The respiratory metabolism of Mycobacterium lepraemurium

1976 ◽  
Vol 22 (9) ◽  
pp. 1293-1299
Author(s):  
Laszlo Kato ◽  
Catherine Adapoe ◽  
M. Ishaque
Keyword(s):  
Tricarboxylic Acid Cycle ◽  
Oxidative Enzymes ◽  
Respiratory Metabolism ◽  
Sprague Dawley ◽  
Succinate Oxidation ◽  
Terminal Electron Acceptor ◽  
Sprague Dawley Rats ◽  
Transport Chain ◽  
Mycobacterium Lepraemurium ◽  
Thiol Binding

The respiratory metabolism of Mycobacterium lepraemurium isolated from Sprague-Dawley rats lepromata using several substrates was investigated. None of the intermediates of the glycolysis cycle as well as of the tricarboxylic acid cycle except succinate was oxidized by purified whole suspensions of M. lepraemurium. Likewise, many sulfur compounds such as cystine, thiourea, thioacetate, thiodiglycol, mercaptosuccinate, and mercaptoethanol were inactive. However, yeast extract and some sulfhydryl compounds, e.g., cysteine, dithioerythritol, dithiothritol, and penicillamine were readily oxidized by murine bacillary suspensions, whereas thioglycolate, thioglucose, and reduced glutathione were oxidized at a slow rate. Succinate was not or was very poorly oxidized by normal cells probably because of impermeability of the cell wall but the addition of succinate to the cell suspensions frozen for 1 min at −40 °C considerably enhanced oxygen uptake over the endogenous value. The oxidation of succinate was unaffected by inhibitors rotenone, atabrine, and amytal but was markedly inhibited by thenoyltrifluoroacetone, antimycin A, 2-N-heptyl-4-hydroxyquinoline-N-oxide, and cyanide. The thiol-binding agents, p-hydroxymercuribenzoate and N-ethylmaleimide were also effective inhibitors of succinate oxidation but the process was not affected by uncouplers dinitrophenol, dibromophenol, pentachlorophenol, and carbonyl-cyanide-m-chlorophenylhydrazone. The results indicated that succinate oxidation by M. lepraemurium was mediated by oxidative enzymes involving an electron transport chain with oxygen as the terminal electron acceptor.

Energy coupling mechanisms in host-grown Mycobacterium lepraemurium

1981 ◽  
Vol 59 (2) ◽  
pp. 75-82 ◽  
Author(s):  
M. Ishaque ◽  
C. Adapoe ◽  
L. Kato
Keyword(s):  
Energy Coupling ◽  
Oxidative Enzymes ◽  
Sprague Dawley ◽  
Succinate Oxidation ◽  
Sprague Dawley Rats ◽  
Mycobacterium Lepraemurium ◽  
Thiol Binding ◽  
Coupling Mechanisms ◽  
Respiratory Chain Inhibitors

Energy coupling mechanisms of Mycobacterium lepraemurium isolated from Sprague-Dawley rats lepromata were investigated. Cell-free extracts catalyzed phosphorylation coupled to the oxidation of generated NADH, added NADH, and succinate yielding P/O ratios of approximately 0.8, 0.6, and 0.4, respectively. Ascorbate oxidation alone or in the presence of cytochrome c or N,N,N′,N′-tetramethyl-p-phenylenediamine was not coupled to ATP synthesis.The oxidative phosphorylation was completely uncoupled by 2,4-dinitrophenol, 2,6-dibromophenol, pentachlorophenol, m-chlorocarbonylcyanide phenylhydrazone, dicumarol, and gramicidin at concentrations which did not cause any inhibition of oxygen uptake. While the NADH oxidation and associated phosphate esterification was markedly sensitive to rotenone and other flavoprotein inhibitors, these inhibitors had no effect, however, on the phosphorylation coupled to succinate oxidation. The respiratory chain inhibitors such as antimycin A or 2-n-heptyl-4-hydroxyquinoline-N-oxide, and cyanide were the potent inhibitors of the phosphorylation associated with the oxidation of NADH and succinate. The ATP formation coupled to the oxidation of NADH and succinate was also inhibited by oligomycin as well as by the thiol-binding agents, p-hydroxymercuribenzoate and N-ethylmaleimide. The results indicated that NADH and succinate oxidation by in vivo grown M. lepraemurium was mediated by oxidative enzymes involving first and second energy coupling sites.

