A novel membrane based process to isolate photosystem-I membrane complex from spinach

The isolation of photosystem-I (PS-I) from spinach has been conducted using ultrafiltration with 300 kDa molecular weight cut-off polyethersulfone membranes. The effects of ultrafiltration operating conditions on PS-I activity were optimized using parameter scanning ultrafiltration. These conditions included solution pH, ionic strength, stirring speed, and permeate flux. The effects of detergent (Triton X-100 and n-dodecyl-beta-D-maltoside) concentration on time dependent activity of PS-I were also studied using an O₂ electrode. Under optimized conditions, the PS-I purity obtained in the retentate was about 84% and the activity recovery was greater than 94% after ultrafiltration. To our knowledge, this is the first report of the isolation of a membrane protein using ultrafiltration alone.     

按蚊肠道微生物及其在阻断疟疾传播上的应用

按蚊体内,尤其是中肠内定殖着大量的微生物群落。肠道菌群通过与按蚊的长期协同进化形成了相互依存的共生关系。肠道共生菌参与调节按蚊的多种生命活动,对于维持按蚊的健康发挥着重要作用,已经成为一个与宿主按蚊密不可分的重要"器官"。研究表明,肠道共生菌在按蚊物质代谢、营养、发育、生殖、免疫调控和免疫防御等生理过程中发挥着重要的调节作用。蚊虫是疟疾、登革、寨卡等多种疾病的传播媒介,而肠道共生菌对寄生虫和病毒在蚊虫肠道内的发育和感染具有重要影响,因此研究蚊虫与共生菌的相互作用有着重要的理论和实践意义。本文将对按蚊肠道共生菌的多样性、生物学功能、与宿主相互作用的机制及其在防治疟疾上的应用进展进行综述,并对未来的研究提出展望。     

细菌素Paracin 1.7的纯化与性质

[目的]分离纯化(Lactobacillus paracasei)HD1.7所产生的细菌素并分析其特性.[方法]细菌素Paracin1.7的纯化采用色谱技术,其分子量检测采用十二烷基磺酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE),利用琼脂扩散法测定细菌素活力.[结果]Paracin 1.7分离于我国传统发酵食品酸菜发酵液中,其产生菌为副干酪乳杆菌.Paracin 1.7可以抑制其它微生物的生长,为细菌素.该菌在稳定期可产生大量Paracin 1.7.经过阳离子交换层析、凝胶过滤层析以及高效液相色谱(HPLC),对该细菌素进行了初步纯化,并经Tricine-SDS-PAGE检测其分子量大约为11 kDa.Paracin 1.7抑菌谱较广,其抑菌范围包括Proteus,Bacillus,Enterobacter,Staphylococcus,Escherichia,Lactobacillus,Microccus,Pseudomonas,Salmonella,Saccharomyces,其中有些为食品源致病菌.该细菌素在酸性及高温下稳定,对几种蛋白质酶敏感.该细菌素对敏感菌株的作用方式为抑菌.在4℃保存4个月后,Paraein 1.7的抑菌活性保持稳定.[结论]基于细菌素Paracin 1.7的性质,该细菌素可用作食品防腐剂.     

影响类弹性蛋白多肽自组装成微球的因素及其作用机制

影响类弹性蛋白多肽(ELPs)自组装成微球的因素较多,目前尚缺乏系统研究。以类弹性蛋白多肽[KV8F]n为对象,利用动态光散射仪测定了不同条件下其自组装成微球的粒径。结果表明:随着分子量的增加ELPs形成的微球粒径也随之增大,粒径的均一度减小;当盐浓度低于0.4 mol/L时,盐浓度的增加,微球粒径相应增加,而盐浓度高于0.4 mol/L则呈减少的趋势,但粒径均大于1.1μm;而当ELPs末端融合木聚糖酶和1,3-丙二醇氧化还原酶后,其自组装形成的微球粒径急剧减小,约为游离ELPs的1/10,分别为151.0 nm和174.2 nm。导致这种现象的原因可能是酶分子和ELPs通过静电引力相互作用后,酶分子的空间位阻妨碍了ELPs分子的聚集。     

Ethanol fermentation with Kluyveromyces marxianus from Jerusalem artichoke grown in salina and irrigated with a mixture of seawater and freshwater

