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1.
A. H. W. Mendis A. Armson R. C. A. Thompson W. B. Grubb 《International journal for parasitology》1991,21(8):965-968
Live, intact third-stage larvae (L3s) of Strongyloides ratti in the absence of exogenous substrates consumed oxygen at a rate (E-QO2) of 181.8 ± 12.4 ng atoms min−1 mg dry weight−1 at 35°C. Respiratory electron transport (RET) Complex I inhibitor rotenone (2 μ
) produced 33 ± 6.5% inhibition of the E-QO2. Unusually the rotenone-induced inhibition was not relieved by 5 μ
-succinate. The E-QO2 of intact L3s was refractory to RET Complex III inhibitor antimycin A at 2 μ
; 4 μ
-antimycin inhibited ≤ 10% of the E-QO2. The electron donor couple ascorbate/TMPD augmented the E-QO2 in the presence of rotenone (2 μ
) and antimycin A (4 μ
) by 110%. Azide (1 m
) stimulated the antimycin A refractory QO2 by 36.6 ± 7.2% which was only partially inhibited by 1.0 m
-KCN (
). The data suggest the presence of classical (CPW) and alternate (APW) electron transport pathways in S. ratti L3s. 相似文献
2.
Jack Myers 《Photosynthesis research》1986,9(1-2):135-147
In the cyanobacterium Agmenellum quadruplicatum steady-state redox conditions were monitored in vivo for cytochrome (+c553) and P700 versus intensities of an actinic light 1 or light 2 (mainly absorbed by photosystems, and 2, respectively). Parallel measurements of O2 evolution were used to calibrate intensities for rates of electron transfer. Results show that the quality of actinic light (as light 1 or light 2) depends on intensity as well as wavelength. The contribution of electron flow from respiration is confirmed by observations of relative rate of photoreaction 1 estimated from Ip (intensity × fraction of P700 reduced). With 3,- (3,4-dichlorophenyl-1, 1-dimethylurea) (DCMU) the rate of photoreaction 1 depends upon, and is sensitive to small changes in, the rate of dark respiration. Very slow transient dark reductions of Cyt (f+c553) and P700 following any low intensity actinic light 1 are attributed to respiratory electron flow. Cyclic electron flow around photoreaction 1 cannot be large compared to dark respiration and cannot vary significantly with light intensity.This paper is contributed in honor of my longtime friend, L.N.M. Duysens, who has carried still further the eminence of the Dutch tradition in biophysics. 相似文献
3.
The electron-transport machinery in photosynthetic membranes is known to be very sensitive to heat. In this study, the rate of electron transport (ETR) driven by photosystem I (PSI) and photosystem II (PSII) during heat stress in the wild-type Synechocystis sp. strain PCC 6803 (WT) and its ndh gene inactiva-tion mutants ΔndhB (M55) and ΔndhD1/ndhD2 (D1/D2) was simultaneously assessed by using the novel Dual-PAM-100 measuring system. The rate of electron transport driven by the photosystems (ETRPSs) in the WT, M55, and D1/D2 cells incubated at 30℃ and at 55℃ for 10 min was compared. Incubation at 55℃ for 10 min significantly inhibited PSII-driven ETR (ETRPSII) in the WT, M55 and D1/D2 cells, and the ex-tent of inhibition in both the M55 and D1/D2 cells was greater than that in the WT cells. Further, PSI-driven ETR (ETRPSI) was stimulated in both the WT and D1/D2 cells, and this rate was increased to a greater extent in the D1/D2 than in the WT cells. However, ETRPSI was considerably inhibited in the M55 cells. Analysis of the effect of heat stress on ETRPSs with regard to the alterations in the 2 active NDH-1 complexes in the WT, M55, and D1/D2 cells indicated that the active NDH-1 supercomplex and medi-umcomplex are essential for alleviating the heat-induced inhibition of ETRPSII and for accelerating the heat-induced stimulation of ETRPSI, respectively. Further, it is believed that these effects are most likely brought about by the electron transport mediated by each of these 2 active NDH-1 complexes. 相似文献
4.
