Large Scale Chromatin Structure

大尺度染色质结构是指染色质在几百个碱基的尺度上的高阶折叠。人们对这种折叠知之甚少，但这种结构一定会影响DNA的转录、复制和修复。为了进一步了解这些结构，我们用光学显微镜检查了400 - 2000 kb的转录活性区域。我们发现几个不同的结构域在光学显微镜图像中表现出相似的结构，即一系列相邻的点或直径约0.5微米的“珠子”。当这些相同的结构域转录不活跃时，只检测到一个点或“头”。因此，转录诱导从单珠状结构到多珠状结构的去浓缩。这些观察结果对染色质的高阶折叠施加了限制。目前的工作重点是识别与这些结构相关的分子，并通过更高分辨率的成像来观察这些结构。

Large-scale chromatin structure is the higher-order folding of chromatin on the scale of several hundred kilobases. Little is known about this folding, but the structures must influence transcription, replication and repair of DNA. To learn more about these structures, we have examined transcriptionally active domains of 400 - 2000 kb by light microscopy. We find that several different domains exhibit similar structures in light microscope images, namely a series of adjacent puncta or "beads" approximately 0.5 microns in diameter. When these same domains are transcriptionally inactive, only one punctum or "bead" is detected. Thus transcription induces a decondensation from single beaded to multi-beaded structures. These observations impose constraints on the higher order folding of chromatin. Present work focuses on identifying molecules associated with these structures, and observing the structures by higher resolution imaging.