Hauswirth W W, Laipis P J
Proc Natl Acad Sci U S A. 1982 Aug;79(15):4686-90. doi: 10.1073/pnas.79.15.4686.
Two mitochondrial genotypes are shown to exist within one Holstein cow maternal lineage. They were detected by the appearance of an extra Hae III recognition site in one genotype. The nucleotide sequence of this region has been determined and the genotypes are distinguished by an adenine/guanine base transition which creates the new Hae III site. This point mutation occurs within an open reading frame at the third position of a glycine codon and therefore does not alter the amino acid sequence. The present pattern of genotypes within the lineage demands that multiple shifts between genotypes must have occurred within the past 20 years with the most rapid shift taking place in no more than 4 years and indicates that mitochondrial DNA polymorphism can occur between maternally related mammals. The process that gave rise to different genotypes in one lineage is clearly of fundamental importance in understanding intraspecific mitochondrial polymorphism and evolution in mammals. Several potential mechanisms for rapid mitochondrial DNA variation are discussed in light of these results.
在一头荷斯坦奶牛的母系谱系中发现存在两种线粒体基因型。它们是通过一种基因型中额外出现的Hae III识别位点检测到的。已确定该区域的核苷酸序列，两种基因型通过腺嘌呤/鸟嘌呤碱基转换来区分，这种转换产生了新的Hae III位点。该点突变发生在一个开放阅读框内甘氨酸密码子的第三位，因此不会改变氨基酸序列。该谱系中目前的基因型模式表明，在过去20年内一定发生了多次基因型之间的转变，其中最快速的转变发生在不超过4年的时间内，这表明母系相关的哺乳动物之间可能发生线粒体DNA多态性。在一个谱系中产生不同基因型的过程对于理解哺乳动物种内线粒体多态性和进化显然至关重要。根据这些结果讨论了线粒体DNA快速变异的几种潜在机制。
