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

The activities of ornithine decarboxylase and S-adenosylmethione ne decarboxylase, two key enzymes in polyamine metabolism, were determined during the first 10 days of imaginal life in the nervous tissue and the rat body of the adult cricket Acheta domesticus. The kinetic constants or the two enzymes were also determined in both tissues. Both decarboxylases presented a higher activity in fat body than in nervous tissue. 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 enzymatic activities in fatbody, low at emergence, strongly increased on day 2. Thereafter, whereas ornithine decarboxylase activity remained rather high, S-adenosyl-methionine decarboxylase activity dropped back to emergence levels by day 10. These results, examined in light of the temporal alterations of polyamine levels observed in the two tissues, demonstrate synchronous variations between polyamine contents and the enzymes involved in their biosynthesis. (C) 1993 Wiley Liss, Inc.