羊布鲁杆菌M5-90 BP26抗原单克隆抗体的制备及鉴定

目的 制备高亲和性的羊布鲁杆菌M5-90 BP26抗原单克隆抗体,并对抗体进行鉴定.方法 将质粒pET-28a-BP26转化感受态大肠埃希菌(E.coli)BL21 (DE3),构建原核表达质粒pET-28a-BP26,用镍离子金属螯合亲和层析法(Ni-NTA)纯化、重组BP26蛋白(rBP26).将纯化后的rBP26蛋白与弗氏完全佐剂等体积混合成乳化抗原,接每只100 μg/0.1 ml在BALB/c小鼠皮下多点注射进行初次免疫;2周后,按每只50μg/0.1ml 在小鼠皮下多点注射进行再次免疫.再次免疫后2周,小鼠尾静脉取血测效价,检测免疫效果;在细胞融合前3天,将乳化抗原按每只小鼠50μg腹腔注射加强免疫.将小鼠骨髓瘤SP2/0细胞与脾细胞按1∶5比例在聚乙二醇( PEG) 1450作用下进行细胞融合,置于37℃、5％CO2培养箱中培养;10 d后取细胞培养上清液,用间接酶联免疫吸附法(ELISA)测定,筛选分泌抗rBP26抗体的杂交瘤细胞;再经过反复3次克隆,筛选出单克隆全阳性的杂交瘤细胞建株,用杂交瘤细胞株制备BP26抗原单克隆抗体,并以初始杂交瘤细胞克隆导命名.利用羊布鲁杆菌M5 -90疫苗株制备膜蛋白提取物(NMP),采用免疫印迹法(Western)及斑点间接酶联免疫吸附法(Dot-ELISA)对筛选的单克隆抗体进行免疫学特性鉴定,用单克隆抗体亚型试剂盒进行抗体分型和Kappa (κ)和Lambda(λ)轻链鉴定.结果 成功地获得2株能稳定分泌抗rBP26抗原的高亲和性杂交瘤3C3和5A5单克隆抗体,并能与羊布鲁杆菌M5-90疫苗株上的NMP结合,构建成M5-90 BP26抗原单克隆抗体,抗体亚型分别为IgG1和IgG2b,轻链均为κ链.结论 鉴定结果表明,成功制备2株羊布鲁杆菌BP26抗原的高亲和性单克隆抗体,抗体具有识别M5-90疫苗株的膜蛋白构象表位的能力,优势表位的识别可为羊布鲁杆菌M5-90疫苗株的改造提供实验依据.     

非溶细胞性乙型肝炎病毒清除过程中细胞因子的作用

乙型肝炎病毒（HBV）入侵人体后通过诱导宿主免疫反应破坏肝细胞。各种临床类型的肝炎和机体所处的免疫状态有关。近年研究表明,机体感染HBV后,清除病毒的机制主要是溶细胞机制,主要通过CD8＋细胞毒性T淋巴细胞（CTL）的细胞毒效应清除病毒;非溶细胞性机制,主要由T细胞、自然杀伤（NK）细胞、巨噬细胞、树突状细胞等分泌各种细胞因子介导。HBV感染时,从胞质中清除HBV复制中间体及从细胞核中清除共价闭合环状DNA（cccDNA）主要通过非溶细胞性抗病毒机制,其本质是通过多种细胞因子介导清除细胞中的HBV。     

婴儿高胰岛素性低血糖症病因学研究进展

婴儿高胰岛素性低血糖症 (PHHI)是一种具有遗传异质性和临床表现异质性的综合征。对其病因学研究的深入促进了人们对胰岛素分泌和葡萄糖代谢调控机制的了解。具常染色体隐性遗传模式的PHHI患者 ,由于编码胰岛 β细胞KATP通道SUR1 或Kir6 .2蛋白的基因突变 ,使其KATP通道功能丧失 ,造成PHHI。常染色体显性遗传模式患者的病因尚不清 ,仅在一个家系发现了葡萄糖激酶基因的突变。而合并有高氨血症的PHHI,则多是因谷氨酸脱氢酶的功能突变所致。     

