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pulsed light reduces the toxicity of the algal toxin okadaic acid to freshwater crustacean daphnia pulex.this constitutes the first study to report on the reduction in toxicity of the dinoflagellate algal toxin okadaic acid after novel pulsed light (pl) treatments where ecotoxicological assessment was performed using a miniaturised format of the conventional in vivo freshwater crustacean daphnia sp. acute toxicity test. bivalves accumulate this toxin, which can then enter the human food chain causing deleterious health effects such as diarrhetic shellfish poisoning. this miniaturised toxicological ...201829052147
conservation of the notch antagonist hairless in arthropods: functional analysis of the crustacean daphnia pulex hairless gene.the notch signaling pathway is highly conserved in all animal metazoa: upon notch receptor activation, transcription of notch target genes is turned on by an activator complex that centers on the transcription factor csl. in the absence of signal, csl assembles transcriptional repression complexes that display remarkable evolutionary diversity. the major antagonist of notch signaling in insects named hairless was originally identified in drosophila melanogaster. it binds to the drosophila csl ho ...201728861687
interaction of the red pigment-concentrating hormone of the crustacean daphnia pulex, with its cognate receptor, dappu-rpchr: a nuclear magnetic resonance and modeling study.the primary sequence of the red pigment-concentrating hormone (rpch) receptor of the water flea, daphnia pulex, was used in homology modeling to construct the first 3d model of a crustacean g-protein coupled receptor, dappu-rpchr. this receptor was found to belong to the class a subfamily of gpcrs with a disulfide bridge between cys72 and cys150 and an ionic lock between arg97 and thr224 and thr220. nmr restrained molecular dynamics was used to determine the structure of an agonist, dappu-rpch, ...201828837848
evolution of a predator-induced, nonlinear reaction norm.inducible, anti-predator traits are a classic example of phenotypic plasticity. their evolutionary dynamics depend on their genetic basis, the historical pattern of predation risk that populations have experienced and current selection gradients. when populations experience predators with contrasting hunting strategies and size preferences, theory suggests contrasting micro-evolutionary responses to selection. daphnia pulex is an ideal species to explore the micro-evolutionary response of anti-p ...201728835554
the genetics of phenotypic plasticity. viii. the cost of plasticity in daphnia pulex.in a heterogeneous world, the optimal strategy for an individual is to continually change its phenotype to match the optimal type. however, in the real world, organisms do not behave in this fashion. one potential reason why is that phenotypic plasticity is costly. we measured production and maintenance costs of plasticity in the freshwater crustacean daphnia pulex (cladocera: crustacea) in response to the presence of chemical signals from a predator, the insect chaoborus americanus. we looked a ...199828568340
the evolutionary ecology of an antipredator reaction norm: daphnia pulex and chaoborus americanus.ponds containing the parthenogenetic zooplankter daphnia pulex with and without chaoborid predators were sampled over the course of a season. a significant (p < 0.05) spearman rank correlation was found between predator density and the expression of an antipredator defense (neckteeth) by the daphnia. the reaction norms (percent induction of a single genotype versus predator density) of clones isolated from predator-free and predator-rich habitats were determined in a laboratory setting. there wa ...199128564128
chaoborus predation and life-history evolution in daphnia pulex: temporal pattern of population diversity, fitness, and mean life history.the effect of predation by the aquatic dipteran larva chaoborus americanus on genetic diversity and life-history evolution in the cladoceran daphnia pulex was investigated in large replicate laboratory populations. instantaneous daily loss rates of clonal diversity and genetic variance for fitness indicate that 93-99% of initial genetic diversity can be removed from populations during the 8-12 generations of clonal reproduction that occur each year in natural populations. in the absence of preda ...199128564082
grazing resistance in nutrient-stressed phytoplankton.grazing experiments were performed with the zooplankters daphnia pulex and daphnia magna, feeding on phosphorus-saturated and phosphorus-limited cells of two green algae (scenedesmus subspicatus and selenastrum capricornutum). p-limited algal cells passed largely intact through the gut and were thus spared from heavy grazing pressure. p-saturated algal cells, in contrast, were efficiently assimilated. structural and morphological changes in the p-limited cells most probably reduced their digesti ...199328313818
seasonal patterns of total and energy reserve lipids of dominant zooplanktonic crustaceans from a hyper-eutrophic lake.seasonal patterns of lipid reserves and lipid classes of dominant zooplankton in a hyper-eutrophic lake were examined in relation to algal food resources. triacylglycerol was the principle lipid energy reserve in all five species examined. during the height of the yearlyaphanizomenon flos-aquae bloom, lipid levels of the principle herbivores (daphnia pulex andleptodiaptomus sicilis) and an omnivore (diacyclops bicuspidatus thomasi), were at their lowest concentration, suggesting that this cyanob ...199228313577
demographic costs of chaoborus-induced phenotypic plasticity in daphnia pulex.it has been proposed that morphological defenses against predation have demographic costs. we measured the cost of a predator-induced morphological defense, using predaceous phantom midge larvae chaoborus americanus (insecta, diptera) and the prey species daphnia pulex (crustacea, cladocera). the induced defense is a neck tooth (and other pleiotropic structures) developed in juvenile d. pulex in the presence of c. americanus. laboratory life table experiments, in the absence of predation, indica ...199028313251
phenotypic plasticity of daphnia pulex in the presence of invertebrate predators: morphological and life history responses.morphological and life history traits of two clones of the cladoceran daphnia pulex were measured in the presence and absence of size-selective insect predators, the midge larva chaoborus flavicans, which preys on small daphnia, and the water bug notonecta glauca, which preys on large daphnia. the aim was to detect predator-induced phenotypic changes, particularly the effect of simultaneous exposure to both types of predators. other work has shown that in the presence of chaoborus americanus, da ...199228312604
chaoborus americanus predation on various zooplankters; functional response and behavioral observations.predation rates for chaoborus americanus on different types of noncyclomorphic zooplankton prey were determined in the laboratory as a function of both prey species and density. the sequence of events leading to consumption of prey was also observed, and probabilities determined for the various components.predation rates generally reached an upper limit as the density of prey increased to high levels. larger prey were always less vulnerable to chaoborus predation. among the species of zooplankto ...198028310942
