EFFECTS OF A SYNTHETIC POLYPEPTIDE ENCODED BY THE p14-6,A cDNA CLONE WITH ANTIONCOGENE ACTIVITY, ON MALIGNANT TRANSFORMED DT CELLS

A synthetic polypeptide, pt27, which is encoded by a cDNA clone with antloncogene activity, p14-6, is found to be able to reduce remarkably the soft agar colony formation ability of part of DT cells and to raise their resistance to the ouabaln toxtcity. This shows that the pt27 peptide can affect the DT cells In a manner similar to the p14- 6 done and provides evidence that the reverting action of the p14-6 to DT cells may be exerted by the expression of its cDNA.

Isolating cDNA clones from rice induced by Magnaporthe grisea using PCR based differential screening method

The differential hybridization technique hasbeen widely used to identify genes that are dif-ferentially expressed.However,this approachhas several drawbacks.First,the screeningprocedures are rather labor-intensive and time-consuming.Second,the amount of phageDNAs transferred onto the two filters may notbe equivalent,which leads to an inaccurate se-lection of a positive clone.Third,isolation ofphage DNA is slow and cumbersome.Here,aPCR based differential screening method that

IDENTIFICATION AND SEQUENCE OF A cDNA CLONE CORRESPONDING TO A GENE INVOLVED IN DEVELOPMENT OF UNDARIA PINNATIFIDA

During the induction of gamete-producing gametangia, induced gametophytes werecollected at 4 days intervals (0,4,8, 12 d) and total RNAs were isolated by CsCl gradient ultracentrifu-gation. Some stage-specific expressed mRNAs were identified by differential display of mRNAs from dif-ferent developing stages of the gametophytes. The cDNA of one specific mRNA was verified, cloned andsequenced. This gene was specifically expressed during 4 days of induction, and had partial homologoussequence with tobacco IAA-binding protein gene. It suggests that this cDNA may represent a gene whichis related to the LAA regulating function during the development of the gametophytes.

白菜种子cDNA酵母文库的构建及BrTTG1互作蛋白的筛选及分析

【目的】通过构建白菜种子的cDNA文库,筛选WDR 40蛋白TRANSPARENT TESTA GLABRA 1(TTG1)的互作蛋白,探究TTG1参与MBW三元复合体调控种皮原花青素形成的分子机制。【方法】以棕籽白菜自交系‘B147’的种子为材料,提取总RNA并建立cDNA文库,通过gateway技术构建诱饵载体pGBKT7-TTG1并进行酵母双杂交筛库。【结果】酵母文库库容为1.2×10^(7)CFU,文库滴度是5.0×10^(7)CFU/mL,插入片段平均长度大于1000 bp,诱饵载体在酵母中无自激活活性。通过构建的诱饵载体pGBKT7-TTG1与构建的cDNA文库杂交,共获得了38个阳性互作蛋白,功能预测显示其中一个蛋白注释为MYB转录因子,注释为MYB73,序列分析结果显示该基因含有R2R3-MYB型抑制子保守基序C1和C2,推测该基因为白菜中参与种皮颜色形成的R2R3-MYB型抑制子,暗示着白菜中可能存在不同MYB转录因子参与的调控网络,影响着原花青素的形成。【结论】本研究构建了白菜种子组织的酵母双杂交cDNA文库,获得了38个TTG1阳性互作蛋白,首次挖掘到了可能影响白菜种皮颜色原花青素形成的R2R3-MYB型抑制子MYB73,为后期探究白菜种皮原花青素的调控网络奠定良好的基础。

Recovery of a Far-Eastern Strain of Tick-Borne Encephalitis Virus with a Full-Length Infectious cDNA Clone