Dibromothymoquinone has been shown to inhibit light-induced cytochrome b reduction, and oxidation of succinate and NADH by chromatophores of Rhodopseudomonas capsulata. The half-inhibitory concentration of light-induced reactions and NADH oxidation is 2.5 M, but of succinate oxidation is 16 M. Hexane extraction inhibited oxidation of NADH and succinate equally. The results are interpreted to suggest that ubiquinone is concerned in all three processes described, but that the pools associated with NADH and succinate oxidation are not equally accessible to dibromothymoquinone.Abbreviations DBMIB
Dibromothymoquinone
- NADH
Reduced nicotinamide adenine dinucleotide
- Bchl
Bacteriochlorophyll 相似文献
5.
The cytochromeb
6/f complex of higher plant chloroplasts is uniformly distributed throughout both appressed and nonappressed thylakoids, in contrast to photosystem II and photosystem I, the other major membrane protein complexes involved in electron transport. We discuss how this distribution is likely to affect interactions of the cytochromeb
6/f complex with other electron transport components because of the resulting local stoichiometries, and how these may affect the regulation of electron transport. 相似文献
6.
Exposure of isolated chloroplasts of pea (Pisum sativum L.) to temperatures above 35° C leads to a stimulation of photosystem-I-mediated electron transport from dichlorophenolindophenol to methyl viologen. The threshold temperature for this stimulation coincides closely with that for heat-induced inhibition of photosystem-II activity in such chloroplasts. This coincidence is explained in terms of a rearrangement of the thylakoid membrane resulting in the exposure of a new set of donor sites for dichlorophenolindophenol within the cytochrome f/b
6 complex of the electron-transport chain linking the two photosystems.Abbreviations cyt
cytochrome
- DBMIB
2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone
- DCPIP (H2)
2,6-dichlorophenolindophenol
- EDAC
ethyldimethylaminopropyl-carbodiimide
- MV
methyl viologen
- PSI, II
photosystem I, II
- PCy
plastocyanin
- PQ(H2)
plastoquinone 相似文献
7.
Photosynthetic electron transport in thylakoids from cotton cultivars (Gossypium sp.) differing in tolerance to prometryn 总被引:1,自引:0,他引:1
A method to determine photosynthetic electron transport in thylakoid membranes is described for Gossypium barbadense (cv. Pima S-7) and G. hirsutum (cv. DP 5415). These cultivars differed markedly in tolerance to prometryn, a PS II inhibitor. The rates of photosynthetic electron transport obtained were 245 mole oxygen mg–1 chl h1. Plant age and leaf size influenced the activity of the thylakoid preparations. Thylakoids from leaves of plants 24 to 37 d and 50–70 mm in diameter had the highest activities; thylakoids from cotyledons, fully expanded leaves and young leaves had low activity. Thylakoids from both species had similar photosynthetic activities and I50's for prometryn, atrazine and diuron. Thus, tolerance to prometryn was not due to differential binding at D1 protein.Abbreviations PSII
photosystem II
- DAP
day after planting
- DQ
duroquinone
- DBMIB
dibromothymoquinone
- DMBQ
2,5-dimethyl-p-benzoquinone
- I50
concentration to inhibit reaction by 50%
- QA
quinone A
- QB
quinone B 相似文献
8.
Xiao Shuhua Peter J. Hotez Sen Binggui Liu Sen Qiang Huiqing Xue Haichou Zhan Bin Feng Zheng 《Parasitology international》2001,50(4)
The role of neutrophils in mediating host inflammation was examined in mice vaccinated with living third-stage infective hookworm larvae (L3). Mice were vaccinated by oral immunization with 500 L3 (Ancylostoma caninum) once every 2 weeks for a total of three immunizations. The vaccinated mice were then challenged intraperitoneally with 2000 L3, 1 week after the final immunization. To stimulate peritoneal production of neutrophils, 2 ml of 2% glycogen were injected intraperitoneally at 16 h prior to the challenge infection. Neutrophils were found to comprise 85% of the peritoneal cell population. L3 from the challenge infection were collected and then examined at timed intervals by inverted light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Greater than a fivefold increase in the total numbers of peritoneal cells was noted in the vaccinated mice as compared to unvaccinated mice. In the peritoneal cavity of vaccinated mice, the neutrophils adhered to the L3 within 2 h, and over 55% of the L3 were surround by clusters of neutrophils to form a sausage-like sheath 4 h later. At 24–72 h after challenge, almost all of the L3 recovered from the vaccinated mice were covered with thick clusters of cells. Both SEM and TEM demonstrated extensive ultrastructural damage to the L3. In contrast, the L3 recovered from the unvaccinated mice appeared to be unaffected by neutrophils. These studies suggest that neutrophils, like macrophages, can have an important role as effector cells in L3-vaccinated mice. 相似文献
9.
