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Showing papers on "Regulation of gene expression published in 1977"


Journal ArticleDOI
TL;DR: The degree of hypomethylation of DNA and tRNA from FL cells induced to differentiate with dimethylsulfoxide and butyrate, and DNA isolated from cells exposed to any of the three inducers, suggest that methylation ofDNA may play a role in the regulation of gene expression.
Abstract: This report identifies l-ethionine as an inducer of differentiation in murine erythroleukemia cells. When Friend erythroleukemia cells are grown in the presence of 4 mM l-ethionine, globin mRNA accumulates and in 4–5 days, 25–30% of the cells in the culture contain hemoglobin. Incubation of the cells with bromodeoxyuridine prevents both ethionine-induced accumulation of globin mRNA and erythroid differentiation. At the concentration where l-ethionine acts as an inducer of FL cell differentiation it inhibits methylation of DNA and tRNA in vivo but does not prevent macromolecular synthesis or cell division. To establish whether a link existed between inhibition of a specific methyltransferase and activation of globin synthesis in FL cells, we examined the degree of hypomethylation of DNA and tRNA from FL cells induced to differentiate with dimethylsulfoxide and butyrate. In contrast to the tRNA from ethionine-treated cells, tRNA from cells induced by butyrate or Me2SO cannot be methylated in vitro using homologous enzymes. DNA isolated from cells exposed to any of the three inducers, however, was significantly hypomethylated when compared with DNA from uninduced cells. These data suggest that methylation of DNA may play a role in the regulation of gene expression.

194 citations


Journal ArticleDOI
20 Jan 1977-Nature
TL;DR: This work presents evidence of extensive gene silencing in the 50-Myr history of a family of tetraploid fishes and suggests that those species regarded by systematists as advanced may have lost the expression of more duplicate genes than primitive species.
Abstract: INCREASES in cellular DNA content have been important in the evolution of eukaryotes1–3. One mechanism for increasing DNA content is polyploidisation, which has been observed in a wide variety of organisms4–8, and which is believed to have preceded the evolution of the early vertebrates9. It has been suggested that, following gene duplication, many of the redundant copies would be silenced early in evolution by mutation10,11. Those duplicate genes remaining expressed are then available to diverge in structure and acquire new functions9. We present evidence of extensive gene silencing in the 50-Myr history of a family of tetraploid fishes. Furthermore, those species regarded by systematists as advanced (that is, morphologically divergent from the ancestral form) may have lost the expression of more duplicate genes than primitive species (that is, those with a morphology similar to the ancestral form).

182 citations


Journal ArticleDOI
TL;DR: Hypotheses are suggested in an attempt to explain the data in tissue preparations and whole animals which suggest that regulation of the synthesis of at least some proteins by cAMP-dependent protein kinases does occur at the transcriptional level.

96 citations



Journal ArticleDOI
TL;DR: The preferential binding of biologically active molecules in general to chromosomal proteins could result in the exposure and transcription of deoxyribonucleotide sequences with subsequent production of specific receptor proteins, as detailed by O'Malley and co-workers.
Abstract: A broad spectrum of naturally occurring substances and synthetics is known to influence responses in a variety of biological systems. Substances classified as hormones, phytohormones, pheromones, antigens, carcinogens, antibiotics, etc., range widely in structure from exotic steroids to straight chain aliphatics; the functional groups on these small molecules are equally diverse, for example, the presence of esters, amines, alcohols, phosphates, ethers, and others. Despite this chemical diversity, it appears logical to expect some similarity in the mechanisms by which this array of molecular species influences biological processes. The action of some regulatory molecules may involve their initial interactions with proteins which somehow eventually result in gene action. Accordingly, O'Malley and co-workers [1,2] have detailed such a mechanism in the action of steroid hormones with the nonhistone protein components of DNA. Hence, the preferential binding of biologically active molecules in general to chromosomal proteins could result in the exposure and transcription of deoxyribonucleotide sequences with subsequent production of specific receptor proteins. However, the details concerning the origin of a specific protein(s) which recognizes one regulatory molecule from a host of other substances in a cell or the regulation of transcription and translation of genetic information into proteins involved in a given cellular function are not clear. Indeed, inspection of the chemistry of DNA and RNA indicates that while the multiplicity of nucleotide sequences may be responsible for coding the primary structural differences among proteins, the array of specific recognition sites

