转基因植物食品检测技术研究进展

随着转基因植物的迅速发展,转基因植物（GMO）含量大量涌向市场。出于对人类健康的考虑,GMO食品标识制度在世界范围内受到人们普遍关注。不论是对GMO食品贴标签,或是对GMO与非GMO原料的分别输送,GMO原料和食品的检测技术是必不可少的。GMO食品的检测主要有两种方法：一种是以DNA为基础的PCR法,另一种是从蛋白质水平出的ELISA法。比较全面地阐述了这两种检测方法的应用状况,重点介绍了PCR检测法及影响PCR检测方法的因素,作者预测DNA芯片检测法将是未来的发展方向。     

不同时期开沟施氮对水稻物质生产及产量的影响

通过田间试验 ,研究了水稻不同生育时期开沟深施氮肥对水稻叶片、叶鞘和茎秆干重以及生物产量和籽粒产量的影响 .结果表明 ,孕穗期开沟深施氮肥处理比分蘖期开沟、穗分化始期开沟和不开沟处理的水稻叶片干重保持最大值 (2 .9g/穴 )时间长 ,叶面积指数达到最大值 (LAI =8.9)后保持缓慢下降 ;叶鞘干重 (2 .7g/穴 )变化小 ;处理以后茎秆干重 (4.3g/穴 )稳步增加 .孕穗期开沟施肥处理的水稻生物产量(0 .73g·d-1/穴 )递增速度快 ,籽粒产量 (10 4 34kg·hm-2 )高 .与不开沟施肥相比 ,孕穗期开沟施氮对产量增加作用最大 ,为水稻开沟深施氮肥的最佳时期 ;其次为穗分化始期 ,分蘖期开沟施氮效果较差 ,但仍有一定的增产作用 .     

In Vivo Residue-specific Histone Methylation Dynamics

Methylation of specific histone residues is capable of both gene activation and silencing. Despite vast work on the function of methylation, most studies either present a static snapshot of methylation or fail to assign kinetic information to specific residues. Using liquid chromatography-tandem mass spectrometry on a high-resolution mass spectrometer and heavy methyl-SILAC labeling, we studied site-specific histone lysine and arginine methylation dynamics. The detection of labeled intermediates within a methylation state revealed that mono-, di-, and trimethylated residues generally have progressively slower rates of formation. Furthermore, methylations associated with active genes have faster rates than methylations associated with silent genes. Finally, the presence of both an active and silencing mark on the same peptide results in a slower rate of methylation than the presence of either mark alone. Here we show that quantitative proteomic approaches such as this can determine the dynamics of multiple methylated residues, an understudied portion of histone biology.     

长白山地区不同采集土样方式筛菌效率比较

目的对随机采样和田字格定点采样两种取样方式筛菌效率进行比较分析。方法利用随机采样和定点采样两种不同方式,采集了长白山地区的土样,取来自不同植物根际的土样,制成菌悬液后煮沸,涂布无氮平板以分离固氮芽胞杆菌。对分离的菌株进行菌落16S rDNA PCR,从中筛选鉴别巨大芽胞杆菌。结果定点采集土样分离出无晶体芽胞菌和有晶体芽胞菌分别是261株和76株,随机采集土样分离出无晶体芽胞菌和有晶体芽胞菌分别是279株和94株。经16S rDNA法鉴定分离巨大芽胞杆菌共19株。结论随机采样的取土方式与定点采样的取土方式差异度小,两种采集土样的方式在筛菌效率上并未表现出明显差异。     

银杏叶中聚戊烯醇类化合物的研究进展

本文对银杏叶中聚戊烯醇类化合物的研究作了综述,主要包括它们的化学结 构、提取分离方法、光谱特征、分析方法、作用,以及多萜醇的合成等。并对其研究前景进 行了展望。     

What affects the magnitude of change in first arrival dates of migrant birds?

We analysed which among four factors (mean first arrival date, migration distance, changes in population size, detectability of species) influenced the magnitude of change (regression coefficient) in the first arrival dates of 30 migrant bird species in western Poland during 1983–2003. An examination suggested that several of these factors could be important: the regression coefficient was positively related to mean first arrival date (early species advancing their arrival date more) and negatively with change in population size (species in decline changing less). Moreover, significant differences in regression coefficient were detected between short and long distance migrants and between low detectable and highly detectable species. Undertaking a principal components analysis on the four factors produced an axis explaining 59% of the variance and whose positive values were associated with late arriving, long distance and low detectable species which were more likely to be in decline. However, the multi-collinearity of these factors is a problem that cannot be resolved here and we recommend that further work from different areas is needed to tease apart these effects.     

