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In the brain of the African catfish aromatase activity was demonstrated with two different methods using [7-3H]androstenedione and [19-3H]androstenedione as substrates. Kinetic analysis of estrogen formation following incubations of a cell-free fraction of brain homogenates showed that the apparent Km is the same for both substrates (0.03 micro M), but the(More)
Aromatase activity was determined in small discrete areas of the brain of the African catfish, Clarias gariepinus, by a radiometric assay. The fore- and midbrain were divided into eighteen 500-microns transverse sections. From these sections several punches (0.3 mg of tissue) were taken and incubated with [19-3H]-androstenedione. The aromatase activity,(More)
Gonadal homogenates of rainbow trout from D(ay) 60, D100 and D200 after fertilization have been incubated in vitro in the presence of dehydroepiandrosterone-3H to demonstrate 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) and delta 5,4-isomerase activity, of pregnenolone-3H to assess the synthesis of "progestins" and of androstenedione-3H to determine(More)
Tritiated androstenedione was in vitro aromatized to estrone and estradiol by the stickleback brain. Highest aromatase activity was found in the diencephalon, particularly in the periventricular hypothalamic region containing the nucleus preopticus (NPO), in the area containing the nucleus lateralis tuberis, and in the pituitary. This localization suggests(More)
Brain homogenates from Atlantic salmon parr converted tritiated androstenedione to testosterone, estrone, and 17 beta-estradiol. The formation of estrogens was markedly higher in homogenates of whole brains from mature parr males than from immature parr males. The highest estrogen synthesis was found in the telencephalon and diencephalon. In both of these(More)
Brain homogenates from male Atlantic salmon parr aromatized tritiated androstenedione to estrogens. The aromatase activity in homogenates of whole brains from castrated male parr was lower than that in homogenates from sham-operated male parr in autumn. This was also found in homogenates of the telencephalon and diencephalon, but not in homogenates of the(More)
In female zebrafish ovulation could be induced by male holding water, testis homogenates, and testis fractions containing steroid glucuronides. Deglucuronidation of these fractions led to a loss of ovulation-inducing potency, indicating steroid glucuronides as ovulation inducers. The chemical substances were perceived by the recipient females by means of(More)
Our previous experiments to study the effect of stress adaptation on pubertal development in carp showed that repeated temperature stress and prolonged feeding with cortisol-containing food pellets, which mimics the endocrine stress effects, retarded the first waves of spermatogenesis and decreased 11-ketotestosterone (11KT) plasma levels. The objective of(More)