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Biomedical subjects

F Gros

Publications and source records attributed to F Gros.

At least 145 records · Page 8Linked to original sources
PubMed1981

Muscle coding sequences and their regulation during myogenesis: cloning of muscle actin cDNA probes.

For a number of years our group has been mainly interested in the regulation of muscle gene expression during myogenesis. Using primary cultures and cell lines we have tried to find out whether the coding sequences for muscle proteins are already present in an unexpressed form or if there is a transcriptional switch at the onset of differentiation. Metabolic studies on pulse-labelled RNA, together with translation and molecular hybridization experiments have given a certain number of indications. More recently the development of genetic engineering techniques has made it possible to answer these questions directly with probes which are complementary to specific muscle coding sequences. We have identified a plasmid which contains a coding sequence for muscle actin. Other recombinant plasmids are being characterized. Such plasmids, used as probes, will permit us to study the organization and expression of the genes coding for the contractile proteins in muscle cells.

Actins↗
PubMed1981

In vitro inhibition of protein synthesis by dialysates of plasma from uraemic patients.

An in vitro technique was devised to test the effects on protein synthesis of plasma dialysate from control and uraemic subjects. Each plasma was dialysed for 24 h to extract the molecules having molecular weight less than 12,000 and the dialysate was lyophilized. Protein synthesis was studied in vitro, using a cell-free system form mouse Krebs II ascites cells. The cells were lysed, and the 30,000 g supernatant ("S-30 lysate") was used to test the protein-synthesizing activity of dialysates of control and uraemic plasma. The rate of protein synthesis was monitored by measuring the incorporation of [14C]leucine into tri-chloracetic acid-precipitable material in the presence of various amounts of plasma dialysate. The presence of normal plasma dialysate increased the [14C]leucine incorporation rate which went through a maximum for 20-22 microliters of added plasma dialysate. In contrast, in the presence of uraemic plasma dialysate, the incorporation rate of the radiolabel decreased as the amount of uraemic dialysate was raised. The ratio of incorporation in the presence of these two kinds of plasma dialysates significantly differed (P less than 0.01) in the range of 15-25 microliters of added plasma dialysate. Heating the uraemic plasma dialysate at 100 degrees C for 1 h prior to incubation almost restored the ratio of [14C]leucine incorporation to control values. Therefore it is concluded that: (1) uraemic plasma inhibits protein synthesis, (2) a significant part of this inhibitory effect is related to thermosensitive molecules, (3) the total inhibition appears to be the results of combined effects of ionic and organic compounds accumulated in uraemic plasma.

Adult↗
PubMed1981

Identification of transcription initiation sites for bacterial RNA polymerase and eukaryotic RNA polymerase B on the 5' end of the mouse beta-Globin gene.

Using a recombinant phage containing the mouse beta-Globin gene with lambda gtWES bacteriophage DNA, transcription initiation sites for Escherichia coli RNA polymerase and calf thymus RNA polymerase B were mapped at the 5' and 3' ends of the mouse beta-Globin gene. The bacterial enzyme was capable of initiating RNA synthesis at the 3' end site located at about 700 residues from the 3' end of the beta-Globin restriction enzyme map. Initiation at this site was more efficient than initiation at the known early lambda promotors (PL, PR). Calf thymus RNA polymerase B initiated transcription at the same sites as the bacterial enzyme but in this case maximum efficiency was at the 5' end site as compared to the 3' end site. Initiation of transcription occurs in the region of the d(T-A-T-A-A) sequence. Initiation efficiency at the 5' end site, as probed by the maximum rate of transcription, was shown to depend partly upon the presence of the adjacent sequences upstream and downstream of the 5' initiation site.

Base Sequence↗
PubMed1981

In vitro cytotoxic properties of plasma fractions from uremic patients.

The growth of cultured cells was studied in the presence of control and uremic plasma. Cell multiplication was observed by in situ countings and measured by 3H-thymidine incorporation during one population doubling time of mouse 3T3 fibroblasts. Uremic plasma were taken from severe uremic patients (plasma creat. greater than 0.45 mM/L) and from hemodialysed (HD) patients: plasma from HD patients were obtained at the beginning and end of a dialysis session. The 3H-Thymidine incorporation in the presence of uremic plasma was decreased (3620 +/- 160 cpm, n = 16) as compared to the control incorporation (8500 +/- 520 cpm, n = 14) (p 0.01). The comparison between the pre- and post-dialysis incorporation values (3900 +/- 660 cpm vs 9580 +/- 1600 cpm, n = 8) showed a significant increase of the 3H-Thymidine incorporation in the presence of post-dialysis plasma (paired t test: p less than 0.01) which did not differ from that of control plasma. To obtain information on the properties of the cytotoxic material, incubations were made with ultrafiltrate (UF) of plasma and UF middle molecular weight fraction of UF obtained by G-15 Sephadex filtration. Uremic UF and fraction displayed no cytotoxic properties when added alone to the culture medium. The pre-incubation of uremic UF and "middle molecule" fraction with control plasma restored a cytotoxic effect which was not different from that observed with total uremic plasma. Uremic plasma induces an inhibition of the growth of cultured cells. That is due to ultrafiltrate molecules abnormally accumulated in uremic plasma which are inhibitory when mixed with plasma macromolecules.

Animals↗
PubMed1980

Preparative isoelectric focusing and some properties of solubilized adenylate cyclase from rat brain.

A new procedure for the purification of rat brain adenylate cyclase (ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1) is presented. The enzyme solubilized in Lubrol PX was purified either by molecular sieving or by hydrophobic chromatography, followed by a preparative isoelectric focusing step. For this purpose, a new isoelectric focusing technique was developed which allows a good resolution of adenylate cyclase in a short period of time. When resolved by this procedure, the enzyme migrated as a single molecular species with a pI of 6.3. When isoelectric focusing was performed in the presence of EGTA, two distinct peaks of activity could be detected at pI 6.1 and 7.3. This suggests that adenylate cyclase consists of two subunits held together by divalent ions. It is shown that the purified adenylate cyclase has a smaller sedimentation coefficient and is less hydrophobic than the native one. We conclude that the adenylate cyclase containing complex was at least partially disaggregated by this procedure.

Adenylyl Cyclases↗
PubMed1980

Selective action of colchicine on protein synthesis and release in a clonal line of rat glial cells.

The effect of colchicine on protein synthesis and secretion in stationary cultures of clonal rat glial cells C6 was examined. Colchicine inhibited the synthesis of the brain specific S100 protein in intact cells but not in a cell-free protein synthesizing system derived from these cells. There was no demonstrable effect of the drug on the synthesis of any of the several hundred proteins resolved by a two-dimensional electrophoretic analysis. However, colchicine specifically enhanced the secretion of several proteins of molecular weighs of 30,000 and of 200-300,000 into the medium. Two of the high molecular weight proteins were apparently membrane proteins whose release into the medium was stimulated by the drug.

Animals↗