甘草酸单铵盐稳定性研究

本文考察甘草酸单铵盐贮存条件对其稳定性的影响。使用甘草酸单铵盐模拟市售包装,通过加速试验与长期稳定性试验,采用国家药品标准及中国药典附录收载的检测方法对样品进行检测,考察药物稳定性。本品内包装采用双层聚氯乙烯塑料袋,外包装为纸板桶,药品在常温条件贮存,五年内保持各项技术指标符合标准规定。甘草酸单铵盐选择适宜包装在常温库保存,药品有效期可由目前两年延长至五年。     

G418对IL—2基因包装细胞的筛选

本文用高浓度的G418(800μg/ml)和低浓度的G418(200μg/ml)对包装细胞PLXSN/IL-2/PA317细胞进行40天的选择筛选培养,使其细胞呈稳定状态生长时,收集上清液转染NIH/3T3细胞,进行病毒滴度测定。试图在高选择标记的情况下筛选出高表达目的基因的包装细胞。实验结果表明:高、低浓度的G418对PLXSN/IL-2/PA317包装细胞的选择作用相同,即包装细胞的病毒滴度同选择标记物浓度无关。提示可用低浓度的G418来维持包装细胞的生命。     

HIV-1假病毒包装的重要影响因素分析

[目的]分析影响HIV-1假病毒包装的主要因素,建立该假病毒包装的优化条件.[方法]用单因素分析对比的方法,比较了对病毒包装效果有重要影响的转染试剂、转染试剂与质粒的数量、培养基血清类型、细胞周期阶段对于病毒包装效果的影响.[结果]对45批150盘病毒包装结果分析显示,使用PEI转染试剂成本低,转染效果好,其N/P在8-40均可以产生高活性的包装病毒;用进口血清包装时,相对于国产血清结果重复性高;细胞周期处于S及G2/M期时转染质粒相对于S以及G0/G1期有较高的病毒活性.[结论]用PEI为转染试剂可以包装出高活性的病毒,包装获取高活性病毒可以通过质粒与PEI梯度比例以及血清类型构成多个组合策略来实现.     

包装饮用水、饮料类型与健康

水是生命之源,是人类生存的基本需求,饮用水的卫生是保证安全饮水的重要前提,但除卫生安全外,包装饮用水带来的健康问题常被人忽略。近年来,包装饮用水和饮料的生产量和销售额增速明显,人均包装饮用水和饮料消费量不断上升,已经成为一种普遍的消费行为,但存在诸多问题,如一些饮料含糖量高且消费量增加、喝纯净水成为消费时尚等。研究显示,除饮水量和饮水卫生之外,包装饮用水、饮料类型与健康密切相关。包装饮用水中含有一些营养素且很大程度上受加工工艺和环境条件影响,不同营养素含量的饮用水对健康的影响所有不同。包装饮用水、饮料类型还会影响机体水合状态,与机体身体活动能力、患糖尿病、血脂异常、龋齿、心血管疾病、泌尿系统疾病等其他疾病的发病风险有一定关系。可开展队列研究、横断面研究、干预性研究等,也可通过循证学研究综合评估包装饮用水、饮料与健康的关系,研究方向可着重在探索含糖饮料摄入量占膳食糖摄入量的比例、不同包装水及饮料对水合状态影响及对认知、体能、疾病影响的研究上,这将有助于居民了解包装饮用水、饮料健康效应,在足量饮水的同时合理选择健康包装饮用水、饮料类型;引领包装水、饮料行业新的大健康发展趋势。     

低温贮藏下真空与非真空包装对小麦种子生活力的影响

对以铝箔袋真空包装和铝盒非真空包装的89份小麦种子,在-4～0℃的低温种质库中贮藏11年后的贮藏效果进行了研究.从种子贮藏后的发芽率与入库前的初始发芽率差异,2种包装方式的种子年份间、同一年份2种方式间的种子发芽率差异等3个方面探讨了2种包装方式的种子在低温贮藏条件下的贮藏效果.结果表明:通过低温贮藏11年的小麦种子生活力测定.82%的材料在低温保存后其种子平均发芽率高于初始发芽率.而贮藏第10年后发芽率才出现较初始发芽率明显下降;铝箔袋包装的种子发芽率下降幅度小于铝盒包装,且差异达显著水平;铝箔袋真空密封包装的贮藏效果明显好于非真空包装的种子.     

