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Ancestral lineages of arbuscular mycorrhizal fungi (Glomales).

Using new and existing 18S rRNA sequence data, we show that at least five species of glomalean fungi lie outside the previously defined families and diverged very early in the evolution of that group. These five fungi would have been missed by many previous ecological studies because their sequences are not well matched to available taxon-specific primers and they do not stain well with the standard reagents used for morphological analysis. Based upon spore morphology, these species are currently assigned to Glomus and Acaulospora, and two of the species are dimorphic, exhibiting spore stages of both genera. This suggests that dimorphic spores are the ancestral state for the order and that one or the other morphology was lost in various lineages. Our analyses also show that Geosiphon pyriforme, a symbiont with cyanobacteria, is not necessarily a sister group of the Glomales; instead, it may be derived from mycorrhizal ancestors.

DNA, Fungal↗

Detection and taxonomic placement of endophytic fungi within frond tissues of Livistona chinensis based on rDNA sequences.

The 5.8S gene and flanking internal transcribed spacers (ITS1 and ITS2) of the rDNA were amplified from total DNA extracted from frond tissues of Livistona chinensis with universal and fungal-specific primers. These amplified fragments were cloned and sequenced. Phylogenetic analysis based on the 5.8S gene sequences indicated that the six clone sequences obtained were of different origins. Five sequences, P1-9, P2-6, P4-4, P4-5, and P4-7, belonged to the fungi and one sequence, P3-2, belonged to the plants. P1-9 was inferred to belong to the Basidiomycota based on the phylogenetic analysis of the 5.8S gene sequences but could not be identified to lower taxonomic levels. Further identification of the other four fungal clones to lower taxonomic levels was attempted based on phylogenetic analysis and sequence comparison of both the conserved 5.8S gene and the variable ITS regions. The origin of P2-6 was identified to be Glomerella and its anamorph Colletotrichum, the origins of P4-5 and P4-7 were Mycosphaerella and its anamorph Cladosporium, and the origin of P4-4 was the Herpotrichiellaceae. The direct approach to detection and taxonomic placement of endophytic fungi within host tissue without the need for conventional in vitro culturing is discussed.

DNA, Fungal↗

Cytochrome P450 of fungi: primary target for azole antifungal agents.

Cytochromes of fungi are essentially similar to those of animals. Cytochromes of fungi constitute two electron transport systems occurring in mitochondria and the endoplasmic reticulum. The former system, called the respiratory chain, contributes to cellular respiration and ATP generation, whereas the later system, named the microsomal electron transport system, is responsible for biosynthesis of several cellular components. The oxidative metabolism of lanosterol, that is included in the biosynthetic pathway of ergosterol, is one of the important functions of the microsomal electron transport system, which is catalyzed by P450(14DM). Many azole antifungal agents avidly combine with P450(14DM) and inhibit the oxidative removal of C-32 (the 14 alpha-demethylation) of lanosterol. This inhibition causes depletion of ergosterol and accumulation of 14-methylsterols in the membrane of fungal cells. Such change in sterol composition disturbs membrane function and results in growth inhibition and death of the fungal cells. Accordingly, P450(14DM) is considered as the primary target for azole antifungal agents. Cytochrome P450, which mediates the 14 alpha-demethylation of lanosterol, is also present in mammalian cells. Mammalian cells contain various species of cytochrome P450 which are responsible for many important cellular metabolic functions. If azole antifungal agents inhibit mammalian cytochrome P450 too, their systemic use may result in potentially significant adverse reactions. The high selectivity of azole antifungal agents for fungal P450(14DM) will be necessary for their systemic application. Binding ability of an azole antifungal agent to P450(14DM) is predominantly determined by the substituent at N-1 of the azole group, and the substituent must interact with the substrate site of the cytochrome. Extensive modification of the N-1 substituents and the screening of newly developed compounds with respect to the selectivity to fungal P450(14DM) with some conventional methods will be necessary. For this project, a biochemical understanding of cytochrome P450 and other cytochromes is important.

Animals↗

Polyploidy in fungi.

There is evidence supporting a concept of polyploid evolution in a number of groups of fungi. These typically have dominant diploid phases in their life-histories. There are a number of reports of suspected polyploidy in other fungi, but these should be considered speculative at this time.

Ascomycota↗

Classification and taxonomy of fungi pathogenic for warm-blooded hosts.

The kingdom of fungi is described with emphasis on fungi pathogenic for warm-blooded hosts. The various growth forms of the most frequent causative agents of fungal infections are described and their classification based on characteristics of their sexual life cycle and on their DNA/RNA pattern is summarized in various tables.

Animals↗

Keratinophilic fungi isolated from soil of Italian parks in the province of Pavia.

