Phototoxicity and oxidative stress responses in Daphnia magna under exposure to sulfathiazole and environmental level ultraviolet B irradiation

International Nuclear Information System (INIS)

Kim, Jungkon; Park, Yena; Choi, Kyungho

2009-01-01

Sulfonamide antibiotics frequently occur in aquatic environments. In this study, phototoxicity of sulfathiazole (STZ) and its mechanism of action were investigated using Daphnia magna. We evaluated the changes of molecular level stress responses by assessing gene expression, enzyme induction and lipid peroxidation, and the related organism-level effects in D. magna. In the presence of ultraviolet B (UV-B) light (continuous irradiation with 13.8 ± 1.0 μW cm -2 d -1 ), STZ (at the nominal concentration of 94.9 mg/L) caused a significant increase in reactive oxygen species (ROS) generation and lipid peroxidation. Catalase (CAT) and glutathione S-transferase (GST) showed concentration-dependent increases caused by the exposure. Exposure to STZ and UV-B light caused apparent up-regulation of α-esterase, hemoglobin, and vitellogenin mRNA. The survival of daphnids was significantly affected by the co-exposure to STZ and UV-B. The biochemical and molecular level observations in combination with organism-level effects suggest that the phototoxicity of STZ was mediated in part by ROS generated by oxidative stress in D. magna

Ramon Llull's Ars Magna

DEFF Research Database (Denmark)

Jensen, Thessa

2018-01-01

The Ars Magna of Ramon Llull must be seen as one of the first attempts to formalise language, thought processes, and creating a basis for rational discussions. It consists of so-called principles, concepts, which are defined and combined through the use of four main figures. Llull's contribution...

Body posture modulates action perception.

Science.gov (United States)

Zimmermann, Marius; Toni, Ivan; de Lange, Floris P

2013-04-03

Recent studies have highlighted cognitive and neural similarities between planning and perceiving actions. Given that action planning involves a simulation of potential action plans that depends on the actor's body posture, we reasoned that perceiving actions may also be influenced by one's body posture. Here, we test whether and how this influence occurs by measuring behavioral and cerebral (fMRI) responses in human participants predicting goals of observed actions, while manipulating postural congruency between their own body posture and postures of the observed agents. Behaviorally, predicting action goals is facilitated when the body posture of the observer matches the posture achieved by the observed agent at the end of his action (action's goal posture). Cerebrally, this perceptual postural congruency effect modulates activity in a portion of the left intraparietal sulcus that has previously been shown to be involved in updating neural representations of one's own limb posture during action planning. This intraparietal area showed stronger responses when the goal posture of the observed action did not match the current body posture of the observer. These results add two novel elements to the notion that perceiving actions relies on the same predictive mechanism as planning actions. First, the predictions implemented by this mechanism are based on the current physical configuration of the body. Second, during both action planning and action observation, these predictions pertain to the goal state of the action.

Long-term effects to ionizing radiation in crustacean Daphnia magna

International Nuclear Information System (INIS)

Sarapul'tseva, E.I.

2016-01-01

The results of this study have provided strong evidence for the trans generational effects of parental exposure to ionizing radiation in crustacean Daphnia magna. To establish whether parental irradiation can affect the survival, life span and fertility of directly exposed organisms and their non-exposed offspring, D. magna were given 10, 100, 1000 and 10,000 mGy of acute γ-rays. MTT-assay was first applied for the investigation in vivo of the mechanisms of trans generational low doses effects of radiation and development of stress in Daphnia. Our dates strongly support MTT assay results as a good bio marker of survival and fertility effects at D. magna. (authors)

Toxicity of three strobilurins (kresoxim-methyl, pyraclostrobin, and trifloxystrobin) on Daphnia magna.

Science.gov (United States)

Cui, Feng; Chai, Tingting; Liu, Xiaoxu; Wang, Chengju

2017-01-01

Strobilurins constitute a new class of fungicides that is the most widely used in the world. The present study was conducted to investigate the aquatic toxicity of 3 common strobilurin fungicides (kresoxim-methyl, pyraclostrobin, and trifloxystrobin) to Daphnia magna. The neonate acute immobilization test showed that the 48-h 50% effective concentration (EC50) values of kresoxim-methyl, pyraclostrobin, and trifloxystrobin were 443.3 µg/L, 20.9 µg/L, and 23.0 µg/L, respectively. In addition, the 3 strobilurins significantly induced activity of the important detoxification enzyme glutathione S-transferase (GST) in D. magna, and there was a significant positive relationship between GST activity and immobility of D. magna after acute exposure. The 3 strobilurins showed higher toxicity to D. magna embryos, and the 48-h EC50 were 157.3 µg/L, 3.9 µg/L, and 1.7 µg/L for kresoxim-methyl, pyraclostrobin, and trifloxystrobin, respectively. The 21-d chronic test revealed that the strobilurins could also significantly affect the reproduction, development, and growth of D. magna at sublethal concentrations. The lowest-observed-effect concentrations of kresoxim-methyl, pyraclostrobin, and trifloxystrobin for reproduction were 20 µg/L, 0.15 µg/L, and 0.2 µg/L, respectively, which were close to environmental concentrations. The findings indicate that strobilurin fungicides are very toxic to D. magna and they are sufficient to cause harm to D. magna at environmentally relevant concentrations. Environ Toxicol Chem 2017;36:182-189. © 2016 SETAC. © 2016 SETAC.

Magna-field irradiation: physical considerations

Energy Technology Data Exchange (ETDEWEB)

Van Dyk, J.

1983-12-01

Magna-field radiotherapy in the form of total body, half body and total nodal irradiation is becoming increasingly prominent and involves dosimetric problems that are much more pronounced than they are for conventional field sizes. In this review of the physical considerations of magna-field irradiation, a number of possible alternate methods of producing large radiation fields are outlined, the basic beam dosimetry is reviewed and the factors producing dose variation in the patient are considered. Since the lung contains large regions of low density tissues and has a lower tolerance to radiaiton than most other tissues, special consideration is given to methods of dose determination and dose reduction to this organ. The question of accuracy in dose delivery is briefly discussed and the concept of delivering a radiation dose 'as precisely as readily achievable (APARA), technological and biological factors being taken into account' is introduced.

Fossa navicularis magna detection on cone-beam computed tomography

Energy Technology Data Exchange (ETDEWEB)

Syed, Ali Z. [Dept. of Oral and Maxillofacial Medicine and Diagnostic Sciences, School of Dental Medicine, Case Western Reserve University, Cleveland(United States); Mupparapu, Mel [Div. of Radiology, University of Pennsylvania School of Dental Medicine, Philadelphia (United States)

2016-03-15

Herein, we report and discuss the detection of fossa navicularis magna, a close radiographic anatomic variant of canalis basilaris medianus of the basiocciput, as an incidental finding in cone-beam computed tomography (CBCT) imaging. The CBCT data of the patients in question were referred for the evaluation of implant sites and to rule out pathology in the maxilla and mandible. CBCT analysis showed osseous, notch-like defects on the inferior aspect of the clivus in all four cases. The appearance of fossa navicularis magna varied among the cases. In some, it was completely within the basiocciput and mimicked a small rounded, corticated, lytic defect, whereas it appeared as a notch in others. Fossa navicularis magna is an anatomical variant that occurs on the inferior aspect of the clivus. The pertinent literature on the anatomical variations occurring in this region was reviewed.

Interspecific differences between D. pulex and D. magna in tolerance to cyanobacteria with protease inhibitors.

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Christian J Kuster

Full Text Available It is known that cyanobacteria negatively affect herbivores due to their production of toxins such as protease inhibitors. In the present study we investigated potential interspecific differences between two major herbivores, Daphnia magna and Daphnia pulex, in terms of their tolerance to cyanobacteria with protease inhibitors. Seven clones each of D. magna and of D. pulex were isolated from different habitats in Europe and North America. To test for interspecific differences in the daphnids' tolerance to cyanobacteria, their somatic and population growth rates were determined for each D. magna and D. pulex clone after exposure to varying concentrations of two Microcystis aeruginosa strains. The M. aeruginosa strains NIVA and PCC(- contained either chymotrypsin or trypsin inhibitors, but no microcystins. Mean somatic and population growth rates on a diet with 20% NIVA were significantly more reduced in D. pulex than in D. magna. On a diet with 10% PCC(-, the population growth of D. pulex was significantly more reduced than that of D. magna. This indicates that D. magna is more tolerant to cyanobacteria with protease inhibitors than D. pulex. The reduction of growth rates was possibly caused by an interference of cyanobacterial inhibitors with proteases in the gut of Daphnia, as many other conceivable factors, which might have been able to explain the reduced growth, could be excluded as causal factors. Protease assays revealed that the sensitivities of chymotrypsins and trypsins to cyanobacterial protease inhibitors did not differ between D. magna and D. pulex. However, D. magna exhibited a 2.3-fold higher specific chymotrypsin activity than D. pulex, which explains the observed higher tolerance to cyanobacterial protease inhibitors of D. magna. The present study suggests that D. magna may control the development of cyanobacterial blooms more efficiently than D. pulex due to differences in their tolerance to cyanobacteria with protease

Absceso mamario no puerperal por Finegoldia magna Nonpuerperal breast abscess caused by Finegoldia magna

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L. Castello

2007-06-01

Full Text Available Finegoldia magna son cocos gram-positivos anaerobios estrictos, cuyas células se disponen en pares, tétradas y acúmulos. Forman parte de la flora normal de la piel, tractos gastrointestinal y genitourinario femeninos, y cavidad oral. La especie se caracteriza por ser asacarolítica y su principal fuente de energía la constituyen aminoácidos y peptonas. Por lo general se la aísla en cultivos polimicrobianos a partir de abscesos y otras infecciones de piel y partes blandas, huesos y articulaciones. En el caso descrito, F. magna fue recuperada en cultivo monomicrobiano, a partir de un absceso mamario no puerperal, que se agrega a los dos casos comunicados en la literatura. La identificación se realizó mediante la determinación de la sensibilidad a los discos de potencia especial, pruebas convencionales, y producción de enzimas sacarolíticas y proteol��ticas. Se efectuó la prueba de sensibilidad a los antimicrobianos por el método epsilométrico. Los agentes ensayados y los valores de CIM (µg/ml obtenidos fueron: penicilina, 0,064; cefalotina, 1; metronidazol, 0,25; minociclina, Finegoldia magna is a species of strictly anaerobic gram-positive cocci, arranged in pairs, tetrads, and clusters. These organisms are components of the normal flora of the skin, gastrointestinal and genitourinary female tracts, and oral cavity. They are asaccharolytic and their major energy sources are aminoacids and peptones. The species is usually isolated in polymicrobial cultures from abscesses, soft tissue infections, bone and joints. In the case herein presented, F. magna was recovered in pure culture from a nonpuerperal breast abscess, which adds to the two reported cases in related literature. Species identification was performed by special potency disks, standard bacteriological anaerobic tests, and production of saccharolytic and proteolytic enzymes. Antimicrobial susceptibility testing was performed by using the epsilometric test. The agents

Modulating action duration to establish non-conventional communication

DEFF Research Database (Denmark)

Vesper, Cordula; Schmitz, Laura; Knoblich, Günther

2017-01-01

communication. The current study investigated whether systematic modulations of action duration provide a sufficient basis for communication. The results of three experiments demonstrate that knowledgeable actors spontaneously and systematically adjusted the duration of their actions to communicate task...

Accumulation of dieldrin in an alga (Scenedesmus obliquus), Daphnia magna, and the guppy (Poecilia reticulata)

Science.gov (United States)

Reinert, Robert E.

1972-01-01

Scenedesmus obliquus, Daphnia magna, and Poecilia reticulata accumulated dieldrin directly from water; average concentration factors (concentration in organism, dry weight, divided by concentration in water) were 1282 for the alga, 13,954 for D. magna, and 49,307 (estimated) for the guppy. The amount accumulated by each species at equilibrium (after about 1.5, 3-4, and 18 days, respectively) was directly proportional to the concentration of dieldrin in the water. Daphnia magna and guppies accumulated more dieldrin from water than from food that had been exposed to similar concentrations in water. When guppies were fed equal daily rations of D. magna containing different concentrations of insecticide, the amounts of dieldrin accumulated by the fish were directly proportional to the concentration in D. magna; when two lots of guppies were fed different quantities of D. magna (10 and 20 organisms per day) containing identical concentrations of dieldrin, however, the amounts accumulated did not differ substantially.

In-vitro antioxidant activity of crataeva magna lour. dc bark extract

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Sridhar N

2012-10-01

Full Text Available The plant Crataeva magna belonging to family Capparaceae is used in anti spasmodic, hypotensive, anti-inflammatory, hypoglycemic, anti protozoal, analgesic purposes. The present study was carried out to evaluate appropriate animal model. The antioxidative potential of different solvent extracts of Crataeva magna were evaluated using 1,1-Diphenyl-2-Picrylhydrazyl (DPPH, 2,2 ’-Azino-Bis(3-ethylbenzthiazoline-6-Sulphonic acid (ABTS, superoxide radical, hydroxyl radical, nitric oxide radical scavenging activities and lipid peroxidation inhibition assay. Among those solvent extracts, ethanolic extract of C. magna exhibited highest level of antioxidant activities. The ethanolic extract also inhibited H 2O2 mediated haemolysis and lipid peroxidation in human RBC.

The complete mitochondrial genome sequence of Eimeria magna (Apicomplexa: Coccidia).

Science.gov (United States)

Tian, Si-Qin; Cui, Ping; Fang, Su-Fang; Liu, Guo-Hua; Wang, Chun-Ren; Zhu, Xing-Quan

2015-01-01

In the present study, we determined the complete mitochondrial DNA (mtDNA) sequence of Eimeria magna from rabbits for the first time, and compared its gene contents and genome organizations with that of seven Eimeria spp. from domestic chickens. The size of the complete mt genome sequence of E. magna is 6249 bp, which consists of 3 protein-coding genes (cytb, cox1 and cox3), 12 gene fragments for the large subunit (LSU) rRNA, and 7 gene fragments for the small subunit (SSU) rRNA, without transfer RNA genes, in accordance with that of Eimeria spp. from chickens. The putative direction of translation for three genes (cytb, cox1 and cox3) was the same as those of Eimeria species from domestic chickens. The content of A + T is 65.16% for E. magna mt genome (29.73% A, 35.43% T, 17.09 G and 17.75% C). The E. magna mt genome sequence provides novel mtDNA markers for studying the molecular epidemiology and population genetics of Eimeria spp. and has implications for the molecular diagnosis and control of rabbit coccidiosis.

Medical-biological aspects of radiation effects in Daphnia magna

International Nuclear Information System (INIS)

Sarapultseva, E; Ustenko, K; Uskalova, D; Savina, N

2017-01-01

We have shown that γ-irradiation at doses of 100 and 1000 mGy significantly compromised fecundity and reproductive success of the directly exposed D. magna . These effects were also observed among the non-exposed first-generation progeny of irradiated parents, thus implying the manifestation of transgenerational effects in Daphnia . We have also shown that compromised viability of irradiated D. magna can be attributed cytotoxic effects of irradiation. It would therefore appear that the compromised viability may be attributed to the cytotoxic effects resulted from epigenetic changes affecting some metabolic pathways involved in detoxification of free-radicals. Additionally we have analyzed more distant progeny of irradiated at doses of 10, 100 and 1000 mGy Daphnia . Our data demonstrated that multicellular crustacean D. magna represent a very useful experimental model for analyse of long-term effects of ionising radiation at the organismal level. (paper)

Multigenerational cadmium acclimation and biokinetics in Daphnia magna

International Nuclear Information System (INIS)

Guan Rui; Wang Wenxiong

2006-01-01

A Cd exposure (3 μg L -1 ) experiment was conducted for six successive generations to investigate the responses to chronic Cd stress in Daphnia magna. We observed a biphasic accumulation of Cd in the six generations and suggested a similar pattern with respect to daphnids' tolerance. Cd assimilation efficiencies, daphnid growth, and reproduction corresponded to the changes of tolerance, which was partially accounted for by metallothionein induction. When maternally exposed neonates grew in Cd-free water for one or two generations, their growth, MT concentration and biokinetic parameters partially or totally recovered. The rapid recovery suggests the high potential for ecological restoration from Cd pollution. Our results indicate that the tolerance of sensitive D. magna clones to Cd was dependent on long-term or multigenerational exposure. The tolerance developed within the first several generations might not be maintained, and the animals may become even more sensitive to Cd stress in subsequent generations. - Tolerance of sensitive Daphnia magna clones to cadmium was dependent on long-term or multigenerational exposure

Comparative ovarian microarray analysis of juvenile hormone-responsive genes in water flea Daphnia magna: potential targets for toxicity.

Science.gov (United States)

Toyota, Kenji; Williams, Timothy D; Sato, Tomomi; Tatarazako, Norihisa; Iguchi, Taisen

2017-03-01

The freshwater zooplankton Daphnia magna has been extensively employed in chemical toxicity tests such as OECD Test Guidelines 202 and 211. Previously, it has been demonstrated that the treatment of juvenile hormones (JHs) or their analogues to female daphnids can induce male offspring production. Based on this finding, a rapid screening method for detection of chemicals with JH-activity was recently developed using adult D. magna. This screening system determines whether a chemical has JH-activity by investigating the male offspring inducibility. Although this is an efficient high-throughput short-term screening system, much remains to be discovered about JH-responsive pathways in the ovary, and whether different JH-activators act via the same mechanism. JH-responsive genes in the ovary including developing oocytes are still largely undescribed. Here, we conducted comparative microarray analyses using ovaries from Daphnia magna treated with fenoxycarb (Fx; artificial JH agonist) or methyl farnesoate (MF; a putative innate JH in daphnids) to elucidate responses to JH agonists in the ovary, including developing oocytes, at a JH-sensitive period for male sex determination. We demonstrate that induction of hemoglobin genes is a well-conserved response to JH even in the ovary, and a potential adverse effect of JH agonist is suppression of vitellogenin gene expression, that might cause reduction of offspring number. This is the first report demonstrating different transcriptomics profiles from MF and an artificial JH agonist in D. magna ovary, improving understanding the tissue-specific mode-of-action of JH. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Effect of an Aspartame-Ethanol Mixture on Daphnia magna Cardiac Activity

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Rebecca Kohn

2009-01-01

Full Text Available Aspartame in conjunction with alcohol has been shown to increase the blood alcohol level in humans faster than alcohol and sucrose (Wu et al., 2006. To determine the potential effects of various mixtures of ethanol and aspartame on the nervous system, the heart rate of Daphnia magna (D.magna, water flea was measured in deionized water (control, ethanol, aspartame, and five different mixtures of ethanol and aspartame. The heart rate was chosen as a representative measure since it is controlled by the nervous system and the heart rate of D.magna can easily be measured. The results were statistically evaluated by student’s t-test. A significant increase in heart rate was observed for all mixed assays compared to both control and ethanol, but not to aspartame. The data suggests that the aspartame and alcohol mixture have a greater effect on D. magna heart rate than water or ethanol, but not aspartame alone. We propose that alcohol in combination with aspartame has potentially detrimental consequences for the nervous system.

Multigenerational contaminant exposures produce non-monotonic, transgenerational responses in Daphnia magna

International Nuclear Information System (INIS)

Kimberly, David A.; Salice, Christopher J.

2015-01-01

Generally, ecotoxicologists rely on short-term tests that assume populations to be static. Conversely, natural populations may be exposed to the same stressors for many generations, which can alter tolerance to the same (or other) stressors. The objective of this study was to improve our understanding of how multigenerational stressors alter life history traits and stressor tolerance. After continuously exposing Daphnia magna to cadmium for 120 days, we assessed life history traits and conducted a challenge at higher temperature and cadmium concentrations. Predictably, individuals exposed to cadmium showed an overall decrease in reproductive output compared to controls. Interestingly, control D. magna were the most cadmium tolerant to novel cadmium, followed by those exposed to high cadmium. Our data suggest that long-term exposure to cadmium alter tolerance traits in a non-monotonic way. Because we observed effects after one-generation removal from cadmium, transgenerational effects may be possible as a result of multigenerational exposure. - Highlights: • Daphnia magna exposed to cadmium for 120 days. • D. magna exposed to cadmium had decreased reproductive output. • Control D. magna were most cadmium tolerant to novel cadmium stress. • Long-term exposure to cadmium alter tolerance traits in a non-monotonic way. • Transgenerational effects observed as a result of multigenerational exposure. - Adverse effects of long-term cadmium exposure persist into cadmium free conditions, as seen by non-monotonic responses when exposed to novel stress one generation removed.

Trans-generational effects induced by alpha and gamma ionizing radiations at Daphnia magna

International Nuclear Information System (INIS)

Parisot, Florian

2015-01-01

Anthropogenic activities related to the nuclear industry contribute to continuous discharges of radionuclides into terrestrial and aquatic ecosystems. Over the past decades, the ecological risk of ionizing radiation has become a growing public, regulatory and scientific concern for ecosystems protection. Until recently, only few studies focus on exposure situations at low doses of irradiation, although these situations are representative of realistic environmental conditions. Understanding how ionizing radiation affects species over several generations and at various levels of biological organization is a major research goal in radioecology. The aim of this PhD was to bring new knowledge on the effects of ionizing radiation during a multi-generational expose of the aquatic invertebrate, Daphnia magna. A two-step strategy was implemented. First, an external gamma radiation at environmentally relevant dose rates was performed on D. magna over three successive generations (F0, F1 and F2). The objective of this experiment was to examine whether low dose rates of radiation induced increasing effects on survival, growth and reproduction of daphnids over generations and to test a possible accumulation and transmission of DNA alterations from adults to offspring. Results showed an accumulation and a transmission of DNA alterations over generations, together with an increase in effect severity on growth and reproduction from generation F0 to generation F2. Transiently more efficient DNA repair leading to some recovery at the organism level was suggested in generation F1. Second, data from the external gamma irradiation and those from an earlier study of internal alpha contamination were analyzed with DEBtox models (Dynamic Energy Budget applied to toxicology), to identify and compare the causes of the trans-generational increase in effect severity between the two types of radiation. In each case, two distinct metabolic modes of action were necessary to explain effects on

Do not resonate with actions: sentence polarity modulates cortico-spinal excitability during action-related sentence reading.

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Marco Tullio Liuzza

Full Text Available BACKGROUND: Theories of embodied language suggest that the motor system is differentially called into action when processing motor-related versus abstract content words or sentences. It has been recently shown that processing negative polarity action-related sentences modulates neural activity of premotor and motor cortices. METHODS AND FINDINGS: We sought to determine whether reading negative polarity sentences brought about differential modulation of cortico-spinal motor excitability depending on processing hand-action related or abstract sentences. Facilitatory paired-pulses Transcranial Magnetic Stimulation (pp-TMS was applied to the primary motor representation of the right-hand and the recorded amplitude of induced motor-evoked potentials (MEP was used to index M1 activity during passive reading of either hand-action related or abstract content sentences presented in both negative and affirmative polarity. Results showed that the cortico-spinal excitability was affected by sentence polarity only in the hand-action related condition. Indeed, in keeping with previous TMS studies, reading positive polarity, hand action-related sentences suppressed cortico-spinal reactivity. This effect was absent when reading hand action-related negative polarity sentences. Moreover, no modulation of cortico-spinal reactivity was associated with either negative or positive polarity abstract sentences. CONCLUSIONS: Our results indicate that grammatical cues prompting motor negation reduce the cortico-spinal suppression associated with affirmative action sentences reading and thus suggest that motor simulative processes underlying the embodiment may involve even syntactic features of language.

Transmission risk assessment of invasive fluke Fascioloides magna using GIS-modelling and multicriteria analysis methods

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Juhásová L.

2017-06-01

Full Text Available The combination of multicriteria analysis (MCA, particularly analytic hierarchy process (AHP and geographic information system (GIS were applied for transmission risk assessment of Fascioloides magna (Trematoda; Fasciolidae in south-western Slovakia. Based on the details on F. magna life cycle, the following risk factors (RF of parasite transmission were determined: intermediate (RFIH and final hosts (RFFH (biological factors, annual precipitation (RFAP, land use (RFLU, flooded area (RFFA, and annual mean air temperature (RFAT (environmental factors. Two types of risk analyses were modelled: (1 potential risk analysis was focused on the determination of the potential risk of parasite transmission into novel territories (data on F. magna occurrence were excluded; (2 actual risk analysis considered also the summary data on F. magna occurrence in the model region (risk factor parasite occurrence RFPO included in the analysis. The results of the potential risk analysis provided novel distribution pattern and revealed new geographical area as the potential risk zone of F. magna occurrence. Although the actual risk analysis revealed all four risk zones of F. magna transmission (acceptable, moderate, undesirable and unacceptable, its outputs were significantly affected by the data on parasite occurrence what reduced the informative value of the actual transmission risk assessment.

CRISPR/Cas-mediated targeted mutagenesis in Daphnia magna.

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Takashi Nakanishi

Full Text Available The water flea Daphnia magna has been used as an animal model in ecology, evolution, and environmental sciences. Thanks to the recent progress in Daphnia genomics, genetic information such as the draft genome sequence and expressed sequence tags (ESTs is now available. To investigate the relationship between phenotypes and the available genetic information about Daphnia, some gene manipulation methods have been developed. However, a technique to induce targeted mutagenesis into Daphnia genome remains elusive. To overcome this problem, we focused on an emerging genome editing technique mediated by the clustered regularly interspaced short palindromic repeats/CRISPR-associated (CRISPR/Cas system to introduce genomic mutations. In this study, we targeted a functionally conserved regulator of eye development, the eyeless gene in D. magna. When we injected Cas9 mRNAs and eyeless-targeting guide RNAs into eggs, 18-47% of the survived juveniles exhibited abnormal eye morphology. After maturation, up to 8.2% of the adults produced progenies with deformed eyes, which carried mutations in the eyeless loci. These results showed that CRISPR/Cas system could introduce heritable mutations into the endogenous eyeless gene in D. magna. This is the first report of a targeted gene knockout technique in Daphnia and will be useful in uncovering Daphnia gene functions.

Computed tomography of the cisterna magna and mega cisterna magna in normal children

International Nuclear Information System (INIS)

Enomoto, Takao; Nakada, Yoshitaka; Maki, Yutaka

1984-01-01

We studied the cisterna magna (CM) on the computed tomography of children under 15 years of age. The scanners were GE-8800RTX and Hitachi CTH, and scanning was carried out parallel to the orbitomeatal line. Those with artifacts were excluded. 5 slices were needed to cover all the posterior fossa in children, but 4 slices were enough in infants, especially those under 6 months of age. 698 cases were included in the former group, and 69, in the latter. The authors estimated the size of the CM on the basis of the position of its tip. 7.1% of the children and 4% of the infants, especially under 6 months of age, had a CM of the full extent (from the foramen magnum to the 5th slice in children and to the 4th one in infants). If we may define a mega cisterna magna (MCM) as a CM more than 2 SD bigger than the mean, then the MCM are included in the groups described above. The MCM had no relationship with age or underlying disorders. The size of the 4th ventricle was, however, rather bigger in the MCM group than the normal CM group, suggesting that the pathogenesis of MCM might be a physiological hypoplasia of the cerebellar vermis. Therefore, no therapy was indicated for this abnormality. (author)

A fluorescence-based hydrolytic enzyme activity assay for quantifying toxic effects of Roundup® to Daphnia magna

DEFF Research Database (Denmark)

Ørsted, Michael; Roslev, Peter

2015-01-01

Daphnia magna is a widely used model organism for aquatic toxicity testing. In the present study, we investigated the hydrolytic enzyme activity of D. magna after exposure to toxicant stress. In vivo enzyme activity was quantified using 15 fluorogenic enzyme probes based on 4-methylumbelliferyl...... or 7-amino-4-methylcoumarin. Probing D. magna enzyme activity was evaluated using short-term exposure (24-48 h) to the reference chemical K2Cr2O7, or the herbicide formulation Roundup®. Toxicant induced changes in hydrolytic enzyme activity were compared to changes in mobility (ISO 6341). The results...... showed that hydrolytic enzyme activity was quantifiable as a combination of whole body fluorescence of D. magna, and fluorescence of the surrounding water. Exposure of D. magna to lethal and sublethal concentrations of Roundup® resulted in loss of whole body enzyme activity, and release of cell...

Life history response of Daphnia magna to a mixotrophic golden alga, Poterioochromonas sp., at different food levels

DEFF Research Database (Denmark)

Zhang, Xue; Hu, Hong-Ying; Perlt, Trine Warming

2011-01-01

The toxicity of Poterioochromonas to Daphnia magna was investigated at different food (Scenedesmus acutus) levels. Poterioochromonas alone of 0.4–20 mg C L-1 was not acutely toxic to D. magna, but did not support D. magna growth, either. When fed mixed diets (2 mg C L-1 in total), D. magna...

Corticospinal excitability modulation during action observation.

Science.gov (United States)

Sartori, Luisa; Betti, Sonia; Castiello, Umberto

2013-12-31

This study used the transcranial magnetic stimulation/motor evoked potential (TMS/MEP) technique to pinpoint when the automatic tendency to mirror someone else's action becomes anticipatory simulation of a complementary act. TMS was delivered to the left primary motor cortex corresponding to the hand to induce the highest level of MEP activity from the abductor digiti minimi (ADM; the muscle serving little finger abduction) as well as the first dorsal interosseus (FDI; the muscle serving index finger flexion/extension) muscles. A neuronavigation system was used to maintain the position of the TMS coil, and electromyographic (EMG) activity was recorded from the right ADM and FDI muscles. Producing original data with regard to motor resonance, the combined TMS/MEP technique has taken research on the perception-action coupling mechanism a step further. Specifically, it has answered the questions of how and when observing another person's actions produces motor facilitation in an onlooker's corresponding muscles and in what way corticospinal excitability is modulated in social contexts.

Breast abscess due to Finegoldia magna in a non-puerperal women.

Science.gov (United States)

Cobo, Fernando; Rodríguez-Granger, Javier; Sampedro, Antonio; Navarro-Marí, José María

2017-10-01

Finegoldia magna is a Gram-positive anaerobic coccus involved in a wide variety of infections. We report a unusual case of breast abscess in a non-puerperal patient. A 46-year-old woman presented with pain and a nodular lesion in the left breast. Culture of abscess drainage resulted in isolation of F. magna. Initial treatment with clindamycin was changed to a definitive treatment with amoxicillin-clavulanate for 10 days due to resistance to clindamycin, and improvement of this infection was documented. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of the lipid regulator Gemfibrozil in the Cladocera Daphnia magna at different temperatures.

Science.gov (United States)

Salesa, Beatriz; Ferrando, María D; Villarroel, María J; Sancho, Encarna

2017-02-23

In the present study, an ecotoxicological approach to the evaluation of Gemfibrozil (GEM) as an emerging organic pollutant was done. In order to assess its toxicity, tests were conducted using the cladocera Daphnia magna. Experiments were carried out at 22°C and 28°C. EC 50 , feeding behavior, and chronic toxicity tests (21 days) were evaluated in D. magna exposed to GEM as well as cholesterol levels at 21-day chronic exposure. D. magna GEM EC 50 values (24 h) in our experimental conditions were 148.75 and 116.24 mg L -1 at 22°C and 28°C, respectively. Test concentrations of 0.1, 0.5, 1.0, 5.0 and 7.5 mg L -1 were selected for subacute and chronic experiments. Subacute short-term test (feeding study) was assessed after exposure to the toxicant. Filtration and ingestion rates of D. magna exposed animals did not show any significant difference (P > 0.05) with respect to control daphniids neither at 22°C nor at 28°C. Therefore, GEM test concentrations used in the present study did not reduce feeding behavior in D. magna. Temperature increased from 22°C to 28°C, which resulted in a decrease of the daphniids reproductive parameters such as brood size and number of young per female. Other parameters as longevity were not affected. The GEM concentrations used in the chronic test with D. magna did not affect daphniids longevity but some reproductive parameters as number of young per female or brood size were affected. Finally, a significant decreased in cholesterol levels was found in those animals exposed to the highest toxicant concentrations. More studies must be done to determine the possible implications of GEM in aquatic fauna and to derive its possible effects on the environment.

Bioaccumulation, stress, and swimming impairment in Daphnia magna exposed to multiwalled carbon nanotubes, graphene, and graphene oxide.

Science.gov (United States)

Cano, Amanda M; Maul, Jonathan D; Saed, Mohammad; Shah, Smit A; Green, Micah J; Cañas-Carrell, Jaclyn E

2017-08-01

The use of carbon-based nanomaterials (CNMs) such as multiwalled carbon nanotubes (MWCNTs), graphene, and graphene oxide (GO) is increasing across many applications because of their unique and versatile properties. These CNMs may enter the aquatic environment through many pathways, creating the potential for organism exposure. The present study addresses the bioaccumulation and toxicity seen in Daphnia magna exposed to CNMs dispersed in sodium dodecyl benzene sulfonate (SDBS). In study I, D. magna were exposed to varying outer diameters of MWCNTs for 24 h in moderately hard or hard freshwater. Bioaccumulation of MWCNT was found in all treatments, with the highest concentrations (0.53 ± 0.27 μg/g) in D. magna exposed in hard freshwater (p < 0.005). The median lethal concentration (LC50) was determined for D. magna exposed to CNMs in moderately hard and hard freshwater. In study II, D. magna were exposed to CNMs for 72 h in moderately hard freshwater to assess swimming velocity and generation of reactive oxygen species (ROS) detected by dichlorofluorescein fluorescence. An overall decrease was seen in D. magna swimming velocity after exposure to CNMs. The generation of ROS was significantly higher (1.54 ± 0.38 dichlorofluorescein mM/mg dry wt) in D. magna exposed to MWCNTs of smaller outer diameters than in controls after 72 h (p < 0.05). These results suggest that further investigation of CNM toxicity and behavior in the aquatic environment is needed. Environ Toxicol Chem 2017;36:2199-2204. © 2017 SETAC. © 2017 SETAC.

Bioconcentration of the antidepressant fluoxetine and its effects on the physiological and biochemical status in Daphnia magna.

Science.gov (United States)

Ding, Jiannan; Zou, Hua; Liu, Qingqing; Zhang, Shanshan; Mamitiana Razanajatovo, Roger

2017-08-01

The aim of this study was to evaluate the bioconcentration potential of fluoxetine and its biological effects in Daphnia magna. After 48h of waterborne exposure, the bioconcentration of fluoxetine in D. magna was determined to be 460.61 and 174.41Lkg -1 for nominal exposure concentrations of 0.5 and 5µgL -1 , respectively. Moreover, various biological endpoints, including physiological responses (filtration and ingestion rates), enzymatic biomarkers related to neurotoxicity [acetylcholinesterase (AChE)] and antioxidant defense [superoxide dismutase (SOD)], and an oxidative stress damage marker [malondialdehyde (MDA)], were assessed. Fluoxetine exposure increased the filtration rate of daphnia, while the ingestion rate was not obviously modified. AChE activity was significantly inhibited, highlighting the neurotoxicity of fluoxetine on D. magna. However, with some alterations in the SOD activity and MDA content, no obvious oxidative damage was observed in D. magna exposed to fluoxetine at the tested concentrations. These results indicate that fluoxetine can be accumulated and consequently induce physiological and biochemical perturbations in D. magna. Copyright © 2017. Published by Elsevier Inc.

Object words modulate the activity of the mirror neuron system during action imitation.

Science.gov (United States)

Wu, Haiyan; Tang, Honghong; Ge, Yue; Yang, Suyong; Mai, Xiaoqin; Luo, Yue-Jia; Liu, Chao

2017-11-01

Although research has demonstrated that the mirror neuron system (MNS) plays a crucial role in both action imitation and action-related semantic processing, whether action-related words can inversely modulate the MNS activity remains unclear. Here, three types of task-irrelevant words (body parts, verbs, and manufactured objects) were presented to examine the modulation effect of these words on the MNS activity during action observation and imitation. Twenty-two participants were recruited for the fMRI scanning and remaining data from 19 subjects were reported here. Brain activity results showed that word types elicited different modulation effects over nodes of the MNS (i.e., the right inferior frontal gyrus, premotor cortex, inferior parietal lobule, and STS), especially during the imitation stage. Compared with other word conditions, action imitation following manufactured objects words induced stronger activation in these brain regions during the imitation stage. These results were consistent in both task-dependent and -independent ROI analysis. Our findings thus provide evidence for the unique effect of object words on the MNS during imitation of action, which may also confirm the key role of goal inference in action imitation.

Secreted protein eco-corona mediates uptake and impacts of polystyrene nanoparticles on Daphnia magna.

Science.gov (United States)

Nasser, Fatima; Lynch, Iseult

2016-03-30

Nanoparticles (NPs) are defined as having at least one external dimension between 1 and 100 nm. Due to their small size, NPs have a large surface area to volume ratio giving them unique characteristics that differ from bulk material of the same chemical composition. As a result these novel materials have found numerous applications in medical and industrial fields with the result that environmental exposure to NPs is increasingly likely. Similarly, increased reliance on plastic, which degrades extremely slowly in the environment, is resulting in increased accumulation of micro-/nano-plastics in fresh and marine waters, whose ecotoxicological impacts are as yet poorly understood. Although NPs are well known to adsorb macromolecules from their environment, forming a biomolecule corona which changes the NP identity and how it interacts with organisms, significantly less research has been performed on the ecological corona (eco-corona). Secretion of biomolecules is a well established predator-prey response in aquatic food chains, raising the question of whether NPs interact with secreted proteins, and the impact of such interaction on NP uptake and ecotoxicity. We report here initial studies, including optimisation of protocols using carboxylic-acid and amino modified spherical polystyrene NPs, to assess interaction of NPs with biomolecules secreted by Daphnia magna and the impact of these interactions on NP uptake, retention and toxicity towards Daphnia magna. Daphnia magna are an important environmental indicator species who may be especially sensitive to nanoparticles (NPs) as a result of being filter-feeders. This paper demonstrates for the first time that proteins released by Daphnia magna create an eco-corona around polystyrene NPs which causes heightened uptake of the NPs and consequently increases toxicity. The secreted protein eco-corona also causes the NPs to be less efficiently removed from the gut of D. magna and NPs remaining in the gut of D. magna

Paraspidodera uncinata (Nematoda, Lauroiinae as parasite of Cavia magna and Cavia aperea (Rodentia, Caviidae in southern Brazil

Directory of Open Access Journals (Sweden)

Ana Gabriela da Silva Rocha

2015-05-01

Full Text Available Out of the 5 species of Guinea pig registered for Brazil, 4 (Cavia fulgida, C. porcellus, C. aperea, and C. magna have already been reported as hosts of Paraspidodera uncinata. The rodent species C. magna and C. aperea are small-sized mammals, with terrestrial habits, which occur from southern Brazil to eastern Uruguay. Guinea pig specimens donated for research were necropsied for the analysis of endoparasites, and the nematodes found were identified as P. uncinata. The microhabitats of this species were the small and large intestines in C. magna and the large intestine in C. aperea. The prevalence of P. uncinata in the hosts was 60% in C. magna (n = 5 and 14% in C. aperea (n = 7. The record of P. uncinata in different Guinea pig species allows inferring that the foraging mode is similar in the different locations where they occur in southern Brazil, because, perhaps, the infection of hosts has occurred through the ingestion of vegetables contaminated with P. uncinata eggs. This study contributes to knowledge on the helminth fauna of C. magna and C. aperea in southern Brazil.

Ecotoxicological testing of gas oils (daphnia magna test)

Energy Technology Data Exchange (ETDEWEB)

Altmann, B.R.; Mueller, J.; Wenzel, A.; Hensel, R.

2002-02-01

The Water Accomodated Fractions WAF of 4 diesel fuels no. 2 and 4 domestic heating fuels no. 2 of differing origin were analysed on their effect on the mobility of the freshwater crustacean Daphnia Magna. Five loadings per test substance were tested. After an exposition period of 24 h a relationship between loading rates of the WAF and immobility was found for 3 samples, while after 48 h this was observed for all samples. WAF-generation and gas oil data were documented. (orig.) [German] Von 4 Dieselkraftstoff-Gasoelen und 4 Heizoel-Gasoelen EL wurden die Water Accomodated Fractions WAF auf ihre immobilisierende Wirkung auf den Wasserfloh Daphnia Magna untersucht. Von jeder Probe wurden fuenf unterschiedliche Dosierraten geprueft. Nach einer Expositionszeit von 24 Stunden zeigte sich bei 3 Proben und nach 48 Stunden bei allen Proben eine Beziehung zwischen der Dosierrate der Probe und der Immobilitaet. Die Herstellung der WAF und die Daten der Gasoele wurden dokumentiert. (orig.)

A Study on the D. magna and V. fischeri Toxicity Relationship of Industrial Wastewater from Korea

Science.gov (United States)

Pyo, S.; Lee, S.; Chun Sang, H.; Park, T. J.; Kim, M. S.

2015-12-01

It is well known that high concentration of TDS (total dissolved solid) in industrial effluent gives rise to the toxicity to the Daphnia magna toxicity test. D. magna is vulnerable to relatively low TDS concentration showing the 24-hr EC50 of Salinity 0.6% (as the sea salt concentration). Recently, standard mandatory toxicity testing using Daphnia magna has been used to monitor industrial effluent toxicity according to Korea standard method (Acute Toxicity Test Method of the Daphnia magna Straus (Cladocera, Crustacea), ES 04704. 1a) under regulation. Since only one acute toxicity testing is applied in the present, we are trying to introduce microbial battery for more complete toxicity assessment. In this study, the acute toxicities between daphnids and microbes were compared. The results of D. magna and Vibrio fischeri toxicity test from 165 industrial wastewater effluents showed high positive correlation. In addition, the possibility of predicting daphnia toxicity from the bacterial toxicity data amounts to 92.6% if we consider salinity effect (>5ppt) together. From this study, we found that the V. fischeri toxicity test is a powerful battery tool to assess the industrial wastewater toxicity. Here, we suggest that luminescent bacteria toxicity test be useful not only for complete toxicity assessment which can't be obtained by daphnia toxicity testing only but also for the reduction cost, time, and labor in the Korean society. Keywords : D. magna, V. fischeri, Industrial waste water, battery test Acknowledgement This research was supported by a grant (15IFIP-B089908-02) from Plant Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government

Action preparation modulates sensory perception in unseen personal space: An electrophysiological investigation.

Science.gov (United States)

Job, Xavier E; de Fockert, Jan W; van Velzen, José

2016-08-01

Behavioural and electrophysiological evidence has demonstrated that preparation of goal-directed actions modulates sensory perception at the goal location before the action is executed. However, previous studies have focused on sensory perception in areas of peripersonal space. The present study investigated visual and tactile sensory processing at the goal location of upcoming movements towards the body, much of which is not visible, as well as visible peripersonal space. A motor task cued participants to prepare a reaching movement towards goals either in peripersonal space in front of them or personal space on the upper chest. In order to assess modulations of sensory perception during movement preparation, event-related potentials (ERPs) were recorded in response to task-irrelevant visual and tactile probe stimuli delivered randomly at one of the goal locations of the movements. In line with previous neurophysiological findings, movement preparation modulated visual processing at the goal of a movement in peripersonal space. Movement preparation also modulated somatosensory processing at the movement goal in personal space. The findings demonstrate that tactile perception in personal space is subject to similar top-down sensory modulation by motor preparation as observed for visual stimuli presented in peripersonal space. These findings show for the first time that the principles and mechanisms underlying adaptive modulation of sensory processing in the context of action extend to tactile perception in unseen personal space. Copyright © 2016 Elsevier Ltd. All rights reserved.

Toxicity and genotoxicity of the quaternary ammonium compound benzalkonium chloride (BAC) using Daphnia magna and Ceriodaphnia dubia as model systems

International Nuclear Information System (INIS)

Lavorgna, Margherita; Russo, Chiara; D'Abrosca, Brigida; Parrella, Alfredo; Isidori, Marina

2016-01-01

The toxicity and genotoxicity of the cationic surfactant benzalkonium chloride (BAC) were studied using Daphnia magna and Ceriodaphnia dubia as model systems. Acute and chronic toxicity testing were performed according to the international standard guidelines and the genotoxicity was detected through the comet assay on cells from whole organisms in vivo exposed. Acute effects occurred at concentrations in the order of tens of μg/L in D. magna and hundreds of μg/L in C. dubia. Chronic effects were found at one order of magnitude less than short-term effects maintaining the same difference in sensitivity between D. magna and C. dubia. BAC induced relevant DNA damage, in both cladocerans; the lowest adverse effect levels were 0.4 and 4 ng/L for D. magna and C. dubia, respectively. As these effective concentrations are far lower than BAC occurrence in surface waters (units of μg/L) a concerning environmental risk cannot be excluded. The findings of this study showed that D. magna and C. dubia, could be used as model organisms to detect acute and chronic toxicity as well as genotoxicity at the whole organism level. - Highlights: • Benzalkonium chloride chronic effect in C. dubia was found at dozens of μg/L. • The LOAEC detected by comet assay in D. magna is in the order of hundreds of pg/L. • D. magna and C. dubia are useful model organisms to detect toxicity and genotoxicity. - Benzalkonium chloride showed chronic toxicity and genotoxicity in Daphnia magna and Ceriodaphnia dubia at concentrations of environmental concern. Daphnids are useful model organisms.

In vivo biodegradation of colloidal quantum dots by a freshwater invertebrate, Daphnia magna

Energy Technology Data Exchange (ETDEWEB)

Kwon, Dongwook; Kim, Min Jung; Park, Chansik; Park, Jaehong [Department of Chemistry, Hanyang University, Seoul 133-791 (Korea, Republic of); Choi, Kyungho [Department of Environmental Health, Seoul National University, Seoul 151-742 (Korea, Republic of); Yoon, Tae Hyun, E-mail: thyoon@gmail.com [Department of Chemistry, Hanyang University, Seoul 133-791 (Korea, Republic of)

2012-06-15

Impacts of planktonic invertebrate, Daphnia magna, on the speciation of colloidal quantum dots (QD) were investigated using fluorescence spectromicroscopic technique. Well-dispersed {sup GA/TOPO}QD were prepared by forming a supramolecular assembly of hydrophobic {sup TOPO}QD with biomacromolecules (i.e., Gum Arabic, GA). Biological degradation of this nanomaterial was monitored by fluorescence spectromicroscopic methods. Our study confirmed the major uptake pathway of manufactured nanomaterials and in vivo biodegradation processes in a well-known toxicity test organism, D. magna. In addition, we also found that D. magna can induce significant deterioration of aquatic media by releasing fragments of partially degraded QD colloids. These biological processes may significantly change the predicted toxicities of nanomaterials in aquatic environments. Thus, we propose that the impacts of aquatic living organisms on the environmental fate of manufactured nanomaterials (MNs) should be carefully taken into account when assessing the risk of MNs to the environment and human health.

Multi-generational effects of propranolol on Daphnia magna at different environmental concentrations

International Nuclear Information System (INIS)

Jeong, Tae-Yong; Kim, Hyun Young; Kim, Sang Don

2015-01-01

To evaluate the effects of propranolol on Daphnia magna (D. magna), we employed a multi-generational exposure period for eight generations and an environmentally relevant low concentration with 1.5 ng/L, 0.2 μg/L and 26 μg/L to reflect a realistic exposure scenario. Physiological endpoints were checked, including growth, number of neonates, heart rate, frequency of abdominal appendage movement and malformation rate of neonates. In the results, growth and abdominal appendage movement were affected by environmental concentration during several generations, and the responses showed consistent tendencies of response increase with concentration increase. Heart rate was the only endpoint affected throughout all exposure generations. Inhibitory and acceleratory effects on heart rate, growth and abdominal appendage movement suggest that it is necessary to cover sub-lethal endpoints of non-targeted organisms in eco-toxicity study because the physiological responses were detected at much lower concentrations than the results of traditional toxicity tests, including environmental concentration. - Highlights: • Multi-generational exposure was conducted to evaluate the effect of propranolol on Daphnia magna. • Heart rate was the only endpoint affected throughout all exposure generations. • Growth and abdominal appendage movement were affected at environmental concentrations. • Time series fluctuations in responses appeared with no tendencies throughout all generations. • It is necessary to cover sub-organismal endpoints and long-term exposure in ecotoxicity test. - Heart rate, growth and abdominal appendage movement of D. magna were affected by the multigenerational exposure of propranolol at environmental levels.

Genetic variation in the cellular response of Daphnia magna (Crustacea: Cladocera) to its bacterial parasite.

Science.gov (United States)

Auld, Stuart K J R; Scholefield, Jennifer A; Little, Tom J

2010-11-07

Linking measures of immune function with infection, and ultimately, host and parasite fitness is a major goal in the field of ecological immunology. In this study, we tested for the presence and timing of a cellular immune response in the crustacean Daphnia magna following exposure to its sterilizing endoparasite Pasteuria ramosa. We found that D. magna possesses two cell types circulating in the haemolymph: a spherical one, which we call a granulocyte and an irregular-shaped amoeboid cell first described by Metchnikoff over 125 years ago. Daphnia magna mounts a strong cellular response (of the amoeboid cells) just a few hours after parasite exposure. We further tested for, and found, considerable genetic variation for the magnitude of this cellular response. These data fostered a heuristic model of resistance in this naturally coevolving host-parasite interaction. Specifically, the strongest cellular responses were found in the most susceptible hosts, indicating resistance is not always borne from a response that destroys invading parasites, but rather stems from mechanisms that prevent their initial entry. Thus, D. magna may have a two-stage defence--a genetically determined barrier to parasite establishment and a cellular response once establishment has begun.

Magna Carta: Teaching Medieval Topics for Historical Significance

Science.gov (United States)

Metzger, Scott Alan

2010-01-01

The Middle Ages are an immensely important era in the Western experience. Unfortunately, medieval studies are often marginalized or trivialized in school curriculum. With the approach of the 800th anniversary of Magna Carta, the famous charter of rights from medieval England, one has a timely and useful example for considering what a focus on…

Ecotoxicological effect of ketamine: Evidence of acute, chronic and photolysis toxicity to Daphnia magna.

Science.gov (United States)

Li, Shih-Wei; Wang, Yu-Hsiang; Lin, Angela Yu-Chen

2017-09-01

Ketamine has been increasingly used in medicine and has the potential for abuse or illicit use around the world. Ketamine cannot be removed by conventional wastewater treatment plants. Although ketamine and its metabolite norketamine have been detected to a significant degree in effluents and aquatic environments, their ecotoxicity effects in aquatic organisms remain undefined. In this study, we investigated the acute toxicity of ketamine and its metabolite, along with the chronic reproductive toxicity of ketamine (5-100μg/L) to Daphnia magna. Multiple environmental scenarios were also evaluated, including drug mixtures and sunlight irradiation toxicity. Ketamine and norketamine caused acute toxicity to D. magna, with half lethal concentration (LC 50 ) values of 30.93 and 25.35mg/L, respectively, after 48h of exposure. Irradiated solutions of ketamine (20mg/L) significantly increased the mortality of D. magna; pre-irradiation durations up to 2h rapidly increased the death rate to 100%. A new photolysis byproduct (M.W. 241) of norketamine that accumulates during irradiation was identified for the first time. The relevant environmental concentration of ketamine produced significant reproductive toxicity effects in D. magna, as revealed by the reduction of the number of total live offspring by 33.6-49.8% (p ketamine concentration cannot be ignored and warrant further examination. Copyright © 2017 Elsevier Inc. All rights reserved.

Uptake and depuration of gold nanoparticles in Daphnia magna

DEFF Research Database (Denmark)

Skjolding, Lars Michael; Kern, Kristina; Hjorth, Rune

2014-01-01

This study presents a series of short-term studies (total duration 48 h) of uptake and depuration of engineered nanoparticles (ENP) in neonate Daphnia magna. Gold nanoparticles (Au NP) were used to study the influence of size, stabilizing agent and feeding on uptake and depuration kinetics...

Free ionic nickel accumulation and localization in the freshwater zooplankter, Daphnia magna

International Nuclear Information System (INIS)

Hall, T.M.

1982-01-01

The processes which lead to the accumulation of free ionic nickel (radioactive) from solution by Daphnia magna were studied and incorporated into a model which describes accummulation at different concentrations. Adsorption proved to be a relatively small component of nickel accummulation. The accummulation rate eventually approached zero, which represented an equilibrium between uptake and loss of nickel. However, elimination experiments did reveal a pool of relatively static nickel. The appearance and distribution of nickel within five body parts (body fluid, carapace, gut, filtering appendages, and eggs) of D. magna supported the accummulation data and added to the understanding of the pathways of nickel through the organism

Bioassay of Phenol and its Intermediate Products Using Daphnia magna

Directory of Open Access Journals (Sweden)

Afshin Maleki

2008-06-01

Full Text Available Phenol is one of the most common compounds found in many industrial effluents such as petroleum refining and petrochemicals, pharmaceuticals, pesticides, paint and dye industries, organic chemicals manufacturing, etc. The contamination of bodies of water with phenol is a serious problem in terms of environmental considerations due to its high toxicity. In this study, toxicity of phenol and its degradation mixtures by sonochemical, photochemical, and photosonochemical processes were investigated. Toxicity assay tests were carried out using Daphnia magna as a bio-indicator. The sonochemical and photochemical experiments were carried out using a bath sonicator (500 W working at 35 and 130 kHz frequencies and with a 400 W medium pressure mercury lamp, respectively. Experiments were performed at initial concentrations of 100 mg L-1. Bioassay tests showed that phenol was toxic to D.magna and so resulted in quite low LC50 values. Comparison of toxicity units (TU between phenol and effluent toxicity showed that TU value for photosonochemical effluent was lower than that obtained for phenol, photochemical effluent, and sonochemical effluent. It was found that the toxicity unit of photochemical effluent was lower than that obtained for sonochemical effluent. According to the D.magna acute toxicity test, it is concluded that photosonolysis and photolysis are capable of decreasing the toxicity of by-products formed during the degradation of phenol aqueous solutions. Photosonic and photolytic processes can, therefore, be recommended as a potential approach to the treatment of phenolic wastewater.

Interactive effects of a bacterial parasite and the insecticide carbaryl to life-history and physiology of two Daphnia magna clones differing in carbaryl sensitivity

International Nuclear Information System (INIS)

De Coninck, Dieter I.M.; De Schamphelaere, Karel A.C.; Jansen, Mieke; De Meester, Luc; Janssen, Colin R.

2013-01-01

Highlights: ► Interactive effects between a bacterial parasite and an insecticide in Daphnia magna. ► Two D. magna clones differing strongly in their sensitivity to the insecticide. ► Effects studied on various life-history and physiological endpoints. ► Genetic differences in strength and direction of interaction effects. -- Abstract: Natural and chemical stressors occur simultaneously in the aquatic environment. Their combined effects on biota are usually difficult to predict from their individual effects due to interactions between the different stressors. Several recent studies have suggested that synergistic effects of multiple stressors on organisms may be more common at high compared to low overall levels of stress. In this study, we used a three-way full factorial design to investigate whether interactive effects between a natural stressor, the bacterial parasite Pasteuria ramosa, and a chemical stressor, the insecticide carbaryl, were different between two genetically distinct clones of Daphnia magna that strongly differ in their sensitivity to carbaryl. Interactive effects on various life-history and physiological endpoints were assessed as significant deviations from the reference Independent Action (IA) model, which was implemented by testing the significance of the two-way carbaryl × parasite interaction term in two-way ANOVA's on log-transformed observational data for each clone separately. Interactive effects (and thus significant deviations from IA) were detected in both the carbaryl-sensitive clone (on survival, early reproduction and growth) and in the non-sensitive clone (on growth, electron transport activity and prophenoloxidase activity). No interactions were found for maturation rate, filtration rate, and energy reserve fractions (carbohydrate, protein, lipid). Furthermore, only antagonistic interactions were detected in the non-sensitive clone, while only synergistic interactions were observed in the carbaryl sensitive clone. Our

Interactive effects of a bacterial parasite and the insecticide carbaryl to life-history and physiology of two Daphnia magna clones differing in carbaryl sensitivity

Energy Technology Data Exchange (ETDEWEB)

De Coninck, Dieter I.M., E-mail: Dieter.DeConinck@UGent.be [Laboratory of Environmental Toxicology and Aquatic Ecology, Ghent University, J. Plateaustraat 22, B-9000 Ghent (Belgium); De Schamphelaere, Karel A.C. [Laboratory of Environmental Toxicology and Aquatic Ecology, Ghent University, J. Plateaustraat 22, B-9000 Ghent (Belgium); Jansen, Mieke; De Meester, Luc [Laboratory of Aquatic Ecology, Evolution and Conservation, University of Leuven, Ch. Deberiotstraat 32, B-3000 Leuven (Belgium); Janssen, Colin R. [Laboratory of Environmental Toxicology and Aquatic Ecology, Ghent University, J. Plateaustraat 22, B-9000 Ghent (Belgium)

2013-04-15

Highlights: ► Interactive effects between a bacterial parasite and an insecticide in Daphnia magna. ► Two D. magna clones differing strongly in their sensitivity to the insecticide. ► Effects studied on various life-history and physiological endpoints. ► Genetic differences in strength and direction of interaction effects. -- Abstract: Natural and chemical stressors occur simultaneously in the aquatic environment. Their combined effects on biota are usually difficult to predict from their individual effects due to interactions between the different stressors. Several recent studies have suggested that synergistic effects of multiple stressors on organisms may be more common at high compared to low overall levels of stress. In this study, we used a three-way full factorial design to investigate whether interactive effects between a natural stressor, the bacterial parasite Pasteuria ramosa, and a chemical stressor, the insecticide carbaryl, were different between two genetically distinct clones of Daphnia magna that strongly differ in their sensitivity to carbaryl. Interactive effects on various life-history and physiological endpoints were assessed as significant deviations from the reference Independent Action (IA) model, which was implemented by testing the significance of the two-way carbaryl × parasite interaction term in two-way ANOVA's on log-transformed observational data for each clone separately. Interactive effects (and thus significant deviations from IA) were detected in both the carbaryl-sensitive clone (on survival, early reproduction and growth) and in the non-sensitive clone (on growth, electron transport activity and prophenoloxidase activity). No interactions were found for maturation rate, filtration rate, and energy reserve fractions (carbohydrate, protein, lipid). Furthermore, only antagonistic interactions were detected in the non-sensitive clone, while only synergistic interactions were observed in the carbaryl sensitive clone. Our

Interactive effects of a bacterial parasite and the insecticide carbaryl to life-history and physiology of two Daphnia magna clones differing in carbaryl sensitivity

Energy Technology Data Exchange (ETDEWEB)

De Coninck, Dieter I.M., E-mail: Dieter.DeConinck@UGent.be [Laboratory of Environmental Toxicology and Aquatic Ecology, Ghent University, J. Plateaustraat 22, B-9000 Ghent (Belgium); De Schamphelaere, Karel A.C. [Laboratory of Environmental Toxicology and Aquatic Ecology, Ghent University, J. Plateaustraat 22, B-9000 Ghent (Belgium); Jansen, Mieke; De Meester, Luc [Laboratory of Aquatic Ecology, Evolution and Conservation, University of Leuven, Ch. Deberiotstraat 32, B-3000 Leuven (Belgium); Janssen, Colin R. [Laboratory of Environmental Toxicology and Aquatic Ecology, Ghent University, J. Plateaustraat 22, B-9000 Ghent (Belgium)

2013-04-15

Highlights: ► Interactive effects between a bacterial parasite and an insecticide in Daphnia magna. ► Two D. magna clones differing strongly in their sensitivity to the insecticide. ► Effects studied on various life-history and physiological endpoints. ► Genetic differences in strength and direction of interaction effects. -- Abstract: Natural and chemical stressors occur simultaneously in the aquatic environment. Their combined effects on biota are usually difficult to predict from their individual effects due to interactions between the different stressors. Several recent studies have suggested that synergistic effects of multiple stressors on organisms may be more common at high compared to low overall levels of stress. In this study, we used a three-way full factorial design to investigate whether interactive effects between a natural stressor, the bacterial parasite Pasteuria ramosa, and a chemical stressor, the insecticide carbaryl, were different between two genetically distinct clones of Daphnia magna that strongly differ in their sensitivity to carbaryl. Interactive effects on various life-history and physiological endpoints were assessed as significant deviations from the reference Independent Action (IA) model, which was implemented by testing the significance of the two-way carbaryl × parasite interaction term in two-way ANOVA's on log-transformed observational data for each clone separately. Interactive effects (and thus significant deviations from IA) were detected in both the carbaryl-sensitive clone (on survival, early reproduction and growth) and in the non-sensitive clone (on growth, electron transport activity and prophenoloxidase activity). No interactions were found for maturation rate, filtration rate, and energy reserve fractions (carbohydrate, protein, lipid). Furthermore, only antagonistic interactions were detected in the non-sensitive clone, while only synergistic interactions were observed in the carbaryl sensitive clone

The acute toxic effects of 1-alkyl-3-methylimidazolium nitrate ionic liquids on Chlorella vulgaris and Daphnia magna.

Science.gov (United States)

Zhang, Cheng; Zhang, Shuai; Zhu, Lusheng; Wang, Jinhua; Wang, Jun; Zhou, Tongtong

2017-10-01

Given their increasingly widespread application, the toxic effects of ionic liquids (ILs) have become the subject of significant attention in recent years. Therefore, the present study assessed the acute toxic effects of 1-alkyl-3-methylimidazolium nitrate ([C n mim]NO 3 (n = 2, 4, 6, 8, 10, 12)) on Chlorella vulgaris and Daphnia magna. The sensitivity of the tested organism Daphnia magna and the investigated IL concentrations in water using high-performance liquid chromatography (HPLC) were also evaluated to demonstrate the reliability of the present study. The results illustrated that Daphnia magna is indeed sensitive to the reference toxicant and the investigated ILs were stable in the aquatic environment. The 50% effect concentration (EC 50 ) was used to represent the acute toxic effects on Chlorella vulgaris and Daphnia magna. With the increasing alkyl-chain lengths, the toxicity of the investigated ILs increased in both the test organisms. Accordingly, the alkyl-chain lengths can cause significantly toxic effects on aquatic organisms, and Daphnia magna are much more sensitive than Chlorella vulgaris to the imidazolium-based ILs used in the present study. Furthermore, the present study provides more information on the acute toxic effects of 1-alkyl-3-methylimidazolium nitrate. Copyright © 2017 Elsevier Ltd. All rights reserved.

Magna Carta Libertatum – osmisté výročí

Czech Academy of Sciences Publication Activity Database

Blahož, Josef

2015-01-01

Roč. 154, č. 6 (2015), s. 449-464 ISSN 0231-6625 Institutional support: RVO:68378122 Keywords : Magna Carta Libertatum * development of constitutionalism * rule of law Subject RIV: AG - Legal Sciences

Single nucleotide polymorphism discovery from expressed sequence tags in the waterflea Daphnia magna

Directory of Open Access Journals (Sweden)

Souche Erika L

2011-06-01

Full Text Available Abstract Background Daphnia (Crustacea: Cladocera plays a central role in standing aquatic ecosystems, has a well known ecology and is widely used in population studies and environmental risk assessments. Daphnia magna is, especially in Europe, intensively used to study stress responses of natural populations to pollutants, climate change, and antagonistic interactions with predators and parasites, which have all been demonstrated to induce micro-evolutionary and adaptive responses. Although its ecology and evolutionary biology is intensively studied, little is known on the functional genomics underpinning of phenotypic responses to environmental stressors. The aim of the present study was to find genes expressed in presence of environmental stressors, and target such genes for single nucleotide polymorphic (SNP marker development. Results We developed three expressed sequence tag (EST libraries using clonal lineages of D. magna exposed to ecological stressors, namely fish predation, parasite infection and pesticide exposure. We used these newly developed ESTs and other Daphnia ESTs retrieved from NCBI GeneBank to mine for SNP markers targeting synonymous as well as non synonymous genetic variation. We validate the developed SNPs in six natural populations of D. magna distributed at regional scale. Conclusions A large proportion (47% of the produced ESTs are Daphnia lineage specific genes, which are potentially involved in responses to environmental stress rather than to general cellular functions and metabolic activities, or reflect the arthropod's aquatic lifestyle. The characterization of genes expressed under stress and the validation of their SNPs for population genetic study is important for identifying ecologically responsive genes in D. magna.

Modulation of brain activity during action observation: influence of perspective, transitivity and meaningfulness.

Directory of Open Access Journals (Sweden)

Sébastien Hétu

Full Text Available The coupling process between observed and performed actions is thought to be performed by a fronto-parietal perception-action system including regions of the inferior frontal gyrus and the inferior parietal lobule. When investigating the influence of the movements' characteristics on this process, most research on action observation has focused on only one particular variable even though the type of movements we observe can vary on several levels. By manipulating the visual perspective, transitivity and meaningfulness of observed movements in a functional magnetic resonance imaging study we aimed at investigating how the type of movements and the visual perspective can modulate brain activity during action observation in healthy individuals. Importantly, we used an active observation task where participants had to subsequently execute or imagine the observed movements. Our results show that the fronto-parietal regions of the perception action system were mostly recruited during the observation of meaningless actions while visual perspective had little influence on the activity within the perception-action system. Simultaneous investigation of several sources of modulation during active action observation is probably an approach that could lead to a greater ecological comprehension of this important sensorimotor process.

A piece of the action: modulation of sensory-motor regions by action idioms and metaphors.

Science.gov (United States)

Desai, Rutvik H; Conant, Lisa L; Binder, Jeffrey R; Park, Haeil; Seidenberg, Mark S

2013-12-01

The idea that the conceptual system draws on sensory and motor systems has received considerable experimental support in recent years. Whether the tight coupling between sensory-motor and conceptual systems is modulated by factors such as context or task demands is a matter of controversy. Here, we tested the context sensitivity of this coupling by using action verbs in three different types of sentences in an fMRI study: literal action, apt but non-idiomatic action metaphors, and action idioms. Abstract sentences served as a baseline. The result showed involvement of sensory-motor areas for literal and metaphoric action sentences, but not for idiomatic ones. A trend of increasing sensory-motor activation from abstract to idiomatic to metaphoric to literal sentences was seen. These results support a gradual abstraction process whereby the reliance on sensory-motor systems is reduced as the abstractness of meaning as well as conventionalization is increased, highlighting the context sensitive nature of semantic processing. © 2013.

Acute and chronic toxicity of veterinary antibiotics to Daphnia magna

DEFF Research Database (Denmark)

Wollenberger, Leah; Halling-Sørensen, B.; Kusk, Kresten Ole

2000-01-01

The acute and chronic toxicity of nine antibiotics used both therapeutically and as growth promoters in intensive farming was investigated on the freshwater crustacean Daphnia magna. The effect of the antibiotics metronidazole (M), olaquindox (OL), oxolinic acid (OA), oxytetracycline (OTC...

Understanding action language modulates oscillatory mu and beta rhythms in the same way as observing actions.

Science.gov (United States)

Moreno, Iván; de Vega, Manuel; León, Inmaculada

2013-08-01

The mu rhythms (8-13 Hz) and the beta rhythms (15 up to 30 Hz) of the EEG are observed in the central electrodes (C3, Cz and C4) in resting states, and become suppressed when participants perform a manual action or when they observe another's action. This has led researchers to consider that these rhythms are electrophysiological markers of the motor neuron activity in humans. This study tested whether the comprehension of action language, unlike abstract language, modulates mu and low beta rhythms (15-20 Hz) in a similar way as the observation of real actions. The log-ratios were calculated for each oscillatory band between each condition and baseline resting periods. The results indicated that both action language and action videos caused mu and beta suppression (negative log-ratios), whereas abstract language did not, confirming the hypothesis that understanding action language activates motor networks in the brain. In other words, the resonance of motor areas associated with action language is compatible with the embodiment approach to linguistic meaning. Copyright © 2013 Elsevier Inc. All rights reserved.

Health Activities Project (HAP): Heart Fitness and Action Module.

Science.gov (United States)

Buller, Dave; And Others

Contained within this Health Activities Project (HAP) learning packet are activities for children in grades 5-8. Design of the activities centers around the idea that students can control their own health and safety. Within the Heart Fitness and Action Module are teacher and student folios describing five activities which involve students in…

Rapid changes in water hardness and alkalinity: Calcite formation is lethal to Daphnia magna.

Science.gov (United States)

Bogart, Sarah J; Woodman, Samuel; Steinkey, Dylan; Meays, Cindy; Pyle, Greg G

2016-07-15

There is growing concern that freshwater ecosystems may be negatively affected by ever-increasing anthropogenic inputs of extremely hard, highly alkaline effluent containing large quantities of Ca(2+), Mg(2+), CO3(2-), and HCO3(-) ions. In this study, the toxicity of rapid and extreme shifts in water hardness (38-600mg/L as CaCO3) and alkalinity (30-420mg/L as CaCO3) to Daphnia magna was tested, both independently and in combination. Within these ranges, where no precipitation event occurred, shifts in water hardness and/or alkalinity were not toxic to D. magna. In contrast, 98-100% of D. magna died within 96h after exposure to 600mg/L as CaCO3 water hardness and 420mg/L as CaCO3 alkalinity (LT50 of 60h with a 95% CI of 54.2-66.0h). In this treatment, a CaCO3 (calcite) precipitate formed in the water column which was ingested by and thoroughly coated the D. magna. Calcite collected from a mining impacted stream contained embedded organisms, suggesting field streams may also experience similar conditions and possibly increased mortality as observed in the lab tests. Although further investigation is required to determine the exact fate of aquatic organisms exposed to rapid calcite precipitation in the field, we caution that negative effects may occur more quickly or at lower concentrations of water hardness and alkalinity in which we observed effects in D. magna, because some species, such as aquatic insects, are more sensitive than cladocerans to changes in ionic strength. Our results provide evidence that both calcite precipitation and the major ion balance of waters should be managed in industrially affected ecosystems and we support the development of a hardness+alkalinity guideline for the protection of aquatic life. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

Rigorous patient-prosthesis matching of Perimount Magna aortic bioprosthesis.

Science.gov (United States)

Nakamura, Hiromasa; Yamaguchi, Hiroki; Takagaki, Masami; Kadowaki, Tasuku; Nakao, Tatsuya; Amano, Atsushi

2015-03-01

Severe patient-prosthesis mismatch, defined as effective orifice area index ≤0.65 cm(2) m(-2), has demonstrated poor long-term survival after aortic valve replacement. Reported rates of severe mismatch involving the Perimount Magna aortic bioprosthesis range from 4% to 20% in patients with a small annulus. Between June 2008 and August 2011, 251 patients (mean age 70.5 ± 10.2 years; mean body surface area 1.55 ± 0.19 m(2)) underwent aortic valve replacement with a Perimount Magna bioprosthesis, with or without concomitant procedures. We performed our procedure with rigorous patient-prosthesis matching to implant a valve appropriately sized to each patient, and carried out annular enlargement when a 19-mm valve did not fit. The bioprosthetic performance was evaluated by transthoracic echocardiography predischarge and at 1 and 2 years after surgery. Overall hospital mortality was 1.6%. Only 5 (2.0%) patients required annular enlargement. The mean follow-up period was 19.1 ± 10.7 months with a 98.4% completion rate. Predischarge data showed a mean effective orifice area index of 1.21 ± 0.20 cm(2) m(-2). Moderate mismatch, defined as effective orifice area index ≤0.85 cm(2) m(-2), developed in 4 (1.6%) patients. None developed severe mismatch. Data at 1 and 2 years showed only two cases of moderate mismatch; neither was severe. Rigorous patient-prosthesis matching maximized the performance of the Perimount Magna, and no severe mismatch resulted in this Japanese population of aortic valve replacement patients. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Comet Assay on Daphnia magna in eco-genotoxicity testing.

Science.gov (United States)

Pellegri, Valerio; Gorbi, Gessica; Buschini, Annamaria

2014-10-01

Detection of potentially hazardous compounds in water bodies is a priority in environmental risk assessment. For the evaluation and monitoring of water quality, a series of methodologies may be applied. Among them, the worldwide used toxicity tests with organisms of the genus Daphnia is one of the most powerful. In recent years, some attempts were made to utilize Daphnia magna in genotoxicity testing as many of the new environmental contaminants are described as DNA-damaging agents in aquatic organisms. The aim of this research was to develop a highly standardized protocol of the Comet Assay adapted for D. magna, especially regarding the isolation of cells derived from the same tissue (haemolymph) from newborn organisms exposed in vivo. Several methods for haemolymph extraction and different Comet Assay parameters were compared. Electrophoretic conditions were adapted in order to obtain minimum DNA migration in cells derived from untreated organisms and, at the same time, maximum sensitivity in specimens treated with known genotoxicants (CdCl2 and H2O2). Additional tests were performed to investigate if life-history traits of the cladoceran (such as the age of adult organisms that provide newborns, the clutch size of origin, the number of generations reared in standard conditions) and the water composition as well, might influence the response of the assay. This study confirms the potential application of the Comet Assay in D. magna for assessing genotoxic loads in aqueous solution. The newly developed protocol could integrate the acute toxicity bioassay, thus expanding the possibility of using this model species in freshwater monitoring (waters, sediment and soil elutriates) and is in line with the spirit of the EU Water Framework Directive in reducing the number of bioassays that involve medium-sized species. Copyright © 2014 Elsevier B.V. All rights reserved.

Toxicity of noradrenaline, a novel anti-biofouling component, to two non-target zooplankton species, Daphnia magna and Ceriodaphnia dubia.

Science.gov (United States)

Overturf, C L; Wormington, A M; Blythe, K N; Gohad, N V; Mount, A S; Roberts, A P

2015-05-01

Noradrenaline (NA) is the active component of novel antifouling agents and acts by preventing attachment of fouling organisms. The goal of this study was to examine the toxicity of NA to the non-target zooplankton D. magna and C. dubia. Neonates were exposed to one of five concentrations of NA and effects on survival, reproduction and molting were determined. Calculated LC50 values were determined to be 46 and 38 μM in C. dubia and D. magna, respectively. A 10-day C. dubia study found that reproduction metrics were significantly impacted at non-lethal concentrations. In D. magna, concentrations greater than 40 μM significantly impacted molting. A toxicity test was conducted with D. magna using oxidized NA, which yielded similar results. These data indicate that both NA and oxidized NA are toxic to non-target zooplankton. Results obtained from this study can be used to guide future ecological risk assessments of catecholamine-based antifouling agents. Copyright © 2015. Published by Elsevier Inc.

Performance Evaluation of Manual and Automated (MagNA Pure Nucleic Acid Isolation in HPV Detection and Genotyping Using Roche Linear Array HPV Test

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Aikaterini Chranioti

2011-01-01

Full Text Available Nucleic acids of human papillomavirus (HPV isolated by manual extraction method (AmpliLute and automated MagNA pure system were compared and evaluated with cytohistological findings in 253 women. The concordance level between AmpliLute and MagNA was very good 93.3% (=0.864, <.0001. Overall HPVpositivity detected by AmpliLute was 57.3% (30.4% as single and 27% as multiple infections in contrast to MagNA 54.5% (32% and 23%, resp.. Discrepant results observed in 25 cases: 11 MagNA(−/AmpliLute(+, 10 of which had positive histology; 5 MagNA(+/AmpliLute(− with negative histology; 8 MagNA(+/AmpliLute(+: in 7 of which AmpliLute detected extra HPV genotypes and 1 MagNA(invalid/AmpliLute(+ with positive histology. Both methods performed well when compared against cytological (area under curve (AUC of AmpliLute 0.712 versus 0.672 of MagNA and histological diagnoses (AUC of AmpliLute 0.935 versus 0.877 of MagNA, with AmpliLute showing a slightly predominance over MagNA. However, higher sensitivities, specificities, and positive/negative predictive values were obtained by AmpliLute.

Evaluation of Daphnia magna as an indicator of Toxicity and ...

African Journals Online (AJOL)

Performance evaluation of wastewater treatment plants (WWTPs) with special reference to toxicity reduction using Daphnia magna straus as test organism is very important to study the likely adverse effects of the treated wastewater on the aquatic ecosystem of receiving waters and to detect common environmentally ...

