Mechanisms of Salmonella entry into host cells

Salmonella enterica is an enteric bacterial pathogen that causes a variety of food and water-borne diseases ranging from gastroenteritis to typhoid fever. Ingested bacteria colonize the intestinal epithelium by triggering their own phagocytosis, using a sophisticated array of effector proteins that are injected into the host cell cytoplasm through a type III secretion apparatus. The synergistic action of these secreted effectors leads to a dramatic reorganization of the host actin cytoskeleton, resulting in vigorous membrane protrusion and the engulfment of attached bacteria. Analysis of these effector proteins and identification of their cellular targets has provided insight into the molecular mechanisms by which bacteria can subvert the host signalling and cytoskeletal machinery for their own purposes. This review is intended to summarize our current understanding of the tools used by Salmonella to enter host cells, with a focus on effectors that modulate the actin cytoskeleton.     

驴源兽疫链球菌的分离鉴定及多位点序列分型分析

【目的】本研究采集了新疆地区驴腺疫病料,从样品中分离鉴定可疑病原菌并对其进行基因水平的分型与进化分析。【方法】对采集的新疆地区某驴场驴腺疫病驴颌下淋巴结拭子进行细菌分离培养,对2个分离株(HT111、HT321)进行染色、培养、生化试验、药敏试验,对其16S rRNA及SeM基因进行测序和进化分析,并通过PCR扩增7个管家基因,利用多位点序列分型(MLST)方法鉴定其分子分型。【结果】2个分离株均属马链球菌兽疫亚种,其中HT111对测试的13种抗生素中的3种(青霉素、克拉霉素和四环素)耐药,HT321对8种抗生素(阿莫西林、头孢呋辛、头孢噻呋、青霉素、克拉霉素、克林霉素、土霉素和四环素)耐药。序列分型发现了一种新的ST型为ST420 (HT321),分离株HT111为ST179型。【结论】本研究在新疆地区首次分离了驴源马链球菌兽疫亚种,并鉴定出一个新的ST型(ST420),为驴腺疫的流行病学提供了参考数据。     

Alteration of tubuliform silk gland cytoarchitecture with the reproductive cycle of the Western black widow spider,Latrodectus hesperus

The protein synthetic and secretory activity of spider tubuliform glands is known to be coordinated with the reproductive stage of the spider. For spiders that produce multiple egg cases, such as the black widow Latrodectus hesperus, this means that the cells that make up the tubuliform gland cycle from minimal to maximal silk protein synthesis and exocytosis as the spider transitions from early vitellogenesis to a gravid state and back. The impact of these transitions on the cells that form the tubuliform gland has yet to be characterized. The entire tubuliform gland undergoes an elastic deformation, doubling in size in response to the accumulation and depletion of egg case silk proteins within its lumen. Similarly, the diversity and organization of organelles within the cytoplasm of the secretory epithelial cells that make up the wall of the tubuliform gland change with the reproductive stage of the spider. Progression of a spider from early to late vitellogenesis is accompanied by decondensed nucleoli and distention of the rough endoplasmic reticulum, markers of protein synthetic activity. The presumed silk proteins that fill the lumen of the tubuliform gland of a gravid spider include a fibrous matrix with homogeneous spherical inclusions. These components are also present within the cytoplasm of the cell; however, only the fibrous material appears to be enclosed by membranous organelles. Transition of the tubuliform gland from peak silk synthesis back to a quiescent state is marked by the appearance of multivesicular bodies and organelles resembling phagophores and autophagosomes, suggestive of a role for autophagy in the process of recovery. The reproducible cellular dynamics of the tubuliform silk gland of the black widow spider makes it a potential model system for study of the regulation of silk gene expression, endomembrane transport, and exocytosis of silk proteins and autophagy.     

酵母细胞自然衰老分子作用机理的研究进展

衰老是任何生物都无法避免的生理现象,它由多种因素引起,其过程极其复杂.酵母细胞是目前衰老研究领域公认的模式生物,一系列影响衰老的分子作用机理及调控因素的发现均源自于对酵母细胞的研究.自然衰老是酵母细胞的衰老模式之一,由于该衰老过程与其他高等真核细胞(特别是哺乳动物细胞)极为相似,近年来受到广泛关注.全面比较酵母细胞衰老的两种模式,详细介绍自然衰老过程中分子作用机理的研究进展,重点阐述其复杂的自然寿命调控通路,包括卡路里限制以及药物添加对Ras/PKA、Sch9、Tor等营养依赖型调控通路的影响,并展望未来该领域需要解决的重要科学问题,为全面深入了解高等生物,特别是人类自身的衰老机理提供参考.     

