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PubMed1984

Purification and characterization of oocyte vitellin from Perinereis cultrifera (polychaete annelid).

Vitellin was identified and purified from submature oocytes of Perinereis cultrifera by concanavalin-A - Sepharose and Ultrogel AcA 34 column chromatography. The yolk protein was defined as a glycolipoprotein with a relative molecular mass of 380000. Upon dissociation by sodium dodecyl sulphate, vitellin was shown to release five polypeptide subunits which ranged in relative molecular mass from 98000-16000. The purified vitellin was further characterized by amino acid analysis and its lipid and carbohydrate contents. The molecule contained about 5% carbohydrate and 16% lipid. Antiserum prepared against vitellin was shown to react with a component from the coelomic fluid of maturing females. Thus, it was suggested that in nereid annelids, considered phylogenetically and morphologically primitive, oocyte differentiation might depend upon the incorporation of a vitellogenin as in insects and many oviparous vertebrates.

Amino Acids↗
PubMed1984

Study of the conversion of GDP-mannose into GDP-fucose in Nereids: a biochemical marker of oocyte maturation.

Homogenates of Perinereis cultrifera oocytes were found to transform GDP-D-mannose into another sugar nucleotide. Ultraviolet absorption spectra, chromatographic behaviour, gas-liquid chromatography coupled to mass spectrometry analysis revealed that GDP-D-mannose had been converted into GDP-L-fucose. This conversion is a multi-step reaction as proved by the involvement of two intermediates identified as GDP-4-oxo-6-deoxy-D-mannose and GDP-4-oxo-6-deoxy-L-galactose, this latter being reduced by NADPH to give GDP-L-fucose. It is shown that the enzymatic activities responsible for the conversion of GDP-D-mannose into GDP-L-fucose is recovered only in oocytes and is not present in the other coelomic cells (i.e. coelomocytes). More interesting is the fact that maximum activity is recovered at a well defined stage of the hormone-controlled oogenesis. Thus, this enzymatic system appears as a biochemical marker of the oocyte maturation in P. cultrifera.

Animals↗
PubMed1984

The amino acid sequence of sarcoplasmic calcium-binding protein obtained from sandworm, Perinereis vancaurica tetradentata.

The amino acid sequence of sarcoplasmic calcium-binding protein obtained from sandworm (Perinereis vancaurica tetradentata) has been determined. It is composed of 174 amino acid residues, its N-terminus is blocked by an acetyl group and the relative molecular mass is calculated to be 19556. From the results of amino acid sequence, it has three EF-hand-type calcium-binding sites. The positions of calcium-binding sites could be easily predicted by its hydropathy profile. Amino acid sequence homology between sarcoplasmic calcium-binding protein from different species is between 14-20%, thus it is not such a conservative protein.

Amino Acid Sequence↗
PubMed1986

Structuring of H1 histone. Evidence of high-affinity binding sites for phosphate ions.

Circular dichroism studies show that low concentrations of phosphate ions induce folding of the H1 histones. Sulfate and perchlorate anions have effects similar to phosphate indicating the presence on H1 histones of binding sites with high affinity for ions with tetrahedral geometry. In fact, the structuring efficiency of different ions, as determined by the midpoint value of the effect/concentration curve, is 0.05 M for NaCl, 0.005 M for NaClO4, 0.001 M for sodium phosphate and 0.0003 M for sodium sulfate on H1 histone from Chaetopterus variopedatus sperm chromatin. Phosphate shows similar folding efficiency also on calf thymus and on sea-urchin sperm H1 histones. The effect of phosphate ions on the H1 molecule is observed also by differential absorption spectroscopy in the region of absorption of amino acid side-chains. Binding studies by gel filtration chromatography on Sephadex columns show that phosphate binding occurs in the presence of structuring concentrations of sodium chloride. About 9 ATP molecules bind to H1 histones derived from non-active cell chromatins while only 3.5 ATP molecules bind to H1 derived from active somatic chromatins. The fluorescence of the tyrosine residues of Chaetopterus sperm H1 is enhanced by chloride ions and heavily quenched by phosphate ions in correlation with structuring of the molecule, demonstrating direct interactions between tyrosine residues and phosphate ions. The defined and limited number of phosphate groups bound per histone molecule, the high affinity of the interaction and the effect on the structure of the histone suggest the participation of phosphate groups in the binding of H1 histones to DNA.

