Vitellogenin (Vtg), a large multidomain protein precursor of egg-yolk proteins, is used as an endocrine disruption biomarker in fish, and in the last decades, its use has been extended to invertebrates like mollusks. However, it remains unclear whether invertebrate endocrine system produces Vtg in response to estrogens, like it occurs in oviparous vertebrates. In a previous study, no evidence of induction of Vtg expression at protein level was found in gonads of the marine mussel Mytilus galloprovincialis after exposure to the estrogenic chemical 17α-ethinylestradiol (EE2). In the present follow-up study, it was investigated whether there is any effect of EE2 on Vtg abundance at transcriptional level in M. galloprovincialis gonads. To this aim, RT-qPCR analysis targeting three different domains of Vtg transcript was performed on gonads of mussels that were exposed either 4 or 24 days to 100 ng/L EE2. In addition, several reference genes were analysed and a selection of these for potential use in further RT-qPCR analyses on mussel male and female gonads is provided. Results showed higher expression in females than in males for the three analysed Vtg domains, and no evidence of Vtg mRNA induction due to EE2 either in females or males. The present results, together with those obtained from previous analysis at protein level, support that Vtg is not an adequate biomarker for xenoestrogenicity in marine mussels. Additionally, nucleotide sequences of Vtg transcripts of three closely-related species from Mytilus edulis complex (M. galloprovincialis, M. edulis and M. trossulus) are provided and compared with Vtg sequences from other mollusk species to assess the level of conservation and evolutionary relationships among species.

卵黄蛋白（Vtg）是卵黄蛋白的大型多结构域蛋白前体，被用作鱼类的内分泌干扰生物标志物，在最近的几十年中，其用途已扩展到无脊椎动物，如软体动物。然而，尚不清楚无脊椎动物的内分泌系统是否会产生对雌激素的反应的Vtg，就像它在卵生脊椎动物中一样。在先前的研究中，在暴露于雌激素化学物质17α-炔雌醇（EE2）之后，在海洋贻贝Mytilus galloprovincialis的性腺中未发现在蛋白质水平诱导Vtg表达的证据。在目前的后续研究中，研究了EE2对鸡生殖支原体中转录水平的Vtg丰度是否有任何影响。性腺。为此，对贻贝的性腺进行了针对Vtg转录本三个不同域的RT-qPCR分析，该贻贝的性腺暴露于100 ng / L EE2的第4天或第24天。此外，还分析了几种参考基因，并提供了一些可供进一步在贻贝雄性和雌性性腺进行RT-qPCR分析中使用的参考基因。结果显示，在三个分析的Vtg结构域中，女性的表达高于男性，并且没有证据表明在雌性或雄性中由于EE2引起的Vtg mRNA诱导。目前的结果，以及从蛋白质水平的先前分析获得的结果，均支持Vtg并不是海洋贻贝异种雌激素性的适当生物标记。此外，来自Mytilus edulis复合体的三个密切相关物种的Vtg转录物的核苷酸序列（提供了M. galloprovincialis，M。edulis和M. trossulus，并将其与其他软体动物物种的Vtg序列进行比较，以评估物种之间的保守性和进化关系。