PTD-HBcAg融合蛋白诱导特异性CTL在HepG2.2.15细胞抑制HBV复制的研究

目的探讨PTD-HBcAg融合蛋白诱导小鼠体内特异性CTL并抑制HepG2.2.15细胞HBV复制的作用。方法 PTD-HBcAg、HBcAg和阴性对照分别与等体积的弗氏佐剂乳化后皮下免疫小鼠;第14d,分离脾淋巴细胞并分别用PTD-HBcAg、HBcAg、PTD和PBS加强刺激后收集上清,检测细胞因子IFN-γ、IL-12、IL-4和IL-10;刺激后的淋巴细胞作为效应细胞与HepG2.2.15细胞共培养,检测,效应细胞对HBsAg、HBVDNA的抑制作用及对HepG2.2.15细胞、HepG2细胞的杀伤效果。结果 PTD-HBcAg组分泌的IFN-γ、IL-12、IL-4和IL-10与HBcAg组和阴性对照组比较差异有统计学意义(P0.05);PTD-HBcAg融合蛋白组较HBcAg组和阴性对照组有更明显的病毒抑制作用(P0.05);PTD-HBcAg组对HepG2.2.15细胞的杀伤率明显高于HBcAg组和阴性对照组(P0.05)。结论 PTD-HBcAg可诱导HBV特异性CTL,能有效抑制HepG2.2.15细胞HBV的复制。     

SH-SY5Y细胞α7尼古丁受体基因抑制对APP代谢的影响

目的采用RNA干扰技术抑制神经母细胞瘤细胞(SH-SY5Y细胞)中α7神经型尼古丁乙酰胆碱受体(nAChR)基因表达,了解对β淀粉样前体蛋白(APP)代谢中的γ-分泌酶两个重要组分早老蛋白(PS)及单过性跨膜蛋白(NCT)水平的影响。方法 SH-SY5Y细胞转染针对α7nAChR的小干扰RNA(siRNA),用实时PCR法和Western印迹法分别测定细胞中α7 nAChR、PS及NCT在mRNA和蛋白表达水平的变化。结果转染α7 nAChR siRNA后,与对照组相比,α7 nAChR mRNA及蛋白表达水平明显降低;PS蛋白mRNA及蛋白水平均升高,而NCT水平无明显变化。结论α7 nAChR基因表达抑制后γ-分泌酶组分之一PS的水平明显升高,这种改变可能与α7 nAChR基因表达抑制后β-淀粉样蛋白(Aβ)的产生增多有关,可能与阿尔茨海默氏病(AD)的发病有一定的关系。     

汉坦病毒Hunan03株S基因克隆、表达及核蛋白免疫原性分析

目的构建汉坦病毒Hunan03株核蛋白基因原核重组表达载体,在大肠杆菌中进行核蛋白表达,研究核蛋白的免疫性及免疫反应性。方法设计特异性扩增汉坦病毒Hunan03株S基因完整开放阅读框(ORF)的引物,RT-PCR扩增,产物克隆到pGM-T载体,转化感受态细胞TOP10,应用蓝白斑筛选、酶切、PCR鉴定,定向克隆到pGEX-6p-2原核表达载体,转化Ecoli.BL21 Star^TM(DE3),IPTG诱导表达,SDS-PAGE、Western blot对重组蛋白进行鉴定。应用Glutathione Sepharose 4B纯化柱纯化重组蛋白,免疫新西兰兔,建立间接ELISA法对核蛋白的免疫原性与免疫反应性进行评价。结果PCR扩增S基因ORF区域产物大小约1 306 bp,重组载体pGEX-6p-2-S经双酶切、PCR、测序鉴定提示构建成功;在37 ℃,IPTG浓度为0.8 mmol/L诱导5 h的条件下,表达出最高量的相对分子量约74 kDa的GST-NP融合蛋白。建立的间接ELISA法检测GST-NP融合蛋白免疫后的新西兰兔血清,IgM抗体滴度达1∶8 000,IgG抗体滴度达1∶16 000。结论成功构建了高效表达的汉坦病毒S基因重组表达载体,获得了纯度较高具有较好的免疫原性与免疫反应性的核蛋白,为后续汉坦病毒单克隆抗体的制备奠定了基础。     

