细菌DNA紫外线辐射损伤和DNA修复系统的实验探究活动

目的探究玉米顶腐病病原细菌——成团泛菌(Pantoea agglomerans) C3菌株对不同环境的适应性。方法通过稀释涂板法测定成团泛菌在不同温度、水质和寄主植物中的存活动态。结果C3菌株对紫外线辐射较为敏感,照射40 s后致死率达到100%;相较于37 ℃,4 ℃和20 ℃有利于C3菌株生存,灭菌自来水、水沟水和自来水中的菌体数量高于臭水沟水和池塘水;另外,C3菌株可在多种植物叶片上定殖,定殖密度表现为玉米>烟草>棉花>三叶草>稗草。结论成团泛菌具有很强的环境适应性,能够在不同的环境中进行生存和繁殖。     

农药紫外光保护剂研究应用进展

综述了黄酮类、荧光增白剂类等近10种农药紫外光保护剂及其作用机理,指出农药紫外光保护剂主要存在的问题是安全性问题和制剂成本问题,提出了解决措施,展望了其应用发展前景,认为天然源紫外光保护剂具有广阔的应用前景.     

Protective effect of the isoflavone equol against DNA damage induced by ultraviolet radiation to hairless mouse skin

Equol, an isoflavonoid metabolite produced from the dietary isoflavone daidzein by the gut microflora in mammals, has been found to protect not only against ultraviolet (UV) radiation-induced cutaneous inflammation and photoimmune suppression, but also have anti-photocarcinogenic properties in mice. Because the state of DNA damage has been correlated with suppression of the immune system and photocarcinogenesis, we have therefore examined the potential of equol to offer protection from solar-simulated UV (SSUV) radiation-induced DNA damage in hairless mice by the immunohistochemical approach using monoclonal antibody specific for cyclobutane pyrimidine dimers (CPDs; H3 antibody). Topical application of 20 µM equol lotion, which was applied both before and after SSUV significantly reduced the number of CPDs. This reduction was evident immediately after SSUV exposure, at 1 h after exposure, and at 24 h after exposure, revealing 54%, 50%, and 26% reduction in CPDs, respectively. When the same concentration was applied for 5 consecutive days after SSUV exposure, there was no significant difference in the reduction of CPDs immediately after SSUV irradiation or at 1 hour afterwards, but there were significant reductions of 23% and 42% at 24 and 48 h after SSUV exposure, respectively. Despite apparently reducing the number of CPDs post-SSUV, topically applied equol did not appear to increase the rate of dimer removal. To conclude, equol applied topically prior to SSUV irradiation offers protection against CPD formation in hairless mice, possibly by acting as a suncreen and thus inhibiting DNA photodamage.     

球孢白僵菌分生孢子乳悬剂的配方筛选

从6种常用的食品乳化剂中，筛选适合于球孢白僵菌（Beuaveia bassiana)分生孢子粉使用的乳化剂。除单二甘酯外，其余5种乳化剂的乳化性能与孢子浓度呈正相关。除十二烷基硫酸钠外，各种乳化剂均能以孢子极好地相容。综合乳化性、生物相容性、湿润力和其它理化特性、蔗糖脂肪酸酯S－1可作为白僵菌孢子粉较为理想的乳化剂，使用浓度为0．2％。以0．3％的羧甲基纤维素钠为稳定剂和0．1％的抗坏血酸作为紫外线保护剂，能显著提高孢子悬液在2h内的稳定性，并能较好地保护孢子免受紫外线损伤。     

微波辅助提取-紫外分光光度法测定柚皮中总黄酮含量

通过均匀设计试验考察及优化了微波辅助提取-紫外分光光度法提取柚皮黄酮的最适提取条件:微波辐射功率638W,辐射时间6min,乙醇浓度70%,固液比1:4。研究了紫外分光光度法测定柚皮中总黄酮含量的方法,以芦丁为参照品,测定波长为258nm,吸光度与芦丁浓度的线性范围在1.0～30цg/ml,相关系数R=0.9995,平均回收率为99.60%,相对标准偏差为1.0%。该方法简单、快速、准确,样品提取后不经分离可直接测定黄酮含量,是一种较理想的测定方法。     

双波长紫外分光光度法测定酒石酸泰乐菌素-盐酸多西环素可溶性粉的含量

建立了双波长紫外分光光度法同时测定酒石酸泰乐菌素-盐酸多西环素可溶性粉中酒石酸泰乐菌素和盐酸多西环素含量的检测方法。结果显示，吸收度与浓度呈良好线性关系。酒石酸泰乐菌素的平均回收率为99．90％，RSD为0．42％n=5）；盐酸多西环素的平均回收率为100．07％，RSD为0．74％（n=5）。     

畜禽用凝结芽孢杆菌菌剂制备工艺的初步研究

试验对畜禽用凝结芽孢杆菌的菌剂制备工艺进行了研究,结果表明:最适吸附载体为麦麸,发酵液经离心吸附菌体损失率较高,最适干燥方式为40℃恒温干燥,制剂生产过程中粉碎时间应严格控制在15 s内,在当前益生菌和抗生素联用的客观背景下,建议和金霉素联合使用,紫外吸收剂2(3,5-二叔丁基-2-羟苯基)-5氯苯并三唑对凝结芽孢杆菌制剂在紫外环境下保护作用最佳。     

紫外分光光度法测定硫酸链霉素的含量

采用紫外分光光度法测定硫酸链霉素的含量,检测波长323 nm.硫酸链霉素在12～48 mg/L的浓度范围内,其紫外吸收值与浓度呈线性关系,回归方程为A=0.012 1 C 0.000 5,r=0.999 9;平均回收率为99.82%,RSD为0.62%.