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Black turtle plasmatic vitellogenin (VTG) was purified from 17beta-estradiol-induced males using ion-exchange chromatography. The isolated protein was identified as VTG by its glycolipoprotein nature and amino acid sequence homology with other vertebrate VTG. It was characterized as a 500-kDa dimer composed of two identical, 200- to 240-kDa monomers. Polyclonal antibodies raised against black turtle VTG showed high titer and specificity, as demonstrated by enzyme-linked immunosorbent assay and Western blot analysis, respectively. The range of the assay was estimated to be between 15 ng/ml and 2 microg/ml, and the inter- and intra-assay coefficients of variation were 9.4 and 7.3%, respectively. Black turtle antibody cross-reacted with VTG of two other sea turtle species, Caretta caretta (loggerhead) and Eretmochelys imbricata (hawksbill), extending the applicability of the assay as part of a sea turtle health assessment program.

The oyster's reproductive process is poorly documented, especially in terms of a quantitative approach. In recent years, investigations with this species have been directed at determining important reproductive factors.Within this scope, techniques that allow standardized and accurate quantitative estimations of gonad development have become of primary importance. In this study, the histological characteristics and the levels of vitellin/vitellogenin-like proteins (Vn/Vtg) from ovaries of the Mexican Paci¢c 'pleasure' oyster Crassostrea corteziensis (Hertlein 1951) were analysed during di¡erent stages of gonad maturation using quantitative histological techniques and an enzyme-linked immunosorbent assay. This was performed in order to evaluate a possible quantitative tool to predict the degrees of gonad maturity and to analyse the biological implications of the ¢ndings relative not only to broodstock conditioning but also to natural populations. Using this information, we expect to be able to undertake further research on di¡erent reproductive aspects of this oyster species, including, among others, evaluation of the response in Vn/Vtg concentrations to di¡erent diets and environmental conditions during laboratory conditioning.

This study evaluated organismal toxicity, cytotoxicity, and genotoxicity and the filtration rate in response to different concentrations of subchronic lindane (gamma-hexachlorocyclohexane [gamma-HCH]), exposure (12 d) in adult Pacific oysters Crassostrea gigas. Oysters were exposed in vivo in laboratory aquaria to 10 different concentrations (0.0-10.0 mg/L) of gamma-HCH. The median lethal concentration (LC50) after 12 d was calculated as 2.22 mg/L. Cytotoxic effects were observed in hemocytes, where the mean cell viability was significantly decreased at 1.0 mg/L of gamma-HCH after 12 d. Genotoxicity of gamma-HCH measured by single cell gel electrophoresis assay, in hemocytes was evident at 0.7 mg/L of gamma-HCH after 12 d. After 4 h of exposure to gamma-HCH, filtration rates were reduced compared with controls to 65.8 and 38.2% at concentrations of 0.3 and 0.7 mg/L, respectively, and after 11 d of exposure, filtration rates were reduced to 60.4 and 30.9% at concentrations of 0.1 mg/L and higher. These results show the subchronic effects of gamma-HCH at different concentrations and effect sensitivities are categorized as filtration rate < genotoxicity < cytotoxicity < mortality. The relevance of integral toxicity evaluation, considering different endpoints from molecular, cellular, and individual levels is discussed.

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