The Nucleoids of Rat Liver Cell Microbodies

Abstract

The nucleoids of microbodies of rat liver cells were isolated in a highly homogeneous and pure state, by treating the microbody-rich fraction, prepared from 10% Folyvinylpyrrolidone-0.25 M sucrose homogenate, with Triton X-100. Three treatments with 0.1% detergent were enough to render the nucleoids free from contamination with mitochondria, microsomes, lysosomes, and intact microbodies. Electron microscopically, the nucleoids were found to consist of parallel bundles of highly dense hollow tubules, the outer and inner diameters of which are approximately 150 and 50 A, respectively. Ten tubules are arranged around a longitudinal space 190 X 200 A in width. The nucleoids thus show a honeycomb appearance in the cross-plane and a parallel-packed structure in the longitudinal plane. Biochemically, the nucleoids were found to bear only urate oxidase among probably microbody-enzymes, and they might be the only cytoplasmic particles of rat liver cells in which the enzyme locates. Urate oxidase activity, on a unit protein basis, of the nucleoid preparation is approximately 380 times as high as that of the whole homogenate, and is almost comparable with that of a commercial type I enzyme preparation. No enzymes of mitochondrial, microsomal, and lysosomal origins were detected in the nucleoids. The fine structure of the nucleoids is described in detail, and a probable schematic diagram is presented.

Cytochemical Localization of Peroxidatic Activity of Catalase in Rat Hepatic Microbodies (Peroxisomes)

“…From a comparison of our electron micrographs with the model of microbody nucleoids proposed by Tsukada et al . (61), it appears that the substance of the nucleoids did not show any staining but that the lumen of the hollow tubules contained the reaction product . This finding emphasizes the intimate association of the nucleoids containing urate oxidase with the catalase which surrounds them.…”

“…In this figure the microbody has been sectioned perpendicular to the longitudinal axis of the crystalline nucleoid . Note the honeycomb appearance, which is due to the presence of the reaction product in the lumen of the tubules of the nucleoids (61) . (Section contrasted with lead citrate .)…”

“…The fine structure and enzyme content of the nucleoids of rat hepatic microbodies have been studied extensively (5,60,61) . Morphologically the nucleoids consist of parallel bundles of hollow tubules, which in cross-section have a honeycomb appearance and in longitudinal plane show a parallel packed, tubular structure (61) .…”

“…Morphologically the nucleoids consist of parallel bundles of hollow tubules, which in cross-section have a honeycomb appearance and in longitudinal plane show a parallel packed, tubular structure (61) . The only enzyme known to be associated with the nucleoids is urate oxidase .…”

Peroxisome degradation in mammals

“…The most conspicuous structural component of the peroxisome is a dense core, which has been described as crystalline, semicrystalline, crystalloid, or maltilamellated, mostly on the basis of electron microscopic images and is made up of regular striation with a honeycomb appearance (2). Biochemical analyses showed that the structure was made of urate oxidase (4,5). Peroxisome deficiencies participate in a variety of pathologies, including Zellweger syndrome.…”