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1.
Fatty acid, isoprenoid quinone and polar lipid composition in the classification of Renibacterium salmoninarum 总被引:1,自引:1,他引:0
Twenty-one strains of Renibacterium salmoninarum were degraded by acid methanolysis and the non-hydroxylated fatty acid esters released examined by thin-layer and gas chromatography. The fatty acid profiles were composed almost exclusively of methyl-branched fatty acids with 12-methyltetradecanoic ( anteiso -C15 ), 13-methyltetradecanoic ( iso -C15 ) and 14-methylhexadecanoic ( anteiso -C17 ) as major components. Polar lipids of the test strains were examined by two-dimensional thin-layer chromatography. All of the organisms possessed very characteristic polar lipid patterns consisting of diphosphatidylglycerol, two major and six or seven minor glycolipids, and two unidentified minor phospholipids. In all cases the major menaquinone components consisted of unsaturated menaquinones with nine isoprene units. The lipid data support the integrity of the genus Renibacterium and can be used to separate it from Corynebacterium and from coryneform bacteria which also contain lysine in the wall peptidoglycan. 相似文献
2.
B.J. Tindall 《FEMS microbiology letters》1989,60(3):251-254
Abstract The anaerobic, thermophilic archaebacterium, Pyrobaculum islandicum (Geo 3) was examined for the presence of lipoquinones. Thin layer chromatographic, HPLC, UV, and mass spectroscopic analysis showed that a menaquinone was present. No evidence was found for substitution of the 2-methyl-3-polyisoprenyl-1,4-naphthoquinone ring nucleus. However, the C3 isoprenoid chain consisted of six fully saturated units, and shows that the major menaquinone in this organism corresponds to 2-methyl-3-VI,V,IV,III,II,I-dodecahydrohexaprenyl-1, 4-naphthoquinone (MK-6H12 ). 相似文献
3.
Suspension-cultured rose ( Rosa damascena Mill. cv. Gloire de Guilan) cells irradiated with UV-C (254 nm. 558 J m−2 ) showed a transient production of H2 O2 as measured by chemiluminescence of luminol in the presence of peroxidase (EC 1.1 1.1.7). The peak concentration of H2 O2 , which occurred at about 60–90 min after irradiation, was 8–9 μ M . The time course for the appearance of H2 O2 matched that for UV–induced K+ efflux. Treatments that inhibited the UV-induced efflux of K+ , including heat and overnight incubation with cycloheximide and diethylmaleate, also inhibited the appearance of H2 O2 . The converse was not always true, since catalase (EC 1.11.1.6. and salicylhydroxamic acid, which inhibited luminescence, did not stop K+ efflux. We conclude that H2 O2 synthesis depends on K+ efflux. Because H2 .O2 in the extracellular space is required for lignin synthesis in many plant tissues, we suggest that the UV–stimulated production of H2 O2 is an integral part of a defensive lignin synthesis. 相似文献
4.
Soils contain two different activities for oxidation of hydrogen 总被引:1,自引:0,他引:1
Abstract Hydrogen oxidation rates were measured in a neutral compost soil and an acidic sandy loam at H2 mixing ratios of 0.01 to 5000 ppmv. The kinetics were biphasic showing two different K m values for H2 , one at about 10–40 nM dissolved H2 , the other at about 1.2–1.4 μM H2 . The low- K m activity was less sensitive to chloroform fumigation than the high- K m activity. If sterile soil was amended with Paracoccus denitrificans or a H2 -oxidizing strain isolated from compost soil, it exhibited only a high- K m (0.7–0.9 μM) activity. It also failed to utilize H2 mixing ratios below a threshold of 1.6–3.0 ppmv H2 (160–300 mPa). A similar result was obtained when fresh soil samples were suspended in water, and H2 oxidation was determined from the decrease of dissolved H2 . However, H2 was again utilized to mixing ratios lower than 0.05 ppmv, if the supernatant of the soil suspension or the settled soil particles were dried onto sterile soil or purified quarz sand. Obviously, soils contain two different activities for oxidation of H2 : (1) a high- K m , high-threshold activity which apparently is due to aerobic H2 -oxidizing bacteria, and (2) a low- K m , low-threshold activity whose origin is unknown but presumably is due to soil enzymes. 相似文献
5.