The I-D dip, an early transient of the fluorescence induction, was examined as a means to monitor redox changes of plastoquinone in cells of a cyanobacterium, Synechococcus sp. That the occurrence of the dip depends upon the reduced state of the plastoquinone pool was indicated by observations that 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone and 3-(3,4-dichlorophenyl)-1,1-dimethylurea did not affect the initial rise to I but abolished the subsequent decline from I to D and that illumination of the cells with light 1, prior to fluorescence measurements, eliminated the transient. The I-D dip was prominent in freshly harvested cells containing abundant endogenous substrates, disappeared slowly as the cells were starved by aeration but reappeared on addition of fructose to the starved cells in the dark. The dip that had been induced by a brief illumination of the starved cells with light 2 was rapidly diminished in the dark and KCN inhibited the dark decay of the transient. The results indicate that plastoquinone is reduced with endogenous as well as exogenous substrates and oxidized by a KCN-sensitive oxidase in the dark, thus providing strong support for the view that plastoquinone of photosynthetic electron transport also functions in respiration. In addition, the occurrence of a cyclic pathway of electrons from Photosystem I to plastoquinone, possibly via ferredoxin or NADP, was suggested. Several lines of evidence indicate that, under a strong light 2, Photosystem I-dependent oxidation of plastoquinone predominates over Photosystem II-dependent reduction of the quinone in the cyanobacterium which contains Photosystem I more abundantly than Photosystem II. 相似文献
10.
【目的】蜜蜂球囊菌(Ascosphaera apis,简称球囊菌)专性侵染蜜蜂幼虫而导致白垩病,危害蜜蜂健康和养蜂生产。本研究旨在探究中华蜜蜂(Apis cerana cerana,简称中蜂) 6日龄幼虫响应球囊菌胁迫的环状RNA(circular RNA,circRNA)差异表达谱及差异表达circRNA (differentially expressed circRNA,DEcircRNA)在宿主胁迫应答中的潜在功能。【方法】利用去除线性RNA的circRNA-seq技术对正常和球囊菌侵染的中蜂6日龄幼虫肠道(AcCK和AcT)进行测序。利用find_circ软件鉴定circRNA,统计circRNA的长度和环化类型。根据|log_2(Fold change)|≥1和P≤0.05的标准筛选DEcircRNA。将DEcircRNA的来源基因比对Gene ontology (GO)数据库和Kyoto Encyclopedia of Genes and Genomes (KEGG)数据库,从而获得功能及通路(pathway)注释。随机挑选3个DEcircRNA进行RT-qPCR验证。【结果】AcCK和AcT的circRNA-seq分别得到76342570和68269362条原始读段(raw reads),经严格质控得到74524108和66974392条有效读段(clean reads),Q30分别为92.75%和94%,GC含量分别为54.31%和54.90%。比对上东方蜜蜂(Apis cerana)参考基因组的短序列读段(anchor reads)共计23648400条。AcCK和AcT中分别鉴定到805和702个circRNA,长度均介于201–1000 nt,数量最多的环化类型均为已注释外显子circRNA,但分布在不同长度、不同环化类型的circRNA数量存在差异。AcCK vs AcT比较组共有494个DEcircRNA,包括257个上调circRNA和237个下调circRNA;上调和下调幅度最大的circRNA分别为novel_circ_000123和novel_circ_000726。上述DEcircRNA的来源基因可注释到11条生物学进程相关条目,9条分子功能相关条目,9条细胞组分相关条目,以及73条通路。进一步分析发现,部分DEcircRNA的来源基因注释到7条细胞免疫通路和3条体液免疫通路。【结论】中蜂6日龄幼虫响应球囊菌胁迫的过程中可能通过改变分布在不同长度和环化类型的circRNA数量,以及特异性表达一些circRNA和调节部分circRNA的表达量对病原产生应答;novel_circ_000027、novel_circ_000127、novel_circ_000312等DEcircRNA在宿主的胁迫应答过程中可能通过调控氧化磷酸化、细胞和体液免疫等通路发挥特殊作用。研究结果为深入理解中蜂幼虫对球囊菌的胁迫应答机制及二者的相互作用机制提供了新见解。 相似文献
11.
