Abstract
Putative serine protease genes including trypsin and chymotrypsin were identified in the tsetse fly Glossina morsitans morsitans during an EST project. Trypsin and chymotrypsin are major digestive enzymes involved in the parasite-host interactions of vector insects. In this study, two genes designated Gmmtry1 and Gmmchy1 were further characterized during blood digestion and in responses against parasite infection. Both Gmmtry1 and Gmmchy1 mRNA was expressed at high levels in the posterior region of the midgut. Gmmchy1 transcript increased following an infectious blood meal suggesting chymotrypsin is regulated by the presence of the trypanosome during the early establishment of the parasite infection in the midgut. The possible roles of trypsin and chymotrypsin proteases in determining the refractoriness of the tsetse fly against trypanosomes is also discussed.