Aims: To study fuel ethanol fermentation with Kluyveromyces marxianus ATCC8554 from Jerusalem artichoke (Helianthus tuberosus) grown in salina and irrigated with a mixture of seawater and freshwater. Methods and Results: The growth and ethanol fermentation of K. marxianus ATCC8554 were studied using inulin as substrate. The activity of inulinase, which attributes to the hydrolysis of inulin, the main carbohydrate in Jerusalem artichoke, was monitored. The optimum temperatures were 38°C for growth and inulinase production, and 35°C for ethanol fermentation. Aeration was not necessary for ethanol fermentation with the K. marxianus from inulin. Then, the fresh Jerusalem artichoke tubers grown in salina and irrigated with 25% and 50% seawater were further examined for ethanol fermentation with the K. marxianus, and a higher ethanol yield was achieved for the Jerusalem artichoke tuber irrigated with 25% seawater. Furthermore, the dry meal of the Jerusalem artichoke tubers irrigated with 25% seawater was examined for ethanol fermentation at three solid concentrations of 200, 225 and 250 g l^?1, and the highest ethanol yield of 0·467, or 91·5% of the theoretical value of 0·511, was achieved for the slurry with a solid concentration of 200 g l^?1. Conclusions: Halophilic Jerusalem artichoke can be used for fuel ethanol production. Significance and Impact of the Study: Halophilic Jerusalem artichoke, not competing with grain crops for arable land, is a sustainable feedstock for fuel ethanol production.     

拟南芥转录因子GRAS 家族基因群响应渗透和干旱胁迫的初步探索

GRAS家族是一类植物特有的转录调控因子, 已有报道表明该家族基因在植物生长发育和光信号转导过程中具有重要作用。目前在拟南芥(Arabidopsis thaliana)基因组中已鉴定了33个GRAS家族基因。利用功能基因组学和生物信息学手段,通过基因芯片数据挖掘和基因功能预测, 对拟南芥GRAS家族基因在渗透和干旱胁迫过程中的应答模式进行了初步探索, 提出了一类响应渗透胁迫和干旱胁迫的拟南芥GRAS家族基因。以SCL13为例, 利用基因芯片相关性和GO分析, 对其在渗透胁迫信号转导过程中可能的调控机制进行了预测和分析。这一研究将为阐明GRAS家族基因参与水分胁迫的分子机制提供新的思路, 同时也为植物抗逆分子育种提供候选基因。     

超声检测左心室舒张功能的临床意义——85例超声检测结果与冠状动脉造影的对照分析

目的超声心动图检测左心室舒张功能与冠状动脉造影对照分析,探讨超声诊断的临床意义。方法85例临床疑诊冠心病超声检查左心室二尖瓣口舒张早、晚期血流充盈速度E、A两峰峰值,计算E/A比值,其结果分为舒张功能正常和降低两组。全部病人均与冠状动脉造影结果对照分析。结果超声检测左心室舒张功能与冠脉造影均正常24例,均异常53例,共77例,符合率90.59%,不符合8例,占9.41%;本文依据冠脉造影提出超声检测左心室舒张功能正常值;并发现冠心病早期舒张功能降低,且随年龄与病程长短不同。结论超声检测左心室舒张功能的改变与冠脉造影符合率高,舒张功能于冠心病早期可降低,随病程长短不同,为临床对冠心病诊治和预防提供有价值的信息。     

Development of a fluorescent probe hydrolysis-insulated isothermal PCR for rapid and sensitive on-site detection of African swine fever virus

Highlights
1. A probe-based insulated isothermal PCR (iiPCR) assay was developed for rapid and onsite detection of ASFV.
2. The developed iiPCR showed similar sensitivity and specificity with OIE recommended real-time PCR.
3. Blood samples could be directly applied as PCR template in iiPCR without DNA extraction.     

GenoBaits Soy40K: a highly flexible and low-cost SNP array for soybean studies

<正>Dear Editor,Soybean(Glycine max [L.] Merr.) provides more than half of the oilseeds and more than a quarter of protein worldwide. It is estimated that the production of soybean has to be doubled by 2050 to meet the needs of the rapidly increasing consumption of soybean seeds along with a continuously increasing population(Ray et al., 2013). As such, development of a genotyping platform with high throughput, high efficiency and high precision but low-cost is urgently needed to accelerate...