冷却肉糜辐照脂肪氧化影响因素与抑制效果研究

研究了低剂量辐照、抗氧化剂、包装条件以及贮藏时间等影响辐照冷却肉脂肪氧化的主要因素和抑制效果.结果表明,对冷却猪肉的辐照处理会加剧其脂肪的氧化,真空包装或无氧包装可以明显的降低贮藏期间辐照冷却肉的脂肪氧化.辐照处理前在肉糜中添加抗氧化剂并采用真空包装时, 肉糜可以贮藏2周以上而不产生脂肪氧化.比较几种主要的抗氧化剂的效果表明,茶多酚在抑制辐照冷却肉糜脂肪氧化方面效果最好.     

重组水疱性口炎病毒载体病毒包装体系的建立及优化

目的:建立并优化重组水疱性口炎病毒(VSV)载体病毒包装体系,以获得稳定高效的重组VSV载体疫苗包装系统。方法:以prVSVΔG-GFP为骨架载体,pBS-N、pBS-P、pBS-G、pBS-L为辅助载体,探索不同的骨架质粒及辅助质粒用量、包装细胞系、重组痘病毒vTF7-3作用时间、转染试剂作用时间等因素对重组VSV载体病毒包装的影响,用光学显微镜及荧光显微镜观测重组VSV载体病毒的包装效果,应用TCID50法测定重组VSV的滴度。结果:重组VSV的包装效率随着辅助质粒或包装质粒总量的减少而降低,293T细胞较BHK21-WI2细胞包装效率更高,适当延长重组痘病毒vTF7-3作用时间或转染试剂作用时间能提高VSV包装效率。优化的病毒包装条件为:选用293T细胞,v TF7-3以5～15 MOI感染细胞1 h或以5 MOI感染细胞1～4 h,总质粒用量为3.67～22μg,转染细胞6～14 h可获得高效包装的rVSVΔG-GFP。采用优化包装条件高效包装了rVSVΔG-ZE病毒。结论:获得了稳定高效的重组VSV包装体系,为重组VSV载体的疫苗研究奠定了基础。     

采用Red重组系统构建包装菌株DH-gⅢ

选择感染性噬菌体技术是研究蛋白相互作用的良好手段,获得基因Ⅲ缺陷的辅助噬菌体是构成SIP体系的关键.为制备基因Ⅲ缺失的辅助噬菌体,利用λRed重组系统将完整的噬菌体基因Ⅲ和氯霉素抗性基因整合到大肠埃希菌DH5α的染色体上组氨酸操纵元位点构建包装菌株,经氯霉素抗性筛选并用PCR及组氨酸表型鉴定,获得包装菌株DH-gⅢ;将缺失功能基因Ⅲ的缺陷型噬菌体基因组转化到包装菌株中培养制备辅助噬菌体,以集落形成试验来检测缺陷型噬菌体的感染能力,结果滴度可达到4.3×108,只具备一次感染力,表明包装菌株构建成功,能用来制备辅助噬菌体,有望用于SIP体系.     

以HSV-1扩增子载体构建的新型重组AAV载体包装系统

将缺失两端ITR的AAV -2基因组克隆于HSV -1扩增子载体获得了质粒pHSV AAV .以HSV- 1tsK株为辅助病毒感染转染了该质粒的Vero细胞 ,可获得一种具有包装重组AAV质粒能力的混合毒种 .连续传代可使其包装能力迅速升高 ,至 5～ 6代达到最高并趋于平稳 .此混合毒种中 ,含有包装了多拷贝AAV -2基因组的复制缺陷性假型HSV- 1病毒 ,它可表达AAV -2编码的复制与包装所需的各种反式蛋白 ;同时也含有HSV -1tsK病毒 ,它提供AAV -2复制与包装所需的全部辅助病毒功能 .实验结果也表明 ,HSV -1tsK病毒的复制为混合毒种辅助重组AAV载体的包装所必需 .这项研究首次报道了一种全新的重组AAV载体包装系统 ,与传统的双质粒共转染、腺病毒辅助包装方案相比 ,本系统简便易行 ,并明显提高了重组AAV的包装效率 .     

