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At least 235 records · Page 13Linked to original sources
PubMed2006

Molecular phylogeny of the Drosophila virilis section (Diptera: Drosophilidae) based on mitochondrial and nuclear sequences.

Regardless of the well-documented virilis species group, most groups of the Drosophila virilis section have not been completely studied at molecular level since it was suggested. Therefore, phylogenetic relationships among and within species groups of the virilis section are generally unknown. In present paper, the complete mitochondrial ND2 gene and fragment of COI gene in combination with a nuclear gene, Adh coding region, were used to derive the most extensive molecular phylogeny to date for the Drosophila virilis section. A total of 111 individuals covering 61 species were sampled in this study. Novel phylogenetic findings included (1) support for the paraphyly of the melanica and robusta species group and at least two subgroups of the robusta species group, the lacertosa and okadai subgroups, were distinguished as paraphyletic taxa. In addition, (2) present results revealed the sister relationship between D. moriwakii and the robusta subgroup, conflicting with current taxonomy regarding D. moriwakii, which was shifted from the robusta species group to the melanica group. (3) In contrast to the robusta and melanica species groups, monophyly of the polychaeta species group, the angor group and the virilis group was confirmed, respectively. However, the monophyletic quadrisetata species group was resolved with uncertainty. (4) Our analyses of combined data set suggested close relationship between the quadrisetata species group and the unpublished clefta group, and the okadai subgroup is sister to the clade comprising of the quadrisetata and clefta species groups. Within the virilis section, D. fluvialis and three tropical species groups, the polychaeta group, the angor group and the repleta group, are found to branch off earlier than other ingroup taxa. This suggests that the virilis section might have originated in the Old World tropics. Besides, the derived status of the close affinities of the quadrisetata group, the clefta group, and the melanica and robusta groups is probably the result of their adaptation to forests between subtropical and cool-temperate climate. Based on the consideration of the phylogenetic placement of the species of the virilis section, we suggest that at least five independent migrations occurred from the Old World to the New World.

Animals↗
PubMed2004

Identification and quantification of n-octyl esters of alkanoic and hexanedioic acids and phthalates as urban wastewater markers in biota and sediments from estuarine areas.

A gas chromatographic method for the identification and quantification of n-octyl esters (from n-octyl tetradecanoate to n-octyl hexa-cosanoate including dioctyl hexanedioate) and phthalates [dibutyl phthalate, benzyl butyl phthalate and di(2-ethylhexyl) phthalate] in sediments and biota from estuarine environments is described. Standards used for identification and quantification of some n-octyl esters were synthesized. The method has allowed the analysis of these compounds in polychaeta (Nereis diversicolor), oysters (Crassostea angulata), crabs (Carcinus maenas) and fish (Chelon labrosus, Platichtys flesus and Chondostroma polylepis) that were collected at different locations of the Urdaibai estuary (Bizkaia, Basque Country, Spain). Total phthalates and n-octyl esters ranged between 0.01 and 12 microg g(-1) and 0.05 and 9.4 microg g(-1), respectively, and were predominantly found in polychaeta and fish. Sediments did not contain these compounds in significant amount, only benzyl butyl phthalate, dioctyl hexanedioate and di(2-ethylhexyl) phthalate were found above limit of detection (0.01-0.05 microg g(-1)).

Adipates↗
PubMed2004

Ground plan of the polychaete brain--I. Patterns of nerve development during regeneration in Dorvillea bermudensis (Dorvilleidae).

