaokoveld, Namibia preserves a succession of clastic and carbonate sediments with unusual sedimentary features. The stratigraphy of these units is discussed here in detail for the first time since their initial definition, with particular emphasis on the sedimentology of carbonate units. Early Neoproterozoic shales of the Beesvlakte Formation, equivalent to the Zambian Katangan Copperbelt's Lower Roan Formation, host evaporitic lithologies and minor copper mineralisation. The overlying, dolomitic ~ 760 Ma Devede Formation contains carbonate platformal lithologies which are in many ways dissimilar to Phanerozoic shallow-water carbonates. This includes unusual "curl breccias", sheet cavities, carbonate shrubs, and tepee carbonate lithologies which contain large quantities of fibrous cements. "Curl breccias" are defined here as distinctive, curled intraclasts of laminated dolomite that often have shrinkage cracks in their margins, and are cemented by fibrous dolomite cements. Fibrous cements take on two forms: an early, length-fast fascicular-optic dolomite and a later length-slow phase with unit extinction. The presence of overlying internal sediments, the fibrous habit of these first-generation cements, as well as their preserved cathodoluminescent and optical character, suggests that these cements originally precipitated as calcite and dolomite marine cements respectively. After this initial marine calcite precipitation, all components of Devede Formation carbonates have been mimetically dolomitised, preserving original depositional fabrics. Combined with the presence of marine dolomite cements, this style of dolomitisation is suggested to be syn-sedimentary, similar to that of some Cryogenian dolomites, suggesting unusual ocean conditions during the Early Neoproterozoic. In particular, the presence of dolomite marine cements, which have been linked to ocean anoxia and high seawater Mg/Ca conditions, suggests that the

  9. 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.

    the dominant respiratory process. Anoxia O2=0 ml l−1, NO−2 , NO−3 =0 µM, H2S>0 µM The environment is completely anaerobic with sulphate reduction being the dominant respiratory process. a 1 ml l−1=1.43 mg l−1=44.64 µM are involved in the destruction of ozone... depletion. In contrast with the atmospheric deposition, the riverine supply of reactive nitrogen that has been greatly altered by human activities (Seitzinger et al., 2002; Galloway et al., 2004) is largely confined to the coastal zone. Moreover, while...

  10. 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...

  11. [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

  12. 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

  13. Abrupt ocean anoxia and mass extinction at the Hangenberg crisis, Devonian-Carboniferous boundary

    Science.gov (United States)

    Schmitz, M. D.; Davydov, V. I.

    2012-12-01

    The late Devonian period hosts a set of profound biotic crises accompanying episodes of tropical ocean anoxia, positive carbon isotope excursions, relative sea level rise and fall, and apparent global climatic cooling. The Hangenberg event, at the close of the Devonian, is the last of these crises which ushered in a new and long-lived icehouse climate regime spanning the Carboniferous and early Permian. New high-precision U-Pb zircon ages for bracketing volcanic tuffs constrain the timing and tempo of the Hangenberg biotic crisis. When combined with quantitative biostratigraphic analysis, these data constrain the duration of tropical ocean anoxia, mass extinction and carbon cycle perturbation to less than 100 thousand years. This rapidity and duration is consistent with a model of orbitally-forced cooling resulting in enhancement of oceanic circulation, in turn promoting catastrophic overturn, upwelling of anoxic bottom waters onto the tropical continental shelves, and consequent biotic reorganization. Enhanced organic carbon burial evidenced by a positive carbon isotope spike is also revealed as rapid and short-lived, but sufficient to draw down atmospheric CO2 and initiate a glacial pulse restricted to a single short period eccentricity cycle at the end-Devonian.

  14. 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.

  15. Reconstructing the rise of recent coastal anoxia; molybdenum in Chesapeake Bay sediments

    Science.gov (United States)

    Adelson, J.M.; Helz, G.R.; Miller, C.V.

    2001-01-01

    Sporadic, direct observations over a 50 yr period inadequately characterize the history of seasonal hypoxia and anoxia in Chesapeake Bay, alarge estuary threatened by eutrophication. Here, we undertake a reconstruction of 20th century oxygen depletion in this estuary using Mo concentrations in 210Pb-dated sediments; Cu concentrations are used to control for anthropogenic influences. Cores from the central channel display mild Mo enrichments above crustal backgrounds (up to 5 ??g/g) and strong Cu enrichments (up to 35 ??g/g). Temporally, Cu enrichment (mostly anthropogenic) began earlier and stabilized in the last two thirds of the 20th century. In contrast, Mo enrichment has grown during the last two thirds of the century. Molybdenum enrichment is mostly hydrogenic, except in a section of the channel that receives additional Mo from erosion of Early Miocene shore deposits. Two geochemical mechanisms promote Mo enrichment: Manganese refluxing concentrates dissolved MoO24- at the sediment-water interface and sulfide substitution into MoO24- produces thiomolybdates, which can be fixed by particles. The Mo enrichment mechanisms operate primarily during periods when bottom waters are anoxic and thiomolybdate formation can occur near the sediment-water interface. This implies a temporal coupling between water-column anoxia and Mo fixation even though fixation occurs only within sediments. The Mo enrichment profiles suggest that Chesapeake Bay has experienced growing O2 depletion since the first half of the 20th century, but especially after 1960. Copyright ?? 2001 Elsevier Science Ltd.

  16. ANOXIA, Treatment by Oxygen Deprivation, Optimizing Treatment Time of Museum Objects

    CERN Document Server

    Gunn, M; Naffah, C; Ziaeepour, H; Gunn, Michele; Merizzi, Fabrice; Naffah, Christitiane; Ziaeepour, Houri

    2006-01-01

    ANOXIA, treatment by oxygen deprivation is largely used for decontamination and disinfestation of cellulose and protein-based organic materials. More specifically this method is applied to more than one hundred thousand of objects destinated for a new museum in Paris, "Musee du Quai Branly". We describe the anoxia installation in this museum and report the result of a study regarding the efficiency of this method and the optimum treatment time, crucial for treating a large collection. We show that the standard 21 days of exposure is not always the optimal choice. Temperature plays a crucial role for hastening the death of insects found within objects. At a temperature of 25C, it is entirely possible to reduce exposure times to 10 or 15 days for the insect species commonly found in museums. The oxygen drop times is between 1 and 2 days for most objects, depending on type and porosity of materials. This corresponds to a treatment time between 15 and 16 days. The effect of humidity is less clear. It can increase...

  17. Biological impact of eutrophication in the bay of somme and the induction and impact of anoxia

    Science.gov (United States)

    Desprez, M.; Rybarczyk, H.; Wilson, J. G.; Ducrotoy, J. P.; Sueur, F.; Olivesi, R.; Elkaim, B.

    The first effects of eutrophication in the Bay of Somme became apparent in the years 1982-1985, when the cockle population collapsed. Areas of high mortality were mapped. Following exceptionally high summer temperatures, other effects were seen in 1982, 1983 and 1989, notably a mass mortality of the benthos. It appeared that the mortality of the benthos was a direct result of anoxia in the water promoted by phytoplankton blooms which were due to high nitrogen levels (nitrates from river and land runoff; ammonium from estuarine bivalve populations). Effects from the change in the benthic community (the disappearance of Cerastoderma edule and the proliferation of Pygospio elegans) were also apparent higher up in the food chain, viz. changes in the diet of the two main predators of the bivalve, the oystercatcher ( Haematopus ostralegus) and the common gull ( Larus canus). Following respirometry measurements of the water, sediment and the major macrobenthic species ( Cerastoderma edule, Macoma balthica, Nereis diversicolor, Hydrobia ulvae), a model for anoxia was constructed.

  18. Transgenic AEQUORIN reveals organ-specific cytosolic Ca2+ responses to anoxia and Arabidopsis thaliana seedlings

    Science.gov (United States)

    Sedbrook, J. C.; Kronebusch, P. J.; Borisy, G. G.; Trewavas, A. J.; Masson, P. H.

    1996-01-01

    Using the transgenic AEQUORIN system, we showed that the cotyledons and leaves of Arabidopsis thaliana seedlings developed a biphasic luminescence response to anoxia, indicating changes in cytosolic Ca2+ levels. A fast and transient luminescence peak occurred within minutes of anoxia, followed by a second, prolonged luminescence response that lasted 1.5 to 4 h. The Ca2+ channel blockers Gd3+, La3+, and ruthenium red (RR) partially inhibited the first response and promoted a larger and earlier second response, suggesting different origins for these responses. Both Gd3+ and RR also partially inhibited anaerobic induction of alcohol dehydrogenase gene expression. However, although anaerobic alcohol dehydrogenase gene induction occurred in seedlings exposed to water-agar medium and in roots, related luminescence responses were absent. Upon return to normoxia, the luminescence of cotyledons, leaves, and roots dropped quickly, before increasing again in a Gd3+, La3+, ethyleneglycol-bis(beta-aminoethyl ether)-N,N'-tetraacetic acid-, and RR-sensitive fashion.

  19. Regulation of the mitogen-activated protein kinase p44 ERK activity during anoxia/recovery in rainbow trout hypodermal fibroblasts

    DEFF Research Database (Denmark)

    Ossum, Carlo G; Wulff, Tune; Hoffmann, Else K

    It is well known from various mammalian cells that anoxia has a major impact on the mitogen-activated protein kinase ERK, but a possible similar effect in fish cells has not been investigated. Here we characterise a p44ERK-like protein in the rainbow trout cell line RTHDF and study the effect of (i......) serum stimulation, (ii) sodium azide (chemical anoxia) and removal of azide (recovery) and (iii) anoxia (P(O)2<0.1%) and recovery. During both chemical and true anoxia p44ERK was inhibited and recovery resulted in robust reactivation of p44ERK activity, far above the initial level. The inhibition was...... secondary to activation of p38(MAPK) and the increase was MEK dependent, as SB203580 inhibited the dephosphorylation during anoxia and the presence of PD98059 inhibited phosphorylation of p44ERK during recovery. In addition, we demonstrated that the reactivation of p44ERK during recovery also was dependent...

  20. 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

  1. 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.

  2. 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

  3. 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.

  4. Exposure of yeast cells to anoxia induces transient oxidative stress. Implications for the induction of hypoxic genes.

    Science.gov (United States)

    Dirmeier, Reinhard; O'Brien, Kristin M; Engle, Marcella; Dodd, Athena; Spears, Erick; Poyton, Robert O

    2002-09-20

    The mitochondrial respiratory chain is required for the induction of some yeast hypoxic nuclear genes. Because the respiratory chain produces reactive oxygen species (ROS), which can mediate intracellular signal cascades, we addressed the possibility that ROS are involved in hypoxic gene induction. Recent studies with mammalian cells have produced conflicting results concerning this question. These studies have relied almost exclusively on fluorescent dyes to measure ROS levels. Insofar as ROS are very reactive and inherently unstable, a more reliable method for measuring changes in their intracellular levels is to measure their damage (e.g. the accumulation of 8-hydroxy-2'-deoxyguanosine (8-OH-dG) in DNA, and oxidative protein carbonylation) or to measure the expression of an oxidative stress-induced gene, e.g. SOD1. Here we used these approaches as well as a fluorescent dye, carboxy-H(2)-dichloro-dihydrofluorescein diacetate (carboxy-H(2)-DCFDA), to determine whether ROS levels change in yeast cells exposed to anoxia. These studies reveal that the level of mitochondrial and cytosolic protein carbonylation, the level of 8-OH-dG in mitochondrial and nuclear DNA, and the expression of SOD1 all increase transiently during a shift to anoxia. These studies also reveal that carboxy-H(2)-DCFDA is an unreliable reporter of ROS levels in yeast cells shifted to anoxia. By using two-dimensional electrophoresis and mass spectrometry (matrix-assisted laser desorption ionization time-of-flight), we have found that specific proteins become carbonylated during a shift to anoxia and that some of these proteins are the same proteins that become carbonylated during peroxidative stress. The mitochondrial respiratory chain is responsible for much of this carbonylation. Together, these findings indicate that yeast cells exposed to anoxia experience transient oxidative stress and raise the possibility that this initiates the induction of hypoxic genes. PMID:12089150

  5. 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.

  6. Differential role for ERK2 in anoxia-induced activation of transcription and translation of Hsp70 in NIH 3T3 cells

    DEFF Research Database (Denmark)

    Ossum, Carlo G; Lauritsen, Anders N; Karottki, Dorina Gabriela; Hoffmann, Else K

    2011-01-01

    transcription and translation of Hsp70 during recovery from chemical anoxia and the role of the extracellular signal regulated kinase ERK2 in this induction of Hsp70. 10 mM azide for 30 minutes (chemical anoxia) significantly inhibited the activity of ERK2 (measured as phospho-ERK) but the ERK-2 activity is...... rapidly increased in a MEK-independen manner, when azide is washed out of the cells. Chemical anoxia and overnight recovery induced Hsp70 expression (analyzed by Western blotting) and this was inhibited by actinomycin D as well as by cycloheximide showing that induction of both translation and...... transcription was involved. Inhibition of the MAP kinase p38, which was transiently activated during chemical anoxia, had no effect on the increase in Hsp70 expression whereas an inhibitor of reactive oxygen species and inhibition of the phosphatase PP1 and PP2a inhibited the increase in Hsp70 expression...

  7. 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) and......-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, these...

  8. Expression of α-Expansin and Xyloglucan Endotransglucosylase/Hydrolase Genes Associated with Shoot Elongation Enhanced by Anoxia, Ethylene and Carbon Dioxide in Arrowhead (Sagittaria pygmaea Miq.) Tubers

    OpenAIRE

    OOKAWARA, RYUTO; SATOH, SHIGERU; YOSHIOKA, TOSHIHITO; ISHIZAWA, KIMIHARU

    2005-01-01

    • Background and Aims Shoot elongation of arrowhead tubers (Sagittaria pygmaea Miq.) is stimulated by anoxia, ethylene and CO2. The aim of this study was to characterize anoxic elongation by comparison with elongation stimulated by ethylene and CO2.

  9. The relationship between NMDA receptor function and the high ammonia tolerance of anoxia-tolerant goldfish.

    Science.gov (United States)

    Wilkie, Michael P; Pamenter, Matthew E; Duquette, Stephanie; Dhiyebi, Hadi; Sangha, Navjeet; Skelton, Geoffrey; Smith, Matthew D; Buck, Leslie T

    2011-12-15

    Acute ammonia toxicity in vertebrates is thought to be characterized by a cascade of deleterious events resembling those associated with anoxic/ischemic injury in the central nervous system. A key event is the over-stimulation of neuronal N-methyl-D-aspartate (NMDA) receptors, which leads to excitotoxic cell death. The similarity between the responses to acute ammonia toxicity and anoxia suggests that anoxia-tolerant animals such as the goldfish (Carassius auratus Linnaeus) may also be ammonia tolerant. To test this hypothesis, the responses of goldfish were compared with those of the anoxia-sensitive rainbow trout (Oncorhynchus mykiss Walbaum) during exposure to high external ammonia (HEA). Acute toxicity tests revealed that goldfish are ammonia tolerant, with 96 h median lethal concentration (LC(50)) values of 199 μmol l(-1) and 4132 μmol l(-1) for NH(3) and total ammonia ([T(Amm)]=[NH(3)]+[NH(4)(+)]), respectively. These values were ~5-6 times greater than corresponding NH(3) and T(Amm) LC(50) values measured in rainbow trout. Further, the goldfish readily coped with chronic exposure to NH(4)Cl (3-5 mmol l(-1)) for 5 days, despite 6-fold increases in plasma [T] to ~1300 μmol l(-1) and 3-fold increases in brain [T(Amm)] to 6700 μmol l(-1). Muscle [T(Amm)] increased by almost 8-fold from ~900 μmol kg(-1) wet mass (WM) to greater than 7000 μmol kg(-1) WM by 48 h, and stabilized. Although urea excretion rates (J(Urea)) increased by 2-3-fold during HEA, the increases were insufficient to offset the inhibition of ammonia excretion that occurred, and increases in urea were not observed in the brain or muscle. There was a marked increase in brain glutamine concentration at HEA, from ~3000 μmol kg(-1) WM to 15,000 μmol kg(-1) WM after 48 h, which is consistent with the hypothesis that glutamine production is associated with ammonia detoxification. Injection of the NMDA receptor antagonists MK801 (0.5-8 mg kg(-1)) or ethanol (1-8 mg kg(-1)) increased trout

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

    OpenAIRE

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

    2010-01-01

    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...

  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. Interpreting the History of Lake Anoxia Using Iron and Sulfur Geochemistry

    Science.gov (United States)

    Ku, T.; Lozewski, J.; Ekdahl, E.; Teranes, J.

    2004-05-01

    Over the last thousand years, anthropogenic activities, such as land cultivation and atmospheric pollution, have increased the flux of growth-limiting nutrients to several North American lakes. The most common effect of this enhanced nutrient supply is a dramatic increase in the abundance of aquatic plants and algae. When these organisms die, the organic carbon in their remains falls through the water column and is oxidized by dissolved oxygen. Thus, eutrophic lakes are characterized by seasonally or permanently anoxic bottom waters because the rate of organic carbon oxidation exceeds the rate at which oxygen is replenished. The depletion of water column oxygen adversely affects lake ecosystems by decreasing water quality and by altering the community structure of fish and algae populations. In this study we examine the history of lake anoxia in two North American lakes, Half-Moon Lake in Michigan and Crawford Lake in Ontario. Sediment freeze cores and water column samples were taken from each site and both lakes contained well-preserved varved sediments. The sediments were analyzed for FeH (HCl-extractable iron), AVS (acid-volatile sulfur), CRS (chromium-reducible sulfur), d34S(CRS), CaCO3, CH2O, C/N, and d13C (CaCO3). Water samples were analyzed for pH, O2, cations, anions, and d34S(SO4). Today, Half-Moon Lake is seasonal anoxic while Crawford Lake has not overturned in the past ~15 years. Geochemical and biological data indicate that both lakes have experienced cultural eutrophication events in the 1800-1900s related to European-style agricultural practices. In addition, Crawford Lake experienced an earlier eutrophication episode around 1325 A.D. related to Iroquoian settlement of the area. Each eutrophication event showed an increase in the mass accumulation rate of pyritic sulfur, suggesting that sediments were exposed to longer durations of low-O2, H2S-rich waters during periods of cultural eutrophication. The geochemical parameter DOP (degree of pyritization

  13. 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.

  14. 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

    stress activated member of the mitogen-activated protein kinase family, p38MAPK and induction of heat shock protein (Hsp70) were evident. The time-course of the p38MAPK activation and the induction of Hsp70 expression in RTHDF were studied in response to chemically induced anoxia. p38MAPK was activated...... suggests that RTHDF can be useful in studying biochemical responses of teleost cells to environmental stress....

  15. 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.

  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

    )-agonists affect force and ion homeostasis in anoxic muscles. In the present study isolated rat extensor digitorum longus (EDL) muscles exposed to anoxia showed a considerable loss of force, which was markedly reduced by the β(2)-agonists salbutamol (10(-6) M) and terbutaline (10(-6) M). Intermittent......AMP stimulation of the Na(+),K(+)-pumps, and that it is not related to recovery of energy status (PCr, ATP, lactate)....

  17. 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

  18. 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.

  19. 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?

  20. 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.

  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. 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

  4. Development of anoxia during the last 90 years in Lake Tiefer See, NE Germany

    Science.gov (United States)

    Groß-Schmölders, Miriam; Dräger, Nadine; Kienel, Ulrike; Brauer, Achim

    2015-04-01

    medius in all water depths detectable; Asterionella, Fragilaria, Navicula, Stephanodiscus parvus, Synedra, Tabellaria in larger abundances only in the deeper parts; Aulacoseira mainly in the shallow areas. (4) Missing single varves have been only traced in the eastern part of the basin. Possible reasons for the observed differences including wind and wave activity near the shore-line and in shallow water, water circulation and lake bathymetry are discussed in this paper. The varves of Lake Tiefer See are part of an integrated multi-proxy study including high-resolution sediment analyses and monitoring of modern deposition processes within the Virtual Institute of Integrated Climate and Landscape Evolution Analysis -ICLEA- of the Helmholtz Association, grant number VH-VI-415. Reference KIENEL, U.; DULSKI, P.; OTT, F.; LORENZ, S.; BRAUER, A. (2013): Recently induced anoxia leading to the preservation of seasonal laminae in two NE-Germany lakes. Journal of Paleolimnology 50:535 - 544

  5. 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

    double mutant in the green alga Chlamydomonas reinhardtii lacking both PGRL1 and LHCSR3 expression. Phenotypic comparative analyses of this double mutant, together with the single knockout strains and with the P. patens pgrl1, demonstrated that PGRL1 is crucial for acclimation to high light and anoxia in...

  6. 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; Jarmer, Hanne Østergaard; Gracey, A.Y.; Cossins, A.R.

    2008-01-01

    designs, 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...

  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. 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

    1. Littorella uniflora and Lobelia dortmanna are prominent small rosette species in nutrient-poor, soft-water lakes because of efficient root exchange of CO2 and O2. We hypothesise that higher gas exchange across the leaves of L.similar to uniflora than of L.similar to dortmanna ensures O2 uptake...... 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....... 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...

  9. Anti-apoptotic response during anoxia and recovery in a freeze-tolerant wood frog (Rana sylvatica)

    Science.gov (United States)

    Gerber, Victoria E.M.; Wijenayake, Sanoji

    2016-01-01

    The common wood frog, Rana sylvatica, utilizes freeze tolerance as a means of winter survival. Concealed beneath a layer of leaf litter and blanketed by snow, these frogs withstand subzero temperatures by allowing approximately 65–70% of total body water to freeze. Freezing is generally considered to be an ischemic event in which the blood oxygen supply is impeded and may lead to low levels of ATP production and exposure to oxidative stress. Therefore, it is as important to selectively upregulate cytoprotective mechanisms such as the heat shock protein (HSP) response and expression of antioxidants as it is to shut down majority of ATP consuming processes in the cell. The objective of this study was to investigate another probable cytoprotective mechanism, anti-apoptosis during oxygen deprivation and recovery in the anoxia tolerant wood frog. In particular, relative protein expression levels of two important apoptotic regulator proteins, Bax and p-p53 (S46), and five anti-apoptotic/pro-survival proteins, Bcl-2, p-Bcl-2 (S70), Bcl-xL, x-IAP, and c-IAP in response to normoxic, 24 Hr anoxic exposure, and 4 Hr recovery stages were assessed in the liver and skeletal muscle using western immunoblotting. The results suggest a tissue-specific regulation of the anti-apoptotic pathway in the wood frog, where both liver and skeletal muscle shows an overall decrease in apoptosis and an increase in cell survival. This type of cytoprotective mechanism could be aimed at preserving the existing cellular components during long-term anoxia and oxygen recovery phases in the wood frog. PMID:27042393

  10. 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

  11. 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

  12. Biological and Morphological Aspects of Anoxia (Mesanoxia) matutinalis ssp. matutinalis Castelnau, 1832 (Coleoptera, Melolonthidae), a Pest of Apulian Pinewoods in Southern Italy

    OpenAIRE

    Eustachio Tarasco; Oreste Triggiani

    2011-01-01

    Huge defoliations by Anoxia (Mesanoxia) matutinalis spp. matutinalis Castelnau, 1832 (Coleoptera, Scarabeidae) have been observed in recent years in the coastal pinewoods (Pinus halepensis, P. pinea) of the southern Apulia Region of Italy. Starting from adults collected in the field, insect breeding was conducted in the laboratory, following the life-cycle from ovideposition to larval development and emergence. Observations were performed in the laboratory and the field to study the different...

  13. Astragaloside IV protects cardiomyocytes from anoxia/reoxygenation injury by upregulating the expression of Hes1 protein.

    Science.gov (United States)

    Huang, Huang; Lai, Songqing; Wan, Qing; Qi, Wanghong; Liu, Jichun

    2016-05-01

    Astragaloside IV (ASI), a traditional Chinese medicine, is a main active ingredient of Astragalus membranaceus. Many clinical studies have found that ASI protects cardiomyocytes in cardiovascular diseases, but the underlying mechanisms remain obscure. The aim of this study was to investigate the molecular mechanisms responsible for the protective effects of ASI in cardiomyocytes from anoxia/reoxygenation (A/R) injury. According to the previous studies, we hypothesized that the cardioprotective effects of ASI against A/R injury might be associated with Notch1/Hes1 signaling pathway. In this study, neonatal rat primary cardiomyocytes were preconditioned with ASI prior to A/R injury. Our results showed that ASI effectively increased the cell viability, decreased the content of MDA, decreased the activities of CPK and LDH, increased the activities of GSH-Px and SOD, and reduced the reactive oxygen species (ROS) generation and the loss of mitochondrial membrane potential (Δψm). ASI inhibited the mitochondrial permeability transition pore (mPTP) opening and activation of caspase-3, and finally decreased the cell apoptosis in cardiomyocytes. Furthermore, ASI upregulated Hes1 protein expression. However, pretreatment with DAPT, a Notch1 inhibitor, effectively attenuated the cardioprotective effects of ASI against A/R injury, except MDA, SOD, GSH-Px, and the ROS generation. Taken together, we demonstrated that ASI could protect against A/R injury via the Notch1/Hes1 signaling pathway. PMID:27070866

  14. High-precision geochronology links the Ferrar large igneous province with early-Jurassic ocean anoxia and biotic crisis

    Science.gov (United States)

    Burgess, S. D.; Bowring, S. A.; Fleming, T. H.; Elliot, D. H.

