DIETARY CONTROL OF LATE TRYPSIN GENE-TRANSCRIPTION IN AEDES-AEGYPTI

In Aedes aegypti the levels of midgut trypsin activity after feeding a re directly proportional to the protein concentration in the meal. The mechanisms of this up-regulatory event were investigated by analyzing the expression of the late trypsin gene under different dietary condi tions. Transcription of the gene was dependent on both the quality and quantity of protein in the meal. As measured by Northern blot analysi s, the levels of late trypsin gene expression increased up to 100-fold 24 h after feeding on gamma-globulin, hemoglobin or albumin (100 mg/m l). In contrast, gelatin, histone, amino acids, saline or agarose were very poor inducers of transcription. The rates of late trypsin transc ription induced during the first 24 h were directly proportional to th e concentration of protein in the meal. These data further support the suggestion that the primary mechanism that regulates the synthesis of trypsin in the mosquito midgut is transcriptional regulation of the g ene. This regulatory mechanism enables the midgut to maintain the appr opriate balance between protease synthesis and the protein content of the meal.