Trophic transfer of gold nanoparticles from Euglena gracilis or Chlamydomonas reinhardtii to Daphnia magna

International Nuclear Information System (INIS)

Lee, Woo-Mi; Yoon, Sung-Ji; Shin, Yu-Jin; An, Youn-Joo

2015-01-01

Understanding the trophic transfer of nanoparticles (NPs) is important because NPs are small enough to easily penetrate into organisms. In this study, we evaluated the trophic transfer of gold NPs (AuNPs) within the aquatic food chain. We observed AuNPs transfer from 2 species of primary producers (Chlamydomonas reinhardtii or Euglena gracilis) to the primary consumer (Daphnia magna). Also, bioaccumulation of AuNPs in E. gracilis was higher than that in C. reinhardtii. The reasons for the difference in Au accumulation may be the physical structure of these organisms, and the surface area that is available for interaction with NPs. C. reinhardtii has a cell wall that may act as a barrier to the penetration of NPs. The size of E. gracilis is larger than that of C. reinhardtii. This study demonstrates the trophic transfer of AuNPs from a general producer to a consumer in an aquatic environment. - Highlights: • This study evaluated the trophic transfer of AuNPs in an aquatic food chain. • Chlamydomonas reinhardtii and Euglena gracilis were selected as the primary producers. • Daphnia magna was used as the primary consumer. • The bioaccumulation of AuNPs in E. gracilis was higher than that in C. reinhardtii. • AuNPs were transferred from C. reinhardtii and E. gracilis to D. magna. - Gold nanoparticles can transfer from primary producers (Chlamydomonas reinhardtii or Euglena gracilis) to the primary consumer (Daphnia magna) in an aquatic environment

Effects of symbiotic bacteria on chemical sensitivity of Daphnia magna.

Science.gov (United States)

Manakul, Patcharaporn; Peerakietkhajorn, Saranya; Matsuura, Tomoaki; Kato, Yasuhiko; Watanabe, Hajime

2017-07-01

The crustacean zooplankton Daphnia magna has been widely used for chemical toxicity tests. Although abiotic factors have been well documented in ecotoxicological test protocols, biotic factors that may affect the sensitivity to chemical compounds remain limited. Recently, we identified symbiotic bacteria that are critical for the growth and reproduction of D. magna. The presence of symbiotic bacteria on Daphnia raised the question as to whether these bacteria have a positive or negative effect on toxicity tests. In order to evaluate the effects of symbiotic bacteria on toxicity tests, bacteria-free Daphnia were prepared, and their chemical sensitivities were compared with that of Daphnia with symbiotic bacteria based on an acute immobilization test. The Daphnia with symbiotic bacteria showed higher chemical resistance to nonylphenol, fenoxycarb, and pentachlorophenol than bacteria-free Daphnia. These results suggested potential roles of symbiotic bacteria in the chemical resistance of its host Daphnia. Copyright © 2017 Elsevier Ltd. All rights reserved.

DEGRADATION AND CONSERVATION OF MARBLE IN THE GREEK ROMAN HADRIANIC BATHS IN LEPTIS MAGNA, LIBYA

OpenAIRE

Nabil.A. ABD EL-TAWAB

2012-01-01

The Hadrianic Baths is one of the most important archaeological sites in Leptis Magna- Libya. It was built at the command of Emperor Hadrian in the early 2nd century CE; they represent some of the most lavish structures of Leptis Magna. It is unique in design and building technique. It was built of limestone, marble and brick. This paper mainly describes the deterioration of marble. The marble in the monuments can be classified into several types, based on its color, texture, chemical composi...

Quantifying sublethal effects of glyphosate and Roundup® to Daphnia magna using a fluorescence based enzyme activity assay and video tracking

DEFF Research Database (Denmark)

Roslev, Peter; R. Hansen, Lone; Ørsted, Michael

Glyphosate (N-(phosphonomethyl)glycine) is the active ingredient in a range of popular broad-spectrum, non-selective herbicide formulations. The toxicity of this herbicide to non-target aquatic organisms such as Daphnia magna is often evaluated using conventional toxicity assays that focus...... on endpoints such as immobility and mortality. In this study, we investigated sublethal effects of glyphosate and Roundup® to D. magna using video tracking for quantifying behavioral changes, and a novel fluorescence based assay for measuring in vivo hydrolytic enzyme activity (FLEA assay). Roundup® exposure...... resulted in concentration-dependent inhibition of alkaline phosphatase activity in D. magna. The inhibition of alkaline phosphatase by Roundup® was temperature-dependent with lowest inhibition at 14 °C and greater inhibition at 20 and 26 °C. Exposure of D. magna to sublethal concentrations of glyphosate...

Action and valence modulate choice and choice-induced preference change.

Directory of Open Access Journals (Sweden)

Raphael Koster

Full Text Available Choices are not only communicated via explicit actions but also passively through inaction. In this study we investigated how active or passive choice impacts upon the choice process itself as well as a preference change induced by choice. Subjects were tasked to select a preference for unfamiliar photographs by action or inaction, before and after they gave valuation ratings for all photographs. We replicate a finding that valuation increases for chosen items and decreases for unchosen items compared to a control condition in which the choice was made post re-evaluation. Whether choice was expressed actively or passively affected the dynamics of revaluation differently for positive and negatively valenced items. Additionally, the choice itself was biased towards action such that subjects tended to choose a photograph obtained by action more often than a photographed obtained through inaction. These results highlight intrinsic biases consistent with a tight coupling of action and reward and add to an emerging understanding of how the mode of action itself, and not just an associated outcome, modulates the decision making process.

High pathogenicity and strong immunogenicity of a Chinese isolate of Eimeria magna Pérard, 1925.

Science.gov (United States)

Tao, Geru; Wang, Yunzhou; Li, Chao; Gu, Xiaolong; Cui, Ping; Fang, Sufang; Suo, Xun; Liu, Xianyong

2017-06-01

Coccidia infection of rabbits with one or several species of parasites of the genus Eimeria causes coccidiosis, a disease leading to huge economic losses in the rabbit industry. Eimeria magna, one of the causal agents of rabbit coccidiosis, was characterized as mildly pathogenic and moderately immunogenic in previous studies. In this study, we identified a Chinese isolate of E. magna by testing its biological features (oocyst morphology and size, prepatent time) and sequencing its internal transcribed spacer 1 (ITS-1) DNA fragment. This isolate is highly pathogenic; infection of rabbits with only 1×10 2 oocysts caused a 55% reduction in weight gain in 14days. In addition, immunization with 1×10 2 oocysts prevented body weight loss against re-infection with 5×10 4 oocysts, indicating the high immunogenicity of this isolate. Our study described the distinctive phenotype of the Chinese isolate of E. magna and contributed to the research of geographic variation of rabbit coccidia. Copyright © 2017 Elsevier B.V. All rights reserved.

Bioavailability and effect of pirimicarb on Daphnia magna in a laboratory freshwater/sediment system

DEFF Research Database (Denmark)

Kusk, K.O.

1996-01-01

In tests with newborn and one-week-old Daphnia magna, 48-h EC(50) values of 21-24 mu g/L and 16 mu g/L pirimicarb, respectively, were found. Older animals thus were as sensitive to pirimicarb as newborn animals. In an experiment with sediment included in the test system, all mother animals survived...... not reduced significantly during the experiment, due to the small amount of sediment used. Accumulation in the sediment was found independent of the water concentration used. This was also the case with bioaccumulation in Daphnia magna, where a bioaccumulation factor of 31-37 was found on a dry weight basis...

Mixture toxicity of flubendazole and fenbendazole to Daphnia magna.

Science.gov (United States)

Puckowski, Alan; Stolte, Stefan; Wagil, Marta; Markiewicz, Marta; Łukaszewicz, Paulina; Stepnowski, Piotr; Białk-Bielińska, Anna

2017-05-01

Nowadays, residual amounts of many pharmaceuticals can be found in various environmental compartments including surface and ground waters, soils and sediments as well as biota. Even though they undergo degradability, their environmental discharge is relatively continuous, thus they may be regarded as quasi-persistent contaminants, and are also frequently regarded as emerging organic pollutants. Benzimidazoles, especially flubendazole (FLU) and fenbendazole (FEN), represent two anthelmintic drugs belonging to this group. Although their presence in environmental matrices has been reported, there is relatively little data concerning their (eco)toxicological impact. Furthermore, no data is available on their mixture toxicity. FLU and FEN have been found to have a strong impact on an environmentally important non-target organism - Daphnia magna. Moreover, these compounds are usually present in the environment as a part of pharmaceutical mixtures. Therefore, there is a need to evaluate their mixture toxicity, which was the main aim of this study. Single substance toxicity tests were carried out in parallel with mixture studies of FLU and FEN, with the application of two well established concepts of Concentration Addition (CA) and Independent Action (IA). As a result, both models (CA and IA) were found to underestimate the toxicity of mixtures, however CA yielded more accurate predictions. Copyright © 2017 Elsevier GmbH. All rights reserved.

Uptake and effects of microplastic textile fibers on freshwater crustacean Daphnia magna.

Science.gov (United States)

Jemec, Anita; Horvat, Petra; Kunej, Urban; Bele, Marjan; Kržan, Andrej

2016-12-01

Microplastic fibers (MP) from textile weathering and washing are increasingly being recognized as environmental pollutants. The majority of studies on the bioavailability and effects of microplastic focused on small polystyrene spherical plastic particles, while less data are available for fibers and for other materials besides polystyrene. We investigated the ingestion and effects of ground polyethylene terephthalate (PET) textile microfibers (length range: 62-1400 μm, width 31-528 μm, thickness 1-21.5 μm) on the freshwater zooplankton crustacean Daphnia magna after a 48 h exposure and subsequent 24 h of recovery in MP free medium and algae. The majority of ingested fibers by D. magna were around 300 μm, but also some very large twisted MP fibers around 1400 μm were found inside the gut. Exposure to these fibers results in increased mortality of daphnids after 48 h only in the case where daphnids were not pre-fed with algae prior to experiment, but no effect was found when daphnids were fed before the experiments. Regardless of the feeding regime, daphnids were not able to recover from MP exposure after additional 24 h incubation period in a MP free medium with algae. The uptake and effects of PET textile MP on D. magna are presented here for the first time. Copyright © 2016 Elsevier Ltd. All rights reserved.

Efficiency in Rule- vs. Plan-Based Movements Is Modulated by Action-Mode.

Science.gov (United States)

Scheib, Jean P P; Stoll, Sarah; Thürmer, J Lukas; Randerath, Jennifer

2018-01-01

The rule/plan motor cognition (RPMC) paradigm elicits visually indistinguishable motor outputs, resulting from either plan- or rule-based action-selection, using a combination of essentially interchangeable stimuli. Previous implementations of the RPMC paradigm have used pantomimed movements to compare plan- vs. rule-based action-selection. In the present work we attempt to determine the generalizability of previous RPMC findings to real object interaction by use of a grasp-to-rotate task. In the plan task, participants had to use prospective planning to achieve a comfortable post-handle rotation hand posture. The rule task used implementation intentions (if-then rules) leading to the same comfortable end-state. In Experiment A, we compare RPMC performance of 16 healthy participants in pantomime and real object conditions of the experiment, within-subjects. Higher processing efficiency of rule- vs. plan-based action-selection was supported by diffusion model analysis. Results show a significant response-time increase in the pantomime condition compared to the real object condition and a greater response-time advantage of rule-based vs. plan-based actions in the pantomime compared to the real object condition. In Experiment B, 24 healthy participants performed the real object RPMC task in a task switching vs. a blocked condition. Results indicate that plan-based action-selection leads to longer response-times and less efficient information processing than rule-based action-selection in line with previous RPMC findings derived from the pantomime action-mode. Particularly in the task switching mode, responses were faster in the rule compared to the plan task suggesting a modulating influence of cognitive load. Overall, results suggest an advantage of rule-based action-selection over plan-based action-selection; whereby differential mechanisms appear to be involved depending on the action-mode. We propose that cognitive load is a factor that modulates the advantageous

Genetically modified rice Bt-Shanyou63 expressing Cry1Ab/c protein does not harm Daphnia magna.

Science.gov (United States)

Zhang, Li; Guo, Ruqing; Fang, Zhixiang; Liu, Biao

2016-10-01

The genetically modified (GM) rice Bt-ShanYou63 (Bt-SY63) received an official biosafety certificate while its safety remained in dispute. In a lifelong study, Daphnia magna were experimentally fed a basal diet of rice flours from Bt-SY63 or its parental rice ShanYou63 (SY63) at concentrations of 0.2mg, 0.3mg, or 0.4mgC (per individual per day). Overall the survival, body size, and reproduction of the animals were comparable between Bt-SY63 and ShanYou63.. The results showed that no significant differences were observed in growth and reproduction parameters between D. magna fed GM and non-GM flour and no dose-related changes occurred in all the values. Based on the different parameters assessed, the GM rice Bt-SY63 is a safe food source for D. magna that does not differ in quality from non-GM rice. Copyright © 2016. Published by Elsevier Inc.

Acute and Chronic Toxicity of Soluble Fractions of Industrial Solid Wastes on Daphnia magna and Vibrio fischeri

Directory of Open Access Journals (Sweden)

Letícia Flohr

2012-01-01

Full Text Available Industrial wastes may produce leachates that can contaminate the aquatic ecosystem. Toxicity testing in acute and chronic levels is essential to assess environmental risks from the soluble fractions of these wastes, since only chemical analysis may not be adequate to classify the hazard of an industrial waste. In this study, ten samples of solid wastes from textile, metal-mechanic, and pulp and paper industries were analyzed by acute and chronic toxicity tests with Daphnia magna and Vibrio fischeri. A metal-mechanic waste (sample MM3 induced the highest toxicity level to Daphnia magna(CE50,48 h=2.21%. A textile waste induced the highest toxicity level to Vibrio fischeri (sample TX2, CE50,30 min=12.08%. All samples of pulp and paper wastes, and a textile waste (sample TX2 induced chronic effects on reproduction, length, and longevity of Daphnia magna. These results could serve as an alert about the environmental risks of an inadequate waste classification method.

Biochemical analysis of plant protection afforded by a nonpathogenic endophytic mutant of Colletotrichum magna

Energy Technology Data Exchange (ETDEWEB)

Redman, R.S.; Rodriguez, R.J. (Geological Survey, Seattle, WA (United States) Univ. of Washington, Seattle, WA (United States). Dept. of Botany); Clifton, D.R.; Morrel, J.; Brown, G. (Geological Survey, Seattle, WA (United States)); Freeman, S. (Volcani Center, Bet Dagan (Israel). Dept. of Plant Pathology)

1999-02-01

A nonpathogenic mutant of Colletotrichum magna (path-1) was previously shown to protect watermelon (Citrullus lanatus) and cucumber (Cucumis sativus) seedlings from anthracnose disease elicited by wild-type C. magna. Disease protection was observed in stems of path-1-colonized cucurbits but not in cotyledons, indicating that path-1 conferred tissue-specific and/or localized protection. Plant biochemical indicators of a localized and systemic (peroxidase, phenylalanine ammonia-lyase, lignin, and salicylic acid) plant-defense response were investigated in anthracnose-resistant and-susceptible cultivars of cucurbit seedlings exposed to four treatments: (1) water (control), (2) path-1 conidia, (3) wild-type conidia, and (4) challenge conditions (inoculation into path-1 conidia for 48 h and then exposure to wild-type conidia). Collectively, these analyses indicated that disease protection in path-1-colonized plants was correlated with the ability of these plants to mount a defense response more rapidly and to equal or greater levels than plants exposed to wild-type C. magna alone. Watermelon plants colonized with path-1 were also protected against disease caused by Colletotrichum orbiculare and Fusarium oxysporum. A model based on the kinetics of plant-defense activation is presented to explain the mechanism of path-1-conferred disease protection.

Daphnia magna fitness during low food supply under different water temperature and brownification scenarios

Directory of Open Access Journals (Sweden)

Andrea Gall

2016-11-01

Full Text Available Much of our current knowledge about non-limiting dietary carbon supply for herbivorous zooplankton is based on experimental evidence and typically conducted at ~1 mg C L-1 and ~20°C. Here we ask how low supply of dietary carbon affects somatic growth, reproduction, and survival of Daphnia magna and test effects of higher water temperature (+3 °C relative to ambient and brownification (3X higher than natural water color; both predicted effects of climate change during fall cooling. We predicted that even at very low carbon supply (~5µg C L-1, higher water temperature and brownification will allow D. magna to increase its fitness. Neonates (<24 h old were incubated with lake seston for 4 weeks (October-November 2013 in experimental bottles submerged in outdoor mesocosms to explore effects of warmer and darker water. Higher temperature and brownification did not significantly affect food quality, as assessed by its fatty acid composition. Daphnia exposed to both increased temperature and brownification had highest somatic growth and were the only that reproduced, and higher temperature caused the highest Daphnia survival success. These results suggest that even under low temperature and thus lower physiological activity, low food quantity is more important than its quality for D. magna fitness.

CRISPR/Cas-mediated knock-in via non-homologous end-joining in the crustacean Daphnia magna.

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Kumagai, Hitoshi; Nakanishi, Takashi; Matsuura, Tomoaki; Kato, Yasuhiko; Watanabe, Hajime

2017-01-01

The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated system (Cas) is widely used for mediating the knock-in of foreign DNA into the genomes of various organisms. Here, we report a process of CRISPR/Cas-mediated knock-in via non-homologous end joining by the direct injection of Cas9/gRNA ribonucleoproteins (RNPs) in the crustacean Daphnia magna, which is a model organism for studies on toxicology, ecology, and evolution. First, we confirmed the cleavage activity of Cas9 RNPs comprising purified Cas9 proteins and gRNAs in D. magna. We used a gRNA that targets exon 10 of the eyeless gene. Cas9 proteins were incubated with the gRNAs and the resulting Cas9 RNPs were injected into D. magna eggs, which led to a typical phenotype of the eyeless mutant, i.e., eye deformity. The somatic and heritable mutagenesis efficiencies were up to 96% and 40%, respectively. Second, we tested the CRISPR/Cas-mediated knock-in of a plasmid by the injection of Cas9 RNPs. The donor DNA plasmid harboring the fluorescent reporter gene was designed to contain the gRNA recognition site. The co-injection of Cas9 RNPs together with the donor DNAs resulted in generation of one founder animal that produced fluorescent progenies. This transgenic Daphnia had donor DNA at the targeted genomic site, which suggested the concurrent cleavage of the injected plasmid DNA and genomic DNA. Owing to its simplicity and ease of experimental design, we suggest that the CRISPR/Cas-mediated knock-in method represents a promising tool for studying functional genomics in D. magna.

Genes mirror geography in Daphnia magna.

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Fields, Peter D; Reisser, Céline; Dukić, Marinela; Haag, Christoph R; Ebert, Dieter

2015-09-01

Identifying the presence and magnitude of population genetic structure remains a major consideration in evolutionary biology as doing so allows one to understand the demographic history of a species as well as make predictions of how the evolutionary process will proceed. Next-generation sequencing methods allow us to reconsider previous ideas and conclusions concerning the distribution of genetic variation, and what this distribution implies about a given species evolutionary history. A previous phylogeographic study of the crustacean Daphnia magna suggested that, despite strong genetic differentiation among populations at a local scale, the species shows only moderate genetic structure across its European range, with a spatially patchy occurrence of individual lineages. We apply RAD sequencing to a sample of D. magna collected across a wide swath of the species' Eurasian range and analyse the data using principle component analysis (PCA) of genetic variation and Procrustes analytical approaches, to quantify spatial genetic structure. We find remarkable consistency between the first two PCA axes and the geographic coordinates of individual sampling points, suggesting that, on a continent-wide scale, genetic differentiation is driven to a large extent by geographic distance. The observed pattern is consistent with unimpeded (i.e. no barriers, landscape or otherwise) migration at large spatial scales, despite the fragmented and patchy nature of favourable habitats at local scales. With high-resolution genetic data similar patterns may be uncovered for other species with wide geographic distributions, allowing an increased understanding of how genetic drift and selection have shaped their evolutionary history. © 2015 John Wiley & Sons Ltd.

Study of the uranium effects on energy budget and population dynamics in Daphnia magna

International Nuclear Information System (INIS)

Massarin, S.

2010-01-01

This work aimed to study effects of uranium on energy budget and population dynamics in Daphnia magna a representative micro-crustacean of freshwater ecosystems. An experimental study of uranium toxicity on physiology (nutrition, respiration) and life history (survival, growth and reproduction) of D. magna was carried out, based on exposures over one, two or three successive generations (F0, F1 and F2) started with neonates from 1. or 5. brood, at 0, 10, 25 and 75 μg U.L -1 . Results showed that toxic effects increased across generations (partially due to daphnid exposure during embryogenesis) and that individuals from 1. brood were more sensitive than individuals from 5. brood. Significant reductions in assimilation rates, measured using a radio-tracing method with 14 C-labelled food, allowed us to identify an effect on assimilation as the mode of action for uranium, in agreement with important damages in the integrity of intestinal epithelium observed by optic microscopy. Integrating results in a dynamic energy budget model (DEBtox) yielded estimated no effect concentrations (NEC) of 9.37, 8.21 and 2.31 μg U.L -1 above which organism functions were altered in generations F0, F1 and F2, respectively. Combining DEBtox with matrix models allowed us to extrapolate consequences on asymptotic population growth rate (λ), a relevant endpoint in an ecological context. Simulations predicted an increase in uranium impact across generations with reduction of λ in F0 and population extinctions at 51-59 μg U.L -1 in F1 and 39-41 μg U.L -1 in F2. Simulations emphasized the importance of considering the most sensitive individuals while determining population response. (author)

Male meiosis in Crustacea: synapsis, recombination, epigenetics and fertility in Daphnia magna.

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Gómez, Rocío; Van Damme, Kay; Gosálvez, Jaime; Morán, Eugenio Sánchez; Colbourne, John K

2016-09-01

We present the first detailed cytological study of male meiosis in Daphnia (Crustacea: Branchiopoda: Cladocera)-an aquatic microcrustacean with a cyclical parthenogenetic life cycle. Using immunostaining of the testes in Daphnia magna for baseline knowledge, we characterized the different stages of meiotic division and spermiogenesis in relation to the distribution of proteins involved in synapsis, early recombination events and sister chromatid cohesion. We also studied post-translational histone modifications in male spermatocytes, in relation to the dynamic chromatin progression of meiosis. Finally, we applied a DNA fragmentation test to measure sperm quality of D. magna, with respect to levels of inbreeding. As a proxy for fertility, this technique may be used to assess the reproductive health of a sentinel species of aquatic ecosystems. Daphnia proves to be a model species for comparative studies of meiosis that is poised to improve our understanding of the cytological basis of sexual and asexual reproduction.

[Comparison of manual and automated (MagNA Pure) nucleic acid isolation methods in molecular diagnosis of HIV infections].

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Alp, Alpaslan; Us, Dürdal; Hasçelik, Gülşen

2004-01-01

Rapid quantitative molecular methods are very important for the diagnosis of human immunodeficiency virus (HIV) infections, assessment of prognosis and follow up. The purpose of this study was to compare and evaluate the performances of conventional manual extraction method and automated MagNA Pure system, for the nucleic acid isolation step which is the first and most important step in molecular diagnosis of HIV infections. Plasma samples of 35 patients in which anti-HIV antibodies were found as positive by microparticule enzyme immunoassay and confirmed by immunoblotting method, were included in the study. The nucleic acids obtained simultaneously by manual isolation kit (Cobas Amplicor, HIV-1 Monitor Test, version 1.5, Roche Diagnostics) and automated system (MagNA Pure LC Total Nucleic Acid Isolation Kit, Roche Diagnostics), were amplified and detected in Cobas Amplicor (Roche Diagnostics) instrument. Twenty three of 35 samples (65.7%) were found to be positive, and 9 (25.7%) were negative by both of the methods. The agreement between the methods were detected as 91.4%, for qualitative results. Viral RNA copies detected by manual and MagNA Pure isolation methods were found between 76.0-7.590.000 (mean: 487.143) and 113.0-20.300.0000 (mean: 2.174.097) copies/ml, respectively. When both of the overall and individual results were evaluated, the number of RNA copies obtained with automatized system, were found higher than the manual method (p<0.05). Three samples which had low numbers of nucleic acids (113, 773, 857, respectively) with MagNA Pure, yielded negative results with manual method. In conclusion, the automatized MagNA Pure system was found to be a reliable, rapid and practical method for the isolation of HIV-RNA.

"Scaffolding" of Action Learning within a Part-Time Management Development Module

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Joesbury, Mark

2015-01-01

This Account of Practice describes the introduction and development of action learning within a level 5 module of "Communications at Work" delivered as part of a Business & Technology Education Council (BTEC) Professional Certificate in Management (CMS) between 2005/2006 and 2009/2010. This will commence with a personal narrative and…

Automated extraction of genomic DNA from medically important yeast species and filamentous fungi by using the MagNA Pure LC system.

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Loeffler, Juergen; Schmidt, Kathrin; Hebart, Holger; Schumacher, Ulrike; Einsele, Hermann

2002-06-01

A fully automated assay was established for the extraction of DNA from clinically important fungi by using the MagNA Pure LC instrument. The test was evaluated by DNA isolation from 23 species of yeast and filamentous fungi and by extractions (n = 28) of serially diluted Aspergillus fumigatus conidia (10(5) to 0 CFU/ml). Additionally, DNA from 67 clinical specimens was extracted and compared to the manual protocol. The detection limit of the MagNA Pure LC assay of 10 CFU corresponded to the sensitivity when DNA was extracted manually; in 9 of 28 runs, we could achieve a higher sensitivity of 1 CFU/ml blood, which was found to be significant (p DNA from all fungal species analyzed could be extracted and amplified by real-time PCR. Negative controls from all MagNA Pure isolations remained negative. Sixty-three clinical samples showed identical results by both methods, whereas in 4 of 67 samples, discordant results were obtained. Thus, the MagNA Pure LC technique offers a fast protocol for automated DNA isolation from numerous fungi, revealing high sensitivity and purity.

Better Alone or in Ill Company? The Effect of Migration and Inter-Species Comingling on Fascioloides magna Infection in Elk.

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Pruvot, Mathieu; Lejeune, Manigandan; Kutz, Susan; Hutchins, Wendy; Musiani, Marco; Massolo, Alessandro; Orsel, Karin

2016-01-01

Migratory movements and alteration of host communities through livestock production are examples of ecological processes that may have consequences on wildlife pathogens. We studied the effect of co-grazing of cattle and wild elk, and of elk migratory behaviour on the occurrence of the giant liver fluke, Fascioloides magna, in elk. Migratory elk and elk herds with a higher proportion of migratory individuals were significantly less likely to be infected with F. magna. This may indicate a decreased risk of infection for migratory individuals, known as the "migratory escape" hypothesis. Elk herds overlapping with higher cattle densities also had a lower prevalence of this parasite, even after adjustment for landscape and climate variables known to influence its life cycle. Serological evidence suggests that even in low-prevalence areas, F. magna is circulating in both elk and cattle. Cattle are "dead-end" hosts for F. magna, and this may, therefore, indicate a dilution effect where cattle and elk are co-grazing. Migratory behaviour and host community composition have significant effects on the dynamics of this wildlife parasite; emphasizing the potential impacts of decisions regarding the management of migratory corridors and livestock-wildlife interface.

Better Alone or in Ill Company? The Effect of Migration and Inter-Species Comingling on Fascioloides magna Infection in Elk.

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Mathieu Pruvot

Full Text Available Migratory movements and alteration of host communities through livestock production are examples of ecological processes that may have consequences on wildlife pathogens. We studied the effect of co-grazing of cattle and wild elk, and of elk migratory behaviour on the occurrence of the giant liver fluke, Fascioloides magna, in elk. Migratory elk and elk herds with a higher proportion of migratory individuals were significantly less likely to be infected with F. magna. This may indicate a decreased risk of infection for migratory individuals, known as the "migratory escape" hypothesis. Elk herds overlapping with higher cattle densities also had a lower prevalence of this parasite, even after adjustment for landscape and climate variables known to influence its life cycle. Serological evidence suggests that even in low-prevalence areas, F. magna is circulating in both elk and cattle. Cattle are "dead-end" hosts for F. magna, and this may, therefore, indicate a dilution effect where cattle and elk are co-grazing. Migratory behaviour and host community composition have significant effects on the dynamics of this wildlife parasite; emphasizing the potential impacts of decisions regarding the management of migratory corridors and livestock-wildlife interface.

Nano-TiO2 enhances the toxicity of copper in natural water to Daphnia magna

International Nuclear Information System (INIS)

Fan Wenhong; Cui Minming; Liu Hong; Wang Chuan; Shi Zhiwei; Tan Cheng; Yang Xiuping

2011-01-01

The acute toxicity of engineered nanoparticles (NPs) in aquatic environments at high concentrations has been well-established. This study demonstrates that, at a concentration generally considered to be safe in the environment, nano-TiO 2 remarkably enhanced the toxicity of copper to Daphnia magna by increasing the copper bioaccumulation. Specifically, at 2 mg L -1 nano-TiO 2 , the (LC 50 ) of Cu 2+ concentration observed to kill half the population, decreased from 111 μg L -1 to 42 μg L -1 . Correspondingly, the level of metallothionein decreased from 135 μg g -1 wet weight to 99 μg g -1 wet weight at a Cu 2+ level of 100 μg L -1 . The copper was found to be adsorbed onto the nano-TiO 2 , and ingested and accumulated in the animals, thereby causing toxic injury. The nano-TiO 2 may compete for free copper ions with sulfhydryl groups, causing the inhibition of the detoxification by metallothioneins. - Research highlights: → This study demonstrates that, at a concentration generally considered to be safe in the environment, nano-TiO 2 remarkably enhanced the toxicity of copper to Daphnia magna. → The copper was found to be adsorbed onto the nano-TiO 2 , and ingested and accumulated in the Daphnia magna, thereby causing toxic injury. → The nano-TiO 2 may compete for free copper ions with sulfhydryl groups, causing the inhibition of the detoxification mechanism of metallothionein. - The nano-TiO 2 remarkably enhanced the toxicity of copper to Daphnia magna. The nano-TiO 2 may compete for free copper ions with sulfhydryl groups, causing the inhibition of the detoxification mechanism of metallothionein.

Cytokine modulation by glucocorticoids: mechanisms and actions in cellular studies.

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Brattsand, R; Linden, M

1996-01-01

Glucocorticoids inhibit the expression and action of most cytokines. This is part of the in vivo feed-back system between inflammation-derived cytokines and CNS-adrenal produced corticosteroids with the probable physiological relevance to balance parts of the host defence and anti-inflammatory systems of the body. Glucocorticoids modulate cytokine expression by a combination of genomic mechanisms. The activated glucocorticoid-receptor complex can (i) bind to and inactivate key proinflammatory transcription factors (e.g. AP-1, NF kappa B). This takes place at the promotor responsive elements of these factors, but has also been reported without the presence of DNA; (ii) via glucocorticoid responsive elements (GRE), upregulate the expression of cytokine inhibitory proteins, e.g. I kappa B, which inactivates the transcription factor NF kappa B and thereby the secondary expression of a series of cytokines; (iii) reduce the half-life time and utility of cytokine mRNAs. In studies with triggered human blood mononuclear cells in culture, glucocorticoids strongly diminish the production of the 'initial phase' cytokines IL-1 beta and TNF-alpha and the 'immunomodulatory' cytokines IL-2, IL-3, IL-4, IL-5, IL-10, IL-12 and IFN-gamma, as well as of IL-6, IL-8 and the growth factor GM-CSF. While steroid treatment broadly attenuates cytokine production, it cannot modulate it selectively, e.g. just the TH0, the TH1 or the TH2 pathways. The production of the 'anti-inflammatory' IL-10 is also inhibited. The exceptions of steroid down-regulatory activity on cytokine expression seem to affect 'repair phase' cytokines like TGF-beta and PDGF. These are even reported to be upregulated, which may explain the rather weak steroid dampening action on healing and fibrotic processes. Some growth factors, e.g. G-CSF and M-CSF, are only weakly affected. In addition to diminishing the production of a cytokine, steroids can also often inhibit its subsequent actions. Because cytokines work in

Mechanistic study of the toxicity of ionizing radiation in Daphnia magna

Energy Technology Data Exchange (ETDEWEB)

Parisot, F.; Alonzo, F. [Institut de Radioprotection et de Surete Nucleaire, IRSN/PRP-ENV/SERIS/LECO, Laboratoire d' Ecotoxicologie des Radionucleides, Cadarache (France); Bourdineaud, J.P. [UMR CNRS 5805 EPOC - OASU Station Marine d' Arcachon Universite Bordeaux 1, Arcachon (France); Poggiale, J.C. [Mediterranean Institute of Oceanography - MIO - UMR 7294 Pytheas Institute - OSU, Aix-Marseille University, Marseille (France)

2014-07-01

In the last decade, the ecological impact of ionizing radiation has emerged as a growing scientific concern for ecosystems protection. However, the assessment of potential radiological effects on the environment is hampered by both a gap of available scientific data and a lack in proven methods. Understanding how ionizing radiation affects wildlife at biologically and ecologically relevant scales is a major issue in environmental protection. This issue is one of the objectives of the Strategic Research Agenda (SRA) developed in the framework of the European program STAR (Strategy for Allied Radioecology). In this context, the present PhD project aims to evaluate chronic effects of external Cs-137 gamma radiation at low doses on a representative species of aquatic ecosystems, the cladoceran crustacean Daphnia magna. More precisely, the objectives of this study are to evaluate multi-generational effects of irradiation on: (i) genotoxic effects and their potential consequences on survival, somatic growth and fecundity, (ii) the energy budget and (iii) the population dynamics of Daphnia. An experimental design was developed to expose daphnids to low doses of ionizing radiation ranging from 0,008 to 32 mGy.h{sup -1} across 3 successive generations (75 days). DNA damages were assessed using random amplified polymorphic DNA and real time PCR (RAPD - PCR). Effects on survival, somatic growth and fecundity were monitored for 21-25 days in each generation, from hatching to release of brood 5. Our aim is to: examine a potential correlation between molecular (DNA) damage and effects observed at the individual level (survival, somatic growth and fecundity) across generations and test the suitability of DNA damage as an early indice of future trans-generational effects. As a future perspective, individual and molecular effects data will be analysed using a DEBtox model (Dynamic Energy Budget Applied to Toxicology) in order to identify the metabolic modes of action of ionizing

Promoting effects on reproduction increase population vulnerability of Daphnia magna.

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Agatz, Annika; Hammers-Wirtz, Monika; Gabsi, Faten; Ratte, Hans Toni; Brown, Colin D; Preuss, Thomas G

2012-07-01

Environmental risk assessment of chemicals is based on single species tests at the individual level with single compounds. However, the protection goal is the sustainability of a population, which faces several natural stressors and mixtures of chemicals in the environment. Therefore, experiments were undertaken to quantify the combined effects of chemicals with different modes of action on Daphnia magna populations. Populations continuously exposed to dispersogen A and at abundance equilibrium were treated with a 2-d pulse of p353-nonylphenol. In previous studies, dispersogen A was shown to act as a natural info-chemical, promoting the reproduction of daphnids (higher offspring quantity) coupled with reduced offspring fitness, whereas nonylphenol in pulsed-exposure caused size-selective mortality. Dispersogen A caused accelerated population growth to maximum abundance, shifted the population structure towards smaller individuals, and increased the population sensitivity to nonylphenol. The authors showed that a positive effect observed at the individual level can be transposed to a negative effect when monitored at the population level. So far, positive effects are not addressed in environmental risk assessment, and even in higher-tier testing, population structure is not quantified. Both factors indicate a potential mismatch between protection aim and risk assessment practice. Copyright © 2012 SETAC.

Food mediated life history strategies in Daphnia magna : their relevance to ecotoxicological evaluations

NARCIS (Netherlands)

Enserink, E.L.

1995-01-01

The waterflea Daphnia magna is a widely used test organism in ecotoxicological studies. Acute and chronic laboratory tests yield basic information for the development of water quality standards, assessment of potential hazards of (new) chemicals, waste water licences and

Toxicity of tetramethylammonium hydroxide to aquatic organisms and its synergistic action with potassium iodide.

Science.gov (United States)

Mori, Izumi C; Arias-Barreiro, Carlos R; Koutsaftis, Apostolos; Ogo, Atsushi; Kawano, Tomonori; Yoshizuka, Kazuharu; Inayat-Hussain, Salmaan H; Aoyama, Isao

2015-02-01

The aquatic ecotoxicity of chemicals involved in the manufacturing process of thin film transistor liquid crystal displays was assessed with a battery of four selected acute toxicity bioassays. We focused on tetramethylammonium hydroxide (TMAH, CAS No. 75-59-2), a widely utilized etchant. The toxicity of TMAH was low when tested in the 72 h-algal growth inhibition test (Pseudokirchneriellia subcapitata, EC50=360 mg L(-1)) and the Microtox® test (Vibrio fischeri, IC50=6.4 g L(-1)). In contrast, the 24h-microcrustacean immobilization and the 96 h-fish mortality tests showed relatively higher toxicity (Daphnia magna, EC50=32 mg L(-1) and Oryzias latipes, LC50=154 mg L(-1)). Isobologram and mixture toxicity index analyses revealed apparent synergism of the mixture of TMAH and potassium iodide when examined with the D. magna immobilization test. The synergistic action was unique to iodide over other halide salts i.e. fluoride, chloride and bromide. Quaternary ammonium ions with longer alkyl chains such as tetraethylammonium and tetrabutylammonium were more toxic than TMAH in the D. magna immobilization test. Copyright © 2014 Elsevier Ltd. All rights reserved.

Modulation of motor cortex excitability by physical similarity with an observed hand action.

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Marie-Christine Désy

Full Text Available The passive observation of hand actions is associated with increased motor cortex excitability, presumably reflecting activity within the human mirror neuron system (MNS. Recent data show that in-group ethnic membership increases motor cortex excitability during observation of culturally relevant hand gestures, suggesting that physical similarity with an observed body part may modulate MNS responses. Here, we ask whether the MNS is preferentially activated by passive observation of hand actions that are similar or dissimilar to self in terms of sex and skin color. Transcranial magnetic stimulation-induced motor evoked potentials were recorded from the first dorsal interosseus muscle while participants viewed videos depicting index finger movements made by female or male participants with black or white skin color. Forty-eight participants equally distributed in terms of sex and skin color participated in the study. Results show an interaction between self-attributes and physical attributes of the observed hand in the right motor cortex of female participants, where corticospinal excitability is increased during observation of hand actions in a different skin color than that of the observer. Our data show that specific physical properties of an observed action modulate motor cortex excitability and we hypothesize that in-group/out-group membership and self-related processes underlie these effects.

Lethal/sublethal responses of Daphnia magna to acute norfloxacin contamination and changes in phytoplankton-zooplankton interactions induced by this antibiotic

Science.gov (United States)

Pan, Ying; Yan, Shi-Wei; Li, Ruo-Zhu; Hu, Yi-Wen; Chang, Xue-Xiu

2017-01-01

Although the well-known antibiotic norfloxacin (NOR) is recognized as an important environmental pollutant, little is known about its impacts on ecological processes, particularly on species interactions. In this paper, we quantified Daphnia magna (Crustacea, Cladocera) responses in mortality rate at lethal NOR concentrations (0, 25, 50, 100, 200, 300 and 400 mg L-1), and in heartbeat rate, swimming behavior and feeding rate (on the green alga Chlorella pyrenoidosa) at sublethal NOR concentrations (0, 25, 50 and 100 mg L-1) to determine the effects of this antibiotic in plankton systems. In 96-h-long lethal experiment, mortality rates of D. magna increased significantly with increasing NOR concentration and exposure time. In sublethal experiments, heartbeat rate decreased, while time ratio of vertical to horizontal swimming (TVH) and the duration of quiescence increased in D. magna individuals exposed to increasing NOR concentrations after 4 and 12 h of exposure. These collectively led to decreases in both average swimming ability and feeding rate, consistent with the positive relationship between average swimming ability and feeding rate. Overall, results indicate that, by affecting zooplankton heartbeat rate and behavior, NOR decreased feeding efficiency of D. magna even at low doses, therefore, it might seriously compromise ecosystem health and function.

Ghrelin and Ghrelin Receptor Modulation of Psychostimulant Action

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Paul Jeff Wellman

2013-09-01

Full Text Available Ghrelin (GHR is an orexigenic gut peptide that modulates multiple homeostatic functions including gastric emptying, anxiety, stress, memory, feeding and reinforcement. GHR is known to bind and activate growth-hormone secretagogue receptors (termed GHR-Rs. Of interest to our laboratory has been the assessment of the impact of GHR modulation of the locomotor activation and reward/reinforcement properties of psychostimulants such as cocaine and nicotine. Systemic GHR infusions augment cocaine stimulated locomotion and conditioned place preference (CPP in rats, as does food restriction which elevates plasma ghrelin levels. Ghrelin enhancement of psychostimulant function may occur owing to a direct action on mesolimbic dopamine function or may reflect an indirect action of ghrelin on glucocorticoid pathways. Genomic or pharmacological ablation of GHR-Rs attenuates the acute locomotor-enhancing effects of nicotine, cocaine, amphetamine and alcohol and blunts the CPP induced by food, alcohol, amphetamine and cocaine in mice. The stimulant nicotine can induce CPP and like amphetamine and cocaine, repeated administration of nicotine induces locomotor sensitization in rats. Inactivation of ghrelin circuit function in rats by injection of a ghrelin receptor antagonist (e.g. JMV 2959 diminishes the development of nicotine-induced locomotor sensitization. These results suggest a key permissive role for GHR-R activity for the induction of locomotor sensitization to nicotine. Our finding that GHR-R null rats exhibit diminished patterns of responding for intracranial self-stimulation complements an emerging literature implicating central GHR circuits in drug reward/reinforcement. Finally, antagonism of GHR-Rs may represent a smoking cessation modality that not only blocks nicotine-induced reward but that also may limit weight gain after smoking cessation.

Successfully resisting a pathogen is rarely costly in Daphnia magna.

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Labbé, Pierrick; Vale, Pedro F; Little, Tom J

2010-11-17

A central hypothesis in the evolutionary ecology of parasitism is that trade-offs exist between resistance to parasites and other fitness components such as fecundity, growth, survival, and predator avoidance, or resistance to other parasites. These trade-offs are called costs of resistance. These costs fall into two broad categories: constitutive costs of resistance, which arise from a negative genetic covariance between immunity and other fitness-related traits, and inducible costs of resistance, which are the physiological costs incurred by hosts when mounting an immune response. We sought to study inducible costs in depth using the crustacean Daphnia magna and its bacterial parasite Pasteuria ramosa. We designed specific experiments to study the costs induced by exposure to this parasite, and we re-analysed previously published data in an effort to determine the generality of such costs. However, despite the variety of genetic backgrounds of both hosts and parasites, and the different exposure protocols and environmental conditions used in these experiment, this work showed that costs of exposure can only rarely be detected in the D. magna-P. ramosa system. We discuss possible reasons for this lack of detectable costs, including scenarios where costs of resistance to parasites might not play a major role in the co-evolution of hosts and parasites.

Greek perceptions of frontier in Magna Graecia: literature and archaeology in dialogue

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Airton POLLINI

2013-07-01

Full Text Available The paper deals with Greek perceptions of frontier in Magna Graecia, from a historical archaeological, contextual standpoint. Considering the complex relationship between literary and archaeological evidence, the paper uses as a case study the frontier in Southern Italy, discussing the subjective frontier perceptions by Greeks and Natives in interaction.

The efficacy of intraoperative ultrasonography-assisted microinvasive cisterna magna reconstruction for Chiari malformation typeⅠwith syringomyelia

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LI Peng-chao

2012-08-01

Full Text Available Objective To report the method and effect of intraoperative ultrasonography-assisted microinvasive cisterna magna reconstruction for Chiari malformation type Ⅰ with syringomyelia. Methods Ninty-three patients suffered from Chiari malformation typeⅠwith syringomyelia were treated by microinvasive cisterna magna reconstruction. The skin incision was 1.50-3.00 cm. The bone removal of foramen magnum was 1.50 cm × 2.00 cm with C1 reserved. Dura and arachnoid were incised and sutured linearly. All of the patients underwent cerebellar tonsillar resection and exploration of median aperture of fourth ventricle. Intraoperative ultrasonography was performed both before and after cerebellar tonsillar resection to judge the effect of cisterna magna reconstruction. According to Tator method, the curative effect was divided into 3 groups, improved, stable and worsen. MRI were reviewed at the same time, and the result was divided into syrinx disappeared, reduced, no change and expanded. Results The operation was successful in all patients. Postoperative complications included cerebellum hemorrhage (n = 1, cerebral infarction (n = 1, hydrocephalus (n = 1, subcutaneous dropsy (n = 2 and were recovered after specific treatment. All patients were followed up for 6 months to 12 months after operation. Thirty-six cases were improved, 55 cases were stable, and 2 cases got worse. The MRI showed that the syringomyelia shrinked or disappeared in 90 cases, no change in 3 cases and no expansion. Eighty cases were followed up for 30 months to 36 months after operation, 12 stable cases improved, 1 stable case got worse, while the others remained unchanged. The MRI showed no change was compared with previous follow-up imaging. Conclusion Microinvasive cisterna magna reconstruction is a surgical procedure with mininal injury, quick recovery, stable effect, fewer complications, and high security. Intraoperative ultrasonography provides reliable data and is easy to perform.

A comparison of the response of Simocephalus mixtus (Cladocera) and Daphnia magna to contaminated freshwater sediments.

Science.gov (United States)

Martínez-Jerónimo, Fernando; Cruz-Cisneros, Jade Lizette; García-Hernández, Leonardo

2008-09-01

The southeast region of Mexico is characterized by intensive oil industry activities carried out by the national public enterprise Petróleos Mexicanos (PEMEX). The freshwater lagoon "El Limón", located in the municipality of Macuspana, state of Tabasco, Mexico, has received over 40 years discharges of untreated waste waters from the Petrochemical Complex "Ciudad PEMEX", located on the border of the lagoon. To assess the toxicity of the sediments and, hence, to obtain information on the biological effects of these contaminating discharges, the cladoceran Simocephalus mixtus was used as a test organism in acute (48h) and chronic (12d) toxicity assays. For comparison purposes, bioassays were also conducted with the reference cladoceran Daphnia magna. The sediments of this lagoon contain important amounts of metals and hydrocarbons that have been accumulated over time; however, the acute tests only registered reduced lethal effects on the test organisms (maxima of 10% and 17% mortality for D. magna and S. mixtus, respectively). This may be due to low bioavailability of the pollutants present in the sediments. On the other hand, partial or total inhibition and delay in the start of reproduction, reduction in clutch sizes, reduced survival, as well as reduction in the size of adults and offspring were recorded in the chronic assays. The most evident chronic effects were found in S. mixtus; in this species, reproduction was inhibited up to 72%, whereas D. magna was only affected by 24%. We determined that S. mixtus is a more sensitive test organism than D. magna to assess whole-sediment toxicity in tropical environments, and that chronic exposure bioassays are required for an integrated sediment evaluation. The sediments from "El Limón" lagoon induced chronic intoxication responses and, therefore, remediation measures are urgently needed to recover environmental conditions suitable for the development of its aquatic biota.

Effects of aqueous stable fullerene nanocrystals (nC60) on the food conversion from Daphnia magna to Danio rerio in a simplified freshwater food chain.

Science.gov (United States)

Tao, Xianji; Li, Cuilan; Zhang, Bo; He, Yiliang

2016-02-01

Understanding the nanomaterial potential to the food conversion of two food chain levels is important in the ecosystem assessment as manufactured nanomaterials are being released into the environment. In this investigation, the food conversion from Daphnia magna (D. magna) (prey) to Danio rerio (D. rerio) (predator) was used as the study object of aqueous stable fullerene nanocrystals (nC60). Accumulated nC60 of D. magna was determined as the nominal initial exposure concentration for D. rerio. The results of 21-d dietary exposure experiment demonstrate that nC60 in D. magna decreased the body weight growths and condition factors of D. rerio, and reduced the food conversion ratio by 20% (from D. magna to D. rerio). Further, the experiments present that nC60 decrease three digestive enzymes activities of trypsinase, lipase, and amylase by 30, 29, and 55% in vivo, and by 60, 90, and 42% in vitro, respectively. Both in vivo and in vitro experiments indicated that nC60 was involved with the decrements of digestive enzymes activities. These decrements in digestive enzymes activities may be due to the deactivation caused by the adsorption of nC60 particles onto the surface or active center of digestive enzymes. Sum up, these results not only describe the nC60 deleterious effects on the food conversion from D. magna to D. rerio, but also provide some information regarding a probable food conversion inhibition mechanism of nC60. Copyright © 2015 Elsevier Ltd. All rights reserved.

Toxicity Identification and Evaluation for the Effluent from Wastewater Treatment Plant in Industrial Complex using D.magna

Science.gov (United States)

Lee, S.; Keum, H.; Chun Sang, H.

2015-12-01

In recent years, the interests on the impacts of industrial wastewater on aquatic ecosystem have increased with concern about ecosystem protection and human health. Whole effluent toxicity tests are used to monitor toxicity by unknown toxic chemicals as well as conventional pollutants from industrial effluent discharges. This study describes the application of TIE (toxicity identification evaluation) procedures to an acutely toxic effluent from a wastewater treatment plant in industrial complex which was toxic to Daphnia magna. In TIE phase I (characterization step), the toxic effects by heavy metals, organic compounds, oxidants, volatile organic compounds, suspended solids and ammonia were screened and revealed that the source of toxicity is far from these toxicants group. Chemical analysis (TIE phase II) on TDS showed that the concentration of chloride ion (6,900 mg/L) was substantially higher than that predicted from EC50 for D. magna. In confirmation step (TIE phase III), chloride ion was demonstrated to be main toxicant in this effluent by the spiking approach, species sensitivity approach and deletion approach. Calcium, potassium, magnesium, sodium, fluorine, sulfate ion concentration (450, 100, 80, 5,300, 0.66, 2,200mg/L) was not shown toxicity from D. magna. Finally, we concluded that chloride was the most contributing toxicant in the waste water treatment plant. Further research activities are needed for technical support of toxicity identification and evaluation on the various types of wastewater treatment plant discharge in Korea. Keywords : TIE, D. magna, Industrial waste water Acknowledgement This research was supported by a grant (15IFIP-B089908-02) from Plant Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government

Ultrasound guided double injection of blood into cisterna magna: a rabbit model for treatment of cerebral vasospasm.

Science.gov (United States)

Chen, Yongchao; Zhu, Youzhi; Zhang, Yu; Zhang, Zixuan; Lian, Juan; Luo, Fucheng; Deng, Xuefei; Wong, Kelvin K L

2016-02-06

Double injection of blood into cisterna magna using a rabbit model results in cerebral vasospasm. An unacceptably high mortality rate tends to limit the application of model. Ultrasound guided puncture can provide real-time imaging guidance for operation. The aim of this paper is to establish a safe and effective rabbit model of cerebral vasospasm after subarachnoid hemorrhage with the assistance of ultrasound medical imaging. A total of 160 New Zealand white rabbits were randomly divided into four groups of 40 each: (1) manual control group, (2) manual model group, (3) ultrasound guided control group, and (4) ultrasound guided model group. The subarachnoid hemorrhage was intentionally caused by double injection of blood into their cisterna magna. Then, basilar artery diameters were measured using magnetic resonance angiography before modeling and 5 days after modeling. The depth of needle entering into cisterna magna was determined during the process of ultrasound guided puncture. The mortality rates in manual control group and model group were 15 and 23 %, respectively. No rabbits were sacrificed in those two ultrasound guided groups. We found that the mortality rate in ultrasound guided groups decreased significantly compared to manual groups. Compared with diameters before modeling, the basilar artery diameters after modeling were significantly lower in manual and ultrasound guided model groups. The vasospasm aggravated and the proportion of severe vasospasms was greater in ultrasound guided model group than that of manual group. In manual model group, no vasospasm was found in 8 % of rabbits. The ultrasound guided double injection of blood into cisterna magna is a safe and effective rabbit model for treatment of cerebral vasospasm.

Obesogens beyond Vertebrates: Lipid Perturbation by Tributyltin in the Crustacean Daphnia magna

Science.gov (United States)

Jordão, Rita; Casas, Josefina; Fabrias, Gemma; Campos, Bruno; Piña, Benjamín; Lemos, Marco F.L.; Soares, Amadeu M.V.M.; Tauler, Romà

2015-01-01

Background The analysis of obesogenic effects in invertebrates is limited by our poor knowledge of the regulatory pathways of lipid metabolism. Recent data from the crustacean Daphnia magna points to three signaling hormonal pathways related to the molting and reproductive cycles [retinoic X receptor (RXR), juvenile hormone (JH), and ecdysone] as putative targets for exogenous obesogens. Objective The present study addresses the disruptive effects of the model obesogen tributyltin (TBT) on the lipid homeostasis in Daphnia during the molting and reproductive cycle, its genetic control, and health consequences of its disruption. Methods D. magna individuals were exposed to low and high levels of TBT. Reproductive effects were assessed by Life History analysis methods. Quantitative and qualitative changes in lipid droplets during molting and the reproductive cycle were studied using Nile red staining. Lipid composition and dynamics were analyzed by ultra-performance liquid chromatography coupled to a time-of-flight mass spectrometer. Relative abundances of mRNA from different genes related to RXR, ecdysone, and JH signaling pathways were studied by qRT-PCR. Results and Conclusions TBT disrupted the dynamics of neutral lipids, impairing the transfer of triacylglycerols to eggs and hence promoting their accumulation in adult individuals. TBT’s disruptive effects translated into a lower fitness for offspring and adults. Co-regulation of gene transcripts suggests that TBT activates the ecdysone, JH, and RXR receptor signaling pathways, presumably through the already proposed interaction with RXR. These findings indicate the presence of obesogenic effects in a nonvertebrate species. Citation Jordão R, Casas J, Fabrias G, Campos B, Piña B, Lemos MF, Soares AM, Tauler R, Barata C. 2015. Obesogens beyond vertebrates: lipid perturbation by tributyltin in the crustacean Daphnia magna. Environ Health Perspect 123:813–819; http://dx.doi.org/10.1289/ehp.1409163 PMID

Nutritional value content, biomass production and growth performance of Daphnia magna cultured with different animal wastes resulted from probiotic bacteria fermentation

Science.gov (United States)

Endar Herawati, Vivi; Nugroho, R. A.; Pinandoyo; Hutabarat, Johannes

2017-02-01

Media culture is an important factor for the growth and quality of Daphnia magna nutrient value. This study has purpose to find the increasing of nutritional content, biomass production and growth performance of D. magna using different animal wastes fermented by probiotic bacteria. This study conducted using completely randomized experimental design with 10 treatments and 3 replicates. Those media used different animal manures such as chicken manure, goat manure and quail manure mixed by rejected bread and tofu waste fermented by probiotic bacteria then cultured for 24 days. The results showed that the media which used 50% chicken manure, 100% rejected bread and 50% tofu waste created the highest biomass production, population and nutrition content of D.magna about 2111788.9 ind/L for population; 342 grams biomass production and 68.85% protein content. The highest fatty acid profile is 6.37% of linoleic and the highest essential amino acid is 22.8% of lysine. Generally, the content of ammonia, DO, temperature, and pH during the study were in the good range of D. magna’s life. This research has conclusion that media used 50% chicken manure, 100% rejected bread and 50% tofu waste created the highest biomass production, population and nutrition content of D. magna.

Copper regulation and homeostasis of Daphnia magna and Pseudokirchneriella subcapitata: influence of acclimation

International Nuclear Information System (INIS)

Bossuyt, Bart T.A.; Janssen, Colin R.

2005-01-01

This study aimed to evaluate (1) the capacity of the green alga Pseudokirchneriella subcapitata and the waterflea Daphnia magna to regulate copper when exposed to environmentally realistic copper concentrations and (2) the influence of multi-generation acclimation to these copper concentrations on copper bioaccumulation and homeostasis. Based on bioconcentration factors, active copper regulation was observed in algae up to 5 μg Cu L -1 and in daphnids up to 35 μg Cu L -1 . Constant body copper concentrations (13 ± 4 μg Cu g DW -1 ) were observed in algae exposed to 1 through 5 μg Cu L -1 and in daphnids exposed to 1 through 12 μg Cu L -1 . At higher exposure concentrations, there was an increase in internal body copper concentration, while no increase was observed in bioconcentration factors, suggesting the presence of a storage mechanism. At copper concentrations of 100 μg Cu L -1 (P. subcapitata) and 150 μg Cu L -1 (D. magna), the significant increases observed in body copper concentrations and in bioconcentration factors may be related to a failure of this regulation mechanism. For both organisms, internal body copper concentrations lower than 13 μg Cu g DW -1 may result in copper deficiency. For P. subcapitata acclimated to 0.5 and 100 μg Cu L -1 , body copper concentrations ranged (mean ± standard deviation) between 5 ± 2 μg Cu g DW -1 and 1300 ± 197 μg Cu g DW -1 , respectively. For D. magna, this value ranged between 9 ± 2 μg Cu g DW -1 and 175 ± 17 μg Cu g DW -1 for daphnids acclimated to 0.5 and 150 μg Cu L -1 . Multi-generation acclimation to copper concentrations ≥12 μg Cu L -1 resulted in a decrease (up to 40%) in body copper concentrations for both organisms compared to the body copper concentration of the first generation. It can be concluded that there is an indication that P. subcapitata and D. magna can regulate their whole body copper concentration to maintain copper homeostasis within their optimal copper range and

Effects of Cylindrospermopsis raciborskii and Aphanizomenon ovalisporum (cyanobacteria) ingestion on Daphnia magna midgut and associated diverticula epithelium

International Nuclear Information System (INIS)

Nogueira, Isabel C.G.; Lobo-da-Cunha, Alexandre; Vasconcelos, Vitor M.

2006-01-01

This article reports a light and electron microscopy investigation of the effects of Cylindrospermopsis raciborskii and Aphanizomenon ovalisporum ingestion on midgut and associated digestive diverticula of Daphnia magna. Additionally, survivorship and growth effects caused by feeding on cyanobacteria were assessed. Three cyanobacteria were used in the experiments: cylindrospermopsin (CYN)-producing C. raciborskii, CYN-producing A. ovalisporum and non-CYN-producing C. raciborskii. In order to discriminate between the alterations due to the low nutritional value of cyanobacteria and toxic effects, a control group was fed on the chlorophyte Ankistrodesmus falcatus and another control group was not fed. In the chlorophyte fed control, the epithelium lining the midgut and associated diverticula is mainly formed by strongly stained cells with an apical microvilli border. Nevertheless, unstained areas in which cell lyses had occurred were also observed. In the unfed control, the unstained areas became predominant due to an increment of cell lyses. All individuals fed on CYN-producing A. ovalisporum and some of those fed on non-CYN-producing C. raciborskii appear similar to the unfed control. However, some individuals fed on non-CYN-producing C. raciborskii showed similarities with the fed control. In contrast, the midgut and digestive diverticula of D. magna fed on CYN-producing C. raciborskii showed a widespread dissociation of epithelial cells, associated with severe intracellular disorganization, but cell lysis was less evident than in controls. These alterations cannot be attributed to CYN, because those effects were not induced by CYN-producing A. ovalisporum. Therefore, data suggest the production of another unidentified active metabolite by CYN-producing C. raciborskii, responsible for the disruption of cell adhesion in the epithelium of D. magna digestive tract. Data also show that the tested cyanobacteria are inadequate as food to D. magna, due to low nutritional

Negative effects of UVB-irradiated phytoplankton on life history traits and fitness of Daphnia magna

NARCIS (Netherlands)

Lange, de H.J.; Reeuwijk, van P.L.

2003-01-01

1. We tested the effect of ultraviolet-B (UVB)-irradiated phytoplankton on life history characteristics of Daphnia magna . Two phytoplankton species were used, Chlamydomonas reinhardtii and Cryptomonas pyrenoidifera . The phytoplankton species were cultured under photosynthetically active radiation

Successfully resisting a pathogen is rarely costly in Daphnia magna

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Vale Pedro F

2010-11-01

Full Text Available Abstract Background A central hypothesis in the evolutionary ecology of parasitism is that trade-offs exist between resistance to parasites and other fitness components such as fecundity, growth, survival, and predator avoidance, or resistance to other parasites. These trade-offs are called costs of resistance. These costs fall into two broad categories: constitutive costs of resistance, which arise from a negative genetic covariance between immunity and other fitness-related traits, and inducible costs of resistance, which are the physiological costs incurred by hosts when mounting an immune response. We sought to study inducible costs in depth using the crustacean Daphnia magna and its bacterial parasite Pasteuria ramosa. Results We designed specific experiments to study the costs induced by exposure to this parasite, and we re-analysed previously published data in an effort to determine the generality of such costs. However, despite the variety of genetic backgrounds of both hosts and parasites, and the different exposure protocols and environmental conditions used in these experiment, this work showed that costs of exposure can only rarely be detected in the D. magna-P. ramosa system. Conclusions We discuss possible reasons for this lack of detectable costs, including scenarios where costs of resistance to parasites might not play a major role in the co-evolution of hosts and parasites.

Combining physico-chemical analysis with a Daphnia magna bioassay to evaluate a recycling technology for drinking water treatment plant waste residuals.

Science.gov (United States)

Chen, Ting; Xu, Yongpeng; Zhu, Shijun; Cui, Fuyi

2015-12-01

Recycling water treatment plant (WTP) waste residuals is considered to be a feasible method to enhance the efficiency of pollutant removal. This study also evaluated the safety and water quality of a pilot-DWTP waste residuals recycling technology by combining physical-chemistry analysis with a Daphnia magna assay. The water samples taken from each treatment step were extracted and concentrated by XAD-2 resin and were then analyzed for immobilization and enzyme activity with D. magna. The measured parameters, such as the dissolve organic carbon (DOC), UV254 and THM formation potential (THMFPs) of the recycling process, did not obviously increase over 15 days of continuous operation and were even lower than typical values from a conventional process. The extract concentration ranged from 0 to 2 Leq/ml as measured on the 7th and 15th days and the immobilization of D. magna exposed to water treated by the recycling process was nearly equivalent to that of the conventional process. Both the superoxide dismutase (SOD) and the catalase (CAT) activity assay indicated that a lower dose of water extract (0.5, 1, 1.5 Leq/ml) could stimulate the enzyme activity of D. magna, whereas a higher dose (2 Leq/ml at the sampling point C3, R3, R4 ) inhibits the activity. Moreover, the SOD and CAT activity of D. magna with DOC and UV254 showed a strong concentration-effect relationship, where the concentration range of DOC and UV254 were 4.1-16.2 mg/L and 0.071-4.382 cm(-1), respectively. The results showed that there was no statistically significant difference (p>0.05) between the conventional and recycling treatment processes and the toxicity of water samples in the recycling process did not increase during the 15-day continuous recycling trial. Copyright © 2015 Elsevier Inc. All rights reserved.

Variações fisiológicas da pressão do líquido cefalorraqueano na cisterna magna

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A. Spina-França

1963-03-01

Full Text Available É feito estudo de revisão das variações fisiológicas da pressão do LCR ao nível da cisterna magna (punção suboccipital. Em relação à série de 1.500 pacientes com afecções do sistema nervoso e sem sintomatologia de hipotensão ou de hipertensão intracraniana, a pressão média normal do LCR ao nível da cisterna magna foi de 11,9 cm de água (paciente calmo, decúbito lateral horizontal. As variações fisiológicas de pressão, segundo os achados, têm como limites os valôres de 4,1 e 19,7 cm de água. Êsses valôres permitem caracterizar, para a cisterna magna, a existência de hipotensão do LCR quando a pressão fôr menor ou igual a 4 cm de água; a hipertensão é caracterizada por valores iguais ou maiores do que 20 cm de água. A pressão do LCR ao nível da cisterna magna é menor do que no fundo de saco lombar. Para série de 276 pacientes o valor médio achado para êste último nível foi de 16,7 cm de água (decúbito lateral horizontal. A diferença entre as médias foi altamente significativa. Não foram verificadas modificações da pressão do LCR ao nível da cisterna magna que pudessem ser relacionadas ao sexo. Sem que representassem dados de interêsse para a prática, foram verificadas variações ligadas à côr e à idade dos pacientes. Em média a pressão do LCR se mostrou menor entre pacientes prêtos e amarelos que entre os brancos e os mulatos. Um declínio do valor médio da pressão foi verificado à medida em que aumentava a idade dos pacientes. Êste declínio mostrou-se maior para o grupo de pacientes com idade acima de 60 anos.

Natural Translating Locomotion Modulates Cortical Activity at Action Observation

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Thierry Pozzo

2017-11-01

Full Text Available The present study verified if the translational component of locomotion modulated cortical activity recorded at action observation. Previous studies focusing on visual processing of biological motion mainly presented point light walker that were fixed on a spot, thus removing the net translation toward a goal that yet remains a critical feature of locomotor behavior. We hypothesized that if biological motion recognition relies on the transformation of seeing in doing and its expected sensory consequences, a significant effect of translation compared to centered displays on sensorimotor cortical activity is expected. To this aim, we explored whether EEG activity in the theta (4–8 Hz, alpha (8–12 Hz, beta 1 (14–20 Hz and beta 2 (20–32 Hz frequency bands exhibited selectivity as participants viewed four types of stimuli: a centered walker, a centered scrambled, a translating walker and a translating scrambled. We found higher theta synchronizations for observed stimulus with familiar shape. Higher power decreases in the beta 1 and beta 2 bands, indicating a stronger motor resonance was elicited by translating compared to centered stimuli. Finally, beta bands modulation in Superior Parietal areas showed that the translational component of locomotion induced greater motor resonance than human shape. Using a Multinomial Logistic Regression classifier we found that Dorsal-Parietal and Inferior-Frontal regions of interest (ROIs, constituting the core of action-observation system, were the only areas capable to discriminate all the four conditions, as reflected by beta activities. Our findings suggest that the embodiment elicited by an observed scenario is strongly mediated by horizontal body displacement.

Action Potential Modulation of Neural Spin Networks Suggests Possible Role of Spin

CERN Document Server

Hu, H P

2004-01-01

In this paper we show that nuclear spin networks in neural membranes are modulated by action potentials through J-coupling, dipolar coupling and chemical shielding tensors and perturbed by microscopically strong and fluctuating internal magnetic fields produced largely by paramagnetic oxygen. We suggest that these spin networks could be involved in brain functions since said modulation inputs information carried by the neural spike trains into them, said perturbation activates various dynamics within them and the combination of the two likely produce stochastic resonance thus synchronizing said dynamics to the neural firings. Although quantum coherence is desirable and may indeed exist, it is not required for these spin networks to serve as the subatomic components for the conventional neural networks.

Is The Principle Of Magna Carta Regarding Religious Liberties Applied In Macedonia?

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Nuhija Bekim

2015-12-01

Full Text Available Human rights were analyzed and described in many writings from older times. If we consider their fame and historical value, most important ones are: Great Charter of Freedoms (Magna Carta Libertatum of 1215, the Law on Rights (Bill of Rights of 1689, the Declaration of Independence of the United States of America (1776 and the Declaration of the Rights of Man and Citizen (1789.

EFFECTIVE CONCENTRATIONS OF 6 CONTAMINANTS TO LEMMA MINOR, PIMEPHALES PROMELA, DAPHNIA MAGNA, AND CERIODAPHNIA DUBIA

Science.gov (United States)

The research presented here resulted in EC50 and LOEC values for the contaminants copper, cadmium, diazinon, atrazine, and cyanide to the species Lemna Minor, Pimephales promelas, Daphnia magna, and Ceriodaphnia dubia. Observed values were used as benchmarks for assessing the se...

Response selection difficulty modulates the behavioral impact of rapidly learnt action effects.

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Uta eWolfensteller

2014-12-01

Full Text Available It is well established that we can pick up action effect associations when acting in a free-choice intentional mode. However, it is less clear whether and when action effect associations are learnt and actually affect behavior if we are acting in a forced-choice mode, applying a specific stimulus-response (S-R rule. In the present study, we investigated whether response selection difficulty imposed by S-R rules influences the initial rapid learning and the behavioral expression of previously learnt but weakly practiced action effect associations when those are re-activated by effect exposure. Experiment 1 showed that the rapid acquisition of action effect associations is not directly influenced by response selection difficulty. By contrast, the behavioral expression of re-activated action effect associations is prevented when actions are directly activated by highly over-learnt response cues and thus response selection difficulty is low. However, all three experiments showed that if response selection difficulty is sufficiently high during re-activation, the same action effect associations do influence behavior. Experiment 2 and 3 revealed that the effect of response selection difficulty cannot be fully reduced to giving action effects more time to prime an action, but seems to reflect competition during response selection. Finally, the present data suggest that when multiple novel rules are rapidly learnt in succession, which requires a lot of flexibility, action effect associations continue to influence behavior only if response selection difficulty is sufficiently high. Thus, response selection difficulty might modulate the impact of experiencing multiple learning episodes on action effect expression and learning, possibly via inducing different strategies.

Automated Extraction of Genomic DNA from Medically Important Yeast Species and Filamentous Fungi by Using the MagNA Pure LC System

OpenAIRE

Loeffler, Juergen; Schmidt, Kathrin; Hebart, Holger; Schumacher, Ulrike; Einsele, Hermann

2002-01-01

A fully automated assay was established for the extraction of DNA from clinically important fungi by using the MagNA Pure LC instrument. The test was evaluated by DNA isolation from 23 species of yeast and filamentous fungi and by extractions (n = 28) of serially diluted Aspergillus fumigatus conidia (105 to 0 CFU/ml). Additionally, DNA from 67 clinical specimens was extracted and compared to the manual protocol. The detection limit of the MagNA Pure LC assay of 10 CFU corresponded to the sen...

Draft Genome Sequence of Serratia sp. Strain DD3, Isolated from the Guts of Daphnia magna

OpenAIRE

Poehlein, Anja; Freese, Heike M.; Daniel, Rolf; Simeonova, Diliana D.

2014-01-01

We report the draft genome sequence of Serratia sp. strain DD3, a gammaproteobacterium from the family Enterobacteriaceae. It was isolated from homogenized guts of Daphnia magna. The genome size is 5,274 Mb. peerReviewed

Growth and Survival Rate of Tilapia (Oreochromis niloticus Larvae Fed by Daphnia magna Cultured With Organic Fertilizer Resulted From Probiotic Bacteria Fermentation

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Vivi Endar Herawati

2015-10-01

Full Text Available Daphnia magna is a potential feed for fish. The aim of this research was to find the best treatment and effect of D. magna culture addition from fermented organic fertilizer, to growth and survival rate of Oreochromis niloticus larvae. There were five treatments, each with three repetitions used in the study. All treatments used chicken dung, and different combinations of rice bran, coconut oilcake waste and tilapia larvae. Feeding on tilapia was given by ad libitum method for five times a day until 14 days. Water quality during the research was maintained at temperature 28–29°C, DO 0.3 ppm and pH 8.1–8.2. Observed variables include relative growth rate, survival rate, food consumption rate and water quality. Our results showed that D. magna cultured by fermented organic fertilizer for tilapia larvae (O. niloticus had high significant effect (p < 0.01 on the relative growth rate and survival rate. Treatment of D. magna cultured by 1.2 g/L chicken manure, 0.9 g/L rice bran and 0.3 g/L coconut oilcake showed the highest value on the relative growth rate (10.86%; survival rate (98.46% and food consumption at first week (106.43% and second week (152.76%.

The protective roles of TiO2 nanoparticles against UV-B toxicity in Daphnia magna.

Science.gov (United States)

Liu, Jie; Wang, Wen-Xiong

2017-09-01

Aquatic environments are increasingly under environmental stress due to ultraviolet (UV) radiation and potential inputs of nanoparticles with intense application of nanotechnology. In this study, we investigated the interaction between UV-B radiation and titanium nanoparticles (TiO 2 -NPs) in a model freshwater cladoceran Daphnia magna. UV-B toxicity to Daphnia magna was examined when the daphnids were exposed to a range of TiO 2 -NPs concentrations with an initial 5 or 10min of 200μW/cm 2 UV-B radiation. In addition, UV-B toxicity was also examined in the presence of TiO 2 -NPs in the body of daphnids. Our results demonstrated that the daphnid mortality under UV-B radiation decreased significantly in the presence of TiO 2 -NPs both in the water and in the body, indicating that TiO 2 -NPs had some protective effects on D. magna against UV-B. Such protective effect was mainly caused by the blockage of UV-B by TiO 2 -NPs adsorption. UV-B produced reactive oxygen species (ROS) in the water and in the daphnids, which was not sufficient to cause mortality of daphnids over short periods of radiation. Previous studies focused on the effects of TiO 2 -NPs on the toxicity of total UV radiation, and did not attempt to differentiate the potential diverse roles of UV-A and UV-B. Our study indicated that TiO 2 -NPs may conversely protect the UV-B toxicity to daphnids. Copyright © 2017 Elsevier B.V. All rights reserved.

Influence of environmental factors on the response of a natural population of Daphnia magna (Crustacea: Cladocera) to spinosad and Bacillus thuringiensis israelensis in Mediterranean coastal wetlands

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Duchet, C. [Entente Interdepartementale de Demoustication du Littoral Mediterraneen, 165 avenue Paul-Rimbaud, Montpellier F-34184 (France); INRA, UMR985 Ecologie et Sante des Ecosystemes, Equipe Ecotoxicologie et Qualite des Milieux Aquatiques, 65 rue de Saint Brieuc, Rennes F-35042 (France); Caquet, Th. [INRA, UMR985 Ecologie et Sante des Ecosystemes, Equipe Ecotoxicologie et Qualite des Milieux Aquatiques, 65 rue de Saint Brieuc, Rennes F-35042 (France); Franquet, E. [Universite Paul Cezanne, Institut Mediterraneen d' Ecologie et de Paleoecologie, Faculte des Sciences et Techniques Saint Jerome, C31, Marseille F-13397 (France); Lagneau, C. [Entente Interdepartementale de Demoustication du Littoral Mediterraneen, 165 avenue Paul-Rimbaud, Montpellier F-34184 (France); Lagadic, L., E-mail: Laurent.Lagadic@rennes.inra.f [INRA, UMR985 Ecologie et Sante des Ecosystemes, Equipe Ecotoxicologie et Qualite des Milieux Aquatiques, 65 rue de Saint Brieuc, Rennes F-35042 (France)

2010-05-15

The present study was undertaken to assess the impact of a candidate mosquito larvicide, spinosad (8, 17 and 33 mug L{sup -1}) on a field population of Daphnia magna under natural variations of water temperature and salinity, using Bti (0.16 and 0.50 muL L{sup -1}) as the reference larvicide. Microcosms (125 L) were placed in a shallow temporary marsh where D. magna was naturally present. The peak of salinity observed during the 21-day observation period may have been partly responsible for the decrease of daphnid population density in all the microcosms. It is also probably responsible for the absence of recovery in the microcosms treated with spinosad which caused a sharp decrease of D. magna abundance within the first two days following treatment whereas Bti had no effect. These results suggest that it may be difficult for a field population of daphnids to cope simultaneously with natural (water salinity and temperature) and anthropogenic (larvicides) stressors. - Significant interaction between salinity and spinosad exposure impairs the recovery of a natural population of Daphnia magna.

