Kuznetsova I, Podgornaya O, Ferguson-Smith M A
Institute of Cytology, RAS, St. Petersburg, Russia.
Cytogenet Genome Res. 2006;112(3-4):248-55. doi: 10.1159/000089878.
We studied the organization of mouse satellite 3 and 4 (MS3 and MS4) in comparison with major (MaSat) and minor (MiSat) DNA sequences, located in the centromeric and pericentromeric regions of mouse telocentric chromosomes by fiber-FISH. The centromeric region consists of a small block of MiSat and MS3 followed by a pericentromeric block of MaSat with MS4. Inside the block of the long-range cluster, MaSat repeats intermingle mostly with MS4, while MiSat intermingle with MS3. The distribution of GC-rich satellite DNA fragments is less strict than that of AT-rich fragments; it is possible to find MS3 fragments in the MaSat array and MS4 fragments in the MiSat array. The methylation pattern does not fully correspond to one of the four families of satellite DNA (satDNA). In each satDNA fragment only part of the DNA is methylated. MS3 and MS4 are heavily methylated being GC-rich. Pericentomeric satellite DNA fragments are more methylated than centromeric ones. Among the four families of satDNA MS4 is the most methylated while MiSat is methylated only to a minimal extent. Estimation of the average fragment length and average distance between fragments shows that the range of the probes used does not cover the whole centromeric region. The existence of unknown sequences in the mouse centromere is likely.
我们通过纤维荧光原位杂交技术，研究了小鼠3号和4号卫星DNA（MS3和MS4）的组织情况，并与位于小鼠端着丝粒染色体着丝粒和着丝粒周围区域的主要（MaSat）和次要（MiSat）DNA序列进行了比较。着丝粒区域由一小段MiSat和MS3组成，后面跟着一段带有MS4的MaSat着丝粒周围区域。在长程簇区域内，MaSat重复序列大多与MS4相互交织，而MiSat则与MS3相互交织。富含GC的卫星DNA片段的分布不如富含AT的片段严格；在MaSat阵列中可以找到MS3片段，在MiSat阵列中可以找到MS4片段。甲基化模式并不完全与卫星DNA（satDNA）的四个家族之一相对应。在每个satDNA片段中，只有部分DNA被甲基化。MS3和MS4富含GC，甲基化程度很高。着丝粒周围的卫星DNA片段比着丝粒区域的甲基化程度更高。在satDNA的四个家族中，MS4甲基化程度最高，而MiSat仅在最小程度上被甲基化。对平均片段长度和片段之间平均距离的估计表明，所用探针的范围并未覆盖整个着丝粒区域。小鼠着丝粒中可能存在未知序列。