Submerged versus air-exposed intertidal macrophyte productivity: from physiological to community-level assessments

The photosynthetic productivity of the intertidal communities dominated by the seagrass Zostera noltii and the cordgrass Spartina maritima was assessed in two contrasting situations during a tidal cycle, i.e., air exposure and water immersion. Two complementary methods were used: infra red gas analysis of CO₂ flux measurements in whole communities and chlorophyll a fluorescence measurements of individual plants photosynthetic activity. Higher photosynthetic rates of Z. noltii in air were observed both at the individual plants response level determined by chlorophyll fluorescence and at the community level measured as gas exchange (CO₂ uptake). S. maritima plants consistently showed low photosynthetic response when immersed. Gross community production (GCP) measured as carbon dioxide uptake was always higher in air than in water for both communities. When immersed, the GCP of both communities was similar. However, when exposed to the air, the GCP of the S. maritima community was higher than the one of Z. noltii's. The key factor in CO₂ assimilation by air-exposed Z. noltii was the retention of water in sediment microdepressions. During low tide, depressions in the sediment retain a considerable amount of water, enough to maintain leaf hydration. In these conditions, rapid air-water CO₂ diffusion occurs, making it readily available to plants. The community gas exchange measurements compared well with the fluorescence indications. Both Z. noltii and S. maritima were shown to be responsible for the overall pattern of photosynthetic carbon fixation within their respective communities, both during submersion and emersion periods. The short-term incubations method described in this report proved to be a valuable tool for field measurements of intertidal lagoon productivity. It provides fast and precise values of carbon dioxide fixation, both in submerged and air-exposed communities.     

Twenty-first century brain banking: practical prerequisites and lessons from the past: the experience of New York Brain Bank,Taub Institute,Columbia University

Generally accepted methods for processing postmortem brains are lacking, despite the efforts of pioneers in the field, and the growing awareness of the importance of brain banking for investigating the pathogenesis of illnesses unique to humans. Standardizing methods requires compromises, institutional or departmental mindset promoting collaboration, and the willingness to share ideas, information, and samples. A sound balance between competition and institutional interests is needed to best fulfill the tasks entrusted to health care institutions. Thus, a potentially widely accepted protocol design involves tradeoffs. We successfully integrated brain banking within the operation of the department of pathology. We reached a consensus whereby a brain can be utilized for diagnosis, research, and teaching. Thus, routing brains away from residency programs is avoided. The best diagnostic categorization possible is being secured and the yield of samples for research maximized. Thorough technical details pertaining to the actual processing of brains donated for research were recently published. Briefly, one-half of each brain is immersed in formalin for performing the neuropathologic evaluation, which is combined with the teaching task. The contralateral half is extensively dissected at the fresh state to obtain samples ready for immediate disbursement once categorized diagnostically. The samples are tracked electronically, which is crucial. This important tracking system is described separately in this issue. This report focuses on key lessons learned over the past 25 years of brain banking including successful solutions to originally unforeseen problems.     

Surface electromyographic measurements on land prior to and after 90 min of submersion (swimming) are highly reliable

The purpose of this study was to investigate the reliability of surface electromyography (sEMG) measurements after submersion (swimming) for 90 min. Isometric maximal voluntary contractions (MVC) on land and in water were collected from eight muscles on the right side of the body in 12 healthy participants (6 women and 6 men). Repeated measures analyses of variance (general linear model ANOVA) showed no significant differences in the peak amplitude MVC scores between land pre and post measurements for all muscles, p > .05. The mean of the Intraclass correlation coefficient (1, 1) for land pre and land post was .985 with (95% Cl = .978–.990), for land pre and water pre .976 (95% Cl = .964–.984) and for land pre and post, water pre and post .981 (95% Cl = .974–.987). Measuring sEMG on land before and after a prolonged submersion is highly reliable without additional waterproofing when using electrodes with 57 mm diameter.     

RPE65, Visual Cycle Retinol Isomerase, Is Not Inherently 11-cis-specific: SUPPORT FOR A CARBOCATION MECHANISM OF RETINOL ISOMERIZATION*

The mechanism of retinol isomerization in the vertebrate retina visual cycle remains controversial. Does the isomerase enzyme RPE65 operate via nucleophilic addition at C₁₁ of the all-trans substrate, or via a carbocation mechanism? To determine this, we modeled the RPE65 substrate cleft to identify residues interacting with substrate and/or intermediate. We find that wild-type RPE65 in vitro produces 13-cis and 11-cis isomers equally robustly. All Tyr-239 mutations abolish activity. Trp-331 mutations reduce activity (W331Y to ∼75% of wild type, W331F to ∼50%, and W331L and W331Q to 0%) establishing a requirement for aromaticity, consistent with cation-π carbocation stabilization. Two cleft residues modulate isomerization specificity: Thr-147 is important, because replacement by Ser increases 11-cis relative to 13-cis by 40% compared with wild type. Phe-103 mutations are opposite in action: F103L and F103I dramatically reduce 11-cis synthesis relative to 13-cis synthesis compared with wild type. Thr-147 and Phe-103 thus may be pivotal in controlling RPE65 specificity. Also, mutations affecting RPE65 activity coordinately depress 11-cis and 13-cis isomer production but diverge as 11-cis decreases to zero, whereas 13-cis reaches a plateau consistent with thermal isomerization. Lastly, experiments using labeled retinol showed exchange at 13-cis-retinol C₁₅ oxygen, thus confirming enzymatic isomerization for both isomers. Thus, RPE65 is not inherently 11-cis-specific and can produce both 11- and 13-cis isomers, supporting a carbocation (or radical cation) mechanism for isomerization. Specific visual cycle selectivity for 11-cis isomers instead resides downstream, attributable to mass action by CRALBP, retinol dehydrogenase 5, and high affinity of opsin apoproteins for 11-cis-retinal.