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PubMed1979

Changes in peroxisomes in preneoplastic liver and hepatoma of mice induced by alpha-benzene hexachloride.

Peroxisomes in hepatomas and hyperplastic preneoplastic liver lesions induced in mice by 500 ppm alpha-benzene hexachloride were examined histochemically and electron microscopically. Although most of the hepatomas were well-differentiated tumors and contained a considerable number of peroxisomes, the tumor cells did not respond to ethyl-alpha-p-chlorophenoxyisobutyrate with proliferation of peroxisomes. At the 16th week of carcinogen feeding, hyperplastic nodules appeared and advanced to further stages. A majority of the nodules showed a considerable number of peroxisomes and the inductive proliferation of peroxisomes. Within the nodules, foci of proliferation of the cells that showed no inducibility of proliferation of peroxisomes appeared. These cells proliferated further, replacing the most part of the nodules, and with this process hepatomas appeared to have been formed. No abnormal matrical inclusions of peroxisomes were formed in the cells of hyperplastic nodules by ethyl-alpha-p-chlorophenoxyisobutyrate unlike in the case of rats.

Animals↗

PubMed1976

Cytochemical studies on the localization of methanol oxidase and other oxidases in peroxisomes of methanol-grown Hansenula polymorpha.

The localization of methanol oxidase activity in cells of methanol-limited chemostat cultures of the yeast Hansenula polymorpha has been studied with different cytochemical staining techniques. The methods were based on enzymatic or chemical trapping of the hydrogen peroxide produced by the enzyme during aerobic incubations of whole cells in methanol-containing media. The results showed that methanol-dependent hydrogen peroxide production in either fixed or unfixed cells exclusively occurred in peroxisomes, which characteristically develop during growth of this yeast on methanol. Apart from methanol oxidase and catalase, the typical peroxisomal enzymes D-aminoacid oxidase and L-alpha-hydroxyacid oxidase were also found to be located in the peroxisomes. Urate oxidase was not detected in these organelles. Phase-contrast microscopy of living cells revealed the occurrence of peroxisomes which were cubic of form. This unusual shape was also observed in thin sections examined by electron microscopy. The contents of the peroxisomes showed, after various fixation procedures, a completely crystalline or striated substructure. It is suggested that this substructure might represent the in vivo organization structure of the peroxisomal enzymes.

Alcohol Oxidoreductases↗

PubMed1979

Cytochemical localization of catalase and several hydrogen peroxide-producing oxidases in the nucleoids and matrix of rat liver peroxisomes.

The distribution of catalase, amino acid oxidase, alpha-hydroxy acid oxidase, urate oxidase and alcohol oxidase was studied cytochemically in rat hepatocytes. The presence of catalase was demonstrated with the conventional diaminobenzidine technique. Oxidase activities were visualized with methods based on the enzymatic or chemical trapping of the hydrogen peroxide produced by these enzymes during aerobic incubations. All enzymes investigated were found to be present in peroxisomes. Catalase activity was found in the peroxisomal matrix, but also associated with the nucleoid. After staining for oxidase activities the stain deposits occurred invariably in the peroxisomal matrix as well as in the nucleoids. In all experiments the activity of both catalase and the oxidases was confined to the peroxisomes. The presence of a hydrogen peroxide-producing alcohol oxidase was demonstrated for the first time in peroxisomes in liver cells. The results imply that the enzyme activity of the nucleoids of rat liver peroxisomes is not exclusively due to urate oxidase. The nucleoids obviously contain a variety of other enzymes that may be more or less loosely associated with the insoluble components of these structures.

3,3'-Diaminobenzidine↗

PubMed1978

Acyl-Coenzyme A synthetase and fatty acid oxidation in rat liver peroxisomes.

Rat liver peroxisomes oxidized palmitate in the presence of ATP, CoA and NAD+, and the rate of palmitate oxidation exceeded that of palmitoyl-CoA oxidation. Acyl-CoA synthetase [acid: CoA ligase (AMP-forming); EC 6.2.1.3] was found in peroxisomes. The substrate specificity of the peroxisomal synthetase towards fatty acids with various carbon chain lengths was similar to that of the microsomal enzyme. The peroxisomal synthetase activity toward palmitate (40--100 nmol/min per mg protein) was higher than the rate of palmitate oxidation by the peroxisomal system (0.7--1.7 nmol/min per mg protein). The data show that peroxisomes activate long chain fatty acids and oxidize their acyl-CoA derivatives.

Adenine Nucleotides↗

PubMed1975

Peroxisome development in the metanephric kidney of mouse.

