[Hybridization between Atlantic salmon Salmo salar L. and brown trout S. trutta l. upon artificial propagation].

Samples of Salmo salar and S. trutta were examined in 12 Russian fish hatcheries. With protein markers, hybrids of the two species were found in three hatcheries of the Baltic Sea basin.

Effects of testosterone on gonadotropins, testes, and plasma 17alpha,20beta-dihydroxy-4-pregnene-3-one levels in postbreeding mature Atlantic salmon, Salmo salar, male parr.

Atlantic salmon, Salmo salar, mature male parr were implanted with testosterone (T) in small (T3) or large (T10) Silastic capsules in the breeding season or at its end in November or December, in order to find out whether the postbreeding decline in 17alpha, 20beta-dihydroxy-4-pregnene-3-one (17,20beta-P) and milt production is a consequence of declining T levels. In the first of three experiments, fish were sampled the following January and March, whereas in the second and in the third they were sampled in April. Pituitary and plasma concentrations of gonadotropic hormone (GTHs) I and II and plasma levels of T, 11-ketotestosterone (11-KT) and 17, 20beta-P were measured by radioimmunoassays, and the testes were examined histologically.

[Antimicrobial and antitrichomonal activity of 5-nitroimidazole derivatives in an in vitro experiment].

The comparative study on the antimicrobial activity of metronidazole and its complex with cobalt sulfate showed that the complex formation increased 2-4 times the metronidazole activity against elective anaerobes. The study of the drug action on Trichomonas spp. revealed that as a result of the complexing with cobalt sulfate the metronidazole efficacy against the Trichomonas strains isolated from the discharge of a female patient with metronidazole resistant trichomoniasis increased, the activating effect of the complex on the host cells being suggested.