A brief introductory exercise in the use of on-line databases to examine fungal genes and their products is described. Fungal genes make particularly good teaching models owing to their relatively simple eukaryotic structure and wide range of homologues in higher organisms including humans. An evaluation of students' reactions to the exercise is included.

Some fungi are found only in specific geographical regions. The human pathogen Paracoccidioides brasiliensis has only rarely been isolated in nature and incidences of infections are restricted to Central and Southern America. Most commonly infected individuals are not urban dwellers, but rather farmers and people living in mountainous areas. In addition, it is almost invariably males who are infected. The gender bias has been reported as between 10 - 20:1 males over females! A possible explanation for this astonishing and unique phenomenon is given below. P. brasiliensis is the causative agent of paracoccidioidomycosis, a human systemic mycosis for which the portal of entry of the fungus is via inhalation of air-borne propagules into the respiratory tract. After entering the host, the fungus converts spontaneously to its yeast form, a fundamental step for the successful establishment of the infection.

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.