The Dutch elm disease (DED) pathogen Ophiostoma novo-ulmi Buissm. elicited the production of H2 O2 in cell suspension cultures of the resistant species Ulmus pumila L. This response was not observed in suspensions of the susceptible elm U. campestris Mill. H2 O2 production started after a lag time of 30–40 min following inoculation, peaked between 4 and 6 h and lasted up to 24 h. Treatment of the suspensions with exogenously added H2 O2 did not cause accumulation of the sesquiterpene phytoalexins mansonones nor of the coumarin scopoletin. Spore germination and growth of O. novo-ulmi were significantly delayed with different amounts of H2 O2 (0.1–1 m M ). These results suggest that H2 O2 production is an inducible defence response which may contribute to DED resistance by delaying the growth of the pathogen at the earliest stages of infection. Whether H2 O2 is involved in other elm defence responses to the pathogen is presently unknown, but its production seems to be an independent event from phytoalexin formation. 相似文献
6.
RAT BRAIN FOLATE IDENTIFICATION 总被引:3,自引:0,他引:3
Abstract— Endogenous rat brain folates were identified using column chromatography for folate separation, authentic folate standards, and microbiological assay. The total folate content of rat brain was 360 ng per gram brain (wet wt) and consisted of tetrahydropteroylpentaglutamate (H4 PteGlu5 , 29%), H4 PteGlu6 (14%), H4 PteGlu7 (7%), 5-CH3 -H4 PteGlu4 (7%), 5-CH3 -H4 PteGlu5 (13%), and small amounts of formyl-, methyl-, and H4 PteGlu1-6 (~25%) and non-methylated folates having a glutamate chain over seven glutamates long (4%). Overall folate oxidation state and one carbon forms were H4 PteGlun (58%), 5-CH3 -H4 PteGlun (18%), 5- and 10-CHO-H4 PteGlun (16%), and H2 PteGlun (8%). No PteGlun was detected. 相似文献
7.
Anita Sellstedt 《Physiologia plantarum》1989,75(2):304-308
Occurrence and activity of the hydrogen uptake enzyme were studied in root nodule homogenates made from plants of Alnus incana (L.) Moench collected from field sites in the northern part of Sweden. Nitrogenase (EC 1.7.99.2) activity (estimated by acetylene reduction) and hydrogen evolution were studied in excised nodules. All Frankia sources showed acetylene reduction activity, and possessed a hydrogen uptake system. Hydrogen uptake in nodule homogenates from the Frankia sources measured at 23.8 μM H2 ranged from 0.04 to 5.0 μmol H2 (g fresh weight nodule)−1 h−1 . The H2 uptake capacity of nodule homogenates from one of the Frankia sources was almost 8 times higher than the hydrogen evolution from nitrogenase, both expressed on a nodule fresh weight basis. Frankia sources from field sites 6 and 11 showed Km for H2 of 13.0 and 23.6 μM H2 , respectively. This indicates similarities in the hydrogen uptake enzymes in the two Frankia sources. It is concluded that hydrogen uptake is a common characteristic in Frankia. 相似文献
8.
HISTAMINE-SENSITIVE ADENYLATE CYCLASE IN HYPOTHALAMUS OF RAT BRAIN: H1 AND H2 RECEPTORS 总被引:3,自引:2,他引:1
Abstract— In in vitro experiments on rat hypothalamic homogenates the effects of biogenic amines such as histamine (HA), noradrenaline (NA), dopamine (DA), serotonin (5-HT) and drugs such as isoprenaline (ISP), 2-(2-pyridyl)ethylamine (H2 stimulant—Hls ), 4-methyl-histamine (H2 stimulant H2s ), mepyramine (H1 antagonistp Hla ), cimetidine (H2 antagonist—H2a ) were tested on adenylate cyclase activity. HA possessed a powerful stimulating effect on hypothalamic adenylate cyclase activity, higher than that shown by the other substances.
The stimulating effect of HA was greatest in hypothalamic tissue from male rats, while tissue from females showed only a modest stimulation. H2s , induced a greater stimulation of adenylate cyclase than Hls . On the other hand, the H2a inhibited HA stimulation to a greater extent than the Hla , Hla and H2a , when used together, completely inhibited the HA stimulation. HA may have a neurotrans-mitter role in the hypothalamus, and in this area there appears to be a mixed population of H1 and H2 receptors, with a majority of H2 receptors. 相似文献
The stimulating effect of HA was greatest in hypothalamic tissue from male rats, while tissue from females showed only a modest stimulation. H
9.