Relationship between trans-generational effects of tetracycline on Daphnia magna at the physiological and whole organism level

International Nuclear Information System (INIS)

Kim, Hyun Young; Yu, Seungho; Jeong, Tae-yong; Kim, Sang Don

2014-01-01

The effects of pharmaceuticals have been underestimated during single generation exposure. Therefore, in this study, we investigated toxic responses at the physiological and whole organism level in tetracycline-exposed Daphnia magna over four consecutive generational lifecycles. The results showed that tetracycline affected energy-related physiological functions in concentration- and generation-dependent manners, and especially maintenance costs increased. Consequently, multigenerational exposure to tetracycline induced changes in energy balance, resulting in the change of higher levels of biological responses. In contrast, D. magna acclimated to tetracycline exposure over multiple generations, as evidenced by the increased LC 50 values. Transgenerational adaptation was related to the neonatal sensitivity and energy reserves of the organism. The results also emphasized the idea that the number of generation is an important factor for toxicity. The present study confirmed that toxic stress induces metabolic changes in an organism, thereby leading to increased energy consumption that results in adverse effects on reproduction. - Highlights: • Transgenerational adaptation of D. magna to tetracycline was observed. • TCN affected energy-related physiological function and increased maintenance energy. • LC 50 value of TCN increased with increasing concentration and generation. • The number of exposure generation may be an important factor for toxicity. - The change in internal energy balance in daphnids during multigenerational exposure to tetracycline may explain whole organism responses

Pharmacological and morphological characteristics of the muscular system of the giant liver fluke (Fascioloides magna - Bassi 1875).

Science.gov (United States)

Trailović, Saša M; Marinković, Darko; Trailović, Jelena Nedeljković; Milovanović, Mirjana; Marjanović, Djordje S; Aničić, Milan R

2015-12-01

Motility is required for feeding, reproduction and maintenance of the fluke in the host's liver. According to that, the neuromuscular system can be an attractive drugable target for chemotherapy. Musculature of the Fascioloides magna is organized into three layers, an outer circular layer, beneath this layer the longitudinal layer, and third, the oblique, or diagonal layer underlies the longitudinal layer. In our study, the administration of atropine or caffeine did not cause classic muscle contractions of F. magna muscle strips. However, the Electrical Field Stimulation (EFS) induced stable and repeatable contractions, which enabled us to examine their sensitivity to the various substances. Acetylcholine (ACh) (300 μM and 1 mM), caused only a slight relaxation, without affecting the amplitude of spontaneous contractions or the amplitude of contractions induced by EFS. Contrary to that, atropine (100 μM) caused a significant increase in the basal tone and an increase of EFS-induced contractions. If acetylcholine is an inhibitory neurotransmitter in trematodes, the described effects of atropine are achieved by the blockade of inhibitory neurotransmission. On the other hand, with respect to the process of excitation-contraction coupling, the plant alkaloid ryanodine (30 μM) significantly reduced the basal tone, as well as EFS-induced contractions of F. magna muscle strips. Ryanodine inhibited the potentiating effect of atropine on the basal tone and contractions caused by EFS, which indicates that the contractile effect of atropine is dependent on Ca(++) release from intracellular stores. Caffeine (500 μM) caused relaxation of fluke muscle strips and at the same time significantly enhanced the EFS-induced contractions. Both effects of caffeine can be explained by entry of extracellular Ca(++) into muscle cells. The muscle contractility of F. magna depends both on the entry of extracellular calcium, and calcium release from intracellular stores, which are

Effects of various metals on survival, growth, reproduction, and metabolism of Daphnia magna

Energy Technology Data Exchange (ETDEWEB)

Biesinger, K E; Christensen, G M

1972-01-01

The toxicities of various metals to Daphnia magna were evaluated on the basis of a 48-hr 50% lethal concentration (lc50) 3-week 16% reproductive impairment concentrations (In micrograms per liter) for the metal ions tested were: Na(I), 680,000; Ca(II), 116,000; Mg(II), 82,000; K(I), 53,000; Sr(II), 42,000; Ba(II), 5,800; Fe(III), 4,380; Mn(II), 4,100; As(V), 520; Sn(II), 350; Cr(III), 330; Al(III), 320; Zn(II), 70; Au(III), 60; Ni(II), 30; Pb(II), 30; Cu(II), 22; Pt(IV), 14; Co(II), 10; Hg(II), 3.4; and Cd(II), 0.17. At mental concentrations permitting survival but impairing reproduction, daphnids weighed less than control animals. Amounts of total protein and glutamic oxalacetic transaminase activity varied with the different metals. The negative logarithm of the solubility product constant 8 pksp of the metal sulfides, electronegativity, and the logarithm of the equilibrium constant (log keg) of the metal-ATP complex were positively correlated with toxicity to D. magna. Other physicochemical properties were considered, but no additional correlations were found.

Study on the Effect of Heavy metals toxicity according to changing Hardness concentration using D.magna

Science.gov (United States)

Chun Sang, H.

2016-12-01

n order to determine and prevent the number of ecological effects of heavy metals in the materials, we have to accurately measure the heavy metals present in the water-based protection ecosystems and may determine the effects to humans. Heavy metals occurred in the industrial effluent which is a state in which the monitor, based on the emission standards are made by the Ministry of Environment and managed and waste water contained Copper, Zinc, lead, etc. These heavy metals are able to express the toxic effects only when present in the free-ions in the aqueous condition, which appears differently affected by the degree to hardness change in accordance with the season, precipitation. Generally changing hardness concentration can not precisely evaluate toxic effects of heavy metals in the water system. Anderson announced a study on bioassay for heavy metals from industrial waste water using Daphnia magna(Anderson, 1944, 1948). Breukelman published study the resitivity difference for the mercury Chloride(HgCl2). Braudouin(1974) compared the zooplankton(Daphnia sp.) acute toxicity of the different heavy metals and confirmed the sensitivity. Shcherban(1979) presented for toxicity evaluation results for the heavy metal of the Daphnia magna according to different temperature conditions. In the United States Environmental Protection Agency(EPA) established a standard test method for water fleas, managed and supervised water ecosystems, and announced the adoption of a bioassay standard method. This study was performed to evaluate acute inhibition using the Daphnia magna for the biological effect of heavy metal ions in water-based toxicity in the hardness change. Evaluation methods were conducted in EPA Water Quality process test criteria. TU(Toxic Unit), NOEC (No Observable Effect Concentration), LOEC (Lowest Observable Effect Concentration), EC50 (Median Effective Concentration) was calculated by Toxcalc 5.0 Program. Keywords : D. magna, Hardness, Toxic Unit, Heavy metal

Population structure and dispersal routes of an invasive parasite, Fascioloides magna, in North America and Europe

Czech Academy of Sciences Publication Activity Database

Juhasova, L.; Kraľová-Hromadová, I.; Bazsalovicsová, E.; Minárik, G.; Štefka, Jan; Mikulíček, P.; Pálková, L.; Pybus, M.

2016-01-01

Roč. 9, OCT 13 (2016), č. článku 547. ISSN 1756-3305 Institutional support: RVO:60077344 Keywords : microsatellites * parasite * giant liver fluke * Fascioloides magna * genetic interrelationships * migratory routes Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.080, year: 2016

Exposure of Daphnia magna to trichloroethylene (TCE) and vinyl chloride (VC): evaluation of gene transcription, cellular activity, and life-history parameters.

Science.gov (United States)

Houde, Magali; Douville, Mélanie; Gagnon, Pierre; Sproull, Jim; Cloutier, François

2015-06-01

Trichloroethylene (TCE) is a ubiquitous contaminant classified as a human carcinogen. Vinyl chloride (VC) is primarily used to manufacture polyvinyl chloride and can also be a degradation product of TCE. Very few data exist on the toxicity of TCE and VC in aquatic organisms particularly at environmentally relevant concentrations. The aim of this study was to evaluate the sub-lethal effects (10 day exposure; 0.1; 1; 10 µg/L) of TCE and VC in Daphnia magna at the gene, cellular, and life-history levels. Results indicated impacts of VC on the regulation of genes related to glutathione-S-transferase (GST), juvenile hormone esterase (JHE), and the vitelline outer layer membrane protein (VMO1). On the cellular level, exposure to 0.1, 1, and 10 µg/L of VC significantly increased the activity of JHE in D. magna and TCE increased the activity of chitinase (at 1 and 10 µg/L). Results for life-history parameters indicated a possible tendency of TCE to affect the number of molts at the individual level in D. magna (p=0.051). Measurement of VG-like proteins using the alkali-labile phosphates (ALP) assay did not show differences between TCE treated organisms and controls. However, semi-quantitative measurement using gradient gel electrophoresis (213-218 kDa) indicated significant decrease in VG-like protein levels following exposure to TCE at all three concentrations. Overall, results indicate effects of TCE and VC on genes and proteins related to metabolism, reproduction, and growth in D. magna. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

The effects of food availability on growth and reproduction of Daphnia magna exposed to silver nanoparticles

DEFF Research Database (Denmark)

Mackevica, Aiga; Skjolding, Lars Michael; Gergs, A.

) were performed using 30 nm citric acid stabilized AgNP. The aim of the study was, besides providing data for the chronic toxicity of AgNP, to study the influence of the food availability on the reproductive toxicity of AgNP in Daphnia magna. The exposure concentrations applied ranged from 2 to 50 μg...... to controls, whereas concentrations above 10 μgAg/L resulted in inhibition of growth and reproduction as well as an increased mortality. The addition of higher amounts of food showed a beneficial effect on animal survival, growth and reproduction. Similar as in normal food availability treatment, animals......The number of available studies on the acute effects of silver nanoparticles (AgNP) on aquatic organisms has increased dramatically in recent years, but there is still very limited information available on chronic effects. In this study, a series of Daphnia magna 21-days reproduction test (OECD 211...

Linking sub-individual and supra-individual effects in Daphnia magna exposed to sub-lethal concentration of chlorpyrifos.

Science.gov (United States)

Ferrario, Claudia; Parolini, Marco; De Felice, Beatrice; Villa, Sara; Finizio, Antonio

2018-04-01

The main objective of the present study was to investigate possible links between sub-individual and supra-individual levels (i.e. population level) biomarkers in D. magna exposed to sublethal concentrations of the insecticide chlorpyrifos (CPF). To achieve the aim, 8-day old individuals were exposed for 96 h to two environmentally relevant concentrations of CPF (50 and 250 ng/L). Sub-individual level effects were investigated by measuring the activity of antioxidant (SOD, CAT, and GPx) and detoxifying (GST) enzymes, as well as by measuring the acetylcholinesterase (AChE) inhibition. In addition, the effects at supra-individual level were assessed by using a video-tracking system and analyzing changes in swimming capabilities (i.e. percentage of activity time, distance moved, and velocity). Our data have shown that daphnids exposed to both CPF concentrations were in a condition of stress which was highlighted by changes in both sub- and supra-individual biomarkers. Moreover, our results highlighted that the lowest tested CPF concentration did not modulate the antioxidant and detoxifying enzymes, whereas, an inhibition of AChE and a decrease of some parameters related to swimming behaviour (distance moved and velocity) were noted. On the contrary, significant changes in all the sub-individual biomarkers were measured at the highest tested concentration. In addition, organisms recovered the movement capability (distance moved) and also activate a mechanism of avoidance (increased swimming velocity). On the other hand, a reduction in the percent of active time was measured and this was attributed to the energy spent by organisms to activate antioxidant and detoxifying enzymes and the mechanism of avoidance. Based on these results, our study suggests the existence of a link between sub- and supra-individual levels, as the activation or non-activation in the antioxidant and detoxifying enzymes activities can led to different modifications of the swimming behaviour

Multi-generation cadmium acclimation and tolerance in Daphnia magna Straus

International Nuclear Information System (INIS)

Muyssen, Brita T.A.; Janssen, Colin R.

2004-01-01

The cladoceran Daphnia magna was acclimated for seven generations to cadmium concentrations ranging from 0 (control) to 250 μg/l Cd (corresponding to a free ion activity of 4.60 nM Cd 2+ ). Acute and chronic cadmium tolerance as well as cadmium accumulation were monitored as a function of acclimation time. After two to three generations of acclimation to concentrations ranging from 0.23 to 1.11 nM Cd 2+ increases in acute tolerance were maximal (factor 7.2) and significant. Acclimation for seven generations to the same acclimation concentrations did result in an increased chronic cadmium tolerance (21 days EC 50 values increased). Organisms acclimated to 1.93 nM Cd 2+ were equally or more sensitive than non-acclimated daphnids in acute and chronic toxicity tests. Cadmium contents in D. magna increased significantly as a function of the acclimation concentration. Maximum body burdens of 236±30 μg Cd/g dry weight were measured in organisms exposed to 4.60 nM Cd 2+ , but detoxification mechanisms were only successful up to 82±20 μg Cd/g dry weight as this concentration did not cause major decreases in survival and reproduction in chronic toxicity tests. As the potential positive effect of acclimation on cadmium tolerance disappeared with successive acclimation generations and increasing acclimation concentrations, it is concluded that multi-generation acclimation studies are important for the evaluation of the long-term effects of environmental toxicants. - Multi-generation acclimation studies are important for evaluating long-term effects of aquatic pollutants

Modulation of ethanol-intake by morphine: Evidence for a central site of action

Energy Technology Data Exchange (ETDEWEB)

Wild, K.D.; Reid, L.D. (Rensselaer Polytechnic Institute, Troy, NY (USA))

1990-01-01

Previous studies have shown that subcutaneous administration of low doses of morphine increase, while subcutaneous naloxone decreases, ethanol-intake in rats. However, the site of action of morphine modulation of ethanol-intake remains unclear. In an attempt to elucidate this issue, seven graded doses of morphine were given intracerebroventricularly to rats 15 min prior to an opportunity to consume water and sweetened alcoholic beverage for 2 hr. Two lower doses of intracerebroventricular morphine reliably increased ethanol-intake, while higher doses decreased intake of water. Preference ratios were reliably increased by morphine doses of 1 {mu}g and higher. The present data provide support for a central site of morphine modulation of ethanol-intake.

The development of pathogen resistance in Daphnia magna: implications for disease spread in age-structured populations.

Science.gov (United States)

Garbutt, Jennie S; O'Donoghue, Anna J P; McTaggart, Seanna J; Wilson, Philip J; Little, Tom J

2014-11-01

Immunity in vertebrates is well established to develop with time, but the ontogeny of defence in invertebrates is markedly less studied. Yet, age-specific capacity for defence against pathogens, coupled with age structure in populations, has widespread implications for disease spread. Thus, we sought to determine the susceptibility of hosts of different ages in an experimental invertebrate host-pathogen system. In a series of experiments, we show that the ability of Daphnia magna to resist its natural bacterial pathogen Pasteuria ramosa changes with host age. Clonal differences make it difficult to draw general conclusions, but the majority of observations indicate that resistance increases early in the life of D. magna, consistent with the idea that the defence system develops with time. Immediately following this, at about the time when a daphnid would be most heavily investing in reproduction, resistance tends to decline. Because many ecological factors influence the age structure of Daphnia populations, our results highlight a broad mechanism by which ecological context can affect disease epidemiology. We also show that a previously observed protective effect of restricted maternal food persists throughout the entire juvenile period, and that the protective effect of prior treatment with a small dose of the pathogen ('priming') persists for 7 days, observations that reinforce the idea that immunity in D. magna can change over time. Together, our experiments lead us to conclude that invertebrate defence capabilities have an ontogeny that merits consideration with respect to both their immune systems and the epidemic spread of infection. © 2014. Published by The Company of Biologists Ltd.

Acute and chronic toxicity of four frequently used UV filter substances for Desmodesmus subspicatus and Daphnia magna.

Science.gov (United States)

Sieratowicz, Agnes; Kaiser, Dominic; Behr, Maximilian; Oetken, Matthias; Oehlmann, Jörg

2011-01-01

As a consequence of growing public concern about UV radiation effects on human health chemical and physical UV filters are increasingly used in personal care and other products. The release of these lipophilic and often persistent compounds into surface waters may pose a risk for aquatic organisms. The aim of the study was to determine effects of four frequently used UV filters on primary aquatic producers and consumers, the green alga Desmodesmus subspicatus and the crustacean Daphnia magna. Exposure to benzophenone 3 (BP3), ethylhexyl methoxycinnamate (EHMC), 3-benzylidene camphor (3-BC) and 3-(4'-methylbenzylidene)-camphor (4-MBC) resulted in growth inhibition of D. subspicatus with 72 h IC(10) values of 0.56 mg/L (BP 3), 0.24 mg/L (EHMC), 0.27 mg/L (3-BC) and 0.21 mg/L (4-MBC). EC(50) concentrations in the acute test with D. magna were 1.67, 0.57, 3.61 and 0.80 mg/L for BP3, EHMC, 3-BC and 4-MBC, respectively. Chronic exposure of D. magna resulted in NOECs of 0.04 mg/L (EHMC) and 0.1 mg/L (3-BC and 4-MBC). BP 3 showed no effects on neonate production or the length of adults. Rapid dissipation of these substances from the water phase was observed indicating the need for more frequent test medium renewal in chronic tests or the use of flow-through test systems.

Spectral SAR Ecotoxicology of Ionic Liquids: The Daphnia magna Case

International Nuclear Information System (INIS)

Putz, M.V.; Lacrama, A.M.; Ostafe, V.; Lacrama, A.M.

2007-01-01

Aiming to provide a unified theory of ionic liquids eco toxicity, the recent spectral structure activity relationship (S-SAR) algorithm is employed for testing the two additive models of anionic-cationic interaction containing ionic liquid activity: the causal and the endpoint, |0+> and |1+> models, respectively. As a working system, the Daphnia magna eco toxicity was characterized through the formulated and applied spectral chemical-eco biological interaction principles. Specific anionic-cationic-ionic-liquid rules of interaction along the developed mechanistic hypersurface map of the main eco toxicity paths together with the so-called resonance limitation of the standard statistical correlation analysis were revealed.

The positively phototactic reaction of daphnia magna straus: A contribution to the understanding of diurnal vertical migration

NARCIS (Netherlands)

Ringelberg, J.

1964-01-01

The present investigation was aimed at gaining more insight into the physiological mechanism underlying the diurnal vertical migration of planktonic animals. The experiments were carried out on Daphnia magna. Only reactions to decreases in light intensity were studied. Kinetical

Ecotoxicological assessment of Roundup-ready soybean agriculture investigated in a D. magna model

OpenAIRE

Cuhra, Marek

2015-01-01

Paper III of this thesis is not available i Munin: III: M. Cuhra, T. Traavik & T. Bøhn. 2014. 'Life cycle fitness differences in Daphnia magna fed Roundup-Ready soybean or conventional soybean or organic soybean', available in Aquaculture Nutrition Transgenic glyphosate tolerant soybeans are constituents of an industrial production system with specific agricultural practices and supplementary agrochemicals as interwoven additional elements. Thus the material produced should not be see...

Multigenerational effects evaluation of the flame retardant tris(2-butoxyethyl) phosphate (TBOEP) using Daphnia magna.

Science.gov (United States)

Giraudo, Maeva; Dubé, Maxime; Lépine, Mélanie; Gagnon, Pierre; Douville, Mélanie; Houde, Magali

2017-09-01

Tris(2-butoxyethyl) phosphate (TBOEP) is an organophosphate ester used as substitute following the phase-out of brominated flamed retardants. Because of its high production volume and its use in a broad range of applications, this chemical is now frequently detected in the environment and biota. However, limited information is available on the long-term effects of TBOEP in aquatic organisms. In this study, Daphnia magna were exposed over three 21d generations to an environmentally relevant concentration of TBOEP (10μg/L) and effects were evaluated at the gene transcription, protein, and life-history (i.e., survival, reproduction and growth) levels. Chronic exposure to TBEOP did not impact survival or reproduction of D. magna but affected the growth output. The mean number of molts was also found to be lower in daphnids exposed to the chemical compared to control for a given generation, however there were no significant differences over the three generations. Molecular responses indicated significant differences in the transcription of genes related to growth, molting, ecdysteroid and juvenile hormone signaling, proteolysis, oxidative stress, and oxygen transport within generations. Levels of mRNA were also found to be significantly different for genes known to be involved in endocrine-mediated mechanisms such as reproduction and growth between generations F0, F1, and F2, indicating effects of parental exposure on offspring. Transcription results were supported by protein analyses with the significant decreased in catalase (CAT) activity in F1 generation, following the decreased transcription of cat in the parental generation. Taken together, these multi-biological level results suggest long-term potential endocrine disruption effects of TBOEP in D. magna exposed to an environmentally relevant concentration. This study highlights the importance of using chronic and multigenerational biological evaluation to assess risks of emerging chemicals. Crown Copyright �

Ecotoxicological assessment of grey water treatment systems with Daphnia magna and Chironomus riparius.

Science.gov (United States)

Hernández Leal, L; Soeter, A M; Kools, S A E; Kraak, M H S; Parsons, J R; Temmink, H; Zeeman, G; Buisman, C J N

2012-03-15

In order to meet environmental quality criteria, grey water was treated in four different ways: 1) aerobic 2) anaerobic+aerobic 3) aerobic+activated carbon 4) aerobic+ozone. Since each treatment has its own specific advantages and disadvantages, the aim of this study was to compare the ecotoxicity of differently treated grey water using Chironomus riparius (96 h test) and Daphnia magna (48 h and 21d test) as test organisms. Grey water exhibited acute toxicity to both test organisms. The aerobic and combined anaerobic+aerobic treatment eliminated mortality in the acute tests, but growth of C. riparius was still affected by these two effluents. Post-treatment by ozone and activated carbon completely removed the acute toxicity from grey water. In the chronic toxicity test the combined anaerobic+aerobic treatment strongly affected D. magna population growth rate (47%), while the aerobic treatment had a small (9%) but significant effect. Hence, aerobic treatment is the best option for biological treatment of grey water, removing most of the toxic effects of grey water. If advanced treatment is required, the treatment with either ozone or GAC were shown to be very effective in complete removal of toxicity from grey water. Copyright © 2011 Elsevier Ltd. All rights reserved.

Parasitism drives host genome evolution: Insights from the Pasteuria ramosa-Daphnia magna system.

Science.gov (United States)

Bourgeois, Yann; Roulin, Anne C; Müller, Kristina; Ebert, Dieter

2017-04-01

Because parasitism is thought to play a major role in shaping host genomes, it has been predicted that genomic regions associated with resistance to parasites should stand out in genome scans, revealing signals of selection above the genomic background. To test whether parasitism is indeed such a major factor in host evolution and to better understand host-parasite interaction at the molecular level, we studied genome-wide polymorphisms in 97 genotypes of the planktonic crustacean Daphnia magna originating from three localities across Europe. Daphnia magna is known to coevolve with the bacterial pathogen Pasteuria ramosa for which host genotypes (clonal lines) are either resistant or susceptible. Using association mapping, we identified two genomic regions involved in resistance to P. ramosa, one of which was already known from a previous QTL analysis. We then performed a naïve genome scan to test for signatures of positive selection and found that the two regions identified with the association mapping further stood out as outliers. Several other regions with evidence for selection were also found, but no link between these regions and phenotypic variation could be established. Our results are consistent with the hypothesis that parasitism is driving host genome evolution. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

DEGRADATION AND CONSERVATION OF MARBLE IN THE GREEK ROMAN HADRIANIC BATHS IN LEPTIS MAGNA, LIBYA

Directory of Open Access Journals (Sweden)

Nabil.A. ABD EL-TAWAB

2012-09-01

Full Text Available The Hadrianic Baths is one of the most important archaeological sites in Leptis Magna- Libya. It was built at the command of Emperor Hadrian in the early 2nd century CE; they represent some of the most lavish structures of Leptis Magna. It is unique in design and building technique. It was built of limestone, marble and brick. This paper mainly describes the deterioration of marble. The marble in the monuments can be classified into several types, based on its color, texture, chemical composition and the constituent mineral. The Hadrianic Baths is subjected to severe degradation, due to the climate, which is typically marine. This site suffered from different weathering forms, for example, disintegration of grains, pitting, chipping, frequent flaking, multiple-flaking, fissures and biodeterioration. These weathering forms were produced by many deterioration factors, such as moisture, salt weathering, biological and micro-biological factors, changes in temperature and wind erosion. The aim of this study is to characterize the building materials at the Hadrianic Baths, especially marble, and to evaluate the role of groundwater and sea weathering on the strength of the marble exposed to the coastline of the Mediterranean. Many samples were collected from limestone, marble, mortar, plaster and salts, for analysis and investigation. Several scientific techniques were used in the study of the morphology and texture. Those methods include microscopy, such as scanning electron microscopy (SEM, polarized light microscopy (PLM and stereo microscopy. A qualitative identification of organic and inorganic chemical species was performed by using techniques such as energy-dispersive spectroscopy (EDS, X-ray diffraction (XRD and microbial investigation were also done. Our results indicated that the deterioration of marble was caused by the aggressive action of environmental agents. SEM observations indicated the occurrence of microcracks and particle aggregates

Is acetylcholinesterase a biomarker of susceptibility in Daphnia magna (Crustacea, Cladocera) after deltamethrin exposure?

Science.gov (United States)

Toumi, Héla; Boumaiza, Moncef; Millet, Maurice; Radetski, Claudemir Marcos; Felten, Vincent; Férard, Jean François

2015-02-01

In the present study, we explored the possibility of using the acetylcholinesterase (AChE) as a biomarker after deltamethrin (pyrethroid insecticide) exposure with three strains of the cladoceran Daphnia magna. Four calculated time-weighted deltamethrin concentrations (20.1, 40.3, 80.6 and 161.3 ng L(-1)) were compared against control acetylcholinesterase activity. Our results showed that after 48 h of deltamethrin exposure, all treatments induced a significant decrease of AChE activities whatever the three considered strains. However, diverse responses were registered in terms of lowest observed effect concentrations (LOEC: 80.6 ng L(-1) for strain 1 and 20.1 ng L(-1) for strains 2 and 3) revealing differences in sensitivity among the three tested strains of D. magna. Our results suggest that after deltamethrin exposure, the AChE activity responses can be also used as a biomarker of susceptibility (i.e., variation of strain specific response). Moreover, our results show that strain 1 is the less sensitive in terms of IC50-48 h of AChE, whereas it became the most sensitive when considering the EC50-48 h estimated in the standard ecotoxicity test. Copyright © 2014 Elsevier Ltd. All rights reserved.

Calcium pathways such as cAMP modulate clothianidin action through activation of α-bungarotoxin-sensitive and -insensitive nicotinic acetylcholine receptors.

Science.gov (United States)

Calas-List, Delphine; List, Olivier; Quinchard, Sophie; Thany, Steeve H

2013-07-01

Clothianidin is a neonicotinoid insecticide developed in the early 2000s. We have recently demonstrated that it was a full agonist of α-bungarotoxin-sensitive and -insensitive nicotinic acetylcholine receptors expressed in the cockroach dorsal unpaired median neurons. Clothianidin was able to act as an agonist of imidacloprid-insensitive nAChR2 receptor and internal regulation of cAMP concentration modulated nAChR2 sensitivity to clothianidin. In the present study, we demonstrated that cAMP modulated the agonist action of clothianidin via α-bungarotoxin-sensitive and insensitive receptors. Clothianidin-induced current-voltage curves were dependent to clothianidin concentrations. At 10 μM clothianidin, increasing cAMP concentration induced a linear current-voltage curve. Clothianidin effects were blocked by 0.5 μM α-bungarotoxin suggesting that cAMP modulation occurred through α-bungarotoxin-sensitive receptors. At 1 mM clothianidin, cAMP effects were associated to α-bungarotoxin-insensitive receptors because clothianidin-induced currents were blocked by 5 μM mecamylamine and 20 μM d-tubocurarine. In addition, we found that application of 1mM clothianidin induced a strong increase of intracellular calcium concentration. These data reinforced the finding that calcium pathways including cAMP modulated clothianidin action on insect nicotinic acetylcholine receptors. We proposed that intracellular calcium pathways such as cAMP could be a target to modulate the mode of action of neonicotinoid insecticides. Copyright © 2013 Elsevier Inc. All rights reserved.

Sucralose induces biochemical responses in Daphnia magna.

Directory of Open Access Journals (Sweden)

Ann-Kristin Eriksson Wiklund

Full Text Available The intense artificial sweetener sucralose has no bioconcentration properties, and no adverse acute toxic effects have been observed in standard ecotoxicity tests, suggesting negligible environmental risk. However, significant feeding and behavioural alterations have been reported in non-standard tests using aquatic crustaceans, indicating possible sublethal effects. We hypothesized that these effects are related to alterations in acetylcholinesterase (AChE and oxidative status in the exposed animals and investigated changes in AChE and oxidative biomarkers (oxygen radical absorbing capacity, ORAC, and lipid peroxidation, TBARS in the crustacean Daphnia magna exposed to sucralose (0.0001-5 mg L(-1. The sucralose concentration was a significant positive predictor for ORAC, TBARS and AChE in the daphnids. Moreover, the AChE response was linked to both oxidative biomarkers, with positive and negative relationships for TBARS and ORAC, respectively. These joint responses support our hypothesis and suggest that exposure to sucralose may induce neurological and oxidative mechanisms with potentially important consequences for animal behaviour and physiology.

Modulation of KCNQ1 alternative splicing regulates cardiac IKs and action potential repolarization.

Science.gov (United States)

Lee, Hsiang-Chun; Rudy, Yoram; Po-Yuan, Phd; Sheu, Sheng-Hsiung; Chang, Jan-Gowth; Cui, Jianmin

2013-08-01

Slow delayed-rectifier potassium current (IKs) channels, made of the pore-forming KCNQ1 and auxiliary KCNE1 subunits, play a key role in determining action potential duration (APD) in cardiac myocytes. The consequences of drug-induced KCNQ1 splice alteration remain unknown. To study the modulation of KCNQ1 alternative splicing by amiloride and the consequent changes in IKs and action potentials (APs) in ventricular myocytes. Canine endocardial, midmyocardial, and epicardial ventricular myocytes were isolated. Levels of KCNQ1a and KCNQ1b as well as a series of splicing factors were quantified by using the reverse transcriptase-polymerase chain reaction and Western blot. The effect of amiloride-induced changes in the KCNQ1b/total KCNQ1 ratio on AP was measured by using whole-cell patch clamp with and without isoproterenol. With 50 μmol/L of amiloride for 6 hours, KCNQ1a at transcriptional and translational levels increased in midmyocardial myocytes but decreased in endo- and epicardial myocytes. Likewise, changes in splicing factors in midmyocardial were opposite to that in endo- and epicardial myocytes. In midmyocardial myocytes amiloride shortened APD and decreased isoproterenol-induced early afterdepolarizations significantly. The same amiloride-induced effects were demonstrated by using human ventricular myocyte model for AP simulations under beta-adrenergic stimulation. Moreover, amiloride reduced the transmural dispersion of repolarization in pseudo-electrocardiogram. Amiloride regulates IKs and APs with transmural differences and reduces arrhythmogenicity through the modulation of KCNQ1 splicing. We suggested that the modulation of KCNQ1 splicing may help prevent arrhythmia. Copyright © 2013 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Dopaminergic modulation of positive expectations for goal-directed action: evidence from Parkinson’s disease

Directory of Open Access Journals (Sweden)

Noham eWolpe

2015-10-01

Full Text Available Parkinson’s disease (PD impairs the control of movement and cognition, including the planning of action and its consequences. This provides the opportunity to study the dopaminergic influences on the perception and awareness of action. Here we examined the perception of the outcome of a goal-directed action made by medicated patients with PD. A visuomotor task probed the integration of sensorimotor signals with the positive expectations of outcomes (Self priors, which in healthy adults bias perception towards success in proportion to trait optimism. We tested the hypotheses that (i the priors on the perception of the consequences of one’s own actions differ between patients and age- and sex-matched controls, and (ii that these priors are modulated by the levodopa dose equivalent in patients. There was no overall difference between patients and controls in the perceptual priors used. However, the precision of patient priors was inversely related to their levodopa dose equivalent. Patients with high levodopa dose equivalent showed more accurate priors, representing predictions that were closer to the true distribution of performance. Such accuracy has previously been demonstrated when observing the actions of others, suggesting abnormal awareness of action in these patients. These results confirm a link between dopamine and the positive expectation of the outcome of one’s own actions, and may have implications for the management of PD.

Evaluation of Baffle Fixes Film up Flow Sludge Blanket Filtration (BFUSBF) System in Treatment of Wastewaters from Phenol and 2,4-Dinitrophenol Using Daphnia Magna Bioassay

OpenAIRE

Mohammad Javad Ghannadzadeh; Ahmad Jonidi Jafari; Abbas Rezaee; Fatemeh Eftekharian; Ali Koolivand

2016-01-01

Background: Phenol and nitrophenol are common compounds found in different types of industrial wastewater known as serious threats to human health and natural environment. In this study, Daphnia magna was used to evaluate the effectiveness of "baffle fixes film up flow sludge blanket filtration" (BFUSBF) system in elimination of phenolic compounds from water. Methods: D. magna cultures were used as toxicity index of phenol and 2,4-DNP mixtures after treatment by a pilot BFUSBF system which...

Long-term evaluation of lethal and sublethal toxicity of industrial effluents using Daphnia magna and Moina macrocopa.

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Yi, Xianliang; Kang, Sung-Wook; Jung, Jinho

2010-06-15

Acute toxicity and feeding rate inhibition of effluent from a wastewater treatment plant and its adjacent stream water on Daphnia magna and Moina macrocopa were comparatively studied. The acute toxicity of the final effluent (FE) fluctuated greatly over the sampling period from January to August 2009. Toxicity identification results of the FE in July 2009 showed that Cu originating from the Fenton's reagent was likely a key toxicant. In addition, the feeding rate of both species was still inhibited by the FEs in which acute toxicity was not observed. These findings indicate that the feeding response would be a useful tool for monitoring sublethal effects of industrial effluents. For the acute toxicity test, M. macrocopa was more sensitive than D. magna, but the opposite result was true in the case of the feeding rate inhibition. These suggest that different species have different sensitivities to toxic chemicals and to the test methods. Copyright 2010 Elsevier B.V. All rights reserved.

Comparative ecotoxicity of potential biofuels to water flea (Daphnia magna), zebrafish (Danio rerio) and Chinese hamster (Cricetulus griseus) V79 cells.

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Heger, Sebastian; Du, Miaomiao; Bauer, Kevin; Schäffer, Andreas; Hollert, Henner

2018-08-01

The ecotoxicity of two biofuel candidates (1‑octanol and 2‑butanone) was investigated by an integrative test strategy using three bioassays: the acute immobilisation test with water flea (D. magna), the fish embryo acute toxicity test with zebrafish (Danio rerio) and the in vitro micronucleus assay with Chinese hamster (Cricetulus griseus) V79 cells. The median effective concentration (EC 50 ) values were 14.9±0.66mgL -1 for 1‑octanol, and 2152.1±44.6mgL -1 for 2‑butanone in the D. magna test. Both 1‑octanol and 2‑butanone caused teratogenic and lethal effects on zebrafish embryos, while exposure to 1‑octanol significantly induced these effects at concentrations ≥2.0mgL -1 . These results indicate that 1‑octanol exert much higher ecotoxicity than 2‑butanone to D. magna and zebrafish embryos. Moreover, both 1‑octanol and 2‑butanone did not cause significant genotoxic effects, while their metabolites significantly induced micronuclei in V79 cells. The present study proposed an integrative test approach to evaluate the potential ecotoxicity of biofuels using simple, quick and inexpensive bioassays. Copyright © 2018 Elsevier B.V. All rights reserved.

Silver nanoparticles and silver nitrate induce high toxicity to Pseudokirchneriella subcapitata, Daphnia magna and Danio rerio

International Nuclear Information System (INIS)

Ribeiro, Fabianne; Gallego-Urrea, Julián Alberto; Jurkschat, Kerstin; Crossley, Alison; Hassellöv, Martin; Taylor, Cameron; Soares, Amadeu M.V.M.; Loureiro, Susana

2014-01-01

Silver nanoparticles (AgNP) have gained attention over the years due to the antimicrobial function of silver, which has been exploited industrially to produce consumer goods that vary in type and application. Undoubtedly the increase of production and consumption of these silver-containing products will lead to the entry of silver compounds into the environment. In this study we have used Pseudokirchneriella subcapitata, Daphnia magna and Danio rerio as model organisms to investigate the toxicity of AgNP and AgNO 3 by assessing different biological endpoints and exposure periods. Organisms were exposed following specific and standardized protocols for each species/endpoints, with modifications when necessary. AgNP were characterized in each test-media by Transmission Electron Microscopy (TEM) and experiments were performed by Dynamic Light Scattering (DLS) to investigate the aggregation and agglomeration behavior of AgNP under different media chemical composition and test-period. TEM images of AgNP in the different test-media showed dissimilar patterns of agglomeration, with some agglomerates inside an organic layer, some loosely associated particles and also the presence of some individual particles. The toxicity of both AgNO 3 and AgNP differ significantly based on the test species: we found no differences in toxicity for algae, a small difference for zebrafish and a major difference in toxicity for Daphnia magna. - Highlights: •Effects of silver nanoparticles and nitrate were compared in three aquatic species. •The presence of food on the immobilization assay for Daphnia magna significantly decreased AgNP toxicity. •AgNP and AgNO 3 differ in toxicity according to the test species and endpoint. •AgNP and AgNO 3 induced dissimilar abnormalities on zebrafish embryos' development. •AgNP behavior in the test media will rule its bioavailability and uptake and therefore toxicity

Silver nanoparticles and silver nitrate induce high toxicity to Pseudokirchneriella subcapitata, Daphnia magna and Danio rerio

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, Fabianne, E-mail: ribeiro.f@ua.pt [Department of Biology and CESAM, University of Aveiro. Campus Universitario de Santiago, 3810-193. Aveiro (Portugal); Gallego-Urrea, Julián Alberto [Department of Chemistry and Molecular Biologyx, University of Gothenburg, Kemivägen 4, 41296 Gothenburg (Sweden); Jurkschat, Kerstin; Crossley, Alison [Department of Materials, Oxford University Begbroke Science Park OX5 1PF (United Kingdom); Hassellöv, Martin [Department of Chemistry and Molecular Biologyx, University of Gothenburg, Kemivägen 4, 41296 Gothenburg (Sweden); Taylor, Cameron [Department of Materials, Oxford University Begbroke Science Park OX5 1PF (United Kingdom); Soares, Amadeu M.V.M.; Loureiro, Susana [Department of Biology and CESAM, University of Aveiro. Campus Universitario de Santiago, 3810-193. Aveiro (Portugal)

2014-01-01

Silver nanoparticles (AgNP) have gained attention over the years due to the antimicrobial function of silver, which has been exploited industrially to produce consumer goods that vary in type and application. Undoubtedly the increase of production and consumption of these silver-containing products will lead to the entry of silver compounds into the environment. In this study we have used Pseudokirchneriella subcapitata, Daphnia magna and Danio rerio as model organisms to investigate the toxicity of AgNP and AgNO{sub 3} by assessing different biological endpoints and exposure periods. Organisms were exposed following specific and standardized protocols for each species/endpoints, with modifications when necessary. AgNP were characterized in each test-media by Transmission Electron Microscopy (TEM) and experiments were performed by Dynamic Light Scattering (DLS) to investigate the aggregation and agglomeration behavior of AgNP under different media chemical composition and test-period. TEM images of AgNP in the different test-media showed dissimilar patterns of agglomeration, with some agglomerates inside an organic layer, some loosely associated particles and also the presence of some individual particles. The toxicity of both AgNO{sub 3} and AgNP differ significantly based on the test species: we found no differences in toxicity for algae, a small difference for zebrafish and a major difference in toxicity for Daphnia magna. - Highlights: •Effects of silver nanoparticles and nitrate were compared in three aquatic species. •The presence of food on the immobilization assay for Daphnia magna significantly decreased AgNP toxicity. •AgNP and AgNO{sub 3} differ in toxicity according to the test species and endpoint. •AgNP and AgNO{sub 3} induced dissimilar abnormalities on zebrafish embryos' development. •AgNP behavior in the test media will rule its bioavailability and uptake and therefore toxicity.

Research of acute influence of new fertlizer «Rost-concentrate» on the hydrobionts Сyprinus carpio L. and Daphnia magna Straus

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N. Tson

2016-12-01

Full Text Available Purpose. To establish and assess acute toxicity parameters of "ROST-concentrate (10+7+7" acute toxicity for planktonic crustacean Daphnia magna Straus and carp fingerlings Cyprinus carpio L. Methodology."ROST-concentrate (10+7+7" contains macronutrients (nitrogen, phosphorus, potassium, which are valuable for the pond ecosystem, and trace elements in environmentally safe chelate form. We determined the vital (LC0, absolutely lethal (LC100 and median (LC50 drug concentrations on the test organisms such as crustacean D. magna (Cladocera and carp fingerlings C. carpio. The determination of acute lethal toxicity on D. magna was conducted according to DSTU 4173: 2003 that corresponded to the international standard ISO 6341: 2012, MOD [7]. The temperature of the experiment was 20±0.5 oC. The exposure time - 96 hours. Daphnia were not fed. Following "ROST-concentrate (10+7+7" concentrations were tested: 100; 75; 50; 25; 10; 1; 0.5; 0.1; 0.05; 0.01; 0,005; 0,001 ml/dm3. We also determined the acute lethal toxicity on carp fingerings with an average weight of 6.78±0.63 grams following the standardized procedure [8]. Pond water was used in the experiment. Ten fish were placed into a 40 L aquarium. Following concentrations of "ROST-concentrate (10+7+7" were investigated: 0,5; 1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 15; 20; 30; 40 mg/L. The exposure time was 24 hours. Water temperature was 19±1oC. LC50 drug median concentration was calculated according to G. Kerber method. Findings. The parameters of integral acute toxicity of "ROST-concentrate (10+7+7" on typical organisms of fish pond ecosystems.With 96 h exposure on juvenile cladoceran D. magna, lethal concentration was LC100 = 5,00 ml/dm3, median concentration was LC50 = 0,15 ml/dm3, vital concentration was LC0 = 0,01 ml/dm3. According to the classification of toxic substances, the "ROST-concentrate (10+7+7" is characterized by low toxicity on juvenile cladoceran D. magna. With 24 h exposure on carp

The Effect of Fermentation Time with Probiotic Bacteria on Organic Fertilizer as Daphnia magna Cultured Medium towards Nutrient Quality, Biomass Production and Growth Performance Enhancement

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Endar Herawati, Vivi; Agung Nugroho, Ristiawan; Pinandoyo; Darmanto, YS; Hutabarat, Johannes

2018-02-01

The nutrient quality and growth performance of D. magna are highly depend on the organic fertilizer which is used in its culture medium. The objective of this study was to identify the best fermentation time by using probiotic bacteria on organic fertilizer as mass culture medium to improve its nutrient quality, biomass production, and growth performance. This study was conducted using completely randomized experimental design with five treatments and three repetitions. Organic fertilizers used cultured medium with chicken manure, rejected bread and tofu waste fermented by probiotic bacteria then cultured for 0, 7, 14, 21 and 28 days. The results showed that medium which used 25% chicken manure, 25% tofu waste and 50% rejected bread cultured for 28 days created the highest biomass production, population density and nutrient content of D. magna those are 233,980 ind/L for population density; 134.60 grams for biomass production, 0.574% specific growth rate; 68.06% protein content and 6.91% fat. The highest fatty acid profile is 4.83% linoleic and 3.54% linolenic acid. The highest essential amino acid is 53.94 ppm lysine. In general, the content of ammonia, DO, temperature, and pH during the study were in the good range of D. magna life. The conclusion of this research is medium which used 25% chicken manure, 25% tofu waste and 50% rejected bread cultured for 28 days created the highest biomass production, population and nutrient content of D. magna.

Symbiotic bacteria contribute to increasing the population size of a freshwater crustacean, Daphnia magna.

Science.gov (United States)

Peerakietkhajorn, Saranya; Tsukada, Koji; Kato, Yasuhiko; Matsuura, Tomoaki; Watanabe, Hajime

2015-04-01

The filter-feeding crustacean Daphnia is a key organism in freshwater ecosystems. Here, we report the effect of symbiotic bacteria on ecologically important life history traits, such as population dynamics and longevity, in Daphnia magna. By disinfection of the daphniid embryos with glutaraldehyde, aposymbiotic daphniids were prepared and cultured under bacteria-free conditions. Removal of bacteria from the daphniids was monitored by quantitative polymerase chain reaction for bacterial 16S rRNA gene. The population of aposymbiotic daphniids was reduced 10-folds compared with that of the control daphniids. Importantly, re-infection with symbiotic bacteria caused daphniids to regain bacteria and increase their fecundity to the level of the control daphniids, suggesting that symbiotic bacteria regulate Daphnia fecundity. To identify the species of symbiotic bacteria, 16S rRNA genes of bacteria in daphniids were sequenced. This revealed that 50% of sequences belonged to the Limnohabitans sp. of the Betaproteobacteria class and that the diversity of bacterial taxa was relatively low. These results suggested that symbiotic bacteria have a beneficial effect on D. magna, and that aposymbiotic Daphnia are useful tools in understanding the role of symbiotic bacteria in the environmental responses and evolution of their hosts. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

Trophic transfer of differently functionalized zinc oxide nanoparticles from crustaceans (Daphnia magna) to zebrafish (Danio rerio)

DEFF Research Database (Denmark)

Skjolding, Lars Michael; Winther-Nielsen, M.; Baun, Anders

2014-01-01

) higher than toxic levels reported for zinc in D. magna. Consequently, the zinc recovered in the animals was not solely due to soluble zinc, but agglomerates/aggregates of ZnO NP or ZnO-octyl NP contributed to the body burdens. The trophic transfer study showed uptake of both ZnO NP and ZnO-octyl NP...

The Fluid Dynamical Performance of the Carpentier-Edwards PERIMOUNT Magna Ease Prosthesis

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Philipp Marx

2018-01-01

Full Text Available The aim of the present in vitro study was the evaluation of the fluid dynamical performance of the Carpentier-Edwards PERIMOUNT Magna Ease depending on the prosthetic size (21, 23, and 25 mm and the cardiac output (3.6–6.4 L/min. A self-constructed flow channel in combination with particle image velocimetry (PIV enabled precise results with high reproducibility, focus on maximal and local peek velocities, strain, and velocity gradients. These flow parameters allow insights into the generation of forces that act on blood cells and the aortic wall. The results showed that the 21 and 23 mm valves have a quite similar performance. Maximal velocities were 3.03±0.1 and 2.87±0.13 m/s; maximal strain Exx, 913.81±173.25 and 896.15±88.16 1/s; maximal velocity gradient Eyx, 1203.14±221.84 1/s and 1200.81±61.83 1/s. The 25 mm size revealed significantly lower values: maximal velocity, 2.47±0.15 m/s; maximal strain Exx, 592.98±155.80 1/s; maximal velocity gradient Eyx, 823.71±38.64 1/s. In summary, the 25 mm Magna Ease was able to create a wider, more homogenous flow with lower peak velocities especially for higher flow rates. Despite the wider flow, the velocity values close to the aortic walls did not exceed the level of the smaller valves.

Gene transcription in Daphnia magna: effects of acute exposure to a carbamate insecticide and an acetanilide herbicide.

Science.gov (United States)

Pereira, Joana Luísa; Hill, Christopher J; Sibly, Richard M; Bolshakov, Viacheslav N; Gonçalves, Fernando; Heckmann, Lars-Henrik; Callaghan, Amanda

2010-05-05

Daphnia magna is a key invertebrate in the freshwater environment and is used widely as a model in ecotoxicological measurements and risk assessment. Understanding the genomic responses of D. magna to chemical challenges will be of value to regulatory authorities worldwide. Here we exposed D. magna to the insecticide methomyl and the herbicide propanil to compare phenotypic effects with changes in mRNA expression levels. Both pesticides are found in drainage ditches and surface water bodies standing adjacent to crops. Methomyl, a carbamate insecticide widely used in agriculture, inhibits acetylcholinesterase, a key enzyme in nerve transmission. Propanil, an acetanilide herbicide, is used to control grass and broad-leaf weeds. The phenotypic effects of single doses of each chemical were evaluated using a standard immobilisation assay. Immobilisation was linked to global mRNA expression levels using the previously estimated 48h-EC(1)s, followed by hybridization to a cDNA microarray with more than 13,000 redundant cDNA clones representing >5000 unique genes. Following exposure to methomyl and propanil, differential expression was found for 624 and 551 cDNAs, respectively (one-way ANOVA with Bonferroni correction, P

Sequence Conservation and Sexually Dimorphic Expression of the Ftz-F1 Gene in the Crustacean Daphnia magna.

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Nur Syafiqah Mohamad Ishak

Full Text Available Identifying the genes required for environmental sex determination is important for understanding the evolution of diverse sex determination mechanisms in animals. Orthologs of Drosophila orphan receptor Fushi tarazu factor-1 (Ftz-F1 are known to function in genetic sex determination. In contrast, their roles in environmental sex determination remain unknown. In this study, we have cloned and characterized the Ftz-F1 ortholog in the branchiopod crustacean Daphnia magna, which produces males in response to environmental stimuli. Similar to that observed in Drosophila, D. magna Ftz-F1 (DapmaFtz-F1 produces two splicing variants, αFtz-F1 and βFtz-F1, which encode 699 and 777 amino acids, respectively. Both isoforms share a DNA-binding domain, a ligand-binding domain, and an AF-2 activation domain and differ only at the A/B domain. The phylogenetic position and genomic structure of DapmaFtz-F1 suggested that this gene has diverged from an ancestral gene common to branchiopod crustacean and insect Ftz-F1 genes. qRT-PCR showed that at the one cell and gastrulation stages, both DapmaFtz-F1 isoforms are two-fold more abundant in males than in females. In addition, in later stages, their sexual dimorphic expressions were maintained in spite of reduced expression. Time-lapse imaging of DapmaFtz-F1 RNAi embryos was performed in H2B-GFP expressing transgenic Daphnia, demonstrating that development of the RNAi embryos slowed down after the gastrulation stage and stopped at 30-48 h after ovulation. DapmaFtz-F1 shows high homology to insect Ftz-F1 orthologs based on its amino acid sequence and exon-intron organization. The sexually dimorphic expression of DapmaFtz-F1 suggests that it plays a role in environmental sex determination of D. magna.

Interactive effects of a bacterial parasite and the insecticide carbaryl to life-history and physiology of two Daphnia magna clones differing in carbaryl sensitivity.

Science.gov (United States)

De Coninck, Dieter I M; De Schamphelaere, Karel A C; Jansen, Mieke; De Meester, Luc; Janssen, Colin R

2013-04-15

Natural and chemical stressors occur simultaneously in the aquatic environment. Their combined effects on biota are usually difficult to predict from their individual effects due to interactions between the different stressors. Several recent studies have suggested that synergistic effects of multiple stressors on organisms may be more common at high compared to low overall levels of stress. In this study, we used a three-way full factorial design to investigate whether interactive effects between a natural stressor, the bacterial parasite Pasteuria ramosa, and a chemical stressor, the insecticide carbaryl, were different between two genetically distinct clones of Daphnia magna that strongly differ in their sensitivity to carbaryl. Interactive effects on various life-history and physiological endpoints were assessed as significant deviations from the reference Independent Action (IA) model, which was implemented by testing the significance of the two-way carbaryl×parasite interaction term in two-way ANOVA's on log-transformed observational data for each clone separately. Interactive effects (and thus significant deviations from IA) were detected in both the carbaryl-sensitive clone (on survival, early reproduction and growth) and in the non-sensitive clone (on growth, electron transport activity and prophenoloxidase activity). No interactions were found for maturation rate, filtration rate, and energy reserve fractions (carbohydrate, protein, lipid). Furthermore, only antagonistic interactions were detected in the non-sensitive clone, while only synergistic interactions were observed in the carbaryl sensitive clone. Our data clearly show that there are genetically determined differences in the interactive effects following combined exposure to carbaryl and Pasteuria in D. magna. Copyright © 2013 Elsevier B.V. All rights reserved.

To flee or not to flee: detection, avoidance and attraction of profitable resources by Daphnia magna studied with olfactometer

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Johann P. Müller

2013-10-01

Full Text Available The cladoceran herbivore Daphnia magna is a major consumer of phytoplankton in lakes. Therefore, this organism may control the phytoplankton community and the proliferation of some algae or cyanobacteria. Cladoceran behaviour and migration in relation to temperature, light or presence of planktivorous fishes have been well studied. In particular, it is known that the detection of kairomones produced by predators may induce avoidance. Avoidance could also occur with other semiochemicals such as cyanotoxins. In order to explore this hypothesis, we used an olfactometer to observe and measure the exploratory behaviour of D. magna individuals based on the motivation for food. Daphnids were allowed to choose between different compounds: water, a pure cyanotoxin, i.e. the microcystin-RR [(MC-RR], extracts of one MC-producing strain (PMC 75.02 and one MC-free strain (PMC 87.02 of Planktothrix agardhii, or a green algae Scenedesmus obliquus. With this experimental design, we observed that i cladocerans are able to detect resources with different qualities, ii they can explore before exhibiting preferences, and iii daphnids are able to avoid compounds that are potentially toxic (e.g., microcystins. First, daphnids explored the environment, subsequently (after about 1.5 h, they showed a significant tendency to stay where there is a profitable resource such as S. obliquus. These results also suggest that specimens of D. magna cannot detect MC compounds from P. agardhii, but they respond to it as a food resource. The study of zooplankton ability to explore the environment when exposed to semiochemicals needs further investigation. 

Genomic integration and germline transmission of plasmid injected into crustacean Daphnia magna eggs.

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Yasuhiko Kato

Full Text Available The water flea, Daphnia, has been the subject of study in ecology, evolution, and environmental sciences for decades. Over the last few years, expressed sequence tags and a genome sequence have been determined. In addition, functional approaches of overexpression and gene silencing based on microinjection of RNAs into eggs have been established. However, the transient nature of these approaches prevents us from analyzing gene functions in later stages of development. To overcome this limitation, transgenesis would become a key tool. Here we report establishment of a transgenic line using microinjection of plasmid into Daphnia magna eggs. The green fluorescent protein (GFP gene fused with the D. magna histone H2B gene under the control of a promoter/enhancer region of the elongation factor 1α-1 (EF1α-1 gene, EF1α-1::H2B-GFP, was used as a reporter providing high resolution visualization of active chromatin. Transgenic lines were obtained from 0.67% of the total fertile adults that survived the injections. One of the transgenic animals, which exhibited fluorescence in the nuclei of cells during embryogenesis and oogenesis, had two copies of EF1α-1::H2B-GFP in a head-to-tail array. This is the first report of a transgenesis technique in Daphnia and, together with emerging genome sequences, will be useful for advancing knowledge of the molecular biology of Daphnia.

The Principle Of Justice In Magna Carta Libertatum And Its Influence On The Law In General

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Zendeli Emine

2015-12-01

Full Text Available This article aims to expound the principle of justice, as a fundamental value and as an immanent category of law, as well as one of the fundamental human rights, prescribed and guaranteed by a myriad of international instruments and documents. After a brief historical account, by focusing on Article 40 of the Magna Carta Libertatum, which states that: “To No One Will we Sell, To No One Will we refuse or delay, right or justice”, this article claims to show the importance of incorporation of this principle in the provisions of the Magna Carta and its impact on the development of theory and legislation in the past and present. Moreover, the article intends to explore the extent of influence that the priciple of justice has on the functioning of the law in general. Since justice implicates the permanent and constant will to render each person his due, and this achieved through equality, it results that justice means being equal. In this context, the article will explore the concept of equality as a precondition of justice, as well as the conditions and modalities for its implementation.

Effect of carbaryl (carbamate insecticide) on acetylcholinesterase activity of two strains of Daphnia magna (Crustacea, Cladocera).

Science.gov (United States)

Toumi, Hela; Bejaoui, Mustapha; Touaylia, Samir; Burga Perez, Karen F; Ferard, Jean François

2016-11-01

The present study was designed to investigate the effect of carbaryl (carbamate insecticide) on the acetylcholinesterase activity in two strains (same clone A) of the crustacean cladoceran Daphnia magna. Four carbaryl concentrations (0.4, 0.9, 1.8 and 3.7 µg L(-1)) were compared against control AChE activity. Our results showed that after 48 h of carbaryl exposure, all treatments induced a significant decrease of AChE activities whatever the two considered strains. However, different responses were registered in terms of lowest observed effect concentrations (LOEC: 0.4 µg L(-1) for strain 1 and 0.9 µg L(-1) for strains 2) revealing differences in sensitivity among the two tested strains of D. magna. These results suggest that after carbaryl exposure, the AChE activity responses can be also used as a biomarker of susceptibility. Moreover, our results show that strain1 is less sensitive than strain 2 in terms of IC50-48 h of AChE activity. Comparing the EC50-48 h of standard ecotoxicity test and IC50-48 h of AChE inhibition, there is the same order of sensitivity with both strains.

A Case with Mega Cisterna Magna Renal and Ear Anomalies: Is This a New Syndrome?

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Çapan Konca

2013-01-01

Full Text Available Background. Extrarenal pathologies may be associated with renal position and fusion anomalies. According to the literature, our patient is the first horseshoe kidney case that had mega cisterna magna, arachnodactyly, and mild mental retardation. Case Report. A 9-year-old boy admitted because of the myoclonic jerks. He had a dysmorphic face, low-set and cup-shaped ears, arachnodactyly, and mild mental retardation. The patient’s laboratory findings were normal except for a mild leucocytosis and hypochromic microcytic anemia. His cerebrospinal fluid was cytologically and biochemically normal. Cranial MRI revealed 1.5 cm diametered mega cisterna magna in the retrocerebellar region. Although there were no significant epileptical discharges in the electroencephalography, there were slow wave discharges arising from the anterior regions of both hemispheres. Because he had stomachache, abdominal ultrasonography was performed, and horseshoe kidney was determined. Abdominal CT did not reveal any abnormalities except the horseshoe kidney. There were not any cardiac pathologies in echocardiography. He had normal 46XY karyotype and there were no repeated chromosomal derangements, but we could not evaluate for molecular and submicroscopic somatic changes. He was treated with valproic acid and myoclonic jerks did not repeat. Conclusion. We suggest that the presence of these novel findings may represent a newly recognized, separate syndrome.

Structural and functional studies of the modulator NS9283 reveal agonist-like mechanism of action at α4β2 nicotinic acetylcholine receptors

DEFF Research Database (Denmark)

Olsen, Jeppe A; Ahring, Philip K; Kastrup, Jette Sandholm Jensen

2014-01-01

Modulation of Cys loop receptor ion channels is a proven drug discovery strategy, but many underlying mechanisms of the mode of action are poorly understood. We report the x-ray structure of the acetylcholine-binding protein from Lymnaea stagnalis with NS9283, a stoichiometry selective positive...... on efficacy. The shared modulatory profile along with a binding site located in an extracellular subunit interface suggest that modulation via an agonist-like mechanism may be a common mechanism of action that potentially could apply to Cys loop receptors beyond the α4β2 nAChRs....... modulator that targets the α4-α4 interface of α4β2 nicotinic acetylcholine receptors (nAChRs). Together with homology modeling, mutational data, quantum mechanical calculations, and pharmacological studies on α4β2 nAChRs, the structure reveals a modulator binding mode that overlaps the α4-α4 interface...

An investigation of the inter-clonal variation of the interactive effects of cadmium and Microcystis aeruginosa on the reproductive performance of Daphnia magna

International Nuclear Information System (INIS)

De Coninck, Dieter I.M.; Janssen, Colin R.; De Schamphelaere, Karel A.C.

2013-01-01

Highlights: •Interaction of a metal and cyanobacterium in 20 genetically distinct waterflea clones. •All observed effects were non-interactive. •This contrasted expectations based on shared modes of toxic action. -- Abstract: Interactive effects between chemical and natural stressors as well as genetically determined variation in stress tolerance among individuals may complicate risk assessment and management of chemical pollutants in natural ecosystems. Although genetic variation in tolerance to single stressors has been described extensively, genetic variation in interactive effects between two stressors has only rarely been investigated. Here, we examined the interactive effects between a chemical stressor (Cd) and a natural stressor (the cyanobacteria Microcystis aeruginosa) on the reproduction of Daphnia magna in 20 genetically different clones using a full-factorial experimental design and with the independent action model of joint stressor action as the reference theoretical framework. Across all clones, the reduction of 21-day reproduction compared to the control treatment (no Cd, no M. aeruginosa) ranged from −10% to 98% following Cd exposure alone, from 44% to 89% for Microcystis exposure alone, and from 61% to 98% after exposure to Cd + Microcystis combined. Three-way ANOVA on log-transformed reproduction data of all clones together did not detect a statistically significant Cd × Microcystis interaction term (F-test, p = 0.11), meaning that on average both stressors do not interact in inhibiting reproductive performance of D. magna. This finding contrasted expectations based on some known shared mechanisms of toxicity of Cd and Microcystis and therefore cautions against making predictions of interactive chemical + natural stressor effects from incomplete knowledge on affected biological processes and pathways. Further, still based on three-way ANOVA, we did not find statistically significant clone × Cd × Microcystis interaction when data for

An investigation of the inter-clonal variation of the interactive effects of cadmium and Microcystis aeruginosa on the reproductive performance of Daphnia magna

Energy Technology Data Exchange (ETDEWEB)

De Coninck, Dieter I.M., E-mail: Dieter.DeConinck@UGent.be; Janssen, Colin R.; De Schamphelaere, Karel A.C.

2013-09-15

Highlights: •Interaction of a metal and cyanobacterium in 20 genetically distinct waterflea clones. •All observed effects were non-interactive. •This contrasted expectations based on shared modes of toxic action. -- Abstract: Interactive effects between chemical and natural stressors as well as genetically determined variation in stress tolerance among individuals may complicate risk assessment and management of chemical pollutants in natural ecosystems. Although genetic variation in tolerance to single stressors has been described extensively, genetic variation in interactive effects between two stressors has only rarely been investigated. Here, we examined the interactive effects between a chemical stressor (Cd) and a natural stressor (the cyanobacteria Microcystis aeruginosa) on the reproduction of Daphnia magna in 20 genetically different clones using a full-factorial experimental design and with the independent action model of joint stressor action as the reference theoretical framework. Across all clones, the reduction of 21-day reproduction compared to the control treatment (no Cd, no M. aeruginosa) ranged from −10% to 98% following Cd exposure alone, from 44% to 89% for Microcystis exposure alone, and from 61% to 98% after exposure to Cd + Microcystis combined. Three-way ANOVA on log-transformed reproduction data of all clones together did not detect a statistically significant Cd × Microcystis interaction term (F-test, p = 0.11), meaning that on average both stressors do not interact in inhibiting reproductive performance of D. magna. This finding contrasted expectations based on some known shared mechanisms of toxicity of Cd and Microcystis and therefore cautions against making predictions of interactive chemical + natural stressor effects from incomplete knowledge on affected biological processes and pathways. Further, still based on three-way ANOVA, we did not find statistically significant clone × Cd × Microcystis interaction when data for

Classification of solid industrial waste based on ecotoxicology tests using Daphnia magna: an alternative

OpenAIRE

William Gerson Matias; Vanessa Guimarães Machado; Cátia Regina Silva de Carvalho-Pinto; Débora Monteiro Brentano; Letícia Flohr

2005-01-01

The adequate treatment and final disposal of solid industrial wastes depends on their classification into class I or II. This classification is proposed by NBR 10.004; however, it is complex and time-consuming. With a view to facilitating this classification, the use of assays with Daphnia magna is proposed. These assays make possible the identification of toxic chemicals in the leach, which denotes the presence of one of the characteristics described by NBR 10.004, the toxicity, which is a s...

Is ultraviolet radiation a synergistic stressor in combined exposures? The case study of Daphnia magna exposure to UV and carbendazim

International Nuclear Information System (INIS)

Ribeiro, Fabianne; Ferreira, Nuno C.G.; Ferreira, Abel; Soares, Amadeu M.V.M.; Loureiro, Susana

2011-01-01

The toxicological assessment of chemical compounds released to the environment is more accurate when mixtures of chemicals and/or interactions between chemicals and natural stressors are considered. Ultraviolet radiation can be taken as a natural stressor since the levels of UV are increasing due to the decrease of its natural filter, the stratospheric ozone concentration. Therefore, a combination of chemical exposures and increasing UV irradiance in aquatic environments is likely to occur. In the current study, combined effects of carbendazim and ultraviolet radiation were evaluated, using selected life traits as endpoints on Daphnia magna. To design combined exposures, first single chemical and natural stressor bioassays were performed: a reproduction test with carbendazim and a reproduction, feeding inhibition and Energy budget test with ultraviolet radiation. Following single exposures, the combinations of stressors included exposures to UV radiation and carbendazim for a maximum exposure time of 4 h, followed by a post-exposure period in chemically contaminated medium for a maximum of 15 days, depending on the endpoint, where the effects of the combined exposures were investigated. Statistical analyses of the data set were performed using the MixTox tool and were based on the conceptual model of Independent Action (IA) and possible deviations to synergism or antagonism, dose-ratio or dose-level response pattern. Both ultraviolet radiation and carbendazim as single stressors had negative impacts on the measured life traits of daphnids, a decrease on both feeding rates and reproduction was observed. Feeding rates and reproduction of D. magna submitted to combined exposures of ultraviolet radiation and carbendazim showed a dose-ratio deviation from the conceptual model as the best description of the data set, for both endpoints. For feeding inhibition, antagonism was observed when the UV radiation was the dominant item in combination, and for reproduction

Daphnia magna shows reduced infection upon secondary exposure to a pathogen.

Science.gov (United States)

McTaggart, Seanna J; Wilson, Philip J; Little, Tom J

2012-12-23

Previous pathogen exposure is an important predictor of the probability of becoming infected. This is deeply understood for vertebrate hosts, and increasingly so for invertebrate hosts. Here, we test if an initial pathogen exposure changes the infection outcome to a secondary pathogen exposure in the natural host-pathogen system Daphnia magna and Pasteuria ramosa. Hosts were initially exposed to an infective pathogen strain, a non-infective pathogen strain or a control. The same hosts underwent a second exposure, this time to an infective pathogen strain, either immediately after the initial encounter or 48 h later. We observed that an initial encounter with a pathogen always conferred protection against infection compared with controls.

The critical importance of defined media conditions in Daphnia magna nanotoxicity studies.

Science.gov (United States)

Römer, Isabella; Gavin, Alex J; White, Thomas A; Merrifield, Ruth C; Chipman, James K; Viant, Mark R; Lead, Jamie R

2013-10-23

Due to the widespread use of silver nanoparticles (AgNPs), the likelihood of them entering the environment has increased and they are known to be potentially toxic. Currently, there is little information on the dynamic changes of AgNPs in ecotoxicity exposure media and how this may affect toxicity. Here, the colloidal stability of three different sizes of citrate-stabilized AgNPs was assessed in standard strength OECD ISO exposure media, and in 2-fold (media2) and 10-fold (media10) dilutions by transmission electron microscopy (TEM) and atomic force microscopy (AFM) and these characteristics were related to their toxicity towards Daphnia magna. Aggregation in undiluted media (media1) was rapid, and after diluting the medium by a factor of 2 or 10, aggregation was reduced, with minimal aggregation over 24h occurring in media10. Acute toxicity measurements were performed using 7nm diameter particles in media1 and media10. In media10 the EC50 of the 7nm particles for D. magna neonates was calculated to be 7.46μgL(-1) with upper and lower 95% confidence intervals of 6.84μgL(-1) and 8.13μgL(-1) respectively. For media1, an EC50 could not be calculated, the lowest observed adverse effect concentration (LOAEC) of 11.25μgL(-1) indicating a significant reduction in toxicity compared to that in media10. The data suggest the increased dispersion of nanoparticles leads to enhanced toxicity, emphasising the importance of appropriate media composition to fully assess nanoparticle toxicity in aquatic ecotoxicity tests. Copyright © 2013 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Filming of zooplankton: a case study of rotifer males and Daphnia magna

Directory of Open Access Journals (Sweden)

Pierluigi Colangeli

2015-11-01

Full Text Available Filming live organisms can give new insights into the hidden life of plankton. Accessibly priced digital cameras are now available for a large range of users. Here, we demonstrate the technical setup and workflow of using a single-lens reflex (DSLR camera to film the behaviour of males of two rotifer species, Brachionus angularis Gosse (1851 and Keratella cochlearis Gosse (1851, and of the cladoceran Daphnia magna Straus (1820. Rotifers are cyclical parthenogens that produce males only under certain environmental conditions. Thus, knowledge on rotifer males is still limited because of their ephemeral nature and because they are often smaller than females. We filmed males of B. angularis and K. cochlearis with a DSLR camera connected to a compound microscope to better understand their morphology and behaviour in comparison to conspecific females. While written descriptions have their scientific value, seeing is complementary because everyone can verify what has been described. We made our videos publicly accessible through links connected to the paper. Our videos are, to our best knowledge, the first on males of B. angularis and K. cochlearis. Furthermore, we filmed the behavioural response of D. magna to ultraviolet (UV radiation with a macro lens attached to the DSLR camera. Approaches like this are valuable tools in environmental teaching. To see live organisms with one’s own eyes may contribute to raising public awareness about the value of water resources and their hidden communities. In summary, filming can be a valuable tool to ignite scientific discussion, but the videos need an open-access platform where they can be referenced in a topic-related order.

A3 Adenosine Receptor Allosteric Modulator Induces an Anti-Inflammatory Effect: In Vivo Studies and Molecular Mechanism of Action

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Shira Cohen

2014-01-01

Full Text Available The A3 adenosine receptor (A3AR is overexpressed in inflammatory cells and in the peripheral blood mononuclear cells of individuals with inflammatory conditions. Agonists to the A3AR are known to induce specific anti-inflammatory effects upon chronic treatment. LUF6000 is an allosteric compound known to modulate the A3AR and render the endogenous ligand adenosine to bind to the receptor with higher affinity. The advantage of allosteric modulators is their capability to target specifically areas where adenosine levels are increased such as inflammatory and tumor sites, whereas normal body cells and tissues are refractory to the allosteric modulators due to low adenosine levels. LUF6000 administration induced anti-inflammatory effect in 3 experimental animal models of rat adjuvant induced arthritis, monoiodoacetate induced osteoarthritis, and concanavalin A induced liver inflammation in mice. The molecular mechanism of action points to deregulation of signaling proteins including PI3K, IKK, IκB, Jak-2, and STAT-1, resulting in decreased levels of NF-κB, known to mediate inflammatory effects. Moreover, LUF6000 induced a slight stimulatory effect on the number of normal white blood cells and neutrophils. The anti-inflammatory effect of LUF6000, mechanism of action, and the differential effects on inflammatory and normal cells position this allosteric modulator as an attractive and unique drug candidate.

Physiological actions of corticosterone and its modulation by an immune challenge in reptiles.

Science.gov (United States)

Meylan, Sandrine; Haussy, Claudy; Voituron, Yann

2010-11-01

Hormones are an important interface between genome and environment, because of their ability to modulate the animal's phenotype. In particular, corticosterone, the stress hormone in lizards, is known to reallocate energy from non-essential functions to affect morphological, physiological and behavioral traits that help the organism to deal with acute or chronic stressors. However, the effects of corticosterone on life history stages are still unclear primarily because of the dependence of life history stages on both internal and external factors. Using a cross-design, we tested the effect of elevated levels of exogenous corticosterone on the physiology of pregnant females in different immune contexts in a wild population of common lizards (Lacerta vivipara). Immune challenge was induced by the injection of sheep red blood cells (SRBC) and corticosterone levels were increased using a transdermal administration of corticosterone. Thereafter, reproductive traits, metabolism and cellular immune responses were measured. The elevation of corticosterone in pregnant females significantly altered reproductive and physiological performance. The corticosterone treatment decreased clutch success, juvenile size and body condition, but enhanced measures of physiological performance, such as metabolism and catalase activity. These first results reinforce the understanding of the physiological actions of corticosterone in reptiles. The data also demonstrated different direct impacts of immune challenge by SRBC on inflammatory response and antioxidant activity. The injection of SRBC stimulated the SOD activity in larger females. Finally, we demonstrated experimentally the modulation of the corticosterone action by the immune challenge on stamina and hatching date. Copyright © 2010 Elsevier Inc. All rights reserved.

Deep brain stimulation of the subthalamic nucleus modulates reward processing and action selection in Parkinson patients.

Science.gov (United States)

Wagenbreth, Caroline; Zaehle, Tino; Galazky, Imke; Voges, Jürgen; Guitart-Masip, Marc; Heinze, Hans-Jochen; Düzel, Emrah

2015-06-01

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for motor impairments in Parkinson's disease (PD) but its effect on the motivational regulation of action control is still not fully understood. We investigated whether DBS of the STN influences the ability of PD patients to act for anticipated reward or loss, or whether DBS improves action execution independent of motivational valence. 16 PD patients (12 male, mean age = 58.5 ± 10.17 years) treated with bilateral STN-DBS and an age- and gender-matched group of healthy controls (HC) performed a go/no-go task whose contingencies explicitly decouple valence and action. Patients were tested with (ON) and without (OFF) active STN stimulation. For HC, there was a benefit in performing rewarded actions when compared to actions that avoided punishment. PD patients showed such a benefit reliably only when STN stimulation was ON. In fact, the relative behavioral benefit for go for reward over go to avoid losing was stronger in the PD patients under DBS ON than in HC. In PD patients, rather than generally improving motor functions independent of motivational valence, modulation of the STN by DBS improves action execution specifically when rewards are anticipated. Thus, STN-DBS establishes a reliable congruency between action and reward ("Pavlovian congruency") and remarkably enhances it over the level observed in HC.

Assessing mandated credit programs: Case study of the Magna Carta in the Philippines

Directory of Open Access Journals (Sweden)

Ryan Jacildo

2016-09-01

Full Text Available We examine the effects of a mandated credit program to small and medium enterprises in the Philippines (Magna Carta Law using a panel dataset compiled from official data published by the Bangko Sentral ng Pilipinas. The final sample of 109 financial institutions represented over 90% of total finance sector assets in the Philippines. We highlight three important findings. First, although the total lending levels to micro, small, and medium enterprises (MSMEs grew slightly, the percentage shares of loans allocated to MSMEs declined drastically from a peak of 30% of total loans in 2002 to 16.4% in 2010. Second, following the upwards revision of the loan target (from 6% to 8% for smaller firms in 2008, there was a sharp increase in noncompliance especially amongst universal and commercial banks. On the other hand, total loans to medium enterprises were still more than threefold larger than the targeted 2%. Third, there is an increased heterogeneity in optimal loan portfolio across banks. Most surprisingly, the absolute level of MSME lending by rural and cooperative banks declined since 2008. Direct compliance amongst universal and commercial banks decreased beginning in the late 2007, while that of thrift banks increased to almost 100%. Abolishing the Magna Carta targets for medium-sized enterprise loans would most likely yield little adverse effects. Meanwhile, efforts to improve financial access to MSMEs should focus on alternative nondistortionary ways to increase financing supply, such as improving institutional framework for informational availability and development of equity and bond markets for MSMEs.

