中国人肠道产甲酸草酸杆菌frc基因的分离及其在真核细胞中的表达

目的：探讨中国人肠道产甲酸草酸杆菌甲酰辅酶A转移酶基因（frc）的分离、克隆和鉴定。方法：提取中国人肠道产甲酸草酸杆菌的基因组DNA,利用PCR技术扩增frc基因片段并克隆入真核表达载体pEGFP—C1,重组质粒命名为pEGFP—frc,通过限制性内切酶酶切电泳和测序鉴定插入片段。将pEGFP—frc通过脂质体转染293细胞,通过逆转录PCR（RT—PCR）和蛋白印迹（Western blot）分别从mRNA和蛋白水平检测frc基因在真核细胞中的表达。结果：中国人肠道产甲酸草酸杆菌fre基因全长1287bp,存在53个碱基和4个氨基酸残基的变异,与GenBank中的frc基因的碱基序列的同源性为95．88％,氨基酸残基序列的同源性为99．07％。转染293细胞后24-72h,可观察到明亮的绿色荧光,RT—PCR和Western blot分别从mRNA和蛋白水平上检测到frc基因在真核细胞中的表达。结论：中国人肠道产甲酸草酸杆菌中可以分离出frc基因;中国人肠道产甲酸草酸杆菌frc基因存在一定的变异;frc基因可在真核细胞293细胞中表达。     

产甲酸草酸杆菌FRC基因慢病毒表达载体构建及鉴定

产甲酸草酸杆菌(Oxalobacter formigenes,Ox.F)是一种寄居于脊椎动物胃肠道、依赖分解肠道草酸生存的革兰阴性菌[12].我们采用基因克隆重组技术从前期分离培养的中国人肠道Ox.F[3]中克隆了草酸分解关键酶--甲酰辅酶A转移酶(FCoAT)基因FRC,并成功构建重组慢病毒表达载体pLenti6.3-FRC-IRES-EGFP,为高草酸尿症基因治疗提供基础.     

表达产甲酸草酸杆菌草酸分解基因的人肝细胞系的构建

目的：构建表达产甲酸草酸杆菌（Ox．F）草酸分解基因的人肝细胞系,探索高草酸尿的治疗方法。方法：分离培养人肠道Ox．F并克隆其功能基因OXC和fre,构建同时表达OXC和fre的真核双表达载体质粒pIRES—oxc-frc,将pIRES-oxe—fre转染人正常肝细胞系L—02。用RT—PCR和Western blot技术了解转基因细胞的目的基因表达状况;用离子色谱法测定转基因后细胞培养液中草酸浓度,了解其草酸分解功能。结果：转基因后人肝细胞系L-02在mRNA和蛋白质水平均成功表达OXC和fre基因,其草酸分解功能较转染前明显增强（P〈0．01）。结论：Ox．F分解草酸的两个重要功能基因OXC和frc能在体外转入人正常肝细胞（L-02）中,并使后者草酸分解能力明显增强。转草酸分解基因的人肝细胞系的构建,有望用于高草酸尿,尤其是PH的病因治疗,值得进一步研究．     

克隆与表达产甲酸草酸杆菌代谢基因Frc及临床意义

目的研究产甲酸草酸杆菌草酸代谢基因Frc转化大肠杆菌BL21后稳定表达代谢草酸相关性酶--甲酰辅酶A转移酶(FCoAT)对草酸的降解效能。方法成功培养产甲酸草酸杆菌后,采用PCR方法从产甲酸草酸基因组中获得Frc基因,克隆到pMDTM19-T载体上进行测序,得到正确的基因片段。经双酶切将目的基因片段插入到原核表达载体PGEX-4T-2上,测序正确后,转化大肠杆菌BL-21,IPTG诱导表达GST-FCoAT融合蛋白,表达产物行western-blot鉴定分析。结果重组克隆载体pMDTM19-Frc经测序鉴定序列正确。成功构建融合原核表达质粒PGEX-4T-2-Frc,大肠杆菌BL21成为载体,并稳定表达可溶性融合蛋白GST-FCoAT的同时获得代谢草酸潜能。结论克隆产甲酸草酸杆菌Frc基因,成功构建PGEX-4T-2-Frc载体,并转化大肠杆菌BL21,能稳定表达可溶性融合蛋白GST-FCoAT,具有代谢草酸潜能,为肠道细菌获得代谢草酸潜能,减少胃肠道内草酸的吸收,降低尿液中草酸含量和临床防治草酸结石的研究奠定理论基础。     

