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1.
2.
Werner Eckert 《Biogeochemistry》1987,4(1):15-26
The process of H2S oxidation by the phototrophic bacteriaThiocapsa roseopersicina andChlorobium phaeobacteroides, respectively, was monitored using a Pt-glass-Ag0, Ag2S electrode combination without liquid junction. Due to the resulting pe(pH) and pH2S plottings three steps can be distinguished: oxidation of H2S to an S(0) state, oxidation of S (0) to SO4
2–, and oxidation of the remaining H2S directly to SO4
2–. Differences between the investigated bacteria exist with respect to their individual oxidation strategies.Thiocapsa apparently stops oxidizing H2S at pH2S 7.5 (e.g. 10–7.5M H2S) and shifts to the utilization of the intracellularly stored S (0). In contrastChlorobium utilizes its extracellularly stored sulfur parallel to the extracellular H2S fraction. The corresponding Pt-sensor responses (pe7 values) were found to be similar to the corresponding partial redox equilibria (p7 values) of H2S oxidation stoichiometries as proposed by Van Niel (1931) and Trüper (1964). It is concluded that the recording of pe enables investigators to understand (and control) in situ redox processes, independent of their thermodynamic equilibration, only bound to changes of electroactivity vs. sensor. 相似文献
3.
4.
Carbon disulfide (CS2) and carbonyl sulfide (COS) are colorless, foul-smelling, volatile sulfur compounds with biocidal properties. Some plants produce CS2 or COS or both. When used as an intercrop or forecrop, these plants may have agronomic potential in protecting other plants. Most of the factors which affect production of these plant-generated organic sulfides are unknown. We determined the effects of sulfate concentration, plant age, nitrogen fixation, drought stress, root injury (through cutting), and undisturbed growth on COS production in Leucaena retusa or Leucaena leucocephala and the effect of some of these factors on CS2 production in Mimosa pudica. In addition, we determined if organic sulfides were produced in all Leucaena species. When L. retusa and M. pudica seedlings were grown in a plant nutrient medium with different sulfate concentrations (50 to 450 mg SL-1), COS or CS2 from crushed roots generally increased with increasing sulfate concentration. COS production was highest (74 ng mg-1 dry root) for young L. retusa seedlings and declined to low amounts (<5 ng mg-1 dry root) for older seedlings. Nitrogen fixation reduced the amounts of COS or CS2 produced in L. leucocephala and M. pudica. Under conditions of undisturbed growth, root cutting, or drought stress, no COS production was detected in 4-to 8-weeks-old L. retusa plants. COS or CS2 or both was obtained from crushed roots or shoots of all 13 known Leucaena species. 相似文献
5.
Cornelia Herschbach L. J. De Kok H. Rennenberg 《Plant biology (Stuttgart, Germany)》1995,108(1):41-46
Spinach plants (Spinacea oleracea L. cv. Estivato) were grown on nutrient solutions under deficient, normal and excess sulfate supply. In both young and mature plants net uptake of sulfate and its transport to the shoot increased with increasing sulfate supply, but both processes proceeded at a higher rate in young as compared to mature plants. The relative sulfate transport, i.e. the relative amount of the sulfate taken up that is transported to the shoot, decreased with increasing sulfate supply. Apparently, net uptake of sulfate is not strictly controlled by the sulfur demand of the shoot, but xylem loading appears to counteract excess transport of sulfate to the shoot. Fumigation with H2S or SO2 reduced net uptake of sulfate by the roots in sulfur-deficient plants and absolute as well as relative sulfate transport to the shoot independent of the three sulfate levels supplied to the plant. At the same time thiol contents of the shoot and the root were enhanced by fumigation with H2S and SO2. These findings are consistent with the idea that thiols produced in the leaves can mediate demand-driven control of sulfate uptake by the roots and its transport to the shoot. 相似文献
6.
Fourteen lichens, 10 green algal lichens and four cyanolichens, as well as a cyanobacterium emitted significant quantities of H2S (0.01–0.04 pmol g dw–1 s–1) and DMS (0.005–0.025 pmol g dw–1 s–1) but were sinks for COS (0.015–0.14 pmol g dw–1 s–1). In contrast, exchange of CH3SH and CS2 were sporatic and inconsistent. Although some interspecific variation occurred for the first three gases, exchange rates were relatively uniform and were not influenced by irradiance conditions. In contrast to DMS and H2S emission, COS uptake was strongly influenced by degree of thallus hydration. Because lichen dominated systems cover extensive terrestrial habitats, COS uptake is potentially important in the world's sulfur budget. 相似文献
7.