Tick-borne encephalitis virus(TBEV) is a pathogenic virus known to cause central nervous system(CNS) diseases in humans, and has become an increasing public health threat nowadays. The rates of TBEV infection in the endemic countries are increasing. However, there is no effective antiviral against the disease. This underscores the urgent need for tools to study the emergence and pathogenesis of TBEV and to accelerate the development of vaccines and antivirals. In this study, we reported an infectious c DNA clone of TBEV that was isolated in China(the WH2012 strain). A beta-globin intron was inserted in the coding region of nonstructural protein 1(NS1) gene to improve the stability of viral genome in bacteria. In mammalian cells, the inserted intron was excised and spliced precisely, which did not lead to the generation of inserted mutants. High titers of infectious progeny viruses were generated after the transfection of the infectious clone. The cDNA-derived TBEV replicated efficiently, and caused typical cytopathic effect(CPE) and plaques in BHK-21 cells. In addition, the CPE and growth curve of cDNA-derived virus were similar to that of its parental isolate in cells. Together, we have constructed the first infectious TBEV cDNA clone in China, and the clone can be used to investigate the genetic determinants of TBEV virulence and disease pathogenesis, and to develop countermeasures against the virus.

Modification of the full-length cDNA clone of Newcastle disease virus isolated from an outbreak in the goose

A 6.5-kb specific fragment containing the T7 promoter and the transcription vector was excised from the full-length cDNA clone of the Newcastle disease virus(NDV)strain ZJI of goose origin,and thereafter it was self-ligated to form a high quality plasmid for mutagenesis.Site-directed mutagenesis was used for inserting three additional G nucleotides(nts)into the region between the T7 promoter and the leader sequence of the NDV genome.RT-PCR was employed to amplify the F/HN gene fragments,and then they were ligated by the shared restriction enzyme BsmBI.Finally,the corresponding fragment in the mutant full-length cDNA was substituted with the new one.The sequencing results showed that the three additional G nts were successfully inserted and the mutant nts in the full-length cDNA were corrected.This study lays a good foundation for research on the reverse genetics of NDV strain ZJI.

Engineering infectious foot-and-mouth disease virus in vivo from a full-length genomic cDNA clone of the A/AKT/58 strain

Two full-length genomic cDNA clones, pTA/FMDV and pCA/FMDV, were constructed that contained three point-mutants [A174G and A308G (not present in pTA/FMDV); T1029G] in the genome compared with the wild type A/AKT/58 strain of foot-and-mouth disease virus. These two viruses were rescued by co-transfection of pCA/FMDV with pCT7RNAP, which can express T7 RNA polymerase in BHK-21 cell-lines, or by transfection of the in vitro transcribed RNA. Their biological properties were analyzed for their antigenicity, virulence in suckling-mice (LD50) and growth kinetics in BHK-21 cells. The in vivo rescued viruses showed high pathogenicity for 3-day-old unweaned mice (LD50=10?7.5). However, the in vitro transcribed RNA derived from pTA/FMDV had lower pathogenicity for suckling-mice (LD50=10?6), and the in vivo transcribed RNA recovered from pCA/FMDV co-transfected with pCT7RNAP showed no significant differences from the wild type virus. These data showed that recovery of the infectious foot-and-mouth disease virus directly from the use of in vivo techniques was better than from in vitro methods. Furthermore, the reverse genetic procedure technique was simplified to a faster one-step procedure based on co-transfection with pCT7RNAP. These results suggest that in vivo RNA tran- scripts may be more valuable for engineering recombinant foot-and-mouth disease virus than in vitro RNA transcripts, and may contribute to further understanding of the biological properties, such as replication, maturation and quasispecies, of the foot-and-mouth disease virus.

Sequencing and rescuing a highly virulent classical swine fever virus: Chinese strain cF114 from a full-length cDNA clone

The complete nucleotide sequence of classical swine fever virus (CSFV) strain cF114 (F114 strain propa- gated on PK-15 cells) was cloned by RT-PCR. The analyses of nucleotide and amino acids identity between cF114 and F114, Brescia, Alfort or C strain were 99.41%, 96.80%, 86.03%, 95.70% and 99.28%, 98.54%, 93.33%, 97.41% re- spectively. The cDNA fragments with correct sequence were ligated into a full-length cDNA and inserted into pMC18 plasmid (pMC12297). A full-length infectious viral RNA was synthesized by runoff transcription and transfected to PK15 cells. Viruses were recovered from transfected cells which wese titrated on PK-15 cells by endpoint dilution and indirect immunofluorescence with a CSFV-specific monoclonal antibody. The antigenicity and replication kinetics of the plasmid-derived virus (vM12297) were similar to the parental virus in vitro. The E01 or E2 gene was replaced with the genes from strain C and the pM/CE01 and pM/CE2 with chimeric full-length cDNA of cF114 were generated. The infectious viruses were obtained from pM/CE01 and pM/CE2. Both of the chimeric viruses can infect PK-15, SK- 6 and primary testicle cell of swine. The chimeric viruses can grow to a titer of 8?05 F-PFU/mL. These results are very important for understanding the genes related to the CSFV propagation and pathogenesis.

