Showing papers on "Regulation of gene expression published in 1968"
459 citations
TL;DR: Evidence that the Spm system can preset a gene locus at one stage in development to give a particular pattern of gene expression at a later stage was obtained from studies of several different gene loci that came under the control of the system.
60 citations
TL;DR: It is concluded that actinomycin inhibits cephalic regeneration of the planarian Dugesia gonocephala “mainly during the first 24 hours following amputation”.
Abstract: ACTINOMYCIN D, a potent inhibitor of nucleic acid syntheses1, has been used in many developing systems to determine immediately gene-dependent events2. Gabriel3 concluded that actinomycin inhibits cephalic regeneration of the planarian Dugesia gonocephala “mainly during the first 24 hours following amputation”. Previous investigations4, however, have suggested that this early period is one of non-specific proliferation and that the definitive gene-dependent events occur later in development.
17 citations
TL;DR: Evidence stems from the induction of puffs in giant chromosomes by the insect hormone ecdysone, the stimulation of nucleic acid synthesis by hormones in vivo and in vitro, and the action of hormones on isolated nuclei where the activity of the DNA-dependent RNA polymerase is stimulated.
Abstract: Regulation of gene expression, i.e. the reading of the genetic message, is of great importance for many vital processes. According to Jacob and Monod, genes are regulated by a “repressor” (a protein) which may interact with an “inducer” (a small molecule). In higher organisms, hormones often function as inducers. Evidence stems from (i) the induction of puffs in giant chromosomes by the insect hormone ecdysone, (ii) the stimulation of nucleic acid synthesis by hormones in vivo and in vitro, (iii) the induction of enzymes by hormones, e.g. cortisol, and (iv) the action of hormones on isolated nuclei where the activity of the DNA-dependent RNA polymerase is stimulated. This is most probably due to an increased template activity of the chromatin. — The implication of these findings for developmental processes are discussed.
10 citations
TL;DR: A new schema of genetic regulation in bacteria is proposed based on the following two points: a) All nonsense mutations would not have the same probability of preventing the translation and b) There would be interactions of competitive type between the short m-RNA and the homologous long m- RNA.
Abstract: We propose a new schema of genetic regulation in bacteria. This schema is based on the following two points: 1. a) All nonsense mutations would not have the same probability of preventing the translation. 2. b) There would be interactions of competitive type between the short m-RNA and the homologous long m-RNA. According to this hypothesis, the regulator and operator genes appear only as simple structural genes. Each structural gene may have a regulatory, coordinated function on all the not necessarily linked genes which control the synthesis of the enzymes of a metabolic pathway. The result is a new conception of the operon. Repression and induction are regulated by the same mechanism. This new hypothesis proves to be in agreement with the observations that support the model proposed by Jacob and Monod.
2 citations
01 Jan 1968
TL;DR: This chapter explains the rapidity of variations in gene activity in differentiated cells, which is capable of responding to the appropriate environmental stimuli with the same rapidity as the bacterial genome, within a brief period of time ranging from seconds to 1 or 2 minutes.
Abstract: This chapter explains the rapidity of variations in gene activity in differentiated cells. A temporal aspect of gene control over cellular function is the rapidity of response in metazoan cells toward activation signals of external origin. It is at present well known that inducible bacterial systems react almost at once to the appropriate inductive stimulus. The metazoan cell genome is capable of responding to the appropriate environmental stimuli with the same rapidity as the bacterial genome, that is., within a brief period of time ranging from seconds to 1 or 2 minutes. A temporal asymmetry, thus, exists in the metazoan genomic control system in the sense that change in the patterns of cell function resulting from gene activation can be effected with far greater temporal sharpness than can control by gene repression, even though the genome-level response may be equally rapid in cases of external signals causing gene repression. The asymmetry follows [A7]
1 citations