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PubMed2004

Identification of two Nereis virens (Annelida: Polychaeta) cytochromes P450 and induction by xenobiotics.

Cytochrome P450 (CYP) enzyme catalysed metabolism of xenobiotics such as polycyclic aromatic hydrocarbons (PAHs) are known to occur in polychaetes. Yet specific polychaete CYP enzymes have so far not been identified. Here, we report two partial CYP cDNA sequences, both of 453 bp, characterised from Nereis virens. These are the first CYP sequences reported in annelids. The deduced amino acid sequences both share highest identities to mammalian CYP4F enzymes (61% and 58%), indicating membership of the CYP4 family (accordingly, referred to as CYP41 and CYP42, respectively). The CYP42 gene expression was significantly higher in vehicle controls (corn oil) compared to untreated controls. Clofibrate increased the expression of the CYP42 genes. The induction by clofibrate and corn oil indicates regulatory similarities to vertebrate CYP4 enzymes, which are primarily involved in the metabolism of endogenous compounds such as fatty acids. Crude oil and benz(a)anthracene significantly induced CYP42 gene expression 2.6-fold, and because CYP enzymes often are induced by their own substrates, this induction may indicate involvement of N. virens CYP4 enzymes in the detoxification of environmental contaminants such as PAHs. The present study demonstrates that these N. virens CYP genes are transcriptionally inducible, and suggests that N. virens CYP4 enzymes may be involved in the metabolism of both exogenous and endogenous compounds.

Amino Acid Sequence↗
PubMedDate not supplied

Oxidative stress in Laeonereis acuta (Polychaeta, Nereididae): environmental and seasonal effects.

Laeonereis acuta was seasonally collected in an industrially polluted site (P) and in an unpolluted site (UP) at the Patos Lagoon estuary (southern Brazil). Glutathione S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT) activity (U/mg protein) was determined in five groups of worms from each site. Metallothionein (MT - mol GSH/g ww) and lipid peroxides content (LPO - nmoles of cumene hydroperoxide/g ww) were also measured. Annual mean values for CAT (UP=3.7+/-0.3; P=5.7+/-0.6), GST (UP=0.034+/-0.003; P=0.045+/-0.004) and MT (UP=0.15+/-0.02; P=0.23+/-0.03) were higher (p<0.05) in worms from the P site. In autumn, CAT activity was higher (p<0.05) in worms from the P site (7.6 +/- 1.3) than in those from the UP site (3.6 +/- 0.4). In summer, MT concentration was higher in worms from the P site (0.37 +/- 0.03) than in those from the UP site (0.19 +/- 0.01). No significant difference (p>0.05) in the LPO content was observed in worms from the different sites or collected in different seasons. These results indicate that worms from the polluted site showed higher antioxidant responses than those from the unpolluted site, sufficient to prevent oxidative damage in terms of LPO.

Analysis of Variance↗
PubMed2006

Bacterial accumulation by Branchiomma luctuosum (Annelida: Polychaeta): a tool for biomonitoring marine systems and restoring polluted waters.

In this study, we examined the bacterial accumulation in the filter feeder polychaete Branchiomma luctuosumGrube (Sabellidae). Analyses were performed on worm homogenates from 'unstarved' and 'starved' individuals, and seawater from the same sampling site (Gulf of Taranto, Western Mediterranean, Italy). Densities of culturable heterotrophic bacteria (22 degrees C), total culturable bacteria at 37 degrees C and halophilic vibrios at 22 and 35 degrees C were measured on Marine Agar 2216, Plate Count Agar and thiosulphate-citrate-bile-salt-agar (TCBS) plus 2% NaCl, respectively. Total and faecal coliforms as well as faecal streptococci were determined by the Most Probable Number method. Results showed that B. luctuosum is able to accumulate all the considered six microbiological groups with a higher efficiency for autochthonous bacteria. The analysis also indicated that bacterial groups differ in their resistance to digestion by B. luctuosum. Our data suggest the potential role of B. luctuosum as an useful bioindicator to assess low levels of microbiological water pollution as well as bioremediator of microbial polluted waters.

Animals↗
PubMed2005

Phylogeny of Aphroditiformia (Polychaeta) based on molecular and morphological data.

The phylogeny of Aphroditiformia, benthic polychaetes carrying dorsal elytra, is assessed from nuclear 18S rDNA, mitochondrial cytochrome c oxidase subunit I (COI), and 31 morphological characters. Two non-elytrabearing taxa, Palmyra and Pisione, are included to assess their relationship to the elytrabearers. The data are analysed both separately and combined, with parsimony, maximum likelihood and Bayesian analyses. In total, 19 terminal taxa are examined, including 12 elytrabearing taxa from all scale-worm groups, Palmyra, Pisione, and five outgroup taxa. The results show that Palmyra and Pisione are nested within Aphroditiformia. Palmyra is sister to Aphrodita, and both Pisione and Pholoe are positioned within Sigalionidae, suggesting that both family names Pisionidae and Pholoidae should be treated as junior synonyms of Sigalionidae.

