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PubMed2002

Toxicity and bioaccumulation of fipronil in the nontarget arthropodan fauna associated with subalpine mosquito breeding sites.

In order to examine ecological impact of fipronil use for larval culicine control in natural hydrosystems, toxicity and bioaccumulation of this new insecticide were analyzed on aquatic species representative of the nontarget arthropodan fauna (nonculicine larval Diptera: Chaoboridae, Chironomidae; planktonic Crustacea: Cladocera, Copepoda, Ostracoda) associated with target larval mosquito populations in the subalpine breeding sites. Standard toxicological bioassays using fipronil aqueous solutions from 1 to 2000 nM indicated different sensitivity levels among species. Insecticide bioaccumulation analyses, using [(14)C]fipronil solutions in simplified laboratory ecosystem, also indicated large differences among species. These differences may come from biological parameters characteristic of each species. Taking into account these nontarget effects of fipronil, a possible strategy of use of this insecticide for integrated mosquito control management was proposed, which is based upon selective dietary absorption of the insecticide by larval Culicidae.

Absorption↗
PubMed2000

Mitochondrial DNA variation and the evolutionary history of cryptic Gammarus fossarum types.

The evolutionary history of the cryptic Gammarus fossarum species complex (Crustacea, Amphipoda) in Central Europe was approached by investigating the genetic variation in populations of a natural contact zone. Nucleotide sequence variation of a 395-bp segment of the mitochondrial 16S rRNA gene was compared to that of six nuclear allozyme loci. Three major mtDNA lineages were found, the eastern clade being consistent with the former allozyme type A. The two western clades (types B and C) were not distinguished previously. Strong sequence divergence and correlation with nuclear genetic isolation in syntopic populations, however, justifies the specific status of the three G. fossarum types. The common speciation event is believed to be very old (Miocene). The within-type mtDNA variation is probably molded by the ice ages, with type B populations being most affected. Moreover, the patch-like distribution of mtDNA type B lineages in an area near the contact zone corroborates the hypothesis of a recent colonization.

Animals↗
PubMed2000

28S rDNA evolution in the Eumalacostraca and the phylogenetic position of krill.

The Malacostraca are an ancient and morphologically diverse class of Crustacea. The phylogenetic position of one order within this class, the Euphausiacea ("krill," subclass Eumalacostraca) was investigated using 28S rDNA sequences from representatives of several malacostracan orders. Phylogenies for these sequences were estimated by maximum-likelihood and maximum-parsimony analysis. The results of these analyses produced a new scheme for evolution within the Eumalacostraca. The new phylogenies suggested that Euphausiacea are most closely related to the Mysida and not the Decapoda, as is generally thought. Furthermore, the Mysida were found not to be closely related to the Lophogastrida, which are often considered their sister taxon. These hypotheses were tested against the hypotheses of monophyly for the Eucarida, Mysidacea, and Peracarida and found to be significantly better on the basis of the 28S rDNA data.

Animals↗
PubMed2000

Molecular genetics of crustacean feeding appendage development and diversification.

Arthropods dominate our seas, land, and air and have done so for hundreds of millions of years. Among the arthropods, crustaceans present us with a rich history of morphological change, much of which is still represented among extant forms. Crustacea largely interact with their environment via their appendages; thus vast amounts of variation exist among the different appendages of a single individual and between appendages from different species. Comparative studies of crustacean appendage development present us with an important story regarding the evolution of morphology over both relatively short (a few million years) and relatively long (a few hundred million years) evolutionary time scales. Recent studies have used the genetic and molecular data from Drosophila development to try to understand the molecular basis for some of the variations seen in crustacean limbs. Here we review some of these data based on the expression patterns of the genes Ultrabithorax, abdominal - A, Sex combs reduced, and Distal-less.

Animals↗
PubMed1987

Quantification and characterization of metallothioneins in tissues of lower vertebrates and invertebrates.