Selected endocrine disrupting compounds (vinclozolin, flutamide, ketoconazole and dicofol): Effects on survival, occurrence of males, growth, molting and reproduction of Daphnia magna

Czech Academy of Sciences Publication Activity Database

Haeba, M. H.; Hilscherová, Klára; Mazurová, E.; Bláha, Luděk

2008-01-01

Roč. 15, č. 3 (2008), s. 222-227 ISSN 0944-1344 Institutional research plan: CEZ:AV0Z60050516 Keywords : Daphnia magna * dicofol * endocrine disruption Subject RIV: EF - Botanics Impact factor: 2.492, year: 2008

Mimicking Daphnia magna bioassay performance by an electronic tongue for urban water quality control

Energy Technology Data Exchange (ETDEWEB)

Kirsanov, Dmitry, E-mail: d.kirsanov@gmail.com [Laboratory of Chemical Sensors, St. Petersburg State University, St. Petersburg (Russian Federation); Laboratory of Artificial Sensor Systems, ITMO University, St. Petersburg (Russian Federation); Legin, Evgeny [Laboratory of Artificial Sensor Systems, ITMO University, St. Petersburg (Russian Federation); Sensor Systems LLC, St. Petersburg (Russian Federation); Zagrebin, Anatoly; Ignatieva, Natalia; Rybakin, Vladimir [Institute of Limnology, Russian Academy of Sciences, St. Petersburg (Russian Federation); Legin, Andrey [Laboratory of Chemical Sensors, St. Petersburg State University, St. Petersburg (Russian Federation); Laboratory of Artificial Sensor Systems, ITMO University, St. Petersburg (Russian Federation)

2014-05-01

Highlights: • -Daphnia magna bioassay can be simulated with multisensor system. • Urban water toxicity can be predicted from potentiometric ET data. • Independent test set validation confirms statistical significance of the results. - Abstract: Toxicity is one of the key parameters of water quality in environmental monitoring. However, being evaluated as a response of living beings (as their mobility, fertility, death rate, etc.) to water quality, toxicity can only be assessed with the help of these living beings. This imposes certain restrictions on toxicity bioassay as an analytical method: biotest organisms must be properly bred, fed and kept under strictly regulated conditions and duration of tests can be quite long (up to several days), thus making the whole procedure the prerogative of the limited number of highly specialized laboratories. This report describes an original application of potentiometric multisensor system (electronic tongue) when the set of electrochemical sensors was calibrated against Daphnia magna death rate in order to perform toxicity assessment of urban waters without immediate involvement of living creatures. PRM (partial robust M) and PLS (projections on latent structures) regression models based on the data from this multisensor system allowed for prediction of toxicity of unknown water samples in terms of biotests but in the fast and simple instrumental way. Typical errors of water toxicity predictions were below 20% in terms of Daphnia death rate which can be considered as a good result taking into account the complexity of the task.

Cisterna magna microdialysis of 22Na to evaluate ion transport and cerebrospinal fluid dynamics

International Nuclear Information System (INIS)

Knuckey, N.W.; Fowler, A.G.; Johanson, C.E.; Nashold, J.R.; Epstein, M.H.

1991-01-01

Microdialysis is used in vivo for measuring compounds in brain interstitial fluid. The authors describe another application of this technique to the central nervous system, namely microprobe dialysis in the cisterna magna to study the dynamics of ion transport and cerebrospinal fluid (CSF) formation in the rat. The choroid plexus is the major source of CSF, which is produced by active transport of Na from blood into the cerebral ventricles. Formation of CSF is directly proportional to the blood-to-CSF transport of Na. By injecting 22 Na into the systemic circulation and quantifying its movement into CSF by microdialysis, one can reliably estimate alterations in the rate of CSF formation. The sensitivity of this system was determined by administering acetazolamide, a standard inhibitor of CSF production. Because acetazolamide is known to decrease CSF formation by 40% to 50%, the cisternal microdialysis system in animals treated with this drug should detect a corresponding decrease in the amount of 22 Na dialyzed. This hypothesis is supported by the 22 Na uptake curves for control versus treated animals: that is, by the acetazolamide-induced average diminution of about 45% in both the rate and extent of tracer accession to dialysate. Bumetanide, a loop diuretic, reduced by 30% the 22 Na entry into dialysate. Microprobe dialysis of fluid in the cisterna magna is thus a minimally invasive and economical method for evaluating effects of drugs and hormones on the choroid plexus-CSF system

Relationships between acute toxicities of para nitrophenol (p-NP) and nitrobenzene (NB) to Daphnia magna and Photobacterium phosphoreum: Physicochemical properties and metabolites under anaerobic/aerobic sequentials

International Nuclear Information System (INIS)

Sponza, Delia Teresa; Kuscu, Ozlem Selcuk

2011-01-01

In this study, the acute toxicities of nitrobenzene (NB) and para nitrophenol (p-NP) were investigated in a high rate sequential anaerobic migrating blanket (AMBR)/aerobic completely stirred tank reactor (CSTR) using Microtox and Daphnia magna tests. After sequential anaerobic and aerobic treatments, the inhibitions in the Microtox bacteria decreased from an initial 78.10-48.20% and 4.00%, respectively, in wastewater containing 40.00 mg/L p-NP. The inhibitions of the influent wastewater containing 60.00 mg/L NB decreased from 72.10% to 45.30% and to 4.00% after anaerobic and aerobic treatment, respectively. The acute toxicity removals were 94% and 93% in the effluent of the whole sequential system, for p-NP and NB, respectively. The acute toxicity in the influent was dependent on the parent NB and p-NP concentrations and ons their physicochemical properties such as hydrophobicity, octanol/water partition coefficient and vapour density for both Microtox bacteria and Daphnia magna while the toxicity in the effluent of the anaerobic reactor was strongly dependent on the metabolites of p-NP (p-amino phenol, phenol, NH 4 -N) and NB (aniline) for Microtox test. This effluent was not toxic to Daphnia magna.

AAV9-mediated central nervous system–targeted gene delivery via cisterna magna route in mice

Directory of Open Access Journals (Sweden)

Vera Lukashchuk

2016-01-01

Full Text Available Current barriers to the use of adeno-associated virus serotype 9 (AAV9 in clinical trials for treating neurological disorders are its high expression in many off-target tissues such as liver and heart, and lack of cell specificity within the central nervous system (CNS when using ubiquitous promoters such as human cytomegalovirus (CMV or chicken-β-actin hybrid (CAG. To enhance targeting the transgene expression in CNS cells, self-complementary (sc AAV9 vectors, scAAV9-GFP vectors carrying neuronal Hb9 and synapsin 1, and nonspecific CMV and CAG promoters were constructed. We demonstrate that synapsin 1 and Hb9 promoters exclusively targeted neurons in vitro, although their strengths were up to 10-fold lower than that of CMV. In vivo analyses of mouse tissue after scAAV9-GFP vector delivery via the cisterna magna revealed a significant advantage of synapsin 1 promoter over both Hb9 variants in targeting neurons throughout the brain, since Hb9 promoters were driving gene expression mainly within the motor-related areas of the brain stem. In summary, this study demonstrates that cisterna magna administration is a safe alternative to intracranial or intracerebroventricular vector delivery route using scAAV9, and introduces a novel utility of the Hb9 promoter for the targeted gene expression for both in vivo and in vitro applications.

Resistance to a bacterial parasite in the crustacean Daphnia magna shows Mendelian segregation with dominance.

Science.gov (United States)

Luijckx, P; Fienberg, H; Duneau, D; Ebert, D

2012-05-01

The influence of host and parasite genetic background on infection outcome is a topic of great interest because of its pertinence to theoretical issues in evolutionary biology. In the present study, we use a classical genetics approach to examine the mode of inheritance of infection outcome in the crustacean Daphnia magna when exposed to the bacterial parasite Pasteuria ramosa. In contrast to previous studies in this system, we use a clone of P. ramosa, not field isolates, which allows for a more definitive interpretation of results. We test parental, F1, F2, backcross and selfed parental clones (total 284 genotypes) for susceptibility against a clone of P. ramosa using two different methods, infection trials and the recently developed attachment test. We find that D. magna clones reliably exhibit either complete resistance or complete susceptibility to P. ramosa clone C1 and that resistance is dominant, and inherited in a pattern consistent with Mendelian segregation of a single-locus with two alleles. The finding of a single host locus controlling susceptibility to P. ramosa suggests that the previously observed genotype-genotype interactions in this system have a simple genetic basis. This has important implications for the outcome of host-parasite co-evolution. Our results add to the growing body of evidence that resistance to parasites in invertebrates is mostly coded by one or few loci with dominance.

The Role of AChE in Swimming Behavior of Daphnia magna: Correlation Analysis of Both Parameters Affected by Deltamethrin and Methomyl Exposure

Directory of Open Access Journals (Sweden)

Qing Ren

2017-01-01

Full Text Available The unpredictable toxicity of insecticides may cause behavior disorder of biological organisms. In order to assess the role of acetylcholinesterase (AChE in swimming behavior of Daphnia magna, a correlation analysis of both parameters in 24 h exposure of deltamethrin (DM and methomyl (MT was investigated. The behavior responses of D. magna in DM (13.36 μg/L and 33.40 μg/L and MT (19.66 μg/L and 49.15 μg/L suggested that recovery behavior in the adjustment phase was crucial, and behavior homeostasis provided them with an optimal way to achieve a wider tolerance against environmental stress. During the experiment, positive effects on AChE activity occurred in the beginning of the exposure. Even though the de novo synthesis of AChE in D. magna might help it recover, the AChE inhibition in different treatments could be observed. Some induction effects on AChE activity at the beginning of exposure occurred, and a 50% decrease may cause toxic effects on behavior. In most treatments, the results showed that both behavior strength and AChE activity stayed in the same field within a correlation circle. These results illustrated that the environmental stress caused by both DM and MT could inhibit AChE activity and subsequently induce a stepwise behavior response, though both pesticides affect it as direct and indirect inhibitors, respectively.

Joint action modulates motor system involvement during action observation in 3-year-olds

NARCIS (Netherlands)

Meyer, M.; Hunnius, S.; Elk, M. van; Ede, F.L. van; Bekkering, H.

2011-01-01

When we are engaged in a joint action, we need to integrate our partner's actions with our own actions. Previous research has shown that in adults the involvement of one's own motor system is enhanced during observation of an action partner as compared to during observation of an individual actor.

Pressor response to L-cysteine injected into the cisterna magna of conscious rats involves recruitment of hypothalamic vasopressinergic neurons.

Science.gov (United States)

Takemoto, Yumi

2013-03-01

The sulfur-containing non-essential amino acid L-cysteine injected into the cisterna magna of adult conscious rats produces an increase in blood pressure. The present study examined if the pressor response to L-cysteine is stereospecific and involves recruitment of hypothalamic vasopressinergic neurons and medullary noradrenergic A1 neurons. Intracisternally injected D-cysteine produced no cardiovascular changes, while L-cysteine produced hypertension and tachycardia in freely moving rats, indicating the stereospecific hemodynamic actions of L-cysteine via the brain. The double labeling immunohistochemistry combined with c-Fos detection as a marker of neuronal activation revealed significantly higher numbers of c-Fos-positive vasopressinergic neurons both in the supraoptic and paraventricular nuclei and tyrosine hydroxylase containing medullary A1 neurons, of L-cysteine-injected rats than those injected with D-cysteine as iso-osmotic control. The results indicate that the cardiovascular responses to intracisternal injection of L-cysteine in the conscious rat are stereospecific and include recruitment of hypothalamic vasopressinergic neurons both in the supraoptic and paraventricular nuclei, as well as of medullary A1 neurons. The findings may suggest a potential function of L-cysteine as an extracellular signal such as neuromodulators in central regulation of blood pressure.

Assessing potential targets of calcium action in light-modulated gravitropism

Science.gov (United States)

Roux, S. J.

1995-01-01

Light, through the mediation of the pigment phytochrome, modulates the gravitropic response of the shoots and roots of many plants. The transduction of both light and gravity stimuli appears to involve Ca(2+)-regulated steps, one or more of which may represent points of intersection between the two transduction chains. To be confident that Ca2+ plays a critical role in stimulus-response coupling for gravitropism, it will be important to identify specific targets of Ca2+ action whose function can be clearly linked to the regulation of growth. Calcium typically exerts its influence on cell metabolism through binding to and activating key regulatory proteins. The three best characterized of these proteins in plants are the calmodulins, calcium-dependent protein kinases, and annexins. In this review we summarize what is known about the structure and function of these proteins and speculate on how their activation by Ca2+ could influence the differential growth response of gravitropism.

Arginine kinase in the cladoceran Daphnia magna: cDNA sequencing and expression is associated with resistance to toxic Microcystis.

Science.gov (United States)

Lyu, Kai; Zhang, Lu; Zhu, Xuexia; Cui, Guilian; Wilson, Alan E; Yang, Zhou

2015-03-01

Nutrient loading derived from anthropogenic activities into lakes have increased the frequency, severity and duration of toxic cyanobacterial blooms around the world. Although herbivorous zooplankton are generally considered to be unable to control toxic cyanobacteria, populations of some zooplankton, including Daphnia, have been shown to locally adapt to toxic cyanobacteria and suppress cyanobacterial bloom formation. However, little is known about the physiology of zooplankton behind this phenomenon. One possible explanation is that some zooplankton may induce more tolerance by elevating energy production, thereby adding more energy allocation to detoxification expenditure. It is assumed that arginine kinase (AK) serves as a core in temporal and spatial adenosine triphosphate (ATP) buffering in cells with high fluctuating energy requirements. To test this hypothesis, we studied the energetic response of a single Daphnia magna clone exposed to a toxic strain of Microcystis aeruginosa, PCC7806. Arginine kinase of D. magna (Dm-AK) was successfully cloned. An ATP-gua PtransN domain which was described as a guanidine substrate specificity domain and an ATP-gua Ptrans domain which was responsible for binding ATP were both identified in the Dm-AK. Phylogenetic analysis of AKs in a range of arthropod taxa suggested that Dm-AK was as dissimilar to other crustaceans as it was to insects. Dm-AK transcript level and ATP content in the presence of M. aeruginosa were significantly lower than those in the control diet containing only the nutritious chlorophyte, Scenedesmus obliquus, whereas the two parameters in the neonates whose mothers had been previously exposed to M. aeruginosa were significantly higher than those of mothers fed with pure S. obliquus. These findings suggest that Dm-AK might play an essential role in the coupling of energy production and utilization and the tolerance of D. magna to toxic cyanobacteria. Copyright © 2014 Elsevier B.V. All rights reserved.

Reducing Prosthesis-Patient Mismatch With Edwards Magna Prosthesis for Aortic Valve Replacement.

Science.gov (United States)

Kume, Yuta; Fujita, Tomoyuki; Fukushima, Satsuki; Hata, Hiroki; Shimahara, Yusuke; Matsumoto, Yorihiko; Yamashita, Kizuku; Kobayashi, Junjiro

2017-03-24

Prosthesis-patient mismatch (PPM) is associated with increased mid-term and long-term mortality rates after aortic valve replacement (AVR). This study aimed to evaluate the efficacy of the Carpentier-Edwards Perimount Magna and Magna Ease (CEPMs) aortic bioprostheses to reduce the incidence of PPM.Methods and Results:Altogether, 282 consecutive patients (113 women, mean age 69.9±9.9 years) underwent AVR with a CEPMs between 2008 and 2015. They were divided into 3 groups based on the risk of PPM as a result of their body surface area and aortic annular diameter (BSA/AnnD ratio): low-risk (LR) group: 0.64±0.05 m 2 /cm (n=94); medium-risk (MR) group: 0.73±0.02 m 2 /cm (n=94); high-risk (HR) group: 0.83±0.05 m 2 /cm (n=94). The 30-day mortality rate was 0.4%. The 5-year actuarial survival rates were 93.2%, 92.3%, and 94.8% for groups LR, MR, and HR, respectively. No explants as a result of structural valve deterioration occurred. No patients showed severe PPM, defined as a measured effective orifice area index (EOAI) <0.65 cm 2 /m 2 . Although there were significant (P<0.05) differences in EOAI (0.98±0.2, 0.90±0.21, and 0.88±0.1 cm 2 /m 2 among the LR, MR, and HR groups, respectively), the corresponding transvalvular mean pressure gradients (13.0±5.5, 12.3±4.0, 12.7±5.3 mmHg) and regression rates of the left ventricular mass (29.8%, 28.7%, 28.9%) were similar among groups. CEPMs provide low surgical risk and reduce the risks of PPM, even in HR patients, with excellent hemodynamics.

QSTR with extended topochemical atom (ETA) indices. 16. Development of predictive classification and regression models for toxicity of ionic liquids towards Daphnia magna

International Nuclear Information System (INIS)

Roy, Kunal; Das, Rudra Narayan

2013-01-01

Highlights: • Ionic liquids are not intrinsically ‘green chemicals’ and require toxicological assessment. • Predictive QSTR models have been developed for toxicity of ILs to Daphnia magna. • Simple two dimensional descriptors were used to reduce the computational burden. • Discriminant and regression based models showed appreciable predictivity and reproducibility. • The extracted features can be explored in designing novel environmentally-friendly agents. -- Abstract: Ionic liquids have been judged much with respect to their wide applicability than their considerable harmful effects towards the living ecosystem which has been observed in many instances. Hence, toxicological introspection of these chemicals by the development of predictive mathematical models can be of good help. This study presents an attempt to develop predictive classification and regression models correlating the structurally derived chemical information of a group of 62 diverse ionic liquids with their toxicity towards Daphnia magna and their interpretation. We have principally used the extended topochemical atom (ETA) indices along with various topological non-ETA and thermodynamic parameters as independent variables. The developed quantitative models have been subjected to extensive statistical tests employing multiple validation strategies from which acceptable results have been reported. The best models obtained from classification and regression studies captured necessary structural information on lipophilicity, branching pattern, electronegativity and chain length of the cationic substituents for explaining ecotoxicity of ionic liquids towards D. magna. The derived information can be successfully used to design better ionic liquid analogues acquiring the qualities of a true eco-friendly green chemical

Phenoloxidase but not lytic activity reflects resistance against Pasteuria ramosa in Daphnia magna.

Science.gov (United States)

Pauwels, Kevin; De Meester, Luc; Decaestecker, Ellen; Stoks, Robby

2011-02-23

The field of ecological immunology strongly relies on indicators of immunocompetence. Two major indicators in invertebrates, the activity of phenoloxidase (PO) and lytic activity have recently been questioned in studies showing that, across a natural range of baseline levels, these indicators did not predict resistance against a manipulated challenge with natural parasites. We confirmed this finding by showing that baseline levels of PO and lytic activity in the host Daphnia magna were not related to spore load of the parasite Pasteuria ramosa. Yet, PO levels in infected hosts did predict spore load, indicating PO activity can be useful as an indicator of immunocompetence in this model parasite-host system.

Acute and chronic toxicity of buprofezin on Daphnia magna and the recovery evaluation.

Science.gov (United States)

Liu, Yong; Qi, Suzhen; Zhang, Wen; Li, Xuefeng; Qiu, Lihong; Wang, Chengju

2012-11-01

The toxic effects of buprofezin on Daphnia magna after both chronic and acute exposures were evaluated according to OECD guidelines. A 48-h acute exposure of buprofezin resulted in daphnid immobility at an EC(50) of 0.44 mg/L. In a 14 days chronic exposure of buprofezin (0, 0.025, 0.05, 0.10 and 0.15 mg/L), the development and reproduction of daphnids were all significantly affected and the body length was more sensitive than other observed parameters. However, the adverse effects of buprofezin on parental daphnids can be passed on to their offspring and cannot be recovered in a short time.

Cadmium tolerance in seven Daphnia magna clones is associated with reduced hsp70 baseline levels and induction

International Nuclear Information System (INIS)

Haap, Timo; Koehler, Heinz-R.

2009-01-01

The stress protein hsp70 is part of the intracellular alarm and repair system which enables organisms to counteract negative effects of toxicants on protein integrity. Under long-term selection pressure exerted by environmental pollution, in particular heavy metals, this system may be expected to play a major role in the course of local, microevolutionary events leading to the acquisition of toxicant resistance. Seven clones of Daphnia magna from different geographical regions were characterized regarding their sensitivity to Cd, their hsp70 expression, and Cd accumulation. In an acute immobilisation assay, the tested clones showed remarkable differences in their sensitivity to Cd. The highest EC 50 values by far were obtained for the clone displaying lowest hsp70 expression. In general, hsp70 levels reflected the order of sensitivity to Cd among the seven clones reciprocally. Clonal variations in sensitivity and hsp70 expression could not be related to differential accumulation of Cd, though. In summary, the association of stress insensitivity with low hsp70 induction which has been exemplarily reported for populations of different invertebrates under strong selection pressure could be affirmed for a largely parthenogenetic species for the first time. Furthermore, our observation has serious consequences for the interpretation of toxicological assays using a single D. magna clone solely.

Relationships between acute toxicities of para nitrophenol (p-NP) and nitrobenzene (NB) to Daphnia magna and Photobacterium phosphoreum: Physicochemical properties and metabolites under anaerobic/aerobic sequentials

Energy Technology Data Exchange (ETDEWEB)

Sponza, Delia Teresa, E-mail: delya.sponza@deu.edu.tr [Dokuz Eyluel University, Engineering Faculty, Environmental Engineering Department, Buca Kaynaklar Campus, Buca, Izmir (Turkey); Kuscu, Ozlem Selcuk [Department of Environmental Engineering, Engineering and Architecture Faculty, Sueleyman Demirel University, Cuenuer Campus, 32260 Isparta (Turkey)

2011-01-30

In this study, the acute toxicities of nitrobenzene (NB) and para nitrophenol (p-NP) were investigated in a high rate sequential anaerobic migrating blanket (AMBR)/aerobic completely stirred tank reactor (CSTR) using Microtox and Daphnia magna tests. After sequential anaerobic and aerobic treatments, the inhibitions in the Microtox bacteria decreased from an initial 78.10-48.20% and 4.00%, respectively, in wastewater containing 40.00 mg/L p-NP. The inhibitions of the influent wastewater containing 60.00 mg/L NB decreased from 72.10% to 45.30% and to 4.00% after anaerobic and aerobic treatment, respectively. The acute toxicity removals were 94% and 93% in the effluent of the whole sequential system, for p-NP and NB, respectively. The acute toxicity in the influent was dependent on the parent NB and p-NP concentrations and ons their physicochemical properties such as hydrophobicity, octanol/water partition coefficient and vapour density for both Microtox bacteria and Daphnia magna while the toxicity in the effluent of the anaerobic reactor was strongly dependent on the metabolites of p-NP (p-amino phenol, phenol, NH{sub 4}-N) and NB (aniline) for Microtox test. This effluent was not toxic to Daphnia magna.

Evaluation of Baffle Fixes Film up Flow Sludge Blanket Filtration (BFUSBF System in Treatment of Wastewaters from Phenol and 2,4-Dinitrophenol Using Daphnia Magna Bioassay

Directory of Open Access Journals (Sweden)

Mohammad Javad Ghannadzadeh

2016-02-01

Full Text Available Background: Phenol and nitrophenol are common compounds found in different types of industrial wastewater known as serious threats to human health and natural environment. In this study, Daphnia magna was used to evaluate the effectiveness of "baffle fixes film up flow sludge blanket filtration" (BFUSBF system in elimination of phenolic compounds from water. Methods: D. magna cultures were used as toxicity index of phenol and 2,4-DNP mixtures after treatment by a pilot BFUSBF system which consisted of baffle in anoxic section and biofilm in aerobic sections. Initial concentrations were 312 mg/L phenol and 288 mg/L 2,4-dinitrophenol (2,4-DNP. Results: Bioassay tests showed that D. magna was influenced by the toxicity of phenol and 2,4 DNP mixtures. The comparison between the toxicity of initial phenol and 2,4-DNP mixtures and the output toxic unit (TU derived from BFUSBF treatment system showed that the TU of the effluent from BFUSBF reactor was much lower than that of the solution that entered the reactor. Conclusion: Based on the acute toxicity test, BFUSBF process could reduce phenol and 2,4-DNP in aqueous solutions. Therefore, it is possible to use BFUSBF process as an appropriate treatment option for wastewaters containing phenolic compounds.

The effect of temperature on the sensitivity of Daphnia magna to cyanobacteria is genus dependent.

Science.gov (United States)

Hochmuth, Jennifer D; De Schamphelaere, Karel A C

2014-10-01

In the present study, the authors investigated the effects of 6 different genera of cyanobacteria on multiple endpoints of Daphnia magna in a 21-d life table experiment conducted at 3 different temperatures (15 °C, 19 °C, and 23 °C). The specific aims were to test if the effect of temperature on Daphnia's sensitivity to cyanobacteria differed among different cyanobacteria and if the rank order from most to least harmful cyanobacteria to Daphnia reproduction changed or remained the same across the studied temperature range. Overall, the authors observed a decrease in harmful effects on reproduction with increasing temperature for Microcystis, Nodularia, and Aphanizomenon, and an increase in harmful effects with increasing temperature for Anabaena and Oscillatoria. No effect of temperature was observed on Daphnia sensitivity to Cylindrospermopsis. Harmful effects of Microcystis and Nodularia on reproduction appear to be mirrored by a decrease in length. On the other hand, harmful effects of Anabaena, Aphanizomenon, and Oscillatoria on reproduction were correlated with a decrease in intrinsic rate of natural increase, which was matched by a later onset of reproduction in exposures to Oscillatoria. In addition, the results suggest that the cyanobacteria rank order of harmfulness may change with temperature. Higher temperatures may increase the sensitivity of D. magna to the presence of some cyanobacteria (Anabaena and Oscillatoria) in their diet, whereas the harmful effects of others (Microcystis, Nodularia, and Aphanizomenon) may be reduced by higher temperatures. © 2014 SETAC.

Effect of pH and ionic strength on exposure and toxicity of encapsulated lambda-cyhalothrin to Daphnia magna.

Science.gov (United States)

Son, Jino; Hooven, Louisa A; Harper, Bryan; Harper, Stacey L

2015-12-15

Encapsulation of pesticide active ingredients in polymers has been widely employed to control the release of poorly water-soluble active ingredients. Given the high dispersibility of these encapsulated pesticides in water, they are expected to behave differently compared to their active ingredients; however, our current understanding of the fate and effects of encapsulated pesticides is still limited. In this study, we employed a central composite design (CCD) to investigate how pH and ionic strength (IS) affect the hydrodynamic diameter (HDD) and zeta potential of encapsulated λ-cyhalothrin and how those changes affect the exposure and toxicity to Daphnia magna. R(2) values greater than 0.82 and 0.84 for HDD and zeta potential, respectively, irrespective of incubation time suggest those changes could be predicted as a function of pH and IS. For HDD, the linear factor of pH and quadratic factor of pH×pH were found to be the most significant factors affecting the change of HDD at the beginning of incubation, whereas the effects of IS and IS×IS became significant as incubation time increased. For zeta potential, the linear factor of IS and quadratic factor of IS×IS were found to be the most dominant factors affecting the change of zeta potential of encapsulated λ-cyhalothrin, irrespective of incubation time. The toxicity tests with D. magna under exposure conditions in which HDD or zeta potential of encapsulated λ-cyhalothrin was maximized or minimized in the overlying water also clearly showed the worst-case exposure condition to D. magna was when the encapsulated λ-cyhalothrin is either stable or small in the overlying water. Our results show that water quality could modify the fate and toxicity of encapsulated λ-cyhalothrin in aquatic environments, suggesting understanding their aquatic interactions are critical in environmental risk assessment. Herein, we discuss the implications of our findings for risk assessment. Copyright © 2015 Elsevier B.V. All

Molecular cloning of manganese superoxide dismutase gene in the cladoceran Daphnia magna: Effects of microcystin, nitrite, and cadmium on gene expression profiles

Energy Technology Data Exchange (ETDEWEB)

Lyu, Kai; Zhu, Xuexia; Chen, Rui [Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023 (China); Chen, Yafen [State Key Laboratory for Lake Science and Environment, Nanjing Institute of Geography and Limnology, the Chinese Academy of Sciences, Nanjing 210008 (China); Yang, Zhou, E-mail: yangzhou@njnu.edu.cn [Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023 (China)

2014-03-01

Graphical abstract: - Highlights: • Daphnia magna MnSOD (Dm-MnSOD) was identified and revealed MnSOD-family features. • The expression of Dm-MnSOD decreased with increased developmental stages. • Dm-MnSOD transcript was kinetically up-regulated by microcystin, nitrite and Cd. • Response of SOD to ubiquitous waterborne pollutants in D. magna was elucidated. • Dm-MnSOD gene is a potential biomarker indicating pollutants in the environment. - Abstract: Superoxide dismutases (SODs) are metalloenzymes that represent one important line of defense against oxidative stress produced by reactive oxygen species in aerobic organisms. Generally, waterborne pollutants caused by irregular anthropogenic activities often result in oxidative damage in aquatic organisms. The aim of this study was to molecularly characterize the manganese superoxide dismutase gene (Dm-MnSOD) in the waterflea, Daphnia magna, and evaluate the mRNA expression patterns quantified by real-time PCR after exposure to three common waterborne pollutants (microcystin-LR, nitrite, and cadmium). The results showed that the full-length Dm-MnSOD sequence consists of 954 bp nucleotides, encoding 215 amino acids, showing well-conserved domains that are required for metal binding and several common characteristics, such as two MnSOD domains. The deduced amino acid sequence of Dm-MnSOD shared over 70% similarity with homologues from Bythograea thermydron, Dromia personata, Cancer pagurus, and Scylla paramamosain. Dm-MnSOD gene expression was up-regulated in response to exposure to the three chemicals tested. The overall results indicated that Dm-MnSOD gene is an inducible gene and potential biomarker indicating these pollutants in the environment.

Development and characterization of multiplex panels of polymorphic microsatellite loci in giant liver fluke Fascioloides magna (Trematoda: Fasciolidae), using next-generation sequencing approach

Czech Academy of Sciences Publication Activity Database

Minárik, G.; Bazsalovicsová, E.; Zvijáková, Ĺ.; Štefka, Jan; Pálková, L.; Kraľová-Hromadová, I.

2014-01-01

Roč. 195, č. 1 (2014), s. 30-33 ISSN 0166-6851 Institutional support: RVO:60077344 Keywords : Short tandem repeats * Population genetics * Invasive parasite * Microsatellites * Fascioloides magna Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.787, year: 2014

Toxicidade aguda e risco ambiental do antibiótico oxitetraciclina para tilápia ( Oreochromis niloticus , Daphnia magna e Lemna minor

Directory of Open Access Journals (Sweden)

A.A. Machado

Full Text Available RESUMO O objetivo deste estudo foi classificar o antibiótico Terramicina(r de acordo com a toxicidade aguda e o risco de intoxicação ambiental para Oreochromis niloticus, Daphnia magna e Lemna minor, com base no seu ingrediente ativo oxitetraciclina (OTC. Além disso, observou-se a ocorrência de sinais de intoxicação aguda em peixes e o efeito da diluição do antibiótico sobre as variáveis de qualidade de água. Alevinos, neonatos e frondes foram expostos a concentrações de OTC. De acordo com os resultados dos testes de toxicidade aguda, a Terramicina(r foi classificada pela toxicidade aguda e pelo risco de intoxicação ambiental. Para O. niloticus, a CL(I50; 48h calculada foi de 6,92 mg L-1, para D. magna a CE(I50; 48h foi de 0,17mg.L-1, enquanto para L. minor a CI(I50;7d foi de 0,68 mg L-1. A Terramicina(r foi classificada como muito tóxica para O. niloticus e extremamente tóxica para D. magna e L. minor e causa risco de intoxicação ambiental para os três organismos testados. Concentrações de 7,5 e 8,0 mg L-1 de OTC reduziram a concentração de oxigênio dissolvido na água. De acordo com este estudo, a Terramicina(r não deve ser utilizada na aquicultura, pois é altamente tóxica e causa risco de intoxicação ambiental aos organismos teste.

Effects of the cyanobacterial neurotoxin B-N-methylamino-L-alamine (BMAA) on the survival, mobility and reproduction of Daphnia magna

NARCIS (Netherlands)

Lürling, M.F.L.L.W.; Faassen, E.J.; Eenennaam, van J.S.

2011-01-01

In short-term tests and chronic life table assays, Daphnia magna was exposed to the cyanobacterial neurotoxic non-protein amino acid ß-N-methylamino-l-alanine (BMAA). BMAA was not acutely lethal to Daphnia (LC50–48h > 10 000 µg L-1), but reduced mobility (IC50–48h 40 µg L-1) and affected life

Modification of metal bioaccumulation and toxicity in Daphnia magna by titanium dioxide nanoparticles

International Nuclear Information System (INIS)

Tan, Cheng; Wang, Wen-Xiong

2014-01-01

Titanium dioxide (TiO 2 ) nanoparticles are widely used in water treatments, yet their influences on other contaminants in the water are not well studied. In this study, the aqueous uptake, assimilation efficiency, and toxicity of two ionic metals (cadmium-Cd, and zinc-Zn) in a freshwater zooplankton, Daphnia magna, were investigated following 2 days pre-exposure to nano-TiO 2 . Pre-exposure to 1 mg/L nano-TiO 2 resulted in a significant increase in Cd and Zn uptake from the dissolved phase. After the nano-TiO 2 in the guts were cleared, the uptake rates immediately recovered to the normal levels. Concurrent measurements of reactive oxygen species (ROS) and metallothioneins (MTs) suggested that the increased metal uptake was mainly due to the increased number of binding sites provided by nano-TiO 2 presented in the guts. Consistently, pre-exposure to nano-TiO 2 increased the toxicity of aqueous Cd and Zn due to enhanced uptake. Our study provides the evidence that nano-TiO 2 in the guts of animals could increase the uptake and toxicity of other contaminants. -- Highlights: • Dissolved Cd and Zn uptake in daphnids increased significantly after nano-TiO 2 pre-exposure. • Aqueous toxicity of Cd and Zn also increased after nano-TiO 2 pre-exposure. • Dietary assimilation of Cd and Zn was not affected after nano-TiO 2 pre-exposure. • Metal uptake recovered to normal levels after nano-TiO 2 in the guts were removed. • Nano-TiO 2 in the guts of animals could increase the uptake and toxicity of other contaminants. -- Nano-TiO 2 accumulation in Daphnia magna facilitated the uptake and toxicity of metal contaminants

Gene transcription profiles, global DNA methylation and potential transgenerational epigenetic effects related to Zn exposure history in Daphnia magna

International Nuclear Information System (INIS)

Vandegehuchte, Michiel B.; De Coninck, Dieter; Vandenbrouck, Tine; De Coen, Wim M.; Janssen, Colin R.

2010-01-01

A reduced level of DNA methylation has recently been described in both Zn-exposed and non-exposed offspring of Daphnia magna exposed to Zn. The hypothesis examined in this study is that DNA hypomethylation has an effect on gene transcription. A second hypothesis is that accumulative epigenetic effects can affect gene transcription in non-exposed offspring from parents with an exposure history of more than one generation. Transcriptional gene regulation was studied with a cDNA microarray. In the exposed and non-exposed hypomethylated daphnids, a large proportion of common genes were similarly up- or down-regulated, indicating a possible effect of the DNA hypomethylation. Two of these genes can be mechanistically involved in DNA methylation reduction. The similar transcriptional regulation of two and three genes in the F 0 and F 1 exposed daphnids on one hand and their non-exposed offspring on the other hand, could be the result of a one-generation temporary transgenerational epigenetic effect, which was not accumulative. - Zn-induced DNA hypomethylation is related to gene transcription in Daphnia magna and Zn exposure potentially induced limited temporary transgenerational effects on gene transcription.

Daphnia magna and Xenopus laevis as in vivo models to probe toxicity and uptake of quantum dots functionalized with gH625

Directory of Open Access Journals (Sweden)

Galdiero E

2017-04-01

Full Text Available Emilia Galdiero,1 Annarita Falanga,2 Antonietta Siciliano,1 Valeria Maselli,1 Marco Guida,1 Rosa Carotenuto,1 Margherita Tussellino,1 Lucia Lombardi,3 Giovanna Benvenuto,4 Stefania Galdiero2 1Department of Biology, 2Department of Pharmacy and CiRPEB, University of Naples Federico II, 3Department of Experimental Medicine, Second University of Naples, 4Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli, Italy Abstract: The use of quantum dots (QDs for nanomedicine is hampered by their potential toxicologic effects and difficulties with delivery into the cell interior. We accomplished an in vivo study exploiting Daphnia magna and Xenopus laevis to evaluate both toxicity and uptake of QDs coated with the membranotropic peptide gH625 derived from the glycoprotein H of herpes simplex virus and widely used for drug delivery studies. We evaluated and compared the effects of QDs and gH625-QDs on the survival, uptake, induction of several responsive pathways and genotoxicity in D. magna, and we found that QDs coating plays a key role. Moreover, studies on X. laevis embryos allowed to better understand their cell/tissue localization and delivery efficacy. X. laevis embryos raised in Frog Embryo Teratogenesis Assay-Xenopus containing QDs or gH625-QDs showed that both nanoparticles localized in the gills, lung and intestine, but they showed different distributions, indicating that the uptake of gH625-QDs was enhanced; the functionalized QDs had a significantly lower toxic effect on embryos’ survival and phenotypes. We observed that D. magna and X. laevis are useful in vivo models for toxicity and drug delivery studies. Keywords: membranotropic peptide, delivery, blood–brain barrier, nanoparticles, genotoxicity

Metallothionein and Hsp70 trade-off against one another in Daphnia magna cross-tolerance to cadmium and heat stress

Energy Technology Data Exchange (ETDEWEB)

Haap, Timo, E-mail: timo.haap@gmx.de; Schwarz, Simon; Köhler, Heinz-R.

2016-01-15

Highlights: • Cadmium acclimation of two Daphnia magna clones which differed in Cd sensitivity and Hsp70 levels. • Two distinct metal-handling strategies regarding Hsp70 and MT expression were observed. • High Hsp70 levels did not confer an increase in Cd and heat stress tolerance. • Our results indicate a trade-off between Hsp70 and MT. - Abstract: The association between the insensitivity of adapted ecotypes of invertebrates to environmental stress, such as heavy metal pollution, and overall low Hsp levels characterizing these organisms has been attracting attention in various studies. The present study seeks to induce and examine this phenomenon in Daphnia magna by multigenerational acclimation to cadmium in a controlled laboratory setting. In this experiment, interclonal variation was examined: two clones of D. magna that have previously been characterized to diverge regarding their cadmium resistance and levels of the stress protein Hsp70, were continuously exposed to a sublethal concentration of Cd over four generations to study the effects of acclimation on Hsp70, metallothionein (MT), reproduction and cross-tolerance to heat stress. The two clones differed in all the measured parameters in a characteristic way, clone T displaying Cd and heat resistance, lower Hsp70 levels and offspring numbers on the one hand and higher MT expression on the other hand, clone S the opposite for all these parameters. We observed only slight acclimation-induced changes in constitutive Hsp70 levels and reproductive output. The differences in MT expression between clones as well as between acclimated organisms and controls give evidence for MT accounting for the higher Cd tolerance of clone T. Overall high Hsp70 levels of clone S did not confer cross tolerance to heat stress, contrary to common expectations. Our results suggest a trade-off between the efforts to limit the proteotoxic symptoms of Cd toxicity by Hsp70 induction and those to sequester and detoxify Cd by

Transgenerational effects and recovery of microplastics exposure in model populations of the freshwater cladoceran Daphnia magna Straus.

Science.gov (United States)

Martins, Alexandra; Guilhermino, Lúcia

2018-08-01

The environmental contamination by microplastics is a global challenge to ecosystem and human health, and the knowledge on the long-term effects of such particles is limited. Thus, the effects of microplastics and post-exposure recovery were investigated over 4 generations (F 0 , F 1 , F 2 , F 3 ) using Daphnia magna as model. Effect criteria were parental mortality, growth, several reproductive parameters, and population growth rate. Microplastics exposure (0.1mg/l of pristine polymer microspheres 1-5μm diameter) caused parental mortality (10-100%), and significantly (p≤0.05) decreased growth, reproduction, and population growth rate leading to the extinction of the microplastics-exposed model population in the F 1 generation. Females descending from those exposed to microplastics in F 0 and exposed to clean medium presented some recovery but up to the F 3 generation they still had significantly (p≤0.05) reduced growth, reproduction, and population growth rate. Overall, these results indicate that D. magna recovery from chronic exposure to microplastics may take several generations, and that the continuous exposure over generations to microplastics may cause population extinction. These findings have implications to aquatic ecosystem functioning and services, and raise concern on the long-term animal and human exposure to microplastics through diverse routes. Copyright © 2018. Published by Elsevier B.V.

Analyzing the capacity of the Daphnia magna and Pseudokirchneriella subcapitata bioavailability models to predict chronic zinc toxicity at high pH and low calcium concentrations and formulation of a generalized bioavailability model for D. magna.

Science.gov (United States)

Van Regenmortel, Tina; Berteloot, Olivier; Janssen, Colin R; De Schamphelaere, Karel A C

2017-10-01

Risk assessment in the European Union implements Zn bioavailability models to derive predicted-no-effect concentrations for Zn. These models are validated within certain boundaries (i.e., pH ≤ 8 and Ca concentrations ≥ 5mg/L), but a substantial fraction of the European surface waters falls outside these boundaries. Therefore, we evaluated whether the chronic Zn biotic ligand model (BLM) for Daphnia magna and the chronic bioavailability model for Pseudokirchneriella subcapitata could be extrapolated to pH > 8 and Ca concentrations model can accurately predict Zn toxicity for Ca concentrations down to 0.8 mg/L and pH values up to 8.5. Because the chronic Zn BLM for D. magna could not be extrapolated beyond its validity boundaries for pH, a generalized bioavailability model (gBAM) was developed. Of 4 gBAMs developed, we recommend the use of gBAM-D, which combines a log-linear relation between the 21-d median effective concentrations (expressed as free Zn 2+ ion activity) and pH, with more conventional BLM-type competition constants for Na, Ca, and Mg. This model is a first step in further improving the accuracy of chronic toxicity predictions of Zn as a function of water chemistry, which can decrease the uncertainty in implementing the bioavailability-based predicted-no-effect concentration in the risk assessment of high-pH and low-Ca concentration regions in Europe. Environ Toxicol Chem 2017;36:2781-2798. © 2017 SETAC. © 2017 SETAC.

Acute and chronic effects from pulse exposure of D. magna to silver and copper oxide nanoparticles

DEFF Research Database (Denmark)

Sørensen, Sara Nørgaard; Lützhøft, Hans-Christian Holten; Rasmussen, Rose

2016-01-01

Aquatic toxicity testing of nanoparticles (NPs) is challenged by their dynamic behavior in test suspensions. The resulting difficulties in controlling and characterizing exposure concentrations are detrimental to the generation of concentration-response data needed for hazard identification of NPs...... is an environmentally relevant exposure scenario for NPs, which for AgNPs and CuONPs enables more stable exposures and cause acute immobility of D. magna comparable to continuous 24 h exposures. Pulse exposure is likely relevant and applicable for other toxic and dissolving metal NPs, but this requires further research....

Widespread gene transfer in the central nervous system of cynomolgus macaques following delivery of AAV9 into the cisterna magna

Directory of Open Access Journals (Sweden)

Christian Hinderer

2014-01-01

Full Text Available Adeno-associated virus serotype 9 (AAV9 vectors have recently been shown to transduce cells throughout the central nervous system of nonhuman primates when injected into the cerebrospinal fluid (CSF, a finding which could lead to a minimally invasive approach to treat genetic and acquired diseases affecting the entire CNS. We characterized the transduction efficiency of two routes of vector administration into the CSF of cynomolgus macaques—lumbar puncture, which is typically used in clinical practice, and suboccipital puncture, which is more commonly used in veterinary medicine. We found that delivery of vector into the cisterna magna via suboccipital puncture is up to 100-fold more efficient for achieving gene transfer to the brain. In addition, we evaluated the inflammatory response to AAV9-mediated GFP expression in the nonhuman primate CNS. We found that while CSF lymphocyte counts increased following gene transfer, there were no clinical or histological signs of immune toxicity. Together these data indicate that delivery of AAV9 into the cisterna magna is an effective method for achieving gene transfer in the CNS, and suggest that adapting this uncommon injection method for human trials could vastly increase the efficiency of gene delivery.

Effects of an anionic surfactant (FFD-6) on the energy and information flow between a primary producer (Scenedesmus obliquus) and a consumer (Daphnia magna)

NARCIS (Netherlands)

Lürling, M.; de Lange, H.J.; Peeters, E.T.H.M.

2011-01-01

The effects of a commercially available anionic surfactant solution (FFD-6) on growth and morphology of a common green alga (Scenedesmus obliquus) and on survival and clearance rates of the water flea Daphnia magna were studied. The surfactant-solution elicited a morphological response (formation of

Toxicity of binary mixtures of metals and pyrethroid insecticides to Daphnia magna Straus. Implications for multi-substance risks assessment

Energy Technology Data Exchange (ETDEWEB)

Barata, Carlos [Laboratory of Environmental Toxicology, Universitat Poltiecnica de Catalunya, CN 150 Km 14.5, Terrassa 08220 (Spain)]. E-mail: barata@intexter.upc.edu; Baird, D.J. [National Water Research Institute (Environment Canada) at Canadian Rivers Institute, 10 Bailey Drive, PO Box 45111, University of New Brunswick, Fredericton E3B 6E1, New Brunswick (Canada); Nogueira, A.J.A. [Departamento de Biologia, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Soares, A.M.V.M. [Departamento de Biologia, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Riva, M.C. [Laboratory of Environmental Toxicology, Universitat Poltiecnica de Catalunya, CN 150 Km 14.5, Terrassa 08220 (Spain)

2006-06-10

Two different concepts, termed concentration addition (CA) and independent action (IA), describe general relationships between the effects of single substances and their corresponding mixtures allowing calculation of an expected mixture toxicity on the basis of known toxicities of the mixture components. Both concepts are limited to cases in which all substances in a mixture influence the same experimental endpoint, and are usually tested against a 'fixed ratio design' where the mixture ratio is kept constant throughout the studies and the overall concentration of the mixture is systematically varied. With this design, interaction among toxic components across different mixture ratios and endpoints (i.e. lethal versus sublethal) is not assessed. In this study lethal and sublethal (feeding) responses of Daphnia magna individuals to single and binary combinations of similarly and dissimilarly acting chemicals including the metals (cadmium, copper) and the pyrethroid insecticides ({lambda}-cyhalothrin and deltamethrin) were assayed using a composite experimental design to test for interactions among toxic components across mixture effect levels, mixture ratios, lethal and sublethal toxic effects. To account for inter-experiment response variability, in each binary mixture toxicity assay the toxicity of the individual mixture constituents was also assessed. Model adequacy was then evaluated comparing the slopes and elevations of predicted versus observed mixture toxicity curves with those estimated for the individual components. Model predictive abilities changed across endpoints. The IA concept was able to predict accurately mixture toxicities of dissimilarly acting chemicals for lethal responses, whereas the CA concept did so in three out of four pairings for feeding response, irrespective of the chemical mode of action. Interaction effects across mixture effect levels, evidenced by crossing slopes, were only observed for the binary mixture Cd and Cu for

Toxicity of binary mixtures of metals and pyrethroid insecticides to Daphnia magna Straus. Implications for multi-substance risks assessment

International Nuclear Information System (INIS)

Barata, Carlos; Baird, D.J.; Nogueira, A.J.A.; Soares, A.M.V.M.; Riva, M.C.

2006-01-01

Two different concepts, termed concentration addition (CA) and independent action (IA), describe general relationships between the effects of single substances and their corresponding mixtures allowing calculation of an expected mixture toxicity on the basis of known toxicities of the mixture components. Both concepts are limited to cases in which all substances in a mixture influence the same experimental endpoint, and are usually tested against a 'fixed ratio design' where the mixture ratio is kept constant throughout the studies and the overall concentration of the mixture is systematically varied. With this design, interaction among toxic components across different mixture ratios and endpoints (i.e. lethal versus sublethal) is not assessed. In this study lethal and sublethal (feeding) responses of Daphnia magna individuals to single and binary combinations of similarly and dissimilarly acting chemicals including the metals (cadmium, copper) and the pyrethroid insecticides (λ-cyhalothrin and deltamethrin) were assayed using a composite experimental design to test for interactions among toxic components across mixture effect levels, mixture ratios, lethal and sublethal toxic effects. To account for inter-experiment response variability, in each binary mixture toxicity assay the toxicity of the individual mixture constituents was also assessed. Model adequacy was then evaluated comparing the slopes and elevations of predicted versus observed mixture toxicity curves with those estimated for the individual components. Model predictive abilities changed across endpoints. The IA concept was able to predict accurately mixture toxicities of dissimilarly acting chemicals for lethal responses, whereas the CA concept did so in three out of four pairings for feeding response, irrespective of the chemical mode of action. Interaction effects across mixture effect levels, evidenced by crossing slopes, were only observed for the binary mixture Cd and Cu for lethal effects

Tax and the Forgotten Classes: from the Magna Carta to the English Revolution

Directory of Open Access Journals (Sweden)

John Passant

2016-09-01

Full Text Available This paper looks at three key early events in English tax history, the 1215 Magna Carta, the Peasants' Revolt of 1381 and the English Revolution from 1640 to 1649. It uses these events to explore the relationship between tax, ward, democracy and rebellion. Tax is both an expression of and a cause of class divisions that is can, and does as these events show, spark revolts against the state imposing the taxes. These revolts can be between members of the ruling elite, or between the people outside the ruling elite and that group of rulers both political and economic, or a mixture of both. The aim is to reintroduce class into tax history and show over time the crucial role ordinary people (for example peasants, artisans and workers play in the history of taxation. Thus the people of London played a role in the successful rebellion of the Barons against the kings' imposition of excessive tax and the establishment of a common counsel of the elite to approve future extractions. This gain became the bedrock for future democratic demands, for example no taxation without representation. Peasants drove the revolt of 1381 against poll taxes but could not make demands that transcended their particular class position although they gave hints of an alternative non-class divided society. In 1629 Ship Money enabled the King to rule without parliamentary and this eventually sparked the rebellion and then revolution from 1640 in the context of a society changing from feudal to capitalist relations. In all three cases the actions of the masses of ordinary people are a key to understanding the events and the intertwining of war, tax, democracy and rebellion that becomes evident during this investigation.

The effect of pH on the uptake and toxicity of the bivalent weak base chloroquine tested on Salix viminalis and Daphnia magna

DEFF Research Database (Denmark)

Rendal, Cecilie; Kusk, Kresten Ole; Trapp, Stefan

2011-01-01

, and therefore a higher toxicity can be expected. The current study examines the pHdependent toxicity and bioaccumulation of the bivalent weak base chloroquine (pKa: 10.47 and 6.33, log KOW 4.67) tested on Salix viminalis (basket willow) and Daphnia magna (water flea). The transpiration rates of hydroponically...

Serotonin, dopamine and noradrenaline adjust actions of myelinated afferents via modulation of presynaptic inhibition in the mouse spinal cord.

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David L García-Ramírez

Full Text Available Gain control of primary afferent neurotransmission at their intraspinal terminals occurs by several mechanisms including primary afferent depolarization (PAD. PAD produces presynaptic inhibition via a reduction in transmitter release. While it is known that descending monoaminergic pathways complexly regulate sensory processing, the extent these actions include modulation of afferent-evoked PAD remains uncertain. We investigated the effects of serotonin (5HT, dopamine (DA and noradrenaline (NA on afferent transmission and PAD. Responses were evoked by stimulation of myelinated hindlimb cutaneous and muscle afferents in the isolated neonatal mouse spinal cord. Monosynaptic responses were examined in the deep dorsal horn either as population excitatory synaptic responses (recorded as extracellular field potentials; EFPs or intracellular excitatory postsynaptic currents (EPSCs. The magnitude of PAD generated intraspinally was estimated from electrotonically back-propagating dorsal root potentials (DRPs recorded on lumbar dorsal roots. 5HT depressed the DRP by 76%. Monosynaptic actions were similarly depressed by 5HT (EFPs 54%; EPSCs 75% but with a slower time course. This suggests that depression of monosynaptic EFPs and DRPs occurs by independent mechanisms. DA and NA had similar depressant actions on DRPs but weaker effects on EFPs. IC50 values for DRP depression were 0.6, 0.8 and 1.0 µM for 5HT, DA and NA, respectively. Depression of DRPs by monoamines was nearly-identical in both muscle and cutaneous afferent-evoked responses, supporting a global modulation of the multimodal afferents stimulated. 5HT, DA and NA produced no change in the compound antidromic potentials evoked by intraspinal microstimulation indicating that depression of the DRP is unrelated to direct changes in the excitability of intraspinal afferent fibers, but due to metabotropic receptor activation. In summary, both myelinated afferent-evoked DRPs and monosynaptic

Transcriptional and cellular effects of benzotriazole UV stabilizers UV-234 and UV-328 in the freshwater invertebrates Chlamydomonas reinhardtii and Daphnia magna.

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Giraudo, Maeva; Cottin, Guillaume; Esperanza, Marta; Gagnon, Pierre; Silva, Amila O De; Houde, Magali

2017-12-01

Benzotriazole ultra violet stabilizers (BZT-UVs) are compounds used in many applications and products to prevent photochemical degradation. Despite their widespread presence in aquatic ecosystems and persistence in the environment, there are very limited data on their effects and toxicity, and their modes of action remain largely unknown. The objectives of the present study were to evaluate the chronic effects of 2 BZT-UVs, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (UV-234) and 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV-328), on the freshwater green algae Chlamydomonas reinhardtii and the freshwater crustacean Daphnia magna. Organisms were exposed to 0.01 and 10 μg/L of UV-234, UV-328, as well as a mixture of the 2 compounds. Life-history endpoints (viability, reproduction, and growth) and oxidative stress-related biomarkers (gene transcription, reactive oxygen species [ROS] production, and lipid peroxidation) were measured. Daphnia magna growth, reproduction, and gene transcription were not impacted by 21-d individual or mixed exposure. After 96-h of exposure, no differences were observed on the cellular viability of C. reinhardtii for either of the 2 BZT-UVs. In the algae, results showed increased ROS production in response to UV-328 and lipid peroxidation following exposure to UV-234. Synergistic effects of the 2 BZT-UVs were evident at the transcriptional level with 2 to 6 times up-regulation of glutathione peroxidase (gp x ) in response to the mixture for all treatment conditions. The transcription of superoxide dismutase (sod), catalase (cat), and ascorbic peroxidase (apx) was also regulated by UV-234 and UV-328 in the green algae, most likely as a result of ROS production and lipid peroxidation. Results from the present study suggest potential impacts of UV-234 and UV-328 exposure on the antioxidant defense system in C. reinhardtii. Environ Toxicol Chem 2017;36:3333-3342. © 2017 Crown in the Right of Canada. Published by

Magna Carta And Its Significant Role For Rule Of Law In The Republic Of Macedonia

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Shumanovska-Spasovska Ivana

2015-12-01

Full Text Available One of the most important and famous historical documents from the English legal and constitutional legacy is the Magna Carta Libertatum. Signed and sealed in the year 1215 the Magna Carta is further on viewed as the sole inception of the idea of limiting the power of the ruler trough legal rules. That limitation is to be made with legal rules that are binding for everyone, even the monarch. Therefore, the Great Charter is viewed as the first document signed by a monarch with which, the principle of supremacy of the law is set out. That supremacy of the law has been further on developed by eminent scholars and practitioners, eventually leading to the development of the concept of rule of law. Rule of law, as a concept, means that the royal authority (or the executive branch of power is going to be inferior to the law. However, this concept means a lot more than simply that. Unlike the principle of legal state, the rule of law is closely linked to justice, separation of powers and legal certainty. All of these concepts are actually prerequisites for its existence. That is why each of them is separately examined and elaborated. Furthermore, as one of the most important principles the rule of law had a great influence on the constitutional (and legal systems around the world. Since the Republic of Macedonia strives to become a democratic state where the rule of law is established and developed it is important to elaborate the influence of this principle in it. Therefore, the research gravitates over the principle of rule of law in the Republic of Macedonia.

Binding Action and Emotion in Social Understanding

Science.gov (United States)

Ferri, Francesca; Ebisch, Sjoerd J. H.; Costantini, Marcello; Salone, Anatolia; Arciero, Giampiero; Mazzola, Viridiana; Ferro, Filippo Maria; Romani, Gian Luca; Gallese, Vittorio

2013-01-01

In social life actions are tightly linked with emotions. The integration of affective- and action-related information has to be considered as a fundamental component of appropriate social understanding. The present functional magnetic resonance imaging study aimed at investigating whether an emotion (Happiness, Anger or Neutral) dynamically expressed by an observed agent modulates brain activity underlying the perception of his grasping action. As control stimuli, participants observed the same agent either only expressing an emotion or only performing a grasping action. Our results showed that the observation of an action embedded in an emotional context (agent’s facial expression), compared with the observation of the same action embedded in a neutral context, elicits higher neural response at the level of motor frontal cortices, temporal and occipital cortices, bilaterally. Particularly, the dynamic facial expression of anger modulates the re-enactment of a motor representation of the observed action. This is supported by the evidence that observing actions embedded in the context of anger, but not happiness, compared with a neutral context, elicits stronger activity in the bilateral pre-central gyrus and inferior frontal gyrus, besides the pre-supplementary motor area, a region playing a central role in motor control. Angry faces not only seem to modulate the simulation of actions, but may also trigger motor reaction. These findings suggest that emotions exert a modulatory role on action observation in different cortical areas involved in action processing. PMID:23349792

Post-error action control is neurobehaviorally modulated under conditions of constant speeded response.

Science.gov (United States)

Soshi, Takahiro; Ando, Kumiko; Noda, Takamasa; Nakazawa, Kanako; Tsumura, Hideki; Okada, Takayuki

2014-01-01

Post-error slowing (PES) is an error recovery strategy that contributes to action control, and occurs after errors in order to prevent future behavioral flaws. Error recovery often malfunctions in clinical populations, but the relationship between behavioral traits and recovery from error is unclear in healthy populations. The present study investigated the relationship between impulsivity and error recovery by simulating a speeded response situation using a Go/No-go paradigm that forced the participants to constantly make accelerated responses prior to stimuli disappearance (stimulus duration: 250 ms). Neural correlates of post-error processing were examined using event-related potentials (ERPs). Impulsivity traits were measured with self-report questionnaires (BIS-11, BIS/BAS). Behavioral results demonstrated that the commission error for No-go trials was 15%, but PES did not take place immediately. Delayed PES was negatively correlated with error rates and impulsivity traits, showing that response slowing was associated with reduced error rates and changed with impulsivity. Response-locked error ERPs were clearly observed for the error trials. Contrary to previous studies, error ERPs were not significantly related to PES. Stimulus-locked N2 was negatively correlated with PES and positively correlated with impulsivity traits at the second post-error Go trial: larger N2 activity was associated with greater PES and less impulsivity. In summary, under constant speeded conditions, error monitoring was dissociated from post-error action control, and PES did not occur quickly. Furthermore, PES and its neural correlate (N2) were modulated by impulsivity traits. These findings suggest that there may be clinical and practical efficacy of maintaining cognitive control of actions during error recovery under common daily environments that frequently evoke impulsive behaviors.

Claudia Quinta (Pro Caelio 34 and an altar to Magna Mater

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Eleanor Winsor Leach

2010-11-01

Full Text Available Among the items of sculpture from the Capitoline collection now housed in the Museum of the Power Station Montemartini is a marble relief altar of the Claudian Period (E. Simon's dating dedicated to the mater deorum and the navis salvia and depicting the arrival of the goddess Cybele at Rome by ship. The dedicator is one Claudia Syntyche and the sculpture alludes to the legends attached to a much honored woman of the Claudian family whom Cicero, in his oration pro Caelio brought on stage in a cameo appearance to bolster his case against the controversial contemporary woman Clodia Metelli as one of the accusers of his client M. Caelius Rufus. This paper will consider questions raised by the iconography of the altar with reference to the development of Claudia's legend in Roman mythology and subsequently ask who was this Claudia the dedicator and why did she choose Magna Mater for her vow?

Validation of a Mathematical Model for Green Algae (Raphidocelis Subcapitata Growth and Implications for a Coupled Dynamical System with Daphnia Magna

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Michael Stemkovski

2016-05-01

Full Text Available Toxicity testing in populations probes for responses in demographic variables to anthropogenic or natural chemical changes in the environment. Importantly, these tests are primarily performed on species in isolation of adjacent tropic levels in their ecosystem. The development and validation of coupled species models may aid in predicting adverse outcomes at the ecosystems level. Here, we aim to validate a model for the population dynamics of the green algae Raphidocelis subcapitata, a planktonic species that is often used as a primary food source in toxicity experiments for the fresh water crustacean Daphnia magna. We collected longitudinal data from three replicate population experiments of R. subcapitata. We used this data with statistical model comparison tests and uncertainty quantification techniques to compare the performance of four models: the Logistic model, the Bernoulli model, the Gompertz model, and a discretization of the Logistic model. Overall, our results suggest that the logistic model is the most accurate continuous model for R. subcapitata population growth. We then implement the numerical discretization showing how the continuous logistic model for algae can be coupled to a previously validated discrete-time population model for D. magna.

Viewing instructions accompanying action observation modulate corticospinal excitability

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David James Wright

2016-02-01

Full Text Available Action observation interventions may have the potential to contribute to improved motor function in motor (relearning settings by promoting functional activity and plasticity in the motor regions of the brain. Optimal methods for delivering such interventions, however, have yet to be established. This experiment investigated the effect on corticospinal excitability of manipulating the viewing instructions provided to participants (N = 21 prior to action observation. Specifically, motor evoked potential responses measured from the right hand muscles following single-pulse transcranial magnetic stimulation to the left motor cortex were compared when participants were instructed to observe finger-thumb opposition movement sequences: (i passively; (ii with the intent to imitate the observed movement; or (iii whilst simultaneously and actively imagining that they were performing the movement as they observed it. All three action observation viewing instructions facilitated corticospinal excitability to a greater extent than did observation of a static hand. In addition, the extent to which corticospinal excitability was facilitated was greater during combined observation and imagery, compared to passive observation. These findings have important implications for the design of action observation interventions in motor (relearning settings, where instructions that encourage observers to simultaneously imagine themselves performing the observed movement may offer the current optimal method for improving motor function through action observation.

Host age modulates parasite infectivity, virulence and reproduction.

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Izhar, Rony; Ben-Ami, Frida

2015-07-01

Host age is one of the most striking differences among hosts within most populations, but there is very little data on how age-dependent effects impact ecological and evolutionary dynamics of both the host and the parasite. Here, we examined the influence of host age (juveniles, young and old adults) at parasite exposure on host susceptibility, fecundity and survival as well as parasite transmission, using two clones of the water flea Daphnia magna and two clones of its bacterial parasite Pasteuria ramosa. Younger D. magna were more susceptible to infection than older ones, regardless of host or parasite clone. Also, younger-infected D. magna became castrated faster than older hosts, but host and parasite clone effects contributed to this trait as well. Furthermore, the early-infected D. magna produced considerably more parasite transmission stages than late-infected ones, while host age at exposure did not affect virulence as it is defined in models (host mortality). When virulence is defined more broadly as the negative effects of infection on host fitness, by integrating the parasitic effects on host fecundity and mortality, then host age at exposure seems to slide along a negative relationship between host and parasite fitness. Thus, the virulence-transmission trade-off differs strongly among age classes, which in turn affects predictions of optimal virulence. Age-dependent effects on host susceptibility, virulence and parasite transmission could pose an important challenge for experimental and theoretical studies of infectious disease dynamics and disease ecology. Our results present a call for a more explicit stage-structured theory for disease, which will incorporate age-dependent epidemiological parameters. © 2015 The Authors. Journal of Animal Ecology © 2015 British Ecological Society.

Acute toxicity tests with Daphnia magna, Americamysis bahia, Chironomus riparius and Gammarus pulex and implications of new EU requirenments for the aquatic effect assessment of insecticides

NARCIS (Netherlands)

Brock, T.C.M.; Wijngaarden, van R.P.A.

2012-01-01

Threshold concentrations for treatment related effects of 31 insecticides, as derived from aquatic micro-/mesocosm tests, were used to calibrate the predictive value of the European Tier-1 acute effect assessment on basis of laboratory toxicity tests with Daphnia magna, Chironomus spp., Americamysis

Urocortin2 prolongs action potential duration and modulates potassium currents in guinea pig myocytes and HEK293 cells.

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Yang, Li-Zhen; Zhu, Yi-Chun

2015-07-05

We previously reported that activation of corticotropin releasing factor receptor type 2 by urocortin2 up-regulates both L-type Ca(2+) channels and intracellular Ca(2+) concentration in ventricular myocytes and plays an important role in cardiac contractility and arrhythmogenesis. This study goal was to further test the hypothesis that urocortin2 may modulate action potentials as well as rapidly and slowly activating delayed rectifier potassium currents. With whole cell patch-clamp techniques, action potentials and slowly activating delayed rectifier potassium currents were recorded in isolated guinea pig ventricular myocytes, respectively. And rapidly activating delayed rectifier potassium currents were tested in hERG-HEK293 cells. Urocortin2 produced a time- and concentration-dependent prolongation of action potential duration. The EC50 values of action potential duration and action potential duration at 90% of repolarization were 14.73 and 24.3nM respectively. The prolongation of action potential duration of urocortin2 was almost completely or partly abolished by H-89 (protein kinase A inhibitor) or KB-R7943 (Na(+)/Ca(2+) exchange inhibitor) pretreatment respectively. And urocortin2 caused reduction of rapidly activating delayed rectifier potassium currents in hERG-HEK293 cells. In addition, urocortin2 slowed the rate of slowly activating delayed rectifier potassium channel activation, and rightward shifted the threshold of slowly activating delayed rectifier potassium currents to more positive potentials. Urocortin2 prolonged action potential duration via activation of protein kinase A and Na(+)/ Ca(2+) exchange in isolated guinea pig ventricular myocytes in a time- and concentration- dependent manner. In hERG-HEK293 cells, urocortin2 reduced rapidly activating delayed rectifier potassium current density which may contribute to action potential duration prolongation. Copyright © 2015 Elsevier B.V. All rights reserved.

Integrated analysis of the ecotoxicological and genotoxic effects of the antimicrobial peptide melittin on Daphnia magna and Pseudokirchneriella subcapitata

International Nuclear Information System (INIS)

Galdiero, Emilia; Maselli, Valeria; Falanga, Annarita; Gesuele, Renato; Galdiero, Stefania; Fulgione, Domenico; Guida, Marco

2015-01-01

Melittin is a major constituent of the bee venom of Apis mellifera with a broad spectrum of activities. Melittin therapeutical potential is subject to its toxicity and the assessment of ecotoxicity and genotoxicity is of particular interest for therapeutic use. Here we analyzed the biological effects of melittin on two aquatic species, which are representative of two different levels of the aquatic trophic chain: the invertebrate Daphnia magna and the unicellular microalgae Pseudokirchneriella subcapitata. The attention was focused on the determination of: i) ecotoxicity; ii) genotoxicity; iii) antigenotoxicity. Our main finding is that melittin is detrimental to D. magna reproduction and its sub-lethal concentrations create an accumulation dependent on exposition times and a negative effect on DNA. We also observed that melittin significantly delayed time to first eggs. Moreover, results showed that melittin exerted its toxic and genotoxic effects in both species, being a bit more aggressive towards P. subcapitata. - Highlights: • We examine ecotoxicity to study how AMPs affect the environment. • We examine genotoxicity in order to analyze the damages to the DNA. • We examine the antigenotoxicity in order to verify DNA repair ability of the cells. • Possible therapeutical applications of AMPs depend on assessment of ecotoxicity. - Melittin exerts its dose dependent toxic and genotoxic effects on both indicators; no toxicity is found at concentrations that may typically reach the environment

Post-error action control is neurobehaviorally modulated under conditions of constant speeded response

Directory of Open Access Journals (Sweden)

Takahiro eSoshi

2015-01-01

Full Text Available Post-error slowing is an error recovery strategy that contributes to action control, and occurs after errors in order to prevent future behavioral flaws. Error recovery often malfunctions in clinical populations, but the relationship between behavioral traits and recovery from error is unclear in healthy populations. The present study investigated the relationship between impulsivity and error recovery by simulating a speeded response situation using a Go/No-go paradigm that forced the participants to constantly make accelerated responses prior to stimuli disappearance (stimulus duration: 250 ms. Neural correlates of post-error processing were examined using event-related potentials (ERPs. Impulsivity traits were measured with self-report questionnaires (BIS-11, BIS/BAS. Behavioral results demonstrated that the commission error for No-go trials was 15%, but post-error slowing did not take place immediately. Delayed post-error slowing was negatively correlated with error rates and impulsivity traits, showing that response slowing was associated with reduced error rates and changed with impulsivity. Response-locked error ERPs were clearly observed for the error trials. Contrary to previous studies, error ERPs were not significantly related to post-error slowing. Stimulus-locked N2 was negatively correlated with post-error slowing and positively correlated with impulsivity traits at the second post-error Go trial: larger N2 activity was associated with greater post-error slowing and less impulsivity. In summary, under constant speeded conditions, error monitoring was dissociated from post-error action control, and post-error slowing did not occur quickly. Furthermore, post-error slowing and its neural correlate (N2 were modulated by impulsivity traits. These findings suggest that there may be clinical and practical efficacy of maintaining cognitive control of actions during error recovery under common daily environments that frequently evoke

Combined acute ecotoxicity of malathion and deltamethrin to Daphnia magna (Crustacea, Cladocera): comparison of different data analysis approaches.

Science.gov (United States)

Toumi, Héla; Boumaiza, Moncef; Millet, Maurice; Radetski, Claudemir Marcos; Camara, Baba Issa; Felten, Vincent; Masfaraud, Jean-François; Férard, Jean-François

2018-04-19

We studied the combined acute effect (i.e., after 48 h) of deltamethrin (a pyrethroid insecticide) and malathion (an organophosphate insecticide) on Daphnia magna. Two approaches were used to examine the potential interaction effects of eight mixtures of deltamethrin and malathion: (i) calculation of mixture toxicity index (MTI) and safety factor index (SFI) and (ii) response surface methodology coupled with isobole-based statistical model (using generalized linear model). According to the calculation of MTI and SFI, one tested mixture was found additive while the two other tested mixtures were found no additive (MTI) or antagonistic (SFI), but these differences between index responses are only due to differences in terminology related to these two indexes. Through the surface response approach and isobologram analysis, we concluded that there was a significant antagonistic effect of the binary mixtures of deltamethrin and malathion that occurs on D. magna immobilization, after 48 h of exposure. Index approaches and surface response approach with isobologram analysis are complementary. Calculation of mixture toxicity index and safety factor index allows identifying punctually the type of interaction for several tested mixtures, while the surface response approach with isobologram analysis integrates all the data providing a global outcome about the type of interactive effect. Only the surface response approach and isobologram analysis allowed the statistical assessment of the ecotoxicological interaction. Nevertheless, we recommend the use of both approaches (i) to identify the combined effects of contaminants and (ii) to improve risk assessment and environmental management.

Interclonal proteomic responses to predator exposure in Daphnia magna may depend on predator composition of habitats.

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Otte, Kathrin A; Schrank, Isabella; Fröhlich, Thomas; Arnold, Georg J; Laforsch, Christian

2015-08-01

Phenotypic plasticity, the ability of one genotype to express different phenotypes in response to changing environmental conditions, is one of the most common phenomena characterizing the living world and is not only relevant for the ecology but also for the evolution of species. Daphnia, the water flea, is a textbook example for predator-induced phenotypic plastic defences; however, the analysis of molecular mechanisms underlying these inducible defences is still in its early stages. We exposed Daphnia magna to chemical cues of the predator Triops cancriformis to identify key processes underlying plastic defensive trait formation. To get a more comprehensive idea of this phenomenon, we studied four genotypes with five biological replicates each, originating from habitats characterized by different predator composition, ranging from predator-free habitats to habitats containing T. cancriformis. We analysed the morphologies as well as proteomes of predator-exposed and control animals. Three genotypes showed morphological changes when the predator was present. Using a high-throughput proteomics approach, we found 294 proteins which were significantly altered in their abundance after predator exposure in a general or genotype-dependent manner. Proteins connected to genotype-dependent responses were related to the cuticle, protein synthesis and calcium binding, whereas the yolk protein vitellogenin increased in abundance in all genotypes, indicating their involvement in a more general response. Furthermore, genotype-dependent responses at the proteome level were most distinct for the only genotype that shares its habitat with Triops. Altogether, our study provides new insights concerning genotype-dependent and general molecular processes involved in predator-induced phenotypic plasticity in D. magna. © 2015 John Wiley & Sons Ltd.

Toxicity of a binary mixture on Daphnia magna: biological effects of uranium and selenium isolated and in mixture

International Nuclear Information System (INIS)

Zeman, F.

2008-10-01

Among the multiple substances that affect freshwater ecosystems, uranium and selenium are two pollutants found worldwide in the environment, alone and in mixture. The aim of this thesis work was to investigate the effect of uranium and selenium mixture on daphnia (Daphnia magna). Studying effects of a mixture requires the assessment of the effect of single substances. Thus, the first experiments were performed on single substance. Acute toxicity data were obtained: EC 50 48h = 0, 39±0, 04 mg.L -1 for uranium and EC 50 48h 1, 86±0, 85 mg.L -1 for selenium. Chronic effects were also studied. Data on fecundity showed an EC 10 reproduction of 14±7 μg. L -1 for uranium and of 215±25 μg. L -1 for selenium. Uranium-selenium mixture toxicity experiments were performed and revealed an antagonistic effect. This study further demonstrates the importance of taking into consideration different elements in binary mixture studies such as the choice of reference models (concentration addition or independent action), statistical method, time exposure and endpoints. Using integrated parameters like energy budget was shown to be an interesting way to better understand interactions. An approach including calculation of chemical speciation in the medium and bioaccumulation measurements in the organism permits assumptions to be made on the nature of possible interactions between mixture components (toxico-dynamic et toxico-kinetic interactions). (author)

Analysis of the swimming velocity of cadmium-stressed Daphnia magna

International Nuclear Information System (INIS)

Baillieul, M.; Blust, R.

1999-01-01

The swimming velocity of the waterflea Daphnia magna is dependent on its body size. Therefore, environmental factors like toxic stress that influence growth also influence swimming velocity. An experiment was set up to test whether exposure to cadmium would reduce only growth, with a concomitant decrease in velocity, or whether it would reduce velocity below the swimming velocity of similarly-sized control animals. Daphnids were exposed for 10 days to free cadmium ion concentrations ranging from 1x10 -8 to 1x10 -7 M Cd 2+ , and body size and swimming velocity were measured every 2 days. The results showed that cadmium decreased both growth and velocity, i.e. exposed daphnids swam slower than similarly-sized control daphnids. Swimming velocity provided no indication of successful acclimation in any cadmium treatment. Food consumption and assimilation were reduced by exposure to cadmium. This reduced food intake may have, at least partially, caused the decreased growth rates. However, since reduced food intake does not affect swimming velocity, the reduced swimming velocity must be attributed to toxic effects of cadmium, other than those on food intake. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

Regulating prefrontal cortex activation: an emerging role for the 5-HT₂A serotonin receptor in the modulation of emotion-based actions?

Science.gov (United States)

Aznar, Susana; Klein, Anders B

2013-12-01

The prefrontal cortex (PFC) is involved in mediating important higher-order cognitive processes such as decision making, prompting thereby our actions. At the same time, PFC activation is strongly influenced by emotional reactions through its functional interaction with the amygdala and the striatal circuitry, areas involved in emotion and reward processing. The PFC, however, is able to modulate amygdala reactivity via a feedback loop to this area. A role for serotonin in adjusting for this circuitry of cognitive regulation of emotion has long been suggested based primarily on the positive pharmacological effect of elevating serotonin levels in anxiety regulation. Recent animal and human functional magnetic resonance studies have pointed to a specific involvement of the 5-hydroxytryptamine (5-HT)2A serotonin receptor in the PFC feedback regulatory projection onto the amygdala. This receptor is highly expressed in the prefrontal cortex areas, playing an important role in modulating cortical activity and neural oscillations (brain waves). This makes it an interesting potential pharmacological target for the treatment of neuropsychiatric modes characterized by lack of inhibitory control of emotion-based actions, such as addiction and other impulse-related behaviors. In this review, we give an overview of the 5-HT2A receptor distribution (neuronal, intracellular, and anatomical) along with its functional and physiological effect on PFC activation, and how that relates to more recent findings of a regulatory effect of the PFC on the emotional control of our actions.

Weight dependent modulation of motor resonance induced by weight estimation during observation of partially occluded lifting actions.