Animals↗
PubMed2002

Genotoxic, cytotoxic and ontogenetic effects of tri-n-butyltin on the marine worm, Platynereis dumerilii (Polychaeta: Nereidae).

The genotoxic, cytotoxic and ontogenetic (embryo-larval) or developmental effects of tri-n-butyltin (TBT), were investigated in Platynereis dumerilii. Following the determination of maximum tolerated dose with regard to ontogenetic effects and mortality, early life stages of P. dumerilii were exposed to a range of TBT concentrations. Subsequently, the embryo-larvae were analysed for evidence of genotoxicity and cytotoxicity. Genotoxicity was assessed using cytogenetic endpoints that included the frequency of sister chromatid exchanges and chromosomal aberrations from metaphase spreads. Cytotoxicity was evaluated by determining the proliferative rate index of the growing embryo-larval cells using 5-bromodeoxyuridine labelling of the chromosomes or fluorescence plus Giemsa staining technique. TBT-exposed embryo-larvae of P. dumerilii exhibited sensitivity similar to that of other invertebrates, indicating that P. dumerilii is a suitable ecotoxicity test species. The results also suggested dose-dependent effects for genotoxic and cytotoxic end points in relation to TBT exposure. The present study highlights the need to elucidate the relative importance of direct genotoxic and indirect effects through production of genotoxic hormonal derivatives.

Animals↗
PubMed2002

Numerical chromosomal aberrations in the early life-history stages of a marine tubeworm, Pomatoceros lamarckii (Polychaeta: Serpulidae).

The marine environment provides a sink for a host of toxic chemicals, directly or inadvertently, released as a result of human activity. Some of these chemicals have the potential to act as aneugens, substances that cause numerical chromosomal aberrations (NCAs). NCAs are one of the most important classes of genetic abnormality and are implicated in a variety of deleterious effects, including premature ageing, birth defects and cancer. Clearly, any increase in the incidence of these agents in the marine environment poses a risk to the indigenous biota and its predators, including man. In this paper, we describe our recent success with applying the fluorescence in situ hybridisation technique (FISH) to detect NCAs in the interphase cell nuclei of Pomatoceros lamarckii, a common rocky shore invertebrate. Given the lack of requirement for any detailed cytogenetic knowledge, the method holds considerable promise for laboratory and field studies in general, and should lend itself to automated screening protocols, where large numbers of cells can be screened rapidly, for example, using a flow cytometer. When exposed either under acute or chronic (viz. adult) exposure conditions, colchicine and di-butylphthalate (DBP) (a widely-used plasticiser), two recognised aneugens, induced significant increases in the levels of NCAs, in the dose range 1 x 10(-6)-5 x 10(-6) M, in both four to eight cell embryo stages and 24 h-old larvae. In keeping with the severely debilitating effects of this class of agent, an inverse correlation was observed between the induced levels of NCAs and larval fitness based on the results of a standard 48-h larval bioassay.

Animals↗
PubMed1997

Acetylcholinesterase in Spirographis spallanzanii (Polychaeta: Sedentaria): presence of two dimeric membrane-bound forms.

In the annelid polychaete Spirographis spallanzanii two acetylcholinesterases, named DS and HSDS, were detected. They differ in relative amount, membrane anchoring and pharmacological properties. Studies with inhibitors evidenced complete inhibition of both acetylcholinesterases by 10(-3) M eserine and different sensitivities for edrophonium or procainamide. Both enzymes, sensitive to BW284c51, were unaffected by iso-OMPA; at variance, only the HSDS form underwent excess-substrate inhibition. DS and HSDS enzymes were solubilized by homogenization in a low-salt or high-salt-Triton X-100 buffer and then purified by affinity chromatography on edrophonium- or procainamide-Sepharose column respectively. According to gel-filtration chromatography, sedimentation analysis and SDS-PAGE, the least represented (30%) DS form is a G2 amphiphilic globular dimer (124-130 kDa, 6.0-7.0S) with S-S linked monomers (66 kDa). Phosphatidylinositol anchors give cell membrane insertion, self-aggregation and detergent (Triton X-100, Brij 97) interaction. The prevailing (70%) HSDS acetylcholinesterase is once again a G2 form similar to DS enzyme in its molecular size (117-125 kDa), sedimentation coefficient (6.0S) of the native form and presence of S-S linked subunits (66 kDa). However, it is likely attached to the cell membrane by involvement of strong electrostatic interactions. DS acetylcholinesterase displays moderate active site specificity with differently sized substrates. The HSDS form is inactive on butyrylthiocholine. DS and HSDS forms show a comparable catalytic efficiency (kcat/K(m)) approaching that of other invertebrate enzymes. The results suggest that DS and HSDS enzymes, likely encoded by distinct genes, are both functional in cholinergic synapses.

Acetylcholinesterase↗
PubMed2002

The abdominal-B-like gene expression during larval development of Nereis virens (polychaeta).