Metallothionein (MT) and the related metal-binding proteins in tissues of lower vertebrates and invertebrates were isolated by gel filtration chromatography (conventional liquid and high performance liquid chromatography). The metal-binding proteins including MT were detected by determining the metals bound to the proteins by atomic absorption spectrophotometry. This analytical procedure was recommendable as the first step to characterize unknown metal-binding proteins in diverse living bodies. As MT in the lower vertebrates, avian (Japanese quail), reptilian (tortoise), amphibian (8 species of frogs and 2 species of tailed amphibians) and fish MTs were isolated and characterized. The number of isoMTs was different among animals belonging not only to different classes but also to different species in the same family. One of the isoMTs in the avian, reptilian and amphibian MTs was shown to contain one histidinyl residue. Cadmium(Cd)-binding proteins were induced in three species of insect (Insecta, Arthropoda) larvae (midge, fleshfly and silkworm) by loading of Cd. Distribution of Cd in insect tissues was different among the three species though the alimentary canal was commonly the most important tissue for the storage of Cd in all species. Further, Cd in the soluble fractions was bound to inducible proteins of different molecular sizes in the three species. Cd-binding protein was also detected in the waterflea (Crustacea, Arthropoda) after loading of Cd. Cd-binding proteins induced in the earthworm (Oligochaeta, Annelida) by loading of Cd were a mixture of proteins with three different molecular sizes. One of the Cd-binding proteins with an apparent molecular size of 7,000 was shown to have characteristics of MT.

Amphibians↗
PubMed1981

The structure and distribution of satellite cells of cardiac muscles in decapod crustaceans.

The structure and distribution of satellite cells of cardiac muscles were examined in twenty-one species of animals chosen from each tribe within the order Decapoda (Arthropoda, Crustacea). The satellite cells were found in all animals observed. Most of them are morphologically identical with those described in different striated muscles of other species, but some cells have unusual features. The decapod satellite cell occasionally lies right over the region corresponding to the intercalated disc between the apposed cardiac muscle cells. The cell sends cytoplasmic processes into the adjacent muscle cells, enabling the plasma membrane to make close contact with the cleft opening of the intercalated disc, and with the myofibril at the level of the Z-line. Another characteristic feature is the presence of "paired" cells. Such cells are clearly separated from each other over most of the contact area by the respective plasma membranes, which are smooth in appearance and devoid of specialized regions. The significance of the presence of satellite cells in decapod cardiac muscle and its possible role are discussed and compared with those described for other species.

Animals↗
PubMed1978

The acute and chronic effects of cadmium on the estuarine mysid, Mysidopsis bahia.

Mysids, small shrimp-like crustacea, proved to be a practical bioassay animal for investigating the effects of cadmium in seawater and may serve this purpose for other pollutants. In the laboratory under flow-through test conditions, the mysid, Mysidopsis bahia, was more sensitive to cadmium than other crustaceans tested. LC50 values were 15.5 microgram/l within 96 hrs and 11.3 microgram/l during a 17-day life cycle, whereas LC50's for other selected crustaceans were between 120 and 720 microgram/l. Results of life-cycle bioassays can aid in the establishment of water quality criteria for marine and estuarine organisms.

Animals↗
PubMed2004

Differential expression of duplicated opsin genes in two eyetypes of ostracod crustaceans.

In the first molecular study of ostracod (Crustacea) vision, we present partial cDNA sequences of ostracod visual pigment genes (opsins). We found strong support for differential expression of opsins in ostracod median and compound eyes and suggest that photoreceptor specific expression may be a general phenomenon in organisms with multiple receptors. We infer that eye-specific expression predates the divergence of the two species examined, Skogsbergia lerneri and Vargula hilgendorfii, because eye-specific opsin orthologs are present in both species. We found multiple opsin loci in ostracods, estimating that at least eight are present in Skogsbergia lerneri. All opsins from both ostracod species examined are more closely related to each other than to any other known opsin sequences. Because we find no evidence for gene conversion or alternative splicing, we suggest the occurrence of many recent gene duplications. Why ostracods may have retained multiple recent opsin gene duplicates is unknown, but we discuss several possible hypotheses.

Amino Acid Sequence↗
PubMed2000

The role of ion regulation in the control of the distribution of Gammarus tigrinus (Sexton) in salt-polluted rivers.

