The conserved fraction of repetitive sequences in the human and mammalian genome in health, in pathology, and for long-term mutagenic exposure

Abstract

The percentage and the size distribution of weakly divergent sites of repetitive sequences of human chromosomal DNA were determined in health and in hereditary genome diseases which are characterized by chromosome instability and predisposition to malignant tumor.

Centriolar Mechanisms of Differentiation and Replicative Aging of Higher Animal Cells

“…And if we remem ber that the culture age (i.e., also Hayflick's limit and aging) is determined by not the time but the number of cell divisions (this is pointed by both supporters and opponents of Hayflick) [3,80,81] and the cell division is directly related with the centrosomal structures, it is reasonably to conclude that the centrosome should be related to the initiation of cell aging, i.e., the mechanism of counting "cell divisions" seems to be concentrated in this organelle.…”

“…Ultimately changing activities of transcriptional factors, this process mediates morphogenesis and differentiation of the cell [64]. Thus, an integral system has been proved to exist which consists of the extracellular matrix, plasma membrane, and cytoskeleton and is involved in spreading and transmis 3 In this paper, we do not concern differences between the centrosome and centriole. Although centrioles are present in the cen trosome of the absolute majority of animal cells, this is not obligatory.…”

“…The cell life duration is thought to be associated with senescence, whereas the replicative potential relates to proliferation, differentiation, and apoptosis [200]. Thus, the telomere hypothesis seems to be poorly related with the essence of aging, and it may be considered only as an explanation of the reason for the existence of Hayflick's limit [3]. But we do affirm that all these mech anisms, in spite of different pathways of realization, are controlled from the same center.…”

“…As noted in [3], "on reaching the final dif ferentiation, somatic cells lose reproductive potential, and from this moment they are condemned to die". This thesis was not refuted even under the boom on plasticity of hemopoietic stem cells (HSC) of bone marrow.…”