We have studied the posterior Hox gene Nvi-Post1 expression in the early development of the polychaete Nereis virens. This is the first evidence of the posterior group Hox genes expression during the larval development of a Lophotrochozoan. The expression begins in the trochophore hyposphere at the prospective sites of larval parapodia. As the larva develops the expression weakens and finally becomes undetectable in the nectochaete stage and juvenile worm. The Nvi-Post1 expression appears to be important for larval, but not postlarval development.

Animals↗
PubMed2002

Progenesis in Eunicida ("Polychaeta," Annelida)--separate evolutionary events? Evidence from molecular data.

The Eunicida are a well-defined annelid taxon currently comprising Dorvilleidae, Lumbrineridae, Eunicidae, Onuphidae, and Hartmanniellidae. Especially the Dorvilleidae include several species of small body size and apparently simple organisation, resembling larvae and juveniles of larger species. One hypothesis to explain the evolution of such species is progenesis. By this criterion the Dinophilidae were included in this group as well. Although their overall similarity suggests monophyly, parallel evolution of such progenetic taxa cannot be excluded. To infer the phylogeny of Eunicida and their presumed relationship to Dinophilidae and progenetic dorvilleids, 18S rDNA sequences from various Dinophilidae, Dorvilleidae, and members of other Eunicida were determined. The data matrix were extended by adding sequences from several annelid and molluscan species and analysed with maximum-parsimony, distance, and maximum-likelihood algorithms. Highly significant bootstrap-values support monophyly of the Dinophilidae, of a clade enclosing the Eunicidae and the Onuphidae, and of a dorvilleid group comprising six species including the presumed progenetic Parapodrilus psammophilus. The position of the Dinophilidae remains unresolved, so that their inclusion within the Eunicida can neither be corroborated nor rejected. However, a constraint monophyly of Dinophilidae and P. psammophilus is rejected by several tests, substantiating the hypothesis of separate progenetic evolutionary events. Furthermore, the molecular data indicate polyphyly of the Dorvilleidae.

Animals↗
PubMed1997

Evaluation of the genotoxicity of municipal sewage effluent using the marine worm Platynereis dumerilii (Polychaeta: Nereidae).

Samples of settled (primary) effluent were collected from a municipal sewage treatment works at Newton Abbot, Devon, UK, a site which discharges primary effluent via long sea pipeline into the English Channel (minimum of 200-fold initial dilution). Sewage samples were collected during the period February-April 1995 and were analysed for standard physico-chemical parameters (ammonia, chemical oxygen demand, conductivity, non-purgeable organic carbon and settled solids). Samples were also tested for cytotoxicity, genotoxicity, and for developmental effects in the embryo-larval stages of the marine worm, Platynereis dumerilii. Exposure to sewage concentrations of > or = 10% (v/v) in seawater at 20 +/- 1 degrees C led to a marked reduction in normal embryo-larval development (7 h EC50 values from 10% to 18% v/v, n = 5). There was also evidence of a simultaneous delay in the cell cycle progression (as determined by sister chromatid differential staining) following embryo-larval exposures to sewage concentrations of > or = 10% (v/v). Following the calculation of the Maximum Tolerated Dose (MTD), based on cytotoxic and developmental effects, cells from the same embryo-larvae were analysed for chromosomal aberrations (CAs). Results were consistent for all samples tested, demonstrating the absence of cytogenetic damage following the in vivo exposure of polychaete embryo-larvae to settled sewage.

Animals↗
PubMed1995

Long-lasting exocytosis and massive structural reorganisation in the egg periphery during cortical reaction in Platynereis dumerilii (Annelida, Polychaeta).

The course of the cortical reaction in the Platynereis dumerilii egg is described from live observation and from sectioned fixed material and is found to differ in several aspects from the course of cortical reactions in better-known systems. Cortical granules are unusually numerous. They are discharged by exocytosis during a period of about 25 min following fertilisation (18 degrees C). Most of the surplus membrane material brought to the egg surface by exocytosis is set free into the perivitelline space. Swelling of egg jelly precursor secreted by cortical granule exocytosis may be causal for the detachment of the vitelline envelope from the egg cell surface which, however, remains attached punctately to the vitelline envelope by about 30,000 microvilli. Under the strain of the distending vitelline envelope, the bases of the microvilli move and line up, pulling the cell surface into a network of ridges. The grooves in between the ridges are the sites of exocytoses. Cytochalasin B, generally destabilising actin filaments, induces rupture of the microvilli and exaggerated distension of the vitelline envelope during the cortical reaction. In a final phase of the cortical reaction the vitelline envelope wrinkles and falls back onto the egg cell surface, the microvilli shorten and the egg cell transiently becomes deformed by local contractions. The cortical reaction in the nereid egg is discussed as a process of distortion and reorganisation of the egg cortex and plasmalemma. The abundance of cortical granules accommodating egg jelly precursor in the Platynereis oocyte is attributed to the mode of so-called diffuse oogenesis characteristic of nereids, i.e. of differentiation of oocytes freely suspended in the coelomic fluid. In nereids, egg jelly therefore forms after fertilisation as opposed to ovulation.

Animals↗