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Environmental Toxicology
Birds

Samples of genetics and genomics research from the USGS Ecosystems Mission Area about the environmental toxicology of birds.

Genomic indicators of endocrine disruption in multiple generations of Japanese quail exposed to 17β trenbolone
Japanese quail hatchling. Photo courtesy of Yu Chen, USGS Patuxent Wildife Research Center.

Adult Japanese quail (Coturnix japonica). Photo courtesy of Yu Chen, USGS Patuxent Wildlife Research Center.

17β trenbolone is a synthetic anabolic steroid used as a growth promoter in cattle and is a common contaminant of Concentrated Animal Feeding Operations (CAFOs), found in manure and wastewater outflows. We investigated the effects of 17β trenbolone on gonadal function of three successive generations of Japanese quail (Coturnix japonica) by examining the expression of sex-steroid responsive genes, thyroid hormone related genes, and peptide hormone related genes. The U.S. Environmental Protection Agency has proposed the use of Japanese quail for evaluating the effects of potential endocrine disrupting chemicals on human and wildlife health. As part of this, PWRC scientists are developing new, more informative reproductive, physiological and genomic endpoints, not previously considered by the EPA, which would improve protocol sensitivity for detecting adverse effects and which could be applied to wildlife species. The results from our study, combined with additional endocrine and physiological data from the same population, will allow us to assess the potential of 17β trenbolone to act as an endocrine disruptor in wild avian species.

For more information contact Natalie K. Karouna-Renier, Patuxent Wildlife Research Center.

Genomic effects of the flame retardant 1,2,5,6,9,10-Hexabromocyclododecane (HBCD) in multiple generations of Japanese quail
Japanese quail hatchling. Photo courtesy of Yu Chen, USGS Patuxent Wildife Research Center.
Japanese quail (Coturnix japonica) hatchling. Photo courtesy of Yu Chen, USGS Patuxent Wildife Research Center.

1,2,5,6,9,10-Hexabromocyclododecane (HBCD) is a globally distributed, high production volume brominated flame retardant, which has demonstrated endocrine effects related to the thyroid, progesterone, estrogen, and androgen systems. Toxicity concerns surrounding HBCD stem from its persistence, potential for long-range transport in the environment, evidence of its bioaccumulation and biomagnification in the food chain, and potential reproductive, developmental, and neurological effects in terrestrial and aquatic species. We are investigating the effects of HBCD on gene expression in multiple generations of Japanese quail (Coturnix japonica) exposed to one of five doses of HBCD. Gene expression indicative of potential endocrine disrupting effects including sex-steroid responsive genes and thyroid hormone related genes, and biotransformation enzyme-related genes, is being analyzed in adult and embryonic quail tissues using real-time quantitative PCR. The results of this study will provide a preliminary basis for comparing the Japanese quail model relative to known effects observed in wildlife avian species.

For more information contact Natalie K. Karouna-Renier, Patuxent Wildlife Research Center.

Profiling Mercury Response Genes in Birds as an Indicator of Species Sensitivity
Laughing Gull (Larus atricilla). Photo credit: courtesy of Jeffrey A. Spendelow, USGS Patuxent Wildlife Research Center
Laughing Gull (Larus atricilla). Photo credit: courtesy of Jeffrey A. Spendelow, USGS Patuxent Wildlife Research Center

Although exposure to mercury is known to have toxic effects on birds, until recently, only limited information was available on the sensitivity of various species to mercury exposure. Recent studies conducted at the USGS Patuxent Wildlife Research Center have confirmed that clear differences exist in the sensitivity of various bird species to methylmercury. However, the molecular mechanisms that account for the observed differences in sensitivity in birds are unknown. To address this issue, we are investigating the genomics of methylmercury in exposed birds. Gene expression profiles of less sensitive species are being compared with those of more sensitive species. The results of these studies will improve our understanding of species-specific and within-species differences in susceptibility to methylmercury in birds. Our goal is to identify a new genetic tool that would enable prediction of mercury’s effects in field-collected samples and facilitate identification of at-risk or resistant populations.


Publication: Jenko, K., N.K. Karouna-Renier, D. J. Hoffman. 2012. Gene expression, glutathione status and indicators of hepatic oxidative stress in laughing gull (Larus atricilla) hatchlings exposed to methylmercury. Environ. Toxicol. Chem. In press. http://onlinelibrary.wiley.com/doi/10.1002/etc.1985/abstract

For more information contact Natalie K. Karouna-Renier, Patuxent Wildlife Research Center.

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