白纹伊蚊细胞色素P450CYP6N3基因分子进化机制初探

为了初步探讨白纹伊蚊细胞色素P450 CYP6家族新基因分子进化机理,根据已获得的白纹伊蚊溴氰菊酯抗性株一新的细胞色素P450CYP6基因cDNA片段,设计反向引物,进行5‘-cDNA末端快速扩增（rapid amplification of cDNA ends,RACE);以正向引物进行3‘-RACE。然后分别进行克隆,测序和鉴定。根据获得白纹伊蚊CYP6家族新成员全长cDNA序列,运用PC/CENE软件分析其5‘-UTP区DNA序列相似性及编码区氨基酸残基相似性,构建系谱树。结果获得的3个全长序列中5‘-UTP区DNA序列安全相同;编码区氨基酸残基相似性为3/497或4/497个氨基酸差异。而且此种差异均位于蛋白质功能非保守的基础区域;构建的系谱树显示CYP6N3基因与冈比亚按蚊CYP6N1-2亲缘关系最近,而与致倦库蚊的CYP6E1,CYP6F1亲缘关系较远。说明白纹伊蚊CYP6N3基因较致倦库蚊的CYP6E1,CYP6F1基因更为古老;白纹伊蚊CYP6N3各等位基因变异体是通过整个CYP6N3基因座的新近复制而产生。     

白纹伊蚊CYP6N3基因启动子序列的分子克隆与功能分析

根据本室已获得的白纹伊蚊CYP6N亚家族新成员CYP6N3全长cDNA的 5′ 末端核苷酸序列 ,设计 2个反向特异引物 (GSP1和GSP2 ) ,利用 4种限制性内切酶DraⅠ、EcoRⅤ、PvuⅡ和StuⅠ分别消化白纹伊蚊溴氰菊酯抗性株高分子量基因组DNA ,消化产物与适配子连接产生 4种消化的DNA库 ,并分别以此为模板 ,进行基因步移。用特异引物GSP1与适配子引物AP1进行第 1步PCR扩增 ,然后再以第 1步PCR产物为模板、用内部特异引物GSP2与内部适配子引物AP2进行第 2次PCR扩增。将扩增产物进行T A克隆及测序。结果显示 :分别以DraⅠ、EcoRⅤ、PvuⅡ和StuⅠ消化的DNA库为模板而获得 4个长短不一的DNA序列 :80 6bp、 2 190bp、 3 0 76bp和 2 2 0 6bp ,它们均包括有CYP6N3全长cDNA5′ 非翻译区序列及氨基端开头 10个氨基酸的编码序列 ;在其ATG上游序列中均存在有若干个典型的TATA盒、Barbie盒和 或CCAAT盒、抗氧化剂反应元件或外源化合物反应元件。表明本实验已成功地获得了白纹伊蚊溴氰菊酯抗性株CYP6N3基因 4个上游启动子区序列 ,并分析、讨论了它们在蚊虫中细胞色素P45 0基因多样性及其参与杀虫剂抗性中的作用     

白纹伊蚊CYP6N3基因启动子序列的分子克隆与功能分析

根据本室已获得的白纹伊蚊CYP6N亚家族新成员CYP6N3全长cDNA的5′-末端核苷酸序列,设计2个反向特异引物(GSP1和GSP2),利用4种限制性内切酶Dra Ⅰ、EcoR Ⅴ、Pvu Ⅱ和Stu Ⅰ分别消化白纹伊蚊溴氰菊酯抗性株高分子量基因组DNA,消化产物与适配子连接产生4种消化的DNA库,并分别以此为模板,进行基因步移.用特异引物GSP1与适配子引物AP1进行第1步PCR扩增,然后再以第1步PCR产物为模板、用内部特异引物GSP2与内部适配子引物AP2进行第2次PCR扩增.将扩增产物进行T-A克隆及测序.结果显示分别以Dra Ⅰ、EcoR Ⅴ、Pvu Ⅱ和Stu Ⅰ消化的DNA库为模板而获得4个长短不一的DNA序列806bp、2 190bp、3 076bp和2 206bp,它们均包括有CYP6N3全长cDNA5′-非翻译区序列及氨基端开头10个氨基酸的编码序列;在其ATG上游序列中均存在有若干个典型的TATA盒、Barbie盒和/或CCAAT盒、抗氧化剂反应元件或外源化合物反应元件.表明本实验已成功地获得了白纹伊蚊溴氰菊酯抗性株CYP6N3基因4个上游启动子区序列,并分析、讨论了它们在蚊虫中细胞色素P450基因多样性及其参与杀虫剂抗性中的作用.     