羊布鲁杆菌脂蛋白OMP19单克隆抗体制备与鉴定

目的 制备与鉴定羊布鲁杆菌脂蛋白OMP19单克隆抗体,用于布菌感染免疫机制研究。方法 将OMP19基因连接入pET-30a(+)表达载体中,构建pET-30a(+)/OMP19质粒,转化入大肠埃希氏菌BL21(E3),以不同浓度异丙基-β-D硫代半乳糖苷(IPTG)进行诱导表达,采用镍金属螯合亲和层析(NI-NTA)纯化;以布菌阳性血清检测重组蛋白免疫反应性,并利用杂交瘤技术制备单克隆抗体,以天然OMP19蛋白及布菌外膜蛋白提取物(NMP)对制备的单克隆抗体进行Western Blot及酶免疫染色试验(IEST)鉴定。结果 表达了OMP19蛋白,分子量约19 kDa,通过纯化纯度可达95%,Western Blot分析显示蛋白具有良好的抗原性,并制备了OMP19抗原23株鼠源性单克隆抗体,鉴定结果 显示22(95.65%)株能与天然OMP19蛋白反应,18(78.26%)株能与NMP反应,其中IgG1(k)亚型占91.30%;4株能与羊种布鲁氏菌菌涂片反应。结论 成功制备具有良好抗原性的重组OMP19蛋白,筛选出识别天然蛋白的单克隆抗体,已初步应用于布菌的检测,为OMP19抗原B细胞表位的筛选奠定基础。     

日本血吸虫虫源性抗原诱导效应性B细胞分化的研究

目的 目的 观察日本血吸虫可溶性虫卵抗原 （SEA） 和可溶性成虫抗原 （SWAP） 诱导小鼠效应性B细胞分化情况。方 方 法 法 SEA、 SWAP和脂多糖 （LPS） 分别体外刺激小鼠脾脏单个核细胞和脾脏CD19+ B细胞, 72 h后采用流式细胞术检测 CD19+ IL?6+ 及CD19+ IFN?γ+ 细胞比例; 用酶联免疫吸附试验 （ELISA） 检测抗原刺激后脾脏B细胞培养上清中IL?6和IFN?γ 水平。用SEA、 SWAP、 PBS分别和不完全弗氏佐剂混合免疫小鼠, 每周1次, 共3次, 末次免疫后7 d取小鼠脾脏, 流式细胞 术检测CD19+ IL?6+ 及CD19+ IFN?γ+ 细胞比例, 用ELISA法检测培养上清中IL?6和IFN?γ水平。 结果 结果 SEA与LPS可以体 外诱导脾脏单个核细胞和脾脏B细胞分化为CD19+ IL?6+ B细胞 （F = 5.099, P < 0.05; F = 6.951, P < 0.05）, 并刺激脾脏B细 胞分泌IL?6 （F = 55.184, P < 0.01）; SEA免疫小鼠后, 可以在体内刺激小鼠脾脏B细胞分泌IL?6 （F = 19.244, P < 0.01）, 并诱 导小鼠脾脏单个核细胞分化为CD19+ IL?6+ B细胞 （F = 14.904, P < 0.05）。SWAP可以体外诱导脾脏单个核细胞分化为 CD19+ IFN?γ+ B细胞 （F = 3.277, P < 0.05）, 但不能单独诱导脾脏B细胞分化为IFN?γ+ B细胞, 也不能刺激脾脏B细胞分泌 IFN?γ; SWAP免疫小鼠后, 可以在体内刺激小鼠脾脏B细胞分泌IFN?γ （F = 31.886, P < 0.01）, 并诱导其分化为CD19+ IFN? γ+ B细胞 （F = 49.873, P < 0.01）。 结论 结论 日本血吸虫SEA可以优势诱导小鼠脾脏单个核细胞分化为CD19+ IL?6+ B细胞, 而 SWAP可以优势诱导小鼠脾脏单个核细胞分化为CD19+ IFN?γ+ B细胞, 但依赖于其他免疫细胞的参与。     

