The Goddard and Saturn Genes Are Essential for Drosophila Male Fertility and May Have Arisen De Novo
The Goddard and Saturn Genes Are Essential for Drosophila Male Fertility and May Have Arisen De Novo
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DOI：
10.1093/molbev/msx057
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发表时间：
2017-05-01
影响因子：
10.7
通讯作者：
Findlay, Geoffrey D.
中科院分区：
文献类型：
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作者：
Gubala, Anna M.;Schmitz, Jonathan F.;Findlay, Geoffrey D.
新基因通过各种机制产生，包括复制现有基因和从非编码DNA序列中从头产生基因。虽然有许多具有重要功能作用的重复基因的例子，但从头基因的功能在很大程度上仍未被探索。许多新进化的基因在男性生殖道中表达，这表明这些进化创新可能为经历性别选择的男性提供优势。利用睾丸特异的RNA干扰，我们筛选了11个果蝇中可能的从头基因对男性生育能力的影响，并确定了两个基因，Goddard和saturn，它们对精子发生和精子功能是必不可少的。戈达德基因敲除(KD)雄性不能产生成熟的精子，而土星KD雄性产生的精子很少，一旦转移到雌性身上，这些功能就会变得低效。与从头开始的起源一致，这两个基因只能在果蝇中识别，并被预测编码的蛋白质与任何注释的蛋白质没有序列相似性。然而，由于高度的分歧阻碍了对每个基因产生的非编码序列的明确识别，我们认为戈达德和土星是假定的从头基因。在果蝇体内，这两个基因在某些谱系中已经丢失，但在发现它们的物种中显示出保守的、男性特有的表达模式。戈达德一直存在于单拷贝中，并在净化选择下进化。相比之下，土星通过基因复制和正向选择实现了多样化。这些数据表明，从头基因可以在男性生殖中发挥重要作用。
New genes arise through a variety of mechanisms, including the duplication of existing genes and the de novo birth of genes from noncoding DNA sequences. While there are numerous examples of duplicated genes with important functional roles, the functions of de novo genes remain largely unexplored. Many newly evolved genes are expressed in the male reproductive tract, suggesting that these evolutionary innovations may provide advantages to males experiencing sexual selection. Using testis-specific RNA interference, we screened 11 putative de novo genes in Drosophila melanogaster for effects on male fertility and identified two, goddard and saturn, that are essential for spermatogenesis and sperm function. Goddard knockdown (KD) males fail to produce mature sperm, while saturn KD males produce few sperm, and these function inefficiently once transferred to females. Consistent with a de novo origin, both genes are identifiable only in Drosophila and are predicted to encode proteins with no sequence similarity to any annotated protein. However, since high levels of divergence prevented the unambiguous identification of the noncoding sequences from which each gene arose, we consider goddard and saturn to be putative de novo genes. Within Drosophila, both genes have been lost in certain lineages, but show conserved, male-specific patterns of expression in the species in which they are found. Goddard is consistently found in single-copy and evolves under purifying selection. In contrast, saturn has diversified through gene duplication and positive selection. These data suggest that de novo genes can acquire essential roles in male reproduction.