56 citations


Journal ArticleDOI
TL;DR: Catalytically active mouse beta-glucuronidase is formed when Xenopus oocytes are injected with mouse RNA enriched for poly(A)-containing mRNA sequences, and makes available an opportunity to study the regulation of post-translational polypeptide processing of a lysosomal enzyme.
Abstract: Catalytically active mouse beta-glucuronidase (beta-D-glucuronide glucuronosohydrolase, EC 3.2.1.31) is formed when Xenopus oocytes are injected with mouse RNA enriched for poly(A)-containing mRNA sequences. With the RNA from androgen-induced kidneys, the efficiency of translation is comparable to that of endogenous Xenopus messenger, and the fidelity of translation is high. Detection of glucuronidase messenger by formation of a catalytically active product is several orders of magnitude more sensitive than detection by incorporation of isotopically labeled amino acids. As well as providing a sensitive technique for examining the regulation of gene expression, the system makes available an opportunity to study the regulation of post-translational polypeptide processing of a lysosomal enzyme.

49 citations


Journal ArticleDOI
TL;DR: The results establish conditions for maximal estrogen-induced responses in this system, and are compatible with the hypothesis that a major regulatory mechanism of steroid hormones in the control of protein synthesis is that of gene activation and regulation of messenger RNA levels.
Abstract: The vitellogenin gene is inactive in the liver of male Xenopus laevis, unless exogenous estrogen is administered. We have previously shown that conventional doses of estradiol-17beta result in the appearance of new hepatic messenger RNAs, some of which are encoded for vitellogenin. We now report that much higher doses of the hormone (2 mg/frog per day for 4 days) are required to elicit maximal responses. The relative levels of membrane-bound polysomes and vitellogenin mRNA were determined as a function of time and dose of hormone. Translation of total polysomal RNA in a cell-free system derived from wheat germ was used to estimate the relative levels of vitellogenin messenger RNA. Faithful translation of this messenger RNA was indicated by two lines of evidence: labeled cell-free products were immunoprecipitated with antivitellogenin antibody, and the migration of the major labeled product in sodium dodecyl sulfate/acrylamide gels was identical to that of native vitellogenin. Our results establish conditions for maximal estrogen-induced responses in this system, and are compatible with the hypothesis that a major regulatory mechanism of steroid hormones in the control of protein synthesis is that of gene activation and regulation of messenger RNA levels.

42 citations


Journal ArticleDOI
TL;DR: These analyses indicate that there is stage-specific protein synthesis in the primary spermatocyte which is characterized by differential activation of the LDH-C locus and of the gene coding for cytochrome ct.

23 citations


Book ChapterDOI
TL;DR: The chapter discusses the gene regulation at the different levels at which the activation or repression of chromatin seems to occur—the whole nucleus, the individual chromosome, the large block of genes, and the individual gene locus.
Abstract: Publisher Summary This chapter discusses the range of mechanisms implicated in the activation and repression of chromatin. Whereas the genomic DNA of prokaryotes is neutralized by relatively small molecules such as polyamines, the DNA of eukaryotes is complexed with relatively large amounts of basic protein, normally histone. The molecular complexity of eukaryotic chromatin, and the very large amounts of DNA in the genomes of most eukaryotic organisms, not only suggests that many mechanisms of gene control are unique to higher organisms, but also render the investigation of eukaryotic genetic regulation much more difficult. The chapter discusses the gene regulation at the different levels at which the activation or repression seems to occur—the whole nucleus, the individual chromosome, the large block of genes, and the individual gene locus. Such an approach helps to reveal the great range of factors and processes involved in eukaryotic gene regulation. Techniques involving radioactive complementary DNA probes render the detection of specific mRNA molecules feasible, some regulatory molecules and control sequences have been characterized, at least in bacteria, and at last light seems to be dawning on the vexing question of the physical organization of DNA-histone complexes.

