Identification of the genes associated with a virulent strain of Porphyromonas gingivalis using the subtractive hybridization technique

Background/aims:  Porphyromonas gingivalis , a major etiological organism implicated in periodontal disease, can be classified into virulent and avirulent strains. Our aim was to identify a gene for the virulence of P .  gingivalis .
Methods:  The subtractive hybridization technique was employed to identify the genes specific to P .  gingivalis W83, a virulent strain. In this study, P. gingivalis W83 was used as the tester strain, and P .  gingivalis ATCC 33277 was the driver strain. The prevalence of W83-specific genes was determined by Southern blot analysis of several P. gingivalis strains.
Results:  We obtained 575 colonies using the subtractive hybridization technique. From among these, 26 DNA fragments were subjected to a homology search using the BLAST program. Compared with strain ATCC 33277, strain W83 contained 12 unique clones. The specificities of the isolated DNA fragments were analyzed among four P. gingivalis strains by Southern blot analysis. Five genes showed specificity for strain W83 compared with strain ATCC 33277. All five genes were also identified in strain W50.
Conclusions:  The subtractive hybridization technique was effective in screening the two strains for specific DNA sequences, some of which might be responsible for determining virulence. The results suggested that several genes specific to strain W83 were associated with its virulence. Further analysis of these DNA fragments will provide important information on the pathogenesis of virulent P .  gingivalis strains.     

抑制性差减杂交技术分离白血病多药耐药基因

目的分离及鉴定与白血病多药耐药性相关的差异表达基因。方法采用抑制性差减杂交(SSH)技术分离非耐药细胞株K562与耐药细胞株K562/DOX差异表达基因。提取总RNA,逆转录合成cDNA,经限制性内切酶RsaⅠ酶切后,分别与不同的接头(adopter1和adopter2R)连接;连接产物插入pMD19-T载体后转入大肠埃希菌中,构建cDNA差减文库;挑取阳性克隆提取质粒进行测序及同源序列分析,确定差异表达基因。结果筛选获得220个差异表达基因,包括血红蛋白、核糖体和线粒体等相关基因,以及热休克因子结合蛋白(HSPB1)基因等其他基因。结论采用SSH技术及分子克隆技术可构建耐药及非耐药肿瘤细胞株差异表达基因的差减cDNA文库,能够为进一步筛选、克隆肿瘤细胞多药耐药性相关差异表达基因奠定基础。     

白血病原代骨髓基质细胞对柔红霉素作用下Jurkat细胞基因表达的影响

目的研究白血病患者骨髓基质细胞（BMSCs）抑制柔红霉素（DNR）诱导Jurkat细胞凋亡过程中Jurkat细胞相关基因表达的变化,并进一步分析差异表达基因在BMSCs对Jurkat细胞保护过程中的意义.方法采用Percoll体外分离初治急性白血病患者骨髓单个核细胞,贴壁培养BMSCs;采用抑制性消减杂交技术等分子生物学方法建立白血病BMSCs保护的Jurkat细胞差异表达基因的cDNA文库;并对差异表达的基因进行初步鉴定与分析.结果成功地建立了白血病BMSCs保护的Jurkat细胞上调和下调差异表达基因的cDNA文库;初步筛选克隆到30个上调差异表达基因和22个下调差异表达基因cDNA片段;其功能主要与细胞周期调控、细胞凋亡、细胞能量代谢相关.结论白血病患者BMSCs能诱导Jurkat细胞基因发生差异表达,为探讨白血病患者BMSCs保护白血病细胞逃避化疗药物杀伤的分子机制进行了前期研究.     

细胞因子IL-1β/ IFN-γ对骨骼肌成肌细胞基因表达的影响

目的研究细胞因子白细胞介素-1β(IL-1β)/干扰素-γ( IFN-γ)对鼠骨骼肌成肌细胞基因表达的影响.方法鼠骨骼肌成肌细胞在IL-1β/ IFN-γ混合液中孵育12 h,用抑制性削减杂交法克隆差异表达基因.随机挑取抑制性削减杂交所得克隆制备质粒,进行PCR扩增, 选取不同长度片断的产物,测序分析.结果发现1种骨骼肌结构蛋白基因(原肌球蛋白-4)表达下调,另发现2种凋亡相关的基因和2种功能不明基因的表达上调.结论①IL-1β/ IFN-γ下调骨骼肌结构蛋白基因,调节凋亡相关基因表达,推测可能是骨骼肌功能失调的原因之一;② 2种功能不明基因的表达为进一步研究骨骼肌功能失调的原因提供了新线索.     

