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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pectoral muscle from normal and dystrophic New Hampshire chicken embryos was dissociated and grown in vitro. Marked differences between the two types of cell cultures were observed with the light and electron microscopes during early myogenic stages. The diseased myoblasts assumed a polarized affect and fused into smaller and fewer myotubes. Pseudostraps rather than true muscle straps were often seen in diseased cultures. There was also a delay in the appearance of myosin containing thick myofilaments in differentiating dystrophic muscle cells.
Virchows Arch B Cell Pathol Incl Mol Pathol 1979
PMID:Aspects of normal and dystrophic chicken muscle grown in vitro. 4 18

Direct selection for recombinants by supplemented minimal media from polyethylene-glycol (PEG)-induced fusion of protoplasts of polyauxotrophic strains of B. megaterium revealed striking physiological influences on the yield of recombinants. Cytoplasmic state of the protoplasts to be fused, rather than genetic events, determined the number of colonies obtained on the selection media. It is suggested that the physiological effects primarily influenced the ability of the fused protoplasts to revert to bacillary form.
Mol Gen Genet 1979 Jan 05
PMID:Polyethylene-glycol induced fusion of bacterial protoplasts: direct selection of recombinants. 10 89

Derivatives of the Escherichia coli drug resistance plasmid pMB-9 were constructed which contain the promoter from the lactose operon of E. coli fused to the araC gene of E. coli. E. coli possessing these plasmids contain about 50 times as much of the araC gene product as do cells with a wild-type araC gene and promotor.
Mol Gen Genet 1977 Dec 09
PMID:In vitro construction of plasmids which result in overproduction of the protein product of the araC gene of Escherichia coli. 34 Sep 31

A genetic and enzymological study was made of five spontaneous prototrophic revertants of a tryptophan auxotroph of Salmonella typhimurium which carries a deletion extending from the closely linked supX locus into the trp operator-promoter region. The revertants were found to have regained initiation of expression of all five trp genes. Recombinational tests showed that in each case the genetic change responsible for re-initiation is cotransducible with the trp-cysB region of the chromosome. Two different mechanisms leading to re-initiation of trp gene expression were established: (a) an extension of the limits of the original deletion resulting in the fusion of the trp structural genes with a nearby gene or gene set located outside the operator end of trp, and (b) translocation of a duplicate set of the trp structural genes to other chromosomal sites, located operator-distal to the normal trp operon, in such a manner that they are functionally fused to foreign genetic units. One revertant which arose by mechanism (a) was shown to have an extended deletion with one new terminus in trp and the other in the nearby cysB locus. All the revertants exhibit constitutive expression of the trp enzymes, with activities varying among strains from five to forty five times greater than the fully repressed wild type level. The protein product of trpA, the first structural gene of the operon, appears to have been partially damaged by the re-initiation event in at least two strains, while in the other strains, the enzyme appears in preliminary tests to be indistinguishable from that of wild type.
Mol Gen Genet 1978 Jan 17
PMID:Re-initiation of tryptophan operon expression in a promoter deletion strain of Salmonella typhimurium. 34 12

A fine structure analysis of the threonine operon in Escherichia coli K-12 was performed by deletion mapping. Lambda transducing bacteriophages carrying various parts of the threonine operon were isolated from strains in which the lacZ gene was fused to a thr gene. We tested for recombination between deletions of the threonine promotor extending into the threonine operon, carried by the phage, and bacterial thr auxotrophs. The relative order of thrO (operator) mutations was established. We propose that an operator region is located between a promoter region and the structural genes. Mutations leading to the desensitization of the aspartokinase I-homoserine dehydrogenase I towards threonine were localized in two different regions of the thrA gene.
Mol Gen Genet 1978 Jun 01
PMID:Fine structure analysis of the threonine operon in Escherichia coli K-12. 35 21

The glycogen content of cultured chick embryo breast muscle cells changes during their development and can be reduced by starvation. It is demonstrated that the rate of glucose incorporation into glycogen and the degree of interconversion of glycogen synthase are controlled by the actual glycogen content. Stimulation of both corresponding activities by insulin is found in fused and in unfused cells. The insulin response depends on the extracellular calcium concentration and can be mimicked by the ionophore A 23187. These metabolic effects as well as calcium efflux data confirm the hypothesis that insulin acts on its enzyme target via increased cytoplasmic calcium concentration. Cytochalasin B is shown to inhibit the interconversion but does not interfere with the insulin-induced increase of the mitochondrial calcium pool or with the acceleration of the calcium efflux out of 45C-preloaded myotubes.
Mol Cell Endocrinol 1977 Jul
PMID:Regulation of glycogen synthase interconversion in cultured muscle cells: actions of insulin, calcium, ionophore A 23187 and cytochalasin B. 40 13

Complementation tests were performed on 10 strains of Dictyostelium discoideum which carry developmental mutations representing aggregation loci identified previously in two independent studies. When the 5 aggregation-deficient strains representing loci CGI-5 were fused with the 5 strains carrying mutations at loci ago A-E, all 25 crosses produced aggregation-competent diploids. Complicating factors, such as negative gene interactions and possible interallelic complementation are discussed. The results of this experiment suggest that the 10 aggregation loci identified in the two studies are different and that aggregation loci in D. discoideum are probably not associated with significant mutational "hot-spots".
Mol Gen Genet 1977 Mar 16
PMID:Evidence against mutational "hot-spots" at aggregation loci in Dictyostelium discoideum. 55 42

