Expression of vitellogenin gene (vtg) is used as a biomarker for the evaluation of the exposure of estrogenic substances in fish. However, scientific information regarding this biomarker in Neotropical fish is limited. In this study, a 760 bp partial sequence of the vtg mRNA from the liver of the catfish Rhamdia quelen was cloned, representing almost 20% of the full-length vtg. The phylogenetic tree analysis recovered the vtg of R. quelen inside the clade of Siluriformes. The alignment of the deduced amino acid sequence of R. quelen vtg with other species confirmed that the described sequence is gene specific. Also, this cloned sequence presents almost 70% of identity with the vtgI subtype, that is known to translate into the incomplete form of Vtg due to the lack of the two domains, the β’-c and the Ct. Moreover, from the cloning and sequencing of vtg of R. quelen, a protocol for a RT-qPCR was developed with the goal to be applied as a biomarker of the hypothalamic-pituitary-gonad-liver (HPGL) axis, in order to evaluate the effects of endocrine disruptor exposure in Neotropical fish. Thus, this protocol was applied in the effects of a dose of 10 mg/kg of 17β-estradiol (E2) on vtg expression in male and female fish. The results showed that after 17 days of the exposure injection the E2 treatment upregulated vtg expression in both sexes. No observed differences in the levels of gene expression between the male and female fish were observed, and no statistical interaction between E2-treatment and sex were found. The results obtained from cloning add new information regarding vtg in Siluriformes fish, an order poorly studied in this aspect. Also, the vtg RT-qPCR protocol stablished for vtg of R. quelen will expand the application of this animal model, a Neotropical fish, in investigation regarding the effects of endocrine disruptors.

中文翻译：

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新热带鲶鱼Rhamdia quelen肝卵黄蛋白原基因的克隆、部分测序和17β-雌二醇调节

v itellogenin基因 ( vtg ) 的表达被用作评估鱼类雌激素物质暴露的生物标志物。然而，关于新热带鱼中这种生物标志物的科学信息是有限的。在这项研究中，克隆了来自鲶鱼Rhamdia quelen肝脏的vtg mRNA的 760 bp 部分序列，几乎占全长vtg 的20% 。进化树分析回收的VTG的R. quelen鲶的分支内。R的推导氨基酸序列的比对。皇后乐队与其他物种确认所描述的序列是基因特异性的。此外，该克隆序列与vtgI亚型具有几乎 70% 的同一性，已知由于缺少 β'-c 和 Ct 两个结构域而转化为不完整形式的 Vtg。而且，从克隆和测序VTG的R. quelen，用于RT-qPCR的一个协议是与目标开发的应用为下丘脑-垂体-性腺-中肝脏（HPGL）轴的生物标志物，以评价内分泌干​​扰物暴露对新热带鱼的影响。因此，该协议适用于 10 mg/kg 17β-雌二醇 (E2) 对vtg 的影响雄鱼和雌鱼的表达。结果表明，在暴露注射 17 天后，E2 处理上调了两种性别的vtg表达。没有观察到雄性和雌性鱼之间基因表达水平的差异，并且没有发现 E2 处理和性别之间的统计相互作用。克隆获得的结果增加了有关鲶形目鱼类vtg 的新信息，这方面的研究很少。此外，为R. quelen 的vtg建立的vtg RT-qPCR 协​​议将扩大这种动物模型（一种新热带鱼）在内分泌干扰物影响研究中的应用。