Tetraploid Cell Lines Research Articles

A rapid method for production of binucleate cells

Populations of BHK-21 fibroblasts that are 90–95% binucleate can be obtained within 2–3 h by combining mitotic synchrony techniques with use of the drug cytochalasin B. Such populations are potentially useful for the study of nuclear-cytoplasmic balance and control, nuclear synchrony, and the production of tetraploid cell lines.

Induction of hypoxanthine-guanine-phosphoribosyl-transferase (HGPRT)-deficient mutants in diploid and tetraploid Chinese hamster cell lines : Van Zeeland, A. A., and J. W. J. M. Simons, Department of Radiation Genetics and Chemical Mutagenesis, University of Leiden (The Netherlands)

Induction of hypoxanthine-guanine-phosphoribosyl-transferase (HGPRT)-deficient mutants in diploid and tetraploid Chinese hamster cell lines : Van Zeeland, A. A., and J. W. J. M. Simons, Department of Radiation Genetics and Chemical Mutagenesis, University of Leiden (The Netherlands)

Early functional mutants of mammalian cells.

WE have reported before1 a method for the isolation of conditional lethal mutants (temperature sensitive) of mammalian cells and have shown2,3 the usefulness of such mutants in the study of cell biology. We modified the technique originally designed to select for mutant clones restricted in growth at 39.5° C to select preferentially for mutants defective in (1) DNA synthesis (involving replication), or (2) RNA synthesis (involving transcription or synthesis of various RNA species). These mutants were intended for studying (1) cellular regulatory mechanisms and (2) host-virus interactions. Because of unusually high reversion frequency in the mutant clones of the tetraploid cell line (in the order of 10−4 to 10−5), a second selection (by testing these mutants through successive passage for efficiency of plating at the restricted temperature) becomes necessary so that these selected clones could be used for biochemical analysis. All our mutants were thus selected for reversion frequencies of less than 10−5.

CHROMOSOMAL MUTATION IN BONE-MARROW AS CAUSE OF ACQUIRED GRANULOMATOUS DISEASE AND REFRACTORY MACROCYTIC ANÆMIA

A man aged 58, who developed chronic granulomatous ulceration of the perineum, was found to have a refractory macrocytic anæmia and a defect in bactericidal activity and chemotactic motility of polymorphonuclear leucocytes (P.M.N.S). Almost all his circulating P.M.N.S were excessively large and hypersegmented, and cytogenetic studies of the bone-marrow revealed a tetraploid cell line with a structural chromosome aberration. It is suggested that a unique somatic mutation in the bone-marrow led to the abnormal blood picture and to the defects in P.M.N. function. One of the genetic loci important in the bactericidal activity of P.M.N.S may be located in the presumptive chromosomal deletion.

Initial characterization of a temperature sensitive mutant of monkey kidney cell.

AMONG the several temparature sensitive conditional mutants of the tetraploid cell line of African green monkey kidney (BS-C-1) is one (ts-2) in which simian virus 40 either fails to multiply or form tumour specific antigens (unpublished) at the temperature (39.5° C) at which cellular growth is restricted1. Because of the potential importance of this mutant in the study of host dependence of tumour virus multiplication, we have investigated several of its properties and have found that the mutant ts-2 is blocked in the incorporation of 3H-thymidine in the nucleus, probably in the nucleolus.

Polyploidy in malignant melanoma

Chromosome studies were performed on primary or metastatic malignant melanoma from 6 patients. All of them were aneuploid and had either hyperdiploid, near triploid, tetraploid, or hypertetraploid cell lines. Two of them had definite stem-cell lines, but the other 4 cases had a wide distribution of chromosome numbers with no apparent cell lines. Three of the 6 patients had one or more marker chromosomes, i.e., large submetacentrics or long aaocentrics. These results lead us to speculate that the rapid cell growth is due not only to selection but also to continuous replication defects and mitotic abnormalities.

Polyploidy in human malignancy. Hypopentaploid chromosome pattern in malignant reticulosis with secondary sideroachrestic anemia.

A 73-year-old man developed malignant reticulosis with secondary sideroachrestic anemia. On eight occasions chromosome analyses were performed which included 208 peripheral blood cells and 403 bone marrow cells. Chromosome number ranged from 40-625. In marrow a hypopentaploid stemline predominated with a mode at 104-106. Supernumerary chromosomes were found in groups C, D, E, F and G, including two markers. Minor diploid, tetraploid and polyploid cell lines were also present. Peripheral blood cells were, with some exceptions, exactly diploid and only 1.5% were near-tetraploid. During progression of the disease more and more hypertetraploid, hypopentaploid and polyploid reticulum cells emerged in the bone marrow, suggesting clonal evolution.

Pilot studies of the cell population kinetics in irradiated tumours

Diploid and tetraploid cell lines, both derived from the same Ehrlich ascites tumor, were mixed together in varying proportions. The resulting cell populations were grown in mice by serial intraperitoneal transfers. At regular time intervals, the relative proportion of the two cell types was determined by chromosome analysis of colchicine treated populations. In all cases, the frequency of diploid cells increased gradually, until a constant level was reached. The length of the growth period, necessary for the shift, was inversely related to the initial proportion of diploid cells. The observational data were in a good agreement with a theoretical kinetic model defined by an independent, average growth rate of the diploid and tetraploid subpopulations, and the occurrence of endomitotic processes in diploid cells giving rise to tetraploid cells at a constant rate. The numerical value of the kinetic parameters, calculated by mathematical formulas which were developed on the basis of the model, agreed well with previous estimates. The role of the particular kinetics in the development of radioresistant cell populations was discussed in view of the greater radioresistance of tetraploid cells as compared to diploid cells.