白纹伊蚊溴氰菊酯抗性株CYP6cDNA片段克隆、鉴定

根据家蝇CYP6A1,CYP6D1以及致倦库蚊CYP6E1的保守区氨基酸序列设计一组简并引物,采用RT-PCR的方法,从白纹伊蚊四龄期活体幼虫总RNA中扩增出与设计相符的基因片段。利用T-A克隆法,将获得的基因片段克隆入pGEM-Teasy载体。经限制性内切酶酶切和PCR鉴定证明重组成功。将筛选的阳性克隆经序列测定及同源性分析。表明共获得CYP6家族中9个的新cDNA序列。为进一步研究细胞色素P450的多样性及其与抗药性形成的分子机制打下基础。     

白纹伊蚊溴氰菊酯抗性株CYP6基因全长cDNA的快速扩增

根据本室已获得的白纹伊蚊溴氰菊酯抗性株CYP6家族成员cDNA序列片段，设计一对特异性引物．以上述蚊株总RNA为模板，分别进行5’-cDNA末端快速扩增(5’-RACE)和3’-cDNA末端快速扩增(3’-RACE)，所获得的产物经1．2％琼脂糖凝肢电薄，显示：5’-RACE产物达I.5kb，3’-RACE产物达500bp，扣陈两重叠部分的已知cDNA片段(250bp)，则该CYP6家族成员生长cDNA长度达1．75kb，与其它昆虫中已知的CYP6家旅全长cDNA长度相似；然后再分别切胶回收，并以此(RACE产物)为模板，用上述双引物进行PCR鉴定，结果显示2个RACE产物均包含有已知的250bp cDNA片段，提示所得的RACE产物为该CYP6家族成员生长cDNA。     

淡色库蚊(Culex pipiens Pallens)与击倒抗性(kdr)相关的钠通道基因突变

本研究采用RT-PCR技术,使用简并引物分别从淡色库蚊(Culex pipiens pallens)敏感品系和抗溴氰菊酯品系中扩增出钠通道ⅡS4～ⅡS6区域的基因片段,长度为359bp.该基因片段所编码的氨基酸与黑尾果蝇(Drosophila melanogaster)、家蝇(Musca domestica)、埃及伊蚊(Aedes aegypti)、冈比亚按蚊(Anopheles gambiae)及德国小蠊(Blattella germanica)等昆虫相应区域的氨基酸序列具有较高的同源性,其同源性分别为95.8%,95.0%,100.0%,98.3%和95.0%.经序列比对,确认抗溴氰菊酯品系淡色库蚊钠通道基因在1014位点发生了突变该位点的碱基"A"突变为"T",其对应氨基酸由亮氨酸(L)变为苯丙氨酸(F),该突变(L1014F型)在多种昆虫中较为常见.     

联合PCR技术克隆白纹伊蚊漆酶型酚氧化酶基因及其生物信息学分析

目的测定白纹伊蚊漆酶型酚氧化酶的基因的全长序列并用生物信息学方法分析其结构和功能。方法从白纹伊蚊卵、幼虫、蛹、雌蚊、雄蚊中提取总RNA,逆转录后以总cDNA为模板,设计简并引物进行巢式PCR,扩增部分序列后设计新的特异性引物补全5’端序列,使用3’-RACE法补全3’端序列,拼接全长后进一步进行生物信息学分析。结果通过巢式PCR扩增出1145bp的核苷酸序列,测序后设计5’端序列的下游引物,扩增出约900bp的核苷酸序列,设计3’端的上游引物,配合3’RACE试剂盒扩增出约600bp的核苷酸序列,寻找重复序列将三段序列进行拼接,得到国内外从未获得的长2244bp、编码747个氨基酸序列的白纹伊蚊漆酶型酚氧化酶基因的全长序列。生物信息学分析其与白纹伊蚊的相似性最高,为含信号肽的跨膜蛋白,含3个Cu氧化酶超家族位点,属于蓝色多铜氧化酶家族。结论联合PCR技术的应用使较长长度的基因序列的扩增更为方便、准确。为进一步对其进行功能的研究奠定了基础。     

