AGE AND TISSUE-DEPENDENT CHANGES OF ORNITHINE DECARBOXYLASE AND S-ADENOSYLMETHIONINE DECARBOXYLASE ACTIVITIES IN NEURAL TISSUE AND FAT-BODYOF ADULT CRICKETS

The activities of ornithine decarboxylase and S-adenosylmethione ne de carboxylase, two key enzymes in polyamine metabolism, were determined during the first 10 days of imaginal life in the nervous tissue and th e rat body of the adult cricket Acheta domesticus. The kinetic constan ts or the two enzymes were also determined in both tissues. Both decar boxylases presented a higher activity in fat body than in nervous tiss ue. In nervous tissue, the activity of the two enzymes peaked at 16 h postemergence, then slowly decreased up to day 3-4. By contrast, the e nzymatic activities in fatbody, low at emergence, strongly increased o n day 2. Thereafter, whereas ornithine decarboxylase activity remained rather high, S-adenosyl-methionine decarboxylase activity dropped bac k to emergence levels by day 10. These results, examined in light of t he temporal alterations of polyamine levels observed in the two tissue s, demonstrate synchronous variations between polyamine contents and t he enzymes involved in their biosynthesis. (C) 1993 Wiley Liss, Inc.