Environment and sex determination in farmed fish
Environment and sex determination in farmed fish
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DOI：
10.1016/s1532-0456(01)00267-8
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发表时间：
2001-12-01
影响因子：
3.9
通讯作者：
D'Cotta, H
中科院分区：
文献类型：
--
作者：
Baroiller, JF;D'Cotta, H
性腺性别分化的可塑性在20世纪30年代被报道在鱼类外源类固醇治疗后，但证明环境因素（温度，pH值，密度和社会相互作用）可以影响性别比例在gonochoristic物种已经相对较新。在鱼类中，就像在爬行动物和两栖动物中显示环境性别决定一样，影响性别的主要环境因素似乎是温度（TSD =温度性别决定）。在大多数温度敏感的物种（一些Atherinids，Poecilids，慈鲷：罗非鱼，金鱼，Siluriform，比目鱼.）雌雄比例随温度增加和/或卵巢分化由低温诱导。相反，在一些稀有物种（Dicentrarchus labrax，Ictalurus punctatus）中，高温可能会产生女性偏向的性别比例和/或低温促进男性偏向的性别比例。高温和低温均能诱导出单性的牙鲆雄鱼种群，而中温则产生1：1的性比（U型曲线）。鱼类显示其TSD模式的特殊性，因为单性种群一般不会在极端温度下产生，这表明存在强烈的温度/基因型相互作用。在显示TSD的爬行动物、两栖动物和鱼类中，温度处理必须在关键敏感期应用，相对类似于激素敏感期。在雌雄异株鱼类中，雌鱼体内的雌激素和雄鱼体内的11-氧合雄激素可能是调节性腺性别分化的关键生理步骤。细胞色素P450-芳香化酶是催化雄激素转化为雌激素的酶，似乎是卵巢分化的关键酶。温度敏感性的分子机制已在两个物种罗非鱼Oreochromis niloticus和Hirame中得到解决，其中芳香化酶基因表达通过雄性化温度处理而下调。此外，在罗非鱼中，11 β-羟化酶（参与11-氧化雄激素合成的关键酶）的基因表达似乎不受温度处理的影响。(C)2001 Elsevier Science Inc. All rights reserved.
A plasticity of gonadal sex differentiation was reported in the 1930s following exogenous steroid treatments in fish, but demonstration that environmental factors (temperature, pH, density and social interactions) could influence the sex ratio in gonochoristic species has been relatively recent. In fish, as in reptiles and amphibians displaying environmental sex determination, the main environmental factor influencing sex seems to be temperature (TSD = Temperature Sex Determination). In most thermosensitive species (some Atherinids, Poecilids, Cichlids: tilapias, goldfish, a Siluriform, a flatfish...) male to female ratio increases with temperature and/or ovarian differentiation is induced by low temperatures. Conversely, in some rare species (Dicentrarchus labrax, Ictalurus punctatus), high temperatures may produce female-biased sex ratios and/or low temperatures promote male-biased sex ratios. In the hirame Paralichthys olivaceus, both high and low temperatures induce monosex male populations while intermediate temperatures yield a 1:1 sex ratio (U-shape curve). Fish show particularities in their TSD patterns since mono-sex populations are generally not produced at extreme temperatures, suggesting the existence of strong temperature/genotype interactions. In reptiles, amphibians and fish displaying TSD, temperature treatments must be applied at a critical sensitive period, relatively similar to the hormone sensitive period. In gonochoristic fish, steroid hormones with estrogens in females and 11-oxygenated andro-ens in males, are probably key physiological steps in the regulation of gonadal sex differentiation. Cytochrome P450-aromatase, enzyme catalysing conversion of androgens to estrogens, seems to be a critical enzyme for ovarian differentiation. Molecular mechanisms of thermosensitivity have been addressed in two species tilapia Oreochromis niloticus and the hirame, where aromatase gene expression is down-regulated by masculinizing temperature treatments. Furthermore, in tilapia the gene expression of 11 beta -hydroxylase (a key enzyme involved in the synthesis of 11-oxygenated androgens) does not appear to be affected by temperature treatments. (C) 2001 Elsevier Science Inc. All rights reserved.