Showing papers on "Gene expression published in 1979"
TL;DR: This co-transformation system should allow the introduction and stable integration of virtually any defined gene into cultured cells and is likely to represent a subpopulation of competent cells which are likely to integrate other unlinked genes at frequencies higher than the general population.
1,281 citations
TL;DR: The hormonal regulation of casein gene expression appears to be an "all or none" process occurring only at the transcriptional or post-transcriptional levels, but may involve a coordinated response at several levels to permit the efficient expression of specialized differentiated functions.
438 citations
TL;DR: It is suggested that splicing is a prerequisite for stable RNA formation in viruses carrying various combinations of splice junctions derived from the viral genome and a mouse globin gene.
229 citations
TL;DR: Correlation of haematological data and the location of deletions in two cases of HPFH and one case of δβ-thalassaemia suggest that a region of DNA located near the 5′-end of the δ- globin gene may be involved in the suppression in cis of γ-globin gene expression in adults.
Abstract: Deletions in the DNA of individuals with hereditary persistence of fetal haemoglobin (HPFH) and 8 beta-thalassaemia have been mapped as a means of identifying regulatory sequences involved in the switch from fetal to adult globin gene expression. The end points of these deletions have been precisely located with respect to restriction endonuclease cleavage sites within and surrounding the gamma-, delta- and beta-globin genes in normal human DNA and the deletion maps were used to obtain definitive evidence for the physical linkage of the fetal and adult beta-like globin genes in the order 5'Ggamma-Agamma-delta-beta 3'. Correlation of haematological data and the location of deletions in two cases of HPFH and one case of deltabeta-thalassaemia suggest that a region of DNA located near the 5'-end of the delta-globin gene may be involved in the suppression in cis of gamma-globin gene expression in adults. The interpretation of a second case of deltabeta-thalassaemia is complicated by the fact that the deletion removes the Agamma-gene in addition to the region near the 5'-end of the delta-globin gene.
227 citations
TL;DR: The results reported here suggest that a glucocorticoid receptor and the induction of gene expression are involved in the anti-inflammatory action of dexamethasone.
Abstract: GLUCOCORTICOIDS are potent anti-inflammatory agents, but the molecular mechanisms involved in this activity are not yet understood. The biological actions of various steroid hormones have been shown to be mediated by functional proteins synthesised following translocation of a hormone-cytoplasmic receptor complex into the nucleus1,2. It is still not clear, however, whether the anti-inflammatory effects of glucocorticoids are mediate via binding to a cytoplasmic receptor in target cells and subsequent activation of gene expression3, although glucocorticoid receptors have been demonstrated in HTC cells, liver5, thymocytes6 and lymphocytes7. The results reported here suggest that a glucocorticoid receptor and the induction of gene expression are involved in the anti-inflammatory action of dexamethasone.
203 citations
TL;DR: The involvement of promoters in Nal and novobiocin action, as well as a possible role of in vivo negative supercoiling in the selectivity of gene expression, are discussed.
Abstract: Nalidixic acid (Nal), a drug which affects deoxyribonucleic acid gyrase activity, inhibits the expression of catabolite-sensitive genes: the three maltose operons, the lactose and galactose operons, and the tryptophanase gene. A correlation between the degree of sensitivity to Nal and that to catabolite repression has been observed. The expression of the threonine and tryptophan operons, insensitive to catabolite repression, is insensitive to Nal. The expression of the lacZ gene under the control of the IQ promoter is activated by Nal. Strains carrying a mutation in the nalA locus are resistant to these effects. Novobiocin, which inhibits the negative supercoiling activity of deoxyribonucleic acid gyrase, affects expression of the operons similarly to Nal. The involvement of promoters in Nal and novobiocin action, as well as a possible role of in vivo negative supercoiling in the selectivity of gene expression, are discussed.
187 citations
TL;DR: Establishment of the primary structure of this glyceraldehyde-3-phosphate dehydrogenase gene provides a basis for further studies involving in vitro mutation of the gene and subsequent analysis of gene expression in vivo.
170 citations
TL;DR: Transcription of all early regions was initiated and continued for at least 2 to 3 h in cells that were treated with cycloheximide or emetine before and during infection, suggesting that at least the initiation of RNA synthesis from the five early adenovirus type 2 transcription units does not depend on the formation of a viral protein.
