Similar but not the same: insights into the evolutionary history of paralogous sex-determining genes of the dwarf honey bee Apis florea
Similar but not the same: insights into the evolutionary history of paralogous sex-determining genes of the dwarf honey bee Apis florea
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DOI：
10.1038/hdy.2015.60
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发表时间：
2015-07
期刊：
影响因子：
3.8
通讯作者：
M. Biewer;Sarah Lechner;Martin Hasselmann
中科院分区：
文献类型：
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作者：
M. Biewer;Sarah Lechner;Martin Hasselmann
研究复制基因的命运提供了对它们所属生物路径的进化可塑性的信息洞察。在蜜蜂属的性别决定基因互补性别决定基因(CSD)和雌性化基因(Fem)中，只有杂合子CSD才能启动雌性发育。在这里，描述了系统发育基础上的矮小蜜蜂Apis Florea的基因CSD和fem的全长编码序列。与其他蜜蜂物种相比，在蛋白质相互作用(卷曲线圈)基序的形成和定位以及编码CSD特征高变区(HVR)的氨基酸方面观察到了显著的进化变化。此外，从随机人群样本中分离出功能不同的CSD等位基因作为基因组片段。在预测的潜在特定域中，πN/πS=1.6时为正选择，而在其他蜜蜂物种中普遍存在的平衡选择的迹象缺失。同义和全基因组非编码点的低核苷酸多样性以及位置频率分析表明，黄曲霉的遗传漂移具有强烈的影响，可能与其生物学有关。沿着大约3000万年CSD进化的进化轨迹，间歇性的多样化选择似乎在不同的Apis分支中起到了不同的作用。在功能杂合型CSD等位基因中，PSD内的氨基酸差异一直很低，这表明HVR是决定等位基因特异性的最重要的区域。我们认为，在蜜蜂产生CSD的谱系特异性FEM复制的早期历史中，黄蜂CSD是初始性别决定信号可塑性的一个显著例子。
Studying the fate of duplicated genes provides informative insight into the evolutionary plasticity of biological pathways to which they belong. In the paralogous sex-determining genes complementary sex determiner (csd) and feminizer (fem) of honey bee species (genus Apis), only heterozygous csd initiates female development. Here, the full-length coding sequences of the genes csd and fem of the phylogenetically basal dwarf honey bee Apis florea are characterized. Compared with other Apis species, remarkable evolutionary changes in the formation and localization of a protein-interacting (coiled-coil) motif and in the amino acids coding for the csd characteristic hypervariable region (HVR) are observed. Furthermore, functionally different csd alleles were isolated as genomic fragments from a random population sample. In the predicted potential specifying domain (PSD), a high ratio of π N/π S= 1.6 indicated positive selection, whereas signs of balancing selection, commonly found in other Apis species, are missing. Low nucleotide diversity on synonymous and genome-wide, non-coding sites as well as site frequency analyses indicated a strong impact of genetic drift in A. florea, likely linked to its biology. Along the evolutionary trajectory of~ 30 million years of csd evolution, episodic diversifying selection seems to have acted differently among distinct Apis branches. Consistently low amino-acid differences within the PSD among pairs of functional heterozygous csd alleles indicate that the HVR is the most important region for determining allele specificity. We propose that in the early history of the lineage-specific fem duplication giving rise to csd in Apis, A. florea csd stands as a remarkable example for the plasticity of initial sex-determining signals.