Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ANNELIDA”

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 307 records · Page 17Linked to original sources
PubMed1982

The histochemistry of the clitellum of Tubifex tubifex (annelida: oligochaeta).

The histochemistry of the clitellar glands of Tubiflex tubiflex is reported, together with the ultrastructure of mature secretion units. The distribution and ultrastructure of mucous and granule cells are consistent with published accounts of tubificid citella, thus indicating an absence of intrageneric variation. Mucous cells contain homogenous electron lucent globules which are rich in neutral and acidic mucopolysaccharides and are non-reactive with techniques designed to reveal protein. Type I cells possess structured granules composed of tyrosine-containing basic protein and carboxylated acid mucopolysaccharides. The granules of type II cells are heterogenous and contain several 0.3--0.7 micrometer inclusions of acidic protein with identifiable tyrosine, tryptophan and cystine. The inclusions occur within a matrix composed of neutral mucopolysaccharides and carboxymucin. Type III cell granules possess 0.2--0.5 micrometer inclusions within an electron dense matrix and are rich in neutral and carboxylated acid mucopolysaccharides and basic protein containing tyrosine, tryptophane and cystine. Clitelar carboxymucins are characterized by their stability to beta-glucoronidase, hyaluronidase, neurominidase and acid hydrolysis. A pyridine-extractable lipid moiety within the clitellar secretions was not detected. The results are discussed in relation to cell function during cocoon deposition and, comparatively, with those documented for other oligochaete families.

Animals↗
PubMed1983

Organization of actin filaments during polar body formation in eggs of Tubifex (Annelida, Oligochaeta).

Microfilaments in the Tubifex egg undergoing polar body formation can be decorated with heavy meromyosin (HMM). Since the HMM-arrowheads on filaments are dissociated by rinsing with ATP, they are identified as actin filaments. From metaphase through telophase of the second meiotic division, actin filaments are present in the cortex and in the meiotic apparatus. Consistent with the previous observations [26, 27], cortical filaments show stage-specific localization patterns. At metaphase the thick filamentous layer is localized at the animal pole, that means the region overlying the peripheral aster of the meiotic apparatus; filaments are organized in a meshwork. Upon the onset of anaphase chromosome movement, the filament meshwork mostly disappears and the remaining filaments are found to be solitary. Surrounding the animal pole region, but not extending over the animal pole, more and more filaments reappear during anaphase. As the polar body forms at the animal pole, filaments surrounding its base are organized into small bundles which are oriented randomly. By early telophase these filaments come to run circumferentially in the cortical layer (i.e. they form the contractile ring) engirding the cleavage furrow which develops at the base of the polar body. In the remaining cortex, filaments run along the surface and are oriented randomly. At all stages, adjacent filaments are often found to have opposite polarities; in favorable sections, HMM-decorated filaments appear to attach to the oolemma. The mechanism underlying the filament alignment of the contractile ring is discussed in relation to formation of the polar body.

Actins↗
PubMed1984

Fine structure of the epidermal cuticle of some Brazilian earthworms (Oligochaeta: Annelida).

Electron microscopic techniques were adopted to study the epidermal cuticle of 4 species of brazilian earthworms. Basically this structure consists of collagenous fibers arranged in alternate layers and embedded in an amorphous and fibrillar matrix. Of characteristics, the ellipsoidal projections of the cuticle of P. hawayana were found to be enclosed between 2 parallel layers, where each layer consists of 2 electron dense lines, separated by a space filled with an electron dense material.

Animals↗
PubMed1981

[Purification of the brain hormone of Nereis diversicolor and Perinereis cultrifera (Annelida:Polichaeta) by high-pressure liquid chromatography (HPLC)].

Five thousand brains inhibiting gametogenesis in Nereis diversicolor and Perinereis cultrifera were extracted with cold methanol, giving a micromolecular fraction containing the whole of the inhibitory activity of the brains. This micromolecular fraction, fractionated (i) on Sephadex G 25 fine and (ii) on Sephadex G 25 superfine, gave an inhibitory peak (P 5) in organ culture. Fraction P 5, purified by high-pressure liquid chromatography, showed an area with the same biological inhibitory activity as the blank brains.

Animals↗
PubMed1978

[Evolution of muscles in Nereidae (Annelida polycheta) during epitoky. I and II. Atokous and epitokous longitudinal fibres (author's transl)].

