Arunkumar K P, Mita Kazuei, Nagaraju J
Centre of Excellence for Genetics and Genomics of Silkmoths, Laboratory of Molecular Genetics, Centre for DNA Fingerprintingand Diagnostics, Tuljaguda, Nampally, Hyderabad, India.
Genetics. 2009 Jun;182(2):493-501. doi: 10.1534/genetics.108.099994. Epub 2009 Mar 30.
The role of sex chromosomes in sex determination has been well studied in diverse groups of organisms. However, the role of the genes on the sex chromosomes in conferring sexual dimorphism is still being experimentally evaluated. An unequal complement of sex chromosomes between two sexes makes them amenable to sex-specific evolutionary forces. Sex-linked genes preferentially expressed in one sex over the other offer a potential means of addressing the role of sex chromosomes in sexual dimorphism. We examined the testis transcriptome of the silkworm, Bombyx mori, which has a ZW chromosome constitution in the female and ZZ in the male, and show that the Z chromosome harbors a significantly higher number of genes expressed preferentially in testis compared to the autosomes. We hypothesize that sexual antagonism and absence of dosage compensation have possibly led to the accumulation of many male-specific genes on the Z chromosome. Further, our analysis of testis-specific paralogous genes suggests that the accumulation on the Z chromosome of genes advantageous to males has occurred primarily by translocation or tandem duplication.
性染色体在性别决定中的作用已在多种生物群体中得到充分研究。然而，性染色体上的基因在赋予两性异形方面的作用仍在通过实验进行评估。两性之间性染色体的互补不均等，使得它们容易受到性别特异性进化力量的影响。在一种性别中比另一种性别优先表达的性连锁基因，为研究性染色体在两性异形中的作用提供了一种潜在方法。我们研究了家蚕（Bombyx mori）的睾丸转录组，家蚕雌性具有ZW染色体组成，雄性具有ZZ染色体组成，结果表明，与常染色体相比，Z染色体上优先在睾丸中表达的基因数量明显更多。我们推测，性拮抗和剂量补偿的缺失可能导致了许多雄性特异性基因在Z染色体上的积累。此外，我们对睾丸特异性旁系同源基因的分析表明，对雄性有利的基因在Z染色体上的积累主要是通过易位或串联重复发生的。