Fluctuating salinities at different sites on the German salt-polluted rivers Werra and Weser were compared with extracellular ion levels of specimens of Gammarus tigrinus (Sexton; Amphipoda, Crustacea), collected at the same sites. G. tigrinus regulated haemolymph concentrations of inorganic anions (Cl-, SO(4)2-, PO(4)3-) and cations (Na+, K+, Mg2+, Ca2+) during fluctuations of salt pollution in the upper Weser. This capacity to regulate varying levels of salt pollution in the upper Weser, correlated well with the distribution of the brackish amphipods in this river ecosystem. G. tigrinus tolerated periods of Na+ and Cl- stress (> 380 mmol l-1) without compensating these maxima by regulating extracellular Na+ and Cl-. However, during such bursts of Na+ and Cl- stress in Werra and Weser, the ability to regulate extracellular [K+] at river water K+ stress of > or = 6.0 mmol l-1 may explain why this brackish species has been more successful in these rivers than its competitors like Gammarus pulex. The present investigation demonstrates that the water salinity affects the [NO3-] in the haemolymph of G. tigrinus. With increasing hypo-osmotic stress the animals accumulate increasing amounts of NO3-. A simultaneous increase in stream water [NO3-] causes an additional accumulation of NO3- in the haemolymph. The high extent of accumulation indicates that active ion transport systems may be involved. The accumulation of NO3- in the haemolymph has low physiological consequences to G. tigrinus, but when hypo-osmotically stressed under anoxic conditions, nitrite formed by the reduction of nitrate may have an adverse affect on the metabolism of G. tigrinus.

Adaptation, Physiological↗
PubMed2003

Metazoan parasites and feeding behaviour of four small-sized fish species from the central North Sea.

The metazoan parasites and stomach contents of the small-sized demersal fishes Agonus cataphractus, Buglossidium luteum, Callionymus lyra and Rhinonemus cimbrius were studied and analysed. The fishes were captured using various sampling gears at 12 stations in the central North Sea. A total of 16 metazoan parasite species were isolated: six adult Digenea, three larval and adult Cestoda, four larval and adult Nematoda and three larval and adult Crustacea. With nine parasites species each, A. cataphractus and R. cimbrius harboured the highest parasite diversity, while B. luteum and C. lyra hosted only six and five parasite species, respectively. Eighteen new hosts and four new locality records were established. No Myxozoa, Monogenea or Acanthocephala were found. Most of the detected parasites showed a wide geographical range and a low host-specificity. The composition of the parasite fauna differed between the fish species, in accordance with their different feeding behaviours. The diet of bentho-pelagic feeders ( A. cataphractus, R. cimbrius) was more diverse in comparison with the more specialised benthic feeders ( C. lyra, B. luteum). This correlated with the lower diversity of heteroxenic parasites within both small-sized benthic fish species.

Animals↗
PubMed2006

Reduced metals concentrations of water, sediment and hyalella azteca from lakes in the vicinity of the sudbury metal smelters, Ontario, Canada.

Hyalella azteca (Crustacea: Amphipoda), water and sediments from 12 circum-neutral lakes between Sudbury and North Bay in Ontario, Canada were sampled in August 1998 and analyzed for 10 metals including Cu, Zn, Cd, Ni, Pb, Co, Mo, V, Ba and Ti. Statistical analyses showed that concentrations of the metals in H. azteca, water and sediment differed significantly (ANOVA, P<0.05) among lakes (except for Zn and Pb in H. azteca and Mo in water). There was a trend of declining metal concentration, especially for Cu, Ni and Co (in water, Hyalella and sediment), with distance from the smelters indicating the reduced impact of atmospheric pollution. Metal concentrations of lakes (water) in the Sudbury area were found to be lower compared to data from the 1970s and 1980s indicating an improvement in water quality. Metal concentrations in field-collected amphipods compared favorably with those measured in the laboratory in animals exposed to deep-water sediments, provided metal concentrations were not extremely low (e.g., Pb) and that water chemistry differences (e.g., pH) were taken into account for some metals (especially Cd). In general bioaccumulation of metals in H. azteca was predicted better from surface water than from sediment total metal.

Animals↗
PubMed1982

The distribution of zinc, cadmium, lead and copper within the hepatopancreas of a woodlouse.

The distribution of metals within the hepatopancreas of Oniscus asellus (Crustacea, Isopoda) from two uncontaminated sites, and two sites contaminated with zinc, cadmium and lead, has been studied by atomic absorption spectrophotometry, light microscopy, transmission and scanning electron microscopy and X-ray microanalysis. The hepatopancreas contains two types of intracellular granule. The first type, in the S cells, are spherical granules which contain copper, sulphur and calcium. In woodlice from contaminated sites, these 'copper' granules, also contain zinc, cadmium and lead. The second type, in the B cells, are flocculent deposits which contain iron. In woodlice from contaminated sites, these 'iron' granules also contain zinc and lead. Moribund woodlice from contaminated sites have large numbers of 'copper' and 'iron' granules in the hepatopancreas and a fine deposit of zinc and lead on the membranes of the cells. There are numerous microorganisms in close association with the microvillous border of the hepatopancreas of woodlice from all four sites. Within the microorganisms of Oniscus asellus from contaminated sites, there are deposits of material which contain zinc, lead, calcium and phosphorus 'Copper' and 'iron' granules could have evolved as storage sites for essential metals to be utilized when demand from the body exceeds uptake from the food. Woodlice in contaminated sites may be able to 'detoxify' potentially harmful amounts of essential and non-essential metals by storing them in a relatively insoluble form within these granules.