寻常性痤疮皮损患者感染病原菌特征、炎症因子和免疫水平及相关因素分析北大核心CSCD

目的探讨发生皮损的寻常性痤疮患者感染病原菌特征、炎症因子和免疫水平,以及影响病情严重程度的相关因素。方法选择2019年10月-2020年8月本院收治的寻常性痤疮患者281例,参照痤疮综合分级系统分为轻度组(1~18分,52例)、中度组(19~30分,103例)、重度组(31~38分,74例)和超重度组(>39分,52例)。采集患者皮损处标本,厌氧罐法进行病原菌的培养及鉴定;采集患者静脉血,ELISA法检测血清炎症因子水平,采用流式细胞仪检测T细胞亚群水平;收集患者临床资料,通过单因素和多因素Logistic回归分析确定寻常性痤疮严重程度影响因素。结果281例寻常性痤疮患者的皮损标本分离出216株厌氧菌,以痤疮丙酸杆菌(71.31%)、表皮葡萄球菌(18.53%)、颗粒丙酸杆菌(4.63%)和贪婪丙酸杆菌(1.85%)为主。4组患者间血清降钙素原、高敏C反应蛋白、白细胞介素-12、肿瘤坏死因子-(水平,以及CD3^(+)、CD4^(+)和CD8^(+)百分率差异均有统计学意义(均P<0.05)。其中超重度组降钙素原、高敏C反应蛋白、白细胞介素-12、肿瘤坏死因子-(水平和CD8^(+)百分率均显著高于其他三组(均P<0.05),CD3^(+)、CD4^(+)百分率显著低于其他三组(均P<0.05);重度组血清降钙素原、高敏C反应蛋白、白细胞介素-12、肿瘤坏死因子-(水平和CD8^(+)百分率显著高于中度组和轻度组(均P<0.05),CD3^(+)、CD4^(+)百分率显著低于中度组和轻度组(均P<0.05);中度组血清降钙素原、高敏C反应蛋白、白细胞介素-12、肿瘤坏死因子-(水平和CD8^(+)百分率显著高于对照组(均P<0.05),CD3^(+)、CD4^(+)百分率显著低于对照组(均P<0.05)。经单因素分析,寻常性痤疮病情严重程度与性别、初发年龄、每日洗脸次数、每日睡眠时间、皮肤类型、便秘、家族遗传史及季节等存在一定关系(均P<0.05);多因素Logistic回归分析显示,男性(OR=2.190,95%CI:2.179~3.319)、初发年龄(≤15岁)(OR=2.246,95%CI:1.169~4.313)、喜食咸味(OR=1.655,95%CI:1.143~2.398)和油性皮肤(OR=1.835,95%CI:1.502~2.241)等均是寻常性痤疮严重程度的独立影响因素(均P<0.05)。结论寻常性痤疮皮损处感染病原菌以痤疮丙酸杆菌、表皮葡萄球菌和颗粒丙酸杆菌等厌氧菌为主,炎症因子和免疫功能与寻常性痤疮病情严重程度相关,且性别、初发年龄、饮食习惯和皮肤类型等是病情严重程度的独立影响因素,可为寻常性痤疮的防治提供参考依据。     

Ⅱ型登革病毒E基因的克隆及其酵母表达

目的　克隆 2型登革病毒E基因并用酵母真核表达 ,获得全长的重组E蛋白 ,为其结构与功能的研究提供条件。方法　从感染DEN2 (NGC株 )后病变的C6 /36细胞上清中提取RNA ,通过RT -PCR扩增E基因片段 ,与载体pPICZαB连接筛选得到重组质粒 ,电穿孔法将重组体整合入酵母菌P pastoris,经抗生素Zeocin筛选产生的转化子进行表型鉴定 ,取Mut+菌诱导表达 ,SDS -PAGE、免疫印迹检测表达产物。结果　RT -PCR得到 1 5kb的E基因片段 ,酶切鉴定与测序显示重组质粒含DEN2全长E基因 ;Mut+ 酵母转化菌可分泌表达约 6 9kDa的蛋白 ,与DEN2E单抗的免疫印迹证实它为型特异的重组E蛋白。结论　成功将克隆的全长DEN2E基因在酵母菌中表达 ,获得的重组E蛋白具有免疫反应性。     

