The Foldback-like transposon Galileo is involved in the generation of two different natural chromosomal inversions of Drosophila buzzatii
The Foldback-like transposon Galileo is involved in the generation of two different natural chromosomal inversions of Drosophila buzzatii
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DOI：
10.1093/molbev/msg070
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发表时间：
2003-05-01
影响因子：
10.7
通讯作者：
Ruiz, A
中科院分区：
文献类型：
--
作者：
Casals, F;C치ceres, M;Ruiz, A
染色体倒置是果蝇属中最常见的基因组重排类型。尽管转座元件(TES)在实验室中产生倒位的潜力已被反复证明，但人们对它们在自然倒位产生中的作用知之甚少，自然倒位是那些有效地促进物种适应和/或进化的元件。我们克隆并测序了布氏木霉多态倒位2q(7)的两个断裂点。对断裂点区的序列分析表明，在没有倒位的情况下，由转座子的复杂组合形成的大插入体存在于倒置的染色体中。在插入的转座子中，先前被发现负责产生广泛的Buzzatii倒位2J的折叠回元件Galileo存在于两个2q(7)断裂点，并且是最可能的倒位的诱导者。对2Q(7)倒位的6个染色体系断裂区的核苷酸和结构变异进行了详细的研究，发现它们之间没有核苷酸差异，这表明它们是单系起源和近期起源。相反，在相同的六个染色体系中观察到了显著程度的结构变异。因此，倒置染色体的两个断裂点似乎已经成为遗传不稳定的热点，就像之前在2J倒位断裂点发现的那样。讨论了这种不稳定性是由折返元件的结构特性引起的可能性。
Chromosomal inversions are the most common type of genome rearrangement in the genus Drosophila. Although the potential of transposable elements (TEs) for generating inversions has been repeatedly demonstrated in the laboratory, little is known on their role in the generation of natural inversions, which are those effectively contributing to the adaptation and/or evolution of species. We have cloned and sequenced the two breakpoints of the polymorphic inversion 2q(7) of D. buzzatii. The sequence analysis of the breakpoint regions revealed the presence in the inverted chromosomes of large insertions, formed by complex assemblies of transposons, that are absent from the chromosomes without the inversion. Among the transposons inserted, the Foldback-like element Galileo, that was previously found responsible of the generation of the widespread inversion 2j of D. buzzatii, is present at both 2q(7) breakpoints and is the most likely inducer of the inversion. A detailed study of the nucleotide and structural variation in the breakpoint regions of six chromosomal lines with the 2q(7) inversion detected no nucleotide differences between them, which suggests a monophyletic and recent origin. In contrast, a remarkable degree of structural variation was observed in the same six chromosomal lines. It thus appears that the two breakpoints of the inverted chromosomes have become genetically unstable hotspots, as was previously found for the 2j inversion breakpoints. The possibility that this instability is caused by structural properties of Foldback elements is discussed.