density-dependent effects of prey defences.in this study, we show that the protective advantage of a defence depends on prey density. for our investigations, we used the predator-prey model system chaoborus-daphnia pulex. the prey, d. pulex, forms neckteeth as an inducible defence against chaoborid predators. this morphological response effectively reduces predator attack efficiency, i.e. number of successful attacks divided by total number of attacks. we found that neckteeth-defended prey suffered a distinctly lower predation rate (prey ...200028308594
morphological defenses induced in situ by the invertebrate predator chaoborus: comparison of responses between daphnia pulex and d. rosea.the presence of plankton predators may induce altered morphology in their potential prey. to date, the mechanism of induction and adaptive value of such defensive responses have been examined in the laboratory. this study investigated the morphological defense structures induced by the invertebrate predator chaoborus in two coexisting daphnia species, d. pulex and d. rosea, in the field. in piscivore lake (gräfenhain, germany), continuous and intense biomanipulation had led to near elimination o ...200028308217
chaoborus crystallinus predation on daphnia pulex: can induced morphological changes balance effects of body size on vulnerability?juvenile daphnia pulex form neckteeth in reponse to chemicals released by predatory chaoborus crystallinus larvae. formation of neckteeth is strongest in the second instar followed by the third instar, whereas only small neckteeth are found in the first and fourth instar of experimental clones. predation experiments showed that body-size-dependent vulnerability of animals without neckteeth to fourth instar c. crystallinus larvae matched the pattern of neckteeth formation over the four juvenile i ...199528306785
interaction between stress induced by competition, predation, and an insecticide on the response of aquatic invertebrates.the present study investigated the effects of species interactions like competition and (intraguild) predation on the sensitivity of aquatic organisms to the insecticide chlorpyrifos. in the first experiment, combined effects of chlorpyrifos and different levels of intraspecific and interspecific interaction were assessed on gammarus pulex survival using asellus aquaticus as an interacting species. intraspecific and interspecific interactions increased the time to extinction of g. pulex up to a ...201728295548
comparative luciferase assay for establishing reliable in vitro screening system of juvenile hormone agonists.the cultured cell-based in vitro assay using the stringency of ligand-receptor interactions is typically useful for screening certain hormone agonists from among a very large number of molecules. however, ligands are frequently altered or modified through evolution; indeed, even in the same receptor orthologs, different ligand sensitivity profiles are considered to arise among species and/or taxa. such ligand transition has been observed in juvenile hormone (jh), one of the most important endocr ...201728261832
how does the cladoceran daphnia pulex affect the fate of escherichia coli in water?the faecal indicator escherichia coli plays a central role in water quality assessment and monitoring. it is therefore essential to understand its fate under various environmental constraints such as predation by bacterivorous zooplankton. whereas most studies have examined how protozooplankton communities (heterotrophic nanoflagellates and ciliates) affect the fate of e. coli in water, the capacity of metazooplankton to control the faecal indicator remains poorly understood. in this study, we i ...201728178322
ancient and recent duplications support functional diversity of daphnia opsins.daphnia pulex has the largest known family of opsins, genes critical for photoreception and vision in animals. this diversity may be functionally redundant, arising from recent processes, or ancient duplications may have been preserved due to distinct functions and independent contributions to fitness. we analyzed opsins in d. pulex and its distant congener daphnia magna. we identified 48 opsins in the d. pulex genome and 32 in d. magna. we inferred the complement of opsins in the last common an ...201728004131
transcriptomic responses in the bloom-forming cyanobacterium microcystis induced during exposure to zooplankton.the bloom-forming, toxic cyanobacterium microcystis synthesizes multiple secondary metabolites and has been shown to deter zooplankton grazing. however, the biochemical and/or molecular basis by which microcystis deters zooplankton remains unclear. this global transcriptomic study explored the response of microcystis to direct and indirect exposures to multiple densities of two cladoceran grazers, daphnia pulex and d. magna higher densities of both daphnids significantly reduced microcystis cell ...201728003198
population genomics of daphnia pulex.using data from 83 isolates from a single population, the population genomics of the microcrustacean daphnia pulex are described and compared to current knowledge for the only other well-studied invertebrate, drosophila melanogaster these two species are quite similar with respect to effective population sizes and mutation rates, although some features of recombination appear to be different, with linkage disequilibrium being elevated at short (< 100 bp) distances in d. melanogaster and at long ...201627932545
genome-wide profiling of 24 hr diel rhythmicity in the water flea, daphnia pulex: network analysis reveals rhythmic gene expression and enhances functional gene annotation.marine and freshwater zooplankton exhibit daily rhythmic patterns of behavior and physiology which may be regulated directly by the light:dark (ld) cycle and/or a molecular circadian clock. one of the best-studied zooplankton taxa, the freshwater crustacean daphnia, has a 24 h diel vertical migration (dvm) behavior whereby the organism travels up and down through the water column daily. dvm plays a critical role in resource tracking and the behavioral avoidance of predators and damaging ultravio ...201627538446
identification of putative circadian clock genes in the american horseshoe crab, limulus polyphemus.while the american horseshoe crab, limulus polyphemus, has robust circadian and circatidal rhythms, virtually nothing is known about the molecular basis of these rhythms in this species or any other chelicerate. in this study, next generation sequencing was used to assemble transcriptomic reads and then putative homologs of known core and accessory circadian genes were identified in these databases. homologous transcripts were discovered for one circadian clock input gene, five core genes, 22 ac ...201627341138
if you see one, have you seen them all?: community-wide effects of insecticide cross-resistance in zooplankton populations near and far from agriculture.the worldwide use of pesticides has led to increases in agricultural yields by reducing crop losses. however, increased pesticide use has resulted in pesticide-resistant pest species and recent studies have discovered pesticide-resistance in non-target species living close to farms. such increased tolerance not only affects the species, but can alter the entire food web. given that some species can evolve not only resistance to a single pesticide, but also cross-resistance to other pesticides th ...201627208756
the persistence and ecological impacts of a cyanobacterium genetically engineered to express mosquitocidal bacillus thuringiensis toxins.the cyanobacterium anabaena pcc 7120#11 has been genetically engineered to act as a delivery vehicle for bacillus thuringiensis subspecies israelensis mosquitocidal toxins. to address ecological concerns about releasing this genetically engineered microorganism into the environment for mosquito larva control, the persistence and ecological impacts of pcc 7120#11 was evaluated using multi-species, standardized aquatic microcosms.201627165108
