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Open Access Research article

Adaptive evolution of SCML1 in primates, a gene involved in male reproduction

Hai-hui Wu123 and Bing Su12*

Author Affiliations

1 State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, PR China

2 Kunming Primate Research Center, Chinese Academy of Sciences, Kunming, Yunnan, PR China

3 Graduate School of Chinese Academy of Sciences, Beijing, PR China

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BMC Evolutionary Biology 2008, 8:192  doi:10.1186/1471-2148-8-192

Published: 5 July 2008

Abstract

Background

Genes involved in male reproduction are often the targets of natural and/or sexual selection. SCML1 is a recently identified X-linked gene with preferential expression in testis. To test whether SCML1 is the target of selection in primates, we sequenced and compared the coding region of SCML1 in major primate lineages, and we observed the signature of positive selection in primates.

Results

We analyzed the molecular evolutionary pattern of SCML1 in diverse primate species, and we observed a strong signature of adaptive evolution which is caused by Darwinian positive selection. When compared with the paralogous genes (SCML2 and SCMH1) of the same family, SCML1 evolved rapidly in primates, which is consistent with the proposed adaptive evolution, suggesting functional modification after gene duplication. Gene expression analysis in rhesus macaques shows that during male sexual maturation, there is a significant expression change in testis, implying that SCML1 likely plays a role in testis development and spermatogenesis. The immunohistochemical data indicates that SCML1 is preferentially expressed in germ stem cells of testis, therefore likely involved in spermatogenesis.

Conclusion

The adaptive evolution of SCML1 in primates provides a new case in understanding the evolutionary process of genes involved in primate male reproduction.