Effets à court terme et à long terme d'un narcotique sur quelques activités enzymatiques chez le copépode harpacticoïde Tisbe holothuriae

The anaesthetic properties of clomethiazole ethane disulfonate (hydrochloric ester of thiazole fraction of Vitamin B 1) were tested on the harpacticoid copepod Tisbe holothuriae Humes. Concentrations of 0.250, 0.50, 0.625, 0.714 and 0.833 in sea water were tested. The copepod was exposed to the anaesthetic solutions for periods of 30 min and 1 h. A concentration of 0.250 was sufficient to induce immobility within a few minutes; the lethal concentration is 1. Immediate and delayed effects of narcosis on the activities of the enzymes esterases (EST), leucine aminopeptidase (LAP), alkaline phosphatase (ALP), malate dehydrogenase (MDH), malic enzyme (ME) and phosphoglucomutase (PGM) were studied using electrophoresis in polyacrylamide gel. No change in EST, LAP and ALP zymograms was observed during 48 h postnarcosis, whatever the clomethiazole concentration used, but changes in MDH, ME and PGM activity were observed after anaesthesia in 0.714 and 0.833 clomethiazole. The stronger the concentration used, the earlier and longer-lasting was the decrease in activity. For MDH, which is coded by two loci, electrophoresis revealed that one locus (the fast fraction) is more sensitive to the narcotic than the other, slow one.