The nervous systems of adult specimens and regenerating fragments of Dorvillea bermudensis ("Polychaeta," Dorvilleidae) were stained with antisera directed against acetylated alpha-tubulin and analyzed by indirect fluorescence and confocal laser scanning microscopy. The anlage of each circumesophageal connective is initially doubled in regenerates and starts with the outgrowth of two nerves from each side of the ventral cord of the amputee. The inner nerves on each side, which become the ventral roots, fuse medially to form the ventral cerebral commissure, whereas the outer nerves become the dorsal roots. As development proceeds, both roots split again, to form the four cerebral commissures. In later stages, the two circumesophageal connectives of each side merge, the point of fusion progressing from the ventral cord toward the brain. In D. bermudensis, this process stops halfway along the connective, thus producing the typical polychaete pattern according to Orrhage ([ 1995] Acta Zool 79:215-234): Each single circumesophageal connective divides near the brain into dorsal and ventral roots, which themselves split into two branches to form the four cerebral commissures. From the results presented here, we conclude that each circumesophageal connective is basically a paired structure but is partially fused in species possessing dorsal roots and completely fused in species lacking them. This may also be true for Clitellata, in which dorsal roots have hitherto not been found. At the posterior end, the outgrowing fibers form five connectives, of which the two outermost of each side fuse in an anteroposterior direction, forming the main connectives. Outgrowing fibers of the stomatogastric nerve stumps soon form the stomatogastric ring, which subsequently is linked with the new brain via stomatogastric connectives.

Acetylation↗
PubMed1995

The polychaete Platynereis dumerilii (Audouin and Milne-Edwards): a new species for assessing the hazardous potential of chemicals in the marine environment.

The polychaete Platynereis dumerilii (Polychaeta: Nereidae) has been evaluated as a candidate bioassay species for marine ecotoxicity testing. The species conforms with many of the requirements of an ideal bioassay organism in that (i) it is amenable to laboratory culture, (ii) its relatively small size makes it convenient for handling and laboratory exposure studies, (iii) its diet is defined and can be controlled, (iv) it reproduces throughout the year and, using photoperiod manipulation, can be induced to spawn as required, and (v) it has a short life cycle (approximately 3 months at 20 degrees C) making it feasible to study the effects of xenobiotics on chronic endpoints such as reproduction. The components of the life history which have been examined to date include fertilization rate, embryo-larval development, and larval survival. These life stages were evaluated using the reference materials used in the 1991 International Paris Commission (PARCOM) Ring Test (namely, the biocides, Bioban P-1487 and Vantocil IB, and the widely used reference toxicant, 3,5-dichlorophenol). For fertilization rate, the median effect concentrations (1-h EC50 values) were 0.32 mg.liter-1 for Bioban P-1487, 1.92 [corrected] mg.liter-1 for 3,5-dichlorophenol, and 9.66 mg.liter-1 for Vantocil IB. For embryo-larval development, the median effect concentrations (48-h EC50 values) were 0.29 mg.liter-1 for Bioban P-1487, 2.13 mg.liter-1 for 3,5-dichlorophenol, and 4.81 mg.liter-1 for Vantocil IB. For larval survival, the median lethal concentrations (48-h LC50 values) were 0.32 mg.liter-1 for Bioban P-1487, 3.64 mg.liter-1 for 3,5-dichlorophenol, and 10.9 mg.liter-1 for Vantocil IB. These results (all based on nominal values) suggest that, for these reference materials, the early life stages of P. dumerilii are of similar sensitivity to other marine invertebrate species. Together with the amenability of this species to laboratory culture, these data suggest that P. dumerilii has significant potential for use in marine ecotoxicity testing.

Animals↗
PubMed1980

Rudimentary cilia in muscle cells of annelids and echinoderms.

Rudimentary cilia have been observed in muscle cells lining the tube feet of Ophioderma brevispinum (Ophiuroidea) and in muscle cells of the body wall and parapodial glands of Owena fusiformis (Polychaeta). A diplosomal basal body is associated with each cilium. Striated rootlets are absent. This is the first report on rudimentary cilia in muscle cells of an echinoderm and an annelid.

Animals↗
PubMed1999

Localization of a visual Gq protein in the photoreceptors of a polychaete, Perinereis brevicirris (Annelida).