scholarly journals Anaerobic Expression of Escherichia coli Succinate Dehydrogenase: Functional Replacement of Fumarate Reductase in the Respiratory Chain during Anaerobic Growth

1998 ◽  
Vol 180 (22) ◽  
pp. 5989-5996 ◽  
Author(s):  
Elena Maklashina ◽  
Deborah A. Berthold ◽  
Gary Cecchini
Keyword(s):  
Escherichia Coli ◽  
Tricarboxylic Acid Cycle ◽  
Anaerobic Respiration ◽  
Growth Conditions ◽  
Fumarate Reductase ◽  
Anaerobic Growth ◽  
Enzyme Complex ◽  
Succinate Oxidation ◽  
Terminal Electron Acceptor ◽  
E Coli

ABSTRACT Succinate-ubiquinone oxidoreductase (SQR) from Escherichia coli is expressed maximally during aerobic growth, when it catalyzes the oxidation of succinate to fumarate in the tricarboxylic acid cycle and reduces ubiquinone in the membrane. The enzyme is similar in structure and function to fumarate reductase (menaquinol-fumarate oxidoreductase [QFR]), which participates in anaerobic respiration by E. coli. Fumarate reductase, which is proficient in succinate oxidation, is able to functionally replace SQR in aerobic respiration when conditions are used to allow the expression of the frdABCD operon aerobically. SQR has not previously been shown to be capable of supporting anaerobic growth ofE. coli because expression of the enzyme complex is largely repressed by anaerobic conditions. In order to obtain expression of SQR anaerobically, plasmids which utilize the PFRD promoter of the frdABCD operon fused to the sdhCDAB genes to drive expression were constructed. It was found that, under anaerobic growth conditions where fumarate is utilized as the terminal electron acceptor, SQR would function to support anaerobic growth ofE. coli. The levels of amplification of SQR and QFR were similar under anaerobic growth conditions. The catalytic properties of SQR isolated from anaerobically grown cells were measured and found to be identical to those of enzyme produced aerobically. The anaerobic expression of SQR gave a greater yield of enzyme complex than was found in the membrane from aerobically grown cells under the conditions tested. In addition, it was found that anaerobic expression of SQR could saturate the capacity of the membrane for incorporation of enzyme complex. As has been seen with the amplified QFR complex, E. coli accommodates the excess SQR produced by increasing the amount of membrane. The excess membrane was found in tubular structures that could be seen in thin-section electron micrographs.

scholarly journals The metabolic response of plants to oxygen deficiency

2002 ◽  
Vol 14 (2) ◽  
pp. 83-94 ◽  
Author(s):  
Carlos Antônio Ferreira de Sousa ◽  
Ladaslav Sodek
Keyword(s):  
Anaerobic Metabolism ◽  
Metabolic Response ◽  
Tricarboxylic Acid Cycle ◽  
Oxygen Deficiency ◽  
Future Research ◽  
Experimental Conditions ◽  
Terminal Electron Acceptor ◽  
Transport Chain ◽  
N Metabolism

Plants, under natural or experimental conditions, can be subject to a range of O2 concentrations from normal (normoxia) through deficient (hypoxia) to total absence (anoxia). Many metabolic processes are affected by O2 deficiency but the most studied events are those related to respiration and metabolism of N. In the absence of a terminal electron acceptor for the electron transport chain, the tricarboxylic acid cycle functions only partially and in both directions. Acidification of the cytosol occurs and pyruvate, the product of glycolysis, is transformed to lactate and ethanol, which represent the main fermentation reactions in plants. Alanine is the third most important product of anaerobic metabolism, resulting from high rates of amino acid interconversion in which transaminases such as alanine aminotransferase play an important role. The role of alanine accumulation under anaerobiosis is not clear and appears to be independent of the source of N whether NO3-, NH4+ or N2. How nitrate exerts its beneficial effect on tolerance of root hypoxia in waterlogged plants is still not clearly understood. Such aspects of N metabolism pose interesting challenges for future research on metabolic responses of plants to oxygen deficiency.