20 citations


Journal ArticleDOI
TL;DR: T1 infected bacteria exhibit a distinct pattern of gene expression and the control of this expression is accessible to biochemical analysis, and the positive control of late gene expression is not coupled to replication.
Abstract: T1 infected bacteria exhibit a distinct pattern of gene expression. The control of this expression is accessible to biochemical analysis. T1 induces the synthesis of 31 proteins inE. coli. The virion contains 15 proteins. By means of T1 amber mutants, 10 gene products have been assigned to specific T1 genes. Three classes of T1 proteins are defined by the kinetics of their syntheses: early, early-late and late proteins. The regulation of protein synthesis involves at least three mechanisms: for cessation of host gene expression, for discontinuation of the early class during the late phase and for induction of the late T1 proteins. The positive control of late gene expression is not coupled to replication. The host RNA-polymerase transcribes the viral genome throughout the infectious cycle. No virus coded RNA-polymerase is induced.

19 citations


Journal ArticleDOI
TL;DR: Isozyme patterns in homogenates from various testicular cell types from mice were examined in an effort to ascertain whether the haploid genome is expressed during spermiogenesis as mentioned in this paper.
Abstract: Isozyme patterns in homogenates from various testicular cell types from mice were examined in an effort to ascertain whether the haploid genome is expressed during spermiogenesis. Male mice heterozygous for electrophoretic variants of several glycolytic enzymes were analyzed by starch gel electrophoresis. The enzymes examined were isocitrate dehydrogenase, glucose-6-phosphate dehydrogenase, and glucosephosphate isomerase. The isozyme patterns produced by these dimeric enzymes reflect the relative activity of genes in each cell type. These patterns reveal the presence or absence of the transcription of specific genes during spermiogenesis. We found that the genes encoding these enzymes continue to increase during spermiogenesis. Synthesis of these enzymes most likely continues in spermatids, but this synthesis must depend upon premeiotically produced mRNA. These data provide biochemical evidence for the hypothesis that the phenotype of the haploid mammalian gamete depends upon the preceding diploid genome and that a mechanism must exist for the long term post-transcriptional regulation of gene expression during spermiogenesis.

Journal ArticleDOI
TL;DR: A more rigorous proof for functional homology in early gene regulation of P22 and Px1 is presented and suggests the presence of a separate, and oR-independent, promotor for late gene expression.
Abstract: Phage P22 replicates in Px1-lysogenic cells because the ant-product (“antirepressor-protein”) of P22 removes the repression exerted by the Px1-prophage. P22 ant - phages however are repressed in Px1-lysogens. The ant-product of P22 is also required for the transactivation of the “early” genes 24, 12, and 23 of the Px1-prophage. P22 virB3 ant - mutants, which are insensitive to c-repression and therefore replicate in Px1-lysogens, are unable to transactivate early genes of the Px1-prophage or of a coinfecting Px1 phage. Transactivation of the “late” gene 19 is insensitive to repression and independent of ant-activity. This suggests the presence of a separate, and oR-independent, promotor for late gene expression. —A more rigorous proof for functional homology in early gene regulation of P22 and Px1 is presented.

