科幻电影《苍蝇》讲述了一位科学家由于操作失误，将自己与苍蝇的基因结合，产生突变，最终无法控制的悲剧。9月19日，中科院昆明动物研究所传出消息，中美科学家四年来对黑腹果蝇种系突变分布模式进行了研究，该研究成果已在《美国科学院院刊》（PNAS）上发表。
参与此项研究的研究人员高建军向记者详细介绍了这一研究的重要性。他说，突变是遗传变异的最终来源，其在生物学中的重要性早已得到普遍共识。突变可发生于高等生物的受精卵经一系列细胞分裂形成成体细胞的过程中。由于发生于较早期细胞分裂过程中的突变将会影响更多的组织，并更有可能被遗传给下一代，因此，了解种系细胞发育过程中突变分布的细节，不仅将加深人类对许多遗传缺陷的了解，还有助于解释突变研究中一些更广泛的问题。
在这项为期4年的实验过程中，来自云南大学、中科院昆明动物研究所、美国德克萨斯大学等多个研究机构的科研人员合作完成了这一高难度的研究。研究人员共观察了共8618个家系的每一个中的突变体数目以及每个独立突变的频率，其丰富的信息使得雄性黑腹果蝇在发育的不同阶段的自发隐性致死突变速率第一次得以严格分析。来自云南大学的符云新教授和中科院的张亚平院士开发了用于分析此类数据的新的统计方法，获得了种系细胞发育不同阶段的突变速率变化。
研究结果表明，在种系细胞发育的不同阶段，自发隐性致死突变的速率呈现高度变化，其中第一次卵裂过程中的突变速率最高，第二次或随后几次卵裂过程中的速率显著降低；在第一次卵裂与精子形成期之间，各次分裂的突变速率至少低一个数量级；精子形成过程中的突变速率也较高。
高建军解释，上述研究结果彻底否定了种系发育过程中速率恒定的流行观点，对于以往基于此观点的研究及其得出的结论提出了质疑，包括对雄性主导进化的理论作出了新的解释。两位中国科学家所构建的新的个体内溯祖理论及其突变统计分析方法，将可能应用于进一步研究人类生殖细胞、体细胞和肿瘤细胞的突变模式。
生物探索推荐英文论文摘要：
Highly variable recessive lethal or nearly lethal mutation rates during germ-line development of male Drosophila melanogaster
Each cell of higher organism adults is derived from a fertilized egg through a series of divisions, during which mutations can occur. Both the rate and timing of mutations can have profound impacts on both the individual and the population, because mutations that occur at early cell divisions will affect more tissues and are more likely to be transferred to the next generation. Using large-scale multigeneration screening experiments for recessive lethal or nearly lethal mutations of Drosophila melanogaster and recently developed statistical analysis, we show for male D. melanogaster that (i) mutation rates (for recessive lethal or nearly lethal) are highly variable during germ cell development; (ii) first cell cleavage has the highest mutation rate, which drops substantially in the second cleavage or the next few cleavages; (iii) the intermediate stages, after a few cleavages to right before spermatogenesis, have at least an order of magnitude smaller mutation rate; and (iv) spermatogenesis also harbors a fairly high mutation rate. Because germ-line lineage shares some (early) cell divisions with somatic cell lineage, the first conclusion is readily extended to a somatic cell lineage. It is conceivable that the first conclusion is true for most (if not all) higher organisms, whereas the other three conclusions are widely applicable, although the extent may differ from species to species. Therefore, conclusions or analyses that are based on equal mutation rates during development should be taken with caution. Furthermore, the statistical approach developed can be adopted for studying other organisms, including the human germ-line or somatic mutational patterns.
英文论文全文阅读：https://www.biodiscover.com/news/phylogeny/library/994
