Natural variation of the Y chromosome suppresses sex ratio distortion and modulates testis-specific gene expression in Drosophila simulans

Date Published:

Abstract:

X-linked sex-ratio distorters that disrupt spermatogenesis can cause a deficiency in functional Y-bearing sperm and a female-biased sex ratio. Y-linked modifiers that restore a normal sex ratio might be abundant and favored when a X-linked distorter is present. Here we investigated natural variation of Y-linked suppressors of sex-ratio in the Winters systems and the ability of these chromosomes to modulate gene expression in Drosophila simulans. Seventy-eight Y chromosomes of worldwide origin were assayed for their resistance to the X-linked sex-ratio distorter gene Dox. Y chromosome diversity caused males to sire approximately 63% to approximately 98% female progeny. Genome-wide gene expression analysis revealed hundreds of genes differentially expressed between isogenic males with sensitive (high sex ratio) and resistant (low sex ratio) Y chromosomes from the same population. Although the expression of about 75% of all testis-specific genes remained unchanged across Y chromosomes, a subset of post-meiotic genes was upregulated by resistant Y chromosomes. Conversely, a set of accessory gland-specific genes and mitochondrial genes were downregulated in males with resistant Y chromosomes. The D. simulans Y chromosome also modulated gene expression in XXY females in which the Y-linked protein-coding genes are not transcribed. The data suggest that the Y chromosome might exert its regulatory functions through epigenetic mechanisms that do not require the expression of protein-coding genes. The gene network that modulates sex ratio distortion by the Y chromosome is poorly understood, other than that it might include interactions with mitochondria and enriched for genes expressed in post-meiotic stages of spermatogenesis.

Notes:

Branco, A TTao, YHartl, D LLemos, BengGM079536/GM/NIGMS NIH HHS/R01 GM065169/GM/NIGMS NIH HHS/R01 HD060679/HD/NICHD NIH HHS/Research Support, N.I.H., ExtramuralEngland2013/04/18 06:00Heredity (Edinb). 2013 Jul;111(1):8-15. doi: 10.1038/hdy.2013.5. Epub 2013 Apr 17.