phenotypic plasticity in three daphnia genotypes in response to predator kairomone: evidence for an involvement of chitin deacetylases.the genetic background of inducible morphological defences in daphnia is still largely unknown. dissolved infochemicals from the aquatic larvae of the phantom midge chaoborus induce so-called 'neck-teeth' in the first three post-embryonic stages of daphnia pulex this defence has become a textbook example of inducible defences. in a target gene approach, by using three daphnia genotypes which show a gradient of neck-teeth induction in response to equal amounts of kairomone, we report a high corre ...201626994174
evolution of neuropeptides in non-pterygote hexapods.neuropeptides are key players in information transfer and act as important regulators of development, growth, metabolism, and reproduction within multi-cellular animal organisms (metazoa). these short protein-like substances show a high degree of structural variability and are recognized as the most diverse group of messenger molecules. we used transcriptome sequences from the 1kite (1k insect transcriptome evolution) project to search for neuropeptide coding sequences in 24 species from the non ...201626923142
wetland defense: naturally occurring pesticide resistance in zooplankton populations protects the stability of aquatic communities.anthropogenic stressors are ubiquitous and have been implicated in worldwide declines of terrestrial and aquatic species. pesticides are one such stressor that can have profound effects on aquatic communities by directly affecting sensitive species and indirectly affecting other species via trophic cascades, which can alter ecosystem function. however, there is growing evidence that non-target species can evolve increased resistance. when such species are important drivers of the food web, then ...201626875187
comparative developmental staging of female and male water fleas daphnia pulex and daphnia magna during embryogenesis.the freshwater crustacean genus daphnia has been used extensively in ecological, developmental and ecotoxicological studies. daphnids produce only female offspring by parthenogenesis under favorable conditions, but in response to various unfavorable conditions and external stimuli, they produce male offspring. although we reported that exogenous exposure to juvenile hormones and their analogs can induce male offspring even under female-producing conditions, we recently established a male inducti ...201626853866
identification of hox genes and rearrangements within the single homeobox (hox) cluster (192.8 kb) of the cyclopoid copepod (paracyclopina nana).we report the first identification of the entire complement of the eight typical homeobox (hox) genes (lab, pb, dfd, scr, antp, ubx, abd-a, and abd-b) and the ftz gene in a 192.8 kb region in the cyclopoid copepod paracyclopina nana. a hox3 gene ortholog was not present in the p. nana hox gene cluster, while the p. nana dfd gene was transcribed in the opposite direction to the daphnia pulex dfd gene, but in the same direction as the dfd genes of the fruit fly drosophila melanogaster and red flou ...201626833546
predators modify the evolutionary response of prey to temperature change.as climate regimes shift in many ecosystems worldwide, evolution may be a critical process allowing persistence in rapidly changing environments. organisms regularly interact with other species, yet whether climate-mediated evolution can occur in the context of species interactions is not well understood. we tested whether a species interaction could modify evolutionary responses to temperature. we demonstrate that predation pressure by dipteran larvae (chaoborus americanus) modified the evoluti ...201526673935
microsatellite evolutionary rate and pattern in schistocerca gregaria inferred from direct observation of germline mutations.unravelling variation among taxonomic orders regarding the rate of evolution in microsatellites is crucial for evolutionary biology and population genetics research. the mean mutation rate of microsatellites tends to be lower in arthropods than in vertebrates, but data are scarce and mostly concern accumulation of mutations in model species. based on parent-offspring segregations and a hierarchical bayesian model, the mean rate of mutation in the orthopteran insect schistocerca gregaria was esti ...201526562076
development of an efficient rna interference method by feeding for the microcrustacean daphnia.rna interference (rnai) is an important molecular tool for analysis of gene function in vivo. daphnia, a freshwater microcrustacean, is an emerging model organism for studying cellular and molecular processes involved in aging, development, and ecotoxicology especially in the context of environmental variation. however, in spite of the availability of a fully sequenced genome of daphnia pulex, meaningful mechanistic studies have been hampered by a lack of molecular techniques to alter gene expre ...201526446824
about the interest of a zooplankton compartment in pond systems: methodology to study the growth kinetic of daphnia pulex on scenedesmus sp.a reliable characterization of cladocerans' growth kinetic on their substrates is crucial for the estimation of their biochemical conversion rate in pond models. although many studies reported cladocerans' growth inhibitions by high chlorophyceae contents, their growth kinetics had continued to be described in many pond system models by monod-type kinetic, which describes growth saturation by high substrate contents, but fails to explain the disappearance of cladocerans observed during chlorophy ...201526442483
the alignment between phenotypic plasticity, the major axis of genetic variation and the response to selection.phenotypic plasticity is the ability of a genotype to produce more than one phenotype in order to match the environment. recent theory proposes that the major axis of genetic variation in a phenotypically plastic population can align with the direction of selection. therefore, theory predicts that plasticity directly aids adaptation by increasing genetic variation in the direction favoured by selection and reflected in plasticity. we evaluated this theory in the freshwater crustacean daphnia pul ...201526423845
comparative paleovirological analysis of crustaceans identifies multiple widespread viral groups.the discovery of many fragments of viral genomes integrated in the genome of their eukaryotic host (endogenous viral elements; eves) has recently opened new avenues to further our understanding of viral evolution and of host-virus interactions. here, we report the results of a comprehensive screen for eves in crustaceans. following up on the recent discovery of eves in the terrestrial isopod, armadillidium vulgare, we scanned the genomes of six crustacean species: a terrestrial isopod (armadilli ...201526388953
data for comparative proteomics of ovaries from five non-model, crustacean amphipods.ovaries were taken from five sexually mature amphipods: gammarus fossarum, gammarus pulex, gammarus roeseli, hyallela azteca and parhyale hawaiensis. the soluble proteome extracted from individual pair of ovaries from five biological replicates was trypsin digested and the resulting peptides were analyzed by high resolution tandem mass spectrometry. the spectra were assigned with four protein sequence databases with different specificities: a rnaseq-derived g. fossarum database; a rnaseq-derived ...201526380837