Journal Article
TL;DR: The results suggest that for repetitive sequence transcripts, massive "derepression" of the genome does not occur at the early stages of liver regeneration, and increased transport of repetitive sequence transcriptions from nucleus to cytoplasm appears to take place in regenerating liver.
Abstract: To determine whether massive gene activation occurs in rat liver following partial hepatectomy, DNA-RNA hybridization-saturation and RNA depletion experiments were performed. RNA was extracted from whole cells, nuclei, post-mitochondrial extracts, and polysomes obtained from livers of normal, sham-operated, and partially hepatectomized rats. The purified RNA was labeled with [3H]dimethyl sulfate in vitro and hybridized with nuclera DNA under conditions in which only repetitive sequence transcripts form hybrids with DNA. For comparative purposes, experiments were also performed with nuclear RNA labeled with [32P3phosphoric acid in vivo. The following observations were made: (a) for whole-cell RNA the saturation levels obtained in the hybrization reaction are the same regardless of the source of RNA USED (NORMAL, SHAM-OPERATED, OR PARTIALLY HEPATECTOMIZED RATS); (B) NO DIFFERENCES IN THE SATURATION LEVELS WERE FOUND WHEN LIVER NUCLEAR RNA from these three groups of animals were used; (c) the concentration of nuclear RNA from 6-hr regenerating liver necessary to saturate the DNA is slightly higher than that of nuclear RNA obtained from normal rat liver; (d) cytoplasmic RNA from 6-hr regenerating liver saturates the DNA at a much lower concentration than that required for RNA from normal or sham-operated rats. Our results suggest that for repetitive sequence transcripts, massive "derepression" of the genome does not occur at the early stages of liver regeneration. The alterations detected reflect primarily changes in RNA concentrations rather than qualitative alterations in gene expression. Increased transport of repetitive sequence transcripts from nucleus to cytoplasm appears to take place in regenerating liver.

Journal Article
TL;DR: A general approach to purify and sequence DNA fragments of a specific gene starting with a heterogeneous mixture of mRNAs and some selectivity in the codon choices was found, and this may be important for RNA or gene regulation or structure.
Abstract: In summary, a general approach is presented to purify and sequence DNA fragments of a specific gene starting with a heterogeneous mixture of mRNAs. The methodology has been applied to the determination of the DNA sequence of a portion of the gene for human chorionic somatomammotropin. Most of the possible translation codons of the genetic code were found to be used. Some selectivity in the codon choices was found, and this may be important for RNA or gene regulation or structure. The stop codon UAG was found and a second stop codon in the same reading frame was found nine bases farther down. Finally, a "palindrome" sequence was detected in the 3' noncoding region.

Journal ArticleDOI
TL;DR: Electrophoretic analysis of acetate incorporation into gastrula acid-soluble crude chromatin protein showed that acetate was almost completely incorporated into histones and not into other proteins found in the acid extract of crude Chromatin, suggesting that histone acetylation may be part of the underlying biochemical mechanism of embryonic differentiation.

Book
01 Jan 1977
TL;DR: This paper presents a systematic literature review and meta-analyses of viral gene expression and integration at the cellular level using a probabilistic procedure called “ Nak-acycline-like correction”.
Abstract: REGULATION AND GENETICS : viral gene expression and integration , REGULATION AND GENETICS : viral gene expression and integration , کتابخانه مرکزی دانشگاه علوم پزشکی ایران


Journal Article
TL;DR: Evidence was obtained that in the course of the degenerative osteoarthrosis chondrocytes switch from synthesis of type II collagen to synthesis of types I and III collagen.
Abstract: The polymorphism of collagen was the initial observation which stimulated the interest in the regulation of the gene expression of this eucaryotic protein. In the first set of experiments it was shown that a fibroblast from fetal skin possesses the capability to synthesize both type I and type III collagen at the same time. In a second line of investigations, evidence was obtained that in the course of the degenerative osteoarthrosis chondrocytes switch from synthesis of type II collagen to synthesis of type I collagen. A similar observation was made when enzymatically isolated chondrocytes from the sterna of embryonic chicken were grown under tissue culture conditions. This change in synthesis probably reflects a change in gene regulation which might be caused by an as yet unknown disturbance in the cell matrix interaction.