The longitudinal fibres from atokous Nereis belong to the double oblique striation type. Their thick myofilaments, paramyosinic (about 145 A periodicity) are arranged in an hexagonal lattice, well preserved after a glycerol treatment. 9 to 13 thin filaments form an orbit around one thick filament (ratio: 6-7/1). The contraction occurs in two processes: a sliding filament mechanism, and a shearing mechanism. This second mechanism consists in a parallel shifting of thick filaments, arising their overlap and decreasing their degree of stagger; it induces the increase of the myofibrillar (A-bands) oblique angle from 10-12 degrees in isolated glycerol extracted fibres, to 35-38 degrees in the same fibres after contraction by the action of ATP-solution. The longitudinal fibres from epitokous Nereis or Heteronereis are characterized also by a double oblique striation. The structural aspects of the contraction are similar to these ones occurring in atokous fibres. Nevertheless, the epitokous fibres are different from the atokous fibres by many characteristic points. Their thick myofilaments, with an hexagonous array, are thinner and shorter than these ones from atokous fibres. The contractile material is only present in the cortex. The axis of epitokous fibres is filled with numerous mitochondria, between them numerous glycogen particles have been synthetised. The sarcoplasm of the fiber's coelomic edge is often devoided of myofilaments but it is full of mitochondria and glycogen granules. The nucleus, with a voluminous nucleolus, is no more placed in the fibre axis, but in a lateral sarcoplasm containing ribosomes, glycogen and mitochondria. The important transformations of longitudinal fibres are discussed in connection with the Heteronereis locomotor behaviour, very different from this one of the atokus Nereis. Particularly, it seems that the abundance of glycogen and mitochondria in epitokous muscles allows a high contraction frequency. The decrease of the diameter and length from the thick filaments should be set in relation with the augmentation of the contraction's swiftness. These results are very similar to these ones occuring in Syllidae with the stolonization mode of reproduction. The Syllis stolonial fibres present the same characteristics than the Nereis epitokous fibres.

Animals↗
PubMed1994

Ultrastructural analysis of the intestinal content of earthworm Lumbricus rubellus Hoffm. (Annelida, Lumbricidae).

Gut content sections of the earthworm Lumbricus rubellus, the surrounding soil and casts were studied using transmission electron microscopy. Bacteria, actinomycetes, dead fungi and empty mycelia were observed to occur throughout the gut content. In the foregut and midgut of worms, some bacteria were found to be partially or totally lysed and digested, although were protected by polysaccharides and clay particles. Not only inactive resting forms (spores) or cells protected by capsular polysaccharides and clay particles and/or by plant cellular remnants, but also separate metabolically active and dividing cells were recovered especially in hindgut. The formation of new bacterial microaggregates was noticed in the posterior intestine as well.

Animals↗
PubMed1994

First North American record of the marine leech Notostomum laeve (Annelida: Hirudinea).

The Arctic marine leech Notostomum laeve is reported for the first time from North America. A single, small specimen was collected in April 1990 on the external surface of 1 of 30 Greenland halibut Reinhardtius hippoglossoides from Cumberland Sound, Baffin Island, Northwest Territories, Canada. Total length of the specimen including suckers is 41 mm; maximum body width is 1.8 mm. The species is easily identified by the unusual suckers. The caudal sucker is divided into 2 lateral halves that appear to close somewhat like a clam shell; the oral sucker is very thick and muscular with a row of small, hard teeth-like papillae around the outer margin. On the basis of this report from northern Canada, N. laeve probably has a circumpolar distribution in the Arctic Ocean.

Animals↗
PubMed1975

[Caudal regeneration in the presence of a supplemental nerve cord grafted dorsally in Nereis pelagica L. (Annelida Polychaeta)].

In Nereis pelagica, the existence of an additional nerve cord grafted dorsally induces the differentiation on the dorsal face of the regenerate of a supernumerary area with ventral characteristics, provided the grafted nerve cord regenerates posteriorly. These results led us to think that the dorse-ventral differentiation of the body wall doesn't depend upon the nature of the stump region but is controlled by the nerve cord regenerating in the area.

Animals↗
PubMed1976

[Elemental chemical composition of Scolelepis fuliginosa (Annelida, Polychaeta): effect of growth conditions].

The elemental chemical composition of Scolelepis fuliginosa was comparatively with specimens reared in laboratory and from a natural population. The carbon-nitrogen ratio variations show a certain homogeneity of composition in juveniles and young sexed and a sexual dimorphism in adults. C/N ratio of the laboratory specimens is not significantly different from that of the ones from natural surroundings. But, when these are kept several weeks in captivity, this ratio considerably decreases.

Age Factors↗
PubMed1976

[Demonstration of the dorsal character of the body wall of the aneurogenic regenerate of Nereis pelagica L. (Annelida, Polychaeta)].

In Nereis pelagica, graft of dorsal or ventral parts of a regenerate edified in the absence of nerve cord (=aneurogenic) on the ventral or dorsal face of a normal host demonstrates a completely dorsal nature of the body wall in these special regenerates. The results indicate that the nerve cord is involved in setting up regenerate dorso-ventral polarity by fixing differentiation of the ventral characters in the area located near by; without it , only the dorsal character is expressed.

Animals↗
PubMed1995

[Analysis of protein nutrient reserves of the clitellum and cocoon albumin in Eisenia fetida Sav (Annelida Oligochaeta). Demonstration of a glycolipoprotein comparable to vitellogenin].

