Search PubMed⌕ Search

Biomedical subjects

F Gros

Publications and source records attributed to F Gros.

At least 199 records · Page 11Linked to original sources
PubMed1976

Changes in the sedimentation properties of acetycholinesterase during neuroblastoma differentiation.

The adrenergic mouse neuroblastoma clone NIE 115 contains two species of AChE which sediment at 4S and 11S. These two species are found both in logarithmic growing phase cells (round neuroblast morphology) and in cells which have undergone morphological differentiation due to the elimination of serum. The 4S form is predominant in the growing cells (70 per cent) whereas the 11S form is more abundant (55 per cent to 65 per cent) in the cells with neurites. When protein synthesis is inhibited by cycloheximide, there is an increase states : we postulate that the 11S species is formed by a conversion of the 4S species. When cell division is blocked by sodium butyrate, there is an increase in AChE activity but no modification in the proportion of 4S/11S species as compared to the cells in growing phase. We were unable to associate temporally the increase in the 11S species with neurite outgrowth ; when cells were allowed to retract their neurites and were subsequently maintained in a GROWING state for 10 to 15 days, the 11s species still predominates. Although the presence of the 11S molecule cannot always be correlated with the state of morphological differentiation, the shift in sedimentation coefficient of AChE form 4S to 11S might eventually constitute a reference in the study of biochemical events leading to terminal differentiation in this system.

Acetylcholinesterase↗
PubMed1976

Protein synthesis and actin heterogeneity in calf muscle cells in culture.

Pulse-labeled cytoplasmic proteins from cultured fetal calf-muscle cells at various stages of development were analyzed by one- and two-dimensional gel electrophoresis. The high resolution of the two-dimensional technique allows the determination of those protein species that begin to be synthesized after cell fusion. In addition, actin has been found to exist in three forms possessing similar biochemical properties and identical molecular weights but having slightly different isoelectric points. Two of the forms are found in prefusion dividing myoblasts and also in cultured kidney cells. The third form is the only one found in fetal muscle tissue and is predominant in cultures of fused muscle cells. Thus, it would seem that actin can exist in several isozymic forms of which one is specific to fused muscle tissue.

Actins↗
PubMed1975

Effect of a low-molecular-weight DNA binding protein, H1 factor, on the in vitro transcription of the lactose operon in Escherichia coli.

H1 protein, a heat-stable low-molecular-weight DNA-binding factor previously described by Cukier-Kahn et al. [Proc. Nat. Acad. Sci USA (1972) 69, 3643-3647] markedly stimulates in vitro synthesis of lac-specific RNA directed by bacteriophage lambdah80 dlac or phi80 dlac DNA templates in the presence of purified E. coli RNA polymerase holoenzyme. The extent of stimulation obtained by addition of H1 alone is usually greater than that observed with the cAMP receptor protein-cAMP combination. H1 effect varies quite appreciably (from 4- to 16-fold) with the functional state of the promoter, being much larger with lambdah80 dlac p-s, a transducing DNA carrying a superpromoter mutation, than with lambdah80 dlac p+. H1 and cAMP receptor protein effects are nearly additive, although interpretation of the data obtained at high H1 concentration is complicated by the appearance of some inhibitory property. While the cAMP-receptor-protein-mediated synthesis is asymmetrical ("I" strand almost exclusively copied), the degree of asymmetry observed with H1 is less pronounced, suggesting asymmetrical copying from the lac promoter and symmetric transcription from other regions of the DNA. Synthesis of lac-specific RNA from lambdah80 dtrp/lac or phi80 dlac p-r uv5 templates, in which lac promoters are insensitive to cAMP receptor protein, either as a result of lac fusion to the trp operon or mutation in the lac promoter, is totally H1-insensitive. Glycerol (10-15% w/w) can fully substitute for H1 in stimulating lac RNA synthesis in a fashion analogous to that reported for the cAMP receptor protein-cAMP system. The possibility that H1 acts by causing conformational modifications at the promoter level in a way that increases its functional state, and that this effect is more pronounced with operons sensitive to cAMP receptor protein, is discussed.

Bacterial Proteins↗
PubMed1975

Synthesis of acetylcholine receptor during differentiation of cultured embryonic muscle cells.

Acetylcholine receptor, a component of the specialized muscle membrane, appears during the differentiation of embryonic myogenic cells in tissue culture. Demonstration of incorporation of the radioactive precursor L-[35S]methionine into purified receptor polypeptides is presented as evidence for its synthesis de novo. The identity of the purified radioactive species is established by cosedimentation of the [35S]receptor with [3H]alpha-toxin binding activity on sucrose gradients and by crossreaction with antiserum to purified acetylcholine receptor of Electrophorus electricus.