Soil samples collected from 9 parks in the Italian province of Pavia were baited with hair and feathers for the isolation of keratinophilic fungi. The dominant species were the teleomorphs Arthroderma gypsea, A. uncinatum, Ctenomyces serratus and Aphanoascus fulvescens with their anamorphs. Among the other species isolated, Amauroascus mutatus, Gymnascella dankaliensis, Gymnoascus intermedius and Gymnoascus reessii were recorded. The distribution of these fungi is discussed and related to previous records.

Ascomycota↗

Visualization of mitotic chromosomes in filamentous fungi by fluorescence staining and fluorescence in situ hybridization.

Mitotic chromosomes of the plant pathogenic filamentous fungi Botrytis cinerea and Alternaria alternata were observed. Chromosomes prepared by the germ tube burst method were stained with the fluorescent dye 4',6-diamidino-2-phenylindole (DAPI) to yield figures with good resolution. Using this method, component chromosomes were clearly distinguished and the chromosome number could be determined. Fluorescence in situ hybridization (FISH) was also successfully applied to the specimens, revealing one ribosomal RNA gene cluster, or nucleolus organizer region (NOR) in the genome of each fungus. A long attenuated chromatid thread expanding from a condensed metaphase chromosome, which had been called a thread-like structure in B. cinerea, was proved to be an NOR. This is the first report of the successful application of FISH to the chromosomes of filamentous fungi.

Alternaria↗

Microscopic observations on the interaction of the mycoparasite Verticillium biguttatum with Rhizoctonia solani and other soil-borne fungi.

The mycoparasitic interactions of Verticillium biguttatum with Rhizoctonia solani and with a variety of other soil-borne fungi were investigated in dual cultures. V. biguttatum interacted with various soil fungi by appressed growth along the host hyphae and infrequent penetrations. Intracellular growth and subsequent sporulation, however, only occurred with R. solani, a few binucleate Rhizoctonia and Ceratobasidium spp., and Sclerotinia sclerotiorum. Effective mycoparasitism on sclerotia was restricted to those belonging to R. solani. Electron-microscopic observations revealed that V. biguttatum can penetrate the host cell with infection tubes. This process is probably mediated by enzymatic hydrolysis of the cell wall. Subsequently, trophic hyphae develop within the host cytoplasm, ultimately resulting in death of the host cell.

Host-Parasite Interactions↗

Fungi from otitis media of agricultural field workers.

Twenty four fungi were isolated from ear wax or otitis media of agricultural field workers, of which 18 are being reported for the first time from India. Direct observation, revealed the presence of hyphal fragments, spores of Alternaria, Bipolaris, conidial head of Aspergillus, smut teliospores and pollen. Spores of only four fungi, Alternaria humicola, Aspergillus niveus, Bipolaris spicifera and Fusarium moniliforme germinated in otitis media at 37 degrees C, and their germination was affected by relative humidity. Alternaria humicola and Aspergillus niveus appeared to be the causative agents of otomycosis, and otitis media is fungistatic in nature.

Agricultural Workers' Diseases↗

Distribution of keratinophilic fungi in animal folds in Kuwait.

Soil samples from seventeen animal herds (camels, goats, sheep, cows) were surveyed for the occurrence of keratinophilic fungi. Twenty four species related to eleven genera were recovered on defatted wool baits. Eleven Chrysosporium species were reported in the following order of dominance: C. keratinophilum, C. tropicum, C. indicum, C. queenslandicum, C. pannicola, C. carmichaelii, C. state of Arthroderma curreyi, C. zonatum, C. state of A. cuniculi and Chrysosporium state of Renispora flavissima. The Aphanoascus teleomorph of C. keratinophilum, C. indicum and C. tropicum were frequently reported in soils from cow and sheep folds. Scopulariopsis, Cephaliophora and Sepedonium, although not keratinolytic, were also recorded on wool baits of soils from cow herds which are slightly acidic. The frequency and distribution of these fungi are discussed in relation to animal species and the general ecological conditions of desert soils.

Animals↗

Keratinophilic fungi isolated from the air at Pavia.

The presence of keratinophilic fungi was revealed by sampling the air of Pavia (Italy) from March 1981 to February 1982. The species isolated were: Chrysosporium indicum , Geomyces pannorum var. pannorum , Microsporum gypseum, Myceliophtora vellerea and Trichophyton terrestre . Several filamentous fungi tolerating high levels of cycloheximide were also recovered.

Air Microbiology↗

Preservation of fungi in water (Castellani): 20 years.

Five-hundred ninety-four strains of fungi were studied. They were found being preserved with Castellani's method with distilled water during 1 to 20 years. 62% of the strains (n=368) did grow when subcultured and maintained their main morphological features. 90% of the 20 years old strains of different species were viable. It is argued that the technique of introduction of the strains into the water and their optimal condition will determine survival. The Castellani's method is recommended as easy, cheap and satisfactory for preservation of most species of fungi.

