Meeting Abstract
109.4 Sunday, Jan. 6 Androgen profiles across the male pregnancy cycle in the sex-role reversed Gulf pipefish SCOBELL, S.K.*; JAQUES, J.T.; JONES, A.G.; Texas A&M University; Texas A&M Veterinary Medical Diagnostic Laboratory, Texas A&M University; Texas A&M University skscobell@tamu.edu
Male pregnancy is a phenomenon found only in the teleost fish family Syngnathidae (seahorses, seadragons, and pipefish). The male accepts eggs from the female into a ventral brood pouch where they are fertilized and brooded until birth. Recent studies in syngnathids have shown that males aerate and osmoregulate the brood pouch fluid, and likely provide nutrients and immunity to embryos during the pregnancy. However, few studies have examined the hormonal regulation of male pregnancy in syngnathids. Hormones are well established in teleost fish as primary regulators of puberty, gonadal development, mating, and reproductive behaviors, and thus are likely candidates for mediating male pregnancy in seahorses and pipefish. Previous work on syngnathids suggests an important role of androgens in development of the brood pouch, maintenance of the testes, and spermatogenesis. However, to our knowledge there have not been any studies that correlate circulating plasma androgens with these traits across the reproductive cycle. We conducted a field study of circulating testosterone and 11-ketotestosterone levels in male and female Gulf pipefish, Syngnathus scovelli. We first asked whether there was a reversal of plasma androgen levels in the sexes of this polyandrous, sex-role reversed species. We then examined whether androgens correlated with gonad mass or body size in both sexes. Finally, we compared testes mass and circulating androgen levels across various stages of the male reproductive cycle. Our data show no reversal of plasma androgen levels between the sexes, but they do suggest that male Gulf pipefish modulate androgens across the reproductive cycle to regulate alternating cycles of spermatogenesis and pregnancy.