Heterotrimeric GTP-binding proteins (G proteins) play an important role in phototransduction. The presence of G-protein subclasses has been reported in photoreceptive membranes, e.g., the Gi subgroup (transducin) in vertebrate rods, and the Gq subgroup in the eyes of the Arthropoda and the Mollusca. We examined the immunoreactivity and distribution of a Gq homologue in the cerebral ocelli of Perinereis brevicirris (Polychaeta, Annelida) using an anti-GqC antibody raised against a conserved sequence at the C-terminal of the alpha-subunit of Gq (Gq-alpha). The anti-GqC antibody labeled a 48-kDa band on the Western blot of proteins from the Perinereis ocelli. The anti-GtC antibody, which is raised against the C-terminal sequence of bovine transducin alpha-subunit (Gt-alpha), did not cross-react to the ocellar proteins of Perinereis. The rhabdomeric layers of the anterior and posterior ocelli were strongly labeled by anti-GqC on light-microscopic immunohistology. Immunoelectron microscopy showed that the Gq molecules were specifically localized in the photoreceptive membrane of the rhabdomeric microvilli. These results suggest that the Gq protein plays a role in the phototransduction of the Perinereis ocelli.

Amino Acid Sequence↗
PubMed1990

Polypeptides related to mammalian procholecystokinin in the brain of an invertebrate, a marine worm, Nereis diversicolor: evidence from in ovo translation of mRNA.

Total mRNA extracted from brain of a sea worm Nereis diversicolor (Annelida, Polychaeta) were injected into Xenopus oocytes. The in ovo-translated polypeptides were analyzed through electrophoresis of immunoprecipitated products or Western blotting techniques. Some of these polypeptides cross-reacted antibodies elaborated against three mammalian (human and rat) procholecystokinin (pro-CCK) sequences. Polypeptides of 15, 64, and 70 kDa were determined, but two families of less obvious products, whose molecular masses were between 27-34 kDa and 46-60 kDa, appeared. Furthermore, the Western blotting technique also showed a cross-reaction between some of the polypeptides (64 and 70 kDa) extracted from brains and the antibodies used. From this work, evidence is given of the presence of epitopes shared by cellular polypeptides extracted from the brain, in ovo-translated products and mammalian pro-CCK. Furthermore, these data suggest the existence of a CCK precursor in the brain of N. diversicolor.

Animals↗
PubMed1992

Some polypeptides in the nervous system of the marine worm, Nereis diversicolor, are related to the sodium influx stimulating peptide of the pulmonate freshwater snail, Lymnaea stagnalis.

Total mRNA, extracted from brain of the marine worm, Nereis diversicolor (Annelida, Polychaeta), was translated either in vitro using a rabbit reticulocyte lysate or in ovo (Xenopus laevis oocyte). The synthesized polypeptides were analyzed by electrophoresis and Western blotting techniques using polyclonal antisera raised against three peptides: sodium influx stimulating peptide (SISP) sequences 10-19 and 67-76 and a monoclonal antibody raised against purified native SISP (1-77) of Lymnaea stagnalis. Among the products translated in vitro, three polypeptides of 80, 72, and 64 kDa were recognized by the anti-SISP (10-19) polyclonal antiserum and by the monoclonal antiserum, but not by anti-SISP (67-76). Some of the in ovo translated products showed almost identical immunoreactivity to both the anti-SISP (10-19) and the monoclonal antibody. These polypeptides have molecular masses of 80, 72, and 43 kDa. No polypeptides were recognized by anti-SISP (67-76). Western blotting analysis of brain extracts revealed a number of proteins that reacted with the antiserum raised against SISP (10-19) and the monoclonal antiserum. Several perikarya of brain ganglionic nuclei and ventral nerve cord were immunoreactive to anti-SISP (10-19). The monoclonal antiserum gave similar results, although with a less intense immunoreaction. The infracerebral region was also stained, suggesting that the immunoreactive material is released as a true neurohormone into the hemolymph. The largest polypeptides, in particular those translated from brain mRNA, could be neuropeptide precursors containing a SISP-related sequence.

Animals↗
PubMed1992

Conservative system for dosage-dependent modulation of translational fidelity in eukaryotes.

