CBET Research Group, Centre for Experimental Marine Biology and Biotechnology (PiE-UPV/EHU) and Zoology and Cell Biology Dept, (Faculty of Science and Technology), University of the Basque Country (UPV/EHU), E-48080, Bilbao, PO Box 644, Basque Country, Spain.
CBET Research Group, Centre for Experimental Marine Biology and Biotechnology (PiE-UPV/EHU) and Zoology and Cell Biology Dept, (Faculty of Science and Technology), University of the Basque Country (UPV/EHU), E-48080, Bilbao, PO Box 644, Basque Country, Spain.
Gen Comp Endocrinol. 2020 Feb 1;287:113339. doi: 10.1016/j.ygcen.2019.113339. Epub 2019 Nov 21.
The reproductive cycle of teleost fishes is regulated by the brain-pituitary-gonad (BPG) axis. The transcription profile of genes involved in the reproduction signalling in the BPG-axis differs in females and males during the gametogenic cycle. Impacts of endocrine disrupting chemicals on these signalling pathways in fish are known, but the participation of the BPG-axis in the development of the intersex condition is not well understood. Intersex thicklip grey mullets (Chelon labrosus) have been identified in several estuaries from the SE Bay of Biscay, revealing the presence of feminizing contaminants in the area. In previous studies, transcription patterns of genes related with steroidogenesis and gamete growth have been shown to differ among female, male and intersex mullets. However, many components of the reproduction control have not been studied yet. The aim of this study was to assess the transcription levels of target BPG-axis genes in female, male and intersex mullets captured in the polluted harbour of Pasaia, during their gametogenic cycle. After histologically examining the gonads, the transcription levels of previously sequenced target genes were measured by qPCR: kiss2, gpr54 and gnrh1 in brain, fshβ and lhβ in pituitary and fshr and lhr in gonads. In both females and males, brain genes were most transcribed in early gametogenesis, proving their relevance in the onset of both oogenesis and spermatogenesis. Pituitary gonadotropins in females showed upregulation as oogenesis progressed, reaching the highest transcription levels at vitellogenic stage, while in males transcript levels were constant during spermatogenesis. Transcription levels of gonadotropin receptors showed different patterns in ovaries and testes, suggesting differing function in relation to gametogenesis and maturation. Intersex mullets showed transcription levels of brain target genes similar to those observed in females at cortical alveoli stage and to those in mid spermatogenic males. In intersex testes the transcription pattern of gonadotropin receptor fshr was downregulated in comparison to non-intersex testes.
硬骨鱼类的生殖周期受脑-垂体-性腺（BPG）轴调控。在配子发生周期中，BPG 轴中参与生殖信号的基因的转录谱在雌性和雄性之间存在差异。已知内分泌干扰化学物质对鱼类这些信号通路的影响，但 BPG 轴在雌雄同体发育中的参与程度尚不清楚。在比斯开湾东南海域的几个河口已经发现了雌雄同体的厚唇灰鲻，这表明该地区存在致女性化的污染物。在以前的研究中，已经显示与类固醇生成和配子生长相关的基因的转录模式在雌性、雄性和雌雄同体的鲻鱼之间存在差异。然而，许多生殖控制的组成部分尚未得到研究。本研究的目的是评估在受污染的帕斯亚港捕获的处于配子发生周期的雌性、雄性和雌雄同体鲻鱼的 BPG 轴靶基因的转录水平。在对性腺进行组织学检查后，通过 qPCR 测量了先前测序的靶基因的转录水平：脑中的 kiss2、gpr54 和 gnrh1、垂体中的 fshβ 和 lhβ 以及性腺中的 fshr 和 lhr。在雌性和雄性中，脑基因在早期配子发生中转录水平最高，证明它们在卵发生和精子发生的开始中具有重要作用。随着卵母细胞发生的进行，雌性的垂体促性腺激素上调，在卵黄发生阶段达到最高转录水平，而在雄性中，在精子发生过程中转录水平保持不变。促性腺激素受体的转录水平在卵巢和睾丸中表现出不同的模式，这表明与配子发生和成熟有关的不同功能。雌雄同体的鲻鱼显示出与皮质肺泡阶段观察到的雌性相似的脑靶基因转录水平，以及与处于中期精子发生的雄性相似的转录水平。与非雌雄同体的睾丸相比，雌雄同体睾丸中促性腺激素受体 fshr 的转录模式下调。
