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Biomedical subjects

F Gros

Publications and source records attributed to F Gros.

At least 163 records · Page 9Linked to original sources
PubMed1980

Identification of rat brain polysomes synthesizing the brain specific enolase (14.3.2 protein), S100 protein and alpha and beta tubulin subunits.

Polysomes prepared from frozen rat brain powder were fractionated by centrifugation in a sucrose gradient. Individual fractions were used to program a reticulocyte lysate in a run-off reaction. The products of cell-free synthesis were assayed for the brain-specific enolase (14.3.2 protein) and S100 protein by immunoprecipitation with specific antisera and for tubulin by two-dimensional electrophoresis in polyacrylamide slab gels. The relative synthesis of these proteins by unfractionated free brain polysomes were 0.1 per cent, 0.05 per cent and 0.7 per cent respectively. After centrifugation in a sucrose gradient polysomes synthesizing S100 protein were separated from those synthesizing the other two markers. There was a threefold enrichment in the specific messenger RNA activity for each of the three proteins studied in their respective peak fractions of polysomes.

Animals↗
PubMed1980

Partial purification of the alpha-tubulin and beta-tubulin messenger RNAs from rat brain.

Poly(A)-containing RNA from frozen adult rat brain were fractionated by centrifugation in a formamide/sucrose gradient. Individual fractions were used to program protein synthesis in vitro in a reticulocyte lysate. The cell-free translation products were analyzed by two-dimensional electrophoresis in polyacrylamide slab gels. We observed a heterodispersion of the mRNA translation activity coding for the beta-tubulin subunit which contrasts with a relatively homogeneous distribution of the alpha-tubulin subunit mRNA. These last mRNA species are present in a peak which sediments near the 18-S region of the gradient whereas the beta-tubulin mRNA activity is predominant in the fractions corresponding to the heaviest mRNA species. When these heaviest RNAs were separated again by centrifugation in a second formamide/sucrose gradient, a poly(A)-rich RNA population was obtained that was enriched in RNA for programming the beta-tubulin subunit. Analysis of the products whose synthesis in vitro was directed by this mRNA population revealed that beta tubulin was the main protein formed, the ratio beta/alpha being more than tenfold greater than in the products translated in vitro using total poly(A)-rich RNA.

Animals↗
PubMed1979

Function of individual E. coli 30 S ribosomal proteins as determined by in situ immunospecific neutralization: a tentative classification.

The accessibility of each 30S subunit protein to their cognate antibodies (IgG or Fabs) having been previously well established, the effect of their in situ specific neutralization by monovalent IgG fragments (FabI) are reported for five reactions: 1) T4 and R17 RNA directed protein synthesis: 2) polyphenylalanine synthesis: 3) enzymatic Phe-tRNA binding in the presence of 30S + 50W subunits: 4) fMet-tRNAf binding to the 30S subunit in the presence of initiation factors IF1, IF2, IF3; 5) coupling with lambda plac DNA transcription of the initial translation step (i.e., interaction of IF3 activated 30S subunits with nascent mRNA, in the absence of tRNA). According to evident similarities in their inhibition pattern concerning the five reactions tested, 30S subunit proteins can be classified in five categories which are discussed in terms of functional topography.

Bacterial Proteins↗
PubMed1979

Contractile protein isozymes in muscle development: identification of an embryonic form of myosin heavy chain.

The nature of the myosin heavy chain in embryonic muscle tissue, cultured muscle cells, and several adult muscles was investigated. After denaturation with sodium dodecyl sulfate, purified rat myosins were subjected to partial proteolytic cleavage or immunological analysis using microcomplement fixation. Three types of myosin heavy chains could be demonstrated by both approaches. Whereas adult muscles contain fast- or slow-type myosin heavy chains, embryonic tissue and cultured muscle cells harbor a distinct embryonic form. The existence of this distinct form further characterizes the isozymic transitions of contractile proteins during muscle development.

Aging↗
PubMed1979

Comparison of non histone proteins selectively associated with nucleosomes with proteins released during limited DNase digestions.

Cultured mammary cells from GR mouse were used to analyse proteins associated with the mononucleosomes and released by a short micrococcal DNase treatment of nuclei. On metrizamide density gradients, mononucleosomes appear to be heterogeneous according to their content of associated non-histone proteins. Proteins associated with the denser fraction (1.22 - 1.24 g/ml) were analysed by two dimensional electrophoresis and compared to the proteins released by DNase I treatment. All the proteins associated with mononucleosomes were also released by DNase I treatment. It could then be assumed that these proteins are associated with the active part of the genome. Additional proteins were released by micrococcal DNase treatment of the nuclei. They could be involved in a higher order organization of chromatin.

Animals↗
PubMed1979

Expression of single copy DNA sequences in nuclear RNA from undifferentiated mouse embryonal carcinoma and differentiated muscle cell line.