Valentino Casolo Enrico Braidot Elisa Chiandussi Angelo Vianello Francesco Macrì 《Physiologia plantarum》2003,118(3):313-318
The role of a recently identified K+ ATP channel in preventing H2 O2 formation was examined in isolated pea stem mitochondria. The succinate-dependent H2 O2 formation was progressively inhibited, when mitochondria were resuspended in media containing increasing concentration of KCl (from 0.05 to 0.15 M ). This inhibition was linked to a partial dissipation of the transmembrane electrical potential (ΔΨ) induced by KCl. Conversely, the malate plus glutamate-dependent H2 O2 formation was not influenced. The succinate-sustained H2 O2 generation was also unaffected by nigericin (a H+ /K+ exchanger), but completely prevented by valinomycin (a K+ ionophore). In addition, cyclosporin A (a K+ ATP channel opener) inhibited this H2 O2 formation, while ATP (an inhibitor of the channel opening) slightly increased it. The inhibitory effect of ATP was strongly stimulated in the presence of atractylate (an inhibitor of the adenine nucleotide translocase), thus suggesting that the receptor for ATP on the K+ channel faces the intermembrane space. Finally, the succinate-dependent H2 O2 formation was partially prevented by phenylarsine oxide (a thiol oxidant). 相似文献
10.
The hydrogen peroxide (H2 O2 ) stress response in Enterococcus faecalis ATCC19433 was investigated. A 2·4 mmol l−1 H2 O2 pretreatment conferred protection against a lethal concentration (45 mmol l−1 ) of this agent. The relatively high concentrations of H2 O2 used for adaptation and challenge treatments in Ent. faecalis emphasised the strong resistance towards oxidative stress in this species. Various stresses (NaCl, heat, ethanol, acidity and alkalinity) induced weak or strong H2 O2 cross-protection. This paper describes the involvement of protein synthesis in the active response to lethal dose of H2 O2 , in addition to the impressive enhancement of synthesis of five H2 O2 stress proteins. Combined results suggest that these proteins might play an important role in the H2 O2 tolerance response. 相似文献
11.
Abstract Hydrogen consumption was measured in hot geothermal water from two ponds of the San Federigo solfatara, Tuscany, Italy, where emanation gases contained approx. 4% H2 . H2 consumption was completely inhibited by NaOH and partially by HgCl2 indicating microbial utilization. Aerobic and anaerobic H2 consumption activities coexisted in the same water with aerobic activity being higher in one pond and anaerobic activity in the other. The kinetics of H2 consumption were consistent with those of 'Knallgas', methanogenic or sulfidogenic bacteria. 相似文献
12.
M. J. Smit H. Timmerman J. Blauw M. W. Beukers E. Roovers E. H. Jacobs M. Hoffmann R. Leurs 《Journal of neurochemistry》1996,67(5):1791-1800
Abstract: To examine the role of the C terminal tail in H2 receptor regulation, three cDNAs, encoding truncated histamine H2 receptor mutants (H2 T295, H2 T307, and H2 T341), were constructed and stably transfected in Chinese hamster ovary (CHO) cells. The amino acids before position 307 appear to be necessary for proper receptor transport or folding, as no detectable H2 receptor binding of the H2 T295 was observed after transfection. Truncation of the C terminal tail by 51 amino acids (H2 T307) did not affect the binding properties of H2 antagonists and histamine or histamine-induced signaling. Yet, removal of 17 amino acids generated a mutant receptor (H2 T341), which was able to form a ternary complex but was unable to fully activate the Gs protein on histamine exposure. Agonist-induced but not the cyclic AMP-dependent H2 receptor down-regulation was more profound for the H2 T307 receptor, indicating that different structural elements of the H2 receptor protein are involved in the cyclic AMP-dependent and independent pathways of H2 receptor down-regulation. Taken together, in this study we identified regions in the C terminal tail of the H2 receptor that act as positive and/or negative signals in H2 receptor signaling and down-regulation. 相似文献
13.
Abstract: In a model recently developed to study the parameters altering vulnerability to oxidative stress, it was shown via image analysis that H2 O2 -exposed PC12 cells exhibited increased levels of intracellular Ca2+ (baseline), decreases in K+ -stimulated Ca2+ levels (peak), and decreased poststimulation Ca2+ clearance (recovery). The present experiments were performed to determine if the response patterns in these parameters to oxidative stress would be altered after modification of membrane lipid composition induced by incubating the PC12 cells with 660 µ M cholesterol (CHL) in the presence or absence of 500 µ M sphingomyelin (SPH) before low (5 µ M ) or high (300 µ M ) H2 O2 exposure. Neither CHL nor SPH had synergistic effects with high concentrations of H2 O2 on baseline. However, CHL in the presence or absence of SPH reversed the effect of low concentrations of H2 O2 on baseline. SPH decreased significantly the cell's ability to clear excess Ca2+ in the presence or absence of H2 O2 and increased significantly the level of conjugated dienes (CDs). It is surprising that in the cells pretreated with CHL, the CD levels were not significantly different from controls. However, in the presence of SPH, the effects of CHL on CDs were altered. These results suggest that the ratios of membrane lipids could be of critical importance in determining the vulnerability to oxidative stress and Ca2+ translocation in membranes. This may be of critical importance in aging where there is increased membrane SPH and significant loss of calcium homeostasis. 相似文献
14.
