Discoidin I and discoidin II are localized differently in developing Dictyostelium discoideum.

The distribution of discoidin I and discoidin II, developmentally regulated lectins in Dictyostelium discoideum, was determined immunohistochemically at various stages of development. Discoidin I was first prominent as focal clumps in aggregating cells, then accumulated on the surface of aggregates and around them. Discoidin II became prominent later and ultimately localized in what appear to be prespore vesicles. The results indicate that discoidin I and discoidin II have different and possibly multiple functions.

Elemental sulfur: accumulation in different species of fungi.

Sulfur, in elemental form, is present in several fungi especially in self-inhibited and resting structures such as dormant spores and sclerotia. The possible importance of sulfur in fungal spore dormancy is discussed.

Localization of chitin in the cell wall of Candida albicans by means of wheat germ agglutinin. Fluorescence and ultrastructural studies.

Cytochemical localization of wheat germ agglutinin binding sites in the cell wall of Candida albicans was investigated with fluorescence and electron microscopy. Various analytical techniques were employed in order to obtain a good penetration of the cytochemical markers, glycosylated horseradish peroxidase or glycosylated ferritin. In blastospores sectioned by cryostatic methods, a weak and continuous labelling of the blastospore periphery was observed with peroxidase, whereas bud scars and inner cell wall areas were labelled with ferritin. Following enzymatic treatment with pronase whose efficiency was followed by the periodic acid-thiocarbohydrazide -- Silver proteinate technique, the inner cell wall layers of bud are strongly stained with both fluorescein and the reactions products of peroxidase. After pronase-chitinase treatment, fluorescence was observed only in the mother cell wall. Finally, ultrathin glycol methacrylate sections showed a labelling both in inner and outer layers. All these results suggest that chitin was essentially distributed in the inner wall layers near the plasmalemma and in a smaller amount in outer wall layers. On the basis of the present findings, a hypothesis of wall assembly is proposed.

Visualization of exocellular lectins in the entomopathogenic fungus Conidiobolus obscurus.

We demonstrated the presence of lectins binding to glucose and N-acetylglucosamine on the surface of Conidiobolus obscurus spores by using glycosylated serum albumins substituted with fluorescent dyes and colloidal gold. The role of these exocellular lectins was examined in relation to the adhesion of the fungal spores to their host insect and the pathogenicity of the fungus.

Separation of mycotoxin-containing sources in grain dust and determination of their mycotoxin potential.

Two distinct reservoirs of mycotoxins exist in fungal-infected cereal grains--the fungal spores and the spore-free mycelium-substrate matrix. Many fungal spores are of respirable size and the mycelium-substrate matrix can be pulverized to form particles of respirable size during routine handling of grain. In order to determine the contribution of each source to the level of mycotoxin contamination of dust, we developed techniques to harvest and separate mycelium-substrate matrices from spores of fungi. Conventional quantitative chromatographic analyses of separated materials indicated that aflatoxin from Aspergillus parasiticus, norsolorinic acid from a mutant of A. parasiticus, and secalonic acid D from Penicillium oxalicum were concentrated in the mycelium-substrate matrices and not in the spores. In contrast, spores of Aspergillus niger and Aspergillus fumigatus contained significant concentrations of aurasperone C and fumigaclavine C, respectively; only negligible amounts of the toxins were detected in the mycelium-substrate matrices of these two fungi.

Fatty acids and sterols of Cronartium fusiforme basidiospores.

The hydrocarbons, fatty acids, and sterols of Cronartium fusiforme basidiospores were examined by gas chromatography and mass spectrometry. Trace quantities of aliphatic hydrocarbons were detected, but these were probably not fungal products. Principal nonsubstituted fatty acids were palmitic (11.7%), linoleic (17.2%), and linolenic (16.1%) acids; the predominant acid was 9,10-cis-epoxyocta-decanoic acid (40.7%). Four sterols were detected, three of which were identified as stigmast-7-enol (57.6%), stigmasta-5, 7-dienol (22.7%), and ergost-7-enol (16.0%). The fourth sterol (4%) is a C28 diene. Lipids of the aeciospores and basidiospores of C. fusiforme are compared.

Characterization of exposure to molds and actinomycetes in agricultural dusts by scanning electron microscopy, fluorescence microscopy and the culture method.

Air samples from 79 farms with 10(5) to 10(11) microorganisms/m3 were analyzed by scanning electron microscopy (SEM), fluorescence microscopy (FM), and the culture method. The total exposure to microorganisms (particularly actinomycetes) was underestimated when assessed as colony-forming units (cfu). The average cfu count was one-sixth of the total count according to SEM or FM, and the individual variability was great. This occurrence was partly explained by the aggregation of spores. Single spores accounted for 2-65% of all spores in 35 samples. There was an average of three spores/particle, and 93 (range 67-100)% of the spores were single or in aggregates of respirable size. Aggregation was more pronounced for actinomycetes and at high spore counts. Actinomycetes and bacteria could not be distinguished by FM. Bacteria (other than actinomycetes) were not detected by SEM, yet the total count of microorganisms was similar for FM and SEM. Most particles were spores from actinomycetes and fungi of the genera Aspergillus or Penicillium.

[Fungal spores in the atmosphere at Besançon, France: seasonal and annual variations during 1988 and 1989]. / Les spores fungiques dans l'atmosphère de Besançon, France: variations saisonnières et annuelles au cours des années 1988 et 1989.

Airborne spora in the atmosphere of Besançon were weekly determined, searching links between appearance of species and seasonal allergies. By comparison of the results of the two years, it is easy to see many variations. At first, the number of colonies collected is very different, 2,990 colonies in 1988, 9,841 in 1989. During 1989, some genera are present in greatest quantities. It is the case of Cladosporium and Epicoccum in summer and Aspergillus in autumn. For the allergologists, Alternaria, very abundant during 1989, is perhaps the outstanding incident, this genus being considerated as very allergenic.

An aerobiological survey of allergens in al Khobar, Saudi Arabia.

A nationwide aerobiologic study is in progress in Saudi Arabia using Burkard 7-day volumetric spore traps to determine the major airborne allergens and their seasonal patterns. Eights months readings have been completed at Al-Khobar, an important coastal city on the Arabian Gulf. Pollen levels showed a double season. An autumnal peak reached its maximum in October rising sharply from the low summer values before falling during the short winter then rising again in springtime. Both local and imported flora were represented with chenopodiaceae, grasses and Ambrosia as the most common botanical groups, identification of the most significant individual species is still in progress. Fungal spores also show distinctive seasonal patterns. In descending rank order from the most common genera were Cladosporium, Ustilago, Alternaria, with Chaetomium and Ulocladium as consistent but minor components. Basiodiospores and Ascospores represented less than 10% of the total spore population, indicative of the dry nature of the climate. Desert dust added an important irritant to the Saudi atmosphere but a major contaminating factor to the aerobiological material being analysed.

[Pigment and antibiotic substance contained in the spores of Actinomyces streptomycini B-6]. / Pigment i antibioticheskoe veshchestvo, soderzhashcheesia v sporakh Actinomyces streptomycini B-6

The antibiotic activity and fractional composition of the supernatant of the homogenate of Actinomyces streptomycini B-6 spores were investigated. The homogenate supernatant was of yellow colour and showed antibiotic activity when used as the test-organism of the culture St. aureus 209. The antibiotic activity was associated not with the homogenate pigment but with the colourless substance referring to streptomycins which was contained in spores.