烟草扭脉病毒云南分离物rtp基因克隆及序列分析

探究来自云南不同时间和不同地区的烟草扭脉病毒(TVDV)各分离物间rtp基因序列差异,分析烟草丛顶病近年在田间发生趋势减缓的原因.以2020—2022年从云南楚雄、大理、保山及红河采集的染病烟草样品为材料,对TVDV的rtp基因进行扩增和序列分析,共得到TVDV 7个不同分离物的rtp基因序列,长度均为2172 nt,包含618 nt的cp基因及1554 nt的rtd区;推导的TVDVRTP蛋白共编码722个氨基酸,其中包含CP蛋白的205个氨基酸,RTD的517个氨基酸.多重序列比对结果发现,获得的7个TVDV分离物与GenBank上登录的其他TVDV分离物间cp基因核苷酸序列一致性为98.71%~100%,不同TVDV分离物间CP蛋白的氨基酸序列一致性为98.05%~100%,存在4个氨基酸的差异.获得的7个TVDV分离物与GenBank数据库登录的其他TVDV分离物间rtd区核苷酸序列一致性为96.68%~99.81%,RTD蛋白的氨基酸序列一致性为96.52%~100%,存在39个氨基酸的差异.这些TVDV分离物rtp基因的变异可能会对TVDV的蚜虫传播效率产生影响,进而影响到烟草丛顶病在田间的发生与流行.

甜菜坏死黄脉病毒75kDa通读蛋白基因构建与表达

利用DNA重组技术,将甜菜坏死黄脉病毒(BNYVV)内蒙分离物的CP基因和54kDa通读区片段拼接,构建了BNYVV75kDa通读蛋白基因。序列分析表明,构建的75kDa通读蛋白基因与野生型相比,只有4个核苷酸发生了改变(包括将CP基因的终止密码子TAG改造为ATG),相应地2个氨基酸也发生了改变。将75kDa通读蛋白基因及其54kD。片段分别克隆到pJW2上,构建了这两个基因的原核表达载体。SDS-PAGE和Western blotting检测结果表明,75kDa通读蛋白基因在E.coli BL21(DE3)中经温度(42℃)诱导后除可特异地表达75kDa。蛋白外,还产生两种小蛋白。75kDa通读蛋白基因的54kDa片段只表达出37kDa的蛋白。

Molecular diversity of barley yellow dwarf virus-PAV from China and the Czech Republic

Wheat yellow dwarf disease(BYD),caused by different species of barley/cereal yellow dwarf viruses(B/CYDVs),is one of the most serious cereal diseases in China and the Czech Republic.Because genetic diversity of the virus directly influences disease epidemiology,the molecular diversity and population structure of 24 Chinese isolates and 16 the Czech Republic isolates of BYDV-PAV from different regions in two countries were analyzed by sequencing their coat protein(CP)and readthrough protein(RTP)domain(RTD)genes and comparing the sequences with six CP and 16 RTP sequences of BYDVPAV isolates from the NCBI database based on nucleotide identity position,phylogenetic analysis and nucleotide diversity.Nucleotide identities between the Chinese and the Czech Republic isolates for the CP were 76.6–99.4%,73.9–89.1%for RTD(ORF5),respectively.The Chinese and the other country isolates showed 74.7–99.2%nucleotide identity for RTP(ORF3+ORF5).Phylogenetic analysis of CP sequences showed that 20 Chinese isolates clustered in the same clade,but the other four Chinese isolates clustered in another clade with the isolates from the Czech Republic and other counties.The population of BYDV-PAV in China had greater nucleotide variability and was more divergent than that in the Czech Republic.Geographical and ecological factors but not hosts might contribute to the population differences in the two countries.

Cloning and expression of the Chinese wheat mosaic virus RNA2 coat protein read-through and 19 ku cysteine-rich domains and localization of these proteins

The 5’-terminal (RTn) and 3’-terminal (RTc) halves of the coat protein readthrough domain and the 19 ku cysteine-rich protein of Chinese wheat mosaic virus (CWMV) were amplified by RT-PCR, cloned and expressed in E. coll. Antisera and monoclonal antibodies against these proteins were prepared by immunising these purified proteins to mice. Detection of RTn, RTc and 19 ku proteins in CWMV infected wheat sap and leaf tissue indicated that the RTn and RTc proteins were distributed on the surface of virus particles whereas the 19 ku protein was in the cytoplasm of the infected wheat cells.

基因治疗药物无义突变通读活性检测方法的研究进展

30%人类致病基因突变属无义突变,无义突变可导致众多疾病。无义突变通读剂具有无义突变通读活性,可诱导基因恢复其功能,属于基因治疗药物。基因编码区发生的无义突变可致蛋白翻译在无义突变位点提前终止,导致蛋白功能缺失,引起包括遗传病、肿瘤在内的众多疾病。少数化合物具有无义突变通读作用,可诱导全长蛋白翻译,是一种潜在的治疗药物。目前通读剂活性检测方法主要包括蛋白质截短试验和报告基因系统两大类型。本文回顾了无义突变通读活性检测方法的发展及最新进展,为药物高通量筛选方法的建立提供参考。

无义突变型荧光素酶稳定表达细胞株的建立

目的:建立稳定表达含无义突变位点荧光素酶的细胞株,用以筛选新的无义突变通读剂。方法:酶切质粒p GL4-WT和p GL4-MUT,得到野生型和无义突变荧光素酶编码c DNA,分别插入到慢病毒载体p LVX-IRES-Neo多克隆位点。酶切及PCR鉴定后,将重组载体包装成慢病毒颗粒,感染HEK 293细胞,单克隆细胞抗性筛选获得稳定细胞株,提取总RNA,经逆转录PCR方法验证荧光素酶m RNA表达。最后用已知阳性无义突变通读剂G 418处理细胞,Western blot方法检测处理前后荧光素酶蛋白表达水平,同时分析荧光素酶活性。结果:经酶切获得2.7 kb长野生型和无义突变荧光素酶编码c DNA,与p LVX-IRES-Neo连接获得重组慢病毒载体p LVX-WT、p LVX-MUT,EcoRⅠ单酶切、NheⅠ与BamHⅠ双酶切结果证明序列正确插入,PCR也扩增出目的片段;稳定感染慢病毒的HEK293WT和HEK293MUT细胞经逆转录PCR方法成功检测到荧光素酶m RNA表达;阳性通读剂G 418处理细胞后发现,HEK293WT细胞在处理前后均表达荧光素酶蛋白,荧光素酶活性也基本相同,而HEK293MUT细胞在处理前不表达荧光素酶蛋白,无荧光素酶活性,处理后恢复了部分荧光素酶蛋白表达,其荧光素酶活性相当于HEK293WT细胞的20%。结论:成功建立了稳定表达无义突变荧光素酶的细胞株,可用于筛选新的无义突变通读剂。