On a model for ontogenic development.
A theory to explain both the endogenous control of differentiation and programmed organismal aging as the result of one fundamental regulatory mechanism is advanced. It is postulated that these phenomena are linked to cell division, which is presumed to be the primary unit of measurement for the organism's maturation and aging. The hypothesis developed here holds that a genetic locus (DSI), modulating both cell division and enzyme induction, is first activated and then inactivated with each cycle. The number of DSIs in the genome of each cell is finite, cellular sensescence occurring when the genome is depleted of functional DSIs. Protein inducers are linked to specific DSIs, which are only transcribed at appropriate times during ontogeny, this in turn being a function of the number of DSIs previously inactivated during earlier mitoses. Experimental approaches which could test this model are discussed.
D001402:B-Lymphocytes / Q000166:cytology; D005075:Biological Evolution; D002455:Cell Division; D002874:Chromosome Mapping; D004247:DNA / Q000096:biosynthesis; D005796:Genes; D008954:Models, Biological; D011506:Proteins; D012333:RNA, Messenger; D014158:Transcription, Genetic
D011506:Proteins; D012333:RNA, Messenger; D004247:DNA