牛种布鲁氏菌2308强毒株dsbG基因缺失突变株的构建与初步评价

目的 研究dsbG基因对布鲁氏菌2308毒力的影响。方法 以布鲁氏菌2308亲本株为模板,通过同源重组和抗性替代的方法,构建布鲁氏菌dsbG基因缺失株(2308ΔdsbG)。将毒力株2308、疫苗株RB51、2308ΔdsbG缺失株在相同起始浓度下恒温振荡培养,观察其生长变化趋势;将各菌株按200:1的感染复数侵染人胚胎滋养层细胞(HPT-8),比较其在胞内的生存能力和粘附侵袭力。结果 成功构建并获得了布鲁氏菌dsbG缺失株,且10代内未发现回复现象,遗传性较稳定。2308ΔdsbG缺失株与2308亲本株相比在体外具有相似的生长趋势,但其对宿主细胞的粘附侵袭和胞内的繁殖能力显著低于亲本株。结论 dsbG基因在布鲁氏菌的致病能力中发挥重要作用,dsbG基因的缺失显著降低了牛种布鲁氏菌2308的粘附侵袭和胞内生存能力。     

布鲁氏菌IV型分泌系统效应蛋白BPE043的功能和致病机制研究

目的 研究布鲁氏菌IV型分泌系统效应蛋白BPE043在布鲁氏菌感染和胞内生存过程中的作用。方法 以羊种布鲁氏菌104株为起始菌株,通过同源重组的方法构建布鲁氏菌BPE043基因缺失株。将布鲁氏菌野生株104和突变株104ΔBPE043在相同的起始浓度下培养,观察它们生长变化的趋势;用野生株和突变株分别感染小鼠,构建小鼠体内感染模型,测定小鼠脾重并计算脾脏细菌载量;利用免疫共沉淀技术筛选BPE043蛋白的宿主互作蛋白。结果 成功构建了布鲁氏菌BPE043基因缺失株。与野生株相比,突变株104ΔBPE043在体外培养的生长趋势和野生株基本相同;小鼠感染实验显示,在感染1周后,两组小鼠脾均肿大,但突变株104ΔBPE043感染组小鼠脾重低于野生株104感染组小鼠脾重;在感染后两周,两组小鼠脾肿大现象开始减轻。在细菌载量方面,在感染1周后,突变株104ΔBPE043感染小鼠的脾脏细菌载量低于野生株104感染小鼠;在感染后2周,突变株感染组的脾细菌载量下降趋势更明显。免疫共沉淀实验显示BPE043蛋白与鼠源小分子GTP结合蛋白Rab4和Rab11存在相互作用。结论 布鲁氏菌IV型分泌系统效应蛋白BPE043是布鲁氏菌重要的毒力因子。本研究为进一步探索BPE043基因在布鲁氏菌感染和胞内生存中的作用奠定了基础。     

Structural basis for alginate secretion across the bacterial outer membrane

Pseudomonas aeruginosa is the predominant pathogen associated with chronic lung infection among cystic fibrosis patients. During colonization of the lung, P. aeruginosa converts to a mucoid phenotype characterized by the overproduction of the exopolysaccharide alginate. Secretion of newly synthesized alginate across the outer membrane is believed to occur through the outer membrane protein AlgE. Here we report the 2.3 Å crystal structure of AlgE, which reveals a monomeric 18-stranded β-barrel characterized by a highly electropositive pore constriction formed by an arginine-rich conduit that likely acts as a selectivity filter for the negatively charged alginate polymer. Interestingly, the pore constriction is occluded on either side by extracellular loop L2 and an unusually long periplasmic loop, T8. In halide efflux assays, deletion of loop T8 (ΔT8-AlgE) resulted in a threefold increase in anion flux compared to the wild-type or ΔL2-AlgE supporting the idea that AlgE forms a transport pathway through the membrane and suggesting that transport is regulated by T8. This model is further supported by in vivo experiments showing that complementation of an algE deletion mutant with ΔT8-AlgE impairs alginate production. Taken together, these studies support a mechanism for exopolysaccharide export across the outer membrane that is distinct from the Wza-mediated translocation observed in canonical capsular polysaccharide export systems.     