ATP-Responsive Drug Delivery Systems

The combination of targeted drug delivery and controlled-release technology may pave the road for more effective yet safer chemotherapeutic options for cancer therapy. Drug-encapsulated polymeric nanoparticle–aptamer bioconjugates represent an emerging technology that can facilitate the delivery of chemotherapeutics to primary and metastatic tumours. Aptamers are short nucleic acid molecules with binding properties and biochemical characteristics that may make them suitable for use as targeting molecules. The goal of this review is to summarise the key components that are required for creating effective cancer targeting nanoparticle–aptamer bioconjugates. The field of controlled release and the structure and properties of aptamers, as well as the criteria for constructing effective conjugates, will be discussed.     

幽门螺杆菌ssDNA适配子的筛选及其应用

目的通过富集的配基系统进化技术(SELEX)筛选出与幽门螺杆菌(HP)菌体具有高亲和性适配子,并且利用其检测组织和活体内HP的感染。方法培养HP细菌,利用SELEX筛选获得HP菌体的适配子。在HP感染患者活检组织验证其结合。结果从第6轮筛选所得ssDNA中筛选出一条高结合力的适配子命名为HP1,将适配子HP1区别于其他筛选出的适配子,并检测其与幽门螺旋杆菌的亲和力。结论初步获得了针对HP菌体筛选出高亲和性适配子,为开发HP诊断试剂奠定了基础。     

结核分枝杆菌MPT64蛋白适配子的筛选与鉴定

目的 利用指数富集配体系统进化(SELEX)技术筛选能与结核分枝杆菌分泌蛋白MPT64特异性结合的寡核苷酸适配子,寻找早期诊断结核病的方法.方法 体外合成随机单链DNA(ssDNA)文库,以MPT64蛋白为靶物质,采取SELEX技术进行12轮筛选,将适配子库克隆、测序后,用DNAMAN软件对其结构进行分析,经生物素-链亲和素-辣根过氧化物酶显色系统测定亲和力,并利用捕获适配子与检测适配子组成的"三明治"夹心法对获得的适配子进行初步验证.将13个非结核分枝杆菌菌株和BCG菌株作为阴性组计为0,将结核分枝杆菌和牛结核分枝杆菌组作为阳性组计为1,采用MedCalc软件分析受试者操作特征曲线,确定最佳阳性判定值,并构建散点图.结果 经12轮筛选后,随机挑选15个适配子与MPT64蛋白的亲和性进行分析,吸光度值为0.492～1.243,73.3％的适配子的吸光度值在1.0以上;二级结构分析显示,适配子与MPT64蛋白亲和性的基础主要是大口袋茎环结构,口袋与环之间的茎桥含有不同数量的GC碱基对;"三明治"夹心法对阴性组[非结核分枝杆菌标准菌株及卡介苗(BCG)株]和阳性组(结核分枝杆菌实验室H37Rv株及临床株、牛结核分枝杆菌标准株)共47个菌株培养上清的检测结果显示,在临界(cut-off)值为0.61时,H37Rv、牛结核分枝杆菌组为阳性,BCG株为阴性;阴性组标本的阴性检出率为85.7％,阳性组标本的阳性检出率为87.9％,表现出一定的检测价值.结论 已初步筛选到与MPT64蛋白具有高亲和性的DNA适配子.     

Aptamers in Diagnostics and Treatment of Viral Infections

Aptamers are in vitro selected DNA or RNA molecules that are capable of binding a wide range of nucleic and non-nucleic acid molecules with high affinity and specificity. They have been conducted through the process known as SELEX (Systematic Evolution of Ligands by Exponential Enrichment). It serves to reach specificity and considerable affinity to target molecules, including those of viral origin, both proteins and nucleic acids. Properties of aptamers allow detecting virus infected cells or viruses themselves and make them competitive to monoclonal antibodies. Specific aptamers can be used to interfere in each stage of the viral replication cycle and also inhibit its penetration into cells. Many current studies have reported possible application of aptamers as a treatment or diagnostic tool in viral infections, e.g., HIV (Human Immunodeficiency Virus), HBV (Hepatitis B Virus), HCV (Hepatitis C Virus), SARS (Severe Acute Respiratory Syndrome), H5N1 avian influenza and recently spread Ebola. This review presents current developments of using aptamers in the diagnostics and treatment of viral diseases.