474. Bianchini, A. and Wood, C.M. (2008) Sodium uptake in different life stages of crustaceans: The water flea Daphnia magna Strauss. J. Exp. Biol. 211 pp: 539-547. (PDF). ...
rdf:RDF xmlns:dcterms="http://purl.org/dc/terms/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:bibo="http://purl.org/ontology/bibo/" xmlns:dspace="http://digital-repositories.org/ontologies/dspace/0.1.0#" xmlns:foaf="http://xmlns.com/foaf/0.1/" xmlns:void="http://rdfs.org/ns/void#" xmlns:xsd="http://www.w3.org/2001/XMLSchema#" , ,rdf:Description rdf:about="https://kops.uni-konstanz.de/rdf/resource/123456789/17951", ,dcterms:abstract xml:lang="eng",Small filter-feeding zooplankton organisms like the cladoceran Daphnia spp. are key members of freshwater food webs. Although several interactions between Daphnia and bacteria have been investigated, the importance of the microbial communities inside Daphnia guts has been studied only poorly so far. In the present study, we characterised the bacterial community composition inside the digestive tract of a laboratory-reared clonal culture of Daphnia magna using 16S rRNA gene libraries and ...
Data on the population dynamics of five Daphnia species, viz. D. galeata mendotae, D. obtusa, D. pulicaria, D. pulex and D. magna, were collected from the literature. The experiments with constant food input were re-analysed for the oscillatory behaviour of the populations. Some populations appear to stabilize, whereas others continue to fluctuate. Some fluctuations are apparently caused by external factors. A decline to far below the average population size is always followed by a large population overshoot. Even populations that tend to stabilize do so by way of a series of damped oscillations. The oscillation period depends on, among other things, the Daphnia species, and increases with its size. Sometimes the same feeding regime leads to an equal or greater population size for a larger Daphnia species. This suggests that the chosen food species was not equally suitable for the two Daphnia species. No effect of crowding on the population size of Daphnia is found.
Water flea eye. Polarised light micrograph of the eye of a Sida crystallina water flea. Water fleas (order Cladocera) are small crustaceans, commonly found in fresh water. They are filter feeders that ingest algae, protozoa or organic matter, and are a constituent of plankton. Magnification: x400 when printed 10 centimetres wide. - Stock Image C028/9152
There is considerable interest in the pathways by which carbon and growth-limiting elemental and biochemical nutrients are supplied to upper trophic levels. Fatty acids and sterols are among the most important molecules transferred across the plant-animal interface of food webs. In lake ecosystems, in addition to phytoplankton, bacteria and terrestrial organic matter are potential trophic resources for zooplankton, especially in those receiving high terrestrial organic matter inputs. We therefore tested carbon, nitrogen, and fatty acid assimilation by the crustacean Daphnia magna when consuming these resources. We fed Daphnia with monospecific diets of high-quality (Cryptomonas marssonii) and intermediate-quality (Chlamydomonas sp. and Scenedesmus gracilis) phytoplankton species, two heterotrophic bacterial strains, and particles from the globally dispersed riparian grass, Phragmites australis, representing terrestrial particulate organic carbon (t-POC). We also fed Daphnia with various mixed ...
Microcrustacean emergence from the dry sediments is an important colonization pathway that allows these microfauna to recover and repopulate temporary aquatic habitats after months or years of dryness. Viable microcrustacean propagules in sediments of three different temporary aquatic habitats - rainpools located within the rarely flooded portions, frequently flooded floodplains and rarely flooded floodplains - were assessed experimentally by flooding the soils. Three major groups of microcrustaceans - cladocerans, copepods and ostracods - emerged from the sediments. Species richness and mean total numbers of emerged microcrustaceans per sample varied across the studied temporary aquatic habitats (Kruskal-Wallis, p , 0.05). Both species richness and mean total number of emerged microcrustacean per sample were lowest in sediments of rarely flooded floodplains. The highest species richness of microcrustaceans emerged from the treatments with soils of the frequently flooded floodplains. The mean ...
During their aquatic life cycle, nanoparticles are subject to environmentally driven surface modifications (e.g. agglomeration or coating) associated with aging. Although the ecotoxicological potential of nanoparticles might be affected by these processes, only limited information about the potential impact of aging is available. In this context, the present study investigated acute (96 h) and chronic (21 d) implications of systematically aged titanium dioxide nanoparticles (nTiO2; ~90 nm) on the standard test species Daphnia magna by following the respective test guidelines. The nTiO2 were aged for 0, 1, 3 and 6 d in media with varying ionic strengths (Milli-Q water: approx. 0.00 mmol/L and ASTM: 9.25 mmol/L) in the presence or absence of natural organic matter (NOM). Irrespective of the other parameters, aging in Milli-Q did not change the acute toxicity relative to an unaged control. In contrast, 6 d aged nTiO2 in ASTM without NOM caused a fourfold decreased acute toxicity. Relative to the 0 d aged
Predation is a primary force driving adaptation in prey. When predatory threats are fluctuating in natural environments, inducible defences may evolve in prey organisms. For example, behavioural adaptations reduce the chance of predator encounter and life-history changes increase survival chances under size selective predation [1]. Prominent examples of inducible defences are the various defensive morphological traits observed in the model freshwater crustacean Daphnia. Several Daphnia species display spectacular morphological defences [2,3] including crowns of thorns [4], spines [5], crests [6] and helmets [7-9]. All these defensive strategies are induced via predator-specific chemical cues known as kairomones. The chemical perception of kairomones initiates a series of internal physiological reactions including neuronal signal integration [10] and subsequent conversion into endocrine agents [11-13]. These substances in turn modulate developmental changes, which result in the growth of a ...
Daphnia pulex (Water flea) is the first fully sequenced crustacean genome. The crustaceans and insects have diverged from a common ancestor. It is a model organism for studying the molecular makeup for coping with the environmental challenges. In the complete proteome, there are 30,550 putative proteins. However, about 10,000 of them have no known homologues. Currently, the UniProtoKB reports on 95% of the Daphnias proteins as putative and uncharacterized proteins. We have applied ProtoNet, an unsupervised hierarchical protein clustering method that covers about 10 million sequences, for automatic annotation of the Daphnias proteome. 98.7% (26,625) of the Daphnia full-length proteins were successfully mapped to 13,880 ProtoNet stable clusters, and only 1.3% remained unmapped. We compared the properties of the Daphnias protein families with those of the mouse and the fruitfly proteomes. Functional annotations were successfully assigned for 86% of the proteins. Most proteins (61%) were mapped to only
Daphnia (Daphnia pulex) is the most common freshwater species known to tropical fish keeping enthusiasts as Water Fleas, Moina, or Water Bugs.
