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At least 217 records · Page 12Linked to original sources
PubMed1976

[Stability of determination and differentiation of the somatic sexual characters in Nereis pelagica L. (Annelida polychaeta)].

Experiments of regeneration in situ or on grafts were carried out to test the stability of determination of the somatic sexual characters in Nereis pelagica. The sexual characters of the parapodial cirri (male and female swellings, male crenellations) are always expressed on stump or regenerate according to the genetic sex. Supernumary parapodia which developed at the site of junction of the heterologous faces of host and graft of opposite sexes, might have the characters of either sex; this result can be interpreted by supposing that a supernumary parapodium is derived from tissues of either host or graft, of the corresponding sex. Conversely, the pygidial papillae, which normally occur only on the heteronereid male, will appear on regenerating female pygidia, triggered to transform to the heteronereid condition naturally or by decerebration, with a frequency depending on the age of the regenerate, the length of the regenerate, and the genital condition of both the stump and the regenerate. It is concluded that the presence of the papillae is not a sex-specific character, but that their development is normally inhibited in the maturing female.

Animals↗
PubMed2003

Determination of lipid peroxides in invertebrates tissues using the Fe(III) xylenol orange complex formation.

Reactive oxygen species (ROS) are subproducts of the oxidative metabolism known to initiate chain reactions with polyunsaturated fatty acids that generate lipid peroxides (LPO). The objective of this work was to adapt the ferrous oxidation/xylenol orange (FOX) assay to measure LPO in invertebrate tissues i.e.: from polychaeta (Laeonereis acuta) and crab (Chasmagnathus granulata) species. Whole polychaetes were homogenized in methanol 100%, being determined the optimal sample volume and the time required for color development. It was tested five sample volumes (8-30 microl), following color development up to 215 min. Absorbance stabilization was observed after 90 min, being linearly related with sample volume. A similar procedure was adopted for crab tissues (anterior gills, posterior gills, and hepatopancreas). Differences between species and between organs of the same species were observed when analyzed nonspecific absorbance increments after adding the standard cumene hydroperoxide (CHP). In polychaeta and crab anterior gills tissue, absorbance increments were lower (21-25%) than samples without tissue extracts (blanks) that received CHP. In crab posterior gills and hepatopancreas, the nonspecific increment was almost negligible. Correction formulae are given to account for these differences and simplified protocols for each tissue and species are also included. Great differences in the lipid peroxides content was detected between worms (127.05 +/- 19.32 nmoles CHP/g of wet tissue) respect to anterior gills, posterior gills, and hepatopancreas from the crab species (52.65 +/- 3.59, 30.54 +/- 4.73, and 48.51 +/- 8.78 nmoles CHP/g of wet tissue, respectively).

Animals↗
PubMed2000

[Effect of hydrodynamics on the prey-predator relation. Experimental approach in a hydrodynamic channel].

Coupling effects of hydrodynamics and predatory activity of Nepthys hombergii (Savigny) (Polychaeta: Nephtyidae) on emigration of Hediste diversicolor (O.F. Müller) (Polychaeta: Nereidae) recruits were assessed in a flume. Experiments carried out in still water conditions and in the flume flow showed that predatory activity of N. hombergii is independent of the presence or the absence of flow and does not statistically influence the recruit emigration rate. It appears, however, that hydrodynamics is an inhibiting factor for the emigration of H. diversicolor which occurs in the absence of flow. The comparison of these results with literature data suggests that recruits could use hydrodynamics to leave an unsuitable habitat according to the species mobility range.

Animals↗
PubMed2006

Toxicants accumulation rates and effects in Mytilus trossulus and Nereis diversicolor exposed separately or together to cadmium and PAHs.

Two invertebrates, Mytilus trossulus and Nereis diversicolor, were exposed in aquaria to cadmium (50 microg L(-1)) and a mixture of three- to six-ring PAHs (2 microg L(-1) each) for 2 weeks. Organisms of two species were reared in separate tanks or together in the same one. Concentrations of Cd, PAHs and activities of selected biomarkers: catalase (CAT), glutathione S-transferase (GST) and acetylcholinesterase (AChE) were measured within 2 weeks of exposure. When reared separately, higher accumulation rates for cadmium were measured in mussels (16.4 microg day(-1) g(-1) d.w. lipid-free tissue) than in polychaeta (0.7 microg Cd g(-1) d.w day(-1)). When co-exposed, a difference in bioaccumulation was maintained but the accumulation rate in N. diversicolor increased to 1.0 microg Cd g(-1) d.w. day(-1) and decreased to 9.6 microg Cd g(-1) d.w. day(-1) in M. trossulus. On the contrary, faster bioaccumulation rates of PAHs were seen in polychaeta than in mussels when exposed separately (19.3 vs 4.5 microg PAHs day(-1) g(-1) lipid weight) than together (12.0 vs 3.1 microg PAHs g(-1) l.w. day(-1)). Substantial changes in the bioaccumulation patterns of the different M. trossulus organs were observed when both species were reared together. Biochemical responses indicated no effect of the accumulated contaminants on AChE, enhancement of CAT in both species and depletion of GST in Mytilus. The observed differences are discussed in terms of different bioavailability of contaminants, route of uptake and detoxification mechanism, under the two modes of exposure.

Animals↗