转基因动物技术的研究进展

本文通过转基因动物技术的研究状况、目的、方法、用途及存在问题对该技术进行综述。     

转基因动物的分子生物学

分子生物学领域以惊人速度不断获得新的发现，加深了人们对于实验动物和家畜基因工程潜力的理解。近期一些重要的技术，如重组ＤＮＡ技术，基因克隆技术，基因表达的分子技术以及核酸和蛋白的序列分析技术，已获得进一步完善。这些分子技术与重组基因转移到活细胞和受精卵技术相结合，可以生产转基因小鼠和其他转基因动物，其应用前景是无限的。     

转基因动物研究进展

本文综述了转基因动物近年来的研究进展。着重对动物基因转移的方法、转基因动物的应用,以及转基因技术所存在的问题进行了初步探讨。     

转基因技术在动物育种中的研究应用进展

转基因技术在动物育种中的研究应用进展李福岭（山东滨州地区畜牧兽医研究所）转基因技术运用于动物育种的研究始于７０年代，经过近２０年的研究和不断发展，取得了突破性进展，不仅开始应用于鱼、泥鳅、小鼠、兔、羊、猪、牛等动物的遗传育种和抗病育种，而且利用转基因...     

转基因动物在药理学和毒理学研究中的应用

转基因动物技术在药理学和毒理学研究中的应用有十分广泛的前景。目前已建立了早老性痴呆，胰岛素依赖性糖尿病，直炎病毒感染和人类免疫病毒感染等多种复杂疾病的转因动物模型，用于新药的筛选和评价。此外，还制备了５－羟色胺受体缺陷小鼠，高血压转基因大鼠，γ干扰素基因和多药耐药基因缺陷转基因小鼠，分别用于５－羟色胺受体，肾素，白介素１２和多药耐药蛋白和药理特性研究。     

绿色荧光蛋白在转基因动物研究中的应用

来源于水母(Aequorea Victoria)的绿色荧光蛋白(Green fluorescent protein, GFP),现已成为细胞生物学和分子生物学中应用最广泛的分子标记之一.其内源性荧光基团在受到紫外或蓝光激发时可发现清晰可见的绿光.由于检测方便,对生物体基本没有毒性,在很多领域已有取代LacZ,荧光素酶等传统标记方法的趋势,在制作转基因动物过程中更是如此.本文综述了GFP在标记目的基因、筛选阳性胚胎等方面的应用.     

心脏组织特异性表达Cre重组酶转基因小鼠的建立

目的：建立在小鼠心肌细胞中特异性表达Cre重组酶的转基因小鼠。方法：构建了心肌细胞特异性表达Cre重组酶的转基因载体。该载体通过显微注射被导入小鼠受精卵中，通过胚胎移植，获得转基因首建者小鼠。利用PCR检测子代小鼠Cre重组酶整合情况。通过Northern杂交检测Cre重组酶表达的组织特异性。结果：构建了含有心肌细胞特异性α-肌球蛋白重链(α-MHC)启动子、Cre重组酶基因和人生长激素基因polyA的转基因载体α-MHC—Cre—hGH。将转基因载体进行显微注射，共注射了215枚小鼠受精卵，其中202枚移植入13只假孕母鼠的输卵管中发育，获得子代小鼠42只。PCR检测发现有1只小鼠在其基因组上整合有Cre重组酶基因。Northem杂交检测结果显示该转基因小鼠只在心脏组织中特异性地表达Cre重组酶基因。结论：成功获得了在小鼠心肌细胞中特异性表达Cre重组酶的转基因小鼠，为利用条件基因打靶技术研究基因在心脏发育与相关疾病中的功能提供了有利的工具。     

平滑肌细胞特异表达Cre重组酶转基因小鼠的建立

目的：建立平滑肌细胞特异表迭Cre重组酶的转基因小鼠。方法：用分子克隆的方法构建含有α平滑肌肌动蛋白(α-SMA)启动子、Cre重组酶基因和polyA的转基因载体α-SMA-Cre。以显微注射的方法将5．3kb的转基因片段引入小鼠基因组。通过PCR和LacZ染色以检测Cre重组酶在体内介导重组的功能。结果：共注射282枚受精卵，移植至10只假孕母小鼠的输卵管中发育，获得子代小鼠19只，经PCR鉴定有4只小鼠在基因组上整合有Cre基因，整合率为2l％。将该小鼠与基因组上携带LoxP位点的Smad4务件基因打靶小鼠交配，通过PCR在所有含有平滑肌细胞的组织基因组DNA中检测到重组后的234bp特异条带。与“报告”小鼠-ROSA26交配，LacZ染色后小肠壁平滑肌细胞中特异地检测到Cre重组酶活性。结论：成功构建了平滑肌细胞特异表达Cre重组酶的转基因小鼠．该小鼠在平滑肌细胞中特异表迭Cre重组酶，并能在体内成功地介导LoxP位点间的重组。     