Numerous recombinants arose when protoplasts of S. coelicolor were treated with polyethylene glycol and regenerated on non-selective solid medium. In six-factor crosses, recombination frequencies of more than 10% (up to 17%) were routinely observed. This recombination did not require either of the known sex factors, SCPI and SCP2. The proportion of multiple crossover classes was much higher than amongst recombinants produced by conjugated between mycelia. Analysis of the spatial distribution of crossovers in double and quadruple crossover recombinants showed only a slight tendency for crossovers to occur closer together than randomly on the complete linkage group. This suggests that genomes brought together by protoplast fusion are complete, or nearly so (in conjugation, in contrast, one genome is represented by a comparatively short fragment). Individual colonies arising from fused protoplasts did not contain different parental genomes without recombinants, but recombinants often occurred without parentals. Several recombinant genotypes often occurred in the same colony, showing a segregation of some, only, of the parental alleles. Complementary genotypes, parental or recombinant, did not occur in the same colony. It is postulated that complete genomes of fused protoplasts usually become fragmented and that crossing-over, often repeated, occurs between the fragments, to generate haploid recombinants. Analysis of fusions between propoplasts of four different genotypes indicated that the average number of protoplasts fusing together was low, but nevertheless appreciable numbers of fusions involved three or four genomes. Crossing-over between them produced recombinants inheriting markers from three or four parents. The generation of nearly random populations of recombinants between two or more parent strains by propoplast fusion under the conditions described appears to have simple applications in industrial and academic strain construction.
Mol Gen Genet 1978 Jul 04
PMID:Bacterial protoplast fusion: recombination in fused protoplasts of Streptomyces coelicolor. 68 71

The trp genes of a lambda imm434 trp-transducing phage have been fused to the immunity region by deletion, in vitro, of the DNA between two targets for the restriction enzyme R.EcoRI. The resulting phage has been used to study the control of expression of the cI gene in vivo. The constitutive rate of expression of the cI gene is between 2 and 5% of the maximally stimulated rate. The products of the cII and cIII genes enhance expression of cI on infection of a sensitive host. The requirement for the cII product is more stringent than that for the cIII protein. The phage 434 repressor present in a 434-immune cell stimulates the rate of cI expression from a superinfecting homoimmune phage about fifteen-fold. This result strongly suggests that repressor stimulates its own synthesis by a direct effect on transcription of the cI gene.
Mol Gen Genet 1976 Jul 23
PMID:Control of cI gene expression in bacteriophage lambda imm434, studied in an immunity/trp fusion made in vitro. 78 19

A fused F prime factor was obtained from a mating of a recA donor carrying an F'- factor containing the genes metBJF, ppc and argECBH (KLF5) with a recA recipient carrying an F' factor containing att80, trp and lac (f155). lysogenization of this fused F-prime factor with gammacI857hphi80 phage followed by thermoinduction produced the transducing phages phi80 dmetBJF and phi80 dppcargECBH. This kind of fusion provides a general procedure for the construction of transducing phages carrying genes from different regions of the E. coli genome. To understand the mechanism of this fusion, the parental F prime factors (F155 and KLF5) were analyzed by the electron microscope heteroduplex technique. F155 has a length of 176 +/- 3 kilobases including two substitutions. The F sequence 0 F-2.8 F has been substituted by 53 kb of chromosomal DNA including the lac operon and the F sequences 8.5 F-16.3 F has been substituted by 27 kb of a chromosome sequence including att80 and the trp operon KLF5 contains 221 +/- 4 kilobases of DNA (molecular weight, 148 megadaltons). It contains complete F and the segment of the E. coli chromosome from polA to rif. The F sequence 2.8 F-8.5 F known to be involved in F specific recombination in recA+ and recA backgrounds occurs twice on KLF5, once at each of the junctions of F DNA with chromosomal DNA. The population of closed circular plasmid molecules extracted from KLF5-containing strains is heterogeneous. It is proposed that this heterogeneity is due to intramolecular recombination events occurring in KLF5 between the duplicated 2.8 F-8.5 F sequences. Such recombination can account for the genetic instability of KLF5 observed in both recA+ and recA hosts. The F sequence 2.8 F-8.5 (also called gammadelta) is one of the characterized integration sequences on F. A model for the fusion of the parental F prime factors is proposed in which recombination between gammadelta sequences brings att80 close to the metBJF genes. This is followed by a deletion of an F' lac factor. The resulting fused F' factor still carries two gammadelta sequences and is therefore expected to be unstable. The closed circular molecules isolated from the fused F' containing strains show two different sizes of molecules. Genetic and physical analyses of these molecules are in agreement with the predicted instability of the fused F' factor and the existance of the gammadelta sequence in the phi80 dmet phages isolated from fused F' and previously analyzed by the electron microscope heteroduplex technique.
Mol Gen Genet 1976 Aug 02
PMID:Fusion of two F-prime factors in Escherichia coli studied by electron microscope heteroduplex analysis. 79 87


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