Patrick Scaps

Acetylcholinesterase activity of the polychaete Nereis diversicolor: effects of temperature and salinity

In order to estimate the potential use of the mean wholebody acetylcholinesterase (AChE) activity from the ragworm Nereis diversicolor for the biological assessment of pollution by anticholinesterase agents in estuarine areas, we measured the effects of the main abiotic factors (i.e. temperature and salinity) on AChE activity. We report here that AChE activity tends to decrease in individuals sampled in tanks at a salinity of 30 per thousand as temperature increases. No tendencies in the evolution of AChE activity were observed in individuals sampled in tanks at a salinity of 15 per thousand. In contrast, salinity seems to have a greater effect on AChE activity than temperature. At a temperature of 12 degrees C, a salinity of 30 per thousand provokes a significant transient increase of AChE 2 days after the beginning of the maintenance period compared with a salinity of 15 per thousand. The effects are short-term stress effects. We noticed only a transient increase of AChE activity between 2 days for individuals maintained in tanks at temperature of 20 degrees C and salinity of 15 and 30 per thousand, respectively, and 8 days for individuals maintained in tanks at salinity of 30 per thousand and at a temperature of 12 degrees C after the beginning of the maintenance period, confirming the more pronounced effect of salinity over temperature.

Cadmium and Lead Accumulation in the Earthworm Eisenia fetida (Savigny) and its Impact on Cholinesterase and Metabolic Pathway Enzyme Activity

Abstract The uptake of cadmium and lead was studied in the earthworm Eisenia fetida (Annelida: Oligochaeta) using an artificial soil exposure. Although cadmium and lead are bioconcentrated in Eisenia fetida tissue, bioaccumulation is not shown for concentrations below 100 ppm for lead, individuals eliminating as much metal as they ingest or the interactions between lead and organic matter in our substratum reduce the bioavailability of lead at low concentration. The cholinesterase activity was not inhibited when individuals were exposed for 8 weeks to either 8 or 80 ppm of cadmium or 100 or 2,000 ppm of lead. Results are different from those reported in another species Eisenia fetida andrei (= E. andrei) showing an inhibitory effect of lead on ChE activity; thus, differences in cholinesterase inhibition reflects the existence of two separate species. No effect of cadmium and lead on the activity of esterases, malate dehydrogenase, phosphoglucomutase and glutamate oxalate transferase was found in our experimental conditions, but we observed the disappearance of the fast moving band after electrophoretic separation for phosphoglucose isomerase.

Morphological and biochemical evidence that Perinereis cultrifera (Polychaeta: Nereididae) is a complex of species

Paragnath variation was examined in two populations of the epitokous form of the polychaete Perinereis cultrifera from the English Channel and the Algerian Mediterranean coast. Populations differ from each other in the mean number of paragnaths in groups I, II, III, V and VII–VIII, in the number of teeth per half jaw and in the morphology of paragnaths in the posterior belt. Individuals of the two populations studied share no common alleles at five loci involved in electrophoretic comparison. The general protein band patterns reveal 13 markers that discriminate between the Perinereis individuals. Congruence of all the reported results agree with the assignment that P. cultrifera is a complex of species, probably more than two.

Effects of an Ecdysteroid Analog (RH-0345) on the Ovarian and Testicular Components of Eupolybothrus nudicornis (Myriapoda: Chilopoda)

We studied the effects of one ecdysteroid analog (RH-0345) on the ovarian and testicular components of the centipede Eupolybothrus nudicornis used as a model of predators of soil fauna. The injection of 10 µg of RH-0345 significantly reduced protein, lipid and carbohydrate concentrations in both the ovarian tissue of females and testicular tissue of males collected in spring or autumn. In consequence, this study shows that ecdysteroid analog pesticides can affect the reproduction of other arthropods than insects by modifying the level of metabolites in male and female gonads.