Physiological and Ecological Studies on the Effects of Global Warming on Fish Reproduction

该项目涉及开展基础和应用研究，以了解高温对性别分化和性腺功能的作用机制，并制定方法监测和预测全球变暖对鱼类繁殖和自然鱼类种群的影响。在以下四个主要领域进行了研究。1)研究高温诱导的细胞凋亡在性别分化过程中的作用，特别是在热不稳定性性别决定中的作用，以及生殖细胞变性和消失的现象。总之，我们阐明了斑马鱼幼鱼细胞凋亡诱导的分子和细胞机制，以及斑马鱼幼鱼、幼鱼和青年鱼细胞凋亡的细胞和生化过程的动力学。很明显，性腺细胞的凋亡在两个物种的性腺性别分化中起着重要作用，特别是在温度依赖性性别决定中。 ...更多信息 佩杰里的时代。我们还表明，暴露于高温会引发青少年和成年人性腺细胞的快速凋亡反应，最终导致生殖细胞变性，生育能力降低，甚至在长期暴露期间不育。2)高温对性腺类固醇生成的影响及其与热不稳定性性别决定的相关性研究。我们克隆和其特征在于卵巢细胞色素p450芳香化酶（cyp 19 A1）基因在pejerrey和研究高温对基因表达的影响，这种重要的酶催化转换从男性到女性类固醇激素在性别分化过程中pejerrey和斑马鱼。高温抑制芳香化酶基因的表达，并与这两个物种的雄性化。芳香化酶抑制剂法倔唑的治疗也引起了雄性化，这一结果也强调了这种酶在卵巢分化中的作用。此外，我们确定在青鳉，性别分化过程中的低温和高温有协同和拮抗作用，分别与雌二醇，主要的女性类固醇激素。3)温度对脑-垂体-性腺轴发育和功能影响的研究。这些研究阐明了主要脑和垂体促性腺激素（GnRH，FSH，LH）及其受体的分子结构，并评估了它们在不同温度下与性腺性别分化的关系。结果表明，脑和垂体在性别分化和温度依赖性性别决定中的作用。4)开发监测天然鱼类种群中温度依赖性性别决定和生殖细胞退化表达的方法。我们澄清了耳石的化学成分和水温之间的关系，在日本和阿根廷的模式野生pejerrey种群的耳石微化学重建的热历史验证。我们还开发了一个SNP的性连锁标记在巴塔哥尼亚pejerrey和应用此标记的基因型和温度依赖性的性别决定在这个物种的温度的影响的研究。这些实例和本研究获得的丰富信息为研究全球变暖对天然鱼类种群繁殖的影响提供了依据。少

This project is concerned with the development of basic and applied research leading to the understanding of the mechanisms of action of high temperatures on sex differentiation and gonadal function, and the development of methods to monitor and forecast the effects of global warming on fish reproduction and natural fish populations. Research was conducted in four main areas as follows. 1) Study of the role of high temperature-induced apoptosis on the process of sex differentiation, particularly on thermolabile sex determination, and the phenomenon of germ cell degeneration and disappearance. In brief, we elucidated the molecular and cellular mechanisms of apoptosis induction in zebrafish larvae as well as the dynamics of cellular and biochemical process of apoptosis in pejerrey larvae, juveniles, and young adults. It became clear that apoptosis of gonadal cells plays an important role in gonadal sex differentiation in both species and particularly in temperature-dependent sex determin … More ation of pejerrey. We also showed that exposure to high temperatures triggers a quick apoptotic response in gonadal cells of juveniles and adults that eventually leads to germ cell degeneration, reduced fertility and even sterility during prolonged exposure. 2) Study of the effects of high temperatures on gonadal steroidogenesis and its relevance for thermolabile sex determination. We cloned and characterized the ovarian cytochrome p450 aromatase (cyp19A1) gene in pejerrey and examined the effect of high temperatures on the gene expression of this important enzyme catalyzing the conversion from male to female steroid hormones during sex differentiation in pejerrey and zebrafish. High temperature suppressed aromatase gene expression and was associated with masculinization in both species. Treatment with fadrozole, an aromatase inhibitor, also caused masculinization a result that also emphasizes the role of this enzyme in ovarian differentiation. Moreover, we determined in medaka that low and high temperatures during sex differentiation have synergistic and antagonistic effects, respectively, with estradiol, the main female steroid hormone. 3) Study of the effects of temperatures on the development and function of the brain-pituitary-gonad axis. These studies clarified the molecular structure of major brain and pituitary gonadotrophic hormones (GnRH, FSH, LH) and their receptors and evaluated their ontogeny in relation to gonadal sex differentiation at different temperatures. The results obtained suggest a role of the brain and pituitary in sex differentiation and temperature-dependent sex determination. 4) Development of methods to monitor expression of temperature-dependent sex determination and germ cell degeneration in natural fish populations. We clarified the relationship between the chemical composition of otoliths and water temperature in pejerrey and medaka and validated the technique of otolith microchemistry to reconstruct thermal history in model wild pejerrey populations from Japan and Argentina. We also developed a SNP sex-linked marker in Patagonian pejerrey and applied this marker to the study of the effects of temperature on genotypic and temperature-dependent sex determination in this species. These examples and the abundant information obtained in this study provide the basis for the study of the effects of global warming on the reproduction of natural fish populations. Less