[Complexity and diversity of poly(A)-containing mRNAs from different tissues of Bos taurus]

The kinetic complexity of poly(A)+-mRNA isolated from Bos taurus liver, kidney and spleen polysomes has been studied using the mathematical analysis of kinetic curves of hybridisation between mRNA and complementary DNA (cDNA) synthesized by means of reverse transcriptase. Liver, kidney and spleen polysomal mRNA have been found to be represented by 9300, 10 200 and 7200 mRNA types respectively. These mRNA are transcribed from 0.4--0.6% of genome. The sequences of the studied mRNAs are grouped in four discrete classes differentiated by the complexity of polynucleotide sequences and by the frequency per cell. The comparative study of homology of nucleotide sequences of liver, kidney and spleen mRNA has been undertaken using cross hybridization of cDNA with heterologous mRNA. About 40--67% of molecules of the total poly(A)+-mRNA are common for all the tissues under study.