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Janer G Mesia-Vela S Wintermyer ML Cooper KR Kauffman FC Porte C 《Marine environmental research》2004,58(2-5):481-484
The esterification of two model vertebrate steroid hormones - estradiol (E2) and dehidroepiandrosterone (DHEA) - was studied in the oyster Crassostrea virginica. The activity of acyl-CoA:steroid acyltransferase was characterized in microsomal fractions isolated from oyster digestive glands. The apparent Km and Vmax values changed with the fatty acid acyl-CoA used (C20:4, C18:2, C18:1, C16:1, C18:0 or C16:0), and were in the range of 9-17 microM, and 35-74 pmol/min/mg protein for E2, and in the range of 45-120 microM, and 30-182 pmol/min/mg protein for DHEA. Kinetic parameters were also assessed in gonadal tissue. The enzyme saturated at similar concentrations, although conjugation rates were lower than in digestive gland. Preliminary data shows that tributyltin (TBT) in the low microM range (1-50) strongly inhibits E2 and DHEA esterification, the esterification of E2 being more sensitive to inhibition than that of DHEA. Overall, results indicate that apolar conjugation occurs in oysters, in both digestive gland and gonads, at a very similar rate to mammals, suggesting that this is a well conserved conjugation pathway during evolution. Esterification, together with other mechanisms, can modulate endogenous steroid levels in C. virginica, and might be a target for endocrine disrupters, such as TBT. 相似文献
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Despite scientific and public concern, research on food web contamination from chemicals in plastic is limited, and distinguishing plastic sources from prey remains a challenge. We analyzed juvenile yellowtail (Seriola lalandi) from the North Pacific Central Gyre for plastic ingestion and tissue concentrations of persistent organic pollutants and nonionic surfactants to investigate potential contamination from plastic exposure. Ingestion of synthetic debris occurred in ∼10% of the sample population. PCBs and DDTs were 352 ± 240 (mean ± SD) and 1425 ± 1118 ng/g lw, respectively. PBDEs were 9.08 ± 10.6 ng/g lw, with BDEs-47, 99, and 209 representing 90% of PBDEs. Nonylphenol (NP) was detected in one-third of the yellowtail with a mean of 52.8 ± 88.5 ng/g ww overall and 167 ± 72.3 ng/g ww excluding non-detects. Because environmental NP is strongly associated with wastewater treatment effluents, long-range transport is unlikely, and NP was previously measured in gyre plastic, we concluded that plastic-mediated exposure best explained our findings of NP in yellowtail. 相似文献
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Wintermyer M Skaidas A Roy A Yang YC Georgapoulos P Burger J Cooper K 《Marine environmental research》2005,60(2):133-152
A physiologically-based pharmacokinetic model (PBPK) was developed to describe the kinetics of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the eastern oyster (Crassostrea virginica). The estimated t(1/2) of elimination for a bolus dose of TCDD in C. virginica is approximately 14-24 days based on both the experimental data and the PBPK model. The highest dioxin concentration reached during 28-days was in the digestive gland followed by the mantle, gonad, hemolymph, gill, adductor muscle, and the kidney/heart. A binding protein for 2,3,7,8-TCDD had been reported in the literature for both the digestive gland and gonad. Incorporating a binding component in the model resulted in a better fit for the data. The PBPK model predicted the distribution and the elimination concentrations for 2,3,7,8-TCDD within each of the tissue compartments. This model will serve as a useful tool for predicting the kinetics of other persistent organic pollutants as well as, allow for a more refined ecological risk assessment by estimating dioxin concentrations in sensitive tissues such as the gonad. 相似文献
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Gemma Janer Sonia Mesia-Vela Margy L. Wintermyer Keith R. Cooper Fred C. Kauffman Cinta Porte 《Marine environmental research》2004,58(2-5):481
The esterification of two model vertebrate steroid hormones – estradiol (E2) and dehidroepiandrosterone (DHEA) – was studied in the oyster Crassostrea virginica. The activity of acyl-CoA:steroid acyltransferase was characterized in microsomal fractions isolated from oyster digestive glands. The apparent Km and Vmax values changed with the fatty acid acyl-CoA used (C20:4, C18:2, C18:1, C16:1, C18:0 or C16:0), and were in the range of 9–17 μM, and 35–74 pmol/min/mg protein for E2, and in the range of 45–120 μM, and 30–182 pmol/min/mg protein for DHEA. Kinetic parameters were also assessed in gonadal tissue. The enzyme saturated at similar concentrations, although conjugation rates were lower than in digestive gland. Preliminary data shows that tributyltin (TBT) in the low μM range (1–50) strongly inhibits E2 and DHEA esterification, the esterification of E2 being more sensitive to inhibition than that of DHEA. Overall, results indicate that apolar conjugation occurs in oysters, in both digestive gland and gonads, at a very similar rate to mammals, suggesting that this is a well conserved conjugation pathway during evolution. Esterification, together with other mechanisms, can modulate endogenous steroid levels in C. virginica, and might be a target for endocrine disrupters, such as TBT. 相似文献
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