Microbial polysaccharides, due to their unique physiochemical properties, have found application in the food industry, cosmetics, pharmacy and medicine. In the environment, microbes can use polysaccharides to alleviate the adverse effects of heavy metals in their close proximity. This adaptive property shows interesting potential for bioremediation. Herein, the effects of the exopolysaccharides (EPS) levan, produced by the bacterium Bacillus licheniformis NS032 and pullulan, produced by the fungus Aureobasidium pullulans CH-1 in the presence of copper (Cu2+) have been investigated for the first time on antioxidant enzyme activity, respiration and Cu2+ bioaccumulation of Daphnia magna as well as the bioluminescence of Vibrio fischeri. Both EPS decreased toxicity of Cu2+ in the acute test with D. magna. The activity of catalase (CAT) was significantly diminished after acute exposure to Cu2+ in comparison to treatments with Cu2+ and EPS, while in the prolonged acute exposure the CAT activ...ity did ...
This Iowan eighth-grader turned her love of nature into a long-term study of water pollution. Shes continuing to investigate the mysterious growths that have formed on her Daphnia magna.
Introduction. The effect of caffeine on heart rate Aim: To investigate the effect of caffeine on the heart rate of Daphnia (water fleas). Introduction: Plants produce caffeine as an insecticide. Cocoa in South America, coffee in Africa and tea in Asia have all been used for hundreds of years to produce pick me up drinks containing caffeine. These days, caffeine is also used as a flavour enhancer in a wide range of cola and other soft drinks. ...read more. Middle. This can lead to heart and circulation problems. Daphnia are small, planktonic crustaceans commonly called water fleas because of their saltatory swimming style (although fleas are insects and thus only very distantly related). They live in various aquatic environments ranging from acidic swamps to freshwater lakes, ponds, streams and rivers. Hypothesis: Caffeine will increase the heart rate of the Daphnia (water fleas). Equipment needed: * Culture of Daphnia (water fleas) * Cavity slides * Dropping pipettes * Distilled water and pond ...
We reconstructed the genetic structure of a planktonic crustacean Daphnia longispina living in high mountain lakes and ponds in the Pyrenees to investigate whether it was shaped by persistent founder effects originating shortly after the last glacial maximum or by ongoing dispersal and effective migration (gene flow). We found that the genetic structure can largely be explained by a single colonization event following gradual deglaciation of the Pyrenees c. 10-15 000 years ago. Nuclear genetic diversity declined steeply from southeast to northwest, suggestive of serial colonization of available habitats with advancing deglaciation. The spatial genetic structure suggests that founder effects were major determinants of the present-day diversity, both at the catchment level and at the level of individual water bodies, further supporting extremely low effective migration rates. This study reveals a prime example of a founder effect that is both long-lasting and maintained at small spatial scales. ...
To study on a spatial scale the composition of Daphnia populations we surveyed Daphnia populations north and south of the Swiss Alps. We found that Lakes North of the Alps were invaded with one species (D. galeata) and hypothesize that lakes south of the Alps were invaded with D. longispina. A first life history experiment shows some evidence for this hypothesis. Further, testing of this hypothesis needs to come from sediment cores from lakes from the south side of the alps. I will present recent data about these studies.. 10.06.2013. Urban Friberg - "Genetics of sexual dimorphism". Evolutionary Biology Centre, Uppsala University, Sweden. Abstract: Evolution of sexual dimorphism (SD) is a paradox. On the one hand it shouldbe constrained, because it is restricted to occur only through geneexpression and because it relies on gene expression having a sex-specificgenetic architecture. On the other hand SD is common and SD traits are amongthose that evolve the fastest. How is this possible? Is ...
Acute Toxicity Evaluation to Daphnia magna of Disease Resistant(OsCK1) Rice - Daphnia magna;Disease resistant transgenic rice;Risk assessment;
The common evergreen dwarf shrub Empetrum hormaphroditum has influence on the functioning of boreal terrestrial ecosystems in northern Sweden. The negative effects of E. hermaphroditum are partly attributed to the production of the dihydrostilbene, batatasin-III, which is released from leaves and litter by rain and snowmelt. In this study, we investigated whether batatasin-III is carried by runoff into streams and lakes during the snowmelt period and whether it is also potentially hazardous to aquatic fauna. Sampling of water from streams and a lake for which the surrounding terrestrial vegetation is dominated by E. hermaphroditum was done during the snowmelt period in May 1993 and in 1998, and analyzed for batatasin-III. Using 24- and 48-hr standard toxicity tests, we analyzed toxicity to brown trout (Salmo trutta) alevins and juvenile water fleas (Daphnia magna). Toxicity (proportion of dead individuals) to trout was tested at pH 6.5 and compared with that of a phenol within a range of ...
From York University - quite possibly the most poorly written science by press release Ive seen this year. The leaps of may are profound, and the footbal team analogy is designed to elicit sympathy. I suppose if Daphnia populations were collapsing in lakes due to lack of helmets and shoulder pads, wed see a collapse…
We show that the stable (C, N, O) isotopic composition of the water flea Daphnia pulicaria is strongly related to that of its diet (C, N) and the water they live in (O). We also show that the stable isotopic composition of the sheaths of Daphnia resting eggs (ephippia) is indicative of the isotopic composition of Daphnia that produced them. This implies that stable isotope ratios of fossil Daphnia ephippia can provide information on past ecological and climatic developments in and around lakes ...
Sigma-Aldrich offers abstracts and full-text articles by [David J Civitello, Rachel M Penczykowski, Aimee N Smith, Marta S Shocket, Meghan A Duffy, Spencer R Hall].
The dual role of recombination in TE proliferation has generated great interest in the effects of sexual versus asexual reproduction on TE loads in the genome over time (Arkhipova & Meselson 2000; Wright & Finnegan 2001; Dolgin & Charlesworth 2006). Sex can facilitate the spread of a new TE throughout a population, but it also provides a mechanism through which new copies can be lost. Thus, sex can lead to an accelerated rate of increase and decrease in TEs over time relative to asexuals, and also impact the distribution of TEs among individuals within a population where sex has been lost (Schaack et al. in press). We surveyed six families of transposable elements in populations of D. pulex, which reproduce either with or without sex and find that both the number and distribution of TEs differ between cyclical parthenogens and obligate asexuals, despite the fact that obligately asexual populations in this species are thought to be relatively young (Lynch et al. 2008). Even though purging ...
Background The cladoceran crustacean Daphnia pulexproduces female offspring by parthenogenesis under favorable conditions, but in response to various unfavorable external stimuli, it produces male...
THE efficacy of natural selection may be severely reduced in asexual compared to sexual organisms due to the absence of recombination and segregation (Fisher 1930; Barton and Charlesworth 1998; Otto and Lenormand 2002; Agrawal 2006). Consequently, asexual populations may adapt more slowly to changing environments (Peck 1994; Orr 2000; Roze and Barton 2006) and suffer from an increased genetic load (Muller 1964; Crow and Kimura 1970; Pamilo et al. 1987; Kondrashov 1988; Charlesworth 1994). Both of these factors may contribute to the rarity of obligate asexuality in eukaryotes (Bell 1982), despite its immediate advantages over sexual reproduction (Maynard Smith 1978). The main reason for the decreased efficiency of selection in asexual organisms is that due to the complete linkage of their genomes, selection cannot operate on different mutations independently (the Hill-Robertson effect, Hill and Robertson 1966). Thus, deleterious mutations anywhere in the genome reduce the effective population ...
