The no-on-transient A (nonA) gene encodes a putative RNA-binding protein, and mutations in this gene are known to affect vision, male courtship song and viability in Drosophila melanogaster. Here we have sequenced the coding region of the nonA gene of Drosophila littoralis and compared it with those of Drosophila virilis and D. melanogaster. All portions of nonA appeared to be conserved between D. littoralis and D. virilis, while the 5′ region of the gene of these two species showed high divergence from that of a more distantly-related species, D. melanogaster. The same was true for the glycine repeat regions. No significant deviation from neutrality was observed in the analysis of intraspecific nucleotide variation in 5′ or 3′ region of the nonA gene in D. littoralis population. Also, comparison of D. littoralis sequences with homologous sequence of D. virilis suggests that the gene is evolving neutrally in D. virilis group. Divergence of the 5′ regions between D. virilis group species and D. melanogaster could be a result of positive selection, but this finding is obscured by the long divergence time of the species groups.

中文翻译：

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滨海果蝇非瞬时 A 基因的核苷酸变异

非瞬时 A (nonA) 基因编码一种假定的 RNA 结合蛋白，已知该基因的突变会影响黑腹果蝇的视力、雄性求爱歌曲和生存能力。在这里，我们对滨海果蝇的 nonA 基因的编码区进行了测序，并将其与果蝇和黑腹果蝇的编码区进行了比较。nonA 的所有部分似乎在 D. littoralis 和 D. virilis 之间都是保守的，而这两个物种的基因 5' 区域显示出与关系更远的物种 D. melanogaster 的高度差异。甘氨酸重复区域也是如此。在分析滨海 D. littoralis 种群中 nonA 基因的 5' 或 3' 区域的种内核苷酸变异时，未观察到显着偏离中性。另外，比较D。littoralis 序列与 D. virilis 同源序列表明该基因在 D. virilis 组中中性进化。D. virilis 组物种和 D. melanogaster 之间 5' 区域的分歧可能是正选择的结果，但这一发现被物种组的较长分歧时间所掩盖。