the cpxa and cpxb mutations appear to affect the production of active isozyme i , rather than its activity , since ( i ) neither the cpxa nor the cpxb gene mapped near the structural gene for isozyme i ( ilvb ) , ( ii ) the growth of mutant cells shifted from the permissive ( 34 degrees c ) to the nonpermissive ( 41 degrees c ) temperature did not immediately cease , but declined gradually over a period corresponding to several normal generation times , and ( iii ) the enzyme from mutant cells grown at 34 degrees c was as stable at 41 degrees c as the enzyme from cpx+ cells .
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growth of
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cells