Animals↗
PubMed1987

NMR studies of the heme pocket conformations of monomeric hemoglobins from Glycera dibranchiata. Implications for ligand binding.

Two-dimensional 1H-NMR methods have been used to assign side-chain resonances for the tryptophan residues and for several amino acids located in the heme pockets of the carbon monoxide complexes of the major monomeric hemoglobins from Glycera dibranchiata. The NMR spectra reveal a high degree of conservation of the heme pocket structure in the different hemoglobins. However some conformational differences are evident and residues at positions B10 and G8 on the distal side of the heme pocket are not conserved. From the present NMR studies it appears that the monomeric G. dibranchiata hemoglobin examined by X-ray crystallography [Padlan, E. A. & Love, W. (1974) J. Biol. Chem. 249, 4067-4078] corresponds to HbC. Except that the orientation of the heme in solution is the reverse of that reported in the crystal structure, there is a close correspondence between the heme pocket structure in the crystal and in solution. The proximal histidine coordination geometry is almost identical in the CO complexes of the three monomeric hemoglobins studied. Distal residues are strongly implicated in determining the observed kinetic differences in ligand binding reactions. In particular, steric crowding of the ligand binding site in hemoglobin A is probably a major factor in the slower kinetics of this component.

Amino Acid Sequence↗
PubMed1987

Structural consequences of heme isomerism in monomeric hemoglobins from Glycera dibranchiata.

Two-dimensional 1H-NMR methods have been used to assign heme and amino acid proton resonances in both isomeric states of the carbon monoxide complexes of two Glycera dibranchiata monomeric hemoglobins, HbA and HbB. For each hemoglobin, there are small differences in heme pocket structure in the two isomeric forms. The largest structural perturbations associated with heme isomerism involve residues close to pyrrole rings I and II. The positions relative to the heme of phenylalanine CD1 and the proximal histidine ligand are almost unaffected by heme isomerism. These residues probably play a key role in determining the location of the heme within the heme pocket.

Animals↗
PubMed1988

A 15,000-Mr protein proteolytically derived from vitellogenin within oocyte of Perinereis cultrifera (polychaete annelid). Identification, purification and partial characterization.

It has been shown previously in our laboratory that, in Perinereis cultrifera, the four mature vitellin subunits (Mr 98,000, 22,000, 20,000, 16,000) are proteolytically derived within the oocyte from a single extraoocytic precursor, vitellogenin, with an apparent Mr (176,000) higher by 20,000 than the sum of the Mr of the four end products. In this report, it is shown that a 15,000-Mr protein, designated as P15, not only accumulates in maturing oocytes but also originates from outside these cells similarly to vitellin. Moreover in vivo labelling experiments indicate that the appearance of P15 occurs after vitellogenin enters the oocyte, concurrently with the appearance of the lower-Mr fragments characteristic of vitellin. From these data, it is concluded that P15 most likely represents a vitellogenin-derived protein which is generated within the oocytes during the transformation of vitellogenin into vitellin. This conclusion is further supported by the additional finding that P15 immunologically cross-reacts with vitellogenin but not with mature vitellin. P15 has been purified to homogeneity from the soluble protein fraction of submature oocytes and partially characterized. The 15,000-Mr protein exists in a monomeric form with a pI of about 7.7. Unlike vitellin, P15 does not contain significant amounts of lipid or carbohydrate and has a low absorbance at 280 nm. The amino acid composition of the purified protein is also presented.

