Efecto in vitro del suero de la trucha arco iris, oncorhynchus mykiss, sobre metacercarias del género tylodelphys trematoda displostomatidae / The in vitro effect of rainbow trout, oncorhynchus mykiss, serum in tylodelphys sp trematoda displostomatidae metacercariae

Here, it has been described that normal fresh sera from rainbow trout (oncorhynchus mykiss) were able to Iyse Tylodlphys sp. metacercariae isolated form Galaxias maculatus (Jenyns, 1842) (Teleostei, Galaxiidae) brain. This effect was time dependent, and progressively increased since 1 h up to 18 h incubation. There were oscillations in the ability of different sera samples to lyse these parasites. Similar values were achieved with other salmonid sera, and also with normal human sera pool. The lytic activity was abolished by heat-inactivated sera, by zymosan treatment and by incubation in the presence of EDTA. However, the mean values obtained in the presence of EGTA-Mg++ did not significantly differ from those found with sera as a source of complement. The results of this study suggested the role of complement alternative pathway on Tylodephys sp. in vitro lysis, under our experimental conditions

Effects of cadmium on plasma cortisol and prolactin levels in the rainbow trout [oncorhynchus mykiss]

Cadmium occurs as a contaminant in freshwater systems, primarily are a result of lead mining, smelting and electroplating. In freshwater fish, prolactin and cortisol are thought to be in volved in the maintenance of ionic and osmotic balance and since this regulation is apparently disrupted by cadmium, related changes in prolactin and cortisol might occur. In view of this, it was decided to investigate the effect of cadmium on plasma cortisol and prolactin levels in the rainbow trout. The objectives of this research were to determine the LC50 values during 120 h period after acute exposure to poison of cadmium chloride. The LC50 values for 24, 48, 72, 96 hours were, found to be 7.76, 1.95, 0.5, 0.45 mg/lit respectively. Exposure of rainbow trout to 10, 1, 0.5 mg/lit cadmium during 24h did not have any change in plasma prolactin levels [p>0.05]. Exposure of fish to 0.1 mg/lit cadmium 5, 24, 48, 96 hours in tank water produced time dependent changes [p=0] in plasma prolactin levels. Exposure of trout to 0.05 mg/lit cadmium did not change plasma prolactin levels [p>0.05]. Exposure of trout to 0.05 mg/lit cadmium for 24 and 27 h. didnot have any change in plasma cortisol levels [p=0.08]. Exposure of trout to 0.1 mg/lit of cadmium in the tankwater in 5, 24, 28, 26 h. Producedtime dependent changes in plasma cortisol levels which may reflect the alarm resistance and exhaustion stages in the response of the fish to the cadmium

Determinación de algunos aspectos hematológicos de Oncorhynchus mykiss (Salmonidae), en Cundinamarca, Colombia / Determination of some hematological aspects of Oncorhynchus mykiss (Salmonidae), in Cundinamarca, Columbia

Thirty-five normal, adult specimens of the rainbow trout Oncorhynchus mykiss (Richardson, 1836) cultured in the Neusa Fishculture Station (73 degrees 38'28r W; 5 degrees 8'30r N) were studied to establish normal blood values; the hematopoietic tissues (pronefros, spleen and thymus), and other organs such as the stomach were also structurally studied. The rainbow trout collected in the second half of 1990 and the beginning of the first half of 1991 had 1,415,000 erythrocytes and 22,000 leukocytes per mm3 of blood. Their hemoglobin concentration was 6.99 g/100ml. They had three types of circulating leukocytes: lymphorytes 65 per cent, polimorphonuclears 24 per cent and monocytes 11 per cent. The pronephros is the major hematopoietic organ in the rainbow trout. It produces mainly the polimorphonuclears; the spleen and the thymus are linfopoietics. The study of the hemocytometric values in the peripheral blood frotis and the structure of the hematopoietic organs of the rainbow trout is very useful, accessible and inexpensive. It produces data which yield information about physiological and pathological conditions