免耕覆盖条件下田间土壤水分入渗的二维数值模拟研究

根据土壤水动力学基本原理,建立了秸秆覆盖条件下夏玉米SPAC系统中二维土壤水分入渗模型,应用该模型采用ADI法对辽宁地区秸秆覆盖条件下玉米田间土壤水分入渗过程进行模拟计算。模拟结果再现田间土壤水分入渗过程,同时显示产流与未产流情况试验数据与模拟值均有较好的一致性,平均相对误差均在5%以内,所构建模型可用于覆盖条件下土壤水分运动规律的研究。     

Effect of CO2 on Chemical and Microbial Changes of Pacific White Shrimp During Modified Atmosphere Packaging

ABSTRACT

This study monitored the physical, chemical, and sensory quality of raw Pacific white shrimp (Litopenaeus vannamei) and the evolution of microbial flora under modified atmosphere packaging (MAP) with varying concentrations of CO₂ (95% CO₂/5% O₂; 80% CO₂/15% N₂/5% O₂; 65% CO₂/30% N₂/5% O₂) at 4°C during 10-day storage. Plate counts on selective agars indicated that MAP had a strong inhibitory effect on psychrotrophic bacteria, mesophilic bacteria, Enterobacteriaceae, and H₂S-producing bacteria. Analyses with molecular techniques (denaturing gradient gel electrophoresis, DGGE) by extracting bacterial DNA from shrimp samples showed that Vibrio spp. and Aeromonas spp. were predominant in fresh MAP samples. Shewanella putrefaciens, which dominated in samples stored in air, were found sporadically in MAP samples. Interestingly, lactic acid bacteria were not predominant in MAP samples, whose pH values were high (6.66 to 8.14) during storage. The content of total volatile basic nitrogen in MAP samples was about 10 mg N/g lower than the control at the end of storage. Higher lightness values and sensory scores were also observed in samples under MAP. However, MAP with CO₂ concentrations higher than 80% did not enhance the inhibitory effect on bacterial growth but induced more severe reddening and sensory quality loss.     

玉米蛋白质组研究中双向电泳技术条件的优化

为了优化玉米叶片双向凝胶电泳技术条件,通过比较3种总蛋白提取方法对玉米双向电泳结果的影响,并对蛋白质上样量、IEF等电聚焦条件及SDS-聚丙烯酰胺凝胶浓度等参数进行探索、优化;结果发现,与酚提取法和磷酸缓冲液法相比,采用改进的TCA/丙酮法提取总蛋白操作简单、方便,所得的2-DE图谱中蛋白质点数量多、背景清晰,是一种适用于提取玉米苗期叶片总蛋白的有效方法;同时筛选出:第一向IEF等电聚焦样品上样量为800μg,聚焦条件为20 000 V/h,在浓度为12.5%的SDS-聚丙烯酰胺凝胶中进行电泳,能够在17 cm的IPG胶条上获得背景低、分辨率较高、重复性好的双向电泳图谱,该优化体系适用于玉米叶片蛋白质组双向电泳分离,对玉米蛋白质组学研究具有重要参考价值。     

2-DE技术在果树研究中的应用

蛋白质组学是后基因组时代的研究热点之一。文章对果树蛋白质组研究进行了综述,包括双向电泳体系的建立以及双向电泳技术在果树生长发育、胁迫反应、激素响应和果实采后处理中的应用,并展望了果树蛋白质组学研究的前景。     

桃果实蛋白质双向电泳影响因素的研究

以‘大久保’桃（^{Prunus persica} L.'Okubao'）果实为试材,通过比较不同上样量、不同上样缓冲液、不同平衡缓冲液、不同染色方式等条件下的双向电泳图谱,探讨以上各因素对桃果实双向电泳图谱效果的影响。结果表明考马斯亮蓝染色后的电泳图谱虽然蛋白质点的数量少于银染色后的图谱,但背景较为清晰,适用于蛋白质组分析。采用固相pH梯度17 cm胶条,100 μg蛋白质上样量,样品干粉溶于375 μL含有硫脲、磺基三甲基胺乙内脂3~10的上样缓冲液中,等电聚焦后用含有磷酸三丁酯的平衡缓冲液还原,进行SDS-PAGE,银染色得出的双向电泳图有蛋白点1 209个,纹理较少,适用于桃果实蛋白质组学分析且兼容于下游技术的蛋白质质谱鉴定。     

