犬瘟热病毒的静水压灭活

以250MPa的静水压力对犬瘟热病毒（CDV）处理30min之后，CDV被灭活，由其制成的灭活疫苗诱导犬产生中和抗体的能力明显优于传统的福尔马林灭活疫苗，免疫保护率达90％。电镜观察显示，经不同程度静水压力处理后的CDV粒子均发生变形，表面呈现凸起，但CDV H基因部分片段的RT－PCR扩增结果揭示，高达510MPa的静水压力作用30min也未能使其基因片段受到破坏。     

Nuclear transfer in loach (Paramisgurnus dabryanus Sauvage) by cell-to-cell electrofusion

To study nuclear transfer in the loach (Paramisgurnus dabryanus Sauvage), blastula and gastrula cells were fused with UV-inactivated oocytes by cell-to-cell electrofusion. To facilitate nuclear transfer, blastula and gastrula cells were cultured or incubated at 4 °C in different solutions. TC-199 medium supplemented with 20% calf serum was the best culture solution, and effectively retained the totipotence of blastula or gastrula cells for up to 10 days. It was found that gastrula cells incubated at 4 °C had the same totipotence as blastula cells. The optimal UV dosage for inactivation of the oocyte chromatin was 180–240 mJ cm⁻². Electrofusion was carried out in a cone-shaped fusion chamber, which permitted the recipient oocyte and the donor blastula cell to contact one another. The electrofusion procedure resulted in a 10% success rate of normal-appearing fish. Genetic analysis indicated that the nuclear material originated from the donor cell (blastomere) and the oocyte pronucleus did not take part in development.     

不同处理方式对蔬菜种传病毒病的消毒效果评价

为了研究不同种子处理对种子传播病毒的灭活效果,试验以番茄、辣椒、甜瓜、南瓜种子样本中被番茄花叶病毒(ToMV)、烟草花叶病毒(TMV)、黄瓜花叶瓜病毒(CMV)感染的种子为研究对象,经过酶联免疫吸附测定(ELISA)和逆转录聚合酶链反应(RT-PCR)测试选择出研究材料,采用7种病毒失活处理方法,分别为醋酸、过氧化氢、盐酸、次氯酸钠浸种,干热处理,温汤浸种和臭氧熏蒸处理。结果发现,能有效减少病毒浓度的处理为盐酸浸种、干热处理、温汤浸种(65℃)和臭氧(10 g/m3)处理,分别能将种子传播病毒的浓度平均降低51%、50%、42%和32%。其他灭活方法治疗效果较差,病毒浓度平均降低了12%~27%。盐酸浸种和干热处理是最有效的方法,对种子出芽率和活力没有影响。     

超临界CO_2对哈密瓜汁中大肠杆菌的杀灭效果研究

以哈密瓜汁中的大肠杆菌为研究对象,采用超临界CO_2技术(压力10、20、35 MPa,温度35、45、55℃),以温度、压力、保压时间为自变量,以大肠杆菌存活对数为因变量,对哈密瓜汁中大肠杆菌进行超临界CO_2(SCCO_2)杀菌效果的研究。采用一级反应动力学模型分析超临界CO_2对大肠杆菌的杀菌动力学;采用透射电镜观察超临界CO_2对大肠杆菌超微结构的影响。试验结果表明,在35～55℃、10～35 MPa的条件下对哈密瓜汁中大肠杆菌进行超临界二氧化碳处理,灭菌速率分为先快后慢两个阶段;随温度和压力的提高,大肠杆菌的灭菌速率均逐步上升;经超临界二氧化碳处理后,大肠杆菌细胞出现明显的缺陷,部分细胞壁消失。     

基于核酸适配体的PCR法检测溶藻弧菌及其灭活菌

溶藻弧菌(Vibrio alginolyticus)分布广,数量多,发病率高,是水产养殖中常见的条件致病菌,而对溶藻弧菌进行快速准确的识别鉴定是其病害防治的前提和基础。核酸适配体,因为具有较高的亲和特异性,在微生物的识别鉴定方面展现出了巨大的优势。本文利用核酸适配体和适配体筛选产物,通过结合、洗涤、加热分离、PCR扩增以及电泳检测等步骤,对溶藻弧菌进行了检测鉴定。结果表明,适配体和筛选产物都能对溶藻弧菌及其灭活菌进行较好的识别鉴定,适配体筛选产物对溶藻弧菌的检测下限为10~3cfu/mL,而对其灭活菌的检测下限为10~2cfu/mL,适配体对溶藻弧菌及其灭活菌的检测下限都可达到10 cfu/mL。该方法对溶藻弧菌有较好的亲和特异性,并能较好地区分溶藻弧菌与哈维氏弧菌等水产常见病原菌,在水产病害的检测中显示了较好的应用前景。     