Variations in dosage of some genes can alter the level of translational fidelity. The Saccharomyces cerevisiae genes that act as dosage-dependent suppressors and/or modulators of suppression, are the following: some tRNA genes (for example, tRNA(Gln)) inducing readthrough by mispairing; genes coding for either translational elongation factor or other proteins taking part in translation; and some genes of unknown function. We suggest that the SUP35 protein is a factor which may play a major role in balance-dependent regulation of translational fidelity. Homologues of this genes have been identified in other yeast genera (Pichia), green algae (Chlamydomonas) and various animals including man. No homologies have been found in the polychaeta (Nereis) or in insects (Drosophila). Rates of evolution differ for two separate parts of the genes; the N-terminal part, which is important for ambiguous translation in Saccharomyces, is markedly variable in the organisms tested. However, the C-terminal part which is required for yeast viability has a common origin but a separate evolution from that of the EF-Tu protein family.

Animals↗
PubMed2006

Effects of estuarine sediment contamination on feeding and on key physiological functions of the polychaete Hediste diversicolor: Laboratory and in situ assays.

This study aimed at integrating postexposure feeding and some biochemical parameters in the responses of the estuarine polychaeta, Hediste diversicolor, to controlled laboratory exposure conditions and to in situ exposures scenario of sediment contamination. Since H. diversicolor feeding may be considered as a major rate-limiting step in the processing of detritus in European estuaries, a reduction in feeding activity may have implications not only at the individual and population level of the species but also in detritus processing and in organic matter decomposition rates at the ecosystem level. The biochemical parameters were chosen as indicators of four key physiological functions: neurotransmission, metabolic condition, detoxification processes and antioxidant defences. The Mira and Sado estuaries, located in the Southwest coast of Portugal and classified as undisturbed and impacted, respectively, were selected as sites for this study. A significant depression in H. diversicolor postexposure feeding (from 30 to 70%) was consistently detected in all impacted sediments, supporting the sensitivity and responsiveness of feeding as a sublethal toxicity endpoint. Alongside with a reduced energy intake, an increased rate of organisms' anaerobic metabolism, as evidenced by an enhancement of lactate dehydrogenase activity (up to 1.5-fold), suggested a rapid need of additional energy to ameliorate chemical stress. Moreover, oxidative stress was shown to be an important mechanism of toxicity of the impacted sediments in H. diversicolor, as evidenced by a marked reduction in the glutathione redox status (up to 6.5-fold) and an increase in lipid peroxides levels (up to 2.3-fold) in organisms exposed to the most impacted sediments. Results of the in situ assay, conducted to assess the ecological relevance of sediment laboratory toxicity estimates and their application to make valid field extrapolations, revealed a lack of agreement in the response of catalase in organisms exposed to moderate impacted sediments. Our results support the utility of integrating responses at individual and sub-individual level to evaluate potential toxicant-induced changes in key physiological functions of H. diversicolor and to interpret their potential ecological consequences.

Animals↗
PubMed2026

Diverse methyl-end desaturases enable LC-PUFA biosynthesis across Annelida.

Recent studies have demonstrated that annelids possess front-end desaturases and elongases involved in the biosynthesis of physiologically important long-chain polyunsaturated fatty acids (LC-PUFA). However, methyl-end desaturases (ωx desaturases), enzymes that play a central role in the de novo biosynthesis of polyunsaturated fatty acids and their subsequent conversion into LC-PUFA, have so far been reported in only a limited number of polychaete species. To advance our understanding of ωx desaturases across the phylum Annelida, this study performed a comprehensive molecular and functional characterisation of these enzymes in the major annelid taxa Polychaeta, Clitellata and Sipuncula, encompassing species from diverse taxonomic groups and ecological niches. A total of 110 ωx desaturase sequences were retrieved from available genomes and transcriptomes. The number of ωx desaturase genes varied among species, ranging from zero to four copies. Phylogenetic analyses revealed that annelid ωx desaturases are classified into two major clades, designated Cluster A and Cluster B. Analyses of histidine-box motifs and exon-intron organisation revealed conserved patterns within each clade. Functional characterisation of ωx desaturases from Eisenia fetida (Clitellata) and Sipunculus nudus (Sipuncula), together with previously published data from polychaetes, demonstrated that annelids generally possess two ωx desaturases, one with Δ12 desaturase activity and another with ω3 desaturase activity. Collectively, these results demonstrate that annelids possess a phylogenetically and functionally diverse ωx desaturase repertoire that underpins their LC-PUFA biosynthetic capacity and may reflect adaptation to different ecological and nutritional environments.

