Isolation and characterization of the rodlet layer of Trichophyton mentagrophytes microconidial wall

Abstract

The rodlet layer of the microconidial wall of Trichophyton mentagrophytes was isolated and partially characterized. The purified microconidial walls were first extracted with urea (8 M), mercaptoethanol (1%), and sodium dodecyl sulfate (1%) followed by enzymatic digestion with glusulase (snail intestinal enzymes) and purified (1-*3)-,8-D-glucanase and chitinase. The purified rodlet layer was 15 to 30 nm thick and accounted for approximately 10% ofthe original wall weight. The pattern of rodlet patches, as revealed by electron microscopy of freeze-etched preparations ofthe isolated layer, was essentially the same as that observed on the intact microconidial wall. The rodlet layer was found to be resistant to most of the common organic solvents, cell wall lytic enzymes, mild acid treatments, and surface-active agents, but was solubilized in boiling 1 N NaOH with concomitant disorientation of the rodlet patterns. A melanin or melanin-like pigment appeared to be intimately associated with this rodlet layer and was solubilized during a hot-alkali treatment. Protein (80 to 85%) and glucomannan (7 to 10%) were the major components of the rodlet layer. The rodlet layer did not contain any appreciable amounts of lipid or phosphorus.

Differences in microfibrils in the walls of Agaricus bisporus secondary mycelium

“…lb). These individual fibres seem to be similar to the rodlets reported previously in the walls of the yeast phase of Paracoccidiodes brasiliensis [10], hyphal walls of Schizophyllum commune [9], microconidial walls of Trichophyton mentagrophytes [11] and spore walls of A. bisporus…”

Hydrophobins: the protein-amphiphiles of filamentous fungi

“…Rodlet layers had, however, been described on fungal structures before any systematic study of hydrophobins. Characterization of these layers had shown many properties similar to those later described for some hydrophobins, such as being highly resistant to attempts to dissolve them by chemicals [54]. The connection between hydrophobins and rodlets was made by studying hydrophobin deletion mutants [26][27][28].…”

Ultrastructural Studies in Lichens

“…Structurally similar surface layers have been observed on the cell walls of hyphomycetes and the hymenial layer in basidiomycetes (summarized by Honegger, 1984), in cotton fibres (Ryser, Meier & Holloway, 1983;Yatsu, Espelie & Kolattukudy, 1983;Ryser & Holloway, 1985) and at the poUen-stigma interface in angiosperms. In conidia this surface layer is composed of proteins (Hashimoto, Wu-Yuan & Blumenthal, 1976;Beever, Redgwell & Dempsey, 1979) or proteins and lipids (Cole & Pope, 1981). Beever & Dempsey (1978) demonstrated that the surface layer of conidial cell walls renders these spores water-repellent.…”