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Valchev, Nikola; Zijdewind, Inge; Keysers, Christian; Gazzola, Valeria; Avenanti, Alessio; Maurits, Natasha M

2015-01-01

Seeing others performing an action induces the observers' motor cortex to "resonate" with the observed action. Transcranial magnetic stimulation (TMS) studies suggest that such motor resonance reflects the encoding of various motor features of the observed action, including the apparent motor effort. However, it is unclear whether such encoding requires direct observation or whether force requirements can be inferred when the moving body part is partially occluded. To address this issue, we presented participants with videos of a right hand lifting a box of three different weights and asked them to estimate its weight. During each trial we delivered one transcranial magnetic stimulation (TMS) pulse over the left primary motor cortex of the observer and recorded the motor evoked potentials (MEPs) from three muscles of the right hand (first dorsal interosseous, FDI, abductor digiti minimi, ADM, and brachioradialis, BR). Importantly, because the hand shown in the videos was hidden behind a screen, only the contractions in the actor's BR muscle under the bare skin were observable during the entire videos, while the contractions in the actor's FDI and ADM muscles were hidden during the grasp and actual lift. The amplitudes of the MEPs recorded from the BR (observable) and FDI (hidden) muscle increased with the weight of the box. These findings indicate that the modulation of motor excitability induced by action observation extends to the cortical representation of muscles with contractions that could not be observed. Thus, motor resonance appears to reflect force requirements of observed lifting actions even when the moving body part is occluded from view. Copyright © 2014 Elsevier Ltd. All rights reserved.

High concentrations of protein test substances may have non-toxic effects on Daphnia magna: implications for regulatory study designs and ecological risk assessments for GM crops.

Science.gov (United States)

Raybould, Alan; Burns, Andrea; Hamer, Mick

2014-01-01

Laboratory testing for possible adverse effects of insecticidal proteins on non-target organisms (NTOs) is an important part of many ecological risk assessments for regulatory decision-making about the cultivation of insect-resistant genetically modified (IRGM) crops. To increase confidence in the risk assessments, regulatory guidelines for effects testing specify that representative surrogate species for NTOs are exposed to concentrations of insecticidal proteins that are in excess of worst-case predicted exposures in the field. High concentrations in effects tests are achieved by using protein test substances produced in microbes, such as Escherichia coli. In a study that exposed Daphnia magna to a single high concentration of a microbial test substance containing Vip3Aa20, the insecticidal protein in MIR162 maize, small reductions in growth were observed. These effects were surprising as many other studies strongly suggest that the activity of Vip3Aa20 is limited to Lepidoptera. A plausible explanation for the effect on growth is that high concentrations of test substance have a non-toxic effect on Daphnia, perhaps by reducing its feeding rate. A follow-up study tested that hypothesis by exposing D. magna to several concentrations of Vip3Aa20, and a high concentration of a non-toxic protein, bovine serum albumin (BSA). Vip3Aa20 and BSA had sporadic effects on the reproduction and growth of D. magna. The pattern of the effects suggests that they result from non-toxic effects of high concentrations of protein, and not from toxicity. The implications of these results for regulatory NTO effects testing and ERA of IRGM crops are discussed.

Can mixtures of cyanotoxins represent a risk to the zooplankton? The case study of Daphnia magna Straus exposed to hepatotoxic and neurotoxic cyanobacterial extracts.

Science.gov (United States)

Freitas, Emanuela Cristina; Pinheiro, Carlos; Rocha, Odete; Loureiro, Susana

2014-01-01

Worldwide, cyanobacterial blooms have been increasing in intensity and frequency, with toxic cyanobacteria sometimes dominant throughout the year in many freshwater bodies. Since the coexistence of more than one type of cyanotoxins in freshwater environments is a common phenomenon, studies on the joint effects of these toxins would be very useful. In this study, the single and combined effects of two cyanotoxins with different modes of action (hepatotoxic and neurotoxic) on the survival (lethal exposure) and feeding (sublethal exposure) of the cladoceran Daphnia magna were investigated. With the single exposures, it was observed that both the survival and feeding activity of the daphnids were impaired by the hepatotoxic and neurotoxic extracts at environmentally relevant concentrations. In the combined exposures, both survival and feeding rate endpoints showed a good fit to the independent action model. For the acute assay and 24h exposure period in the feeding inhibition test, there was no interaction between components of the hepatotoxic and neurotoxic extracts, although a slight tendency to a synergistic deviation could be seen in the feeding rates. On the other hand, for the 4h post-exposure period, a synergistic deviation was found in feeding rates at all mixture concentrations tested. Hence, the combined exposure of hepatotoxins and neurotoxins should also be taken into account in risk assessments of freshwater bodies, since the mixture of these toxins can result in more severe post-exposure effects on the feeding of daphnids than the sum of those expected for single exposures. Copyright © 2013 Elsevier B.V. All rights reserved.

Health Activities Project (HAP): Action/Reaction Module.

Science.gov (United States)

Buller, Dave; And Others

Contained within this Health Activities Project (HAP) learning packet are activities for children in grades 5-8. Design of the activities centers around the idea that students can control their own health and safety. Within this module are teacher and student folios describing activities in timing, improving, and practicing to improve reaction…

Environmental labeling of car tires--toxicity to Daphnia magna can be used as a screening method.

Science.gov (United States)

Wik, Anna; Dave, Göran

2005-02-01

Car tires contain several water-soluble compounds that can leach into water and have toxic effects on aquatic organisms. Due to tire wear, 10,000 tonnes of rubber particles end up along the Swedish roads every year. This leads to a diffuse input of emissions of several compounds. Emissions of polyaromatic hydrocarbons (PAHs) are of particular concern. PAHs are ingredients of the high aromatic oil (HA oil) that is used in the rubber as a softener and as a filler. The exclusion of HA oils from car tires has started, and an environmental labeling of tires could make HA oils obsolete. The toxicity to Daphnia magna from 12 randomly selected car tires was tested in this study. Rubber from the tread of the tires was grated into small pieces, to simulate material from tire wear, and the rubber was equilibrated with dilution water for 72 h before addition of test organisms. The 24-h EC50s of the rubber pieces ranged from 0.29 to 32 gl-1, and the 48-h EC50s ranged from 0.0625 to 2.41 gl-1. Summer tires were more toxic than winter tires. After the 48-h exposure, the daphnids were exposed to UV-light for 2 h, to determine if the tires contained compounds that were phototoxic. After UV-activation the EC50s ranged from 0.0625 to 0.38 gl-1. Four of the 12 tires had a very distinct photoactivation, with a toxicity increase of >10 times. This study has shown that the used method for toxicity testing with Daphnia magna according to ISO 6341 could be used as a basis for environmental labeling of car tires.

Activity in ventral premotor cortex is modulated by vision of own hand in action

Directory of Open Access Journals (Sweden)

Luciano Fadiga

2013-07-01

Full Text Available Parietal and premotor cortices of the macaque monkey contain distinct populations of neurons which, in addition to their motor discharge, are also activated by visual stimulation. Among these visuomotor neurons, a population of grasping neurons located in the anterior intraparietal area (AIP shows discharge modulation when the own hand is visible during object grasping. Given the dense connections between AIP and inferior frontal regions, we aimed at investigating whether two hand-related frontal areas, ventral premotor area F5 and primary motor cortex (area F1, contain neurons with similar properties. Two macaques were involved in a grasping task executed in various light/dark conditions in which the to-be-grasped object was kept visible by a dim retro-illumination. Approximately 62% of F5 and 55% of F1 motor neurons showed light/dark modulations. To better isolate the effect of hand-related visual input, we introduced two further conditions characterized by kinematic features similar to the dark condition. The scene was briefly illuminated (i during hand preshaping (pre-touch flash, PT-flash and (ii at hand-object contact (touch flash, T-flash. Approximately 48% of F5 and 44% of F1 motor neurons showed a flash-related modulation. Considering flash-modulated neurons in the two flash conditions, ∼40% from F5 and ∼52% from F1 showed stronger activity in PT- than T-flash (PT-flash-dominant, whereas ∼60% from F5 and ∼48% from F1 showed stronger activity in T- than PT-flash (T-flash-dominant. Furthermore, F5, but not F1, flash-dominant neurons were characterized by a higher peak and mean discharge in the preferred flash condition as compared to light and dark conditions. Still considering F5, the distribution of the time of peak discharge was similar in light and preferred flash conditions. This study shows that the frontal cortex contains neurons, previously classified as motor neurons, which are sensitive to the observation of meaningful

Effects of functionalized fullerenes on bifenthrin and tribufos toxicity to Daphnia magna: Survival, reproduction, and growth rate.

Science.gov (United States)

Brausch, Kathryn A; Anderson, Todd A; Smith, Philip N; Maul, Jonathan D

2010-11-01

Incorporation of carbon nanomaterials into industrial and consumer products is increasing, yet their impact on aquatic ecosystems alone and in chemical mixtures is largely unknown. Carbon nanomaterials may be found in the aquatic environment as mixtures with pesticides because of their proposed use in agriculture as smart delivery systems and nanosensors. The interaction effects of a functionalized fullerene ([1,2-methanofullerene C₆₀]-61-carboxylic acid) (fC₆₀) at 52.8 µg/L and the hydrophobic pesticides bifenthrin and tribufos were examined. The test organism was Daphnia magna, and response variables included 48-h survival, reproduction (bifenthrin, 70-d; tribufos, 21-d), and 10-d growth. Both pesticides reduced D. magna survival and reproduction (p bifenthrin acute toxicity but did not significantly affect chronic endpoints or growth (p > 0.05). Median lethal concentrations (LC50s), median inhibition concentrations (IC50s) for days surviving, and IC50s for reproduction were 0.86, 0.55, and 0.49 µg/L for bifenthrin; 0.22, 0.39, and 0.77 µg/L for fC₆₀-bifenthrin mix; 6.63, 9.89, and 5.79 µg/L for tribufos; and 9.17, 8.17, and 6.59 µg/L for fC₆₀-tribufos mix. Mixtures did not affect instantaneous growth rate (p > 0.05). These results suggest that fC₆₀ had little effect on pesticide chronic toxicity but influenced acute toxicity. Given the widespread application of nanotechnology, the influence of nanomaterials on environmental contaminants is an important consideration. Thus, our results may be useful in the development and use of nanotechnology in agricultural practices. © 2010 SETAC.

Identification of a novel modulator of thyroid hormone receptor-mediated action.

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Bernhard G Baumgartner

Full Text Available BACKGROUND: Diabetes is characterized by reduced thyroid function and altered myogenesis after muscle injury. Here we identify a novel component of thyroid hormone action that is repressed in diabetic rat muscle. METHODOLOGY/PRINCIPAL FINDINGS: We have identified a gene, named DOR, abundantly expressed in insulin-sensitive tissues such as skeletal muscle and heart, whose expression is highly repressed in muscle from obese diabetic rats. DOR expression is up-regulated during muscle differentiation and its loss-of-function has a negative impact on gene expression programmes linked to myogenesis or driven by thyroid hormones. In agreement with this, DOR enhances the transcriptional activity of the thyroid hormone receptor TR(alpha1. This function is driven by the N-terminal part of the protein. Moreover, DOR physically interacts with TR( alpha1 and to T(3-responsive promoters, as shown by ChIP assays. T(3 stimulation also promotes the mobilization of DOR from its localization in nuclear PML bodies, thereby indicating that its nuclear localization and cellular function may be related. CONCLUSIONS/SIGNIFICANCE: Our data indicate that DOR modulates thyroid hormone function and controls myogenesis. DOR expression is down-regulated in skeletal muscle in diabetes. This finding may be of relevance for the alterations in muscle function associated with this disease.

Coherent states on Hilbert modules

International Nuclear Information System (INIS)

Ali, S Twareque; Bhattacharyya, T; Roy, S S

2011-01-01

We generalize the concept of coherent states, traditionally defined as special families of vectors on Hilbert spaces, to Hilbert modules. We show that Hilbert modules over C*-algebras are the natural settings for a generalization of coherent states defined on Hilbert spaces. We consider those Hilbert C*-modules which have a natural left action from another C*-algebra, say A. The coherent states are well defined in this case and they behave well with respect to the left action by A. Certain classical objects like the Cuntz algebra are related to specific examples of coherent states. Finally we show that coherent states on modules give rise to a completely positive definite kernel between two C*-algebras, in complete analogy to the Hilbert space situation. Related to this, there is a dilation result for positive operator-valued measures, in the sense of Naimark. A number of examples are worked out to illustrate the theory. Some possible physical applications are also mentioned.

Sequence analysis of ribosomal and mitochondrial genes of the giant liver fluke Fascioloides magna (Trematoda: Fasciolidae): intraspecific variation and differentiation from Fasciola hepatica

Czech Academy of Sciences Publication Activity Database

Kráľová-Hromadová, I.; Špakulová, M.; Horáčková, Eva; Turčeková, Ĺ.; Novobilský, A.; Beck, R.; Koudela, Břetislav; Marinculić, A.; Rajský, D.; Pybus, M.

2008-01-01

Roč. 94, č. 1 (2008), s. 58-67 ISSN 0022-3395 R&D Projects: GA ČR GD524/03/H133; GA AV ČR IAA6022404 Grant - others:Slovak Research and Development Agency(SK) APVV-51-062205 Institutional research plan: CEZ:AV0Z60220518 Keywords : Fascioloides magna * Fasciola hepatica * ribosomal genes * mitochondrial genes Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.165, year: 2008

CLICing into action

CERN Multimedia

Barbara Warmbein

2015-01-01

Putting its acronym into action, the Compact Linear Collider (CLIC) collaboration is testing its first compact accelerator module in the CTF3 test facility. Fed by high-power waveguides, cables and cooling tubes, the module has all the functions of future CLIC modules and allows the experts to test all the features, including frequency, losses, damping, acceleration and deceleration.   The new CLIC module in the CTF3 test facility. CLIC is one of the potential follow-up projects to the LHC, alongside the International Linear Collider (ILC) and the Future Circular Collider (FCC) studies. Instead of smashing protons into protons, it is designed to collide electrons with positrons. Following the publication of its CDR in 2012, the CLIC collaboration entered the project preparation phase - testing its unique technology, making improvements and taking a closer look at the cost of the individual components. This is where the new module comes in. While many of the techniques and technologies neede...

Behavior and chronic toxicity of two differently stabilized silver nanoparticles to Daphnia magna

DEFF Research Database (Denmark)

Sakka, Yvonne; Skjolding, Lars Michael; Mackevica, Aiga

2016-01-01

While differences in silver nanoparticle (AgNP) colloidal stability, surface potential, or acute aquatic toxicity for differently stabilized AgNP have often been reported, these have rarely been studied in long-term ecotoxicity tests. In the current study, we investigated the chronic toxicity of Ag...... types of AgNP during a typical media exchange period in the D. magna test for chronic toxicity. As expected, the sterically stabilized AgNP were more stable in the test medium, also in the presence of food; however, a higher uptake of silver after 24 h exposure of the charge stabilized AgNP was found...... compared to the detergent-stabilized AgNP (0.046 ± 0.006 μg Ag μg DW−1 and 0.023 ± 0.005 μg Ag μg DW−1, respectively). In accordance with this, the higher reproductive effects and mortality were found for the charge-stabilized than for the sterically-stabilized silver nanoparticles in 21-d tests...

Valenced action/inhibition learning in humans is modulated by a genetic variant linked to dopamine D2 receptor expression

Directory of Open Access Journals (Sweden)

Anni eRichter

2014-08-01

Full Text Available Motivational salience plays an important role in shaping human behavior, but recent studies demonstrate that human performance is not uniformly improved by motivation. Instead, action has been shown to dominate valence in motivated tasks, and it is particularly difficult for humans to learn the inhibition of an action to obtain a reward, but the neural mechanism behind this behavioral specificity is yet unclear. In all mammals, including humans, the monoamine neurotransmitter dopamine is particularly important in the neural manifestation of appetitively motivated behavior, and the human dopamine system is subject to considerable genetic variability. The well-studied TaqIA restriction fragment length polymorphism (rs1800497 has previously been shown to affect striatal dopamine metabolism. In this study we investigated a potential effect of this genetic variation on motivated action/inhibition learning. Two independent cohorts consisting of 87 and 95 healthy participants, respectively, were tested using the previously described valenced go/no-go learning paradigm in which participants learned the reward-associated no-go condition significantly worse than all other conditions. This effect was modulated by the TaqIA polymorphism, with carriers of the A1 allele showing a diminished learning-related performance enhancement in the rewarded no-go condition compared to the A2 homozygotes. This result highlights a modulatory role for genetic variability of the dopaminergic system in individual learning differences of action-valence interaction.

Observing back pain provoking lifting actions modulates corticomotor excitability of the observer's primary motor cortex.

Science.gov (United States)

Lehner, Rea; Meesen, Raf; Wenderoth, Nicole

2017-07-01

Observing another person experiencing exogenously inflicted pain (e.g. by a sharp object penetrating a finger) modulates the excitability of the observer' primary motor cortex (M1). By contrast, far less is known about the response to endogenously evoked pain such as sudden back pain provoked by lifting a heavy object. Here, participants (n=26) observed the lifting of a heavy object. During this action the actor (1) flexed and extended the legs (LEG), (2) flexed and extended the back (BACK) or (3) flexed and extended the back which caused visible pain (BACKPAIN). Corticomotor excitability was measured by applying a single transcranial magnetic stimulation pulse to the M1 representation of the muscle erector spinae and participants scored their perception of the actor's pain on the numeric pain rating scale (NPRS). The participants scored vicarious pain as highest during the BACKPAIN condition and lowest during the LEG condition. MEP size was significantly lower for the LEG than the BACK and BACKPAIN condition. Although we found no statistical difference in the motor-evoked potential (MEP) size between the conditions BACK and BACKPAIN, there was a significant correlation between the difference in NPRS scores between the conditions BACKPAIN and BACK and the difference in MEP size between these conditions. Participants who believed the vicarious pain to be much stronger in the BACKPAIN than in the BACK condition also exhibited higher MEPs for the BACKPAIN than the BACK condition. Our results indicate that observing how others lift heavy objects facilitates motor representations of back muscles in the observer. Modulation occurs in a movement-specific manner and is additionally modulated by the extent to which the participants perceived the actor's pain. Our findings suggest that movement observation might be a promising paradigm to study the brain's response to back pain. Copyright © 2017 Elsevier Ltd. All rights reserved.

Testosterone Modulates Altered Prefrontal Control of Emotional Actions in Psychopathic Offenders(1,2,3).

Science.gov (United States)

Volman, Inge; von Borries, Anna Katinka Louise; Bulten, Berend Hendrik; Verkes, Robbert Jan; Toni, Ivan; Roelofs, Karin

2016-01-01

Psychopathic individuals are notorious for their controlled goal-directed aggressive behavior. Yet, during social challenges, they often show uncontrolled emotional behavior. Healthy individuals can control their social emotional behavior through anterior prefrontal cortex (aPFC) downregulation of neural activity in the amygdala, with testosterone modulating aPFC-amygdala coupling. This study tests whether individual differences in this neuroendocrine system relate to the paradoxical lack of emotional control observed in human psychopathic offenders. Emotional control was operationalized with an fMRI-adapted approach-avoidance task requiring rule-driven control over rapid emotional responses. Fifteen psychopathic offenders and 19 matched healthy control subjects made approaching and avoiding movements in response to emotional faces. Control of social emotional behavior was required during affect-incongruent trials, when participants had to override affect-congruent, automatic action tendencies and select the opposite response. Psychopathic offenders showed less control-related aPFC activity and aPFC-amygdala coupling during trials requiring control of emotional actions, when compared with healthy control subjects. This pattern was particularly pronounced in psychopathic individuals with high endogenous testosterone levels. These findings suggest that reduced prefrontal coordination underlies reduced behavioral control in psychopathic offenders during emotionally provoking situations. Even though the modest sample size warrants replication, the modulatory role of endogenous testosterone on the aPFC-amygdala circuit suggests a neurobiological substrate of individual differences that is relevant for the advancement of treatment and the reduction of recidivism.

Discordant K-Ar ages between hornblende and biotite from the Tanzawa tonalitic pluton in the southern Fossa Magna, central Japan

International Nuclear Information System (INIS)

Sato, Kohei; Shibata, Ken; Uchiumi, Shigeru

1986-01-01

K-Ar ages were determined for hornblende and biotite in three tonalites from the Tanzawa pluton in the southern Fossa Magna, central Japan. The two minerals show discordant ages of 10.1 and 10.7 Ma for hornblende and 4.6 - 5.1 Ma for biotite. The age data and field evidence indicate that the pluton was emplaced in the Tanzawa Group in Middle Miocene time and its slow cooling (ca. 50 deg C/Ma in average) resulted in younger ages of boitites than hornblendes due to lower closure temperature for biotite. (author)

Not all that glitters is gold - Electron microscopy study on uptake of gold nanoparticles in Daphnia magna and related artefacts

DEFF Research Database (Denmark)

Jensen, Louise Helene Søgaard; Skjolding, Lars Michael; Thit, Amalie

2017-01-01

techniques are used to investigate internalization of 10 nm gold nanoparticles in Daphnia magna gut lumen and gut epithelial cells upon 24h exposure and outline potential artefacts, i.e. high contract precipitates from sample preparation related to these techniques. Light sheet microscopy confirmed...... accumulation of gold nanoparticles in the gut lumen. Scanning transmission electron microscopy and elemental analysis revealed gold nanoparticles attached to the microvilli of gut cells. Interestingly, the peritrophic membrane appeared to act as a semipermeable barrier between the lumen and the gut epithelium...

Comparing humic substance and protein compound effects on the bioaccumulation of perfluoroalkyl substances by Daphnia magna in water.

Science.gov (United States)

Xia, Xinghui; Dai, Zhineng; Rabearisoa, Andry Harinaina; Zhao, Pujun; Jiang, Xiaoman

2015-01-01

The influence of humic substances and protein compounds on the bioaccumulation of six types of perfluoroalkyl substances (PFASs) in Daphnia magna was compared. The humic substances included humic acid (HA) and fulvic acid (FA), the protein compounds included chicken egg albumin (albumin) and peptone, and the PFASs included perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid, perfluoroundecanoic acid, and perfluorododecanoic acid. Four concentrations (0, 1, 10, and 20 mg L(-1)) of the four dissolved organic matter (DOM) types were investigated. At the 1 mg L(-1) level, HA and albumin enhanced all tested PFAS bioaccumulation, whereas FA and peptone only enhanced the bioaccumulation of shorter-chain PFASs (PFOS, PFOA, and PFNA). However, all four DOM types decreased all tested PFAS bioaccumulation at the 20 mg L(-1) level, and the decreasing ratios of bioaccumulation factors caused by FA, HA, albumin, and peptone were 1-49%, 23-77%, 17-58%, and 8-56%, respectively compared with those without DOM. This is because DOM not only reduced the bioavailable concentrations and uptake rates of PFASs but also lowered the elimination rates of PFASs in D. magna, and these opposite effects would change with different DOM types and concentrations. Although the partition coefficients (L kg(-1)) of PFASs between HA and water (10(4.21)-10(4.98)) were much lower than those between albumin and water (10(4.92)-10(5.86)), their effects on PFAS bioaccumulation were comparable. This study suggests that although PFASs are a type of proteinophilic compounds, humic substances also have important effects on their bioavailability and bioaccumulation in aquatic organisms. Copyright © 2014 Elsevier Ltd. All rights reserved.

Acupuncture's Cardiovascular Actions: A Mechanistic Perspective.

Science.gov (United States)

Longhurst, John

2013-04-01

Over the last several decades, there has been an explosion of articles on acupuncture, including studies that have begun to explore mechanisms underlying its analgesic and cardiovascular actions. Modulation of cardiovascular function is most effective during manual and low-frequency, low-intensity electroacupuncture (EA) at a select set of acupoints situated along meridians located over deep somatic nerves on the upper and lower extremities. Stimulation at these acupoints activates underlying sensory neural pathways that project to a number of regions in the central nervous system (CNS) that ultimately regulate autonomic outflow and hence cardiovascular function. A long-loop pathway involving the hypothalamus, midbrain, and medulla underlies EA modulation of reflex increases in blood pressure (BP). Actions of excitatory and inhibitory neurotransmitters in the supraspinal CNS underlie processing of the somatic input and adjustment of autonomic outflow during EA. Acupuncture also decreases elevated blood pressure through actions in the thoracic spinal cord. Reflexes that lower BP likewise are modulated by EA through its actions on sympathetic and parasympathetic nuclei in the medulla. The autonomic influence of acupuncture is slow in onset but prolonged in duration, typically lasting beyond the period of stimulation. Clinical studies suggest that acupuncture can be used to treat cardiac diseases, such as myocardial ischemia and hypertension, associated with overactivity of the sympathetic nervous system.

The effect of food on the respiration rates of Daphnia magna using a flow-through system

Directory of Open Access Journals (Sweden)

Claire Schmoker

2003-09-01

Full Text Available Respiration rates and gut fluorescence of the cladoceran Daphnia magna were studied using a flow-through system. This open system has the advantage of introducing food or producing a starvation effect during the course of the experiment. Severe variations in respiratory rates were observed in relation to the presence or absence of food, indicating short-term variability. Organisms kept starved or at low food for a long period (15-20 h responded to a sudden increase in food by increasing their respiration rates three- to four-fold in parallel with their gut content. A significant relationship between gut fluorescence and respiration rates was observed, suggesting that feeding and the related swimming activity were responsible for the observed metabolic variability.

The relationship between action-effect monitoring and attention capture.

Science.gov (United States)

Kumar, Neeraj; Manjaly, Jaison A; Sunny, Meera Mary

2015-02-01

Many recent findings suggest that stimuli that are perceived to be the consequence of one's own actions are processed with priority. According to the preactivation account of intentional binding, predicted consequences are preactivated and hence receive a temporal advantage in processing. The implications of the preactivation account are important for theories of attention capture, as temporal advantage often translates to attention capture. Hence, action might modulate attention capture by feature singletons. Experiment 1 showed that a motion onset and color change captured attention only when it was preceded by an action. Experiment 2 showed that the capture occurs only with predictable, but not with unpredictable, consequences of action. Experiment 3 showed that even when half the display changed color at display transition, they were all prioritized. The results suggest that action modulates attentional control.

Visual search is modulated by action intentions

NARCIS (Netherlands)

Bekkering, H; Neggers, SFW

The influence of action intentions on visual selection processes was investigated in a visual search paradigm. A predefined target object with a certain orientation and color was presented among distractors, and subjects had to either look and point at the target or look at and grasp the target.

Toxicity of platinum, palladium and rhodium to Daphnia magna in single and binary metal exposure experiments.

Science.gov (United States)

Zimmermann, Sonja; Wolff, Carolina; Sures, Bernd

2017-05-01

Mainly due to automobile traffic, but also due to other sources, the platinum group elements (PGE) platinum (Pt), palladium (Pd) and rhodium (Rh) are introduced into aquatic biotopes where they accumulate in sediments of lakes and rivers. However, the toxicity of these noble metals to aquatic organisms is not well understood and especially toxicity studies under standardized condition are lacking. Thus, the toxicity of Pt, Pd and Rh to Daphnia magna was tested in single metal exposure experiments according to OECD guideline 202. Immobility and lethality was recorded after 24 h and 48 h of exposure and EC 50 and LC 50 , respectively, were determined. As the nominal exposure concentration of Pd differed significantly from the quantified concentration, the control of the real exposure concentration by chemical analysis is mandatory, especially for Pd. The toxicity decreased in the order Pd > Pt ≫ Rh with e.g. LC 50 (48 h) values of 14 μg/L for Pd, 157 μg/L for Pt and 56,800 μg/L for Rh. The exposure period had a clear effect on the toxicity of Pt, Pd and Rh. For Pt and Rh the endpoint immobility was more sensitive than the endpoint lethality whereas Pd toxicity was similar for both endpoints. The Hill slopes, which are a measure for the steepness of the concentration-response curves, showed no significant discrepancies between the different metals. The binary metal exposure to Pt and Pd revealed a more-than-additive, i.e. a synergistic toxicity using the toxic unit approach. The present study is a start to understand the toxicity of interacting PGE. The modes of action behind the synergistic effect are unclear. Copyright © 2017 Elsevier Ltd. All rights reserved.

Visual Context Modulates Action Perception In 10-Month-Old Infants

OpenAIRE

Noack, Hannes; Werkle-Bergner, Markus; Lindenberger, Ulman; Kopp, Franziska; Stadler, Waltraud; Springer, Anne; Bache, Cathleen

2017-01-01

Research on early action perception has documented infants' astounding abilities in tracking, predicting, and understanding other people's actions. Common interpretations of previous findings tend to generalize across a wide range of action stimuli and contexts. In this study, ten-month-old infants repeatedly watched a video of a same-aged crawling baby that was transiently occluded. The video was presented in alternation with videos displaying visually either dissimilar movements (i.e., dist...

Dopamine modulates male sexual behavior in Japanese quail in part via actions on noradrenergic receptors.

Science.gov (United States)

Cornil, Charlotte A; Dejace, Christel; Ball, Gregory F; Balthazart, Jacques

2005-08-30

In rats, dopamine (DA) facilitates male sexual behavior through its combined action on D1- and D2-like receptors, in the medial preoptic area (MPOA) as well as other brain areas. In Japanese quail, systemic injections of dopaminergic drugs suggested a similar pharmacology but central injections have never been performed. Recent electrophysiological experiments demonstrated that DA effects in the MPOA of quail are mediated mainly through the activation of alpha2-noradrenergic receptors. Previous studies of DA action on behavior used specific dopaminergic agonists/antagonists and therefore unintentionally avoided the potential cross-reaction with alpha2-receptors. The present study was thus designed to investigate directly the effects of DA on male sexual behavior and to test whether the interaction of DA with heterologous receptors affects this behavior. Intracerebroventricular (i.c.v.) injection of DA or NE inhibited copulation in a dose-dependent manner. Systemic injections of yohimbine, an alpha2-noradrenergic antagonist, modulated copulation in a bimodal manner depending on the dose injected. Interestingly, a behaviorally ineffective dose of yohimbine markedly reduced the inhibitory effects of DA when injected 15min before. Together, these results show for the first time that i.c.v. injections of DA itself inhibit male sexual behavior in quail and suggest that the interaction of DA with alpha2-receptors has behavioral significance.

Leadership development through action learning sets: an evaluation study.

Science.gov (United States)

Walia, Surinder; Marks-Maran, Di

2014-11-01

This article examines the use of action learning sets in a leadership module delivered by a university in south east England. An evaluation research study was undertaking using survey method to evaluate student engagement with action learning sets, and their value, impact and sustainability. Data were collected through a questionnaire with a mix of Likert-style and open-ended questions and qualitative and quantitative data analysis was undertaken. Findings show that engagement in the action learning sets was very high. Action learning sets also had a positive impact on the development of leadership knowledge and skills and are highly valued by participants. It is likely that they would be sustainable as the majority would recommend action learning to colleagues and would consider taking another module that used action learning sets. When compared to existing literature on action learning, this study offers new insights as there is little empirical literature on student engagement with action learning sets and even less on value and sustainability. Copyright © 2014 Elsevier Ltd. All rights reserved.

Genetic theory – a suggested cupping therapy mechanism of action

OpenAIRE

Shaban , Tamer; Ravalia , Munir

2017-01-01

The Cupping Therapy mechanism of action is not clear. Cupping may increase local blood circulation, and may have an immunomodulation effect. Local and systemic effects of Cupping Therapy were reported. Genetic expression is a physiological process that regulates body functions. Genetic modulation is a reported acupuncture effect. In this article, the authors suggest genetic modulation theory as one of the possible mechanisms of action of cupping therapy.

Impaired reproduction and individual growth of the water flea Daphnia magna as consequence of exposure to the non-ester pyrethroid etofenprox.

Science.gov (United States)

Sancho, Encarna; Banegas, Sandra; Villarroel, María José; Ferrando, Dolores

2018-03-01

The effect of the pesticide etofenprox (0.76, 0.95, 1.18, 1.48, and 1.85 μg L -1 ) on survival, reproduction, and growth of Daphnia magna organisms was monitored using 21-day exposure tests. In order to test pesticide effects on D. magna, survival, length, mean total neonates per female, mean brood size, time to first reproduction, mean number broods per female, cumulative molting, and the population parameter intrinsic rate of natural increase (r) were used. Reproduction was seriously affected by etofenprox. Concentrations of etofenprox higher than 1.18 μg L -1 affected all the reproductive parameters analyzed as well as individual length. However, daphnids' survival after 21 days of pesticide exposure did not exhibited differences among experimental and control groups. The no observed effect concentration (NOEC), the lowest observed effect concentration (LOEC), and the maximum acceptable toxicant concentration (MATC) were calculated for the different parameters. A MATC estimation of 1.32 μg L -1 was calculated for mean brood size, mean number of broods per female, mean number of neonates per female, and the intrinsic rate of growth population. Etofenprox effect on the algae Nannochloris oculata was also evaluated. The selected etofenprox concentrations did not affect algal growth rate (μ) after 24 h; however, N. oculata exposed during 48 and 72 h to the highest etofenprox concentration showed a decreased in its population rate.

Effect of subcellular distribution on nC₆₀ uptake and transfer efficiency from Scenedesmus obliquus to Daphnia magna.

Science.gov (United States)

Chen, Qiqing; Hu, Xialin; Yin, Daqiang; Wang, Rui

2016-06-01

The potential uptake and trophic transfer ability of nanoparticles (NPs) in aquatic organisms have not been well understood yet. There has been an increasing awareness of the subcellular fate of NPs in organisms, but how the subcellular distribution of NPs subsequently affects the trophic transfer to predator remains to be answered. In the present study, the food chain from Scenedesmus obliquus to Daphnia magna was established to simulate the trophic transfer of fullerene aqueous suspension (nC60). The nC60 contaminated algae were separated into three fractions: cell wall (CW), cell organelle (CO), and cell membrane (CM) fractions, and we investigated the nC60 uptake amounts and trophic transfer efficiency to the predator through dietary exposure to algae or algal subcellular fractions. The nC60 distribution in CW fraction of S. obliquus was the highest, following by CO and CM fractions. nC60 uptake amounts in D. magna were found to be mainly relative to the NPs' distribution in CW fraction and daphnia uptake ability from CW fraction, whereas the nC60 trophic transfer efficiency (TE) were mainly in accordance with the transfer ability of NPs from the CO fraction. CW fed group possessed the highest uptake amount, followed by CO and CM fed groups, but the presence of humic acid (HA) significantly decreased the nC60 uptake from CW fed group. The CO fed groups acquired high TE values for nC60, while CM fed groups had low TE values. Moreover, even though CW fed group had a high TE value; it decreased significantly with the presence of HA. This study contributes to the understanding of fullerene NPs' dietary exposure to aquatic organisms, suggesting that NPs in different food forms are not necessarily equally trophically available to the predator. Copyright © 2016 Elsevier Inc. All rights reserved.

Infections by Pasteuria do not protect its natural host Daphnia magna from subsequent infections.

Science.gov (United States)

Duneau, David; Ebert, Dieter; Du Pasquier, Louis

2016-04-01

The existence of immunological memory in invertebrates remains a contentious topic. Exposure of Daphnia magna crustaceans to a noninfectious dose of the bacterium Pasteuria ramosa has been reported to reduce the chance of future infection upon exposure to higher doses. Using clonal hosts and parasites, we tested whether initial exposure of the host to the parasite (priming), followed by clearing of the parasite with antibiotic, protects the host from a second exposure (challenge). Our experiments included three treatments: priming and challenge with the same or with a different parasite clone, or no priming. Two independent experiments showed that both the likelihood of infection and the degree of parasite proliferation did not differ between treatments, supporting the conclusion that there is no immunological memory in this system. We discuss the possibility that previous discordant reports could result from immune or stress responses that did not fade following initial priming. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of pH on the toxicity and bioconcentration of sulfadiazine on Daphnia magna

DEFF Research Database (Denmark)

Anskjær, Gitte Gotholdt; Rendal, Cecilie; Kusk, Kresten Ole

2013-01-01

The antimicrobial sulfonamide sulfadiazine has in the last decades been detected in environmental water bodies, both surface and ground water. Since pH in the environment may vary considerably, this study examined the toxicity of the amphoter sulfadiazine towards Daphnia magna at pH levels of 6.......0, 7.5 and 8.5, thus taking the impact of speciation into consideration, contrary to earlier eco-toxicity studies conducted at standard conditions. Toxicity tests were performed using the standard ISO 6341 test procedure modified to accommodate the three pH levels and the toxicity was expressed as EC50....... After 48h the EC50 was determined to be 27.2, 188 and 310mgL−1 at pH 6.0, 7.5 and 8.5, respectively, thus demonstrating a significant effect of pH on the toxicity of sulfadiazine. Furthermore, the bioconcentration factor (dry weight) was determined to be 50 and 36 at pH 6.0 and 8.5, respectively...

Bodily action penetrates affective perception

Science.gov (United States)

Rigutti, Sara; Gerbino, Walter

2016-01-01

Fantoni & Gerbino (2014) showed that subtle postural shifts associated with reaching can have a strong hedonic impact and affect how actors experience facial expressions of emotion. Using a novel Motor Action Mood Induction Procedure (MAMIP), they found consistent congruency effects in participants who performed a facial emotion identification task after a sequence of visually-guided reaches: a face perceived as neutral in a baseline condition appeared slightly happy after comfortable actions and slightly angry after uncomfortable actions. However, skeptics about the penetrability of perception (Zeimbekis & Raftopoulos, 2015) would consider such evidence insufficient to demonstrate that observer’s internal states induced by action comfort/discomfort affect perception in a top-down fashion. The action-modulated mood might have produced a back-end memory effect capable of affecting post-perceptual and decision processing, but not front-end perception. Here, we present evidence that performing a facial emotion detection (not identification) task after MAMIP exhibits systematic mood-congruent sensitivity changes, rather than response bias changes attributable to cognitive set shifts; i.e., we show that observer’s internal states induced by bodily action can modulate affective perception. The detection threshold for happiness was lower after fifty comfortable than uncomfortable reaches; while the detection threshold for anger was lower after fifty uncomfortable than comfortable reaches. Action valence induced an overall sensitivity improvement in detecting subtle variations of congruent facial expressions (happiness after positive comfortable actions, anger after negative uncomfortable actions), in the absence of significant response bias shifts. Notably, both comfortable and uncomfortable reaches impact sensitivity in an approximately symmetric way relative to a baseline inaction condition. All of these constitute compelling evidence of a genuine top-down effect on

Bodily action penetrates affective perception

Directory of Open Access Journals (Sweden)

Carlo Fantoni

2016-02-01

Full Text Available Fantoni & Gerbino (2014 showed that subtle postural shifts associated with reaching can have a strong hedonic impact and affect how actors experience facial expressions of emotion. Using a novel Motor Action Mood Induction Procedure (MAMIP, they found consistent congruency effects in participants who performed a facial emotion identification task after a sequence of visually-guided reaches: a face perceived as neutral in a baseline condition appeared slightly happy after comfortable actions and slightly angry after uncomfortable actions. However, skeptics about the penetrability of perception (Zeimbekis & Raftopoulos, 2015 would consider such evidence insufficient to demonstrate that observer’s internal states induced by action comfort/discomfort affect perception in a top-down fashion. The action-modulated mood might have produced a back-end memory effect capable of affecting post-perceptual and decision processing, but not front-end perception. Here, we present evidence that performing a facial emotion detection (not identification task after MAMIP exhibits systematic mood-congruent sensitivity changes, rather than response bias changes attributable to cognitive set shifts; i.e., we show that observer’s internal states induced by bodily action can modulate affective perception. The detection threshold for happiness was lower after fifty comfortable than uncomfortable reaches; while the detection threshold for anger was lower after fifty uncomfortable than comfortable reaches. Action valence induced an overall sensitivity improvement in detecting subtle variations of congruent facial expressions (happiness after positive comfortable actions, anger after negative uncomfortable actions, in the absence of significant response bias shifts. Notably, both comfortable and uncomfortable reaches impact sensitivity in an approximately symmetric way relative to a baseline inaction condition. All of these constitute compelling evidence of a genuine top

Single- and mixture toxicity of three organic UV-filters, ethylhexyl methoxycinnamate, octocrylene, and avobenzone on Daphnia magna.

Science.gov (United States)

Park, Chang-Beom; Jang, Jiyi; Kim, Sanghun; Kim, Young Jun

2017-03-01

In freshwater environments, aquatic organisms are generally exposed to mixtures of various chemical substances. In this study, we tested the toxicity of three organic UV-filters (ethylhexyl methoxycinnamate, octocrylene, and avobenzone) to Daphnia magna in order to evaluate the combined toxicity of these substances when in they occur in a mixture. The values of effective concentrations (ECx) for each UV-filter were calculated by concentration-response curves; concentration-combinations of three different UV-filters in a mixture were determined by the fraction of components based on EC 25 values predicted by concentration addition (CA) model. The interaction between the UV-filters were also assessed by model deviation ratio (MDR) using observed and predicted toxicity values obtained from mixture-exposure tests and CA model. The results from this study indicated that observed ECx mix (e.g., EC 10mix , EC 25mix , or EC 50mix ) values obtained from mixture-exposure tests were higher than predicted ECx mix (e.g., EC 10mix , EC 25mix , or EC 50mix ) values calculated by CA model. MDR values were also less than a factor of 1.0 in a mixtures of three different UV-filters. Based on these results, we suggest for the first time a reduction of toxic effects in the mixtures of three UV-filters, caused by antagonistic action of the components. Our findings from this study will provide important information for hazard or risk assessment of organic UV-filters, when they existed together in the aquatic environment. To better understand the mixture toxicity and the interaction of components in a mixture, further studies for various combinations of mixture components are also required. Copyright © 2016 Elsevier Inc. All rights reserved.

Temperature-dependent effect of filamentous cyanobacteria on Daphnia magna life history traits

Directory of Open Access Journals (Sweden)

Piotr DAWIDOWICZ

2011-08-01

Full Text Available Filamentous cyanobacteria are unsuitable food for Daphnia due to their poor manageability, poor nutritional value and, in some cases, toxicity. As the strength of harmful effects of cyanobacteria on filter-feeding zooplankton is temperature dependent, the global warming scenarios for eutrophic lakes in temperate zone might include an escalated suppression of Daphnia populations caused by the presence of cyanobacterial filaments. To test this assumption, we conducted life-table experiments with four clones of Daphnia magna fed either a green alga Scenedesmus obliquus or a non-toxic strain of filamentous cyanobacteria Cylindrospermopsis raciborskii in two temperatures (20 °C and 24 °C. Key life history parameters of Daphnia, i.e., age and size at first reproduction, fecundity, and individual growth rate, were measured. Both food and temperature significantly affected Daphnia performance, however, the effect of interaction of these two factors was ambiguous and highly genotype-dependent. We conclude that the temperature increase within the studied range will not necessarily strengthen the suppression of Daphnia growth by filamentous cyanobacteria, but may affect clonal selection within population of Daphnia, thus possibly triggering microevolutionary changes within affected populations.

Use of action requests to control communications

International Nuclear Information System (INIS)

Brady, J.

1988-01-01

This paper discusses the Plant Information Management System (PIMS) that is implemented at Pacific Gas and Electric Company's (PG and E) Diablo Canyon Power Plant (DCPP). PIMS is implemented on IBM mainframes located at the plant, is on-line and interactive, and is accessed via a computer communication system that supports more than 450 IBM 3270 PC workstations. This paper discusses the role of the ACTION REQUEST module of PIMS and how it is used to control plant sensitive communications. The ACTION REQUEST module of PIMS can be accessed from any workstation and during the first year of Commercial Operation of DCPP replaced numerous and redundant forms of manual communication mechanisms. Also in this first year, users at the plant generated approximately 25,000 Action Requests which were controlled through review and approval cycles by PIMS. Each organization assigned action were immediately notified of their responsibilities so that action could be taken in a timely manner. The Diablo Canyon Power Plant broke Westinghouse world-wide operating records for the first year of operation (over 90% availability) due to a well built and reliable plant and due to a responsive Operations organization, which was well informed and controlled

Vanillin selectively modulates the action of antibiotics against resistant bacteria.

Science.gov (United States)

Bezerra, Camila Fonseca; Camilo, Cicera Janaine; do Nascimento Silva, Maria Karollyna; de Freitas, Thiago Sampaio; Ribeiro-Filho, Jaime; Coutinho, Henrique Douglas Melo

2017-12-01

The treatment of infections caused by microorganisms that are resistant to antibiotics represent one of the main challenges of medicine today, especially due to the inefficacy of long-term drug therapy. In the search for new alternatives to treat these infections, many researchers have been looking for new substances derived from natural products to replace, or be used in combination with conventional antibiotics. Vanillin is a phenolic compound whose antimicrobial activity has been used in the elimination of pathogens present in fruits and vegetables. However, its antibacterial and modulating properties remain to be characterized. Therefore, this work aimed to evaluate the antibacterial activity and analyze the modulator activity of vanillin in association with conventional antibiotics. The antimicrobial activity of vanillin was evaluated using the microdilution method to determine the Minimum Inhibitory Concentration (MIC) Standard strains of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and multi-resistant strains of Escherichia coli 06, Staphylococcus aureus 10, Pseudomonas aeruginosa 24 were used in this study. The antibiotic modulating effect was analyzed by combining vanillin with Norfloxacin, Imipenem, Gentamicin, Erythromycin and Tetracycline against the following multiresistant bacteria strains: Escherichia coli 06, Staphylococcus aureus 10 and Pseudomonas aeruginosa 24. Data were analyzed using the ANOVA test of two tracks followed by the post hoc Bonferroni test. Vanillin presented CIMs ≥1024μg/mL against all tested strains demonstrating that it did not present significant antibacterial activity. However, modulated the activity of gentamicin and imipenem against S. aureus and E. coli, causing a synergistic effect, but did not affect the activity of norfloxacin, tetracycline and erythromycin against these same microorganisms. A synergistic effect was also obtained from the association of vanillin with norfloxacin against P

Bone marrow stem cells delivered into the subarachnoid space via cisterna magna improve repair of injured rat spinal cord white matter

Science.gov (United States)

Marcol, Wiesław; Slusarczyk, Wojciech; Sieroń, Aleksander L; Koryciak-Komarska, Halina; Lewin-Kowalik, Joanna

2015-01-01

The influence of bone marrow stem cells on regeneration of spinal cord in rats was investigated. Young adult male Wistar rats were used (n=22). Focal injury of spinal cord white matter at Th10 level was produced using our original non-laminectomy method by means of high-pressured air stream. Cells from tibial and femoral bone marrow of 1-month old rats (n=3) were cultured, labeled with BrdU/Hoechst and injected into cisterna magna (experimental group) three times: immediately after spinal cord injury and 3 as well as 7 days later. Neurons in brain stem and motor cortex were labeled with FluoroGold (FG) delivered caudally from the injury site a week before the end of experiment. Functional outcome and morphological features of regeneration were analyzed during 12-week follow-up. The lesions were characterized by means of MRI. Maximal distance of expansion of implanted cells in the spinal cord was measured and the number of FG-positive neurons in the brain was counted. Rats treated with stem cells presented significant improvement of locomotor performance and spinal cord morphology when compared to the control group. Distance covered by stem cells was 7 mm from the epicenter of the injury. Number of brain stem and motor cortex FG-positive neurons in experimental group was significantly higher than in control. Obtained data showed that bone marrow stem cells are able to induce the repair of injured spinal cord white matter. The route of cells application via cisterna magna appeared to be useful for their delivery in spinal cord injury therapy. PMID:26628950

Processing abstract language modulates motor system activity.

Science.gov (United States)

Glenberg, Arthur M; Sato, Marc; Cattaneo, Luigi; Riggio, Lucia; Palumbo, Daniele; Buccino, Giovanni

2008-06-01

Embodiment theory proposes that neural systems for perception and action are also engaged during language comprehension. Previous neuroimaging and neurophysiological studies have only been able to demonstrate modulation of action systems during comprehension of concrete language. We provide neurophysiological evidence for modulation of motor system activity during the comprehension of both concrete and abstract language. In Experiment 1, when the described direction of object transfer or information transfer (e.g., away from the reader to another) matched the literal direction of a hand movement used to make a response, speed of responding was faster than when the two directions mismatched (an action-sentence compatibility effect). In Experiment 2, we used single-pulse transcranial magnetic stimulation to study changes in the corticospinal motor pathways to hand muscles while reading the same sentences. Relative to sentences that do not describe transfer, there is greater modulation of activity in the hand muscles when reading sentences describing transfer of both concrete objects and abstract information. These findings are discussed in relation to the human mirror neuron system.

Determination of action thresholds for electromagnetic tracking system-guided hypofractionated prostate radiotherapy using volumetric modulated arc therapy

Energy Technology Data Exchange (ETDEWEB)

Zhang, Pengpeng; Mah, Dennis; Happersett, Laura; Cox, Brett; Hunt, Margie; Mageras, Gig [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021 (United States); Department of Radiation Oncology, Montefiore Medical Center, Bronx, New York 10467 (United States); Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021 (United States); Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021 (United States); Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021 (United States)

2011-07-15

Purpose: Hypofractionated prostate radiotherapy may benefit from both volumetric modulated arc therapy (VMAT) due to shortened treatment time and intrafraction real-time monitoring provided by implanted radiofrequency(RF) transponders. The authors investigate dosimetrically driven action thresholds (whether treatment needs to be interrupted and patient repositioned) in VMAT treatment with electromagnetic (EM) tracking. Methods: VMAT plans for five patients are generated for prescription doses of 32.5 and 42.5 Gy in five fractions. Planning target volume (PTV) encloses the clinical target volume (CTV) with a 3 mm margin at the prostate-rectal interface and 5 mm elsewhere. The VMAT delivery is modeled using 180 equi-spaced static beams. Intrafraction prostate motion is simulated in the plan by displacing the beam isocenter at each beam assuming rigid organ motion according to a previously recorded trajectory of the transponder centroid. The cumulative dose delivered in each fraction is summed over all beams. Two sets of 57 prostate motion trajectories were randomly selected to form a learning and a testing dataset. Dosimetric end points including CTV D95%, rectum wall D1cc, bladder wall D1cc, and urethra Dmax, are analyzed against motion characteristics including the maximum amplitude of the anterior-posterior (AP), superior-inferior (SI), and left-right components. Action thresholds are triggered when intrafraction motion causes any violations of dose constraints to target and organs at risk (OAR), so that treatment is interrupted and patient is repositioned. Results: Intrafraction motion has a little effect on CTV D95%, indicating PTV margins are adequate. Tight posterior and inferior action thresholds around 1 mm need to be set in a patient specific manner to spare organs at risk, especially when the prescription dose is 42.5 Gy. Advantages of setting patient specific action thresholds are to reduce false positive alarms by 25% when prescription dose is low, and

Determination of action thresholds for electromagnetic tracking system-guided hypofractionated prostate radiotherapy using volumetric modulated arc therapy

International Nuclear Information System (INIS)

Zhang, Pengpeng; Mah, Dennis; Happersett, Laura; Cox, Brett; Hunt, Margie; Mageras, Gig

2011-01-01

Purpose: Hypofractionated prostate radiotherapy may benefit from both volumetric modulated arc therapy (VMAT) due to shortened treatment time and intrafraction real-time monitoring provided by implanted radiofrequency(RF) transponders. The authors investigate dosimetrically driven action thresholds (whether treatment needs to be interrupted and patient repositioned) in VMAT treatment with electromagnetic (EM) tracking. Methods: VMAT plans for five patients are generated for prescription doses of 32.5 and 42.5 Gy in five fractions. Planning target volume (PTV) encloses the clinical target volume (CTV) with a 3 mm margin at the prostate-rectal interface and 5 mm elsewhere. The VMAT delivery is modeled using 180 equi-spaced static beams. Intrafraction prostate motion is simulated in the plan by displacing the beam isocenter at each beam assuming rigid organ motion according to a previously recorded trajectory of the transponder centroid. The cumulative dose delivered in each fraction is summed over all beams. Two sets of 57 prostate motion trajectories were randomly selected to form a learning and a testing dataset. Dosimetric end points including CTV D95%, rectum wall D1cc, bladder wall D1cc, and urethra Dmax, are analyzed against motion characteristics including the maximum amplitude of the anterior-posterior (AP), superior-inferior (SI), and left-right components. Action thresholds are triggered when intrafraction motion causes any violations of dose constraints to target and organs at risk (OAR), so that treatment is interrupted and patient is repositioned. Results: Intrafraction motion has a little effect on CTV D95%, indicating PTV margins are adequate. Tight posterior and inferior action thresholds around 1 mm need to be set in a patient specific manner to spare organs at risk, especially when the prescription dose is 42.5 Gy. Advantages of setting patient specific action thresholds are to reduce false positive alarms by 25% when prescription dose is low, and

Steroid modulation of the chloride ionophore in rat brain: structure-activity requirements, regional dependence and mechanism of action

Energy Technology Data Exchange (ETDEWEB)

Gee, K.W.; Bolger, M.B.; Brinton, R.E.; Coirini, H.; McEwen, B.S.

1988-08-01

Further in vitro studies of steroids active at the gamma-aminobutyric acidA (GABAA) receptor regulated Cl- channel labeled by (35S)-t-butylbicyclophosphorothionate ((35S)TBPS) reveal additional structural requirements necessary for activity. Evaluation of selected steroids for activity against TBPS-induced convulsions show similar requirements for activity. Interestingly, steroids (e.g., 5 alpha-pregnan-3 alpha, 20 alpha-diol) were identified that have high potency but limited efficacy as modulators of (35S)TBPS binding. These characteristics are reminiscent of the clinically useful benzodiazepines (BZs) such as clonazepam. However, interactions between the prototypical anesthetic-barbiturate, sodium pentobarbital, and steroids active at the Cl- channel suggest that they do not share a common site of action as allosteric modulators of (35S)TBPS and BZ receptor binding. The most potent steroid evaluated, 5 alpha-pregnan-3 alpha-ol-20-one, modulates (35S)TBPS binding at low concentrations (IC50 approximately 17 nM) in a regionally dependent manner. All (35S)TBPS binding sites appear to be functionally coupled to a steroid modulatory site. Because several of the active steroids are metabolites of progesterone, their ability to inhibit the binding of (3H)promegestrone to the cytosolic progestin receptor in rat uterus was evaluated. Those steroids showing potent activity at the GABAA receptor-Cl- ionophore were inactive at the intracellular progestin receptor. Such specificity coupled with their high potency provide additional support for the hypothesis that some of these steroids may be involved in the homeostatic regulation of brain excitability via the GABAA-BZ receptor complex.

Shield verification and validation action matrix summary

International Nuclear Information System (INIS)

Boman, C.

1992-02-01

WSRC-RP-90-26, Certification Plan for Reactor Analysis Computer Codes, describes a series of action items to be completed for certification of reactor analysis computer codes used in Technical Specifications development and for other safety and production support calculations. Validation and verification are integral part of the certification process. This document identifies the work performed and documentation generated to satisfy these action items for the SHIELD, SHLDED, GEDIT, GENPRT, FIPROD, FPCALC, and PROCES modules of the SHIELD system, it is not certification of the complete SHIELD system. Complete certification will follow at a later date. Each action item is discussed with the justification for its completion. Specific details of the work performed are not included in this document but can be found in the references. The validation and verification effort for the SHIELD, SHLDED, GEDIT, GENPRT, FIPROD, FPCALC, and PROCES modules of the SHIELD system computer code is completed

Synchronisation and desynchronisation of self-modulation oscillations in a ring chip laser under the action of a periodic signal and noise

International Nuclear Information System (INIS)

Dudetskiy, V Yu; Lariontsev, E G; Chekina, S N

2014-01-01

The effect of pump noise on the synchronisation of selfmodulation oscillations in a solid-state ring laser with periodic pump modulation is studied numerically and experimentally. It is found that, in contrast to desynchronisation that usually occurs under action of noise in the case of 1/1 synchronisation of self-oscillations by a periodic signal, the effect of noise on 1/2 synchronisation may be positive, namely, at a sufficiently low intensity, pump noise is favourable for synchronisation of self-oscillations, for narrowing of their spectrum, and for increasing the signal-to-noise ratio. (lasers)

Validation of a biotic ligand model on site-specific copper toxicity to Daphnia magna in the Yeongsan River, Korea.

Science.gov (United States)

Park, Jinhee; Ra, Jin-Sung; Rho, Hojung; Cho, Jaeweon; Kim, Sang Don

2018-03-01

The objective of this study was to determine whether the water effect ratio (WER) or biotic ligand model (BLM) could be applied to efficiently develop water quality criteria (WQC) in Korea. Samples were collected from 12 specific sites along the Yeongsan River (YSR), Korea, including two sewage treatment plants and one estuary lake. A copper toxicity test using Daphnia magna was performed to determine the WER and to compare to the BLM prediction. The results of the WER from YSR samples also indicated significantly different copper toxicities in all sites. The model-based predictions showed that effluent and estuary waters had significantly different properties in regard to their ability to be used to investigate water characteristics and copper toxicity. It was supposed that the slight water characteristics changes, such as pH, DOC, hardness, conductivity, among others, influence copper toxicity, and these variable effects on copper toxicity interacted with the water composition. The 38% prediction was outside of the validation range by a factor of two in all sites, showing a poor predictive ability, especially in STPs and streams adjacent to the estuary, while the measured toxicity was more stable. The samples that ranged from pH 7.3-7.7 generated stable predictions, while other samples, including those with lower and the higher pH values, led to more unstable predictions. The results also showed that the toxicity of Cu in sample waters to D. magna was closely proportional to the amounts of acidity, including the carboxylic and phenolic groups, as well as the DOC concentrations. Consequently, the acceptable prediction of metal toxicity in various water samples needs the site-specific results considering the water characteristics such as pH and DOC properties particularly in STPs and estuary regions. Copyright © 2017 Elsevier Inc. All rights reserved.

Bleach Solution Requirement for Hatching of Daphnia magna Resting Eggs

Directory of Open Access Journals (Sweden)

Catur Retnaningdyah

2016-11-01

Full Text Available Daphnia (water fleas belong to the zooplankton group called Cladocerans have sexual reproduction when conditions less favorable that produce diapausing eggs are enclosed in the ephippium. Hatching ephippial eggs in the laboratory is important in ecological, toxicology, genetical, and evolutionary studies. This study aims to improve the current methods of egg hatching from ephippium. Each of 50 ephippium were treated together by placing them in a glass jar and adding 50 mL bleach solution (sodium hypochlorite. Concentrations of sodium hypochlorite used in this experiment were 0%, 0.5%, 1%, 2%, 4% and 8%. These concentration treatments were crossed with the following exposure times (1, 2, 4, 8, 16, and 32 minutes. Culturing was done in 80 mL of artificial Daphnia medium, incubated in constant light and temperatures 20°C for 25 days. There were two repetitions in this experiment that were run at the same time. Result of this experiment showed that pretreatment with 0.5-8% bleach solution significantly increases the yield of total hatch rate of Daphnia magna resting eggs by about 21% over unbleached control. However, there was no significant difference among the bleach treatments. Concentration of bleach solution 0.5%, 1% and 4% significantly accelerated the time period until the first hatching (first day hatching. Difference of exposure time (1 - 32 minutes at each concentration treatments were not influence the yield of total hatch and the time period until first hatching.

Does Branched-Chain Amino Acids Supplementation Modulate Skeletal Muscle Remodeling through Inflammation Modulation? Possible Mechanisms of Action

Directory of Open Access Journals (Sweden)

Humberto Nicastro

2012-01-01

Full Text Available Skeletal muscle protein turnover is modulated by intracellular signaling pathways involved in protein synthesis, degradation, and inflammation. The proinflammatory status of muscle cells, observed in pathological conditions such as cancer, aging, and sepsis, can directly modulate protein translation initiation and muscle proteolysis, contributing to negative protein turnover. In this context, branched-chain amino acids (BCAAs, especially leucine, have been described as a strong nutritional stimulus able to enhance protein translation initiation and attenuate proteolysis. Furthermore, under inflammatory conditions, BCAA can be transaminated to glutamate in order to increase glutamine synthesis, which is a substrate highly consumed by inflammatory cells such as macrophages. The present paper describes the role of inflammation on muscle remodeling and the possible metabolic and cellular effects of BCAA supplementation in the modulation of inflammatory status of skeletal muscle and the consequences on protein synthesis and degradation.

The effects of epoxiconazole and α-cypermethrin on Daphnia magna growth, reproduction, and offspring size

DEFF Research Database (Denmark)

Gottardi, Michele; Birch, Michala Rosa; Dalhoff, Kristoffer

2017-01-01

of sublethal concentrations of epoxiconazole and α-cypermethrin and their mixture on growth, reproduction, and in vivo cytochrome P450 activity of the aquatic crustacean Daphnia magna over 42 d. Continuous exposure to nonlethal concentrations of α-cypermethrin at 20 ng/L negatively affected adult growth...... and number and size of neonates within the first 14 d of exposure. Exposure to epoxiconazole at 25 μg/L increased protein content of adults within 1 to 3 d after initiating exposure and increased cumulative number of offspring at exposure times >31 d. Epoxiconazole enhanced the negative effect of α...... with other stressors such as food scarcity, predation, and pathogens, posing an additional hazard for the organisms at the beginning of their life cycle. Environ Toxicol Chem 2017;9999:1-12. © 2017 SETAC....

Presynaptic signal transduction pathways that modulate synaptic transmission

NARCIS (Netherlands)

de Jong, A.P.H.; Verhage, M.

2009-01-01

Presynaptic modulation is a crucial factor in the adaptive capacity of the nervous system. The coupling between incoming action potentials and neurotransmitter secretion is modulated by firstly, recent activity of the presynaptic axon that leads to the accumulation of residual calcium in the

Modularity and hierarchical organization of action programs in children's acquisition of graphic skills.

Science.gov (United States)

Manoel, Edison de J; Dantas, Luiz; Gimenez, Roberto; de Oliveira, Dalton Lustosa

2011-10-01

The organization of actions is based on modules in memory as a result of practice, easing the demand of performing more complex actions. If this modularization occurs, the elements of the module must remain invariant in new tasks. To test this hypothesis, 35 children, age 10 yr., practiced a graphic criterion task on a digital tablet and completed a complex graphic task enclosing the previous one. Total movement and pause times to draw the figure indicated skill acquisition. A module was identified by the variability of relative timing, pause time, and sequencing. Total movement to perform the criterion task did not increase significantly when it was embedded in the more complex task. Modularity was evidenced by the stability of relative timing and pause time and sequencing. The spatial position of new elements did not perturb the module, so the grammar of action may still have been forming.

Attention, biological motion, and action recognition.

Science.gov (United States)

Thompson, James; Parasuraman, Raja

2012-01-02

Interacting with others in the environment requires that we perceive and recognize their movements and actions. Neuroimaging and neuropsychological studies have indicated that a number of brain regions, particularly the superior temporal sulcus, are involved in a number of processes essential for action recognition, including the processing of biological motion and processing the intentions of actions. We review the behavioral and neuroimaging evidence suggesting that while some aspects of action recognition might be rapid and effective, they are not necessarily automatic. Attention is particularly important when visual information about actions is degraded or ambiguous, or if competing information is present. We present evidence indicating that neural responses associated with the processing of biological motion are strongly modulated by attention. In addition, behavioral and neuroimaging evidence shows that drawing inferences from the actions of others is attentionally demanding. The role of attention in action observation has implications for everyday social interactions and workplace applications that depend on observing, understanding and interpreting actions. Published by Elsevier Inc.

Going deeper into phosphorus adsorbents for lake restoration: Combined effects of magnetic particles, intraspecific competition and habitat heterogeneity pressure on Daphnia magna.

Science.gov (United States)

Del Arco, Ana; Parra, Gema; de Vicente, Inmaculada

2018-02-01

Aquatic population responses to chemical exposure may be exacerbated by intraspecific competition pressures, being also shaped by habitat heterogeneity. Magnetic particles (MPs) have been recently proposed as promising phosphorus (P) adsorbents for lake restoration. This study focuses on assessing the effects of MPs on the abundance of the crustacean Daphnia magna under different levels of both intraspecific competition pressure and habitat heterogeneity. The experimental design consisted of two experiments (in homogeneous and heterogeneous habitats) done in glass jars with four concentrations of MPs: controls of 0g MPsL -1 , and treatments of 1, 1.5 and 2g MPsL -1 . In addition, competition treatments were established by using different population densities, and hence, no competition (C), low (L) and high (H) competition pressures were simulated. The experiments lasted for 7 days, with a 4-day pre-exposure period, in which competition was all allowed to take place, and a 3-day post-exposure period. Twenty-four hours after adding MPs, the MPs were removed by applying a magnetic separation technique. The results showed that competition pressures occurred and significantly reduced population abundances during the pre-exposure period. During the post-exposure period, the combined effects of competition and MPs were detected in both homogeneous (Ho-) and heterogeneous (He-) habitat experiments, showing a significantly drastic reduction in abundances. In fact, the lethal concentration for 50% of the population (LC 50 - 24h) was 0 and 0.16g MPsL -1 in the Ho- and He-experiments respectively, indicating that the addition and especially the removal of MPs cause extreme mortality. These results indicated that even though competition plays a role in shaping populations, its influence was down-weighted by the stronger pressures of MPs. In addition, as no significant differences between homogeneous and heterogeneous habitats were found, we may state that the refuge offered was

The genetic basis of resistance and matching-allele interactions of a host-parasite system: The Daphnia magna-Pasteuria ramosa model.

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Gilberto Bento

2017-02-01

Full Text Available Negative frequency-dependent selection (NFDS is an evolutionary mechanism suggested to govern host-parasite coevolution and the maintenance of genetic diversity at host resistance loci, such as the vertebrate MHC and R-genes in plants. Matching-allele interactions of hosts and parasites that prevent the emergence of host and parasite genotypes that are universally resistant and infective are a genetic mechanism predicted to underpin NFDS. The underlying genetics of matching-allele interactions are unknown even in host-parasite systems with empirical support for coevolution by NFDS, as is the case for the planktonic crustacean Daphnia magna and the bacterial pathogen Pasteuria ramosa. We fine-map one locus associated with D. magna resistance to P. ramosa and genetically characterize two haplotypes of the Pasteuria resistance (PR- locus using de novo genome and transcriptome sequencing. Sequence comparison of PR-locus haplotypes finds dramatic structural polymorphisms between PR-locus haplotypes including a large portion of each haplotype being composed of non-homologous sequences resulting in haplotypes differing in size by 66 kb. The high divergence of PR-locus haplotypes suggest a history of multiple, diverse and repeated instances of structural mutation events and restricted recombination. Annotation of the haplotypes reveals striking differences in gene content. In particular, a group of glycosyltransferase genes that is present in the susceptible but absent in the resistant haplotype. Moreover, in natural populations, we find that the PR-locus polymorphism is associated with variation in resistance to different P. ramosa genotypes, pointing to the PR-locus polymorphism as being responsible for the matching-allele interactions that have been previously described for this system. Our results conclusively identify a genetic basis for the matching-allele interaction observed in a coevolving host-parasite system and provide a first insight into

The genetic basis of resistance and matching-allele interactions of a host-parasite system: The Daphnia magna-Pasteuria ramosa model.

Science.gov (United States)

Bento, Gilberto; Routtu, Jarkko; Fields, Peter D; Bourgeois, Yann; Du Pasquier, Louis; Ebert, Dieter

2017-02-01

Negative frequency-dependent selection (NFDS) is an evolutionary mechanism suggested to govern host-parasite coevolution and the maintenance of genetic diversity at host resistance loci, such as the vertebrate MHC and R-genes in plants. Matching-allele interactions of hosts and parasites that prevent the emergence of host and parasite genotypes that are universally resistant and infective are a genetic mechanism predicted to underpin NFDS. The underlying genetics of matching-allele interactions are unknown even in host-parasite systems with empirical support for coevolution by NFDS, as is the case for the planktonic crustacean Daphnia magna and the bacterial pathogen Pasteuria ramosa. We fine-map one locus associated with D. magna resistance to P. ramosa and genetically characterize two haplotypes of the Pasteuria resistance (PR-) locus using de novo genome and transcriptome sequencing. Sequence comparison of PR-locus haplotypes finds dramatic structural polymorphisms between PR-locus haplotypes including a large portion of each haplotype being composed of non-homologous sequences resulting in haplotypes differing in size by 66 kb. The high divergence of PR-locus haplotypes suggest a history of multiple, diverse and repeated instances of structural mutation events and restricted recombination. Annotation of the haplotypes reveals striking differences in gene content. In particular, a group of glycosyltransferase genes that is present in the susceptible but absent in the resistant haplotype. Moreover, in natural populations, we find that the PR-locus polymorphism is associated with variation in resistance to different P. ramosa genotypes, pointing to the PR-locus polymorphism as being responsible for the matching-allele interactions that have been previously described for this system. Our results conclusively identify a genetic basis for the matching-allele interaction observed in a coevolving host-parasite system and provide a first insight into its molecular basis.

Antitumor and chemosensitizing action of dichloroacetate implicates modulation of tumor microenvironment: A role of reorganized glucose metabolism, cell survival regulation and macrophage differentiation

Energy Technology Data Exchange (ETDEWEB)

Kumar, Ajay; Kant, Shiva; Singh, Sukh Mahendra, E-mail: sukhmahendrasingh@yahoo.com

2013-11-15

Targeting of tumor metabolism is emerging as a novel therapeutic strategy against cancer. Dichloroacetate (DCA), an inhibitor of pyruvate dehydrogenase kinase (PDK), has been shown to exert a potent tumoricidal action against a variety of tumor cells. The main mode of its antineoplastic action implicates a shift of glycolysis to oxidative metabolism of glucose, leading to generation of cytotoxic reactive oxygen intermediates. However, the effect of DCA on tumor microenvironment, which in turn regulates tumor cell survival; remains speculative to a large extent. It is also unclear if DCA can exert any modulatory effect on the process of hematopoiesis, which is in a compromised state in tumor-bearing hosts undergoing chemotherapy. In view of these lacunas, the present study was undertaken to investigate the so far unexplored aspects with respect to the molecular mechanisms of DCA-dependent tumor growth retardation and chemosensitization. BALB/c mice were transplanted with Dalton's lymphoma (DL) cells, a T cell lymphoma of spontaneous origin, followed by administration of DCA with or without cisplatin. DCA-dependent tumor regression and chemosensitization to cisplatin was found to be associated with altered repertoire of key cell survival regulatory molecules, modulated glucose metabolism, accompanying reconstituted tumor microenvironment with respect to pH homeostasis, cytokine balance and alternatively activated TAM. Moreover, DCA administration also led to an alteration in the MDR phenotype of tumor cells and myelopoietic differentiation of macrophages. The findings of this study shed a new light with respect to some of the novel mechanisms underlying the antitumor action of DCA and thus may have immense clinical applications. - Highlights: • DCA modulates tumor progression and chemoresistance. • DCA alters molecules regulating cell survival, glucose metabolism and MDR. • DCA reconstitutes biophysical and cellular composition of tumor microenvironment. �

Antitumor and chemosensitizing action of dichloroacetate implicates modulation of tumor microenvironment: A role of reorganized glucose metabolism, cell survival regulation and macrophage differentiation

International Nuclear Information System (INIS)

Kumar, Ajay; Kant, Shiva; Singh, Sukh Mahendra

2013-01-01

Targeting of tumor metabolism is emerging as a novel therapeutic strategy against cancer. Dichloroacetate (DCA), an inhibitor of pyruvate dehydrogenase kinase (PDK), has been shown to exert a potent tumoricidal action against a variety of tumor cells. The main mode of its antineoplastic action implicates a shift of glycolysis to oxidative metabolism of glucose, leading to generation of cytotoxic reactive oxygen intermediates. However, the effect of DCA on tumor microenvironment, which in turn regulates tumor cell survival; remains speculative to a large extent. It is also unclear if DCA can exert any modulatory effect on the process of hematopoiesis, which is in a compromised state in tumor-bearing hosts undergoing chemotherapy. In view of these lacunas, the present study was undertaken to investigate the so far unexplored aspects with respect to the molecular mechanisms of DCA-dependent tumor growth retardation and chemosensitization. BALB/c mice were transplanted with Dalton's lymphoma (DL) cells, a T cell lymphoma of spontaneous origin, followed by administration of DCA with or without cisplatin. DCA-dependent tumor regression and chemosensitization to cisplatin was found to be associated with altered repertoire of key cell survival regulatory molecules, modulated glucose metabolism, accompanying reconstituted tumor microenvironment with respect to pH homeostasis, cytokine balance and alternatively activated TAM. Moreover, DCA administration also led to an alteration in the MDR phenotype of tumor cells and myelopoietic differentiation of macrophages. The findings of this study shed a new light with respect to some of the novel mechanisms underlying the antitumor action of DCA and thus may have immense clinical applications. - Highlights: • DCA modulates tumor progression and chemoresistance. • DCA alters molecules regulating cell survival, glucose metabolism and MDR. • DCA reconstitutes biophysical and cellular composition of tumor microenvironment. �

Insulin action in brain regulates systemic metabolism and brain function.

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Kleinridders, André; Ferris, Heather A; Cai, Weikang; Kahn, C Ronald

2014-07-01

Insulin receptors, as well as IGF-1 receptors and their postreceptor signaling partners, are distributed throughout the brain. Insulin acts on these receptors to modulate peripheral metabolism, including regulation of appetite, reproductive function, body temperature, white fat mass, hepatic glucose output, and response to hypoglycemia. Insulin signaling also modulates neurotransmitter channel activity, brain cholesterol synthesis, and mitochondrial function. Disruption of insulin action in the brain leads to impairment of neuronal function and synaptogenesis. In addition, insulin signaling modulates phosphorylation of tau protein, an early component in the development of Alzheimer disease. Thus, alterations in insulin action in the brain can contribute to metabolic syndrome, and the development of mood disorders and neurodegenerative diseases. © 2014 by the American Diabetes Association.

Comparative toxicity of leachates from 52 textiles to Daphnia magna.

Science.gov (United States)

Dave, Göran; Aspegren, Pia

2010-10-01

The environmental aspects of textiles are very complex and include production, processing, transport, usage, and recycling. Textiles are made from a variety of materials and can contain a large number of chemicals. Chemicals are used during production of fibres, for preservation and colouring and they are released during normal wear and during washing. The aim of this study was to investigate the release to water of toxic chemicals from various textiles. Altogether 52 samples of textiles made from cotton (21), linen (4), cotton and linen (7), cellulose (3), synthetic fibres (7), cotton and synthetic fibres (8) and wool (2). Seven were eco-labelled. All textiles were cut into squares and placed into Petri dishes with 50 ml ISO test medium in a concentration series (4-256 cm(2)/50 ml) and tested for acute toxicity to Daphnia magna. Estimated EC50s were converted into weight/volume, and 48-h EC50s ranged between 182 g/L. It was not possible to detect any difference between fibre type and toxicity (ANOVA), but a significantly higher toxicity was found for printed versus unprinted cotton and cotton/linen textiles, while the opposite was found for synthetic textiles. Eco-labelled products were evenly distributed on a toxicity scale, which means that eco-labelling in its present form does not necessarily protect users or the environment from exposure to toxic chemicals. Therefore, the results from the present study suggest that bioassays and toxicity tests should become an integrated part of textile environmental quality control programs. Copyright © 2010 Elsevier Inc. All rights reserved.

The Action Observation System when Observing Hand Actions in Autism and Typical Development.

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Pokorny, Jennifer J; Hatt, Naomi V; Colombi, Costanza; Vivanti, Giacomo; Rogers, Sally J; Rivera, Susan M

2015-06-01

Social impairments in individuals with autism spectrum disorders (ASD) may be in part due to difficulty perceiving and recognizing the actions of others. Evidence from imitation studies, which involves both observation and execution of an action, suggests differences, in individuals with ASD, between the ability to imitate goal-directed actions involving objects (transitive actions) and the ability to imitate actions that do not involve objects (intransitive actions). In the present study, we examined whether there were differences in how ASD adolescents encoded transitive and intransitive actions compared to typically developing (TD) adolescents, by having participants view videos of a hand reaching across a screen toward an object or to where an object would be while functional magnetic resonance images were collected. Analyses focused on areas within the action observation network (AON), which is activated during the observation of actions performed by others. We hypothesized that the AON would differentiate transitive from intransitive actions only in the ASD group. However, results revealed that object presence modulated activity in the right inferior frontal gyrus and supramarginal gyrus of the TD group, a differentiation that was not seen in the ASD group. Furthermore, there were no significant group differences between the TD and ASD groups in any of the conditions. This suggests that there is not a global deficit of the AON in individuals with ASD while observing transitive and intransitive actions. © 2015 International Society for Autism Research, Wiley Periodicals, Inc.

