Showing papers on "Gene published in 1973"
TL;DR: Pulse-chase experiments in wild-type and mutant phage-infected cells provide evidence that the following particles called prohead I, II and III are successive precursors to the mature heads as discussed by the authors.
3,697 citations
TL;DR: The RNAs and proteins specified by five early genes of bacteriophage T7 have been identified by electrophoresis on sodium dodecyl sulfate, polyacrylamide gels using a slab gel system in which 25 samples can be run simultaneously and then dried for autoradiography.
2,127 citations
TL;DR: Marginotomy is responsible for the loss with age of various cell clones of the body, including some endocrine cell clones, and may be the primary cause of various disorders of age of the ageing of multicellular organisms.
1,802 citations
TL;DR: This report will demonstrate the existence of clonal segregation of developmental pathways in the wing (dorsal mesothoracic) disk of Drosophila and show that these cell lineages are fixed.
Abstract: MOSAICS generated by genetic methods or by technical operations have been used to investigate cell autonomous and non-autonomous developmental processes. The use of cell autonomous genetic markers allows us to label cells for analysis of morphogenetic processes and to follow cell lineages in development1–4. If it can be shown that these cell lineages are fixed, a genetic analysis of development can be focused on how genes control clonal processes. This report will demonstrate the existence of clonal segregation of developmental pathways in the wing (dorsal mesothoracic) disk of Drosophila.
767 citations
TL;DR: The gene products that are defined by the cdc cistrons are essential for the completion of the cell cycle in haploids of a and alpha mating type and in a/alpha diploid cells and the same genes control thecell cycle in each of these stages of the life cycle.
Abstract: One hundred and forty-eight temperature-sensitive cell division cycle (cdc) mutants of Saccharomyces cerevisiae have been isolated and characterized. Complementation studies ordered these recessive mutations into 32 groups and tetrad analysis revealed that each of these groups defines a single nuclear gene. Fourteen of these genes have been located on the yeast genetic map. Functionally related cistrons are not tightly clustered.Mutations in different cistrons frequently produce different cellular and nuclear morphologies in the mutant cells following incubation at the restrictive temperature, but all the mutations in the same cistron produce essentially the same morphology. The products of these genes appear, therefore, each to function individually in a discrete step of the cell cycle and they define collectively a large number of different steps.The mutants were examined by time-lapse photomicroscopy to determine the number of cell cycles completed at the restrictive temperature before arrest. For most mutants, cells early in the cell cycle at the time of the temperature shift (before the execution point) arrest in the first cell cycle while those later in the cycle (after the execution point) arrest in the second cell cycle. Execution points for allelic mutations that exhibit first or second cycle arrest are rather similar and appear to be cistron-specific. Other mutants traverse several cycles before arrest, and its suggested that the latter type of response may reveal gene products that are temperature-sensitive for synthesis, whereas the former may be temperature-sensitive for function.The gene products that are defined by the cdc cistrons are essential for the completion of the cell cycle in haploids of a and alpha mating type and in a/alpha diploid cells. The same genes, therefore, control the cell cycle in each of these stages of the life cycle.
710 citations
TL;DR: It is suggested that all cells possess multiple structural genes capable of coding for transforming factors which can release the cell from its normal constraints on growth.
Abstract: A general hypothesis of carcinogenesis is proposed consisting of the following features: (1) It is suggested that all cells possess multiple structural genes (Tr) capable of coding for transforming factors which can release the cell from its normal constraints on growth. (2) In adult cells they are suppressed by diploid pairs of regulatory genes and some of the transforming genes are tissue specific. (3) The Tr loci are temporarily activated at some stage of embryogenesis and possibly during some stage of the cell cycle in adult cells. (4) Spontaneous tumors, or tumors induced by chemicals or radiation, arise as the result of a double mutation of any set of regulatory genes releasing the suppression of the corresponding Tr genes and leading to transformation of the cell. (5) Autosomal dominant hereditary tumors, such as retinoblastoma, are the result of germ-line inheritance of one inactive regulatory gene. Subsequent somatic mutation of the other regulatory gene leads to tumor formation. (6) The Philadelphia chromosome produces inactivation of one regulatory gene by position effect. A somatic mutation of the other leads to chronic myelogenous leukemia. (7) Oncogenic viruses evolved by the extraction of host Tr genes with their conversion to viral transforming genes. As a result, in addition to the above mechanisms, tumors may also be produced by the reintroduction of these genes into susceptible host cells.