Abstract: The time course of appearance of transcriptional activity from five early adenovirus type 2 transcription units has been determined. RNA complementary to region 1A (1-4.4 map units), the first region to be transcribed, was detectable at 45 min after infection; a maximal rate of RNA synthesis was reached at 3 h after infection and was maintained thereafter for at least 6 h. RNA from region 2 (75-56 map units), which encodes the mRNA for the 72,000-dalton DNA-binding protein, was the last to be synthesized; transcription commenced at about 2 h postinfection, reached a maximum at 7 h, and then declined. Transcription of regions 3 (76-86 map units) and 4 (99-91 map units) reached a maximal value at 3 h postinfection. The rates of RNA synthesis from these regions then declined over the next 6 h. The decline of transcription from regions 2 and 4 appeared to be a specific repression of these transcription units. The repression did not occur in the absence of protein synthesis, suggesting that a viral protein might be involved. Transcription of all early regions was initiated and continued for at least 2 to 3 h in cells that were treated with cycloheximide or emetine before and during infection, suggesting that at least the initiation of RNA synthesis from the five early adenovirus type 2 transcription units does not depend on the formation of a viral protein. Moreover, mRNA was formed in the absence of protein synthesis that hybridized to DNA fragments representing each of the five early transcription units. The increase in mRNA accumulation in the presence of cycloheximide (or emetine) does not appear to be due to increased RNA synthesis; thus, either increased mRNA stability or increased efficiency of nuclear RNA processing must occur.
163 citations
TL;DR: Results indicate that gene expression in M. xanthus is complex and subject to tight regulation, and that methionine blocks a late stage of development.
138 citations
TL;DR: Data are presented that indicate that the z locus of Drosophila melanogaster represses w locus activity, but the repression is effective only on paired or physically adjacent w loci.
Abstract: Data are presented that indicate that the z locus of Drosophila melanogaster represses w locus activity, but the repression is effective only on paired or physically adjacent w loci. Various mutant alleles of z and w were combined in a series of different doses to determine the effect of dosage and physical position in the nucleus on gene expression. In z/z individuals, paired white alleles fail to be expressed, while unpaired alleles are expressed normally. The results are discussed in terms of a model postulating that the z gene product represses the transcription of w+ by complexing with an RNA produced by part of the white locus itself. In order to be effective in repression, there must be two w+ genes producing the RNA in a limited volume in the nucleus. Such a model necessarily imposes a specific architecture on the chromatin of interphase nuclei.
123 citations
TL;DR: Findings are not inconsistent with the hypothesis that histone hyperacetylation may be a necessary, but obviously not sufficient, part of the biochemical mechanisms leading to new genomic expression in Friend erythroleukemic cells.
TL;DR: Cytoplasmic RNA, isolated at various times after vaccinia virus infection, was translated in a message-dependent cell-free system prepared from rabbit reticulocytes, and a correlation between RNA sedimentation and molecular weight of translation product was obtained.
TL;DR: The major modulations of histone gene expression are neither abrupt nor an absolute on-off switch, and may represent only a gradual and relative repression of early gene expression.
TL;DR: This study analyzed the influence of the flagellar genes on the expression of the hag gene (structural gene forflagellin) by constructing a hag::Mu d(Apr lac) mutant which allowed the measurement of hag Gene expression by detection of beta-galactosidase activity.
Abstract: Previous studies have defined 28 genes necessary for the synthesis of the flagellar apparatus of Escherichia coli K-12. This study analyzed the influence of the flagellar genes on the expression of the hag gene (structural gene for flagellin). To this end, a hag::Mu d(Apr lac) mutant which had the lac genes fused to the promoter of the hag gene was constructed. This allowed the measurement of hag gene expression by detection of beta-galactosidase activity. The following observations were made. (i) The hag gene was expressed constitutively in Fla+ cells. (ii) hag gene expression was positively regulated by flaA, FLAB, flaC, flaD, flaE, flaG, flaH, flaI, flaK, flaL, flaM, flaN, flaO, flaP, flaQ, flaR, flaV, flaW, flaX, flaY, flaZ, flbA, and flbB genes.hag-lac expression was not observed in strains with these fla mutations. (iii) The hag gene was expressed in mutants with flaS, flaT, flaU, and flbC defects. Therefore, these genes were not involved in regulation of hag gene transcription.
TL;DR: It is demonstrated here that withdrawal of diethylstilbestrol resulted in a depletion of high-molecular-weight ovalbumin RNA and of mature ovalbumIn mRNA and that readministration of the estrogen induced the nuclear accumulation of both forms of ovalbum in RNA.