small rna sequencing based identification of mirnas in daphnia magna.small rna molecules are short, non-coding rnas identified for their crucial role in post-transcriptional regulation. a well-studied example includes mirnas (micrornas) which have been identified in several model organisms including the freshwater flea and planktonic crustacean daphnia. a model for epigenetic-based studies with an available genome database, the identification of mirnas and their potential role in regulating daphnia gene expression has only recently garnered interest. computationa ...201526367422
temporal assessment of copper speciation, bioavailability and toxicity in uk freshwaters using chemical equilibrium and biotic ligand models: implications for compliance with copper environmental quality standards.although significant progress has been made in understanding how environmental factors modify the speciation, bioavailability and toxicity of metals such as copper in aquatic environments, the current methods used to establish water quality standards do not necessarily consider the different geological and geochemical characteristics of a given site and the factors that affect copper fate, bioavailability potential and toxicity. in addition, the temporal variation in the concentration and bioava ...201526318223
the acute toxicity of thallium to freshwater organisms: implications for risk assessment.the acute toxicity of tl(i) to the microalga, pseudokirchneriella subcapitata, the planktonic crustaceans, daphnia magna and daphnia pulex, and early-life stage of the zebrafish, danio rerio, has been studied according to oecd protocols. toxicological end-point concentrations for the microalga ranged from 17 μg l(-1) for a 72 h eyc25 (yield inhibition) to 80 μg l(-1) for a 72 h erc50 (growth inhibition). daphnia were less sensitive to tl, with 48 h ec50s of about 1000 μg l(-1) and 1200 μg l(-1) ...201526225743
elimination of bisphenol a and triclosan using the enzymatic system of autochthonous colombian forest fungi.bisphenol a (bpa) and triclosan (tcs) are known or suspected potential endocrine disrupting chemicals (edcs) which may pose a risk to human health and have an environmental impact. enzyme preparations containing mainly laccases, obtained from ganoderma stipitatum and lentinus swartzii, two autochthonous colombian forest white rot fungi (wrf), previously identified as high enzyme producers, were used to remove bpa and tcs from aqueous solutions. a box-behnken factorial design showed that ph, temp ...201325969787
dynamic evolution and biogenesis of small rnas during sex reversal.understanding origin, evolution and functions of small rna (srna) genes has been a great challenge in the past decade. molecular mechanisms underlying sexual reversal in vertebrates, particularly srnas involved in this process, are largely unknown. by deep-sequencing of small rna transcriptomes in combination with genomic analysis, we identified a large amount of pirnas and mirnas including over 1,000 novel mirnas, which were differentially expressed during gonad reversal from ovary to testis vi ...201525944477
cloning, expression and localization of the daphnia carinata transformer gene dcartra during different reproductive stages.in this study, the full-length cdna of the transformer (tra) gene from the common freshwater species daphnia carinata (dcartra; genbank accession no. kj735445) was cloned using primers based on homologous sequences and rapid amplification of cdna ends (race). the relative expression and localization of dcartra and the cellular abundance of the dcartra protein during different sexual phases were subsequently investigated. the full-length dcartra cdna was 1620 bp with an orf of 1143 bp encoding a ...201525917617
protobug: functional families from the complete proteomes of insects.protobug (http://www.protobug.cs.huji.ac.il) is a database and resource of protein families in arthropod genomes. protobug platform presents the relatedness of complete proteomes from 17 insects as well as a proteome of the crustacean, daphnia pulex. the represented proteomes from insects include louse, bee, beetle, ants, flies and mosquitoes. based on an unsupervised clustering method, protein sequences were clustered into a hierarchical tree, called protobug. protobug covers about 300,000 sequ ...201525911153
the evolutionary history of daphniid α-carbonic anhydrase within animalia.understanding the mechanisms that drive acid-base regulation in organisms is important, especially for organisms in aquatic habitats that experience rapidly fluctuating ph conditions. previous studies have shown that carbonic anhydrases (cas), a family of zinc metalloenzymes, are responsible for acid-base regulation in many organisms. through the use of phylogenetic tools, this present study attempts to elucidate the evolutionary history of the α-ca superfamily, with particular interest in the e ...201525893130
native and non-native plants provide similar refuge to invertebrate prey, but less than artificial plants.non-native species introductions are widespread and can affect ecosystem functioning by altering the structure of food webs. invading plants often modify habitat structure, which may affect the suitability of vegetation as refuge and could thus impact predator-prey dynamics. yet little is known about how the replacement of native by non-native vegetation affects predator-prey dynamics. we hypothesize that plant refuge provisioning depends on (1) the plant's native status, (2) plant structural co ...201525885967
assessing toxicity of copper nanoparticles across five cladoceran species.as a result of ever increasing applications, nanoparticles will eventually end up in the environment. however, currently no common principle has been established to help understand the toxicity of nanoparticles (nps) across species. therefore, it is difficult to estimate the potential risks of nanoparticles to untested species in the environment. the authors exposed 4 different sizes of copper nanoparticles (cunps) and 1 submicron-sized copper particle to 5 cladoceran species (daphnia magna, dap ...201525826796
ionotropic glutamate receptors mediate inducible defense in the water flea daphnia pulex.phenotypic plasticity is the ability held in many organisms to produce different phenotypes with a given genome in response to environmental stimuli, such as temperature, nutrition and various biological interactions. it seems likely that environmental signals induce a variety of mechanistic responses that influence ontogenetic processes. inducible defenses, in which prey animals alter their morphology, behavior and/or other traits to help protect against direct or latent predation threats, are ...201525799112
cardiac contractility structure-activity relationship and ligand-receptor interactions; the discovery of unique and novel molecular switches in myosuppressin signaling.peptidergic signaling regulates cardiac contractility; thus, identifying molecular switches, ligand-receptor contacts, and antagonists aids in exploring the underlying mechanisms to influence health. myosuppressin (ms), a decapeptide, diminishes cardiac contractility and gut motility. myosuppressin binds to g protein-coupled receptor (gpcr) proteins. two drosophila melanogaster myosuppressin receptors (drmms-rs) exist; however, no mechanism underlying ms-r activation is reported. we predicted dr ...201525793503
multigenerational genomic responses to dietary phosphorus and temperature in daphnia.temperature and nutrient availability are both hypothesized to affect organisms at the cellular and genomic levels. in this multigenerational study, daphnia magna (d. magna) and daphnia pulex (d. pulex) were maintained at high (20 °c) and low (10 °c) temperatures and nourished with phosphorus (p)-sufficient (50 μmol/l) and p-deficient (2 μmol/l) algae for up to 35 generations to assess the multigenerational impacts on genome size and nucleus size. analysis by flow cytometry revealed significant ...201425389902
