Karamysheva T V, Bogdanov A S, Kartavtseva I V, Likhoshvaĭ T V, Bochkarev M N, Kolcheva N E, Marochkina V V, Rubtsov N B
Genetika. 2010 Jun;46(6):805-16.
The composition and homology of centromeric heterochromatin DNA has been compared in representatives of the Asian race and two chromosomal forms (Eastern European and Southern European) of the European race of the pygmy wood mouse Sylvaemus uralensis by means of in situ hybridization with metaphase chromosomes of microdissection DNA probes obtained from centromeric C-blocks of mice of the Southern European chromosomal form and the Asian race. Joint hybridization of both DNA probes yielded all possible variants of centromeric regions in terms of the presence of repetitive sequences homologous to those of some or another dissection region, which indicates a diversity of centromeric regions differing in DNA composition. However, most variations of the fluorescent in situ hybridization (FISH) patterns are apparently related to quantitative differences of repetitive elements of the genome. Experiments with the DNA probe obtained from the genome of the Southern European form of the pygmy wood mouse have shown that the number of intense FISH signals roughly corresponds to the number of large C-segments in representatives of the European race, which is characterized by a large amount of the centromeric C-heterochromatin in the karyotype. However, intense signals have been also detected in experiments on hybridization of this probe with chromosomes of representatives of the Asian race, which has no large C-blocks in the karyotype; thus, DNA sequences homologous to heterochromatic ones are also present in nonheterochromatic regions adjacent to C-segments. Despite the variations of the numbers of both intense and weak FISH signals, all chromosomal forms/races of S. uralensis significantly differ from one another in these characters. The number of intense FISH signals in DNA from the samples of pygmy wood mice from eastern Turkmenistan (the Kugitang ridge) and southern Omsk oblast (the vicinity of the Talapker railway station) was intermediate between those in the European and Asian races, which is apparently related to a hybrid origin of these populations (the hybridization having occurred long ago in the former case and recently in the latter case).
通过使用从欧洲南部染色体形式和亚洲种族小鼠的着丝粒C区获得的微切割DNA探针与中期染色体进行原位杂交，比较了亚洲种族代表以及侏儒林鼠（Sylvaemus uralensis）欧洲种族的两种染色体形式（东欧和南欧）着丝粒异染色质DNA的组成和同源性。两种DNA探针的联合杂交产生了着丝粒区域的所有可能变体，这些变体在与某些或其他切割区域的重复序列同源性方面存在差异，这表明着丝粒区域在DNA组成上存在多样性。然而，荧光原位杂交（FISH）模式的大多数变化显然与基因组重复元件的数量差异有关。对从侏儒林鼠欧洲南部形式的基因组中获得的DNA探针进行的实验表明，强烈FISH信号的数量大致与欧洲种族代表中大型C段的数量相对应，欧洲种族的特征是核型中存在大量着丝粒C异染色质。然而，在用该探针与亚洲种族代表的染色体杂交的实验中也检测到了强烈信号，亚洲种族的核型中没有大型C区；因此，与异染色质序列同源的DNA序列也存在于与C段相邻的非异染色质区域。尽管强烈和微弱FISH信号的数量存在变化，但乌拉尔侏儒林鼠的所有染色体形式/种族在这些特征上彼此显著不同。来自土库曼斯坦东部（库吉唐岭）和鄂木斯克州南部（塔拉普克火车站附近）的侏儒林鼠样本DNA中强烈FISH信号的数量介于欧洲和亚洲种族之间，这显然与这些种群的杂交起源有关（前者的杂交发生在很久以前，后者的杂交发生在最近）。
