Charlesworth D, Liu F L, Zhang L
Department of Ecology and Evolution, University of Chicago, USA.
Mol Biol Evol. 1998 May;15(5):552-9. doi: 10.1093/oxfordjournals.molbev.a025955.
We present results showing that several species in the plant genus Leavenworthia, in the Brassica family, have three alcohol dehydrogenase loci, unlike Arabidopsis thaliana, which has only a single classical (class P) alcohol dehydrogenase locus. Based on a portion of the sequence, the alcohol dehydrogenase loci of Leavenworthia show about 92%-93% amino acid sequence identity to that of the A. thaliana alcohol dehydrogenase. The great majority of the sequence differences from the A. thaliana Adh-coding sequence, and also between three different Leavenworthia species, are synonymous, suggesting that all are currently functional (or have been in the recent evolutionary past). The loci differ in the numbers of introns present, with one locus (Adh-3) having no introns present. RT-PCR tests detect expression of all three loci. Linkage data using variant alleles identified by single-strand conformation polymorphism analysis show that the three Leavenworthia loci are not closely linked. The results therefore suggest that the Adh-3 locus may have arisen via an mRNA intermediate but, despite loss of the introns, is expressed.
我们展示的结果表明，十字花科植物Leavenworthia属中的几个物种有三个乙醇脱氢酶基因座，这与拟南芥不同，拟南芥只有一个经典的（P类）乙醇脱氢酶基因座。基于部分序列，Leavenworthia的乙醇脱氢酶基因座与拟南芥乙醇脱氢酶的氨基酸序列同一性约为92%-93%。与拟南芥Adh编码序列以及三个不同Leavenworthia物种之间的绝大多数序列差异都是同义的，这表明所有这些基因座目前都是有功能的（或者在最近的进化历程中曾经有功能）。这些基因座所含内含子数量不同，其中一个基因座（Adh-3）没有内含子。RT-PCR检测发现所有三个基因座均有表达。利用单链构象多态性分析鉴定的变异等位基因进行的连锁数据显示，Leavenworthia的三个基因座并非紧密连锁。因此，结果表明Adh-3基因座可能是通过mRNA中间体产生的，尽管内含子缺失，但仍可表达。
