Molecular aspects of specific cell contact.

Complementary macromolecules were isolated from yeasts of opposite mating type. These cell-surface molecules neutralize each other as do antibodies and antigens. Both yeast factors are glycoproteins of low molecular weight. Other specific cell associations may be due to the interaction of such complementary macromolecules.

Lipids of the yeast Hansenula anomala.

An analysis of the free lipids of Hansenula anomala was performed. The main fatty acids obtained by saponification of whole cell crude lipids were palmitic, C18:1, C18:2 and C18:3 acids. In mitochondrial lipids the tri-unsaturated acid was present as traces. Fatty acid composition of each class of lipids was also determined. Phosphatidylcholine and phosphatidylethanolamine were the main phospholipids; phosphatidylserine, phosphatidylinositol and cardiolipin were also characterized. The most abundant sterols were ergosterol and lanosterol. An acetate of a 24-ethyl cholesterol was also isolated. Two glycolipids, a galactosyl diglyceride and a glucosyl ceramide were identified; concerning the galactosyl diglyceride, the content of C18:3 acid was higher than in other lipid classes. In the glucosyl ceramide, the main fatty acid was alpha-hydroxy C18:0 acid; C16:0, C18:1, C18:2 and C18:3 acids were present too. The long chain base was shown to be C18-phytosphingosine (4-hydroxy C18 sphinganine). Some similarities and differences with Saccharomyces cerevisiae are discussed.

Localization of chitin in algal and fungal cell walls by light and electron microscopy.

Chitin was visualized in cell walls after hydrolysis with potassium hydroxide and subsequent postfixation of the deacetylated polysaccharide (chitosan) in OsO4. Areas of chitin deposition appeared dark borwn by light microscopy and electron dense in the electron microscope. With this method, the presence of chitin was demonstrated in the cell walls of the green alga Pithophora oedogonia (Montagne) Wittrock and two fungi, Ceratocystis ulmi Buism. (C. Moreau) and Blastocladiella emersonii Cantino and Hyatt. Most of the chitin in P. oedogonia ws found in the crosswall disk and small amounts occurred in the outer longitudinal walls. The septal disk of C. ulmi also contained chitin, but significant amounts were present in the inner and outer regions of longitudinal walls as well. Chitin was present throughout the walls of B. emersonii. Small amounts of chitin were not easily demonstrated by this technique, but removal of chitosan by exposure to dilute acetic acid before osmium fixation disrupted cell wall integrity, suggesting that small amounts of the structural polysaccharide had been removed.

Ultrastructural localization of glycoconjugates in the fungus Ascocalyx abietina, the Scleroderris canker agent of conifers, using lectin-gold complexes.

Different glycoconjugates were revealed in the fungus Ascocalyx abietina (Lagerberg.) Schlaepfer-Bernhard, by using various lectin-gold complexes. N-acetylglucosamine, N-acetylgalactosamine, and D-mannose were specifically localized in cell walls of fungal cells. N-acetylneuraminic acid (sialic acid) and L-fucose were detected in structures corresponding to lipid bodies, whereas they were totally absent in the cell wall. This is the first report on the occurrence of sialic acid in fungi and of fucose in Ascomycetes. The great advantage of using lectin-gold complexes for ultrastructural localization of sugars in phytopathogenic fungi, as well as in studies concerning host-pathogen interactions, is discussed.

The nucleotide sequence of 5S ribosomal RNA from Schizosaccharomyces pombe.

The nucleotide sequence of 5S rRNA from the fission yeast, S. pombe, has been established by post labeling procedures combined with cataloging RNase T1- and A-oligonucleotides derived from unlabeled 5S rRNA. The sequence consists of 119 nucleotides without a modified base and shows more dissimilarities (at 38 positions) from that of S. cerevisiae than from that of humans (at 33 positions).

Isolation of furanoterpene-containing particles from Ceratocystis fimbriata-infected sweet potato root tissue.