The relationship of enzymatic activity to organelle development and organelle number during differentiation of the metanephric kidney in the mouse was approached from several experimental directions. Biochemical analyses of marker enzymes for peroxisomes (catalase and D-amino acid oxidase), mitochondria (cytochrome oxidase) and lysosomes (acid phosphatase) were performed on kidneys at ages from 17 days prenatal to adult. These data were correlated with a morphometric analysis of populations of peroxisomes and mitochondria in differentiating cells of the proximal tubule. Postnatal development of the metanephric kidney was found to be accompanied by a rapid increase in both the specific activity of catalase and the number of peroxisomes per 100 mu2 in the proximal tubule during the first 4 weeks of postnatal growth. Elaboration of the endoplasmic reticulum (ER) was seen to parallel the increase in number of peroxisomes to which segments of ER were often in close apposition. Extensive interactions between segments of ER and peroxisomes were readily visible in 0.5-mu sections viewed in the high voltage electron microscope. In contrast to peroxisomes, neither mitochondria nor lysosomes followed a similar pattern of net organelle increase, suggesting that a defined population density of mitochondria and lysosomes may exist in the proximal tubule at birth, prior to complete development of the kidney.

Acid Phosphatase↗

PubMed1977

Peroxisomes in pulmonate gastropods.

Organelles with the morphologic characteristics of peroxisomes have been found in the cells of the kidney sac of two terrestrial pulmonate gastropods. Arion ater and Ariolimax columbianus. These peroxisomes appear in profile as circles or ellipses, 0.25 micron in diameter and 0.3-0.8 micron long; They have a finely granular matrix and a single-limiting membrane; the organelles are extensively associated with smooth endoplasmic reticulum. Some Ariolimax peroxisomes contained structures reminiscent of nucleoids while those of Arion did not. The peroxisomes of Arion ater show a strongly-positive staining reaction with the 3,3'-diaminobenzidine technique, which is inhibited in the presence of aminotriazole. Peroxisomes of Ariolimax columbianus did not show a positive reaction, despite a number of variations of the 3,3'-diaminobenzidine protocol. Speculations are made concerning the biochemical reasons for this cytochemical behavior. Peroxisomes in both tissues were negatively stained while lysosomes were positively stained in acid-phosphatase incubations.

3,3'-Diaminobenzidine↗

PubMed1978

Evidence for glycogen particles in the peroxisome of riboflavin deficient mouse kidney.

In the proximal tubular cells of the kidney in riboflavin deficient mice, electron dense particulate materials of about 30 nm in diameter were observed in the matrix of the peroxisome-like cytoplasmic bodies. The cytochemical study showed that these cytoplasmic bodies were negative for acid phosphatase activity and positive for DAB reaction, thus indicating that these organelles were peroxisomes. The particulate materials in peroxisomes were well stained with aqueous uranyl acetate, lead tartrate, alkaline bismuth and periodate acid bismuth. These particles were also digested by amylase. These results indicated that the particulate materials in peroxisomes were native glycogen particles. From the present study it was apparent that the peroxisome contained glycogen particles, and suggested the possibility that in some conditions glycogen might be synthesized in the peroxisome.

Animals↗

PubMedDate not supplied

[Possible participation of mitochondria in formation of peroxisomes in yeasts].

The origin of peroxisomes in yeast organisms is still unknown. These organelles are believed to be formed, similar to animal cells, from the endoplasmatic reticulum. However, this has not been confirmed directly. Peroxisomes are often found to be in contact with channels of the endoplasmatic reticulum and, in our experiments, with mitochondria of yeast organisms, especially those which utilize oleic acid, n-alkanes and methanol as a sole source of carbon. In Rhodotorula, peroxisomes are characterized by the same "bean" configuration and paired arrangement imitating "copulation" as mitocondria. In Kloeckera boidinii, a mitochondrion was transformed into a peroxisome and cristae were lost. A part of the peroxisome still possessed a double membrane typical of mitochondria while another part had a single membrane characteristic of peroxisomes. Further studies are being carried out in order to find if this is a general relationship or one of possibilities.

Microbodies↗

PubMedDate not supplied

[Role of divalent cations in the structural organization of the peroxisomal membrane].

Factors, which affected the stability of peroxisomal membrane in vitro, were investigated. The decrease in the activity of catalase at neutral and alkaline pH was prevented by addition of Ca2+, Mg2+ and Ba2+; at the same time EDTA, EGTA and o-phenantroline decreased the stability of peroxisomes. All the effects were temperature-dependent. Ca2+ did not prevent the injury of peroxisomes during hypotonic lysis, but increased the electrostatic interactions of enzymes with the peroxisomal membrane. These data suggest that at neutral and alkaline pH the peroxisomal membranes had a large negative charge on their surface, which affected the stability of peroxisomes in vitro.