真核表达载体 pcDNA3.1-h转化生长因子-β1的构建

目的：为研究软骨细胞基因转染的可行性创造条件,从而为基因修饰的软骨组织工程研究奠定基础。方法：应用基因重组技术和限制性内切酶酶切构建并鉴定pcDNA3.1-TGF-β1真核表达载体,经Fugene6介导质粒转染3T3细胞后应用逆转录－聚合酶链反应（RT－PCR）检测hTGF-β1 mRNA在真核细胞中的表达。结果：重组真核表达载体pcDNA3.1-TGF-β1经限制性内切酶Xho I和Hind Ⅲ酶切,电泳后显示1．35kb的hTGF-β1目的片段和5．40kb的pcDNA3.1载体片段,证明重组质粒连接正确;经RT－PCR检测了hTGF-β1在转录水平mRNA的表达情况,表明质粒转染3T3细胞后hTGF-β1mRNA的表达明显增强。结论：重组真核表达载体构建正确,并能在真核细胞3T3中表达hTGF-β1 mRNA,为其在软骨组织工程中的基因转染奠定了基础。     

产甲酸草酸杆菌甲酰辅酶A转移酶基因和草酰辅酶A脱羧酶基因慢病毒表达载体的构建及鉴定

目的 构建国人肠道来源产甲酸草酸杆菌(OxCF)甲酰辅酶A转移酶(FCoAT)基因(FRC)和草酰辅酶A脱羧酶(OCoAD)基因(OXC)的重组慢病毒pLenti6.3-FRC-IRES-EGFP和pLenti6.3-OXC-IRES-DsRED,为高草酸尿症的基因治疗奠定基础.方法 采用Taq高保真DNA聚合酶从OxCF基因组中扩增FRC基因和OXC基因片段,用DNA凝胶回收试剂盒切胶回收,用DNA连接试剂盒将回收产物分别与pMD18-T Simple载体连接获得FRC和OXC的克隆载体,并转化大肠杆菌DH5α感受态细胞,挑取阳性克隆并测序,筛选携带完整目的基因质粒pMD18T simple-FRC和pMD18T simple-OXC,用BamH Ⅰ酶切获得目的基因,连接FRC和携带绿色荧光蛋白的pLenti6.3/v5DEST-IRES-EGFP,连接OXC与表达红色荧光蛋白的pLenti6.3/v5 DEST-IRES-DsRED,转化DH5α后挑取阳性克隆并测序.构建的慢病毒过表达载体pLenti6.3-FRC-IRES-EGFP和pLenti6.3-OXC-IRES-DsRED转染HEK293T细胞,包装并测滴度.结果 聚合酶链反应(PCR)从OxCF基因组中扩增分获得1.3kb和1.7kb的DNA片段,与Genbank中FRC( U82167)间碱基序列匹配率为95.88％,存在53个碱基的变异;与Genbank中OXC( M77128)间碱基序列匹配率为93.61％,存在109个碱基的变异;测序证实pLenti6.3-FRC-IRES-EGFP和pLenti6.3-OXC-IRES-DsRED分别含有大小正确的正向FRC cDNA和OXC cDNA,转染HEK293T细胞实验24h后,在荧光显微镜下相应可见大量绿色荧光和红色荧光,两种慢病毒滴度分别为1.15×108 TU/ml和9.75×107 TU/ml.结论 成功构建表达OxCF中草酸分解关键基因FRC和OXC的重组慢病毒载体,并通过转染293细胞制备了高滴度慢病毒.     