埃及伊蚊表皮结构基因AaCPR100A序列特征和表达特性分析

Aa CPR100A是本实验室从埃及伊蚊RNAseq数据库中获得的预测与表皮结构相关的基因。本文拟通过生物信息学和分子生物学技术,探究埃及伊蚊表皮Aa CPR100A基因的序列特点,并分析其在埃及伊蚊的时空表达特征。埃及伊蚊表皮Aa CPR100A蛋白序列Aa CPR100A ORF长度为765 bp,编码254个氨基酸,蛋白分子量约为28.6 k Da,1~16位氨基酸残基为信号肽,其氨基酸序列中含有表皮蛋白CPR家族中的RR-1基序。埃及伊蚊与白纹伊蚊、致倦库蚊、冈比亚按蚊和黑腹果蝇的氨基酸同源性分别为95%、72%、61%、54%。qRT-PCR结果显示Aa CPR00A基因在表皮和卵期表达量最高,并随发育阶段呈现显著递减变化。结果表明,埃及伊蚊Aa CPR100A表达具有时空和组织特异性特征。     

白纹伊蚊Rh类糖蛋白基因的克隆与生物信息学分析

目的应用简并引物RT．PCR和RACE方法获取白纹伊蚊Rh类糖蛋白（Aedes albopictus rhesuslike glycoprotein,AaRh）基因的全长cDNA。方法根据冈比亚按蚊、埃及伊蚊等亲缘关系较近物种的Rh类糖蛋白同源性分析结果,在氨基酸高度保守区域184／343和219／337氨基酸位点设计2对简并引物,以白纹伊蚊雌蚊总RNA为模板,应用巢式RT—PCR扩增AaRh的基因片段。根据获得的AaRh基因部分序列,设计2对特异性引物AaRhGSP1、GSP2和AaRhGSP3、GSP4,应用5’RACE和3’RACE分别扩增AaRh基因的5’端和3’端cDNA片段,然后拼接出全长cDNA序列。通过在线生物信息学分析（NCBI和Expasy）,对目的基因序列进行生物信息学分析。结果应用2对简并引物进行巢式RT-PCR．获得379bpAaRh基因片段。应用5’RACE和3’RACE方法,分别获得AaRh基因5’端1008bp、3’端822bpcDNA序列,根据两个片段的首／尾共同序列拼接为1717bp的基因片段。该核苷酸序列经BLASTn分析显示,与埃及伊蚊Rh蛋白的一致性高达95％,鉴定其为白纹伊蚊Rh类糖蛋白基因。AaRh基因具有完整的开放阅读框,其ORF从第128位到1516位含1389bp,编码462个氨基酸。Expasy在线生物信息学程序分析显示,白纹伊蚊Rh类糖蛋白是一个整合膜蛋白,跨膜11次,58aa．446aa具有铵离子通道的结构功能域;理论等电点（pI）5．37,分子量49775．10Mr,laa-26aa可能为分泌信号肽序列;含有4个潜在的天冬酰胺糖基化位点和17个线性抗原决定簇,翻译后可能进行糖基化修饰,提示其为糖蛋白。结论成功获取AaRh基因的全长cDNA,生物信息学分析结果为AaRh蛋白的生物学特性和功能研究奠定了基础。     

白纹伊蚊和埃及伊蚊defensin A基因克隆及序列分析

应用PCR技术从白纹伊蚊和埃及伊蚊基因组中扩增出defensinA基因 ,并与文献报道的defensinA的5个型的cDNA序列进行同源性比较 ,发现此两序列中存在内元 ;从埃及伊蚊体内扩增的片段为蚊虫defen sinAl的前体AaDefAl;从白纹伊蚊体内扩增的片段为defensinA的 1个新型 ,命名为DefA6。     

Strategy for identifying the gene encoding the DNA polymerase of molluscum contagiosum virus type 1

