Evaluation of ribosomal cistron activity in embryos and newborns with Down syndrome

Author: Natia Kulijanishvili
Keywords: Down syndrome, ribosomal cistrons, trisomy
Annotation:

Down's syndrome is one of the well-studied hereditary pathologies from a genetic point of view due to its high frequency in the general population. Although the syndrome has been studied from many perspectives, data regarding variation in such an important genomic feature as the activity of ribosomal cistrons are scarce. This test is very important, from the point of view that it shows high specificity in the case of certain pathologies. The aim of this paper was to evaluate the activity of ribosomal cistrons in the case of Down's syndrome. The research material was used: 1 - cells from lymphocyte cultures of patients with Down's syndrome (postnatal diagnosis), 2 - cells from amniocyte cultures of fetuses with Down's syndrome (prenatal diagnosis) were cultivated in both cases using standard methods. The association rate of acrocentric chromosomes stained by the G-banding method was subjected to analysis. The latter is the main test for determining the activity of ribosomal cistrons. The G-method of differential staining used in the study ensures the identification of associatively active chromosomes and, therefore, creates the possibility of detecting the specific variability of this indicator. A comparative study of the results of pre- and postnatal studies provides an opportunity to exclude the modifying influence of the environment. When determining the level of activity of ribosomal cistrons, as a result of the analysis of the union index in the associations of acrocentric chromosomes, a reliable decrease in the associative activity of the 14th chromosome was revealed. It should be noted that literature data regarding the frequency of association of acrocentric chromosomes containing ribosomal cistrons 13, 14, 15, 21 and 22 in healthy individuals indicate high association activity of the 14th acrocentric chromosome. As a result of the conducted studies, it is concluded that for Down's syndrome, against the background of a general decrease in the activity of ribosomal cistrons (and, correspondingly, the synthetic processes taking place in cells) in both prenatal and postnatal periods, there is a significant decrease in the activity level of ribosomal cistrons localized in the 14th chromosome, which has a specific character.