Studies on Microperoxisomes V. Are Microperoxisomes Ubiquitous in Mammalian Cells?

Abstract

A variety of mammalian cell types has been studied by electron microscopy following incubation in a 3,3'-diaminobenzidine medium at pH 9.7 and containing a high H202 concentration. This medium visualizes the recently described anucleoid microperoxisomes as well as the nucleoid-containing peroxisomes. All 24 cell types contain 3, 3'-diaminobenzidinepositive microperoxisomes but none shows nucleoid-containing peroxisomes. The number of microperoxisomes within a cell varies greatly among different cell types. There are huge numbers in some cell types; in others microperoxisomes are common, few or rare. Such differences imply varying functional significance of these organelles in the metabolism of different cell types. Whether the endoplasmic reticulum (ER) is abundant or scarce or whether its membrane is studded with numerous ribosomes or not, ribosomes are lacking where the ER is connected to the microperoxisomes by slender channels. It may be presumed that molecular interchange occurs between these two organelles. Such interchange may occur between microperoxisomes, ER and lipid droplets, as previously suggested, and between zymogen granules of guinea pig pancreas and ER and microperoxisomes. Two rapidly growing malignant cell types were studied (HeLa and Novikoff hepatoma) and both show moderate numbers of microperoxisomes. of human jejunum (26), cells of the distal

Response of chemically induced hepatocytelike cells in hamster pancreas to methyl clofenapate, a peroxisome proliferator.

“…Peroxisomes are not exclusive cell markers for hepatocytes (3,14). However, the presence in hepatocytelike cells of four of the enzymes associated with peroxisomes namely, catalase, carnitine acetyltransferase, enoyl-CoA hydratase, and palmitoyI-CoA oxidizing system, the striking morphologic similarity of peroxisomes in these ceils to those in liver hepatocytes, and their almost identical quantitative response to a peroxisome proliferator as compared to normal liver cells, strongly support …”

Enzyme Histochemical and Ultrastructural Observations on the Liver of Teleost Fishes

“…The crista-and tubule-rich mitochondria of the hepatocytes of a few species, especially Corydoras, exhibit a markedly different ultrastructure in comparison with those of amphibians (WELSCH and STORCH, 1972) and mammals (NOVIKOFF and HOLTZMAN, 1970), in which the cristae are usually reduced and the matrix predominates.…”

“…In some species, e.g. in Corydoras, they possess a core, which in anurans was correlated with the enzyme allantoinase (VISENTIN and ALLEN, 1969) or urate oxidase in mammals (NOVIKOFF and HOLTZMAN, 1970). Since experimental data are apparently lacking on teleost liver cells, no definite statements can be made on the function of these organelles in this tissues; however, the suggestion of NOVIKOFF and others (1972) that in the mammalian jejunum microperoxisomes may play a functional role in lipid metabolism and transport may also apply to the lipid-rich liver cells of fish.…”

Transcription regulation of peroxisomal fatty acyl-CoA oxidase and enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase in rat liver by peroxisome proliferators.

“…Peroxisomes are ubiquitous cytoplasmic organelles, present in animal and plant cells, that contain enzymes capable of generating and degrading hydrogen peroxide (1)(2)(3)(4). In mammalian liver parenchymal cells, peroxisomes are few in number and appear insignificant in the overall cytoplasmic organization.…”