Purification and chemical characterization of the rodlet layer of Neurospora crassa conidia

Abstract

The rodlet layer of Neurospora crassa macroconidia has been purified and chemically characterized. Sheets of rodlets were released from the conidial surface by vigorously shaking conidia in water. Conidia were removed by filtration and low-speed centrifugation, and the rodlets were recovered from the supernatant by high-speed centrifugation. The rodlet pellet comprised 1.9% of the initial dry weight. Chemical analysis was hampered by the insolubility of the rodlets. They were not solubilized by heating in various protein-denaturing buffers and were only partially dissolved by heating in 1 M NaOH at 100°C for 5 min. Nevertheless, they were found to be largely composed of protein (91%, based on total nitrogen). The major amino acids in acid hydrolysates were aspartic acid, glycine, serine, alanine, half-cystine, and valine. Glucosamine was not detected in acid hydrolysates. The sulfur content was 2.5%, and this could be accounted for in half-cystine and methionine. Carbohydrate comprised just over 2%. The phosphorus content was 0.21%, of which less than one-third was accounted for in phospholipid. The total fatty acid content was 1.0%, most of which could be accounted for by the fatty acids of the phospholipids. 1063 on August 2, 2020 by guest

rodletless mutants of Aspergillus fumigatus

“…Recent experiments have even shown that the purified hydrophobin Sc3 from Schizophyllum commune can form rodlets in vitro (25). These results are in agreement with those of previous biochemical studies which showed that the rodlet layer is composed mainly of proteins (4,8). However, no biochemical analysis of the Aspergillus rodlet layer has been done.…”

Surface properties of the conidiospores of Phanerochaete chrysosporium and their relevance to pellet formation

“…However, the conidiospores of P. chrysosporium INA-12 are cream colored, and melanin is thus not expected in large amounts. Although fatty acids and alkanes were extracted from the spore walls of different fungi, their concentrations were only a few percent (5,13,14) and not up to 30 to 40% as estimated for the conidiospores of P. chrysosponum. This points to the importance of distinguishing bulk composition and surface composition, with the latter being made accessible by XPS.…”

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.…”