
Full text loading...
The presence and location of an acetolysis-resistant polymer (sporopollenin) in various fruiting structures of the cellular slime moulds were demonstrated. Macrocysts (giant cells with thick cell walls) formed by a mutant (MF-1) of Dictyostelium mucoroides 7 contained large amounts of sporopollenin in their walls. In contrast, microcysts (round, walled resting cells) of Polysphondylium pallidum ws-320 lacked sporopollenin, at least in a tight networked form. This difference in sporopollenin distribution seems to be at least partly related to a difference in the germination efficiency of the two types of cells. In Acytostelium irregularvsporum fruiting bodies, the acellular stalk was found to consist mainly of sporopollenin, but the spores lacked it in a tight networked form. Spores of Polysphondylium pallidum and P. violaceum contained sporopollenin in the wall region. All the above species belong to the class Dictyostelia. Fruiting bodies of Acrasis rosea, a member of the class Acrasea, lack a tight network of cellulose wall as well as sporopollenin. It is clear that slime mould sporopollenin shows unique distribution patterns depending upon cell type and species. The functional significance of sporopollenin is discussed, with special reference to the late developmental stages of slime mould cells.