Fungi↗

Susceptibility of clinical isolates of fungi to saperconazole.

The in vitro activity of saperconazole against 228 strains of mycotic agents belonging to 48 species was investigated. Susceptibility testing was performed using a microtiter broth dilution method. Isolates of Candida albicans, C. tropicalis and Torulopsis glabrata showed distinct intra-species variation of susceptibility with MIC values ranging from 0.045 to 100 mg l-1. The drug was inhibitory for the dermatophytes at a relatively narrow range of concentrations, most isolates being inhibited at MIC 0.78 mg l-1. The strongest antifungal potency of saperconazole was exerted against clinical isolates of the genus Aspergillus (MIC 90% = 0.19 mg l-1). Concentrations up to 100 mg l-1 had no macroscopically recognizable effect on the growth of zygomycetous fungi (Mucor, Rhizopus, Syncephalastrum). Species of the genus Absidia with their good sensitivity are an exception. Justification of in vitro susceptibility testing of triazoles is discussed. In the author's opinion, MIC values can serve as an informative parameter showing the range of indications of these antifungals for treatment. It is concluded that saperconazole exhibits a very good activity against a broad spectrum of medically important fungi in vitro and can be considered a promising antifungal drug.

Antifungal Agents↗

Incidence of keratinophilic fungi in rice-field soils.

Soil samples from rice-fields, collected at monthly intervals, were analysed by baiting technique for the incidence of keratinophilic fungi. Nine species, among a total of 102 species isolated by various methods, were keratinophilic species (8.8%). These were recorded from 38 out of 45 samples collected. The distribution pattern of the different keratinophilic fungi and their significance are discussed.

Aspergillus fumigatus↗

In vitro sensitivity of environmental isolates of pathogenic dematiaceous fungi to azole compounds and a phenylpropyl-morpholine derivative.

The in vitro sensitivity (minimum inhibitory concentrations; MICs) of 42 environmental isolates of pathogenic dematiaceous fungi to 7 azole compounds, viz. thiabendazole, ketoconazole, miconazole, econazole bifonazole, Bay n 7133, Bay 1 9139 and phenylpropyl-morpholine derivative, Ro14-4767/002 was studied by an agar dilution method using Emmon's Sabouraud dextrose agar (ESDA) as the culture medium. The isolates of Fonsecaea pedrosoi, Cladosporium carrionii, Exophiala jeanselmei and Ramichloridium subulatum were most sensitive to bifonazole with mean MICs of 0.06 microgram/ml or less; Phialophora verrucosa had an MIC of 0.05 microgram/ml to ketoconazole and Ro14-4767/002, respectively. Ochroconis sp had an MIC of 0.025 microgram/ml to Ro14-4767/002 and Cladosporium tennuisimum 0.39 microgram/ml to ketoconazole. Econazole and thiabendazole also showed good antifungal activity. The fungi were relatively resistant to the more recently developed azoles, viz. Bay n 7133 and Bay 1 9139, the later failing to inhibit C. tennuisimum at a concentration of 100 micrograms/ml. The minimum fungicidal concentrations (MFC) of the drugs were mostly within 2 to 8 fold of the MICs.

Animals↗

Isolation of opportunistic fungi from bronchoalveolar lavage of compromised hosts in Isfahan, Iran.

In this study, bronchoalveolar lavage (BAL) specimens from 247 immunocompromised patients were investigated for the incidence of opportunistic fungi. In the direct examination and culture of the specimens, 5 (2.02%) of filamentous fungi and 55 (22.26%) yeasts were isolated and identified as follows: Aspergillus fumigatus (2), A. terreus (1), A. nidulans (1), Mucor sp. (1), Candida albicans (29), C. glabrata (3), C. Parapsilosis (1), Trichosporon beigelii (1), Candida sp. (13) and unknown yeasts (8). In addition, one strain of Nocardia asteroides and two strains of Streptomyces sp. were isolated.

Aspergillus↗

Isolation of keratinophilic fungi from the floor dust of Arab kindergarten schools in the West Bank of Jordan.

The keratinophilic mycoflora of floor dust of seventy two classrooms in 24 kindergarten schools (children aged 2-5) in the city of Nablus was studied using a hair-baiting technique. The study was aimed at the evaluation of extent of diffusion of keratinophilic fungi in this environment in relation to human presence and the age of children in order to determine their role and impact in the epidemiology of human dermatophytoses. Thirty three species were isolated. A large proportion of these species are either well-known human and animal mycotic agents or have been isolated frequently from human and animal lesions. These pathogenic and potentially pathogenic fungi comprised about 85.8% of all keratinophilic fungal isolates found in the classroom dust. The results of this investigation have also been discussed in respect to previous studies on human dermatophytoses in the West Bank of Jordan.

Arthrodermataceae↗