Bucci S, Ragghianti M, Mancino G, Petroni G, Guerrini F, Giampaoli S
Dipartimento di Fisiologia e Biochimica, Pisa, Italy.
Genome. 1999 Jun;42(3):504-11. doi: 10.1139/g98-149.
The highly repetitive Rana/Pol III family consists of short, tandemly arrayed sequences, scattered throughout the genomes of Palearctic green water frogs. The repeat unit is about 250 bp in length and is a composite element: it contains a SINE-like retroposon with a tRNA structure, flanked by two short direct repeats, and the occurrence of two internal repeats gives evidence that an additional transposition event may have inserted a segment within the already transposed element. Rana/Pol III family is present in the genomes of Rana lessonae, R. ridibunda, and their hybrid form R. esculenta, as well as in R. shqiperica. R. epeirotica, R. cretensis, and the Italian taxon. These sequences are also present in the Iberian R. perezi, although less abundant, but appear to be lacking in the north African species R. saharica. The distribution of Rana/Pol III in the genomes of Palearctic green frogs is in agreement with the phyletic history based on genetic data. The evolutionary pattern proposed for the genus Rana enables us to suppose that the hybridogenetic mechanism is one of the factors accounting for the possible horizontal transfer of Rana/Pol III elements from the central-north Europe species to R. perezi.
高度重复的林蛙/聚合酶III家族由短串联排列序列组成，散布在古北界绿水蛙的基因组中。重复单元长度约为250 bp，是一个复合元件：它包含一个具有tRNA结构的类似SINE的反转录转座子，两侧有两个短的直接重复序列，两个内部重复序列的出现表明可能有一个额外的转座事件在已经转座的元件内插入了一个片段。林蛙/聚合酶III家族存在于无斑林蛙、欧洲林蛙及其杂交形式食用蛙的基因组中，也存在于阿尔巴尼亚林蛙、希腊林蛙、克里特岛林蛙和意大利分类群的基因组中。这些序列也存在于伊比利亚半岛的佩氏林蛙中，尽管数量较少，但在北非物种撒哈拉林蛙中似乎不存在。林蛙/聚合酶III在古北界绿蛙基因组中的分布与基于遗传数据的系统发育历史一致。为林蛙属提出的进化模式使我们能够推测，杂交起源机制是林蛙/聚合酶III元件可能从欧洲中北部物种水平转移到佩氏林蛙的因素之一。