Flash-induced primary charge separation, detected as electrochromic absorbance change, the operation of the cytochrome b/f complex and the redox state of the plastoquinone pool were measured in leaves, protoplasts and open-cell preparations of tobacco (Nicotiana tabacum L.), and in isolated intact chloroplasts of peas (Pisum sativum L.). Addition of 0.5–5 mM KCN to these samples resulted in a large increase in the slow electrochromic rise originating from the electrogenic activity of the cytochrome b/f complex. The enhancement was also demonstrated by monitoring the absorbance transients of cytochrome f and b
6 between 540 and 572 nm. In isolated, intact chloroplasts with an inhibited photosystem (PS) II, low concentrations of dithionite or ascorbate rendered turnover of only 60% of the PSI reaction centers, KCN being required to reactivate the remainder. Silent PSI reaction centers which could be reactivated by KCN were shown to occur in protoplasts both in the absence and presence of a PSII inhibitor. Contrasting spectroscopic data obtained for chloroplasts before and after isolation indicated the existence of a continuous supply of reducing equivalents from the cytosol.Our data indicate that: (i) A respiratory electron-transport pathway involving a cyanide-sensitive component is located in chloroplasts and competes with photosynthetic electron transport for reducing equivalents from the plastoquinone pool. This chlororespiratory pathway appears to be similar to that found in photosynthetic prokaryotes and green algae. (ii) There is an influx of reducing equivalents from the cytosol to the plastoquinone pool. These may be indicative of a complex respiratory control of photosynthetic electron transport in higher-plant cells.Abbreviations and symbols A515
flash-induced electrochromic absorbance change at 515 nm
- DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- PS
photosystem
- SHAM
salicylhydroxamic acid 相似文献
12.
The transport of exogenous indol-3yl-acetic acid (IAA) from the apical tissues of intact, light-grown pea (Pisum sativum L. cv. Alderman) shoots exhibited properties identical to those associated with polar transport in isolated shoot segments. Transport in the stem of apically applied [1-14C]-or [5-3H]IAA occurred at velocities (approx. 8–15 mm·h-1) characteristic of polar transport. Following pulse-labelling, IAA drained from distal tissues after passage of a pulse and the rate characteristics of a pulse were not affected by chases of unlabelled IAA. However, transport of [1-14C]IAA was inhibited through a localised region of the stem pretreated with a high concentration of unlabelled IAA or with the synthetic auxins 1-napthaleneacetic acid and 2,4-dichlorophenoxyacetic acid, and label accumulated in more distal tissues. Transport of [1-14C]IAA was also completely prevented through regions of the intact stem treated with N-1-naphthylphthalamic acid (NPA) and 2,3,5-triiodobenzoic acid.Export of IAA from the apical bud into the stem increased with total concentration of IAA applied (labelled+unlabelled) but approached saturation at high concentrations (834 mmol·m-3). Transport velocity increased with concentration up to 83 mmol·m-3 IAA but fell again with further increase in concentration.Stem segments (2 mm) cut from intact plants transporting apically applied [1-14C]IAA effluxed 93% of their initial radioactivity into buffer (pH 7.0) in 90 min. The half-time for efflux increased from 32.5 to 103.9 min when 3 mmol·m-3 NPA was included in the efflux medium. Long (30 mm) stem sections cut from immediately below an apical bud 3.0 h after the apical application of [1-14C]IAA effluxed IAA when their basal ends, but not their apical ends, were immersed in buffer (pH 7.0). Addition of 3 mmol·m-3 NPA to the external medium completely prevented this basal efflux.These results support the view that the slow long-distance transport of IAA from the intact shoot apex occurs by polar cell-to-cell transport and that it is mediated by the components of IAA transmembrane transport predicted by the chemiosmotic polar diffusion theory.Abbreviations IAA
indol-3yl-acetic acid
- 2,4-D
2,4-dichlorophenoxyacetic acid
- NAA
1-naphthaleneacetic acid
- NPA
N-1-naphthylphthalamic acid
- TIBA
2,3,5-triiodobenzoic acid 相似文献
13.
