建立以TK基因为标记将外源基因导入臭曲霉（Asper—gillus...

A new system for selection of transformed Aspergillus foetidus was reported. In this system, TK- A. foetidus which were constructed by homologous recombination of mutated TK gene of vaccinia virus with TK gene of A. foetidus were screened by adding BUdR in agar plates. Conditions for screen of TK+ A. foetidus strain, transformation of A. foetidus and selection of transformed TK- A. foetidus have been studied. By using this system, several transformed A. foetidus which contained HBsAg gene derived bf a promoter H8 cloned from genomic DNA of A. foetidus were isolated. It was demonstrated that HBsAg gene was integrated into the chromosome DNA of A. foetidus by Southern blot after many passages of spores. ELISA showed that HBsAg was positive in the growth medium (p/n = 20). The 22 nm particles which were very similar to the HBsAg particles in human serum were found in the growth medium by immunoelectromicroscope. Western blot also gave the specific bands. All these data showed that HBsAg gene was expressed in A. foetidus and the products were secreted into the growth medium. The selection system using TK gene as marker could generally be used to study the expression of foreign gene in A. foetidus.     

Cloning of α-amylase gene from Schwanniomyces occidentalis and expression in Saccharomyces cerevisiae

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臭曲霉(Aspergillus foetidus)启动子H8片段克隆及其序列

使用原核及真核菌通用的挑选启动子克隆载体pJGI,从臭曲霉菌体总DNA中分离到具有较好活性的启动子H8片段。根据Southern blot证明该启动子来自臭曲霉菌;H8全片段DNA序列分析结果表明其含有7 50bp,内含典型真核启动子功能序列(TA TA box)及增强子GTGG：TTTAAAG的相似序列,分析证实是一个新的臭曲霉启动子。初步实验表明该启动子不但在臭曲霉菌内有启动功能;并第一次证明来自臭曲霉菌的启动子在原核细胞中也具有启动子活性,能够表达完整的Lacz基因。     

极端嗜盐菌16SrDNA的PCR扩增

四株嗜盐菌Haloarcula vallismortis(EM201)、Haloferax denitrificans(EM303)、A_5和B_2已通过一对特定引物用PCR技术从总DNA中扩增出各自的16SrDNA片段,分子大小在1.47kd左右.DNA杂交也表明这些PCR产物具有嗜盐菌的同源性.     

美味侧耳病毒及其生化特性

自美味侧耳(Pleurotus sapidus)子实体中分离到两类病毒颗粒,一是球形,直径为25nm(少数为19、32am);一是杆状,具较深锯齿状亚基,大小为12～14×40～600nm,病毒具核蛋白吸收峰,最大吸收为E257nm,最小为242nm,ISCO蔗糖密度梯度离心中出现3个峰。 病毒具有分子量为44000和22000两条主要衣壳多肽,自子实体中提取到分子量约1.2×10~(?)道尔顿的dsRNA,可能是球形病毒的基因组,病毒与同属真菌糙皮侧耳(P,ostreatus)和德平菇(P,floride)球形病毒之间有血清学关系。     

协同凝集试验快速诊断葡萄扇叶病毒

本文描述一个新的试验方法,即协同凝集试验,用于检测葡萄扇叶病毒(GFV).检出GFV的最低浓度为4ng／ml,其灵敏度与ELISA检测病毒水平相当,而且更简便、快速。     

栗疫菌低毒力菌株dsRNA的分离及转移

自云南、广西、江苏、浙江、河北、京郊六个省市的板栗树(Castanea mollissima)溃疡斑上分离了栗疫菌(Endothia parasitica)160株,进行了dsRNA的提取及其毒力测定,获得两株含dsRNA的低毒力菌株(H),其毒力与带有起源于欧洲的dsRNA的低毒力菌株比较相近。比较国内菌株与欧洲低毒力菌株的dsRNA电泳谱带,示有共同分子量为5x106或6．2 x 108的电泳带。与正常毒力菌株(V)混合接种能显著降低致病力。这是欧美大陆发现低毒力菌株后,亚洲地区的首次报告。以5株具有欧洲dsRNA的低毒力菌株作为供体,与云南、江苏、浙江的10株毒力菌株配对,16％(8,50)的毒力菌株发生形态变化,dsRNA转入后毒力明显降低。结果表明,国内毒力菌株可以接受欧洲低毒力因子——dsRNA并转变为低毒力菌株。