TRIMODAL FORMATION OF MICROBODIES AND ASSOCIATED BIOCHEMICAL AND CYTOCHEMICAL CHANGES DURING DEVELOPMENT IN BLASTOCLADIELLA-EMERSONII

Microbodies and microbody marker enzyme activities were monitored ultrastructurally and biochemically, respectively, in Blastocladiella emersonii from the time of zoospore encystment (when the single symphyomicrobody fragments into smaller microbodies), through exponential growth (when microbodies proliferate), to the time of zoosporogenesis (when microbodies coalesce to form a larger single symphyomicrobody once again). Catalase was demonstrated cytochemically in glutaraldehyde-fixed cells by using 3′,3′-diaminobenzidine at pH 9.5. The number of microbody profiles per cell thin section seemingly increased most rapidly between 9 and 15 h of growth. During this period, protein per cell also increased at the maximum rate, and numerous associations between microbodies and endoplasmic reticulum were seen. The microbody profiles measured between 0.29 and 0.38 μm throughout exponential growth (3 to 18 h). During this period, changes in activity per cell of mitochondrial and microbody enzyme markers roughly paralleled changes in protein per cell. The changes in microbody enzyme activities per cell, however, deviated from changes in protein per cell in two places: between 0 and 3 h, when isocitrate lyase decreased sharply, and between 18 h and spore cleavage, when malate synthase increased. The specific activities of two mitochondrial enzymes, fumarase and succinic dehydrogenase, fluctuated similarly during growth whereas the specific activities of the microbody enzymes, malate synthase and isocitrate lyase, differed substantially from one another. © 1979 Academic Press Inc. All rights reserved.