TISSUE-SPECIFIC CHANGES IN POLYAMINE LEVELS OF NEURAL TISSUE AND FAT-BODY IN ADULT CRICKETS

The three major polyamines-putrescine, spermidine, and spermine-were s tudied and changes of their levels were examined in extracts of cerebr al ganglia and fat body from adult Acheta domesticus. In nervous tissu e, only spermidine and spermine were present and spermine was two- to three-fold more abundant than spermidine. The polyamine levels were hi gh up to day 3, decreased on day 4, and then remained relatively uncha nged up to day 10. The spermidine/spermine ratios decreased during the imaginal life. Higher spermidine titres were observed in the neural t issue of egg-laying females compared to virgin females. In the fat bod y, putrescine was detected together with spermidine and spermine. Sper midine and spermine levels were two-fold higher than putrescine. Fat b ody of virgin females contained two times more polyamines than mate fa t body. Low at emergence, spermidine and spermine concentrations peake d on days 2-3 only in females, and egg-laying was characterized by an increase of putrescine and spermidine titres. Starvation did not chang e polyamine contents, implying homeostatic regulation of the intracell ular polyamine metabolism. These data showing tissue specific changes in polyamine levels during the imaginal life of Acheta domesticus poin t to the physiological importance of polyamines as possible intracellu lar regulators during adult insect development. (C) 1993 Wiley-Liss, i nc.