人睾丸基因TDRG1重组真核载体的构建及其表达

目的 构建人睾丸基因TDRGl的真核表达质粒,并研究其表达.方法 取人新鲜正常睾丸组织,提取总RNA,采用逆转录.聚合酶联链反应(RT-PCR)扩增TDRG1基因编码序列;将该基因克隆到真核表达载体pYD5中,构建真核细胞表达载体pYD5-TDRG1,用限制性内切酶酶切分析,DNA序列分析鉴定重组质粒;将测序正确的重组质粒pYD5-TDRG1在脂质体介导下转染293细胞,间接免疫荧光法和Western Blot法鉴定目的 蛋白质的表达.结果 RT-PCR扩增出TDRGl基因编码序列,目的 插入片段长约303bp:产物行限制性内切酶酶切后连接到真核表达载体pYD5,重组质粒pYD5-TDRG1经酶切及DNA测序鉴定构建成功:该质粒转染293细胞48h后在荧光显微镜下可观察到绿色荧光,阳性细胞率96.42%;行Western blot分析检测到约39-8kD的目的 蛋白表达.结论 成功构建了人类睾丸基因TDRG1的真核表达载体pYD5-TDRG1,TDRG1基因在293细胞内成功表达.     

人肠道产甲酸草酸杆菌的分离培养

目的探讨产甲酸草酸杆菌分离培养及鉴定方法。方法应用选择性培养基,在37℃厌氧环境下分离培养人肠道产甲酸草酸杆菌。通过观察菌落形态、细菌涂片染色镜检、离子色谱仪及核酸序列分析,对细菌进行鉴定。结果产甲酸草酸杆菌菌落形态为白色点状或梭状,大小约(0.1~0.5)mm×(1.0~3.0)mm;菌落周边出现直径约3.5~4.5 mm的清晰透明圈。该细菌为革兰氏阴性杆菌,大小约(1.0~1.6)μm×(3.0~6.5)μm。液体培养基中草酸浓度随细菌浓度增加而逐渐下降。与文献报道核酸序列比较,该细菌分解草酸的功能基因frc、oxc的核酸同源性分别为95.8%及93.6%。结论产甲酸草酸杆菌可通过选择性培养基、在厌氧环境下从人粪便中分离出来。     

大鼠ETFβ基因过表达对NADPH氧化酶基因表达的影响

目的:构建大鼠ETFβ的重组质粒并检测其在人胚胎肾293T细胞中的表达和对NADPH氧化酶的影响。方法:应用RT-PCR方法从大鼠肾脏组织总RNA中扩增出编码ETFβ的cDNA,克隆至pUM-T载体并测序,然后亚克隆至真核表达载体pcDNA3.1/V5-His,酶切鉴定后测序,测序正确后用磷酸钙共沉淀法瞬时转染HEK293T细胞,使用RT-PCR方法检测空载体组和重组质粒转染组的NADPH氧化酶各亚基mRNA水平的表达变化。结果:(1)测序结果证实PCR扩增得到编码ETFβ的cDNA序列正确;(2)磷酸钙共沉淀法转染HEK293T细胞后,ETFβ融合蛋白成功表达;(3)RT-PCR结果显示重组质粒转染组的NADPH氧化酶5个亚基中的NOX3,NOX4的mRNA表达降低(P<0.05),空载体组和重组质粒转染组之间比较NOX1,NOX2,NOX5的mRNA表达差异无统计学意义。结论:成功构建大鼠ETFβ的重组质粒,该重组质粒可在HEK293T中过表达,并且降低了NADPH氧化酶NOX3,NOX4的mRNA表达水平。     