Amino Acids↗
PubMed1990

Organization and complete nucleotide sequence of the core-histone-gene cluster of the annelid Platynereis dumerilii.

The arrangement of the core-histone genes, their transcriptional polarity and their nucleotide sequences have been determined for the polychaete annelid Platynereis dumerili. A clone containing the core-histone genes was isolated from a annelid genomic library constructed in the EMBL-4 phage vector, using a trout H3 genomic probe. This clone was found to contain two and a half repeats of a 6-kbp EcoRV fragment that contained one copy of each of the core-histone genes. The clusters are tandemly arrayed in the genome and the gene order within the core-histone cluster does not vary. Absolutely no differences were found in the nucleotide sequences comprising the same part of two adjacent clusters (bases -225 to 2776 and bases 5821 to 8825). The number of copies of the cluster appeared to be high: approximately 660 copies/diploid cell, as also observed in sea urchins and amphibians. There are also some additional subtypes of histone gene organization: multimers of tandemly arrayed genes and isolated genes; these are present at a much lower copy number (an average of 40-50 copies/diploid genome). Two mRNAs (for H2B and H3) are transcribed from one DNA strand and the two other histone mRNAs (for H2A and H4) from the other strand as is the case for some insects and certain vertebrates. No H1-coding sequence has been found in the completely sequenced four-membered cluster. The organization of histone genes in P. dumerilii is similar to the clustering found in Caenorhabditis elegans but in this nematode worm several different types of organization are observed with a low copy number for each.

Amino Acid Sequence↗
PubMed1990

In vivo 13C-NMR studies on the metabolism of the lugworm Arenicola marina.

13C-NMR natural-abundance spectra of specimens of Arenicola marina obtained, showed seasonal changes in the concentration of some metabolites, with the osmolite alanine as well as triacylglyceride storage compounds present at high concentrations. Glycogen was sometimes only barely detectable due to the low natural abundance level of 13C. Glycogenic metabolism of the lugworm A. marina was studied in vivo by 13C-NMR spectroscopy using 13C-labelled glucose. During recovery from a hypoxic period [1-13C]glucose was incorporated into glycogen. [1-13C]Glucose was injected 5 h after the end of hypoxia to guarantee sufficient and reliable 13C labelling of glycogen. An earlier injection of [1-13C]glucose led to considerably diminished incorporation of 13C-labelled glucosyl units into glycogen, probably due to the consumption of the available glucose as fuel for ATP production. No scrambling of 13C into the C6 position of glycogen was observed, indicating a lack of gluconeogenic activity. 13C was also incorporated into the C3 positions of alanine and alanopine. To assign correctly this last 13C-NMR resonance, the compound was synthesized biochemically. No labelling of glycogen was observed when [3-13C]alanine was injected into the coelomic cavity with similar incubation conditions being used. The 13C of [1-13C]glucose, incorporated into glycogen, showed a very low turnover rate in normoxic lugworms as shown by two 13C(1H)-NMR spectra, one obtained 48 h after the other. On the other hand, in hypoxia lugworms the signal due to 13C-labelled glycogen decreased very rapidly proving a high turnover rate. The disappearance of 13C from glycogen during the first 24 h of hypoxia indicates that the last glycosyl units to be synthesized are the first to be utilized. Lugworms were quite sensitive to the 1H-decoupling field used for obtaining the 13C(1H)-NMR spectra, especially at 11.7 T. Using bi-level composite-pulse decoupling and long relaxation delays, no tissue damage or stress-dependent phosphagen mobilization, as judged by 31P-NMR spectroscopy, was observed.

Alanine↗
PubMed1991

Isolation and characterization of authentic Phe-Met-Arg-Phe-NH2 and the novel Phe-Thr-Arg-Phe-NH2 peptide from Nereis diversicolor.

