Grif V G
Laboratory of Biosystematics and Cytology, Komarov Botanical Institute, Russian Academy of Sciences, St. Petersburg, Russia.
Int Rev Cytol. 2000;196:131-75. doi: 10.1016/s0074-7696(00)96004-2.
The significance of the 4C value (where C is the amount of DNA in the unreplicated haploid genome) in angiosperm plants is discussed. The DNA amount is a stable feature used in biosystematics. Although this parameter varies even in closely related taxa, there is no correlation between the DNA amount and the structural and functional organization of plants. The role of DNA amount, including "excess" DNA, in plant evolution is considered. Some rules governing the distribution of DNA amount among different plant taxa are postulated, together with the possibility of using the data in systematics, phylogeny, and solutions of problems of genetic apparatus organization and evolution. The decrease in DNA value per genome during plant evolution and the high level of species formation in taxa with large DNA values have been shown. Plant taxa with a small DNA value per genome have a high percentage and higher degree of polyploidy. The nature of the differential staining of euchromatin and heterochromatin bands of prophase and metaphase chromosomes is also discussed. Data that could explain the mechanism of heterochromatin visualization under cold pretreatment of cells are reviewed. Phenomena involved in the arrangement of chromocenters in interphase nuclei and chromosomes in metaphase during consecutive cell generations are discussed.
本文讨论了被子植物中4C值（其中C是未复制单倍体基因组中的DNA量）的意义。DNA量是生物系统学中使用的一个稳定特征。尽管该参数即使在亲缘关系密切的分类群中也会有所变化，但DNA量与植物的结构和功能组织之间并无关联。文中考虑了DNA量，包括“多余”DNA在植物进化中的作用。提出了一些关于不同植物分类群中DNA量分布的规则，以及在系统学、系统发育以及解决遗传机制组织和进化问题时使用这些数据的可能性。研究表明，在植物进化过程中每个基因组的DNA值会降低，而在具有大DNA值的分类群中物种形成水平较高。每个基因组DNA值较小的植物分类群具有较高的多倍体百分比和程度。文中还讨论了前期和中期染色体常染色质和异染色质带差异染色的本质。综述了能够解释细胞冷预处理下异染色质可视化机制的数据。讨论了在连续细胞世代中，间期核中染色中心的排列以及中期染色体的排列所涉及的现象。
