茶油皂脚脂肪酸甲酯制备的水溶性改性胺固化物性能研究

以茶油皂脚脂肪酸甲酯制备的水溶性改性胺(CA-921)与水性环氧树脂固化,通过热重分析、差示扫描量热法(DSC)、机械性能测试及扫描电镜分析,研究了环氧树脂分散相粒子的粒径和黏度、环氧基与胺氢物质的量之比及固化温度对固化物性能的影响.研究结果表明,黏度及粒径均较小的水性环氧乳液AB-EP-20与固化剂CA-921复配所...     

Microbial and microfaunal community structure in cropping systems with genetically modified plants

Soils from field sites at Foulum (DK), Narbons (FR) and Varois (FR) planted with genetically modified maize expressing either the insecticidal Bacillus thuringiensis protein (Bt) or herbicide tolerance (HT), as described elsewhere in this volume, were analysed for nematodes, protozoa and microbial community structure. These analyses were mirrored in single-species testing and in mesocosm experiments, and were coordinated with field samples taken for microarthropods, enchytraeids and earthworms so allowing for cross-comparison and a better understanding of the results observed in the field. Over the first 2 years of the field experiments (in 2002 and 2003), the effect of Bt-maize was within the normal variation expected in these agricultural systems. Sampling in 2004 and 2005 was expanded to include the effects of tillage (i.e. reduced tillage versus conventional tillage) and also the use of HT-maize. Tillage had major effects regardless of soil type (Varois or Foulum), with reduced-tillage plots having a greater abundance of microfauna and a different microbial community structure (measured both by phospholipid fatty-acid analysis (PLFA) and by community-level physiological profiling (CLPP)) from conventionally tilled plots. Grass, as a contrasting cropping system to maize, also had an effect regardless of soil type and resulted in greater microfaunal abundance and an altered microbial community structure. Differences in crop management, which for the Bt-maize was removal of the insecticide used to control European corn borer and for HT-maize was a change in herbicide formulation, were only tested at single sites. There were differences in microbial community structure (CLPP but not PLFA) and sporadic increases in protozoan abundance under the Bt-crop management. The HT-maize cropping system, which covered a shorter period and only one site, showed little change from the conventional system other than an altered microbial community structure (as measured by PLFA only) at the final harvest. The Bt-trait had a minimal impact, with fewer amoebae at Foulum in May 2003, fewer nematodes at Foulum in May 2004 but more protozoa at Varois in October 2002 and an altered microbial community structure (PLFA) at Foulum in August 2005. These were not persistent effects and could not be distinguished from varietal effects. Based on the field evaluations of microfauna and microorganisms, we conclude that there were no soil ecological consequences for these communities associated with the use of Bt- or HT-maize in place of conventional varieties. Other land management options, such as tillage, crop type and pest management regime, had significantly larger effects on the biology of the soil than the type of maize grown.     

转基因作物安全研究进展及南繁转基因生物安全管理对策

本文从生物多样性、生态系统和人畜安全三方面概述了转基因作物生物安全研究进展,并介绍了全世界转基因生物安全评价原则与方法和我国转基因作物安全管理法规.表明转基因作物存在潜在的生物安全风险,全世界正在积极构建转基因生物安全管理体系.通过对我国南繁转基因环境安全问题和情况进行分析,认为南繁地区有成为染缸的潜在威胁.为保护南繁...     

Environmental impacts from herbicide tolerant canola production in Western Canada

The commercial production of herbicide tolerant (HT) canola began in Western Canada in 1997. With more than a decade of use, the actual farm-level environmental impact of HT canola can be evaluated. This article reports on a spring 2007 survey of nearly 600 canola farmers in the three prairie provinces of Western Canada. Producers were asked about their crop production experiences for 2005 and 2006 and expected crop planting for 2007. A reduction in the total number of chemical applications over the 3-year period was reported, resulting in a decrease of herbicide active ingredient being applied to farmland in Western Canada of nearly 1.3 million kg annually. Fewer tillage passes over the survey period were reported, improving moisture conservation, decreasing soil erosion and contributing to carbon sequestration in annual cropland. An estimated 1 million tonnes of carbon is either sequestered or no longer released under land management facilitated by HT canola production, as compared to 1995. The value of this carbon off-set is estimated to be C$5 million. Comparisons with similar studies and against non-adoption of HT canola can guide future decisions about HT canola adoption.     