Stachys recta L. is a very polymorphous species in which numerous subspecies were recognised. S. recta L. subsp. serpentini (Fiori) Arrigoni is a typical endemism growing on serpentine soils in northern Apennines and particularly in Tuscany (Italy). In order to contribute to a better knowledge of this plant and to its differentiation with respect to S. recta L. subsp. recta, the micromorphological characters (non-glandular and glandular trichomes) and the essential oil composition of the two subspecies were investigated. Micromorphological characters were studied using scanning and transmission electron microscopy, while light microscopy was used for histochemical observations. Essential oil analysis was carried out by gas chromatography and mass spectrometry.In the two examined taxa, the morphology and distribution of glandular and non-glandular trichomes, and the different essential oil composition, may be considered distinctive characters at subspecies level. This is consistent with the taxonomic classification considering S. recta subsp. serpentini a subordinate taxon of S. recta. 相似文献
14.
[目的] 探明黄带犀猎蝽成虫对斜纹夜蛾幼虫的捕食潜力。[方法] 在室内条件下,研究了黄带犀猎蝽对斜纹夜蛾2、3、4龄幼虫的捕食功能反应、搜寻效应和干扰反应。[结果] 黄带犀猎蝽成虫对斜纹夜蛾2、3、4龄幼虫的捕食功能反应模型均符合Holling II型,即其捕食量随猎物密度的增加而增加,其搜寻效应随猎物密度的增加而减小,HollingⅡ方程依次为:Na=0.9750N/(1+0.0273N)、Na=1.1654N/(1+0.0804N),Na=1.3058N/(1+0.1799N);黄带犀猎蝽成虫自身密度干扰反应符合HasseⅡ型(E=0.337P-0.565),即随着自身密度的增加,平均捕食量逐渐减少,捕食作用率逐渐降低。[结论] 黄带犀猎蝽成虫对斜纹夜蛾幼虫有较好的防治潜力,可用于斜纹夜蛾的生物防治中。 相似文献
15.
Günter A. Peschek 《Archives of microbiology》1980,125(1-2):123-131
Respiratory particles from hydrogen-grown Anacystis nidulans were found to oxidize H2, NADPH, NADH, succinate and ascorbate plus N,N,N,N-tetramethyl-p-phenylenediamine at rates corresponding to 28, 15, 6, 2.5, and 70 nmol O2 taken up x mg protein–1xmin–1, respectively. The particles were isolated by brief sonication of lysozyme-pretreated cells. Respiratory activities were studied in terms of both substrate oxidation and O2 uptake. The stoichiometry between oxidation of H2, NADPH, NADH or succinate, and consumption of O2 was calculated to be 1.95+-0.1 with each substrate.Inhibitors of flavoproteins did not affect the oxyhydrogen reaction while 2-n-heptyl-8-hydroxyquinoline-N-oxide as well as compounds known to block the terminal oxidase impaired the oxidation of both H2 and of NAD(P)H or succinate in a parallel fashion. No additivity of O2 uptake was observed when NADPH, NADH or succinate was present in addition to H2. Instead, H2 uptake was depressed under such conditions, and also the oxidation of NAD(P)H or succinate was increasingly lowered by increasing H2 tensions.The results suggest that in Anacystis molecular hydrogen is oxidized through the same type of respiratory chain as are NAD(P)H and succinate. Moreover, the cyanide-resistant branch of respiratory O2 uptake will be discussed, and a few results obtained with particles prepared from thylakoid-free Anacystis will also be presented.Abbreviations BAL
2,3-dimercaptopropanol-(1)
- DCPIP
2,6-dichlorophenolindophenol
- HOQNO
2-n-heptyl-8-hydroxyquinoline-N-oxide
- TMPD
N,N,N,N-tetramethyl-p-phenylenediamine
- tricine
N-tris-(hydroxymethyl)-methylglycine
- Tris
tris-(hydroxymethyl)-aminomethane
- TTFA
thenoyltrifluoroacetone
NAD(P)H indicates NADPH and/or NADH 相似文献
16.
