The influence of certain colchicine derivatives on the growth characteristics of L cells.

Colchicine and its derivatives (demecolcine, 2-demethyldemecolcine and acetylated 2-demethyldemecolcine) blocked the mitotic activity of L cells and inhibited proliferation and DNA synthesis. This effect depended on the length of the exposure and the concentration of the substances tested (from 0.05 micrograms/ml up to 2.

Hybrids formed by fusion of X- or gamma-irradiated and non-irradiated mouse cells.

Hybrid cells were obtained by fusion of irradiated and non-irradiated mouse cells of two different lines; they differed from the parent lines and from the hybrid cells of non-irradiated parents in their morphological, growth and karyological properties. The frequency of their occurrence was lower than in hybrids from non-irradiated cells, and unlike the irradiated cells of the parent line, these hybrid cells were capable of permanent proliferation in vitro. Chromosomes of the irradiated parent line were preferentially eliminated from the karyotype of the hybrids.

Establishment of mouse neuroblastoma clone E 7 in serum-free medium.

Ninety-six clonal populations were derived from a wild mouse neuroblastoma cell population C 1300 in a serum-free medium containing commercially available serum growth-promoting proteins (GPP). From among these 96 lines the clonal population E 7 was chosen for further work because it displayed maximum spontaneous morphological differentiation. The neuroblastoma clonal population differs morphologically from the original population; it was defined both cytogenetically and by means of growth parameters.

Isolated fractions of the growth-promoting alpha-globulin stimulate differently the incorporation of exogenous DNA into L cells.

The growth-promoting alpha-globulin necessary for long-term cultivation of mammalian cells in serum-free medium is a complex of several proteins which also stimulates the incorporation of exogenous DNA into recipient L cells. Biological activity responsible for the stimulation of DNA incorporation into L cells can be concentrated because one of two major protein components, compared to the whole GPAG complex, increases incorporation into cell nuclei by 100%.

Early studies in cybrids derived from fusion of mouse lymphosarcoma cells LS/BL and L cell cytoplasts.

This paper describes the proliferative and morphological properties of cybrid cells derived from fusion of the whole cells of a mouse lymphosarcoma LS/BL and cytoplasts prepared from L cells or their biochemically marked mutants (HGPRT-). In cybrids, decondensation of parent LS/BL nuclei and their cooperation with heterologous cytoplasm was observed. Cybrids incorporated the precursors of nucleic acid and protein synthesis up to 70 h after fusion.