EXTRA-CELLULAR DNA FOR THE UNSOLVED EVOLUTIONAL PROBLEMS

The genome assembly and new sequencing methods shed light on extra-cellular DNA (ecDNA) content and uptake. The recent data are described. The asymmetry in repetitive sequences distribution in ecDNA are shown: 1) significant enrichment in pericentromeric tandem repeats (TR), but decrease of centromeric alpha-satellite; 2) enrichment in Alu (SINE) but decrease of LINEs. In the genomes, Alu repeats (SINE) are located mostly to the gene-rich regions, while LINEs enrich facultative heterochromatin as evidenced by bioinformatics and cytological data (FISH). Human shows a greater fraction of tissue-specific genes and a greater ratio of the total expression of tissue-specific genes to housekeeping genes in each tissue studied. A higher level of evolutionary cell differentiation (specialization) in human correlates with the substitution of 4 mouse SINEs with Alu (SINE) repeat. Sperm-mediated gene transfer became the ordinary methods of the veterinary. The overall substitution of ecDNA SINEs in the whole genome by recombination is possible due to Alu element and mouse B1 (SINE) sequence similarity. The orthologous genes are not altered initially but chromatin landscape change lifts up the transcription and provides the evolutionary advantage for the newly born species. So, the scheme suggested may remove two of the contradictions of the Modern evolutionary synthesis theory: 1) gene mutations are not necessary for the progressive evolution but repetitive elements substitution; 2) ancient mammalians could have litters with the number of offspring altered by ecDNA and inbred mating was possible for the descendant altered.