盖塔病毒SC483株cDNA感染性克隆的构建

【背景】盖塔病毒(Getah virus,GETV)是一种由蚊虫传播的病毒,分类学上属于披膜病毒科甲病毒属成员。该病毒宿主范围广,可感染猪、马、牛、狐狸等多种哺乳动物,人也可以感染,但在人群中造成的危害尚不知晓。动物感染主要临床表现为发热、皮疹、关节炎、繁殖障碍和死胎。GETV在世界范围内流行较为广泛,近年来在我国的流行呈上升趋势,2018年我国南方多个猪场爆发该病,GETV在畜禽养殖及公共卫生方面的危害渐渐受到人们的关注。目前,尚无用于预防和治疗盖塔病毒感染的商业化疫苗和药物。由于对GETV研究较少,其生物学特性、对不同物种的致病性和致病机制以及流行趋势在很大程度上均是未知的。【目的】建立高效的GETV反向遗传操作平台,为深入研究GETV基因组结构与功能、致病机制以及开发新型疫苗奠定基础。【方法】采取化学合成的方式人工合成了两端分别含有锤头状核酶(HamRz)和丁肝病毒核酶(HdvRz)序列的GETV SC483株基因组全长,并克隆至低拷贝pOK12-CMV载体中,从而获得含有GETV SC483株基因组全长cDNA克隆的重组质粒pGETV-SC483。将纯化的重组质粒pGETV-SC483转染BHK-21细胞进行病毒拯救。对拯救病毒进行连续传代、鉴定以及生物学特性分析,并对感染性克隆质粒pGETV-SC483在大肠杆菌中的遗传稳定性进行验证。【结果】重组质粒pGETV-SC483转染BHK-21细胞后,48 h即可观察到GETV感染引起的典型细胞病变,获得的拯救病毒命名为rSC483。分别提取拯救病毒和亲本病毒基因组RNA,对病毒基因组进行RT-PCR扩增、Not I酶切以及序列测定。结果表明,拯救病毒不同于亲本病毒,其含有人为引入以消去Not I酶切位点的G4332A突变的分子标记。使用GETV特异性抗体作为检测抗体的间接免疫荧光试验和病毒粒子形态学电镜负染观察结果进一步表明,GETV拯救成功。噬斑形成试验和一步生长曲线试验结果表明,拯救病毒与亲本病毒具有相似的复制能力和增殖特性。另外,感染性克隆质粒pGETV-SC483在大肠杆菌DH5α中连续传代后的测序结果表明,该重组质粒具有良好的遗传稳定性。【结论】成功构建了稳定、高效的GETV SC483株全长cDNA感染性克隆,为GETV生物学特性及致病机理研究以及新型疫苗开发提供了技术平台。