450 citations
TL;DR: Recent experimental information in areas of animal cell molecular biology which are relevant to the mechanism of gene regulation are concerned, with particular reference to the frequency of structural gene sequences, mRNA turnover, and the interpretation of dipteran complementation groups.
Abstract: This review concern recent experimental information areas of animal cell molecular biology which are relevant to the mechanism of gene regulation. New data regarding interspersion and clustering of repetitive sequence elements in DNA are considered Molecular characteristics of
animal structural genes and mRNAs are discussed, with particular reference the frequency of structural gene sequences, mRNA turn over and the interpretation of dipteran complementation groups. The molecular characteristics of nuclear RNAs, the primary transcription products, are reviewed. Evidence for transcription level regulation is summarized and the relation of nuclear
and mRNA examined. The protein activator branch of the Britten-Davidson model for gene regulation is further developed and considered in light of current knowledge.
408 citations
TL;DR: It was found that approximately 44% of the F factor is homologous to several different fi+ R factors and to Col V-K94, and that all of the homology between these plasmids and F is restricted to a region comprising only one-half of theF-factor molecule.
331 citations
TL;DR: It is concluded that an intact prohead structure is required to mature the virus DNA (i.e. to cut the overlength DNA concatemer to the mature length) and apparently this cutting occurs as part of the encapsulation event.
284 citations
TL;DR: It is apparent from these findings that the gene(s) for indophenol oxidase (IPO-B) and the gene for the antiviral protein are syntenic and that they are linked to human chromosome G-21.
Abstract: 13 independent mouse-human somatic cell hybrid clones derived from β-propiolactone-inactivated Sendai stimulated cell fusion of human cells with mouse cells were tested for their sensitivities to human and mouse interferon. All of them were protected by mouse interferon and only six of the clones were protected by both human and mouse interferon. Only the six that were protected by human interferon were shown to express the human dimeric form of indophenol oxidase. Complete chromosomal analysis of the clones indicated human chromosome G-21 to be the only human chromosome in common for the six clones which had both phenotypes present. Nine subclones were derived from one of the clones expressing both phenotypes. Eight of the nine subclones were shown to retain both phenotypes, whereas one subclone lost both. Chromosomal analysis of the subclones indicated the loss of chromosome G-21 from the subclone which lost both phenotypes. It is apparent from these findings that the gene(s) for indophenol oxidase (IPO-B) and the gene(s) for the antiviral protein are syntenic and that they are linked to human chromosome G-21.
277 citations
TL;DR: Since both repressible acid and alkaline phosphatases were affected simultaneously in the phoR, phoD, and phoS mutants, it was concluded that these enzymes were under the same regulatory mechanism or that they shared a common polypeptide.
Abstract: Saccharomyces cerevisiae strain H-42 seems to have two kinds of acid phosphatase: one which is constitutive and one which is repressible by inorganic phosphate. The constitutive enzyme was significantly unstable to heat inactivation, and its Km of 9.1 × 10−4m for p-nitrophenylphosphate was higher than that of the repressible enzyme (2.4 × 10−4m). The constitutive and the repressible acid phosphatases are specified by the phoC gene and by the phoB, phoD, or phoE gene, respectively. Results of tetrad analysis suggested that the phoC and phoE genes are linked to the lys2 locus on chromosome II. Since both repressible acid and alkaline phosphatases were affected simultaneously in the phoR, phoD, and phoS mutants, it was concluded that these enzymes were under the same regulatory mechanism or that they shared a common polypeptide. The phoR mutant produced acid phosphatase constitutively, and the phoR mutant allele was recessive to its wild-type counterpart. The phoS mutant showed a phenotype similar to that of a mutant defective in one of the phoB, phoD, or phoE genes. However, the results of genetic analysis of the phoS mutant clearly indicated that the phoS gene is not a structural gene for either of the repressible acid and alkaline phosphatases, but is a kind of regulatory gene. According to the proposed model, the phoS gene controls the expression of the phoR gene, and inorganic phosphate would act primarily as an inducer for the formation of the phoR product which represses phosphatase synthesis.
