Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Polychaeta”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
PubMed2005

Antioxidant enzymes and tissue regeneration in Eurythoe complanata (Polychaeta: Amphinomidae) exposed to used vehicle crankcase oil.

Polychaetes, Eurythoe complanata, from the Gulf of Cariaco,Venezuela, were exposed to 0.3, 1.6, and 3.3% water-soluble fraction (WSF) of used crankcase oil during 15 and 21 days. The antioxidant enzymes glutathione peroxidase (GPX), glutathione reductase (GR), catalase (CAT), and glutathione-S-transferase (GST) were assayed in the body wall tissue. Furthermore, after chemical exposure, the polychaetes were cut into equal halves; then wound healing and the number of regenerated body segments were recorded periodically. GST activity was affected by all the experimental treatments, with activity increasing with WSF concentrations. GPx activity was altered for the contamination period. GR and CAT activities rose in response to increasing WSF concentrations, and were higher for long-term than for short-term exposures. The wound healing of the transected body regions was retarded by WSF exposure. WSF affected the tissue regeneration, which was almost abolished at 3.3% WSF. The exposure period did not affect the tissue-repairing responses. Alteration of GST in contaminated organisms suggested equivalent changes in detoxication of bioaccumulated organic contaminants. The variation of GR and CAT suggests induction of oxidative stress that could reduce the ability of WSF-exposed worms to repair damaged tissue.

Animals↗
PubMed1987

Cytochemical and biochemical characterization of neurosecretory material in the brain of an annelid, Ophryotrocha puerilis (Polychaeta).

In the brain of the protandric annelid Ophryotrocha, prominent axon terminals accumulate neurosecretory material in female-phase individuals. This material is not present in females after they have had social contact for 2 days and in males. After treatment with Formalin or glyoxylic acid, the axon terminals in isolated females are brightly fluorescent. The injection of reserpine into the coelomic cavity of such females prevents the development of fluorescence in the nerve endings. In an HPLC study of brains containing axon terminals filled with neurosecretory material, catecholamines were found to be present in large quantities. In specimens with empty axon terminals, the amount of catecholamines was significantly less. Thus the secretory material appears to contain catecholamines. The results presented suggest dopamine to be the major component of the neurosecretory material.

Animals↗
PubMed1978

Comparative ultrastructure of juvenile and adult nuchal organs of an annelid (Polychaeta: Opheliidae).

Opheliid nuchal organs are composed of ciliated cells, retractor muscles, and sensory cells. The perikarya of sensory cells are located in the posterior portion of the brain, and their distal processes extend along the body wall, as the nuchal nerve, and terminate just anterior to the ciliated region. The nuchal nerve of the juvenile is composed of 30-35 dendrites; the adult nuchal nerve has 35-40 dendrites. The ends of the sensory dendrites form sensory bulbs which are clustered around the olfactory chamber, and each bulb bears a modified cilium. Sensory cilia lose their axonemes and extend as microvillous-like structures into the olfactory chamber. Supportive cells delineate approximately the posterior and dorsal portions of the chamber with sensory bulbs forming the remaining ventral and anterior portions. On the lateral aspect of the chamber, cuticular matrix. The adult nuchal organ is larger than that of the juvenile, and the sensory portion of the olfactory chamber wall is expanded. Expansion of the sensory area is apparently the result of size increase in sensory bulbs and by intrusion of supportive cells between sensory bulbs.

Animals↗
PubMed1978

Anatomical and ultrastructural study of the pharyngeal bulb in Protodrilus (Polychaeta, Archiannelida) II. The stomodeal and its cuticle.

The epidermal and stomodeal cuticles of Protodrilus are described then compared. The thin epidermal cuticle, the thickness of which is about the same over all the body, is characterized both by the absence of fibrils in its deepest part and by the extension of epidermal microvilli above the cuticle. The stomodeal cuticle, the thickness of which is as variable as that of the epithelium, presents two layers of fibrils comparable to the collagen fibrils described in the cuticle of other Annelida, as well as a relatively diversified supramicrovillous coating. The anterior cuticular thickening or grating plate, is characterized by the length of the epithelial microvilli, the thickness of the cuticular matrix and the superficial cuticular zone with supramicrovillous denticles supported by an axis of fibrous bundles. In the stomodeal cuticle, the fibrillar material seems to give to the cuticle best resistance to deformation during the pharyngeal bulb contraction, while an especially elaborated supramicrovillous coating is found in regions most exposed to friction. These features contrast with the relative simplicity of the epidermal cuticle.

Animals↗
PubMed1979

Ultrastructural evidence for both autosynthetic and heterosynthetic yolk formation in the oocytes of an annelid (Phragmatopoma lapidosa: Polychaeta).

The ovaries of the reef-building polychaete Phragmatopoma lapidosa are attached to the genital blood vessels on the caudal surface of the intersegmental septa of the abdominal segments. Oogenesis is not synchronized and vitellogenesis occurs before the oocytes are released from the ovary into the coelomic cavity. A portion of each developing oocyte rests on the basal lamina of the genital blood vessel while the remaining surface of the oocyte is covered by follicle cells. Two morphologically distinct types of yolk are formed during vitellogenesis: Type I, which may be formed autosynthetically by the conjoined efforts of the rough ER and Golgi systems; and Type II, which is presumably formed heterosynthetically from endocytosis of yolk precursors from the genital blood vessel. Heterosynthetic production of yolk in an annelid has not been reported previously.

