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Regulation Of Growth And Differentiation: This work suggests that drugs, hormones, and other powerful biologically active compounds control the activity of specific genes in man by altering the attachment of regulatory proteins to the DNA, either permitting or inhibiting the expression of the genetic potential of a given cell. All in all, the basic hypotheses of gene regulation and their chemical confirmation provide extremely powerful models with which to explain many aspects of the regulation of growth and differentiation in higher organisms as well as in simple bacteria.
The synthesis of dormin (abscisin II), known to play a major role in controlling the dormancy of buds, tubers, and seeds, provided a significant advance in 1967 in the study of plant growth regulation. In an analysis of the inhibiting mechanism in Lemna minor (duckweed), concentrations of one part per million of this synthetic compound inhibited growth by about 95%. DNA synthesis appeared to be suppressed, and the breaking of the dormancy was thought to be caused by reactivation of the enzyme DNA-polymerase by a growth hormone.
Among other discoveries bearing on the overall problem of differentiation and regulation of the genome was the demonstration in several laboratories that tumor viruses can regulate DNA synthesis. Mammalian and avian (bird) cells that were in the terminal stages of differentiation and in which DNA synthesis had stopped were reactivated by viruses. Specially cultured cells from embryonic skeletal muscle Tissue (from hamster, rat, mouse, man, and chick) showed induced DNA synthesis after being infected by the viruses. Probably only part of the genome was stimulated. |
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