functional genomics of acclimation and adaptation in response to thermal stress in daphnia.gene expression regulation is one of the fundamental mechanisms of phenotypic plasticity and is expected to respond to selection in conditions favoring phenotypic response. the observation that many organisms increase their stress tolerance after acclimation to moderate levels of stress is an example of plasticity which has been long hypothesized to be based on adaptive changes in gene expression. we report genome-wide patterns of gene expression in two heat-tolerant and two heat-sensitive parth ...201425282344
persistence of an amphibian ranavirus in aquatic communities.host-parasite dynamics can be strongly influenced by interactions with other members of the biotic community, particularly when the parasite spends some fraction of its life in the environment unprotected by its host. ranaviruses-often lethal viruses of cold-blooded vertebrate hosts transmitted by direct contact, and via water and fomites-offer an interesting system for understanding these community influences. previous laboratory studies have shown that ranaviruses can persist for anywhere from ...201425266900
annotation of the daphnia magna nuclear receptors: comparison to daphnia pulex.most nuclear receptors (nrs) are ligand-dependent transcription factors crucial in homeostatic physiological responses or environmental responses. we annotated the daphnia magna nrs and compared them to daphnia pulex and other species, primarily through phylogenetic analysis. daphnia species contain 26 nrs spanning all seven gene subfamilies. thirteen of the 26 receptors found in daphnia species phylogenetically segregate into the nr1 subfamily, primarily involved in energy metabolism and resour ...201425239664
living on the edge: populations of two zooplankton species living closer to agricultural fields are more resistant to a common insecticide.ecological communities across the globe are exposed to diverse natural and anthropogenic stressors and disturbances that can lead to community-wide impacts. contaminants are a group of anthropogenic disturbances that are ubiquitous in the environment and can trigger trophic cascades, increased susceptibility to pathogens, reduced biodiversity, and altered ecosystems. in these ecosystems, substantial attention has been given to evolved resistance in targeted pest species, but little attention has ...201425220688
the hr97 (nr1l) group of nuclear receptors: a new group of nuclear receptors discovered in daphnia species.the recently sequenced daphnia pulex genome revealed the nr1l nuclear receptor group consisting of three novel receptors. phylogenetic studies show that this group is related to the nr1i group (car/pxr/vdr) and the nr1j group (hr96), and were subsequently named hr97a/b/g. each of the hr97 paralogs from daphnia magna, a commonly used crustacean in toxicity testing, was cloned, sequenced, and partially characterized. phylogenetic analysis indicates that the hr97 receptors are present in primitive ...201425092536
cutprotfam-pred: detection and classification of putative structural cuticular proteins from sequence alone, based on profile hidden markov models.the arthropod cuticle is a composite, bipartite system, made of chitin filaments embedded in a proteinaceous matrix. the physical properties of cuticle are determined by the structure and the interactions of its two major components, cuticular proteins (cps) and chitin. the proteinaceous matrix consists mainly of structural cuticular proteins. the majority of the structural proteins that have been described to date belong to the cpr family, and they are identified by the conserved r&r region (reb ...201424978609
cloning and expression analysis of a transformer gene in daphnia pulex during different reproduction stages.the full-length cdna of a transformer gene (dptra) was cloned from the cladoceran daphnia pulex using race. dptra expression was assessed by qpcr and whole-mount in situ hybridization in different reproductive stages. the dptra cdna, 1652bp in length, has a 1158-bp open reading frame that encodes a 385 amino acid polypeptide containing one sex determination protein n terminal (sdp_n) superfamily, eight putative phosphorylation sites, and an arginine-serine (rs)-rich domain at the n-terminus. dpt ...201424725535
development and staging of the water flea daphnia magna (straus, 1820; cladocera, daphniidae) based on morphological landmarks.crustaceans of the genus daphnia are one of the oldest model organisms in ecotoxicology, ecology and evolutionary biology. the publication of the daphnia pulex genome has facilitated the development of genetic tools to answer long-standing questions in these research fields (science 331: 555-561, 2011). a particular focus is laid on understanding the genetic basis of the striking ability of daphnids to change their phenotype in response to environmental stressors. furthermore, daphnia have recen ...201424641948
comparative effects of sediment versus aqueous polychlorinated biphenyl (pcb) exposure on benthic and planktonic invertebrates.polychlorinated biphenyls (pcbs) are an environmental concern because of their adverse effects on humans and wildlife, and understanding the contribution of various matrices (i.e., sediment and water) to pcb exposure on aquatic communities is critical for successful remediation of impacted sites. the present study examined the toxicity of different routes of pcb exposure in aquatic invertebrates. in complementary laboratory and field experiments, the authors compared the effects of aqueous versu ...201424464368
molecular docking: a potential tool to aid ecotoxicity testing in environmental risk assessment of pharmaceuticals.a cocktail of human pharmaceuticals pollute aquatic environments and there is considerable scientific uncertainty about the effects that this may have on aquatic organisms. human drug target proteins can be highly conserved in non target species suggesting that similar modes of action (moa) may occur. the aim of this work was to explore whether molecular docking offers a potential tool to predict the effects of pharmaceutical compounds on non target organisms. three highly prescribed drugs, dicl ...201324344392
larger daphnia at lower temperature: a role for cell size and genome configuration?experiments with daphnia magna and daphnia pulex raised at 10 and 20 °c yielded larger adult size at the lower temperature. this must reflect increased cell size, increased cell numbers, or a combination of both. as it is difficult to achieve good estimates on cell size in crustaceans, we, therefore, measured nucleus and genome size using flow cytometry at 10 and 20 °c. dna was stained with propidium iodide, ethidium bromide, and dapi. both nucleus and genome size estimates were elevated at 10 ° ...201324168672
cross-species infection trials reveal cryptic parasite varieties and a putative polymorphism shared among host species.a parasite's host range can have important consequences for ecological and evolutionary processes but can be difficult to infer. successful infection depends on the outcome of multiple steps and only some steps of the infection process may be critical in determining a parasites host range. to test this hypothesis, we investigated the host range of the bacterium pasteuria ramosa, a daphnia parasite, and determined the parasites success in different stages of the infection process. multiple genoty ...201424116675