Molluscum contagiosum virus (MCV) is a member of the family Poxviridae and pathogenic to humans. MCV causes benign epidermal tumors mainly in children and young adults and is a common pathogen in immunecompromised individuals. The viral DNA polymerase is the essential enzyme involved in the replication of the genome of DNA viruses. The identification and characterization of the gene encoding the DNA polymerase of molluscum contagiosum virus type 1 (MCV-1) was carried out by PCR technology and nucleotide sequence analysis. Computer-aided analysis of known amino acid sequences of DNA polymerases from two members of the poxvirus family revealed a high amino acid sequence homology of about 49.7% as detected between the DNA polymerases of vaccinia virus (genus Orthopoxvirus) and fowlpoxvirus (genus Avipoxvirus). Specific oligonucleotide primers were designed and synthesized according to the distinct conserved regions of amino acid sequences of the DNA polymerases in which the codon usage of the MCV-1 genome was considered. Using this technology a 228 bp DNA fragment was amplified and used as hybridization probe for identifying the corresponding gene of the MCV-1 genome. It was found that the PCR product was able to hybridize to theBamHI MCV-1 DNA fragment G (9.2 kbp, 0.284 to 0.332 map units). The nucleotide sequence of this particular region of the MCV-1 genome (7267 bp) between map coordinates 0.284 and 0.315 was determined. The analysis of the DNA sequences revealed the presence of 22 open reading frames (ORFs-1 to-22). ORF-13 (3012 bp; nucleotide positions 6624 to 3612) codes for a putative protein of a predicted size of 115 kDa (1004 aa) which shows 40.1% identity and 35% similarity to the amino acid sequences of the DNA polymerases of vaccinia, variola, and fowlpoxvirus. In addition significant homologies (30% to 55%) were found between the amino acid sequences of the ORFs 3,-5,-9, and-14 and the amino acid sequences of the E6R, E8R, E10R, and a 7.3 kDa protein of vaccinia and variola virus, respectively. Comparative analysis of the genomic positions of the loci of the detected viral genes including the DNA polymerases of MCV-1, vaccinia, and variola virus revealed a similar gene organization and arrangement.     

Cloning and sequence analysis of β-actin gene from Aedes albopictus (Diptera: Culicidae)

Objective: To obtain the complete β-actin gene from Aedes albopictus. Methods: Total RNA was extracted from C6/36 cells. Degenerate primers were designed based on the β-actin sequences of An. gambiae, Ae. aegypti, Cx. pipiens pallens and D.melanogaster. By RT-PCR, the product was amplified, purified, cloned into the pGT vector and sequenced. The β-actin sequence was aligned and phylogenetically analyzed by the BLAST program and the CLUSTAL W program. Results: A sequence of 1132 bp including an open reading frame of 1131 bp was obtained (GenBank DQ657949). The deduced protein had 376 amino acids.Aligned to SWISS-PROT, it exhibited a high level of identity with β-actins from Anopheles, Drosophila and Culex at the amino acid sequence level. Phylogenetic analysis indicated that Ae. albopictus β-actin was much more homologous with invertebrate β-actin than with vertebrate β-actin. Conclusion: The gene may be used as the internal control in the experiments of Ae. albopictus.     

Sequence variations in the introns of the triosephosphate isomerase genes of Oesophagostomum dentatum and O. quadrispinulatum

Degenerated primers were used to amplify DNA fragments of the triosephosphate isomerase (TPI) gene from complementary DNA (cDNA) and from genomic DNA of two species of porcine gastrointestinal nematodes, Oesophagostomum dentatum and O.quadrispinulatum. Polymerase chain reaction (PCR) fragments amplified from cDNA were 520 bp in size for both species, while genomic fragments were 1,035 bp for O. dentatum (GC-content: 45%) and 1,331 bp for O. quadrispinulatum (44%). Sequence analyses revealed blocks of high homology in the exons interrupted by more variable parts in the intron regions. Five exons were predicted from the genomic sequences in the conserved regions which corresponded to the respective cDNA sequences with 6% interspecific differences. The predicted protein sequences (161 amino acids) were 98% similar between the species and showed 71% similarity to the putative protein of Caenorhabditis elegans. As a housekeeping gene, TPI could be amplified from cDNA of both infectious third-stage larvae and adults. Interspecific variations in the non-coding regions allow the PCR-based differentiation of the two Oesophagostomum spp.     

Cloning transforming genes from human papillomavirus type 18]

Nucleotide sequences of type 18 human papilloma virus genes E6 and E7 inserted in human DNA cloned from cervical tumor are determined. The resultant sequences are compared to the prototype variant. Five point mutations not leading to replacement of amino acid residues in polypeptide chain and 1 substituting the amino acid in codon 129 are detected in gene E6 sequence. In E7 sequence, one significant mutation in codon 92 is detected. Both substitutions of asparagine for lysine are localized in the 3'-terminal region of the genes, which may not affect the transforming potential of these sequences. DNA fragments of E6 and E7 coding regions obtained by PCR were independently cloned in bifunctional expression vector DelpC7. The identity of hybrid E6 and E7 nucleotide sequences to initial ones is verified by sequencing.     