TL;DR: Present knowledge about the structure and function of mt DNA and its transcription products is briefly discussed with special emphasis on the unusual structure of mtDNA in Tetrahymena pyriformis and recent experiments on the possible import of mRNA into mitochondria.
TL;DR: A self-consistent map could be constructed which related specific regions of the SV40 genome to the induction of specific antigens in the nondefective Ad2-SV40 hybrids.
Abstract: A series of viable recombinants between adenovirus 2 (Ad2) and simian virus 40 (SV40) (nondefective Ad2-SV40 hybrids) have been isolated. The members of this series (designated Ad2 + ND 1 through Ad2 + ND 5 ) differ from one another in the early SV40-specific antigens and the SV40-specific RNA species which they induce in infected cells. They also contain different amounts of SV40 DNA as shown by RNA-DNA hybridization techniques. We have examined the structure of the DNA molecules from these hybrids, using electron microscope heteroduplex mapping techniques. Each hybrid was found to contain a single segment of SV40 DNA of characteristic size covalently inserted at a unique location in the adenovirus 2 DNA molecule. The SV40 segments of the various hybrids formed an overlapping series with a common end point. When the results of the electron microscopic study were combined with data on antigen induction, it was found that a self-consistent map could be constructed which related specific regions of the SV40 genome to the induction of specific antigens. The order of these early SV40 antigen inducing regions in the SV40 DNA segments contained in the nondefective hybrids is: U antigen, tumor specific transplantation antigen, and T antigen with the U antigen region being nearest the common end point. Images
TL;DR: To eliminate the large excess of adenovirus coat proteins, synthesised in human cells, which are known to bind to DNA, the authors used African green monkey cells as hosts and found that in these cells viral DNA synthesis occurs at a normal rate but late viral capsid proteins are not produced or are synthesisedin very small amounts.
Abstract: DURING productive infection of human cells with types 2 or 5 adenovirus a number of proteins specific for the infected cells, but not found in the intact virion, can be detected by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate (SDS)1, 2. None of these proteins, however, has been isolated in a native state and therefore their functions remain obscure. The observation that replicating adenovirus DNA contained extensive single stranded regions (refs 3, 4 and U. Petterson, personal communication) led us to look for proteins specific for infected cells that bind only to single stranded DNA and may be involved directly in DNA replication. Such a class of proteins, originally described by Alberts and Frey5, has now been found in a number of prokaryotic systems5–7 as well as in mammalian cells8, 9 and they are known, at least in the case of T4 gene 32 protein, to be required for DNA replication and genetic recombination5. To eliminate the large excess of adenovirus coat proteins, synthesised in human cells, which are known to bind to DNA10, we used African green monkey cells as hosts. In these cells viral DNA synthesis occurs at a normal rate but late viral capsid proteins are not produced or are synthesised in very small amounts11.
TL;DR: There appears to be a dichotomy both for genetic control of, and cell populations involved in, the recognitive and destructive phases of cell mediated immunity.
Abstract: The mixed leukocyte culture (MLC) and the cell mediated lympholysis (CML) assays are used as in vitro models of the afferent, or recognitive, and efferent, or destructive, phases of the homograft reaction. Activity in both of these tests has been related to differences at the major histocompatibility complex, HL-A in man and H-2 in mouse. Recent evidence suggests that the presumed cell surface differences which lead to cell proliferation in MLC are different from those which act as a target for CML. Data are presented providing further support for this hypothesis; in addition separate cell populations may respond to the differences which activate cells in MLC and to the differences which serve as targets for CML. There thus appears to be a dichotomy both for genetic control of, and cell populations involved in, the recognitive and destructive phases of cell mediated immunity.
