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11.
Mark L. Paddock Scott H. Rongey Edward C. Abresch George Feher Melvin Y. Okamura 《Photosynthesis research》1988,17(1-2):75-96
Many herbicides that inhibit photosynthesis in plants also inhibit photosynthesis in bacteria. We have isolated three mutants of the photosynthetic bacterium Rhodobacter sphaeroides that were selected for increased resistance to the herbicide terbutryne. All three mutants also showed increased resistance to the known electron transfer inhibitor o-phenanthroline. The primary structures of the mutants were determined by recombinant DNA techniques. All mutations were located on the gene coding for the L-subunit resulting in these changes Ile229 Met, Ser223 Pro and Tyr222 Gly. The mutations of Ser223 is analogous to the mutation of Ser264 in the D1 subunit of photosystem II in green plants, strengthening the functional analogy between D1 and the bacterial L-subunit. The changed amino acids of the mutant strains form part of the binding pocket for the secondary quinone, Q
b
. This is consistent with the idea that the herbicides are competitive inhibitors for the Q
b
binding site. The reaction centers of the mutants were characterized with respect to electron transfer rates, inhibition constants of terbutryne and o-phenanthroline, and binding constants of the quinone UQ0 and the inhibitors. By correlating these results with the three-dimensional structure obtained from x-ray analysis by Allen et al. (1987a, 1987b), the likely positions of o-phenanthroline and terbutryne were deduced. These correspond to the positions deduced by Michel et al. (1986a) for Rhodopseudomonas viridis.Abbreviations ATP
adenosine 5-triphosphate
- Bchl
bacteriochlorophyll
- Bphe
bacteriopheophytin
- bp
basepair
- cyt c2+
reduced form of cytochrome c
- DEAE
diethylami-noethyl
- EDTA
ethylenediamine tetraacetic acid
- Fe2+
non-heme iron atom
- LDAO
lauryl dimethylamine oxide
- Pipes
piperazine-N,N-bis-2-ethane-sulfonic acid
- PSII
photosystem II
- RC
reaction center
- SDS
sodium dodecylsulfate
- Tris
tris(hydroxy-methyl)aminomethane
- UQ0
2,3-dimethoxy-5-methyl benzoquinone
- UQ10
ubiquinone 50 相似文献
12.
13.
Summary A one hour exposure to 3 M amiprophos-methyl (APM) depolymerizes all MT arrays in cells from higher plant suspension cultures. On removal of APM, MT repolymerization sites are detected using immunofluorescent staining. During interphase, Mt arrays return uniformly dispersed across the cell cortex with transverse arrays in elongated cells and random arrays in isodiametric cells. During cell division, MT arrays return as follows: Prophase-MT arrays return in association with the nuclear envelope. Metaphase-MTs return associated with chromosomes. Teleophase-MTs return in apparent association with the reforming nuclear envelope and as aberrant phragmoplasts. MTOCs in higher plant cells may be membrane associated at many stages in the cell cycle. Isolated, condensed chromosomes are capable of nucleating MTs, which can attain small, spindle-like configurations.Abbreviations APM
Amiprophos-methyl
- MT
Microtubule
- MTOC
Microtubule organizing center
- NS
Nucleating site 相似文献
14.
Rapid and simple isolation of pure photosystem II core and reaction center particles from spinach 总被引:2,自引:2,他引:0
Peter J. van Leeuwen Maaike C. Nieveen Erik Jan van de Meent Jan P. Dekker Hans J. van Gorkom 《Photosynthesis research》1991,28(3):149-153
Pure and active oxygen-evolving PS II core particles containing 35 Chl per reaction center were isolated with 75% yield from spinach PS II membrane fragments by incubation with n-dodecyl--D-maltoside and a rapid one step anion-exchange separation. By Triton X-100 treatment on the column these particles could be converted with 55% yield to pure and active PS II reaction center particles, which contained 6 Chl per reaction center.Abbreviations Bis-Tris
bis[2-hydroxyethyl]imino-tris[hydroxymethyl]methane
- Chl
chlorophyll
- CP29
Chl a/b protein of 29 kDa
- Cyt b
559
cytochrome b
559
- DCBQ
2,5-dichloro-p-benzo-quinone
- LHC II
light-harvesting complex II, predominant Chl a/b protein
- MES
2-[N-Morpholino]ethanesulfonic acid
- Pheo
pheophytin
- PS H
photosystem II
- QA
bound plastoquinone, serving as the secondary electron acceptor in PS II (after Pheo)
- SDS
sodiumdodecylsulfate 相似文献
15.
用免疫细胞化学技术观察了单眼剥夺后金黄地鼠视觉中枢GABA神经元分布的变化。结果表明:单眼剥夺后,金黄地鼠视皮层和上丘的GABA阳性神经元暂时性增多,但剥夺后六个月,其数目显著减少。在单眼剥夺前和剥夺后侧膝体中GABA阳性神经元数目没有明显差异。剥夺眼对侧视皮层GABA阳性神经元数比剥夺眼同侧视皮层GABA神经元数目少。单眼剥夺后视觉中枢GABA神经元类型及形态与剥夺前没有差别。晚期单眼剥夺也能引起视觉中枢GABA神经元数量和分布的变化。以上结果表明,单眼剥夺后视觉中枢抑制神经元的结构发生了变化。 相似文献
16.