Acetylcholine↗
PubMed1975

Characterization of a novel, low-molecular-weight DNA-binding protein from Escherichia coli.

A low-molecular-weight (7000), heat-stable protein--HU--that stimulates transcription of bacteriophage lambda DNA by E. coli RNA polymerase was purified from E. coli extracts using affinity chromatography on DNA-cellulose. HU binds to native DNA, resulting in an apparent thickening of the DNA chains as revealed by electron microscopy. Contrary to DNA unwinding proteins, it causes no destabilization of the double helix. HU differs from previously described transcription factors (H1, D, etc.) and from the low-molecular-weight omega subunit of the RNA polymerase. By its amino-acid composition and characteristics, HU displays an interesting resemblance to some eukaryotic histones, such as H2B and H1.

Amino Acids↗
PubMed1975

[Jaw block at maximal mouth aperture in subcondylar fractures in the very young child].

In one case involving post-traumatic temporo-mandibular ankylosis, the authors suggest a means of bi-maxillary blockage at the maximum buccal aperture which they consider prevents this type of complication in very young children presenting with bicondylar fracture. The simplicity of this method, the possibility of carrying it out where the milk teeth are not yet complete, the fact that it is well-tolerated by the children it has been tried out on, make this, in their opinion, the procedure of choice.

Ankylosis↗
PubMed1974

Function of individual 30S subunit proteins of Escherichia coli. Effect of specific immunoglobulin fragments (Fab) on activities of ribosomal decoding sites.

Specific anti-30S protein immunoglobulin G fragments (Fab) were used to determine the contribution of each of the 30S ribosomal proteins to: (1) polyphenylalanine synthesis, (2) initiation factor-dependent binding of fMet-tRNA, (3) T-factor-dependent binding of phenylalanyl-tRNA, and (4) fixation of radioactive dihydrostreptomycin. Twenty of the 21 possible antibodies (antibody against S17 excepted) were used. In conditions where all the 30S proteins were accessible to Fabs, all of these monovalent antibodies strongly inhibited polyphenylalanine synthesis in vitro. Antibodies against S4, S6, S7, S12, S15, and S16, however, showed a weaker effect.30S proteins can be classified into four categories by their contributions to the function of sites "A" and "P": class I appears nonessential for tRNA positioning at either site (S4, S7, S15, and S16); class II includes proteins whose role in initiation is critical (S2, S5, S6, S12, and S13); class III (S8, S9, S11, and S18) corresponds to proteins whose blockade prevents internal (elongation factor Tudependent) positioning; and class IV includes entities that are essential for activities of both "A" and "P" sites (S1, S3, S10, S14, S19, S20, and S21). Dihydrostreptomycin fixation to the 30S or 70S ribosomes was inhibited by antibodies against S1, S10, S11, S18, S19, S20, and S21, but only weakly by the anti-S12 (Str A protein) Fab. The significance of these results is discussed in relation to 30S protein function, heterogeneity, and topography.

Antigen-Antibody Reactions↗
PubMed1974

The synthesis and stability of cytoplasmic messenger RNA during myoblast differentiation in culture.

The synthesis of poly(A)-containing cytoplasmic RNA was examined in primary myoblast cultures prepared from skeletal muscle of fetal calves. After a period of cell division, these cells undergo fusion, with concomitant appearance of acetylcholine receptor and subsequent myosin synthesis. In the dividing myoblast there is a high level of messenger RNA synthesis, including a 26S RNA, the size of a putative messenger for the large subunit of myosin. In the transition period prior to fusion, there are quantitative changes in RNA synthesis. At this time, there is a pronounced production of 26S RNA, which diminishes during fusion. The possibility that 26S RNA is accumulated in the dividing myoblast was investigated by chase experiments. At fusion, there is a marked increase in the half-lives of a number of messenger RNA species, including 26 S, which increases from about 10 hr in the dividing cell to a value of more than 50 hr. The identity of the more rapidly turning over 26 S in the myoblasts, compared to that of the 26 S at fusion, was examined in terms of polysomal distribution, migration on gels, and hybridization with complementary DNA for the myosin message. The results of these analyses suggest that the 26S species are identical. Thus, it would appear that in a predetermined cell like the myoblast, the transition to the differentiated state of myotube that is synthesizing muscle specific proteins is effected by the stabilization of messenger already being actively transcribed: terminal differentiation, with respect to myosin synthesis, is preceded by the stabilization of 26S RNA.

Adenine Nucleotides↗