猫杯状病毒HRB-SS株感染性cDNA克隆的构建与病毒的拯救

为构建猫杯状病毒(FCV)HRB-SS株的感染性克隆,本研究合成3’端含有丁肝病毒核酶(HdvRz)序列的HRB-SS株全长基因组序列,将该序列插入p OK12-CMV载体,获得含FCV HRB-SS全长基因组cDNA克隆的重组质粒p FCV-HRB-SS。将重组质粒p FCV-HRB-SS转染猫肾细胞(CRFK),48 h即可观察到典型细胞病变,将病变细胞的上清接种未感染的CRFK细胞进行传代培养,连续传5代,从感染的细胞上清中获得拯救病毒。采用FCV VP1蛋白MAb,经间接免疫荧光试验检测,结果显示拯救病毒与亲本病毒均可观察到特异性绿色荧光,而未感染病毒的对照组细胞无荧光信号;各组细胞负染色后经电镜观察均可见病毒粒子呈典型的杯状结构。提取拯救病毒和亲本病毒基因组RNA,反转录为c DNA作为模板,经RT-PCR扩增、Kpn I酶切鉴定及测序分析,结果显示,拯救病毒含C^(5724)G位点突变的分子标记,消除了Kpn I酶切位点,不同于亲本病毒。上述结果表明获得拯救病毒r FCV HRB-SS。采用蚀斑形成试验和绘制病毒的一步生长曲线进一步检测r FCV HRB-SS,结果显示,r FCV HRB-SS与亲本病毒具有一致的复制水平和体外生长能力。本研究利用真核启动子构建的FCV HRB-SS株全长感染性cDNA克隆系统可直接在细胞内转录,减少了体外操作流程,有效防止了操作污染,具有操作简便,拯救效率高的优势,为后续FCV基因功能的研究和新型疫苗的研发奠定了基础。

Bioinformatics and Expression Pattern Analysis of Tomato ns LTP 2-like cDNA full-length Gene Clone

TDF1(transcription-drived fragment) was homologous to the predicted S. lycopersicum nonspecific lipid-transfer protein,nsLTP 2-like(91%), and it was significantly upregulated in response to C. fulvum(cladosporium fulvum) infection in tomato plants.In this experiment, the full-length cDNA of nsLTP 2-like was cloned using RACE technology based on the sequence of TDF1(GenBank: JZ717725). A full-length, 625 bp(GenBank: KU366289), cDNA sequence, which with 98% similarity to nsLTP 2-like gene(GenBank: XM015233692) was obtained. This cDNA contains an ORF(open reading frame) with full-length of 345 bp, coding of 114 amino acids, including 12.3% Ala and Gly. Protein molecular weight was 11.51 ku, the isoelectric point(pI) was 8.99, and average overall hydrophilicity was 0.412, with one phosphorylation sites, belonging to volatile acidic nuclear protein. Secondary structure prediction showed that α-Helix accounts for 30.7%, extension chain for 12.28%, β-corner for 9.65%, and random coil for 47.37%. Through comparative analysis of the homology among species, it was found that the amino acid sequence of tomato nsLTP 2-like protein had a high similarity with other plants, and with a specific conserved sequence which might related features in nsLTP 2-like protein. It also be analyzed the gene expression pattern of tomato in different parts and under different stress conditions.The results showed that nsLTP 2-like gene was up-regulated in varying degrees, under the condition of cold stress, exogenous hormone spraying and cladosporium fulvum infection. Therefore, it was speculated that the gene played a role in response to abiotic and biotic stress in tomato.

SCREENING A CDNA LIBRARY FOR PHOSPHOLIPASE A2 CLONES USING BLOOD AGAR PLATES

A technique was developed for detecting venom phospholipase A2(PLA2) using serum and red blood cells. M1 and M2, two PLA2s isolated from Crotalus m.molossus (Northern black-tail rattlesnake), were used for preliminary development of the as say. Various combinations of human, sheep, rat, and mouse red blood cells (RBC) with human,rat,and mouse sera were tested on their effectiveness to detect PLA2.Complete hemolysis (b hemolysis) was evident in the plate with rat RBC mixed with mouse serum.No hemolysis was detected in plates containing human RBC and human serum. Human RBC mixed with mouse serum proved to be ideal, even though this combination displayed incomplete hemolysis(a hemolysis).Susceptible RBC, in conjunction with rat or mouse serum, are excellent indicators for the presence of PLA2.Mixtures of RBC and serum in combination with BB4(E. coli) cells,λbacteriophage,and IPTG on LB agar plates provide an excellent detection system for cDNA clones that express venonl PLA2. Hemolysis surrounding a plaque is identified as positive for PLA2.