Inflammation in cystic fibrosis airways: relationship to increased bacterial adherence.

It is unclear whether inflammation in the cystic fibrosis (CF) lung relates predominantly to bacterial infection, or occurs as a direct consequence of mutant cystic fibrosis transmembrane conductance regulator (CFTR) protein. Interleukin (IL)-8 secretion from CF and non-CF cell lines, and from CF and non-CF human primary nasal epithelial cells incubated with or without Pseudomonas aeruginosa, was measured. Activation of nuclear factor-kappaB (NF-kappaB) in unstimulated CF and non-CF nasal epithelial cells, cell lines and murine tissues was measured by gel-shift assays. No significant difference in basal IL-8 production or NF-kappaB activation was observed between CF and non-CF primary nasal cells. However, CF cells exhibited a significantly (p<0.01) increased IL-8 secretion following P. aeruginosa stimulation. Equalization of the increased P. aeruginosa adherence observed in CF cells, to non-CF levels, resulted in comparable IL-8 secretion. Further, IL-8 production did not differ with mutations which result in either correctly localized CFTR, or in partial/total mislocalization of this protein. Similar levels of NF-kappaB activation were observed in a number of organs of wildtype and CF mice. Finally, IL-8 secretion and NF-kappaB activity were not consistently increased in CF cell lines. Cos-7 cell transfection with plasmids expressing deltaF508 or G551D mutant CFTR protein resulted in increased activation of a p50-containing NF-kappaB complex, but IL-8 secretion was similar to wild-type cells. The authors conclude that the stimulus produced by Pseudomonas aeruginosa is the predominant inflammatory trigger in their models.     

肠炎沙门菌rfbG基因缺失株的构建及其生物学特性研究

目的 探究rfbG基因对肠炎沙门菌毒力的影响,评价肠炎沙门菌缺失rfbG基因后作为减毒活疫苗的潜力。方法 利用自杀质粒介导的同源重组技术,无痕构建肠炎沙门菌Z11ΔrfbG缺失株,并对其生物学特性进行分析。结果 成功构建肠炎沙门菌Z11ΔrfbG缺失株,与野生株相比,缺失株Z11ΔrfbG生化特性没有发生变化,在LB液体培养基中生长速率较慢;缺失株生物被膜形成能力显著弱于野生株,其感染J774A.1细胞后,产生的细胞毒性亦显著低于野生株。此外,缺失株可与吖啶橙溶液发生凝集,但与O₉血清不发生凝集。结论 rfbG基因缺失显著降低了肠炎沙门菌Z11的毒力,且缺失株符合粗糙型菌株的特点,Z11ΔrfbG不仅具有作为沙门菌减毒活疫苗或载体的潜质,也具有作为DIVA疫苗的潜力,为肠炎沙门菌减毒活疫苗的开发研究奠定了基础。     

A system for functional analysis of Ebola virus glycoprotein

Ebola virus causes hemorrhagic fever in humans and nonhuman primates, resulting in mortality rates of up to 90%. Studies of this virus have been hampered by its extraordinary pathogenicity, which requires biosafety level 4 containment. To circumvent this problem, we developed a novel complementation system for functional analysis of Ebola virus glycoproteins. It relies on a recombinant vesicular stomatitis virus (VSV) that contains the green fluorescent protein gene instead of the receptor-binding G protein gene (VSVΔG*). Herein we show that Ebola Reston virus glycoprotein (ResGP) is efficiently incorporated into VSV particles. This recombinant VSV with integrated ResGP (VSVΔG*-ResGP) infected primate cells more efficiently than any of the other mammalian or avian cells examined, in a manner consistent with the host range tropism of Ebola virus, whereas VSVΔG* complemented with VSV G protein (VSVΔG*-G) efficiently infected the majority of the cells tested. We also tested the utility of this system for investigating the cellular receptors for Ebola virus. Chemical modification of cells to alter their surface proteins markedly reduced their susceptibility to VSVΔG*-ResGP but not to VSVΔG*-G. These findings suggest that cell surface glycoproteins with N-linked oligosaccharide chains contribute to the entry of Ebola viruses, presumably acting as a specific receptor and/or cofactor for virus entry. Thus, our VSV system should be useful for investigating the functions of glycoproteins from highly pathogenic viruses or those incapable of being cultured in vitro.     

