VISUALIZATION OF PROTEINDIGESTION IN THE MIDGUT OF THEACARID MITE Lepidoglyphusdestructor

摘要

The ingestion of chromogenic or fluorescent substrates for protease detectionenables the visualization of digestive processes in mites in vivo due to theirtransparent bodies. The substrates for protease detection were offered toLepidoglyphus destructor, and the resulting signals were observed in specimensunder a compound microscope. The protease activity was successfully localizedusing chromogenic substrates (azoalbumin, AAPpNA, SAAPFpNA,elastin–orcein, SA3pNA, ZRRpNA, ArgpNA, and MAAPMpNA) andfluorescent substrates (casein–fluorescein, albumin–fluorescein, AAPAMC,BAAMC, ZRRAMC, ArgAMC, and AGPPPAMC). No activity wasdetected using the keratin azure and BApNA substrates. In the mesodeum,trypsin-like activity generated by hydrolysis of the BApNA substrate was notobserved, but the BAAMC substrate allowed the visualization of trypsin-likeactivity in food boli in the posterior mesodeum. The results indicate thatcathepsins B, D, and G and cathepsin H or aminopeptidase-like activities arepresent in the midgut of L. destructor. Among these activities, cathepsin D-likeactivity was identifled for the flrst time in the gut of L. destructor. All proteasesmentioned are produced in the mesodeal lumen and form the food bolustogether with ingested food, afterward passing through the gut to be defecated.The method used enables the visualization of protease activities in the gut oftransparent animals.