DIFFERENTIAL REGULATION OF NITROGEN-METABOLISM IN THE WILD-TYPE AND THE HIGH-LIGHT-TOLERANT MUTANT-CELLS OF ANACYSTIS-NIDULANS

The glutamine synthetase activity in the wild type and high-light-tole rant mutant of Anacystis exhibited differential response to the increa sing light intensity (2-40 W/m(2)). As evident from the results, the g lutamine synthetase (GS) activity in the wild type is more dependent o n respiration, whereas the GS enzyme in the mutant cells derived its c arbon and energy from photosynthesis, Further, results revealed that t he reduced GS activity in the wild-type cells under the high-light str ess was accompanied by high aspartate amino transferase (AST/GOT) acti vity and low alanine amino transferase (ALT/GPT) activity. On the cont rary, high GS activity in the mutant cells was accompanied by low AST/ GOT enzyme activity and high ALT/GPT activity. It was inferred that mu tant and wild-type cells adapt to the high-light stress by different m echanisms.