characterization of microsatellite loci and repeat density in the gooseneck barnacle, pollicipes elegans, using next generation sequencing.pollicipes elegans is a commercially important and biogeographically significant rocky-shore gooseneck barnacle found along the eastern pacific coasts of peru, el salvador, and mexico. little is known about its reproductive biology, and no genetic resources exist despite its growing importance as a fisheries species in the region. next generation sequencing methods can provide rapid and cost-effective development of molecular markers such as microsatellites, which can be applied to studies of pa ...201324115106
transcription patterns of genes encoding four metallothionein homologs in daphnia pulex exposed to copper and cadmium are time- and homolog-dependent.metallothioneins are proteins that play an essential role in metal homeostasis and detoxification in nearly all organisms studied to date. yet discrepancies between outcomes of chronic and acute exposure experiments hamper the understanding of the regulatory mechanisms of their isoforms following metal exposure. here, we investigated transcriptional differences among four identified homologs (mt1-mt4) in daphnia pulex exposed across time to copper and cadmium relative to a control. transcription ...201324113165
decolorization of different textile dyes by penicillium simplicissimum and toxicity evaluation after fungal treatment.the objective of this study was to investigate the capacity of decolorization and detoxification of the textile dyes reactive red 198 (rr198), reactive blue 214 (rb214), reactive blue 21 (rb21) and the mixture of the three dyes (mxd) by penicillium simplicissimum incqs 40211. the dye rb21, a phthalocyanine, was totally decolorized in 2 days, and the others, the monoazo rr198, the diazo rb214 and mxd were decolorized after 7 days by p. simplicissimum. initially the dye decolorization involved dye ...200924031428
characterisation and localisation of the opsin protein repertoire in the brain and retinas of a spider and an onychophoran.opsins have been found in the majority of animals and their most apparent functions are related to vision and light-guided behaviour. as an increasing number of sequences have become available it has become clear that many opsin-like transcripts are expressed in tissues other than the eyes. opsins can be divided into three main groups: rhabdomeric opsins (r-opsins), ciliary opsins (c-opsins) and group 4 opsins. in arthropods, the main focus has been on the r-opsins involved in vision. however, w ...201324010579
identification of the precise kairomone-sensitive period and histological characterization of necktooth formation in predator-induced polyphenism in daphnia pulex.many organisms have the ability to alter their development in the presence of predators, leading to predator-induced defenses that reduce vulnerability to predation. in the water flea daphnia pulex, small protuberances called 'neckteeth' form in the dorsal neck region in response to kairomone(s) released by predatory phantom midges (chaoborus larvae). although previous studies suggested that kairomone sensitivity begins when chemoreceptors begin to function during embryogenesis, the exact critic ...201323915154
copper/zinc superoxide dismutase from the cladoceran daphnia magna: molecular cloning and expression in response to different acute environmental stressors.the copper/zinc superoxide dismutase (cu/zn-sod) is a representative antioxidant enzyme that is responsible for the conversion of superoxide to oxygen and hydrogen peroxide in aerobic organisms. cu/zn-sod mrnas have been cloned from many species and employed as useful biomarkers of oxidative stresses. in the present study, we cloned cu/zn-sod cdna from the cladoceran daphnia magna, analyzed its catalytic properties, and investigated mrna expression patterns after exposure to known oxidative stre ...201323815380
combined exposure to cyanobacteria and carbaryl results in antagonistic effects on the reproduction of daphnia pulex.in aquatic ecosystems, daphnia are exposed to a wide variety of natural and chemical stressors that can cause interactive effects resulting in an increased impact on aquatic ecosystems. the authors therefore investigated the interactive effects of harmful cyanobacteria (cyanohabs) with carbaryl in daphnia pulex, because cyanobacteria have become an important concern for aquatic ecosystems. daphnia were exposed for 21 d to 4 selected cyanobacteria (aphanizomenon sp., cylindrospermopsis raciborski ...201323733205
interactive effects of xenobiotic, abiotic and biotic stressors on daphnia pulex--results from a multiple stressor experiment with a fractional multifactorial design.pollutant effects on aquatic key species are confounded by multiple abiotic and biotic stressors. to better discriminate and understand the intrinsic and environmental correlates of changing aquatic ecosystems, we untangle in present study how the effects of a low-dosed fungicide on daphnids (via different exposure routes) becomes modified by increasing temperature and the presence of a predator. using a fractional multifactorial test design, the individual growth, reproduction and population gr ...201323727598
interspecific differences between d. pulex and d. magna in tolerance to cyanobacteria with protease inhibitors.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' to ...201323650523
a transgenerational endocrine signaling pathway in crustacea.environmental signals to maternal organisms can result in developmental alterations in progeny. one such example is environmental sex determination in branchiopod crustaceans. we previously demonstrated that the hormone methyl farnesoate could orchestrate environmental sex determination in the early embryo to the male phenotype. presently, we identify a transcription factor that is activated by methyl farnesoate and explore the extent and significance of this transgenerational signaling pathway.201323613913
function, diversity, and application of insect juvenile hormone epoxidases (cyp15).juvenile hormones (jhs) represent a family of sesquiterpenoid hormones in insects, and they play a key role in regulating development, metamorphosis, and reproduction. the last two steps of the jh biosynthetic pathway, epoxidation and methyl esterification of farnesoic acid to jh, are insect specific, and thus have long been considered a promising target for biorational insecticides. recently, the enzymes involved in the last two steps have been molecularly identified: jh acid methyltransferase ...201723586995
acute toxicity, critical body residues, michaelis-menten analysis of bioaccumulation, and ionoregulatory disturbance in response to waterborne nickel in four invertebrates: chironomus riparius, lymnaea stagnalis, lumbriculus variegatus and daphnia pulex.we investigated the bioaccumulation and acute toxicity (48 h or 96 h) of ni in four freshwater invertebrate species in two waters with hardness of 40 (soft water) and 140 mg l(-1) as caco(3) (hard water). sensitivity order (most to least) was lymnaea stagnalis > daphnia pulex > lumbriculus variegatus > chironomus riparius. in all cases water hardness was protective against acute ni toxicity with lc(50) values 3-3.5× higher in the hard water vs. soft water. in addition, higher water hardness sign ...201323570754
[enhancement of hypoxia tolerance and survival rate of daphnia in severe hypoxia based on acidic preconditioning].ph homeostasis is essential for development, proliferation and apoptosis of cells. once the ph balances are broken, cell functions and survival will be affected. nevertheless, moderate acidosis could result in adaptive responses for cell survival and increase tolerance to harmful stress. here we found that acidic preconditioning (apc) could significantly increase the survival rate of daphnia pulex, a freshwater invertebrate, during severe hypoxic insult. meanwhile, the acidic treatment significa ...201223469549
