Comings D E
Hum Genet. 1980 Feb;53(2):131-43. doi: 10.1007/BF00273484.
The factors responsible for producing some degree of order to the arrangement of chromatin in the nucleus are reviewed. They are following: 1. Chromosomes are attached to the nuclear membrane, nucleolus and intranuclear matrix. As a result they have a relatively fixed position in the nucleus. 2. In some species somatic pairing results in alignment of homologs. This is rare in mammals. 3. The association of ribosomal DNA and 5S DNA with the nucleolous results in the close approximation of the chromosomes carrying these DNA sequences. In man and other animals the most obvious consequence is satellite association. 4. Heterochromatin is condensed onto the inner nuclear membrane and periphery of the nucleolous while genetically active chromatin occupies the more central portion of the nucleus. The results is a peripheral location of late replicating DNA and a central location of early relicating DNA. 5. The DNA replication points tend to be associated with the nuclear matrix. Autoradiography of briefly labelled cells shows a high frequency of grains associated with nuclear matrix material. 6. Heterochromatin association results in chromocenters and ectopic pairing. 7. In addition to all these is the Rabl orientation or alignment of centromeres with centromeres and telomeres with telomeres. This polarization of the chromosomes results from the traction on the centromeres by the spindle fibers. There is no firm evidence for any higher degrees of order that might bring specific functioning genes into close proximity.
本文综述了细胞核中染色质排列产生一定程度有序性的相关因素。具体如下：1. 染色体附着于核膜、核仁及核内基质。因此，它们在细胞核中具有相对固定的位置。2. 在某些物种中，体细胞配对导致同源染色体对齐。这在哺乳动物中较为罕见。3. 核糖体DNA和5S DNA与核仁的结合导致携带这些DNA序列的染色体紧密靠近。在人类和其他动物中，最明显的结果是随体联合。4. 异染色质浓缩于内核膜和核仁周边，而具有遗传活性的染色质占据细胞核更中心的部分。结果是晚期复制的DNA位于周边，早期复制的DNA位于中心。5. DNA复制点倾向于与核基质相关联。对短期标记细胞的放射自显影显示，与核基质物质相关的银粒频率很高。6. 异染色质联合导致染色中心和异位配对。7. 除上述所有因素外，还有拉布尔定向，即着丝粒与着丝粒对齐，端粒与端粒对齐。染色体的这种极化是由纺锤体纤维对着丝粒的牵引所致。没有确凿证据表明存在任何更高程度的有序性，能使特定功能基因紧密靠近。
