Davidson W S, Huang T-K, Fujiki K, von Schalburg K R, Koop B F
Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, B.C., Canada.
Sex Dev. 2009;3(2-3):78-87. doi: 10.1159/000223073. Epub 2009 Aug 10.
Salmonids are descended from a common ancestor that underwent an autotetraploidization event. After a whole genome duplication species could deal with sex determination by deleting one copy of SEX, the sex determining locus, or by recruiting a duplicated transcription factor to become a novel sex determining gene. It is not known which if any of these strategies salmonids adopted, but it appears that they all have primarily a genetic mechanism of sex determination with male heterogamety. The sharing of sex-linked markers on the X and Y chromosomes and the difficulty in identifying Y-specific markers indicate that X and Y chromosomes in salmonids have a large pseudoautosomal region and a small sex determining region. Linkage analyses suggest that either SEX differs in different lineages or else has remained the same and moved by transposition to different chromosomes. The identification of the sex chromosomes in salmonid species has not resolved this issue. It is clear that salmonids are at an early stage in sex chromosome differentiation and therefore provide a wonderful opportunity to study the evolution of sex determination. The availability of a reference salmonid genome sequence would provide an important resource for research in this area.
鲑科鱼类起源于一个经历了自体四倍体化事件的共同祖先。在全基因组复制之后，物种可以通过删除性别决定位点SEX的一个拷贝，或者通过招募一个复制的转录因子成为一个新的性别决定基因来处理性别决定问题。目前尚不清楚鲑科鱼类采用了这些策略中的哪一种（如果有的话），但似乎它们都主要具有雄性异配性别的遗传性别决定机制。X和Y染色体上性别连锁标记的共享以及鉴定Y特异性标记的困难表明，鲑科鱼类的X和Y染色体具有一个大的拟常染色体区域和一个小的性别决定区域。连锁分析表明，要么SEX在不同谱系中不同，要么它保持不变并通过转座转移到不同的染色体上。鲑科物种性染色体的鉴定尚未解决这个问题。很明显，鲑科鱼类正处于性染色体分化的早期阶段，因此为研究性别决定的进化提供了一个绝佳的机会。参考鲑科鱼类基因组序列的可用性将为该领域的研究提供重要资源。
