TRANSCRIPTIONAL REGULATION OF FABP EXPRESSION IN-FLIGHT MUSCLE OF THEDESERT LOCUST, SCHISTOCERCA-GREGARIA

FABP is the most abundant cytosolic protein in developed fight muscle of adult locusts, but it is completely absent in nymphs. During the tw o weeks following adult ecdysis, FABP rises to 18% of the total solubl e proteins. its mRNA increases steadily up to day 8, before it gradual ly declines until reaching a low concentration at day 15, which remain s constant for the rest of the animal's life. Using a PCR primer combi nation specific for a 597 bp sequence of intron 1, we have developed a reverse transcription PCR assay to quantify the amount of primary tra nscript present in muscle tissue at various ages. The FABP gene is not transcribed prior to metamorphosis; its primary transcript rises rapi dly during the first two days of adult life, and remains close to maxi mal until day 5. Subsequently its level rapidly declines, ultimately r eaching values of less than 0.02% of the maximal level. The correlatio n between primary transcript, mRNA and FABP content were analyzed by m odeling transcription, translation and degradation with computer model ing software. The computer simulation is in good agreement with the ex perimentally obtained data, suggesting that the control of FABP expres sion in locust flight muscle occurs predominantly at the level of tran scription initiation. (C) 1998 Elsevier Science Ltd. All rights reserv ed.