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An antarctic hemoglobin-free Fish, living in the Kerguelen archipelago, Channichthys rhinoceratus, is devoid of carbonic anhydrase in the blood but has a high content of this enzyme in the gills which appears to be twice that of another normal species living in the same area. Notothenia magellancia. This enzyme appears to play an important role in the osmoregulation of the Channichthyidae.

The plasma testosterone levels in Fish treated with ovine Prolactin during 10 or 21 days are significantly greater than in controls. Shorter term treatment remains ineffective. The ponderal parameters concerning the testes and the genital accessory glands tend to vary in the same way during the longest term treatments.

An anticlotting factor was found recently in the cephalothoracic latero-oesophageal glands (G.L.O.) of Cymothoid Isopods (blood-sucking fishparasites). This substance is efficient on the blood of hosts such as Boops boops (L.), and also on the human plasma. The way of action and the chemical kind of this factor were investigated: Plasmatic coagulation-tests (Howell, Quick, Cephalin-kaolin, Stypven, Stypven-cephalin, Thrombin and Thrombin coagulase times) were realized on citrated plasmas of Boops and man; enzymatic activities of latero-esophageal glands and hepatopancreas of Meinertia oestroides (Risso, 1826) were also studied. Our results show that the anticlotting action of G.L.O. extracts proceeds from an anti-thrombinic factor, certainly carbohydrate-like as heparin.

The levels of ornithine carbamyl transferase, acid phosphatase, alkaline phosphatase, leucine amino peptidase, creatine kinase, amylase, glutamic oxalacetic transaminase, glutamic pyruvic transaminase, lactate deshydrogenase, hydroxybutyrate deshydrogenase, glutamate deshydrogenase and malate deshydrogenase were determined in the plasma of Rainbow Trout and Tench submitted to water temperature increases. In the Rainbow Trout a thermal shock from 12 to 21 degrees, increases activities of some enzymes while temperature increase up to pre-mortem stage causes very important changes in enzymatic levels. In the Tench a thermal shock from 12 to 28 degrees causes more changes of enzymatic activities than a shock from 12 to 25 degrees. In Tench acclimated to 25 degrees, various enzyme levels are increased in comparison with 12 degrees control animals. A high potassium level in water causes complex changes in enzyme levels. The most sensitive enzymes to thermal disturbance are GOT and GPt transaminases which increase whatever the aggression form, amylase when thermal disturbance is moderate, alkaline phosphatase and malate deshydrogenase in case of strong thermal stress. The study of these enzymes is recommended for watching the state of fishes living in artificially heated waters.

The free amino-acid composition of the sera of 4 species of Isopods Cymothoidae (Meinertia oestroides, Meinertia parallela, Emetha audouini, Anilocra physodes) are very similar, and present the same characteristics, both quantitatively and qualitatively, as those of free marine Isopods of the family Sphaeromatidae and Idoteidae. Five amino acids are preponderant (serin, prolin, glycin, alanin and taurin). The total concentration is relatively high (154.6-356.4 mg/100 ml) with respect to Decapods. In the parasites studied so far, the free amino-acid pattern (except prolin) is rather like that of the Teleost Fishes, whether they are potential hosts of Cymothoidae or not. The free amino-acid concentration of the blood of the Fishes does not seem to be impaired by the Cymothoidae parasitism.

Antarctic hemoglobin-free fish possess, besides white and cardiac muscles, a third type of striated muscle of yellowish appearance devoid of myoglobin which corresponds to the fish red muscles. Each of these three types differs from the others by its parvalbumin composition and lactate dehydrogenase isozymic distribution.

An ecophysiological study on certain parasitisms by Cymothoids allows the elucidation of the following points: --occurrence of oesophagien-side glands producing an anticoagulant effect on the blood of host, the absorption and metabolism of haemoglobin derivatives (hematin and iron) are performed by the hepatopancreas; --existence of immunological reactions between host and Cymothoids; --existence of biochemical, histological, haemotological and biometrical variations among fishes infected by these parasites.