烟草白肋型与正常绿叶型之间叶绿体性状差异的遗传研究

利用普通烟草(Nicotiana, tabacum L.)的正常绿叶型烟草和白肋型烟草品种,按安量性状遗传研究的完全双列杂交组合的設计所进行的研究表明:1.烟草叶绿素含量的遗传为部分显性的核基因所控制,白肋型的基因型并非前人报道的那样只是两对隐性重叠基因,还可能存在一些隐性的微效修饰基因;2.白肋型的叶绿体基粒数及其片层结构均较绿叶型减少,同是隐性核基因突变的结果;3.烟草叶绿体希尔反应活性受核基因的控制。F_1光活性表现明显的杂种优势,是核基因杂合性的反映;4.同前人的研究结果一样,普通烟草RuBp羧化酶的合成受核基因和叶绿体基因的双重控制,但本研究结果指出,白肋型和绿时型之间RuBp羧化酶的大亚基等电点聚焦电泳带存在差異,說明两者控制大亚基合成的叶绿体基因有了一定程度的分化。     

Serological Survey of Toxoplasma gondii Infection in the Domestic Goose (Anser domestica) in Southern China

In the present study, the antibodies to Toxoplasma gondii in 191 farm‐bred and 83 house‐bred geese (Anser domestica) were assessed for the prevalence of T. gondii infection in southern China with the modified agglutination test. Antibodies to T. gondii (MAT ≥ 1 : 5) were found in 27 (14.14%) of farm‐bred geese and 14 (16.87%) of house‐bred geese. Geese infected with T. gondii may be a source of T. gondii infection for humans and cats.     

An empirical approach to target DNA quantification in environmental samples using real-time polymerase chain reactions

Recent advances in molecular techniques have allowed for the routine examination of nucleic acids in environmental samples. Although current methodologies are very sensitive, accurate target DNA quantification from environmental samples remains challenging. To facilitate high-throughput DNA quantification from environmental samples, we developed a novel DNA quantification method based on a non-linear curve-fitting approach to extract additional information from quantitative PCR amplification curves and used the fitted parameters to develop multiple regression standard equations for target DNA quantification. A 3-parameter sigmoidal function performed superior to a 4-parameter Weibull function for generating the multiple regression standard equations. In a verification experiment, target DNA was quantified in a series of ‘unknown’ samples in three soils using this approach and the results were compared to target DNA values determined using corrected and uncorrected Ct-based (threshold cycle) methods. For each method, the deviations from the expected target DNA content were determined. Results clearly showed that over all DNA concentrations, target DNA content determined by the non-linear curve-fitting method was more accurate and more precise than values predicted by all other methods. Analysis of variance conducted on the predicted DNA contents also revealed fewer statistical artifacts with the non-linear curve fitting method compared to the conventional Ct-based methods. The novel approach described here is accurate, inexpensive, and very amenable for automation and high-throughput applications.     