In the clitella of Eisenia fetida, the amount of total proteins decreased dramatically during puberty. In contrast, the level of soluble proteins increased during the same period. In the cocoons, the increase of total proteins and soluble proteins corresponded to the development of the embryos. Among the soluble proteins of the mature clitellum, 3 major proteins (A, B and C) were separated by electrophoresis: A, glycolipoproteinic (molecular weight = 450 kDa), B, glycoproteic (MW = 350 kDa) and C, also glycoproteinic (MW = 150 kDa). Only A was present in the cocoons during all the stages of development. Although this protein is not incorporated in the oocyte, it has the same characteristics as a typical vitellogenin. After denaturation of the soluble proteins, 4 polypeptides were obtained. Two of them, a and c, are involved in the making of this 'vitellogenin'.

Albumins↗
PubMed1995

[Sugars and lipids of the clitellum and cocoon albumin in Eisenia fetida Sav (Annelida Oligochaeta)].

Biochemical methods were used to analyze the glucidic and lipidic components of the clitellar epithelium and the cocoon's albumen in Eisenia fetida. In the clitellum, the sugar concentration increased dramatically (about 5-fold) during differentiation. The assays showed increases in several monosaccharides during puberty. In addition, glucose was prominent in immature clitella, whereas mannose was the main sugar in the mature ones. About 50% of the dry weight of recently deposited cocoons was carbohydrates. The sugar concentration decreased in the albumen as hatching approached. The amount of total lipids in the clitellum increased during maturation. The levels of neutral lipids, however varied very little. Phospholipids began at low levels at the beginning of differentiation, and increased dramatically thereafter. The amount of fatty acids in the clitellar epithelium reached a maximum during the submature stage. Large amounts of fatty acids were stored in the cocoon. Palmitic, stearic, oleic and vaccenic acids were preponderant in both the clitellum and cocoon.

Albumins↗
PubMed1995

The effect of sublethal lead exposure on the ultrastructure and on the distribution of acid phosphatase activity in chloragocytes of earthworms (Annelida, Oligochaeta).

Laboratory experiments were conducted to study the effects of the exposure to a sublethal concentration (500 p.p.m.) of lead on the ultrastructure and acid phosphatase compartmentalization of the chloragogenous tissue of earthworms, Eisenia foetida. For the cytochemical demonstration of acid phosphatase activity, lead and cerium were used as capturing agents. In both cases there was a change in the compartmentalization of acid phosphatase, the enzyme activity being localized within the chloragosomes in controls, but distributed throughout the cytosol in treated animals. In addition, acid phosphatase activity increased following lead exposure. At the ultrastructural level, disruption of the chloragosomal membranes, an increase in chloragosomal fusion processes and vesiculation of the cytoplasm were evident. Moreover, an enhanced release of chloragosomes to the extracellular space was found in lead-exposed worms.

Acid Phosphatase↗
PubMed2002

Are Echiura derived from a segmented ancestor? Immunohistochemical analysis of the nervous system in developmental stages of Bonellia viridis.

Despite several unquestionably homologous characters with Annelida, the Echiura have generally been considered to form a distinct taxon due to apparent lack of segmentation: neither in the body cavity nor in any other structures of the adult animals have clear signs of a metameric organization been observed. However, it must be considered that this lack of segmentation could represent a secondary condition and that Echiura are derived from segmented ancestors. An immunohistochemical analysis visualized with confocal laser-scanning microscopy (cLSM) shows the development of serially repeated units in the nervous system of Bonellia viridis. This organization corresponds to the metameric ganglia typical of Annelida. Antibodies against the neurotransmitters serotonin (5-hydroxytryptamine) and FMRFamide label distinct subsets of neurons. Their perikarya are arranged in discrete repetitive units in the ventral nerve cord of different larval stages. Labeling of neurotubuli using antibodies against different tubulin isoforms provides additional support for the metameric character of the nervous system. Contrary to previous descriptions, the peripheral nerves extending from the ventral nerve cord into the body wall musculature are paired and are evenly distributed; their arrangement corresponds to that of the serotoninergic perikarya. Morphological and neurochemical differentiation of the nervous system clearly proceeds from anterior to posterior, indicating the occurrence of a posterior growth zone. The serial ganglionic organization of the nervous system of Articulata is generally regarded as having evolved in conjunction with repetitive muscular units, in particular with the formation of typical annelid segments. Therefore, these results are interpreted as an indication that Echiura are derived from segmented ancestors and thus support the systematic inclusion of the Echiura within the Annelida.

Animals↗
PubMedDate not supplied

[The distribution of Blastocystis according to different systematic groups of hosts].

After the carried out examination of different animals belonging to four phyla, Annelida, Mollusca, Arthropoda, and Chordata, the blastocysts were detected within three phyla, Annelida, Arthropoda, and Chordata. Within the phylum Annelida the blastocysts were found in Hirudinea, within the phylum Arthropoda--in Insecta, within the phylum Chordata--in Amphibia, Reptilia, Aves, and Mammalia.

Amphibians↗