Furanoterpene-containing particles were isolated by centrifugation on a discontinuous Ficoll density gradient from a homogenate of the non-infected tissue adjacent to the infected region of Ceratocystis fimbriata-infected sweet potato root tissue. The particles were recovered at a relatively high ratio in the 2% Ficoll fraction, in which there was no contamination by mitochondria and only little by endoplasmic reticulum judging from the distribution of the activities of their marker enzymes and electron micrographs. Each particle was enveloped in a single membrane, 7-10 nm thick.

Methylation and acetolysis of extracellular D-mannans from yeast.

Methylation-fragmentation analyses were conducted on a series of extra-cellular, yeast alpha-D-linked mannans representing six different structural types. D-Mannans of low degree of branching were produced by Hansenula capsulata strains and by species related to H. holstii, The former consisted primarily of (1 leads to 2)- and (1 leads to 6)-linked D-mannosyl residues; the latter, of (1 leads to 2)- and (1 leads to 3)-linked D-mannosyl residues. Although the remaining structural types were highly branched, each gave distinct methylation-patterns indicative of (1 leads to 6)-linked backbones to which are appended non-(1 leads to 6)-linked side-chains. Acetolysis studies were correlated with the methylation analyses, and the correlation demonstrated that each branched polymer possesses side chains of heterogeneous length.

Immunochemical studies on L-rhamno-D-mannans of Sporothrix schenckii and related fungi by use of rabbit and human antisera.

Antisera were prepared in rabbits against the human pathogenic yeast Sporothrix schenckii (strain 1099.12) grown at two different temperatures (25 degrees and 37 degrees). Precipitation and inhibition data showed that the former serum had a specificity directed against alpha-L-Rhap-(1 yields 2)-alpha-L-Rhap-(1 yields 3)-D-Man-(1 yields determinants, whereas the latter had a broad specificity in which alpha-L-rhamnosyl or alpha-L-Rhap-(1 yields 3)-D-Man- was the immunodominant structure. These results are consistent with data on the structures of the L-rhamno-D-mannans isolated from the organism grown at the two different temperatures. Human sera from patients with sporotrichosis were shown to have different specificities resembling the specificities developed in the rabbits. The rabbit antisera were also used to examine the cross-reactivity with L-rhamno-D-mannans from species of the genus Ceratocystis, which is reputed to include the ascigerous (perfect) state of S. schenckii. Polysaccharides from four species of Ceratocystis grown at 25 degrees reacted with the antisera in a manner resembling that of the L-rhamno-D-mannan from S. schenckii grown at 37 degrees. This is in accord with earlier data that showed that only S. schenckii, of the species studied, produces a polysaccharide with large amounts of alpha-L-Rhap-(1 yields 2)-alpha-L-Rhap-(1 yields side-chains when grown at 25 degrees.

Determination of the absolute configuration at C-20 and C-24 of ergosterol in Ascomycetes and Basidiomycetes by proton magnetic resonance spectroscopy.

Samples of ergosterol isolated from Saccharomyces cerevisiae, Neurospora crassa, and Agaricus sp., and commercial ergosterol all displayed identical proton magnetic resonance (PMR) spectra at 220 MHz. From the effects produced on the doublet for C-21 by epimerization at C-20 and C-24 in sterols of known configuration, the absolute configurations at these positions in ergosterol were determined. The data demonstrate that ergosterol from both Ascomycetes and Basidiomycetes is the same and that at C-20 and C-24, the two H-atoms are on the alpha-side of the asymmetric carbon atoms and that C-22 is trans-oriented with respect to C-13 about the 17(20)-bond.

Antibiotic activity of pyrenomycetes under submerged conditions.

Twenty-three pyrenomycete species were tested for antibiotic activity in submerged cultures. When they were screened against bacteria and fungi, 15 showed positive results. Among these, Eutypa acharii, Diaporthe pustulata, Melanconis flavovirens and Camarops microspora were quite promising against bacteria and/or fungi. An antibacterial antibiotic from Camarops microspora was partially purified and characterized.