Effects of ions substitutions and of inhibitors on transepithelial potential difference and sodium fluxes in perfused gills of the crab Pachygrapsus marmoratus.

With the same saline on both sides of the epithelium, a spontaneous inside negative transepithelial potential difference (PD) was measured in perfused posterior gills of the euryhaline crab Pachygrapsus marmoratus acclimated to dilute sea water. The origin of the PD and the transport properties of the epithelium were investigated by ionic substitutions and by application of inhibitors. Diffusion of Na+ and Cl- ions at the apical side contributes to the establishment of the PD.

Perfusion of gills isolated from the hyper-hyporegulating crab Pachygrapsus marmoratus (Crustacea, Decapoda): adaptation of a method.

This paper reports the adaptation of a branchial perfusion technique to the gills of the small hyper-hyporegulating crab, Pachygrapsus marmoratus. The physiological quality of the preparation has been established and preliminary measurements of the transepithelial potential difference (PD) and sodium fluxes were reported. A clear-cut distinction has to be made between anterior and posterior gills.

Stimulation of osmoregulating processes in the perfused gill of the crab Pachygrapsus marmoratus (Crustacea, Decapoda) by a sinus gland peptide.

Isolated posterior gills of the hyper-hyporegulating crab Pachygrapsus marmoratus were perfused with extracts of homologous sinus glands. Sinus gland extracts stimulated the influx of Na+ ions and increased the transepithelial potential difference in the gills in a dose-dependent and reversible fashion. The bioactivity of extracts prepared from crabs that had been acclimated to 10/1000 salinity for at least 1 week was not significantly different from that of extracts prepared from seawater (36/1000 salinity) crabs.

Ontogeny of Osmoregulatory Structures in the Shrimp Penaeus japonicus (Crustacea, Decapoda).

The ontogeny of differentiated osmoregulatory epithelia in the branchial chamber (gills, branchiostegite, pleura, epipodite) was studied by transmission electron microscopy throughout the postembryonic development of Penaeus japonicus. These epithelia are characterized by typical cytological features, including apical microvilli and numerous basal infoldings associated with mitochondria. Differentiated osmoregulatory structures are not observed in the early larval stages: nauplii and zoea 1.

[Some aspects of nutritional mechanisms in the isopod Ceratothoa oestroides Risso, 1826 parasite of fishes (author's transl)].

Some nutritional mechanisms of the isopod Cymothoidae Ceratothoa oestroides, haematophagic parasite of the teleostean sparid fish Boops boops have been studied in female sexual phase individuals. The study of qualitative (hepatopancreas repletion, different colouration) and quantitative variations (weight variations-) of digestive tract and its appendages has permitted to observe that blood absorption is close related to sexual developmental stages and intermolt cycle. The general pattern seems as follows: food intake is made prior or just before vitellogenesis and after releasing of "pulli".