RESUMEN
Numerous populations of anadromous salmonids in the northwestern United States have been declining for many years, resulting in Endangered Species Act listings and in some cases extinction. The degradation of river ecosystems has been proposed as one of the major reasons for the inability of salmon to maintain their populations. However, the specific factors interfering with the reproduction and survival of salmon during the freshwater phase of their life cycle have not been fully described. This study was initiated to determine the incidence of phenotypic sex reversal in wild, fall chinook salmon (Oncorhynchus tshawytcha) that returned to spawn in the Columbia River. Fish were sampled at different locations within this watershed to determine whether they were faithfully expressing their genotype. We report a high incidence (84%) of a genetic marker for the Y chromosome in phenotypic females sampled from the wild, which was not observed in female fish raised in hatcheries. It appears likely that female salmon with a male genotype have been sex reversed, creating the potential for an abnormal YY genotype in the wild that would produce all-male offspring and alter sex ratios significantly.
Asunto(s)
Trastornos del Desarrollo Sexual , Oncorhynchus/genética , Cromosoma Y/genética , Animales , ADN/análisis , Exposición a Riesgos Ambientales , Femenino , Marcadores Genéticos , Masculino , Fenotipo , Reacción en Cadena de la Polimerasa , Contaminantes Químicos del Agua/efectos adversosRESUMEN
1. The hepatotoxic response of rainbow trout (Salmo gairdneri) to a middle distillate (MD) and heavy distillate (HD) coal liquid was determined following administration by injection or in food. Hepatic aryl hydrocarbon hydroxylase (AHH) activity was compared to the known AHH inducer, benzo(a)pyrene. 2. Acute toxicities (LD50) of 1500 and 1410 mg/kg were obtained 120 hr after intraperitoneal injection (i.p.) for MD and HD coal liquids, respectively. Only the HD induced AHH activity when injected at 5% and 10% of the acute LD50. 3. Ingestion of 7 or 70 mg HD/kg body weight for 1 week resulted in AHH induction at 5-7 times that of control values. Levels of hepatic AHH activity in fish treated at 7 mg HD/kg declined to 2.6 times control values 7 days after exposure. Maximum induction was observed for the 70 mg HD/kg group that was provided control food for 1 week following 2 weeks of exposure. 4. The hepatic index (HI) or liver to body weight ratio generally increased along with increased activity in the enzyme response system.
Asunto(s)
Hidrocarburo de Aril Hidroxilasas/biosíntesis , Carbón Mineral/efectos adversos , Hígado/enzimología , Salmonidae/metabolismo , Trucha/metabolismo , Animales , Inducción Enzimática , Hígado/efectos de los fármacosRESUMEN
1. Rainbow trout (Salmo gairdneri) readily absorbed 14C-quinoline from pelleted food and whole-body concentrations reached apparent equilibrium after 10 days feeding. Maximum whole body concentrations of 14C-quinoline were only 30 eta g/g of quinoline plus metabolites after 7 days depuration. 2. Initial rates of uptake and elimination varied widely among tissues. The uptake rate constants ranged from 0.0006/day for muscle to 0.1455/day for gallbladder plus bile. Mean elimination half-life for quinoline and its metabolites ranged from 0.4 days in gills to 8.7 days for muscle. 3. Depending on tissue, 58-83% of the stored radioactivity was present as metabolites. About 14% of the radioactivity in the bile was present as glucuronide conjugates. 4. Rainbow trout eliminated 66% of the ingested dose 24 hr after feeding. Biliary and fecal excretion were minor routes of elimination.