Abstract: The transcription of structural and intervening sequences of the chicken ovalbumin gene was studied in nuclei isolated from the oviduct, liver, and spleen of chickens in different states of estrogen simulation. The concentration of transcripts of structural and intervening DNA sequences was determined by hybridizing the newly synthesized [3H]RNA to filters containing cloned ovalbumin cDNA (pOV230) or fragments of the natural ovalbumin gene (pOV2.4 and pOV1.8). Of the RNA synthesized by oviduct nuclei from chickens chronically stimulated with diethylstilbestrol, 0.23% corresponded to ovalbumin mRNA and 0.17% were transcripts of intervening sequences. No detectable ovalbumin mRNA sequences were synthesized by nuclei from spleen and liver. After 60 hr of hormone withdrawal, synthesis of ovalbumin mRNA by oviduct nuclei could not be detected. After readministration of estrogen, a gradual increase in ovalbumin mRNA synthesis was observed which began at 1 hr and reached a plateau by 8 hr. For the intervening sequences, similar kinetics were observed for the initial 4 hr. Previously we had identified multiple species of putative precursors of ovalbumin mRNA in oviduct nuclei from chickens chronically stimulated with diethylstilbestrol. We demonstrate here that withdrawal of diethylstilbestrol resulted in a depletion of high-molecular-weight ovalbumin RNA and of mature ovalbumin mRNA and that readministration of the estrogen induced the nuclear accumulation of both forms of ovalbumin RNA. These findings indicate that: (i) a method exists to assay synthesis of hormone-inducible specific eukaryotic [3H]mRNA in vitro; (ii) the estrogen-mediated preferential expression of the ovalbumin gene is maintained in isolated oviduct nuclei; (iii) after hormone withdrawal, a single injection of diethylstilbestrol induces transcription of ovalbumin structural and intervening sequences, with nuclear accumulation of high-molecular-weight ovalbumin RNA and mature ovalbumin mRNA; and (iv) these results are consistent with regulation of ovalbumin mRNA at the level of ovalbumin gene transcription.
TL;DR: The cloned chromosomal rabbit beta-globin gene has been introduced into mouse fibroblasts by DNA-mediated gene transfer (transformation) and transcripts reflect correct processing of the two intervening sequences but lack 48 +/- 5 nucleotides present at the 5' terminus of rabbit erythrocyte globin mRNA.
Abstract: The cloned chromosomal rabbit beta-globin gene has been introduced into mouse fibroblasts by DNA-mediated gene transfer (transformation). In this report, we examine the expression of the rabbit gene in six independent transformants that contain from 1 to 20 copies of the cloned globin gene. Rabbit globin transcripts were detected in two of these transformants at steady-state concentrations of 5 and 2 copies per cell. The globin transcripts from one cell line are polyadenylylated and migrate as 9S RNA on methylmercury gels. These transcripts reflect correct processing of the two intervening sequences but lack 48 +/- 5 nucleotides present at the 5' terminus of rabbit erythrocyte globin mRNA.
TL;DR: It is proposed that collision of RNA polymerase molecules moving in opposing directions can terminate transcription and this may result in a complete block in gene expression or it may merely reduce and delay expression.
TL;DR: The chapter describes a method, utilizing a combination of restriction endonuclease cleavage and digestion with Escherichia coli exonuclelease III (Exo III) and S1 nuclease, which allows to position a restriction fragment bearing the promoter of the lac Z gene of E. coli at virtually any distance in front of any cloned gene.
Abstract: Publisher Summary This chapter discusses a method for maximizing gene expression on a plasmid using recombination in vitro The amount of a gene product produced in transformed cells by plasmids carrying a given gene promoter fusion is dependent on the separation between the promoter and the gene The chapter describes a method, utilizing a combination of restriction endonuclease cleavage and digestion with Escherichia coli ( E coli ) exonuclease III (Exo III) and S1 nuclease, which allows to position a restriction fragment bearing the promoter of the lac Z gene of E coli and the region coding for the SD sequence of the lac Z gene at virtually any distance in front of any cloned gene This technique has been used to produce E coli strains, which can provide up to 200,000 monomers of cro protein per transformed cell It is useful in constructing plasmids that direct the production of large amounts of various E coli proteins and proteins from other prokaryotic and even eukaryotic cells
TL;DR: Evidence is presented to show that a more heterogeneous group of very small poly(A)-containing RNAs characterizes the last part of oogenesis, stages 13 and 14, and it is proposed that they represent mRNAs for chorion proteins.
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TL;DR: A remarkably simple genetic system for study of DNA multiplication and gene expression in plants is provided by DNA plant viruses, which have only a half-dozen or so genes that are believed to be regulated in the same way as other plant genes.
