In contrast to the cultivated mushroom (Agaricus bisporus (J. Lange) Imbach) which was first cultivated in the early 18th century in France, the famous Shii-take mushroom (Lentinula edodes (Berk.) Pegler) was cultivated in China centuries earlier, before being developed in Japan and extensively exported throughout the world. Other common names include the Oakwood mushroom, Japanese forest mushroom, Black mushroom, and Pasania. It is a mushroom long valued for both a unique flavour and as a medicinal tonic, for even in the Ming Dynasty (1368 – 1644 CE) it was claimed to be a general stimulant, curing colds, increasing blood circulation and lowering blood pressure.

One indication that a disease is prevalent in the general population is when it appears in literary offerings, is depicted in paintings by the old masters, and when it is given a colloquial name that bears no resemblance to the causative organism. Dermatophyte or ringworm infections have achieved this notoriety with the ignominious epithets of ‘athlete's foot’ and ‘jock itch’ being applied to infection of various body parts. Although not life-threatening, superficial mycoses due to dermatophyte fungi have been amongst the most communicable diseases in the population since antiquity and have considerable social and health-economic implications.

This issue of the Mycologist contains four contemporary reviews of topical issues in the field of medical mycology – a branch of mycology that has been fuelled by the urgent need to discover new classes of antifungal drugs and which has benefited from the injection of new information from genome sequencing of key pathogens. These four vignettes are not intended to provide a coherent overview of medical mycology, but instead illustrate why that area of mycology is enjoying a period of investment, progress and academic excitement. The reviews are presented by four scientists who are the foremost authorities in their respective fields. They focus on drug discovery and drug resistance, and on recent advances in our understanding of the biology of the two major fungal pathogens of humans – Candida albicans and Aspergillus fumigatus.

‘Geomycology’ can be defined as the impact of fungi on geological processes, including the alteration and weathering of rocks and minerals, the accumulation of metals and their role in nutrient cycling and influence on proliferation of microbial communities in mineral substrates. Although many studies on microbial interactions with minerals have been published in recent years, the main focus of geomicrobiology has been on prokaryotes. Recently, it has become apparent that epi- and endolithic fungi comprise a significant component of the microflora in a wide range of rocks including siliceous types (silica, silicates and aluminosilicates), sandstone, granite, limestone, marble and gypsum. However, to date little is known about their in situ growth patterns or biogeochemical roles in such an environment. The aim of this article is to highlight our recent work on the biogeochemical roles of fungi inhabiting limestone (CaCO3) and dolomite (CaMg(CO3)2) rocks and to emphasise the importance of fungi as agents of geological change.

Names of fungi

1. Sclerotinia curreyana (Berkeley ex Currey) P. Karsten = Myriosclerotinia curreyana (Berkeley ex Currey) Buchwald; conidial state Myrioconium Sydow

2. Sclerotinia Fuckeliana (de Bary) Fuckel = Botryotinia fuckeliana (de Bary) Whetzel; conidial state Botrytis cinerea Persoon ex Fries

3. Sclerotinia fructigena (Persoon) Schröter = Monilia fructigena Honey ex Whetzel; conidial state Monilia fructigena (Persoon) Eaton

Introduction: Features of interest

Members of the Sclerotiniaceae are plant pathogens characterized by stalked apothecia with inoperculate asci. Apothecia arise from stromata, e.g. sclerotia which are formed on or in the tissue of the host plant. The apothecial state and the type of stroma are typical and taxonomically relevant features of the Sclerotiniaceae, and the family has been supported and delimited by DNA sequence data (Carbone & Kohn, 1993; Holst-Jensen et al., 1997a,b).

The majority of the 22 primate species known to eat fungi spend less than 5% of their feeding time doing so. The Goeldi's monkey (Callimico goeldii), a small South American primate, devotes up to 63% of its feeding time to the consumption of Auricularia auricula, A. mesenterica, Ascopolyporus polyporoides and A. polychrous. This may be as much as 6.1kg/animal/year of fresh weight of fungus consumed by an animal weighing half a kilogram; in comparison, the average person in the U.S.A. consumes 1.9 kg/person/year of fresh weight of mushrooms. The nutritional benefits of mycophagy appear to be relatively few, but need to be investigated further. Mycophagy by Goeldi's monkeys may be a strategy for reducing feeding competition during the dry season and likely affects the monkeys' home range size and distribution pattern.

