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Abstract

We examined differences in gonadal steroid production and biosynthetic pathway activity with changing reproductive condition and between sexes in the scincid lizard, Tiliqua nigrolutea. We observed clear seasonal and sexual variation in the production of androgens and steroid conjugates, but detected no 17-beta-estradiol or 5-alpha-dihydrotestosterone produced by the gonads. An alternative steroid, more polar than estradiol, was detected: an investigation of this steroid is reported separately [Gen. Comp. Endocrinol. 129 (2002) 114]. There were seasonal and sex-related differences in steroid biosynthetic pathway activity. The Delta 5 pathway metabolite, dehydroepiandrosterone, was detected only in males, and only from incubations using regressed testicular tissue. There was also a seasonal difference between the sexes in rates of progesterone accumulation, although the absence of corresponding elevated plasma concentrations suggests that the role of progesterone switches from a directly acting hormone to a precursor for others during the reproductive cycle in females. These results suggest that within the traditional view that vertebrate biosynthetic pathway activity and end-products are phylogenetically conserved, there is likely to be considerably species- and/or genus-specific variation.

Item Type:	Article
Authors/Creators:	Edwards, A and Jones, SM and Davies, NW
Keywords:	Conjugation; End-product; Ovary; Reptile; Steroid biosynthesis; Testis; Tiliqua nigrolutea
Journal or Publication Title:	General and Comparative Endocrinology
ISSN:	0016-6480
DOI / ID Number:	10.1016/S0016-6480(03)00243-0
Additional Information:	The definitive version is available at http://www.sciencedirect.com
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