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Biomedical subjects

B Ephrussi

Publications and source records attributed to B Ephrussi.

At least 19 recordsLinked to original sources
PubMed1977

Enhanced expression of alkaline phosphatase in hybrids between neuroblastoma and embryonal carcinoma.

Three independent hybrid cell lines were isolated from the fusion of clonal lines of embryonal carcinoma and neuroblastoma. A series of subclones was subsequently derived from the original hybrid clones. In early hybrid generations all hybrid lines showed enhancement of alkaline phosphatase activity, expressing 2--8 times the activity of the teratoma parental line. The overexpression of APase appears to take place in the stationary phase of the growth cycle. Segregation for very high levels of APase activity was observed among subclones of one hybrid line. Specific activities of the segregants ranged from 0.1 to 133. Results of heat denaturation studies are consistent with the hypothesis that it is the embryonal carcinoma APase that is being expressed in the hybrids.

Alkaline Phosphatase↗
PubMed1974

Behavior of three types of ribovirus-like particles in segregating hamster times mouse somatic hybrids.

An electron microscopic study of somatic hybrids resulting from a cross between hamster melanoma cells harboring R-type particles and mouse fibroblasts harboring intracisternal A-type and (mostly) immature C-type particles was performed. The major findings are: (a) hybrid cells that retain a large fraction of both hamster and mouse chromosomes produce all three types of particles; (b) the loss of mouse chromosomes is followed by that of intracisternal A- and C-type particles; (c) the continued production of A- and C-type particles is dependent on the retention of different mouse chromosomes; (d) the mixed intracellular population of R- and A-particles comprises a small number of complex structures in which the two types of virions are enclosed within a common envelope.

Animals↗
PubMed1973

Alkaline phosphatase activity in mouse teratoma.

In tumors and embryoid bodies of mouse teratoma a correlation has been established between specific activity of alkaline phosphatase (EC 3.1.3.1) and content of embryonal carcinoma, the stem cell of the tumor. A histochemical study of embryoid bodies has shown that high levels of the enzyme are confined to embryonal carcinoma. Fifteen tissue culture lines could be classified into three groups: (a) lines identifiable as pluripotential embryonal carcinoma by their morphology, tumorigenicity, and capacity to differentiate in vivo; (b) nullipotential embryonal carcinoma, resembling pluripotential embryonal carcinoma in morphology and malignancy but giving rise to undifferentiated tumors; and (c) lines of apparently nonmalignant somatic cells. Both types of embryonal carcinoma possess levels of alkaline phosphatase 5- to a 100-fold higher than the somatic cell lines. The embryonal carcinoma enzyme resembles the enzymes from kidney and placenta in kinetics of thermal inactivation and sensitivity to the inhibitor L-phenylalanine, but is distinguishable from the alkaline phosphatases of liver and intestine. These findings are discussed in relation to the use of teratoma for the study of cell differentiation.

Alkaline Phosphatase↗
PubMed1972

Gene dosage dependence of pigment synthesis in melanoma x fibroblast hybrids (hamster cells-mouse fibroblast-DOPA-oxidase-irradiation).

Hybrids between Syrian hamster melanoma cells and mouse fibroblasts, containing one genome (1s) of each parent, produce neither melanin nor DOPA-oxidase ("extinction"). Attempts to induce loss of the fibroblast chromosomes by irradiation of the fibroblasts before fusion with melanoma cells resulted in the formation of colonies comprising pigmented hybrid cells, which contained 2s melanoma and 1s fibroblast chromosome-complements suggesting that extinction or re-expression of melanogenesis is a function of genic balance. This interpretation was confirmed by crosses between 2s melanoma cells with unirradiated 1s fibroblasts, which produced both pigmented and unpigmented hybrids. No correlation has thus far been established between karyotype and phenotype of the hybrid cells, but analysis of the karyological data suggests that the fibroblast chromosomes responsible for extinction cannot be numerous.

Animals↗