TL;DR: An hypothesis is presented of a general mechanism for the formation and maintenance of metabolic diversity, and two gene linkage groups are shown for the reactions before and after isobutyrate.
Abstract: Earlier papers demonstrated an extensive genetic exchange among fluorescent Pseudomonads; this one documents for genes specifying enzymes of peripheral dissimilation an extrachromosomal array, segregation, and frequent interstrain transfer. An hypothesis is presented of a general mechanism for the formation and maintenance of metabolic diversity. The example used, the path of oxidative cleavage of the carbocyclic rings of the bicyclic monoterpene D- and L-camphor, terminates in acetate release and isobutyrate chain debranching. By transduction, two gene linkage groups are shown for the reactions before and after isobutyrate. The group for reactions before isobutyrate is plasmid borne, contransferable by conjugation, mitomycin curable, and shows a higher segregation rate from cells that are multiplasmid rather than carrying a single plasmid. The genes that code for isobutyrate and essential anaplerotic and amphibolic metabolism are chromosomal. By conjugation plasmid-borne genes are transferred at a higher frequency than are chromosomal, and are transferred in homologous crosses more frequently than between heterologous species. Most isobutyrate-positive fluorescent pseudomonad strains will accept and express the camphor plasmid.
TL;DR: Although the Tc6-5 plasmid is not self-transmissible, it can interact and/or recombine with conjugally-proficient plasmids that promote its transfer to other bacteria.
Abstract: Controlled shearing of R-factor DNA leads to formation of fragments carrying an antibiotic resistance gene present on, but not expressed by, the intact R-factor. Transformation of CaCl2-treated E. coli by such fragments yields an autonomously replicating tetracycline-resistance plasmid (Tc6-5) that contains only a small fraction of the genome of the parent R-factor, and lacks both its fertility functions and its other drug-resistance determinants. Although the Tc6-5 plasmid is not self-transmissible, it can interact and/or recombine with conjugally-proficient plasmids that promote its transfer to other bacteria.
TL;DR: Amphetamine exerted opposite effects in relation to those exerted by scopolamine on activity and its action was found to be determined by a polygenic system.
TL;DR: In situ hybridization of 5S RNA and cRNA transcribed in vitro from Xenopus laevis5S DNA shows that 5S DNA is localized at or near the telomere region of the long arm of many, if not all, of the X. laevIS chromosomes, which suggests that the uniformity of5S sequences on non-homologous chromosomes might be maintained by crossing-over between the chromosomes.
Abstract: In situ hybridization of 5S RNA and cRNA transcribed in vitro from Xenopus laevis 5S DNA shows that 5S DNA is localized at or near the telomere region of the long arm of many, if not all, of the X. laevis chromosomes. No 5S DNA is detected near the nucleolus organizer in the normal X. laevis chromosome complement, but in a X. laevis kidney cell line, 5S DNA is found at the distal end of the secondary constriction. The arrangement of 5S DNA in several types of interphase nuclei is described. — During the pairing stages of meiosis the telomeres of most or perhaps all of the chromosomes become closely associated so that the regions containing 5S DNA form a single cluster. This close association might be either a cause or a result of the presence of the similar sequences of 5S DNA on many telomeres. It suggests that the uniformity of 5S sequences on non-homologous chromosomes might be maintained by crossing-over between the chromosomes.
TL;DR: Through use of tetrad, random spore, trisomic, and mitotic analysis procedures a large number of genes, including 48 new genetic markers, were studied for their locations on the genetic maps of the yeast Saccharomyces cerevisiae, finding Functionally-related sets of genes generally were found to be dispersed over the genome.