Immunocytochemical studies have shown that peptides like Phe-Met-Arg-Phe-NH2 (FMRFamide) are widely distributed throughout the nervous system of three Nereidae. In Nereis diversicolor we have isolated these peptides from an extract of total worms by affinity chromatography and two steps of reversed-phase high-performance liquid chromatography. The sequences of the purified peptides have been determined by amino acid sequencing and on the basis of their reactivity with an anti-FMRFamide serum specific for the determinant Arg-Phe-NH2. Two primary structures have been established: Phe-Thr-Arg-Phe-NH2 (FTRFamide) and PHe-Met-Arg-Phe-NH2 (FMRFamide). Furthermore a methionine sulfoxide derivative of the FMRFamide has been identified. We have synthesized the FTRFamide peptide and in all cases, the native peptides were indistinguishable from the synthetic counterparts. The structure of the two native peptides and of the methionyl sulfoxide derivate have been confirmed by fast-atom-bombardment and tandem mass spectrometry.

Amino Acid Sequence↗
PubMed1996

Mitochondrial sulfide oxidation in Arenicola marina. Evidence for alternative electron pathways.

Sulfide is oxidized in the mitochondria of the lugworm Arenicola marina. Mitochondrial sulfide oxidation is coupled with oxygen consumption and with an equimolar production of thiosulfate [Völkel, S. & Grieshaber, M. K. (1994) Mar. Biol. 118, 137-147]. Mitochondrial respiration in the presence of malate (or succinate) and ADP but without sulfide could be completely inhibited by rotenone, antimycin, cyanide, and sulfide. Only 40% inhibition was achieved by salicylhydroxamic acid. Sulfide oxidation (with sulfide as the only substrate) was fully inhibited by antimycin and by salicylhydroxamic acid but not by rotenone or sulfide. Moreover, sulfide oxidation was 3-4-fold less sensitive to cyanide as compared to normal respiration. The data indicate that sulfide oxidation in A. marina is linked to the respiratory electron transport chain. We suggest that electrons from sulfide enter the respiratory chain via ubiquinone or at the ubiquinol-cytochrome-c oxidoreductase. At sulfide concentrations higher than 10 microM, the cytochrome-c oxidase is blocked and electrons from sulfide are transferred to oxygen via an alternative terminal oxidase.

Animals↗
PubMed1997

Metabolic response in Arenicola marina to limiting oxygen as reflected in the 1H-NMR oxymyoglobin signal.

Many intertidal animals can endure prolonged periods of environmental stress and have developed strategies to preserve a functioning energy state in the cell. Recent 1H/31P-NMR techniques have allowed investigators to monitor directly mammalian tissue metabolism in vivo. In particular, the signals of myoglobin (Mb) offer a unique opportunity to explore the intracellular oxygen-partial-pressure [p(O2)] interaction in Arenicola marina, a standard model to study hypoxia tolerance in invertebrates. The present study reveals that the 1H-NMR MbO2 signal at -2.9 ppm is detectable in tissue and reflects directly the oxygenated state. As the p(O2) declines, MbO2 saturation and oxygen consumption decrease. However, phosphotaurocyamine concentration remains unaltered until the MbO2 saturation falls below 33%. The extracellular to intracellular p(O2) gradient appears substantial. The study establishes the 1H-NMR technique as an approach to measure the intracellular p(O2) with an oxygenated state marker and presents the interrelationship between oxygen and the metabolic adaptation during hypoxic stress.

Anaerobiosis↗
PubMed1997

Quaternary structure of the extracellular haemoglobin of the lugworm Arenicola marina: a multi-angle-laser-light-scattering and electrospray-ionisation-mass-spectrometry analysis.

