| Summary: | Thesis (M.Sc.)--Memorial University of Newfoundland, 2003. Biology Bibliography: leaves 75-86. Integrins are transmembrane proteins involved in cell adhesion and signal transduction. This study reports findings on a possible integrin-like protein in an entomopathogenic fungus, Entomophaga aulicae. -- Extracts oi Entomophaga aulicae protoplasts contained a 71 kDa protein which cross-reacted with antiserum raised against a Bi-chicken-integrin. The inclusion of DTT in the cell extracts had no effect on the mobility of this protein indicating the lack of a significant number of sulfur-sulfur bonds. A combination of eight protease inhibitors was necessary to prevent protein degradation in order to obtain consistent results. Positive and negative controls supported these results. -- Using immunofluorescence microscopy, similar patterns of abundant peripheral patches of staining were detected at the periphery of the protoplast when probed with four different anti-integrin or anti-B-integrin like protein antibodies. Controls showed that staining of the periphery of the nucleus and staining of the nuclear "core" were non-specific. This conclusion is tentative however since we were unable to show characteristic integrin staining in positive controls of monkey kidney fibroblasts. In cell adhesion assays, there was no evidence to support the hypothesis that E. aulicae protoplasts attach to either a host insect cell line, or to the integrin-binding proteins, fibronectin and collagen. Future experiments using newly isolated protoplasts and cell lines derived from insect fat body may be more instructive. -- We conclude that while we have preliminary evidence for an integrin-like protein in E. aulicae, strong support for integrin in any fungus remains elusive.
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