【目的】明确蠋蝽对茄二十八星瓢虫的捕食能力。【方法】在实验室条件下测定蠋蝽5龄若虫对茄二十八星瓢虫2和4龄幼虫的捕食功能反应及搜寻效应。【结果】蠋蝽5龄若虫对茄二十八星瓢虫2和4龄幼虫的捕食行为均符合Ⅱ型功能反应;随着茄二十八星瓢虫密度的增加,蠋蝽的搜寻效应逐渐降低,蠋蝽5龄若虫对茄二十八星瓢虫2龄幼虫的搜寻效应明显大于4龄幼虫;蠋蝽5龄若虫对茄二十八星瓢虫2和4龄幼虫的实际最大捕食量分别为15和10头。【结论】蠋蝽5龄若虫对茄二十八星瓢虫幼虫具有较好的捕食作用。 相似文献
17.
Functional response of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) to Aphis gossypii Glover (Homoptera: Aphididae) in the Laboratory 总被引:1,自引:0,他引:1
Stage specific functional response of Harmonia axyridis (Pallas) to varying densities of Aphis gossypii Glover was examined in a simplified cucumber leaf arena under laboratory conditions. All stages of H. axyridis were isolated individually for 24 h with different prey densities at 25 °C and a photoperiod of 16:8 (L:D) h. The number of prey consumed by the predator was checked at 3, 6, 12, and 24 h. All stages of H. axyridis showed a Type II functional response. Based on the random predator equation, estimated attack rates of H. axyridis at 24 h were 0.0037, 0.0442, 0.3590, 0.3228, and 0.1456, and estimated handling times were 4.1001, 2.4575, 0.7500, 0.2132, and 0.1708 h for the first, second, third, and fourth instars, and female adult, respectively. 相似文献
18.
天然免疫系统是多细胞生物抵抗各种入侵微生物的第一道防线.Notch途径介导相邻细胞之间的相互作用,调节细胞、组织、器官的分化和发育.为了进一步探索Notch信号途径在果蝇天然免疫中的功能,利用Notch途径下游基因Su(H)和E(spl)的低表达突变体果蝇,通过体外注射病原体分析了生存率、血细胞的噬菌功能和抗菌肽的表达量以及突变体的血细胞数量.结果表明,革兰氏阴性细菌和真菌感染后果蝇E(spl)突变体的生存率、噬菌能力及抗菌肽的表达量明显降低,而且幼虫期血细胞出现异常增殖;Su(H)突变体只对真菌表现出敏感性,抗菌肽的表达量降低,但是对真菌的噬菌能力正常.此结果表明,Notch途径不仅影响个体的生长发育,而且在果蝇天然免疫中也起重要的调节作用. 相似文献
19.
原绿球藻(Prochlorococcus)作为海洋丰度最高的浮游植物,对海洋生态系统的物质循环和能量流动起着重要的驱动作用。原绿球藻生长和光合作用活性容易受到环境胁迫的影响,进而影响整个海洋生态系统的稳定性。因此,研究原绿球藻应对环境胁迫的响应机制具有重要的生态意义。原绿球藻主要通过分化出不同的生态型来适应不同光照和营养盐的海洋环境,但仍然会很难快速适应各种突如其来的海洋环境变化。本文从原绿球藻应对环境胁迫的角度,探讨了其生理和分子响应机制的最新研究进展,包括光系统I循环电子传递在光照变化时发挥的重要作用,通过RNA快速响应而调控基因表达应对环境胁迫,以及在辅助异养细菌的保护下应对活性氧的胁迫等。本文也展望了原绿球藻对环境胁迫响应的生理和分子机制的未来研究方向,旨在为原绿球藻抗逆机制的深入研究提供参考。 相似文献