Boris Ephrussi

A Technique of Transplantation for Drosophila

A technique of transplantation, applicable to Drosophila species, which consists of injection by means of a micro-pipette, is described in some detail.

A Selective System for the Isolation of Hybrids Between L Cells and Normal Cells

T HE occurrence of mating between cultured cells of a permanent line and freshly explanted, normal cells has been recently demonstrated (previous communication). We have developed a system for tho selection of such hybrids and for the determination of the rate of their formation. The purpose of this communication is to describe this system. The permanent line used is A9, a sub-line of the L line, kindly supplied to us by Dr. J. W. Littlefield. A9 is resistant to 3 [J.g/ml. of 8-azaguanino. (A similar line was used by Littlefield1 to establish a selective system involving two biochemically marked L cell lines.) Cells of line A9 are heteroploid and contain 51-58 chromosomes (mode = 55), 18-20 of which are hi-armed. The normal cells are

Infection of chick iris epithelium with the Rous sarcoma virus in vitro

Abstract Cells of chicken iris epithelium have been grown in vitro for over four months. During this period they have maintained the characteristics of the tissue of origin (formation of epithelial membranes and production of pigment). The ability of these cells of ectodermal origin to be infected with the Rous sarcoma virus and to support its multiplication has been demonstrated. Under the influence of the infecting virus, the cells of iris epithelium undergo morphological changes similar to those exhibited by infected fibroblasts, the type of change depending upon the genotype of the infecting virus.

DEVELOPMENT OF EYE COLORS IN DROSOPHILA: NATURE OF THE DIFFUSIBLE SUBSTANCES; EFFECTS OF YEAST, PEPTONES AND STARVATION ON THEIR PRODUCTION

An account of chemical investigations of the nature of the v+ and cn+ hormones of Drosophila is given. It is concluded that they probably belong to the group of amino-bases.It is shown that the effects of Colliphora extracts, containing these hormones, are proportional to the concentration.It is shown that under the influence of starvation v flies undergo a modification of the eye color, similar to that produced by the v+ hormone.It is shown that similar effects are produced by feeding Drosophila larvae on small doses of dry yeast. At low doses the effects produced are proportional to the concentration of yeast. Higher doses of dry yeast suppress the effect which is also suppressed by the presence of glucose in the medium.Various peptones also produce a hormone-like effect when fed to v larvae. Again the effect is proportional to the concentration of peptone at low concentrations, and decreases above a certain maximum.High concentrations of yeast extract suppress the effects of the peptones, but not the e...

Development of Eye Colors in Drosophila: The Mutants Bright and Mahogany

(1) ca+ substance-a substance necessary for the development of wild type _pigment which is absent or reduced in amount in the eye color mutant claret. (2) v+ substance-a substance capable of changing the development of a vermilion eye in such a wray that it forms pigment phenotypically like that of a wild type eye. (3) cn+ substance-a substance capable of changing the development of a -cinnabar eye in such a way that it is similar in its pigmentation to a wild -type eye.

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.