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411.
大鼠肺泡巨噬细胞的更新时间 总被引:1,自引:0,他引:1
在估算吸入放射性核索致肺巨噬细胞的剂量以及分析有害因子对它的损伤效应时,肺泡巨噬细胞的更新时间是重要的生物参数。本文用颈静脉点滴的方法给大鼠注入~3H-TdR,剂量为4.64×10~4Bq/g体重,在注入后1—41天期间分批活杀,用0.02%EDTA-PBS洗肺获取肺泡巨噬细胞,用放射自显影方法测定标记的肺泡巨噬细胞%。注入后1天标记细胞为5.1%,第5天达峰值8.4%,以后随时间延长,标记细胞%降低,到41天降至0.6%。标记细胞%与注入后时间之间的关系,可拟合二项指数函数,相关系数0.9990。56%的细胞更新一半的时间为0.9天,44%的细胞为14天。文内还就本实验得到的结果与国外报道的资料进行了比较与讨论。 相似文献
412.
Mathilde Chomel Jocelyn M. Lavallee Nil Alvarez‐Segura Francisco de Castro Jennifer M. Rhymes Tancredi Caruso Franciska T. de Vries Elizabeth M. Baggs Mark C. Emmerson Richard D. Bardgett David Johnson 《Global Change Biology》2019,25(10):3549-3561
Theory suggests that more complex food webs promote stability and can buffer the effects of perturbations, such as drought, on soil organisms and ecosystem functions. Here, we tested experimentally how soil food web trophic complexity modulates the response to drought of soil functions related to carbon cycling and the capture and transfer below‐ground of recent photosynthate by plants. We constructed experimental systems comprising soil communities with one, two or three trophic levels (microorganisms, detritivores and predators) and subjected them to drought. We investigated how food web trophic complexity in interaction with drought influenced litter decomposition, soil CO2 efflux, mycorrhizal colonization, fungal production, microbial communities and soil fauna biomass. Plants were pulse‐labelled after the drought with 13C‐CO2 to quantify the capture of recent photosynthate and its transfer below‐ground. Overall, our results show that drought and soil food web trophic complexity do not interact to affect soil functions and microbial community composition, but act independently, with an overall stronger effect of drought. After drought, the net uptake of 13C by plants was reduced and its retention in plant biomass was greater, leading to a strong decrease in carbon transfer below‐ground. Although food web trophic complexity influenced the biomass of Collembola and fungal hyphal length, 13C enrichment and the net transfer of carbon from plant shoots to microbes and soil CO2 efflux were not affected significantly by varying the number of trophic groups. Our results indicate that drought has a strong effect on above‐ground–below‐ground linkages by reducing the flow of recent photosynthate. Our results emphasize the sensitivity of the critical pathway of recent photosynthate transfer from plants to soil organisms to a drought perturbation, and show that these effects may not be mitigated by the trophic complexity of soil communities, at least at the level manipulated in this experiment. 相似文献
413.
Atmospheric CO2 mole fraction affects stand‐scale carbon use efficiency of sunflower by stimulating respiration in light
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Xiao Ying Gong Rudi Schäufele Christoph Andreas Lehmeier Guillaume Tcherkez Hans Schnyder 《Plant, cell & environment》2017,40(3):401-412
Plant carbon‐use‐efficiency (CUE), a key parameter in carbon cycle and plant growth models, quantifies the fraction of fixed carbon that is converted into net primary production rather than respired. CUE has not been directly measured, partly because of the difficulty of measuring respiration in light. Here, we explore if CUE is affected by atmospheric CO2. Sunflower stands were grown at low (200 μmol mol?1) or high CO2 (1000 μmol mol?1) in controlled environment mesocosms. CUE of stands was measured by dynamic stand‐scale 13C labelling and partitioning of photosynthesis and respiration. At the same plant age, growth at high CO2 (compared with low CO2) led to 91% higher rates of apparent photosynthesis, 97% higher respiration in the dark, yet 143% higher respiration in light. Thus, CUE was significantly lower at high (0.65) than at low CO2 (0.71). Compartmental analysis of isotopic tracer kinetics demonstrated a greater commitment of carbon reserves in stand‐scale respiratory metabolism at high CO2. Two main processes contributed to the reduction of CUE at high CO2: a reduced inhibition of leaf respiration by light and a diminished leaf mass ratio. This work highlights the relevance of measuring respiration in light and assessment of the CUE response to environment conditions. 相似文献
414.