Abstract The effect of cadmium (Cd) on methane formation from methanol and/or H2 –CO2 by Methanosarcina barkeri was examined in a defined growth medium and in a simplified buffer system containing 50 mM Tes with or without 2 mM dithiothreitol (DTT). No inhibition of methanogenesis by high concentrations of cadmium was observed in growth medium. Similarly, little inhibition of methanogenesis by whole cells in the Tes buffer system was observed in the presence of 430 μM Cd or 370 μM mercury (Hg) with 2 mM DTT. When the concentration of DTT was reduced to 0.4 mM, almost complete inhibition of methanogenesis from H2 –CO2 and methanol by 600 μM Cd was observed. In the absence of DTT, 150 μM Cd inhibited methanogenesis from H2 –CO2 completely and from methanol by 97%. Methanogenesis from H2 –CO2 was more sensitive to Cd than that from methanol. 相似文献
15.
Abstract: We studied the action of H2 O2 on the exocytosis of glutamate by cerebrocortical synaptosomes. The treatment of synaptosomes with H2 O2 (50–150 µ M ) for a few minutes results in a long-lasting depression of the Ca2+ -dependent exocytosis of glutamate, induced by KCl or by the K+ -channel inhibitor 4-aminopyridine. The energy state of synaptosomes, as judged by the level of phosphocreatine and the ATP/ADP ratio, was not affected by H2 O2 , although a transient decrease was observed after the treatment. H2 O2 did not promote peroxidation, as judged by the formation of malondialdehyde. In indo-1-loaded synaptosomes, the treatment with H2 O2 did not modify significantly the KCl-induced increase of [Ca2+ ]i . H2 O2 inhibited exocytosis also when the latter was induced by increasing [Ca2+ ]i with the Ca2+ ionophore ionomycin. The effects of H2 O2 were unchanged in the presence of superoxide dismutase and the presence of the Fe3+ chelator deferoxamine. These results appear to indicate that H2 O2 , apparently without damaging the synaptosomes, induces a long-lasting inhibition of the exocytosis of glutamate by acting directly on the exocytotic process. 相似文献
16.
Abstract Bradyrhizobium japonicum and Shewanella putrefaciens were unable to oxidize hydrogen at atmospheric concentrations (0.55 ppmv), neither in suspension nor when added to sterile soil. The K m -value of S. putrefaciens for H2 (39 ppmv in gas phase, 0.22 μM in aqueous phase), using Fe(III) as electron acceptor, showed a 4–5-fold higher affinity for H2 than that of B. japonicum (1200 ppmv; 0.84 μM) or other hydrogen-oxidizing bacteria. However, the V max (4.54 fmol H2 h−1 cell −1 ) and threshold (> 0.5 ppmv; 0.35 nM) of S. putrefaciens and the V max (7.19 fmol H2 h−1 cell−1 ) and threshold (> 0.5 ppmv; 0.35 nM) of B. japonicum were in the same order of magnitude as data for Knallgas bacteria from relevant literature. To enable hydrogen oxidation in soil the soil-samples with S. putrefaciens even had to be supplemented with Fe(III). Fresh soil, on the other hand, oxidized hydrogen very efficiently below atmospheric mixing ratios, demonstrating that there must be other oxidation activities in soil. 相似文献
17.
