The dot chromosome of Drosophila:: Insights into chromatin states and their change over evolutionary time
The dot chromosome of Drosophila:: Insights into chromatin states and their change over evolutionary time
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DOI：
10.1007/s10577-006-1061-6
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发表时间：
2006-05-01
影响因子：
2.6
通讯作者：
Elgin, Sarah C. R.
中科院分区：
文献类型：
--
作者：
Riddle, Nicole C.;Elgin, Sarah C. R.
从历史上看，染色质被细分为异染色质和常染色质，异染色质是在整个细胞周期中保持密集包装的转录无活性区域，而常染色质是在细胞进入间期时呈弥散状的转录活跃区域。黑腹果蝇小的第4染色体（点染色体）的带状部分表现出许多异染色质结构域的特征，同时保持了典型的常染色质的基因密度。与嵌入在中心周围异染色质中的基因类似，许多点染色体基因已经适应了异染色质环境。人们对这些基因的调控知之甚少，对它们在染色质背景下的进化也知之甚少。有趣的是，大部分来自黑腹果蝇第四染色体的基因在整个果蝇属中仍然聚集在一条小染色体上；然而，在一些物种中，点染色体呈现出正染色，例如D. virilis。现有的基因组序列数据允许探索物种之间DNA序列组织的潜在差异。在这里，我们回顾了现有的数据描述点染色体，这主要来自黑腹龙。由于其不寻常和不断变化的性质，果蝇属的点染色体为研究进化过程中染色质状态之间的转变提供了一个独特的机会。
Historically, chromatin has been subdivided into heterochromatin, transcriptionally inactive regions that remain densely packaged throughout the cell cycle, and euchromatin, transcriptionally active regions that take on a diffuse appearance as the cell enters interphase. The banded portion of the small fourth chromosome (dot chromosome) of Drosophila melanogaster is unusual in exhibiting many characteristics of heterochromatic domains, and at the same time maintaining a gene density typical of euchromatin. Similar to genes embedded in pericentric heterochromatin, many of the dot chromosome genes have adapted to a heterochromatic environment. Little is known about the regulation of these genes and less about their evolution in a chromatin context. Interestingly, most of the genes from the D. melanogaster fourth chromosome remain clustered on a small chromosome throughout the genus Drosophila; yet the dot chromosome appears euchromatic in some species, such as D. virilis. Existing genomic sequence data allow an exploration of the underlying differences in DNA sequence organization between species. Here we review the available data describing the dot chromosome, which derives primarily from D. melanogaster. With its unusual and changing nature, the dot chromosome in the genus Drosophila provides a unique opportunity for the examination of transitions between chromatin states during evolution.