Journal ArticleDOI
TL;DR: A well-established prokaryotic regulatory system is used for the exploration of mitochondrial gene regulation using DNA of the bacterial virus as a template for gene expression in a mitochondrialin vitro system.
Abstract: Mitochondria and bacteria possess protein synthesizing machineries which are similar in many respects; The regulation of gene expression in mitochondria is unknown. We, therefore, tried to use a well-established prokaryotic regulatory system for the exploration of mitochondrial gene regulation. DNA of the bacterial virus can be used as a template for gene expression in a mitochondrial in vitro system. The gene directed enzyme synthesis in the mitochondrial system is the basis for a study of regulation in mitochondrial protein synthesis.

Book ChapterDOI
01 Jan 1977
TL;DR: This chapter discusses translational and transcriptional control of protein synthesis during differentiation of Dictyostelium discoideum and gene expression during differentiation.
Abstract: Publisher Summary This chapter discusses translational and transcriptional control of protein synthesis during differentiation of Dictyostelium discoideum. To study the regulation of gene expression in a differentiating system such as Dictyostelium, one must identify genes whose expression is regulated. There are many examples of enzymic activities and surface antigens or proteins that appear or disappear at prescribed times of differentiation. However, in very few cases, it is completely clear whether the increase in activity is because of an increase in the rate of synthesis of the enzyme or antigen protein or to some other factor. The chapter also discusses gene expression during differentiation.


Book ChapterDOI
David Fromson1
01 Jan 1977
TL;DR: This review will not include an analysis of the inhibition of genetic expression by various drugs and teratogens, and will concentrate on describing the sites of regulation of genetic activity.
Abstract: The major purpose of this review is to outline and indicate the major steps in the regulation of gene activity in eukaryotes at the molecular level. This review will not include an analysis of the inhibition of genetic expression by various drugs and teratogens. Rather, it will concentrate on describing the sites of regulation of genetic activity; genetic activity is defined as the production and utilization of messenger RNA (mRNA).



Journal ArticleDOI
TL;DR: The regulation of lactose operon in Escherichia coli has been discussed as a model system for studies on the regulation of gene expression in animal systems and specific polysomes involved in the synthesis of acetyl-CoA carboxylase are identified.
Abstract: We have discussed the regulatory mechanisms of gene expression in higher animals, covering the following aspects on the basis of our recent results: 1. The regulation of lactose operon inEscherichia coli has been discussed as a model system for studies on the regulation of gene expression in animal systems. 2. Acetyl-CoA carboxylase plays a critical role in the regulation of biosynthesis of long-chain fatty acids. In an attempt to gain insight into the molecular mechanisms underlying the regulation of synthesis of hepatic acetyl-CoA carboxylase, we have been able to identify specific polysomes involved in the synthesis of this enzyme. Furthermore, it has been demonstrated that the relative content of these polysomes in the liver correlates well with the rate of hepatic synthesis of the enzyme under different dietary and hormonal conditions. 3. The pituitary hormone, corticotropin (ACTH), which is a single polypeptide consisting of 39 amino acids, has some interesting features with respect to the regulation of its biosynthesis. First of all, we have attempted to synthesize ACTH in a cell-free heterologous system. Our studies indicate that ACTH mRNA is translated in wheat germ extracts into a product which contains the amino acid sequence of ACTH but is much larger (M.W. approximately 35,000) than this hormone (M.W. approximately 4,500).

Book ChapterDOI
Horst Binding1
01 Jan 1977
TL;DR: Gene regulation in higher plants has been or is currently reviewed in this periodical by HUTTER, NAGL, HERZFELD, DORFLING, and FELLENBERG.
Abstract: The pathways of gene expression in prokaryotic cells are understood in great detail. Investigations in eukaryotes revealed a high degree of homology. The intention of this article is to cover the mechanisms of the expression of nuclear genes in higher plant cells. The sections will be introduced by short summaries of the general feature with special references. Gene regulation in higher plants has been or is currently reviewed in this periodical by HUTTER, NAGL, HERZFELD, DORFLING, and FELLENBERG. Only some aspects of gene regulation will be discussed here.