Nagabhushana A, Mishra Rakesh K
Centre for Cellular and Molecular Biology, Council of Scientific and industrial Research, Uppal Road, Hyderabad 500007, India.
J Biosci. 2016 Mar;41(1):145-55. doi: 10.1007/s12038-016-9593-1.
How sex is determined has been one of the most intriguing puzzles in biology since antiquity. Although a fundamental process in most metazoans, there seems to be myriad of ways in which sex can be determined - from genetic to environmental sex determination. This variation is limited mainly to upstream triggers with the core of sex determination pathway being conserved. Zebrafish has gained prominence as a vertebrate model system to study development and disease. However, very little is known about its primary sex determination mechanism. Here we review our current understanding of the sex determination in zebrafish. Zebrafish lack identifiable heteromorphic sex chromosomes and sex is determined by multiple genes, with some influence from the environment. Recently, chromosome 4 has been identified as sex chromosome along with few sex-linked loci on chromosomes 5 and 16. The identities of candidate sex-linked genes, however, have remained elusive. Sex in zebrafish is also influenced by the number of meiotic oocytes in the juvenile ovary, which appear to instruct retention of the ovarian fate. The mechanism and identity of this instructive signal remain unknown. We hypothesize that sex in zebrafish is a culmination of combinatorial effects of the genome, germ cells and the environment with inputs from epigenetic factors translating the biological meaning of this interaction.
自古以来，性别如何决定一直是生物学中最引人入胜的谜题之一。尽管这是大多数后生动物的一个基本过程，但性别决定的方式似乎多种多样——从基因性别决定到环境性别决定。这种变化主要局限于上游触发因素，而性别决定途径的核心是保守的。斑马鱼作为研究发育和疾病的脊椎动物模型系统已受到广泛关注。然而，对于其主要的性别决定机制我们知之甚少。在此，我们综述了目前对斑马鱼性别决定的理解。斑马鱼缺乏可识别的异形性染色体，性别由多个基因决定，同时受到环境的一些影响。最近，4号染色体已被确定为性染色体，同时在5号和16号染色体上也发现了一些性连锁位点。然而，候选性连锁基因的身份仍然难以确定。斑马鱼的性别还受到幼年卵巢中减数分裂卵母细胞数量的影响，这些卵母细胞似乎决定了卵巢命运的维持。这种指导性信号的机制和身份仍然未知。我们推测，斑马鱼的性别是基因组、生殖细胞和环境的组合效应的结果，表观遗传因素的输入转化了这种相互作用的生物学意义。
