Serum Concentrations of Various Environmental Contaminants and Their Relationship to Sex Steroid Concentrations and Phallus Size in Juvenile American Alligators

Department of Zoology, 223 Bartram Hall, University of Florida, Gainesville, Florida 32611, USA.
Archives of Environmental Contamination and Toxicology (Impact Factor: 1.9). 06/1999; 36(4):447-55. DOI: 10.1007/PL00006617
Source: PubMed

ABSTRACT Recent studies have reported a number of abnormalities in the hatchling and juvenile alligators of Lake Apopka, FL (USA). These abnormalities include modifications of plasma concentrations of sex steroids in males and females as well as abnormalities in gonadal morphology, gonadal enzyme activity, and steroidogenesis. Embryonic exposure to environmental contaminants in the eggs has been hypothesized to be the causal agent for these changes. However, posthatchling exposure can also contribute to changes in reproductive and endocrine functioning. We have detected serum concentrations of 16 of 18 organochlorine pesticides or metabolites (OCs) and 23 of 28 congener-specific polychlorinated biphenyls (PCBs) examined in juvenile alligators from Lake Apopka, Orange Lake, and Lake Woodruff National Wildlife Refuge. Lake Apopka juveniles had significantly elevated serum concentrations of p,p'-DDE, dieldrin, endrin, mirex, oxychlordane, SigmaDDTs, and SigmaPCBs compared to juveniles from the other lakes. Further, we observed no correlations between serum contaminant concentrations and sex steroid concentrations (estradiol-17beta and testosterone). However, serum testosterone was significantly lower in males from Lake Apopka and Orange Lake compared to Lake Woodruff NWR. We did not observe relationships between phallus size or other body parameters and serum contaminant levels. Phallus size was smaller in males from Lake Apopka even after adjustment for body size. We suggest that the observations previously reported for juvenile alligators-and observed again in this study-are apparently not associated with the current serum levels of the environmental contaminants we measured, but could be due to exposures during embryonic development to these or other pollutants. Future studies must determine if a causal relationship exists between the contaminants found in alligator eggs and abnormalities observed in the hatchlings and persisting in juveniles.

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Available from: Louis J Guillette, Jul 23, 2014
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    • "Photos were captured with Leica Application Suite V3 7.0. The width of the hemipenes of both male and female neonates was measured (mm; Guillette et al. 1999; Newbold 2004). Both hemipenes were measured thrice in ImageJ ( and the average of the six measurements was utilised in the statistical analysis. "
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    ABSTRACT: The ubiquitous presence of endocrine-disrupting chemicals (EDCs) in the environment is of major concern. Studies on oviparous reptiles have significantly advanced knowledge in this field; however, 30% of reptilian species are viviparous (live-bearing), a parity mode in which both yolk and a placenta support embryonic development, thus exposure to EDCs may occur via multiple routes. In this first study of endocrine disruption in a viviparous lizard (Niveoscincus metallicus), we aimed to identify effects of the oestrogen mimic diethylstilbestrol (DES) on gonadal development. At the initiation of sexual differentiation, pregnant N. metallicus were treated with a single dose of DES at 100 or 10µgkg--1, a vehicle solvent or received no treatment. There was no dose-response effect, but the testes of male neonates born to DES-exposed mothers showed reduced organisation of seminiferous tubules and a lack of germ cells compared with those from control groups. The ovaries of female neonates born to DES-exposed mothers exhibited phenotypic abnormalities of ovarian structure, oocytes and follicles compared with controls. The results indicate that, in viviparous lizards, maternal exposure to oestrogenic EDCs during gestation may have profound consequences for offspring reproductive fitness.
    Reproduction Fertility and Development 04/2014; DOI:10.1071/RD13411 · 2.40 Impact Factor
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    • "The lakes differ in their spring and fall temperature profiles and contaminant loads (Garrison et al. 2010; Guillette et al. 1999, 2000; Heinz et al. 1991). Lake Apopka has a history of substantial contamination and nutrient inputs and was up to 7 °C warmer in the late fall and early spring, compared to Lake Woodruff, which is more protected from anthropogenic influences . "
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    ABSTRACT: Sixteen monthly collections of adult male Gambusia holbrooki (eastern mosquitofish) were obtained from two lakes in central Florida, USA. Lake Woodruff and Lake Apopka are 36 miles apart, but differ in several environmental parameters. Compared with Lake Woodruff, Lake Apopka is warmer, more shallow in sampling areas (particularly during drought conditions; approximately 15-90 cm in Lake Apopka versus 60-120 cm in Lake Woodruff), more turbid, and more heavily contaminated with nutrients and industrial and agricultural chemicals. Here, we present detailed information on seasonal reproduction patterns in mosquitofish in their native range and compare patterns between fish from the two lakes. Male mosquitofish were reproductively active from spring through fall. Spermatogenesis, which is regulated in part by 11-ketotestosterone, ceased in October, and fish stored spermatozoa through the winter for immediate fertilization of offspring in the spring. Compared with Lake Woodruff, fish from Lake Apopka tended to be larger and have longer gonopodia and greater gonado- and hepato-somatic indices (GSI and HSI). High GSI in Apopka fish correlated with greater spermatid production, but fewer mature spermatozoa and either the same or lower sperm counts and sperm viability. Taken together, these observations suggest that differentiation of spermatids to spermatozoa is disrupted in Apopka fish, leading to reductions in fertility in some months. Delivery of sperm to females could also be affected in Apopka fish, which exhibit lower prevalence of efferent duct tissue in the testes during the summer.
    Fish Physiology and Biochemistry 02/2013; 39(5). DOI:10.1007/s10695-013-9772-z · 1.62 Impact Factor
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    • "Florida, USA Egg yolk Sepulveda et al. 2006 Florida, USA Eggs, mature ovaries Sepulveda et al. 2004 Florida, USA Tail muscle Delany et al. 1988 Florida, USA Tail muscle, visceral fat Honeyfield et al. 2008 Florida, USA Blood plasma Guillette et al. 1999 Florida, USA Brain, fat, liver, muscle, stomach content Wheeler et al. 1977 P. CHARRUAU, ET AL. 2 have shown that OCPs can override the temperature effect and cause sex reversal ( male to female ) at intermediate and male producing temperatures in American alli - gator ( A . mississippiensis ) ( Guillette and Milnes 2000 ; Milnes et al . "
    Caribbean Journal of Science 02/2013; 47(1):1-12. · 0.35 Impact Factor
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