Acid Phosphatase↗

PubMedDate not supplied

[Yeast peroxisomes, their development and operation].

Yeast peroxisomes (microbodies) were studied, particularly with yeast methylotrophs, using light-optical microscopy, viz. intravitam phase- and anoptral-contrast microscopy, with cytochemical as well as fixed and stained objects. The data obtained were compared with cytochemical as well as fixed and stained objects. The data obtained were compared with other evidence that we had gained on methylotrophs studied by electron microscopy and with the results obtained by investigating the peroxisomes of yeast cultures grown on nutrient containing other carbon sources. The activity of exocatalase and endocatalase, the enzymes characteristic of peroxisomes, was assayed at different growth phases of yeast methylotrophs and was found to be correlated with the cycle of development of peroxisomes. The content of biotin and inositol and its dynamics were studied in the methylotroph cells. Possible origin of peroxisomes is discussed as well as their development and the mechanism of degradation. A close contact and functional relationship have been established between peroxisomes and mitochondria.

Biotin↗

PubMed1978

Rat liver peroxisomes catalyze the beta oxidation of fatty acids.

Peroxisomes were purified by differential and equilibrium density centrifugation from the livers of rats treated with clofibrate to enhance their peroxisomal system of fatty acid oxidation. These purified peroxisomes were tested for the presence of crotonase, beta-hydroxybutyryl-CoA dehydrogenase and thiolase using spectroscopic techniques that utilize the characteristic absorption bands of the appropriate 4-carbon acyl-CoA substrates. All three enzymes were found. Analysis of the fractions from equilibrium density centrifugation revealed major peaks of these enzyme activities in peroxisomes and excluded contamination by mitochondria as an explanation of the results. In the presence of excess CoA the purified peroxisomes oxidized palmitoyl-CoA to acetyl-CoA, and reduced NAD, with a 1:5:5 stoichiometry. The peroxisomes were inactive with butyryl-CoA and less active with octanoyl-CoA than with lauroyl-CoA or palmitoyl-CoA; they appear specialized for the beta oxidation of long chain fatty acids.

Acetyl Coenzyme A↗

PubMed1978

Hepatic peroxisome proliferation: induction by BR-931, a hypolipidemic analog of WY-14,643.

Administration of BR-931, an ethanolamine derivative of Wy-14,643 [4-chloro-6-(2,3-xylidino)-2-pyrimidinythio]acetic acid, at a dietary concentration of 0.125% for 3 weeks to male F-344 rats, resulted in a significant enlargement of the liver. The hepatomegaly appeared to be due to liver cell hyperplasia and hypertrophy resulting, in part, from peroxisome and smooth endoplasmic reticulum proliferation. The hepatic catalase and carnitine acetyltransferase activities increased significantly in association with peroxisome proliferation. The hepatomegaly and peroxisome proliferation induced by BR-931 were comparable in degree to those resulting from feeding of an equivalent dose of Wy-14,643. All these hepatic effects were reversible when the drugs were withdrawn from the diet. Screening of new compounds for hepatic peroxisome proliferation and for increases in peroxisome-associated enzymes may prove to be an adjunct to evaluating their potency as hypolipidemic agents, in view of frequent association between hepatic peroxisome proliferation and hypolipidemia.

Acetamides↗

PubMedDate not supplied

[Structure and function of hepatocyte lysosomes and peroxisomes of rachitic rats].

The submicroscopic organization and activity of acid phosphatase and catalase in lysosomes and peroxisomes of the rat hepatocytes were studied with experimental rachitis. It is determined that total and free activity of acid phosphatase in the liver tissue and certain lysosomes with rachitis increases whereas the catalase activity in the tissue and certain peroxisomes decreases. Permeability of the lysosome and peroxisome membranes rises for enzymes and cations. The process of peroxisome differentiation with rachitis is disturbed: there appear peroxisomes containing the marginal plates, that is not peculiar to the redont peroxisomes.

Acid Phosphatase↗

PubMed2025

Spectrum of genetic alterations in patients with peroxisome biogenesis defects in the Iranian population: a case series study.