    2015-04-01

    Apparent synchrony between eruption/emplacement of large igneous province (LIP) magmas and mass extinction has led to the implication of magmatism as a primary trigger of global scale environmental change. Evaluating the efficacy of magmatism as a driver of global change depends on the relative timing of magmatism and environmental change, and the magma effusion/intrusion rate, both of which can be constrained by high-precision geochronology. Early Jurassic (Pliensbachian-Toarcian) global ocean anoxia and acidification, carbon isotope perturbations, and biotic crisis have been linked to "synchronous" eruption and emplacement of the Karoo and Ferrar LIPs. To better constrain the timing and duration of Ferrar magmatism, we apply the single crystal, chemical abrasion U-Pb ID-TIMS method to zircon crystals isolated from twenty Ferrar LIP sills and lavas, and the Dufek intrusion. Dates suggest that both intrusive and extrusive Ferrar magmatism occurred over an interval of 349 ± 49 kyr, beginning with intrusive magmatism as early as 182.779 ± 0.033 Ma. Lava eruption was synchronous with, and in some cases postdates intrusion. When coupled with existing geochronology on the Karoo province, our dates confirm broad synchrony between Karoo and Ferrar magmatism, though Karoo magmatism began demonstrably prior to Ferrar magmatism, starting as early as 183.246 ± 0.045 Ma. The short-lived magmatic history of the Ferrar LIP makes it a plausible trigger for early-Jurassic environmental change.

  15. 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

  16. Involvement of Bcl-2 Signal Pathway in the Protective Effects of Apigenin on Anoxia/Reoxygenation-induced Myocardium Injury.

    Science.gov (United States)

    Chen, Chuanjun; He, Huan; Luo, Yong; Zhou, Min; Yin, Dong; He, Ming

    2016-02-01

    Apigenin is a type of flavonoids, which has been demonstrated to protect myocardium against ischemia/reperfusion (I/R) injury. However, the mechanism is still unclear. We hypothesized that the mechanism of cardioprotective action of apigenin on the I/R-induced injury might be caused via B-cell lymphoma (Bcl) signaling pathway. In this study, an in vitro I/R model was replicated on Langendorff-perfused heart and H9c2 cardiomyocytes by anoxia/reoxygenation (A/R) treatment. The recovery of cardiac contractile function, infarct size, lactate dehydrogenase (LDH) and creatine kinase (CK) in the perfusate, the expression and activity of Bcl-2 and caspase-3, and cardiomyocyte apoptosis were measured in the Langendorff heart undergoing A/R injury. In addition, the cell viability, LDH release, intracellular reactive oxygen species (ROS), mitochondrial membrane potential (Δψm), expression of cytochrome c in the cytosol, and cell apoptosis were examined in the culture of H9c2 cardiomyocytes after the A/R. The results showed that apigenin significantly improved rat heart contractile function, reduced LDH release, infarct size and apoptotic rate, upregulated the expression of Bcl-2 and caspase-3, and downregulated the expression of cleaved caspase-3 after the A/R. Moreover, apigenin increased the cell viability and decreased the release of LDH, production of reactive oxygen species, release of mitochondrial cytochrome c into the cytosol, and cell apoptosis in the culture of H9c2 cardiomyocytes after the A/R. In addition, inhibition of Bcl-2 activity by ABT-737 markedly attenuated the protective effect of apigenin on the A/R-induced myocardium injury. Taken together, we firstly demonstrated that the effect of apigenin against A/R injury in cardiomyocytes involves Bcl-2 signal pathway and at least partly depends on its effect of upregulating the expression of Bcl-2. PMID:26466327

  17. Puerarin Attenuates Anoxia/Reoxygenation Injury Through Enhancing Bcl-2 Associated Athanogene 3 Expression, a Modulator of Apoptosis and Autophagy.

    Science.gov (United States)

    Ma, Yayu; Gai, Ya; Yan, Jingpeng; Li, Jian; Zhang, Yangyang

    2016-01-01

    BACKGROUND Puerarin has protective effects on ischemia-reperfusion injury, but the underlying mechanisms are not fully revealed. This study explored the effect of puerarin on the expression of Bcl-2 associated athanogene 3 (BAG3) in an in vitro model of anoxia/reoxygenation injury (A/RI) in neonate rat primary cardiomyocytes and the functions of BAG3 in A/RI. MATERIAL AND METHODS BAG3 expression in cardiomyocytes with or without puerarin pre-treatment was quantified using qRT-PCR and Western blot analysis. The effects of BAG3 on A/RI were studied by measuring the activity of lactate dehydrogenase (LDH) and creatine phosphate kinase (CPK), the concentration of malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px). The effects of BAG3 on autophagy and apoptosis of the cardiomyocytes after A/RI were further studied. RESULTS Puerarin significantly promoted BAG3 expression in the rat primary cardiomyocytes after A/RI. Enforced BAG3 expression presented similar effects as puerarin pre-treatment in attenuating A/RI in terms of CPK, LDH, MDA, SOD, GSH-Px, ROS generation, and cell viability. BAG3 overexpression significantly stimulated autophagy in cardiomyocytes after A/RI, which presented protective effects on A/RI in terms of cell viability and apoptosis. Autophagy inhibition partly abrogated the protective effects of BAG3. CONCLUSIONS Puerarin can directly increase BAG3 transcription and translation in cardiomyocytes after A/RI. The elevated BAG3 expression presents protective effects on A/RI at least through enhancing autophagy and reducing apoptosis, which is a novel protective mechanism of puerarin in ARI. PMID:27011313

  18. 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; Pedersen, Stine F

    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......(+))], prevented recovery of intracellular pH (pH(i)) during chemical anoxia (10 mM NaN(3) +/- 10 mM glucose), indicating that activation of NHE was the dominating mechanism of pH(i) regulation under these conditions. NHE activation by chemical anoxia was unaffected by inhibitors of p38 MAPK (SB203580) 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...

  19. Tolerancia a la anoxia y defensas antioxidantes en el mejillón verde Perna viridis (Linneus, 1758 bajo exposición aguda al cadmio

    Directory of Open Access Journals (Sweden)

    Edgar Zapata-Vívenes

    2014-07-01

    Full Text Available Se estimó la sobrevivencia a la anoxia del mejillón verde Perna viridis después de siete días de exposición a 50 μg L-1 de cadmio (Cd, seguido de un período de recuperación en el mar durante 21 días. En la glándula digestiva de los organismos experimentales se determinó los niveles de Cd acumulados, y marcadores de estrés oxidativo tales como: metalotioneínas (MT, glutatión reducido (GSH, peroxidación lipídica (TBARS y las actividades de las enzimas catalasa (CAT, glutatión reductasa (GR y glutatión-S-transferasa (GST. Los organismos expuestos a Cd mostraron una menor tolerancia al tratamiento anóxico, sin embargo una vez recuperados en el mar presentaron valores de sobrevivencia relativamente mayores en comparación a sus controles. Los organismos expuestos a Cd revelaron un incremento en la concentración de MT y la actividad de CAT, correlacionado al ingreso corporal de Cd. Los organismos transplantados al mar mostraron una disminución del metal acumulado, manteniendo niveles de MT incrementados. Los mejillones tratados y controles no exhibieron diferencias significativas en los marcadores de estrés oxidativo determinados (TBARS, GSH, GR y GST. El Cd acumulado posiblemente afectó algunas estrategias bioquímicas relacionadas con la tolerancia a la anoxia de P. viridis. Sin embargo, los altos niveles de MT en organismos pre-expuestos y posteriormente recuperados, podría condicionar la protección contra la toxicidad del Cd e indirectamente una mayor tolerancia a la anoxia.

  20. 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.

  1. Biological and Morphological Aspects of Anoxia (Mesanoxia) matutinalis ssp. matutinalis Castelnau, 1832 (Coleoptera, Melolonthidae), a Pest of Apulian Pinewoods in Southern Italy Aspetos da Biologia e Morfologia da Anoxia (Mesanoxia) matutinalis ssp. matutinalis Castelnau, 1832 (Coleoptera, Melolonthidae), Praga nos Pinhais da Apúlia, Sul de Itália

    OpenAIRE

    Eustachio Tarasco; Oreste Triggiani

    2011-01-01

    Huge defoliations by Anoxia (Mesanoxia) matutinalis spp. matutinalis Castelnau, 1832 (Coleoptera, Scarabeidae) have been observed in recent years in the coastal pinewoods (Pinus halepensis, P. pinea) of the southern Apulia Region of Italy. Starting from adults collected in the field, insect breeding was conducted in the laboratory, following the life-cycle from ovideposition to larval development and emergence. Observations were performed in the laboratory and the field to study the different...

  2. 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

  3. 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)

  4. 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

  5. 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

  6. Complete mitochondrial genomes of the yellow-bellied slider turtle Trachemys scripta scripta and anoxia tolerant red-eared slider Trachemys scripta elegans.

    Science.gov (United States)

    Yu, Danna; Fang, Xindong; Storey, Kenneth B; Zhang, Yongpu; Zhang, Jiayong

    2016-05-01

    The complete mitochondrial genomes of the yellow-bellied slider (Trachemys scripta scripta) and anoxia tolerant red-eared slider (Trachemys scripta elegans) turtles were sequenced to analyze gene arrangement. The complete mt genomes of T. s. scripta and elegans were circular molecules of 16,791 bp and 16,810 bp in length, respectively, and included an A + 1 frameshift insertion in ND3 and ND4L genes. The AT content of the overall base composition of scripta and elegans was 61.2%. Nucleotide sequence divergence of the mt-genome (p distance) between scripta and elegans was 0.4%. A detailed comparison between the mitochondrial genomes of the two subspecies is shown. PMID:25541313

  7. 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

  8. 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)

  9. 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

    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 of...

  10. 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.

  11. 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.

  12. MicroRNA‑451 protects against cardiomyocyte anoxia/reoxygenation injury by inhibiting high mobility group box 1 expression.

    Science.gov (United States)

    Xie, Jing; Hu, Xiaorong; Yi, Chunfeng; Hu, Gangying; Zhou, Xiaoya; Jiang, Hong

    2016-06-01

    High mobility group box 1 (HMGB1) protein serves an important role in myocardial ischemia/reperfusion (I/R) injury. MicroRNAs (miRNAs) are a group of small non‑coding RNAs that regulate numerous signaling pathways involved in myocardial I/R injury. The present study aimed to investigate whether miR‑451 protects against cardiomyocyte anoxia/reoxygenation (A/R) injury by attenuating HMGB1 expression. Neonatal rat ventricular cardiomyocytes were prepared and then subjected to A/R injury. The effect of upregulation or downregulation of miR‑451 on cell viability, apoptosis, superoxide dismutase (SOD) activity, and the expression of cleaved‑caspase‑3 and HMGB1 were measured accordingly. A luciferase assay was performed to further confirm whether miR‑451 can directly recognize the 3'‑untranslated region of HMGB1 in HEK293 cells. The expression of miR‑451 was significantly decreased in the cardiomyocytes during A/R, and upregulation of miR‑451 led to increased miR‑451 expression (P<0.05). Upregulation of miR‑451 significantly attenuated the loss of cardiomyocyte viability (P<0.05) and increased the intracellular levels of SOD during A/R (P<0.05). Furthermore, upregulation of miR‑451 significantly decreased the apoptosis of cardiomyocytes during A/R (P<0.05). The HMGB1 mRNA and protein expression levels were significantly downregulated in the Ad‑miR‑451 group compared with those in the A/R group (P<0.05). In addition, upregulation of miR‑451 reduced its translocation from the nucleus to the cytoplasm. The luciferase assay confirmed that HMGB1 mRNA is a direct target of miR‑451 in cardiomyocytes. In conclusion, the present study suggested that upregulation of miR‑451 could protect against A/R‑induced cardiomyocyte injury by inhibiting HMGB1 expression. PMID:27121079

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. Transformation of herbicides under transient anoxia

    Science.gov (United States)

    Resurgence in the use of soil-applied residual herbicides to augment performance of failing post-emergence herbicides has predictably reignited concerns over potential offsite movement, carryover damage onsite, or potential herbicide failure due to accelerated degradation. Many of the key processes ...

  1. 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.

  2. 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。

  3. 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

  4. 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

  5. The influence of anoxia and local radiotherapy on implantation metastases

    International Nuclear Information System (INIS)

    The survival rate for carcinoma of the breast has hardly improved during the last decades, in spite of many of attempts to attain better results by drastic changes in the methods of treatment. This is equally true of the frequent local recurrences in the former area of operation, often after a period of many years, so when a complete cure has already been assumed by patient and doctor. This local recurrence is nearly always followed after a short period by the symptoms of a complete dissemination, which invariably leads to a lethal end. This thesis deals with the local recurrences. For that purpose a study has been made of the available literature, which has been described in the first part and a number of prophylactic measures has been mentioned in this same part. The influence of anoxaemia and radiotherapy on local recurrence is also discussed. For the time being, in preventing local recurrence of carcinoma of the breast chemotherapy does not seem to be a substitute for the loco-regional directed surgery and radiotherapy, but does seem to be a complementary. Local treatment, if longer survival is achieved by the use of chemotherapeutics, whereby a longer period is available for the originating of a local recurrence. (Auth.)

  6. Causes and consequences of mid-Proterozoic anoxia

    Science.gov (United States)

    Derry, Louis A.

    2015-10-01

    Evidence for low pO2 and a ferruginous ocean characterize the mid-Proterozoic (1.8-0.8 Ga). Considerations of redox sources and sinks imply that generation of O2 via organic carbon (Corg) burial must be low to maintain a low pO2 atmosphere for geologically long intervals, yet low oxygen should result in increased Corg preservation. Marine export production must therefore be low to limit Corg burial and O2 generation. Formation of ferrous phosphate can buffer deepwater phosphate (Pi) to levels an order of magnitude or more below those in the modern ocean, limiting export production. Low deepwater Pi is consistent with the hiatus in sedimentary phosphorite deposits during the mid-Proterozoic, and low pO2 limits formation of sedimentary iron deposits (BIF). We propose that low pO2 was maintained by P limitation resulting from ferrous phosphate buffering. The near-absence of BIF and phosphorite deposition is direct and indirect consequences of the low pO2, respectively.

  7. OXYGEN REGIMES IN ESTUARIES: IMAGING ANOXIA THROUGH NORMOXIA

    Science.gov (United States)

    The U.S. EPA, National Health and Environmental Effects Research Laboratory, Atlantic Ecology Division, is developing empirical stressor-response models linking nitrogen loading to near-bottom dissolved oxygen (DO) concentrations in semi-enclosed coastal systems. Sediment profil...

  8. 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.

    -poor, nutrient-rich subsurface waters to the Indian continental shelf that turn anoxic (sulfate-reducing) by late summer due to exhaustion of oxygen and nitrate by heterotrophic microorganisms. This natural oxygen-deficient system, by far the world’s largest...

  9. 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...

  10. 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....

  11. Catastrophic anoxia in the chesapeake bay in 1984.

    Science.gov (United States)

    Seliger, H H; Boggs, J A; Biggley, W H

    1985-04-01

    In 1984, four climatic sequences combined to produce what may be a major anoxic catastrophe in the northern Chesapeake Bay, sufficient to severely threaten the major benthic species. These sequences are (i) the highest late-winter streamflow on record from the Susquehanna River watershed; (ii) streamflows from the Susquehanna River for the consecutive months of June, July, and August that are higher by 2 standard deviations than the respective monthly mean values measured over the last 34 years; (iii) a stationary high in August off the Atlantic Coast; and (iv) an absence of strong storm events in summer. An empirical equation is proposed for the prediction of the monthly trend of dissolved oxygen decrease in terms of a temperature-dependent subpycnoclinal respiration and a modified estuarine Richardson number. As of 23 August 1984, the summer pycnocline of the northern bay had eroded upward from its historically recorded depth below 10 meters to an abnormally shallow 5 meters, with higher stratification than in earlier years. Dissolved oxygen concentrations directly below the pycnocline decreased to zero during June, 2 months earlier than for previous wet years. At present, oxygen-deficient waters containing significant concentrations of hydrogen sulfide have penetrated into Eastern Bay and the Choptank and Potomac rivers. Because most remaining shellfish-spawning and seed-bed areas in these tributaries are located at depths between 4 and 8 meters, the continued absence of major destratifying events will prolong the present anoxic trend and may result in high benthic mortalities. PMID:17811570

  12. 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.)

  13. 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.

  14. 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.

    microscope (Olympus IX 51; 400X). Phytoplankton taxa were identified following Tomas (1997), Subramanyan (1946, 1968), Lebour (1978). For carbon conversion, phytoplankton was broadly classified as diatoms and non-diatoms. Their bio-volumes were separately...-volume of dominant diatom and non-diatom taxa were then applied to other less dominant taxa (numerically contributing <5%) for carbon conversion. Since samples were analyzed immediately, effect of preservation and storage was not considered in this study. Wind...

  15. 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

  16. Anoxia, sealevel changes and mass extinctions at the Devonian/Carboniferous boundary

    Science.gov (United States)

    Kaiser, S. I.; Steuber, T.; Becker, R. T.

    2003-04-01

    During the Latest Devonian, the transition from global greenhouse to icehouse conditions began with a first glaciation pulse in SW Gondwana. Decisive palaeoclimatic and palaeoceanographic changes are reflected in the multiphase Late Devonian Hangenberg Event. Mass extinctions, blackshale and sandstone deposits in different palaeogeographical settings were the result of eustatic sea level changes, and probably also of variations in the composition and temperature of seawater during the Late Devonian -- Early Carboniferous. The investigated boundary sections from different palaeogeographical settings include localities in Europe and North Africa. Detailed bed-by-bed sampling of limestones, and field observations on the sedimentology of intercalated siliciclastics were considered important in order to achieve a high-resolution biostratigraphical zonation, precise records of biofacies evolution, and correlation of changes in sedimentary environments. The carbon isotopic composition of micritic limestones and the oxygen isotopic composition of conodont apatite provide important information about palaeoceanographic changes and perturbations in the global carbon cycle during the event interval. Detailed investigations of the sedimentology in Moroccan sections indicate significant variations of facies patterns over short distances. The Famennian pelagic carbonate platform of North-Gondwana was not re-established in the latest Famennian or in the post-event early Tournaisian, which yielded new rich goniatites from blackshales and sandstones. These observations and microfacies analyses from other sections of different palaeolatitudes are important for the reconstruction and correlation of global transgression-regression cycles. The first results of biostratigraphical correlations will be presented together with carbon isotope data of micritic limestone collected from boundary sections in the Rheinische Schiefergebirge and in the Carnic Alps. A slight but continuous decrease of δ13C from the expansa to the sandbergi Zone occurs in all studied sections of the Rheinisches Schiefergebirge, but no reliable data are present for the clastic units of the event interval. A distinct carbon isotope excursion up to +4 ppm δ13C in the praesulcata zone was found by detailed sampling of the Grüne Schneid section in the Carnic Alps. This excursion is most probably time-equivalent to the deposition of black shales elsewhere, and indicates widespread oceanic anoxic conditions during an episode of sealevel highstand, related to the onset of the main phase of the Hangenberg Event.

  17. 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

  18. 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‰).

  19. Improving Functional Skills Using Behavioral Procedures in a Child with Anoxia.

    Science.gov (United States)

    Silver, Bernard; And Others

    A behavioral treatment program was used to improve the functional skills of a 12-year-old anoxic child. Neuropsychological test results indicated marked amnesia and global cognitive deficits. Functionally, self-care tasks could be performed, but only with verbal and physical prompting. Introduction of a monetary reward system significantly reduced…

  20. Long-term anoxia and release of ancient, labile carbon upon thaw of Pleistocene permafrost

    Science.gov (United States)

    Ewing, Stephanie A.; O'Donnell, Jonathan A.; Aiken, George R.; Butler, Kenna; Butman, David; Windham-Myers, Lisamarie; Kanevskiy, Mikhail Z.

    2015-12-01

    The fate of permafrost carbon upon thaw will drive feedbacks to climate warming. Here we consider the character and context of dissolved organic carbon (DOC) in yedoma permafrost cores from up to 20 m depth in central Alaska. We observed high DOC concentrations (4 to 129 mM) and consistent low molecular weight organic acid concentrations in three cores. We estimate a DOC production rate of 12 µmol DOC m-2 yr-1 based on model ages of up to ~200 kyr derived from uranium isotopes. Acetate C accounted for 24 ± 1% of DOC in all samples. This proportion suggests long-term anaerobiosis and is likely to influence thaw outcomes due to biolability of acetate upon release in many environments. The combination of uranium isotopes, ammonium concentrations, and calcium concentrations explained 86% of the variation in thaw water DOC concentrations, suggesting that DOC production may be related to both reducing conditions and mineral dissolution over time.

  1. 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.

    -mediated toxicity (Halliwell 1978, Halliwell & Gutteridge 1986, Pryor & Godber 1991, Winston & Di Giulio 1991, Ahmad 1995). B. amphitrite is regularly exposed in the intertidal area of the study region to tidal fluctuations from 0.25 to 2.5m. Being an intertidal... #................... 17 REFERENCES Ahmad S (1995) Antioxidant mechanism of enzymes and proteins. In: S. Ahmad (ed) Oxidative stress and Antioxidant defenses in Biology, Chapman and Hall, New York, p 238-272 Anger K, Dawirs RR (1981) Influence of starvation...

  2. 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

    Environmental metabolomics has become interesting in marine ecological studies. One example is the revealing of new insights in stress response of Zostera marina. This is essential to understand how, at which level and to what extend aquatic plants adapt, tolerate and react to environmental stres...

  3. 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.

  4. 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.

    concentration are caused by increasing runoff of nutrients from land. Although the local ecological and socio-economic effects have received much attention, the potential contribution of increasing hypoxia to global-change phenomena is unknown...

  5. 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...

  6. 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...

  7. Inorganic geochemical indicators of glacial-interglacial changes in productivity and anoxia on the California continental margin

    Science.gov (United States)

    Dean, W.E.; Gardner, J.V.; Piper, D.Z.

    1997-01-01

    Evidence from sediments in cores collected from within the present oxygen-minimum zone (OMZ; 600-1200 m) on the central and northern California margins record several episodes during the last interstadial (OIS-3, ca. 60-24 ka) of deposition of laminated sediments containing elevated concentrations of several trace elements indicative of anoxic conditions (e.g., Mo, Ni, Zn, and Cu). The presence of abundant well-preserved organic matter, as well as lack of bioturbation and the presence of elevated concentrations of Mo and other trace elements, all support the theory that the OMZ in the northeastern Pacific Ocean was more intense, possibly anoxic, at several times during the late Pleistocene. Sediments of all ages in cores from the southern California margin contain elevated concentrations of Mo, suggesting that this area has always had higher rates of sulfate reduction than either the central or northern California areas. Most of the Ba in sediments in all cores collected on the upper continental slope (200-2700 m) off California and southern Oregon is derived from detrital clastic material, and this source did not change much in time. However, the amount of biogenic Ba did vary with time, and these variations closely follow the temporal variations in organic C (Corg) mass accumulation rate. Using Ba and Corg mass accumulation rates as proxy variables for productivity, all cores show that organic productivity under the California Current upwelling system was highest during OIS-3 and the Holocene, and lowest during the last glacial interval (LGI, ca. 24-10 ka). All paleoproductivity proxy variables indicate that the southern California area has always experienced higher productivity than other areas under the California Current, at least over the last 50 ky. Copyright ?? 1997 Elsevier Science Ltd.

  8. Plant anaerobic stress II. Strategy of avoidance of anaerobiosis and other aspects of plant life under hypoxia and anoxia

    Science.gov (United States)

    This article is a logical follow-up of previous publications (Vartapetian and Crawford 2007; Sachs and Vartapetian 2007) where an attempt was made to summarize the results of earlier periods of investigations of plant anaerobic stress and the activity of members of the International Society for Plan...

  9. 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

  10. 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.

  11. Multi proxy records of trophic state and hypolimnetic anoxia in a large hard-water lake (lake Bourget, french Alps)

    OpenAIRE

    Giguet-Covex, Charline; MILLET, Laurent; Verneaux, Valéry; Druart, Jean-Claude; Adatte, Thierry; Reyss, Jean Louis; Lazzarotto, Jérôme; Poulenard, Jérôme; Arnaud, Fabien; Enters, Dirk

    2010-01-01

    Instrumental data about lake functioning before anthropogenic disturbances of the last century are scarce and often discontinuous. A paleolimnological study through sedimentological, geochemical (mineral and organic), chironomid and diatom assemblages analyses has been applied to reconstruct the trophic state and hypolimnion oxygenation changes in Lake Bourget during the last century. This approach presents also the interest to permit the access to the reference state of lake in the sense of ...

  12. Two novel anoxia-induced ethylene response factors that interact with promoters of deastringency-related genes from persimmon.

    Directory of Open Access Journals (Sweden)

    Ting Min

    Full Text Available A hypoxic environment is generally undesirable for most plants and stimulates anaerobic metabolism. It is a beneficial treatment, however, for the removal of astringency from persimmon to improve the fruit quality after harvest. High soluble tannins (SCTs content is one of most important causes of astringency. High CO2 (95% treatment effectively reduced SCTs in both "Mopan" and "Gongcheng-shuishi" persimmon fruit by causing increases in acetaldehyde. Using RNA-seq and realtime PCR, twelve ethylene response factor genes (DkERF11-22 were isolated and characterized, to determine those responsive to high CO2 treatment. Only two genes, DkERF19 and DkERF22, showed trans-activation effects on the promoters of deastringency-related genes pyruvate decarboxylase genes (DkPDC2 and DkPDC3 and the transcript levels of these genes was enhanced by hypoxia. Moreover, DkERF19 and the previously isolated DkERF9 had additive effects on activating the DkPDC2 promoter. Taken together, these results provide further evidence that transcriptome changes in the level of DkERF mRNAs regulate deastringency-related genes and their role in the mechanism of persimmon fruit deastringency is discussed.

  13. Alternative acetate production pathways in Chlamydomonas reinhardtii during dark anoxia and the dominant role of chloroplasts in fermentative acetate production.

