IN-VITRO BIOSYNTHESIS OF ANDROGENS IN THE AUSTRALIAN LUNGFISH, NEOCERATODUS-FORSTERI

The serum concentration of testosterone was estimated from a populatio n of wild lungfish over 6-7 years of sampling. Male lungfish were foun d to have high circulating levels of testosterone (similar to 50 ng/ml ) which varied seasonally and could be correlated with spermatogenesis as judged by testis histology. Incubation of testis tissue slices wit h [H-3]progesterone, [H-3]17-hydroxyprogesterone, or [H-3]tezstosteron e confirmed that testosterone is the major androgen in Neoceratodus. N ot even trace amounts of 11-keto- or 11 beta-hydroxytestosterone or 5 alpha-dihydrotestosterone could be identified by TLC separations. Ther e was little or no conjugation of steroids by the testes, except durin g the spawning season, when glucuronides of androstenedione and testos terone were produced. (C) 1996 Academic Press, Inc.