| Abstract: | Microbodies containing bipyramidal crystalline nucleoid inclusions occur within every cortical cell in roots of Yucca torreyi. Reaction product deposition attributable to catalase, glycolate oxidase, and urate oxidase activities are cytochemically localized to Yucca root microbodies and classifies them as unspecialized peroxisomes on the basis of their enzyme complement and tissue origin. Crystalline nucleoids do not stain for glycolate or urate oxidase activities, appearing as negatively-stained inclusions, but are apparently reactive for catalase activity. Development of unspecialized peroxisomes in Yucca roots is consistent with all evidence for glyoxysome and leaf-type peroxisome biogenesis from ER. Dilated ends of ER cisternae accumulate cytochemically detectable glycolate oxidase activity. After considerable dilation, paracrystalline precursors to nucleoids form within the bulge, and the inclusion enlarges to comprise the majority of peroxisomal volume. Peroxisomes that are not attached to ER are observed with high voltage electron microscopy and in serial thin sections, implying that eventually the budding peroxisomes are vesiculated. The functions of these unspecialized peroxisomes are suggested based upon cytochemical detection of their partial enzyme complement and their spatial and developmental timing relationships within developing Yucca root cortical parenchyma cells. |