    Science.gov (United States)

    Yang, Wenqiang; Catalanotti, Claudia; D'Adamo, Sarah; Wittkopp, Tyler M; Ingram-Smith, Cheryl J; Mackinder, Luke; Miller, Tarryn E; Heuberger, Adam L; Peers, Graham; Smith, Kerry S; Jonikas, Martin C; Grossman, Arthur R; Posewitz, Matthew C

    2014-11-01

    Chlamydomonas reinhardtii insertion mutants disrupted for genes encoding acetate kinases (EC 2.7.2.1) (ACK1 and ACK2) and a phosphate acetyltransferase (EC 2.3.1.8) (PAT2, but not PAT1) were isolated to characterize fermentative acetate production. ACK1 and PAT2 were localized to chloroplasts, while ACK2 and PAT1 were shown to be in mitochondria. Characterization of the mutants showed that PAT2 and ACK1 activity in chloroplasts plays a dominant role (relative to ACK2 and PAT1 in mitochondria) in producing acetate under dark, anoxic conditions and, surprisingly, also suggested that Chlamydomonas has other pathways that generate acetate in the absence of ACK activity. We identified a number of proteins associated with alternative pathways for acetate production that are encoded on the Chlamydomonas genome. Furthermore, we observed that only modest alterations in the accumulation of fermentative products occurred in the ack1, ack2, and ack1 ack2 mutants, which contrasts with the substantial metabolite alterations described in strains devoid of other key fermentation enzymes. PMID:25381350

  14. 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

    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 is...

  15. 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.

  16. The anti-angiogenic factor PEDF is present in the human heart and is regulated by anoxia in cardiac myocytes and fibroblasts

    OpenAIRE

    Rychli, Kathrin; Kaun, Christoph; Hohensinner, Philipp J.; Dorfner, Adrian J; Pfaffenberger, Stefan; Niessner, Alexander; Bauer, Michael; Dietl, Wolfgang; Podesser, Bruno K.; Maurer, Gerald; Huber, Kurt; Wojta, Johann

    2009-01-01

    Abstract Cardiac diseases such as myocardial infarction and heart failure are among the leading causes of death in western societies. Therapeutic angiogenesis has been suggested as a concept to combat these diseases. The biology of angiogenic factors expressed in the heart such as vascular endothelial growth factor (VEGF) is well studied, whereas data on anti-angiogenic mediators in the heart are scarce. Here we study the expression of the anti-angiogenic factor pigment epithelium-derived fac...

  17. Effect of anoxia on choline uptake and release of acetylcholine in brain slices estimated with a bioradiographic technique using [11C] choline

    International Nuclear Information System (INIS)

    The uptake of choline for the synthesis and release of acetylcholine and the metabolism of glucose under anoxic conditions was investigated in brain slices by bioradiography using [N-methyl-11C]choline ([11C]choline) and [18F]2-fluoro-2-deoxy-D-glucose ([18F]FDG). [11C]Choline uptake and the release of accumulated 11C radioactivity in brain slices decreased with anoxic treatment, whereas [18F]FDG uptake increased. The decrease of [11C]choline uptake and the 11C radioactivity accumulated in striatal slices were recovered by acetyl-L-carnitine, an acetyl-donor. However, this effect was not seen in cerebral cortex. These results indicate that choline uptake for the synthesis and release of acetylcholine in brain are energy sensitive. The cholinergic dysfunction in ischemic brain might be improved by compensating for energy loss. (author)

  18. Etiology and radiologic findings of anoxia occurred at Dan-Mu-Ji(Salted radish in rice bran) manufacture: A case report and results of gas analysis

    International Nuclear Information System (INIS)

    To identify the main toxic gas released from salted radish in rice bran(Dan-Mu-Ji) and to introduce the radiological findings of the patient who was exposed to the gas. Chest radiographs and CT scans of one survivor among three men who were exposed to the gas from Dan-Mu-Ji were reviewed. Gas obtained from the closed bottle containing Dan-Mu-Ji was analyzed by using the gas chromatography. The radiographic examinations of the survivor were suggestive of pulmonary edema with it's rapidly improving consideration in both lung. The headspace gas within the bottle containing Dan-Mu-Ji was mainly composed with carbon dioxide, ethyl alcohol and hydrogen sulfide, of which hydrogen sulfide was considered the main toxic gas released. Under the anaerobic condition, Dan-Mu-Ji released toxic hydrogen sulfide. Inhalation of hydrogen sulfide might produce non-cardiogenic pulmonary edema

  19. Anoxia and possible export production spikes in the Red Sea during Termination II: evidence from U-decay series and organic C concentrations

    Science.gov (United States)

    Torfstein, A.; Almogi-Labin, A.; McManus, J. F.

    2014-12-01

    The late Quaternary history of the Red Sea is characterized by sharp increases in sea surface salinity during glacial maxima in response to global sea level drop. These imposed an extremely weak current exchange between the Red Sea and the Indian Ocean through the Bab-el-Mandeb Straits that resulted in temporal changes in stratification, productivity and subsurface oxygenation of the Red Sea. The combined effect of these perturbations has been interpreted to impose extended aplanktonic zones in Red Sea sediments centered at glacial maxima. Yet the dynamics of the transition between glacial and interglacial stages in the Red Sea are still not well understood. Here, we present evidence for the occurrence of a strong anoxic episode during the penultimate transition from Marine Isotope Stage (MIS) 6 to MIS5 (Termination II) based on uranium concentrations, isotopic ratios, and organic carbon concentrations (Corg) studied in core KL23 taken by R/V Meteor from northern Red Sea (24o44.88'N 35o03.28'E) at 702 m water depth. (234U/238U) activity ratios and U concentrations start rising from their MIS6 levels (~1 and 1.9 ppm, respectively) ca. 140 ka, and peak at 135-132 ka (1.08 and 3.1 ppm). These patterns are matched by changes in Corg, and the onset of all slightly precedes sea level rise patterns. Thereafter, uranium and Corg decrease sharply, reaching minima that characterizes the rest of MIS5e, ca. 130 ka. Uranium activity ratios however, decrease gradually from their deglacial peak to a minimum value (~0.94) at 122 ka. In view of the redox sensitive behavior of U, the buildup of U concentrations would support anoxic conditions, rather than a rise in export production, as the most likely explanation for the preservation of Corg in the sediments. Yet, the high (234U/238U) values that imply a dominance of open seawater U in the samples, together with d13C values of foraminifera bracketing the studied interval that display a depletion trend indicating an increase in primary production, both suggest that an increase in export production cannot be ruled out as the source of high Corg in the sediments. We will evaluate the possibility of an increase in export production that is coeval with the aplanktonic zone in this core in the context of 230Th excess data, sea level changes and paleo-circulation of the Red Sea.

  20. RELATIVE INFLUENCE OF HYPOXIA, ANOXIA, AND ASSOCIATED ENVIRONMENTAL FACTORS AS DETERMINANTS OF MACROBENTHIC COMMUNITY STRUCTURE IN A NORTHERN GULF OF MEXICO ESTUARY

    Science.gov (United States)

    Seasonal patterns (i.e., December 1986, and April and October 1987) in benthic macroinfaunal abundance, distribution, and taxa composition at 19 sites in Perdido Bay, AL/FL, are evaluated to assess the relative importance of environmental factors as determinants of community stru...

  1. Experimental Study on the Mechanism o£ Cardiac Failure in the Diffuse Anoxia and Acute Local Ischemia of Myocardium in Dogs

    Directory of Open Access Journals (Sweden)

    Nasser Guiti

    1971-07-01

    Full Text Available The acute diffuse hypoxia in dogs by general hypoxia, ligation of the coronary arteries and perfusion of the coronaries in the diffuse hypoxic hear ts. T he results of our experiments suggest that the quantitative diminu tion of oxygen and bloo d supply to the myocardium is, rather than oxygen differential , a determining fa ctor for development of ventr icular fi brillat ion or cardiac arrest.

  2. Molybdenum accumulation in Cariaco basin sediment over the past 24 k.y.: A record of water-column anoxia and climate

    Science.gov (United States)

    Dean, W.E.; Piper, D.Z.; Peterson, L.C.

    1999-01-01

    Molybdenum (Mo) concentrations in a sediment core from the Cariaco basin on the Venezuelan continental shelf can be partitioned between a marine fraction and a terrigenous fraction. The accumulation rate of the marine fraction of Mo increased abruptly 15 000 calendar years ago (15 ka), from 4 ??g ?? cm-2 ?? yr-1, and then decreased abruptly at 9 ka. The accumulation rate remained high throughout this 6 k.y. period, but exhibited maxima at 15-14 and 12.5 ka, corresponding in time to meltwater pulse IA into the Gulf of Mexico and the onset of the Younger Dryas cold event, respectively. The marine fraction of Mo is interpreted in terms of redox conditions of bottom water, as dictated by both the flux of settling organic matter and bottom-water residence time. Correspondence between geochemical extremes in this core with changes in sea level and global climate demonstrates the high degree to which this ocean-margin basin has responded to the paleoceanographic regime throughout the past 24 k.y.

  3. Numerical Modeling of the Impact of the River Runoff on the Formation of the Anoxia in the Kangjin Bay, South Sea, Korea

    Science.gov (United States)

    Ro, Y.

    2005-05-01

    Introduction The Kangjin Bay, located in the central part of the South Sea of Korea, is interconnected to neighboring bays and the South Sea through the three narrow channels. The geometry is very complex and the depth is less than 20 m in general. The width at the narrowest site of the Noryang Channel is about 500 m, and the narrowest width of the Changson Channel is about 300 m. The bay receives the Sumjin and Namgang River runoff from the north. The averaged annual discharge of the Sumjin River is about 120 cms. The main objectives of this study to understand the circulation pattern in the Kangjin Bay by tidal current and the impact of the river runoff from the Sumjin River on the ecosystem in the Bay. The Kangjin Bay has been a renowned aqua-culturing bed for several important shellfishes such as large arc shell (Scapharca broughtonii) and short-necked clam(Tapes philippinarum) et al. The water quality, current and meteorological conditions are continuously monitored with very high sampling resolution (10 min.) throughout the year and is published on the Internet web pages (http://oceaninfo.co.kr/kangjin). Detailed technical information for the realtime monitoring system can be referred to Ro et al. (2004). Numerical Solution The tidal circulation of the Kangjin Bay was simulated based on ECOM-3D by forcing the tidal elevations at the open boundaries. The model domain is consisted of the 265*320 grid points with the horizontal grid size is 200 m and 11 vertical sigma levels. Under the CFL condition, the external time step is 10 sec and the internal time step is 300 sec. The drying-flooding procedure was taken into account for treating the area of intertidal flats in the Kangjin bay. Model Results Results of the model simulations will be presented to show the tidal current distributions at flood and ebb phases. The tidal currents in the Kangjin Bay are rather complicated due to its physical settings such as complicated geometry, bottom topography and three open boundaries. Because of the three open channels, the current distribution varies remarkably depending on the location inside the Bay. The tidal residual current patterns show the eddy structures developed near the mouth of the three channels which would have significant impact on the local water quality and ecosystem. Implications for the local ecosystem The circulation is driven by the tidal current most of the year except in the summer season when river runoffs from inflowing two rivers affect the salinity distribution and thereby density current is generated. One of the critical conditions in the Bay is dissolved oxygen contents which exhibit hypoxic conditions in the summer season (June, July and August) when water temperature is very high above 25 deg C and stratification is strong which inhibit the vertical supply of oxygen from the air. It is also considered that the critical bottom shear stress plays an important role in the hypoxic condition by resuspending the organic-rich bottom sediment into the water column which then consumes the oxygen. This study will illucidate the one of the mechnanism which will cause the hypoxic condition by the strong pycnocline formed by the river runoffs in the summer monsoon. The massive death rates of the large arc sheel in the summer might be attributed by the hypoxia formed by the river runoff.

  4. 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.

  5. Alternative Acetate Production Pathways in Chlamydomonas reinhardtii during Dark Anoxia and the Dominant Role of Chloroplasts in Fermentative Acetate Production[W

    Science.gov (United States)

    Catalanotti, Claudia; D’Adamo, Sarah; Wittkopp, Tyler M.; Ingram-Smith, Cheryl J.; Mackinder, Luke; Miller, Tarryn E.; Heuberger, Adam L.; Peers, Graham; Smith, Kerry S.; Jonikas, Martin C.; Grossman, Arthur R.; Posewitz, Matthew C.

    2014-01-01

    Chlamydomonas reinhardtii insertion mutants disrupted for genes encoding acetate kinases (EC 2.7.2.1) (ACK1 and ACK2) and a phosphate acetyltransferase (EC 2.3.1.8) (PAT2, but not PAT1) were isolated to characterize fermentative acetate production. ACK1 and PAT2 were localized to chloroplasts, while ACK2 and PAT1 were shown to be in mitochondria. Characterization of the mutants showed that PAT2 and ACK1 activity in chloroplasts plays a dominant role (relative to ACK2 and PAT1 in mitochondria) in producing acetate under dark, anoxic conditions and, surprisingly, also suggested that Chlamydomonas has other pathways that generate acetate in the absence of ACK activity. We identified a number of proteins associated with alternative pathways for acetate production that are encoded on the Chlamydomonas genome. Furthermore, we observed that only modest alterations in the accumulation of fermentative products occurred in the ack1, ack2, and ack1 ack2 mutants, which contrasts with the substantial metabolite alterations described in strains devoid of other key fermentation enzymes. PMID:25381350

  6. Influence of anoxia on the induction of mutations by phenylalanine radicals during γ-irradiation of plasmid DNA in aqueous solution

    International Nuclear Information System (INIS)

    When DNA is irradiated in aqueous solution, most of the damage is inflicted by water-derived radicals. This is called the indirect effect of ionizing radiation. However in whole cells not only the primary formed water radicals play a role, because some cellular compounds form secondary radicals which can also damage DNA. It is known that the amino acid phenylalanine is able to react with water radicals, resulting in the production of secondary phenylalanine radicals which can damage and inactivate DNA. In a previous study the influence of the presence of phenylalanine during γ-irradiation of DNA in aqueous solution under oxic conditions was studied. Under anoxic irradiation conditions different amounts and types of reactive water-derived radicals are formed compared to oxic conditions and also different phenylalanine radicals are formed. Therefore, this study examines the influence of the presence of phenylalanine under anoxic conditions on the γ-radiation-induced mutation spectrum. The results indicate that phenylalanine radicals are damaging to DNA, but less effective compared to primary water radicals. On the mutational level, in the presence of phenylalanine radicals under anoxic conditions, the amount of mutations on G:C base pairs was significantly decreased as compared to oxic conditions. Furthermore, the results of this study indicate that nucleotide excision repair is involved in repair of both inactivating and mutagenic damage induced by phenylalanine radicals under anoxic conditions

  7. Bottom RedOx Model (BROM, v.1.0): a coupled benthic-pelagic model for simulation of seasonal anoxia and its impact

    OpenAIRE

    Yakushev, E. V.; Protsenko, E. A.; Bruggeman, J.; Bellerby, R. G. J.; Pakhomova, S. V.; Couture, R.-M.; Yakubov, S.

    2016-01-01

    Interaction between seawater and benthic sediments plays an important role in global biogeochemical cycling. Benthic fluxes of chemical elements (C, N, P, O, Si, Fe, Mn, S) directly affect redox state and acidification (i.e. pH and carbonate saturation), which in turn determine the functioning of the benthic and pelagic ecosystems. The redox state of the near bottom layer can change and oscillate in many regions responding to the supply of organic matter, ph...

  8. 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.

  9. 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...

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. Sediment features, macrozoobenthic assemblages and trophic relationships (δ13C and δ15N analysis) following a dystrophic event with anoxia and sulphide development in the Santa Giusta lagoon (western Sardinia, Italy)

    International Nuclear Information System (INIS)

    Macrozoobenthic assemblages and stable carbon (δ13C) and nitrogen (δ15N) 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

  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. 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.

  17. Incidence and predictors of difficult mask ventilation and intubation

    Directory of Open Access Journals (Sweden)

    Prerana N Shah

    2012-01-01

    Conclusions: The predictive score may lead to a better anticipation of difficult airway management, potentially deceasing the morbidity and mortality resulting from hypoxia or anoxia with failed ventilation.

  18. 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

  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. 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

    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 of...

  1. Influence of chronic hypoxia and radiation quality on cell survival

    International Nuclear Information System (INIS)

    The purpose of this study was to investigate the influence of chronic hypoxia and anoxia on cell survival after low- and high-linear energy transfer (LET) radiation, Chinese hamster ovary K1 (CHO-K1) cells were kept for 24 h under chronic hypoxia (94.5% N2; 5% CO2; 0.5% O2) or chronic anoxia (95% N2; 5% CO2). Irradiation was performed using 250 kVp X-rays or carbon ions with a dose average LET of 100 keV/μm either directly under the chronic oxygenation states, or at different time points after reoxygenation. Moreover, the cell cycle distribution for cells irradiated under different chronic oxic states was measured over 24 h during reoxygenation. The measurements showed a fairly uniform cell cycle distribution under chronic hypoxia, similar to normoxic conditions. Chronic anoxia induced a block in G1 and a strong reduction of S-phase cells. A distribution similar to normoxic conditions was reached after 12 h of reoxygenation. CHO cells had a similar survival under both acute and chronic hypoxia. In contrast, survival after irradiation under chronic anoxia was slightly reduced compared to that under acute anoxia. We conclude that, in hamster cells, chronic anoxia is less effective than acute anoxia in inducing radioresistance for both X-rays and carbon ions, whereas in hypoxia, acute and chronic exposures have a similar impact on cell killing. (author)

  2. Symmetrical low-density areas on bilateral basal ganglia in childhood CT scans

    International Nuclear Information System (INIS)

    Symmetrical low-density areas of the bilateral basal ganglia are sometimes observed on CT scans in childhood. We report here eight cases who showed these lesions. Three of these cases had Leigh's encephalitis, 2 had perinatal anoxia, and 2 had viral encephalitis, while in the remaining two cases we could not distinctly determine the cause of the lesions. In Leigh's encephalitis, we speculate that metabolic abnormalities cause the necrosis of the basal ganglia. In perinatal anoxia and viral encephalitis, vascular infarction due to anoxia or brain edema may cause these lesions. (author)

  3. Assessing ecosystem effects of reservoir operations using food web-energy transfer and water quality models

    Science.gov (United States)

    Saito, L.; Johnson, B.M.; Bartholow, J.; Hanna, R.B.

    2001-01-01

    The diked and freshened Herring River estuary (Wellfleet, Massachusetts) experiences regular summer hypoxia and one- to three-week periods of main stream anoxia, often accompanied by fish kills. Stream hypoxia results from the temperature-dependent increase in oxygen demand of organic matter released by diked salt marsh deposits; periods of total anoxia are induced by heavy rains which increase the runoff of wetland organic matter. Historic reductions in tidal flushing have extended the low salinity region of the estuary normally characterized by high organic loads and minimal flushing. Recurrent main stream anoxia has depressed both migratory and resident aquatic fauna.

  4. 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 ...

  5. 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

  6. Comment on "Lack of enhanced preservation of organic matter in sediments under the oxygen minimum on the Oman Margin" by T.F. Pedersen, G.B. Shimmield, and N.B. Price

    Digital Repository Service at National Institute of Oceanography (India)

    Paropkari, A.L.; Mascarenhas, A.; PrakashBabu, C.

    rules out the possibility of settling flux of organic carbon being the principal control on the accumulation of organic matter in the marine sediments. Observations indicated the effectiveness of oxygen minimum zone stress and vital role of anoxia...

  7. Neuroprotective effects of some creatine derivative compounds

    Directory of Open Access Journals (Sweden)

    L. Perasso

    2010-01-01

    Full Text Available Some derivatives more lipophylic than creatine, thus theoretically being capable to better cross the blood-brain barrier, were studied for their neuroprotective effect in mouse hippocampal slices. In mouse hippocampal slices we found that EM2 I is ineffective, EM"" weakly increased the latency to population spike disapperance during anoxia. Creatine, Creatine-MG-complex (acetate and Phosphocreatine-Mg-complex (acetate increased more effectively the latency to population spike disappearance during anoxia. Moreover, Phosphocreatine-Mg-complex (acetate significantly reduced neuronal hyperexcitability during anoxia, an effect that no other compound (including creatine itself showed. Summing up, EM2 I is not useful for brain protection, while EM22 and cgelates of both creatine and phosphocreatine di replicate some of the knownn protective effects of creatine. In addition, Phosphocreatine-Mg-complex (acetate also reduced neuronal hyperexcitability during anoxia.

  8. 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.

  9. Middle interhemispheric fusion

    International Nuclear Information System (INIS)

    We report a case of a 19-year-old woman with seizures and mental deficiency attributed to perinatal anoxia. Brain MR showed a congenital malformation, a rare form of semilobar holoprosencephaly termed middle interhemispheric fusion. (orig.)

  10. 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 ...

  11. Denitrifying bacterial community composition changes associated with stages of denitrification in oxygen minimum zones

    Digital Repository Service at National Institute of Oceanography (India)

    Jayakumar, D.A.; O'Mullan, G.D.; Naqvi, S.W.A.; Ward, B.B.

    , responsible for key denitrification transformation steps is described. It is shown that denitrifying assemblages vary in space and time and exhibit striking changes in diversity associated with the progression of denitrification from initial anoxia through...

  12. The effects of hypolimnetic oxygenation on the chemical, physical, and biological properties of a shallow drinking water reservoir

    OpenAIRE

    Browne, Richard Gregory

    2013-01-01

    Hypolimnetic anoxia can result in higher internal phosphorus (P) loads from the sediments to the water column, thereby increasing nutrient availability, making preventing anoxia a major goal for lake managers to improve water quality. Side-stream saturation (SSS), a type of hypolimnetic oxygenation system, has been developed to maintain oxygenated conditions at the sediments by withdrawing oxygen-depleted water from the hypolimnion to an on-site facility and injecting it with oxygen under hi...

  13. Par Pond refill water quality sampling

    International Nuclear Information System (INIS)

    This study was designed to document anoxia and its cause in the event that the anoxia caused a fish kill. However, no fish kill was observed during this study, and dissolved oxygen and nutrient concentrations generally remained within the range expected for southeastern reservoirs. Par Pond water quality monitoring will continue during the second summer after refill as the aquatic macrophytes become reestablished and nutrients in the sediments are released to the water column

  14. 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

    2016-03-01

    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. PMID:26794834

  15. 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

  16. 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.

  17. ATP Production by Respiration and Fermentation, and Energy Charge during Aerobiosis and Anaerobiosis in Twelve Fatty and Starchy Germinating Seeds.

    Science.gov (United States)

    Raymond, P; Al-Ani, A; Pradet, A

    1985-11-01

    The respiration and fermentation rates were compared in germinating seeds of 12 different cultivated species from five families. In air, fermentation contributes significantly to the energy metabolism only in some species (pea, maize), but is generally negligible when compared to respiration. The fermentation rate under anoxia was related either to the metabolic activity under air or to the adenine nucleotide content of the seeds: it was generally higher in seeds which contain starchy reserves (rice, maize, sorghum, pea), than in seeds which do not contain starch (lettuce, sunflower, radish, turnip, cabbage, flax); however, it was similar in wheat, sorghum (starchy seeds), and soya (nonstarchy seeds). The value of the energy charge of all the seeds was lower under anoxia than in air: after 24 hours under anoxia, it was higher than 0.5 in the starchy seeds and in soya and it was around 0.25 in the other fatty seeds. PMID:16664509

  18. 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......, contributes to the increased Rsys of anoxic red-eared slider turtles (Trachemys scripta). Vascular infusion of the H2S donor NaHS in anesthetized turtles at 21°C and fully recovered normoxic turtles at 5°C and 21°C revealed H2S to be a potent vasoconstrictor of the systemic circulation. Likewise, wire...... myography of isolated turtle mesenteric and pulmonary arteries demonstrated H2S to mediate an anoxia-induced constriction. Intriguingly, however, NaHS did not exert vasoconstrictory effects during anoxia (6 h at 21°C; 14 days at 5°C) when plasma H2S concentration, estimated from the colorimetric measurement...

  19. Crecimiento foliar y radical en plantas de fique (furcraea castilla y f. macrophylla) bajo estrés por encharcamiento

    OpenAIRE

    Casierra-Posada, Fánor; Gómez G, Nancy E.

    2009-01-01

    En regiones tropicales y subtropicales se producen pérdidas en las plantas cultivadas como consecuencia de lluvias estacionales prolongadas. El exceso de agua produce condiciones de anoxia en el suelo en pocas horas. Las raíces sufren hipoxia o anoxia, lo cual tiene como resultado una crisis energética que afecta el crecimiento de la planta. El presente estudio se orientó hacia la determinación de crecimiento foliar y radical en dos especies de fique (Furcraea castilla y F. macrophylla) culti...

  20. Comparative aspects of hypoxia tolerance of the ectothermic vertebrate heart

    DEFF Research Database (Denmark)

    Gesser, Hans; Overgaard, Johannes

    2009-01-01

    This chapter reviews cardiac contractile performance and its regulation during hypoxia/anoxia with regard to cellular metabolism and energy state, in particular hypoxia-tolerant ectothermic vertebrates. Overall the contractile performance of the hypoxic isolated heart muscle varies in a way 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...

  1. AcEST: DK953224 [AcEST

    Lifescience Database Archive (English)

    Full Text Available TST39A01NGRL0017_D09 513 Adiantum capillus-veneris mRNA. clone: TST39A01NGRL0017_D09. 5' end seq ... t_id Q9VGX3 Definition sp|Q9VGX3|FAU_DROME Protein anoxia ... up-regulated OS=Drosophila melanogaster Align leng ... ignments: (bits) Value sp|Q9VGX3|FAU_DROME Protein anoxia ... up-regulated OS=Drosophila me... 38 0.032 sp|Q2H92 ...

  2. AcEST: BP915944 [AcEST

    Lifescience Database Archive (English)

    Full Text Available YMU001_000079_G12 455 Adiantum capillus-veneris mRNA. clone: YMU001_000079_G12. BP915944 CL3650C ... apiens GN=... 38 0.024 sp|Q9VGX3|FAU_DROME Protein anoxia ... up-regulated OS=Drosophila me... 36 0.069 sp|Q8WR6 ... AALEEAQR---AQGI 1620 >sp|Q9VGX3|FAU_DROME Protein anoxia ... up-regulated OS=Drosophila melanogaster GN=fau PE= ...