Isolation of a vernalization-related cDNA clone(VRC) using mRNA differential display in winter wheat

Vernalization is an essential factor which affects the flowering development in cold_requiring plants. There is a key stage of nucleic acid and protein metabolism in the process of vernalization in winter wheat. To probe into the molecular determinants of vernalization , we examined mRNA populations in differently_treated plumules of winter wheat \%(Triticum aestivum \%L. \%cv\% Yanda 1817) using mRNA differential display. One vernalization_ related cDNA clone \%(VRC), VRC54\%, was identified and was only expressed at the key stage of 20 d vernalization, rather than at other stages of nonvernalization, 4 d vernalization and devernalization. Northern blot and sequence analysis indicated that \%VRC54\% was a novel vernalization_related clone found in higher plant which not only might play an important role in the floral induction in vernalization_requiring plants but also was different from the cold_acclimatized genes.

苎麻纤维素合成酶基因cDNA的克隆及表达分析

以苎麻[Boehmeria nivea(Linn.)Gaud.]栽培种湘苎3号为材料,通过简并引物RT-PCR结合RACE技术首次成功克隆苎麻纤维素合成酶基因BnCesA15′端450bp序列以外的全部cDNA序列,序列长3276bp,编码一段938个氨基酸的蛋白质。经基因比对及蛋白质结构分析确证是苎麻纤维素合成酶基因。半定量RT-PCR分析显示:BnCesA1在苎麻根、茎、叶和芽组织中均有表达,其表达量为茎>叶>芽>根,相对表达量依次为0.791、0.381、0.319和0.183。从其表达模式可以推测该基因同时参与了苎麻细胞初生和次生细胞壁纤维素的合成。

中国对虾蜕皮抑制激素全长cDNA的克隆及序列分析

对虾的蜕皮活动由蜕皮抑制激素和蜕皮激素调控 ,蜕皮抑制激素是甲壳动物CHH家族神经肽的成员之一 ,通过抑制Y器官蜕皮激素的合成而调节蜕皮。以中国对虾 (Fennropenaeuschinensis)眼柄总RNA为材料 ,采用cDNA末端快速扩增 (RACE)方法 ,首次得到蜕皮抑制激素的全长cDNA (GenBank登录号 :AF4 6 9187)。该全长cDNA大小为 6 97bp ,是由 32 0bp的 3′RACE产物和 4 6 8bp的 5′RACE产物拼接而成。Blast搜索结果显示 ,该全长cDNA与甲壳动物的MIH基因序列具有较高的相似性 ;用ClustalX进行多序列比较结果表明 ,由该全长cDNA推导的氨基酸序列与对虾类的MIH的氨基酸序列同源性最高 ,其中与日本对虾、斑节对虾、刀额新对虾MIH的同源性分别为95 1%、83 1%、79 1%。根据以上数据 ,推断该 6 97bp的全长cDNA为编码中国对虾MIH前体的cDNA。进一步序列分析表明 ,编码中国对虾MIH前体cDNA包括 312bp的开放阅读框、81bp的 3′UTR和 30 2bp的 5′UTR ;编码 10 3个氨基酸的MIH前体分子包括信号肽和成熟肽 ,信号肽由 2 8个氨基酸组成 ,成熟肽由 75个氨基酸组成 ,成熟肽中6个半胱氨酸非常保守。

低温诱导的黄瓜ccr18基因的cDNA克隆及其表达特性分析

采用mRNA差异显示银染技术克隆得到在黄瓜 (CucumissativusL .)冷敏型品种“津研 4号”低温锻炼中特异表达基因的cDNA克隆 (ccr18) ,其大小为 6 39bp。在基因组中以单拷贝或低拷贝形式存在。Northernblot分析显示ccr18基因在 12、2 4、48和 72h低温处理的黄瓜中表达 ,在 6h低温处理及对照中没有表达。这表明ccr18基因与黄瓜低温锻炼相关。序列同源性比较表明 ,它与拟南芥 (Arabidopsisthaliana)染色体ⅢBAC库中的F14P3基因组序列具有 88%的同源性。

