| Abstract: | Mutants of Chlorella vulgaris induced by N-methyl-N′-nitro-N-nitrosoguanidine (NG), and, selected for the resistance to either ethionine or 6-methylpurine, were tested for the relative rate of incorporation into protein of 3H-methionine and 14C-leucine. A highly significant, correlation between the 3H-to-14C ratio in the protein and its methionine content was found. 6-Methylpurine proved to be more effective than ethionine as a screening agent for high methionine strains. Screening for 6-methylpurine resistance, followed by a second screening for the highest methionine-to-leucine incorporation ratio, led to isolation of the mutants with a content up to 45% higher in methionine and up to 3 times higher in cysteine with respect to the wild strain. |