  3. AcEST: DK963202 [AcEST

    Lifescience Database Archive (English)

    Full Text Available TST39A01NGRL0015_O10 597 Adiantum capillus-veneris mRNA. clone: TST39A01NGRL0015_O10. 5' end seq ... 3/CP_0124/CP... 32 2.4 sp|Q9VGX3|FAU_DROME Protein anoxia ... up-regulated OS=Drosophila me... 32 2.4 sp|Q5UQW2| ... EILDTVKEELWEESQEN 184 >sp|Q9VGX3|FAU_DROME Protein anoxia ... up-regulated OS=Drosophila melanogaster GN=fau PE= ...

  4. AcEST: DK957987 [AcEST

    Lifescience Database Archive (English)

    Full Text Available TST39A01NGRL0029_N04 637 Adiantum capillus-veneris mRNA. clone: TST39A01NGRL0029_N04. 5' end seq ... t_id Q9VGX3 Definition sp|Q9VGX3|FAU_DROME Protein anoxia ... up-regulated OS=Drosophila melanogaster Align leng ... ignments: (bits) Value sp|Q9VGX3|FAU_DROME Protein anoxia ... up-regulated OS=Drosophila me... 38 0.050 sp|P3596 ...

  5. AcEST: DK954419 [AcEST

    Lifescience Database Archive (English)

    Full Text Available TST39A01NGRL0020_G06 662 Adiantum capillus-veneris mRNA. clone: TST39A01NGRL0020_G06. 5' end seq ... t_id Q9VGX3 Definition sp|Q9VGX3|FAU_DROME Protein anoxia ... up-regulated OS=Drosophila melanogaster Align leng ... ignments: (bits) Value sp|Q9VGX3|FAU_DROME Protein anoxia ... up-regulated OS=Drosophila me... 38 0.055 sp|A1VG8 ...

  6. AcEST: DK950227 [AcEST

    Lifescience Database Archive (English)

    Full Text Available TST38A01NGRL0008_B15 533 Adiantum capillus-veneris mRNA. clone: TST38A01NGRL0008_B15. 5' end seq ... LD1 PE=1 SV=2 44 6e-04 sp|Q9VGX3|FAU_DROME Protein anoxia ... up-regulated OS=Drosophila me... 43 8e-04 sp|Q499N ... KESLPEKLQPTSKKDQ 446 >sp|Q9VGX3|FAU_DROME Protein anoxia ... up-regulated OS=Drosophila melanogaster GN=fau PE= ...

  7. AcEST: DK958527 [AcEST

    Lifescience Database Archive (English)

    Full Text Available TST39A01NGRL0002_D22 674 Adiantum capillus-veneris mRNA. clone: TST39A01NGRL0002_D22. 5' end seq ... t_id Q9VGX3 Definition sp|Q9VGX3|FAU_DROME Protein anoxia ... up-regulated OS=Drosophila melanogaster Align leng ... ignments: (bits) Value sp|Q9VGX3|FAU_DROME Protein anoxia ... up-regulated OS=Drosophila me... 38 0.056 sp|A1VG8 ...

  8. AcEST: BP918766 [AcEST

    Lifescience Database Archive (English)

    Full Text Available YMU001_000117_C04 505 Adiantum capillus-veneris mRNA. clone: YMU001_000117_C04. BP918766 CL3650C ... P250 OS=Mu... 37 0.053 sp|Q9VGX3|FAU_DROME Protein anoxia ... up-regulated OS=Drosophila me... 36 0.090 sp|Q8WR6 ... 4 + Sbjct: 874 L 874 >sp|Q9VGX3|FAU_DROME Protein anoxia ... up-regulated OS=Drosophila melanogaster GN=fau PE= ...

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

    DEFF Research Database (Denmark)

    Pitkänen, Heikki; Bendtsen, Jørgen; Hansen, Jørgen L. S.; Lehtoranta, Jouni; Lännergren, Christer; Ollikainen, Markku; Priha, Maarit; Reinikainen, Marko; Saarijärvi, Erkki; Zandersen, Marianne

    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...... possibilities 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....

  10. Use of gamma radiation with cobalt 60 source in the disinfection of documentary collections; Uso da radiacao gamma com fonte de cobalto 60 na desinfestacao de acervos documentais

    Energy Technology Data Exchange (ETDEWEB)

    Franca, Conceicao Linda de; Barboza, Kleumanery de Melo

    2011-07-01

    This article aims to conduct a comparative study between disinfection methods (anoxia and freezing) of documentary collections and the application of gamma radiation, with cobalt 60 source, by analyzing the pros and cons of each methods. This study is part of research developed by the authors that study the effect of radiation on materials

  11. 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...

  12. Coastal versus open-ocean denitrification in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A; Naik, H.; Pratihary, A; DeSouza, W.; Narvekar, P.V.; Jayakumar, D.A; Devol, A; Yoshinari, T.; Saino, T.

    to complete anoxia). Unlike the open-ocean system, the coastal system seems to have undergone a change (i.e., it has intensified) over the past few decades presumably due to gone enhanced nutrient loading from land. The two systems also differ from each other...

  13. The effect of soil re-oxidation on wheat (Triticum aestivum L. defense system

    Directory of Open Access Journals (Sweden)

    Żuchowski J.

    1999-09-01

    Full Text Available Responses of superoxide dismutase (SOD activity, malonic di-aldehyde (MDA level and pigments (chlorophyll, carotenoids content were evaluated in roots and leaf tissues of wheat plants (Roma; CZR 1334 which were grown in soil (Eutric Cambisol pre-exposed to anoxia by flooding, during return of oxic conditions in the root zone.

  14. 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

  15. 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

  16. 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…

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

    Science.gov (United States)

    In soil, hypoxia and anoxia conditions generated by waterlogging induce changes in genetic morphological, physiological processes, and as well as altering the growth and development of plant The mass propagation of cacao (Theobroma cacao) cuttings-to produce plantlets (clones) is affected by waterlo...

  18. A new humane method of stunning broilers using low atmospheric pressure

    Science.gov (United States)

    This research project evaluated an alternative method of controlled atmosphere stunning of commercial broilers to induce anoxia utilizing a vacuum pump to reduce the oxygen tension, low atmospheric pressure stun (LAPS). A custom built 2 cage-module system (holding a total of 600 broilers each) with...

  19. SPATIAL AND TEMPORAL RELATIONSHIPS BETWEEN TOTAL NITORGEN AND PLANKTONIC CHLOROPHYLL IN LONG ISLAND SOUND

    Science.gov (United States)

    Excess loading of nitrogen has been identified as a cause of excess primary production in many marine systems, including Long Island Sound. In particular, western Long Island Sound experiences significant seasonal hypoxia and anoxia attributed to excess nitrogen loading. We explo...

  20. Ecophysiological characterization of carnivorous plant roots: oxygen fluxes, respiration, and water exudation

    Czech Academy of Sciences Publication Activity Database

    Adamec, Lubomír

    2005-01-01

    Roč. 49, č. 2 (2005), s. 247-255. ISSN 0006-3134 R&D Projects: GA AV ČR(CZ) IAA6005909 Institutional research plan: CEZ:AV0Z6005908 Keywords : terrestrial carnivorous plants * soil anoxia * Genlisea traps Subject RIV: EF - Botanics Impact factor: 0.792, year: 2005

  1. Spatially and Temporally Detailed Modeling of Water Quality in Narragansett Bay

    Science.gov (United States)

    Nutrient loading to Narragansett Bay has led to eutrophication, resulting in hypoxia and anoxia, finfish and shellfish kills, loss of seagrass, and reductions in the recreational and economic value of the Bay. We are developing a model that simulates the effects of external nutri...

  2. Significance of riverine hypoxia for fish: The case of the Big Sunflower River, Mississippi

    Science.gov (United States)

    Degraded streams draining low-relief, intensively cultivated watersheds may experience periods of hypoxia or anoxia. A three-year study of water quality, fish, and physical habitat in the Big Sunflower River in northwestern Mississippi coupled with continuously logged water quality and hydrology dat...

  3. HYPOXIA IN CHESAPEAKE BAY, 1950-2001: LONG-TERM CHANGE IN RELATION TO NUTRIENT LOADING AND RIVER FLOW

    Science.gov (United States)

    A 52-yr record of dissolved oxygen in Chesapeake Bay (1950 to 2001) and a record of nitrate (NO3-) loading by the Susquehanna River spanning a longer period (1903, 1945 to 2001) were assembled to describe the long-term pattern of hypoxia and anoxia in Chesapeake Bay an...

  4. POST AUDIT OF A LAKE ERIE EUTROPICATION MODEL

    Science.gov (United States)

    A post audit of a eutrophication-dissolved oxygen model of Lake Erie is presented. The model had been calibrated using data from 1970 and 1975. Projections were then made for use in establishing the model target loadings for phosphorus that would essentially eliminate the anoxia ...

  5. Spatially and Temporally Detailed Modeling of Water Quality in Narragansett Bay (AGU)

    Science.gov (United States)

    Nutrient loading to Narragansett Bay has led to eutrophication, resulting in hypoxia and anoxia, finfish and shellfish kills, loss of seagrass, and reductions in the recreational and economic value of the Bay. We are developing a model that simulates the effects of external nutri...

  6. miR-210 as a marker of chronic hypoxia, but not a therapeutic target in prostate cancer

    International Nuclear Information System (INIS)

    Introduction: Radiotherapy in combination with medical castration is the standard treatment for high-risk prostate cancer. Some relapses may be explained by the presence of radioresistant clones arising from hypoxic microenvironment. Since microRNAs (miR) are increased upon hypoxia, the aim of this study was to see whether miR-210 is a potential marker for hypoxia and/or a therapeutic target in prostate cancer. Methods: Human LNCaP, DU145 or PC3 prostate cancer cells were exposed to normoxia or hypoxia for several hours. Gene expression of miR-210, miR-373 and several hypoxia markers were analyzed by Taqman and SYBR green qRT-PCR, respectively. Clonogenic survival after LNA miR-210 inhibitor (78 nM) and concomitant irradiation were evaluated. Results: During anoxia, CAIX and VEGF expressions were dramatically increased. miR-210 expression increased during anoxia exposure, while basal miR-373 expression was low and remained stable upon anoxia. LNA miR-210 inhibitor decreased anoxic miR-210 expression by 90% and clonogenic survival under anoxia (p = 0.01). However, no enhanced effect was observed when miR-210 inhibitor was combined with irradiation. Conclusion: miR-210 could be an interesting marker of chronic hypoxia irrespective of the androgen dependency and should, therefore, be tested as a prognostic marker in high risk prostate cancer patients.

  7. 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)

  8. Sieve plugs in fenestrae of glomerular capillaries--site of the filtration barrier?

    DEFF Research Database (Denmark)

    Rostgaard, Jørgen; Qvortrup, Klaus

    2002-01-01

    artifactual tissue changes, due to subnormal blood pressure or anoxia, have taken place in the endothelium before the tissue and tracers have been sufficiently fixed and immobilized by the fixative. To test this supposition, a new method of fixation, which includes a technique to maintain a physiological...

  9. Long term picoplankton dynamics in a warm-monomictic, tropical high altitude lake

    Czech Academy of Sciences Publication Activity Database

    Macek, Miroslav; Alcocer, J.; Lugo Vázquez, A.; Martínez-Pérez, M.E.; Peralta Soriano, L.; Vilaclara Fatjó, G.

    2009-01-01

    Roč. 68, č. 2 (2009), s. 183-192. ISSN 1129-5767 R&D Projects: GA MŠk(CZ) ME 296 Institutional research plan: CEZ:AV0Z60170517 Keywords : athalassohaline lake * picoplankton * anoxia * bacteria * chlorophyll-a Subject RIV: DA - Hydrology ; Limnology Impact factor: 0.932, year: 2009

  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

    ocean anoxia driven by anthropogenic release of greenhouse gases. Potential consequences of this anthropogenic forcing can be approximated by studying analog environmental perturbations in the past such as the T-OAE. Here we present to our knowledge the first organic carbon isotope record derived from...

  11. Ischemia-Reperfusion Damage

    OpenAIRE

    Yapca, Omer E.; Borekci, Bunyamin; Suleyman, Halis

    2013-01-01

    Ischemia-reperfusion damage is a complex pathological process that begins with tissue anoxia and continues with the production of free oxygen radicals, expanding with the inflammatory response. The literature suggests the importance of antioxidant and anti-inflammatory treatment to treat ischemia-reperfusion-related tissue damage.

  12. 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…

  13. 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.

  14. 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

  15. Nicotine-induced exocytotic norepinephrine release in guinea-pig heart, human atrium and bovine adrenal chromaffin cells: modulation by single components of ischaemia.

    Science.gov (United States)

    Krüger, C; Haunstetter, A; Gerber, S; Serf, C; Kaufmann, A; Kübler, W; Haass, M

    1995-08-01

    The influence of single components of myocardial ischaemia, such as anoxia, substrate withdrawal, hyperkalemia and extracellular acidosis, on nicotine-induced norepinephrine (NE) release was investigated in the isolated perfused guinea-pig heart, in incubated human atrial tissue and in cultured bovine adrenal chromaffin cells (BCC). In normoxia, nicotine (1-1000 mumol/l) evoked a concentration-dependent release of NE (determined by high pressure liquid chromatography and electrochemical detection) from guinea-pig heart and human atrium. In contrast to selective anoxia (Po2 < 5 mmHg) or glucose withdrawal, respectively, anoxia in combination with glucose withdrawal (5-40 min) markedly potentiated nicotine-induced NE release both in guinea-pig heart and human atrium. The sensitization of cardiac sympathetic nerve endings to nicotine was characterized by a lower threshold concentration and an approximate two-fold increase of maximum NE release, peaking after 10 min of anoxia and glucose withdrawal. Cyanide intoxication (1 mmol/l) combined with glucose withdrawal resulted in a similar increase of nicotine-induced sympathetic transmitter release both in guinea-pig heart and human atrium. In contrast, the nicotine-induced (10 mumol/l) NE overflow was only slightly potentiated by 10 min of global ischaemia in guinea-pig heart. Both hyperkalemia ([K+] 16 mmol/l) and acidosis (pH 6.8-6.0) distinctly attenuated the stimulatory effect of nicotine in guinea-pig heart and human atrium under normoxic conditions. Consistent with an exocytotic release mechanism, NE release was dependent on the presence of extracellular calcium under all conditions tested. Furthermore, NE overflow from guinea-pig heart was accompanied by a release of the exocytosis marker neuropeptide Y (NPY; determined by radioimmunoassay). In BCC, nicotine (1-10 mumol/l) evoked a release of NE and NPY and a transient rise of [Ca2+]i (determined with fura-2) during normoxia which were both dependent on the

  16. 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

  17. 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.

  18. 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......)(+), Fe(2+) and CO(2) in sediments. O(2) in leaf lacunae fluctuated from above air saturation in the light to anoxia late in the dark in natural sediments, but organic enrichment prolonged anoxia because of higher O(2) consumption and restricted uptake from the water. Leaf N and P dropped below minimum...

  19. 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

  20. 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.

  1. 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

  2. The clinical significance of determination of adrenal medulla in patients with chronic cor pulmonale and analysis of its relevant factors

    International Nuclear Information System (INIS)

    In order to find the function of adrenal medulla in the development of chronic cor pulmonale and the effect of smoking, anoxia and lung's work on adrenal medulla, the authors determined adrenal medulla in 63 patients with acute cor pulmonale (Group A) and 60 controls (Group B). The authors tried to find out the effect of the patients' age, course of disease, history of smoking, malfunction of lung on adrenal medulla by multiple regressive analysis. Adrenal medulla is significantly higher in Group A than that of in Group B (P 2 both contribute to the conclusion that smoking is an independent factor to affect the adrenal medulla. The study shows that the adrenal medulla in patients with cor pulmonale is higher than that of normal people, and that the level of adrenal medulla is dependent on the degree of seriousness of the disease, obstructive ventilatory disturbance and anoxia

  3. Evidence for a weakening ‘dead zone’ in Tokyo Bay over the past 30 years

    International Nuclear Information System (INIS)

    Weakened hypoxia in the past 30 years at a dredged area in Tokyo Bay was proven by the existence of amorphous hematite (α-Fe2O3) in sediments. The chemical states of iron in sediments can become a proxy for the scale of anoxia at the time of sedimentation. In 2009, we collected core sediments from a dredged area off Makuhari in Tokyo Bay that is very strongly anoxic in the summer. Every layer of the sediments was analysed by 57Fe Mössbauer spectroscopy and excess 210Pb dating, and amorphous hematite was identified in the sediments from the 1976–1979, 1986–1989 and 2006–2009 layers. Using an estimate based on the Eh-pH diagram optimized for the sedimental environment, the existence of hematite in the dredged area proves that the scale of hypoxia/anoxia is decreasing, and these results agree well with the observed dissolved oxygen level of the seawater mass.

  4. The role of glutathione in the radiosensitive effect induced by treating HeLa cells with sanazole

    International Nuclear Information System (INIS)

    Objective: To investigate radiosensitive effect of sanazole on HeLa cells and its relationship with glutathione (GSH). Methods: The anoxia model was made by inflow of nitrogen gas. The survival rate of HeLa cells was observed with method of colony formation after treatment with sanazole and 60Co γ irradiation. Radiosensitive effect was evaluated through measurement of sensitizing enhancement ratio (SER) resulted from single-target multi-hit model. The GSH content in these HeLa cells was determined by the tetra-oxypyrimidine UV-spectrophotometer method to explore the mechanism of radiosensitive effect. Results: SER was more than 1.4. The concentration of GSH decreased significantly with increasing concentration of sensitizer and dose of radiation, especially under anoxia condition. Conclusions: Sanazole has significant radiosensitive effect and decrease in GSH content resulted from combination with 60Co γ irradiation may be one of its radiosensitive mechanisms

  5. 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.

  6. 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.

  7. 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...

  8. Microbial iron reduction and methane oxidation in subsurface sediments of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, C.E.G.; Judith, M.; Gonsalves, M.J.B.D.; Nazareth, D.R.; Nagarchi, L.; Kamaleson, A.S.

    lithologic units (Units I to IV) based on visual description, biogenic and terrigenous composition, trends in logging and physical properties data (Collett et al., 2007). Sediment samples up to a depth of 63 mbsf from litostratigraphic unit I (LSI) were.... Environ. Microbiol. 4, 115–124. Bruchert, V., Currie, B., Peard, K. R., Lass, U., Endler, R., Dubecke, A., Julies, E., Leipe, T., Zitzmann, S. 2006. Biogeochemical and physical control on shelf anoxia and water column hydrogen sulphide in the Benguela...

  9. 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

  10. Distribution spatio-temporelle des cyanobactéries dans le lac de Parentis-Biscarrosse

    OpenAIRE

    Gogin, S.

    2013-01-01

    A monthly monitoring carried out since May 2010 by Irstea Bordeaux allow to assess the physico-chemical status of the lake Parentis-Biscarrosse and give an overall description of the dynamic of phytoplankton communities. The results show that since 2008 the trophic status seems to deteriorate including very high levels of phosphorus. The water body also differs from other regional lakes with anoxia in summer sometimes measured from six meter depht and with frequent blooms of cyanobacteria whi...

  11. Bioreduction of iodate in sediment microcosms

    OpenAIRE

    Fabiola Guido-Garcia, Gareth T. W. Law, Jonathan R. Lloyd, Paul Lythgoe; and Katherine Morris

    2015-01-01

    Iodine-129 is a high-yield fission product formed in nuclear reactors and is a risk-driving radionuclide in both contaminated land and radioactive waste disposal due to its high mobility and long half-life. Here, the bioreduction behaviour of iodate was investigated by tracking iodine speciation and concentration in solution during the development of progressive anoxia in sediment microcosm experiments incubated at neutral pH. Experiments with acetate added as an electron donor sh...

  12. Metabolic responses of Glossina pallidipes (Diptera: Glossinidae) puparia exposed to oxygen and temperature variation: implications for population dynamics and subterranean life.

    Science.gov (United States)

    Basson, C Helene; Terblanche, John S

    2010-12-01

    Understanding the factors affecting insect gas exchange in subterranean environments is critical to understanding energy budgets and predicting mortality under field conditions. Here, we examine the metabolic rate (MR) responses of tsetse puparia, which remain underground for ca. 1 month in this life-stage, to varying oxygen and temperature. First, the effects of temperature and oxygen on puparial MR were investigated by ramping temperature from 15 to 35°C under 10, 21 or 40% O(2). Overall, temperature was the dominant effect on puparial MR although O(2) had small but significant impacts. Second, critical O(2) concentration (P(CRIT)) for MR of puparia was examined across a range of oxygen concentrations (0-40%). P(CRIT) was 6% O(2) which is similar to P(CRIT) in other basal arthropods but relatively high for inactive or subterranean insects. Third, we asked if puparia exposed to anoxia might experience oxygen debt, potentially indicative of anaerobic metabolism or cellular repair. Metabolic responses to anoxia were limited or insignificant, but MR was marginally elevated (∼ 15%) in anoxia-exposed (4h) puparia by 12h post-anoxia. Finally, we examined the ability of puparia to withstand water submersion, thus simulating flooding conditions frequently experienced in tropical soil habitats. Puparia were unable to survive submersion for >24h suggesting limited flooding tolerance. These novel results suggest that soil conditions experienced by puparia should not be limiting for MR, except possibly under high temperature-low O(2) conditions. Due to a large safety margin between P(CRIT) and soil oxygen levels and limited effects of oxygen on metabolism during temperature ramping experiments, we suggest that Glossina pallidipes puparia are not particularly susceptible to oxygen availability in their natural environment. However, soil flooding associated with tropical rainfall likely imposes strong selection on tsetse populations and may have had important effects for

  13. 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 ...

  14. Modeling hydrography and marine sedimentation in the Cariaco Basin since the Last Glacial Maximum

    OpenAIRE

    Lane-Serff, G.F.; Pearce, R.B.

    2009-01-01

    The Cariaco Basin has shallow connections with the Caribbean Sea, and these are further reduced at times of lower sea level, such as at the Last Glacial Maximum (LGM). A numerical model was developed to describe the oceanography and biogenic sedimentation in the Cariaco Basin and nearby Caribbean. The model is run with different sea levels in order to simulate the changing oceanography and the development of deep water anoxia in the Cariaco Basin since the LGM. In the main sequence of numeric...

  15. In vitro thrombolytic potential of root extracts of four medicinal plants available in Bangladesh

    OpenAIRE

    Fahad Hussain; Md. Ariful Islam; Latifa Bulbul; Md Mizanur Rahman Moghal; Mohammad Salim Hossain

    2014-01-01

    Context: Thrombus formation inside the blood vessels obstructs blood flow through the circulatory system leading hypertension, stroke to the heart, anoxia, and so on. Thrombolytic drugs are widely used for the management of cerebral venous sinus thrombosis patients, but they have certain limitations. Medicinal plants and their components possessing antithrombotic activity have been reported before. However, plants that could be used for thrombolysis has not been reported so far. Aims: Thi...

  16. 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...

  17. Ischemic hepatitis after percutaneous nephrolitotomy: A case report

    OpenAIRE

    Mustafa Zafer Temiz; Emrah Yuruk; Kutlu Teberik; Burcu Kadriye Akbas; Mustafa Devrim Piroglu; Hande Selvi Oztorun; Engin Kandirali

    2014-01-01

    INTRODUCTION: Ischemic hepatitis (IH) is the necrosis of the centrilobular hepatocytes of liver and is secondary to liver hypoperfusion in most of the cases. The diagnosis is usually based on biochemical findings due to the absence of symptoms and signs. Although the disease course is often mild, and sometimes is even not diagnosed, the outcome is poor if the etiology of hypotension and liver anoxia is not promptly corrected. PRESENTATION OF CASE: A 64-year-old patient who underwent percut...

  18. Idiopathic Hypoparathyroidism associated Fahrs Disease: Two Case Reports and Review of the Literature

    OpenAIRE

    Mehtap Evran; Gamze Akkus; Murat Sert; Tamer Tetiker

    2015-01-01

    Bilateral Striopallidodentat Calcinosis also called Fahrs disease (FH); basal ganglia, thalamus, and cerebellar dentate nucleus is a disease characterized by symmetric calcifications in the cerebral white matter. Calcifications are often drawn attention in brain imaging for other reasons. The disease can progress with clinically variable neurological or neuro-psychiatric symptoms. Fahrs disease are believed to be associated with anoxia, radiation, systemic diseases, toxins calcium metabolism ...

  19. Idiopathic Hypoparathyroidism associated Fahr's Disease: Two Case Reports and Review of the Literature

    OpenAIRE

    Evran, Mehtap; Akkuş, Gamze; Sert, Murat; Tetiker, Tamer

    2015-01-01

    Bilateral Striopallidodentat Calcinosis also called Fahr's disease (FH); basal ganglia, thalamus, and cerebellar dentate nucleus is a disease characterized by symmetric calcifications in the cerebral white matter. Calcifications are often drawn attention in brain imaging for other reasons. The disease can progress with clinically variable neurological or neuro-psychiatric symptoms. Fahr's disease are believed to be associated with anoxia, radiation, systemic diseases, toxins calcium metabolis...

  20. Towards a translational model of panic attacks

    OpenAIRE

    Luiz Carlos Schenberg

    2010-01-01

    About 20 years ago, Deakin and Graeff proposed that whereas generalized anxiety disorder is produced by the overactivity of 5-HT excitatory projections from dorsal raphe nucleus to the areas of prefrontal cortex and amygdala which process distal threat, panic attacks are a dysfunction of 5-HT inhibitory projections from dorsal raphe nucleus to the dorsal periaqueductal gray matter, thereby releasing the responses to proximal threat, innate fear or anoxia. Besides, they suggested that the decr...

  1. Historical records of coastal eutrophication-induced hypoxia

    Digital Repository Service at National Institute of Oceanography (India)

    Gooday, A.J.; Jorissen, F.; Levin, L.A.; Middelburg, J.J.; Naqvi, S.W.A.; Rabalais, N.N.; Scranton, M.; Zhang, J.

