title: Hyphal walls of isolated lichen fungi: autoradiographic localization of precursor incorporation and binding of fluorescein-conjugated lectins.
abstract: The hyphal walls of three mycobionts, isolated from the lichens Xanthoria parietina, Tornabenia intricata and Sarcogyne sp. were investigated by two techniques: microautoradiography of fungal colonies exposed to radioactive carbohydrate precursors: and binding, in vivo, of fluorescein conjugated lectins to hyphal walls of such colonies. N-[3H] acetylglucosamine was readily incorporated into tips, young hyphal walls and septa of the three mycobionts and the free-living fungus Trichoderma viride, but not into Phytophthora citrophthora, indicating that chitin is a major component of the mycobionts' hyphal walls. All three mycobionts, but neither of the free-living fungi, incorporated [3H] mannose and [3H] mannitol into their hyphal walls. Fluorescein-conjugated wheat germ agglutinin was bound to the hyphal walls of the three mycobionts and T. viride, but not to the walls of P. citrophthora; the binding pattern was similar to the grain pattern obtained in autoradiographs after short N-[3H]acetylglucosamine labelling. As wheat germ agglutinin binds specifically to chitin oligomers, the lectin binding tests further confirmed that chitin is a mycobiont hyphal wall component. Binding characteristics of several fluorescein-conjugated lectins to the three mycobionts indicated that this technique can yield useful information concerning the chemical composition of hyphal wall surfaces.
mesh_terms: D000117:Acetylglucosamine / Q000378:metabolism; D001665:Binding Sites; D050260:Carbohydrate Metabolism; D002473:Cell Wall / Q000378:metabolism; D002686:Chitin / Q000096:biosynthesis / Q000378:metabolism*; D037102:Lectins / Q000378:metabolism*; D008011:Lichens / Q000378:metabolism* / Q000648:ultrastructure; D010838:Phytophthora / Q000378:metabolism; D014242:Trichoderma / Q000378:metabolism
chemical_list: D037102:Lectins; D002686:Chitin; D000117:Acetylglucosamine