Data from: Y-linked variation for autosomal immune gene regulation has the potential to shape sexually dimorphic immunity

Sexually dimorphic phenotypes arise from the differential expression of male and female shared genes throughout the genome. Unfortunately, the underlying molecular mechanisms by which dimorphic regulation manifests and evolves are unclear. Recent work suggests that Y-chromosomes may play an important role; given that Drosophila melanogaster Y’s were shown to influence the regulation of hundreds of X and autosomal genes. For Y-linked regulatory variation (YRV) to facilitate sexually dimorphic evolution, however, it must exist within populations (where selection operates) and influence male fitness. These criteria have seldom been investigated, leaving the potential for dimorphic evolution via YRV unclear. Interestingly, male and female D. melanogaster differ in immune-gene regulation. Furthermore, immune-gene regulation appears to be influenced by the Y-chromosome, suggesting it may contribute to dimorphic immune evolution. We address this possibility by introgressing Y-chromosomes from a single wild population into an isogenic background (to create Y-lines) and assessing immune-gene regulation and bacterial defense. We found that Y-line males differed in their immune-gene regulation and their ability to defend against Serratia marcescens. Moreover, gene expression and bacterial defense were positively genetically correlated. These data indicate that the Y-chromosome has the potential to shape the evolution of sexually dimorphic immunity in this system.性二态表型（Sexually dimorphic phenotypes）源自全基因组范围内雌雄共有基因的差异表达。遗憾的是，介导二态调控形成与演化的潜在分子机制仍不明确。近期研究提示Y染色体或扮演关键角色：已有研究证实黑腹果蝇（Drosophila melanogaster）的Y染色体可调控数百个X染色体与常染色体基因的表达。然而，若要使Y连锁调控变异（Y-linked regulatory variation, YRV）能够促进性二态性状的演化，其必须在种群中存在（即自然选择可在该种群中发挥作用）并影响雄性适合度。但该判定条件极少得到验证，因此YRV介导性二态演化的潜力仍不明确。有趣的是，雌雄黑腹果蝇的免疫基因调控模式存在差异；且免疫基因调控似乎受Y染色体影响，提示YRV或参与了性二态免疫性状的演化。为验证这一可能性，本研究将单一野生种群的Y染色体导入等基因背景以构建Y染色体系（Y-lines），并以此评估免疫基因调控与细菌防御能力。研究发现，不同Y染色体系的雄性果蝇在免疫基因调控模式以及对抗粘质沙雷氏菌（Serratia marcescens）的防御能力上均存在显著差异。此外，基因表达水平与细菌防御能力呈显著正遗传相关。上述数据表明，Y染色体具备塑造本研究体系中性二态免疫性状演化的潜力。