On the Cytochemistry of Cell Wall Formation in Poplar Trees 总被引:2,自引:0,他引:2
Abstract: The ultrastructure of cell walls and the mechanisms of cell wall formation are still not fully understood. The objective of our study was therefore to obtain additional fine structural details on the deposition of cell wall components during the differentiation of xylem cells in hybrid aspen ( Populus tremula L. × P. tremuloides Michx.) we used as a model tree. At the electron microscope level, PATAg staining revealed a successive deposition of polysaccharides with increasing distance from the cambium. Staining with potassium permanganate and UV microspectrophotometry showed that the cell walls were lignified, with some delay to the deposition of polysaccharides. Immunogold labelling of three lignin types in developing cell walls varied with progressive deposition of cell wall layers. Condensed lignin subunits were localized in corners of cells adjacent to the cambium prior to S1 formation, whereas non-condensed lignin subunits became labelled only in later stages - in secondary walls near cell corners and simultaneously with the completion of S1 formation. As S2 polysaccharide deposition progressed, the labelling extended towards the lumen. Labelling of peroxidases revealed their presence in cell corner regions of young xylem cells, still lacking a secondary wall, implying that peroxidases are incorporated into the developing cell wall at early developmental stages. A weak labelling of middle lamella regions and secondary walls could also be seen at later stages. The results are discussed in relation to current knowledge on the succession of polysaccharide and lignin deposition in woody cell walls. 相似文献
415.
In this study we describe the synthesis and characterisation of a new hydrazone-based fluorescent compound that is able to selectively label the endoplasmic reticulum (ER) in yeast and mammalian living cells. The fluorescence properties of the compound depended on the DMSO/water ratio and on the pH. NMR experiments allowed determination of the conformation adopted in various environments. Apart from the convenient synthetic procedure, our compound displays low cell toxicity and blue emission compatible with filters routinely used in fluorescence microscopy. 相似文献
416.
本文通过调整发光剂、氧化剂、发光增强剂的浓度,并加入一组辅助剂,改进了依赖过氧化物酶化学发光液的配方。并通过比较实验证明:该发光液的检测灵敏度高于其它原有的发光液,同时还发现合成后的酶标复合物可经CM-32离子交换柱阶段洗脱纯化,以提高杂交灵敏度。从而建立了一套直接酶标DNA探针——化学发光自显影分子杂交体系。其狭缝杂交灵敏度可达0.03pg。并利用该体系进行了单拷贝基因分析,Western印迹杂交及检测血清HBV DNA等的应用研究。 相似文献
417.
Valérie Jérôme Andreas Heider Anja Schallon Ruth Freitag Professor 《Biotechnology journal》2009,4(10):1479-1487
The study of the non-viral gene delivery process at the molecular level, e.g. during the transfection of mammalian cells, is currently limited by the difficulties of specifically detecting the transfected plasmid DNA within the cells. Here we describe the in vivo production of 5-bromodeoxyuridine (BrdU)-labelled plasmid DNA by a thymine-requiring Escherichia coli strain leading to 92 ± 15% BrdU incorporation while minimizing plasmid structure alteration. The labelled plasmid is produced on the milligram scale in a two-stage cultivation process. The relevance of this approach for plasmid DNA visualisation in the field of gene delivery is demonstrated by localising the BrdU-labelled plasmid DNA via immunodetection/fluorescence microscopy in CHO-K1 cells after electroporation with naked, BrdU-labelled plasmid DNA and after polyfection with polyethylenimine/BrdU-labelled plasmid complexes. 相似文献
418.
Marianne E. Rüffer-Turner David J. Read Martin K. Johnson 《Journal of neurochemistry》1992,58(1):135-141
Neuropathy target esterase from hen brains was radiolabelled at the active site with [3H]diisopropyl phosphorofluoridate. The labelled protein was purified by differential centrifugation and Nonidet P40 solubilization, detergent phase partitioning, anion exchange, and preparative sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The volatilizable counts assay and analytical SDS-PAGE were used to monitor the protein. The 150-kDa subunit polypeptide appears as a single band on analytical SDS-PAGE. 相似文献
419.
420.
We studied the applicability of intersimple sequence repeat (ISSR) polymorphism in cotton. We found that: (i) the resolving power of agarose gels is poor relative to that provided by sequencing gels; (ii) fluorescent labelling of ISSR amplification primers produced numerous scorable bands; (iii) primer mixing (double priming) generated more bands than the sum of fragments resulting from two single primers, although an unexplained disappearance of several larger fragments also reproducibly occurred; (iv) ISSR fingerprinting patterns are highly heritable; and (v) double priming ISSR is an easy and informative genetic marker system in cotton for revealing both inter‐ and intraspecific variations. 相似文献