Review on the acute Daphnia magna toxicity test – Evaluation of the sensitivity and the precision of assays performed with organisms from laboratory cultures or hatched from dormant eggs

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G. Persoone

2009-08-01

Full Text Available One of the most internationally used bioassays for toxicity screening of chemicals and for toxicity monitoring of effluents and contaminated waters is the acute toxicity test with daphnid crustaceans, and in particular that performed with Daphnia magna.Standard methods have been developed for this assay that were gradually endorsed by national and international organisations dealing with toxicity testing procedures, in view of its application within a regulatory framework. As for all toxicity tests, the organisms used for the acute D. magna assay have to be obtained from live stocks which are cultured in the laboratory on live food (micro-algae.Unsurprisingly the various standard protocols of this particular assay differ – at least to a certain extent – with regard to the test organism culturing conditions. In addition, some technical aspects of the toxicity test such as the effect criterion (mortality of immobility, the exposure time, the type of dilution water, etc., also vary from one standard to another.Although this particular assay is currently used in many countries, the technical and biological problems inherent in year-round culturing and availability of the biological material and the culturing/maintenance costs of live stocks restrict its application to a limited number of highly specialised laboratories.This fundamental bottleneck in toxicity testing triggered investigations which brought forward the concept of “microbiotests” or “small-scale” toxicity tests. “Culture/maintenance free” aquatic microbiotests with species of different phylogenetic groups were developed in the early 1990s at the Laboratory for Environmental Toxicology and Aquatic Ecology at the Ghent University in Belgium.These assays which were given the generic name “Toxkits”, are unique in that they employ dormant stages (“cryptobiotic eggs” of the test species, which can be stored for long periods of time and “hatched” at the time of

Assessing the environmental hazard of individual and combined pharmaceuticals: acute and chronic toxicity of fluoxetine and propranolol in the crustacean Daphnia magna.

Science.gov (United States)

Varano, Valentina; Fabbri, Elena; Pasteris, Andrea

2017-08-01

Pharmaceuticals are widespread emerging contaminants and, like all pollutants, are present in combination with others in the ecosystems. The aim of the present work was to evaluate the toxic response of the crustacean Daphnia magna exposed to individual and combined pharmaceuticals. Fluoxetine, a selective serotonin re-uptake inhibitor widely prescribed as antidepressant, and propranolol, a non-selective β-adrenergic receptor-blocking agent used to treat hypertension, were tested. Several experimental trials of an acute immobilization test and a chronic reproduction test were performed. Single chemicals were first tested separately. Toxicity of binary mixtures was then assessed using a fixed ratio experimental design. Five concentrations and 5 percentages of each substance in the mixture (0, 25, 50, 75, and 100%) were tested. The MIXTOX model was applied to analyze the experimental results. This tool is a stepwise statistical procedure that evaluates if and how observed data deviate from a reference model, either concentration addition (CA) or independent action (IA), and provides significance testing for synergism, antagonism, or more complex interactions. Acute EC50 values ranged from 6.4 to 7.8 mg/L for propranolol and from 6.4 to 9.1 mg/L for fluoxetine. Chronic EC50 values ranged from 0.59 to 1.00 mg/L for propranolol and from 0.23 to 0.24 mg/L for fluoxetine. Results showed a significant antagonism between chemicals in both the acute and the chronic mixture tests when CA was adopted as the reference model, while absence of interactive effects when IA was used.

Metabolomics reveals energetic impairments in Daphnia magna exposed to diazinon, malathion and bisphenol-A

International Nuclear Information System (INIS)

Nagato, Edward G.; Simpson, André J.; Simpson, Myrna J.

2016-01-01

Highlights: • Metabolomics detected shifts with sub-lethal exposure to contaminants. • Diazinon and malathion induced comparable, non-linear responses. • Bisphenol-A resulted in energy impairment. • Overall, insight into sub-lethal toxicity was garnered using NMR-based metabolomics. - Abstract: "1H nuclear magnetic resonance (NMR)-based metabolomics was used to study the response of Daphnia magna to increasing sub-lethal concentrations of either an organophosphate (diazinon or malathion) or bisphenol-A (BPA). Principal component analysis (PCA) of "1H NMR spectra were used to screen metabolome changes after 48 h of contaminant exposure. The PCA scores plots showed that diazinon exposures resulted in aberrant metabolomic profiles at all exposure concentrations tested (0.009–0.135 μg/L), while for malathion the second lowest (0.08 μg/L) and two highest exposure concentrations (0.32 μg/L and 0.47 μg/L) caused significant shifts from the control. Individual metabolite changes for both organophosphates indicated that the response to increasing exposure was non-linear and described perturbations in the metabolome that were characteristic of the severity of exposure. For example, intermediate concentrations of diazinon (0.045 μg/L and 0.09 μg/L) and malathion (0.08 μg/L) elicited a decrease in amino acids such as leucine, valine, arginine, glycine, lysine, glutamate, glutamine, phenylalanine and tyrosine, with concurrent increases in glucose and lactate, suggesting a mobilization of energy resources to combat stress. At the highest exposure concentrations for both organophosphates there was evidence of a cessation in metabolic activity, where the same amino acids increased and glucose and lactate decreased, suggesting a slowdown in protein synthesis and depletion of energy stocks. This demonstrated a similar response in the metabolome between two organophosphates but also that intermediate and severe stress levels could be differentiated by changes in the

Automatic modulation recognition of communication signals

CERN Document Server

Azzouz, Elsayed Elsayed

1996-01-01

Automatic modulation recognition is a rapidly evolving area of signal analysis. In recent years, interest from the academic and military research institutes has focused around the research and development of modulation recognition algorithms. Any communication intelligence (COMINT) system comprises three main blocks: receiver front-end, modulation recogniser and output stage. Considerable work has been done in the area of receiver front-ends. The work at the output stage is concerned with information extraction, recording and exploitation and begins with signal demodulation, that requires accurate knowledge about the signal modulation type. There are, however, two main reasons for knowing the current modulation type of a signal; to preserve the signal information content and to decide upon the suitable counter action, such as jamming. Automatic Modulation Recognition of Communications Signals describes in depth this modulation recognition process. Drawing on several years of research, the authors provide a cr...

The Effects of Natural and Anthropogenic Microparticles on Individual Fitness in Daphnia magna.

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Martin Ogonowski

Full Text Available Concerns are being raised that microplastic pollution can have detrimental effects on the feeding of aquatic invertebrates, including zooplankton. Both small plastic fragments (microplastics, MPs produced by degradation of larger plastic waste (secondary MPs; SMPs and microscopic plastic spheres used in cosmetic products and industry (primary MPs; PMPs are ubiquitously present in the environment. However, despite the fact that most environmental MPs consist of weathered plastic debris with irregular shape and broad size distribution, experimental studies of organism responses to MP exposure have largely used uniformly sized spherical PMPs. Therefore, effects observed for PMPs in such experiments may not be representative for MP-effects in situ. Moreover, invertebrate filter-feeders are generally well adapted to the presence of refractory material in seston, which questions the potential of MPs at environmentally relevant concentrations to measurably affect digestion in these organisms. Here, we compared responses to MPs (PMPs and SMPs and naturally occurring particles (kaolin clay using the cladoceran Daphnia magna as a model organism. We manipulated food levels (0.4 and 9 μg C mL-1 and MP or kaolin contribution to the feeding suspension (<1 to 74% and evaluated effects of MPs and kaolin on food uptake, growth, reproductive capacity of the daphnids, and maternal effects on offspring survival and feeding. Exposure to SMPs caused elevated mortality, increased inter-brood period and decreased reproduction albeit only at high MP levels in the feeding suspension (74% by particle count. No such effects were observed in either PMP or kaolin treatments. In daphnids exposed to any particle type at the low algal concentration, individual growth decreased by ~15%. By contrast, positive growth response to all particle types was observed at the high algal concentration with 17%, 54% and 40% increase for kaolin, PMP and SMP, respectively. When test particles

Modulation of the mirror system by social relevance.

Science.gov (United States)

Kilner, James M; Marchant, Jennifer L; Frith, Chris D

2006-09-01

When we observe the actions of others, certain areas of the brain are activated in a similar manner as to when we perform the same actions ourselves. This 'mirror system' includes areas in the ventral premotor cortex and the inferior parietal lobule. Experimental studies suggest that action observation automatically elicits activity in the observer, which precisely mirrors the activity observed. In this case we would expect this activity to be independent of observer's viewpoint. Here we use whole-head magnetoencephalography (MEG) to record cortical activity of human subjects whilst they watched a series of videos of an actor making a movement recorded from different viewpoints. We show that one cortical response to action observation (oscillatory activity in the 7-12 Hz frequency range) is modulated by the relationship between the observer and the actor. We suggest that this modulation reflects a mechanism that filters information into the 'mirror system', allowing only socially relevant information to pass.

Classification of actions of discrete Kac algebras on injective factors

CERN Document Server

Masuda, Toshihiko

2017-01-01

The authors study two kinds of actions of a discrete amenable Kac algebra. The first one is an action whose modular part is normal. They construct a new invariant which generalizes a characteristic invariant for a discrete group action, and we will present a complete classification. The second is a centrally free action. By constructing a Rohlin tower in an asymptotic centralizer, the authors show that the Connes-Takesaki module is a complete invariant.

RIBE at an inter-organismic level: A study on genotoxic effects in Daphnia magna exposed to waterborne uranium and a uranium mine effluent.

Science.gov (United States)

Reis, P; Lourenço, J; Carvalho, F P; Oliveira, J; Malta, M; Mendo, S; Pereira, R

2018-05-01

The induction of RIBE (Radiation Induced Bystander Effect) is a non-target effect of low radiation doses that has already been verified at an inter-organismic level in fish and small mammals. Although the theoretical impact in the field of environmental risk assessment (ERA) is possible, there is a gap of knowledge regarding this phenomenon in invertebrate groups and following environmentally relevant exposures. To understand if RIBE should be considered for ERA of radionuclide-rich wastewaters, we exposed Daphnia magna (uranium mine effluent for 48 h, and to a matching dose of waterborne uranium (55.3 μg L -1 ). Then the exposed organisms were placed (24 and 48 h) in a clean medium together with non-exposed neonates. The DNA damage observed for the non-exposed organisms was statistically significant after the 24 h cohabitation for both uranium (neonates p = 0.002; 5 d-old daphnids p = uranium mine effluent exposure (only for neonates p = 0.042). After 48 h cohabitation significant results were obtained only for uranium exposure (neonates p = 0.017; 5 d-old daphnids p = 0.013). Although there may be some variability associated to age and exposure duration, the significant DNA damage detected in non-exposed organisms clearly reveals the occurrence of RIBE in D. magna. The data obtained and here presented are a valuable contribution for the discussion about the relevance of RIBE for environmental risk assessment. Copyright © 2018 Elsevier B.V. All rights reserved.

Strain difference in sensitivity to 3,4-dichloroaniline and insect growth regulator, fenoxycarb, in Daphnia magna

DEFF Research Database (Denmark)

Oda, S.; Tatarazako, N.; Dorgerloh, M

2007-01-01

Acute and reproductive toxicity tests were conducted on seven strains of Daphnia magna from six laboratories in five countries. 3,4-Dichloroaniline (DCA) and fenoxycarb were used as test chemicals. Acute toxicity tests revealed that estimated EC50 (50% effective concentration) values for DCA varied...... by a factor of 2.1 among strains (310-640 mu g/L), whereas the EC50 values for fenoxycarb varied by a factor of 4 (210-860 mu g/L). EC50 values for reproductive toxicity tests with DCA ranged from 5.9 to 38 mu g/L among strains. Fenoxycarb exposure induced the production of male neonates in all the strains...... used in the present study. Estimated EC50 values for the induction of male offspring were highly variable among strains: sensitivity to fenoxycarb differed by a factor of approximately 23 overall (0.45-10 mu g/L). The present pre-validation tests suggest that induction of male sex in neonates...

A DUPLICATED GREAT SAPHENOUS VEIN AND CLINICAL SIGNIFICANCE FOR VARICOSITY. Duplicación de la vena safena magna y significado clínico de las várices

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Waseem Al Talalwah

2016-03-01

Full Text Available En varios estudios se ha relacionado la vena safena magna doble con dilataciones varicosas. Durante una clase de disección de pre-grado de la extremidad inferior se encontró una doble vena safena magna unilateral en el miembro inferior izquierdo de un cadáver masculino. La incidencia de esta variación fue del 1,3% de todos los especímenes muestra. En este trabajo se reporta la variabilidad del drenaje venoso de las extremidades inferiores para mejorar la conciencia para los radiólogos vasculares y proporcionar además una opción adicional en la cirugía de bypass de la arteria coronaria para evitar las várices iatrogénicas. A double great saphenous vein has been associated with varicosity in a number of studies. During routine undergraduate dissection of the lower limb a unilateral double great saphenous was found in the left lower limb of a male cadaver. The incidence of this variation was 1.3% of all specimens. This paper reports the variability of lower limb venous drainage to increase the awareness for vascular radiologists and provide further an additional option in coronary artery bypass surgery to avoid iatrogenic varicosity.

A taste of plastic - quantifying micro- and nanoplastic ingestion and interactions with feeding in daphnia magna (E)

DEFF Research Database (Denmark)

Rist, Sinja; Baun, Anders; Hartmann, Nanna B.

Aquatic ecosystems worldwide are polluted by microplastics and they are ingested by a broad range of organisms. Although research so far mainly focused on marine ecosystems, freshwater organisms are just as affected. Approaches to study microplastic ingestion are predominantly qualitative since...... exposed to a particle concentration of 1 mg/l for 24 h (uptake) and thereafter transferred to clean medium for another 24 h (depuration). During both phases animals were sampled and particle body burdens were determined by measuring particle fluorescence in the dissolved tissue. To analyze the influence...... of particle size, the study was done with beads of 2 µm and 100 nm. It was furthermore analyzed how the processes are affected by food availability and how the particles in turn affect the feeding rate of D. magna. Both particle sizes were readily taken up and body burdens increased with exposure time. The 2...

On the influence of reward on action-effect binding

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Paul Simon Muhle-Karbe

2012-11-01

Full Text Available Ideomotor theory states that the formation of anticipatory representations about the perceptual consequences of an action (i.e. action-effect (A-E binding provides the functional basis of voluntary action control. A host of studies has demonstrated that A-E binding occurs fast and effortlessly, yet only little is known about cognitive and affective factors that influence this learning process. In the present study, we sought to test whether the motivational value of an action modulates the acquisition of A-E associations. To this end, we associated specific actions with monetary incentives during the acquisition of novel A-E mappings. In a subsequent test phase, the degree of binding was assessed by presenting the former effect stimuli as task-irrelevant response primes in a forced-choice response task in the absence of any reward. Binding, as indexed by response priming through the former action effects, was only found for reward-related A-E mappings. Moreover, the degree to which reward associations modulated the binding strength was predicted by individuals’ trait sensitivity to reward. These observations indicate that the association of actions and their immediate outcomes depends on the motivational value of the action during learning, as well as on the motivational disposition of the individual. On a larger scale, these findings also highlight the link between ideomotor theories and reinforcement-learning theories, providing an interesting perspective for future research on anticipatory regulation of behavior.

Titanium dioxide nanoparticles increase sensitivity in the next generation of the water flea Daphnia magna.

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Mirco Bundschuh

Full Text Available The nanoparticle industry is expected to become a trillion dollar business in the near future. Therefore, the unintentional introduction of nanoparticles into the environment is increasingly likely. However, currently applied risk-assessment practices require further adaptation to accommodate the intrinsic nature of engineered nanoparticles. Combining a chronic flow-through exposure system with subsequent acute toxicity tests for the standard test organism Daphnia magna, we found that juvenile offspring of adults that were previously exposed to titanium dioxide nanoparticles exhibit a significantly increased sensitivity to titanium dioxide nanoparticles compared with the offspring of unexposed adults, as displayed by lower 96 h-EC(50 values. This observation is particularly remarkable because adults exhibited no differences among treatments in terms of typically assessed endpoints, such as sensitivity, number of offspring, or energy reserves. Hence, the present study suggests that ecotoxicological research requires further development to include the assessment of the environmental risks of nanoparticles for the next and hence not directly exposed generation, which is currently not included in standard test protocols.

Botanical modulation of menopausal symptoms: Mechanisms of action?

Science.gov (United States)

Hajirahimkhan, Atieh; Dietz, Birgit M.; Bolton, Judy L.

2013-01-01

Menopausal women suffer from a variety of symptoms, including hot flashes and night sweats which can affect quality of life. Although hormone therapy (HT) has been the treatment of choice for relieving these symptoms, HT has been associated with increased breast cancer risk leading many women to search for natural, efficacious, and safe alternatives such as botanical supplements. Data from clinical trials suggesting that botanicals have efficacy for menopausal symptom relief, have been controversial and several mechanisms of action have been proposed including estrogenic, progestogenic, and serotonergic pathways. Plant extracts with potential estrogenic activities include soy, red clover, kudzu, hops, licorice, rhubarb, yam, and chasteberry. Botanicals with reported progestogenic activities are red clover, hops, yam, and chasteberry. Serotonergic mechanisms have also been proposed since women taking antidepressants often report reduction in hot flashes and night sweats. Black cohosh, kudzu, kava, licorice, and dong quai all either have reported 5-HT7 ligands or inhibit serotonin re-uptake, therefore have potential serotonergic activities. Understanding the mechanisms of action of these natural remedies used for women’s health, could lead to more efficacious formulations and to the isolation of active components which have the potential of becoming effective medications in the future. PMID:23408273

Intracellular Diagnostics: Hunting for the Mode of Action of Redox-Modulating Selenium Compounds in Selected Model Systems

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Dominika Mániková

2014-08-01

Full Text Available Redox-modulating compounds derived from natural sources, such as redox active secondary metabolites, are currently of considerable interest in the field of chemoprevention, drug and phytoprotectant development. Unfortunately, the exact and occasionally even selective activity of such products, and the underlying (bio-chemical causes thereof, are often only poorly understood. A combination of the nematode- and yeast-based assays provides a powerful platform to investigate a possible biological activity of a new compound and also to explore the “redox link” which may exist between its activity on the one side and its chemistry on the other. Here, we will demonstrate the usefulness of this platform for screening several selenium and tellurium compounds for their activity and action. We will also show how the nematode-based assay can be used to obtain information on compound uptake and distribution inside a multicellular organism, whilst the yeast-based system can be employed to explore possible intracellular mechanisms via chemogenetic screening and intracellular diagnostics. Whilst none of these simple and easy-to-use assays can ultimately substitute for in-depth studies in human cells and animals, these methods nonetheless provide a first glimpse on the possible biological activities of new compounds and offer direction for more complicated future investigations. They may also uncover some rather unpleasant biochemical actions of certain compounds, such as the ability of the trace element supplement selenite to induce DNA strand breaks.

Toxicity assessment of polluted sediments using swimming behavior alteration test with Daphnia magna

Science.gov (United States)

Nikitin, O. V.; Nasyrova, E. I.; Nuriakhmetova, V. R.; Stepanova, N. Yu; Danilova, N. V.; Latypova, V. Z.

2018-01-01

Recently behavioral responses of organisms are increasingly used as a reliable and sensitive tool in aquatic toxicology. Behavior-related endpoints allow efficiently studying the effects of sub-lethal exposure to contaminants. At present behavioural parameters frequently are determined with the use of digital analysis of video recording by computer vision technology. However, most studies evaluate the toxicity of aqueous solutions. Due to methodological difficulties associated with sample preparation not a lot of examples of the studies related to the assessment of toxicity of other environmental objects (wastes, sewage sludges, soils, sediments etc.) by computer vision technology. This paper presents the results of assessment of the swimming behavior alterations of Daphnia magna in elutriates from both uncontaminated natural and artificially chromium-contaminated bottom sediments. It was shown, that in elutriate from chromium contaminated bottom sediments (chromium concentration 115±5.7 μg l-1) the swimming speed of daphnids was decreases from 0.61 cm s-1 (median speed over the period) to 0.50 cm s-1 (median speed at the last minute of the experiment). The relocation of Daphnia from the culture medium to the extract from the non-polluted sediments does not essential changes the swimming activity.

Longitudinal density modulation and energy conversion in intense beams

International Nuclear Information System (INIS)

Harris, J. R.; Neumann, J. G.; Tian, K.; O'Shea, P. G.

2007-01-01

Density modulation of charged particle beams may occur as a consequence of deliberate action, or may occur inadvertently because of imperfections in the particle source or acceleration method. In the case of intense beams, where space charge and external focusing govern the beam dynamics, density modulation may, under some circumstances, be converted to velocity modulation, with a corresponding conversion of potential energy to kinetic energy. Whether this will occur depends on the properties of the beam and the initial modulation. This paper describes the evolution of discrete and continuous density modulations on intense beams and discusses three recent experiments related to the dynamics of density-modulated electron beams

Review on the acute Daphnia magna toxicity test – Evaluation of the sensitivity and the precision of assays performed with organisms from laboratory cultures or hatched from dormant eggs

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Persoone G.

2009-08-01

“Culture/maintenance free” aquatic microbiotests with species of different phylogenetic groups were developed in the early 1990s at the Laboratory for Environmental Toxicology and Aquatic Ecology at the Ghent University in Belgium. These assays which were given the generic name “Toxkits”, are unique in that they employ dormant stages (“cryptobiotic eggs” of the test species, which can be stored for long periods of time and “hatched” at the time of performance of the assays. One of these microbiotests is the Daphtoxkit F magna, which is currently used in many laboratories worldwide for research as well as for toxicity monitoring purposes. The microbiotest technology has several advantages in comparison to the “traditional” tests based on laboratory cultures, especially its independence of the stock culturing burden. However, the acceptance (or possible non-acceptance of performing assays with test organisms obtained from “dormant eggs” should be clearly dictated by the “sensitivity” and “precision” criteria of the former assays in comparison to the latter. The first part of this review therefore thoroughly reviews the scientific literature and of data obtained from various laboratories for assays performed with either D. magna test organisms obtained from lab cultures or hatched from dormant eggs. Attention has focused on data of quality control tests performed on reference chemicals, and in particular on potassium dichromate (K2Cr2O7 for which an acceptability range of 0.6–2.1 mg·L–1 has been set in ISO standard 6341 for the 24 h EC50 of the acute D. magna assay. Mean EC50s, standard deviations and variation coefficients were calculated from the collected data, all of which are presented in tables and figures and discussed in detail. The major conclusions drawn from the analysis of the large number of quality control (QC data on the acute D. magna toxicity test are that : (1 Virtually all results from assays performed with

76 FR 8345 - Endangered and Threatened Species; Recovery Plan Module for Columbia River Estuary Salmon and...

Science.gov (United States)

2011-02-14

... and Threatened Species; Recovery Plan Module for Columbia River Estuary Salmon and Steelhead AGENCY.... ACTION: Notice of availability; recovery plan module for Columbia River estuary salmon and steelhead... Plan Module for Salmon and Steelhead (Estuary Module). The Estuary Module addresses the estuary...

Metabolomics reveals energetic impairments in Daphnia magna exposed to diazinon, malathion and bisphenol-A

Energy Technology Data Exchange (ETDEWEB)

Nagato, Edward G.; Simpson, André J.; Simpson, Myrna J., E-mail: myrna.simpson@utoronto.ca

2016-01-15

Highlights: • Metabolomics detected shifts with sub-lethal exposure to contaminants. • Diazinon and malathion induced comparable, non-linear responses. • Bisphenol-A resulted in energy impairment. • Overall, insight into sub-lethal toxicity was garnered using NMR-based metabolomics. - Abstract: {sup 1}H nuclear magnetic resonance (NMR)-based metabolomics was used to study the response of Daphnia magna to increasing sub-lethal concentrations of either an organophosphate (diazinon or malathion) or bisphenol-A (BPA). Principal component analysis (PCA) of {sup 1}H NMR spectra were used to screen metabolome changes after 48 h of contaminant exposure. The PCA scores plots showed that diazinon exposures resulted in aberrant metabolomic profiles at all exposure concentrations tested (0.009–0.135 μg/L), while for malathion the second lowest (0.08 μg/L) and two highest exposure concentrations (0.32 μg/L and 0.47 μg/L) caused significant shifts from the control. Individual metabolite changes for both organophosphates indicated that the response to increasing exposure was non-linear and described perturbations in the metabolome that were characteristic of the severity of exposure. For example, intermediate concentrations of diazinon (0.045 μg/L and 0.09 μg/L) and malathion (0.08 μg/L) elicited a decrease in amino acids such as leucine, valine, arginine, glycine, lysine, glutamate, glutamine, phenylalanine and tyrosine, with concurrent increases in glucose and lactate, suggesting a mobilization of energy resources to combat stress. At the highest exposure concentrations for both organophosphates there was evidence of a cessation in metabolic activity, where the same amino acids increased and glucose and lactate decreased, suggesting a slowdown in protein synthesis and depletion of energy stocks. This demonstrated a similar response in the metabolome between two organophosphates but also that intermediate and severe stress levels could be differentiated by

Responses of alkaline phosphatase activity to phosphorus stress in Daphnia magna.

Science.gov (United States)

McCarthy, S D S; Rafferty, S P; Frost, P C

2010-01-15

We examined how alkaline phosphatase (AP) activity within the bodies and in the materials released by the crustacean Daphnia magna responds to variable algal food phosphorus (P)-content. We found that Daphnia eating P-poor food (C:P approximately 700) had significantly higher AP activity in their bodies on a mass-specific basis compared with individuals eating P-rich food (C:P approximately 100). This dietary P effect on AP activity was not altered by Daphnia starvation but was partially related to differences in the P concentration of animal body homogenates. By contrast, poor P-nutrition of Daphnia lowered AP activity in released materials compared with that measured from their P-sufficient conspecifics. Moreover, AP activity in Daphnia release was lowest in animals consuming P-poor food for longer time periods. Our results support the hypothesis that AP activity increases inside P-limited Daphnia as a mechanism to increase P-acquisition and retention from ingested algae in these nutritionally stressed animals. The lower level of AP activity present in the water of P-deprived animals could reflect a change from largely free to membrane-bound AP isotypes in the digestive tracts of P-starved animals or a decrease in the shedding of membrane-anchored AP from their intestinal lining. These results supplement accumulating evidence that P-poor algal food reduces the dietary mineral P available to Daphnia. In addition, animal body AP activity measurements, with some refinement, may prove useful as an in situ indicator of P-stress in aquatic consumers.

Prediction Error During Functional and Non-Functional Action Sequences

DEFF Research Database (Denmark)

Nielbo, Kristoffer Laigaard; Sørensen, Jesper

2013-01-01

recurrent networks were made and the results are presented in this article. The simulations show that non-functional action sequences do indeed increase prediction error, but that context representations, such as abstract goal information, can modulate the error signal considerably. It is also shown...... that the networks are sensitive to boundaries between sequences in both functional and non-functional actions....

Action of exogenous oxytocin on stress modulation in crossbred Red Angus cows

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Janne Paula Neres de Barros

2016-10-01

Full Text Available Cattle (Bos taurus and Bos indicus are organised on the basis of leadership and dominance in such a manner that a disturbance by an external stressor causes negative effects on their health, productivity, well-being, and behaviour. One of these effects is the excessive release of glucocorticoids, which results in increased alertness. We evaluated the action of exogenous oxytocin (OT on serum cortisol levels in crossbred Red Angus heifers. Twelve Red Angus crossbred heifers were moved daily from the pasture to the corral in weeks 1 and 2 for adaptation to human contact and handling in the cattle crush. In weeks 3 and 4, they were divided into two groups of six (T1 and T2. The T1 group was administered 20 IU (2 mL of OT via intramuscular injection and the T2 group was administered 2 mL of saline solution 0.85% (SS. In weeks 5 and 6, they were only contained in the cattle crush for evaluation. On days 01, 07, 14, 21, 28, 35, and 42, blood samples were collected by jugular venepuncture in vacuum tubes without anticoagulants. Then, serum cortisol levels were measured using a radioimmunoassay. In the period of adaptation, during weeks 1 and 2, serum cortisol levels decreased in both the groups, with higher levels in the SS group; the same result was obtained in weeks 5 and 6. During treatment, however, there was a significant difference between the two groups in week 4, with a reduction in cortisol levels in the OT group. This result suggests a modulator effect of OT on neuroendocrine response to stress.

Environmental sex determination in the branchiopod crustacean Daphnia magna: deep conservation of a Doublesex gene in the sex-determining pathway.

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Yasuhiko Kato

2011-03-01

Full Text Available Sex-determining mechanisms are diverse among animal lineages and can be broadly divided into two major categories: genetic and environmental. In contrast to genetic sex determination (GSD, little is known about the molecular mechanisms underlying environmental sex determination (ESD. The Doublesex (Dsx genes play an important role in controlling sexual dimorphism in genetic sex-determining organisms such as nematodes, insects, and vertebrates. Here we report the identification of two Dsx genes from Daphnia magna, a freshwater branchiopod crustacean that parthenogenetically produces males in response to environmental cues. One of these genes, designated DapmaDsx1, is responsible for the male trait development when expressed during environmental sex determination. The domain organization of DapmaDsx1 was similar to that of Dsx from insects, which are thought to be the sister group of branchiopod crustaceans. Intriguingly, the molecular basis for sexually dimorphic expression of DapmaDsx1 is different from that of insects. Rather than being regulated sex-specifically at the level of pre-mRNA splicing in the coding region, DapmaDsx1 exhibits sexually dimorphic differences in the abundance of its transcripts. During embryogenesis, expression of DapmaDsx1 was increased only in males and its transcripts were primarily detected in male-specific structures. Knock-down of DapmaDsx1 in male embryos resulted in the production of female traits including ovarian maturation, whereas ectopic expression of DapmaDsx1 in female embryos resulted in the development of male-like phenotypes. Expression patterns of another D. magna Dsx gene, DapmaDsx2, were similar to those of DapmaDsx1, but silencing and overexpression of this gene did not induce any clear phenotypic changes. These results establish DapmaDsx1 as a key regulator of the male phenotype. Our findings reveal how ESD is implemented by selective expression of a fundamental genetic component that is

Intracellular calcium modulation of voltage-gated sodium channels in ventricular myocytes

NARCIS (Netherlands)

Casini, Simona; Verkerk, Arie O.; van Borren, Marcel M. G. J.; van Ginneken, Antoni C. G.; Veldkamp, Marieke W.; de Bakker, Jacques M. T.; Tan, Hanno L.

2009-01-01

AIMS: Cardiac voltage-gated sodium channels control action potential (AP) upstroke and cell excitability. Intracellular calcium (Ca(i)(2+)) regulates AP properties by modulating various ion channels. Whether Ca(i)(2+) modulates sodium channels in ventricular myocytes, is unresolved. We studied

Arsenic Trioxide Modulates the Central Snail Neuron Action Potential

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Guan-Ling Lu

2009-09-01

Conclusion: As2O3 at 10 mM elicits BoPs in central snail neurons and this effect may relate to the PLC activity of the neuron, rather than protein kinase A activity, or calcium influxes of the neuron. As2O3 at higher concentration irreversibly abolishes the spontaneous action potentials of the neuron.

P3-10: Crossmodal Perceptual Grouping Modulates Subjective Causality between Action and Outcome

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Takahiro Kawabe

2012-10-01

Full Text Available Agents have to determine which external events their action has causally produced. A sensation of causal relation between action and outcome is called subjective causality. Subjective causality has been linked to the comparator model. This model assumes that the brain compares an internal prediction for action outcome with an actual sensory outcome, distinguishing between self and externally produced outcomes depending on spatiotemporal congruency. However, recent studies have expressed some doubt about the idea that subjective causality arises depending solely on the spatiotemporal congruency, suggesting instead that other perceptual/cognitive factors play a critical role in determining subjective causality. We hypothesized that crossmodal grouping between action and outcome contributed to subjective causality. Crossmodal temporal grouping is an essential factor for crossmodal simultaneity judgments with ungrouped crossmodal signals likely to be judged as non-simultaneous. We predicted that subjective causality would decrease when an agent's action was not temporally grouped with action outcome. In the experiment, observers were asked to press a key in order to trigger a display change with some temporal delay. To disrupt temporal grouping between action and outcome, a task-irrelevant visual flash or tone was sometimes presented synchronously with the button press and/or the display change. Subjective causality was decreased when the flash or the tone was coincided with the button press. This demonstrates that perceptual grouping has a key role in determination of subjective causality, a result that is not accounted for by the standard comparator model.

Effects of 4-nonylphenol, fish predation and food availability on survival and life history traits of Daphnia magna straus.

Science.gov (United States)

Beklioglu, Meryem; Banu Akkas, S; Elif Ozcan, H; Bezirci, Gizem; Togan, Inci

2010-06-01

This study aimed to investigate the compound effect of environmentally relevant 4-nonylphenol (NP) concentrations and natural stressors-namely fish predation and food availability-on Daphnia magna, which were exposed to four NP concentrations (0, 1, 5 and 10 microg l(-1)) under optimum or low food concentrations (1.00 and 0.075 mg C l(-1), respectively) in water (un)conditioned by a fish predator (Alburnus alburnus). A(n) "environmentally relevant" and "no observable effect" concentration (NOEC) of NP (10 microg l(-1)) resulted in a significant reduction (P ecosystems. The deterioration of the life-history traits-namely, NP-induced delay in the age at first reproduction (P ecosystems. The results of this study demonstrate the importance of taking into account environmentally realistic conditions while investigating the effects of NOEC levels of toxicants on non-target aquatic species.

Location estimation of approaching objects is modulated by the observer's inherent and momentary action capabilities

NARCIS (Netherlands)

Kandula, Manasa; Hofman, Dennis; Dijkerman, H Chris

2016-01-01

Action capability may be one of the factors that can influence our percept of the world. A distinction can be made between momentary action capability (action capability at that particular moment) and inherent action capability (representing a stable action capability). In the current study, we

Comprehending Sentences with the Body: Action Compatibility in British Sign Language?

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Vinson, David; Perniss, Pamela; Fox, Neil; Vigliocco, Gabriella

2017-01-01

Previous studies show that reading sentences about actions leads to specific motor activity associated with actually performing those actions. We investigate how sign language input may modulate motor activation, using British Sign Language (BSL) sentences, some of which explicitly encode direction of motion, versus written English, where motion…

When action meets emotions: how facial displays of emotion influence goal-related behavior.

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Francesca Ferri

Full Text Available Many authors have proposed that facial expressions, by conveying emotional states of the person we are interacting with, influence the interaction behavior. We aimed at verifying how specific the effect is of the facial expressions of emotions of an individual (both their valence and relevance/specificity for the purpose of the action with respect to how the action aimed at the same individual is executed. In addition, we investigated whether and how the effects of emotions on action execution are modulated by participants' empathic attitudes. We used a kinematic approach to analyze the simulation of feeding others, which consisted of recording the "feeding trajectory" by using a computer mouse. Actors could express different highly arousing emotions, namely happiness, disgust, anger, or a neutral expression. Response time was sensitive to the interaction between valence and relevance/specificity of emotion: disgust caused faster response. In addition, happiness induced slower feeding time and longer time to peak velocity, but only in blocks where it alternated with expressions of disgust. The kinematic profiles described how the effect of the specificity of the emotional context for feeding, namely a modulation of accuracy requirements, occurs. An early acceleration in kinematic relative-to-neutral feeding profiles occurred when actors expressed positive emotions (happiness in blocks with specific-to-feeding negative emotions (disgust. On the other hand, the end-part of the action was slower when feeding happy with respect to neutral faces, confirming the increase of accuracy requirements and motor control. These kinematic effects were modulated by participants' empathic attitudes. In conclusion, the social dimension of emotions, that is, their ability to modulate others' action planning/execution, strictly depends on their relevance and specificity to the purpose of the action. This finding argues against a strict distinction between social

When action meets emotions: how facial displays of emotion influence goal-related behavior.

Science.gov (United States)

Ferri, Francesca; Stoianov, Ivilin Peev; Gianelli, Claudia; D'Amico, Luigi; Borghi, Anna M; Gallese, Vittorio

2010-10-01

Many authors have proposed that facial expressions, by conveying emotional states of the person we are interacting with, influence the interaction behavior. We aimed at verifying how specific the effect is of the facial expressions of emotions of an individual (both their valence and relevance/specificity for the purpose of the action) with respect to how the action aimed at the same individual is executed. In addition, we investigated whether and how the effects of emotions on action execution are modulated by participants' empathic attitudes. We used a kinematic approach to analyze the simulation of feeding others, which consisted of recording the "feeding trajectory" by using a computer mouse. Actors could express different highly arousing emotions, namely happiness, disgust, anger, or a neutral expression. Response time was sensitive to the interaction between valence and relevance/specificity of emotion: disgust caused faster response. In addition, happiness induced slower feeding time and longer time to peak velocity, but only in blocks where it alternated with expressions of disgust. The kinematic profiles described how the effect of the specificity of the emotional context for feeding, namely a modulation of accuracy requirements, occurs. An early acceleration in kinematic relative-to-neutral feeding profiles occurred when actors expressed positive emotions (happiness) in blocks with specific-to-feeding negative emotions (disgust). On the other hand, the end-part of the action was slower when feeding happy with respect to neutral faces, confirming the increase of accuracy requirements and motor control. These kinematic effects were modulated by participants' empathic attitudes. In conclusion, the social dimension of emotions, that is, their ability to modulate others' action planning/execution, strictly depends on their relevance and specificity to the purpose of the action. This finding argues against a strict distinction between social and nonsocial

Parallel processing streams for motor output and sensory prediction during action preparation.

Science.gov (United States)

Stenner, Max-Philipp; Bauer, Markus; Heinze, Hans-Jochen; Haggard, Patrick; Dolan, Raymond J

2015-03-15

Sensory consequences of one's own actions are perceived as less intense than identical, externally generated stimuli. This is generally taken as evidence for sensory prediction of action consequences. Accordingly, recent theoretical models explain this attenuation by an anticipatory modulation of sensory processing prior to stimulus onset (Roussel et al. 2013) or even action execution (Brown et al. 2013). Experimentally, prestimulus changes that occur in anticipation of self-generated sensations are difficult to disentangle from more general effects of stimulus expectation, attention and task load (performing an action). Here, we show that an established manipulation of subjective agency over a stimulus leads to a predictive modulation in sensory cortex that is independent of these factors. We recorded magnetoencephalography while subjects performed a simple action with either hand and judged the loudness of a tone caused by the action. Effector selection was manipulated by subliminal motor priming. Compatible priming is known to enhance a subjective experience of agency over a consequent stimulus (Chambon and Haggard 2012). In line with this effect on subjective agency, we found stronger sensory attenuation when the action that caused the tone was compatibly primed. This perceptual effect was reflected in a transient phase-locked signal in auditory cortex before stimulus onset and motor execution. Interestingly, this sensory signal emerged at a time when the hemispheric lateralization of motor signals in M1 indicated ongoing effector selection. Our findings confirm theoretical predictions of a sensory modulation prior to self-generated sensations and support the idea that a sensory prediction is generated in parallel to motor output (Walsh and Haggard 2010), before an efference copy becomes available. Copyright © 2015 the American Physiological Society.

Culture-specific familiarity equally mediates action representations across cultures.

Science.gov (United States)

Umla-Runge, Katja; Fu, Xiaolan; Wang, Lamei; Zimmer, Hubert D

2014-01-01

Previous studies have shown that we need to distinguish between means and end information about actions. It is unclear how these two subtypes of action information relate to each other with theoretical accounts postulating the superiority of end over means information and others linking separate means and end routes of processing to actions of differential meaningfulness. Action meaningfulness or familiarity differs between cultures. In a cross-cultural setting, we investigated how action familiarity influences recognition memory for means and end information. Object directed actions of differential familiarity were presented to Chinese and German participants. Action familiarity modulated the representation of means and end information in both cultures in the same way, although the effects were based on different stimulus sets. Our results suggest that, in the representation of actions in memory, end information is superordinate to means information. This effect is independent of culture whereas action familiarity is not.

Translating visual information into action predictions: Statistical learning in action and nonaction contexts.

Science.gov (United States)

Monroy, Claire D; Gerson, Sarah A; Hunnius, Sabine

2018-05-01

Humans are sensitive to the statistical regularities in action sequences carried out by others. In the present eyetracking study, we investigated whether this sensitivity can support the prediction of upcoming actions when observing unfamiliar action sequences. In two between-subjects conditions, we examined whether observers would be more sensitive to statistical regularities in sequences performed by a human agent versus self-propelled 'ghost' events. Secondly, we investigated whether regularities are learned better when they are associated with contingent effects. Both implicit and explicit measures of learning were compared between agent and ghost conditions. Implicit learning was measured via predictive eye movements to upcoming actions or events, and explicit learning was measured via both uninstructed reproduction of the action sequences and verbal reports of the regularities. The findings revealed that participants, regardless of condition, readily learned the regularities and made correct predictive eye movements to upcoming events during online observation. However, different patterns of explicit-learning outcomes emerged following observation: Participants were most likely to re-create the sequence regularities and to verbally report them when they had observed an actor create a contingent effect. These results suggest that the shift from implicit predictions to explicit knowledge of what has been learned is facilitated when observers perceive another agent's actions and when these actions cause effects. These findings are discussed with respect to the potential role of the motor system in modulating how statistical regularities are learned and used to modify behavior.

Acute toxicity over Ceriodaphnia silvestrii and Daphnia magna: Bioassays with water samples from a dam under the influence of uranium mine and with manganese

Energy Technology Data Exchange (ETDEWEB)

Ferrari, Carla R.; Nascimento, Heliana de Azevedo Franco do; Silverio, Emilia Gabriela Costa; Bruschi, Armando Luis; Roque, Claudio Vitor; Nascimento, Marcos Roberto L.; Bonifacio, Rodrigo Leandro, E-mail: carlarolimferrari@yahoo.com.br, E-mail: hazevedo@cnen.gov.br, E-mail: emiliagcsilverio@hotmail.com, E-mail: abruschi@cnen.gov.br, E-mail: cvroque@cnen.gov.br, E-mail: pmarcos@cnen.gov.br, E-mail: rodrigo@cnen.gov.br [Comissao Nacional de Energia Nuclear (LAPOC/CNEN-MG), Pocos de Caldas, MG (Brazil). Laboratorio de Pocos de Caldas; Rodgher, Suzelei [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Sao Jose dos Campos, SP (Brazil). Dep. de Engenharia Ambiental

2015-07-01

Treated effluents from uranium mine with acid mine drainage can impact receiving water bodies. AMD is relevant from the environmental view due to the large volume of effluents generated, known to affect aquatic biota. Studies show that one of the main problems of treated effluents released by UTM/INB on the catchment basin of Ribeirao das Antas is associated to high Mn values in water samples. In this context, acute 48-h toxicity tests with Mn were conducted with Ceriodaphnia silvestrii and Daphnia magna to determine the No Observed Effect Concentration (NOEC) and the Observed Effect Concentration (OEC) in laboratory bioassays and to verify the potential toxicity of the Mn in face of concentrations found in water samples from the Antas Dam, which receives treated effluents from UTM/INB. In this study, preliminary results of acute toxicity for C. silvestrii indicated OEC values between 9.0 and 10.0 mg Mn/L and NOEC < 3.0 mg Mn/L. For D. magna, OEC and NOEC concentrations were ≥ 30 mg Mn/L and ≤ 80 mg Mn/L, respectively. It was verified that Mn concentrations determined in environmental samples registered the highest value at 1.75 mg Mn/L, below the OEC concentrations recorded for both species. Since manganese occurs in the composition of the effluent that may contain other stable and radioactive elements, complementary ecotoxicological tests must be conducted, aiming at the assessment of synergistic and antagonistic effects of the chemical mixture that makes up the radioactive effluents that are treated and released at the Antas Dam. Such bioassays are underway in the Radioecology Laboratory at LAPOC/CNEN. (author)

Acute toxicity over Ceriodaphnia silvestrii and Daphnia magna: Bioassays with water samples from a dam under the influence of uranium mine and with manganese

International Nuclear Information System (INIS)

Ferrari, Carla R.; Nascimento, Heliana de Azevedo Franco do; Silverio, Emilia Gabriela Costa; Bruschi, Armando Luis; Roque, Claudio Vitor; Nascimento, Marcos Roberto L.; Bonifacio, Rodrigo Leandro; Rodgher, Suzelei

2015-01-01

Treated effluents from uranium mine with acid mine drainage can impact receiving water bodies. AMD is relevant from the environmental view due to the large volume of effluents generated, known to affect aquatic biota. Studies show that one of the main problems of treated effluents released by UTM/INB on the catchment basin of Ribeirao das Antas is associated to high Mn values in water samples. In this context, acute 48-h toxicity tests with Mn were conducted with Ceriodaphnia silvestrii and Daphnia magna to determine the No Observed Effect Concentration (NOEC) and the Observed Effect Concentration (OEC) in laboratory bioassays and to verify the potential toxicity of the Mn in face of concentrations found in water samples from the Antas Dam, which receives treated effluents from UTM/INB. In this study, preliminary results of acute toxicity for C. silvestrii indicated OEC values between 9.0 and 10.0 mg Mn/L and NOEC < 3.0 mg Mn/L. For D. magna, OEC and NOEC concentrations were ≥ 30 mg Mn/L and ≤ 80 mg Mn/L, respectively. It was verified that Mn concentrations determined in environmental samples registered the highest value at 1.75 mg Mn/L, below the OEC concentrations recorded for both species. Since manganese occurs in the composition of the effluent that may contain other stable and radioactive elements, complementary ecotoxicological tests must be conducted, aiming at the assessment of synergistic and antagonistic effects of the chemical mixture that makes up the radioactive effluents that are treated and released at the Antas Dam. Such bioassays are underway in the Radioecology Laboratory at LAPOC/CNEN. (author)

Classification of solid industrial waste based on ecotoxicology tests using Daphnia magna: an alternative

Directory of Open Access Journals (Sweden)

William Gerson Matias

2005-11-01

Full Text Available The adequate treatment and final disposal of solid industrial wastes depends on their classification into class I or II. This classification is proposed by NBR 10.004; however, it is complex and time-consuming. With a view to facilitating this classification, the use of assays with Daphnia magna is proposed. These assays make possible the identification of toxic chemicals in the leach, which denotes the presence of one of the characteristics described by NBR 10.004, the toxicity, which is a sufficient argument to put the waste into class I. Ecotoxicological tests were carried out with ten samples of solid wastes of frequent production and, on the basis of the results from EC(I50/48h of those samples in comparison with the official classification of NBR 10.004, limits were established for the classification of wastes into class I or II. A coincidence in the classification of 50% of the analyzed samples was observed. In cases in which there is no coherence between the methods, the method proposed in this work classifies the waste into class I. These data are preliminary, but they reveal that the classification system proposed here is promising because of its quickness and economic viability.

Long-range crystalline order in spicules from the calcareous sponge Paraleucilla magna (Porifera, Calcarea).

Science.gov (United States)

Rossi, Andre L; Campos, Andrea P C; Barroso, Madalena M S; Klautau, Michelle; Archanjo, Bráulio S; Borojevic, Radovan; Farina, Marcos; Werckmann, Jacques

2014-09-01

We investigated the ultrastructure and crystallographic orientation of spicules from the calcareous sponge Paraleucilla magna (subclass Calcaronea) by transmission and scanning electron microscopy using two different methods of sample preparation: ultramicrotomy and focused ion beam (FIB). It was found that the unpaired actine from the spicules was oriented in the [211] zone axis. The plane that contains the unpaired actine and divides symmetrically the paired actines is the (-120). This plane is a mirror plane of the hexagonal lattice system. All the spicule types analyzed presented the same crystallographic orientation. Electron nanodiffraction maps from 4μm×4μm regions prepared by FIB showed disorientation of <2° between diffraction patterns obtained from neighbor regions, indicating the presence of a unique, highly aligned calcite crystalline phase. Among the eight FIB sections obtained, four presented high pore density. In one section perpendicular to the actine axis pores were observed only in the center of the spicule aligned in a circular pattern and surrounded by a faint circular contour with a larger radius. The presence of amorphous carbon representative of organic molecules detected by electron energy loss spectroscopy was correlated neither with porosity nor with specific lattice planes. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Active combustion flow modulation valve

Science.gov (United States)

Hensel, John Peter; Black, Nathaniel; Thorton, Jimmy Dean; Vipperman, Jeffrey Stuart; Lambeth, David N; Clark, William W

2013-09-24

A flow modulation valve has a slidably translating hollow armature with at least one energizable coil wound around and fixably attached to the hollow armature. The energizable coil or coils are influenced by at least one permanent magnet surrounding the hollow armature and supported by an outer casing. Lorentz forces on the energizable coils which are translated to the hollow armature, increase or decrease the flow area to provide flow throttling action. The extent of hollow armature translation depends on the value of current supplied and the direction of translation depends on the direction of current flow. The compact nature of the flow modulation valve combined with the high forces afforded by the actuator design provide a flow modulation valve which is highly responsive to high-rate input control signals.

Trans-generational study of DNA alterations and their consequences on life history traits and energy budget of Daphnia magna exposed to depleted uranium

International Nuclear Information System (INIS)

Plaire, Delphine

2013-01-01

Understanding how toxicants affect species at various levels of biological organization is a major research goal in both ecotoxicology and radioecology. As part of IRSN program ENVIRHOM, which aims to assess environmental risks related to the presence of radionuclides in the environment, this PhD work explored how depleted uranium alters DNA and affects life history traits (survival, growth and reproduction) of an aquatic invertebrate, Daphnia magna. To answer to this problematic, an experimental approach and a modeling approach are conducted. An experimental study is performed to evaluate DNA accumulation and transmission during an uranium exposure (0; 2; 9.9; 22.2 and 50 μg.L -1 ) over two successive generations (F0 and F1). Different exposures scenarios (continuous, post-hatching and embryo exposure) are achieved to test the specific sensitivity of several life stages to uranium. Genotoxic effects are estimated using random amplified DNA technique combined with PCR (PCR-RAPD). In continuous and post-hatching exposure scenarios, results highlighted an accumulation and a transmission of DNA damage across generations with an increase in effect severity. DNA alterations are reported at hatching of the F1 generation at a concentration as low as 2 μg.L -1 . Effects on growth and reproduction are stronger when the embryo stage is exposed and remain visible at 9.9 μg.L -1 despite a return in a clean medium at hatching. Results suggest that DNA damage could be used as early indicators of future effects on life history traits. A mechanistic analysis of experimental results is conducted using a DEBtox model (dynamic energy budget applied to toxicology) to better understand the causes of the increase in effect severity across generations. A model with two stress factors (one correlated to external concentration and another correlated to a damage level) is developed. Results of fits suggest the involvement of one second mode of action to explain immediate effects of

Serotonergic modulation of spinal motor control

DEFF Research Database (Denmark)

Perrier, Jean-Francois Marie; Cotel, Florence

2015-01-01

Serotonin (5-HT) is a monoamine that powerfully modulates spinal motor control by acting on intrasynaptic and extrasynaptic receptors. Here we review the diversity of 5-HT actions on locomotor and motoneuronal activities. Two approaches have been used on in vitro spinal cord preparations: either...

CARACTERIZAÇÃO DE PAINÉIS LAMINADOS COLADOS PRODUZIDOS COM TALISCAS DE BAMBU (Guadua magna NATIVO DO CERRADO

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Divino Eterno Teixeira

2015-12-01

Full Text Available Panels were produced with strips of bamboo (Guadua magna in layers crossed at angles of 90° and bonded with phenol-formaldehyde or PVA based resin, glued in three and five plies. The panels were tested and the physical and mechanical properties determined. The tests were primarily related to the commercial adhesives used as well as the number of layers of bamboo used. The density ranged from 0.690 to 0.768 g.cm-3. Panels bonded with PVA resin showed low mechanical strength, with MOR between 6.7 and 7.8 MPa. Those bonded with phenol-formaldehyde adhesive showed high strength, with modulus of rupture (MOR ranging from 55.5 to 87.0 MPa, which is excellent for boards similar to wood-based panels. Panels with phenolic resin also had reduced thickness swelling, up to 8.4%. The panels made with three layers showed higher resistance to bending than those made with five layers.

Areas Recruited during Action Understanding Are Not Modulated by Auditory or Sign Language Experience.

Science.gov (United States)

Fang, Yuxing; Chen, Quanjing; Lingnau, Angelika; Han, Zaizhu; Bi, Yanchao

2016-01-01

The observation of other people's actions recruits a network of areas including the inferior frontal gyrus (IFG), the inferior parietal lobule (IPL), and posterior middle temporal gyrus (pMTG). These regions have been shown to be activated through both visual and auditory inputs. Intriguingly, previous studies found no engagement of IFG and IPL for deaf participants during non-linguistic action observation, leading to the proposal that auditory experience or sign language usage might shape the functionality of these areas. To understand which variables induce plastic changes in areas recruited during the processing of other people's actions, we examined the effects of tasks (action understanding and passive viewing) and effectors (arm actions vs. leg actions), as well as sign language experience in a group of 12 congenitally deaf signers and 13 hearing participants. In Experiment 1, we found a stronger activation during an action recognition task in comparison to a low-level visual control task in IFG, IPL and pMTG in both deaf signers and hearing individuals, but no effect of auditory or sign language experience. In Experiment 2, we replicated the results of the first experiment using a passive viewing task. Together, our results provide robust evidence demonstrating that the response obtained in IFG, IPL, and pMTG during action recognition and passive viewing is not affected by auditory or sign language experience, adding further support for the supra-modal nature of these regions.

Trainer module for security control center operations

International Nuclear Information System (INIS)

Bernard, E.A.

1982-01-01

An operator trainer module has been developed to be used with the security control center equipment to be installed as part of a safeguards physical protection system. The module is designed to provide improved training and testing capabilities for control center operators through the use of simulations for perimeter equipment operations. Operators, through the trainer module, can be challenged with a variety of realistic situations which require responsive action identical to that needed in an actual system. This permits a consistent evaluation and confirmation of operator capabilities prior to assignment as an operator and allows for periodic retesting to verify that adequate performance levels are maintained

Insulin Action in Brain Regulates Systemic Metabolism and Brain Function

OpenAIRE

Kleinridders, Andr?; Ferris, Heather A.; Cai, Weikang; Kahn, C. Ronald

2014-01-01

Insulin receptors, as well as IGF-1 receptors and their postreceptor signaling partners, are distributed throughout the brain. Insulin acts on these receptors to modulate peripheral metabolism, including regulation of appetite, reproductive function, body temperature, white fat mass, hepatic glucose output, and response to hypoglycemia. Insulin signaling also modulates neurotransmitter channel activity, brain cholesterol synthesis, and mitochondrial function. Disruption of insulin action in t...

Alteration of cardiac glycoside positive inotropic action by modulators of protein synthesis and degradation

International Nuclear Information System (INIS)

Nosek, T.M.; Adams, R.J.

1986-01-01

Numerous membrane bound and cytoplasmic proteins participate in the cardiac expression of the positive inotropic action (PIA) of digitalis glycosides including the Na,K-ATPase (NKA). Exposure of the myocardium to an inhibitor of protein synthesis (cycloheximide, CYC) or of protein degradation (leupeptin, LEU) alters the PIA of ouabain in isolated, paced guinea pig papillary muscles (PM) in opposite ways. In vivo exposure to CYC for 3 hr resulted in a 30% depression of the in vitro PIA of ouabain at 1.7μM compared to control. In vivo exposure to LEU for 1 hr resulted in a 47% enhancement of the in vitro PIA of 1.7μM ouabain. Neither drug had an apparent effect on the ouabain PIA ED50. Neither CYC nor LEU exposure to PM in vitro affect resting or developed tension or the response of skinned PM to calcium. The mechanisms of the PIA alterations by CYC or LEU do not involve a direct effect on the digitalis receptor. Exposure of isolated cardiac sarcolemma enriched in NKA to 10-100μM CYC or LEU did not affect NKA activity or 3 H-ouabain binding. Although direct physicochemical effects of CYC or LEU may be involved in the alterations of the ouabain PIA, it is possible that modulation of the cellular levels or turnover rate of short-lived proteins may affect cardiac regulation of the digitalis PIA

Topical glucocorticoids and the skin-mechanisms of action: an update

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A. Ahluwalia

1998-01-01

Full Text Available The topical glucocorticoids (GCs represent the treatment of choice for many types of inflammatory dermatoses. Despite the extensive use of this class of drugs as first line therapy the mechanism of their action is uncertain. It is clear that the multiplicity of actions of the topical GCs is an important facet of their scope in the treatment of dermal disorders. The aim of this update is to review past and current theories regarding how these agents might work. Current understanding of the molecular mechanism s of GC action has advanced significantly over the past decade with the realisation that multiple systems are responsible for transduction of GC effects at a molecular level. The two primary modes of action are via interaction directly with DNA or indirectly through modulation of specific transcription factors: the endpoint in both cases being modulation of specific protein synthesis. Both of these mechanisms will be discussed. In particular this review will concentrate on the possibility that a GC-inducible protein, termed lipocortin 1, may have a significant role to play in the anti-inflammatory actions of these drugs. Additionally it has become apparent that several inflammatory enzymes induced in inflamm ation are sites of inhibitory action of the GCs, and the possibility that this occurs in the skin will be discussed paying particular attention to the inducible phospholipase A2, nitric oxide synthase and cyclooxygenase systems.

Students in Action Initiative

OpenAIRE

Ryan, Theresa; Mottiar, Ziene; Quinn, Bernadette; Gorman, Catherine; Griffin, Kevin; Craggs, Ruth; Quinn, Deirdre

2015-01-01

The Students in Action Project in the School of Hospitality Management and Tourism was established in 2012 as a way of engaging students and working with stakeholders in a destination. The overall aim of the project was to immerse students in an active collaborative learning environment within the destination to identify ways in which tourism could be enhanced. In the 2014/2015 academic year the project involved over 300 students from a variety of programmes and modules working with local sta...

Action recognition is sensitive to the identity of the actor.

Science.gov (United States)

Ferstl, Ylva; Bülthoff, Heinrich; de la Rosa, Stephan

2017-09-01

Recognizing who is carrying out an action is essential for successful human interaction. The cognitive mechanisms underlying this ability are little understood and have been subject of discussions in embodied approaches to action recognition. Here we examine one solution, that visual action recognition processes are at least partly sensitive to the actor's identity. We investigated the dependency between identity information and action related processes by testing the sensitivity of neural action recognition processes to clothing and facial identity information with a behavioral adaptation paradigm. Our results show that action adaptation effects are in fact modulated by both clothing information and the actor's facial identity. The finding demonstrates that neural processes underlying action recognition are sensitive to identity information (including facial identity) and thereby not exclusively tuned to actions. We suggest that such response properties are useful to help humans in knowing who carried out an action. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

How cyclophosphamide at environmentally relevant concentration influences Daphnia magna life history and its proteome.

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Małgorzata Grzesiuk

Full Text Available The waste of commonly used medicines is known to contaminate freshwater ecosystems. Pharmaceuticals can be toxic, mutagenic, or modifying to freshwater organisms even at low concentrations if consider their permanent presence in the environment. Chemotherapeutics used to treat cancer, and in particular alkylating agents, contribute significantly to this form of pollution, the latter introducing cytotoxic and/or mutagenic lesions to the DNA and RNA of organisms which can be disruptive to their cells. The aim of the present study was to investigate the influence of the alkylating anticancer agent cyclophosphamide (CP on Daphnia magna clones. We evaluated the life history parameters and protein profiles of this crustacean following exposure to environmentally relevant CP concentration of 10 ng L-1. Even at this low concentration, the alkylating agent caused modification of the life history parameters and proteome profile of the Daphnia. These changes were clone-specific and involved growth rate, age at first reproduction, neonate number, and proteins related to cell cycle and redox state regulation. The disturbance caused by pharmaceuticals contaminating freshwater ecosystem is probably weaker and unlikely to be cytotoxic in character due to the high dilution of these substances in the water. However, our results indicate that prolonged exposure of organisms to these toxins may lead to modifications on the organismal and molecular levels with unpredictable significance for the entire ecosystem.

Seasonal abundance and activity of pill millipedes ( Arthrosphaera magna) in mixed plantation and semi-evergreen forest of southern India

Science.gov (United States)

Ashwini, Krishna M.; Sridhar, Kandikere R.

2006-01-01

Seasonal occurrence and activity of endemic pill millipedes ( Arthrosphaera magna) were examined in organically managed mixed plantation and semi-evergreen forest reserve in southwest India between November 1996 and September 1998. Abundance and biomass of millipedes were highest in both habitats during monsoon season. Soil moisture, conductivity, organic carbon, phosphate, potassium, calcium and magnesium were higher in plantation than in forest. Millipede abundance and biomass were about 12 and 7 times higher in plantation than in forest, respectively ( P 0.05). Millipede abundance and biomass were positively correlated with rainfall ( P = 0.01). Besides rainfall, millipedes in plantation were positively correlated with soil moisture as well as temperature ( P = 0.001). Among the associated fauna with pill millipedes, earthworms rank first followed by soil bugs in both habitats. Since pill millipedes are sensitive to narrow ecological changes, the organic farming strategies followed in mixed plantation and commonly practiced in South India seem not deleterious for the endangered pill millipedes Arthrosphaera and reduce the risk of local extinctions.

Propulsion of the Water Flea, Daphnia magna: Experiments, Scaling, and Modelling

Science.gov (United States)

Skipper, A. N.; Murphy, D.; Webster, D. R.; Yen, J.

2016-02-01

The freshwater crustacean Daphnia magna is a widely studied zooplankton in relation to food webs, predator-prey interactions, and other biological/ecological considerations; however, their locomotion is poorly quantified and understood. These water fleas utilize a hop-and-sink mechanism that consists of making quick, impulsive jumps by beating their antennae to propel themselves forward ( 1 body length). The animals then sink for a period, during which they stretch out their antennae to increase drag and thereby reduce their sinking velocity. Time-resolved three-dimensional flow fields surrounding the animals were quantified with a unique infrared tomographic particle image velocity (tomo-PIV) system. Three-dimensional kinematics data were also extracted from the image sequences. In the current work, we compared body kinematics and flow disturbance among organisms of size in the range of 1.3 to 2.8 mm. The stroke cycle averaged 150 ms in duration, ranging from 100 to 180 ms; this period is generally evenly split between the power and recovery strokes. The range of peak hop velocity was 27.2 to 32.5 mm/s, and peak acceleration was in the range of 0.68 to 1.8 m/s2. The results showed a distinct relationship between peak hop speed (Vmax 14 BL/s) and body size; these data collapsed onto a single time-record curve during the power stroke when properly non-dimensionalized. The fluid flow induced by each antennae consisted of a viscous vortex ring that demonstrated a slow decay in the wake. The strength, size, and decay of the induced viscous vortex rings were compared as a function of organism size. Finally, the viscous vortex rings were analyzed in the context of a double Stokeslet model that consisted of two impulsively applied point forces separated by the animal width.

Redox Modulations, Antioxidants, and Neuropsychiatric Disorders

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Erik A. Fraunberger

2016-01-01

Full Text Available Although antioxidants, redox modulations, and neuropsychiatric disorders have been widely studied for many years, the field would benefit from an integrative and corroborative review. Our primary objective is to delineate the biological significance of compounds that modulate our redox status (i.e., reactive species and antioxidants as well as outline their current role in brain health and the impact of redox modulations on the severity of illnesses. Therefore, this review will not enter into the debate regarding the perceived medical legitimacy of antioxidants but rather seek to clarify their abilities and limitations. With this in mind, antioxidants may be interpreted as natural products with significant pharmacological actions in the body. A renewed understanding of these often overlooked compounds will allow us to critically appraise the current literature and provide an informed, novel perspective on an important healthcare issue. In this review, we will introduce the complex topics of redox modulations and their role in the development of select neuropsychiatric disorders.

Revisiting Jürgen Habermas's notion of communicative action and ...

African Journals Online (AJOL)

Erna Kinsey

its relevance for South African school governance: can it succeed? Nonceba ... Keywords: communicative action; Department of Education; governance framework .... view was open-ended and conducted in an informal, non-directive manner so ..... Issues in Social Science Research Methodology (Module 1). Ethiopia:.

Joint action syntax in Japanese martial arts.

Science.gov (United States)

Yamamoto, Yuji; Yokoyama, Keiko; Okumura, Motoki; Kijima, Akifumi; Kadota, Koji; Gohara, Kazutoshi

2013-01-01

Participation in interpersonal competitions, such as fencing or Japanese martial arts, requires players to make instantaneous decisions and execute appropriate motor behaviors in response to various situations. Such actions can be understood as complex phenomena emerging from simple principles. We examined the intentional switching dynamics associated with continuous movement during interpersonal competition in terms of their emergence from a simple syntax. Linear functions on return maps identified two attractors as well as the transitions between them. The effects of skill differences were evident in the second- and third-order state-transition diagrams for these two attractors. Our results suggest that abrupt switching between attractors is related to the diverse continuous movements resulting from quick responses to sudden changes in the environment. This abrupt-switching-quick-response behavior is characterized by a joint action syntax. The resulting hybrid dynamical system is composed of a higher module with discrete dynamics and a lower module with continuous dynamics. Our results suggest that intelligent human behavior and robust autonomy in real-life scenarios are based on this hybrid dynamical system, which connects interpersonal coordination and competition.

Effects of context on visuomotor interference depends on the perspective of observed actions.

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Marta Bortoletto

Full Text Available Visuomotor interference occurs when the execution of an action is facilitated by the concurrent observation of the same action and hindered by the concurrent observation of a different action. There is evidence that visuomotor interference can be modulated top-down by higher cognitive functions, depending on whether own performed actions or observed actions are selectively attended. Here, we studied whether these effects of cognitive context on visuomotor interference are also dependent on the point-of-view of the observed action. We employed a delayed go/no-go task known to induce visuomotor interference. Static images of hand gestures in either egocentric or allocentric perspective were presented as "go" stimuli after participants were pre-cued to prepare either a matching (congruent or non-matching (incongruent action. Participants performed this task in two different cognitive contexts: In one, they focused on the visual image of the hand gesture shown as the go stimulus (image context, whereas in the other they focused on the hand gesture they performed (action context. We analyzed reaction times to initiate the prepared action upon presentation of the gesture image and found evidence of visuomotor interference in both contexts and for both perspectives. Strikingly, results show that the effect of cognitive context on visuomotor interference also depends on the perspective of observed actions. When focusing on own-actions, visuomotor interference was significantly less for gesture images in allocentric perspective than in egocentric perspective; when focusing on observed actions, visuomotor interference was present regardless of the perspective of the gesture image. Overall these data suggest that visuomotor interference may be modulated by higher cognitive processes, so that when we are specifically attending to our own actions, images depicting others' actions (allocentric perspective have much less interference on our own actions.

Mechanisms underlying selecting objects for action

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Melanie eWulff

2015-04-01

Full Text Available We assessed the factors which affect the selection of objects for action, focusing on the role of action knowledge and its modulation by distracters. 14 neuropsychological patients and 10 healthy aged-matched controls selected pairs of objects commonly used together among distracters in two contexts: with real objects and with pictures of the same objects presented sequentially on a computer screen. Across both tasks, semantically related distracters led to slower responses and more errors than unrelated distracters and the object actively used for action was selected prior to the object that would be passively held during the action. We identified a sub-group of patients (N=6 whose accuracy was 2SD below the controls performances in the real object task. Interestingly, these impaired patients were more affected by the presence of unrelated distracters during both tasks than intact patients and healthy controls. Note the impaired had lesions to left parietal, right anterior temporal and bilateral pre-motor regions. We conclude that: (1 motor procedures guide object selection for action, (2 semantic knowledge affects action-based selection, (3 impaired action decision is associated with the inability to ignore distracting information and (4 lesions to either the dorsal or ventral visual stream can lead to deficits in making action decisions. Overall, the data indicate that impairments in everyday tasks can be evaluated using a simulated computer task. The implications for rehabilitation are discussed.

The Effects of Optical Illusions in Perception and Action in Peripersonal and Extrapersonal Space.

Science.gov (United States)

Shim, Jaeho; van der Kamp, John

2017-09-01

While the two visual system hypothesis tells a fairly compelling story about perception and action in peripersonal space (i.e., within arm's reach), its validity for extrapersonal space is very limited and highly controversial. Hence, the present purpose was to assess whether perception and action differences in peripersonal space hold in extrapersonal space and are modulated by the same factors. To this end, the effects of an optic illusion in perception and action in both peripersonal and extrapersonal space were compared in three groups that threw balls toward a target at a distance under different target eccentricity (i.e., with the target fixated and in peripheral field), viewing (i.e., binocular and monocular viewing), and delay conditions (i.e., immediate and delayed action). The illusory bias was smaller in action than in perception in peripersonal space, but this difference was significantly reduced in extrapersonal space, primarily because of a weakening bias in perception. No systematic modulation of target eccentricity, viewing, and delay arose. The findings suggest that the two visual system hypothesis is also valid for extra personal space.

A new VME timing module: TG8

International Nuclear Information System (INIS)

Beetham, C.G.; Daems, G.; Lewis, J.; Puccio, B.

1992-01-01

The two accelerator divisions of CERN, namely PS and SL, are defining a new common control system based on PC, VME and Workstations. This has provided an opportunity to review both central timing systems and to come up with common solutions. The result was, amongst others, the design of a unique timing module, called TG8. The TG8 is a multipurpose VME module, which receives messages distributed over a timing network. These messages include timing information, clock plus calendar and telegrams instructing the CERN accelerators on the characteristics of the next beam to be produced. The TG8 compares incoming messages with up to 256 programmed actions. An action consists of two parts, a trigger which matches an incoming message and what to do when the match occurs. The latter part may optionally create an output pulse on one of the eight output channels and/or a bus interrupt, both with programmable delay and telegram conditioning. (author)

FMFinder: A Functional Module Detector for PPI Networks

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M. Modi

2017-10-01

Full Text Available Bioinformatics is an integrated area of data mining, statistics and computational biology. Protein-Protein Interaction (PPI network is the most important biological process in living beings. In this network a protein module interacts with another module and so on, forming a large network of proteins. The same set of proteins which takes part in the organic courses of biological actions is detected through the Function Module Detection method. Clustering process when applied in PPI networks is made of proteins which are part of a larger communication network. As a result of this, we can define the limits for module detection as well as clarify the construction of a PPI network. For understating the bio-mechanism of various living beings, a detailed study of FMFinder detection by clustering process is called for.

Regulation and dysregulation of vitellogenin mRNA accumulation in daphnids (Daphnia magna)

Energy Technology Data Exchange (ETDEWEB)

Hannas, Bethany R.; Wang, Ying H.; Thomson, Susanne; Kwon, Gwijun; Hong, Li [Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, NC 27695-7633 (United States); LeBlanc, Gerald A., E-mail: Gerald_LeBlanc@ncsu.edu [Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, NC 27695-7633 (United States)

2011-01-25

The induction of vitellogenin in oviparous vertebrates has become the gold standard biomarker of exposure to estrogenic chemicals in the environment. This biomarker of estrogen exposure also has been used in arthropods, however, little is known of the factors that regulate the expression of vitellogenin in these organisms. We investigated changes in accumulation of mRNA products of the vitellogenin gene Vtg2 in daphnids (Daphnia magna) exposed to a diverse array of chemicals. We further evaluated the involvement of hormonal factors in the regulation of vitellogenin expression that may be targets of xenobiotic chemicals. Expression of the Vtg2 gene was highly responsive to exposure to various chemicals with an expression range spanning approximately four orders of magnitude. Chemicals causing the greatest induction were piperonyl butoxide, chlordane, 4-nonylphenol, cadmium, and chloroform. Among these, only 4-nonylphenol is recognized to be estrogenic. Exposure to several chemicals also suppressed Vtg2 mRNA levels, as much as 100-fold. Suppressive chemicals included cyproterone acetate, acetone, triclosan, and atrazine. Exposure to the estrogens diethylstilbestrol and bisphenol A had little effect on vitellogenin mRNA levels further substantiating that these genes are not induced by estrogen exposure. Exposure to the potent ecdysteroids 20-hydroxyecdysone and ponasterone A revealed that Vtg2 was subject to strong suppressive control by these hormones. Vtg2 mRNA levels were not significantly affected from exposure to several juvenoid hormones. Results indicate that ecdysteroids are suppressors of vitellogenin gene expression and that vitellogenin mRNA levels can be elevated or suppressed in daphnids by xenobiotics that elicit antiecdysteroidal or ecdysteroidal activity, respectively. Importantly, daphnid Vtg2 is not elevated in response to estrogenic activity.

Regulation and dysregulation of vitellogenin mRNA accumulation in daphnids (Daphnia magna)

International Nuclear Information System (INIS)

Hannas, Bethany R.; Wang, Ying H.; Thomson, Susanne; Kwon, Gwijun; Li Hong; LeBlanc, Gerald A.

2011-01-01

The induction of vitellogenin in oviparous vertebrates has become the gold standard biomarker of exposure to estrogenic chemicals in the environment. This biomarker of estrogen exposure also has been used in arthropods, however, little is known of the factors that regulate the expression of vitellogenin in these organisms. We investigated changes in accumulation of mRNA products of the vitellogenin gene Vtg2 in daphnids (Daphnia magna) exposed to a diverse array of chemicals. We further evaluated the involvement of hormonal factors in the regulation of vitellogenin expression that may be targets of xenobiotic chemicals. Expression of the Vtg2 gene was highly responsive to exposure to various chemicals with an expression range spanning approximately four orders of magnitude. Chemicals causing the greatest induction were piperonyl butoxide, chlordane, 4-nonylphenol, cadmium, and chloroform. Among these, only 4-nonylphenol is recognized to be estrogenic. Exposure to several chemicals also suppressed Vtg2 mRNA levels, as much as 100-fold. Suppressive chemicals included cyproterone acetate, acetone, triclosan, and atrazine. Exposure to the estrogens diethylstilbestrol and bisphenol A had little effect on vitellogenin mRNA levels further substantiating that these genes are not induced by estrogen exposure. Exposure to the potent ecdysteroids 20-hydroxyecdysone and ponasterone A revealed that Vtg2 was subject to strong suppressive control by these hormones. Vtg2 mRNA levels were not significantly affected from exposure to several juvenoid hormones. Results indicate that ecdysteroids are suppressors of vitellogenin gene expression and that vitellogenin mRNA levels can be elevated or suppressed in daphnids by xenobiotics that elicit antiecdysteroidal or ecdysteroidal activity, respectively. Importantly, daphnid Vtg2 is not elevated in response to estrogenic activity.

Second generation γ-secretase modulators exhibit different modulation of Notch β and Aβ production.