鱼组织中氟喹诺酮类药的HPCE多残留检测方法的建立

建立了以伊诺沙星为内标,环丙沙星、恩诺沙星、沙拉沙星、二氟沙星在鱼组织中的毛细管电泳多残留检测方法。研究了缓冲溶液的类型,pH值,有机试剂添加等电泳条件.得到最佳的缓冲溶液是含10 mL/L乙腈的pH 5.0的磷酸氢二钠-柠檬酸缓冲溶液。用C18固相萃取柱浓缩和净化处理,用二极管阵列检测器进行检测(275 nm)。结果,四种药物在组织中的溶度25~400 μg/kg范围内R＞0.999,线性关系良好。环丙沙星,恩诺沙星,沙拉沙星和二氟沙星回收率分别为75.2%,79.7%,80.1%,79.2%。恩诺沙星的检测限低于25 μg/kg,其余的检测限均为25 μg/kg,,方法的日内变异系数小于13.5%,日间变异系数小于12.3%。该方法简单快速,经济环保,适用于大量阳性样本的筛选。     

Rheological properties of kafirin and zein prolamins

The possibility of forming dough from kafirin was investigated and laboratory prepared kafirin was formed into a viscoelastic dough system. Measurements with Contraction Flow showed that dough systems prepared from kafirin and from commercial zein had the required extensional rheological properties for baking of leavened bread. The extensional viscosity and strain hardening of the kafirin and zein dough systems were similar to those of gluten and wheat flour doughs. The kafirin dough system, however, unlike the zein dough system rapidly became very stiff. The stiffening behaviour of the kafirin dough system was presumed to be caused by cross-linking of kafirin monomers. SDS-PAGE showed that the kafirin essentially only contained α- and γ-kafirin, whereas the zein essentially only contained α-zein. Since γ-kafirin contains more cysteine residues than the α-prolamin it is more likely to form disulphide cross-links, which probably caused the differences in stiffening behaviour between kafirin and zein dough systems. Overall the kafirin dough system displayed rheological properties sufficient for baking of porous bread. Kafirin like zein appears to have promising properties for making non-gluten leavened doughs.     

琼脂糖凝胶电泳在水稻EcoTILLING技术中的应用

为构建低成本的基于琼脂糖凝胶电泳的EcoTILLING技术体系,用于水稻及其他生物自然群体变异的检测,对基于琼脂糖凝胶的EcoTILLING技术进行了优化。结果表明,从芹菜中提取的CEL Ⅰ核酸酶粗提物结合琼脂糖凝胶电泳检测技术,可以成功地检测到目的基因位点的突变。利用该技术,在云南地方水稻品种大吊糯中检测到2 个SNPs。     

玉米杂交种,自交系鉴定技术的研究进展（综述）

系统阐述了玉米品种鉴定技术的产生,发展及研究现状。由于种子科学技术的发展衣相关学科的渗透,玉米品种鉴定技术在近期内已由传统的形态学和化学方法发展到了现代的各种电泳技术,包括醇溶蛋白的等电聚焦电泳、同工酶电泳、     

Capillary zone electrophoresis analysis of gliadin proteins from Chinese and Yugoslav winter wheat cultivars

Gliadin proteins extracted from fifteen Chinese and Yugoslav winter wheat cultivars were fractionated using a new separation technique – Capillary Zone Electrophoresis (CZE). Different CZE conditions were defined to optimize resolution and reproducibility of gliadin separations. Excellent resolution and high reproducibility of gliadin CZE patterns were obtained by using 47 cm length, 50 μm i.d. capillaries at 15 kV and 30° C in sodium borate buffer system with acetonitrile (ACN) and sodium dodecyl sulfate. By using these CZE conditions, gliadin proteins from each cultivar were easily separated into more than 35 components. This resolution is generally superior to that of one- and two-dimensional electrophoresis and RH-HPLC. Analysis of reproducibility of gliadin CZE patterns from Chinese cultivar ‘Lumai 6’ showed that the average relative standard deviation (RSD) for peak migration times and heights was 0.21% and 4.06%, respectively. Gliadin electrophoregrams of all cultivars studied showed clear qualitative and quantitative differences, including presence or absence of some major peak, migration times and heights of peaks. Specifically, some closely related cultivars that were not differentiable by A-PAGE, were readily differentiated by CZE. In addition, winter wheat cultivars from China and Yugoslavia showed greater differences in gliadin compositions revealed by CZE. This revised version was published online in July 2006 with corrections to the Cover Date.