植物根毛生长发育及分子调控机理

植物根毛是植物吸收营养的主要器官, 了解根毛的发生、发育及遗传规律, 能对植物的养分吸收研究提供有利依据。文章旨在介绍植物根毛形态发生特性、发育生长过程及分子调控机理的研究进展, 利用比较基因组学方法研究农作物根毛形态和功能, 及有目的性的对根生长发育进行调控提供参考。研究发现植物根毛发育有反馈侧向抑制(lateral inhibition with feedback)和位置决定模式(position-dependent pattern of cell differentiation)两种方式。拟南芥根表皮细胞是以位置方式决定毛或非毛细胞发育类型, 已成为研究植物细胞命运和分化的模型。目前, 已经鉴定出控制根毛发育的基因, 包括一些转录因子如MYB家族蛋白TRIPTYCHON(TRY)、CAPRICE(CPC)和basic Helix-Loop-Helix (bHLH)蛋白GLABRA3、ENHANCER OF GLABRA3(EGL3)及WD-repeat蛋白等基因。最后针对根毛研究前景提出展望。     

TWO DIFFERENT SPECIES OF EUGLENA,E. GENICULATA AND E. MYXOCYLINDRACEA (EUGLENOPHYCEAE), ARE VIRTUALLY GENETICALLY AND MORPHOLOGICALLY IDENTICAL1

We investigated the similarity of a single Euglena myxocylindracea strain, isolated originally by Bold and MacEntee, to several Euglena geniculata strains on both morphological and DNA levels. We found the three DNA stretches, consisting of fragments coding for the parts of cytoplasmic and chloroplast small subunit rRNA, and the internal transcribed spacer (ITS2) of cytoplasmic rDNA, with the combined length of 4332 nucleotides, are identical in E. myxocylindracea and E. geniculata, strain SAG 1224‐4b. Morphological differences between E. myxocylindracea and any E. geniculata strain examined were well within the range of E. geniculata variability as well. The only difference behind the distinction of E. myxocylindracea from E. geniculata is the presence of the second chloroplast in the latter. However, we were able to induce the appearance of the second chloroplast in the cells of E. myxocylindracea and its disappearance in the cells of E. geniculata by changing the composition of the culture media. We therefore conclude that E. myxocylindracea Bold and MacEntee should be regarded as an environmental form of E. geniculata Dujardin. For the first time the morphology of E. geniculata chloroplasts was shown as revealed by confocal laser microscopy.     

交变脉冲电场凝胶电泳与植物大分子DNA的制备

介绍了交变脉冲电场凝胶电泳的原理、方法及其在植物大分子ＤＮＡ制备方面的应用     

spindlin1基因的原核表达及多克隆抗体制备

目的:明确人新基因spindlin1的组织表达谱、相互作用蛋白。方法与结果:应用PCR技术获得spindlin1的开放读框,并将其插入原核表达载体pGEX-2T,转化大肠杆菌BL21(DE3),经IPTG诱导后,融合蛋白GST-Spindlin1获得了可溶性表达。用SDS-PAGE胶上的目的条带做抗原制备了多克隆抗体,进行了抗体纯化。结论:spindlin1在OVCar3细胞中可能以二聚体形式存在,这一现象还有待于进一步研究。     

Calibration of Terra/MODIS gross primary production over an irrigated cropland on the North China Plain and an alpine meadow on the Tibetan Plateau

This paper evaluated the MODerate resolution Imaging Spectroradiometer (MODIS) gross primary production (GPP) product (MOD17) by using estimated GPP from eddy‐covariance flux measurements over an irrigated winter wheat and maize double‐cropping field on the North China Plain in 2003–2004, and an alpine meadow on the Tibetan Plateau in 2002–2003. The mean annual GPP from MOD17 accounted for 1/2–2/3 of the surface estimated mean annual GPP for the alpine meadow, but only about 1/5–1/3 for the cropland. This underestimation was partly attributed to low estimates of leaf area index by a MODIS product (MOD15) because it is used to calculate absorbed photosynthetically active radiation in the MOD17 algorithm. The main reason is that the parameter maximum light use efficiency (ε_max) in the MOD17 algorithm was underestimated for the two biomes, especially for the cropland. Contrasted to the default, ε_max was optimized using surface measurements. The optimized ε_max for winter wheat, maize and meadow was 1.18, 1.81 and 0.73 g C/MJ, respectively. By using the surface measurements and optimized ε_max , the MOD17 algorithm significantly improved the accuracy of GPP estimates. The optimum MOD17 algorithm explained about 82%, 68%, and 79% of GPP variance for winter wheat, maize, and meadow, respectively. These results suggest that it is necessary to adjust the MOD17 parameters for the estimation of cropland and meadow GPP, particularly over cropland.     

