Transcriptional regulation of FABP expression in flight muscle of the desert locust, Schistocerca gregaria

Abstract

FABP is the most abundant cytosolic protein in developed flight muscle of adult locusts, but it is completely absent in nymphs. During the two weeks following adult ecdysis, FABP rises to 18% of the total soluble proteins. Its mRNA increases steadily up to day 8, before it gradually declines until reaching a low concentration at day 15, which remains constant for the rest of the animal's life. Using a PCR primer combination specific for a 597 bp sequence of intron 1, we have developed a reverse transcription PCR assay to quantify the amount of primary transcript present in muscle tissue at various ages. The FABP gene is not transcribed prior to metamorphosis; its primary transcript rises rapidly during the first two days of adult life, and remains close to maximal until day 5. Subsequently its level rapidly declines, ultimately reaching values of less than 0.02% of the maximal level. The correlation between primary transcript, mRNA and FABP content were analyzed by modeling transcription, translation and degradation with computer modeling software. The computer simulation is in good agreement with the experimentally obtained data, suggesting that the control of FABP expression in locust flight muscle occurs predominantly at the level of transcription initiation.