Cytoplasmic transfer of chloramphenicol resistance in human tissue culture cells.

The cytoplasmic inheritance of human chloramphenicol (cap) resistance has been demonstrated by removing the nuclei of cells of the CAP-resistant HeLa strain 296-1 (enucleation) and fusing them to a CAP-sensitive HeLa strain lacking nuclear thymidine kinase. Plating the fusion products in bromodeoxyuridine and CAP resulted in the growth of about 150 colonies/10(6) parent cells plated. Permanent cell lines (cybrids) grown from such fusions have been designated HEB. A recloned HEB cybrid (HEB7A) has also been enucleated and fused to hypoxanthine phosphoribosyl transferase (HPRT)-deficient HeLa cells (S3AG1) and HPRT-deficient lymphocytes (WAL-2A). Cybrids were selected in thioguanine and CAP. In the fusion of enucleated (en) HEB7A to S3AG1, 1,200 colonies/10(6) parents were observed. Fusion of enHEB7A to WAL-2A was done in mass culture and cybrids were obtained on three separate occasions. In every case the parental controls were negative. All isolates tested from the above fusions have the CAP-resistant characteristics, in vivo and in vitro, of the enucleated parent and the nuclear characteristics of the CAP-sensitive parent, such as chromosome number, morphology, and specific isozyme and chromosome markers. Therefore, it can be concluded that CAP resistance is coded in the cytoplasm and not in the nucleus of 296-1 cells. Furthermore, this resistance can be transferred to cells of widely different origin and differentiated state. These studies represent the first genetic evidence of cytoplasmic inheritance in human cells.

OBSERVATIONS ON SOME EFFECTS OF THE SODIUM SALTS OF CERTAIN MONOCARBOXYLIC ACIDS ON ESTABLISHED CELL LINES

There appears to be very little information in the literature pertaining to concentrations of various air pollutants or tobacco-smoke constituents that may be toxic or nontoxic to tissue cells cultivated in vitro. We have undertaken the task of ascertaining these levels and this report records observations concerning the first few of many known pollutants.The effects of the sodium salts of 10 monocarboxylic acids (formate, acetate, propionate, butyrate, valerate, caproate, oenanthylate, caprylate, caprate, and benzoate) on several established cell lines (HeLa, strain L, human lung, human skin) were studied.All of these compounds at a concentration of 10 mg% were toxic to the cell lines tested with the exceptions of formate, acetate, and benzoate on strain L, and of valerate and caprylate on human lung.All the compounds either stimulated proliferation or had no significant effect at 1 mg% except caproate and benzoate, which were toxic to human lung and human skin cells, respectively.