携带白蛋白启动子和IDO基因重组腺病毒的构建

目的 构建携带小鼠白蛋白启动子和IDO基因的重组腺病毒载体,研究肝脏Hepa l石细胞的IDO基因mRNA及蛋白表达情况.方法 酶切含有小鼠全长IDO cDNA的IDO质粒,亚克隆至穿梭载体pAdTrack.ALB上,在BJ5183细菌中和AdEasy-1进行同源重组,生成并筛选阳性克隆,测序、鉴定正确后,转染AD-293细胞进行包装、扩增,检测病毒滴度,RT-PCR和荧光显微镜鉴定重组腺病毒转染AD-293细胞后IDO的表达.重组腺病毒进一步感染Hepa 1-6细胞,RT-PCR和WesternBlot法分别检测IDO基因在细胞内表达情况.结果 经酶切及测序证实携带白蛋白启动子和IDO基因重组腺病毒载体构建成功,RT-PCR检测到转染后AD-293细胞内IDO的表达,病毒感染滴度为2.9×10~6pfu/ml.感染Hepa 1-6细胞后,RT-PCR和Western Blot可以检测到IDO mRNA水平和蛋白水平表达.结论 构建了携带白蛋白启动子和IDO基因的重组腺病毒载体.     

Detection and identification of oxalate-degrading bacteria in human feces.

BACKGROUND: Oxalate is detoxified (catabolized) via the action of two enzymatic proteins, formyl coenzyme A transferase (encoded by the frc gene) and oxalyl coenzyme A decarboxylase (encoded by the oxc gene), contained in the cytosol of Oxalobacter formigenes that colonizes the human intestinal tract. It is speculated that oxalate-degrading bacteria decrease oxalate absorption from the intestines and their absence in the gastrointestinal tract correlates with the formation of calcium-oxalate urolithiasis. METHODS: Two methods of detection and identification of this bacterial strain were studied in human fecal samples collected from Japanese subjects. Genomic DNA was isolated from bacterial culture, and specific 16S rDNA was amplified by polymerase chain reaction (PCR) followed by sequencing. The oxc gene was amplified directly from human feces by PCR using the specific primers. RESULTS: Oxalate-degrading bacteria were identified by comparing the sequences of 16S rDNA. The oxc gene was directly detected from human feces by PCR. It was ascertained that a combined PCR detection method using both 16S rDNA and the oxc gene allows for identification of O. formigenes in human fecal samples. CONCLUSION: This detection and identification method of oxalate-degrading bacteria using 16S rDNA and oxc gene should be applied in examination of clinical samples.     

Molecular identification of Oxalobacter formigenes with the polymerase chain reaction in fresh or frozen fecal samples.

OBJECTIVE: To develop a simple and rapid polymerase chain reaction (PCR) method for detecting Oxalobacter formigenes (which degrades oxalate in the gut) in fecal specimens from healthy volunteers and patients with urolithiasis, and to determine whether O. formigenes can be detected in frozen or fresh fecal samples. MATERIALS AND METHODS: Whole bacterial DNA was isolated directly from fresh and frozen fecal samples obtained from 30 healthy volunteers free from urolithiasis and from fresh fecal samples obtained from 38 patients with urolithiasis. Genus-specific oligonucleotide sequences were designed, corresponding to homologous regions residing in the oxc gene that encodes for oxalyl-coenzyme A decarboxylase. A PCR-based assay was used on both fresh and frozen fecal samples, and the nucleotide sequences analysed to confirm oxc. RESULTS: A PCR product of 416 bp encoding the oxc gene was detected in 23 (77%) of 30 healthy volunteers free from urolithiasis and in 14 (37%) of 38 patients with urolithiasis. In healthy volunteers, the results of PCR for the fresh and the frozen samples were identical in each subject. The nucleotide sequence analysis showed that the sequence of the amplified product was compatible with that of oxc. CONCLUSION: O. formigenes can be identified easily and efficiently using this PCR-based detection system. The colonization rate of O. formigenes in patients with urolithiasis was significantly lower than that in healthy volunteers known to be free from urolithiasis. Furthermore, as the PCR-based assay results in the frozen fecal samples were identical to those from fresh samples in each subject, immediate processing of fecal samples may not be necessary to detect O. formigenes in the clinical setting.     

