Ryder O A, Hansen S K
Chromosoma. 1979 Apr 30;72(2):115-29. doi: 10.1007/BF00293229.
A (G + C)-rich density satellite DNA (rho = 1.713 gm/cc) has been purified from splenic DNA of Przewalski's horse, Equus przewalskii, by successive equilibrium density gradient centrifugations. The purified satellite, which may comprise as much as 29% of the total DNA, renatures rapidly; however, analyses of native, single-stranded, and reassociated molecules by analytical ultracentrifugation and melting properties suggest that some sequence heterogeniety exists in the 1.713 gm/cc satellite. Complementary RNA (cRNA) transcribed from satellite DNA has been utilized for in situ hybridization studies with E. przewalskii metaphase chromosomes previously identified by quinacrine-banding. These studies establish that sequences complementary to the 1.713 g/cc satellite are greatly enriched in the centromeres of some, but not all, chromosomes. The differential distribution of satellite DNA sequences over heterochromatic regions allows discrimination of three classes of heterochromatin and serves to define three types of pericentromeric regions in the karyotype of this endangered equine species. Additionally, apparent polymorphism in concentrations of satellite DNA sequences between homologs in the same karyotype is noted.
通过连续的平衡密度梯度离心，从普氏野马（Equus przewalskii）的脾脏DNA中纯化出了一种富含（G + C）的密度卫星DNA（ρ = 1.713克/立方厘米）。纯化后的卫星DNA可能占总DNA的29%，其复性迅速；然而，通过分析超速离心和熔解特性对天然、单链和重新结合的分子进行分析表明，1.713克/立方厘米的卫星DNA中存在一些序列异质性。从卫星DNA转录的互补RNA（cRNA）已被用于与先前通过喹吖因显带鉴定的普氏野马中期染色体进行原位杂交研究。这些研究表明，与1.713克/立方厘米卫星DNA互补的序列在一些（但不是所有）染色体的着丝粒中大量富集。卫星DNA序列在异染色质区域的差异分布使得能够区分三类异染色质，并有助于在这种濒危马种的核型中定义三种类型的着丝粒周围区域。此外，还注意到同一核型中同源染色体之间卫星DNA序列浓度存在明显的多态性。