Animals↗
PubMed1996

The stomatogastric nervous system: a formal approach.

A discrete mathematical formalism (d-space) which is specifically designed to investigate discrete aspects of behavior is applied to the foregut of decapod crustacea. This approach differs from continuous modeling techniques in that the analysis determines a structure in which the observed behavior of the foregut is constrained. A notation for the implementation of the formalism is developed as well as a coordinate system natural to the functioning of the gastric mill. The formalism is used to organize previous observations that suggest potential courses of further experimental investigation. A detailed analysis of observed chewing modes of the gastric mill is presented, along with a discussion of the overall organization of the interrelationships between these modes. The investigation also addresses the relationship between behavioral modes of a pyloric muscle found in the shrimp Palaemon. Two alternative hypotheses are presented to describe the relationship of the behavioral components of the gastric mill: an interlaced control scheme in which the components are freely exchanged, and a top-down control system where the chewing modes are rigidly separated into packages. Flow through regions of state space in time is found to be important in determining the relations between the discrete behavioral components. The behavior of the foregut, like that of other motor control systems, is shown to fit naturally into the d-space formalism.

Animals↗
PubMed2006

Testosterone metabolism in Neomysis integer following exposure to benzo(a)pyrene.

Cytochromes P450 (CYPs) are important enzymes involved in the regulation of hormone synthesis and in the detoxification and/or activation of xenobiotics. CYPs are found in virtually all organisms, from archae, and eubacteria to eukaryota. A number of endocrine disruptors are suspected of exerting their effects through disruption of normal CYP function. Consequently, alterations in steroid hormone metabolism through changes in CYP could provide an important tool to evaluate potential effects of endocrine disruptors. The aim of this study was to investigate the potential effects of the known CYP modulator, benzo(a)pyrene (BaP), on the testosterone metabolism in the invertebrate Neomysis integer (Crustacea; Mysidacea). N. integer were exposed for 96 h to 0.43, 2.39, 28.83, 339.00 and 1,682.86 microg BaP L(-1) and a solvent control, and subsequently their ability to metabolize testosterone was assessed. Identification and quantification of the produced phase I and phase II testosterone metabolites was performed using liquid chromatography coupled with multiple mass spectrometry (LC-MS2). Significant changes were observed in the overall ability of N. integer to metabolize testosterone when exposed to 2.39, 28.83, 339.00 and 1,682.86 microg BaP L(-1) as compared to the control animals.

Animals↗
PubMed2006

Marine invertebrate cytochrome P450: emerging insights from vertebrate and insects analogies.

Cytochrome P450 enzymes (P450s) are responsible for the oxidative metabolism of a plethora of endogenous and exogenous substrates. P450s and associated activities have been demonstrated in numerous marine invertebrates belonging to the phyla Cnidaria, Annelida (Polychaeta), Mollusca, Arthropoda (Crustacea) and Echinodermata. P450s of marine invertebrates and vertebrates show considerable sequence divergence and the few orthologs reveal the selective constraint on physiologically significant enzymes. P450s are present in virtually all tissues of marine invertebrates, although high levels usually are found in hepatic-like organs and steroidogenic tissues. High-throughput technologies result in the rapid acquisition of new marine invertebrate P450 sequences; however, the understanding of their function is poor. Based on analogy to vertebrates and insects, it is likely that P450s play a pivotal role in the physiology of marine invertebrates by catalyzing the biosynthesis of signal molecules including steroids such as 20-hydroxyecdysone (the molting hormone of crustaceans). The metabolism of many exogenous compounds including benzo(a)pyrene (BaP), pyrene, ethoxyresorufin, ethoxycoumarin and aniline is mediated by P450 enzymes in tissues of marine invertebrates. P450 gene expression, protein levels and P450 mediated metabolism of xenobiotics are induced by PAHs in some marine invertebrate species. Thus, regulation of P450 enzyme activity may play a central role in the adaptation of animals to environmental pollutants. Emphasis should be put on the elucidation of the function and regulation of the ever-increasing number of marine invertebrate P450s.