Abstract: Through use of tetrad, random spore, trisomic, and mitotic analysis procedures a large number of genes, including 48 new genetic markers, were studied for their locations on the genetic maps of the yeast Saccharomyces cerevisiae. Eighteen new centromere linked genes were discovered and all but one was located on various ones of the 16 previously-established chromosomes. Five fragments of linked genes were also assigned to chromosomes; four were located on known chromosomes while the fifth determined one arm of a new chromosome. The experiments indicate that seventeen is likely to be the haploid chromosome number in this yeast. Most chromosomes have been established by genetic means to be metacentric and their genetic lengths vary from 5 cM to approximately 400 cM. Functionally-related sets of genes generally were found to be dispersed over the genome.
TL;DR: A family in which a translocation t(11; 21) (q23 ;q22) was segregating through three generations was studied clinically and cytogenetically.
Abstract: A family in which a translocation t(11; 21) (q23 ;q22) was segregating through three generations was studied clinically and cytogenetically. Individuals mono somic for the distal part of the long arm
TL;DR: The genes responsible for DNA adeninemethylation (dam) and DNA cytosine methylation (dcm) have been mapped on the E. coli K-12 genetic map and are recessive in F′ merodiploids.
Abstract: The genes responsible for DNA adenine methylation (dam) and DNA cytosine methylation (dcm) have been mapped on the E. coli K-12 genetic map. The dam gene is situated at min 65 and the gene order cysG-(trpS, dam)-aro B inferred. The dcm gene is located at min 37.5 and the gene order is supD-dcm-flaA1. In F′ merodiploids, the dam and dcm alleles are recessive.
TL;DR: The Fv-1 gene, which regulates sensitivity of mouse cells to infection by naturally occurring host-range types of murine leukemia virus, was shown to be located on linkage group VIII (chromosome 4), 39 map units from b.v. leukemia virus.
Abstract: The Fv-1 gene, which regulates sensitivity of mouse cells to infection by naturally occurring host-range types of murine leukemia virus, was shown to be located on linkage group VIII (chromosome 4), 39 map units from b.
TL;DR: Cytoplasmic «petite colonie mutants (ϱ − ) of S. cerevisiae possess mitochondria deficient in respiration, oxidative phosphorylation and protein synthesis that result from large deletions of the wild type mit.
TL;DR: It is suggested that the phoS and phoT genes are primarily involved in P(i) transport and, as a result of this function, play a role in the regulation of alkaline phosphatase synthesis.
Abstract: Two classes of alkaline phosphatase constitutive mutations which comprise the original phoS locus (genes phoS and phoT) on the Escherichia coli genome have been implicated in the regulation of alkaline phosphatase synthesis. When these mutations were introduced into a strain dependent on a single system, the pst system, for inorganic phosphate (Pi) transport, profound changes in Pi transport were observed. The phoT mutations led to a complete Pi− phenotype in this background, and no activity of the pst system could be detected. The introduction of the phoS mutations changed the specificity of the pst system so that arsenate became growth inhibitory. Changes in the phosphate source led to changes in the levels of constitutive alkaline phosphatase synthesis found in phoS and phoT mutants. When glucose-6-phosphate or l-α-glycerophosphate was supplied as the sole source of phosphate, phoT mutants showed a 3- to 15- fold reduction in constitutive alkaline phosphatase synthesis when compared to the maximal levels found in limiting Pi media. However, these levels were still 100 times greater than the basal level of alkaline phosphatase synthesized in wild-type strains under these conditions. The phoS mutants showed only a two- to threefold reduction when grown with organic phosphate sources. The properties of the phoT mutants selected on the basis of constitutive alkaline phosphatase synthesis were similar in many respects to those of pst mutants selected for resistance to growth inhibition caused by arsenate. It is suggested that the phoS and phoT genes are primarily involved in Pi transport and, as a result of this function, play a role in the regulation of alkaline phosphatase synthesis.
TL;DR: It is suggested that the gene(s) that conditions the capability for physiologic T-B cell cooperation must be shared in common by the respective cell types, and suggest, furthermore, that this gene (or genes) belongs to the major histocompatibility system of the mouse.