scholarly journals Passing the Baton: Substrate Channelling in Respiratory Metabolism

Research ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Alisdair R. Fernie ◽  
Youjun Zhang ◽  
Lee J. Sweetlove
Keyword(s):  
Tricarboxylic Acid Cycle ◽  
Interesting Case ◽  
Respiratory Metabolism ◽  
Ample Evidence ◽  
Protein Protein Interaction ◽  
Transport Chain ◽  
Life Itself ◽  
Substrate Channelling ◽  
Species Specific ◽  
Over 40 Years

Despite species-specific differences in the pathways of respiratory metabolism are remarkably conserved across the kingdoms of life with glycolysis, the tricarboxylic acid cycle, and mitochondrial electron transport chain representing the major components of the process in the vast majority of organisms. In addition to being of critical importance in fueling life itself these pathways serve as interesting case studies for substrate channelling with research on this theme having been carried out for over 40 years. Here we provide a cross-kingdom review of the ample evidence for protein-protein interaction and enzyme assemblies within the three component pathways as well as describing the scarcer available evidence for substrate channelling itself.

scholarly journals Antidiabetic and Antinephritic Activities of Aqueous Extract ofCordyceps militarisFruit Body in Diet-Streptozotocin-Induced Diabetic Sprague Dawley Rats

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Chungang Liu ◽  
Jingjing Song ◽  
Meiyu Teng ◽  
Xiaoyi Zheng ◽  
Xiangmei Li ◽  
...  
Keyword(s):  
Aqueous Extract ◽  
Fasting Blood Glucose ◽  
Fruit Body ◽  
Density Lipoprotein ◽  
Diabetic Rats ◽  
Cordyceps Militaris ◽  
Oxidative Enzymes ◽  
Inflammatory Factors ◽  
Sprague Dawley ◽  
Sprague Dawley Rats

Cordyceps militarishas long been used as a crude drug and folk tonic food in East Asia. The present study aims to evaluate the antidiabetic and antinephritic effects of the aqueous extract of theCordyceps militarisfruit body (CM) in diet-streptozotocin- (STZ-) induced diabetic rats. During four weeks of continuous oral administration of CM at doses of 0.5, 1.0, and 2.0 g/kg and metformin at 100 mg/kg, the fasting blood glucose and bodyweight of each rat were monitored. Hypoglycemic effects of CM on diabetic rats were indicated by decreases in plasma glucose, food and water intake, and urine output. The hypolipidemic activity of CM was confirmed by the normalization of total cholesterol, triglycerides, and low- and high-density lipoprotein cholesterol in diabetic rats. Inhibitory effects on albuminuria, creatinine, urea nitrogen, and n-acetyl-β-d-glucosaminidase verified CM’s renal protective activity in diabetic rats. Furthermore, CM exerted beneficial modulation of inflammatory factors and oxidative enzymes. Compared with untreated diabetic rats, CM decreased the expression of phosphor-AKT and phosphor-GSK-3βin the kidneys. Altogether, via attenuating oxidative stress, CM displayed antidiabetic and antinephritic activities in diet-STZ-induced diabetic rats.