复制型HBV转基因小鼠的建立与应用

尽管有了有效的疫苗,但乙肝病毒(HBV)感染依然是全球性公共卫生问题,在我国形势尤为严峻。由于HBV的自然宿主仅限于人和黑猩猩,现有的模型都有不同的缺陷,因此关于其生物学及治疗方法研究的诸多问题依然没有解决。复制型HBV转基因小鼠模型的建立,极大地提高了我们对HBV生活史、免疫生物学和肝脏病变的免疫发病机制的认识。本文简要介绍国际上由Francis V.Chisari实验室和国内由本实验室建立的复制型HBV转基因小鼠,以及利用该模型开展抗病毒药物和乙肝发病机制的研究工作。     

A sensitive and simple assay of saliva on stamps

Summary Identification of saliva on stamps or envelope flaps remains yet a not widely studied problem. In most forensic laboratories it is seldom carried out, but this fact does not reduce the importance of the assay.Most authors consider amylase a sufficiently specific marker of the presence of saliva; really, the only other human body fluid that contains high amounts of this enzyme is the pancreatic juice (and therefore feces).Here we present a simple and sensitive assay for the determination of -amylase that uses a commercially available and well-known substrate. It is hydrolyzed by amylase with the production of soluble blue fragments, that can be measured by photometry, obtaining objective results.The presented assay identifies 1×10^–6 diluted saliva or that present on 0.5 mg of a stamp; 16-year-old samples can also be identified.Intra-assay and day-to-day CV resulted in 10.8% and 13.7%, respectively. Owing to the high sensitivity of the test, handling samples or reagents can introduce contamination with saliva traces, giving false-positive results. Addition of EDTA 0.1 mol/l to the incubation mixture, lowering the sensitivity to 1 × 10^–3 diluted saliva, overcomes this problem.     

Validation of a novel fluorescent probe-based real-time PCR assay to detect saliva-specific unmethylated CpG sites for saliva identification

The identification of saliva from forensic samples is often important to establish what happened at a crime scene, especially in sexual assault cases. Recently, CpG sites that are specifically methylated or unmethylated in saliva have been reported as markers for saliva identification. In this study, we designed a fluorescent probe-based real-time polymerase chain reaction (PCR) assay for analyzing the methylation status of two neighboring CpG sites, which we previously found were saliva-specifically unmethylated. Specificity analysis using various types of body fluid/tissue samples demonstrated a probe detecting the unmethylation of the two CpG sites reacted only to saliva DNA, indicating this probe as an all-or-nothing marker for the presence of saliva DNA. Sensitivity analysis demonstrated that the detection limit was 0.5 ng saliva DNA as input for bisulfite conversion, while we confirmed a negative effect of larger amounts of non-saliva DNA on sensitivity in the analysis of saliva–vaginal DNA mixtures. We finally validated the applicability of this test to swabs from licked skin and bottles after drinking as mock forensic samples in comparison with other saliva-specific markers. We confirmed the potential usefulness of this test for skin samples, from which a saliva-specific mRNA was not detected reliably, while the ingredients in several beverages might affect methylation analysis. Given the simplicity of real-time PCR as well as the high specificity and sensitivity of the test, we believe the developed method is suitable for routine forensic analysis and can play an important role in saliva identification.     

The art of traditional native PAGE: The APLP 48-ID assay for human identification

When full STR profiles cannot be obtained, further DNA analyses targeting single nucleotide polymorphisms (SNPs) may occasionally yield valuable information. Although the discrimination power of each SNP is relatively low, combined analysis of many SNPs can improve the personal identification ability to a level as high as that of commercial STR typing kits. In this study, we developed a new SNP typing method, named the amplified-product length polymorphism (APLP) 48-ID assay, for genotyping of 47 autosomal SNPs and two X and Y chromosomal markers for sex typing. Forty-seven SNPs were selected from all 22 autosomes, showing high diversity in European, Nigerian, Han Chinese, and Japanese population in the HapMap data. PCR primers were designed to generate amplicons 40–100 bp in length to increase the robustness of the PCR.The APLP 48-ID assay consisted of four independent PCR reactions followed by electrophoretic run on four lanes in a polyacrylamide gel. Complete profiles were obtained when more than 1.2 ng of DNA was used. We applied this assay for genotyping of 236 Japanese individuals. The random matching probability was 3.3E-20, and the power of exclusion was greater than 0.9999999. This method is a rapid, robust, and cost-effective approach for human identification and paternity testing.     

Cre重组酶调控的OVA-HBsAg转基因乙肝模型小鼠的制备及鉴定

目的 制备Cre重组酶调控的卵清蛋白(OVA)-HBsAg转基因小鼠,为乙肝的防治提供更好的动物模型.方法 采用原核显微注射方法将线性化的携带OVA-HBsAg基因并带有LoxP位点的质粒注入C57BL/6J×DBA小鼠受精卵的雄原核内,制备受Cre重组酶调控表达的OVA-HBsAg转基因小鼠.将F1代OVA-HBsAg阳性母鼠与本室饲育的Alb-Cre转基因阳性公鼠进行杂交,获得子代小鼠,观察Cre对OVA-HBsAg转基因小鼠HBsAg的诱导表达情况.采用PCR、ELISA和免疫组化方法检测HBsAg基因、Cre基因在转基因小鼠体内的整合及表达情况.结果 共注射受精卵491枚,成活337枚,成活率68.6％.产下F0代小鼠29只,其中PCR阳性4只,外源基因整合率13.8％.目前已传至F4代,F1-F4代PCR阳性率分别为27.5％、32.0％、22.9％、25.0％,ELISA法未检测到血清中HBsAg表达.将F1代OVA-HBsAg阳性母鼠与Alb-Cre阳性公鼠杂交,获得16只子代小鼠,PCR检测Cre基因和HBsAg基因双阳性的子代小鼠有6只,其中2只小鼠血清HBsAg检测为阳性,诱导表达阳性率为33.3％.结论 成功制备出OVA-HBsA转基因小鼠,且可稳定传代,Cre重组酶可以诱导小鼠体内HBsAg的表达.     