    (isorenieratine,B-chl,farnesol) Indicatephoticzoneanoxia Derivedfromstrictlyanaerobicorganismsthatrequirelightandsulphide.B-chlin sedimentsishypoxia-specificproxy. www.biogeosciences.net/6/1707/2009/ Biogeosciences, 6, 1707–1745, 2009 1712 A. J. Gooday et al... with the virtual disappearance of other ostracod species (Fig. 7b). Cronin and Vann (2003) consider the increased in- tensity of seasonal anoxia to be the most likely explanation for this recent faunal shift. Fig. 6. Trends in faunal and environmental parameters...

  2. 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...

  3. 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...

  4. Ecological Analysis of Nutrient, Plankton and Benthic Communities in Farmington Bay and the Great Salt Lake, Utah (2004)

    OpenAIRE

    Marcarelli, Amy; Wurtsbaugh, Wayne A.

    2005-01-01

    In Fall 2004, the Aquatic Ecology Practicum class at Utah State University finished a third year of research on limnological and ecological characteristics of Farmington Bay and Gilbert Bays of the Great Salt Lake. Our previous research has produced interesting findings in Farmington Bay, including hypereutrophy (Marcarelli et a!. 2001), high phosphorus loading into the Bay, overnight water column anoxia linked to high winds (Wurtsbaugh et a!. 2002), potential predator control of brine shrimp...

  5. 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...

  6. Hypercapnic cerebral edema presenting in a woman with asthma: a case report

    OpenAIRE

    McGee William T; Joyce Ryan R

    2011-01-01

    Abstract Introduction Common causes of non-traumatic acute cerebral edema include malignant hypertension, hyponatremia, anoxia, and cerebral vascular accident. The computed tomographic images and data obtained during care of the patient described in this case report provide evidence that hypercarbia can cause increased intracranial pressure and coma without permanent brain injury. Partial pressure of carbon dioxide evaluation for coma is essential to provide faster diagnosis and therapeutic c...

  7. Ecology in Small Aquatic Ecosystems

    DEFF Research Database (Denmark)

    Andersen, Mikkel René

    % supersaturated in oxygen while the bottom waters becomes anoxic. Dense charophyte stands influenced the hydrodynamics and created favorable conditions for the apical parts in the surface waters, while the basal parts withstood anoxia for up to 12 hours in the bottom waters. Nocturnal convective mixing oxygenated......) both in the small lakes and in the small ephemeral streams on the Great Alvar. Downstream respiration was decoupled from GPP as respiration rates were much higher due to agricultural impact....

  8. 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, ...

  9. Metagenomes of tropical soil-derived anaerobic switchgrass-adapted consortia with and without iron

    OpenAIRE

    DeAngelis, Kristen M.; D’Haeseleer, Patrik; Chivian, Dylan; Simmons, Blake; Arkin, Adam P.; Mavromatis, Konstantinos; Malfatti, Stephanie; Tringe, Susannah; Hazen, Terry C.

    2013-01-01

    Tropical forest soils decompose litter rapidly with frequent episodes of anoxia, making it likely that bacteria using alternate terminal electron acceptors (TEAs) such as iron play a large role in supporting decomposition under these conditions. The prevalence of many types of metabolism in litter deconstruction makes these soils useful templates for improving biofuel production. To investigate how iron availability affects decomposition, we cultivated feedstock-adapted consortia (FACs) deriv...

  10. 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

  11. A critical evaluation of depositional parameters controlling the variability of organic carbon in Arabian Sea sediments

    Digital Repository Service at National Institute of Oceanography (India)

    Paropkari, A.L; PrakashBabu, C.; Mascarenhas, A.

    Institute of Oceanography, Dona Paula, Goa 403 004, India (Received October 4, 1991; revision accepted January 9, 1992) ABSTRACT Paropkari, A.L., Prakash Babu, C. and Mascarenhas, A., 1992. A critical evaluation of depositional parameters controlling..., the existing notion is that the black shales formed under conditions of water column anoxia (Demaison and Moore, 1980). In contrast, Calvert (1987), Pedersen and Calvert (1990) and Calvert et al. (1991) suggested that high primary production and not water...

  12. 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)

    Löscher, C. R.; Fischer, M. A.; Neulinger, S. C.; Fiedler, B.; Philippi, M.; Schütte, F.; Singh, A.; Hauss, H.; Karstensen, J.; Körtzinger, A.; Künzel, S.; Schmitz, R. A.

    2015-12-01

    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 (anoxia have the potential to alter microbial community structure with critical impacts on primary productivity and biogeochemical processes of oceanic water bodies.

  13. 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...

  14. 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...

  15. The Mesoscopic Modeling of Burst Suppression during Anesthesia

    OpenAIRE

    Liley, David T. J.; Walsh, Matthew

    2013-01-01

    The burst-suppression pattern is well recognized as a distinct feature of the mammalian electroencephalogram (EEG) waveform. Consisting of alternating periods of high amplitude oscillatory and isoelectric activity, it can be induced in health by deep anesthesia as well as being evoked by a range of pathophysiological processes that include coma and anoxia. While the electroencephalographic phenomenon and clinical implications of burst suppression have been studied extensively, the physiologic...

  16. Therapeutic Applications of Carbon Monoxide

    OpenAIRE

    Melissa Knauert; Sandeep Vangala; Maria Haslip; Patty Lee

    2013-01-01

    Heme oxygenase-1 (HO-1) is a regulated enzyme induced in multiple stress states. Carbon monoxide (CO) is a product of HO catalysis of heme. In many circumstances, CO appears to functionally replace HO-1, and CO is known to have endogenous anti-inflammatory, anti-apoptotic, and antiproliferative effects. CO is well studied in anoxia-reoxygenation and ischemia-reperfusion models and has advanced to phase II trials for treatment of several clinical entities. In alternative injury models, laborat...

  17. 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...

  18. 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...

  19. 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...

  20. Radiotracer studies on molecular mechanisms of death and resuscitation

    International Nuclear Information System (INIS)

    Tracer techniques and artificial circulation were applied to rabbits after death by anoxia and deep hypothermia in order to study molecular mechanisms. 60 min after death the biosynthesis and disintegration of protein RNA and DNA practically stopped in all organs. In animals cooled post mortem the process of biosynthesis and degradation of protein, RNA and DNA, as well as the physiological functions of the whole organism, were restored. (author)

  1. Monitoring angiogenesis using a human compatible calibration for broadband near-infrared spectroscopy

    OpenAIRE

    Yang, Runze; Zhang, Qiong; Wu, Ying; Dunn, Jeff F.

    2013-01-01

    Abstract. Angiogenesis is a hallmark of many conditions, including cancer, stroke, vascular disease, diabetes, and high-altitude exposure. We have previously shown that one can study angiogenesis in animal models by using total hemoglobin (tHb) as a marker of cerebral blood volume (CBV), measured using broadband near-infrared spectroscopy (bNIRS). However, the method was not suitable for patients as global anoxia was used for the calibration. Here we determine if angiogenesis could be detecte...

  2. Effects of mitochondrial KATP modulators on cardioprotection induced by chronic high altitude hypoxia in rats

    Czech Academy of Sciences Publication Activity Database

    Neckář, Jan; Szárszoi, Ondrej; Koten, L.; Papoušek, František; Ošťádal, Bohuslav; Grover, G. J.; Kolář, František

    2002-01-01

    Roč. 55, č. 3 (2002), s. 567-575. ISSN 0008-6363 R&D Projects: GA ČR GA306/98/0470; GA ČR GA305/01/0279; GA MŠk LN00A069 Institutional research plan: CEZ:AV0Z5011922 Keywords : contractile function * hypoxia/anoxia * K-ATP channel Subject RIV: ED - Physiology Impact factor: 4.692, year: 2002

  3. 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...

  4. 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 ...

  5. 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...

  6. A small heat shock/α-crystallin protein from encysted Artemia embryos suppresses tubulin denaturation

    OpenAIRE

    Day, Rossalyn M.; Gupta, Jagdish S.; MacRae, Thomas H.

    2003-01-01

    Small heat shock/α-crystallin proteins function as molecular chaperones, protecting other proteins from irreversible denaturation by an energy-independent process. The brine shrimp, Artemia franciscana, produces a small heat shock/α-crystallin protein termed p26, found in embryos undergoing encystment, diapause, and metabolic arrest. These embryos withstand long-term anoxia and other stresses normally expected to cause death, a property likely dependent on molecular chaperone activity. The as...

  7. 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.

  8. 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.

  9. ECG Changes Due to Hypothermia Developed After Drowning: Case Report

    OpenAIRE

    Sabiye Yılmaz; Mehmet Akif Çakar; Mehmet Bülent Vatan; Harun Kılıç; Nurgül Keser

    2014-01-01

    Drowning is one of the fatal accidents frequently encountered during the summer and is the most common cause of accidental death in the world. Anoxia, hypothermia, and metabolic acidosis are mainly responsible for morbidty. Cardiovascular effects may occur secondary to hypoxia and hypothermia. Atrial fibrillation, sinus dysrhythmias (rarely requiring treatment), and, in serious cases, ventricular fibrillation or asystole may develop, showing as rhythm problems on electrocardiogram and Osborn ...

  10. 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

  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. Chemical micro-environments, ventilation behaviour and microbial processes in sponges

    OpenAIRE

    Schläppy, Marie-Lise

    2008-01-01

    The oxygen dynamics and ventilation behaviour in Dysidea avara and Chondrosia reniformis (Porifera) were investigated using oxygen micro-electrodes and hot-bead thermistors. Both field and laboratory experiments proved the common occurrences of anoxia in the sponge tissue that lasted up to approximately 1 h. Strong temporal and spatial heterogeneity of oxygen concentrations was observed with replicate oxygen profile series across the sponge surface, though tissue close to an osculum was gener...

  13. Hexadecane mineralization in oxygen-controlled sediment-seawater cultivations with autochthonous microorganisms.

    OpenAIRE

    Michaelsen, M; Hulsch, R; Höpner, T; Berthe-Corti, L

    1992-01-01

    Laboratory studies investigated the influence of dissolved oxygen tension (DOT) on microbial degradation of hexadecane in cultures with sediment-seawater suspensions. With a fermentor system, it was possible to adjust and regulate different oxic conditions (DOTs between 0.4 and 80% of oxygen saturation) as well as anoxia. The effects of DOT reduction on the amount and rate of hexadecane degraded and on the degree of mineralization and on the production of biomass were investigated. When the D...

  14. 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.

  15. 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.

  16. Post ischemic reperfusion and anoxic perfusion in the isolated heart: alteration in distribution of radionuclides and in protein synthesis

    International Nuclear Information System (INIS)

    Reperfusion after ischemia and perfusion with total anoxia were studied in the isolated guinea pig heart model, Deprivation of oxygen in both situations resulted in a marked shift of circulation from the left to the right ventricle, with markedly increased spaces of distribution of sup(99m)Tc radionuclides and albumin in the latter. In view of the complexities of measuring protein synthesis during ischemia, continuous anoxic perfusion was used to evaluate this parameter in anoxic induced arrest. There was a profound fall in protein synthesis associated with this arrest, accompanied by a fall in ATP, creatine phosphate, glycogen, potassium, and a rise in lactate production. The fall in protein synthesis was more marked in the left ventricle. The changes in synthesis were almost completely prevented by initiating cardiac arrest with high K+ (16 meq/l) at the same time as anoxia; energy metabolism remained near normal, and recovery of contractility was nearly complete. The studies demonstrated the differences in vascular distribution between the ventricles after ischemia or with perfusion anoxia, the possible difference in availability of substrate to the two ventricles under these conditions, as well as the difference in protein synthetic response, and further support the protective effect of potassium induced arrest on the hypoxic heart

  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. 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

  19. The effect of the anoxic radiosensitizing agent Tan on induction of revertants by γ-rays and helium ions in salmonella tester strains

    International Nuclear Information System (INIS)

    The modification effect of the anoxic radiosensitizer TAN on the mutagenesis in various Salmonella tester strains after γ-ray and helium ion irradiation was studied. The oxygen enhancement ratios (OER) for all 3 strains on the lethal assay after γ-irradiation is approximately equal to 2. The induction of reversions in TA98 and TA100 does not modify under anoxia. The value of OER on mutagenic assay in TA102 equals 1.6. The OER after helium ion irradiation on the lethal and mutagenic assay was less than after γ-irradiation. The mutagenesis in 3 strains after irradiation under anoxia enhances by TAN. The value of TAN modification effects after γ-irradiation increases from 2.1±0.2 for TA102 to 5±0.4 for TA100. However, TAN influence on mutagenesis in TA100 after helium ion irradiation decreases to 3.1±0.3. We conclude that peculiarities of mutagenesis in various tester strain under anoxia with TAN can be explained by considering the nature of premutational DNA damages. 23 refs.; 2 figs.; 2 tabs

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

    International Nuclear Information System (INIS)

    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.)

  1. Inhibition of Ectodermal-Neural Cortex 1 Protects Neural Cells from Apoptosis Induced by Hypoxia and Hypoglycemia.

    Science.gov (United States)

    Lei, Hongtao; Li, Jing; Zhao, Zhi; Liu, Li

    2016-05-01

    Ectodermal-neural cortex 1 (Enc1), a member of the KELCH family, is widely expressed in the nervous system and plays an important role in nervous system development. However, the function of Enc1 in neural survival following apoptosis induced by hypoxia and hypoglycemia remains unclear. In this study, we aimed to investigate the role of Enc1 in the cell survival of neurons subjected to apoptosis induced by oxygen-glucose deprivation (OGD) and the potential underlying mechanism. The in vitro cell model of neuron OGD was established by anoxia/hypoglycemic injury. Real-time quantitative PCR and Western blot analyses showed that Enc1 was significantly reduced in neurons under anoxia/hypoglycemic injury. Knockdown of Enc1 by small interfering RNA markedly promoted the survival of neurons under anoxia/hypoglycemia. Moreover, knockdown of Enc1 inhibited neuronal apoptosis. Conversely, overexpression of Enc1 showed the opposite effect. Further, data demonstrated that Enc1 might regulate neuron survival through heme oxygenase-1 (HO-1) and nuclear factor erythroid 2-related factor (Nrf2). Taken together, our study suggests that knockdown of Enc1 protects newborn neurons from apoptosis induced by OGD associated with Nrf2 and HO-1, providing a novel molecular target for the treatment of neonatal apoptosis induced by hypoxia and hypoglycemia brain injury. PMID:27039095

  2. Killing of Brain Tumor Cells by Hypoxia-Responsive Element Mediated Expression of BAX1

    Science.gov (United States)

    Ruan, Hangjun; Wang, Jingli; Hu, Lily; Lin, Ching-Shwun; Lamborn, Kathleen R; Deen, Dennis F

    1999-01-01

    Abstract 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 HRE 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 HRE copy number, and the degree of hypoxia. PMID:10933058

  3. 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.

  4. 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.

  5. ''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.)

  6. Co-induction of glucose regulated proteins and adriamycin resistance in Chinese hamster cells

    International Nuclear Information System (INIS)

    Glucose deprivation, anoxia, calcium ionophore A23187 or 2-deoxyglucose all inducers of glucose regulated proteins (grps), also lead to a significant induction of resistance to the drug adriamycin. In the case of anoxia, A23187 and 2-deoxyglucose, the induction of resistance correlates with both the application of the inducing stress and the induction of grps. In the case of glucose deprivation, the onset of resistance correlates with the onset of glucose deprivation and precedes grp induction. Removal of each grp including condition results in the rapid disappearance of this resistance in a manner which correlates with the repression of the grps. This drug resistance can be induced in confluent cells or in actively proliferating cells, although the effect is greater in the more sensitive proliferating cells. Induction of heat shock proteins (hsps) does not appear to lead to any major change in adriamycin resistance. Grp induced cells retain less adriamycin than do controls with the greatest reduction occurring during anoxia, which is also the strongest inducer of grps and resistance. The authors propose that the application of a grp inducing stress leads to a concurrent induction in drug resistance, possibly via the translocation of grps in the cell. Finally, they also observed that adriamycin itself can induce both hsps and grps. It is possible that adriamycin exposure may correspondingly induce auto-resistance

  7. 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.

  8. 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

  9. 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

  10. 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

  11. Flooding effects on plant physiology and VOC emissions from Amazonian tree species from two different flooding environments: Varzea and Igapo

    Science.gov (United States)

    Bracho Nunez, A.; Knothe, N.; Liberato, M. A. R.; Schebeske, G.; Ciccioli, P.; Piedade, M. T. F.; Kesselmeier, J.

    2009-04-01

    A land area of 300.000 km² in the Amazon basin is subjected to a continuous flooding pulse, being flooded for 210 days a-1 on an average (Junk et al. 1993). To survive the flooding period vegetation has developed several morphological, anatomical and physiological strategies to mitigate the produced stress due to root anoxia. One of the strategies is fermentation of sucrose in the roots to comply with the energy demand under anoxia. The resulting toxic metabolite ethanol is transported through the transpiration stream to the leaves and can be directly emitted into the atmosphere or converted to acetaldehyde and/or acetate, still volatile enough to be partly released. We investigated short-term and long-term flooding effects on physiology and VOC emission by plant species from várzea and igapó and observed ethanol and acetaldehyde emissions from the várzea species Vatairea guianensis after one day of flooding, which decreased considerably within the next three days. The same species from igapó showed no acetaldehyde emission and much lower emission rates of ethanol, than the várzea species. In contrast Hevea spruceana from both várzea and igapó showed no ethanol or acetaldehyde emissions. After long term flooding (2 months) we did not find any emissions of acetaldehyde or ethanol from all plant species investigated. However, isoprene and monoterpene emissions were clearly affected, showing a significant decrease. Carbon dioxide assimilation was not affected by short term flooding, but declined after two months root anoxia in the case of Hevea spruceana.

  12. Cadmium-isotopic evidence for increasing primary productivity during the Late Permian anoxic event

    Science.gov (United States)

    Georgiev, Svetoslav V.; Horner, Tristan J.; Stein, Holly J.; Hannah, Judith L.; Bingen, Bernard; Rehkämper, Mark

    2015-01-01

    Earth's most extreme extinction event near the end of the Late Permian decimated more than 90% of all extant marine species. Widespread and intensive oceanic anoxia almost certainly contributed to the catastrophe, though the driving mechanisms that sustained such conditions are still debated. Of particular interest is whether water column anoxia was a consequence of a 'stagnant ocean', or if it was controlled by increases in nutrient supply, primary productivity, and subsequent heterotrophic respiration. Testing these competing hypotheses requires deconvolving sedimentary/bottom water redox conditions from changes in surface water productivity in marine sediments. We address this issue by studying marine shales from East Greenland and the mid-Norwegian shelf and combining sedimentary redox proxies with cadmium-isotopic analyses. Sedimentary nitrogen-isotopic data, pyrite framboid analyses, and organic and inorganic shale geochemistry reveal sulfidic conditions with vigorous upwelling, and increasingly anoxic conditions with a strengthening upwelling in the Greenland and Norwegian sections, respectively. Detailed analysis of sedimentary metal budgets illustrates that Cd is primarily associated with organic carbon and records primary geochemical signatures, thus enabling reconstruction of surface water nutrient utilization. Cadmium-isotopic analyses of the authigenic shale fraction released by inverse aqua regia digestion yield an average δ114Cd110 of + 0.15 ± 0.01 ‰ (2 SE, n = 12; rel. NIST SRM 3108), indicative of incomplete surface water nutrient utilization up-section. The constant degree of nutrient utilization combined with strong upwelling requires increasing primary productivity - and not oceanic stagnation - to balance the larger nutrient fluxes to both study sites during the development of the Late Permian water column anoxia. Overall, our data illustrate that if bottom water redox and upwelling can be adequately constrained, Cd-isotopic analyses of

  13. 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

  14. 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.

  15. 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.

  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. Computed tomography of CNS disease. A teaching file

    International Nuclear Information System (INIS)

    This ''teaching file'' comprises a clinically representative collection of over 400 cases of neuropathology diagnosed by computed tomography. Each case is accompanied by a discussion of CT interpretation. Comments on clinical presentation, pathophysiological findings, and therapy are included where appropriate. Abnormalities covered include metastases, meningiomas, posterior fossa tumors inflammatory and degenerative diseases, infarction and anoxia, and spinal lesions. Each pathological category demonstrates a range of CT findings from ''classic'' patterns to atypical examples. Anatomical variants are included only if they mimic pathology. Diverse lesions that potentially resemble each other are highlighted throughout the book in special sections entitled, ''Differential Diagnoses''

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

    DEFF Research Database (Denmark)

    Dahl, Tais Wittchen; Boyle, Richard A.; Canfield, Donald E.;

    2014-01-01

    euxinic waters, triggering the spike in U burial, and peaking in conjunction with a well-known trilobite extinction event. During the second stage widespread euxinia waned, causing U removal to tail off, but enhanced organic carbon and pyrite burial continued, coinciding with evidence for severe sulfate...... depletion in the oceans (Gill et al., 2011). We discuss scenarios for how an interval of elevated pyrite and organic carbon burial could have been sustained without widespread euxinia in the water column (both non-sulfidic anoxia and/or a more oxygenated ocean state are possibilities). Either way, the SPICE...

  1. 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...

  2. 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

  3. [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

  4. 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...

  5. Idiopathic Hypoparathyroidism associated Fahrs Disease: Two Case Reports and Review of the Literature

    Directory of Open Access Journals (Sweden)

    Mehtap Evran

    2015-12-01

    Full Text Available Bilateral Striopallidodentat Calcinosis also called Fahrs disease (FH; basal ganglia, thalamus, and cerebellar dentate nucleus is a disease characterized by symmetric calcifications in the cerebral white matter. Calcifications are often drawn attention in brain imaging for other reasons. The disease can progress with clinically variable neurological or neuro-psychiatric symptoms. Fahrs disease are believed to be associated with anoxia, radiation, systemic diseases, toxins calcium metabolism disorders, and encephalitis. We presented two cases with primary hypoparathyroidism were diagnosed and detected of neurological problems, cerebral and cerebellar calcifications on imaging. [Cukurova Med J 2015; 40(4.000: 836-840

  6. Bases del manejo clínico de la intoxicación por humo de incendios «Docohumo Madrid 2010» Basis for the clinical management of fire smoke poisoning "Docohumo Madrid 2010"

    OpenAIRE

    A. Dueñas-Laita; G. Burillo Putze; Alonso, J. R.; Bajo, A; Climent, B.; E. Corral; F. Felices; Ferrer, A.; M.P. Hernández Frutos; S Nogué; J. Puiguriguer

    2010-01-01

    La intoxicación por humo es la principal causa de morbimortalidad en los incendios. El humo es una mezcla de partículas carbonáceas suspendidas en aire caliente y gases tóxicos. De todos ellos, el monóxido carbono (CO) y fundamentalmente el ácido cianhídrico (CNH) son los que van a provocar la anoxia tisular. Las manifestaciones clínicas de la intoxicación por humo son variables. Algunas de las manifestaciones potenciales podrían ser: irritación ocular, dolor de garganta, estridor laríngeo, d...

  7. Leucoencefalopatía hipóxica tardía Delayed Hypoxic Leukoencephalopathy

    OpenAIRE

    Pablo Sartori; Rolando Giannaula; Gabriela Orzuza

    2012-01-01

    La Leucoencefalopatía Hipóxica Tardía (LHT) es una enfermedad desmielinizante de infrecuente presentación. Se produce como consecuencia de un fenómeno de hipoxia-anoxia y aparece días o semanas más tarde.Los síntomas y cambios imagenológicos remiten casi totalmente y tienen un buen pronóstico En este reporte se ilustra el caso de una joven que desarrolló LHT luego de sufrir un paro cardiorrespiratorio.Delayed Hypoxic Leukoencephalopathy (DHL) is a rare demyelinating disease. This condition oc...

  8. Participación de los canales de calcio dependientes de voltaje en el desarrollo de la epilepsia Participation of voltage-dependent calcium channels in the development of epilepsy

    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,...

  9. Effects of algae-mat thickness on survival and growth of eelgrass (Zostera marina) seedlings

    DEFF Research Database (Denmark)

    Rasmussen, Jonas; Olesen, Birgit

    eelgrass even short periods of water column anoxia may have severe implications for growth and survival. In addition, excessive covering by macroalgal mats decrease the available light at leaf surface and may hamper the diffusive movement of oxygen, inorganic carbon and nutrients to and from the shoot thus......: Chaetomorpha linum and artificial macroalgae. The two types of mats were used to separate physical and metabolic effects of algal presence. During the growth period concentrations of oxygen and sulphide and their diurnal variations in the mats were measured using microelectrodes....

  10. 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...

  11. 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...

  12. [Near death experiences].

    Science.gov (United States)

    Rubia Vila, Francisco José

    2012-01-01

    Near Death Experiences are those accounted by people who after being clinically dead return to life spontaneously or after reanimation. These experiences have been used traditionally to support the belief in the existence of the soul and of life after death. However, today neuroscience tries to explain these experiences from the scientific point of view, i.e. explaining them based on their brain substrates. Their resemblance to mystic experiences and to altered states of consciousness seems to indicate that they may be produced by hyperactivity of limbic structures caused by anoxia or hypercapnia. PMID:24294729

  13. 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

  14. Modality specific semantic knowledge loss for unique items.

    Science.gov (United States)

    Kartsounis, L D; Shallice, T

    1996-03-01

    We report the case of a man who, following a major myocardial infarction, suffered anoxia followed by significant event memory impairment. Investigations indicated that his semantic memory for word concepts and object meanings was well preserved. However, he had great difficulty in identifying in the visual (but not verbal) modality historically known people, such as Queen Elizabeth I and Napoleon, and well known world and London landmarks, such as the Parthenon and Buckingham Palace. This selective impairment could not be accounted for in terms of prosopagnosia or high level visual perceptual deficits and we interpret it as a modality specific semantic memory loss for unique objects. PMID:8697742

  15. A fatal case of Perthes syndrome

    Directory of Open Access Journals (Sweden)

    Jérôme Jobé

    2013-01-01

    Full Text Available Perthes syndrome, or traumatic asphyxia, is a clinical syndrome associating cervicofacial cyanosis with cutaneous petechial haemorrhages and subconjonctival bleeding resulting from severe sudden compressive chest trauma. Deep inspiration and a Valsalva maneuver just prior to rapid and severe chest compression, are responsible for the development of this syndrome. Current treatment is symptomatic: urgent relief of chest compression and cardiopulmonary resuscitation if needed. Outcome may be satisfactory depending on the duration and severity of compression. Prolonged thoracic compression may sometimes lead to cerebral anoxia, irreversible neurologic damage and death. We report a fatal case of Perthes syndrome resulting from an industrial accident.