Animals↗
PubMed2006

Distribution and ecotoxicity of chlorotriazines in the Scheldt Estuary (B-Nl).

As part of the Endis-Risks project, the current study describes the occurrence of the chlorotriazine pesticides atrazine, simazine and terbutylazine in water, sediment and suspended matter in the Scheldt estuary (B-Nl) from 2002 to 2005 (3 samplings a year, 8 sampling points). Atrazine was found at the highest concentrations, varying from 10 to 736 ng/l in water and from 5 up to 10 ng/g in suspended matter. Simazine and terbutylazine were detected at lower concentrations. Traces of the targeted pesticides were also detected in sediments, but these were below the limit of quantification. As part of an ecotoxicological assessment, we studied the potential effect of atrazine on molting of Neomysis integer (Crustacea:Mysidacea), a resident invertebrate of the Scheldt Estuary and a proposed test organism for the evaluation of endocrine disruption. Following chronic exposure ( approximately 3 weeks), atrazine did not significantly affect mysid molting at environmentally relevant concentrations (up to 1 microg/l).

Animals↗
PubMed2005

Microscopical and functional aspects of calcium-transport and deposition in terrestrial isopods.

Terrestrial isopods (Crustacea) are excellent model organisms to study epithelial calcium-transport and the regulation of biomineralization processes. They molt frequently and resorb cuticular CaCO(3) before the molt to prevent excessive loss of Ca(2+) ions when the old cuticle is shed. The resorbed mineral is stored in CaCO(3) deposits within the ecdysial gap of the first four anterior sternites. After the molt, the deposits are quickly resorbed to mineralise the posterior part of the new cuticle. The deposits contain numerous small spherules composed of an organic matrix and amorphous CaCO(3), which has a high solubility and, therefore, facilitates quick mobilization of Ca(2+) and HCO(3)(-) ions. During the formation and resorption of the deposits large amounts of Ca(2+), HCO(3)(-) and H(+) are transported across the anterior sternal epithelial cells. Within the last years, various light and electron microscopical techniques have been used to characterize the CaCO(3) deposits and the cellular mechanisms involved in biomineralization. The work on the CaCO(3) deposits includes studies on the ultrastructure of the deposits, the sequence of events during deposit formation and dissolution, and the mineral composition of the sternal deposits. The differentiation of the anterior sternal epithelial cells and the mechanisms of epithelial ion transport required for the mineralization and demineralisation of the deposits was studied using various analytical light and electron microscopical techniques including polarized light microscopy, immunocytochemistry, electron microprobe analysis, electron energy loss spectroscopy and electron spectroscopic imaging. Comparative analysis of deposit morphology and the differentiation of the sternal epithelia provide information on the evolution of CaCO(3) deposit formation in relation to the degree of adaptation to terrestrial environments.

Animals↗
PubMed2006

Effects of methoprene, nonylphenol, and estrone on the vitellogenesis of the mysid Neomysis integer.

The induction of the female-specific protein, vitellogenin, in male fish is a well-established endpoint to assess exposure to estrogen-like chemicals. The use of vitellogenesis as a biomarker for xenobiotic exposure in egg-laying invertebrates, however, is still relatively unexplored. Recently, we developed a quantitative enzyme-linked immunosorbent assay (ELISA) for vitellin in Neomysis integer (Crustacea: Mysidacea) to study mysid vitellogenesis and its potential disruption by xenobiotics. In this study, gravid mysids were exposed to methoprene, nonylphenol, and estrone for 96 h. All methoprene-exposed (0.01, 1, and 100 microg/L) animals had lower vitellin levels compared to the control animals, though this effect was not statistically significant. Exposure to nonylphenol resulted in significantly induced vitellin levels in the lowest exposure concentration (0.01 microg/L), whereas no effects were observed at higher concentrations. Estrone significantly decreased vitellin levels at the highest test concentration (1 microg/L). These results indicate that mysid vitellogenesis can be disrupted following chemical exposure. Difficulties in the interpretation of the observed chemical-specific and concentration-specific responses in this study highlight the need for a better understanding of hormone regulation of crustacean vitellogenesis.

Animals↗