A morphological and functional characterization of Bombyx mori larval midgut cells in culture

• Main Authors: G Cermenati, P Corti, S Caccia, B Giordana, M Casartelli
• Format: Article
• Language: English
• Published: University of Modena and Reggio Emilia 2007-11-01
• Series: Invertebrate Survival Journal
• Subjects: Bombyx mori larval midgut; stem cells; columnar cells in culture; cytoskeletal scaffolding; digestive enzymes; protein uptake
• Online Access: https://isj02.unimore.it/index.php/ISJ/article/view/151

Recent studies have shown that Bombyx mori larval midgut can transport proteins unaltered following the transcellular pathway by transcytosis. The numerous steps involved in this complex process are still unknown in the insect midgut, and a promising tool to elucidate this aspect is the availability of single midgut cells in culture suitable for transport experiments. Mature midgut cells in culture were obtained from stem cells isolated from B. mori larvae cultured in Grace’s medium supplemented with 20-hydroxyecdysone (20-HE) and α-arylphorin. After three weeks, up to 60 % of the cultured cells were differentiated into columnar and goblet cells, the two predominant cell types in the midgut epithelium. These cells presented in vitro the same shape, morphology and polarity recorded in vivo, even if their dimensions were slightly reduced. Columnar cells displayed a well developed cytoskeletal arrangement, with actin filaments highly organized within the thick brush border and distributed in faint filaments in the cell cytoplasm. Microtubules formed a substantial net just beneath the brush border and ran longitudinally from the apical to the basal pole of the cell. Cultured cells homogenates displayed aminopeptidase N and alkaline phosphatase activity, proving that these two enzymes, involved in vivo in the intermediate and final digestion, are expressed also in vitro. The columnar cells differentiated in culture were able to internalize two model proteins with quite different transport rates.