Cloning and nucleotide sequencing of Vero toxin 2 variant genes from Escherichia coli O91:H21 isolated from a patient with the hemolytic uremic syndrome

Cellular DNA extracted from Escherichia coli strain B2F1 (O91:H21) was found to contain two separate DNA sequences that hybridized with a Vero toxin 2 (VT2)-specific gene probe under stringent conditions. These two sequences were cloned and both were shown to encode a variant of Vero toxin 2 (VT2vh). The nucleotide sequences of the operons encoding VT2vh, designated as vtx2ha and vtx2hb, were determined. The two operons were nearly identical (99% overall DNA homology) and both encoded A subunits of 319 amino acid residues and B subunits of 89 amino acid residues, the A and B subunit genes being separated by a stretch of 14 bp. The A and B subunit genes of the vtx2ha operon exhibited 98.6% and 95.5% DNA homology, respectively, with those of the slt-II operon encoding Shiga-like toxin II (or VT2) cloned from a strain from a patient with hemorrhagic colitis, while the A and B subunit genes of the vtx2ha operon showed 94.5% and 82.8% DNA homology, respectively, with those of the slt-IIv operon encoding a SLT-II variant cloned from a strain isolated from a pig with edema disease. The nucleotide sequences of the presumed promoters and presumptive ribosome binding sites in the vtx2ha, vtx2hb, and slt-II, and slt-IIv operons were identical. These results indicate that nucleotide sequences encoding a family of VT2-related toxins are present in various strains of E. coli and that the sequences of the genes for A subunits are better conserved than those of the B subunit genes.     

Cloning and sequencing of a putative acetylcholinesterase cDNA from Boophilus microplus (Acari: Ixodidae)

Using a strategy based on degenerate primers derived from acetylcholinesterase (AChE) from other species, we cloned and sequenced a putative AChE cDNA from the southern cattle tick, Boophilus microplus (Canestrini). The sequence has a high degree of homology to sequences of AChE from other species reported in the GenBank. The open reading frame of 1,689 bp, corresponding to a deduced sequence of 563 amino acids, has conserved regions and features shared by the AChE family, necessary for its catalytic activity. No differences were found in the putative cDNA sequences from organophosphorus acaricide (OP) resistant and susceptible strains. The results suggest that this putative AChE gene is not involved in resistance to OP compounds as a mutated gene in the resistant strain studied. However, differences were detected, with a probe derived from this cDNA, in DNA fragments after digestion of genomic DNA from different strains with restriction nucleases. This indicates polymorphism in this gene in B. microplus.     

Nucleotide sequences and characterization of haemolysin genes from Aeromonas hydrophila and Aeromonas sobria.

Extracellular haemolysin is thought to be one of the important virulence factors in Aeromonas infection. Two extracellular haemolysin genes (AHH3 and AHH4) from Aeromonas hydrophila strain 28SA, one (AHH5) from A. hydrophila strain AH-1 and one (ASA1) from Aeromonas sobria strain 33 were cloned into cosmid and plasmid vector DNA in Escherichia coli. The nucleotide sequences of the open reading frames of AHH3 and AHH4 are both 1476 basepairs (bp), whereas AHH5 and ASA1 are 1455 and 1467 bp in length, respectively. The deduced amino acid sequences of AHH3, AHH4, AHH5 and the previously reported aerolysin from A. hydrophila showed a significant degree of sequence homology of over 90% each. The amino acid identity of the ASA1 haemolysin and those from A. hydrophila and Aeromonas trota aerolysins ranged from 58-68%. From DNA hybridization analysis using our cloned haemolysin genes as probes, we found that the AHH5 and ASA1 DNA probes hybridized with about 31 and 75% strains of motile Aeromonas species, respectively. The activity of haemolysins of cloned genes were different in medium agar containing various erythrocytes.     

成人型多囊肾病的基因诊断──PKD_1基因与其两侧四种基因探针的连锁分析

采用位于α３′ＨＶＲ同侧与成人型多囊肾病基因（ＰＫＤ１）更加接近的ｐＧＧＧ１及另一侧的２４－１和２１８ＥＰ６等探针对正常人基因组ＤＮＡ进行限制性片段长度多态性（ＲＥＬＰ）分析，分别检测各等位片段的频率，在此基础上，应用这三个基因探针与３′ＨＶＲ一起对２个成人型多囊肾病家系成员进行单体型分析，在这２个家系中，５个ＡＰＫＤ患者的ＲＦＬＰ单体型被证明与ＰＫＤ１基因相连锁，发现一个重组体，并检测出二个症状前个体。