中国新疆维吾尔自治区不明原因发热人群中Tahyna病毒感染状况调查

本研究通过对新疆地区不明原因发热人群血清Tahyna病毒抗体进行检测,以了解Tahyna病毒在当地的感染状况及分布特征。通过间接免疫荧光方法对新疆维吾尔自治区南部喀什地区、北部伊犁地区742例不明原因发热患者急性期血清标本进行Tahyna病毒抗体检测,并对IgM抗体阳性标本平行进行Tahyna病毒、Snowshoe hare病毒和Inkoo病毒三种抗原性相似的布尼亚病毒的蚀斑减少中和试验。研究结果显示新疆南部喀什地区采集不明原因发热患者急性期血清中,IgM抗体阳性率5.3%,IgG抗体阳性率18.3%;新疆北部伊犁地区采集的急性期患者血清标本中并未发现TAHV IgM抗体阳性;蚀斑减少中和试验结果显示,TAHV IgM抗体阳性患者血清中Tahyna病毒中和抗体滴度较其它两种布尼亚病毒中和抗体滴度升高明显。本研究证实新疆南部地区不明原因发热人群存在Tahyna病毒的急性感染和既往感染,为相关疾病的进一步监测提供基础。     

miR-125b在前列腺癌1E8细胞运动转移中的作用及其分子机制的初步探讨

目的 研究 miR-125b在前列腺癌高低转移潜能细胞中的表达差异及其对高转移细胞株1E8细胞的运动转移中的作用和可能的分子机制.方法 realtime PCR法检测前列腺癌高低转移潜能配对细胞系中 miR-125b的表达差异.通过划痕实验及transwell实验观察1E8细胞及转染 miR-125b 抑制剂及其阴性对照后该细胞运动转移能力的变化.结果 realtime PCR结果显示高转移潜能1E8细胞中miR-125b表达水明显高于低转移潜能2B4细胞;下调miR-125b会减弱1E8细胞的运动转移能力.结论 miR-125b可促进前列腺癌细胞的运动转移能力.     

糖蜜草挥发性成分HS-SPME-GC-MS分析

本文首次采用顶空固相微萃取技术(HS-SPME)提取该植物挥发性成分,然后通过气质联用技术(GC-MS)结合保留指数以及标样对照对化学成分进行了定性,并通过峰面积归一化法计算出各组分的相对百分含量。试验确定了PDMS/DVB固相微萃取对糖蜜草挥发物的萃取效果最好,并从中鉴定出33种化合物占总挥发性成分的90.94%,主要为烷烃和萜烯类化合物。该研究为开发糖蜜草作为水稻螟虫的驱避植物进行害虫安全有效防治提供理论依据,并为驱避性挥发物的田间应用奠定基础。     

心脏特异表达Calponin 1转基因小鼠的心脏功能分析

目的建立心脏特异表达Calponin 1转基因小鼠,研究Calponin 1对心脏发育及心肌病的调节作用。方法利用心脏特异启动子α-MHC构建转基因表达载体,显微注射法建立Calponin 1转基因小鼠,PCR法鉴定转基因小鼠的基因型,Western Blot检测Calponin 1在心脏组织中的表达,心脏超声检测转基因小鼠的心脏结构和功能,HE染色和Masson染色检测转基因小鼠心脏的病理改变。结果 Calponin 1在野生型小鼠心脏中有表达,在扩张型心肌病小鼠的心脏组织表达降低。通过显微注射法,建立了2个心脏组织Calponin 1基因高表达的转基因小鼠系。与野生型小鼠相比,Calponin 1转基因小鼠收缩期左室内径（LVID,systolic）增加28%（P〈0.01,n=12）,舒张期左室内径（LVID,diastolic）增加16.2%（P〈0.01,n=12）,收缩期左室后壁厚度（LVPW,systolic）减小15.7%（P〈0.01,n=12）,舒张期左室后壁厚度（LVPW,diastolic）减小21%（P〈0.01,n=12）,射血分数（ejection fraction,EF）降低11.5%（P〈0.01,n=12）,短轴内径缩短率（fraction shortening,FS）降低14.6%（P〈0.05,n=12）。转基因小鼠心脏组织病理H＆E染色和Masson染色显示,转基因小鼠心室扩张,心肌细胞不均匀肥大,细胞间隙变大,心肌间质纤维增多。结论 Calponin 1在心脏特异过表达引起转基因小鼠心脏左室内径增加,收缩期容积和舒张期容积显著增大,心室壁变薄,射血分数及短轴缩短率降低等扩张性心肌病表型,推测Calponin 1是参与心肌病病理发生的基因之一。