Isolation and characterization of drug resistant mutants of Crithidia fasciculata.

Mutants of Crithidia fasciculata, resistant to Actinomycin D, Tubercidin, Crystal Violet, 6-Azauridine, and 5-Fluorouracil were obtained and characterized. The mutants were stable when maintained under nonselective conditions, and could be grouped in several subclasses on the basis of cross-resistance to other drugs. Actinomycin D- and Crystal Violet-resistant mutants appeared spontaneously whereas the others appeared only after mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. Analysis with a cell sorter indicated no large scale meiotic changes in ploidy under the various culture conditions employed. These mutants may provide suitable, selectable, genetic markers for use in studying the possibility of a sexual mating process in Crithidia.