1.3拷贝C基因型HBV转基因小鼠的制备及检测

目的制备1.3拷贝C基因型HBV转基因小鼠,为乙肝的防治提供较好的动物模型。方法采用受精卵显微注射法,制备1.3拷贝C基因型HBV转基因小鼠;采用PCR、ELISA、荧光定量PCR和免疫组化方法检测HBV基因在转基因小鼠体内的整合、复制和表达情况。结果共注射受精卵2282枚,成活2024枚,注射成活率88.7%。共移植假孕雌鼠72只,59只怀孕,假孕雌鼠妊娠率81.9%。共产下F0代小鼠185只,PCR检测共有19只整合阳性,阳性率10.3%。血清荧光定量PCR结果显示,其中6只小鼠有HBV DNA复制,拷贝数为102~103拷贝/ml;经传代产下F1代小鼠96只,PCR检测HBV DNA阳性33只,阳性率34.4%。血清荧光定量PCR结果显示,其中10只小鼠有HBV DNA复制,拷贝数为102~103拷贝/ml;F0代和F1代小鼠随机分别各取3只进行肝脏和肾脏HBsAg免疫组化检测结果均为阳性,且肾脏表达高于肝脏。结论 1.3拷贝C基因可以在上述制备成功的C型HBV转基因小鼠体内复制和表达,并且可以遗传给下一代。     

视蛋白基因启动子的克隆和鉴定

目的 克隆出视蛋白基因启动子。方法 以小鼠全基因组为模板，用PCR法克隆出目的大小的片断。然后连接到T-载体上作酶切鉴定，最后测序。结果 酶切结果与预期相符，测序结果与公布序列完全一致。结论 视蛋白基因启动子克隆成功。     

慢病毒介导的绿色荧光蛋白转基因小鼠的制备及鉴定

目的以携带绿色荧光蛋白(GFP)的慢病毒为载体制备转基因小鼠,建立慢病毒介导的转基因动物制备技术平台。方法将慢病毒表达载体FUGW与ViraPowerTMLentiviral Packaging Mix按1∶2比例混合,用LipofectamineTM2000转染293FT细胞,包装出的病毒经浓缩后以293T细胞测定病毒滴度。采用受精卵卵周隙显微注射的方式制备转基因小鼠。出生小鼠用PCR法检测GFP基因整合情况,并在荧光体视显微镜下鉴定外源基因的表达情况。结果病毒包装过程中,转染后24h即可见GFP表达,72h时293FT细胞的转染效率达95%以上,镜下可见大量绿色荧光。包装出的慢病毒滴度为106U/ml,经浓缩后可达108U/ml。PCR检测显示,F0代小鼠GFP PCR阳性率为70.27%(26/37)。荧光体视显微镜下观察荧光小鼠所占比例,F0代为65.2%(15/23),F1代为55.0%(11/20),荧光强度在两代个体中相当。F0代、F1代中GFP均呈广泛表达。结论制备出携带GFP可传代的转基因小鼠,建立了慢病毒载体介导的转基因小鼠制备技术平台。     

A vertebrate-specific qPCR assay as an endogenous internal control for robust species identification

The identification of vertebrate species is important in numerous fields including archaeology, ecology, as well as food and forensic sciences. Real-time quantitative PCR (qPCR) assays specific for one vertebrate species are promising approaches for species identification, although there are several drawbacks such as difficulty determining whether the detected DNA is authentic or a contaminant. Here, we describe a qPCR assay specific for vertebrate mitochondrial DNA (mtDNA) which can overcome these drawbacks. Since we found that mitochondrial 16S rRNA contains regions that are perfectly (not highly) conserved across virtually all vertebrates, but are variable in invertebrates, we were able to design a vertebrate-specific qPCR assay by placing primers/probe within these regions. The specificity and accuracy of this assay were validated with representative vertebrate and invertebrate samples. This assay detected DNA from all vertebrate samples, but not from any invertebrate samples. In addition, this assay was able to quantify vertebrate mtDNAs as accurately as previously reported species-specific qPCR assays. The results demonstrated it is feasible to quantify vertebrate mtDNA specifically and accurately in a sample. This means that it is possible to determine the ratio of specific vertebrate species mtDNA to total vertebrate mtDNA in a sample. In conjunction with this assay as an endogenous internal control, species-specific qPCR assays will allow for the robust identification of vertebrate species.