Peroxisomal disorders are a group of hereditary metabolic disorders that happen when peroxisomes are defective. Around 80% of individuals affected by peroxisomal disorders are classified within the spectrum of Zellweger syndromes with autosomal recessive inheritance pattern that results from mutations in one of the 13 PEX genes. Clinical exome sequencing plays a vital role in the diagnosis where the symptoms are atypical. In the current study, we used this technique to find the underlying genetic cause in 14 Iranian patients with peroxisomal disorders. PEX1 variants were detected in five patients. PEX2, PEX5, PEX6 and PEX7 variants were detected in three, one, one, and two cases, respectively. Finally, ACOX1 variants were identified in two cases. All cases except two cases were homozygote for the suspected variants in Zellweger syndrome-related genes. Two cases were compound heterozygote for variants in the PEX1 gene. In total, two novel variants were identified, including c.313 C > T (p.Gln105*) and c.961 A > T (p.Ile321Phe) in the PEX1 and ACOX1 genes, respectively. The present research expands the range of genetic variations observed in Iranian individuals diagnosed with various forms of Zellweger spectrum disorders.

Humans↗

PubMed1977

An electron microscopic and enzymic study of rat liver peroxisomal nucleoid core and its association with urate oxidase.

The appearance of the characteristic crystalloid core of rat liver peroxisomes is emulated by the electron microscopic (EM) appearance of highly purified urate oxidase prepared from the same tissue. The purity of the enzyme preparation was established by gel electrophoresis under various conditions and the specific enzyme activity was at least as high as any previously reported. The amino acid composition of urate oxidase was determined. As additional evidence for close association of the peroxisomal core with urate oxidase, it was demonstrated that the biphasic changes in rat liver urate oxidase activity in response to prolonged starvation were paralleled by changes in the EM appearance of peroxisomes. Under comparable conditions catalase, another peroxisomal enzyme, did not show the same changes in activity as did urate oxidase. Evidence for the possible identity of urate oxidase with the peroxisomal crystalloid of rat liver has been presented, all materials having been obtained from, and experiments performed with, the rat.

Amino Acids↗

PubMed1977

Peroxisomes (microbodies) in the myocardium of rodents and primates. A comparative Ultrastructural cytochemical study.

The occurrence of peroxisomes (microbodies), their cytochemical characteristics and their ultrastructural relationship to the neighboring organelles were investigated in the ventricular myocardium of four rodent (rat, rabbit, gerbil, and guinea pig) and two primate (Macaca java and Tupaya) species. The hearts were fixed by vascular perfusion with glutaraldehyde and incubated in alkaline diaminobenzidine media for visualization of catalase. The electron-dense reaction product of catalase was found in the myocardium of all examined species and was localized in 0.2--0.5 mum oval particles, surrounded by a single limiting membrane and located usually at the junction of I and A bands. The peroxisomes in the hearts of gerbil and Macaca java were especially long and tortuous. A close spatial association was found between the myocardial peroxisomes and mitochondria, lipid droplets, and the membranes of sarcoplasmic reticulum, especially the so-called junctional sarcoplasmic reticulum. These observations demonstrate the consistent occurrence of peroxisomes in the heart of various mammalian species and suggest that peroxisomes have important metabolic and physiological functions in myocardium.

Animals↗

PubMed1978

Preparation of peroxisomes from carp liver by zonal rotor density gradient centrifugation.

Peroxisomes from carp liver can be separated by isopycnic density gradient centrifugation in sucrose. Without reaching complete sedimentation equilibrium, the purification by this method is quite successful. There is a 40-fold enrichment of catalase, the peroxisomal marker, with a total yield of 27%. No pretreatment of animals is necessary for separation from lysosomes, which, besides high fragility, show lower buoyant densities than peroxisomes. The enzyme content of carp liver peroxisomes is similar to that of rat liver, with the exception of alpha-glycerophosphate dehydrogenase, which in this tissue is a completely soluble cytoplasmic enzyme. Total activities are much lower than in the rat, for the characteristic peroxisomal oxidases the difference being in the range of one order of magnitude.

Alcohol Oxidoreductases↗

PubMed1976

Peroxisome development in the regenerating pars recta (P3 segment) of proximal tubules of the rat kidney.

The development of peroxisomes, lysosomes and endocytic vacuoles in regenerating cells of the pars recta (P3 segment) of proximal tubules, in rats given a single interperitoneal injection of d-serine (80 mg/100 g.b.wt), was studied by light and electron microscopy using cytochemical methods. Rapid proliferation of cells occurred between 2 and 5 days after d-serine induced tubular necrosis; by day 6 almost all injured tubules were re-epithelialized with flat or low cuboidal cells. Peroxisomes and lysosomes were not observed during the period of rapid cell multiplication i.e., between 2 and 6 days after d-serine injection. Restitution of mitochondrial population preceded the development of peroxisomes in the newly regenerated cells of P3 tubules. Maximum development of peroxisomes occurred between 9 and 14 days after d-serine injection. The formation of peroxisomes appeared to correlate closely with the differentiation of apical endocytic vacuoles and the brush border. Lysosomes in the regenerated cells of P3 tubules were the last to develop.

Acid Phosphatase↗