Every day we are exposed to carcinogens, including ultraviolet radiation (UVR). High levels of ultraviolet radiation are known to cause DNA damage. One of the most common forms of UVR-induced damage, the pyrimidine dimer, is repaired by an enzymatic reaction powered by visible light. We wanted to find out if there is variation in the level of UVR-induced DNA damage induced in two different clones of Daphnia magna, a model organism for ecotoxicology. One clone was derived from a mid-latitude deep reservoir, where escape from UVR is possible via vertical migration. The second clone was from a high-latitude shallow rock pool, where D. magna are exposed to high levels of UVR. Pregnant mothers from each clone line were subjected to ecologically relevant levels of UVR in the lab. Immediately afterwards, we extracted the embryos, suspended the cells in agarose, and performed a comet assay, which allows for quantification of DNA damage within individual cells. The slides were viewed under a fluorescent
The primary objective of the test is to assess the effect of chemicals on the rate of reproduction of Daphnia magna. The concentrations used in the study are based on the results of an acute immobilisation test. The duration of the study is 21 days and the number of offspring produced, together with adult and juvenile survival, is reported. A semi-static system is recommended and the frequency of test media renewal depends on the stability of the substance. The study is started with juveniles which are female and start to produce live young by parthenogenesis after about 7 days.. Juvenile production is compared to that of the controls to determine the lowest observed effect concentration (LOEC) and the no effect concentration (NOEC) in addition of the EC50. Other adverse effects are recorded such as abnormal development of juveniles in the brood pouch (white eggs). Shedding of un-hatched eggs, presence of male Daphnia, ephippial eggs and differences in the size of adults at the end of the test ...
WALSER, B. and HAAG, C. R. (2012), Strong intraspecific variation in genetic diversity and genetic differentiation in Daphnia magna: the effects of population turnover and population size. Molecular Ecology, 21: 851-861. doi: 10.1111/j.1365-294X.2011.05416.x ...
Cry-toxin genes originating from Bacillus thuringiensis are inserted into genetically modified (GM) plants, often called Bt-plants, to provide insect resistance to pests. Significant amounts of Bt-plant residues, and thus Cry-toxins, will be shed to soil and aquatic environments. We exposed Daphnia magna to purified Cry1Ab and Cry2Aa toxins for the full life-span of the animals. We used single toxins in different doses and combinations of toxins and Roundup, another potential stressor on the rise in agricultural ecosystems. Animals exposed to 4.5 mg/L (ppm) of Cry1Ab, Cry2Aa and the combination of both showed markedly higher mortality, smaller body size and very low juvenile production compared to controls. Animals exposed to 0.75 mg/L also showed a tendency towards increased mortality but with increased early fecundity compared to the controls. Roundup stimulated animals to strong early reproductive output at the cost of later rapid mortality. We conclude that i) purified Cry-toxins in high ...
Yang, Y.; May, L.; Gunn, I.D.M.; Huang, X.; Liu, J.. 1999 Comparative studies on effects of predation by fish on Daphnia in Lake Donghu (China) and Loch Leven (Scotland). In: Ecosystem Approaches for Fisheries Management. American Fisheries Society, 265-281. (Alaska Sea Grant Report, 1). Full text not available from this repository. (Request a copy ...
Zeis et al. (2004) recently reported that hemoglobin concentration in daphnids increased with increasing temperature. Mitchell (2001) noted a low incidence of sexually ambiguous offspring when daphnids were reared at 30°C. Elevated temperature may prove to be an environmental signal that stimulates both hemoglobin induction and male sex determination through the common signaling pathway. Preliminary experiments in our laboratory support this premise. However, elevated temperature may stimulate different signaling pathways, resulting in multiple outcomes. For example, oxygen saturation decreases with increasing water temperature, which may stimulate hemoglobin production via the hypoxia signaling pathway. Increased temperature may also adversely impact the uptake or assimilation of nutrients resulting in male production via the terpenoid signaling pathway.. The minimum components to the putative terpenoid signaling pathway described in this study would consist of the hormone (i.e. methyl ...
PubMed Central Canada (PMC Canada) provides free access to a stable and permanent online digital archive of full-text, peer-reviewed health and life sciences research publications. It builds on PubMed Central (PMC), the U.S. National Institutes of Health (NIH) free digital archive of biomedical and life sciences journal literature and is a member of the broader PMC International (PMCI) network of e-repositories.
The last ten years have witnessed increasing interest in host-pathogen interactions involving invertebrate hosts. The invertebrate innate immune system is now relatively well characterised, but in a limited range of genetic model organisms and under a limited number of conditions. Immune systems have been little studied under real-world scenarios of environmental variation and parasitism. Thus, we have investigated expression of candidate innate immune system genes in the water flea Daphnia, a model organism for ecological genetics, and whose capacity for clonal reproduction facilitates an exceptionally rigorous control of exposure dose or the study of responses at many time points. A unique characteristic of the particular Daphnia clones and pathogen strain combinations used presently is that they have been shown to be involved in specific host-pathogen coevolutionary interactions in the wild. We choose five genes, which are strong candidates to be involved in Daphnia-pathogen interactions, ...
Food quality is highly dynamic within lake ecosystems and varies spatially and temporally over the growing season. Consumers may need to continuously adjust their metabolism in response to this variation in dietary nutrient content. However, the rate of metabolic responses to changes in food nutrient content has received little direct study. Here, we examine responses in two metabolic phosphorus (P) pools, ribonucleic acids (RNA), and adenosine triphosphate (ATP) along with body mass and body P content in Daphnia magna exposed to chronic and acute dietary P-limitation. First, we examined food quality effects on animals consuming different food carbon (C):P quality over a 14 day period. Then, we raised daphnids on one food quality for 4 days, switched them to contrasting dietary treatments, and measured changes in their metabolic responses at shorter time-scales (over 48 h). Animal P, RNA, and ATP content all changed through ontogeny with adults containing relatively less of these pools with increasing
Daphnia are tiny crustaceans, closely related to a shrimp. They are often called "water fleas." They are small, but not microscopic. They can be seen with the naked eye, but you will need a dissecting microscope to view the beating heart. Daphnia can be purchased from any of the companies that sell lab supplies and equipment. Since Daphnia are arthropods, they demonstrate the three major arthropod characteristics: exoskeleton, jointed appendages, and segmented body. The exoskeleton is clear, allowing the student to easily view the heart. Daphnia are ectotherms and their body temperature changes with the surrounding environment. This further means that there is a direct relationship between the internal body activities and the external temperature of the water in which it lives ...
Experimental data on the acute toxicity of the Orasol Black X51 (ES 939-191-9) to aquatic invertebrates are available from a static limit test on Daphnia magna conducted according to OECD 202. No mortality was observed at a test concentration of 100 mg/L after 48 h (BASF SE, Rep. no.: 17F0074/16E023, 2017). Therefore, the 48h- EC50 is higher than 100 mg/L. It can be concluded, that Orasol Black X51 is with high probability acutely not harmful to aquatic invertebrates. ...
IT is a question worthy of the scientists of CSI Miami -- which has the more complex gene structure a human being or the humble flea?
