果蝇中DNA的进化速率取决于表达的功能和发育阶段。
Rates of DNA evolution in Drosophila depend on function and developmental stage of expression.
作者信息
Powell J R, Caccone A, Gleason J M, Nigro L
机构信息
Department of Biology, Yale University, New Haven, Connecticut 06511.
出版信息
Genetics. 1993 Feb;133(2):291-8. doi: 10.1093/genetics/133.2.291.
DNA-sequence divergence of genes expressed in the embryonic stage was compared with the divergence of genes expressed in adults for 13 species of Drosophila representing various degrees of relatedness. DNA-DNA hybridization experiments were conducted using as tracers complementary DNA (cDNA) reversed transcribed from poly(A)+ mRNA isolated from different developmental stages. The results indicate: (1) cDNA is less diverged than total single-copy DNA; (2) cDNA sequences are not in the rapidly evolving fraction of the single-copy genome of Drosophila; (3) early in evolutionary divergence embryonic messages are about half as diverged as adult messages; sequence data from some of the species compared indicate this is likely due to differences in rates of silent substitutions in genes expressed at different stages of development; and (4) at greater evolutionary distance, the differences in embryonic and adult messages disappear; this could be due to lineage-specific shifts in codon usage.
针对代表不同亲缘关系程度的13种果蝇，比较了胚胎期表达基因的DNA序列差异与成虫期表达基因的差异。使用从不同发育阶段分离的聚腺苷酸加尾mRNA反转录得到的互补DNA（cDNA）作为示踪剂进行DNA-DNA杂交实验。结果表明：（1）cDNA的差异程度小于总单拷贝DNA；（2）cDNA序列不在果蝇单拷贝基因组快速进化的部分；（3）在进化分歧早期，胚胎期信息的差异程度约为成虫期信息的一半；所比较的一些物种的序列数据表明，这可能是由于在不同发育阶段表达的基因中沉默替换率的差异；（4）在更大的进化距离下，胚胎期和成虫期信息的差异消失；这可能是由于密码子使用的谱系特异性变化。
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