Ahmed Gaber Kazuya Yoshimura Takashi Yamamoto Yukinori Yabuta Toru Takeda Hitoshi Miyasaka Yoshihisa Nakano Shigeru Shigeoka 《Physiologia plantarum》2006,128(2):251-262
Glutathione peroxidase (GPX)-like proteins (GPX-1 and GPX-2) of Synechocystis PCC 6803 ( S. PCC 6803) reduce unsaturated fatty acid hydroperoxides using NADPH, but not reduced glutathione (GSH), as an electron donor. Here, we generated transgenic Arabidopsis plants overexpressing S. PCC 6803 GPX-2 in the cytosol (AcGPX2) or chloroplasts (ApGPX2). The activities toward α-linolenic acid hydroperoxide in ApGPX2 and AcGPX2 plants were 6.5–11.5 and 8.2–16.3 nmol min−1 mg protein−1 , respectively, while no activity (<0.1 nmol min−1 mg protein−1 ) was detected in the wild-type plants. Both transgenic lines (AcGPX2 and ApGPX2) showed enhanced tolerance to oxidative damage caused by treatment with H2 O2 (10 m M ), Fe ions (200 μ M ) or methylviologen (50 μ M ) and environmental stress conditions, such as chilling with high light intensity (4°C, 1000 μmol photons m−2 s−1 ), high salinity (100 m M NaCl) or drought. The degree of tolerance of the transgenic plants to all types of stress was correlated with the levels of lipid peroxide suppressed by the overexpression of S. PCC 6803 GPX-2. Under conditions of oxidative stress due to the H2 O2 treatment, the NADPH/(NADP+ + NADPH) ratio in the transgenic plants was lower than that in the wild-type plants. The data reported here indicate that the expression of S. PCC 6803 GPX-2 contributes to the reduction in unsaturated fatty acid hydroperoxides using NADPH in situ under stress conditions in the transgenic plants. 相似文献
18.
A Note on the Separation of Natural Mixtures of Bacterial Menaquinones using Reverse Phase Thin-layer Chromatography 总被引:10,自引:9,他引:1
Natural mixtures of bacterial menaquinones were separated according to the length and degree of saturation of the polyisoprenyl side-chain using ready made Merck RP-18F254 reverse phase thin-layer chromatography plates. The system described affords a simple and rapid means of menaquinone characterization. 相似文献
19.
Changes in catalase activity and hydrogen peroxide concentration in plants in response to low temperature 总被引:6,自引:0,他引:6
Taxicity of oxygen species such as free radicals and H2 O2 has been invoked to explain a number of degradative processes in plants, most involving photo-oxidation. Since catalase is a major protectant against accumulation and toxicity of H2 O2 , we examined alterations in catalase activity in several plant species ( Pisum sativum L. cv. Greenfeast, Vigna radiata (L.) R. Wilcz, Cucumis sativus L. cv. Heinz Pickling, and Passiflora spp.) during chilling, and compared this change to change in H2 O2 content. Catalase activity was reduced in a range of chilling sensitive and tolerant species by exposure to low temperature. This reduction in catalase activity correlated better with the onset of visible symptoms than with the treatment itself. Visible injury in turn was dependent on light and temperature differences. Hydrogen peroxide concentrations invariably decreased with low temperatures.
Reduction in catalase activity therefore does not necessarily imply accumulation of H2 O2 to damaging levels. The absence of a clear inverse relationship between catalase activity and H2 O2 concentration suggests the continued activity of other reactions that remove H2 O2 and these may be important in the tolerance of plants to oxidative attack. Loss of catalase activity may result from the inability of damaged peroxisomal membranes to transport catalase precursors into the peroxisome. 相似文献
Reduction in catalase activity therefore does not necessarily imply accumulation of H
20.
Hydrogen metabolism was studied in three Casuarina species, C, equisetifolia Forst., C. glauca Sieb. ex. Spreng. and C. obesa Miq., either inoculated with the pure Frankia culture HFP CcI3 or inoculated with a crushed nodule inoculum made from C. glauca nodules. Nitrogenase (EC 1.7.99.2) activity and hydrogen evolution was measured on intact plants, while hydrogen uptake was measured on excised nodules and in nodule homogenates.
Nitrogenase activity was highest in C. glauca inoculated with C. glauca nodules, while no hydrogen evolution was detected. Hydrogen evolution was highest in the symbiosis between C. equisetifolia and HFP CcI3, but the nitrogenase activity showed intermediate values compared to the other symbioses. Measured at a concentration of 93 μ M H2 , H2 uptake was highest in C. glauca inoculated with the C. glauca inoculum. H2 uptake activity in homogenates was 83% of the intact nodule rate. With phenazinemethosulfate as the electron acceptor, H2 uptake by nodule homogenates showed typical Michaelis-Menten kinetics with a Km of 21.3 μ M for H2 .
The data presented here indicate a host plant effect on the endobiont which alters the hydrogen metabolism. 相似文献
Nitrogenase activity was highest in C. glauca inoculated with C. glauca nodules, while no hydrogen evolution was detected. Hydrogen evolution was highest in the symbiosis between C. equisetifolia and HFP CcI3, but the nitrogenase activity showed intermediate values compared to the other symbioses. Measured at a concentration of 93 μ M H
The data presented here indicate a host plant effect on the endobiont which alters the hydrogen metabolism. 相似文献