Confocal microscopic image captured through the Keith Porter Image Facility, UMBC, a collaborative project between Stephen Bradley & Dr. Tagide deCarvalho, UMBC. The process is called autofluorescence a natural emission of light by biological structures such as mitochondria and lysosomes when they have absorbed light, and is used to distinguish the light originating from artificially added fluorescent markers (fluorophores). The bug was sampled from Masonville Cove Environmental Education Center, next to Brooklyn & Curtis Bay, Maryland, August 2017. The overall project is called Waters Edge, Biome Tells, funded by a UMBC summer research fund.. ...
PubMed Central Canada (PMC Canada) provides free access to a stable and permanent online digital archive of full-text, peer-reviewed health and life sciences research publications. It builds on PubMed Central (PMC), the U.S. National Institutes of Health (NIH) free digital archive of biomedical and life sciences journal literature and is a member of the broader PMC International (PMCI) network of e-repositories.
Article Study of environmental risks incurred by leakage of lithium cells to the food chain in a freshwater ecosystem. Water flea (Daphnia magna) and fish (Carassius auratus) at trophic level were used for comprehensive evaluation of environmental ri...
The water flea, Daphnia magna, is the canary of environmental toxicology. Scientists have found the flea to be sensitive to a wide array of toxic conditions. Unlike a mine, a river can contain multiple toxins, and a wide range of reasons why a
Toxicity to fish: A study on the acute toxicity of the substance to Danio rerio was conducted in accordance with the UBA test protocol: Letale Wirkung beim Zebrabaerbling Brachydanio rerio, (LC 0, LC 50, LC100; 48 - 96h) Stand Mai 1984. The test was performed under static conditions and mortality and abnormal behaviour were assessed after 24, 48, 72 and 96h. Groups of ten fish were exposed to test concentration of 0.5 to 50 mg/L (nominal concentration) of the substance. The LC50 (96h) was calculated to be 2.62 mg/L. Toxicity to invertebrates: A study on the acute toxicity of the substance to Daphnia magna was conducted in accordance with the OECD 202. The test was performed under semi-static conditions and mortality was assessed after 24 and 48h. The EC50 (48h) was calculated to be 0.16 mg/L. The long-term toxicity of the substance to Daphnia magna was assessed in a 21-day semi-static test according to the OECD Guideline 202 (Daphnia sp., Acute Immobilisation and Reproduction Test; adopted: ...
When road deicing salt enters freshwater ecosystems, prey species such as Daphnia pulex can rapidly evolve tolerance to the contaminant, buffering their local food webs from the impacts of salination.. 1 Comment. ...
When road deicing salt enters freshwater ecosystems, prey species such as Daphnia pulex can rapidly evolve tolerance to the contaminant, buffering their local food webs from the impacts of salination.. 1 Comment. ...
72h EL50 (growth rate) 0.18 mg/L, 72h NOELR (growth rate) 0.11 mg/L (Pseudokirchnerella subcapitata); OECD 201, 2011; Vryenhoef H., 2018. 48h EL50 0.41 mg/L (CL: 0.35 - 0.48 mg/L); Daphnia magna; OECD 202, 2004; Vryenhoef, H., 2018. Based on the current aquatic data set presented above, the Log Kow of 0.3 - 6.5, the BCF (, 500 L/kg wwt.) and the ready biodegradability result (ready biodegradable), under Regulation (EC) 1272/2008, the test item would be classified as follows: Aquatic Acute Cat. 1 Aquatic Chronic Cat. 3 Data used for CLP conclusion: Acute toxicity data: Daphnid 48h EL50: 0.41 mg/L (OECD202: Vryenhoef, H., 2018) Algae 72h EL50 (growth rate): 0.18 mg/L (OECD 201: Vryenhoef, H., 2018) Chronic toxicity data: Algae 72h EL10 (growth rate): 0.11 mg/L (Vryenhoef, H., 2018) Environmental fate: Ready biodegradable: Yes (OECD 301B: Best, N., 2018) ...
The spiny water flea, a small but aggressive aquatic invasive species, has made its way into another of Wisconsins lakes, University of Wisconsin-Madison researchers reported last week.
Our progress in understanding human genes has been amazing and humbling. About 150 years ago, Gregor Mendel used pea plants to establish some rules of inheritance, and about 50 years ago, Watson and Crick described the double helix of DNA. In 2003, the entire human genome was sequenced. Amazing!. What was humbling was that, when the number of genes in human cells were counted and compared to other organisms, our genome was considerably smaller than that of many other species. For example, humans have about 25,000 genes in each cell, while the tiny water flea has over 30,000! Scientists had assumed that due to our advanced abilities and organ structure, wed have over 100,000 genes.. While we dont have that many genes, scientists have very recently discovered ways to control the modest number we have, in an exciting new field called epigenetics. It explains how changes in gene activity can occur without changing our actual DNA.. One way that we can influence genes without changing their basic ...
Photo 1. Insanitary water supply being infected. Note the open infective lesions on this girls foot. Guinea worm occurs in parts of Africa, India, the Middle East and Brazil where water is drawn from shallow pools or primitive wells. Larvae are swallowed inside water fleas when unboiled water is drunk. The larvae emerge in the intestine from where they migrate to, and mature in the subcutaneous tissues.. ...
Bref brillante fresh vitality pavimenti - Detergent pentru curatat pavimente parfum fresh vitality Bref Proprietati: Este un produs ideal destinat curatarii tuturor suprafetelor lavabile din casa. Utilizat pentru marmura si ceramica. Este o formula noua cu efect reparator. Ofera stralucire si un parfum proaspat fresh care se pastreaza pana la 24 ore. Utilizari: Se foloseste diluat - 2 capace in jumatate galeata de apa. Pentru pete turnati nediluat si apoi stergeti cu o laveta. Atentionari: A nu se lasa la indemana copiilor. 1250 ml
Elements bioassay laboratory is proud to offer an assortment of GLP compliant testing services to assist you in your research or product registering endeavors. Our aquatic toxicity testing services will cover most disciplines, including salt and fresh water applications.. ...
Article A Test of the Additivity of Acute Toxicity of Binary‐Metal Mixtures of Ni with Cd, Cu, and Zn to Daphnia Magna, Using the Inflection Point of the ...
Kottelat, M., A.J. Whitten, S.N. Kartikasari and S. Wirjoatmodjo, 1993. Freshwater fishes of Western Indonesia and Sulawesi. Periplus Editions, Hong Kong. 221 p. (Ref. 7050 ...
We analysed the antioxidant response of Daphnia commutata in the oligotrophicNorth-patagonian lake (Lake Mascardi) that receives inputs of glacial clay inone extreme, which creates a plume with a consequent gradient in underwaterlight intensity (including ultraviolet radiation) and suspended solid material.This gradient in light intensity also affects the light:nutrient ratio andhence the C:P ratio of the food for planktonic herbivores. In the field, alonga 9 km transparency gradient, we measured the activities of glutathioneS-transferase (GST) and catalase (CAT) enzymes involved in protection againstUVR. Through laboratory experiments, we tested the possible role of suspendedsediment particles as an additional stressor for a filter feeding zooplankter.Our results indicate that the inputs of glacial clay into the lake haveantagonistic effects on Daphnia.Glacial clay was a stress mitigating factor to UVR (decrease in the antioxidantresponse of GST activity), but was also a source of stress that ...
