Lack of global meiotic sex chromosome inactivation, and paucity of tissue-specific gene expression on the Drosophila X chromosome

BMC Biology

Research Article

Lyudmila M Mikhaylova¹  Dmitry I Nurminsky² 

[1] Department of Anatomy and Cellular Biology, Tufts University School of Medicine, Boston, USA;Department of Anatomy and Cellular Biology, Tufts University School of Medicine, Boston, USA;Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, USA;

关键词: Dosage Compensation;    Testis Development;    Accessory Gland;    Autosomal Gene;    Dosage Compensation Complex;   

DOI  :  10.1186/1741-7007-9-29

 received in 2011-04-07, accepted in 2011-05-04,  发布年份 2011

来源: Springer

【 摘 要 】

BackgroundPaucity of male-biased genes on the Drosophila X chromosome is a well-established phenomenon, thought to be specifically linked to the role of these genes in reproduction and/or their expression in the meiotic male germline. In particular, meiotic sex chromosome inactivation (MSCI) has been widely considered a driving force behind depletion of spermatocyte-biased X-linked genes in Drosophila by analogy with mammals, even though the existence of global MCSI in Drosophila has not been proven.ResultsMicroarray-based study and qRT-PCR analyses show that the dynamics of gene expression during testis development are very similar between X-linked and autosomal genes, with both showing transcriptional activation concomitant with meiosis. However, the genes showing at least ten-fold expression bias toward testis are significantly underrepresented on the X chromosome. Intriguingly, the genes with similar expression bias toward tissues other than testis, even those not apparently associated with reproduction, are also strongly underrepresented on the X. Bioinformatics analysis shows that while tissue-specific genes often bind silencing-associated factors in embryonic and cultured cells, this trend is less prominent for the X-linked genes.ConclusionsOur data show that the global meiotic inactivation of the X chromosome does not occur in Drosophila. Paucity of testis-biased genes on the X appears not to be linked to reproduction or germline-specific events, but rather reflects a general underrepresentation of tissue-biased genes on this chromosome. Our analyses suggest that the activation/repression switch mechanisms that probably orchestrate the highly-biased expression of tissue-specific genes are generally not efficient on the X chromosome. This effect, probably caused by dosage compensation counteracting repression of the X-linked genes, may be the cause of the exodus of highly tissue-biased genes to the autosomes.

【 授权许可】

CC BY   
© Mikhaylova and Nurminsky; licensee BioMed Central Ltd. 2011