In cell suspensions of Pseudomonas carboxydovorans pulsed with lithotrophic substrates (CO or H2) in the presence of oxygen, formation of reduced pyridine nucleotides and of ATP could be demonstrated using the bioluminescent assay. Experiments employing base-acid transition, an uncoupler and inhibitors of ATPase or electron transport enabled us to propose a model for the formation of NAD(P)H in chemolithotrophically growing P. carboxydovorans.The protonophor FCCP (carbonly-p-trifluormethoxyphenylhydrazon) inhibited both, formation of NAD(P)H and of ATP. In the absence of oxygen, a chemical potential imposed by base-acid transition resulted in the formation of NAD(P)H and ATP when electrogenic substrates (CO or H2) were present. This suggests proton motive force-driven NAD(P)H formation. The proton motive force was generated by oxidation of substrate, and not by ATP hydrolysis, as obvious from NAD(P)H formation during inhibition of ATP synthesis by oligomycin and N,N-dicyclohexylcarbodiimide.That the CO-born electrons are transferred via the ubiquinone 10-cytochrome b region to NADH dehydrogenase functioning in the reverse direction, was indicated by inhibition of NAD(P)H formation by HQNO (2-n-heptyl-4-hydroxyquinoline-N-oxide) and rotenone, and by resistance to antimycin A.We conclude that in P. carboxydovorans, growing with CO or H2, electrons and a proton motive force, generated by respiration, are required to drive an reverse electron transfer for the formation of reduced pyridine nucleotides.Abbreviations CODH
carbon monoxide dehydrogenase
- DCCD
N,N-dicyclohexylcarbodiimide
- FCCP
carbonyl-p-trifluormethoxyphenylhydrazon
- HQNO
2-n-heptyl-4-hydroxyquinoline-N-oxide
- pmf
proton motive force 相似文献
The myenteric plexus of the rainbow trout Salmo gairdneri is enclosed within an incomplete Schwann-like sheath which allows bundles of unmyelinated axons to pass into the adjacent smooth muscle layers. Neuronal and non-neuronal constituents of the myenteric plexus are divided into smaller units by endoneurial collagen which in places condenses to form a perineurial covering. The myenteric plexus is avascular but arterioles and fenestrated capillaries are present close to the plexus in the intermuscular space. Small groups of neurones constitute the ganglia of the plexus but as yet few ultrastructural indications of differing neurone types have been observed. Within the neuropil of the ganglia five types of axon profile, characterised by their vesicle content, have been identified. One of these types was only recognisable following the administration of 5-hydroxydopamine. Axo-somatic and axo-dendritic synaptic contacts were only made by Type 1 axons but these were uncommon. The presence of an adrenergic component of the myenteric plexus was confirmed ultrastructually following 6-hydroxydopamine-induced degeneration and also by Falck-Hillarp fluorescence histochemistry which revealed an extensive distribution of adrenergic nerves in the plexus. The structural organisation of the plexus, the comparatively few ultrastructurally recognisable axon and neurone types and the sparsity of synaptic contacts all indicate that the teleost myenteric plexus is less complex than its mammalian counterpart. 相似文献
The enzymatic synthesis of vicinal, dihalogenated products from alkenes and alkynes is described. The enzymatic reaction required an alkene or alkyne, dilute hydrogen peroxide, a haloperoxidase, and molar amounts of halide ions. Vicinal dichloro, dibromo, and diiodo products could be formed. A hydroxyl group on the carbon adjacent to the carbon-carbon double or triple bond lowered the halide ion concentration needed to produce the dihalo product. This reaction offers one explanation for the origin of natural, vicinal, dihalogenated products, such as those found frequently in marine microogranisms. 相似文献
Evidence is presented that a low dose of peripherally administered N, N-dipropylamino-5, 6-dihydroxytetralin (DiPr-5, 6-ADTN) specifically labels dopamine (DA) receptors in rat brain.Concentrations of this potent DA receptor agonist were determined by a highly selective method using reversed phase liquid chromatography and amperometric detection. The binding characteristics satisfy all criteria regarding saturability, stereospecificity, regional distribution and relation with pharmacological effects that are associated with DA receptor interactions. A rough estimation of the density of binding sites in the striatum resulted in values of 60–70 pmol/g. Lesioning the nigrostriatal pathway does not significantly alter the amount of ligand bound, nor do pretreatments with serotonergic, α-adrenergic or β-adrenergic antagonists. DiPr-5, 6-ADTN has thus been shown to be a useful ligand for labeling central DA receptors and a powerful tool in the study of DA-ergic mechanisms. 相似文献
Highly chlorophyllous photomixotrophic callus was visually selected from callus originating from soybean (Glycine max (L.) Merr. var. Corsoy) cotyledon. Suspension cultures initiated from this callus became photoautotrophic under continuous light with an atmosphere of 5% CO2 (balance air). Dry weight increases of 1000 to 1400% in the 2-week subculture period have been observed. The cellular Chl content ranged from 4.4 to 5.9 micrograms per milligram dry weight which is about 75 to 90% of the Chl content in soybean leaves under equivalent illumination (300 micro-Einsteins per square meter per second).