Molecular epidemiology of fecal Oxalobacter formigenes in healthy adults living in Seoul,Korea

BACKGROUND AND PURPOSE: Oxalobacter formigenes is a member of the intestinal flora that degrades oxalate. This bacterium maintains an important symbiotic relation with its hosts by regulating oxalic acid absorption in the intestine as well as oxalic acid concentrations in plasma. We tried to define the prevalence of fecal O. formigenes positivity in healthy adults. MATERIALS AND METHODS: Whole-bacterial DNA was isolated directly from fresh stool samples obtained from 233 healthy adults known to be free of urolithiasis. Genus-specific oligonucleotide sequences corresponding to homologous regions residing in the oxc gene that encodes oxalyl-coenzyme A decarboxylase were designed. A PCR-based assay was done on the stool samples. RESULTS: A PCR product of 416 bp encoding the oxc gene was detected in 197 of the 233 stool samples (76.8%). Adjusted to the Seoul population census 1995, the calibrated fecal O. formigenes-positive rate was estimated to be 76.7%: 79.2% in men and 74.2% in women, with no significance difference according to age or sex. CONCLUSION: These results suggest that O. formigenes inhabits the intestine of three fourths of the normal Korean populations. These data provide a base for further studies to uncover the relation between O. formigenes and urolithiasis.     

人β神经生长因子基因真核表达载体的构建与表达

目的 构建人NGF-β基因真核表达载体并观察其在子鼠脊髓神经干细胞内的表达.方法 应用逆转录-聚合酶链反应(RT-PCR)从人脑肿瘤旁组织总RNA中扩增出750 bp片段,将其克隆至真核表达载体pcDNA3中经酶切鉴定产生750 bp和5.2 kd)的片段,完成序列分析.分离培养E14子鼠脊髓神经干细胞,以非脂质体转染试剂FuGENE HD介导质粒peDNA3-hNGFb转染培养第3代的细胞,应用免疫细胞化学和Western blot鉴定NGF-β在细胞内的表达.结果 RT-PCR产物为750 bp的片段,重组质粒peDNA3-hNGFb经双酶切产生750 bp和5.2kd)的片段,测序结果与文献报道结果完全一致.免疫细胞化学、Western blot结果表明NGF-β能在细胞中正确表达.结论 成功构建了peDNA3-hNGFb真核表达载体,其转染的子鼠脊髓神经干细胞能正确表达NGF-β.     

Presence of Oxalobacter formigenes in the intestinal tract is associated with the absence of calcium oxalate urolith formation in dogs

The incidence of calcium oxalate (CaOx) urolithiasis in dogs has increased steadily over the last two decades. A potential mechanism to minimize CaOx urolithiasis is to reduce enteric absorption of dietary oxalate by oxalate-metabolizing enteric bacteria. Enteric colonization of Oxalobacter formigenes, an anaerobe which exclusively relies on oxalate metabolism for energy, is correlated with absence of hyperoxaluria or CaOx urolithiasis or both in humans and laboratory animals. We thus hypothesized that decreased enteric colonization of O. formigenes is a risk factor for CaOx urolithiasis in dogs. Fecal samples from dogs with CaOx uroliths, clinically healthy, age-, breed- and gender-matched dogs, and healthy non-stone forming breed dogs were screened for the presence of O. formigenes by quantitative PCR to detect the oxalyl CoA decarboxylase (oxc) gene, and by oxalate degrading biochemical activity in fecal cultures. Prevalence of O. formigenes in dogs with CaOx uroliths was 25%, compared to 50% in clinically healthy, age-, breed- and gender-matched dogs, and 75% in healthy non-stone forming breeds. The presence of oxc genes of O. formigenes was significantly higher in healthy non-stone forming breed dogs than in the dogs with CaOx stones. Further, dogs with calcium oxalate stones and the stone-forming breed-matched controls showed comparable levels of biochemical oxalate degrading activity. We conclude that the absence of enteric colonization of O. formigenes is a risk factor for CaOx urolithiasis.     

