Jc. Pendland et al., LAMININ-BINDING SITES ON CELL-WALLS OF THE ENTOMOPATHOGEN NOMURAEA-RILEYI ASSOCIATED WITH GROWTH AND ADHERENCE TO HOST TISSUES, Mycologia, 86(3), 1994, pp. 327-335
The entomogenous hyphomycete Nomuraea rileyi replicates by budding or
septation of yeast-like hyphal bodies in the hemocoels of host Spodopt
era exigua (beet armyworm) larvae. Hyphal bodies are not recognized by
host hemocytes and circulate freely in the hemolymph. Approximately 8
8 hours postinjection with 5 x 10(3) hyphal bodies per larva, the hyph
al bodies begin to form germ tubes which have the ability to attach to
hemocytes and other host tissues, e.g., fat body. Immunofluorescence
studies showed that laminin, a common component of the extracellular m
atrix in vertebrates and invertebrates, binds to germ tubes but not to
hyphal bodies. Binding to germ tubes is saturable, and the major bind
ing site, as indicated by Western blots of cell wall extracts, is appa
rently a mannoprotein with a molecular mass of 76 kilodaltons. Immunoe
lectron microscopy revealed that laminin binds to the fibrillar sheath
covering the germ tube wall. Laminin also binds to conidia but not to
conidial germ tubes. The significance of the differential binding of
laminin to N. rileyi surfaces during morphogenesis of the fungus as re
lated to recognition by host hemocytes and attachment to host tissues
is discussed.