水芹菜优质高产栽培技术

食药兼用的野生水芹菜资源趋于匮乏,调研与总结出在兴义市水源条件好的耕地,应用"水芹菜优质高产栽培技术",每年能采收5~6批次,年产鲜优质水芹菜15~20 t/hm2,产值﹙市场价8~10元/kg﹚10万~12万元/hm2这项技术包括:以有机肥为主、禁用农药防治病虫害、栽培地选择、精心整地与作厢、水芹菜种选择与处理、分期播种和方式及密度、施肥品种和数量及方式、田间管理、定时采收与分级包装、越冬管理等措施。     

Preservation of micro-organisms by drying; a review

The preservation of micro-organisms by different drying methodologies has been used for decades. Freeze drying in particular is the preferred method for transporting and storing vast culture collections of micro-organism strain types. The literature on drying and preserving micro-organisms is extensive, but is often specific to one particular strain. This review attempts to draw some similar concepts and findings together in one paper, to compare different drying techniques, with specific reference to microorganisms. The main topics covered are cell growth phases and concentration, inducing drying tolerance in microbial cells, drying methods, rehydration of dried cells and packaging and storage conditions. Also, particular attention has been paid to the use of freeze drying and the protective matrices used to improve microbial cell viability after drying.     

Effects of Periodical Soil Drying and Leaf Water Potential on the Sensitivity of Stomatal Response to Xylem ABA

The study on the changes of stomatal sensitivity in relation to xylem ABA during periodical soil drying and the effect of leaf water status on the stomatal sensitivity has confirmed that xylem ABA concentration is a good indicator of soil water status around roots and the relation between xylem ABA concentration and predawn leaf water potential remained constant during the three consecutive soil drying cycles based on the slopes of the fitted lines. The sensitivity of stomata to xylem ABA increased substantially as the soil drying cycles progressed, and the xylem ABA concentration needed to cause a 50% decrease of stomatal conductance was as low as 550 mnoL/L in the next two soil drying cycle, as compared with the 750 nmol/L ABA in the first cycle of soil drying. The results using the split-root system showed that leaf water deficit significantly enhanced the stomatal response to xylem ABA and the xylem ABA concentration needed to cause a 50% decrease in stomatal conductance was 2 to 4 times smaller in the whole-root-drying treatment than those in the semi-root- drying treatment. These results suggested that the sensitivity of stomata to xylem ABA concentration is not a fixed characteristic.     

Homeohydrous (Recalcitrant) Seeds: Dehydration, the State of Water and Viability Characteristics in Landolphia kirkii

Differential scanning calorimetry was used to study the relationships among drying rate, desiccation sensitivity, and the properties of water in homeohydrous (recalcitrant) seeds of Landolphia kirkii. Slow drying of intact seeds to axis moisture contents of approximately 0.9 to 0.7 gram/gram caused lethal damage, whereas very rapid (flash) drying of excised embryonic axes permitted removal of water to approximately 0.3 gram/gram. The amount of nonfreezable water in embryonic axes (0.28 gram H₂O/gram dry mass) did not change with drying rate and was similar to that of desiccation-tolerant seeds. These results suggest that the amount of nonfreezable water per se is not an important factor in desiccation sensitivity. However, flash drying that removed all freezable water damaged embryonic axes. Differences between desiccation-sensitive and -tolerant seeds occur at two levels: (a) tolerant seeds naturally lose freezable water, and sensitive seeds can lose this water without obvious damage only if it is removed very rapidly; (b) tolerant seeds can withstand the loss of a substantial proportion of nonfreezable water, whereas sensitive seeds are damaged if nonfreezable water is removed.     

