LOCALIZATION OF CYTOCHROME-OXIDASE AND THE 2-METHYL BRANCHED-CHAIN ENOYL COA REDUCTASE IN MUSCLE AND HYPODERMIS OF ASCARIS-SUUM LARVAE AND ADULTS

Rabbit lung-derived third-stage larvae (L3) of Ascaris suum are aerobi c and cyanide sensitive but also contain many enzymes specific to anae robic pathways. To localize these enzymes, diaminobenzidine (DAB) stai ning for cytochrome oxidase (COX) and immunogold labeling for 2-methyl butyryl enoyl CoA reductase (ECR) were performed on sections of hypode rmis and muscle of adults and larvae of A. suum and visualized by tran smission electron microscopy. As predicted, adult hypodermal and muscl e mitochondria did not exhibit COX staining; however hypodermal and mu scle mitochondria of the L3 and fourth-stage larvae (L4) were DAB posi tive. In contrast, hypodermal mitochondria from the adult, L3, and L4 did not exhibit ECR immunoreactivity, whereas mitochondria from muscle of all 3 were ECR positive. These observations suggest that both the ECR and COX are colocalized in muscle mitochondria of the L3.