Yves Pichot

Viral infection (picorna-like virus) associated with mass mortalities in hatchery-reared sea-bass (Dicentrarchus labrax) larvae and juveniles

Abstract Histopathological lesions of the central nervous system are described hatchery-reared larval seabass during mass mortalities. Lesions are consistent with an extensive vacuolation of the brain and retina, associated with intracytoplasmic inclusions, containing RNA as demonstrated with acridineorange epifluorescence. Electron microscope observations revealed numerous cytoplasmic, non-enveloped particles about 22–23 nm in diameter. Isopycnic centrifugation in a CsCl gradient produced iwo bands of virus particles showing buoyant densities of 1.30 to 1.34 g/cm 3 , respectively. Negatively stained preparations exhibited full and empty icosahedral particles about 26 nm in diameter from side to side and 29 nm from point to point. By their characteristics, these particles are closely related to the Picornaviridae family.

Deep-sea caging of the mussel Mytilus galloprovincialis: Potential application in ecotoxicological studies

We experimented with caging the Mediterranean mussel (Mytilus galloprovincialis) at various depths for 69 d to measure basic physiological parameters, histological response and bio-accumulation of contaminants in a deep-sea contaminated area. In preliminary experiments, we demonstrated, under artificial pressure conditions, the ability of mussels Mytilus galloprovincialis to tolerate rapid immersion (at a speed of up to 120 m min−1). In situ experiments were performed using submerged lines enabling mussels to be maintained at depths ranging of 40–1550 m with survival rates ranging from 80 to 38%, respectively. No significant differences in condition indexes were observed between treated and control specimens. However, histological observations demonstrated a clear reduction in thickness of the digestive epithelium with increasing depth exposure. By determining the contaminants in caged mussels, we found the following values for chromium accumulation: 27.4 μg g−1 dry weight at 580 m depth and 9.8 μg g−1 dry weight at 1550 m. Selected stations were located downstream of an industrial effluent at 420 m. The biological and environmental consequences of deep-sea contamination demonstrate the suitability of caged mussels for monitoring contaminant accumulation.

Temporal study of estrogenic responses of mussel (Mytilus galloprovinciallis) extracts applied to reporter cell lines

In vitro bioassays would facilitate monitoring of estrogen-like compounds in mussels (Mytilus galloprovincialis) since they tend to accumulate lipophilic compounds in their fat and muscle tissue. However, estradiol (E2) steroid (already identified in mussels) could induce false positive responses. This study focuses on temporal variability in estrogenic responses of mussel extracts and the possible relation of this response with E2 levels. The reproductive cycle and growth were thus monitored for six months in sexed mussels. E2 levels were similar between genders and these levels varied with reproductive stages. human estrogen receptor (hER) activities were similar at all stages except in February. E2 present in male and female extracts accounted for part of the hER activation observed, but no correlation was found between E2 levels and hER activities.