cardioacceleratory function of the neurohormone ccap in the mosquito anopheles gambiae.crustacean cardioactive peptide (ccap) is a highly conserved arthropod neurohormone that is involved in ecdysis, hormone release and the modulation of muscle contractions. here, we determined the ccap gene structure in the malaria mosquito anopheles gambiae, assessed the developmental expression of ccap and its receptor and determined the role that ccap plays in regulating mosquito cardiac function. race sequencing revealed that the a. gambiae ccap gene encodes a neuropeptide that shares 100% am ...201323364571
how to measure maturation: a comparison of probabilistic methods used to test for genotypic variation and plasticity in the decision to mature.maturation is a developmental trait that plays a key role in shaping organisms' life-history. however, progress in understanding how maturation phenotypes evolve has been held back by confusion over how best to model maturation decisions and a lack of studies comparing genotypic variation in maturation. here, we fitted probabilistic maturation reaction norms (pmrns) to data collected from five clones of daphnia magna and five of daphnia pulex collected from within and between different populatio ...201323356623
in silico characterization of the insect diapause-associated protein couch potato (cpo) in calanus finmarchicus (crustacea: copepoda).couch potato (cpo) is an rna-binding protein involved in the regulation of nervous system development and adult diapause in insects. within insects, this protein is highly conserved, yet it has not been identified in another large arthropod group, the crustacea. here, functional genomics was used to identify putative cpo homologs in the copepod calanus finmarchicus, a planktonic crustacean that undergoes seasonal diapause. in silico mining of expressed sequence tag (est) and 454 pyrosequencing d ...201223262277
changes in water chemistry can disable plankton prey defenses.the effectiveness of antipredator defenses is greatly influenced by the environment in which an organism lives. in aquatic ecosystems, the chemical composition of the water itself may play an important role in the outcome of predator-prey interactions by altering the ability of prey to detect predators or to implement defensive responses once the predator's presence is perceived. here, we demonstrate that low calcium concentrations (<1.5 mg/l) that are found in many softwater lakes and ponds dis ...201222949653
from genes to behavior: investigations of neurochemical signaling come of age for the model crustacean daphnia pulex.the cladoceran crustacean daphnia pulex has served as a standard organism for aquatic toxicity testing for decades. the model organism status of d. pulex rests largely on its remarkable ability to rapidly adapt morphologically, physiologically and behaviorally to a wide range of environmental challenges, as well as on its parthenogenetic reproduction and ease of laboratory culture. as in all multicellular organisms, neurochemical control systems are undoubtedly major contributors to the function ...201222786629
electroantennogram measurement of the olfactory response of daphnia spp. and its impairment by waterborne copper.in this study an electroantennogram (eag) method was developed for use on live daphniids. the eag response of daphnia magna and daphnia pulex to a variety of amino acids was measured. the strongest response measured was elicited by l-arginine and was shown to induce a concentration-dependent response indicating the response is olfactory in nature. subsequent exposures of d. magna to a low, ecologically-relevant concentration of copper (7.5 μg/l) showed a disruption in eag function. this study ut ...201222721843
chaoborus and gasterosteus anti-predator responses in daphnia pulex are mediated by independent cholinergic and gabaergic neuronal signals.many prey species evolved inducible defense strategies that protect effectively against predation threats. especially the crustacean daphnia emerged as a model system for studying the ecology and evolution of inducible defenses. daphnia pulex e.g. shows different phenotypic adaptations against vertebrate and invertebrate predators. in response to the invertebrate phantom midge larvae chaoborus (diptera) d. pulex develops defensive morphological defenses (neckteeth). cues originating from predato ...201222590631
daphnia hr96 is a promiscuous xenobiotic and endobiotic nuclear receptor.daphnia pulex is the first crustacean to have its genome sequenced. the genome project provides new insight and data into how an aquatic crustacean may respond to environmental stressors, including toxicants. we cloned daphnia pulex hr96 (dappuhr96), a nuclear receptor orthologous to the car/pxr/vdr group of nuclear receptors. in drosophila melanogaster, (hormone receptor 96) hr96 responds to phenobarbital exposure and has been hypothesized as a toxicant receptor. therefore, we set up a transact ...201222466357
high through-put sequencing of the parhyale hawaiensis mrnas and micrornas to aid comparative developmental studies.understanding the genetic and evolutionary basis of animal morphological diversity will require comparative developmental studies that use new model organisms. this necessitates development of tools for the study of genetics and also the generation of sequence information of the organism to be studied. the development of next generation sequencing technology has enabled quick and cost effective generation of sequence information. parhyale hawaiensis has emerged as a model organism of choice due ...201222448274
elaphoidella grandidieri (harpacticoida: copepoda): demographic characteristics and possible use as live prey in aquaculture.in freshwater ecosystems, rotifers and cladocerans are ideal prey for fish larvae whereas copepods, due to their purported low growth rate and predatory tendency, are not. we recently isolated the parthenogenetic elaphoidella grandidieri (gueme et richard, 1893) a benthic freshwater harpacticoid, from a fish farm in the state of morelos, central mexico and tested its potential as a live prey organism for larval vertebrates. population growth and life table demography experiments were conducted, ...201122315830
identification and characterization of a serine protease inhibitor (ptserpin) in the swimming crab portunus trituberculatus.serine protease inhibitors (serpins) play a key role in diverse immune biological processes. a serine protease inhibitor (serpin), namely ptserpin, was identified from the haemocyte cdna library of swimming crab portunus trituberculatus. the full-length ptserpin cdna was 1593 bp, including an open reading frame (orf) of 1227 bp encoding a polypeptide of 408 amino acids with estimated molecular mass of 45.048 kda and theoretical isoelectric point of 7.23. predicted tertiary structure of ptserpin ...201222245590
de novo assembly and characterization of a maternal and developmental transcriptome for the emerging model crustacean parhyale hawaiensis.arthropods are the most diverse animal phylum, but their genomic resources are relatively few. while the genome of the branchiopod daphnia pulex is now available, no other large-scale crustacean genomic resources are available for comparison. in particular, genomic resources are lacking for the most tractable laboratory model of crustacean development, the amphipod parhyale hawaiensis. insight into shared and divergent characters of crustacean genomes will facilitate interpretation of future dev ...201122118449