Fickean and Non-Fickean Water Desorption During Vacuum Drying of <Emphasis Type="Italic">L. bulgaricus</Emphasis>

The recovery of Lactobacillus bulgaricus was studied in correlation to the kinetics of cell drying. When bacteria were dehydrated at 30 °C, either in the presence or the absence of sucrose, the drying kinetics corresponds to a Fickean diffusion in correspondence with a short lag time. In contrast, when the bacteria were dehydrated at 70 °C in the absence of sugar, the kinetics corresponds to an anomalous diffusion, and the lag time is four to five times higher than that at 30 °C. However, when drying at 70 °C was carried out in the presence of sucrose, drying kinetics turned into a Fickean process parallel to a substantial decrease in the lag time. The pattern of water desorption was correlated with the critical water activity. When the drying kinetics corresponds to a Fickean diffusion, the lag time started to increase at 0.7 water activity, but when the cells were dried at 70 °C, the damage started at 0.5 water activity. This observation indicates that the drying rate affects the pattern of water desorption, and it can change the value of critical water activity. These results put into relevance that the cell recovery is due to the drying history and that the recovery increase produced by sucrose can be related to the maintenance of kinetic barriers for water desorption.     

污水污泥和造纸污泥干燥特性的对比研究

采用4种不同温度(30℃、70℃、102℃、130℃)及4种不同体表比(1.62cm²·g^-1、2.16cm²·g^-1、3.24cm²·g^-1、6.48cm²·g^-1)的污泥样品,对比研究了污水污泥和造纸污泥的干燥特性。结果表明:恒温干燥的温度越高,样品的比表面积越大,干燥时间越短。污泥失水率在10%之前,处于快速干燥阶段;污泥失水率在10%～60%之间,处于恒速干燥阶段;污泥失水率在大于60%时,处于降速干燥阶段。各阶段,污水污泥的失水速率比造纸污泥小0.01%·s^-1左右。     

River drying lowers the diversity and alters the composition of an assemblage of desert riparian arthropods

Summary 1. Many studies have shown negative effects of river drying on in‐stream animals. However, the influence of river drying on riparian animals remains poorly studied. We examined ground‐dwelling riparian arthropod assemblages along a drying section of the semi‐arid San Pedro River in southeastern Arizona, U.S.A. 2. We found strong differences in assemblage composition, taxon diversity and the abundance of key taxa between dry and flowing sites, with higher diversity and abundance of most taxa at flowing sites. 3. Changes in assemblage composition, taxon diversity and abundance of representative taxa were associated with a combined measure of water availability that included distance to water and type of water. Other environmental variables showed a weaker association with changes in these arthropod assemblages. 4. Thus, we found evidence that desert riparian arthropods are sensitive to river drying and to reduction in water resources. Increases in drying along this river may reduce the diversity and the abundance of many groups of ground‐dwelling arthropods, leading to marked shifts in community composition.     

周期性土壤干旱和叶片水势对气孔响应木质部ABA灵敏度的影响

研究了周期性土壤干旱期间气孔对木质部ＡＢＡ响应的灵敏度的变化以及叶片水势对灵敏度的影响。实验结果证明了木质部ＡＢＡ浓度是反映根系周围土壤水分状况的一个指标的结论。土壤周期性干旱不影响木质部ＡＢＡ浓度对土壤水分状况的依赖关系,但显著地提高了气孔对木质部ＡＢＡ 响应的灵敏度。根据对实测数据的数学模拟结果显示,引起气孔导度下降５０％ 所需的木质部ＡＢＡ浓度从第一轮土壤干旱的７５０ ｎｍｏｌ／Ｌ降至第二轮土壤干旱的５５０ ｎｍｏｌ／Ｌ。分根实验的结果表明,叶片水分亏缺显著提高了气孔对木质部ＡＢＡ 的响应的灵敏程度,全根干旱中引起气孔导度下降５０ ％ 所需的木质部ＡＢＡ 浓度比半根干旱的小２ ～４ 倍。这表明,气孔对木质部ＡＢＡ响应的灵敏度不是一个固定的特性,可随植物生长环境及许多其他因素的变化而表现出很大的差异     

