title: [Genetic determination of the activity of nucleolar-organizing regions of human chromosomes].
abstract: Activity of nucleolar organizer regions (NORs) was studied in cultured blood lymphocytes of 8 monozygotic and 8 dizygotic twin pairs using Ag-staining of acrocentric chromosomes. These chromosomes were identified by G-banding. NOR activity was estimated by the number of Ag-stained regions, their distribution among individuals acrocentrics and the size of silver deposits. No statistically significant differences were found as regards these criteria between the monozygotic twins. The dizygotic twins were distinguished, as a rule, in most pairs by one or another chromosome. The data obtained indicate that NOR, activity in each chromosome is of a heritable character, at least in blood lymphocytes. Chromosome 21 was found to have a greater NOR activity as compared with other acrocentrics.
mesh_terms: D000328:Adult; D002871:Chromosome Banding; D002874:Chromosome Mapping; D002901:Chromosomes, Human, 13-15; D002904:Chromosomes, Human, 21-22 and Y; D005260:Female; D006801:Humans; D009697:Nucleolus Organizer Region; D011247:Pregnancy; D014427:Twins; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic
vernacular_title: Geneticheskaia obuslovlennost' aktivnosti iadryshkoobrazuiushchikh raĭonov khromosom cheloveka.