To elucidate the quaternary structure of the extracellular haemoglobin (Hb) of the marine polychaete Arenicola marina (lugworm) it was subjected to multi-angle laser-light scattering (MALLS) and to electrospray-ionisation mass spectrometry (ESI-MS). It was also subjected to SDS/PAGE analysis for comparative purposes. MALLS analysis gave a molecular mass of 3648 +/- 24 kDa and a gyration radius of 11.3 +/- 1.7 nm. Maximum entropy analysis of the multiply charged electrospray spectra of the native, dehaemed, reduced and carbamidomethylated Hb forms, provided its complete polypeptide chain and subunit composition. We found, in the reduced condition, eight globin chains of molecular masses 15952.5 Da (a1), 15974.8 Da (a2), 15920.9 Da (b1), 16020.1 Da (b2), 16036.2 Da (b3), 16664.8 Da (c), 16983.2 Da (d1), 17033.1 Da (d2) and two linker chains L1, 25174.1 Da, and L2, 26829.7 Da. In the native Hb, chains b, c, d occur as five disulphide-bonded trimer subunits T with masses of 49560.4 Da (T1), 49613.9 Da (T2), 49658.6 Da (T3), 49706.8 Da (T4), 49724.5 Da (T5). Linker chains L1 and L2 occur as one disulphide-bonded homodimer 2L1 (D1) of 50323.1 Da and one disulphide-bonded heterodimer L1-L2 (D2) of 51 981.5 Da. Polypeptide chains a and d possess one free cysteine residue and chains d possess an unusual total of five cysteine residues. Semi-quantitative analysis of ESI-MS data allowed us to propose the following model for the one-twelfth protomer: [(3a1)(3a2)2T] (T corresponding to either T3, T4 or T5). From electron micrograph data T1 and T2 are probably located at the centre of the molecule as mentioned in previous studies. The Hb would thus be composed of 198 polypeptide chains with 156 globin chains and 42 linker chains, each twelfth being in contact with 3.5 linker subunits, providing a total mass of 3682 kDa including haems in agreement with the experimental molecular mass determined by MALLS. From ESI-MS relative intensities and the model proposed above, the globin/linker ratio gave 0.71:0.29 and 0.73:0.27, respectively. The estimation of haem content by pyridine haemochromogen and by cyanmethaemoglobin (HiCN) methods also support the globin chain number provided by ESI-MS.

Animals↗
PubMed2004

CDK1/cyclin B regulation during oocyte maturation in two closely related lugworm species, Arenicola marina and Arenicola defodiens.

The molecular mechanisms underlying oocyte maturation in the annelid polychaetes Arenicola marina and Arenicola defodiens were investigated. In both species, a hitherto unidentified hormone triggers synchronous and rapid transition from prophase to metaphase, a maturation process which can be easily reproduced in vitro. Activation of a roscovitine- and olomoucine-sensitive M-phase-specific histone, H1 kinase, occurs during oocyte maturation. Using affinity chromatography on immobilized p9CKShs1, we purified CDK1 and cyclin B from oocyte extracts prepared from both phases and both species. In prophase, CDK1 is present both as an inactive, but Thr161-phosphorylated monomer, and as an inactive (Tyr15-phosphorylated) heterodimer with cyclin B. Prophase to metaphase transition is associated with complete tyrosine dephosphorylation of the cyclin B-associated CDK1, with phosphorylation of cyclin B, and with dramatic activation of the kinase activity of the CDK1/cyclin B complex. We propose that Arenicola oocytes may provide an ideal model system to investigate the acquisition of the ability of oocytes to be fertilized that occurs as oocyte shift from prophase to metaphase, an important physiological event, probably regulated by active CDK1/cyclin B.

Animals↗
PubMed2004

Early steps in microbial colonization processes at deep-sea hydrothermal vents.