Ultrastructural Investigation of Spontaneous Pituitary Adenomas in Aging Sprague-Dawley Rats

1982 ◽  
Vol 40 ◽  
pp. 216-217
Author(s):  
D. J. McComb ◽  
J. Beri ◽  
F. Zak ◽  
K. Kovacs
Keyword(s):  
Microscopic Study ◽  
Pituitary Adenomas ◽  
Wistar Rats ◽  
Microscopic Level ◽  
Sprague Dawley ◽  
Prolactin Cells ◽  
Light Microscopic Level ◽  
Ultrastructural Investigation ◽  
Sprague Dawley Rats ◽  
Long Evans

Investigation of the spontaneous pituitary adenomas in rat have been limited mainly to light microscopic study. Furth et al. (1973) described them as chromophobic, secreting prolactin. Kovacs et al. (1977) in an ul trastructural investigation of adenomas of old female Long-Evans rats, found that they were composed of prolactin cells. Berkvens et al. (1980) using immunocytochemistry at the light microscopic level, demonstrated that some spontaneous tumors of old Wistar rats could contain GH, TSH or ACTH as well as PRL.

Early Development of Drug-Induced Hepatic Necrosis

1971 ◽  
Vol 29 ◽  
pp. 576-577
Author(s):  
F. G. Zaki ◽  
E. Detzi ◽  
C. H. Keysser
Keyword(s):  
Early Development ◽  
Hepatic Necrosis ◽  
Screening Tests ◽  
Dense Matrix ◽  
Sprague Dawley ◽  
Electron Microscopic ◽  
Drug Induced ◽  
Hepatocellular Damage ◽  
Sprague Dawley Rats ◽  
Microscopic Studies

This study represents the first in a series of investigations carried out to elucidate the mechanism(s) of early hepatocellular damage induced by drugs and other related compounds. During screening tests of CNS-active compounds in rats, it has been found that daily oral administration of one of these compounds at a dose level of 40 mg. per kg. of body weight induced diffuse massive hepatic necrosis within 7 weeks in Charles River Sprague Dawley rats of both sexes. Partial hepatectomy enhanced the development of this peculiar type of necrosis (3 weeks instead of 7) while treatment with phenobarbital prior to the administration of the drug delayed the appearance of necrosis but did not reduce its severity.Electron microscopic studies revealed that early development of this liver injury (2 days after the administration of the drug) appeared in the form of small dark osmiophilic vesicles located around the bile canaliculi of all hepatocytes (Fig. 1). These structures differed from the regular microbodies or the pericanalicular multivesicular bodies. They first appeared regularly rounded with electron dense matrix bound with a single membrane. After one week on the drug, these vesicles appeared vacuolated and resembled autophagosomes which soon developed whorls of concentric lamellae or cisterns characteristic of lysosomes (Fig. 2). These lysosomes were found, later on, scattered all over the hepatocytes.

Ultrastructural investigation of spontaneous pituitary gonadotroph cell adenomas in aging Sprague-Dawley rats

1983 ◽  
Vol 41 ◽  
pp. 702-703
Author(s):  
D. J. McComb ◽  
J. Beri ◽  
F. Zak ◽  
K. Kovacs
Keyword(s):  
Electron Microscopy ◽  
Animal Model ◽  
Epoxy Resin ◽  
Immunoelectron Microscopy ◽  
Tumor Type ◽  
Gonadal Function ◽  
Sprague Dawley ◽  
Male And Female ◽  
Reticulin Fibers ◽  
Sprague Dawley Rats

Gonadotroph cell adenomas of the pituitary are infrequent in human patients and are not invariably associated with altered gonadal function. To date, no animal model of this tumor type exists. Herein, we describe spontaneous gonadotroph cell adenomas in old male and female Sprague-Dawley rats by histology, immunocytology and electron microscopy.The material consisted of the pituitaries of 27 male and 38 female Sprague Dawley rats, all 26 months of age or older, removed at routine autopsy. Sections of formal in-fixed, paraffin-embedded tissue were stained with hematoxylin-phloxine-saffron (HPS), the PAS method and the Gordon-Sweet technique for the demonstration of reticulin fibers. For immunostaining, sections were exposed to anti-rat β-LH, anti-ratβ-TSH, anti-rat PRL, anti-rat GH and anti-rat ACTH 1-39. For electron microscopy, tissue was fixed in 2.5% glutaraldehyde, postfixed in 1% OsO4 and embedded in epoxy-resin. Tissue fixed in 10% formalin, embedded in epoxy resin without osmification, was used for immunoelectron microscopy.

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