[Kinetics of the synthesis of nucleic acids in haploid and diploid loach embryos].

Al kinetic analysis of incorporation of the mixture of 3H-nucleosides in the nucleic acid fractions was carried out to examine the mechanisms of compensation of the genetic material deficiency. Both the haploid and diploid embryos of the loach (Misgurnus fossilis L.) were analyzed. When comparing the DNA and RNA syntheses, the level of phosphorylation (nucleotide pool) in the both genetic variants was under control. The rate of incorporation of the labelled nucleosides in DNA was shown to be higher in haploids at the early developmental stages than in diploids but later it became the same. The increased level of DNA replication in the early haploid embryos was due to the compensatory increase of the cell number in them as compared with the diploid ones. The rate of total RNA synthesis corrected by the differences in the rate of nucleoside phosphorylation varied directly with the degree of ploidy at the blastula stage; at the gastrula stage the value of RNA synthesis per haploid genome was compensated, and at the stage of organogenesis the production of total RNA, as calculated per cell, became in haploids even higher than in diploids. The data obtained suggest the essential changes in the patterns of RNA synthesis control during development.