impacts of salinity and fish-exuded kairomone on the survival and macromolecular profile of daphnia pulex.global warming is already causing salinization of freshwater ecosystems located in semi-arid regions, including turkey. daphnids, which are important grazers on phytoplankton and a major food source for fish and invertebrates, are sensitive to not only changes in salinity levels, but also presence of predators. in this study, the interactive effect of salinity toxicity (abiotic factor) with predation pressure mimicked by the fish-exuded kairomone (biotic factor) and the effect of salt acclimatio ...201122102012
a remarkably stable tipe gene cluster: evolution of insect para sodium channel auxiliary subunits.first identified in fruit flies with temperature-sensitive paralysis phenotypes, the drosophila melanogaster tipe locus encodes four voltage-gated sodium (nav) channel auxiliary subunits. this cluster of tipe-like genes on chromosome 3l, and a fifth family member on chromosome 3r, are important for the optional expression and functionality of the para nav channel but appear quite distinct from auxiliary subunits in vertebrates. here, we exploited available arthropod genomic resources to trace th ...201122098672
[the application value of water flea daphnia pulex for hypoxia model].hypoxia-inducible factor (hif) is an important transcription factor under hypoxic condition in many organisms, and plays a key role in the induction of hypoxia tolerance. it is necessary to establish a hypoxia model for hif and to perform further hypoxia tolerance research. to investigate the value of daphnia as a model organism in hypoxia precondition, we developed a preconditioning protocol with a model organism, daphnia pulex. we found that two episodes of exposure to hypoxic solution resulte ...201121936389
genomic identification of a putative circadian system in the cladoceran crustacean daphnia pulex.essentially nothing is known about the molecular underpinnings of crustacean circadian clocks. the genome of daphnia pulex, the only crustacean genome available for public use, provides a unique resource for identifying putative circadian proteins in this species. here, the daphnia genome was mined for putative circadian protein genes using drosophila melanogaster queries. the sequences of core clock (e.g. clock, cycle, period, timeless and cryptochrome 2), clock input (cryptochrome 1) and clock ...201121798832
neurogenesis in the water flea daphnia magna (crustacea, branchiopoda) suggests different mechanisms of neuroblast formation in insects and crustaceans.within euarthropods, the morphological and molecular mechanisms of early nervous system development have been analysed in insects and several representatives of chelicerates and myriapods, while data on crustaceans are fragmentary. neural stem cells (neuroblasts) generate the nervous system in insects and in higher crustaceans (malacostracans); in the remaining euarthropod groups, the chelicerates (e.g. spiders) and myriapods (e.g. millipedes), neuroblasts are missing. in the latter taxa, groups ...201121624360
frequency and inheritance of non-male producing clones in daphnia magna: evolution towards sex specialization in a cyclical parthenogen?in daphnia (cladocera, crustacea), parthenogenetic reproduction alternates with sexual reproduction. individuals of both sexes that belong to the same parthenogenetic line are genetically identical, and their sex is determined by the environment. previously, non-male producing (nmp) genotypes have been described in species of the daphnia pulex group. such genotypes can only persist through phases of sexual reproduction if they co-occur with normal (mp) genotypes that produce both males and femal ...201121599772
histaminergic signaling in the central nervous system of daphnia and a role for it in the control of phototactic behavior.daphnia magna and daphnia pulex are well-established model organisms in the fields of ecotoxicology and toxicogenomics. among the many assays used for determining the effects of environmental and anthropogenic stressors on these animals is monitoring for changes in their phototactic behavior. in most arthropods, histamine has been shown to play a key role in the visual system. currently, nothing is known about histaminergic signaling in either d. magna or d. pulex. here, a combination of immunoh ...201121525325
genomics of environmentally induced phenotypes in 2 extremely plastic arthropods.understanding how genes and the environment interact to shape phenotypes is of fundamental importance for resolving important issues in adaptive evolution. yet, for most model species with mature genetics and accessible genomic resources, we know little about the natural environmental factors that shape their evolution. by contrast, animal species with deeply understood ecologies and well characterized responses to environmental cues are rarely subjects of genomic investigations. here, we previe ...201721525179
chitobiase activity as an indicator of altered survival, growth and reproduction in daphnia pulex and daphnia magna (crustacea: cladocera) exposed to spinosad and diflubenzuron.chitobiase is involved in exoskeleton degradation and recycling during the moulting process in arthropods. in aquatic species, the moulting fluid is released into the aqueous environment, and chitobiase activity present therein can be used to follow the dynamics of arthropod populations. here, chitobiase activity was used for monitoring the impact of mosquito candidate larvicides on daphnia pulex and daphnia magna under laboratory conditions. both species were exposed to spinosad (2, 4, 8μgl(-1) ...201121497397
trehalose and vitreous states: desiccation tolerance of dormant stages of the crustaceans triops and daphnia.several aquatic organisms are able to withstand extreme desiccation in at least one of their life stages. this is commonly known as "anhydrobiosis." it was often thought that to tolerate such a desiccated state required high amounts of compatible solutes such as the nonreducing disaccharide trehalose, which protects cellular structures by water replacement and glass formation. trehalose levels of dormant eggs and cysts of five freshwater crustaceans (daphnia magna, daphnia pulex, triops longicau ...201321460525
pigment-dispersing hormone in daphnia interneurons, one type homologous to insect clock neurons displaying circadian rhythmicity.we report identification of a beta-type pigment-dispersing hormone (pdh) identical in two water flea species, daphnia magna and daphnia pulex. it has been identified by cloning of precursors, chromatographic isolation from tissue extracts followed by immunoassays and de novo-mass spectrometric sequencing. the peptide is restricted to a complex system of distinct interneurons in the brain and visual ganglia, but does not occur in neurosecretory cells projecting to neurohemal organs as in decapod ...201121365282
not just another genome.sequence analysis of the daphnia pulex genome holds some surprises that could not have been anticipated from what was learned so far from other arthropod genomes. it establishes daphnia as an eco-genetical model organism par excellence.201121294909
the ecoresponsive genome of daphnia pulex.we describe the draft genome of the microcrustacean daphnia pulex, which is only 200 megabases and contains at least 30,907 genes. the high gene count is a consequence of an elevated rate of gene duplication resulting in tandem gene clusters. more than a third of daphnia's genes have no detectable homologs in any other available proteome, and the most amplified gene families are specific to the daphnia lineage. the coexpansion of gene families interacting within metabolic pathways suggests that ...021292972
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