HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 78/5/932    most recent biolreprod.107.064915v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Milnes, M. R. Articles by Guillette, L. J. PubMed PubMed Citation Articles by Milnes, M. R. Articles by Guillette, L. J., Jr. Agricola Articles by Milnes, M. R. Articles by Guillette, L. J.

Increased Posthatching Mortality and Loss of Sexually Dimorphic Gene Expression in Alligators (Alligator mississippiensis) from a Contaminated Environment¹

Department of Zoology,³ University of Florida, Gainesville, Florida 32611 Okazaki Institute for Integrative Bioscience,⁴ National Institute for Basic Biology, National Institutes of Natural Sciences, Okazaki 444-8787, Japan

ABSTRACT

A previous study from our laboratory examining development in neonatal alligators from polluted Lake Apopka, Florida, found numerous differences relative to neonates from a reference site, Lake Woodruff National Wildlife Refuge. We postulated that the differences were the result of organizational changes derived from embryonic exposure to environmental contaminants and are related to the poor reproductive success reported in alligators from Lake Apopka. In this study we examine differences in alligators collected as eggs from these two populations and raised under similar conditions for 1 yr. Egg hatch rates did not differ between lake populations; however, posthatching mortality was much higher among Lake Apopka hatchlings. Snout-vent length and body mass were greater in Lake Apopka hatchlings, but no differences were detected between lake populations in thyroid, liver, and spleen mass corrected for body size or in plasma concentrations of testosterone and estradiol. Males from Lake Woodruff exhibited greater relative expression of gonadal mRNA for steroidogenic factor 1 (Nr5a1) and steroidogenic acute regulatory protein (Star) than males from Lake Apopka. Alligators from Lake Woodruff also expressed all genes examined in a sexually dimorphic pattern. In contrast, mRNA expression did not differ between males and females from Lake Apopka for Nr5a1, Star, cytochrome P450 11A1 (Cyp11a1), and hydroxy-delta-5-steroid dehydrogenase, 3 beta- and steroid delta-isomerase 1 (Hsd3b1). Our results document persistent differences in development, survivorship, and gene expression in alligators from a contaminated environment. Because these animals were raised under similar laboratory conditions, the differences are most likely of embryonic origin and organizational in nature.

estradiol, gene regulation, steroid hormones, testosterone, toxicology

¹Supported in part by grants to L.J.G. from the UF Opportunity Fund, grants to T.I. from the Japanese Ministry of Education, Culture, Sports, Science, and Technology and from the Japanese Ministry of Environment, and a grant to M.R.M. from the National Science Foundation and Japanese Society for the Promotion of Science (OISE-0413602).

Correspondence: ²Correspondence and current address: Matthew R. Milnes, Conservation and Research for Endangered Species, Zoological Society of San Diego, 15600 San Pasqual Valley Road, Escondido, CA 92027-7000. FAX: 760 291 5428; e-mail: mmilnes{at}sandiegozoo.org