Kan Shida Kotaro Takamizawa Masato Nagaoka Takao Tsuji Toshiaki Osawa 《Microbiology and immunology》1994,38(4):273-279
The binding of Escherichia coli heat-labile enterotoxin (LT) type I to glycosylated proteins with lactose (Galβ1-4Glc) by amino carbonyl reaction was studied by the Western blot assay and by the microtiter well binding assay. LT bound to a lactose-α-lactalbumin amino carbonyl product (Lac-LA), whereas cholera toxin did not. The binding ability of Lac-LA was abolished by β-galactosidase treatment, indicating that the terminal galactose is essential for the binding of LT. The binding of LT to Lac-LA was inhibited by galactose and lactose, and most effectively inhibited by lactulose (Galβ1-4Fru), which is a structural analog of the Amadori rearrangement product of the amino carbonyl reaction between lactose and an ε-amino group of a lysine residue (lactuloselysine). The results suggest that LT recognizes the portion of lactuloselysine in Lac-LA. LT also bound to a melibiose (Galα1-6Glc)-α-lactalbumin amino carbonyl product (Mel-LA), but the binding ability of Mel-LA was weaker than that of Lac-LA, suggesting that the β1-4 linked terminal galactose is dispensable but preferable for the binding. Furthermore, LT bound to the amino carbonyl products of lactose with β-lactoglobulin, caseins, bovine serum albumin, and ovalbumin. These results indicate that LT binds to the amino carbonyl products between proteins and sugars containing the terminal galactose, such as lactose. 相似文献
8.
Dennis A. Bazylinski Anthony J. Garratt-Reed Afshin Abedi Richard B. Frankel 《Archives of microbiology》1993,160(1):35-42
Greigite (Fe3S4) and pyrite (FeS2) particles in the magnetosomes of a many-celled, magnetotactic prokaryote (MMP), common in brackish-to-marine, sulfidic, aquatic habitats, contained relatively high concentrations of copper which ranged from about 0.1 to 10 atomic per cent relative to iron. In contrast, the greigite particles in the magnetosomes of a curved magnetotactic bacterium collected from the same sampling site did not contain significant levels of copper. The ability of the MMP to biomineralize copper within its magnetosomes appeared to be limited to that organism and dependent upon the site from which it was collected. Although the chemical mechanism and physiological function of copper accumulation in the magnetosomes of the MMP is unclear, the presence of copper is the first evidence that another transition metal ion could be incorporated in the mineral phase of the magnetosomes of a magnetotactic bacterium.Abbreviation MMP
many-celled magnetotactic prokaryote 相似文献
9.
David W. Ow 《In vitro cellular & developmental biology. Plant》1993,29(4):213-219
Summary Plants and certain fungi respond to heavy metal toxicity with the induced synthesis of metal-binding peptides known as phytochelatins
(PCs). With cadmium, PCs can bind the metal to form a low molecular weight PC-Cd complex and a high molecular weight PC-Cd-S2− complex. The sulfide ions enhance the stability and Cd-binding capacity of the metal chelate, and formation of this sulfide-containing
complex is associated with enhanced tolerance to cadmium. Molecular analyses of two fission yeast mutants that fail to produce
a wild type level of the PC-Cd-S2− complex have determined that a vacuolar membrane transporter and several enzymes of the purine biosynthesis pathway are necessary
in vivo for formation of the PC- Cd-S2− complex. A model based on vacuolar sequestration of the PC-Cd complex by an ATP-binding cassette-type transporter and its
subsequent maturation into the stable PC-Cd-S2− complex via the actions of two purine biosynthetic enzymes is described.
Presented in the Session-in-Depth Bioremediation through Biotechnological Means at the 1993 Congress on Cell and Tissue Culture,
San Diego, CA, June 5–9, 1993. 相似文献
10.
Nitrosoglutathione (GSNO) and β-cyclodextrin (β-CD) exhibit positive roles in regulating fruit quality. However, there are few reports about the effects of GSNO and β-CD on enhancing storability and boosting nitric oxide (NO), hydrogen sulfide (H2S), and phenylpropane metabolism in fruits during storage. “Xintaihong” peach were treated with 0.5, 1.0, 1.5 mmol L−1 GSNO in 0.5% (w/v) β-CD solution (GSNO/β-CD). The effects of GSNO/β-CD on endogenous NO, H2S, and phenylpropane metabolism were investigated. Treatment with GSNO/β-CD increased the color difference of peach and inhibited the increase of respiratory intensity, weight loss, and relative conductivity. Treatment with 1.0 mmol L−1 GSNO/β-CD increased the nitric oxide synthase (NOS-like) activity and L-arginine content, thereby promoting the accumulation of endogenous NO. By improving the activities of L-cysteine desulfhydrylase (L-CD), O-acetylserine sulfur lyase (OAS-TL), serine acetyltransferase (SAT), GSNO/β-CD increased the content of endogenous H2S in peach. Treatment with GSNO/β-CD increased the activities of phenylalanine ammonia-lyase (PAL), 4-coumarate-CoA ligase (4CL), and cinnamic acid-4-hydroxylase (C4H), promoted the increase of total phenols, flavonoids, and lignin in peach. These results indicated that GSNO/β-CD treatment better maintained the quality of peach by improving the metabolism of endogenous NO, H2S, and phenylpropane during storage. 相似文献