  16. Role of PET/CT functional imaging on constructing a tumor radiotherapeutic biological target volume

    International Nuclear Information System (INIS)

    In studies on intensity modulated radiotherapy with conventional fractionation, different radiosensitivity areas require different irradiation doses. In tumor radiotherapy areas CR, boosts in radiotherapy doses should be determined according to whether there are survived tumor cells or not. To those survived cells, CT imaging has become the key tool to delineate the radiotherapy target. Thus, the study on the construction of biological target volume with PET/CT functional imaging, which could reflect either radiosensitivity or cell proliferation-related cell metabolism, anoxia and DNA number of various cell cycle phases, is an important research area. (authors)

  17. 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

  18. 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...

  19. 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....... anderseni 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....

  20. 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...

  1. PAMPs and DAMPs stimulate the expression of pro-inflammatory cytokines in vitro in fibroblasts from fish

    DEFF Research Database (Denmark)

    Ingerslev, Hans-Christian; Ossum, C.G.; Przybylska, Dominika;

    through recognition of PAMPs and DAMPs by non immune cells seems plausible. 1Ossum, C.G., et al. (2004) Characterization of a novel fibroblast-like cell line from rainbow trout and responses to sublethal anoxia. Journal of Fish Biology, 64, 1103-1116. This work was supported by The Directorate for Food......, Fisheries and Agri Business grant nr. 3310-06-00116 and by the EU Training network on protective immune modulation in warm water fish by feeding glucans (NEMO), grant nr. 214505....

  2. 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.

  3. A unique micromechanocalorimeter for simultaneous measurement of heat rate and force production of cardiac trabeculae carneae.

    Science.gov (United States)

    Han, June-Chiew; Taberner, Andrew J; Kirton, Robert S; Nielsen, Poul M; Smith, Nicholas P; Loiselle, Denis S

    2009-09-01

    To study cardiac muscle energetics quantitatively, it is of paramount importance to measure, simultaneously, mechanical and thermal performance. Ideally, this should be achieved under conditions that minimize the risk of tissue anoxia, especially under high rates of energy expenditure. In vitro, this consideration necessitates the use of preparations of small radial dimensions. To that end, we have constructed a unique micromechanocalorimeter, consisting of an open-ended flow-through microcalorimeter, a force transducer, and a pair of muscle-length actuators. The device enables the metabolic and mechanical performance of cardiac trabeculae carneae to be investigated for prolonged periods in a continuously replenished oxygen- and nutrient-rich environment. PMID:19589958

  4. 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.

  5. 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...

  6. 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...

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

    DEFF Research Database (Denmark)

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

    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...... is contemporaneous with the widely observed occurrence of black shale deposition during OAE2. Paleontological, lithological, and geochemical data indicate normal marine conditions with persistent anoxic bottom waters during OAE2. The results imply that the high marine primary productivity pulse...

  8. Anesthetic issues and perioperative blood pressure management in patients who have cerebrovascular diseases undergoing surgical procedures.

    Science.gov (United States)

    Jellish, W Scott

    2006-11-01

    Patients who have cerebrovascular disease and vascular insufficiency routinely have neurosurgical and nonneurosurgical procedures. Anesthetic priorities must provide a still bloodless operative field while maintaining cardiovascular stability and renal function. Patients who have symptoms or a history of cerebrovascular disease are at increased risk for stroke, cerebral hypoperfusion, and cerebral anoxia. Type of surgery and cardiovascular status are key concerns when considering neuroprotective strategies. Optimization of current condition is important for a good outcome; risks must be weighed against perceived benefits in protecting neurons. Anesthetic use and physiologic manipulations can reduce neurologic injury and assure safe and effective surgical care when cerebral hypoperfusion is a real and significant risk. PMID:16935193

  9. 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.

  10. 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.

  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. Influence of acute hypoxia and radiation quality on cell survival

    OpenAIRE

    Tinganelli, Walter; Ma, Ning-Yi; von Neubeck, Cläre; Maier, Andreas; Schicker, Corinna; Kraft-Weyrather, Wilma; Durante, Marco

    2013-01-01

    To measure the effect of acute oxygen depletion on cell survival for different types of radiation, experiments have been performed using Chinese hamster ovary (CHO) cells and RAT-1 rat prostate cancer cells. A special chamber has been developed to perform irradiations under different levels of oxygenation. The oxygen concentrations used were normoxia (air), hypoxia (94.5% N2, 5% CO2, 0.5% O2) and anoxia (95% N2, 5% CO2). Cells were exposed to X-rays and to C-, N- or O-ions with linear energy ...

  13. Dynamic Aspects of Alcoholic Fermentation of Rice Seedlings in Response to Anaerobiosis and to Complete Submergence: Relationship to Submergence Tolerance

    OpenAIRE

    BOAMFA, E. I.; RAM, P. C.; Jackson, M B; Reuss, J.; Harren, F.J.M.

    2003-01-01

    Rice plants are severely damaged by complete submergence. This is a problem in rice farming and could be the result, in part, of tissue anoxia imposed by a reduced availability of oxygen. To investigate this possibility we monitored alcoholic fermentation products as markers for tissue anaerobiosis using sensitive laser‐based spectroscopy able to sense ethanol and acetaldehyde down to 3 nl l–1 and 0·1 nl l–1, respectively. Acetaldehyde emission began within 0·5 h of imposing an oxygen‐free ga...

  14. Quantifying ATP turnover in anoxic coleoptiles of rice (Oryza sativa) demonstrates preferential allocation of energy to protein synthesis

    OpenAIRE

    Edwards, Joshua M.; Roberts, Thomas H.; Atwell, Brian J.

    2012-01-01

    Oxygen deprivation limits the energy available for cellular processes and yet no comprehensive ATP budget has been reported for any plant species under O2 deprivation, including Oryza sativa. Using 3-d-old coleoptiles of a cultivar of O. sativa tolerant to flooding at germination, (i) rates of ATP regeneration in coleoptiles grown under normoxia (aerated solution), hypoxia (3% O2), and anoxia (N2) and (ii) rates of synthesis of proteins, lipids, nucleic acids, and cell walls, as well as K+ tr...

  15. Aquatic nitrogen transformations at low oxygen concentrations.

    OpenAIRE

    Downes, M T

    1988-01-01

    Nitrite and nitrous oxide made up 40% of the hypolimnetic dissolved inorganic nitrogen in mesotrophic Lake Rotoiti, New Zealand, prior to hypolimnetic anoxia. Up to 120 mg of N m-3 as nitrite and 20 mg of N m-3 as nitrous oxide accumulated, whereas dissolved-oxygen concentrations remained between 1.0 and 0.2 g m-3 and were totally consumed when the hypolimnion became completely anoxic. Assays of water column nitrification potentials, together with measurements of the relative rates of nitrate...

  16. THE ROLE OF HEAT SHOCK PROTEIN (HSP IN ORAL DISEASE

    Directory of Open Access Journals (Sweden)

    Theresia Indah Budhy

    2015-06-01

    Full Text Available Heat Shock Protein (HSP is a molecular chaperone that prevents stress-induced aggregation of partially denatured proteins and promotes their return to native confirmation when the condition is favorable. As molecular chaperones, the HSP protect protein structure and activity, thereby preventing disease, but they may contribute to cell malfunction if they are perturbed. Intracellular quantities and cellular localization of HSP was changed in response to anoxia/hypoxia, heat and oxidation, and in relation to pathological status. This review discusses the role of HSP in several human medical condition particularly in oral mucosa.

  17. 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.

  18. Methylmercury in water, sediment, and invertebrates in created wetlands of Rouge Park, Toronto, Canada

    International Nuclear Information System (INIS)

    Thousands of hectares of wetlands are created annually because wetlands provide beneficial ecosystem services. Wetlands are also key sites for production of the bioaccumulative neurotoxin methylmercury (MeHg), but little is known about MeHg production in created systems. Here, we studied methylmercury in sediment, water, and invertebrates in created wetlands of various ages. Sediment MeHg reached 8 ng g−1 in the newest wetland, which was significantly greater than in natural, control wetlands. This trend was mirrored in several invertebrate taxa, whose concentrations reached as high as 1.6 μg g−1 in the newest wetland, above levels thought to affect reproduction in birds. The MeHg concentrations in created wetland invertebrate taxa generally decreased with increasing wetland age, possibly due to a combination of deeper anoxia and less organic matter accumulation in younger wetlands. A short-term management intervention and/or improved engineering design may be necessary to reduce the mercury-associated risk in newly created wetlands. - Highlights: ► Investigated methylmercury accumulation in created wetland ecosystems. ► Concentrations and bioaccumulation significantly elevated in new created wetlands. ► Short-term effect may be due to deeper anoxia, less organic matter in new wetlands. ► Intervention or improved design required to reduce short-term ecological risk. - Sediment methylmercury concentrations and bioaccumulation in many invertebrate taxa are significantly elevated in newly created wetlands.

  19. Effects of some .OH scavengers on the radiation sensitizaation of bacterial spores by p-nitroacetophenone and O2 in suspension

    International Nuclear Information System (INIS)

    Spores of Bacillus megaterium were irradiated in suspension with 50 kVp X-rays under three reference conditions: in anoxia (i.e., 100 per cent N2); in anoxia with 2 mM p-nitroacetophenone (PNAP), a concentration that shows the maximum amount of sensitization by this agent; and in air. The responses were then measured when different concentrations of an hydroxyl radical scavenger were also present. Allyl alcohol, t-amyl alcohol, t-butanol, ethanol, glycerol, the formate ion, and methanol were the .OH scavengers that were used. A comparison of the effects these additives had on the three reference responses provided indirect, comparative information on the sensitizing processes of PNAP and O2. Neither t-amyl alcohol or t-butanol affected the response in air or N2 alone. Both these additives, however, could reduce the sensitization from PNAP slightly. The other additives had significant protective effects under the three conditions. In general, the additives had similar effects in air and in 100 per cent N2 but much greater protective effects in PNAP. Although the sensitizing mechanisms were not identified by these experiments, the effects of O2 and PNAP, as judged by the desensitizing actions of these additives, appeared quite different. (author)

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Mechanisms of waterlogging tolerance in wheat - a review of root and shoot physiology.

    Science.gov (United States)

    Herzog, Max; Striker, Gustavo G; Colmer, Timothy D; Pedersen, Ole

    2016-05-01

    We review the detrimental effects of waterlogging on physiology, growth and yield of wheat. We highlight traits contributing to waterlogging tolerance and genetic diversity in wheat. Death of seminal roots and restriction of adventitious root length due to O2 deficiency result in low root:shoot ratio. Genotypes differ in seminal root anoxia tolerance, but mechanisms remain to be established; ethanol production rates do not explain anoxia tolerance. Root tip survival is short-term, and thereafter, seminal root re-growth upon re-aeration is limited. Genotypes differ in adventitious root numbers and in aerenchyma formation within these roots, resulting in varying waterlogging tolerances. Root extension is restricted by capacity for internal O2 movement to the apex. Sub-optimal O2 restricts root N uptake and translocation to the shoots, with N deficiency causing reduced shoot growth and grain yield. Although photosynthesis declines, sugars typically accumulate in shoots of waterlogged plants. Mn or Fe toxicity might occur in shoots of wheat on strongly acidic soils, but probably not more widely. Future breeding for waterlogging tolerance should focus on root internal aeration and better N-use efficiency; exploiting the genetic diversity in wheat for these and other traits should enable improvement of waterlogging tolerance. PMID:26565998

  5. 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.

  6. 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.

  7. Half-life values for DNA double-strand break rejoining in yeast can vary by more than an order of magnitude depending on the irradiation conditions

    International Nuclear Information System (INIS)

    Yeast cells in stationary phase were exposed under oxic or anoxic conditions to sparsely (30 MeV electrons) or densely (3.5 MeV α-particles) ionizing radiation. For all four experimental set-ups postirradiation treatment of cells was the same, i.e. cells were kept under oxic conditions in non-growth medium at 30oC. Double-strand break (dsb) rejoining was measured during this treatment yielding the following results: (1) half-life values ranged from <60 min (electrons, anoxia) to 3.8 h (low doses of electrons, oxia), 7 h (α-particles, anoxia), 10 h (high doses of electrons, oxia) and 13 h (α-particles, oxia). (2) In the case of exposure of oxic cells to electrons a biphasic rejoining kinetics is observed with a dose-dependent increase of the fraction of the slow component. These results suggest that half-life values of dsb rejoining in a given cell depend on physical, chemical and biological parameters. The biphasic rejoining kinetics observed for dsb induced by electrons in oxic cells is interpreted in terms of a dose-dependent change of chromatin structure hindering the interaction between damaged chromatin and the rejoining enzymes rather than by two chemically distinct types of dsb with differing half-life values. (Author)

  8. Lowering Temperature is the Trigger for Glycogen Build-Up and Winter Fasting in Crucian Carp (Carassius carassius).

    Science.gov (United States)

    Varis, Joonas; Haverinen, Jaakko; Vornanen, Matti

    2016-02-01

    Seasonal changes in physiology of vertebrate animals are triggered by environmental cues including temperature, day-length and oxygen availability. Crucian carp (Carassius carassius) tolerate prolonged anoxia in winter by using several physiological adaptations that are seasonally activated. This study examines which environmental cues are required to trigger physiological adjustments for winter dormancy in crucian carp. To this end, crucian carp were exposed to changing environmental factors under laboratory conditions: effects of declining water temperature, shortening day-length and reduced oxygen availability, separately and in different combinations, were examined on glycogen content and enzyme activities involved in feeding (alkaline phosphatase, AP) and glycogen metabolism (glycogen synthase, GyS; glycogen phosphorylase, GP). Lowering temperature induced a fall in activity of AP and a rise in glycogen content and rate of glycogen synthesis. Relative mass of the liver, and glycogen concentration of liver, muscle and brain increased with lowering temperature. Similarly activity of GyS in muscle and expression of GyS transcripts in brain were up-regulated by lowering temperature. Shortened day-length and oxygen availability had practically no effects on measured variables. We conclude that lowering temperature is the main trigger in preparation for winter anoxia in crucian carp. PMID:26853873

  9. Influence of acute hypoxia and radiation quality on cell survival

    International Nuclear Information System (INIS)

    The purpose of this study was to measure the effect of acute oxygen depletion on cell survival for different types of radiation, experiments have been performed using Chinese hamster ovary (CHO) cells and R-3327-AT1 (RAT-1) rat prostate cancer cells. A special chamber has been developed to perform irradiations under different levels of oxygenation. The oxygen concentrations used were normoxia (air), hypoxia (94.5% N2, 5% CO2, 0.5% O2) and anoxia (95% N2, 5% CO2). Cells were exposed to X-rays and to C-, N- or O-ions with linear energy transfer (LET) values ranging from 100-160 keV/μm. The oxygen enhancement ratio (OER) and relative biological effectiveness (RBE) values have been calculated from the measured clonogenic survival curves. For both cell lines, the X-ray OER depended on the survival level. For particle irradiation, OER was not dependent on the survival level but decreased with increasing LET. The RBE of CHO cells under oxic conditions reached a plateau for LET values above 100 keV/μm, while it was still increasing under anoxia. In conclusion, the results demonstrated that our chamber could be used to measure radiosensitivity under intermediate hypoxia. Measurements suggest that ions heavier than carbon could be of additional advantage in the irradiation, especially of radioresistant hypoxic tumor regions. (author)

  10. PETO Interacts with Other Effectors of Cyclic Electron Flow in Chlamydomonas.

    Science.gov (United States)

    Takahashi, Hiroko; Schmollinger, Stefan; Lee, Jae-Hyeok; Schroda, Michael; Rappaport, Fabrice; Wollman, Francis-André; Vallon, Olivier

    2016-04-01

    While photosynthetic linear electron flow produces both ATP and NADPH, cyclic electron flow (CEF) around photosystem I (PSI) and cytochrome b6f generates only ATP. CEF is thus essential to balance the supply of ATP and NADPH for carbon fixation; however, it remains unclear how the system tunes the relative levels of linear and cyclic flow. Here, we show that PETO, a transmembrane thylakoid phosphoprotein specific of green algae, contributes to the stimulation of CEF when cells are placed in anoxia. In oxic conditions, PETO co-fractionates with other thylakoid proteins involved in CEF (ANR1, PGRL1, FNR). In PETO-knockdown strains, interactions between these CEF proteins are affected. Anoxia triggers a reorganization of the membrane, so that a subpopulation of PSI and cytochrome b6f now co-fractionates with the CEF effectors in sucrose gradients. The absence of PETO impairs this reorganization. Affinity purification identifies ANR1 as a major interactant of PETO. ANR1 contains two ANR domains, which are also found in the N-terminal region of NdhS, the ferredoxin-binding subunit of the plant ferredoxin-plastoquinone oxidoreductase (NDH). We propose that the ANR domain was co-opted by two unrelated CEF systems (PGR and NDH), possibly as a sensor of the redox state of the membrane. PMID:26768121

  11. Do pH changes in the leaf apoplast contribute to rapid inhibition of leaf elongation rate by water stress? Comparison of stress responses induced by polyethylene glycol and down-regulation of root hydraulic conductivity.

    Science.gov (United States)

    Ehlert, Christina; Plassard, Claude; Cookson, Sarah Jane; Tardieu, François; Simonneau, Thierry

    2011-08-01

    We have dissected the influences of apoplastic pH and cell turgor on short-term responses of leaf growth to plant water status, by using a combination of a double-barrelled pH-selective microelectrodes and a cell pressure probe. These techniques were used, together with continuous measurements of leaf elongation rate (LER), in the (hidden) elongating zone of the leaves of intact maize plants while exposing roots to various treatments. Polyethylene glycol (PEG) reduced water availability to roots, while acid load and anoxia decreased root hydraulic conductivity. During the first 30 min, acid load and anoxia induced moderate reductions in leaf growth and turgor, with no effect on leaf apoplastic pH. PEG stopped leaf growth, while turgor was only partially reduced. Rapid alkalinization of the apoplast, from pH 4.9 ± 0.3 to pH 5.8 ± 0.2 within 30 min, may have participated to this rapid growth reduction. After 60 min, leaf growth inhibition correlated well with turgor reduction across all treatments, supporting a growth limitation by hydraulics. We conclude that apoplastic alkalinization may transiently impair the control of leaf growth by cell turgor upon abrupt water stress, whereas direct hydraulic control of growth predominates under moderate conditions and after a 30-60 min delay following imposition of water stress. PMID:21477119

  12. Formation and repair of DNA double-strand breaks in superinfecting phage lambda after ionizing irradiation of Escherichia coli host cells

    International Nuclear Information System (INIS)

    Cells of Escherichia coli containing superinfecting phage lambda DNA molecules were irradiated with 4-MeV electrons and lysed at neutral pH; the lysates were sedimented in neutral sucrose gradients to separate lambda DNA molecules containing no strand breaks, one or more single-strand breaks, or a double-strand break. About 40 single-strand breaks were induced for every double-strand break in both the presence and absence of oxygen. The single-strand breaks were rapidly repaired after irradiation in nitrogen anoxia and subsequent incubation in aerobic growth medium, but no net reduction in the number of double-strand breaks was observed. This is similar to observations after oxic irradiation. No quadratic dose dependence of double-strand break induction was found up to 500 krad in oxygen and up to 1800 krad in nitrogen anoxia. Also, no difference in double-strand breakage was observed when equal doses in the range of 60 to 80 krad were delivered either (i) acutely, with 1 sec. or (ii) intermittently, with time to repair most single-strand breaks before onset of the next radiation pulse. It is concluded that the proposed mechanism whereby two independently induced single-strand breaks pair to form a double-strand break is not significant in the biological dose range

  13. 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.

  14. 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

  15. Physiological and biochemical characterization of the assai palm (Euterpe oleracea Mart. during seed germination and seedling growth under aerobic and anaerobic conditions

    Directory of Open Access Journals (Sweden)

    José Francisco de Carvalho Gonçalves

    2010-12-01

    Full Text Available Physiological and biochemical aspects of assai palm during seed germination and early seedling growth were investigated. Seeds collected from plants growing in flooded and upland forests were used to determine the influence of normoxic (aerobic and anoxic (anaerobic conditions in germination and the initial and average time of development in the roots and shoots. After 75 days, seedlings germinated under normoxia were transferred to trays and submitted to flooding. Seed reserves (lipids, proteins, soluble sugars and starch were monitored for quiescent and germinated seeds maintained under normoxic and anoxic conditions, as well as after 5, 10 and 20 days of seedling growth. Alcohol dehydrogenase (ADH activity was quantified in roots and leaves of seedlings without or with flooding (partial and total. Seeds were not able to germinate under anoxia. Different strategies of storage mobilization of lipids, proteins, soluble sugars and starch were observed in seeds of each environment. ADH activity was induced by anoxia, with the highest level observed in the leaves. This study showed that, under normoxic conditions, the best developmental performance of assai palm seeds, from flooded or upland forest areas, during germination was associated with primary metabolites mobilization and seedling flooding tolerance with increased ADH activity. We conclude that the assai palm is well adapted to the anoxic conditions provoked by flooding.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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

  3. 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

  4. Possible Pre-Cryogenian Eutrophication Event Recorded In ~770-742 Ma Strata Of The Uinta Mountain Group, Utah, USA

    Science.gov (United States)

    Dehler, C. M.; Hayes, D. S.; Nagy, R. M.

    2011-12-01

    Previous mid-Neoproterozoic microfossil diversity studies yield evidence for a relatively sudden biotic change prior to the Cryogenian (Sturtian) glaciations. In an event interpreted as a mass extinction of eukaryotic phytoplankton followed by bacterial dominance, diverse assemblages of complex acritarchs are replaced by more uniform assemblages consisting of simple leiosphaerid acritarchs and bacteria. Recent data from the Chuar Group of the Grand Canyon (770-742 Ma) suggest this biotic change was caused by eutrophication rather than the previous idea that this change was due to the direct effects of Sturtian glaciation. Evidence includes total organic carbon increases indicative of increasing primary productivity followed by iron speciation values that suggest sustained water column anoxia. A new data set (this study) suggests that this same eutrophication event may be recorded in shale units of the formation of Hades Pass and the Red Pine Shale of Utah's Neoproterozoic Uinta Mountain Group (770-742 Ma). Preliminary results of this study include a significant shift in microfossil assemblage from a higher-diversity (H'= 0.60) fauna that includes some ornamented acritarchs to a lower-diversity (H' = 0.11) fauna dominated by smooth leiosphaerids and microfossils of a bacterial origin (Ba|lla/ Sphaerocongregus sp.). This biotic change co-occurs with a significant increase in total organic carbon values that directly follows a positive carbon-isotopic excursion, suggesting increased primary productivity that may have been the result of elevated sediment influx and nutrient availability. Both the biotic change and period of increased total organic carbon values correspond with the onset of an interval of anoxia (indicated by total iron to aluminum ratios above 0.60) and a spike in sulfur concentration. Thus far, these findings support 1) correlations between the Uinta Mountain and Chuar groups, 2) the idea that the biotic turnover preserved in both strata was at least

  5. 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

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

    Directory of Open Access Journals (Sweden)

    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

  7. 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

    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...... stimulated the cumulative N2O emissions and reduced the cumulative CO2 fluxes. The faster the anoxia developed, the less the nitrification process appeared to contribute to N2O emissions. No treatment effects on CH4 emissions were observed. Combined high resolution imaging of O2 dynamics and measurements of...... producing greenhouse gases from soil ecosystems....

  8. Benthic mineralization and nutrient exchange over the inner continental shelf of western India

    Directory of Open Access Journals (Sweden)

    A. K. Pratihary

    2013-06-01

    Full Text Available The western Indian continental shelf is one of most productive coastal systems of the world ocean. This system undergoes extreme change in oxygen regime being normoxic from November to May and suboxic/anoxic from June to October owing to the biogeochemical response to cyclical monsoonal influence. In order to understand its impact on benthic mineralization, nutrient exchange and in turn on the shelf ecosystem, we carried out first ever intact core incubation experiments by covering two contrasting seasons i.e. Spring intermonsoon and fall intermonsoon (late southwest monsoon. The results show that the shelf sediments act as a perennial net source of DIN, PO43– and SiO44– to the overlying water column. DIN efflux increased from 1.4 to 3.21 mmol m–2 d–1 from April to October of which NH4+ comprises 59–100%. During oxic regime about 75% of diffusing NH4+ appears to be nitrified (2.55 mmol m–2 d–1 of which about 77% remains coupled to benthic denitrification. Consequently 58% of NH4+ flux gets lost in active coupled nitrification-denitrification process causing substantial N loss (1.98 mmol m–2 d–1 in the sediment. The continental shelf sediment switches over from being a NO3– source during oxic regime to a NO3– sink during low oxygen regime. During suboxia benthic denitrification being fed by NO3– from overlying water causes N loss at a rate of 1.04 mmol m–2 d–1. N loss continues even in sulfidic condition during October possibly through chemolithoautotrophic denitrification at a potential rate of 3.21 mmol m–2 d–1. PO43– flux increased more than 4 fold during October as compared to April due to reductive dissolution of Fe and Mn oxides. The SiO44– flux increases during anoxia due to higher availability of siliceous ooze as a result of diatom blooms during the monsoon season. Porewater was found to be enriched with NH4+, PO43– and SiO44– while depleted in NO3– and NO2– in these organic rich sediments

  9. 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 (TOCagreement 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 incorporated in pyrite in the Cleveland Basin after the CIE, because the availability of sulphur was more limited after the global anoxia

  10. Modification of survival of gamma irradiated mice by adenosine nucleotides

    International Nuclear Information System (INIS)

    The administration prior to irradiation of adenosine triphosphate (ATP) or other adenosine nucleotides, singly or in combination, increased the radioresistance of mice. Post-irradiation treatment with the adenosine nucleotides had no effect on the survival of the irradiated mice. Dose reduction factors of 2.32 could be obtained by pretreatment of mice with the following combination of protective agents: S-2(4-aminobutylamino)ethyl phosphorothioic aced (WR 2822), cysteamine (MEA) and ATP. Since cyclic AMP levels were unchanged in the spleen or gut by administration of cysteamine and other protectors it is unlikely that the increase in protection was due to changes in cyclic AMP levels. The calcium salt of ATP provided a higher level of protection than the ATP alone, indicating that the protective mechanism of ATP is probably not related to anoxia. (orig.)

