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Trypsin and aminopeptidase gene expression is affected by age and food composition in Anopheles gambiae
F J Lemos1, A J Cornel, M Jacobs-Lorena
1Universidade Estadual do Norte Fluminense, Centro de Biochiencias e Biotecnologia, R.J., Brazil.
Insights
Mosquito gut proteases, trypsin and aminopeptidase, show distinct expression patterns. Trypsin gene expression is induced by blood meals and abdominal distention, while aminopeptidase is constitutively expressed regardless of diet.
Area of Science:
- Molecular biology
- Entomology
- Biochemistry
Background:
- The Anopheles gambiae mosquito is a vector for malaria.
- Gut proteases play crucial roles in insect digestion and physiology.
- Understanding protease regulation is vital for vector control strategies.
Purpose of the Study:
- To investigate the effects of age and diet on trypsin and aminopeptidase gene expression and enzyme activity in the Anopheles gambiae gut.
- To elucidate the regulatory mechanisms of these digestive enzymes in response to feeding.
Main Methods:
- Quantitative real-time PCR to measure mRNA levels.
- Enzyme activity assays to quantify protease function.
- Subcellular fractionation to determine enzyme localization.
Main Results:
- Trypsin mRNA was absent in newly eclosed mosquitoes but increased significantly within 24 hours.
- Trypsin enzyme activity was present at low levels in newly eclosed females and induced by blood meals.
- Abdominal distention was suggested to induce trypsin secretion into the gut lumen.
- Aminopeptidase activity was substantial in both newly eclosed and older sugar-fed mosquitoes.
- Aminopeptidase activity and localization were largely independent of food composition and ingestion.
Conclusions:
- Trypsin expression in Anopheles gambiae is tightly regulated by age, blood feeding, and abdominal distention.
- Aminopeptidase exhibits constitutive expression and activity, suggesting a role independent of specific meal components.
- Differential regulation of these proteases highlights distinct physiological roles in mosquito digestion.
Abstract:
The effects of age and food composition on the expression of trypsin and aminopeptidase genes in the Anopheles gambiae gut were investigated. No trypsin mRNA was detected in the gut of newly eclosed females, but this mRNA accumulated to relatively high levels within the first day of life. In contrast, low, but significant trypsin enzyme activity was observed in newly eclosed females. Subcellular fractionation experiments suggested that abdominal distention induces the secretion of the enzyme into the lumen. Blood, but not a protein-free meal, induced the accumulation of new trypsin mRNA and enzyme. Unlike trypsin, substantial aminopeptidase activity was detected in newly eclosed and in older, sugar fed mosquitoes. Moreover, the subcellular localization of aminopeptidase did not change appreciably with food ingestion, and the early increase of enzyme activity was independent of food composition.