Collagen-like proteins containing glycine-X-Y repeats have been identified in several pathogenic bacteria potentially involved in virulence. Recently, a collagen-like surface protein, Pcl1a, was identified in Pasteuria ramosa, a spore-forming parasite of Daphnia. Here we characterise 37 novel putative P. ramosa collagen-like protein genes (PCLs). PCR amplification and sequencing across 10 P. ramosa strains showed they were polymorphic, distinguishing genotypes matching known differences in Daphnia/P. ramosa interaction specificity. Thirty PCLs could be divided into four groups based on sequence similarity, conserved N- and C-terminal regions and G-X-Y repeat structure. Group 1, Group 2 and Group 3 PCLs formed triplets within the genome, with one member from each group represented in each triplet. Maximum-likelihood trees suggested that these groups arose through multiple instances of triplet duplication. For Group 1, 2, 3 and 4 PCLs, X was typically proline and Y typically threonine, consistent ...
Cerium (Ce, CeCl) and Erbium (Er, ErCl) are increasingly used in many electronic devices facilitating the alteration of their biogeochemical cycles (e.g. e-waste). Previous surveys stated that their environmental concentrations due to natural or anthropogenic events can reach up to 161 μg/L in ore mine effluent for Ce with a mean water concentration of 0.79 μg/L, and 11.9 μg/L
Craig, Douglas Charles (1995) An ecotoxicological test utilizing heart rate in Daphnia magna and D. pulex, with comparisons to traditional testing methods. Masters thesis, Concordia University. ...
Despite the central significance of microsatellite mutations to issues of genomic instability, forensic testing, and population genetic analyses, the rate of origin and spectrum of effects of such mutations are still poorly understood, with many estimates being derived from reporter constructs in yeast cultures (e.g., Henderson and Petes 1992; Strand et al. 1995; Wierdl et al. 1996; Sia et al. 1997). Our long-term series of mutation-accumulation lines of C. elegans and D. pulex provide a useful platform for a more direct evaluation of the properties of microsatellite mutations in two key model organisms.. As in previous studies (Wierdl et al. 1997; Brinkmann et al. 1998; Kayser et al. 2000; Beck et al. 2003; Whittaker et al. 2003; Legendre et al. 2007), we find a strong correlation between allele size (repeat number) and mutation rate in C. elegans (Figure 1). In addition, although the variation of repeat numbers among loci sampled in D. pulex does not permit a formal evaluation of length ...
This study examined the interactions between Daphnia magna and a water-soluble, lysophophatidylcholine coated single-walled carbon nanotube. D. magna were able to ingest the nanotubes through normal feeding behavior and utilize the lysophophatidylcho
The authors show that over 50% of the NPs remain in the Daphnia after exposure to clean water . Even after feeding on clean algae for 48 hours, about 30% of the NPs remain in the Daphnia. Additionally, the authors looked at the effect of the NP surface coating on the residence time of NPs in Daphnia. They looked at four surface coatings: octylamine modified polyacrylic acid, polyethylene glycol(PEG) modified polyacrylic acid (PAA), poly(maleic anhydride-alt-1-octadecene) (PMAO), and PEG modified poly(maleic anhydride-alt-1-octadecene). In both cases the PEG conjugated polymers were less accumlative than the parent polymer. The most accumulative by a factor of seven over the PEG modified PAA, was the PMAO. Although all of the NPs accumulate in the Daphnia gut, we see that surface coating does play a large role.. Alright, so we have some Daphnia that look cool under a black light, they are still swimming, right?. This is where the second study comes into play. This study looks at CdSe ...
3. Evolution of Multi-Host Parasites and Effects on Invasive Species We have recently begun studying multihost parasites; most parasites can infect multiple host species. While this can be challenging to study in many cases, Daphnia are well-suited to studies addressing how parasites deal with trying to infect multiple host species. Our work on multihost parasites has, to date, focused on the bacterial pathogen Pasteuria ramosa. This parasite can infect multiple host species (e.g., Duffy et al. 2010). In Georgia, Pasteuria appears to have shifted to infect a novel host, the invasive Daphnia lumholtzi. We will study how parasites evolve after shifting to a novel host and how parasitism influences the population dynamics of indigenous and non-indigenous hosts. This links with earlier work in which we asked how parasites might influence invasive species (Kestrup et al. 2011). ...
The patterns of immunity conferred by host sex or age represent two sources of host heterogeneity that can potentially shape the evolutionary trajectory of disease. With each host sex or age encountered, a pathogens optimal exploitative strategy may change, leading to considerable variation in expression of pathogen transmission and virulence. To date, these host characteristics have been studied in the context of host fitness alone, overlooking the effects of host sex and age on the fundamental virulence-transmission trade-off faced by pathogens. Here we explicitly address the interaction of these characteristics and find that host sex and age at exposure to a pathogen affect age-specific patterns of mortality and the balance between pathogen transmission and virulence. When infecting age-structured male and female Daphnia magna with different genotypes of Pasteuria ramosa, we found that infection increased mortality rates across all age classes for females, whereas mortality only increased in ...
Sarah Karimi MS16, a doctoral student in the Department of Chemistry and Biochemistry at UT Dallas, recently received the Simon Karecki Award for outstanding contributions to environmental research and for academic excellence.. Karimis research examines the potential toxicity of nanoparticles used by the semiconductor industry to smooth and polish the surface of silicon wafers, which eventually become the transistors found in electronic devices. Karimi said that because the nanoparticles are used in large quantities, there is the potential for them to wind up in waterways.. "My work is on aquatic toxicology, and I use the freshwater flea Daphnia magna as a model organism. This research is a beautiful interface of biology and chemistry," Karimi said. "These organisms are recommended by the EPA for environmental testing of all kinds of pollutants. They are very sensitive, so anything that affects them, may also affect humans.". Karimis advisors are Dr. Rockford Draper, professor of biological ...
Cladocerans dominated the microcrustacean communities in the study area. Fifty-one species were collected in the waterbodies and the greatest number of species belonged to the family Chydoridae. Many species of Chydoridae have great value as water-quality indicators because they are highly sensitive to changes in lake trophic state (de Eyto et al. 2002). Cladocerans and copepods are the two taxonomic groups most studied on the Yucatán Peninsula and in surrounding areas (Elías-Gutiérrez et al. 2008). Mexico has been actively involved in studying the systematics of Cladocera (Elías-Gutiérrez et al. 2006). Therefore, identification of collected cladocerans and copepods to species level was possible. Elías-Gutiérrez (2006) reported a total of 162 cladoceran species for two regions of Mexico (Morelos and southeast Mexico), four being endemic species of Southeast Mexico. Some of the cladoceran species we collected are widely distributed in the Northern Neotropics and South America. These ...
Ness, R. The authors emphasized the possibility of drug- induced akathisia when patients with рf paraple- gia or other physical disabilities develop increasing rest- lessness and an inability to sit or lie still.
