Large Scale Chromatin Structure

大规模染色质结构是染色质在尺度上的高级折叠 几百个小矮人。对这种折叠知之甚少，但结构必须 影响DNA转录、复制和修复。为了了解更多关于这些结构的信息， 我们先前通过光学显微镜检查了400 - 2000 kb的转录活性结构域。 我们发现几个不同的域在光学显微镜图像中表现出相似的结构， 即一系列直径约0.5微米的相邻点或“珠”。当 这些相同的结构域在转录上是无活性的，仅检测到一个点或“珠”。 因此，转录诱导从单珠结构到多珠结构的解凝聚。到 在更高的分辨率下观察这些结构，我们正在探索X射线的适用性。 显微镜这种成像方式使整个未切片的哺乳动物细胞可视化 分辨率为25 nm。染色质的检测依赖于由染色质提供的天然对比度。 有机物相对于水的吸收。我们的目标是确定染色质 可以通过这种方法检测核结构，如果是，则提供核的3D图像 染色质在25 nm分辨率。

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 previously examined transcriptionally active domains of 400 - 2000 kb by light microscopy. We found 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. To observe these structures at higher resolution we are exploring the applicability of x-ray microscopy. This imaging modality enables visualization of whole, unsectioned mammalian cells at 25 nm resolution. Detection of chromatin relies on the natural contrast afforded by the absorption of organic matter relative to water. Our goal is to determine if chromatin structure can be detected by this approach and if so, then to provide a 3D image of nuclear chromatin at 25 nm resolution.