No growth can be observed in the dark in sucrose-lacking medium or in the presence of 0.5 micromolar 3-(3,4-dichlorophenyl)-1,1-dimethylurea, a concentration which does not inhibit heterotrophic growth (on sucrose). Photoautotrophic growth has an absolute requirement for elevated CO2 concentrations (>1%). During the 14-day subculture period, growth (fresh weight and dry weight) is logarithmic. Photosynthesis quickly increases after day 4, reaching a peak of 83 micromoles CO2 incorporated per milligram Chl per hour while dark respiration decreases 90% from day 2 to day 6. The pH of the growth medium quickly drops from 7.0 to 4.5 before slowly increasing to 5.0 by day 14. At this pH range and light intensity (200-300 microEinsteins per square meter per second), no O2 evolution could be detected although at high pH and light intensity O2 evolution was recorded.
Cultured fibroblasts of 13 patients with the Menkes syndrome and two with a new subtype (type IX) of the Ehlers-Danlos syndrome (E-D IX patients) showed many very similar abnormalities in their copper and collagen metabolism. Both cell types had markedly increased copper concentrations and 64Cu incorporation, and this cation accumulated in metallothionein or a metallothionein-like protein, as previously established for Menkes cells. Histochemical staining indicated that copper was distributed diffusely throughout the cytoplasm in both cell types, this location being consistent with the accumulation in metallothionein. Both fibroblast types also had markedly low lysyl oxidase activity and distinctly increased extractability of newly synthesized collagen, whereas no abnormalities were present in cell viability, duplication rate, prolyl 4-hydroxylase activity, or collagen synthesis rate. A high negative correlation (P less than 0.001) was found in the pooled group of Menkes and E-D IX cells between cellular copper concentration (r = 0.804) or 64Cu incorporation (r = 0.863) and the logarithm of lysyl oxidase activity. There was also a high positive correlation (P less than 0.001) between cellular copper concentration and incorporation (r = 0.869). One of the two E-D IX patients was also shown to have similar changes in lysyl oxidase activity and collagen extractability in the skin biopsy specimen, suggesting that the abnormalities observed in cultured cells are similar to those present in vivo. The only distinct abnormality found in the cells of the parents of the E-D IX patients was an increased 64Cu incorporation in those of the mother, this finding being consistent with X-linked inheritance of the disorder. 相似文献
Chlorella fusca can utilize the following substances as sole sulfur sources for growth: C1 to C8 n-alkane-1-sulfonates, linear alkylbenzenes sulfonates (LAS), -sulfonated fatty acid esters, polyethylene glycol sulfate and alkylsulfates. Good sulfur sources are alkylsulfonic acids, which are comparable to sulfate. Ethanesulfonic acid was used for comparison of the growth on sulfate and on a sulfonic acid, because best growth was achieved on this C2-sulfonic acid.Growth data of Chlorella on the enviromental important detergents linear alkylbenzene sulfonic acids, -sulfonated fatty acid methylester, Texapon and Sulfopon are presented. So far only microorganisms have been discussed as a source for degradation of sulfonic acids and detergents. It is suggested that green algae could be of similar importance for the biodegradation of these compounds.Abbreviations LAS
Linear alkylbenzene sulfonate
- ES
-sulfonated fatty acid methylester
- DTE
dithiocrythritol 相似文献
Summary Mutants of Escherichia coli K-12 previously isolated in the authors' laboratory have reduced arginyl-tRNA synthetase activity. The mutants fall into two classes. All mutants grow slowly on arginine-free medium. On arginine-supplemented medium some mutants grow at a normal rate (Class I) while others still grow slowly (Class II). Matings were performed to located a Class I and a Class II mutation on the E. coli chromosome map, and on the basis of our results we have assigned both to one locus, argS. 相似文献