Adrenal-kidney and gonadal steroidogenesis during sexual differentiation of a reptile with temperature-dependent sex determination.
Adrenal-kidney and gonadal steroidogenesis were studied during early development in the red-eared slider turtle, Trachemys scripta, which exhibits temperature-dependent sex determination. In vitro steroid secretion by adrenal-kidney-gonad complexes (AKGs) incubated for 6 hr was determined by radioimmunoassay (RIA). AKGs from presumptive males and females secreted progesterone at developmental stages before (stage 15), during (stages 17 and 19), and after (stage 21) the temperature-sensitive period for sex determination, and progesterone secretion increased significantly throughout the period from stage 15 to 21. Presumptive male AKGs secreted significantly more progesterone than female AKGs at stage 19. Corticosterone secretion by AKGs was observed at stage 17 in males only, but in both sexes at stages 19 and 21. Testosterone, estradiol, androstenedione, and dehydroepiandrosterone secretion by AKGs was detected only at stage 21. Of the steroids measured, progesterone and corticosterone were consistently secreted at the highest levels. Although some sex differences were observed, no obvious patterns of sexually dimorphic steroid secretion from AKGs were apparent. Gonads from stage 21, stage 24, and 10-day-old hatchlings from both presumptive sexes incubated with [7-3H]pregnenolone showed only weak precursor conversion, primarily to polar metabolites, in incubations as long as 24 hr. None of the steroids assessed by RIA of AKG incubates could be identified by TLC or HPLC analysis of the stage 21 and stage 24 gonadal incubates. However, progesterone was tentatively identified in incubates of 10-day post-hatch female gonads. For stage 21 females, AKGs were separated into gonadal and adrenal-kidney tissue (AK) components and incubated in vitro for 1, 3, and 18 hr.(ABSTRACT TRUNCATED AT 250 WORDS)
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University of Texas Marine Science Institute, Austin, Port Aransas 78373.
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D000311:Adrenal Glands / Q000378:metabolism*; D000818:Animals; D002855:Chromatography, Thin Layer; D005260:Female; D007202:Indicators and Reagents; D007668:Kidney / Q000378:metabolism*; D008297:Male; D010053:Ovary / Q000378:metabolism*; D011863:Radioimmunoassay; D012733:Sex Differentiation / Q000502:physiology*; D013256:Steroids / Q000096:biosynthesis*; D013696:Temperature; D013737:Testis / Q000378:metabolism*; D014426:Turtles
D007202:Indicators and Reagents; D013256:Steroids