Characterization of Bioactivities and Biosynthesis of Angucycline/Angucyclinone Derivatives Derived from Gephyromycinifex aptenodytis gen. nov., sp. nov.

Strain NJES-13^T is the type strain and currently the only species of the newly established actinobacteria genera Aptenodytes in the family Dermatophilaceae isolated from the gut microbiota of the Antarctic emperor penguin. This strain demonstrated excellent bioflocculation activity with bacteria-derived exopolysaccharides (EPSs). Moreover, it produced bioactive angucycline/angucyclinone derivatives (ADs) and contained one type III polyketide synthase (T3PKS), thus demonstrating great potential to produce novel bioactive compounds. However, the low productivity of the potential new AD metabolite was the main obstacle for its chemical structure elucidation. In this study, to increase the concentration of targeted metabolites, the influence of cellular morphology on AD metabolism in strain NJES-13^T was determined using glass bead-enhanced fermentation. Based on the cellular ultra-structural observation driven by bacterial EPSs, and quantitative analysis of the targeted metabolites, the successful increasing of the productivity of three AD metabolites was achieved. Afterward, a new frigocyclinone analogue was isolated and then identified as 2-hydroxy-frigocyclinone, as well as two other known ADs named 2-hydroxy-tetrangomycin (2-HT) and gephyromycin (GPM). Three AD metabolites were found to demonstrate different bioactivities. Both C-2 hydroxyl substitutes, 2-hydroxy-tetrangomycin and 2-hydroxy-frigocyclinone, exhibited variable inhibitory activities against Staphylococcus aureus, Bacillus subtilis and Candida albicans. Moreover, the newly identified 2-hydroxy-frigocyclinone also showed significant cytotoxicity against three tested human-derived cancerous cell lines (HL-60, Bel-7402 and A549), with all obtained IC₅₀ values less than 10 µM. Based on the genetic analysis after genomic mining, the plausible biogenetic pathway of the three bioactive ADs in strain NJES-13^T was also proposed.     

适于新疆长绒棉的综合机采栽培技术

新疆长绒棉品质优良,在提高我国纺织产品档次、增强行业竞争力方面发挥了重要作用.为了更好地指导新疆长绒棉机采种植,课题组在集成前人对长绒棉优质高效高产栽培技术以及机采棉高效综合栽培技术基础上,结合长绒棉机采种植的特殊要求,提出了机采长绒棉品种要求、机采种植管理技术要点和脱叶采收技术要点,总结形成了适于新疆长绒棉的综合机采...     

The Microstructure,Antibacterial and Antitumor Activities of Chitosan Oligosaccharides and Derivatives

Chitosan obtained from abundant marine resources has been proven to have a variety of biological activities. However, due to its poor water solubility, chitosan application is limited, and the degradation products of chitosan oligosaccharides are better than chitosan regarding performance. Chitosan oligosaccharides have two kinds of active groups, amino and hydroxyl groups, which can form a variety of derivatives, and the properties of these derivatives can be further improved. In this review, the key structures of chitosan oligosaccharides and recent studies on chitosan oligosaccharide derivatives, including their synthesis methods, are described. Finally, the antimicrobial and antitumor applications of chitosan oligosaccharides and their derivatives are discussed.     

基于三参数最佳动力性换档规律的制定与仿真研究

通过对汽车自动变速器三参数最佳动力性换档规律的研究,找出最佳动力性换档规律产生循环换档的原因,提出一种改进的动态三参数最佳动力性换档规律。应用MATLAB/SIMIULINK建立的换档规律仿真模型对改进的换档规律进行仿真分析。仿真表明经改进的动态三参数最佳动力性换档规律可以减少循环换档,使汽车获得更好的行驶性能。     

长江中下游地区棉花涝灾渍害预防及灾后管理技术

针对我国长江中下游地区因梅雨季节阴雨时间长、降水量大而集中常常引发涝灾和造成棉花渍害的现象,总结提出了一系列棉花防涝防渍及灾后田间管理技术措施与要求,以期为长江中下游地区棉农提供技术指导,促进当地棉花产业的发展和植棉效益的提高.     

奶牛胚胎一步细管法冷冻解冻试验

胚胎冷冻技术是胚胎保存、切割和性别鉴定以及建立胚胎库等的重要技术基础。试验应用CL-5500冷冻仪,采用乙二醇作保护剂冷冻奶牛胚胎,解冻复苏率达到85.7%。     

鲁西南植棉区蒜套棉氮肥施用量试验初探

为探讨蒜套棉适宜的施氮水平,以鲁西南植棉区主栽品种瑞杂818为试验材料,设置45、90、135、180和225 kg·hm-25个施氮水平,研究不同施氮量对土壤氮肥残留量、棉花生育期、棉花农艺性状和产量的影响.结果表明,随施氮量的增加,土壤氮肥残留量增加,棉花生育期延长且生殖生长推迟,产量则呈现先增后减的趋势.综合考虑...     

人工牧草粘虫发生为害特点的初步观察

粘虫Mythimna Separata(Walker)*属磷翅目,夜蛾科,别名:"剃头虫"、"花青虫"、"五色虫".幼虫食性杂,取食可达100余种植物,恩施州玉米、水稻、小麦等作物常受其害,曾多次在玉米上间歇性暴发.随着畜牧养殖业规模型发展,人工种植牧草也由原来的零星型种植,发展到规模型种植,累积面积达4.67万hm2.2003年粘虫转入人工牧草危害,已成为近年人工牧草常发性害虫.     

基于高通量测序及分离培养初步研究美国大豆中真菌多样性

中国是全球最大的大豆进口国,进境大豆所携带的病原真菌传入我国的风险极高.基于高通量测序技术对6批美国大豆真菌多样性进行分析,同时采用分离培养获得单一菌株,依据菌落形态、显微结构及分子技术进行鉴定.高通量测序结果显示,大豆中所有真菌共计5门15纲35目63科112属155种,主要为链格孢属(Alternaria)、球腔菌...