Quantitative studies of steroid bioconversions in the seminal vesicles of spawning male African catfish, Clarias gariepinus (Burchell), under natural conditions, and of non-spawning catfish under natural and fish farm conditions.
1. Steroid bioconversions in the seminal vesicles of Clarias gariepinus were studied quantitatively in vitro by tissue incubations with [3H]pregnenolone, [3H]androstenedione and [14C]11 beta-hydroxyandrostenedione, respectively. 2. Spawning and non-spawning catfish, collected in the Hula nature reserve in northern Israel during the spawning period, and non-spawning animals, collected from a fish pond in the same region during the same period, were studied. 3.Spawning animals showed a significantly higher production of 17 alpha-hydroxyprogesterone, 5 beta-pregnan-17 alpha-ol-3,20-dione and 5 beta-reduced androgens than non-spawning feral and pond catfish, as a result of a significantly increased contribution of the enzymes 5 beta-reductase and 3 alpha-hydroxysteroid dehydrogenase (HSD). 4. In spawning catfish the concentration of gonadotropin in blood plasma were also significantly higher than in the plasma of non-spawning feral and pond catfish. This increase in gonadotropin level might have induced the rise in enzyme activity of 5 beta-reductase and 3 alpha-HSD. 5. It is concluded that the absence of a shift in steroidogenesis towards the production of 5 beta-reduced steroids may be among the factors preventing spontaneous spawning in male African catfish under husbandry conditions.
Schoonen
W G
WG
Zoological Laboratory, University of Utrecht, The Netherlands.
Granneman
J C
JC
Lambert
J G
JG
Viveen
W J
WJ
van Oordt
P G
PG
D000735:Androstenedione / Q000031:analogs & derivatives* / Q000378:metabolism*; D000818:Animals; D000829:Animals, Domestic; D000835:Animals, Wild; D001711:Biotransformation; D002250:Carbon Radioisotopes; D002397:Catfishes / Q000378:metabolism*; D008297:Male; D011284:Pregnenolone / Q000378:metabolism*; D012669:Seminal Vesicles / Q000378:metabolism*; D012741:Sexual Maturation; D014316:Tritium
D002250:Carbon Radioisotopes; D014316:Tritium; D000735:Androstenedione; C003582:11-hydroxyandrostenedione; D011284:Pregnenolone