The construction of an oxalate-degrading intestinal stem cell population in mice: a potential new treatment option for patients with calcium oxalate calculus

About 80% of all urological stones are calcium oxalate, mainly caused by idiopathic hyperoxaluria (IH). The increased absorption of oxalate from the intestine is the major factor underlying IH. The continuous self-renewal of the intestinal epithelium is due to the vigorous proliferation and differentiation of intestinal stem cells. If the intestinal stem cell population can acquire the ability to metabolize calcium oxalate by means of oxc and frc transgenes, this will prove a promising new therapy option for IH. In our research, the oxalate-degrading genes of Oxalobacter formigenes (Oxf)—the frc gene and oxc gene—were cloned and transfected into a cultured mouse-derived intestinal SC population to give the latter an oxalate-degrading function. Oxf was isolated and cultivated and the oxalate-degrading genes—frc and oxc—were cloned. The dicistronic eukaryotic expression vector pIRES-oxc-frc was constructed and transferred into the mouse stem cell population. After selection with G418, the expression of the genes was identified. The oxalate-degrading function of transfected cells was determined by transfection into the intestinal stem cell population of the mouse. The change in oxalate concentration was determined with an ion chromatograph. The recombinant plasmid containing oxc and frc genes was transfected into the stem cell population of the mouse and the expression of the genes found normal. The cell population had acquired an oxalate-degrading function. The oxc and frc genes could be transfected into the intestinal stem cell population of the mouse and the cells acquired an oxalate-degrading function.     

人胶质源性神经生长因子真核表达载体构建及在大鼠脊髓组织中的表达

目的探索人胶质源性神经生长因子（human glial derived neurotrophic factor,hGDNF）真核表达载体,体内直接转染SD大鼠脊髓组织治疗急性脊髓损伤（spinal cord injury,SCI）的可能性。方法基因重组和限制性内切酶酶切构建真核表达载体pcDNA3-hGDNF,经脂质体DOTAP介导质粒转染SD大鼠脊髓组织,作为实验组;对照组大鼠直接注射空载体脂质体混合物。14d后取材,RT-PCR及Western blot检测hGDNF mRNA及蛋白表达。结果重组真核表达载体pcDNA3-hGDNF经限制性内切酶Hind III和Xba-酶切后,电泳显示400bp hGDNF目的片段和5400bp pcDNA3载体片段。转染大鼠脊髓组织后14d,RT-PCR检测出目的基因mRNA,Western blot检测出hGDNF的蛋白表达。结论构建的真核表达载体pcDNA3-hGDNF能在转染的大鼠脊髓组织中表达,可为基因治疗修复急性SCI奠定基础。 14 胚胎干细胞移植修复脊髓损伤的实验研究 目的观察胚胎干细胞（embryonic stem cell,ES）诱导的神经前体细胞移植,对小鼠脊髓损伤神经功能恢复的影响。方法取由上海市发育生物学重点实验室提供的ES进行细胞培养和体外诱导,收集ES衍生细胞。并进行RT-PCR检测。将50只C57/BL6J小鼠制备为T9、10脊髓半横断模型,将存活的28只小鼠随机分为三组。假手术组（A组）：9只,未作任何处理;手术/细胞组（B组）：10只,于距损伤区域以远约1cm的椎管内注射2~3μl制备的ES衍生细胞,总细胞数为9×105个;手术/DMEM组（C组）：9只,按B组方法注射2~3μl DMEM。术后1、2、4、6和8周采用BBB后肢功能评分观察小鼠神经功能恢复情况,取损伤脊髓进行X-gal染色和免疫组织化学染色观察。结果ES经体外诱导培养,呈圆形或椭圆形小集落生长,有1个或多个核仁。RT-PCR检测,ES细胞诱导后表达巢蛋白及微管相关蛋白,但未表达胶质纤维酸性蛋白。小鼠实验,BBB后肢功能评分显示术后各时间点A组与B、C组比较,差异均有统计学意义（P〈0.01）。B组与C组比较,1、2和4周时,差异有统计学意义（P〈0.01）;6、8周时,组间差异无统计学意义（P〉0.05）。X-gal染色观察,B组呈阳性染色,A、C组均为阴性。免疫组织化学染色观察,B组在损伤脊髓部位,表达兔抗神经微丝蛋白,未表达胶质纤维酸性蛋白。结论将ES培养诱导分化为神经前体细胞移植后,能够存活、迁移,并分化为神经元,但未明显改善神经功能。