Abstract: Not available – first paragraph follows:
A remarkably simple genetic system for study of DNA multiplication and gene expression in plants is provided by DNA plant viruses. These viruses have only a half-dozen or so genes that are believed to be regulated in the same way as other plant genes. The DNA replicates in nuclei and may be associated with nuclear proteins (histones) in the same way as plant genetic material. Thus, the virus provides a small-scale, readily manipulated model for gene expression.
TL;DR: The advent of new techniques for genetic manipulation of eukaryotic cells and for isolation of large amounts of specific DNA sequences should now permit detailed analyses of steroid hormone action in this system.
TL;DR: Results indicate that synthesis of flagellar tubulin is a direct reflection of the abundance of its mRNA, and provide the molecular techniques for dissection of the factors that regulate the rapid appearance of this structural protein during differentiation.
TL;DR: This study demonstrates that this poly(A)+ RNA is an mRNA sequence by translating the RNA complementary to pDd 812 in a heterologous system and indicates that, at least in part, the control of the synthesis of this RNA is at the level of gene transcription.
TL;DR: A clone of recombinant virus obtained from the cross between WSN and Hong Kong strains of influenza virus gave rise to progeny containing predominantly von Magnus particles, and it was concluded that the extra RNA was derived from the P3 gene probably by deletion.
Abstract: A clone of recombinant virus obtained from the cross between WSN and Hong Kong strains of influenza virus gave rise to progeny containing predominantly von Magnus particles. In the electropherogram of virus RNA, the P3 gene was markedly diminished, and a new species of RNA (extra RNA) was present in addition to eight gene segments. The origin of the extra RNA was studied by two-dimensional gel electrophoresis of T1 RNase-generated oligonucleotides. Four out of five large oligonucleotide spots present in the extra RNA matched to those contained by the P3 gene. It was concluded that the extra RNA was derived from the P3 gene probably by deletion. The possible origin of the spot which was present in the extra RNA but not in eight gene segments including P3 was discussed.
TL;DR: Evidence for premature chain termination during transcription of an animal virus genome is reported, a key regulatory event for the synthesis of enzymes that make amino acids in bacteria.
Abstract: INITIATION of transcription, the first event in gene expression, is probably the most critical possible site for gene regulation. However, it has become clear from recent studies with bacteria and bacteriophages that a transcriptional start does not ensure the expression of a gene. For example, the phenomenon of ‘attenuation’, that is, premature termination of an mRNA chain before transcription of the structural gene region, is a key regulatory event for the synthesis of enzymes that make amino acids in bacteria1–4. We report here evidence for premature chain termination during transcription of an animal virus genome.
TL;DR: It is suggested that M-MuLV-specific gene expression is not sufficient for leukemic transformation and is related to virus-specific DNA amplification in preleukemic animals.
TL;DR: Comparison of in vitro translation products of RNAs isolated from embryonic and adult pancreases suggested that the developing exocrine pancreas undergoes at least two differentiative tran- tion events, and the rate of amylase synthe- sis during this developmental period is controlled in large part by the rateof accumulation of amelase mRNA.
TL;DR: The results suggest that the amount of variegating gene expression is a function of histone gene multiplicity, and the effect of a reduction in the number of genes coding for histone protein on the degree of mosaicism observed in two variegated gene systems is investigated.
Abstract: Position–effect variegation, originally observed in insects, has since been demonstrated in plants and mammals. When cells bear a chromosomal rearrangement which juxtaposes a euchromatic gene near to heterochromatin, a fraction of the cells exhibit no expression of that gene. The resultant organism is a mosaic for activity of the rearranged gene. The degree of mosaicism can be modified; such factors as elevated developmental temperature, additional Y chromosome heterochromatin in the genome, and various modifier genes enhance the proportion of cells in which the gene is active1. Although the phenomenon has been extensively documented, the underlying molecular mechanism of position–effect variegation remains unclear. The proportion of cells exhibiting gene inactivation increases with greater proximity of the rearranged gene locus to heterochromatin. It has been proposed that the variegating gene is inactivated by a ‘spreading effect’, or limited spatial diffusion of molecules from the adjacent heterochromatin2. This explanation supposes that the juxtaposed gene locus is condensed into a transcriptionally inactive state, possibly by a phosphorylated histone protein subspecies characteristic of Drosophila heterochromatin3. Such a model leads to the prediction that an alteration in the amount of cellular histone protein would affect the expression of variegating genes. To test this prediction, we have investigated the effect of a reduction in the number of genes coding for histone protein on the degree of mosaicism observed in two variegating gene systems. Our results suggest that the amount of variegating gene expression is a function of histone gene multiplicity.