Water relations of pine seedlings in relation to root and shoot growth

The effects of water stress on growth and water relations of loblolly and white pine seedlings were studied during series of drying cycles. As mean soil water potential decreased, growth of roots, needles, and buds decreased. Growth of roots during successive severe drying cycles was not uniform, however. A study of needle and root extension showed that of the total growth of roots for 3 7-day drying cycles, only 6% occurred during the third cycle, while needle extension was uniform for the 3 cycles. The difference in response of needles and roots to drying cycles may be attributed primarily to the effect of water stress on the growing region. When subjected to a severe stress, roots matured toward the tip and became dormant, resulting in less growth during subsequent drying cycles. The intercalary growing region of needles, however, was not altered seriously enough by the stress to cause a difference in amount of growth during each drying cycle.

Transpiration of loblolly pine was lower in the second drying cycle than in the first. Needle water potential after rewatering was as high as that of control plants watered daily; root resistance was apparently not important in restricting transpiration during a second drying cycle. Needle diffusion resistance of loblolly pine, measured with a low-resistance diffusion porometer, was slightly higher during the second drying cycle than during the first. In addition, many primary needles were killed during the first period of stress. These factors contributed to the reduction of transpiration during the second drying cycle. Diffusion resistance of Coleus increased and transpiration ceased during the first drying cycle while water potential remained relatively high. After rewatering, both leaf resistance and transpiration returned to the control level, presumably because the stress during the first period of drying was not severe. The diffusion resistances observed for well-watered plants were 30 to 50 sec·cm⁻¹ for loblolly pine, 3 to 5 sec·cm⁻¹ for Coleus, and 4 to 6 sec·cm⁻¹ for tomato. These values agree closely with those reported by other workers.

     

On the Determination of Water Content in Biomass Processing

Processing of lignocellulosic materials to fuels such as methane and bioethanol may involve several processing steps including pretreatment, saccharification, fermentation, and anaerobic digestion. The amounts of substrate used in these processes are usually based on dry matter content, and the processes themselves typically lead to a change in dry matter content. Thus, it is of great importance to be able to measure dry matter accurately. Dry matter content is commonly determined by measuring loss of water during oven drying. We have used Karl Fischer (KF) titration to measure the water content in a wide range of biomass fractions and have compared these data to results obtained by oven drying. This revealed considerable differences for all tested materials. For lignocellulosic materials, oven drying tends to overestimate dry matter content for untreated material. On the other hand, oven drying generally underestimates dry matter content in pretreated materials due to loss of organic volatiles. These differences have major consequences for the calculation of mass balances and yields in bioprocessing. The KF method gives more accurate water determination than oven drying due to the unique selectivity of the analysis. The method is suitable for the analysis of lignocellulosic biomasses and is particularly useful for determination of water content in pretreated materials, where oven drying usually underestimates the dry matter content due to loss of volatiles.     

Leaf and root control of stomatal closure during drying in soybean

The stomatal conductance of an illuminated 2.5 cm² area of an intact soybean leaflet was the same whether the rest of the shoot was in light or darkness. This was true throughout soil drying cycles. Water potential of tissue immediately outside the illuminated area consistently decreased about 0.3 MPa upon illumination of the shoot. This erroneously suggested that stomatal conductance during soil drying did not respond to diurnal reductions in leaf water potential, but was controlled by root or soil water status. Tests showed that the water potential of tissue in the illuminated area did not change in the steady-state upon illumination of the rest of the shoot. Water potentials of shaded sections of leaves were not different from predawn water potentials, and were higher than leaf xylem pressure potentials as determined with a pressure chamber. These steep local gradients of leaf water potential suggest that there is minimal interchange of water among xylem elements leading from roots to different sections of leaves. The relationship between stomatal conductance and leaf water potential was the same whether leaf water potential was reduced by soil drying, application of polyethylene glycol (PEG) to the root system, lowering root temperature, or leaf excision. In the root cooling experiment, there was no soil drying, and with leaf excision, there was no root drying. The similarity of stomatal responses to leaf water potential in all cases strongly suggests control of conductance by a signal produced by local leaf water potential rather than root or soil water status in these experiments.