The association between exposure determined by radiofrequency personal exposimeters and human exposure: A simulation study

The selection of an adequate exposure assessment approach is imperative for the quality of epidemiological studies. The use of personal exposimeters turned out to be a reasonable approach to determine exposure profiles, however, certain limitations regarding the absolute values delivered by the devices have to be considered. Apart from the limited dynamic range, it has to be taken into account that these devices give only an approximation of the exposure due to the influence of the body of the person carrying the exposimeter, the receiver characteristics of the exposimeter, as well as the dependence of the measured value on frequency band, channel, slot configuration, and communication traffic. In this study, the relationship between the field strength measured close to the human body at the location of the exposimeter and the exposure, that is, the field strength at the location of the human body without the human body present, is investigated by numerical means using the Visible Human model as an anatomical phantom. Two different scenarios were chosen: (1) For FM, GSM, and UMTS an urban outdoor scenario was examined that included a transmitting antenna mounted on the roof of one of four buildings at a street crossing, (2) For WLAN an indoor scenario was investigated. For GSM the average degree of underestimation by the exposimeter (relation of the average field levels at the location of the exposimeter to the field level averaged over the volume of the human body without the body present) was 0.76, and for UMTS 0.87; for FM no underestimation was found, the ratio was 1. In the case of WLAN the degree of underestimation was more pronounced, the ratio was 0.64. This study clearly suggests that a careful evaluation of correction factors for different scenarios is needed prior to the definition of the study protocol. It has to be noted that the reference scenario used in this study does not allow for final conclusions on general correction factors. Bioelectromagnetics 31:535–545, 2010. © 2010 Wiley‐Liss, Inc.     

The X-ray crystal structure of APR-B,an atypical adenosine 5′-phosphosulfate reductase from Physcomitrella patens

Sulfonucleotide reductases catalyse the first reductive step of sulfate assimilation. Their substrate specificities generally correlate with the requirement for a [Fe₄S₄] cluster, where adenosine 5′-phosphosulfate (APS) reductases possess a cluster and 3′-phosphoadenosine 5′-phosphosulfate reductases do not. The exception is the APR-B isoform of APS reductase from the moss Physcomitrella patens, which lacks a cluster. The crystal structure of APR-B, the first for a plant sulfonucleotide reductase, is consistent with a preference for APS. Structural conservation with bacterial APS reductase rules out a structural role for the cluster, but supports the contention that it enhances the activity of conventional APS reductases.     

口蹄疫病毒反向遗传学研究进展

反向遗传学操作技术在口蹄疫病毒(FMDV)病原学基础研究领域的应用, 使得人们能够在基因组整体水平上研究病毒基因的功能。得益于反向遗传学系统的不断完善和发展, 目前人们对FMDV分子病原学也有了更加深入的认识和理解。本文结合实验室在FMDV反向遗传学方向上所开展的探索性研究工作, 综述了国内外利用反向遗传学操作技术在研究FMDV分子致病机制、病毒毒力与变异的关系、病毒复制的影响因素、新型FMD基因疫苗的研制等领域所取得的进展, 展望FMDV反向遗传学研究新动向。     

John Kendrew and myoglobin: Protein structure determination in the 1950s

The essay reviews John Kendrew's pioneering work on the structure of myoglobin for which he shared the Nobel Prize for Chemistry in 1962. It reconstructs the status of protein X‐ray crystallography at the time Kendrew entered the field in 1945, after distinctive service in operational research during the war. It reflects on the choice of sperm whale myoglobin as research material. In particular, it highlights Kendrew's early use of digital electronic computers for crystallographic computations and the marshaling of other tools and approaches that made it possible to solve the structure at increasing resolution. The essay further discusses the role of models in structure resolution and their broader reception. It ends by briefly reviewing Kendrew's other contributions in the formation and institutionalization of molecular biology.