Electron microscopical localizations of ATPase

Using an in situ cytochemical staining technique, ATPase activity was localized within tissues with the electron microscope. Activity was seen in association with the axolemma, mitochondria and microtubules of neurones of the common garden snail, Helix aspersa, and the shore crab, Carcinus maenus. Using mammalian tissue, ATPase activity was demonstrated in association with the basement membrane of endothelial cells lining capillaries, nuclei, axolemma, tubular endoplasmic reticulum and microtubules of dendrites of the rat cerebral cortex.The localization of ATPase in association with neuronal microtubules was intensively investigated. Enzyme activity was preserved by I$ glutaraldehyde fixation but not by 2% or 3% glutaraldehyde. Heating to 70°C destroyed the enzyme localization. Omission of ATP or magnesium ions from the incubation medium prevented the localization of precipitation in association with microtubules. Chemical inhibitors, cysteine, sodium fluoride and ouabain, did not influence the precipitation in association with microtubules. The enzyme associated with neuronal microtubules showed a substrate specificity for ATP > GTP > CTP > UTP > ADP. The role of the microtubular ATPase and the possible mechanisms for the involvement of microtubules in axonal transport were discussed. The same in situ cytochemical staining technique was used to demonstrate ATPase within Tetrahymena vorax, a ciliated protozoan. The role of microtubules in the control of cilia motility and the maintenance of cell shape was discussed. Intracellular injection of electron dense markers, into single nerve cells of the snail sub-oesophageal ganglia and their examination under the electron microscope, were carried out to investigate the possible role of microtubules in the intra-axonal transport of material.