As I prepare to get back into the hobby in a big way, I want to include a live food program for my (future) fish. After doing some thorough reading up, Ive decided the best option is a co-culture of daphnia and dero worms. Both species are aquatic and pretty straightforward to culture, based on the research, and both should be tempting for the kinds of fish I want to have. Im thinking Daphnia Pulex should give me the best food yield from my culture, and Im preferring Dero worms to Tubifex
About 30 years ago, a freshwater crayfish kept in an aquarium in Germany reproduced without a mate - perplexing both its owner and scientists. Since then, clones of the animal have been invading wild ecosystems throughout Europe and Africa.. The genome of the marbled crayfish (Procambarus virginalis) has now been sequenced by a team from the German Cancer Researcher Center to uncover the animals unique evolution and adaptation skills. The findings may also offer insight into the cloning process of cancerous tumors, the researchers say.. Freshwater crayfish belong to the order of decapod crustaceans, which also includes crabs, lobsters, prawns and shrimps. However, the only crustacean genomes available are for the water flea and sand flea, and there are no genome sequences for decapods, so there is still a lot to be learned about the various species of crustaceans.. The marbled crayfish (called Marmorkrebs in Germany) is believed to have originated when two slough crayfish, imported to Germany ...
The INNOQUA project aims to demonstrate that nature based-processes can treat wastewater - including the use of earthworms and water fleas.
Most of the fragmentary information available on the species is derived from the work of Notarbartolo-di-Sciara (1987, 1988) in the southern Gulf of California, México, though this species has been recently observed during artisanal fishing camp surveys throughout the Gulf of California (R. Hueter et al. unpublished data, Bizzarro 2001). Migrations are likely driven by temporal changes in water temperature with local movements presumed to be associated with the distribution and abundance of planktonic crustaceans, especially mysid shrimp (Mysidium spp.). Mysids are believed to be the dominant prey item of this species, at least during winter months. However, these conclusions are drawn from a very limited sample size (n=3) and through inference with a closely related, similar-sized mobulid from Africa (M. rochebrunei) and as such should be considered speculative (Notarbartolo-di-Sciara 1988, J. Bizzarro pers. obs). Gastropod shells and coral fragments have been found in stomach contents ...
Solitary. Occurs in waters with a temperature range of 4.5-0.4°C (Ref. 3590). Uses its specialized fin rays (tripod) to elevate body into water column. Specialized sensory pectoral fins are spread facing anteriorly, probably to detect prey. Feeds on planktonic crustaceans. Synchronously hermaphroditic (Ref. 6688). ...
Short-term toxicity to fish In a static limit test system a 96h-LC0 of ≥ 100 mg/L was determined on Danio rerio related to nominal concentration. Analytical monitoring was carried out and the nominal concentrations were confirmed. As a consequence it can be concluded the 96h-LC50 is , 100 mg/L. The test was conducted according to the Council Regulation (EC) No 440/2008, Method C.1 Acute toxicity for Fish (2008) which is in most parts equivalent to the OECD Guideline for Testing of Chemicals No. 203 Fish, Acute Toxicity Test (1992). Short-term toxicity to Daphnia Daphnia magna was investigated in a static limit test in accordance with the Council Regulation (EC) No 440/2008, Method C.2 Acute toxicity for Daphnia which is equivalent to OECD Guideline for Testing of Chemicals No. 202. Acute Immobilisation Test (adopted April 13, 2004). No toxic effect was observed and a 48h-EC50 of ,100 mg/L was received. The LC50-value relates to nominal concentration as effective concentrations ...
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Branchiopod crustaceans are represented by fairy, tadpole, and clam shrimps (Anostraca, Notostraca, Laevicaudata, Spinicaudata), which typically inhabit temporary freshwater bodies, and water fleas (Cladoceromorpha), which live in all kinds of freshwater and occasionally marine environments [1, 2]. The earliest branchiopods occur in the Cambrian, where they are represented by complete body fossils from Sweden such as Rehbachiella kinnekullensis [3] and isolated mandibles preserved as small carbonaceous fossils [4-6] from Canada. The earliest known continental branchiopods are associated with hot spring environments [7] represented by the Early Devonian Rhynie Chert of Scotland (410 million years ago) and include possible stem-group or crown-group Anostraca, Notostraca, and clam shrimps or Cladoceromorpha [8-10], which differmorphologically fromtheirmodern counterparts [1, 2, 11]. Here we report the discovery of an ephemeral pool branchiopod community from the 365-million-year-old Strud locality ...
Regulatory linkage between epibiotic organisms and their host zooplankton populations is one of the least understood topics in zooplankton biology, despite the likely importance of epibionts to pelagic communities. These laboratory studies with Colacium vesiculosum , a common algal epibiont, and Daphnia pulex , one of its most common zooplankton hosts, greatly increase current understanding of zooplankton-epibiont interactions. In Chapter 1 C. vesiculosum is shown to have a resource-mediated effect on D. pulex. When D. pulex was food-limited, its fecundity and growth were increased by epibiosis because it consumed C. vesiculosum in the unattached, dispersal phase. With food in excess, D. pulex fecundity and growth were reduced by epibiosis. Chapter 2 describes the C. vesiculosum experimental system. The epibiont was cultured on D. pulex. It was obtained for experiments by killing the host, which induced C. vesiculosum dispersal. C. vesiculosum cultured on D. pulex attached to D. pulex far more ...
Regulatory linkage between epibiotic organisms and their host zooplankton populations is one of the least understood topics in zooplankton biology, despite the likely importance of epibionts to pelagic communities. These laboratory studies with Colacium vesiculosum , a common algal epibiont, and Daphnia pulex , one of its most common zooplankton hosts, greatly increase current understanding of zooplankton-epibiont interactions. In Chapter 1 C. vesiculosum is shown to have a resource-mediated effect on D. pulex. When D. pulex was food-limited, its fecundity and growth were increased by epibiosis because it consumed C. vesiculosum in the unattached, dispersal phase. With food in excess, D. pulex fecundity and growth were reduced by epibiosis. Chapter 2 describes the C. vesiculosum experimental system. The epibiont was cultured on D. pulex. It was obtained for experiments by killing the host, which induced C. vesiculosum dispersal. C. vesiculosum cultured on D. pulex attached to D. pulex far more ...
Environmental factors have a varied impact on the development of juvenile and adult Cladocera, depending on their different physiological conditions and body size. The values of these factors alter spatially and temporarily, thus implying that they play a role in the spatial distribution of the pre-reproductive and potentially reproductive stages of cladocerans. The aim of the study was to determine seasonal and spatial variations in the distribution of juvenile and adult individuals of limnetic Cladocera in relation to selected physicochemical factors (temperature, conductivity, pH, concentration of dissolved oxygen, total organic carbon, total suspended solids) and fish predation pressure (measured by Chessons coefficient λ) in deep Lake Piaseczno (eastern Poland). Adult Cladocera displayed spatial distribution related to fish predation pressure. The species selectively eaten, B. coregoni and D. longispina, and non-selectively eaten, D. cucullata, selected the pelagic zone to exist, whereas ...
