[Ribosomal genes in inbred mouse strains: interstrain and intrastrain variations of copy number and extent of methylation].

Quantitative dot hybridization was used to estimate the rDNA copy number in brain tissues of five inbred mouse strains (AKR/JY, NZB/B1OrlY, CBA/CaLacY, 101/HY, and 129/JY), which were obtained from the collection of the Research Center of Biomedical Technologies (Y). In each strain, 9-12 mice aged 1-2 months were examined. The rDNA copy number per diploid genome in strains AKR (range 105-181, mean +/- SD 136 +/- 27) and NZB (129-169, 148 +/- 12) was significantly lower than in strains CBA (172-267, 209 +/- 31), 101 (179-270, 217 +/- 30), and 129 (215-310, 264 +/- 33). Mice of strain NZB were relatively homogeneous in this trait (CV = 8.1%). Strains AKR, CBA, 101, and 129 displayed significant between-group differences, CV varying from 12.5 to 19.9%. The same DNA specimens were digested with MspI or HpaII and used to estimate the extent of methylation of the 28S rDNA region. Regardless of the strain, all mice could be classed into two groups. One group (20 mice) had a methylated fraction accounting for less than 8% of rDNA and included all nine mice of strain NZB, seven out of nine mice of strain 101, and three out of ten mice of strain 129. In the other group (29 mice), the methylated fraction varied from 18 to 38%. A possible role of methylation and the genome dosage of ribosomal genes in phenotypic variation (quantitative trait variation) of inbred mouse strains is discussed.

Blood serum DNA in patients with rheumatoid arthritis is considerably enriched with fragments of ribosomal repeats containing immunostimulatory CpG-motifs.

We previously hypothesized that the sequence of transcribed region of human ribosomal repeats is selectively accumulated in circulating extracellular DNA due to its increased resistance to double-strand breaks caused by accumulation of single-chain breaks produced by nucleases. The contents of rDNA in blood serum DNA and in DNA from leukocytic nuclei both in healthy donors and in patients with rheumatoid arthritis were compared using dot hybridization method. By the content of non-methylated CpG-repeats, transcribed region of rDNA is identical to bacterial DNA, which is characterized by potent immunostimulatory effect. The transcribed region of rDNA (13.3 kb) contains more than 200 CpG-motifs capable of interacting with TLR9 receptors, which are the mediators of the cell immune response to the action of CpG-rich DNA fragments. The data suggest that DNA from dead cells circulating in the peripheral blood is enriched with sequences possessing potent immunostimulatory properties.

[Smooth muscle cell apoptosis in aneurysmal aortic lesion in the light of surgical treatment results].

Aortic aneurysm is a polyethiologic disease associated with high disability and perioperative mortality rate. The evolution of ethiopathogenesis of aortic aneurysm development is considered in the article. The findings of recent worldwide studies on immune status impact on the disease progress and the postoperative period are presented. All studies showed that 25% of patients had immune status disturbances accompanied by changes in the hemostasis system and high apoptosis index in blood serum and aneurysm tissue. Variants of clinical course of different aortic aneurysm forms and perioperative managements of patients aimed at prevention of possible complications are highlighted.

[Early and late responses to oxidative stress in human dermal fibroblasts of healthy donors and rheumatoid arthritis patients. Relationship between the cell death rate and the genomic dosage of active ribosomal genes].

A study was made of the effect of the oxidizing agent potassium chromate (K2CrO4, PC) on cultured dermal fibroblasts of a healthy donor and three patients with rheumatoid arthritis (RA). Characteristics of the rRNA gene (RG) complex-RG copy number, active RG (ARG) dosage, and 18S rRNA content--were determined for each cell line. In cells of the healthy donor, oxidative stress caused by low doses of PC (2-4 microM, 1-4 h) induced an early response, including a 50-80% increase in total RNA and rRNA. An appreciable activation of the nucleolus was observed cytochemically, by silver staining and morphometry. The early response grew considerably lower with the increasing passage number and/or PC concentration. Exposure to 6-12 microM PC for 24 h led to a progressive cell death (late response). The existence and intensity of the early response correlated positively with the cell survival during further culturing. Cells of the RA patients displayed almost no early response even at early passages: total RNA did not increase, and rRNA increased by no more than 10%. Cell disruption (apoptosis) during further culturing was more intense than in the line originating from the healthy donor. The apoptosis intensity characterized by the increase in the content of DNA fragments in the culture medium and in the caspase 3 activity, was inversely proportional to the ARG dosage in the genome. The results provide the first quantitative characterization of the early and late responses of cells to PC-induced oxidative stress and suggest a role of the ARG dosage in cell survival in stress.

[Quantitative analysis of repetitive sequences in human genomic DNA and detection of an elevated ribosomal repeat copy number in patients with schizophrenia (the results of molecular and cytogenetic analysis)]. / Kolichestvennoe opredelenie povtoriaiushchikhsia posledovatel'nostei v genomnoi DNK cheloveka. Obnaruzhenie uvelichennogo kolichestva ribosomnykh povtorov v genomakh bol'nykh shizofreniei (rezul'taty molekuliarnogo i tsitogeneticheskogo analizov).

A modified version of quantitating repetitive sequences in genomic DNA was developed to allow comparisons for numerous individual genomes and simultaneous analysis of several sequences in each DNA specimen. The relative genomic content of ribosomal repeats (rDNA) was estimated for 75 individuals, including 33 healthy donors (HD) and 42 schizophrenic patients (SP). The rDNA copy number in HD was 427 +/- 18 (mean SE) per diploid nucleus, ranging 250-600. In SP, the rDNA copy number was 494 +/- 15 and ranged 280-670, being significantly higher than in HD. The two samples did not differ in contents of sequences hybridizing with probes directed to a subfraction of human satellite III or to the histone genes. Cytogenetic analysis (silver staining of metaphase chromosomes) showed that the content of active rRNA genes in nucleolus organizer regions is higher in SP compared with HD. The possible causes of the elevated rRNA gene dosage in SP were considered. The method employed was proposed for studying the polymorphism for genomic content of various repeats in higher organisms, including humans.