超高效液相色谱-四极杆/静电场轨道阱高分辨质谱法快速测定3种含生物碱类中药材中193种农药残留

基于超高效液相色谱-四极杆/静电场轨道阱高分辨质谱(UPLC-Q-Orbitrap HRMS)技术,建立了快速筛查和分析3种含生物碱类中药材(延胡索、黄连和黄柏)中193种农药残留的方法。样品经QuEChERS法提取,引入含阳离子交换型吸附剂的分散固相萃取净化,采用Agilent Poroshell 120 EC-C₁₈色谱柱(3.0 mm×150 mm,2.7μm)分离,以分别含有0.1%甲酸和5 mmol/L甲酸铵的水溶液和甲醇溶液作为流动相梯度洗脱,质谱采用全扫描/数据依赖的二级扫描模式(Full MS/ddMS2),外标法定量。结果显示：193种农药在相应的浓度范围内线性关系良好,相关系数(r)均在0.99以上;定量限为10～100μg/kg;在10、50、100μg/kg 3个添加水平下,延胡索、黄连和黄柏中193种农药的平均回收率分别为58%～120%、68%～124%和73%～122%,相对标准偏差(RSD)均在20%以内(n=6)。该方法前处理简便、快速,采用四极杆/静电场轨道阱高分辨质谱,通过母离子定量定性,二级碎片及保留时间定性,提高了含生物碱...     

山羊对不同饲草瘤胃干物质降解率的研究

选择装有永久性瘘管的雄性黑山羊3只(25±0.5)kg,采用尼龙袋法研究不同牧草的干物质瘤胃降解率。结果显示,新鲜菠萝皮、青贮菠萝皮、荆树叶、苦楝、早稻在瘤胃内都有较好的降解率;青贮对菠萝皮在瘤胃内的降解率有显著提高(P<0.05)。该试验得出了全株象草的降解曲线,以期为生产实践提供理论指导。     

夷陵区羊布鲁氏菌病流行病学调查及防控建议

为全面了解夷陵区羊布鲁氏菌病流行情况,为该区科学防控布鲁氏菌病提供参考,对该区13个乡镇(街道、开发区)所有规模养羊场和散养户进行了现场问卷调查,并采集39 640份羊血清样本进行实验室检测,共检出阳性样品2份,阳性率为0.005%。调查结果表明,夷陵区羊布鲁氏菌病的阳性率较低,疫情处于假定稳定控制状态,但部分地区特别是西北山区的养殖管理水平较低,有潜在疫情风险,应进一步加强对羊布鲁氏菌病的监测和检疫,采取综合措施,提升区域整体养殖管理和防控水平。     

Prevalence of antimicrobial resistance among Salmonella on midwest and northeast USA dairy farms

The objective of this study was to determine the prevalence of antimicrobial resistance among Salmonella isolated from dairy herds in New York, Minnesota, Michigan, and Wisconsin, USA. Serogroup and antimicrobial susceptibility characteristics were determined for Salmonella from cattle and environmental samples collected during August 2000–October 2001 as part of a longitudinal study where 129 herds were visited at 2-month intervals. Salmonella isolates were tested (using a broth microdilution method) for susceptibility to amoxicillin/clavulanic acid, ampicillin, ceftiofur, ceftriaxone, cephalothin, chloramphenicol, ciprofloxacin, gentamicin, kanamycin, nalidixic acid, streptomycin, sulfamethoxazole, tetracycline, and trimethoprim/sulfamethoxazole. Of the 1506 isolates tested for minimum inhibitory concentrations to these 14 antimicrobial agents, 81.2% were pan-susceptible and for most herds (81.6%) the predominant antimicrobial resistance pattern was pan-susceptible. At least 1 Salmonella isolate resistant to 5 or more antimicrobial agents was found on 23.6% of herds. This resistance phenotype was most common among serogroups B and E1 and among samples from calves and farmer-designated sick cows. Resistant samples most frequently exhibited resistance to tetracycline, streptomycin, and/or ampicillin. No samples were resistant to ceftriaxone (though 13 were in the intermediate range), and very few samples were resistant to ciprofloxacin (n = 1), nalidixic acid (n = 5), or trimethoprim/sulfamethoxazole (n = 7).     

Isolation, characterization and antifungal activity of major constituents of the Himalayan lichen Parmelia reticulata Tayl

Antifungal activity of hexane, ethyl acetate and methanol extracts of Parmelia reticulata was evaluated against soilborne pathogenic fungi, namely, Sclerotium rolfsii, Rhizoctonia solani, R. bataticola, Fusarium udum, Pythium aphanidermatum and P. debaryanum by poisoned food technique. Maximum antifungal activity was exhibited by hexane and ethyl acetate extracts against most of the test pathogens. Secondary metabolites, namely, (±)-isousnic acid, (±)-protolichesterinic acid, atranorin, evernyl, ethyl hematommate, ethyl orsellinate, methyl hematommate (3-formyl-2,4-dihydroxy-6-methylbenzoic acid methyl ester), 2-hydroxy-4-methoxy-3,6-dimethylbenzoic acid, 1-hydroxy-3,6-dimethoxy-8-methyl-xanthen-9-one, baeomycesic acid and salazinic acid, were isolated from the above extracts and identified by 1H NMR, 13C NMR and mass spectroscopic methods. When these metabolites were tested for antifungal activity against test pathogens, maximum antifungal activity was exhibited by (±)-protolichesterinic acid against R. solani (ED50=23.09 μg mL(-1)) and P. debaryanum (ED50=16.07 μg mL(-1)) and by atranorin against S. rolfsii (ED50=39.70 μg mL(-1)). The antifungal activity of protolichesterinic acid was found to be comparable to that of hexaconazole, a commercial fungicide.     

好望角芦荟的组织培养与快速繁殖

以好望角芦荟的茎段、叶片、根段为外植体,进行了组织培养与快速繁殖研究。结果表明:外植体以茎段为宜;最佳芽诱导和增殖培养基均为MS+蔗糖3.5%+琼脂0.7%+6-BA2mg/L+IBA0.1mg/L;生根壮苗培养基是MS+蔗糖2%+0.55%琼脂+IBA1.5mg/L+KT0.2mg/L。移栽基质以腐质土为好,成活率可达92%,且组培苗长势健壮。