導讀:本文分為兩部份,第一部份為台灣的貝類1,459種;以及第二部份的33種新種及新亞種的描述。每一種有簡單的採集地紀錄,部份有同種異名或是化石的紀錄。本文所紀錄的台灣貝類,如下,薄石鱉科-Ischnochiton comptus (Gould)、Lepidozona coreanica (Reeve)。石鱉科-Rhyssoplax komaiana (Is. et Iw. Taki)、Liolophura loochooana (Broderip et Sowerby)、Acanthopleura spinosa (Bruguiere)、Onithochiton (Onithoplax) hirasei Pilsbry。鮑螺科-Haliotis asinina Linnaeus、Haliotis (Euhaliotis) discus Reeve、Haliotis (Sanhaliotis) japonica Reeve(=diversicolor auct.=supertexia Lischke=gruneri Philippi=aquatilis Reeve)、Haliotis (Sanhaliotis) varia Linnaeus(=planata Sowerbry)。透孔螺科-Emarginula fuliginea A. Adams、Rimula sp.、Scutus scapha Gmelin、Diodora cf. mus Reeve、Diodora ticaonica Reeve (=elaborata Sowerby)、Diodora galeata (Helbling)。笠螺科-Patella (Penepatella) stellaeformis ...
Cladocera is an order of small crustaceans commonly called water fleas. Around 620 species have been recognised so far, with many more undescribed.[1]. They are everywhere in inland aquatic habitats, but rare in the oceans.[2] Most are 0.2-6.0 mm (0.01-0.24 in) long, with a down-turned head, and a carapace covering the thorax and abdomen.[3] There is a single median compound eye.[2] They swim with jerking flea-like movements.. Most species show cyclical parthenogenesis, where asexual reproduction is occasionally supplemented by sexual reproduction. The sexual reproduction produces resting eggs that allow the species to survive harsh conditions and disperse to distant habitats.[4]. ...
Low levels of glyphosate-based herbicide have also been reported to cause adverse effects on reproduction (fecundity) and clutch size of aquatic invertebrates. In a study, Cuhra et al. reported that Daphnia magna exposed to 0.45 mg/L Roundup® significantly decreased fecundity compared to the control group [44]. They also reported that animals exposed to 1.35 mg/L Roundup® reached reproductive age, but almost all eggs and developing embryos were aborted and did not hatch, whereas animals exposed to 4.05 mg/L Roundup® died before reaching maturation. However, fecundity in Daphnia magna exposed to Roundup® concentrations of 0.05 and 0.15 mg/L was not significantly affected. The abortion rates for animals exposed to Roundup® concentrations of 0.05, 0.15 and 0.45 mg/L were not significantly different from those of the control group. On the other hand, the abortion rates for animals exposed to 1.35 mg/L of Roundup® were significantly higher than control group, reaching nearly 100 %. Cuhra et al. ...
Define Cladocerans. Cladocerans synonyms, Cladocerans pronunciation, Cladocerans translation, English dictionary definition of Cladocerans. n. pl. 1. An order of the Entomostraca
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 µgU.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 µgU.L-1 in F1 and 39-41 µgU.L-1 in F2. Simulations emphasized the importance of considering the ...
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The disadvantages of current biodegradation tests are examined. These problems include need for high substrate concentrations, lack of parent compound concentration measurements and estimation of sediment effects, failure to indicate compounds to which microbial populations must adapt to degrade, and lack of site specificity in innocula selection. A modified river die-away test is proposed for determining biodegradability of organic compounds and testing for toxic degradation products. The chemical abatement test uses shake flasks containing sterile and nonsterile site water, both with and without site sediment. Concurrent toxicity testing with mysids or daphnids provides a sensitive assay for the detection of toxic metabolities ...
Background/Question/Methods. Humans have artificially enhanced the productivity of terrestrial and aquatic ecosystems on a global scale by increasing nutrient loading. While the consequences of eutrophication are well-known, most studies tend to examine short-term responses relative to the time scales of heritable adaptive change. Thus, the potential role of adaptation by organisms in stabilizing the response of ecological systems to such perturbations is largely unknown. We tested the hypothesis that adaptation by a generalist consumer (Daphnia pulicaria) to toxic prey (cyanobacteria) mediates the response of lake ecosystems to nutrient enrichment. Using a manipulative field experiment in limnocorrals, we examined the interactive effects of nutrient enrichment and consumer genotype (sensitive vs. tolerant to toxic prey) on algal abundance and species composition. We then tested theoretical predictions of how the magnitude of consumer effects should vary with productivity by conducting ...
The distribution of sexual reproduction of the geographic parthenogen Eucypris virens (Crustacea: Ostracoda) matches environmental gradients in a temporary ...
In nature, some plants and single-celled organisms produce genetically identical offspring through a process called asexual reproduction. In asexual reproduction, a new individual is generated from a copy of a single cell from the parent organism. For example, water hyacinth produces multiple copies of genetically-identical plants through a process known as apomixis, or asexual seed formation.. Archaea, bacteria, and protists reproduce asexually by binary fission, where a cell divides giving rise to two cells, each having the potential to grow to the size of the original cell. Finally, some plants, invertebrates (such as water fleas, aphids, stick insects, some ants, bees and parasitic wasps), and vertebrates (such as some reptiles, amphibians, fish, and few birds) reproduce using parthenogenesis, a form of asexual reproduction where an unfertilized egg develops into a new individual in the absence of the male gamete.. Natural clones, also known as identical twins, occur in humans and other ...
In nature, some plants and single-celled organisms produce genetically identical offspring through a process called asexual reproduction. In asexual reproduction, a new individual is generated from a copy of a single cell from the parent organism. For example, water hyacinth produces multiple copies of genetically-identical plants through a process known as apomixis, or asexual seed formation.. Archaea, bacteria, and protists reproduce asexually by binary fission, where a cell divides giving rise to two cells, each having the potential to grow to the size of the original cell. Finally, some plants, invertebrates (such as water fleas, aphids, stick insects, some ants, bees and parasitic wasps), and vertebrates (such as some reptiles, amphibians, fish, and few birds) reproduce using parthenogenesis, a form of asexual reproduction where an unfertilized egg develops into a new individual in the absence of the male gamete.. Natural clones, also known as identical twins, occur in humans and other ...
KS2. Look at photos or images of the animals mentioned or visit a marine aquarium. Find out how the starfish, jellyfish, sessile polyps and sea urchins gather or capture and eat their food. Discuss the features that make these animals suited to a life among coral. For a good selection of drawings, photos and text see www.EnchantedLearning.com. KS4. Sample fresh-water ponds and look for living specimens of coral relatives like Hydra and Obelia, or get specimens from a biological supplier. Compare their appearance with that of polyps found in coral. Observe the living specimens with a binocular microscope and look for the bumps that mark the position of the stinging cells (nematocysts) on the tentacles. Add a couple of water fleas or a drop of Marmite to the water and watch how the Hydra or Obelia react.. KS5. Compare the symbiotic relationship of zooxanthellae with other examples of mutualism. See www.york.ac.ukdeptsbiolunitssymbiosis. Research the integration mechanisms (nerve nets) of the Hydra ...