Suppression of root-knot disease by Pseudomonas fluorescens CHA0 in tomato: importance of bacterial secondary metabolite, 2,4-diacetylpholoroglucinol

The antimicrobial metabolites 2,4-diacetylphloroglucinol (2,4-DAPG) and pyoluteorin contribute to the ability of Pseudomonas fluorescens strain CHA0 to control plant diseases caused by soil-borne pathogens. P. fluorescens strain CHA0 and its derivatives CHA89 (antibiotics-deficient) and CHA0/pME3424 (antibiotics overproducing) were investigated as potential biocontrol agents against Meloidogyne javanica the root-knot nematode. Exposure of root-knot nematode to culture filtrates of P. fluorescens under in vitro conditions significantly reduced egg hatch and caused substantial mortality of M. javanica juveniles. Nutrient broth yeast extract (NBY) medium amended with 2% (w/v) glucose or 1 mM EDTA markedly repressed hatch inhibition activity of the strain CHA0 but not that of CHA0/pME3424 or CHA89. On the other hand, NBY medium amended with glucose significantly enhanced nematicidal activity of the strain CHA0/pME3424. Neither glucose nor EDTA had an influence on the nematicidal activity of the strains CHA0 and CHA89. Under in vitro conditions, antibiotic overproducing strain CHA0/pME3424 and CHA0 expressed phl‘-’lacZ reporter gene but strain CHA89 did not. Expression of the reporter gene reflects actual production of DAPG. In general, CHA0/pME3424 expressed reporter gene to a greater extent compared to its wild type counterpart CHA0. Regardless of the bacterial strains, reporter gene expression was markedly enhanced when NBY medium was amended with glucose but EDTA had no such effect. A positive correlation between the degree of juvenile mortality and extent of phl‘-’lacZ reporter gene expression was also observed in vitro. Strain CHA0 produced zones of 4-6 mm on MM medium containing gelatin while strain CHA0/pME3424 and CHA89 did not. When MM medium containing gelatin was amended with 2% glucose of 1 mM EDTA size of haloes produced by the strain CHA0 reduced to 2 mm. Under glasshouse conditions aqueous cell suspension of the strains CHA0 or CHA0/pME3424 at various inoculum levels (10⁷, 10⁸ or 10⁹ cfu ml⁻¹) significantly reduced root-knot development. CHA89 caused significant reduction in galling when applied at 10⁹ cfu ml⁻¹. To better understand the mechanism of nematode suppression, split root bioassay was performed. Split-root experiments, that guarantee a spatial separation of inducing agent and a challenging pathogen, showed that soil treatment of one half of the root system with cell suspension of CHA0 or CHA0/pME3424 resulted in a significant systemic induced resistance leading to reduction of M. javanica infection of tomato roots in the non-baterized nematode treated half. The results clearly suggest that the antibiotic 2,4-DAPG from P. fluorescens CHA0 act as the inducing agents of systemic resistance in tomato roots. Populations of CHA0 and its derivatives declined progressively by 10-fold between first and fourth harvests (0-21 days after inoculation). However, bacterial populations increased at final harvest (28 days after application).     

玉米中转基因成分筛查策略

根据商业化转基因玉米外源基因元件信息,构建玉米转基因检测分子特征矩阵,并根据元件信息建立转基因玉米的筛查检测策略。结果表明:利用CaMV35S启动子、NOS终止子2个元件的组合,可完成对现有转基因玉米转化事件的筛查检测,检测灵敏度可达到1g/kg。该筛查方法可对玉米中的转基因成分进行快速、高灵敏度的筛查。     

木粉丁二酰化改性制备生物基塑料

[目的]制备出具有较好力学性能的注塑级生物基塑料.[方法]以胡桑枝条木粉为原料,经球磨预处理后,于二甲亚砜-四乙基氯化铵复合溶剂体系中部分溶解后,以丁二酸酐为酯化试剂,对二甲氨基吡啶为催化剂,进行酯化改性,制备出具有较好力学性能的注塑级生物基塑料.[结果]通过试验对比,得出最好的试验参数为:当木粉原料与丁二酸酐的质量比为1∶1,在60℃下溶解1h后再反应1h.在此条件下改性产物的增重率为103.7％,可以达到最优的力学性能,其拉伸强度和弯曲强度分别能达到33.4和41.9 MPa,已经达到一般塑料的力学性能.[结论]研究可为木质纤维类生物质全组分综合高值利用提供参考.