PubMed Health⌕ Search

Biomedical subjects

I F Pryme

Publications and source records attributed to I F Pryme.

72 records · Page 4Linked to original sources
PubMed1980

The effect of "shearing" forces during ultracentrifugation on the membrane-bound polysomes associated with light rough microsomes of MPC-11 cells.

When microsomes, isolated from MPC-11 cells after nitrogen cavitation of cells in buffer containing 100 mM KCl, were separated into light rough (LR) and smooth (S) fractions by discontinuous gradient centrifugation it was observed that [3H]-choline label and A260 nm absorption did not coincide in the LR region of the gradient. This was in contrast to the situation when microsomes were isolated from cells disrupted by nitrogen cavitation at 25 mM KCl. The A260 nm absorbing material that appeared in gradient fractions (1-5) below the position of LR membranes was found to consist of polysomal material. This material gave a "richer" polysome profile than that released from the LR membranes by addition of detergent. Labeling experiments with [3H]-leucine showed that nascent polypeptides associated with monosomes and polysomes in fractions 1-5 were of shorter length than the corresponding ones in the LR fraction. A mere contamination of LR microsomes by free polysomes appeared most unlikely. The results are consistent with an effect of "shearing" on the membrane-bound polysomes of the LR microsomes under specific experimental conditions. This effect results in the production of a 5' mRNA fragment (short polypeptide chains) and a 3' mRNA fragment (long polypeptide chains), the former fragment migrating further down the gradient tube free of LR membranes, whilst the latter remained attached to the LR membranes.

Animals↗
PubMed1980

Correlation of the effect of feeding upon the cell cycle distribution profiles of MPC-11 cells with the relative appearance of [3H]-choline labeled material in microsomal subfractions and other cell fractions.

Cultures of mouse plasmacytoma cells (MPC-11) grown within the range 6-23 x 10(5) cells/ml showed considerable variation in cell cycle distribution profiles and also differences with regard to relative amounts of microsomal subfractions. The variability of appearance of heavy rough (HR) and light rough (LR) microsomal subfractions was not merely due to differences in nutritional state of the culture. Cultures containing a high S/G2 + M cell cycld distribution ratio showed a high content of HR microsomal membranes; as the S/G2 + M ratio decreased, so too decreased the amount of HR material whilst the amount of LR microsomal membranes increased. The results indicate that there is a direct correlation between phase of cell cycle and both amount and relative distribution of rough microsomal membranes, the smooth fraction (S), however, remains relatively unchanged.

Animals↗
PubMed1979

Differences in the incorporation of [3H]-glucosamine into nascent polypeptide chains on free polysomes and two fractions of membrane-bound polysomes in mouse myeloma cells.

The incorporation of [3H]-glucosamine into polypeptides of three fractions of polysomes in MPC-11 cells was studied. After short term incubation greatest incorporation was observed in a fraction of membrane-bound polysomes, which after nitrogen cavitation of cells, remained bound to the endoplasmic reticulum (ER) associated with the nucleus (fraction 2). Polypeptide chains on membrane-bound polysomes in the microsomal fraction (fraction 1) and free polysomes contained much less radioactivity. Since nascent polypeptide chains contained within membrane-bound polysomes of fraction 2 are glycosylated at an earlier stage than those in fraction 1 it is likely that this represents a difference in type of proteins synthesized in the respective fractions of ER.

Cell Line↗
PubMed1978

The effects of orally administered L-arginine HCl on the development of myeloma tumors in BABL/C mice following the injection of single cell suspensions, cell aggregates or tumor fragments; and on the growth of two ascites tumour cell lines.

When arginine-HCl was added to the drinking water of Balb/c mice the formation of subcutaneous tumours following the injection of single cell suspensions of MPC-11 cells was prevented, however, tumours did develop after injecting tumour fragments or aggregates of suspension-cultured cells. Arginine-HCl had no inhibitory effect upon the production of Krebs II and 6C3HED lymphoma ascites tumours in Balb/c and C3H mice respectively.

Administration, Oral↗
PubMed1976

Synthesis and secretion of light-chain immunoglobulin in two successive cycles of synchronized plasmacytoma cells.

Suspension-cultured mouse plasmacytoma cells (MPC-11) were accumulated in the late G1 phase by exposure to isoleucine-deficient medium for 20-24 h. The arrested culture was fed with complete medium enabling the cells to continue the cell cycle synchronously, undergo mitosis, and enter a second cycle of growth. This method of synchronization left the protein-synthesizing ability intact as judged by the polysome profile and the capacity of the cells to incorporate labeled amino acids into protein after the restoration of isoleucine. After incubation in isoleucine-deficient medium and the addition of isoleucine to the culture, cells entered the S phase after a short lag, as judged by [3H]thymidine incorporation into nucleic acid and by spectrophotometric measurement of nuclear DNA. The cells were in mitosis between 12 and 18 h as judged by the increase in cell count and analysis of cell populations on albumin gradients. Synthesis and secretion of light-chain immunoglobulin were maximal in the late G1/early S phase of the first cycle. During late S phase, G2 phase, and mitosis, both synthesis and secretion were observed to be at a low level; however, immediately after motosis the cells which then entered the G1 phase apparently commenced synthesis of light chain immunoglobulin straight away, although secretion of labeled material remained at a low level.

Cell Count↗