Animals↗
PubMed1982

Yolk formation in an annelid (Ophryotrocha puerilis, polychaeta).

The polychaete Ophryotrocha does not show a distinct breeding season. Egg masses are produced throughout the year (continuous breeder sensu Olive and Clark, 1978). A female specimen may contain up to three different generations of oocytes with oocyte growth and maturation in each batch being well synchronized. Oogenesis takes about 18 days from proliferation of the oogonia to mature eggs. In each segment pairs of sister cells interconnected by cytoplasmic bridges are located in outpocketings of the ventral mesentery which form the gonad wall. Presumptive oocytes and nurse cells are not easily distinguished at that time. Vitellogenesis is initiated while both oocytes and nurse cells are still in the ovary. Mitochondria, multivesicular bodies (transformed mitochondria?), dense bodies, preformed yolk bodies of smaller size and lipid droplets are probably passed through the cytoplasmic bridge from the nurse cell to the oocyte. Yolk formation includes different mechanisms and materials of different origin. Autosynthetic yolk formation predominates during the first intraovarial growth phase. After detachment of oocyte-nurse cell-complexes from the gonad pinocytotic activity of nurse cells and particularly oocytes, increases considerably. The existence of coated vesicles suggests that external sources of yolk precursors contribute to yolk formation. Prior to oocyte maturation the remnants of the nurse cell are incorporated by oocytes.

Animals↗
PubMed1983

Muscle dedifferentiation and contractile protein synthesis during post-traumatic regeneration by Owenia fusiformis (polychaeta annelid).

During anterior traumatic regeneration of the polychaete annelid Owenia fusiformis, we have observed by electron microscopy the dedifferentiation processes of muscle cells. The dedifferentiated cells are reminiscent of undifferentiated myoblasts. They form the blastema and redifferentiate in muscle cells in the regenerate. The in vivo and in vitro biochemical studies of the biosynthesis of contractile proteins, as markers of the terminal differentiation programme of the muscle cells, showed that gene expression correlated with the terminal differentiation programme (at last for muscle cells) seemed unaffected. It seems in fact that contractile protein synthesis is regulated partly at the translational level during traumatic regeneration in the invertebrate.

Amputation, Surgical↗
PubMed1986

Isolation of polypeptide chains with heme from the extracellular hemoglobin of Amphitrite ornata (Polychaeta, Annelida).

From the extracellular hemoglobin of Amphitrite ornata four constituent polypeptide chains containing heme and designated AI, AII, BI and BII according to the elution order were obtained by DE52-cellulose ion-exchange chromatography with dithiothreitol (DTT) as a reducing reagent. The NH2-terminal sequences for the chains are AI, Asp-Ser-Asn-Ala; AII, Glu-Tyr-Thr; BI, Asp-Phe-Asn-Thr; and BII, Asp-Ser-Glu. Each of the isolated chains showed spectra similar to those of vertebrate hemoglobins, and they bound oxygen reversibly. Acid urea polyacrylamide gel electrophoresis separated four bands, corresponding to the isolated chain, from the intact extracellular hemoglobin reduced with DTT. These results and our failure to detect an appreciable amount of non-heme protein suggest that the extracellular hemoglobin of A. ornata is composed of four polypeptide chains, each containing a heme.

Animals↗
PubMed2005

Regulation of vitellogenesis in Nereis virens (Annelida: Polychaeta): effect of estradiol-17beta on eleocytes.

In the marine polychaete Nereis virens, the yolk protein precursor vitellogenin (Vg) is synthesized in specialized coelomic cells (eleocytes) during oogenesis. This process was visualized by immunohistochemistry using antibodies raised against the yolk protein. Transversal sections from male and female worms confirmed that eleocytes from females but not from males produce Vg. In order to investigate the hormonal regulation of Vg synthesis, eleocytes were incubated in vitro with estradiol-17beta (E(2)) at a concentration of 1 microg/l for up to three days. A strong increase in Vg secretion was detected by ELISA in culture media of treated eleocytes from vitellogenic females. In contrast, no response to the hormonal treatment was detectable in immature worms. Our results showed that Vg synthesis is under a complex regulation, which involves endocrine factors like estrogens. The role of E(2) in vitellogenesis of N. virens rather resembles the situation found in vertebrate than the one in insects.

Animals↗
PubMed2006

Stress protein response in two sibling species of Marenzelleria (Polychaeta: Spionidae): is there an influence of acclimation salinity?

The induction and synthesis of stress proteins in the polychaete sibling species Marenzelleria viridis and M. neglecta was investigated at two different acclimation salinities (10 and 25 ppt). By in vitro labeling of dissected metameres with (35)S-methionine/cysteine and electrophoretic separation, four size classes of heat shock proteins (Hsps) were detected corresponding to 86, 78, 75 and 27 kDa. All Hsps, with the exception of Hsp86, represent a complex of multiple isoforms. The sibling species differed in three aspects of their heat shock response: (1) the induction temperature for Hsp75 synthesis was 25 degrees C and 30 degrees C in M. viridis and M. neglecta, respectively; (2) the relative level of synthesis of Hsp75 was higher in M. viridis; (3) the heat shock response was inactivated at a higher temperature in M. neglecta compared to M. viridis. The results showed that acclimation salinity had no explicit effect on Hsp synthesis in either species and that M. viridis was thermally more sensitive than its sibling species. We proposed that temperature, alone or in combination with other abiotic factors, plays a far greater role in the biogeographic distribution in Marenzelleria spp. than has been estimated so far.

Acclimatization↗