Islands of complex DNA are widespread in Drosophila centric heterochromatin.
Islands of complex DNA are widespread in Drosophila centric heterochromatin.
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复杂 DNA 岛广泛存在于果蝇中心异染色质中。
DOI：
10.1093/genetics/141.1.283
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发表时间：
1995
期刊：
影响因子：
3.3
通讯作者：
Karpen,GH
中科院分区：
文献类型：
--
作者：
Le,MH;Duricka,D;Karpen,GH
异染色质是多细胞真核生物基因组中普遍存在但知之甚少的组成部分。我们对异染色质中DNA序列的性质和整体组织的认识存在重大差距。我们研究了果蝇微型染色体Dp1187中心异染色质的1 Mb的分子结构。辐照的微型染色体的遗传筛选产生Dp1187的重排衍生物，其结构由脉冲场Southern分析和PCR确定。三个Dp1187缺失衍生物和一个倒位在常染色质和异染色质中有一个断点，提供了直接的分子访问以前无法访问的异染色质部分。末端探测脉冲场限制性酶切图谱显示，存在至少三个“岛”的复杂的DNA，大溪地，莫雷阿岛，波拉波拉岛，构成约一半的Dp1187异染色质。脉冲场Southern分析表明，果蝇异染色质一般是由复杂的DNA和简单的卫星DNA交替块。对塔希提岛一小部分的克隆和测序证明了逆转录酶的存在。这些研究结果的异染色质结构和功能的影响进行了讨论。
Heterochromatin is a ubiquitous yet poorly understood component of multicellular eukaryotic genomes. Major gaps exist in our knowledge of the nature and overall organization of DNA sequences present in heterochromatin. We have investigated the molecular structure of the 1 Mb of centric heterochromatin in the Drosophila minichromosome Dp1187. A genetic screen of irradiated minichromosomes yielded rearranged derivatives of Dp1187 whose structures were determined by pulsed-field Southern analysis and PCR. Three Dp1187 deletion derivatives and an inversion had one breakpoint in the euchromatin and one in the heterochromatin, providing direct molecular access to previously inaccessible parts of the heterochromatin. End-probed pulsed-field restriction mapping revealed the presence of at least three "islands" of complex DNA, Tahiti, Moorea, and Bora Bora, constituting approximately one half of the Dp1187 heterochromatin. Pulsed-field Southern analysis demonstrated that Drosophila heterochromatin in general is composed of alternating blocks of complex DNA and simple satellite DNA. Cloning and sequencing of a small part of one island, Tahiti, demonstrated the presence of a retroposon. The implications of these findings to heterochromatin structure and function are discussed.