RIGHT AND LEFT-HANDED HELICITY OF CHITIN MICROFIBRILS IN STIPE CELLS IN COPRINUS-CINEREUS

Chitin microfibrils are a major component of the walls of stipe cells of the mushroom Coprinus cinereus. They occur as shallow helices, which may be right- or left-handed, with about two thirds being left-handed. The sense of the helicity is constant throughout one cell, but cells with both senses are found in the same stipe. This shallow helicity is the same in stipe cells before and after rapid elongation, i.e. the elongation process must involve insertion of new microfibrils between existing ones, with no angular rearrangements as are seen in some other elongating systems. Models are proposed for the ontogeny and elongation of the helical wall structure. Stipe cell walls of an elongationless mutant show the same helicity of microfibrils as strains with normal elongation, before and after fruit body maturation.