P450 aromatase alterations and DNA damage as avian pollution biomarkers in cliff and cave swallow breeding near the Rio Grande region, Texas

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Title: P450 aromatase alterations and DNA damage as avian pollution biomarkers in cliff and cave swallow breeding near the Rio Grande region, Texas
Author: Sitzlar, Megan Annette
Abstract: The endocrine system , specifically relating to sex hormones , and genetic material can be targets of environmental contaminants . Environmental contaminants in the Rio Grande region may originate from industrial or agricultural processes and growing populations lacking proper water and sewage infrastructure . Cliff (Petrochelidon pyrrhonota ) and cave (P . fulva ) swallows breeding near the Rio Grande were selected to monitor aromatase activity alterations and DNA damage . Swallows were sampled at six sites along the Rio Grande from Brownsville to Laredo , and a reference site (Somerville ) 350 miles north of the Rio Grande . DNA damage , based on nuclear DNA content , was determined by flow cytometry . A significantly larger mean half peak coefficient of variation (HPCV ) of DNA content in contaminated sites compared to a reference site reflects possible chromosomal damage . No detectable HPCV differences were observed in cave swallows among locations , notwithstanding the presence of mutagenic contaminants . Selenium may provide a protective role against genetic damage . However , cliff swallows from Laredo had significantly higher HPCV values than those from Somerville . DNA damage could be attributed to metals and polycyclic aromatic hydrocarbons released near Laredo . Brains and gonads , two estrogen -dependent organs , were tested for aromatase activity with a tritiated water method . Brain aromatase activity was higher , though not always statistically , for male cave and male and female cliff swallows . Dichlorodiphenyldichloroethylene (DDE ) may play a role in the increased activity . Female cave swallows in Llano Grande appeared to have a greatly depressed brain aromatase activity , possibly attributed to past human use of toxaphene . Testicular and ovarian aromatase activity in cliff and cave swallows from Rio Grande was higher than in those from Somerville , though not always significantly . DDE , atrazine , sewage treatment plant contaminants (phthalates , alkylphenols , ethynylestradiol ) , metals , or other pollutants could play a role in the increased gonadal activity . Increased aromatase activity , in association with contaminants , may be easier to detect in testes of male birds which normally exhibit low levels of estrogen . Siterelated contaminants may be playing a role in DNA damage and aromatase alterations . This is the first known study which uses aromatase activity as an endocrine disruptor indicator in wild birds .
URI: http : / /hdl .handle .net /1969 .1 /3223
Date: 2006-04-12

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P450 aromatase alterations and DNA damage as avian pollution biomarkers in cliff and cave swallow breeding near the Rio Grande region, Texas. Available electronically from http : / /hdl .handle .net /1969 .1 /3223 .

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