Banker, Howard James (1931) Distribution of school success in families. The Journal of Heredity, 22 (12). pp. 373-379. Banker, Howard James (1931) Mental age distribution in school progress. Journal of Educational Research, 23 (4). pp. 273-279. Banta, Arthur Mangun (1931) Completion and preparation for publication of studies with Cladocera. In: Carnegie Institution of Washington Year Book No. 30, 1930-31. Carnegie Institution of Washington, Washington, D. C., pp. 423-425. Banta, Arthur Mangun, Brown, Leland A. (1931) Attempts to analyze the effects of crowding upon male production in the Cladoceran, Moina macrocopa. The Anatomical Record, 51 (1, sup). Banta, Arthur Mangun, Brown, Leland A. (1931) Factors involved in male production by crowded Moina macrocopa mothers. Proceedings of the Society for Experimental Biology and Medicine, 28 (8). pp. 820-822. Banta, Arthur Mangun, Wood, Thelma Rittenhouse (1931) Dwarf and slow developing clones of Daphina longispina. The Anatomical Record, 51 (1, sup). ...
Aquatic toxicity tests were originally designed for individual compounds that are soluble and stable in water. For sparingly soluble substances that are not toxic at the solubility limit, the issue is whether tests should be performed with insoluble test substance present. Based on a literature evaluation of the physiology of uptake, it was concluded that only the dissolved fraction is available for uptake and that the insoluble test substance may introduce artifacts that aggravate data interpretation. Therefore, toxicity tests should be conducted only up to the solubility limit. Testing of volatile, unstable, or adsorptive substances is complicated by the ability to keep exposure concentrations relatively constant. For these, appropriate test protocols including adequate design of the dosing systems must be employed. For test medium preparation, physical methods and, where necessary, use of low concentrations of certain solvents are recommended to support handling and speed of dissolution. ...
Phylogenetic analyses were performed using multiple nuclear (ITS and ETS) and chloroplast regions (ndhF-trnL, psbA-trnH, psbD-trnT, and trnT-trnL) to test the monophyly of Aconitum subgen. Lycoctonum (Ranunculaceae) and reconstruct the phylogenetic relationships within the subgenus. The subgenus as currently circumscribed is revealed to be polyphyletic. To achieve its monophyly, sect. Galeata and sect. Fletcherum, both being unispecific and each having a unique array of characters (the latter even having the aberrant base chromosome number of x= 6), must be removed from the subgenus. The subgenus Lycoctonum should thus be redefined to include only two sections, the unispecific sect. Alatospermum and the relatively species -rich sect. Lycoctonum. The section Alatospermum, which is both morphologically and karyologically in the primitive condition, is resolved as the first diverging lineage of the subgenus Lycoctonum Glade. The monophyly of sect. Lycoctonum is strongly supported, but all the ten ...
...SAN FRANCISCO August 7 2012 -- The American paddlefish -- known for ... We found that paddlefish have had their own genome duplication said...In order to study how human limbs develop scientists compare the limb...In the last decade paddlefish have become a useful benchmark in evolu...,Paddlefishs,doubled,genome,may,question,theories,on,limb,evolution,biological,biology news articles,biology news today,latest biology news,current biology news,biology newsletters
Rock pool with three red beadlet anenomes (Actinia equine, at centre) top shells (Monodonta turbinate, surrounding anemones at centre) and limpets against (Patella intermedia, flat shells at left and right of anemones) against white alga (Lithophyllum incrustans). - Stock Image Z145/0324
Even though we live in the greatest country in the world, we arent the greatest in food quality and safety for the foods that we all eat every single day.
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Lepidocaris rhyniensis: The Lipostraca contains only Lepidocaris rhyniensis, from the Rhynie cherts of Scotland. This minute branchiopod is preserved so well that fine details of its limbs can be seen. Its structure is better known than that of any other fossil crustacean. It is even possible to deduce its method of…
Cla*doce*ra (?), n. pl. [NL., fr. Gr. a sprout + a horn.] Zoology|Zool. An order of the Entomostraca. ⇒ They have a bival...
Part 3 Dianne Odell of Jackson, Tennessee has lived in an iron lung longer than anyone alive. She tells the story of the day she fell ill with polio and describes what its been like to live ...
This is a hereditary condition wherein your pores and skin loses pigment, main to white patches or white dots on skin This could occur to all and sundry no mat, Hospitals, Clinics Bangalore
Syn: Guinea worm disease. Infection with a nematode worm, Dracunculus medinensis, that has a life cycle in which the larval stage is passed in minute freshwater Crustacea (Copepoda, or water fleas). These infect humans when they drink water containing the water fleas. The disease was formerly common in West Africa, Yemen, and India. It is yielding to efforts to eradicate it but is still endemic in about a dozen countries in Sub-Saharan Africa. ...
To test the quality of the new algorithm, several well-known genes with clusters of mutually exclusive exons with different characteristics were analysed (Figure 3). The first test case is the cytoplasmic dynein heavy chain from Schistosoma mansoni (Sm DHC1). Dynein heavy chains belong to the longest genes in eukaryotes encoding 4000 - 5000 residues and are spread over several dozens of exons. The mutually exclusive exon is clearly identified in the middle of the gene, encoding split codons at the 3- and 5-end of the exon. The query exon and the candidate exon have identical lengths and show strong homology. Based on the multiple sequence alignment of more than 2000 DHCs these exons are mutually exclusive and not constitutive or differentially included. The second case represents the muscle myosin heavy chain gene from the waterflea Daphnia magna[19]. The arthropod muscle myosin heavy chain genes contain several clusters of mutually exclusive exons to fine tune the mechanochemical ...
Pavement sealant is a black liquid sprayed or painted on the asphalt pavement of parking lots, driveways and playgrounds to improve appearance and protect the underlying asphalt. Pavement sealants that contain coal tar have extremely high levels of polycyclic aromatic hydrocarbons (PAHs). Coal tar is a known human carcinogen; several PAHs are probable human carcinogens and some are toxic to fish and other aquatic life.. Rainwater runoff collected as long as three months after coal-tar-sealcoat application caused 100% mortality to minnows and water fleas, which are part of the base of the food chain, when the test organisms were exposed to ultra-violet radiation to simulate sunlight. The full study, reported in the scientific journal Environmental Science and Technology, is available online.. Exposure of fish cells to coal-tar sealant runoff damaged their DNA and impaired the ability of the cells to repair DNA damage. "The simultaneous occurrence of DNA damage and impairment of DNA repair has ...
Media interested in covering the meeting or interviewing experts are asked to contact Emily Staub. Copy of the meeting schedule is available upon request.. GUINEA WORM DISEASE. With less than a fraction of 1 percent of the disease remaining, Guinea worm is poised to be the next disease eradicated in human history. The disease is contracted when people consume stagnant water, contaminated with microscopic water fleas carrying infective larvae. Inside a humans abdomen, the larvae mature and grow, with some reaching 3 feet in length. After a year, the worm slowly emerges through a painful blister in the skin, usually on the lower limbs. In highly endemic areas, infected people usually have mor than one Guinea worm, in some cases dozens, emerging at once.. ...