A pluri-disciplinary in situ colonization experiment was performed to study early stages of colonization in deep-sea vent Alvinella spp. worm habitats. Four colonization devices were deployed onto Alvinella spp. colonies of different chimneys of the East-Pacific Rise (EPR 13 degrees N), for two different periods: a short (less than a week) and a longer one (3 weeks). Video imagery and monitoring of the thermal and physico-chemical conditions were performed during the colonization experiments. Numerous microorganisms bearing specialized adhesion-appendages and/or high amounts of polymeric extracellular matrix were observed on devices, which may efficiently contribute to the colonization of new surfaces. The microbial cohorts preceding and accompanying Alvinella spp. settlement were identified. In all cases, Archaea could not be detected and the microbial mats were essentially composed of e-Proteobacteria. Within this group, one phylotype (AlviH2) was found to dominate the libraries of three colonization devices. Dominance of e-Proteobacteria in the libraries may reflect the wide physiological variety encountered within this group or an adaptability of these microorganisms towards their changing environment. Bacteria affiliated to the Cytophaga-Flavobacterium-Bacteroides group or to the e-Proteobacteria, that grow either chemo-organoheterotrophically by fermentation or chemolithoautotrophically with H2 as an electron donor and S degrees /S2O32- or NO3- as a terminal electron acceptor, were isolated from one of the microbial mat formed in 20 days.

Animals↗
PubMed2005

Evolutionary innovation: a bone-eating marine symbiosis.

Symbiotic associations between microbes and invertebrates have resulted in some of the most unusual physiological and morphological adaptations that have evolved in the animal world. We document a new symbiosis between marine polychaetes of the genus Osedax and members of the bacterial group Oceanospirillales, known for heterotrophic degradation of complex organic compounds. These organisms were discovered living on the carcass of a grey whale at 2891 m depth in Monterey Canyon, off the coast of California. The mouthless and gutless worms are unique in their morphological specializations used to obtain nutrition from decomposing mammalian bones. Adult worms possess elaborate posterior root-like extensions that invade whale bone and contain bacteriocytes that house intracellular symbionts. Stable isotopes and fatty acid analyses suggest that these unusual endosymbionts are likely responsible for the nutrition of this locally abundant and reproductively prolific deep-sea worm.

Animals↗
PubMedDate not supplied

Growth patterns during segmentation in the two polychaete annelids, Capitella sp. I and Hydroides elegans: comparisons at distinct life history stages.

Many animals generate new body segments sequentially from a posterior growth zone, and this is generally thought to be the case for the annelids. Most annelids, including polychaetes, have an indirect life cycle and generate their earliest segments during larval life. We have characterized the nature of the growth zone in two polychaetes, Hydroides elegans and Capitella sp. I, during both larval and juvenile stages of segment formation by examining cell division patterns with 5-bromo-2'-deoxyuridine incorporation. Cell division patterns show commonalities between the two species, even though they have distinct body plans and life history characteristics. In both polychaetes, larval segments arise from a field of dividing cells located in lateral regions of the body, rather than from a localized posterior growth zone. Circumferential expansion of the forming segmental tissue is particularly pronounced in Capitella sp. I. Post-metamorphic segments, in contrast, originate from a classical posterior growth zone, with the exception of four posterior thoracic segments of H. elegans, which appear to arise from an area in the middle of the body, indicating plasticity of segment-generating mechanisms present in different annelid life histories. The distinct nature of larval versus juvenile growth zones in H. elegans and Capitella sp. I raises the question of the mechanistic relationship between these two growth zones. The results of this study increase our understanding of the cellular origins of segments in annelids, and serve as a basis for interpretation of molecular expression patterns associated with segment formation in polychaetes.

Animals↗
PubMedDate not supplied

Molting polychaete jaws--ecdysozoans are not the only molting animals.

Jaw shedding and replacement of Diopatra aciculata (Onuphidae, Eunicida), by the same process as arthropod molting, involving apolysis and ecdysis, is described here. These observations suggest that molting has either evolved convergently in eunicidan polychaetes and ecdysozoans or it was present in the last ecdysozoan/lophotrochozoan common ancestor and thus may not represent a synapomorphy of the ecdysozoans.

Animals↗