Science.gov (United States)

Wanngren, Johanna; Ottervald, Jan; Parpal, Santiago; Portelius, Erik; Strömberg, Kia; Borgegård, Tomas; Klintenberg, Rebecka; Juréus, Anders; Blomqvist, Jenny; Blennow, Kaj; Zetterberg, Henrik; Lundkvist, Johan; Rosqvist, Susanne; Karlström, Helena

2012-09-21

The γ-secretase complex is an appealing drug target when the therapeutic strategy is to alter amyloid-β peptide (Aβ) aggregation in Alzheimer disease. γ-Secretase is directly involved in Aβ formation and determines the pathogenic potential of Aβ by generating the aggregation-prone Aβ42 peptide. Because γ-secretase mediates cleavage of many substrates involved in cell signaling, such as the Notch receptor, it is crucial to sustain these pathways while altering the Aβ secretion. A way of avoiding interference with the physiological function of γ-secretase is to use γ-secretase modulators (GSMs) instead of inhibitors of the enzyme. GSMs modify the Aβ formation from producing the amyloid-prone Aβ42 variant to shorter and less amyloidogenic Aβ species. The modes of action of GSMs are not fully understood, and even though the pharmacology of GSMs has been thoroughly studied regarding Aβ generation, knowledge is lacking about their effects on other substrates, such as Notch. Here, using immunoprecipitation followed by MALDI-TOF MS analysis, we found that two novel, second generation GSMs modulate both Notch β and Aβ production. Moreover, by correlating S3-specific Val-1744 cleavage of Notch intracellular domain (Notch intracellular domain) to total Notch intracellular domain levels using immunocytochemistry, we also demonstrated that Notch intracellular domain is not modulated by the compounds. Interestingly, two well characterized, nonsteroidal anti-inflammatory drugs (nonsteroidal anti-inflammatory drug), R-flurbiprofen and sulindac sulfide, affect only Aβ and not Notch β formation, indicating that second generation GSMs and nonsteroidal anti-inflammatory drug-based GSMs have different modes of action regarding Notch processing.

Inducing repetitive action potential firing in neurons via synthesized photoresponsive nanoscale cellular prostheses.

Science.gov (United States)

Lu, Siyuan; Madhukar, Anupam

2013-02-01

Recently we reported an analysis that examined the potential of synthesized photovoltaic functional abiotic nanosystems (PVFANs) to modulate membrane potential and activate action potential firing in neurons. Here we extend the analysis to delineate the requirements on the electronic energy levels and the attendant photophysical properties of the PVFANs to induce repetitive action potential under continuous light, a capability essential for the proposed potential application of PVFANs as retinal cellular prostheses to compensate for loss of photoreceptors. We find that repetitive action potential firing demands two basic characteristics in the electronic response of the PVFANs: an exponential dependence of the PVFAN excited state decay rate on the membrane potential and a three-state system such that, following photon absorption, the electron decay from the excited state to the ground state is via intermediate state(s) whose lifetime is comparable to the refractory time following an action potential. In this study, the potential of synthetic photovoltaic functional abiotic nanosystems (PVFANs) is examined under continuous light to modulate membrane potential and activate action potential firing in neurons with the proposed potential application of PVFANs as retinal cellular prostheses. Copyright © 2013 Elsevier Inc. All rights reserved.

How the mind shapes action: Offline contexts modulate involuntary episodic retrieval.

Science.gov (United States)

Frings, Christian; Koch, Iring; Moeller, Birte

2017-11-01

Involuntary retrieval of previous stimulus-response episodes is a centerpiece of many theories of priming, episodic binding, and action control. Typically it is assumed that by repeating a stimulus from trial n-1 to trial n, involuntary retrieval is triggered in a nearly automatic fashion, facilitating (or interfering with) the to-be-executed action. Here we argue that changes in the offline context weaken the involuntary retrieval of previous episodes (the offline context is defined to be the information presented before or after the focal stimulus). In four conditions differing in cue modality and target modality, retrieval was diminished if participants changed the target selection criterion (as indicated by a cue presented before the selection took place) while they still performed the same task. Thus, solely through changes in the offline context (cue or selection criterion), involuntary retrieval can be weakened in an effective way.

Acupuncture's Cardiovascular Actions: A Mechanistic Perspective

OpenAIRE

Longhurst, John

2013-01-01

Over the last several decades, there has been an explosion of articles on acupuncture, including studies that have begun to explore mechanisms underlying its analgesic and cardiovascular actions. Modulation of cardiovascular function is most effective during manual and low-frequency, low-intensity electroacupuncture (EA) at a select set of acupoints situated along meridians located over deep somatic nerves on the upper and lower extremities. Stimulation at these acupoints activates underlying...

Scripting Module for the Satellite Orbit Analysis Program (SOAP)

Science.gov (United States)

Carnright, Robert; Paget, Jim; Coggi, John; Stodden, David

2008-01-01

This add-on module to the SOAP software can perform changes to simulation objects based on the occurrence of specific conditions. This allows the software to encompass simulation response of scheduled or physical events. Users can manipulate objects in the simulation environment under programmatic control. Inputs to the scripting module are Actions, Conditions, and the Script. Actions are arbitrary modifications to constructs such as Platform Objects (i.e. satellites), Sensor Objects (representing instruments or communication links), or Analysis Objects (user-defined logical or numeric variables). Examples of actions include changes to a satellite orbit ( v), changing a sensor-pointing direction, and the manipulation of a numerical expression. Conditions represent the circumstances under which Actions are performed and can be couched in If-Then-Else logic, like performing v at specific times or adding to the spacecraft power only when it is being illuminated by the Sun. The SOAP script represents the entire set of conditions being considered over a specific time interval. The output of the scripting module is a series of events, which are changes to objects at specific times. As the SOAP simulation clock runs forward, the scheduled events are performed. If the user sets the clock back in time, the events within that interval are automatically undone. This script offers an interface for defining scripts where the user does not have to remember the vocabulary of various keywords. Actions can be captured by employing the same user interface that is used to define the objects themselves. Conditions can be set to invoke Actions by selecting them from pull-down lists. Users define the script by selecting from the pool of defined conditions. Many space systems have to react to arbitrary events that can occur from scheduling or from the environment. For example, an instrument may cease to draw power when the area that it is tasked to observe is not in view. The contingency

Do microplastic particles affect Daphnia magna at the morphological, life history and molecular level?

Directory of Open Access Journals (Sweden)

Hannes K Imhof

Full Text Available Microplastic particles are ubiquitous not only in marine but also in freshwater ecosystems. However, the impacts of microplastics, consisting of a large variety of synthetic polymers, on freshwater organisms remains poorly understood. We examined the effects of two polymer mixtures on the morphology, life history and on the molecular level of the waterflea Daphnia magna (three different clones. Microplastic particles of ~40 μm were supplied at a low concentration (1% of the food particles leading to an average of ~30 particles in the digestive tract which reflects a high microplastic contamination but still resembles a natural situation. Neither increased mortality nor changes on the morphological (body length, width and tail spine length or reproductive parameters were observed for adult Daphnia. The analyses of juvenile Daphnia revealed a variety of small and rather subtle responses of morphological traits (body length, width and tail spine length. For adult Daphnia, alterations in expression of genes related to stress responses (i.e. HSP60, HSP70 & GST as well as of other genes involved in body function and body composition (i.e. SERCA were observed already 48h after exposure. We anticipate that the adverse effects of microplastic might be influenced by many additional factors like size, shape, type and even age of the particles and that the rather weak effects, as detected in a laboratory, may lead to reduced fitness in a natural multi-stressor environment.

Comparison of the capacity of two biotic ligand models to predict chronic copper toxicity to two Daphnia magna clones and formulation of a generalized bioavailability model.

Science.gov (United States)

Van Regenmortel, Tina; Janssen, Colin R; De Schamphelaere, Karel A C

2015-07-01

Although it is increasingly recognized that biotic ligand models (BLMs) are valuable in the risk assessment of metals in aquatic systems, the use of 2 differently structured and parameterized BLMs (1 in the United States and another in the European Union) to obtain bioavailability-based chronic water quality criteria for copper is worthy of further investigation. In the present study, the authors evaluated the predictive capacity of these 2 BLMs for a large dataset of chronic copper toxicity data with 2 Daphnia magna clones, termed K6 and ARO. One BLM performed best with clone K6 data, whereas the other performed best with clone ARO data. In addition, there was an important difference between the 2 BLMs in how they predicted the bioavailability of copper as a function of pH. These modeling results suggested that the effect of pH on chronic copper toxicity is different between the 2 clones considered, which was confirmed with additional chronic toxicity experiments. Finally, because fundamental differences in model structure between the 2 BLMs made it impossible to create an average BLM, a generalized bioavailability model (gBAM) was developed. Of the 3 gBAMs developed, the authors recommend the use of model gBAM-C(uni), which combines a log-linear relation between the 21-d median effective concentration (expressed as free Cu(2+) ion activity) and pH, with more conventional BLM-type competition constants for sodium, calcium, and magnesium. This model can be considered a first step in further improving the accuracy of chronic toxicity predictions of copper as a function of water chemistry (for a variety of Daphnia magna clones), even beyond the robustness of the current BLMs used in regulatory applications. © 2015 SETAC.

Bidirectional modulation of goal-directed actions by prefrontal cortical dopamine.

Science.gov (United States)

Hitchcott, Paul K; Quinn, Jennifer J; Taylor, Jane R

2007-12-01

Instrumental actions are a vital cognitive asset that endows an organism with sensitivity to the consequences of its behavior. Response-outcome feedback allows responding to be shaped in order to maximize beneficial, and minimize detrimental, outcomes. Lesions of the medial prefrontal cortex (mPFC) result in behavior that is insensitive to changes in outcome value in animals and compulsive behavior in several human psychopathologies. Such insensitivity to changes in outcome value is a defining characteristic of instrumental habits: responses that are controlled by antecedent stimuli rather than goal expectancy. Little is known regarding the neurochemical substrates mediating this sensitivity. The present experiments used sensitivity to posttraining outcome devaluation to index the action-habit status of instrumental responding. Infusions of dopamine into the ventral mPFC (vmPFC), but not dorsal mPFC, restored outcome sensitivity bidirectionally-decreasing responding following outcome devaluation and increasing responding when the outcome was not devalued. This bidirectionality makes the possibility that these infusions nonspecifically dysregulated vmPFC dopamine transmission unlikely. VmPFC dopamine promoted instrumental responding appropriate to outcome value. Reinforcer consumption data indicated that this was not a consequence of altered sensitivity to the reinforcer itself. We suggest that vmPFC dopamine reengages attentional processes underlying goal-directed behavior.

Action plan for photovoltaic standards

Energy Technology Data Exchange (ETDEWEB)

Oldach, R.

1999-07-01

This report examines the present situation regarding international standards governing photovoltaic (PV) systems and components, and seeks to identify barriers to the commercialisation of PV systems in the UK due to the absence of standards and codes of practice, and develop an action plan to overcome these barriers. An overview of standardisation bodies and standard generation mechanisms is presented, and the PV cells and modules, stand-alone PV systems, utility interconnection with PV systems, and building integration of PV are reviewed.

Motor-Evoked Potentials in the Lower Back Are Modulated by Visual Perception of Lifted Weight.

Directory of Open Access Journals (Sweden)

Frank Behrendt

Full Text Available Facilitation of the primary motor cortex (M1 during the mere observation of an action is highly congruent with the observed action itself. This congruency comprises several features of the executed action such as somatotopy and temporal coding. Studies using reach-grasp-lift paradigms showed that the muscle-specific facilitation of the observer's motor system reflects the degree of grip force exerted in an observed hand action. The weight judgment of a lifted object during action observation is an easy task which is the case for hand actions as well as for lifting boxes from the ground. Here we investigated whether the cortical representation in M1 for lumbar back muscles is modulated due to the observation of a whole-body lifting movement as it was shown for hand action. We used transcranial magnetic stimulation (TMS to measure the corticospinal excitability of the m. erector spinae (ES while subjects visually observed the recorded sequences of a person lifting boxes of different weights from the floor. Consistent with the results regarding hand action the present study reveals a differential modulation of corticospinal excitability despite the relatively small M1 representation of the back also for lifting actions that mainly involve the lower back musculature.

Motor-Evoked Potentials in the Lower Back Are Modulated by Visual Perception of Lifted Weight.

Science.gov (United States)

Behrendt, Frank; de Lussanet, Marc H E; Zentgraf, Karen; Zschorlich, Volker R

2016-01-01

Facilitation of the primary motor cortex (M1) during the mere observation of an action is highly congruent with the observed action itself. This congruency comprises several features of the executed action such as somatotopy and temporal coding. Studies using reach-grasp-lift paradigms showed that the muscle-specific facilitation of the observer's motor system reflects the degree of grip force exerted in an observed hand action. The weight judgment of a lifted object during action observation is an easy task which is the case for hand actions as well as for lifting boxes from the ground. Here we investigated whether the cortical representation in M1 for lumbar back muscles is modulated due to the observation of a whole-body lifting movement as it was shown for hand action. We used transcranial magnetic stimulation (TMS) to measure the corticospinal excitability of the m. erector spinae (ES) while subjects visually observed the recorded sequences of a person lifting boxes of different weights from the floor. Consistent with the results regarding hand action the present study reveals a differential modulation of corticospinal excitability despite the relatively small M1 representation of the back also for lifting actions that mainly involve the lower back musculature.

A chimeric prokaryotic-eukaryotic pentameric ligand gated ion channel reveals interactions between the extracellular and transmembrane domains shape neurosteroid modulation.

Science.gov (United States)

Ghosh, Borna; Tsao, Tzu-Wei; Czajkowski, Cynthia

2017-10-01

Pentameric ligand-gated ion channels (pLGICs) are the targets of several clinical and endogenous allosteric modulators including anesthetics and neurosteroids. Molecular mechanisms underlying allosteric drug modulation are poorly understood. Here, we constructed a chimeric pLGIC by fusing the extracellular domain (ECD) of the proton-activated, cation-selective bacterial channel GLIC to the transmembrane domain (TMD) of the human ρ1 chloride-selective GABA A R, and tested the hypothesis that drug actions are regulated locally in the domain that houses its binding site. The chimeric channels were proton-gated and chloride-selective demonstrating the GLIC ECD was functionally coupled to the GABAρ TMD. Channels were blocked by picrotoxin and inhibited by pentobarbital, etomidate and propofol. The point mutation, ρ TMD W328M, conferred positive modulation and direct gating by pentobarbital. The data suggest that the structural machinery mediating general anesthetic modulation resides in the TMD. Proton-activation and neurosteroid modulation of the GLIC-ρ chimeric channels, however, did not simply mimic their respective actions on GLIC and GABAρ revealing that across domain interactions between the ECD and TMD play important roles in determining their actions. Proton-induced current responses were biphasic suggesting that the chimeric channels contain an additional proton sensor. Neurosteroid modulation of the GLIC-ρ chimeric channels by the stereoisomers, 5α-THDOC and 5β-THDOC, were swapped compared to their actions on GABAρ indicating that positive versus negative neurosteroid modulation is not encoded solely in the TMD nor by neurosteroid isomer structure but is dependent on specific interdomain connections between the ECD and TMD. Our data reveal a new mechanism for shaping neurosteroid modulation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Action experience, more than observation, influences mu rhythm desynchronization.

Directory of Open Access Journals (Sweden)

Erin N Cannon

Full Text Available Since the discovery of mirror neurons in premotor and parietal areas of the macaque monkey, the idea that action and perception may share the same neural code has been of central interest in social, developmental, and cognitive neurosciences. A fundamental question concerns how a putative human mirror neuron system may be tuned to the motor experiences of the individual. The current study tested the hypothesis that prior motor experience modulated the sensorimotor mu and beta rhythms. Specifically, we hypothesized that these sensorimotor rhythms would be more desynchronized after active motor experience compared to passive observation experience. To test our hypothesis, we collected EEG from adult participants during the observation of a relatively novel action: an experimenter used a claw-like tool to pick up a toy. Prior to EEG collection, we trained one group of adults to perform this action with the tool (performers. A second group comprised trained video coders, who only had experience observing the action (observers. Both the performers and the observers had no prior motor and visual experience with the action. A third group of novices was also tested. Performers exhibited the greatest mu rhythm desynchronization in the 8-13 Hz band, particularly in the right hemisphere compared to observers and novices. This study is the first to contrast active tool-use experience and observation experience in the mu rhythm and to show modulation with relatively shorter amounts of experience than prior mirror neuron expertise studies. These findings are discussed with respect to its broader implication as a neural signature for a mechanism of early social learning.

The importance of sensory integration processes for action cascading

Science.gov (United States)

Gohil, Krutika; Stock, Ann-Kathrin; Beste, Christian

2015-01-01

Dual tasking or action cascading is essential in everyday life and often investigated using tasks presenting stimuli in different sensory modalities. Findings obtained with multimodal tasks are often broadly generalized, but until today, it has remained unclear whether multimodal integration affects performance in action cascading or the underlying neurophysiology. To bridge this gap, we asked healthy young adults to complete a stop-change paradigm which presented different stimuli in either one or two modalities while recording behavioral and neurophysiological data. Bimodal stimulus presentation prolonged response times and affected bottom-up and top-down guided attentional processes as reflected by the P1 and N1, respectively. However, the most important effect was the modulation of response selection processes reflected by the P3 suggesting that a potentially different way of forming task goals operates during action cascading in bimodal vs. unimodal tasks. When two modalities are involved, separate task goals need to be formed while a conjoint task goal may be generated when all stimuli are presented in the same modality. On a systems level, these processes seem to be related to the modulation of activity in fronto-polar regions (BA10) as well as Broca's area (BA44). PMID:25820681

Action-based effects on music perception.

Science.gov (United States)

Maes, Pieter-Jan; Leman, Marc; Palmer, Caroline; Wanderley, Marcelo M

2014-01-03

The classical, disembodied approach to music cognition conceptualizes action and perception as separate, peripheral processes. In contrast, embodied accounts of music cognition emphasize the central role of the close coupling of action and perception. It is a commonly established fact that perception spurs action tendencies. We present a theoretical framework that captures the ways in which the human motor system and its actions can reciprocally influence the perception of music. The cornerstone of this framework is the common coding theory, postulating a representational overlap in the brain between the planning, the execution, and the perception of movement. The integration of action and perception in so-called internal models is explained as a result of associative learning processes. Characteristic of internal models is that they allow intended or perceived sensory states to be transferred into corresponding motor commands (inverse modeling), and vice versa, to predict the sensory outcomes of planned actions (forward modeling). Embodied accounts typically refer to inverse modeling to explain action effects on music perception (Leman, 2007). We extend this account by pinpointing forward modeling as an alternative mechanism by which action can modulate perception. We provide an extensive overview of recent empirical evidence in support of this idea. Additionally, we demonstrate that motor dysfunctions can cause perceptual disabilities, supporting the main idea of the paper that the human motor system plays a functional role in auditory perception. The finding that music perception is shaped by the human motor system and its actions suggests that the musical mind is highly embodied. However, we advocate for a more radical approach to embodied (music) cognition in the sense that it needs to be considered as a dynamical process, in which aspects of action, perception, introspection, and social interaction are of crucial importance.

Action-based effects on music perception

Science.gov (United States)

Maes, Pieter-Jan; Leman, Marc; Palmer, Caroline; Wanderley, Marcelo M.

2013-01-01

The classical, disembodied approach to music cognition conceptualizes action and perception as separate, peripheral processes. In contrast, embodied accounts of music cognition emphasize the central role of the close coupling of action and perception. It is a commonly established fact that perception spurs action tendencies. We present a theoretical framework that captures the ways in which the human motor system and its actions can reciprocally influence the perception of music. The cornerstone of this framework is the common coding theory, postulating a representational overlap in the brain between the planning, the execution, and the perception of movement. The integration of action and perception in so-called internal models is explained as a result of associative learning processes. Characteristic of internal models is that they allow intended or perceived sensory states to be transferred into corresponding motor commands (inverse modeling), and vice versa, to predict the sensory outcomes of planned actions (forward modeling). Embodied accounts typically refer to inverse modeling to explain action effects on music perception (Leman, 2007). We extend this account by pinpointing forward modeling as an alternative mechanism by which action can modulate perception. We provide an extensive overview of recent empirical evidence in support of this idea. Additionally, we demonstrate that motor dysfunctions can cause perceptual disabilities, supporting the main idea of the paper that the human motor system plays a functional role in auditory perception. The finding that music perception is shaped by the human motor system and its actions suggests that the musical mind is highly embodied. However, we advocate for a more radical approach to embodied (music) cognition in the sense that it needs to be considered as a dynamical process, in which aspects of action, perception, introspection, and social interaction are of crucial importance. PMID:24454299

Action-based effects on music perception

Directory of Open Access Journals (Sweden)

Pieter-Jan eMaes

2014-01-01

Full Text Available The classical, disembodied approach to music cognition conceptualizes action and perception as separate, peripheral phenomena. In contrast, embodied accounts to music cognition emphasize the central role of the close coupling of action and perception. It is a commonly established fact that perception spurs action tendencies. We present a theoretical framework capturing the ways that the human motor system, and the actions it produces, can reciprocally influence the perception of music. The cornerstone of this framework is the common coding theory postulating a representational overlap in the brain between the planning, the execution, and the perception of movement. The integration of action and perception in so-called internal models is explained as a result of associative learning processes. Characteristic of internal models is that they allow intended or perceived sensory states to be transferred into corresponding motor commands (inverse modelling, and vice versa, to predict the sensory outcomes of planned actions (forward modelling. Embodied accounts typically adhere to inverse modelling to explain action effects on music perception (Leman, 2007. We extent this account by pinpointing forward modelling as an alternative mechanism by which action can modulate perception. We provide an extensive overview of recent empirical evidence in support of this idea. Additionally, we demonstrate that motor dysfunctions can cause perceptual disabilities, supporting the main idea of the paper that the human motor system plays a functional role in auditory perception. The finding that music perception is shaped by the human motor system, and the action it produces, suggests that the musical mind is highly embodied. However, we advocate for a more radical approach to embodied (music cognition in the sense that it needs to be considered as a dynamic process, in which aspects of action, perception, introspection, and social interaction are of crucial

Selective Negative Allosteric Modulation Of Metabotropic Glutamate Receptors - A Structural Perspective of Ligands and Mutants

DEFF Research Database (Denmark)

Harpsøe, Kasper; Isberg, Vignir; Tehan, Benjamin G

2015-01-01

modulators. In this analysis, we make the first comprehensive structural comparison of all metabotropic glutamate receptors, placing selective negative allosteric modulators and critical mutants into the detailed context of the receptor binding sites. A better understanding of how the different m......Glu allosteric modulator binding modes relates to selective pharmacological actions will be very valuable for rational design of safer drugs....

HiRITER - An evaluation tool to reduce the adverse effect of inappropriate human actions in nuclear power plants

International Nuclear Information System (INIS)

Park, J.; Jung, W.; Kim, J.; Kim, S.; Heo, G.

2012-01-01

From end-users to regulatory bodies, it is widely recognized that human-induced events including inappropriate human actions are one of the most crucial sources degrading the overall safety of nuclear power plants (NPPs). This means that a systematic framework through which inappropriate human actions can be effectively identified is necessary to enhance the safety of NPPs. For this reason, HiRITER (High Risk Inducible Task Evaluator) has been developed, which is able to evaluate the effect of inappropriate human actions on risk as well as performance. To this end, HiRITER integrates three modules that have distinctive roles: human error prediction module that is able to determine the types of failure modes resulting from inappropriate human actions with the associated daily task, performance evaluation module that computes the loss of electric power due to the change of component configurations caused by human error and risk evaluation module that clarifies whether or not the propagation of human error can trigger an unexpected shutdown of NPPs. In addition, a couple of real events that had occurred in domestic NPPs are simulated in order to validate the feasibility of HiRITER. As a result, it is observed that the results of HiRITER are largely congruent with those of real events. Therefore, although a huge amount of additional effort is indispensable to enhance the overall accuracy of estimated results, it is expected that HiRITER could be a good starting point to reduce the adverse effect of inappropriate human actions in NPPs

A neural network model of causative actions

Directory of Open Access Journals (Sweden)

Jeremy eLee-Hand

2015-06-01

Full Text Available A common idea in models of action representation is that actions are represented in terms of their perceptual effects (see e.g. Prinz, 1997; Hommel et al., 2001; Sahin et al., 2007; Umilta et al., 2008; Hommel et al., 2013. In this paper we extend existing models of effect-based action representations to account for a novel distinction. Some actions bring about effects that are independent events in their own right: for instance, if John 'smashes' a cup, he brings about the event of 'the cup smashing'. Other actions do not bring about such effects. For instance, if John 'grabs' a cup, this action does not cause the cup to 'do' anything: a grab action has well-defined perceptual effects, but these are not registered by the perceptual system that detects independent events involving external objects in the world. In our model, effect-based actions are implemented in several distinct neural circuits, which are organised into a hierarchy based on the complexity of their associated perceptual effects. The circuit at the top of this hierarchy is responsible for actions that bring about independently perceivable events. This circuit receives input from the perceptual module that recognises arbitrary events taking place in the world, and learns movements that reliably cause such events. We assess our model against existing experimental observations about effect-based motor representations, and make some novel experimental predictions. We also consider the possibility that the 'causative actions' circuit in our model can be identified with a motor pathway reported in other work, specialising in 'functional' actions on manipulable tools (Bub et al., 2008; Binkofski and Buxbaum, 2013.

A neural network model of causative actions.

Science.gov (United States)

Lee-Hand, Jeremy; Knott, Alistair

2015-01-01

A common idea in models of action representation is that actions are represented in terms of their perceptual effects (see e.g., Prinz, 1997; Hommel et al., 2001; Sahin et al., 2007; Umiltà et al., 2008; Hommel, 2013). In this paper we extend existing models of effect-based action representations to account for a novel distinction. Some actions bring about effects that are independent events in their own right: for instance, if John smashes a cup, he brings about the event of the cup smashing. Other actions do not bring about such effects. For instance, if John grabs a cup, this action does not cause the cup to "do" anything: a grab action has well-defined perceptual effects, but these are not registered by the perceptual system that detects independent events involving external objects in the world. In our model, effect-based actions are implemented in several distinct neural circuits, which are organized into a hierarchy based on the complexity of their associated perceptual effects. The circuit at the top of this hierarchy is responsible for actions that bring about independently perceivable events. This circuit receives input from the perceptual module that recognizes arbitrary events taking place in the world, and learns movements that reliably cause such events. We assess our model against existing experimental observations about effect-based motor representations, and make some novel experimental predictions. We also consider the possibility that the "causative actions" circuit in our model can be identified with a motor pathway reported in other work, specializing in "functional" actions on manipulable tools (Bub et al., 2008; Binkofski and Buxbaum, 2013).

Self-Inhibiting Modules Can Self-Organize as a Brain of a Robot: A Conjecture

Directory of Open Access Journals (Sweden)

J. Negrete-Martínez

2006-01-01

Full Text Available In this article we describe a new robot control architecture on the basis of self-organization of self-inhibiting modules. The architecture can generate a complex behaviour repertoire. The repertoire can be performance-enhanced or increased by modular poly-functionality and/or by addition of new modules. This architecture is illustrated in a robot consisting of a car carrying an arm with a grasping tool. In the robot, each module drives either a joint motor or a pair of wheel motors. Every module estimates the distance from a sensor placed in the tool to a beacon. If the distance is smaller than a previously measured distance, the module drives its motor in the same direction of its prior movement. If the distance is larger, the next movement will be in the opposite direction; but, if the movement produces no significant change in distance, the module self-inhibits. A self-organization emerges: any module can be the next to take control of the motor activity of the robot once one module self-inhibits. A single module is active at a given time. The modules are implemented as computer procedures and their turn for participation scheduled by an endless program. The overall behaviour of the robot corresponds to a reaching attention behaviour. It is easily switched to a running-away attention behaviour by changing the sign of the same parameter in each module. The addition of a “sensor-gain attenuation reflex” module and of a “light-orientation reflex” module provides an increase of the behavioural attention repertoire and performance enhancement. Since scheduling a module does not necessarily produce its sustained intervention, the architecture of the “brain” is actually providing action induction rather than action selection.

Multiple sclerosis, relapses, and the mechanism of action of adrenocorticotropic hormone (ACTH

Directory of Open Access Journals (Sweden)

Amy ePerrin Ross

2013-03-01

Full Text Available Relapses in multiple sclerosis (MS are disruptive and frequently disabling for patients, and their treatment is often a challenge to clinicians. Despite progress in the understanding of the pathophysiology of MS and development of new treatments for long-term management of MS, options for treating relapses have not changed substantially over the past few decades. Corticosteroids, a component of the HPA axis that modulate immune responses and reduce inflammation, are currently the mainstay of relapse treatment. Adrenocorticotropic hormone (ACTH gel is another treatment option. Although it has long been assumed that the efficacy of ACTH in treating relapses depends on the peptide’s ability to increase endogenous corticosteroid production, evidence from research on the melanocortin system suggests that steroidogenesis may only partly account for ACTH influences. Indeed, the melanocortin peptides (ACTH and α-, β-, γ-melanocyte-stimulating hormones [MSH] and their receptors (MCRs exert multiple actions, including modulation of inflammatory and immune mediator production. Melanocortin receptors are widely distributed within the central nervous system and in peripheral tissues including immune cells (eg, macrophages. This suggests that the mechanism of action of ACTH includes not only steroid-mediated indirect effects, but also direct anti-inflammatory and immune-modulating actions via the melanocortin system. An increased understanding of the role of the melanocortin system, particularly ACTH, in the immune and inflammatory processes underlying relapses may help to improve relapse management.

Arqueología en Egipto y Sudán. El proyecto de investigación de Ehnasya el Medina (Heracleópolis Magna, Egipto

Directory of Open Access Journals (Sweden)

Pérez Die, María del Carmen

1998-12-01

Full Text Available Not available.La presencia española en excavaciones en Egipto y Sudán es relativamente reciente. Se inició en la década de los años sesenta mediante la participación en la campaña de salvamento de Nubia y ha continuado hasta la actualidad, gracias a una serie de proyectos de investigación arqueológica como el que se desarrolla en el yacimiento de Ehnasya el Medina (Heracleópolis Magna, que está proporcionando conclusiones fundamentales para la historia de Egipto. Existen, también, otros proyectos que muestran el interés por la egiptología, así como el alto desarrollo que esta ciencia ha alcanzado en nuestro país.

Fish oil curtails the human action potential dome in a heterogeneous manner: Implication for arrhythmogenesis

NARCIS (Netherlands)

Verkerk, Arie O.; den Ruijter, Hester M.; de Jonge, Nicolaas; Coronel, Ruben

2009-01-01

Omega-3 polyunsaturated fatty acids (omega3-PUFAs) from fish oil modulate various ion channels, including the L-type calcium current (I(Ca,L)). As a result, fish oil shortens the cardiac action potential and may cause a loss of the dome of the action potential (AP). Under conditions of increased

A shortcut to wide-ranging biological actions of dietary polyphenols: modulation of the nitrate-nitrite-nitric oxide pathway in the gut.

Science.gov (United States)

Rocha, Bárbara S; Nunes, Carla; Pereira, Cassilda; Barbosa, Rui M; Laranjinha, João

2014-08-01

Dietary polyphenols are complex, natural compounds with recognized health benefits. Initially attractive to the biomedical area due to their in vitro antioxidant properties, the biological implications of polyphenols are now known to be far from their acute ability to scavenge free radicals but rather to modulate redox signaling pathways. Actually, it is now recognized that dietary polyphenols are extensively metabolized in vivo and that the chemical, biophysical and biological properties of their metabolites are, in most cases, quite different from the ones of the parent molecules. Hence, the study of the metabolic, absorptive and signaling pathways of both phenolics and derivatives has become a major issue. In this paper we propose a short-cut for the systemic effects of polyphenols in connection with nitric oxide (˙NO) biology. This free radical is a ubiquitous signaling molecule with pivotal functions in vivo. It is produced through an enzymatic pathway and also through the reduction of dietary nitrate and nitrite in the human stomach. At acidic gastric pH, dietary polyphenols, in the form they are conveyed in foods and at high concentration, not only promote nitrite reduction to ˙NO but also embark in a complex network of chemical reactions to produce higher nitrogen oxides with signaling functions, namely by inducing post-translational modifications. Modified endogenous molecules, such as nitrated proteins and lipids, acquire important physiological functions. Thus, local and systemic effects of ˙NO such as modulation of vascular tone, mucus production in the gut and protection against ischemia-reperfusion injury are, in this sense, triggered by dietary polyphenols. Evidence to support the signaling and biological effects of polyphenols by modulation of the nitrate-nitrite-NO pathway will be herein provided and discussed. General actions of polyphenols encompassing absorption and metabolism in the intestine/liver are short-cut via the production of

Pb2+ Modulates Ca2+ Membrane Permeability In Paramecium

Science.gov (United States)

Bernal-Martínez, Juan; Ortega Soto, Arturo

2004-09-01

Intracellular recording experiments in current clamp configuration were done to evaluate whether Pb2+ modulates ionic membrane permeability in the fresh water Paramecium tetraurelia. It was found that Pb2+ triggers in a dose-dependent manner, a burst of spontaneous action potentials followed by a robust and sustained after hyper-polarization. In addition, Pb2+ increased the frequency of firing the spontaneous Ca2+-Action Potential and also, the duration of Ca2+-Action Potential, in a dose and reversibly-dependent manner. These results suggest that Pb2+ increases calcium membrane permeability of Paramecium and probably activates a calcium-dependent-potassium conductance in the ciliate.

Wireless cardiac action potential transmission with ultrasonically inserted silicon microprobes

International Nuclear Information System (INIS)

Shen, C J; Ramkumar, A; Lal, A; Gilmour, R F Jr

2011-01-01

This paper reports on the integration of ultrasonically inserted horn-shaped cardiac probes with wireless transmission of 3D cardiac action potential measurement for applications in ex vivo preparations such as monitoring the onset of ventricular fibrillation. Ultrasonically inserted silicon horn probes permit reduced penetration force during insertion, allowing silicon, a brittle material, to penetrate cardiac tissue. The probes also allow recording from multiple sites that are lithographically defined. An application-specific integrated circuit has been designed with a 40 dB amplifying stage and a frequency modulating oscillator at 95 MHz to wirelessly transmit the recorded action potentials. This ultrasonically inserted microprobe wireless system demonstrates the initial results in wireless monitoring of 3D action potential propagation, and the extraction of parameters of interest including the action potential duration and diastolic interval

Influence of pH and media composition on suspension stability of silver, zinc oxide, and titanium dioxide nanoparticles and immobilization of Daphnia magna under guideline testing conditions.

Science.gov (United States)

Cupi, Denisa; Hartmann, Nanna B; Baun, Anders

2016-05-01

In aquatic toxicity testing of engineered nanoparticles (ENPs) the process of agglomeration is very important as it may alter bioavailability and toxicity. In the present study, we aimed to identify test conditions that are favorable for maintaining stable ENP suspensions. We evaluated the influence of key environmental parameters: pH (2-12) and ionic strength using M7, Soft EPA (S EPA) medium, and Very Soft EPA (VS EPA) medium; and observed the influence of these parameters on zeta potential, zeta average, and acute immobilization of Daphnia magna for three different ENPs. Despite being sterically stabilized, test suspensions of silver (Ag) ENPs formed large agglomerates in both VS EPA and M7 media; and toxicity was found to be higher in VS EPA medium due to increased dissolution. Low-agglomerate suspensions for zinc oxide (ZnO) could be obtained at pH 7 in VS EPA medium, but the increase in dissolution caused higher toxicity than in M7 medium. Titanium dioxide (TiO2) ENPs had a point of zero charge in the range of pH 7-8. At pH 7 in VS EPA, agglomerates with smaller hydrodynamic diameters (~200nm) were present compared to the high ionic strength M7 medium where hydrodynamic diameters reached micrometer range. The stable suspensions of TiO2 ENPs caused immobilization of D. magna, 48-h EC50 value of 13.7mgL(-1) (95% CI, 2.4mg-79.1mgL(-1)); whereas no toxicity was seen in the unstable, highly agglomerated M7 medium suspensions, 48-h EC50 >100mgL(-1). The current study provides a preliminary approach for methodology in testing and assessing stability and toxicity of ENPs in aquatic toxicity tests of regulatory relevance. Copyright © 2016 Elsevier Inc. All rights reserved.

Distinct spatio-temporal profiles of beta-oscillations within visual and sensorimotor areas during action recognition as revealed by MEG.

Science.gov (United States)

Pavlidou, Anastasia; Schnitzler, Alfons; Lange, Joachim

2014-05-01

The neural correlates of action recognition have been widely studied in visual and sensorimotor areas of the human brain. However, the role of neuronal oscillations involved during the process of action recognition remains unclear. Here, we were interested in how the plausibility of an action modulates neuronal oscillations in visual and sensorimotor areas. Subjects viewed point-light displays (PLDs) of biomechanically plausible and implausible versions of the same actions. Using magnetoencephalography (MEG), we examined dynamic changes of oscillatory activity during these action recognition processes. While both actions elicited oscillatory activity in visual and sensorimotor areas in several frequency bands, a significant difference was confined to the beta-band (∼20 Hz). An increase of power for plausible actions was observed in left temporal, parieto-occipital and sensorimotor areas of the brain, in the beta-band in successive order between 1650 and 2650 msec. These distinct spatio-temporal beta-band profiles suggest that the action recognition process is modulated by the degree of biomechanical plausibility of the action, and that spectral power in the beta-band may provide a functional interaction between visual and sensorimotor areas in humans. Copyright © 2014 Elsevier Ltd. All rights reserved.

Waste Receiving and Processing (WRAP) Module 1 Hazards Assessment

Energy Technology Data Exchange (ETDEWEB)

CAMPBELL, L.R.

1999-09-29

This document establishes the technical basis in support of Emergency Planning activities for the WRAP Module 1 Facility on the Hanford Site. Through this document, the technical basis for the development of facility specific Emergency Action Levels and Emergency Planning Zone is demonstrated.

Waste Receiving and Processing (WRAP) Module 1 Hazards Assessment

International Nuclear Information System (INIS)

CAMPBELL, L.R.

1999-01-01

This document establishes the technical basis in support of Emergency Planning activities for the WRAP Module 1 Facility on the Hanford Site. Through this document, the technical basis for the development of facility specific Emergency Action Levels and Emergency Planning Zone is demonstrated

Bioavailability of benzo(a)pyrene and dehydroabietic acid from a few lake waters containing varying dissolved organic carbon concentrations to Daphnia magna

International Nuclear Information System (INIS)

Oikari, A.; Kukkonen, J.

1990-01-01

Dissolved organic carbon (DOC) in natural waters consists of a great variety of organic molecules. Some of these molecules have been identified but most of them cannot be identified. This unidentified group of heterogeneous organic macromolecules is considered as humic substances. The role of humic substances in water chemistry and in aquatic toxicology is receiving increasing attention. The effects of DOC on the bioavailability of organic pollutants have been demonstrated in several studies. A decreased bioavailability has been demonstrated in most cases. Both the quantity and the quality of DOC are suggested determinants of this apparent ecotoxicological buffer of inland waters worldwide. In this study, the authors measured the bioaccumulation of benzo(a)pyrene (BaP) and dehydroabietic acid (DHAA) in Daphnia magna using a wide range of naturally occurring DOC levels. Another objective was to associate the reduced bioavailability with the chemical characteristics of water and DOC

Rational modulation of neuronal processing with applied electric fields.

Science.gov (United States)

Bikson, Marom; Radman, Thomas; Datta, Abhishek

2006-01-01

Traditional approaches to electrical stimulation, using trains of supra-threshold pulses to trigger action potentials, may be replaced or augmented by using 'rational' sub-threshold stimulation protocols that incorporate knowledge of single neuron geometry, inhomogeneous tissue properties, and nervous system information coding. Sub-threshold stimulation, at intensities (well) below those sufficient to trigger action potentials, may none-the-less exert a profound effect on brain function through modulation of concomitant neuronal activity. For example, small DC fields may coherently polarize a network of neurons and thus modulate the simultaneous processing of afferent synaptic input as well as resulting changes in synaptic plasticity. Through 'activity-dependent plasticity', sub-threshold fields may allow specific targeting of pathological networks and are thus particularly suitable to overcome the poor anatomical focus of noninvasive (transcranial) electrical stimulation. Additional approaches to improve targeting in transcranial stimulation using novel electrode configurations are also introduced.

How Perception Guides Action: Figure-Ground Segmentation Modulates Integration of Context Features into S-R Episodes

Science.gov (United States)

Frings, Christian; Rothermund, Klaus

2017-01-01

Perception and action are closely related. Responses are assumed to be represented in terms of their perceptual effects, allowing direct links between action and perception. In this regard, the integration of features of stimuli (S) and responses (R) into S-R bindings is a key mechanism for action control. Previous research focused on the…

Distribution in rat tissues of modulator-binding protein of particulate nature

International Nuclear Information System (INIS)

Sobue, K.; Muramoto, Y.; Kakiuchi, S.; Yamazaki, R.

1979-01-01

Studies on Ca 2+ -activatable cyclic nucleotide phosphodiesterase led to the discovery of a protein modulator that is required for the activation of this enzyme by Ca 2+ . Later, this protein has been shown to cause the Ca 2+ -dependent activation of several enzymes that include phosphodiesterase, adenylate cyclase, a protein kinase from muscles, phosphorylase b kinase, actomyosin ATPase, membranous ATPase from erythrocytes and nerve synapses. Thus, modulator protein appears to be an intracellular mediator of actions of Ca 2+ . The present work shows the distribution of this particulate modulator-binding component in rat tissues. This paper also describes the labeling of modulator protein with tritium without deteriorating its biological activities and application of this 3 H-modulator protein to the determination of the Ca ++ dependent binding of modulator protein with membranous protein. This technique proves to be useful in studying enzymes or proteins whose functions are regulated by Ca ++ /modulator protein system. (Auth.)

Relationship between the energy status of Daphnia magna and its sensitivity to environmental stress

International Nuclear Information System (INIS)

Smolders, Roel; Baillieul, Marc; Blust, Ronny

2005-01-01

This work tested the hypothesis that animals with a high energy status are more successful in dealing with stress than animals with a low energy status. Daphnids (Daphnia magna) were reared for 2 weeks in four different concentrations of food. Survival was not affected by food supply, and growth and reproduction increased with increasing food ration. This increase correlated well with the energy status, as was measured by scope for growth on day 15. After 2 weeks, the daphnids in the four different food ration groups were exposed for another 2 weeks to a range of increased salinities or cadmium concentrations, while remaining in their respective food concentrations. In the salinity groups, survival, growth, or reproduction were not influenced at low salinities. Exposure to higher salinity significantly decreased survival and reproduction, but this decrease was more pronounced in the highest food concentrations. In the cadmium exposed daphnids, cadmium content increased with increasing exposure concentrations, but accumulation was independent of food rations. Cadmium exposure significantly decreased survival, growth, and reproduction and this decrease again was more pronounced with increasing food concentration. Thus, the high energy status of the daphnids from the high food concentrations at the start of the exposure did not provide an increased capacity to cope with additional stress. Instead, the sensitivity of the daphnids to stress increased with increasing food ration. This increased sensitivity is likely to be the result of a change in life history from emphasizing survival at low food supply to stressing reproduction at high food supply

The cellular immune response of Daphnia magna under host-parasite genetic variation and variation in initial dose.

Science.gov (United States)

Auld, Stuart K J R; Edel, Kai H; Little, Tom J

2012-10-01

In invertebrate-parasite systems, the likelihood of infection following parasite exposure is often dependent on the specific combination of host and parasite genotypes (termed genetic specificity). Genetic specificity can maintain diversity in host and parasite populations and is a major component of the Red Queen hypothesis. However, invertebrate immune systems are thought to only distinguish between broad classes of parasite. Using a natural host-parasite system with a well-established pattern of genetic specificity, the crustacean Daphnia magna and its bacterial parasite Pasteuria ramosa, we found that only hosts from susceptible host-parasite genetic combinations mounted a cellular response following exposure to the parasite. These data are compatible with the hypothesis that genetic specificity is attributable to barrier defenses at the site of infection (the gut), and that the systemic immune response is general, reporting the number of parasite spores entering the hemocoel. Further supporting this, we found that larger cellular responses occurred at higher initial parasite doses. By studying the natural infection route, where parasites must pass barrier defenses before interacting with systemic immune responses, these data shed light on which components of invertebrate defense underlie genetic specificity. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.

Hazard assessment for a pharmaceutical mixture detected in the upper Tennessee River using Daphnia magna

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D. Wolfe

2015-01-01

Full Text Available Widespread use of pharmaceuticals has resulted in mixture concentrations ranging from mg/L in effluent to µg/L concentrations in surface water. In a 2008 study, 13 pharmaceuticals, ranging in amounts from 0.0028 to 0.1757 µg/l, were identified in the Tennessee River, USA and its tributaries. In order to address the need for risk assessment of environmentally relevant pharmaceutical mixtures, Daphnia magna 21-d life cycle tests were performed on a mixture of 11 of the 13 pharmaceuticals as well as on the individual components of the mixture. Mixture exposures were based on the same initial ratios of individual compounds, up to 1000x the initial mixture concentrations.  The endpoints of mortality, time to first brood, size, and fecundity were the assessed.  The LOEC of the 11- pharmaceutical mixture was determined to be 100x greater than the measured mixture concentration detected in the Tennessee River, with the NOEC being 75x that of the measured mixture.  Single concentrations of pharmaceuticals within the mixture up to the 100x LOEC were not statistically different from control for any of the assessed endpoints.  Thus, no single pharmaceutical was deemed predominately responsible for the mixture toxicity at the concentrations tested. While mixtures of pharmaceuticals are common in many systems, based on the findings of the present study, they may not pose a significant acute or chronic hazard to aquatic invertebrates at current concentrations.

Self-modulation and filamentation of electromagnetic waves in a plasma

International Nuclear Information System (INIS)

Bingham, R.; Lashmore-Davies, C.N.

1976-01-01

Self-modulation and filamentation of an electromagnetic wave is considered as a problem of the non-linear interaction between electromagnetic and ion waves. A new electro-magnetic modulational instability is obtained, whose threshold is the same as that of the oscillating two-stream instability. A simple geometrical model is given of filamentation when the non-linearity is due to the ponderomotive force. The relationship between the filamentation and electromagnetic modulational instabilities and other parametric instabilities is considered. In particular, it is shown that both electromagnetic modulational and filamentation instabilities can occur at the critical density where they have the same threshold as the modulational instability of a Langmuir wave. Finally, a conservation relation (a generalization of the Manley-Rowe relation) for the wave action density is obtained for the filamentation instability. This shows clearly that this instability results from a four wave interaction. (author)

Thyroid hormone action: Astrocyte-neuron communication.

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Beatriz eMorte

2014-05-01

Full Text Available Thyroid hormone action is exerted mainly through regulation of gene expression by binding of T3 to the nuclear receptors. T4 plays an important role as a source of intracellular T3 in the central nervous system via the action of the type 2 deiodinase, expressed in the astrocytes. A model of T3 availability to neural cells has been proposed and validated. The model contemplates that brain T3 has a double origin: a fraction is available directly from the circulation, and another is produced locally from T4 in the astrocytes by type 2 deiodinase. The fetal brain depends almost entirely on the T3 generated locally. The contribution of systemic T3 increases subsequently during development to account for approximately 50% of total brain T3 in the late postnatal and adult stages. In this article we review the experimental data in support of this model, and how the factors affecting T3 availability in the brain, such as deiodinases and transporters, play a decisive role in modulating local thyroid hormone action during development.

Responses to amplitude modulated infrared stimuli in the guinea pig inferior colliculus

Science.gov (United States)

Richter, Claus-Peter; Young, Hunter

2013-03-01

Responses of units in the central nucleus of the inferior colliculus of the guinea pig were recorded with tungsten electrodes. The set of data presented here is limited to high stimulus levels. The effect of changing the modulation frequency and the modulation depth was explored for acoustic and laser stimuli. The selected units responded to sinusoidal amplitude modulated (AM) tones, AM trains of clicks, and AM trains of laser pulses with a modulation of their spike discharge. At modulation frequencies of 20 Hz, some units tended to respond with 40 Hz to the acoustic stimuli, but only at 20 Hz for the trains of laser pulses. For all modes of stimulation the responses revealed a dominant response to the first cycle of the modulation, with decreasing number of action potential during successive cycles. While amplitude modulated tone bursts and amplitude modulated trains of acoustic clicks showed similar patterns, the response to trains of laser pulses was different.

A Study of the Modulating Action of Quercetin on Biochemical and Histological Alterations Induced by Lead Exposure in the Liver and Kidney of Rats.

Science.gov (United States)

Mohammed, Ghena M.; Sedky, Azza; Elsawy, Hany

2017-06-30

Lead is a highly toxic metal and a very potent poison. Lead poisoning is a serious condition but can be treated. Quercetin is a flavonoid with many beneficial uses. The aim of the present study was to investigate the possible modulating action of quercetin as a model of an antioxidant against the toxic effects of lead acetate on liver and kidneys of rats. Rats were randomly divided into four groups: (i) saline group (control); (ii) lead group received i.p. lead acetate (20 mg/kg b.w.); (iii) quercetin group received i.p. quercetin (50 mg/kg b.w.); (iv) lead and quercetin group received i.p. lead acetate (20 mg/kg b.w.) followed by i.p. quercetin (50 mg/kg b.w.) for 4 weeks. The lead concentrations were determined in the liver and kidney tissues. Liver marker enzymes, bilirubin, albumin, total protein, creatinine, uric acid and urea, were assessed in the serum and light microscopic studies were performed. The results showed that lead acetate administration was associated with an increase in serum alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST) activities, total bilirubin, creatinine, uric acid, urea levels. Lead accumulation in kidneys and liver tissues was also found, but were associated with decrease in albumin and total protein in comparison with the respective mean values of the control. Lead acetate caused numerous histological alterations in the liver, including chronic inflammation, bilary hyperplasia, edema, congestion, Kupffer cells hyperplasia and hemosiderosis, and in the kidney, including tubular dilation, atrophy of glomerular tuft, widening of urinary space and mild fibroblast. In contrary, administration of lead acetate along with quercetin partially restored the studied parameters to normal values and improved structure of liver and kidney with significant decreases in the severity of histopathological changes when compared with the lead acetate group. In conclusion, treatment with quercetin may provide a

The modulation effects of d-amphetamine and procaine on the spontaneously generated action potentials in the central neuron of snail, Achatina fulica Ferussac.

Science.gov (United States)

Lin, Chia-Hsien; Tsai, Ming-Cheng

2005-05-01

The modulation effects of d-amphetamine and procaine on the spontaneously generated action potentials were studied on the RP1 central neuron of giant African snails (Achatina fulica Ferussac). Extra-cellular application of d-amphetamine or procaine reversibly elicited bursts of potential (BoP). Prazosin, propranolol, atropine or d-tubocurarine did not alter the BoP elicited by either d-amphetamine or procaine. KT-5720 or H89 (protein kinase A inhibitors) blocked d-amphetamine-elicited BoP, whereas they did not block the procaine-elicited BoP. U73122, neomycin (phospholipase C inhibitors) blocked the procaine-elicited BoP, whereas they did not block the d-amphetamine-elicited BoP in the same neuron. These results suggest that BoP elicited by d-amphetamine or procaine were associated with protein kinase A and phospholipase C activity in the neuron.

Nucleus accumbens is involved in human action monitoring: evidence from invasive electrophysiological recordings

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Thomas F Münte

2008-03-01

Full Text Available The Nucleus accumbens (Nacc has been proposed to act as a limbic-motor interface. Here, using invasive intraoperative recordings in an awake patient suffering from obsessive-compulsive disease (OCD, we demonstrate that its activity is modulated by the quality of performance of the subject in a choice reaction time task designed to tap action monitoring processes. Action monitoring, that is, error detection and correction, is thought to be supported by a system involving the dopaminergic midbrain, the basal ganglia, and the medial prefrontal cortex. In surface electrophysiological recordings, action monitoring is indexed by an error-related negativity (ERN appearing time-locked to the erroneous responses and emanating from the medial frontal cortex. In preoperative scalp recordings the patient's ERN was found to be signifi cantly increased compared to a large (n= 83 normal sample, suggesting enhanced action monitoring processes. Intraoperatively, error-related modulations were obtained from the Nacc but not from a site 5 mm above. Importantly, crosscorrelation analysis showed that error-related activity in the Nacc preceded surface activity by 40 ms. We propose that the Nacc is involved in action monitoring, possibly by using error signals from the dopaminergic midbrain to adjust the relative impact of limbic and prefrontal inputs on frontal control systems in order to optimize goal-directed behavior.

Dismissing Attachment Characteristics Dynamically Modulate Brain Networks Subserving Social Aversion

NARCIS (Netherlands)

Krause, Anna Linda; Borchardt, Viola; Li, Meng; van Tol, Marie-Jose; Demenescu, Liliana Ramona; Strauss, Bernhard; Kirchmanny, Helmut; Buchheim, Anna; Metzger, Coraline D.; Nolte, Tobias; Walter, Martin

2016-01-01

Attachment patterns influence actions, thoughts and feeling through a person's "inner working model". Speech charged with attachment-dependent content was proposed to modulate the activation of cognitive-emotional schemata in listeners. We performed a 7 Tesla rest-task-rest functional magnetic

Uncertainty in action-value estimation affects both action choice and learning rate of the choice behaviors of rats.

Science.gov (United States)

Funamizu, Akihiro; Ito, Makoto; Doya, Kenji; Kanzaki, Ryohei; Takahashi, Hirokazu

2012-04-01

The estimation of reward outcomes for action candidates is essential for decision making. In this study, we examined whether and how the uncertainty in reward outcome estimation affects the action choice and learning rate. We designed a choice task in which rats selected either the left-poking or right-poking hole and received a reward of a food pellet stochastically. The reward probabilities of the left and right holes were chosen from six settings (high, 100% vs. 66%; mid, 66% vs. 33%; low, 33% vs. 0% for the left vs. right holes, and the opposites) in every 20-549 trials. We used Bayesian Q-learning models to estimate the time course of the probability distribution of action values and tested if they better explain the behaviors of rats than standard Q-learning models that estimate only the mean of action values. Model comparison by cross-validation revealed that a Bayesian Q-learning model with an asymmetric update for reward and non-reward outcomes fit the choice time course of the rats best. In the action-choice equation of the Bayesian Q-learning model, the estimated coefficient for the variance of action value was positive, meaning that rats were uncertainty seeking. Further analysis of the Bayesian Q-learning model suggested that the uncertainty facilitated the effective learning rate. These results suggest that the rats consider uncertainty in action-value estimation and that they have an uncertainty-seeking action policy and uncertainty-dependent modulation of the effective learning rate. © 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

The Influence of Estrogens on the Biological and Therapeutic Actions of Growth Hormone in the Liver

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Leandro Fernández-Pérez

2012-07-01

Full Text Available GH is main regulator of body growth and composition, somatic development, intermediate metabolism and gender-dependent dimorphism in mammals. The liver is a direct target of estrogens because it expresses estrogen receptors which are connected with development, lipid metabolism and insulin sensitivity, hepatic carcinogenesis, protection from drug-induced toxicity and fertility. In addition, estrogens can modulate GH actions in liver by acting centrally, regulating pituitary GH secretion, and, peripherally, by modulating GHR-JAK2-STAT5 signalling pathway. Therefore, the interactions of estrogens with GH actions in liver are biologically and clinically relevant because disruption of GH signaling may cause alterations of its endocrine, metabolic, and gender differentiated functions and it could be linked to dramatic impact in liver physiology during development as well as in adulthood. Finally, the interplay of estrogens with GH is relevant because physiological roles these hormones have in human, and the widespread exposition of estrogen or estrogen-related compounds in human. This review highlights the importance of these hormones in liver physiology as well as how estrogens modulate GH actions in liver which will help to improve the clinical use of these hormones.

An illusion of control modulates the reluctance to tempt fate

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Chloe L. Swirsky

2011-10-01

Full Text Available The tempting fate effect is that the probability of a fateful outcome is deemed higher following an action that ``tempts'' the outcome than in the absence of such an action. In this paper we evaluate the hypothesis that the effect is due to an illusion of control induced by a causal framing of the situation. Causal frames require that the action make a difference to an outcome and that the action precedes the outcome. If an illusion of control modulates the reluctance to tempt fate, then actions that make a difference to well-being and that occur prior to the outcome should tempt fate most strongly. In Experiments 1--3 we varied whether the action makes a difference and the temporal order of action and outcome. In Experiment 4 we tested whether an action can tempt fate if all outcomes are negative. The results of all four experiments supported our hypothesis that the tempting fate effect depends on a causal construal that gives rise to a false sense of control.

Weight dependent modulation of motor resonance induced by weight estimation during observation of partially occluded lifting actions

NARCIS (Netherlands)

Valchev, Nikola; Zijdewind, Inge; Keysers, Christian; Gazzola, Valeria; Avenanti, Alessio; Maurits, Natasha M.

Seeing others performing an action induces the observers' motor cortex to "resonate" with the observed action. Transcranial magnetic stimulation (TMS) studies suggest that such motor resonance reflects the encoding of various motor features of the observed action, including the apparent motor

Weight dependent modulation of motor resonance induced by weight estimation during observation of partially occluded lifting actions

NARCIS (Netherlands)

Valchev, N.; Zijdewind, I.; Keysers, C.; Gazzola, V.; Avenanti, A.; Maurits, N.M.

2015-01-01

Seeing others performing an action induces the observers' motor cortex to "resonate" with the observed action. Transcranial magnetic stimulation (TMS) studies suggest that such motor resonance reflects the encoding of various motor features of the observed action, including the apparent motor

Development of thresholds of excess toxicity for environmental species and their application to identification of modes of acute toxic action.

Science.gov (United States)

Li, Jin J; Zhang, Xu J; Yang, Yi; Huang, Tao; Li, Chao; Su, Limin; Zhao, Yuan H; Cronin, Mark T D

2018-03-01

The acute toxicity of organic pollutants to fish, Daphnia magna, Tetrahymena pyriformis, and Vibrio fischeri was investigated. The results indicated that the Toxicity Ratio (TR) threshold of log TR =1, which has been based on the distribution of toxicity data to fish, can also be used to discriminate reactive or specifically acting compounds from baseline narcotics for Daphnia magna and Vibrio fischeri. A log TR=0.84 is proposed for Tetrahymena pyriformis following investigation of the relationships between the species sensitivity and the absolute averaged residuals (AAR) between the predicted baseline toxicity and the experimental toxicity. Less inert compounds exhibit relatively higher toxicity to the lower species (Tetrahymena pyriformis and Vibrio fischeri) than the higher species (fish and Daphnia magna). A greater number of less inert compounds with log TR greater than the thresholds was observed for Tetrahymena pyriformis and Vibrio fischeri. This may be attributed to the hydrophilic compounds which may pass more easily through cell membranes than the skin or exoskeleton of organisms and have higher bioconcentration factors in the lower species, leading to higher toxicity. Most of classes of chemical associated with excess toxicity to one species also exhibited excess toxicity to other species, however, a few classes with excess toxicity to one species exhibiting narcotic toxicity to other species and thus may have different MOAs between species. Some ionizable compounds have log TR much lower than one because of the over-estimated log K OW . The factors that influence the toxicity ratio calculated from baseline level are discussed in this paper. Copyright © 2017 Elsevier B.V. All rights reserved.

Gene expression profiling of three different stressors in the water flea Daphnia magna.

Science.gov (United States)

Jansen, Mieke; Vergauwen, Lucia; Vandenbrouck, Tine; Knapen, Dries; Dom, Nathalie; Spanier, Katina I; Cielen, Anke; De Meester, Luc

2013-07-01

Microarrays are an ideal tool to screen for differences in gene expression of thousands of genes simultaneously. However, often commercial arrays are not available. In this study, we performed microarray analyses to evaluate patterns of gene transcription following exposure to two natural and one anthropogenic stressor. cDNA microarrays compiled of three life stage specific and three stressor-specific EST libraries, yielding 1734 different EST sequences, were used. We exposed juveniles of the water flea Daphnia magna for 48, 96 and 144 h to three stressors known to exert strong selection in natural populations of this species i.e. a sublethal concentration of the pesticide carbaryl, infective spores of the endoparasite Pasteuria ramosa, and fish predation risk mimicked by exposure to fish kairomones. A total of 148 gene fragments were differentially expressed compared to the control. Based on a PCA, the exposure treatments were separated into two main groups based on the extent of the transcriptional response: a low and a high (144 h of fish or carbaryl exposure and 96 h of parasite exposure) stress group. Firstly, we observed a general stress-related transcriptional expression profile independent of the treatment characterized by repression of transcripts involved in transcription, translation, signal transduction and energy metabolism. Secondly, we observed treatment-specific responses including signs of migration to deeper water layers in response to fish predation, structural challenge of the cuticle in response to carbaryl exposure, and disturbance of the ATP production in parasite exposure. A third important conclusion is that transcription expression patterns exhibit stress-specific changes over time. Parasite exposure shows the most differentially expressed gene fragments after 96 h. The peak of differentially expressed transcripts came only after 144 h of fish exposure, while carbaryl exposure induced a more stable number of differently expressed gene

Haemoglobin-mediated response to hyper-thermal stress in the keystone species Daphnia magna.

Science.gov (United States)

Cuenca Cambronero, Maria; Zeis, Bettina; Orsini, Luisa

2018-01-01

Anthropogenic global warming has become a major geological and environmental force driving drastic changes in natural ecosystems. Due to the high thermal conductivity of water and the effects of temperature on metabolic processes, freshwater ecosystems are among the most impacted by these changes. The ability to tolerate changes in temperature may determine species long-term survival and fitness. Therefore, it is critical to identify coping mechanisms to thermal and hyper-thermal stress in aquatic organisms. A central regulatory element compensating for changes in oxygen supply and ambient temperature is the respiratory protein haemoglobin (Hb). Here, we quantify Hb plastic and evolutionary response in Daphnia magna subpopulations resurrected from the sedimentary archive of a lake with known history of increase in average temperature and recurrence of heat waves. By measuring constitutive changes in crude Hb protein content among subpopulations, we assessed evolution of the Hb gene family in response to temperature increase. To quantify the contribution of plasticity in the response of this gene family to hyper-thermal stress, we quantified changes in Hb content in all subpopulations under hyper-thermal stress as compared to nonstressful temperature. Further, we tested competitive abilities of genotypes as a function of their Hb content, constitutive and induced. We found that Hb-rich genotypes have superior competitive abilities as compared to Hb-poor genotypes under hyper-thermal stress after a period of acclimation. These findings suggest that whereas long-term adjustment to higher occurrence of heat waves may require a combination of plasticity and genetic adaptation, plasticity is most likely the coping mechanism to hyper-thermal stress in the short term. Our study suggests that with higher occurrence of heat waves, Hb-rich genotypes may be favoured with potential long-term impact on population genetic diversity.

Evidence for a cost of immunity when the crustacean Daphnia magna is exposed to the bacterial pathogen Pasteuria ramosa.

Science.gov (United States)

Little, Tom J; Killick, Stuart C

2007-11-01

The deployment of the immune system has the obvious potential to ameliorate infection outcomes, but immune responses can also harm hosts by either damaging host tissues or monopolizing resources, leading to enhanced mortality. To gain insight into such a 'cost of immunity' when the crustacean Daphnia magna is challenged with the bacterium Pasteuria ramosa, we measured survivorship among hosts that resisted infection following exposure to various strains and doses of the parasite. In the first of two experiments, these exposures were: single exposures with relatively non-aggressive strains, double exposures with non-aggressive strains, and exposure to aggressive strains. Mortality increased across this gradient of exposure. In a second experiment, we varied the dose of the most aggressive P. ramosa strain and found that resisting infection when a large dose was applied resulted in greater mortality than when a medium or low dose was applied. Assuming that resistance is accomplished with an immune response, and that more aggressive parasites and/or larger doses of parasites are more immunostimulatory, these data are compatible with a cost of immunity. Indeed, in terms of survival, resisting parasites can be more harmful than infection.

Action recognition and movement direction discrimination tasks are associated with different adaptation patterns

Directory of Open Access Journals (Sweden)

Stephan eDe La Rosa

2016-02-01

Full Text Available The ability to discriminate between different actions is essential for action recognition and social interaction. Surprisingly previous research has often probed action recognition mechanisms with tasks that did not require participants to discriminate between actions, e.g. left-right direction discrimination tasks. It is not known to what degree visual processes in direction discrimination tasks are also involved in the discrimination of actions, e.g. when telling apart a handshake from a high-five. Here, we examined whether action discrimination is influenced by movement direction and whether direction discrimination depends on the type of action. We used an action adaptation paradigm to target action and direction discrimination specific visual processes. In separate conditions participants visually adapted to forward and backward moving handshake and high-five actions. Participants subsequently either categorized the action or the movement direction of an ambiguous action. The results showed that direction discrimination adaptation effects were modulated by the type of action but action discrimination adaptation effects were unaffected by movement direction. These results suggest that action discrimination and direction categorization rely on partly different visual information. We propose that action discrimination tasks should be considered for the exploration of visual action recognition mechanisms.

Theta oscillations locked to intended actions rhythmically modulate perception.

Science.gov (United States)

Tomassini, Alice; Ambrogioni, Luca; Medendorp, W Pieter; Maris, Eric

2017-07-07

Ongoing brain oscillations are known to influence perception, and to be reset by exogenous stimulations. Voluntary action is also accompanied by prominent rhythmic activity, and recent behavioral evidence suggests that this might be coupled with perception. Here, we reveal the neurophysiological underpinnings of this sensorimotor coupling in humans. We link the trial-by-trial dynamics of EEG oscillatory activity during movement preparation to the corresponding dynamics in perception, for two unrelated visual and motor tasks. The phase of theta oscillations (~4 Hz) predicts perceptual performance, even >1 s before movement. Moreover, theta oscillations are phase-locked to the onset of the movement. Remarkably, the alignment of theta phase and its perceptual relevance unfold with similar non-monotonic profiles, suggesting their relatedness. The present work shows that perception and movement initiation are automatically synchronized since the early stages of motor planning through neuronal oscillatory activity in the theta range.

Molecular responses during cadmium-induced stress in Daphnia magna: Integration of differential gene expression with higher-level effects

Energy Technology Data Exchange (ETDEWEB)

Soetaert, Anneleen [Department of Biology, Laboratory for Ecophysiology, Biochemistry and Toxicology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)]. E-mail: anneleen.soetaert@ua.ac.be; Vandenbrouck, Tine [Department of Biology, Laboratory for Ecophysiology, Biochemistry and Toxicology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Ven, Karlijn van der [Department of Biology, Laboratory for Ecophysiology, Biochemistry and Toxicology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Maras, Marleen [Department of Biology, Laboratory for Ecophysiology, Biochemistry and Toxicology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Remortel, Piet van [Department of Mathematics and Informatics, Intelligent Systems Laboratory, University of Antwerp, Middelheimlaan 1, B-2020 Antwerp (Belgium); Blust, Ronny [Department of Biology, Laboratory for Ecophysiology, Biochemistry and Toxicology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Coen, Wim M. de [Department of Biology, Laboratory for Ecophysiology, Biochemistry and Toxicology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

2007-07-20

DNA microarrays offer great potential in revealing insight into mechanistic toxicity of contaminants. The aim of the present study was (i) to gain insight in concentration- and time-dependent cadmium-induced molecular responses by using a customized Daphnia magna microarray, and (ii) to compare the gene expression profiles with effects at higher levels of biological organization (e.g. total energy budget and growth). Daphnids were exposed to three cadmium concentrations (nominal value of 10, 50, 100 {mu}g/l) for two time intervals (48 and 96 h). In general, dynamic expression patterns were obtained with a clear increase of gene expression changes at higher concentrations and longer exposure duration. Microarray analysis revealed cadmium affected molecular pathways associated with processes such as digestion, oxygen transport, cuticula metabolism and embryo development. These effects were compared with higher-level effects (energy budgets and growth). For instance, next to reduced energy budgets due to a decline in lipid, carbohydrate and protein content, we found an up-regulated expression of genes related to digestive processes (e.g. {alpha}-esterase, cellulase, {alpha}-amylase). Furthermore, cadmium affected the expression of genes coding for proteins involved in molecular pathways associated with immune response, stress response, cell adhesion, visual perception and signal transduction in the present study.

Who benefits from reduced reproduction in parasitized hosts? An experimental test using the Pasteuria ramosa-Daphnia magna system.

Science.gov (United States)

Mageroy, Jon H; Grepperud, Eldfrid J; Jensen, Knut Helge

2011-12-01

We investigated whether parasites or hosts benefit from reduced reproduction in infected hosts. When parasites castrate their hosts, the regain of host reproduction is necessary for castration to be a host adaptation. When infecting Daphnia magna with Pasteuria ramosa, in a lake water based medium, 49 2% of the castrated females regained reproduction. We investigated the relationship between castration level, and parasite and host fitness proxies to determine the adaptive value of host castration. Hosts which regained reproduction contained less spores and had a higher lifetime reproduction than permanently castrated hosts. We also found a negative correlation between parasite and host lifetime reproduction. For hosts which regained reproduction we found no optimal level of castration associated with lifetime reproduction. These results support the view that host castration only is adaptive to the parasite in this system. In addition, we suggest that permanent castration might not be the norm under natural conditions in this system. Finally, we argue that a reduction in host reproduction is more likely to evolve as a property favouring parasites rather than hosts. To our knowledge this is the only experimental study to investigate the adaptive value of reduced host reproduction when castrated hosts can regain reproduction.

Comparison between two clones of Daphnia magna: Effects of multigenerational cadmium exposure on toxicity, individual fitness, and biokinetics

International Nuclear Information System (INIS)

Guan Rui; Wang Wenxiong

2006-01-01

We investigated the effects of genotype (two different clones) and multigenerational Cd-exposure history on Cd toxicity, individual fitness, and biokinetics in populations of a freshwater cladoceran Daphnia magna. The adults of the tolerant (T) clone had longer mean-survival-time than the sensitive (S) clone in both control groups (without Cd-exposure) and continuous Cd-exposure groups, but the two clones showed comparable resistances to acute Cd stress in the recovery groups. The body concentration of metallothionein (MT) played a critical role in handling Cd stress, which mainly accounted for the significant difference between the two clones in terms of survival distribution. High comparability of these two clones in individual fitness parameters and biokinetics suggested that these parameters are unlikely driven by genetic variation. For each specific clone, continuous Cd-exposure inhibited the animal growth, elevated the MT induction, and increased the Cd uptake rate (ingestion rate, assimilation efficiency from dietary phase, and uptake rate from dissolved phase), all of which enhanced the weight-specific Cd accumulation in daphnids' bodies. The strong dependence of biokinetic parameters on environmental factors (e.g., food concentrations, pH, dissolved or dietary metal concentration, and metal exposure histories) rather than on genotypes implied the great potential of using biokinetics in inter-lab comparisons and environmental risk assessments

Comparison between two clones of Daphnia magna: effects of multigenerational cadmium exposure on toxicity, individual fitness, and biokinetics.

Science.gov (United States)

Guan, Rui; Wang, Wen-Xiong

2006-03-10

We investigated the effects of genotype (two different clones) and multigenerational Cd-exposure history on Cd toxicity, individual fitness, and biokinetics in populations of a freshwater cladoceran Daphnia magna. The adults of the tolerant (T) clone had longer mean-survival-time than the sensitive (S) clone in both control groups (without Cd-exposure) and continuous Cd-exposure groups, but the two clones showed comparable resistances to acute Cd stress in the recovery groups. The body concentration of metallothionein (MT) played a critical role in handling Cd stress, which mainly accounted for the significant difference between the two clones in terms of survival distribution. High comparability of these two clones in individual fitness parameters and biokinetics suggested that these parameters are unlikely driven by genetic variation. For each specific clone, continuous Cd-exposure inhibited the animal growth, elevated the MT induction, and increased the Cd uptake rate (ingestion rate, assimilation efficiency from dietary phase, and uptake rate from dissolved phase), all of which enhanced the weight-specific Cd accumulation in daphnids' bodies. The strong dependence of biokinetic parameters on environmental factors (e.g., food concentrations, pH, dissolved or dietary metal concentration, and metal exposure histories) rather than on genotypes implied the great potential of using biokinetics in inter-lab comparisons and environmental risk assessments.

Mapping the expression of the sex determining factor Doublesex1 in Daphnia magna using a knock-in reporter.

Science.gov (United States)

Nong, Quang Dang; Mohamad Ishak, Nur Syafiqah; Matsuura, Tomoaki; Kato, Yasuhiko; Watanabe, Hajime

2017-11-02

Sexually dimorphic traits are common and widespread among animals. The expression of the Doublesex-/Mab-3-domain (DM-domain) gene family has been widely studied in model organisms and has been proven to be essential for the development and maintenance of sex-specific traits. However, little is known about the detailed expression patterns in non-model organisms. In the present study, we demonstrated the spatiotemporal expression of the DM-domain gene, doublesex1 (dsx1), in the crustacean Daphnia magna, which parthenogenetically produces males in response to environmental cues. We developed a dsx1 reporter strain to track dsx1 activity in vivo by inserting the mCherry gene into the dsx1 locus using the TALEN-mediated knock-in approach. After confirming dsx1 expression in male-specific traits in juveniles and adults, we performed time-lapse imaging of embryogenesis. Shortly after gastrulation stage, a presumptive primary organiser, named cumulus, first showed male-specific dsx1 expression. This cell mass moved to the posterior growth zone that distributes dsx1-expressing progenitor cells across the body during axial elongation, before embryos start male-specific dsx1 expression in sexually dimorphic structures. The present study demonstrated the sex-specific dsx1 expression in cell populations involved in basal body formation.

Exploring the role of quantum chemical descriptors in modeling acute toxicity of diverse chemicals to Daphnia magna.

Science.gov (United States)

Reenu; Vikas

2015-09-01

Various quantum-mechanically computed molecular and thermodynamic descriptors along with physico-chemical, electrostatic and topological descriptors are compared while developing quantitative structure-activity relationships (QSARs) for the acute toxicity of 252 diverse organic chemicals towards Daphnia magna. QSAR models based on the quantum-chemical descriptors, computed with routinely employed advanced semi-empirical and ab-initio methods, along with the electron-correlation contribution (CORR) of the descriptors, are analyzed for the external predictivity of the acute toxicity. The models with reliable internal stability and external predictivity are found to be based on the HOMO energy along with the physico-chemical, electrostatic and topological descriptors. Besides this, the total energy and electron-correlation energy are also observed as highly reliable descriptors, suggesting that the intra-molecular interactions between the electrons play an important role in the origin of the acute toxicity, which is in fact an unexplored phenomenon. The models based on quantum-chemical descriptors such as chemical hardness, absolute electronegativity, standard Gibbs free energy and enthalpy are also observed to be reliable. A comparison of the robust models based on the quantum-chemical descriptors computed with various quantum-mechanical methods suggests that the advanced semi-empirical methods such as PM7 can be more reliable than the ab-initio methods which are computationally more expensive. Copyright © 2015 Elsevier Inc. All rights reserved.

Ursodeoxycholic acid in cholestatic liver disease: mechanisms of action and therapeutic use revisited

NARCIS (Netherlands)

Paumgartner, Gustav; Beuers, Ulrich

2002-01-01

Ursodeoxycholic acid (UCDA) is increasingly used for the treatment of cholestatic liver diseases. Experimental evidence suggests three major mechanisms of action: (1) protection of cholangiocytes against cytotoxicity of hydrophobic bile acids, resulting from modulation of the composition of mixed

Determining lower threshold concentrations for synergistic effects

DEFF Research Database (Denmark)

Bjergager, Maj-Britt Andersen; Dalhoff, Kristoffer; Kretschmann, Andreas

2017-01-01

which proven synergists cease to act as synergists towards the aquatic crustacean Daphnia magna. To do this, we compared several approaches and test-setups to evaluate which approach gives the most conservative estimate for the lower threshold for synergy for three known azole synergists. We focus...... on synergistic interactions between the pyrethroid insecticide, alpha-cypermethrin, and one of the three azole fungicides prochloraz, propiconazole or epoxiconazole measured on Daphnia magna immobilization. Three different experimental setups were applied: A standard 48h acute toxicity test, an adapted 48h test...... of immobile organisms increased more than two-fold above what was predicted by independent action (vertical assessment). All three tests confirmed the hypothesis of the existence of a lower azole threshold concentration below which no synergistic interaction was observed. The lower threshold concentration...

Molecular substrates of action control in cortico-striatal circuits.