Free-living nematodes, commonly known as eelworms, eat bacteria in the soil and may succumb to infection by delicate endoparasitic fungi. In the wild these fungi are host-dependent and infect nematodes with small unicellular spores that either lodge inside the nematode following ingestion, or adhere to the nematode cuticle. Some endoparasites, such as Drechmeria coniospora and Harposporium leptospira, are readily isolated, ubiquitous species, infecting common soil nematodes in a variety of substrates. Others, like the elusive Plesiospora globosa, are seldom seen because they are host-specific for rarer species of nematode occurring in specific habitats.

Since the 1950s, antifungal drug discovery has identified three classes of natural products (griseofulvin, polyenes and echinocandins) and four classes of synthetic chemicals (allylamines, azoles, flucytosine and phenylmorpholines) with clinical value against fungal infections. For life threatening fungal disease, the polyene amphotericin B is still a common choice despite toxic side-effects. The azoles remain the most widely used group of anti fungals active against a wide range of mycoses, benefiting from creative chemistry to boost their effectiveness. More recently, the echinocandins show great promise, with caspofungin licensed for clinical use in 2002 and two other molecules close to registration. New advances in molecular genetics afford the promise of revealing new antifungal targets, together with new agents to inhibit those targets specifically.

Fungi can be found in almost any environment, and play important roles in ecosystem processes such as nutrient cycling and degradation. Despite their importance, the vast majority of fungi have not yet been isolated and identified. Due to the difficulties inherent in culture-based methods, fungal ecologists have turned to community fingerprinting techniques, which utilise signal molecules to profile the fungal members of an environmental sample without culturing. Commonly used signal molecules include chitin, ergosterol, membrane lipids and nucleic acids. Several DNA-based fingerprinting methods have been successfully applied to fungal communities, including D/TGGE (denaturing/temperature gradient gel electrophoresis), SSCP (single-stranded conformational polymorphism), RISA (ribosomal intergenic spacer analysis), and T-RFLP (terminal restriction length fragment polymorphism). These techniques allow the fungal ecologist to rapidly profile fungal populations in an ecosystem, without the need for laborious culturing or cloning.

Aspergillus fumigatus is the most common and life-threatening aerial fungal pathogen, especially among immunocompromised hosts. Understanding the pathobiology of this pathogen requires investigations both to characterise the immunosuppressive status of the phagocytic cells that usually kill the fungus in the immunocompetent host, and to identify fungal virulence factors that either promote the resistance of conidia to innate immunity or stimulate mycelial growth in the lung parenchyma. Recent findings are presented in this review and show how little we know of the interactions between host and pathogen. Now the genome of A. fumigatus has been sequenced, transcriptome/ proteome-based studies should disclose the multiple facets of A. fumigatus pathogenicity.

Fomitopsis officinalis (Vill.: Fr.) Bondartsev & Singer (Laricifomes officinalis) has a holarctic distribution in three large areas: West-Europe, North America, Ural-Siberia, and some small populations in Morocco (Maire, 1914; Malençon, 1955), China (Dai, 2000), Japan and Korea (Gilbertson & Ryvarden, 1986). Undoubtedly, the European as well as the West-Siberian populations are relicts, like their host populations, especially Larix spp. Branke (1896) suggested that the relict localities of F. officinalis on Larix deciduas Mill. in Poland can be recognized as evidence of continuous larch forest occupying large parts of the Europe during cold post-glacial periods. At present, the species is most common in Siberia from the foothills of the Ural Mountains to the shores of the Pacific Ocean (Murashkinskij, 1939; Bondartsev, 1953; Lyubarskij & Vassiljeva, 1975; Mikhaleva, 1993; Mukhin, 1993). It is rare also in North America (Overholts, 1953; Gilbertson, 1980).

The mycoparasite Krieglsteinera lasiosphaeriae Pouzar was first invalidly and illegitimately published by Arnaud (1951) as Jacobia conspicua from a collection near Paris. Although he thought that the sporophores resembled basidia, he described it as a hyphomycete (characterized by the large clamp-connexions) on the basis of the successive spore production. Pouzar (1987) later collected this fungus from Czechoslovakia and Poland and determined that the sporogenous branches described by Arnau were actually basidia. He appropriately redescribed it as a heterobasidiomycete renaming it Krieglsteinera lasiosphaeriae Pouz. after the German mycologist, J. Krieglsteiner. At the same time it was placed in its own family, Krieglsteineraceae, which is now considered a synonym of Platygloeaceae in the Urediniomycetes (Kirk et al., 2001). Pouzar believed that K. lasiosphaeriae was endangered and should be included in the red data book of Central European mycota owing to the rapid decrease of its host caused by air pollution. However, since then it has been found in Denmark (Læssoe & Lange, 1998) and is now reported here for the first time from England, Norway, Russia and the United States. Krieglsteinera lasiosphaeriae is probably much more abundant than previously thought, but is infrequently observed due to its cryptic nature.

