Occurrence, characterization and development of two different types of microbodies in the nematophagous fungusArthrobotrys oligospora

The occurrence of microbodies in different cells of the nematophagous fungus Arthrobotrys oligospora has been investigated. In the predacious phase this organism forms complex 3-dimensional network traps. Mature trap cells generally were crowded with “special” microbodies which possessed an electron dense matrix and were surrounded by a membrane of approx. 9 nm. These organelles developed during the early stages of trap formation and were derived from specialized regions of the endoplasmic reticulum. Cytochemical staining experiments revealed that the electron-dense microbodies contained catalase and d-amino acid oxidase and thus must be considered peroxisomal in nature. Electron-dense bodies were absent in normal vegetative cells of the fungus. These cells contained “normal” microbodies which developed from each other by the separation of small organelles from mature ones. As in yeasts, the metabolic function of these latter organelles was dependent upon environmental conditions.