Maslova Antonina, Zlotina Anna, Kosyakova Nadezhda, Sidorova Marina, Krasikova Alla
Saint Petersburg State University, Saint Petersburg, 198504, Russia.
Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany.
Chromosome Res. 2015 Sep;23(3):625-39. doi: 10.1007/s10577-015-9485-5.
Tandem repeats belong to a class of genomic repetitive elements that form arrays of head-to-tail monomers. Due to technical difficulties in sequencing and assembly of large tandem repeat arrays, it remains largely unknown by which mechanisms tandem-repeat-containing regions aid in maintenance of ordered radial genome organization during interphase. Here we analyzed spatial distribution of several types of tandem repeats in interphase nuclei of chicken MDCC-MSB1 cells and somatic tissues relative to heterochromatin compartments and nuclear center. We showed that telomere and subtelomere repeats generally localize at the nuclear or chromocenters periphery. A tandem repeat known as CNM, typical for centromere regions of gene-dense microchromosomes, forms interchromosome clusters and occupies DAPI-positive chromocenters that appear predominantly within the nuclear interior. In contrast, centromere-specific tandem repeats of the majority of gene-poor macrochromosomes are embedded into the peripheral layer of heterochromatin. Chicken chromocenters rarely comprise centromere sequences of both macro- and microchromosomes, whose territories localize in different radial nuclear zones. Possible mechanisms of observed tandem repeats positioning and its implication in highly ordered arrangement of chromosome territories in chicken interphase nucleus are discussed.
串联重复序列属于一类基因组重复元件，它们形成头尾相连的单体阵列。由于大型串联重复序列阵列测序和组装存在技术困难，含串联重复序列区域在间期帮助维持有序的径向基因组组织的机制在很大程度上仍不为人知。在这里，我们分析了鸡MDCC-MSB1细胞和体细胞组织间期细胞核中几种类型串联重复序列相对于异染色质区室和核中心的空间分布。我们发现端粒和亚端粒重复序列通常定位于核或染色中心的周边。一种名为CNM的串联重复序列，是基因密集型微染色体着丝粒区域的典型特征，形成染色体间簇并占据主要出现在核内部的DAPI阳性染色中心。相反，大多数基因贫乏的大染色体的着丝粒特异性串联重复序列嵌入异染色质的外周层。鸡的染色中心很少包含大染色体和微染色体的着丝粒序列，它们的区域位于不同的径向核区。本文讨论了观察到的串联重复序列定位的可能机制及其对鸡间期细胞核中染色体区域高度有序排列的影响。
