Miroshnichenko G P, Antonov A S, Gileva E A
Mol Biol (Mosk). 1978 Nov-Dec;12(6):1348-58.
In order to elucidate the possible relationship between the karyotype and the polynucleotide sequence organization in DNA, comparison was made between DNA from the liver of Dicrostonyx torquatus chionapaes Allen with different numbers of B-chromosomes (2n = 47-49, 1-3 B-chromosomes; 2n = 52-54,6-8 B-chromosomes). The reassociation kinetics patterns for denatured DNA fragments (about 300 nucleotides long) were obtained by the batch hydroxyapatite method. The analysis of these patterns showed a approximately 10% increase in the proportion of reiterated nucleotide sequences in the DNA of animals with 6-8 B-chromosomes. The increase in the proportion of reiterations in DNA correlated with increase in the number of B-chromosomes can be regarded as an indirect confirmation of the heterochromatic nature of B-chromosomes. The individual fractions of reiterated nucleotide sequences (C0t = 1.0) were isolated from studied DNas. The reassociation kinetics of these fractions and the thermostability of resulting duplexes were examined. The revealed differences are indicative of a certain dissimilarity in the polynucleotide sequences organization that correlate with variation in the number of B-chromosomes. The heterochromatic and euchromatic. DNAas from the liver cell nuclei of animals carrying different numbers of B-chromosomes were studied by thermal denaturation analysis and neutral CsCl equilibrium centrifugation. In the heterochromatic DNAs from livers of D. t. chionopaes with 6-8 B-chromosomes additional components enriched with AT-pairs were revealed. The specific features of DNA correlated with increase in the number of B-chromosomes are discussed in connection with peculiarities of B-chromosomes behaviour and their evolution in Dicrostonyx torquatus chionapaes.
为了阐明核型与DNA中多核苷酸序列组织之间的可能关系，对具有不同数量B染色体（2n = 47 - 49，1 - 3条B染色体；2n = 52 - 54，6 - 8条B染色体）的北美旅鼠指名亚种肝脏中的DNA进行了比较。通过分批羟基磷灰石法获得了变性DNA片段（约300个核苷酸长）的重缔合动力学模式。对这些模式的分析表明，具有6 - 8条B染色体的动物的DNA中重复核苷酸序列的比例增加了约10%。DNA中重复序列比例的增加与B染色体数量的增加相关，这可被视为B染色体异染色质性质的间接证据。从研究的DNA中分离出重复核苷酸序列的各个部分（C0t = 1.0）。检查了这些部分的重缔合动力学以及所得双链体的热稳定性。所揭示的差异表明多核苷酸序列组织存在一定差异，这与B染色体数量的变化相关。通过热变性分析和中性CsCl平衡离心法研究了携带不同数量B染色体的动物肝细胞核中的异染色质和常染色质DNA。在具有6 - 8条B染色体的北美旅鼠指名亚种肝脏的异染色质DNA中，发现了富含AT对的额外成分。结合北美旅鼠指名亚种中B染色体的行为及其进化特点，讨论了与B染色体数量增加相关的DNA的具体特征。