Animals↗
PubMed2001

Species-specific elimination of polychlorinated biphenyls in estuarine animals and its impact on residue patterns.

Elimination kinetics of tetra-, penta- and hexachlorobiphenyls (IUPAC Nos. 44, 52, 87, 95, 101, 153) were investigated by laboratory experiments in three species of different phyla: Nereis diversicolor (Polychaeta), Palaemon longirostris (Crustacea) and Platichthys flesus (Pisces). Half-lives were species-specific and structure-dependent. Palaemon longirostris eliminated all components fastest. N. diversicolor was faster than Platichthys flesus except for components 95 and 153. Contrary to the fish species, the two invertebrates contained significant amounts of polar transformation products of No. 52, which had been applied as 14C labelled. Therefore, the faster elimination by Palaemon longirostris and N. diversicolor was assumed to be generally due to increased biotransformation. Elimination was in accordance with polychlorinated biphenyl (PCB) residue patterns obtained from field samples of the species. Congeners with vicinal H atoms in m,p positions were under-represented in Palaemon longirostris and so were congeners with > or = 7 Cl in N. diversicolor, while the PCB residue pattern in Platichthys flesus was similar to that of Clophen A60. By comparing percentages of the experimental congeners in sigma PCB and their elimination half-lives in the three species, it was revealed that residue patterns were also influenced by species-dependent uptake, e.g. feeding habits. Extractable organic matter-based sigma PCB levels increased with trophic levels of the three species.

Animals↗
PubMed2003

Effects of zinc exposure on the polychaete Dinophilus gyrociliatus: a life-table response experiment.

A life-table response experiment (LTRE) was performed in order to study the effects of enhanced zinc on the survival, fecundity and demographic indices of Dinophilus gyrociliatus (Polychaeta). A control group and three treated cohorts kept in artificial seawater enriched with nominal concentrations of zinc at 0.25, 0.50 and 1.00 microg Zn/ml, respectively, were considered. Zinc marginally affected survival but had a strong impact on the reproduction of D. gyrociliatus. Zinc enrichment had no effect on age at maturity, whereas it induced a slight increase in fecundity during the early reproductive phases at 0.50 and 1.00 microg Zn/ml, and a sharp decrease in fecundity from the 20th day of life at all levels of metal enrichment tested. Treated groups were characterised by a marked reduction of the net growth rate (R0) and a decrease in generation time (T) with respect to the control groups, but no effect on life expectancy (e0) or on population growth rates (lambda) was observed. R0 and lambda, which are the most commonly used indices of fitness, were not equally susceptible to zinc. Lambda appears less sensitive to stress induced by metal enrichment with respect to R0 and other life history traits like age-specific fecundity. D. gyrociliatus appears to be an appropriate bioindicator species in LTRE to assess the consequences of environmental heavy metals on individual life-history and population dynamics.

Animals↗
PubMed2001

Pterospora floridiensis, a new species of acephaline gregarine (Apicomplexa) from the maldanid polychaete Axiothella mucosa in St. Andrew Bay, Florida.

Pterospora floridiensis, a new species of acephaline gregarine from the body cavity of the bamboo worm Axiothella mucosa (Polychaeta: Maldanidae), is described. The gamont stage is distinctive and possesses a central cytoplasmic mass and two elongate trunks that bifurcate repeatedly and comprise approximately 60% of the total cell length. The gamont averages 198 (50-545) x 71 (25-180) microm (N= 45, 43) from the tip of the trunks to the anterior (the junctional site with the other gamont in syzygy). Gametocysts average 402 (297-545) x 304 (149-495) microm (N = 37). The oöcysts measure 22.5 (20.5-23.5) x 8.3 (7.0-10.0) microm (N = 30) and possess an internal capsule (average length = 13.9 microm, N = 30) containing the sporozoites and aliform wings on the epispore.