Nuclear RNA from an undifferentiated mouse embryonal carcionma (EC) cell line and a differentiated muscle (Mt) cell line from similar origin has been analysed with respect to base sequence complexity and frequency distribution with different probes. With the single copy component of mouse genomic DNA it is shown that total EC nuclear RNA and Mt nuclear RNA have respectively base sequence complexities of 100 Kb and 140 Kb corresponding to 6% and 8% of one strand of DNA. It is shown by hybridization with a purified DNA component complementary to total nuclear RNA that nuclear poly A+RNA in both cell types has only one fifth of total nuclear RNA complexity (as has polysomal RNA), but still contains all poly A+RNA present in polysomal poly A+RNA. Polysomal poly A+ sequences in total and poly A+ nuclear RNA are present in a restricted range of frequency distribution in contrast to the situation observed at the polysomal level. The implication of these results in terms of transcriptional and post-transcriptional control is discussed.

Animals↗
PubMed1979

Biochemical aspects of muscle differentiation as analyzed by in vitro cultivation techniques.

Myoblasts cultivated in vitro will undergo terminal differentiation to form muscle fibres. Teratoma derived mouse cell lines, a pluripotent primitive line, and a muscle cell line, provide a possibility for comparing RNA populations in an early precursor cell with those in committed myoblasts and differentiated myotubes. Molecular hybridization analyses led to the conclusion that new RNA sequences appear in the cytoplasm during muscle differentiation. Such muscle specific sequences are not detectable in the nuclear RNA of myoblasts or primitive cells. Studies of protein synthesis during terminal myogenesis indicate co-ordinate expression of the muscle contractile proteins. These represent distinct isozymes, distinguishable from the contractile proteins of other cell types. In the case of myosin light chains isozymic transitions between different muscle forms have been identified during early development.

Animals↗
PubMed1978

The majority of calf muscle cell messenger RNAs contain poly(A).

Previous studies from our laboratory have investigated messenger RNA metabolism in calf muscle cells in tissue culture. The analysis of mRNA was based on its poly(A) content. We have now examined directly the proportion of mRNA which contains poly(A) in these cells. After separation of poly(A)+ -and poly(A) - -RNA on oligo(dT) -cellulos, the two fractions were translated in a reconstituted, heterologous cell-free protein-synthesizing system and the products were compared with those from the translation of total RNA. The great majority of mRNA form either prefusion or postfusion cultures was poly(A)- containing; quantitative determinations show that about 70-90% of the actin mRNA is poly(A)-containing. In order to determine if a large fraction of the calf muscle mRNA can be translated by a heterologous cell-free system, [3H]-POLY(A)+ -RNA was added to reticulocyte lysates and the formation of initiation complexes was followed. These experiments suggest that the bulk of calf muscle cell mRNA would be utilized in such a system and justify the use of cell-free systems to examine the poly(A) content of total mRNA. Thus, differential polyadenylation does not seem to be an important aspect of mRNA metabolism in cultured muscle cells. The previous study of mRNA in these cells, based on poly(A) content, is apparently a valid measure of overall mRNA metabolism.

Cell Line↗
PubMed1978

Skeletal muscle acetylcholine receptor. Purification, characterization, and turnover in muscle cell cultures.

Acetylcholine receptor has been purified from embryonic skeletal muscle cells grown and allowed to differentiate in tissue culture. The polypeptide composition of purified receptor has been determined by two-dimensional electrophoresis. The purest preparations are composed of a single Mr = 41,000 class of polypeptide which exhibits some charge heterogeneity. By high resolution two-dimensional electrophoresis a spot corresponding to acetylcholine receptor was localized among total proteins of muscle membrane extracts. Synthesis of this component is shown to be developmentally regulated. Quantitative analysis of receptor synthesis and degradation has led to the conclusion that receptor is one of a class of proteins whose synthesis is tightly regulated during terminal steps of myogenesis.

Acetylcholine↗
PubMed1978

Complexity of nuclear and polysomal polyadenylated RNA in a pluripotent embryonal carcinoma cell line.

The base-sequence complexities and relative abundance of polysomal and nuclear polyadenylated [poly(A+)] RNA sequences have been analyzed in a pluripotent embryonal carcinoma cell line. Polysomal RNA and nuclear poly(A+) RNA have a complexity representing respectively 0.5% and 2.5% of the single copy component of haploid mouse DNA (1.8 X 10(6) K base pairs). By hybridization with specific cDNAs, three abundance classes were found in polysomal poly(A+) RNA, representing respectively 31%, 33%, and 36% of the RNA, with base sequence complexities of 0.1 X 10(3), 0.9 X 10(3), and 14.5 X 10(3) kilobases. This corresponds to 7000-8000 different mRNA species of an average length of 2000 nucleotides, present on an average of 5 to 600 copies per cell. In nuclear RNA, a major class of abundance was found with a complexity of 100 X 10(3) kilobases, each sequence being present in 1 copy per nucleus. The majority of the polysomal poly(A+) RNA sequences are represented in the nuclear poly(A+) RNA but are present in a more restricted range of relative abundance implying posttranscriptional mechanisms of quantitative modulation: polysomal RNA sequences appear to be preferentially transcribed into nuclear cDNA suggesting a preferential location of these sequences close to poly(A) sequences. The presence of a specialized gene product, globin specific RNA, could not be detected either in the nuclear or polysomal compartments of embryonal carcinoma cells, even at levels that would have detected one sequence per 50 cells.

Base Sequence↗