부산대학교 도서관

At each molt of Manduca , the large dermal secretory cells expel the protein contents of their vacuoles into the hemocoel. The constellation of proteins expelled at the last larval-pupal molt, however, differs qualitatively from those proteins released at earlier larval-larval molts. Secretory cells at the two stages not only have different lectin staining properties but also have different proteins that separate on two-dimensional gels. Numerous physiological changes accompany the termination of the last larval instar, including increased chitin synthesis, diminished oxygen delivery, and reduced humoral immunity. Secretion of trehalase that is essential for chitin synthesis and the release of hypoxia up-regulated protein to ameliorate oxygen deprivation help ensure normal transition from larva to pupa. Proteins released by dermal secretory cells at this last molt could supplement the diminished immune defenses mediated by fat body and hemocytes at the end of larval life. Additional immune defenses provided by dermal secretory cells could help ensure a safe transition during a period of increased vulnerability for the newly molted pupa with its soft, thin cuticle and reduced mobility. Developmental changes at the larval (L)-pupal (P) transition showing four different levels of biological organization: organism (aL,aP), dermal organ (bL,bP), dermal secretory cell (cL,cP), and dermal secretory cell proteins (dL,dP). [Display omitted] • Dermal secretory cells abruptly expel their protein contents into the hemocoel. • Some secreted proteins function in immunity. • Trehalase secretion is associated with increased chitin synthesis at molt. • Secretion of hypoxia protein at molt occurs as oxygen demands increase. • Most proteins secreted at larval-pupal molt differ from those secreted earlier. [ABSTRACT FROM AUTHOR]