Hsp 70/Hsp 90 organizing protein as a nitrosylation target in cystic fibrosis therapy

The endogenous signaling molecule S-nitrosoglutathione (GSNO) and other S-nitrosylating agents can cause full maturation of the abnormal gene product ΔF508 cystic fibrosis (CF) transmembrane conductance regulator (CFTR). However, the molecular mechanism of action is not known. Here we show that Hsp70/Hsp90 organizing protein (Hop) is a critical target of GSNO, and its S-nitrosylation results in ΔF508 CFTR maturation and cell surface expression. S-nitrosylation by GSNO inhibited the association of Hop with CFTR in the endoplasmic reticulum. This effect was necessary and sufficient to mediate GSNO-induced cell-surface expression of ΔF508 CFTR. Hop knockdown using siRNA recapitulated the effect of GSNO on ΔF508 CFTR maturation and expression. Moreover, GSNO acted additively with decreased temperature, which promoted mutant CFTR maturation through a Hop-independent mechanism. We conclude that GSNO corrects ΔF508 CFTR trafficking by inhibiting Hop expression, and that combination therapies—using differing mechanisms of action—may have additive benefits in treating CF.     

Host-derived glucose and its transporter in the obligate intracellular pathogen Toxoplasma gondii are dispensable by glutaminolysis

Toxoplasma gondii, as an obligate intracellular and promiscuous pathogen of mammalian cells, utilizes host sugars for energy and to generate glycoconjugates that are important to its survival and virulence. Here, we report that T. gondii glucose transporter (TgGT1) is proficient in transporting mannose, galactose, and fructose besides glucose, and serves as a major hexose transporter at its plasma membrane. Toxoplasma harbors 3 additional putative sugar transporters (TgST1–3), of which TgST2 is expressed at its surface, whereas TgST1 and TgST3 are intracellular. Surprisingly, TgGT1 and TgST2 are nonessential to the parasite as their ablations inflict only a 30% or no defect in its intracellular growth, respectively. Indeed, Toxoplasma can also tolerate the deletion of both genes while incurring no further growth phenotype. Unlike Δtgst2, the modest impairment in Δtggt1 and Δtggt1/Δtgst2 mutants is because of a minor delay in their intracellular replication, which is a direct consequence of the abolished import of glucose. The Δtggt1 displays an attenuated motility in defined minimal media that is rescued by glutamine. TgGT1-complemented parasites show an entirely restored growth, motility, and sugar import. The lack of exogenous glucose in Δtggt1 culture fails to accentuate its intrinsic growth defect and prompts it to procure glutamine to sustain its metabolism. Unexpectedly, in vivo virulence of Δtggt1 in mice remains unaffected. Taken together, our data demonstrate that glucose is nonessential for T. gondii tachyzoites, underscore glutamine is a complement substrate, and provide a basis for understanding the adaptation of T. gondii to diverse host cells.     

Rescue of a paralyzed-flagella mutant of Chlamydomonas by transformation.

The biflagellate alga Chlamydomonas has been used extensively in the genetic and biochemical analysis of flagellar assembly and motility. We have restored motility to a paralyzed-flagella mutant of Chlamydomonas by transforming with the corresponding wild-type gene. A nitrate reductase-deficient paralyzed-flagella strain, nit1-305 pf-14, carrying mutations in the genes for nitrate reductase and radial spoke protein 3, was transformed with wild-type copies of both genes. Two-thirds of the cells that survived nitrate selection also regained motility, indicating that they had been transformed with both the nitrate reductase and radial spoke protein 3 genes. Transformants typically contained multiple copies of both genes, genetically linked to each other, but not linked to the original mutant loci. Complementation of paralyzed-flagella mutants by transformation is a powerful tool for investigating flagellar assembly and function.