Sometimes progress in mycology is so significant that it contributes to understanding in the wider scientific arena. To reflect this, an ad hoc series of articles will be published in the Mycologist outlining examples of when this has occurred. This, the first of these articles, examines work by Katinka and co-workers who have published a summary of findings about the genetic code (genome sequence) of the fungal parasite Encephalitozoon cuniculi (Nature 414: 450-453; 22/11/2001). Katinka et al. found that although fungi are complex organisms, the cellular machinery required to make a fungus can be very simple.

The study of filamentous fungi can be difficult through experimental means alone due to the complexity of their natural growth habitat (e.g. soils) and the microscopic scale of growth (e.g. tip vesicle translocation and hyphal tip extension). Mathematical modelling provides a complimentary, powerful and efficient method of investigation. In this article, earlier mathematical models are briefly reviewed, before an overview of the construction and resultant predictions of a new model for fungal growth and function is given. Model predictions are compared to experimentally obtained data, giving new insight into the complex interaction between the developing mycelium and its environment.

Recently, it was demonstrated that Candida albicans contains mating type genes. Since that discovery, it has been demonstrated that the majority of strains contain both a and "[agr ]" a genes, that a minority are homozygous for a or "[agr ]" and can undergo fusion, and that the cytological stages of fusion and zygote development are similar to the stages of mating in Saccharomyces cerevisiae. However, it has recently been demonstrated that in order to mate, homozygous a and homozygous "[agr ]" cells must undergo phenotypic switching from the white to opaque phase, adding a developmental step to mating that might be related to pathogenesis.

The spine fungi, which grow on the trunks, branches and stumps of trees, produce strange but beautiful mushrooms. They belong to a genus called Hericium, and there are a number of species throughout the northern hemisphere. Amongst the best known are the ‘spine face’ (H. cirrhatum (Pers.: Fr.) Nikol.) which is branched with several, shell-shaped caps, and the ‘coral spine fungus’ (H. coralloides (Scop.: Fr.) Pers.) which lacks a cap but is highly branched and covered with small spines, up to 10 mm long. Although all the spine fungi are edible and generally delicious, most attention has been given to that known in China as the ‘monkey head’ (H. erinaceum Bull.: Pers.).

Morels and truffles differ widely in their form and behaviour. The morels resemble mushrooms to the extent that they have a cap borne upon a central stem, whilst the truffles form solid, round balls, which grow underground. These are the edible ascomycetes. Both morels and truffles represent some of the most highly prized edible mushrooms in the world.

The morels are sometimes referred to as the ‘truffles of the north’, but other popular names include ‘sponge’, ‘pine cone’, ‘corncob’, and ‘honeycomb mushroom’. They are the most popular of the springtime, edible fungi, usually occurring from late March through to mid-June, although each crop will survive only for a several days. Morels have a delicate flavour that can be overwhelmed during cooking, but delicious when eaten alone. They are normally prepared by frying in butter and can be preserved, with drying being the most popular method.

The behaviour of Suillia flies on basidiocarps of Hebeloma radicosum was studied in central Japan. Hebeloma radicosum is a peculiar fungus that fruits only on talpid mole middens, near the moles' nests. All insect species around selected basidiocarps of this mushroom species were observed, their behaviour studied, and identified in late October to early November 1992, and again briefly in 2001. During these periods, Suillia flies were seen on the basidiocarps, while other insect species were rarely observed. Usually one Suillia fly (male) occupied one basidiocarp and prevented other conspecifics from occupying the same basidiocarp. This appeared to be pre-mating territorial behaviour. Larval stages of Suillia are known to be mycophagous, and the territorial behaviour is presumably performed to defend oviposition sites. This is the first report from Asia on ecological aspects of Suillia flies.

Boletus roseolateritius is described as a new species from Mississippi, USA and is compared with similar taxa.