The effects of a single does of LiCl (2.5 or 10 mEq/kg) on brain inositol and inositol-1-phosphate (Ins1P), intermediates of brain phosphoinositude (PI) turnover, were determinated in male Han: Wistar rats. There was a remarkable, 36–58 fold elevation of brain Li+ as the single does of LiCl was increased 4-fold. Moreover, the accumulation of brain lithium was slow during repeated administration of LiCl. Brain lithium did not correlate with changes in brain PI turnover either after a single or repeated doses. Thus, after a single does of LiCl the increases in brain Ins1P were much less than the decreases in brain inositol. Also, brain inositol was significantly decreased only with the high dose of LiCl whereas brain Ins1P accumulation was more prominent with the lower dose. Moreover, repeated daily doses of LiCl only transiently increased brain Ins1P at 1 and 7 d whereas inositol remained at control levels throughout the 14 d observation period. Lithium probably caused the transient decrease in brain inositol by inhibiting several enzymes, in addition to the inhibition of myo-inositol mono-phosphates, in the PI cycle. Moreover, a slow dampening down of PI turnover by lithium, possible via an inhibitory action on G-protein-coupling, may also explain the present findings. 相似文献
17.
The effect of naloxone-precipitated withdrawal after acute morphine was studied on the concentrations of noradrenaline (NA), 4-hydroxy-3-methoxyphenylethyleneglycol (MHPG), dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), and on the metabolite/parent amine ratios MHPG/NA, DOPAC/DA and HVA/DA, in eight regions of the guineapig brain. Guinea-pigs were treated with a single dose of morphine sulphate (15 mg/kg s.c.) or saline (control) and 2h later with naloxone hydrochloride (15 mg/kg s.c.) to precipitate withdrawal. The animals were decapitated at 0.5 h or 1 h after naloxone injections and their brains analysed for monoamine concentrations by HPLC-ECD. At 0.5 h after naloxone-precipitated withdrawal NA and MHPG levels, and the MHPG/NA ratio, were increased in the hypothalamus, and the NA levels were increased in the hypothalamus, medulla/pons and cortex 1 h after naloxone. Naloxoneprecipitated withdrawal also produced increased DA metabolism in the cortex, midbrain and medulla 0.5 h later, and in the cortex, hypothalamus and striatum 1 h later. Hence naloxone-precipitated withdrawal from acute morphine treatment produced a complex pattern of increased synthesis and metabolism of NA and DA which varied over time and with the brain region examined. 相似文献
18.
The optical spectra of the reaction center (RC) of Rhodopseudomonas viridis including absorption (A), linear dichrosism (LD), circular dichroism (CD), absorption-detected magnetic resonance (ADMR) and its linear dichroism (LD-ADMR) are simulated by an exciton model. It involves the Qy transitions of six prosthetic groups: four (bacteriochlorophyll-b molecules, two bacteriopheophytin-b molecules and the Soret bands By of the special-pair pigments, which couple most strongly with the corresponding Qy transitions. For the ADMR-spectra additional excitations of the special-pair triplet are introduced. While interactions between the Qy transitions and the By transitions are in principle determined from the structural arrangement of the pigments, the interactions to the other states are adjusted to fit the spectral features for the various transitions. The interaction of the newly introduced states are interpreted in terms of a simple model. 相似文献
19.
在麻醉猫,经推动脉注入梭曼、VX,沙林及乙酰甲胆碱引起呼吸中枢严重抑制的剂量分别为0.5—1、3、15、2001μg/头;但在无麻醉、箭毒麻痹、人工呼吸并用药物保护循环的清醒猫,VX用量要增加十多倍,沙林用量增加2~8倍,棱曼用量不变。在严重抑制剂量的给药早期,梭曼使34.8%动物较早地出现膈神经单纤维放电加强,其每次吸气放电的冲动频率由20~30Hz增至50~80Hz,冲动个数由15~25个/每次放电增至40~60个/每次放电,兴奋持续短、迅速转入抑制且不易自动恢复;VX和乙酰甲胆碱使100%动物出现显著的放电加强,其冲动频率由20~30Hz增至70~130Hz、冲动个数由15~25个/每次放电增至60~80个/第次放电,兴奋持续时间较长、转入抑制慢但自动恢复较快;沙林使76.9%动物出现放电加强,其他表现类似VX。三种胆碱酯酶抑制剂和乙酰甲胆碱共使33/52根单纤维放电发生时相变化。结果表明:梭曼对呼吸中枢作用最强、沙林次之、VX最弱且更似乙酰甲胆碱。 相似文献
20.
An oxygen-evolving complex has been highly purified from the thermophilic cyanobacterium Synechococcus sp. The complex, which reproducibly showed 5 major polypeptide bands of 47, 40, 35, 30 and 9 kDa on SDS-polyacrylamide gel electrophoresis and contained 3.2 Mn per QA, had an oxygen-evolving activity of 300–400 μmol/mg chl per h in the presence of 5 mM MnCl2; or CaCl2. The complex most likely represents a minimum functional unit of the photosynthetic oxygen evolution. 相似文献