人胚鼻咽上皮细胞cDNA文库的构建及鼻咽癌相关基因的筛选

为了进一步分离人鼻咽组织特异性表达基因和鼻咽癌特异相关基因 ,采用SMART (switchingmechanismat 5′endofRNAtranscript)技术 ,构建了人胚鼻咽上皮cDNA文库 .从原代培养的人胚鼻咽上皮分离总RNA并纯化mRNA ,利用经修饰的oligo (dT)引物 (含sfiⅠB酶切位点 )合成cDNA第一链 ,同时根据真核生物mRNA5′端帽子结构特点 ,利用SMART核苷酸 (含sfiⅠA酶切位点 )作为cDNA第一链在mRNA 5′端延伸出去的模板 ,进而以此序列为引物利用LD PCR (long distance PCR)合成双链cDNA ,双链cDNA经sfiⅠ (ⅠA和ⅠB)酶切和过柱分级分离后 ,克隆入经sfiⅠ酶切的λTrip1EX2载体后经体外包装而成cDNA文库 .结果表明 ,原始人胚鼻咽上皮cDNA文库获得 1 0× 10 6个重组子 ,重组率达 96 % .文库扩增后 ,滴度达 7 8× 10 9pfu ml,插入cDNA平均长度为 1 2kb ,用PCR从该文库扩增出本实验室新克隆的鼻咽癌相关基因NAG4的全长cDNA .构建的人胚鼻咽上皮cDNA文库具有良好的质量 ,该cDNA文库为进一步筛选。

血管生成抑制因子K4K5 cDNA基因的克隆及其在毕赤酵母中的表达

应用PCR方法 ,扩增人纤溶酶原cDNA基因中K4K5cDNA片段 ,与酵母表达载体 pPIC9K重组 ,获得表达质粒p9kkk 18。该质粒转化毕赤酵母菌GS115 ,用G418 YPD筛选高拷贝表型 ,PCR筛选K4K5cDNA与酵母染色体整合形成的阳性克隆 ,阳性克隆用甲醇诱导表达。表达产物r K4K5分子量约 2 1 5kD ,占分泌总蛋白 80 %以上 ,产物浓度为 15 0～ 2 5 0mg/L。初步纯化产物抑制牛毛细血管内皮 (BCE)细胞增殖与鸡胚绒毛尿囊膜 (CAM )新生血管生成。

半滑舌鳎脑芳香化酶基因cDNA克隆及表达分析

为研究脑型芳香化酶(P450aromB)在半滑舌鳎性别分化中的作用,采用同源克隆策略,从半滑舌鳎脑分离了2184bp长的脑型芳香化酶的全长cDNA,该基因编码498个氨基酸。氨基酸序列和系统发育分析表明,P450aromB属于脑型P450arom,P450aromB的氨基酸序列与其他鱼类脑型P450arom的同源性较高(48.3%-66.1%),与性腺型P450arom的同源性较低(34.2%-49.9%),与自身的性腺型芳香化酶同源性为45.1%。RT-PCR分析表明:P450aromB mRNA的表达具有明显组织特异性,P450aromB只在性腺、脑、鳃和皮肤中表达,且脑中表达量远高于性腺,而在雌雄鱼的其他组织中都不表达。经过甲基睾酮浸浴处理和高温诱导半滑舌鳎由雌性性反转为雄性后,脑中P450aromB的表达量降低,这些结果表明P450aromB参与了半滑舌鳎的性腺分化和性别决定过程。

油茶ACP基因的全长cDNA克隆及序列分析

酰基载体蛋白是脂肪酸合成中的关键蛋白质,位于脂肪酸合成酶系的中央,作为脂酰基的载体将脂酰基从一个酶反应转移到另一个酶反应.以油茶近成熟种子cDNA文库和EST文库为基础,采用分子生物学技术分离克隆了油茶酰基载体蛋白基因全长cDNA序列.结果表明:油茶酰基载体蛋白基因的全长cDNA为669bp,包含1个完整的CDS及3′UTR和5′UTR,编码141个氨基酸,该基因被命名为co-acp并提交至GeneBank,登录号是EU717697;油茶酰基载体蛋白基因的推导氨基酸序列与其它15种植物的ACP进行AlignX比较的结果表明,油茶酰基载体蛋白与油橄榄ACP的相似性最高,而且遗传距离最近;预测油茶酰基载体蛋白的二级结构以α螺旋为主,没有跨膜结构域和信号肽,其等电点约为4.995.