Abstract: In the present study we have asked the question of whether F1 carrier-primed T cells can serve as helper cells for either or both parental B cells when (a) the carrier molecule employed is under genetic control such that one parental strain is a responder and the other is a nonresponder, and (b) the determinant specificity of the parental B cells being assessed is not under genetic control and bears no relationship to the specificity of the carrier molecule. Utilizing the system of immune response gene control of responses to the terpolymer L-glutamic acid-L-lysine-L-tyrosine (GLT) to which A strain mice (H-2a) are nonresponders, whereas BALB/c (H-2d) and (BALB/c x A)F1 hybrids (CAF1) are responders, these studies demonstrate that GLT-primed T cells of CAF1 donors can provide for responder BALB/c, but not for nonresponder A/J, the required stimulus for the anti-DNP responses of DNP-specific B cells of these respective parental strains to the DNP conjugate of GLT. The implications of these findings for Ir gene function in physiologic T-B cell interactions are discussed in detail.
TL;DR: The results indicate that transcriptional controls are important in regulation of MMT virus gene expression and that hormonal and genetic factors may influence transcriptional control.
TL;DR: It is demonstrated that fusion between two immunoglobulin-secreting cell lines produces hybrid cells which secrete immunoglOBulin of both parental types.
Abstract: EACH immunoglobulin chain is the integrated expression of one of several V and C genes, coding respectively for their variable and constant sections1. The restricted expression of these genes leads to molecules of a single class and type with identical combining sites at both halves of the antibody molecule2–4. This symmetry is essential for the formation of the antigen-antibody lattice. Its importance is emphasized by allelic exclusion, whereby each cell expresses only one of two possible alleles4. To understand this problem further we have studied the expression of these genes in hybrid cells obtained by fusion of two cell lines producing different immunoglobulins. Successful fusion of this type has not yet been demonstrated but fusion between immunoglobulin-producing cells and non-immunoglobulin-producing cells has been reported. Thus myeloma cells have been fused to fibroblasts5–7 and also to a non-immunoglobulin-producing lymphoma line8. Substantial immunoglobulin production in the hybrids was observed only in the latter case. Here, we demonstrate that fusion between two immunoglobulin-secreting cell lines produces hybrid cells which secrete immunoglobulin of both parental types.
TL;DR: A heat-inducible lysis-defective lambda prophage has been integrated directly into the E. coli chromosome at a site very closely linked to the ribonucleic acid polymerase mutation rif(d), a dominant rifampin resistance allele.
Abstract: A heat-inducible lysis-defective lambda prophage has been integrated directly into the E. coli chromosome at a site (bfe) very closely linked to the ribonucleic acid polymerase mutation rif(d), a dominant rifampin resistance allele. This unusual lysogen has facilitated the isolation of specialized transducing phages conferring rifampin resistance to sensitive cells, and carrying at least the beta subunit gene of RNA polymerase in intact form.
TL;DR: The results are consistent with the idea that there exist at least two additional pathways for dark repair in yeast, one capable of repairing X-ray and MMS damage to DNA, and another, possibly analogous to post-replication repair in bacteria, that competes with the other two for damaged regions in DNA.
Abstract: In the simple eucaryote Saccharomyces cerevisiae there are at least three phenotypically distinct classes of mutants sensitive to inactivation by radiations and alkylating agents: class I mutants are sensitive to ultraviolet light and nitrogen mustard (HN2); class II mutants are sensitive to X-rays and methylmethane sulphonate (MMS); and class III mutants are sensitive to all four of these agents. We have constructed doubly mutant strains of types (I, I), (I, II), (I, III), and (II, III) and have measured their sensitivity to UV, X-rays, HN2 and MMS in order to characterize the interactions of the various mutant gene pairs. Class (I, III) double mutants proved to be supersensitive to UV and HN2 and class (II, III) double mutants proved to be supersensitive to X-rays and MMS. All other double mutants showed little or no enhancement of sensitivity over their most sensitive single mutant parents. Mutants of class I are known to be defective in excision repair and our results are consistent with the idea that there exist at least two additional pathways for dark repair in yeast, one capable of repairing X-ray and MMS damage to DNA, and another, possibly analogous to post-replication repair in bacteria, that competes with the other two for damaged regions in DNA.