with Macrae about luminosity and stated that at least three different gene mutations could lead to the loss of luminescence. They also reported that the maximum bioluminescence was found at 525 nm, and shifted to 528 nm in deeply pigmented fruit bodies. After intercontinental compatibility tests, Petersen and Bermudes suggested that bioluminescence and compatibility were independent since bioluminescence seemed to be geographically restricted. This suggested that the ability or potential to interbreed must have been preserved since separation of P. stypticus into geographically isolated areas. Function Several authors have suggested that the purpose of fungal bioluminescence is to attract arthropods to the fruit body to help disseminate spores. However, there has been no direct observation of this phenomenon. In many species, the mycelium is luminescent, but the fruit body is not, which argues against this hypothesis. Mycelial bioluminence may also function to attract animals that can potentially carry fungal spores in well-hydrated areas, as light emission from the mycelium is higher when it is hydrated. This would presumably increase the chance that spores would be deposited in an environment that is already optimal for growth. Basidiomycete mushrooms are known to be dependent on an adequate moisture supply for proper development. In species with a luminous mycelium, the mycelium would therefore have a dual function in performing the fungal translocation that permits transport of substances from the further environment back to the fruiting body, and in attracting disseminating vectors towards environments favorable for development of the species. Chemical basis In general, bioluminescence is caused by the action of luciferases, enzymes that produce light by the oxidation of a luciferin (a pigment). Several studies have evaluated the biochemical basis of light production in Panellus stipticus, and concluded that there is no specific fungal luciferase. The fungus was shown in 1988 to contain the sesquiterpene panal, which has a cadinene keto-aldehyde chemical structure. Later, two additional precursors were isolated, PS-A (1-O-decanoylpanal) and PS-B (1-O-dodecanoylpanal). If these compounds are treated with salt of ammonia or primary amines in the presence of iron(II), hydrogen peroxide, and a cationic surfactant, light is emitted by a chemiluminescence reaction, suggesting that panal and its derivatives are fungal luciferins, and that the chemiluminescence reaction is the cause of in vivo bioluminescence. In the fungus, the level of activity of the enzyme superoxide dismutase (SOD) appears to play a critical role in the amount of light emission. SOD quenches the