Extrolites of Wallemia sebi, a very common fungus in the built environment.

Wallemia sebi has been primarily known as a spoilage fungus of dried, salted fish and other foods that are salty or sweet. However, this fungus is also very common in house dust. The health effects of chronic exposure to mold and dampness are known to be associated with both allergens and various inflammatory compounds, including the secondary metabolites of building associated fungi and their allergens. IgE sensitization to W. sebi has been long reported from housing and occupational exposures. However, its allergens have not been described previously. Strains from food have been reported to produce a number of compounds with modest toxicity. Strains from the built environment in Canada produced a number of metabolites including the known compound walleminone and a new compound 1-benzylhexahydroimidazo [1,5-α] pyridine-3,5-dione which we call wallimidione. Based on an in silico analysis, wallimidione is likely the most toxic of the metabolites reported to date from W. sebi. We found that the primary human antigen of W. sebi is a 47 kDa excreted cellulase present in high concentrations in W. sebi arthrospores. This species is a basidiomycete and, unsurprisingly, the antigen was not found in extracts of other fungi common in the built environment, all ascomycetes.

Statistical and historical analyses of nations which deviate from the size-density law.

We examine nations which deviate significantly from the -2/3 size-density slope previously observed for the aggregated political subdivisions of 98 modern nations and previously derived from the theory of time-minimization. We correct Stephan's original list of deviant nations, demonstrate that all slopes more negative than -2/3 were due to the erroneous inclusion of cities in the original data sets, develop a theory to account for the less negative deviant slopes, and test the theory both through statistical manipulation of current data and through analysis of available historical data.