State of nucleolus organizers in hybrids of pluripotent and somatic mouse cells cultivated under different conditions
In the present work, we studied the state of chromosomal nucleolar organizing regions (NOR) in hybrid cells obtained by fusion of cells of embryonal carcinoma of a murine line PCC4aza1 and of cells of adult mouse spleen at cultivation of hybrids under different conditions. The obtained results have shown that long-term cultivation of hybrid cells in a selective medium containing HAT (hypoxanthine, aminopterin, thymidine) promotes preservation of nucleolar organizing chromosomes (NO chromosomes), whereas in nonselective medium predominant elimination of NO chromosomes was revealed. Under nonselective conditions, an increased number of active, i.e., Ag-positive, NORs was observed as compared to under selective conditions. These observations directly show that reprogramming of parent cell genomes in hybrids includes changes in the state of NO chromosomes. The number of active NORs depends on the conditions of cultivation of hybrid cells and can change in two main ways, i.e., by the elimination of NO chromosomes (under nonselective conditions) or by the inactivation of some NORs with maintenance of NO chromosomes (under selective conditions).
Key wordshybrid cells reprogramming nucleolar organizers argentophilic staining of nucleolus organizers hybridization in situ
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