多价噬菌体分离筛选及靶向灭活土壤病原菌的应用研究

农田土壤中残留和滋生多种病原菌会对人体健康和生态环境带来显著的安全隐患,开展针对性的生物修复研究十分迫切。噬菌体疗法靶向灭活土壤中病原菌的技术为修复此类污染土壤提供了全新途径。本研究以南京城郊某奶牛场牛粪堆积池周边,粪肠杆菌和假单胞菌复合污染农田土壤为例,首先筛选和纯化获得两株专一型噬菌体(YSZ1和YSZ5),再人为加速其宿主谱的表达过程,获得对应的多价噬菌体(YSZ1R和YSZ5K),并进行生物学特性(形态、核酸、最佳感染复数、一步生长曲线等)鉴定,结果表明:在水相和污染土壤中不同噬菌体对于同步灭活病原菌的能力依次为YSZ5KYSZ1RYSZ5YSZ1,并且施用多价噬菌体疗法有助于维护和改善修复后土壤微生物生态功能多样性与稳定性。本研究结果可为噬菌体疗法靶向灭活土壤中多种病原菌提供切实可行的修复技术。     

高密度二氧化碳对蛋清液中沙门氏菌和大肠杆菌杀菌效果和杀菌动力学的研究

研究了不同温度、压力和时间条件下,高密度二氧化碳(DPCD)处理对蛋清液中沙门氏菌和大肠杆菌的杀菌效果,并对DPCD处理蛋清液中大肠杆菌的杀菌动力学进行了分析。结果表明,在15 MPa,45℃下DPCD处理60 min,沙门氏菌和大肠杆菌分别降低了4.46和5.57个对数值,其中大肠杆菌对DPCD处理较沙门氏菌敏感。30 MPa,45℃,DPCD处理30 min,可以完全杀灭蛋清液中的大肠杆菌。线性模型能较好地拟合DPCD对大肠杆菌的杀菌效果,其中30 MPa,45℃下D值最小为5.830。     

超声技术在食品杀菌及废水处理中应用的研究进展

介绍了超声的定义和超声杀菌的机理。综述了近些年来超声在食品杀菌及废水处理领域的研究进展,重点阐述超声与其他技术结合使用的杀菌效果,并提出了超声在这些领域中的研究发展方向。     

双亲灭活原生质体融合技术在草菇耐低温菌株选育上的应用

为了选育耐低温草菇菌株,以草菇V23、V3552为亲本,采用酶解法制备原生质体,用紫外诱变、化学诱变两种方法对草菇菌株进行诱变,筛选到耐低温的突变株;然后利用紫外灭活（20 W,30 cm,110 s）和热灭活（50℃ 3 min）的双亲灭活标记法对突变株进行化学融合,结果表明在400 g/L的PEG6000、pH 8.0、融合时间30 min和融合温度32℃的条件下融合率最高,达到0.517%, 共获得200个融合子。经过0℃低温筛选,最终获得15株草菇耐低温菌株,菌丝在0℃的耐冻能力提高了4.5倍。经出菇实验证明其子实体与出发菌株相比具有明显的耐低温性,液化现象明显推迟,说明该方法筛选出的菌株具有进一步应用开发的价值。     

Effect of sulphur in the prevention of incipient iron chlorosis in corn

Abstract

Results of a field experiment, comprising elemental S and three commercial preparations of Fe, applied with and without several other factors showed that the application of S was significantly better than that of Fe supplying materials in preventing the incipient chlorosis of corn leaves on the alkaline calcareous soils. Prevention of chlorosis in corn due to sulphur application increased the grain yield of corn 25–31%.

Leaf samples from plants raised with Fe supplying materials were chlorotic even though they contained significantly higher amounts of Fe. Persistence of chlorosis in spite of high Fe content of leaves, vis a vis freedom from chlorosis in spite of low Fe content, suggest that deficiency of Fe was not a factor in chlorosis. Freedom from chlorosis accompanied by significant increases in corn yields due to S application, on the contrary, show that it was the lack of S rather than Fe as the cause of Chlorosis.

When the supply of S is low, Fe seems to be subjected to a great deal of chemical inactivation and under conditions of stress more and more absorption of Fe is necessitated. In all probability the rate of inactivation exceeds the rate of absorption and chlorosis develops. In this situation either the plant's ability to utilize iron is affected or the physiological availability of absorbed iron is very low. Increased S seems to arrest the process of Fe inactivation by providing a better nutritional environment.