Science.gov (United States)

Shiflett, Michael W; Balleine, Bernard W

2011-09-15

The purpose of this review is to describe the molecular mechanisms in the striatum that mediate reward-based learning and action control during instrumental conditioning. Experiments assessing the neural bases of instrumental conditioning have uncovered functional circuits in the striatum, including dorsal and ventral striatal sub-regions, involved in action-outcome learning, stimulus-response learning, and the motivational control of action by reward-associated cues. Integration of dopamine (DA) and glutamate neurotransmission within these striatal sub-regions is hypothesized to enable learning and action control through its role in shaping synaptic plasticity and cellular excitability. The extracellular signal regulated kinase (ERK) appears to be particularly important for reward-based learning and action control due to its sensitivity to combined DA and glutamate receptor activation and its involvement in a range of cellular functions. ERK activation in striatal neurons is proposed to have a dual role in both the learning and performance factors that contribute to instrumental conditioning through its regulation of plasticity-related transcription factors and its modulation of intrinsic cellular excitability. Furthermore, perturbation of ERK activation by drugs of abuse may give rise to behavioral disorders such as addiction. Copyright © 2011 Elsevier Ltd. All rights reserved.

Automatic imitation in rhythmical actions: kinematic fidelity and the effects of compatibility, delay, and visual monitoring.

Directory of Open Access Journals (Sweden)

Daniel L Eaves

Full Text Available We demonstrate that observation of everyday rhythmical actions biases subsequent motor execution of the same and of different actions, using a paradigm where the observed actions were irrelevant for action execution. The cycle time of the distractor actions was subtly manipulated across trials, and the cycle time of motor responses served as the main dependent measure. Although distractor frequencies reliably biased response cycle times, this imitation bias was only a small fraction of the modulations in distractor speed, as well as of the modulations produced when participants intentionally imitated the observed rhythms. Importantly, this bias was not only present for compatible actions, but was also found, though numerically reduced, when distractor and executed actions were different (e.g., tooth brushing vs. window wiping, or when the dominant plane of movement was different (horizontal vs. vertical. In addition, these effects were equally pronounced for execution at 0, 4, and 8 s after action observation, a finding that contrasts with the more short-lived effects reported in earlier studies. The imitation bias was also unaffected when vision of the hand was occluded during execution, indicating that this effect most likely resulted from visuomotor interactions during distractor observation, rather than from visual monitoring and guidance during execution. Finally, when the distractor was incompatible in both dimensions (action type and plane the imitation bias was not reduced further, in an additive way, relative to the single-incompatible conditions. This points to a mechanism whereby the observed action's impact on motor processing is generally reduced whenever this is not useful for motor planning. We interpret these findings in the framework of biased competition, where intended and distractor actions can be represented as competing and quasi-encapsulated sensorimotor streams.

Individual differences in action co-representation : not personal distress or subclinical psychotic experiences but sex composition modulates joint action performance

NARCIS (Netherlands)

van der Weiden, Anouk; Aarts, Henk; Prikken, Merel; van Haren, Neeltje E M

2015-01-01

Successful social interaction requires the ability to integrate as well as distinguish own and others' actions. Normally, the integration and distinction of self and other are a well-balanced process, occurring without much effort or conscious attention. However, not everyone is blessed with the

The neuropsychopharmacology of action inhibition: cross-species translation of the stop-signal and go/no-go tasks.

Science.gov (United States)

Eagle, Dawn M; Bari, Andrea; Robbins, Trevor W

2008-08-01

The term 'action inhibition' encapsulates the ability to prevent any form of planned physical response. Growing evidence suggests that different 'stages' or even subtypes of action inhibition activate subtly different neuropharmacological and neuroanatomical processes. In this review, we present evidence from two commonly used and apparently similar behavioural tests, the stop-signal task and the go/no-go task, to determine if these have similar neuroanatomical and neurochemical modulation. Whilst performance of the stop-signal and go/no-go tasks is modulated across only subtly different anatomical networks, serotonin (5-HT) is strongly implicated in inhibitory control on the go/no-go but not the stop-signal task, whereas the stop-signal reaction time appears more sensitive to the action of noradrenaline. There is clear neuropharmacological and neuroanatomical evidence that stop-signal and go/no-go tasks represent different forms of action inhibition. This evidence translates with remarkable consistency across species. We discuss the possible implications of this evidence with respect to the development of novel therapeutic treatments for disorders in which inhibitory deficits are prominent and debilitating.

Impulsive action and impulsive choice across substance and behavioral addictions: cause or consequence?

Science.gov (United States)

Grant, Jon E; Chamberlain, Samuel R

2014-11-01

Substance use disorders are prevalent and debilitating. Certain behavioral syndromes ('behavioral addictions') characterized by repetitive habits, such as gambling disorder, stealing, shopping, and compulsive internet use, may share clinical, co-morbid, and neurobiological parallels with substance addictions. This review considers overlap between substance and behavioral addictions with a particular focus on impulsive action (inability to inhibit motor responses), and impulsive choice (preference for immediate smaller rewards to the detriment of long-term outcomes). We find that acute consumption of drugs with abuse potential is capable of modulating impulsive choice and action, although magnitude and direction of effect appear contingent on baseline function. Many lines of evidence, including findings from meta-analyses, show an association between chronic drug use and elevated impulsive choice and action. In some instances, elevated impulsive choice and action have been found to predate the development of substance use disorders, perhaps signifying their candidacy as objective vulnerability markers. Research in behavioral addictions is preliminary, and has mostly focused on impulsive action, finding this to be elevated versus controls, similar to that seen in chronic substance use disorders. Only a handful of imaging studies has explored the neural correlates of impulsive action and choice across these disorders. Key areas for future research are highlighted along with potential implications in terms of neurobiological models and treatment. In particular, future work should further explore whether the cognitive deficits identified are state or trait in nature: i.e. are evident before addiction perhaps signaling risk; or are a consequence of repetitive engagement in habitual behavior; and effects of novel agents known to modulate these cognitive abilities on various addictive disorders. Copyright © 2014 Elsevier Ltd. All rights reserved.

Designing interprofessional modules for undergraduate healthcare learners

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C Maree

2017-12-01

Full Text Available Background. Interprofessional education aims to prepare learners to collaborate across specialties to provide high-quality healthcare. Internationally and nationally, the emerging need for integrated healthcare and education has been emphasised. The current education programme at the School of Health Care Sciences, University of Pretoria, South Africa primarily follows a uniprofessional approach.Objectives. To describe the development of interprofessional modules over 4 years between the departments of Human Nutrition, Nursing Science, Occupational Therapy, Physiotherapy and Radiography.Methods. The Knowledge-to-Action model guided the module development process. The planning phase comprised three steps: (i problem identification (e.g. national and international policy focus on interprofessional education; (ii review of existing knowledge (e.g. common learning outcomes; and (iii adaptation of knowledge to the local context (e.g. syllabi and logistics.Results. The development of interprofessional modules can be guided by the above-mentioned model to meet the needs of the faculty, departments, students and community and to contribute to interprofessional education, while overcoming the associated challenges.Conclusion. Challenges included clashes in timetable schedules, financial constraints, administrative support, logistical issues and resistance to change. The designing and implementing of new modules were intense and time consuming, and required commitment. The development of the modules was an excellent example of interprofessional teamwork that needs to be transferred to the implementation and role modelling of interprofessional education.

Feeding type and development drive the ingestion of microplastics by freshwater invertebrates.

Science.gov (United States)

Scherer, Christian; Brennholt, Nicole; Reifferscheid, Georg; Wagner, Martin

2017-12-05

Microscopic plastic items (microplastics) are ubiquitously present in aquatic ecosystems. With decreasing size their availability and potential to accumulate throughout food webs increase. However, little is known on the uptake of microplastics by freshwater invertebrates. To address this, we exposed species with different feeding strategies to 1, 10 and 90 µm fluorescent polystyrene spheres (3-3 000 particles mL -1 ). Additionally, we investigated how developmental stages and a co-exposure to natural particles (e.g., food) modulate microplastic ingestion. All species ingested microplastics in a concentration-dependent manner with Daphnia magna consuming up to 6 180 particles h -1 , followed by Chironomus riparius (226 particles h -1 ), Physella acuta (118 particles h -1 ), Gammarus pulex (10 particles h -1 ) and Lumbriculus variegatus (8 particles h -1 ). D. magna did not ingest 90 µm microplastics whereas the other species preferred larger microplastics over 1 µm in size. In C. riparius and D. magna, size preference depended on the life stage with larger specimens ingesting more and larger microplastics. The presence of natural particles generally reduced the microplastics uptake. Our results demonstrate that freshwater invertebrates have the capacity to ingest microplastics. However, the quantity of uptake depends on their feeding type and morphology as well as on the availability of microplastics.

Effects of the pyrethroid insecticide, deltamethrin, on respiratory modulated hypoglossal motoneurons in a brain stem slice from newborn mice

DEFF Research Database (Denmark)

Rekling, J C; Theophilidis, G

1995-01-01

We have studied the action of deltamethrin on respiratory modulated hypoglossal motoneurons in a brain stem slice from newborn mice. Deltamethrin depolarized the hypoglossal motoneurons, increased the background synaptic noise and reduced the frequency and amplitude of current elicited action...

Amphetamine elevates nucleus accumbens dopamine via an action potential-dependent mechanism that is modulated by endocannabinoids

Science.gov (United States)

Covey, Dan P.; Bunner, Kendra D.; Schuweiler, Douglas R.; Cheer, Joseph F.; Garris, Paul A.

2018-01-01

The reinforcing effects of abused drugs are mediated by their ability to elevate nucleus accumbens dopamine. Amphetamine (AMPH) was historically thought to increase dopamine by an action potential-independent, non-exocytotic type of release called efflux, involving reversal of dopamine transporter function and driven by vesicular dopamine depletion. Growing evidence suggests that AMPH also acts by an action potential-dependent mechanism. Indeed, fast-scan cyclic voltammetry demonstrates that AMPH activates dopamine transients, reward-related phasic signals generated by burst firing of dopamine neurons and dependent on intact vesicular dopamine. Not established for AMPH but indicating a shared mechanism, endocannabinoids facilitate this activation of dopamine transients by broad classes of abused drugs. Here, using fast-scan cyclic voltammetry coupled to pharmacological manipulations in awake rats, we investigated the action potential and endocannabinoid dependence of AMPH-induced elevations in nucleus accumbens dopamine. AMPH increased the frequency, amplitude and duration of transients, which were observed riding on top of slower dopamine increases. Surprisingly, silencing dopamine neuron firing abolished all AMPH-induced dopamine elevations, identifying an action potential-dependent origin. Blocking cannabinoid type 1 receptors prevented AMPH from increasing transient frequency, similar to reported effects on other abused drugs, but not from increasing transient duration and inhibiting dopamine uptake. Thus, AMPH elevates nucleus accumbens dopamine by eliciting transients via cannabinoid type 1 receptors and promoting the summation of temporally coincident transients, made more numerous, larger and wider by AMPH. Collectively, these findings are inconsistent with AMPH eliciting action potential-independent dopamine efflux and vesicular dopamine depletion, and support endocannabinoids facilitating phasic dopamine signalling as a common action in drug reinforcement

Amphetamine elevates nucleus accumbens dopamine via an action potential-dependent mechanism that is modulated by endocannabinoids.

Science.gov (United States)

Covey, Dan P; Bunner, Kendra D; Schuweiler, Douglas R; Cheer, Joseph F; Garris, Paul A

2016-06-01

The reinforcing effects of abused drugs are mediated by their ability to elevate nucleus accumbens dopamine. Amphetamine (AMPH) was historically thought to increase dopamine by an action potential-independent, non-exocytotic type of release called efflux, involving reversal of dopamine transporter function and driven by vesicular dopamine depletion. Growing evidence suggests that AMPH also acts by an action potential-dependent mechanism. Indeed, fast-scan cyclic voltammetry demonstrates that AMPH activates dopamine transients, reward-related phasic signals generated by burst firing of dopamine neurons and dependent on intact vesicular dopamine. Not established for AMPH but indicating a shared mechanism, endocannabinoids facilitate this activation of dopamine transients by broad classes of abused drugs. Here, using fast-scan cyclic voltammetry coupled to pharmacological manipulations in awake rats, we investigated the action potential and endocannabinoid dependence of AMPH-induced elevations in nucleus accumbens dopamine. AMPH increased the frequency, amplitude and duration of transients, which were observed riding on top of slower dopamine increases. Surprisingly, silencing dopamine neuron firing abolished all AMPH-induced dopamine elevations, identifying an action potential-dependent origin. Blocking cannabinoid type 1 receptors prevented AMPH from increasing transient frequency, similar to reported effects on other abused drugs, but not from increasing transient duration and inhibiting dopamine uptake. Thus, AMPH elevates nucleus accumbens dopamine by eliciting transients via cannabinoid type 1 receptors and promoting the summation of temporally coincident transients, made more numerous, larger and wider by AMPH. Collectively, these findings are inconsistent with AMPH eliciting action potential-independent dopamine efflux and vesicular dopamine depletion, and support endocannabinoids facilitating phasic dopamine signalling as a common action in drug reinforcement

DNA alterations and effects on growth and reproduction in Daphnia magna during chronic exposure to gamma radiation over three successive generations

International Nuclear Information System (INIS)

Parisot, Florian; Bourdineaud, Jean-Paul; Plaire, Delphine; Adam-Guillermin, Christelle; Alonzo, Frédéric

2015-01-01

Highlights: • We exposed three successive generations of Daphnia magna to chronic gamma radiation. • We examined DNA alterations and effects on survival, growth and reproduction. • DNA alterations were accumulated over a generation and transmitted to the progeny. • Effects on survival and reproduction, and delay in growth increased over generations. - Abstract: This study examined chronic effects of external Cs-137 gamma radiation on Daphnia magna exposed over three successive generations (F0, F1 and F2) to environmentally relevant dose rates (ranging from 0.007 to 35.4 mGy h −1 ). Investigated endpoints included survival, growth, reproduction and DNA alterations quantified using random-amplified polymorphic DNA polymerase chain reaction (RAPD-PCR). Results demonstrated that radiation effects on survival, growth and reproduction increased in severity from generation F0 to generation F2. Mortality after 21 days at 35.4 mGy h −1 increased from 20% in F0 to 30% in F2. Growth was affected by a slight reduction in maximum length at 35.4 mGy h −1 in F0 and by reductions of 5 and 13% in growth rate, respectively, at 4.70 and 35.4 mGy h −1 in F2. Reproduction was affected by a reduction of 19% in 21 day-fecundity at 35.4 mGy h −1 in F0 and by a delay of 1.9 days in brood release as low as 0.070 mGy h −1 in F2. In parallel, DNA alterations became significant at decreasing dose rates over the course of F0 (from 4.70 mGy h −1 at hatching to 0.007 mGy h −1 after ∼21 days) and from F0 to F2 (0.070 mGy h −1 at hatching to 0.007 mGy h −1 after ∼21 days), demonstrating their rapid accumulation in F0 daphnids and their transmission to offspring generations. Transiently more efficient DNA repair leading to some recovery at the organism level was suggested in F1, with no effect on survival, a slight reduction of 12% in 21 day-fecundity at 35.4 mGy h −1 and DNA alterations significant at highest dose rates only. The study improved our understanding of

DNA alterations and effects on growth and reproduction in Daphnia magna during chronic exposure to gamma radiation over three successive generations

Energy Technology Data Exchange (ETDEWEB)

Parisot, Florian [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV/SERIS/LECO, Cadarache, St Paul-lez-Durance 13115 (France); Bourdineaud, Jean-Paul [UMR 5805 EPOC – OASU, Station marine d’Arcachon, Université Bordeaux 1, Arcachon 33120 (France); Plaire, Delphine; Adam-Guillermin, Christelle [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV/SERIS/LECO, Cadarache, St Paul-lez-Durance 13115 (France); Alonzo, Frédéric, E-mail: frederic.alonzo@irsn.fr [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV/SERIS/LECO, Cadarache, St Paul-lez-Durance 13115 (France)

2015-06-15

Highlights: • We exposed three successive generations of Daphnia magna to chronic gamma radiation. • We examined DNA alterations and effects on survival, growth and reproduction. • DNA alterations were accumulated over a generation and transmitted to the progeny. • Effects on survival and reproduction, and delay in growth increased over generations. - Abstract: This study examined chronic effects of external Cs-137 gamma radiation on Daphnia magna exposed over three successive generations (F0, F1 and F2) to environmentally relevant dose rates (ranging from 0.007 to 35.4 mGy h{sup −1}). Investigated endpoints included survival, growth, reproduction and DNA alterations quantified using random-amplified polymorphic DNA polymerase chain reaction (RAPD-PCR). Results demonstrated that radiation effects on survival, growth and reproduction increased in severity from generation F0 to generation F2. Mortality after 21 days at 35.4 mGy h{sup −1} increased from 20% in F0 to 30% in F2. Growth was affected by a slight reduction in maximum length at 35.4 mGy h{sup −1} in F0 and by reductions of 5 and 13% in growth rate, respectively, at 4.70 and 35.4 mGy h{sup −1} in F2. Reproduction was affected by a reduction of 19% in 21 day-fecundity at 35.4 mGy h{sup −1} in F0 and by a delay of 1.9 days in brood release as low as 0.070 mGy h{sup −1} in F2. In parallel, DNA alterations became significant at decreasing dose rates over the course of F0 (from 4.70 mGy h{sup −1} at hatching to 0.007 mGy h{sup −1} after ∼21 days) and from F0 to F2 (0.070 mGy h{sup −1} at hatching to 0.007 mGy h{sup −1} after ∼21 days), demonstrating their rapid accumulation in F0 daphnids and their transmission to offspring generations. Transiently more efficient DNA repair leading to some recovery at the organism level was suggested in F1, with no effect on survival, a slight reduction of 12% in 21 day-fecundity at 35.4 mGy h{sup −1} and DNA alterations significant at highest

Automatic Imitation in Rhythmical Actions: Kinematic Fidelity and the Effects of Compatibility, Delay, and Visual Monitoring

Science.gov (United States)

Eaves, Daniel L.; Turgeon, Martine; Vogt, Stefan

2012-01-01

We demonstrate that observation of everyday rhythmical actions biases subsequent motor execution of the same and of different actions, using a paradigm where the observed actions were irrelevant for action execution. The cycle time of the distractor actions was subtly manipulated across trials, and the cycle time of motor responses served as the main dependent measure. Although distractor frequencies reliably biased response cycle times, this imitation bias was only a small fraction of the modulations in distractor speed, as well as of the modulations produced when participants intentionally imitated the observed rhythms. Importantly, this bias was not only present for compatible actions, but was also found, though numerically reduced, when distractor and executed actions were different (e.g., tooth brushing vs. window wiping), or when the dominant plane of movement was different (horizontal vs. vertical). In addition, these effects were equally pronounced for execution at 0, 4, and 8 s after action observation, a finding that contrasts with the more short-lived effects reported in earlier studies. The imitation bias was also unaffected when vision of the hand was occluded during execution, indicating that this effect most likely resulted from visuomotor interactions during distractor observation, rather than from visual monitoring and guidance during execution. Finally, when the distractor was incompatible in both dimensions (action type and plane) the imitation bias was not reduced further, in an additive way, relative to the single-incompatible conditions. This points to a mechanism whereby the observed action’s impact on motor processing is generally reduced whenever this is not useful for motor planning. We interpret these findings in the framework of biased competition, where intended and distractor actions can be represented as competing and quasi-encapsulated sensorimotor streams. PMID:23071623

Objects Mediate Goal Integration in Ventrolateral Prefrontal Cortex during Action Observation.

Directory of Open Access Journals (Sweden)

Mari Hrkać

Full Text Available Actions performed by others are mostly not observed in isolation, but embedded in sequences of actions tied together by an overarching goal. Therefore, preceding actions can modulate the observer's expectations in relation to the currently perceived action. Ventrolateral prefrontal cortex (vlPFC, and inferior frontal gyrus (IFG in particular, is suggested to subserve the integration of episodic as well as semantic information and memory, including action scripts. The present fMRI study investigated if activation in IFG varies with the effort to integrate expected and observed action, even when not required by the task. During an fMRI session, participants were instructed to attend to short videos of single actions and to deliver a judgment about the actor's current goal. We manipulated the strength of goal expectation induced by the preceding action, implementing the parameter "goal-relatedness" between the preceding and the currently observed action. Moreover, since objects point to the probability of certain actions, we also manipulated whether the current and the preceding action shared at least one object or not. We found an interaction between the two factors goal-relatedness and shared object: IFG activation increased the weaker the goal-relatedness between the preceding and the current action was, but only when they shared at least one object. Here, integration of successive action steps was triggered by the re-appearing (shared object but hampered by a weak goal-relatedness between the actually observed manipulation. These findings foster the recently emerging view that IFG is enhanced by goal-related conflicts during action observation.

Mental Representations in Musical Processing and their Role in Action-Perception Loops

Directory of Open Access Journals (Sweden)

Rebecca S. Schaefer

2015-05-01

Full Text Available I address the diverging usage of the term "imagery" by delineating different types of imagery, each of which is supported by multimodal mental representations that are informed and modulated by the body and its in- and outputs, and that in turn modulate and inform perception and action through predictive processing. These multimodal representations, viewed here as mental models, underlie our individual perceptual experience of music, which is constructed in the listener as it is perceived and interpreted. While tracking incoming auditory information, mental representations of music unfold on multiple levels as we listen, from regularities detected across notes to the structure of entire pieces of music, generating predictions for different musical aspects. These predictions lead to specific percepts and behavioral outputs, illustrating a tight coupling of cognition, perception and action. This coupling and the prominence of predictive mechanisms in music processing are described in the context of the broader role of predictive processing in cognitive function, which is well suited to account for the role of mental models in musical perception and action. As a proxy for mental representations, investigating the cerebral correlates of constructive imagination may offer an experimentally tractable approach to clarifying how mental models of music are implemented in the brain.

Neural theory for the perception of causal actions.

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Fleischer, Falk; Christensen, Andrea; Caggiano, Vittorio; Thier, Peter; Giese, Martin A

2012-07-01

The efficient prediction of the behavior of others requires the recognition of their actions and an understanding of their action goals. In humans, this process is fast and extremely robust, as demonstrated by classical experiments showing that human observers reliably judge causal relationships and attribute interactive social behavior to strongly simplified stimuli consisting of simple moving geometrical shapes. While psychophysical experiments have identified critical visual features that determine the perception of causality and agency from such stimuli, the underlying detailed neural mechanisms remain largely unclear, and it is an open question why humans developed this advanced visual capability at all. We created pairs of naturalistic and abstract stimuli of hand actions that were exactly matched in terms of their motion parameters. We show that varying critical stimulus parameters for both stimulus types leads to very similar modulations of the perception of causality. However, the additional form information about the hand shape and its relationship with the object supports more fine-grained distinctions for the naturalistic stimuli. Moreover, we show that a physiologically plausible model for the recognition of goal-directed hand actions reproduces the observed dependencies of causality perception on critical stimulus parameters. These results support the hypothesis that selectivity for abstract action stimuli might emerge from the same neural mechanisms that underlie the visual processing of natural goal-directed action stimuli. Furthermore, the model proposes specific detailed neural circuits underlying this visual function, which can be evaluated in future experiments.

Selective estrogen receptor modulators as brain therapeutic agents

OpenAIRE

Arévalo, María Ángeles; Santos-Galindo, María; Lagunas, Natalia; Azcoitia, I.; García-Segura, Luis M.

2011-01-01

Selective estrogen receptor modulators (SERMs), used for the treatment of breast cancer, osteoporosis, and menopausal symptoms, affect the nervous system. Some SERMs trigger neuroprotective mechanisms and reduce neural damage in different experimental models of neural trauma, brain inflammation, neurodegenerative diseases, cognitive impairment, and affective disorders. New SERMs with specific actions on neurons and glial cells may represent promising therapeutic tools for the brain. © 2011 So...

Development of allosteric modulators of GPCRs for treatment of CNS disorders.

Science.gov (United States)

Nickols, Hilary Highfield; Conn, P Jeffrey

2014-01-01

The discovery of allosteric modulators of G protein-coupled receptors (GPCRs) provides a promising new strategy with potential for developing novel treatments for a variety of central nervous system (CNS) disorders. Traditional drug discovery efforts targeting GPCRs have focused on developing ligands for orthosteric sites which bind endogenous ligands. Allosteric modulators target a site separate from the orthosteric site to modulate receptor function. These allosteric agents can either potentiate (positive allosteric modulator, PAM) or inhibit (negative allosteric modulator, NAM) the receptor response and often provide much greater subtype selectivity than orthosteric ligands for the same receptors. Experimental evidence has revealed more nuanced pharmacological modes of action of allosteric modulators, with some PAMs showing allosteric agonism in combination with positive allosteric modulation in response to endogenous ligand (ago-potentiators) as well as "bitopic" ligands that interact with both the allosteric and orthosteric sites. Drugs targeting the allosteric site allow for increased drug selectivity and potentially decreased adverse side effects. Promising evidence has demonstrated potential utility of a number of allosteric modulators of GPCRs in multiple CNS disorders, including neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and Huntington's disease, as well as psychiatric or neurobehavioral diseases such as anxiety, schizophrenia, and addiction. © 2013.

Action and Perception Are Temporally Coupled by a Common Mechanism That Leads to a Timing Misperception

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Astefanoaei, Corina; Daye, Pierre M.; FitzGibbon, Edmond J.; Creanga, Dorina-Emilia; Rufa, Alessandra; Optican, Lance M.

2015-01-01

We move our eyes to explore the world, but visual areas determining where to look next (action) are different from those determining what we are seeing (perception). Whether, or how, action and perception are temporally coordinated is not known. The preparation time course of an action (e.g., a saccade) has been widely studied with the gap/overlap paradigm with temporal asynchronies (TA) between peripheral target onset and fixation point offset (gap, synchronous, or overlap). However, whether the subjects perceive the gap or overlap, and when they perceive it, has not been studied. We adapted the gap/overlap paradigm to study the temporal coupling of action and perception. Human subjects made saccades to targets with different TAs with respect to fixation point offset and reported whether they perceived the stimuli as separated by a gap or overlapped in time. Both saccadic and perceptual report reaction times changed in the same way as a function of TA. The TA dependencies of the time change for action and perception were very similar, suggesting a common neural substrate. Unexpectedly, in the perceptual task, subjects misperceived lights overlapping by less than ∼100 ms as separated in time (overlap seen as gap). We present an attention-perception model with a map of prominence in the superior colliculus that modulates the stimulus signal's effectiveness in the action and perception pathways. This common source of modulation determines how competition between stimuli is resolved, causes the TA dependence of action and perception to be the same, and causes the misperception. PMID:25632126

Module theory, extending modules and generalizations

CERN Document Server

Tercan, Adnan

2016-01-01

The main focus of this monograph is to offer a comprehensive presentation of known and new results on various generalizations of CS-modules and CS-rings. Extending (or CS) modules are generalizations of injective (and also semisimple or uniform) modules. While the theory of CS-modules is well documented in monographs and textbooks, results on generalized forms of the CS property as well as dual notions are far less present in the literature. With their work the authors provide a solid background to module theory, accessible to anyone familiar with basic abstract algebra. The focus of the book is on direct sums of CS-modules and classes of modules related to CS-modules, such as relative (injective) ejective modules, (quasi) continuous modules, and lifting modules. In particular, matrix CS-rings are studied and clear proofs of fundamental decomposition results on CS-modules over commutative domains are given, thus complementing existing monographs in this area. Open problems round out the work and establish the...

A Framework for Hierarchical Perception-Action Learning Utilizing Fuzzy Reasoning.

Science.gov (United States)

Windridge, David; Felsberg, Michael; Shaukat, Affan

2013-02-01

Perception-action (P-A) learning is an approach to cognitive system building that seeks to reduce the complexity associated with conventional environment-representation/action-planning approaches. Instead, actions are directly mapped onto the perceptual transitions that they bring about, eliminating the need for intermediate representation and significantly reducing training requirements. We here set out a very general learning framework for cognitive systems in which online learning of the P-A mapping may be conducted within a symbolic processing context, so that complex contextual reasoning can influence the P-A mapping. In utilizing a variational calculus approach to define a suitable objective function, the P-A mapping can be treated as an online learning problem via gradient descent using partial derivatives. Our central theoretical result is to demonstrate top-down modulation of low-level perceptual confidences via the Jacobian of the higher levels of a subsumptive P-A hierarchy. Thus, the separation of the Jacobian as a multiplying factor between levels within the objective function naturally enables the integration of abstract symbolic manipulation in the form of fuzzy deductive logic into the P-A mapping learning. We experimentally demonstrate that the resulting framework achieves significantly better accuracy than using P-A learning without top-down modulation. We also demonstrate that it permits novel forms of context-dependent multilevel P-A mapping, applying the mechanism in the context of an intelligent driver assistance system.

Multilayer flow modulator stent technology: a treatment revolution for US patients?

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Sultan, Sherif; Hynes, Niamh

2015-05-01

Thoracoabdominal aortic repair is a high-risk procedure in most experienced centers, not only because of anatomical complexity but also due to the fragility of the patients in whom these aneurysms occur. Such repairs are complex, time-consuming and impose a systemic injury upon the patients, regardless of whether the repair is performed by open surgery or via a fenestrated/branched technique. The substantive risks associated with such repairs include death, dialysis and paralysis. The multilayer flow modulator (MFM) is a disruptive technology which promises a minimally invasive reproducible treatment option, with clinical results demonstrating physiological modulation of the aortic sac with abolition of spinal injury. The mode of action of MFM forces us to completely rethink aneurysm pathogenesis and, consequently, it has been met with much cynicism. We aim to uncloak some of the mystery surrounding the MFM, clarify its mode of action and explore the truth behind its clinical effectiveness.

Impact of polystyrene microplastics on Daphnia magna mortality and reproduction in relation to food availability

Science.gov (United States)

Aljaibachi, Rana

2018-01-01

Microplastics (MPs) in the environment continue to be a growing area of concern in terms of acute and chronic impacts on aquatic life. Whilst increasing numbers of studies are providing important insights into microparticle behaviour and impacts in the marine environment, a paucity of information exists regarding the freshwater environment. This study focusses on the uptake, retention and the impact of 2 µm polystyrene MPs in the freshwater cladoceran Daphnia magna in relation to food intake (algae Chlorella vulgaris), with MP size chosen to approximately match the cell size of the algae. Daphnia were exposed to varied concentrations of MPs and algae. When exposed to a single concentration of MPs Daphnia almost immediately ate them in large quantities. However, the presence of algae, even at low concentrations, had a significant negative impact on MP uptake that was not in proportion to relative availability. As MP concentrations increased, intake did not if algae were present, even at higher concentrations of MPs. This suggests that Daphnia are selectively avoiding eating plastics. Adult Daphnia exposed to MPs for 21 days showed mortality after seven days of exposure in all treatments compared to the control. However significant differences were all related to algal concentration rather than to MP concentration. This suggests that where ample food is present, MPs have little effect on adults. There was also no impact on their reproduction. The neonate toxicity test confirmed previous results that mortality and reproduction was linked to availability of food rather than MP concentrations. This would make sense in light of our suggestion that Daphnia are selectively avoiding eating microplastics. PMID:29686944

Impact of polystyrene microplastics on Daphnia magna mortality and reproduction in relation to food availability

Directory of Open Access Journals (Sweden)

Rana Aljaibachi

2018-04-01

Full Text Available Microplastics (MPs in the environment continue to be a growing area of concern in terms of acute and chronic impacts on aquatic life. Whilst increasing numbers of studies are providing important insights into microparticle behaviour and impacts in the marine environment, a paucity of information exists regarding the freshwater environment. This study focusses on the uptake, retention and the impact of 2 µm polystyrene MPs in the freshwater cladoceran Daphnia magna in relation to food intake (algae Chlorella vulgaris, with MP size chosen to approximately match the cell size of the algae. Daphnia were exposed to varied concentrations of MPs and algae. When exposed to a single concentration of MPs Daphnia almost immediately ate them in large quantities. However, the presence of algae, even at low concentrations, had a significant negative impact on MP uptake that was not in proportion to relative availability. As MP concentrations increased, intake did not if algae were present, even at higher concentrations of MPs. This suggests that Daphnia are selectively avoiding eating plastics. Adult Daphnia exposed to MPs for 21 days showed mortality after seven days of exposure in all treatments compared to the control. However significant differences were all related to algal concentration rather than to MP concentration. This suggests that where ample food is present, MPs have little effect on adults. There was also no impact on their reproduction. The neonate toxicity test confirmed previous results that mortality and reproduction was linked to availability of food rather than MP concentrations. This would make sense in light of our suggestion that Daphnia are selectively avoiding eating microplastics.

QSAR modeling of toxicity of diverse organic chemicals to Daphnia magna using 2D and 3D descriptors

International Nuclear Information System (INIS)

Kar, Supratik; Roy, Kunal

2010-01-01

One of the major economic alternatives to experimental toxicity testing is the use of quantitative structure-activity relationships (QSARs) which are used in formulating regulatory decisions of environmental protection agencies. In this background, we have modeled a large diverse group of 297 chemicals for their toxicity to Daphnia magna using mechanistically interpretable descriptors. Three-dimensional (3D) (electronic and spatial) and two-dimensional (2D) (topological and information content indices) descriptors along with physicochemical parameter log K o/w (n-octanol/water partition coefficient) and structural descriptors were used as predictor variables. The QSAR models were developed by stepwise multiple linear regression (MLR), partial least squares (PLS), genetic function approximation (GFA), and genetic PLS (G/PLS). All the models were validated internally and externally. Among several models developed using different chemometric tools, the best model based on both internal and external validation characteristics was a PLS equation with 7 descriptors and three latent variables explaining 67.8% leave-one-out predicted variance and 74.1% external predicted variance. The PLS model suggests that higher lipophilicity and electrophilicity, less negative charge surface area and presence of ether linkage, hydrogen bond donor groups and acetylenic carbons are responsible for greater toxicity of chemicals. The developed model may be used for prediction of toxicity, safety and risk assessment of chemicals to achieve better ecotoxicological management and prevent adverse health consequences.

QSAR modeling of toxicity of diverse organic chemicals to Daphnia magna using 2D and 3D descriptors

Energy Technology Data Exchange (ETDEWEB)

Kar, Supratik [Drug Theoretics and Cheminformatics Laboratory, Department of Pharmaceutical Technology, Jadavpur University, Raja S C Mullick Road, Kolkata 700032 (India); Roy, Kunal, E-mail: kunalroy_in@yahoo.com [Drug Theoretics and Cheminformatics Laboratory, Department of Pharmaceutical Technology, Jadavpur University, Raja S C Mullick Road, Kolkata 700032 (India)

2010-05-15

One of the major economic alternatives to experimental toxicity testing is the use of quantitative structure-activity relationships (QSARs) which are used in formulating regulatory decisions of environmental protection agencies. In this background, we have modeled a large diverse group of 297 chemicals for their toxicity to Daphnia magna using mechanistically interpretable descriptors. Three-dimensional (3D) (electronic and spatial) and two-dimensional (2D) (topological and information content indices) descriptors along with physicochemical parameter log K{sub o/w} (n-octanol/water partition coefficient) and structural descriptors were used as predictor variables. The QSAR models were developed by stepwise multiple linear regression (MLR), partial least squares (PLS), genetic function approximation (GFA), and genetic PLS (G/PLS). All the models were validated internally and externally. Among several models developed using different chemometric tools, the best model based on both internal and external validation characteristics was a PLS equation with 7 descriptors and three latent variables explaining 67.8% leave-one-out predicted variance and 74.1% external predicted variance. The PLS model suggests that higher lipophilicity and electrophilicity, less negative charge surface area and presence of ether linkage, hydrogen bond donor groups and acetylenic carbons are responsible for greater toxicity of chemicals. The developed model may be used for prediction of toxicity, safety and risk assessment of chemicals to achieve better ecotoxicological management and prevent adverse health consequences.

Reciprocal Modulation of IK1-INa Extends Excitability in Cardiac Ventricular Cells.

Science.gov (United States)

Varghese, Anthony

2016-01-01

The inwardly rectifying potassium current (I K1 ) and the fast inward sodium current (I Na ) are reciprocally modulated in mammalian ventricular myocytes. An increase in the expression of channels responsible for one of these two currents results in a corresponding increase in expression of the other. These currents are critical in the propagation of action potentials (AP) during the normal functioning of the heart. This study identifies a physiological role for I K1 -I Na reciprocal modulation in ventricular fiber activation thresholds and conduction. Simulations of action potentials in single cells and propagating APs in cardiac fibers were carried out using an existing model of electrical activity in cardiac ventricular myocytes. The conductances, G K1 , of the inwardly rectifying potassium current, and G Na , of the fast inward sodium current were modified independently and in tandem to simulate reciprocal modulation. In single cells, independent modulation of G K1 alone resulted in changes in activation thresholds that were qualitatively similar to those for reciprocal G K1 -G Na modulation and unlike those due to independent modulation of G Na alone, indicating that G K1 determines the cellular activation threshold. On the other hand, the variations in conduction velocity in cardiac cell fibers were similar for independent G Na modulation and for tandem changes in G K1 -G Na , suggesting that G Na is primarily responsible for setting tissue AP conduction velocity. Conduction velocity dependence on G K1 -G Na is significantly affected by the intercellular gap junction conductance. While the effects on the passive fiber space constant due to changes in both G K1 and the intercellular gap junction conductance, G gj , were in line with linear cable theory predictions, both conductances had surprisingly large effects on fiber activation thresholds. Independent modulation of G K1 rendered cardiac fibers inexcitable at higher levels of G K1 whereas tandem G K1 -G Na

Short-term exposure with high concentrations of pristine microplastic particles leads to immobilisation of Daphnia magna.

Science.gov (United States)

Rehse, Saskia; Kloas, Werner; Zarfl, Christiane

2016-06-01

Recent studies revealed that freshwaters are not only polluted by chemicals, but also by persistent synthetic material like microplastics (plastic particles pollutants or release additives. Although there is rising concern about the pollution of freshwaters by microplastics, knowledge about their potential effects on organisms is limited. For a better understanding of their risks, it is crucial to unravel which characteristics influence their effects on organisms. Analysing effects by the mere particles is the first step before including more complex interactions e.g. with associated chemicals. The aim of this study was to analyse potential physical effects of microplastics on one representative organism for limnic zooplankton (Daphnia magna). We investigated whether microplastics can be ingested and whether their presence causes adverse effects after short-term exposure. Daphnids were exposed for up to 96 h to 1-μm and 100-μm polyethylene particles at concentrations between 12.5 and 400 mg L(-1). Ingestion of 1-μm particles led to immobilisation increasing with dose and time with an EC50 of 57.43 mg L(-1) after 96 h. 100-μm particles that could not be ingested by the daphnids had no observable effects. These results underline that, considering high concentrations, microplastic particles can already induce adverse effects in limnic zooplankton. Although it needs to be clarified if these concentrations can be found in the environment these results are a basis for future impact analysis, especially in combination with associated chemicals. Copyright © 2016 Elsevier Ltd. All rights reserved.

Temporal genetic stability in natural populations of the waterflea Daphnia magna in response to strong selection pressure.

Science.gov (United States)

Orsini, Luisa; Marshall, Hollie; Cuenca Cambronero, Maria; Chaturvedi, Anurag; Thomas, Kelley W; Pfrender, Michael E; Spanier, Katina I; De Meester, Luc

2016-12-01

Studies monitoring changes in genetic diversity and composition through time allow a unique understanding of evolutionary dynamics and persistence of natural populations. However, such studies are often limited to species with short generation times that can be propagated in the laboratory or few exceptional cases in the wild. Species that produce dormant stages provide powerful models for the reconstruction of evolutionary dynamics in the natural environment. A remaining open question is to what extent dormant egg banks are an unbiased representation of populations and hence of the species' evolutionary potential, especially in the presence of strong environmental selection. We address this key question using the water flea Daphnia magna, which produces dormant stages that accumulate in biological archives over time. We assess temporal genetic stability in three biological archives, previously used in resurrection ecology studies showing adaptive evolutionary responses to rapid environmental change. We show that neutral genetic diversity does not decline with the age of the population and it is maintained in the presence of strong selection. In addition, by comparing temporal genetic stability in hatched and unhatched populations from the same biological archive, we show that dormant egg banks can be consulted to obtain a reliable measure of genetic diversity over time, at least in the multidecadal time frame studied here. The stability of neutral genetic diversity through time is likely mediated by the buffering effect of the resting egg bank. © 2016 John Wiley & Sons Ltd.

Reconstruction of gene regulatory modules from RNA silencing of IFN-α modulators: experimental set-up and inference method.

Science.gov (United States)

Grassi, Angela; Di Camillo, Barbara; Ciccarese, Francesco; Agnusdei, Valentina; Zanovello, Paola; Amadori, Alberto; Finesso, Lorenzo; Indraccolo, Stefano; Toffolo, Gianna Maria

2016-03-12

Inference of gene regulation from expression data may help to unravel regulatory mechanisms involved in complex diseases or in the action of specific drugs. A challenging task for many researchers working in the field of systems biology is to build up an experiment with a limited budget and produce a dataset suitable to reconstruct putative regulatory modules worth of biological validation. Here, we focus on small-scale gene expression screens and we introduce a novel experimental set-up and a customized method of analysis to make inference on regulatory modules starting from genetic perturbation data, e.g. knockdown and overexpression data. To illustrate the utility of our strategy, it was applied to produce and analyze a dataset of quantitative real-time RT-PCR data, in which interferon-α (IFN-α) transcriptional response in endothelial cells is investigated by RNA silencing of two candidate IFN-α modulators, STAT1 and IFIH1. A putative regulatory module was reconstructed by our method, revealing an intriguing feed-forward loop, in which STAT1 regulates IFIH1 and they both negatively regulate IFNAR1. STAT1 regulation on IFNAR1 was object of experimental validation at the protein level. Detailed description of the experimental set-up and of the analysis procedure is reported, with the intent to be of inspiration for other scientists who want to realize similar experiments to reconstruct gene regulatory modules starting from perturbations of possible regulators. Application of our approach to the study of IFN-α transcriptional response modulators in endothelial cells has led to many interesting novel findings and new biological hypotheses worth of validation.

Functional differentiation of macaque visual temporal cortical neurons using a parametric action space.

Science.gov (United States)

Vangeneugden, Joris; Pollick, Frank; Vogels, Rufin

2009-03-01

Neurons in the rostral superior temporal sulcus (STS) are responsive to displays of body movements. We employed a parametric action space to determine how similarities among actions are represented by visual temporal neurons and how form and motion information contributes to their responses. The stimulus space consisted of a stick-plus-point-light figure performing arm actions and their blends. Multidimensional scaling showed that the responses of temporal neurons represented the ordinal similarity between these actions. Further tests distinguished neurons responding equally strongly to static presentations and to actions ("snapshot" neurons), from those responding much less strongly to static presentations, but responding well when motion was present ("motion" neurons). The "motion" neurons were predominantly found in the upper bank/fundus of the STS, and "snapshot" neurons in the lower bank of the STS and inferior temporal convexity. Most "motion" neurons showed strong response modulation during the course of an action, thus responding to action kinematics. "Motion" neurons displayed a greater average selectivity for these simple arm actions than did "snapshot" neurons. We suggest that the "motion" neurons code for visual kinematics, whereas the "snapshot" neurons code for form/posture, and that both can contribute to action recognition, in agreement with computation models of action recognition.

Basic Mechanisms of Action of the Antiepileptic Drugs

Directory of Open Access Journals (Sweden)

Kuzmanova R.

2017-10-01

Full Text Available Available antiepileptic drugs interact with a variety of different molecular targets. The mechanism of action of most anticonvulsants is most often complex with a number of affected regions. The combination of mechanisms of action of drugs in particular proportions can possibly determine the showcase of its antiepileptic activity. The common factor between the different supposed mechanisms for a number of drugs includes the possibility for modulating the excitatory and inhibitory neurotransmission through effects upon the voltage-gated ion channels, synaptic plasticity, heterogeneous receptors, and metabolism of neurotransmitters. There are controversial data on the extent to which a specific action can be the reason for the wholesome anticonvulsive characteristics of various medications, as well as the relation with the presence of undesired drug effects. The complexity of the action of some antiepileptic drugs creates conditions for optimal choice during therapy. In many cases, the insufficient familiarity with individual genetic differences and the disease related receptor damages can hinder defining a particular drug action. Characterizing the mechanisms of action of the present antiepileptic medications would increase the understanding for the pathophysiological mechanisms of epileptic seizures, as well as the development of new therapeutic strategies. The development of novel antiepileptic drugs and the ongoing research regarding the mechanism of action of established antiepileptic drugs, are continuously increasing the level of complexity in the spectrum of molecular targets relevant for epilepsy therapy. The current state of knowledge as well as the limitations in our understanding should guide future research aiming for a more detailed elucidation of the impact of genetics and pathophysiological mechanisms on interindividual differences in expression and function of antiepileptic drug targets.

A Case Study Examining Change in Teacher Beliefs Through Collaborative Action Research

Science.gov (United States)

Vaino, Katrin; Holbrook, Jack; Rannikmäe, Miia

2013-01-01

The main goal of this study was to explore the role of collaborative action research in eliciting change in teacher beliefs. The beliefs were those of five chemistry teachers in implementing a new teaching approach, geared to enhancing students' scientific and technological literacy (STL). The teacher beliefs were analysed based on Ajzen's Theory of Planned Behaviour (2005) by looking at the teacher's (a) attitude towards implementing STL modules, (b) perceived subjective norms, and (c) behavioural control regarding the new teaching approach. After an introductory year, when teachers familiarised themselves with the new approach, a collaborative action research project was initiated in the second year of the study, helping teachers to minimise or overcome initially perceived constraints when implementing STL modules in their classroom. The processes of teacher change and the course of the project were investigated by teacher interviews, teacher informal commentaries, and meeting records. The formation of positive beliefs towards a STL approach increased continuously, although its extent and character varied depending on the teacher. The close cooperation, in the format of collaborative action research and especially through teacher group reflections and perceived collegial support, did support teacher professional development including change in their beliefs towards the new teaching approach. Additionally, positive feedback gained from other teachers through running a two-day in-service course in year three helped to strengthen all five teachers' existing beliefs towards the new approach. The current research demonstrated that perceived constraints, where identified, can be meaningfully addressed by teachers, through undertaking collaborative action research.

Capturing hammerhead ribozyme structures in action by modulating general base catalysis.

Directory of Open Access Journals (Sweden)

Young-In Chi

2008-09-01

Full Text Available We have obtained precatalytic (enzyme-substrate complex and postcatalytic (enzyme-product complex crystal structures of an active full-length hammerhead RNA that cleaves in the crystal. Using the natural satellite tobacco ringspot virus hammerhead RNA sequence, the self-cleavage reaction was modulated by substituting the general base of the ribozyme, G12, with A12, a purine variant with a much lower pKa that does not significantly perturb the ribozyme's atomic structure. The active, but slowly cleaving, ribozyme thus permitted isolation of enzyme-substrate and enzyme-product complexes without modifying the nucleophile or leaving group of the cleavage reaction, nor any other aspect of the substrate. The predissociation enzyme-product complex structure reveals RNA and metal ion interactions potentially relevant to transition-state stabilization that are absent in precatalytic structures.

Students in Action: Engaging Students with Destination Stakeholders

OpenAIRE

Craggs, Ruth; Gorman, Catherine; Griffin, Kevin; mottiar, ziene; Quinn, Deirdre; Quinn, Bernadette; Ryan, Theresa

2015-01-01

The Students in Action Project in the School of Hospitality Management and Tourism was established in 2012 as a way of engaging students and working with stakeholders in a destination. The overall aim of the project was to immerse students in an active collaborative learning environment within the destination to identify ways in which tourism could be enhanced. In the 2014/2015 academic year the project involved over 300 students from a variety of programmes and modules working with local sta...

Molecular Mechanism of Action for Allosteric Modulators and Agonists in CC-chemokine Receptor 5 (CCR5)

DEFF Research Database (Denmark)

Karlshøj, Stefanie; Amarandi, Roxana Maria; Larsen, Olav

2016-01-01

The small molecule metal ion chelators bipyridine and terpyridine complexed with Zn(2+) (ZnBip and ZnTerp) act as CCR5 agonists and strong positive allosteric modulators of CCL3 binding to CCR5, weak modulators of CCL4 binding, and competitors for CCL5 binding. Here we describe their binding site......Terp binds deeply in the major binding pocket and, in contrast to ZnBip, interacts directly with the Trp-248(VI:13/6.48) microswitch, contributing to its 8-fold higher potency. The impact of Trp-248 was further confirmed by ZnClTerp, a chloro-substituted version of ZnTerp that showed no inherent agonism...

What's she doing in the kitchen? Context helps when actions are hard to recognize.

Science.gov (United States)

Wurm, Moritz F; Schubotz, Ricarda I

2017-04-01

Specific spatial environments are often indicative of where certain actions may take place: In kitchens we prepare food, and in bathrooms we engage in personal hygiene, but not vice versa. In action recognition, contextual cues may constrain an observer's expectations toward actions that are more strongly associated with a particular context than others. Such cues should become particularly helpful when the action itself is difficult to recognize. However, to date only easily identifiable actions were investigated, and the effects of context on recognition were rather interfering than facilitatory. To test whether context also facilitates action recognition, we measured recognition performance of hardly identifiable actions that took place in compatible, incompatible, and neutral contextual settings. Action information was degraded by pixelizing the area of the object manipulation while the room in which the action took place remained fully visible. We found significantly higher accuracy for actions that took place in compatible compared to incompatible and neutral settings, indicating facilitation. Additionally, action recognition was slower in incompatible settings than in compatible and neutral settings, indicating interference. Together, our findings demonstrate that contextual information is effectively exploited during action observation, in particular when visual information about the action itself is sparse. Differential effects on speed and accuracy suggest that contexts modulate action recognition at different levels of processing. Our findings emphasize the importance of contextual information in comprehensive, ecologically valid models of action recognition.

The implementation of multi-task geophysical survey to locate Cleopatra Tomb at Tap-Osiris Magna, Borg El-Arab, Alexandria, Egypt “Phase II”

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Abbas M. Abbas

2012-06-01

VLF-EM data were collected along parallel lines covering the investigated site with a line-to-line spacing of 1 m. The point-to-point distance of 1 m along the same line was employed. The data were qualitatively interpreted by Fraser filtering process and quantitatively by 2-D VLF inversion of tipper data and forward modeling. Results obtained from VLF-EM interpretation are correlated with 2-D resistivity imaging and drilling information. Findings showed a highly resistive zone at a depth extended from about 25–45 m buried beneath Osiris temple, which could be indicated as the tomb of Cleopatra and Anthony. This result is supported by Fraser filtering and forward modeling results. The depth of archeological findings as indicated from the geophysical survey is correlated well with the depth expected by archeologists, as well as, the depth of discovered tombs outside Tap-Osiris Magna temple. This depth level has not been reached by drilling in this site. We hope that the site can be excavated in the future based on these geophysical results.

Utilização da safena magna in situ para arterialização do arco venoso do pé The great saphenous vein in situ for the arterialization of the venous arch of the foot

Directory of Open Access Journals (Sweden)

Cesar Roberto Busato

2010-09-01

Full Text Available CONTEXTO: O tratamento da isquemia crítica de membros inferiores sem leito arterial distal pode ser realizado por meio da inversão do fluxo no arco venoso do pé. OBJETIVO: O objetivo deste trabalho foi apresentar a técnica e os resultados obtidos com a arterialização do arco venoso do pé, mantendo a safena magna in situ. MÉTODOS: Dezoito pacientes, dos quais 11 com aterosclerose (AO, 6 com tromboangeíte obliterante (TO e 1 com trombose de aneurisma de artéria poplítea (TA foram submetidos ao método. A safena magna in situ foi anastomosada à melhor artéria doadora. O fluxo arterial derivado para o sistema venoso progride por meio da veia cujas válvulas são destruídas. As colaterais da veia safena magna são ligadas desde a anastomose até o maléolo medial, a partir do qual são preservadas. RESULTADOS: Dos pacientes, 10 (55,6% mantiveram suas extremidades, 5 com AO e 5 com TO; 7 (38,9% foram amputados, 5 com AO, 1 com TO e 1 com Ta; houve 1 óbito (5,5%. CONCLUSÃO: A inversão do fluxo arterial no sistema venoso do pé deve ser considerada para salvamento de extremidade com isquemia crítica sem leito arterial distal.BACKGROUND: Critical lower limb ischemia in the absence of a distal arterial bed can be treated by arterialization of the venous arch of the foot. OBJETIVE: The objective of this paper was to present the technique and the results of the arterialization of the venous arch of the foot with the in situ great saphenous vein. METHODS: Eighteen patients, 11 with atherosclerosis (AO, 6 with thromboangiitis obliterans (TO and 1 with popliteal artery aneurysm thrombosis were submitted to venous arch arterialization. The in situ great saphenous vein was anastomosed to the best donor artery. Arterial flow derived from the venous system progresses through the vein whose valves were destroyed. The collateral vessels of the great saphenous vein are linked from the anastomosis to the medial malleolus and preserved from this point

Self-acceleration of relativistic modulated beams

International Nuclear Information System (INIS)

Ajzatskij, N.I.

1989-01-01

Unlike the case of self-acceleration of continuous beams, the self-acceleration of relativistic modulated beams requires the energy redistribution between the particles not at the period of excited oscillations but rather between the bunches. This may occur only in the case when the electron beam creates a multifrequency equilibrium state in the passive structure. In this case, there is a possibility for some bunches to be captured in the accelerating phase of the field without any external action. The authors have analyzed this possibility both theoretically and experimentally. 12 refs., 2 figs

Irreducible Specht modules are signed Young modules

OpenAIRE

Hemmer, David J.

2005-01-01

Recently Donkin defined signed Young modules as a simultaneous generalization of Young and twisted Young modules for the symmetric group. We show that in odd characteristic, if a Specht module $S^\\lambda$ is irreducible, then $S^\\lambda$ is a signed Young module. Thus the set of irreducible Specht modules coincides with the set of irreducible signed Young modules. This provides evidence for our conjecture that the signed Young modules are precisely the class of indecomposable self-dual module...

A simplified approach to the PROMETHEE method for priority setting in management of mine action projects

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Marko Mladineo

2016-12-01

Full Text Available In the last 20 years, priority setting in mine actions, i.e. in humanitarian demining, has become an increasingly important topic. Given that mine action projects require management and decision-making based on a multi -criteria approach, multi-criteria decision-making methods like PROMETHEE and AHP have been used worldwide for priority setting. However, from the aspect of mine action, where stakeholders in the decision-making process for priority setting are project managers, local politicians, leaders of different humanitarian organizations, or similar, applying these methods can be difficult. Therefore, a specialized web-based decision support system (Web DSS for priority setting, developed as part of the FP7 project TIRAMISU, has been extended using a module for developing custom priority setting scenarios in line with an exceptionally easy, user-friendly approach. The idea behind this research is to simplify the multi-criteria analysis based on the PROMETHEE method. Therefore, a simplified PROMETHEE method based on statistical analysis for automated suggestions of parameters such as preference function thresholds, interactive selection of criteria weights, and easy input of criteria evaluations is presented in this paper. The result is web-based DSS that can be applied worldwide for priority setting in mine action. Additionally, the management of mine action projects is supported using modules for providing spatial data based on the geographic information system (GIS. In this paper, the benefits and limitations of a simplified PROMETHEE method are presented using a case study involving mine action projects, and subsequently, certain proposals are given for the further research.

Language for action: Motor resonance during the processing of human and robotic voices.

Science.gov (United States)

Di Cesare, G; Errante, A; Marchi, M; Cuccio, V

2017-11-01

In this fMRI study we evaluated whether the auditory processing of action verbs pronounced by a human or a robotic voice in the imperative mood differently modulates the activation of the mirror neuron system (MNs). The study produced three results. First, the activation pattern found during listening to action verbs was very similar in both the robot and human conditions. Second, the processing of action verbs compared to abstract verbs determined the activation of the fronto-parietal circuit classically involved during the action goal understanding. Third, and most importantly, listening to action verbs compared to abstract verbs produced activation of the anterior part of the supramarginal gyrus (aSMG) regardless of the condition (human and robot) and in the absence of any object name. The supramarginal gyrus is a region considered to underpin hand-object interaction and associated to the processing of affordances. These results suggest that listening to action verbs may trigger the recruitment of motor representations characterizing affordances and action execution, coherently with the predictive nature of motor simulation that not only allows us to re-enact motor knowledge to understand others' actions but also prepares us for the actions we might need to carry out. Copyright © 2017 Elsevier Inc. All rights reserved.

Disentangling the influence of parasite genotype, host genotype and maternal environment on different stages of bacterial infection in Daphnia magna.

Science.gov (United States)

Hall, Matthew D; Ebert, Dieter

2012-08-22

Individuals naturally vary in the severity of infectious disease when exposed to a parasite. Dissecting this variation into genetic and environmental components can reveal whether or not this variation depends on the host genotype, parasite genotype or a range of environmental conditions. Complicating this task, however, is that the symptoms of disease result from the combined effect of a series of events, from the initial encounter between a host and parasite, through to the activation of the host immune system and the exploitation of host resources. Here, we use the crustacean Daphnia magna and its parasite Pasteuria ramosa to show how disentangling genetic and environmental factors at different stages of infection improves our understanding of the processes shaping infectious disease. Using compatible host-parasite combinations, we experimentally exclude variation in the ability of a parasite to penetrate the host, from measures of parasite clearance, the reduction in host fecundity and the proliferation of the parasite. We show how parasite resistance consists of two components that vary in environmental sensitivity, how the maternal environment influences all measured aspects of the within-host infection process and how host-parasite interactions following the penetration of the parasite into the host have a distinct temporal component.

Progress in the structural understanding of voltage-gated calcium channel (CaV) function and modulation.

Science.gov (United States)

Minor, Daniel L; Findeisen, Felix

2010-01-01

Voltage-gated calcium channels (CaVs) are large, transmembrane multiprotein complexes that couple membrane depolarization to cellular calcium entry. These channels are central to cardiac action potential propagation, neurotransmitter and hormone release, muscle contraction, and calcium-dependent gene transcription. Over the past six years, the advent of high-resolution structural studies of CaV components from different isoforms and CaV modulators has begun to reveal the architecture that underlies the exceptionally rich feedback modulation that controls CaV action. These descriptions of CaV molecular anatomy have provided new, structure-based insights into the mechanisms by which particular channel elements affect voltage-dependent inactivation (VDI), calcium‑dependent inactivation (CDI), and calcium‑dependent facilitation (CDF). The initial successes have been achieved through structural studies of soluble channel domains and modulator proteins and have proven most powerful when paired with biochemical and functional studies that validate ideas inspired by the structures. Here, we review the progress in this growing area and highlight some key open challenges for future efforts.

Dietary Modulation of Inflammation-Induced Colorectal Cancer through PPARγ

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Ashlee B. Carter

2009-01-01

Full Text Available Mounting evidence suggests that the risk of developing colorectal cancer (CRC is dramatically increased for patients with chronic inflammatory diseases. For instance, patients with Crohn's Disease (CD or Ulcerative Colitis (UC have a 12–20% increased risk for developing CRC. Preventive strategies utilizing nontoxic natural compounds that modulate immune responses could be successful in the suppression of inflammation-driven colorectal cancer in high-risk groups. The increase of peroxisome proliferator-activated receptor-γ (PPAR-γ expression and its transcriptional activity has been identified as a target for anti-inflammatory efforts, and the suppression of inflammation-driven colon cancer. PPARγ down-modulates inflammation and elicits antiproliferative and proapoptotic actions in epithelial cells. All of which may decrease the risk for inflammation-induced CRC. This review will focus on the use of orally active, naturally occurring chemopreventive approaches against inflammation-induced CRC that target PPARγ and therefore down-modulate inflammation.

The influence of bacteria-dominated diets on Daphnia magna somatic growth, reproduction, and lipid composition.

Science.gov (United States)

Taipale, Sami J; Brett, Michael T; Pulkkinen, Katja; Kainz, Martin J

2012-10-01

We explored how dietary bacteria affect the life history traits and biochemical composition of Daphnia magna, using three bacteria taxa with very different lipid composition. Our objectives were to (1) examine whether and how bacteria-dominated diets affect Daphnia survival, growth, and fecundity, (2) see whether bacteria-specific fatty acid (FA) biomarkers accrued in Daphnia lipids, and (3) explore the quantitative relationship between bacteria availability in Daphnia diets and the amounts of bacterial FA in their lipids. Daphnia were fed monospecific and mixed diets of heterotrophic (Micrococcus luteus) or methanotrophic bacteria (Methylomonas methanica and Methylosinus trichosporium) and two phytoplankton species (Cryptomonas ozolinii and Scenedesmus obliquus). Daphnia neonates fed pure bacteria diets died after 6-12 days and produced no viable offspring, whereas those fed pure phytoplankton diets had high survival, growth, and reproduction success. Daphnia fed a mixed diet with 80% M. luteus and 20% of either phytoplankton had high somatic growth, but low reproduction. Conversely, Daphnia fed mixed diets including 80% of either methane-oxidizing bacteria and 20% Cryptomonas had high reproduction rates, but low somatic growth. All Daphnia fed mixed bacteria and phytoplankton diets had strong evidence of both bacteria- and phytoplankton-specific FA biomarkers in their lipids. FA mixing model calculations indicated that Daphnia that received 80% of their carbon from bacteria assimilated 46 ± 25% of their FA from this source. A bacteria-phytoplankton gradient experiment showed a strong positive correlation between the proportions of the bacterial FA in the Daphnia and their diet, indicating that bacterial utilization can be traced in this keystone consumer using FA biomarkers. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

A new method to consider human actions in the framework of a dynamic PSA

International Nuclear Information System (INIS)

Kloos, M.; Peschke, J.

2006-01-01

The variety of accident sequences to be considered in the framework of a PSA derives from mutual dependencies between the physical process, the behaviour of the technical system, human actions and stochastic influences along the time axis. Because the conventional PSA approach is not able to adequately account for these interactions, so-called probabilistic dynamics methods have been developed. They generally achieve a more realistic modelling of accident scenarios and a more realistic safety assessment. At GRS, the method MCDET - a combination of Monte Carlo Simulation und the Discrete Dynamic Event Tree method - was developed. The implementation of MCDET was supplemented by a so called Crew-Module which allows - together with a deterministic dynamics code - to simulate human actions as a dynamic process evolving over time in interaction with the system and process dynamics. The Crew-Module accounts for communications between crew members and for performance shaping factors like stress, knowledge or ergonomics. This paper presents the Crew- Module and gives an overview of the results which may be obtained from its combination with MCDET and a deterministic dynamics code. The emergency operating procedure 'Secondary Side Bleed and Feed' in a German PWR is selected as an illustrative application. (authors)

ROBOT LEARNING OF OBJECT MANIPULATION TASK ACTIONS FROM HUMAN DEMONSTRATIONS

Directory of Open Access Journals (Sweden)

Maria Kyrarini

2017-08-01

Full Text Available Robot learning from demonstration is a method which enables robots to learn in a similar way as humans. In this paper, a framework that enables robots to learn from multiple human demonstrations via kinesthetic teaching is presented. The subject of learning is a high-level sequence of actions, as well as the low-level trajectories necessary to be followed by the robot to perform the object manipulation task. The multiple human demonstrations are recorded and only the most similar demonstrations are selected for robot learning. The high-level learning module identifies the sequence of actions of the demonstrated task. Using Dynamic Time Warping (DTW and Gaussian Mixture Model (GMM, the model of demonstrated trajectories is learned. The learned trajectory is generated by Gaussian mixture regression (GMR from the learned Gaussian mixture model.  In online working phase, the sequence of actions is identified and experimental results show that the robot performs the learned task successfully.

Action prediction in younger versus older adults: neural correlates of motor familiarity.

Directory of Open Access Journals (Sweden)

Nadine Diersch

Full Text Available Generating predictions during action observation is essential for efficient navigation through our social environment. With age, the sensitivity in action prediction declines. In younger adults, the action observation network (AON, consisting of premotor, parietal and occipitotemporal cortices, has been implicated in transforming executed and observed actions into a common code. Much less is known about age-related changes in the neural representation of observed actions. Using fMRI, the present study measured brain activity in younger and older adults during the prediction of temporarily occluded actions (figure skating elements and simple movement exercises. All participants were highly familiar with the movement exercises whereas only some participants were experienced figure skaters. With respect to the AON, the results confirm that this network was preferentially engaged for the more familiar movement exercises. Compared to younger adults, older adults recruited visual regions to perform the task and, additionally, the hippocampus and caudate when the observed actions were familiar to them. Thus, instead of effectively exploiting the sensorimotor matching properties of the AON, older adults seemed to rely predominantly on the visual dynamics of the observed actions to perform the task. Our data further suggest that the caudate played an important role during the prediction of the less familiar figure skating elements in better-performing groups. Together, these findings show that action prediction engages a distributed network in the brain, which is modulated by the content of the observed actions and the age and experience of the observer.

Intracellular conversion of environmental nitrate and nitrite to nitric oxide with resulting developmental toxicity to the crustacean Daphnia magna.

Directory of Open Access Journals (Sweden)

Bethany R Hannas

2010-08-01

Full Text Available Nitrate and nitrite (jointly referred to herein as NO(x are ubiquitous environmental contaminants to which aquatic organisms are at particularly high risk of exposure. We tested the hypothesis that NO(x undergo intracellular conversion to the potent signaling molecule nitric oxide resulting in the disruption of endocrine-regulated processes.These experiments were performed with insect cells (Drosophila S2 and whole organisms Daphnia magna. We first evaluated the ability of cells to convert nitrate (NO(3(- and nitrite (NO(2(- to nitric oxide using amperometric real-time nitric oxide detection. Both NO(3(- and NO(2(- were converted to nitric oxide in a substrate concentration-dependent manner. Further, nitric oxide trapping and fluorescent visualization studies revealed that perinatal daphnids readily convert NO(2(- to nitric oxide. Next, daphnids were continuously exposed to concentrations of the nitric oxide-donor sodium nitroprusside (positive control and to concentrations of NO(3(- and NO(2(-. All three compounds interfered with normal embryo development and reduced daphnid fecundity. Developmental abnormalities were characteristic of those elicited by compounds that interfere with ecdysteroid signaling. However, no compelling evidence was generated to indicate that nitric oxide reduced ecdysteroid titers.Results demonstrate that nitrite elicits developmental and reproductive toxicity at environmentally relevant concentrations due likely to its intracellular conversion to nitric oxide.

Phylogeography of Daphnia magna Straus (Crustacea: Cladocera) in Northern Eurasia: Evidence for a deep longitudinal split between mitochondrial lineages.

Science.gov (United States)

Bekker, Eugeniya I; Karabanov, Dmitry P; Galimov, Yan R; Haag, Christoph R; Neretina, Tatiana V; Kotov, Alexey A

2018-01-01

Species with a large geographic distributions present a challenge for phylogeographic studies due to logistic difficulties of obtaining adequate sampling. For instance, in most species with a Holarctic distribution, the majority of studies has concentrated on the European or North American part of the distribution, with the Eastern Palearctic region being notably understudied. Here, we study the phylogeography of the freshwater cladoceran Daphnia magna Straus, 1820 (Crustacea: Cladocera), based on partial mitochondrial COI sequences and using specimens from populations spread longitudinally from westernmost Europe to easternmost Asia, with many samples from previously strongly understudied regions in Siberia and Eastern Asia. The results confirm the previously suspected deep split between Eastern and Western mitochondrial haplotype super-clades. We find a narrow contact zone between these two super-clades in the eastern part of Western Siberia, with proven co-occurrence in a single lake in the Novosibirsk region. However, at present there is no evidence suggesting that the two mitochondrial super-clades represent cryptic species. Rather, they may be explained by secondary contact after expansion from different refugia. Interestingly, Central Siberia has previously been found to be an important contact zone also in other cladoceran species, and may thus be a crucial area for understanding the Eurasian phylogeography of freshwater invertebrates. Together, our study provides an unprecedented complete, while still not global, picture of the phylogeography of this important model species.

A Comparative Study of the Eco toxicity of Palm-Based Methyl Ester Sulphonates (MES) to Tilapia and Daphnia magna

International Nuclear Information System (INIS)

Razmah, G.; Afida, I.S.; Zulina, A.M.; Noorazah, Z.; Hazimah, A.H.

2016-01-01

Methyl ester sulphonates (MES) is a surfactant derived from plant resources, suitable as active ingredient in detergents. MES possesses good surface-active properties, good detergency and tolerant to water hardness. In this study, the eco toxicity of MES was evaluated through the 48 hr Daphnia magna immobilisation test and the 96 hr fish acute toxicity test with Tilapia. MES samples with different alkyl chain lengths (C14, C16 and C16:18) produced by the Malaysian Palm Oil Board (MPOB) and commercial MES (C16:18) were tested. Results from all tests indicated that Daphnia was more sensitive to toxic effects from MES than was Tilapia. There is also significant difference in eco toxicity responses for palm-based MES of various chain lengths regardless of the species tested. The eco toxicity increased as the hydrophobicity of the MES increased due to increase of alkyl chain length. However, less than 30 % of MES is used in detergent products and will not pose environmental effects on aquatic organisms. MES is therefore suitable for environmental compatible cleaning products in view of its eco toxicity that is on par to the widely used anionic surfactants, such as linear alkylbenzene sulphonate (LAS). The use of MES in cleaning products may help the industry to fulfil its social responsibility to a cleaner and better environment. (author)

Modulation of mdm2 pre-mRNA splicing by 9-aminoacridine-PNA (peptide nucleic acid) conjugates targeting intron-exon junctions

DEFF Research Database (Denmark)

Shiraishi, Takehiko; Eysturskard, Jonhard; Nielsen, Peter E

2010-01-01

ABSTRACT: BACKGROUND: Modulation of pre-mRNA splicing by antisense molecules is a promising mechanism of action for gene therapeutic drugs. In this study, we have examined the potential of peptide nucleic acid (PNA) 9-aminoacridine conjugates to modulate the pre-mRNA splicing of the mdm2 human ca...

Signed Young Modules and Simple Specht Modules

OpenAIRE

Danz, Susanne; Lim, Kay Jin

2015-01-01

By a result of Hemmer, every simple Specht module of a finite symmetric group over a field of odd characteristic is a signed Young module. While Specht modules are parametrized by partitions, indecomposable signed Young modules are parametrized by certain pairs of partitions. The main result of this article establishes the signed Young module labels of simple Specht modules. Along the way we prove a number of results concerning indecomposable signed Young modules that are of independent inter...

5-HT1A receptors modulate small-conductance Ca2+-activated K+ channels

DEFF Research Database (Denmark)

Grunnet, Morten; Jespersen, Thomas; Perrier, Jean-François

2004-01-01

Small-conductance calcium-activated potassium channels (SK) are responsible for the medium afterhyperpolarisation (mAHP) following action potentials in neurons. Here we tested the ability of serotonin (5-HT) to modulate the activity of SK channels by coexpressing 5-HT1A receptors with different...

Osmotic and Salt Stresses Modulate Spontaneous and Glutamate-Induced Action Potentials and Distinguish between Growth and Circumnutation in Helianthus annuus Seedlings

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Maria Stolarz

2017-10-01

Full Text Available Action potentials (APs, i.e., long-distance electrical signals, and circumnutations (CN, i.e., endogenous plant organ movements, are shaped by ion fluxes and content in excitable and motor tissues. The appearance of APs and CN as well as growth parameters in seedlings and 3-week old plants of Helianthus annuus treated with osmotic and salt stress (0–500 mOsm were studied. Time-lapse photography and extracellular measurements of electrical potential changes were performed. The hypocotyl length was strongly reduced by the osmotic and salt stress. CN intensity declined due to the osmotic but not salt stress. The period of CN in mild salt stress was similar to the control (~164 min and increased to more than 200 min in osmotic stress. In sunflower seedlings growing in a hydroponic medium, spontaneous APs (SAPs propagating basipetally and acropetally with a velocity of 12–20 cm min−1 were observed. The number of SAPs increased 2–3 times (7–10 SAPs 24 h−1plant−1 in the mild salt stress (160 mOsm NaCl and KCl, compared to the control and strong salt stress (3–4 SAPs 24 h−1 plant−1 in the control and 300 mOsm KCl and NaCl. Glutamate-induced series of APs were inhibited in the strong salt stress-treated seedlings but not at the mild salt stress and osmotic stress. Additionally, in 3-week old plants, the injection of the hypo- or hyperosmotic solution at the base of the sunflower stem evoked series of APs (3–24 APs transmitted along the stem. It has been shown that osmotic and salt stresses modulate differently hypocotyl growth and CN and have an effect on spontaneous and evoked APs in sunflower seedlings. We suggested that potassium, sodium, and chloride ions at stress concentrations in the nutrient medium modulate sunflower excitability and CN.

Uncovering effects of self-control and stimulus-driven action selection on the sense of agency.

Science.gov (United States)

Wang, Yuru; Damen, Tom G E; Aarts, Henk

2017-10-01

The sense of agency refers to feelings of causing one's own action and resulting effect. Previous research indicates that voluntary action selection is an important factor in shaping the sense of agency. Whereas the volitional nature of the sense of agency is well documented, the present study examined whether agency is modulated when action selection shifts from self-control to a more automatic stimulus-driven process. Seventy-two participants performed an auditory Simon task including congruent and incongruent trials to generate automatic stimulus-driven vs. more self-control driven action, respectively. Responses in the Simon task produced a tone and agency was assessed with the intentional binding task - an implicit measure of agency. Results showed a Simon effect and temporal binding effect. However, temporal binding was independent of congruency. These findings suggest that temporal binding, a window to the sense of agency, emerges for both automatic stimulus-driven actions and self-controlled actions. Copyright © 2017 Elsevier Inc. All rights reserved.

Efecto tóxico del DDT, clordano y agua de la presa Ignacio Ramírez (México, sobre Daphnia magna (Crustacea: Daphnidae

Directory of Open Access Journals (Sweden)

Laura Martínez-Tabche

1999-12-01

Full Text Available Actualmente en México son empleados los plaguicidas diclorodifeniltricloroetano (DDT y clordano (CLO para combatir la malaria y termitas. De 1990 a 1996 un total de 27 ton de DDT y 508 de CLO, en forma de productos técnicos, fueron importados. El objetivo de este estudio fue establecer una metodología para determinar el impacto ambiental que pueden producir estos compuestos sobre un embalse. El efecto tóxico del DDT y CLO fue evaluado sobre la actividad de la o-demetilasa (OD y del acetilcolinesterasa (AchA del cladócero Daphnia magna al exponerla a diferentes concentraciones de los insecticidas disueltos en el agua de tres sitios de la presa Ignacio Ramírez (PIR. El efecto del agua contaminada con los insecticidas sobre la actividad de la AChA y OD, así como la CL50, fueron utilizadas como indicadores de exposición para determinar los lugares más contaminadas de la PIR. Las características fisicoquímicas del agua así como la biodiversidad de los sitios en estudio de la presa fueron considerados. Los resultados obtenidos demuestran que la estación cercana a la compuerta exhibe un potencial de toxicidad, ya que las actividades enzimáticas fueron modificadas. Se sugiere utilizar las actividades de AchA y OD del cladócero para evaluar la toxicidad de un cuerpo de agua contaminado por insecticidas organoclorados.Chlorodiphenylnitrichloroethane (DDT and chlordane (CLO are currently used in Mexico to control malaria and termites. From 1990 to 1996 a total of 27 ton of DDT and 508 of CLO were imported. We establish a methodology to determine their environmental impact in a Mexican dam (Ignacio Ramírez. The toxic effect of DDT and CLO were evaluated on the o-demethylase (OD and acethycholinesterase activities (AchA of the cladoceran Daphnia magna exposed to different concentrations of the insecticides solved in water from three sites. Their effect on the AchA and OD activities, and so the CL50 were used as exposure bioindicators to

The link between the use of advanced planning and scheduling (APS) modules and factory context