  11. Untangling metabolic and spatial interactions of stress tolerance in plants. 2. Accelerated method for measuring and predicting stress tolerance. Can we unravel the mysteries of the interactions between photosynthesis and respiration?

    Science.gov (United States)

    Biel, Karl Y; Nishio, John N

    2010-09-01

    A simple method using the O(2) electrode that allows examination of the response of respiration and photosynthesis in leaf slices or algae to anoxia and high light under different temperatures useful for the examination of the interactions among photosynthesis, photorespiration, and respiration is described. The method provides a quantifiable assessment of stress tolerance that also permits us to examine fundamental biochemically and genetically related responses involved in stress tolerance and the cooperation among organelles. Additionally, we demonstrated a role for compounds, such as NO(-)(3) and oxaloacetate, as protective agents against photoinhibition, and we examined the role of dark adaptation in the activation of photosynthesis and NO(-)(3)-dependent O(2) oxygen evolution. A physiological and ecological role of a dark period (night) in stress tolerance is presented. Utilizing the method to follow changes in such metabolic activities as protein synthesis, protein conformation states, enzymes activity, carbon metabolism, and gene expression at different points during the treatments will be educational. PMID:20372947

  12. 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

    -carbonates (Fe-carb), iron-oxides (Fe-ox), magnetite (Fe-mag), and pyrite (FeP) was examined. Overall, the multi-proxy sedimentary geochemical data suggest that the succession containing pyritized trilobite beds was deposited under a dysoxic water-column, in agreement with the paleontological data. The data do...... 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...... favored where pore-waters were iron-dominated in sediments relatively poor in organic carbon....

  13. 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

  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. 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.

  16. Actinide partitioning to an acidic, sandy lake sediment

    International Nuclear Information System (INIS)

    Knowledge of the partitioning of actinides to sediments in natural systems is essential for modeling their environmental fate. Using two different sequential extraction methods, we have studied the partitioning of U and Pu to an acidic, sandy lake sediment that was contaminated due to nuclear production activities. We find that both methods yield similar partitioning information, and that much of the U is associated with insoluble phases, whereas the majority of the Pu is extracted with oxidizable phases, defined to be predominantly organic matter. Our study suggests that U in this ecosystem is of natural origin. Although Pu and Fe in this system are known to cycle from the sediments to the water column during periods of anoxia, only a low percentage of Pu is extracted from the phases that are reducible, which are operationally defined as amorphous Fe oxides. Although this sediment is low in organic matter, our results suggest that natural organics dominate the partitioning of Pu in this system. (orig.)

  17. 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.

  18. 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.

  19. 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

    observations of salt-water ingressions. The sediment record of the dated core is marked by seven Mn/Fe-excursions and suggests that major inflows terminating longer stagnation periods have occurred more frequently during the last 250 years. This in turn suggests the more frequent generation of low......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...

  20. 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

  1. [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

  2. Gold nanoparticle cellular uptake, toxicity and radiosensitisation in hypoxic conditions

    International Nuclear Information System (INIS)

    Background and purpose: Gold nanoparticles (GNPs) are novel agents that have been shown to cause radiosensitisation in vitro and in vivo. Tumour hypoxia is associated with radiation resistance and reduced survival in cancer patients. The interaction of GNPs with cells in hypoxia is explored. Materials and methods: GNP uptake, localization, toxicity and radiosensitisation were assessed in vitro under oxic and hypoxic conditions. Results: GNP cellular uptake was significantly lower under hypoxic than oxic conditions. A significant reduction in cell proliferation in hypoxic MDA-MB-231 breast cancer cells exposed to GNPs was observed. In these cells significant radiosensitisation occurred in normoxia and moderate hypoxia. However, in near anoxia no significant sensitisation occurred. Conclusions: GNP uptake occurred in hypoxic conditions, causing radiosensitisation in moderate, but not extreme hypoxia in a breast cancer cell line. These findings may be important for the development of GNPs for cancer therapy

  3. CT findings in neonatal hypothermia

    Energy Technology Data Exchange (ETDEWEB)

    Schulman, H.; Laufer, L.; Berginer, J.; Hertzanu, Y. [Department of Radiology, Soroka Medical Center, Faculty of Health Sciences, Ben-Gurion University of the Negev, P. O. Box 151, Beer-Sheva 84101 (Israel); Hershkowitz, E.; Berenstein, T.; Sofer, S. [Pediatric Intensive Care Unit, Soroka Medical Center, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva (Israel); Maor, E. [Department of Pathology, Soroka Medical Center, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva (Israel)

    1998-06-01

    Background. Newborn infants are particularly prone to hypothermia, a condition with a high mortality. Objective. To study the CT brain patterns in infants with hypothermia and neurological symptoms. Materials and methods. We reviewed the brain CT of nine infants with neonatal hypothermia, multiple organ failure, seizures and coma. Results. Two infants had normal CT scans, acutely and at follow-up, and were clinically normal at follow-up. In seven infants, CT showed diffuse cerebral oedema, with reversal of the normal density relationship between grey and white matter and a relative increased density of the thalami, brainstem and cerebellum - the `reversal sign`. In six surviving infants with severe developmental delay, follow-up CT revealed cerebral atrophy with multicystic encephalomalacia. Conclusions. The `reversal sign` has been described in the abused child, birth asphyxia and anoxia due to drowning. Neonatal hypothermia is offered as a further cause. (orig.) With 6 figs., 1 tab., 13 refs.

  4. Leucoencefalopatía hipóxica tardía Delayed Hypoxic Leukoencephalopathy

    Directory of Open Access Journals (Sweden)

    Pablo Sartori

    2012-06-01

    Full Text Available La Leucoencefalopatía Hipóxica Tardía (LHT es una enfermedad desmielinizante de infrecuente presentación. Se produce como consecuencia de un fenómeno de hipoxia-anoxia y aparece días o semanas más tarde.Los síntomas y cambios imagenológicos remiten casi totalmente y tienen un buen pronóstico En este reporte se ilustra el caso de una joven que desarrolló LHT luego de sufrir un paro cardiorrespiratorio.Delayed Hypoxic Leukoencephalopathy (DHL is a rare demyelinating disease. This condition occurs days or weeks after a hypoxic-anoxic injury. Symptoms and imaging changes almost fully resolve, with a good prognosis. We report the case of a young woman who developed DHL after a cardiopulmonary arrest.

  5. Interventional therapy of pulmonary arteriovenous malformation by using PDA or ASD occluder

    International Nuclear Information System (INIS)

    Objective: To evaluate the efficacy of transcatheter occlusion of pulmonary arteriovenous malformation (PAVM) by using PDA or ASD occluder. Methods: Five patients (one male and 4 females, aged 7-21 years) with angiographically proved PAVM were included, of which diffuse capillary pattern was seen in 2, multiple saccular pattern in 2 and single saccular pattern in one. Rather huge vascular sac and thick draining vessel were seen in all five patients. Using PDA or ASD occluder, all PAVMs were occluded by transcatheter technique. Results: Technical success was achieved in all cases. After the procedure the mean oxygen saturation was increased from 75.2% to 92.7%. The symptoms of anoxia were markedly improved, or even disappeared. No serious complications occurred. Conclusion: In the treatment of PAVM with interventional procedure, especially when the lesion carries huge vascular sac and thick feeding artery, the use of PDA or ASD occluder should take precedence over other considerations. (authors)

  6. Bone healing following irradiation during tourniquet ischaemia

    International Nuclear Information System (INIS)

    The bone harvest chamber (BHC) methodology, a titanium implant for quantitative evaluations of bone healing, was used in order to investigate the radioprotective function of anoxia, in healing bone tissue. After incorporation of one BHC in each proximal tibial metaphysis of a rabbit it was possible to collect newly formed bone specimens in 3-week-periods without animal sacrifice. The amount of bone was determined by microradiography and densitometry. Ten animals divided into 2 groups were used. One group receiving a single dose of 25 Gy during tourniquet ischaemia was compared with another receiving the same dose during normal blood perfusion. A significantly improved bone healing response was seen in the ischaemic group, with a tendency to further improvement with increasing time after irradiation. (orig.)

  7. Late Pliensbachian-early Toarcian paleoenvironmental changes in the Cleveland Basin: new clues from high-resolution trace element analysis

    DEFF Research Database (Denmark)

    Thibault, Nicolas Rudolph; Ruhl, Micha; Ullmann, Clemens Vinzenz;

    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...... elements across the late Pliensbachian to middle Toarcian of the Cleveland Basin. The Pl/To boundary CIE is associated with low Total Organic Carbon (TOC<2%), a high degree of pyritization (S/Fe) and enrichments in Cu, Zn and Ni, which together suggest that water-mass restriction and anoxia occurred in.......J., 2008. Basinal restriction, black shales, Re-Os dating, and the Early Toarcian (Jurassic) oceanic anoxic event. Paleoceanography 23, PA4217, doi: 10.1029/2008PA001607....

  8. 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

  9. Heterologous expression and purification of membrane-bound pyrophosphatases

    DEFF Research Database (Denmark)

    Kellosalo, J.; Kajander, T.; Palmgren, Michael Broberg;

    2011-01-01

    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...... 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 and...... at levels that would allow their purification for crystallization purposes. Highlights ¿ We have tested expression of eight membrane-bound pyrophosphatases in Saccharomyces cerevisiae. ¿ We have made functional T4-lysozyme-membrane-bound pyrophosphatase chimeras. ¿ We have purified membrane...

  10. In situ dynamics of O2, pH and cyanobacterial transcripts associated with CCM, photosynthesis and detoxification of ROS

    DEFF Research Database (Denmark)

    Jensen, Sheila I; Steunou, Anne-Soisig; Bhaya, Devaki;

    2011-01-01

    cycles, and was coupled with in situ determinations of incoming irradiance and microenvironmental dynamics of O(2) and pH. Fluctuations in pH and O(2) in the mats were largely driven by the diel cycle of solar irradiance, with a pH variation from ~7.0 to ~9.5, and O(2) levels ranging from anoxia to...... supersaturation during night and day, respectively. Levels of various transcripts from mat cyanobacteria revealed several patterns that correlated with incident irradiance, O(2) and pH within the mat matrix. Transcript abundances for most genes increased during the morning dark-light transition. Some transcripts...... remained at a near constant level throughout the light period, whereas others showed an additional increase in abundance as the mat underwent transition from low-to-high light (potentially reflecting changes in O(2) concentration and pH), followed by either a decreased abundance in the early afternoon, or...

  11. Nitric oxide availability in deeply hypoxic crucian carp

    DEFF Research Database (Denmark)

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

    2016-01-01

    order to decipher NO metabolites in plasma and several tissues. We also compared NO metabolite changes during acute (10 min) and chronic (1 day) exposures to three different O2 levels. Plasma [nitrite] decreased with decreasing [O2], while the cellular concentrations of nitrite and nitros......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...... 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 that the...

  12. 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

    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...

  13. Modelling shelf-ocean exchange and its biogeochemical consequences in coastal upwelling systems

    DEFF Research Database (Denmark)

    Muchamad, Al Azhar

    remineralization associated with nitrate reduction to nitrite. Secondly, the coupled model was used to simulate upwelling and iogeochemical cycles associated with different continental shelf geometries. In particular the generalized effect of shelf width was investigated. Anoxic/euxinic conditions in bottom waters...... active but cryptic sulfur cycle possibly is coupled to the nitrogen cycle in an oxygen-minimum-zone (OMZ), 2) what is the relation between the shelf–ocean exchange, continental shelf width and development of the observed bottom water anoxia/euxinia associated with different configurations of continental...... calibrated to reproduce the observed coupling between nitrogen and sulfur cycles in OMZ of the northern Chile upwelling systems. The model results show that sulfate reduction contribute significantly to organic matter remineralization in the OMZ water depths, along with nitrate reduction. In the model...

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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.)

  19. 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.

  20. Diagnostic value of glycocholic acid for intrahepatic cholestasis in pregnancy

    International Nuclear Information System (INIS)

    The content of glycocholic acid (CG) in pregnant women's sera is detected with CG radioimmunoassay (RIA). The content of CG in sera of normal pregnant women after 32 weeks is ascended slightly with the increasing of pregnant month. It is less than 7.0 μmol/l before 31 weeks in pregnancy and less than 9.4 μmol/l after 32 weeks. The serum CG content of patients with intrahepatic cholestasis in pregnancy (ICP) is increased by 100%. The CG value of about half patients appears earlier than pruritus and ALT rise, the earliest CG increasing appears in the 20th pregnant week. It is the most sensitive method for ICP early diagnosis. 136 cases of ICP patients are observed and the results show that the higher the CG content, the higher the rate of intrauterine fetal anoxia; therefore, the dynamic observation of CG content in ICP patients is a dependable objective for surveillance fetal prognosis

  1. 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

  2. Water quality dynamics in an urbanizing subtropical estuary(Oso Bay, Texas).

    Science.gov (United States)

    Wetz, Michael S; Hayes, Kenneth C; Fisher, Kelsey V B; Price, Lynn; Sterba-Boatwright, Blair

    2016-03-15

    Results are presented from a study of water quality dynamics in a shallow subtropical estuary, Oso Bay, Texas, which has a watershed that has undergone extensive urbanization in recent decades. High inorganic nutrient, dissolved organic matter and chlorophyll concentrations, as well as low pH (anoxia. The low oxygen and pH conditions are likely to impose significant stress on benthic organisms and nekton in the affected area. Signatures of eutrophied water were occasionally observed at the mouth of Oso Bay, suggesting that it may be exported to adjacent Corpus Christi Bay and contribute to seasonal hypoxia development in that system as well. These results argue for wastewater nutrient input reductions in order to alleviate the symptoms of eutrophication. PMID:26876558

  3. Physico-chemical and biological properties of Ambroxol under irradiation

    International Nuclear Information System (INIS)

    Physico-chemical properties of Ambroxol (AM), a potential antioxidant drug from the expectorant class, were investigated by radiation chemical and spectroscopic studies. The pulse radiolysis experiments showed that AM is a good scavenger of the primary water radical species, particularly eaq- and ·OH radicals. The ·OH attack, preferentially addressed to the ring positions activated by the -NH2 group and occupied by bromine atoms, leads to hydroxycyclohexadienyl radicals. The molecule stabilisation may be achieved by a dehalogenation reaction to give phenoxyl radicals. The ·OH attack to AM is not affected by Cu(II) ions, which interact only weakly with the drug as evidenced by IR and Raman spectroscopy. Survival experiments on E. coli B/r cells irradiated in the presence of AM showed a radiosensitising effect of AM in anoxia. Some possible mechanisms of radiosensitisation are outlined. (author)

  4. Lens Opacification in the Mouse - Implications for RBE and QF

    International Nuclear Information System (INIS)

    Extensive data collected on cataractogenesis in the mouse exposed to X-rays have established the following: (a) an increased incidence of lens opacities is seen following even small doses; (b) fractionation with a 12-hour interval between exposures decreases the degree of effect; (c) the same total doses given over two minutes or 100 minutes are equally effective ; (d) anoxia does not significantly alter radiosensitivity; and (e) hyperbaric oxygen appreciably increases radiosensitivity. Exposures to monoenergetic neutrons have demonstrated additionally that RBE values are relatively high; the values increase with decreasing neutron energy; the RBE increases appreciably with decreasing dose; and the values increase with decreasing ''dose-rate'', due to a rate- dependence of effect with X-rays. The difficulties of extrapolating these data to QF values applicable for radiation protection are discussed, and a possible approach to evaluating the significance of the data in this respect is outlined. (author)

  5. Hypoxia up-regulates mitochondrial genome-encoded transcripts in Arabidopsis roots.

    Science.gov (United States)

    Hameed, Muhammad Waqar

    2016-04-28

    Plants are frequently exposed to limitations in oxygen availability during their lifetime. During evolution, they have developed a number of physiological and morphological adaptations to tolerate oxygen and other stress conditions. These include regulation of growth by gene expression and ATP generation. The regulation of nuclear genes after hypoxia and anoxia is well studied; however, the regulation of mitochondrial genes in response to oxygen stress has not been characterized to date. Therefore, we have established an Arabidopsis mitochondrial genome-specific microarray that accommodates probes for all mitochondrial DNA-encoded genes and conserved open reading frames. Our analysis showed an up-regulation of mitochondrial transcripts in Arabidopsis roots after 48 h of hypoxia. Since no significant difference was detected in the expression of mitochondrial RNA polymerases or the mitochondrial DNA content per cell, we propose a transcriptional mode of induction of mitochondrial gene expression under hypoxia. PMID:27002184

  6. Kluver- Bucy syndrome - An experience with six cases

    Directory of Open Access Journals (Sweden)

    Jha Sanjeev

    2004-07-01

    Full Text Available The Kluver-Bucy syndrome (KBS is a neurobehavioral syndrome and can be seen in association with a variety of neurological disorders. Case records of 6 patients with KBS seen during a period of 5 years in a university hospital were reviewed. During the study period 6 patients with KBS, aged between 4 and 14 years, were seen. Hyperorality, hypersexuality, and abnormal behavior were the most common manifestations. Of the 6 patients, 5 had recurrent unprovoked seizures. The associated neurological disorders included anoxia-ischemic encephalopthy (2, herpes simplex encephalitis (1, neurocysticercosis (NCC (1, traumatic brain injury with gliosis (1 case and tuberculous meningitis (1 case. Prognosis was poor in all the patients except in the patient with NCC.

  7. CT findings in neonatal hypothermia

    International Nuclear Information System (INIS)

    Background. Newborn infants are particularly prone to hypothermia, a condition with a high mortality. Objective. To study the CT brain patterns in infants with hypothermia and neurological symptoms. Materials and methods. We reviewed the brain CT of nine infants with neonatal hypothermia, multiple organ failure, seizures and coma. Results. Two infants had normal CT scans, acutely and at follow-up, and were clinically normal at follow-up. In seven infants, CT showed diffuse cerebral oedema, with reversal of the normal density relationship between grey and white matter and a relative increased density of the thalami, brainstem and cerebellum - the 'reversal sign'. In six surviving infants with severe developmental delay, follow-up CT revealed cerebral atrophy with multicystic encephalomalacia. Conclusions. The 'reversal sign' has been described in the abused child, birth asphyxia and anoxia due to drowning. Neonatal hypothermia is offered as a further cause. (orig.)

  8. [Progress in research on obstructive sleep apnea syndrome].

    Science.gov (United States)

    Li, Jie; Xie, Jing; Jiang, Mao; Huang, Juanjuan; Yang, Tianlun

    2016-02-28

    Obstructive sleep apnea syndrome (OSAS) is a complicated chronic disease caused by certain reasons, characterized by obstruction of the upper airway and apnea or hypopnea during sleep, which can be followed by anoxia, snoring and daytime sleepiness. Recent studies have shown that hypertension is closely connected to OSAS. OSAS can lead to hypertension by several possible mechanisms. The diagnosis of OSAS mainly depends on the medical history, sign, polysomnogram (PSG) result and the frequency of apnea and hypopnea. OSAS can be relieved by continuous positive airway pressure (CPAP), oral orthodontic treatment, medicine, change of lifestyles and others. This brief review focuses on the mechanism of hypertension due to OSAS and the diagnosis criteria and treatment of OSAS. PMID:26932221

  9. Phospholipid fatty acids in mitochondria and microsomes of wheat and rice seedling roots during aeration and anaerobiosis

    International Nuclear Information System (INIS)

    Mitochondrial and microsomal fractions were isolated from the roots after residence of wheat and rice seedlings under conditions of aeration or anaerobiosis and used to determine the percentage ratio of phospholipid fatty acids (PFA), their content, and the rate of incorporation of [2-14C]-acetate into them. In rice mitochondria under anaerobic influence, the ratio of unsaturated to saturated PFA was higher than the level that occurred in the control plants and PFA content remained close to the control level throughout the entire course of exposure. On the other hand, these indices declined in wheat mitochondria and microsomes of both plants. Anoxia also powerfully inhibited incorporation of labelled acetate into PFA of both membrane fractions in wheat and rice seedlings alike. Probably indicating adaptive reorganizations in composition of the main groups of PFA and inhibition of their decomposition in rice mitochondria, the obtained data are discussed in relation to greater resistance to temporary anaerobiosis in rice as compared with wheat

  10. The Role of Oxidative Stress in the Pathogenesis of Spermatogenesis Disorders in Rats in Post-resuscitation Period

    Directory of Open Access Journals (Sweden)

    Shevantaeva O.N.

    2011-09-01

    Full Text Available The aim of the work is to study the condition of spermatogenesis and the mechanism of its disorders in an early post-resuscitation period. Materials and Methods. The study has been carried out on 52 white male non-pedigree rats, weighing 230—290 g. The terminal state was simulated by modeling acute hypobaric anoxia. There has been performed cytological examination of spermaries cells and assessed the activity of oxidative modification of proteins and lipid peroxidation. Results. The reduction of the number of all types of cells in spermary tissue was revealed. The leading pathogenic factor of post-resuscitation spermary cell damages in rats was stated to be excessive enhancement of lipid peroxidation processes and proteins oxidative modification.

  11. On an extremely dense bloom of the dinoflagellate Alexandrium tamarense in lagoons of the PO river delta: Impact on the environment

    Science.gov (United States)

    Sorokin, Yu. I.; Sorokin, P. Yu.; Ravagnan, G.

    1996-06-01

    An extremely dense bloom of the potentially toxic dinoflagellate Alexandrium tamarense was observed in the lagoons of Cà Pisani (Veneto, Italy) in summer 1993. The lagoons were experiencing a significant eutrophication impact, receiving waste waters from intensive fish culture plants. During their bloom dinoflagellates in the lagoons reached densities of 2 to 4 × 10 6 cells·dm -3 and a biomass of over 100 g·m -3. The bloom produced drastic ecological changes in the lagoons. It caused nocturnal anoxia, mortality of macrophytes and the build-up of labile organic matter in the water column. Grazing by the tintinnid Favella sp. contributed to the termination of the bloom of the flagellates. The results show that coastal aqua culture probably stimulates dinoflagellate blooms in shallow brackish lagoons.

  12. 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

  13. Jellyfish Lake, Palau

    Science.gov (United States)

    Burnett, William C.; Landing, William M.; Lyons, W. Berry; Orem, William

    Elemental cycling in suboxic to anoxic marine environments has received considerable attention in the past few years. The recent expeditions of the RIV Knorr to the Black Sea, for example, illustrate the interest in deciphering the geochemical processes active in such environments “Murray, 1988”.This interest has been stimulated by the recognition that the type of elemental cycling that occurs in restrictive basins such as the Black Sea also occurs in many other environments. Examples include hydrothermal systems, estuarine and marine sediments, and other water columns with restrictive circulation. In addition, evidence that widespread anoxia has occurred in oceans of the geologic past “Fischer and Arthur, 1977; Jenkyns, 1980” requires us to obtain a better understanding of geochemical processes under such conditions. We report here on preliminary geochemical measurements made in a stratified marine lake—an unusual, yet useful environment as an analog of an anoxic ocean.

  14. 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; 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...... anaerobic nitrate metabolism of the fungus Aspergillus terreus (isolate An-4) that was obtained from sediment in the seasonal oxygen minimum zone in the Arabian Sea, a globally important site of oceanic nitrogen loss and nitrous oxide emission. Results: Axenic incubations of An-4 in the presence and absence...... dissimilatory nitrate reduction when oxygen is absent. In the currently spreading oxygen-deficient zones in the ocean, an as yet unexplored diversity of fungi may recycle nitrate to ammonium and nitrite, the substrates of the major nitrogen loss process anaerobic ammonium oxidation, and the potent greenhouse...

  15. 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.

  16. 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

    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...... determining the content and distribution of O2. This complicates data interpretation and leads to speculative conclusions about which nitrogen transformation processes are responsible for N2O production. Using an O2-specific planar optode, this paper shows how spatiotemporal O2 dynamics can be used to...... interpret data on N2O emissions following a uniform or layered amendment of manure to agricultural soil. The spatial distribution of O2 and gas emission rates were monitored for 12 h. An anoxic layer formed rapidly around the layered manure, whereas the uniformly distributed manure led to a more widespread...

  17. Algal blooms and public health

    Energy Technology Data Exchange (ETDEWEB)

    Epstein, P.R. (Cambridge Hospital, MA (United States). Harvard Medical School)

    1993-06-01

    Alterations in coastal ecology are expanding the geographic extent, frequency, magnitude, and species complexity'' of algal blooms throughout the world, increasing the threat of fish and shellfish poisonings, anoxia in marine nurseries, and of cholera. The World Health Organization and members of the medical profession have described the potential health effects of global climate change. They warn of the consequences of increased ultraviolet-B (UV-B) rays and of warming: the possible damage to agriculture and nutrition, and the impact on habitats which may alter the distribution of vector-borne and water-based infectious diseases. Algal growth due to increased nitrogen (N) and phosphorus (P) and warming are already affecting marine microflora and aquatic plants; and there is now clear evidence that marine organisms are a reservoir for enteric pathogens. The pattern of cholera in the Western Hemisphere suggests that environmental changes have already begun to influence the epidemiology of this infectious disease. 106 refs.

