under these conditions , cells with the his1-1s mutation are capable of growth on minimal medium at 15 degrees . three kinds of reversions of a his1-1s thr4 sup ( his1-1s ) strain to histidine prototrophy have been obtained : ( 1 ) his1-1s locus reversions to his1 that restore growth without added histidine at 30 degrees , ( 2 ) thr4 reversions to thr4 that simultaneously eliminate the requirement for threonine and restore the low-temperature effect on the his1-1s allele , and ( 3 ) mutations from sup to sup .
C0007634
cells
C1708726
locus