Animals↗
PubMed2001

Photonic engineering. Aphrodite's iridescence.

The most intense colours displayed in nature result from either multilayer reflectors or linear diffraction gratings. Here we investigate the spectacular iridescence of a spine (notoseta) from the sea mouse Aphrodita sp. (Polychaeta: Aphroditidae). The spine normally appears to be deep red in colour, but when light is incident perpendicular to the axis of the spine, different colours are seen as stripes running parallel to the axis of the spine; over a range of smaller incident angles, the complete visible spectrum is reflected with a reflectivity of 100% to the human eye. The simple structure responsible for this effect is a remarkable example of photonic engineering by a living organism.

Animals↗
PubMed2005

Sharp genetic break between Atlantic and English Channel populations of the polychaete Pectinaria koreni, along the North coast of France.

This study uses enzymatic and mitochondrial genes to infer the relative importance of historical processes and contemporary hydrodynamic features on the observed patterns of genetic structure in subdivided populations of Pectinaria koreni (Polychaeta: Pectinariidae) along the coasts of Brittany and the English Channel. Nucleotide sequence variation of a 603-bp fragment of the mtDNA cytochrome oxidase subunit I gene revealed a surprisingly deep phylogeographic break of about 16% divergence separating the Brittany and Channel populations, which coincides with a biogeographic boundary along the western coast of Brittany. Deep sequence divergence with fixed haplotype differences and the inversion of allele frequencies at two enzyme loci suggests the occurrence of potential cryptic or sibling species of P. koreni. The two clades showed opposite features. Channel populations exhibited bimodal match-mismatch curves due to two highly divergent haplotypes occurring at high frequencies and no overall heterozygote deficiencies at enzyme loci, suggesting respectively, a historic secondary contact between two differentiated populations followed by contemporary panmixia. On the contrary, Brittany populations displayed unimodal curves with low nucleotide diversity and highly significant heterozygote deficiencies, probably reminiscent of a recent population expansion and recolonisation of Brittany with contemporary admixture of divergent populations.

Animals↗
PubMed1976

Isolation, characterization and oxygen equilibrium of an extracellular haemoglobin from Eunice aphroditois (Passas).

The extracellular haemoglobin from the polychaeta,Eunice aphroditois, existed as a mixture of a heavy major component (so20, w = 56.96 +/- 0.125) and a light minor component (so20, w = 10.00 +/- 0.13S), the latter probably being a dissociation product of the former. The molecular weight of the purified heavier component, as detetermined by sedimentation equilibrium, was 3.44 x 10(6) +/- 0.04x10(6). The molecule had the electron-microscopic appearance typical of annelid haemoglobins, consisting of a stack of two hexagonal plates, with dimensions 26.32 +/- 0.27 nm across the flats of the hexagon, height of stack 17.86 +/- 0.34 nm. The sugar composition is reported, and the isoelectric point was approx. pH7.8. The haem content was 2.31 +/- 0.01%, corresponding to a minimal mol.wt. of 26700. Detergent/gel electrophoresis revealed the presence of at least four bands with molecular weights in the range 14600-31000. Five N-terminal amino acids were found. In addition to the 10S component, which co-existed with the 57S component at all pH values in the range 4.0-10.6, at low pH values (less than pH.5.0) A 16S and a 1.9 S component were found. The absorption and circular-dichroic spectra are reported, and the alpha-helical content, calculated from the ellipticity at 222 nm, was about 40%. The molecule bound O2 co-operatively with a maximum value of the Hill coefficient, h, of 3.9. Over the pH range 7.0-8.0 there was a positive Bohr effect.

Amino Acids↗