  18. 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...... on eelgrass seedling performance. The covering of eelgrass shoots by algae decreases the light availability and may hamper the diffusive movement of oxygen, inorganic carbon and nutrients to and from the shoots. Moreover, the high productivity of the algae can result in large diurnal oxygen...... variations within 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...

  19. 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...

  20. 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

  1. 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

  2. [Prediction by means of endogenous and exogenous evoked potentials of the favorable evolution of a prolonged coma].

    Science.gov (United States)

    Michel, C; Denison, S; Minne, C; Guérit, J M

    1998-09-01

    A neurophysiological follow-up (EEG, exogenous and endogenous evoked potentials--EP) was performed over a 4-month period in a patient who presented a long-lasting coma following a cardiac arrest and an amniotic embolism. A pure anoxic aetiology was ruled out starting from the second day on the basis of a dissociation between mildly altered flash visual EP and markedly altered somatosensory EP, indicating focal brain-stem pathology. Endogenous EP reappeared after 12 days. This patient recovered consciousness after 51 days. Despite the absence of MRI abnormalities, we put forward the hypothesis that a brain-stem embolism had, in fact, worsened the clinical picture of an actually moderate anoxia. This case exemplifies the interest of an integrated neurophysiological approach (EEG, exogenous three-modality EP and endogenous EP) in the early evaluation of coma. It also illustrates the complement between structural imaging and functional assessment of the nervous system. PMID:9793066

  3. Linking iron and nitrogen cycles in lake sediment

    DEFF Research Database (Denmark)

    Robertson, Elizabeth; Thamdrup, Bo

    2013-01-01

    -Triassic (~252 Ma) boundaries, which coincide with Central Atlantic Magmatic Province (CAMP) and Siberian Trap volcanism, respectively. The Triassic-Jurassic mass extinction is often contributed to carbon release driven ocean acidification while the Permian-Triassic mass extinction is suggested to be related to...... widespread ocean anoxia. We compare Permian-Triassic and Triassic-Jurassic ocean redox change along continental margins in different geographic regions (Permian-Triassic: Greenland, Svalbard, Iran; Triassic-Jurassic: UK, Austria) and discuss its role in marine mass extinction. Speciation of iron [(FeHR/ Fe...... extinctions however shows 2 phases of euxinia along continental margins, with an initial short peak at the onset of volcanism followed by a shift to ferruginous conditions, possibly due to a strongly diminished ocean sulphate reservoir because of massive initial pyrite burial. D34Spyrite suggests that...

  4. 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

  5. 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

  6. AcEST: DK953437 [AcEST

    Lifescience Database Archive (English)

    Full Text Available |MOLR_ECOLI Putative molybdate metabolism regulator OS=... 30 5.7 sp|Q6CJ50|MDV1_KLULA Mitochondrial divisio...skeleton-regulatory complex prote... 31 4.3 sp|Q58880|Y1485_METJA Uncharacterized cation transport...NA helicase dbp8 OS=Neosarto... 30 7.4 sp|A7EKZ0|PAN1_SCLS1 Actin cytoskeleton-regulatory complex prote... 3...Sbjct: 166 PEAPAVKATVTAEAAPAKTV 185 >sp|Q72ER1|IF2_DESVH Translation initiation factor IF-2 OS=Desulfovibrio...on sp|Q9VGX3|FAU_DROME Protein anoxia up-regulated OS=Drosophila melanogaster Align length 98 Score (bit) 37.7 E-value 0.035 Report

  7. 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.

  8. 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

  9. Radiosensitivity of chlorella after medium energy accelerated electron irradiation

    International Nuclear Information System (INIS)

    The survival curves (capability of multiplication) of chlorella pyrenoidosa after irradiations can be used for soft electrons (0.65 and 1 MeV), hence penetrating into only 2 to 4 millimeters of water: the algae are laying on porous membranes and the doses are calculated from the power of the electron beam measured by the electric current on a metallic target or by Fricke's dosimetry. With these techniques, it is showed and discussed the part of anoxia in the radioprotection (magnitude or reduction of the dose calculated from the slope of survival curves: 2.5 ) that is more important than the restoration studied by the fractionation of the dose. The 0.65 and 1 MeV electrons have a biologic effect lesser than 180 keV X-rays (RBE - relative biological efficiency - calculated on the slope of survival curves is 0.92 in aerated irradiation, 0.56 in the deoxygenated irradiation). (author)

  10. 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

  11. 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

  12. Photosensitized damage to supercoiled plasmid DNA induced by 334-nm radiation in the presence of 2-thiouracil consists of alkali- and piperidine-labile sites as well as frank strand breaks

    International Nuclear Information System (INIS)

    A covalently closed, supercoiled plasmid was irradiated with 334-nm ultraviolet radiation in the presence of the naturally occurring photosensitizer 2-thiouracil (s2Ura). Irradiation of the plasmid in the absence of s2Ura induced small numbers of frank DNA strand breaks (FSB), alkali-labile sites (ALS), and piperidine-labile sites (PLS). The induction of each of these lesions was enhanced 30 times when s2Ura was present during aerobic irradiation. Anoxia, as well as the hydroxyl radical scavengers acetate and formate, inhibited the formation of all three lesion types. Hydrogen peroxide, γ-irradiation, and s2Ura photosensitization produced nearly identical damage proportions, with PLS: FSB ratios of 1.25:l, 0.78:1, and 0.84:1, respectively. Treatment with singlet oxygen produced a PLS:FSB ratio of 4.1:1. (author)

  13. 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.

  14. 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.

  15. Chemical protection of bacteria and cultured mammalian cells by sulfur-containing compounds

    International Nuclear Information System (INIS)

    Protection by sulfur-containing compounds was studied using bacteria E. coli Bsub(H) and cultured mouse leukemic cells, L 5178 Y, and the protective mechanisms were discussed. The dose reduction factors of non-sulfhydryl compounds observed in the bacteria were the same as those observed in mammalian cells, and the protective activity of these compounds was proportional to their reaction rates with hydroxyl radicals. On the other hand, sulfhydryl compounds, with the exception of glutathione, offered a much greater protection than was anticipated from their radical scavenging activity. From studies under anoxia, the protection of cysteine was explained by its OH scavenging and competition with oxygen. In addition, for MEA, protection against the direct action of radiation was suggested. This was supported by the significant protection in the frozen state. (author)

  16. Effect of electroconvulsive stimulation on morphological and physiological aspects of post-cardiac arrest cerebral microcirculation.

    Science.gov (United States)

    Sheleg, Sergey; Hixon, Hugh; Aizberg, Oleg R; Korotkevich, Alexander E; Nedzved, Mikhail K

    2008-09-01

    We investigated the effect of electroconvulsive stimulation (ECS) on cerebral circulation in vivo using the method for measuring microcirculation in real time with the photosensitizer dye Photosense and the fiber optic spectrofluorometer LESA-01-BIOSPEC. We have found that electroconvulsive stimulation significantly improved cerebral microcirculation (fourfold higher comparing to the control cerebral perfusion) after 30 min of room-temperature cardiac arrest. Morphologic study of the brain tissue showed the absence of rouleaux formation of erythrocytes ("sludged blood") in the cerebral cortex microcirculation after the application of electrical stimulus. Electroconvulsive stimulation may be useful for improving cerebral microcirculation (blood flow) in cases of long-term brain hypoxia/anoxia after prolonged cardiac arrest. PMID:18586374

  17. Oxygen-dependent sensitization of irradiated cells

    International Nuclear Information System (INIS)

    Attention is focused primarily on O2 effects in three biological systems, all tested in suspension: bacterial spores, vegetative bacterial cells, and mammalian cells. Information from these systems shows that O2 has more than one process through which it can act. Studies with bacterial spore suspensions provide clear evidence that multiple components to oxygen-dependent radiation sensitization exist. Studies with mammalian cell suspensions also show that at least two oxygen-dependent sensitization processes can be distinguished. Similar studies with vegetative bacteria in suspension have not resolved oxic sensitization into components. The roles of water-derived radicals in radiation sensitivity and, specifically, in sensitization by O2 were examined. OH radicals are clearly implicated in damage in all three biological test systems. However, the specific roles proposed for OH radicals are different in these organisms. In bacterial spores, OH radical removal in itself does not protect in anoxia or in high concentrations of O2. OH radical removal over a limited intermediate range of O2 concentrations will, however, protect. OH radical scavenging probably results in the formation of the actual protector. In bacteria, the supposition is that OH radical removal will protect both in anoxia and in the presence of O2. OH radicals probably react with a cellular target molecule and leave a radicalsite; this is the site which can then react with O2 to cause damage; DNA is the likely cellular target. In mammalian cells, a reaction scheme, similar to that proposed for bacteria, has been suggested for O2-dependent sensitization

  18. Evidence of a suffocation alarm system within the periaqueductal gray matter of the rat.

    Science.gov (United States)

    Schimitel, F G; de Almeida, G M; Pitol, D N; Armini, R S; Tufik, S; Schenberg, L C

    2012-01-01

    Dyspnea, hunger for air, and urge to flee are the cardinal symptoms of panic attacks. Patients also show baseline respiratory abnormalities and a higher rate of comorbid and antecedent respiratory diseases. Panic attacks are also precipitated by infusion of sodium lactate and inhalation of 5% CO₂ in predisposed patients but not in healthy volunteers or patients without panic disorder. Accordingly, Klein [Klein (1993) Arch Gen Psychiatry 50:306-317] suggested that clinical panic is the misfiring of an as-yet-unidentified suffocation alarm system. In rats, selective anoxia of chemoreceptor cells by potassium cyanide (KCN) and electrical and chemical stimulations of periaqueductal gray matter (PAG) produce defensive behaviors, which resemble panic attacks. Thus, here we examined the effects of single or combined administrations of CO₂ (8% and 13%) and KCN (10-80 μg, i.v.) on spontaneous and PAG-evoked behaviors of rats either intact or bearing electrolytic lesions of PAG. Exposure to CO₂ alone reduced grooming while increased exophthalmus, suggesting an arousal response to non-visual cues of environment. Unexpectedly, however, CO₂ attenuated PAG-evoked immobility, trotting, and galloping while facilitated defecation and micturition. Conversely, KCN produced all defensive behaviors of the rat and facilitated PAG-evoked trotting, galloping, and defecation. There were also facilitatory trends in PAG-evoked exophthalmus, immobility, and jumping. Moreover, whereas the KCN-evoked defensive behaviors were attenuated or even suppressed by discrete lesions of PAG, they were markedly facilitated by CO₂. Authors suggest that the PAG harbors an anoxia-sensitive suffocation alarm system which activation precipitates panic attacks and potentiates the subject responses to hypercapnia. PMID:22062132

  19. 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

  20. Oxygen dynamics and transport in the Mediterranean sponge Aplysina aerophoba.

    Science.gov (United States)

    Hoffmann, Friederike; Røy, Hans; Bayer, Kristina; Hentschel, Ute; Pfannkuchen, Martin; Brümmer, Franz; de Beer, Dirk

    2008-01-01

    The Mediterranean sponge Aplysina aerophoba kept in aquaria or cultivation tanks can stop pumping for several hours or even days. To investigate changes in the chemical microenvironments, we measured oxygen profiles over the surface and into the tissue of pumping and non-pumping A. aerophoba specimens with Clark-type oxygen microelectrodes (tip diameters 18-30 μm). Total oxygen consumption rates of whole sponges were measured in closed chambers. These rates were used to back-calculate the oxygen distribution in a finite-element model. Combining direct measurements with calculations of diffusive flux and modeling revealed that the tissue of non-pumping sponges turns anoxic within 15 min, with the exception of a 1 mm surface layer where oxygen intrudes due to molecular diffusion over the sponge surface. Molecular diffusion is the only transport mechanism for oxygen into non-pumping sponges, which allows total oxygen consumption rates of 6-12 μmol cm(-3) sponge day(-1). Sponges of different sizes had similar diffusional uptake rates, which is explained by their similar surface/volume ratios. In pumping sponges, oxygen consumption rates were between 22 and 37 μmol cm(-3) sponge day(-1), and the entire tissue was oxygenated. Combining different approaches of direct oxygen measurement in living sponges with a dynamic model, we can show that tissue anoxia is a direct function of the pumping behavior. The sponge-microbe system of A. aerophoba thus has the possibility to switch actively between aerobic and anaerobic metabolism by stopping the water flow for more than 15 min. These periods of anoxia will greatly influence physiological variety and activity of the sponge microbes. Detailed knowledge about the varying chemical microenvironments in sponges will help to develop protocols to cultivate sponge-associated microbial lineages and improve our understanding of the sponge-microbe-system. PMID:24391232

  1. 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

  2. Climate Variability and Relationship with Ocean Fertility during the Aptian

    Science.gov (United States)

    Bottini, C.; Erba, E.

    2014-12-01

    The late Barremian- Aptian time interval was marked by intense volcanic activity of the Greater Ontong Java Event (GOJE) and Kerguelen Plateau (KP) which induced a global perturbations in the ocean-atmosphere system including the early Aptian Oceanic Anoxic Event (OAE) 1a. Here, we present updated surface-water paleotemperature and fertility changes based on calcareous nannofossil records from the Tethys and Pacific Ocean. The detailed picture of climatic and ocean fertility variations during the Aptian, is discussed in relation to the role of volcanism. The pre-OAE 1a interval was characterized by relatively warm temperatures reaching a maximum in the early phase of anoxia under intense activity of the GOJE. Following accelerated weathering rates a short-lived (~35ky) cooling episode interrupted the major warming. Nannofossils indicate that mesotrophic conditions are associated with highest temperatures and GOJE volcanism. The last part of OAE 1a was characterized by cool snaps, probably promoted by CO2 sequestration via burial of organic matter (OM) under persistent igneous activity. The end of anoxia coincided with the cessation of volcanism and a marked cooling. Massive subaerial volcanism of the KP was associated with cool conditions during the late Aptian, implying the dominant effect of atmospheric CO2 drawdown via enhanced weathering, also promoting relatively high nutrient recycling. Lowest temperatures and low fertility, were reached across the interval marked by blooming of Nannoconus truittii. The almost exclusively submarine GOJE triggered greenhouse conditions during OAE 1a, whereas weathering and burial of OM acted as feedback processes favouring temporary cooler interludes. Extrusion of the subaerial KP was associated with prolonged cooling, indicating that, in a global context, weathering processes might have been relatively more important than CO2-induced warming.

  3. 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.

  4. 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.

  5. 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.

  6. Bacterioplankton and organic carbon dynamics in the lower mesohaline chesapeake bay.

    Science.gov (United States)

    Jonas, R B; Tuttle, J H

    1990-03-01

    The mesohaline portion of the Chesapeake Bay is subject to annual summertime hypoxia and anoxia in waters beneath the pycnocline. This dissolved oxygen deficit is directly related to salinity-based stratification of the water column in combination with high levels of autochthonously produced organic matter and a very high abundance of metabolically active bacteria. Throughout the water column in the lower, mesohaline part of the bay, between the Potomac and Rappahannock rivers, near the southern limit of the mainstem anoxia, bacterial abundance often exceeded 10 x 10 cells per ml and bacterial production exceeded 7 x 10 cells per liter per day during summer. Bacterial biomass averaged 34% (range, 16 to 126%) of the phytoplankton biomass in summer. These values are equal to or greater than those found farther north in the bay, where the oxygen deficit is more severe. Seasonal variations in bacterial abundance and production were correlated with phytoplankton biomass (lag time, 7 to 14 days), particulate organic carbon and nitrogen, and particulate biochemical oxygen demand in spring; but during summer, they were significantly correlated only with dissolved biochemical oxygen demand. During summer, dissolved biochemical oxygen demand can account for 50 to 60% of the total biochemical oxygen demand throughout the water column and 80% in the bottom waters. There is a clear spring-summer seasonal shift in the production of organic matter and in the coupling of bacteria and autochthonous organic matter. The measurement of dissolved, microbially labile organic matter concentrations is crucial in understanding the trophic dynamics of the lower mesohaline part of the bay. The absolute levels of organic matter in the water column and the bacterial-organic carbon relationships suggest that a lower bay source of organic matter fuels the upper mesohaline bay oxygen deficits. PMID:16348148

  7. 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.

  8. Differential contribution of key metabolic substrates and cellular oxygen in HIF signalling

    International Nuclear Information System (INIS)

    Changes in availability and utilisation of O2 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 O2. 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 O2 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 O2 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 O2 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

  9. ATM-dependent phosphorylation of 53BP1 in response to genomic stress in oxic and hypoxic cells

    International Nuclear Information System (INIS)

    The ATM kinase is activated by chromatin modification following exogenous and endogenous DSBs or cell stress, including acute anoxia. The p53 binding protein 1 (53BP1) contains multiple ATM-consensus phosphorylation sites in its N- and C-termini and may therefore be a distal read-out of ATM function. We have examined the cellular activation of these phosphorylation sites for the first time in situ following anoxic/hypoxic stress and IR-induced exogenous DSBs. We show that multiple residues of 53BP1 are phosphorylated and that these phosphoforms form discrete nuclear foci following IR or during DNA replication as exogenous or endogenous DNA double strand breaks (DSBs), respectively. Novel data pertaining to the phosphorylation of 53BP1Ser25in situ supports its dependency on the ATM kinase; but this occurs independently of p53 function. We show that 53BP1Ser25 is activated specifically in S-phase cells during anoxia in an ATM-dependent manner. Exogenous DSBs form discrete IR-induced foci whereas oxygen stress induced non-localized 53BP1Ser25 activation. Our in vitro data are supported by irradiated xenograft studies in vivo whereby 53BP1Ser25 phosphorylation does not occur in sub-regions positive for the hypoxia marker EF5. We propose a model whereby DSBs induce chromatin modification at sites of DNA damage which are tracked by the ATM substrates γ H2AX and 53BP1Ser25 in a mechanism distinct from p53-mediated cell cycle arrest. Together this work indicates 53BP1Ser25, and possibly other 53BP1 phosphoforms, as a bona fide DSB-biomarkers for surveying ongoing DNA-damage related signaling in oxic and hypoxic cells during clinical radiotherapy.

  10. 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.

  11. Significance of background activity and positive sharp waves in neonatal electroencephalogram as prognostic of cerebral palsy Valor do ritmo de base e da onda aguda positiva no eletrencefalograma neonatal como prognóstico da paralisia cerebral

    Directory of Open Access Journals (Sweden)

    Márcia de Oliveira Nicolini Nosralla

    2009-09-01

    Full Text Available OBJECTIVE: To study the significance of electroencephalographic background activity and positive sharp waves in neonatal electroencephalogram as prognostic of cerebral palsy. METHOD: We studied prospectively and sequentially 73 newborns who had severe neonatal complications (neonatal anoxia, seizures, respiratory distress, sepsis, and meningitis. Nineteen newborns were excluded and 54 children formed the object of our study and were followed for 2 years. We analyzed gestational age, conceptional age, electroencephalographic background activity and positive sharp waves, which were correlated with cerebral palsy. RESULTS: There were no statistically significant correlation between gestational age and conceptional age and cerebral palsy; the electroencephalographic background activity was correlated with cerebral palsy as well as the positive sharp waves. CONCLUSION: Children with electroencephalographic background activity markedly abnormal and accompanied by positive sharp waves were associated with a worse prognosis.OBJETIVO: Estudar o valor do ritmo de base e das ondas agudas positivas no eletrencefalograma neonatal como prognóstico da paralisia cerebral. MÉTODO: Nós estudamos, prospectiva e sequencialmente, 73 recém-nascidos que apresentaram complicações neonatais graves (anoxia neonatal, crises convulsivas, desconforto respiratório, septicemia e meningite. Dezenove recém-nascidos foram excluídos e 54 crianças formaram o objeto do nosso estudo e foram seguidas por 2 anos. Nós analisamos a idade gestacional, a idade corrigida, o ritmo de base e as ondas agudas positivas, que foram correlacionadas com a paralisia cerebral. RESULTADOS: Não houve correlação estatisticamente significante entre as idades gestacional e corrigida com a paralisia cerebral; o ritmo de base foi correlacionado com a paralisia cerebral, tanto quanto as ondas agudas positivas. CONCLUSÃO: Crianças com o eletrencefalograma com o ritmo de base marcadamente

  12. 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

  13. The creatine transporter mediates the uptake of creatine by brain tissue, but not the uptake of two creatine-derived compounds.

    Science.gov (United States)

    Lunardi, G; Parodi, A; Perasso, L; Pohvozcheva, A V; Scarrone, S; Adriano, E; Florio, T; Gandolfo, C; Cupello, A; Burov, S V; Balestrino, M

    2006-11-01

    Hereditary creatine transporter deficiency causes brain damage, despite the brain having the enzymes to synthesize creatine. Such damage occurring despite an endogenous synthesis is not easily explained. This condition is incurable, because creatine may not be delivered to the brain without its transporter. Creatine-derived compounds that crossed the blood-brain barrier in a transporter-independent fashion would be useful in the therapy of hereditary creatine transporter deficiency, and possibly also in neuroprotection against brain anoxia or ischemia. We tested the double hypothesis that: (1) the creatine carrier is needed to make creatine cross the plasma membrane of brain cells and (2) creatine-derived molecules may cross this plasma membrane independently of the creatine carrier. In in vitro mouse hippocampal slices, incubation with creatine increased creatine and phosphocreatine content of the tissue. Inhibition of the creatine transporter with 3-guanidinopropionic acid (GPA) dose-dependently prevented this increase. Incubation with creatine benzyl ester (CrOBzl) or phosphocreatine-Mg-complex acetate (PCr-Mg-CPLX) increased tissue creatine content, not phosphocreatine. This increase was not prevented by GPA. Thus, the creatine transporter is required for creatine uptake through the plasma membrane. Since there is a strong indication that creatine in the brain is mainly synthesized by glial cells and transferred to neurons, this might explain why hereditary transporter deficiency is attended by severe brain damage despite the possibility of an endogenous synthesis. CrOBzl and PCr-Mg-CPLX cross the plasma membrane in a transporter-independent way, and might be useful in the therapy of hereditary creatine transporter deficiency. They may also prove useful in the therapy of brain anoxia or ischemia. PMID:16949212

  14. 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

  15. 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

  16. 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.

  17. Effects of severe oxygen depletion on macrobenthos in the Pomeranian Bay (southern Baltic Sea): a case study in a shallow, sublittoral habitat characterised by low species richness

    Science.gov (United States)

    Powilleit, Martin; Kube, Jan

    1999-11-01

    Severe oxygen depletion was detected in shallow parts of the Pomeranian Bay (southern Baltic Sea) for the first time in July/August 1994. A combination of extraordinary meteorological and hydrographical conditions along with generally high nutrient loads in this coastal area is thought to have led to extensive hypoxia/anoxia. Effects of this event on the macrobenthos were studied by comparing the community structure before and after summer 1994 at four sites which differed in degree of oxygen deficiency. Observed changes in the macrobenthos at three stations were attributed mainly to the hypoxia/anoxia event in summer 1994. Macrobenthos recovery after the oxygen depletion did not follow the commonly described succession pattern after a disturbance event, which is characterised by a mass recruitment of opportunistic species together with a rapid species turnover. At station 2, the most severely affected site, species number, total abundance, and total biomass of macrobenthos decreased significantly after the oxygen deficiency event, and recolonisation was still not complete two years later. Stations 1 and 3, which were moderately affected, showed almost complete recovery with respect to species composition and abundance within two years, but biomass was still lower. While recolonisation by juvenile and adult stages from nearby unimpacted coastal areas occurred at stations 1 and 3, succession was dominated by post-larval colonisation from planktonic dispersal at station 2. Station 4 was not affected by oxygen depletion and showed only small variation of community structure. The generally very slow recovery of amphipods at all three affected stations and even of the oligochaetes ( Tubificoides ( Peloscolex) benedeni and Heterochaeta ( Tubifex) costata) at station 2 further underline the severity of this oxygen deficiency in Pomeranian Bay sediments.

  18. Paleoxigenación subsuperficial de la columna de agua en la bahía Mejillones del sur (23oS: Indicadores geoquímicos en testigos de sedimento marino Subsuperficial paleoxygenation in the water colum at Mejillones del sur bay (23ºS: Geochemical indicators in marine sediment cores

    Directory of Open Access Journals (Sweden)

    Jorge Valdés

    2001-01-01

    Full Text Available RESUMEN. Se utilizaron mediciones de cadmio y molibdeno en dos testigos de sedimento marino para reconstruir la oxigenación de las aguas subsuperficiales en la bahía Mejillones del sur (norte de Chile, durante el pasado reciente. Condiciones anóxicas/hipóxicas en el fondo de la bahía permiten considerar que uno de los principales procesos de incorporación de Cd y Mo a los sedimentos es la formación de compuestos insolubles en el agua adyacente al piso marino. Así, las variaciones de la concentración observadas a lo largo de dos testigos que abarcaron los pasados 3000 años, representarían cambios en la oxigenación de las aguas subsuperficiales. La estructura laminada de los testigos y concentraciones de Cd (media = 34 ppm y Mo (media = 50 ppm elevadas indican que el ambiente de fondo de la bahía se ha caracterizado, durante los últimos tres milenios, por presentar niveles de oxígeno muy bajos, mientras que las fluctuaciones de la concentración a lo largo de los testigos se interpretan como cambios en la oxigenación de fondo, dentro de una condición de hipoxia/anoxia. En general, se ha producido una intensificación de condición de mínimo oxígeno hacia el presente. Una buena correlación entre los estratos oscuros identificados en ambos testigos y el aumento de la concentración de Cd y Mo permite indicar que estos estratos representarían periodos en que el fondo de la bahía se caracterizó por presentar condiciones reforzadas de hipoxia/anoxia. Se propone que estos cambios habrían sido provocados por variaciones en la circulación de la bahía y/o intensidad de la surgenciaABSTRACT. Variations in cadmium and molybdenum content along two marine cores were used to reconstruct former oxygen abundance in subsuperficial water in Mejillones Bay (northern Chile, in a recent past. Particular hypoxic/anoxic conditions met at the bottom of this embayment, may have permitted Cd and Mo to be incorporated in the sediments, directly

  19. 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

  20. 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