[Comparative analysis of chromosomal nucleolar organizing region activity in spontaneous and medical abortuses]

Abstract

Comparative analysis of functional activity of silver stained nucleolar-organizing regions (NOR) activity was carried out in human fibroblasts of 70 spontaneous and 50 medical abortuses. The NOR activity was significantly higher in spontaneous abortuses compared with medical ones. This phenomenon which was observed in female, but not in male abortuses, did not depend upon the tissue origin of fibroblasts (embryonic or extraembryonic) and was due to increase of the NOR activity of the all acrocentric chromosomes to the level at which individual differences in the NOR activities among some acrocentrics were smoothed. It has been suggested that the ribosomal genes activity in different sex is likely to be differently involved in polygenic systems determining vitally important features of organism that may lead to different selection intensity in different sex resulted in deviation of the ribosomal gene copy number from the optimum. The possible role of changes in DNA methylation at the genome level in activation of ribosomal genes in spontaneous abortuses is discussed.

PIP: Metaphases of chromosomal preparations were obtained from fibroblastic embryonic cultures of 190 spontaneous and 52 medical abortions. 70 spontaneous abortion samples were chosen for studying the activity of ribosomal genes in the test group and 50 of the medical abortion material served as controls. The objective was to compare the selective functional activity of nitric acid-stained cerebral chromosomal nucleolar organizing region (NOR) compared with normal karyotypes. The age of embryos of the study group was 5-16 weeks and that of the control group was 7-12 weeks of gestation. The total distribution of NOR activity in the genes of both groups was similar, however, the range was 15.6-28.4 in the medical abortion group. The difference between the average meaning of summary activity of NOR in genes in the spontaneous group was 21.3 +or- .2 and 20.2 +or- .3, which was very significant. The 2 groups also differed in the number of active NORs in the cells: 8.9 +or- .08 for the study group and 8.7 +or- .1 for controls. In the study group both sexes had a higher transcriptive activity of ribosomal genes compared with induced abortion materials (significant only for female embryos). The activity of NOR in the medical abortion group was positively lower than the activity of ribosomal genes of spontaneous abortion embryos both for embryonic and extraembryonic cells. NOR activity increased significantly only in the female embryonic and extraembryonic cells. The highest activity of separate acrocentric chromosomes in the control group of embryos was observed in chromosomes 21 and 13 and the lowest in chromosomes 15 and 14. The differences between chromosomes 15 and 21 and also between 15 and 13 were statistically significant. Chromosomes 15 and 14 with the lowest NOR activity in the control group displayed the strongest and most significant increase in the expression of ribosomal genes in the study group.