Abstract
Sentinel fish hornyhead turbot ( Pleuronichthys verticalis ) captured near wastewater outfalls are used for monitoring exposure to industrial and agricultural chemicals of ~ 20 million people living in coastal Southern California. Although analyses of hormones in blood and organ morphology and histology are useful for assessing contaminant exposure, there is a need for quantitative and sensitive molecular measurements, since contaminants of emerging concern are known to produce subtle effects. We developed a second generation multi-species microarray with expanded content and sensitivity to investigate endocrine disruption in turbot captured near wastewater outfalls in San Diego, Orange County and Los Angeles California. Analysis of expression of genes involved in hormone [e.g., estrogen, androgen, thyroid] responses and xenobiotic metabolism in turbot livers was correlated with a series of phenotypic end points. Molecular analyses of turbot livers uncovered altered expression of vitellogenin and zona pellucida protein, indicating exposure to one or more estrogenic chemicals, as well as, alterations in cytochrome P450 (CYP) 1A, CYP3A and glutathione S-transferase-α indicating induction of the detoxification response. Molecular responses indicative of exposure to endocrine disruptors were observed in field-caught hornyhead turbot captured in Southern California demonstrating the utility of molecular methods for monitoring environmental chemicals in wastewater outfalls. Moreover, this approach can be adapted to monitor other sites for contaminants of emerging concern in other fish species for which there are few available gene sequences.
Highlights
Many synthetic chemicals alter endocrine responses in humans and wildlife causing adverse effects on development, reproduction and the incidence of diseases such as diabetes and hypertension [1,2,3,4,5,6,7,8]
We utilized a series of quality control metrics to validate the second generation microarray with turbot (Agilent ink jet oligonucleotide) and compared its performance to the prototype we described previously (Figure 1)
The large number of points centered on the origin indicates that 2-fold and higher changes when measured by the spotted oligonucleotide array are robust
Summary
Many synthetic chemicals alter endocrine responses in humans and wildlife causing adverse effects on development, reproduction and the incidence of diseases such as diabetes and hypertension [1,2,3,4,5,6,7,8] These chemicals are called endocrine disruptors, and they include plasticizers, such as phthalates and alkylphenols, pesticides, fungicides, detergents, dioxin, polychlorinated biphenyls and pharmaceuticals, such as the synthetic estrogen 17α-ethinylestradiol. These and other chemicals from municipal wastewater treatment and industrial sources are discharged into rivers, lakes and the ocean, where they accumulate in aquatic species [9]. There is much concern about the effects of elevated concentrations of xenobiotics in the environment on human health because exposure to endocrine disruptors may lead to premature puberty in females [5,10,11], and decreased reproductive ability in men [12,13]
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