Mobile genetic elements, chiasmata, and the unique organization of beta-heterochromatin.
Mobile genetic elements, chiasmata, and the unique organization of beta-heterochromatin.
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移动遗传元件、交叉和β-异染色质的独特组织。
DOI：
10.1159/000014965
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Jurka,J
中科院分区：
文献类型：
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作者：
Holmquist,GP;Kapitonov,VV;Jurka,J
果蝇和叙利亚仓鼠的β-异染色质具有相似的DNA组织，几乎没有独特的序列，并在没有串联重复的情况下扰乱了移动元件的重复。α-异染色质中的dna是随机重复的，我们现在证明重复单元可以包含或不包含可移动的元件。α-异染色质的串联重复结构可能是由于重复单元之间不平等交换的类似Contina的机制所致。虽然这两种类型的异染色质都是晚期复制的，并且可以结合可移动的逆染色质，但这两种异染色质之间的序列差异似乎是由于交叉赋予β-异染色质中的同源重组过程的性质，而不是α-异染色质中的同源重组过程。交叉交叉似乎抑制了不平等交换的协调机制，并赋予β-异染色质其非串联、杂乱的重复组织。
Beta-heterochromatin in Drosophila and the Syrian hamster share a similar DNA organization, few unique sequences, and scrambled repeats of mobile elements without tandem repetition. DNA in α-heterochromatin is tandemly repetitious, and we now show that the repeat unit can either contain or lack a mobile element. The tandem repeat organization of α-heterochromatin is presumably due to a concertina-like mechanism of unequal exchange between repeat units. Although both heterochromatin types are late replicating and can incorporate mobile retroposons, the sequence distinction between the two heterochromatins appears to be due to a property conferred by chiasmata upon the process of homologous recombination in β-heterochromatin but not in α-heterochromatin. Chiasmata seem to suppress the concertina mechanism of unequal exchange and impart to β-heterochromatin its nontandem, scrambled repeat organization.