Two novel proteins with apparent molecular weight of 38 (Manduca sexta midgut MsM38) and 46kDa (MsM46) were isolated from midgut homogenates in wandering stage Manduca sexta larvae and both of them were found to be present exclusively in this tissue on Western blots. Immunocytochemical studies revealed that both proteins are expressed in the regenerative cells however, their distribution pattern is clearly different. MsM38 is localized in the cytoplasm of resting regenerative cells during the feeding period, and is accumulated in the calcospherits at the beginning of the wandering period. Along with the delamination of the larval epithelium, this protein is released apically from these vesicles. The antiserum labels an additional 76 kDa protein in the wandering larval midgut homogenates. The appearance of this 76 kDa protein coincides with the accumulation of the immunopositive material in the calcospherits. MsM46 is similarly distributed during the feeding period in the cytoplasm of regenerative cells. At the beginning of the wandering period it accumulates around the newly forming large apical vacuoles, that are released at the time of complete delamination of the larval epithelium. In parallel with this process MsM46, and another 40 kDa protein, that becomes labeled from this period on Western blots appeares on the apical microvillar projections. Thus both isolated proteins are directed apically from different compartments, that raises the possibility of a dual apical routing pathway in regenerative cells.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Environmental Science(all)