Using blood plasma for monitoring organochlorine contaminants in juvenile white sturgeon, Acipenser transmontanus, from the lower Columbia River.

Organochlorine (OC) pesticide concentrations in blood plasma samples from 88 juvenile white sturgeon collected from the lower Columbia River were measured and compared to plasma sex steroid and OC tissue levels previously measured in corresponding fish. Significant squared correlation coefficients between summation operator DDT concentrations in sturgeon plasma and gonads and livers were 0.37 and 0.32, respectively. Significant negative correlations between plasma testosterone concentration and plasma Sigma DDT concentration in male fish (r(2)=0.26), plasma 17beta estradiol concentration and plasma Sigma DDT concentration in female fish (r(2)=0.38) and condition factor and plasma Sigma DDT concentration in all fish were found (r(2)=0.17). These results suggest that blood plasma may be a suitable nondestructive method for monitoring adult sturgeon population for persistent OC contaminants.

Behavioral correlates of oral and postingestive satiety in the rat.

Hungry rats display the characteristic "satiety sequence" after drinking a glucose solution: The end of ingestion is accompanied by grooming and exploring, followed by resting. With saccharin solutions over a range of concentrations, however, ingestion is accompanied and followed by persistent grooming and exploring; resting rarely occurs. Gastric preloads of glucose solution promote resting to reinstate the "satiety sequence" after a bout of saccharin ingestion. Therefore, the systemic effects of glucose are sufficient to promote resting. In the absence of postingestive factors, the "satiety sequence" is incomplete following saccharin ingestion as it is after sham-feeding.

Glucose solution intake in the rat: the specificity of postingestive satiety.

Hungry rats were permitted to drink a concentrated glucose solution to 'satiety', as indicated by (1) cessation of drinking, (2) the appearance of behaviors correlated with satiety (grooming and exploring followed by resting), and (3) refusal to drink appreciable further quantities when access to the solution was prolonged. Yet such rats returned to vigorous and prolonged feeding when offered laboratory pellets, powered chow, or even glucose itself in powered form. "Satiety" for a glucose solution does not reflect a generalized suppression of hunger or of a specific carbohydrate hunger. Its properties are more specific than existing theories of energy intake regulation would lead us to suppose.