Environmental control of the survival and differentiation of dentate granule neurons

Dentate granule cells (DGCs) and their microcircuits have been implicated in hippocampus-dependent memory encoding and epileptogenesis. Little is known about how the proper maturation of DGCs is determined by their intrinsic programs or external factors during development. In order to explore this, we dispersed premature DGCs on living hippocampal slices. Here we report that the survival and network formation of DGCs are supported by local cues present in the dentate gyrus ex vivo. The density of surviving DGCs was almost uniform throughout the host slices 12 h after implantation but gradually became heterogenous across substrata, with the cells engrafted onto the stratum granulosum scoring the highest rate of survival. The mossy fiber axons arising from DGCs growing on this substratum were properly guided towards CA3, whereas other misplaced DGCs exhibited heterotopic axon projection. In particular, about half of the axons originating from the hilus were misguided into the molecular layer, which resembles the supragranular mossy fiber sprouting seen in epileptic disorders. These results suggest that local environmental factors influence the cell adhesion, neurite polarization and axon guidance of DGCs.     

Epstein-Barr病毒RPMS1基因在鼻咽癌组织中的表达及其细胞内定位

目的:了解RPMS1基因在鼻咽癌组织中的表达特点,并明确该基因在上皮细胞中表达的亚细胞区域,为进一步研究其生物学功能提供依据. 方法:提取鼻咽癌组织及各细胞系的DNA和总RNA,以巢式PCR扩增W片段来检测Epstein-Barr病毒(EB病毒)的感染情况,RT-PCR检测RPMS1基因在鼻咽癌组织、细胞株中的表达,并克隆入pEGFP-C2真核表达载体,通过脂质体转染技术将其介导入人胚肾上皮(HEK293)细胞,以激光共聚焦显微镜观察其蛋白表达的亚细胞区域. 结果:除BJAB细胞株外,所有标本中均检测到EB病毒W片段;RPMS1 mRNA在鼻咽癌组织中的表达率为83.3%(45/54),在鼻咽非癌组织中则仅为4%(1/25),二者有显著性差异(P<0.001),鼻咽癌外周血淋巴细胞中未检测到RPMS1表达,RPMS1在SUNE1细胞中的表达高于Raji细胞,但不表达于B95.8细胞;RPMS1可稳定表达于HEK293细胞,其编码蛋白的表达以胞核为主. 结论:EB病毒RPMS1基因在高发区鼻咽癌组织中存在高水平转录,在体外可稳定表达于上皮细胞的胞核,提示RPMS1编码蛋白可能作为核转录因子通过调控细胞增殖相关的信息传递而参与上皮癌变过程.     

不同茶叶及茶多酚对高脂饲料致大鼠脂肪肝的影响

目的:考察不同产地绿茶、红茶以及绿茶多酚对高脂饲料致大鼠脂肪肝的影响.方法:大鼠喂饲高脂饲料制备大鼠脂肪肝模型,喂饲含不同茶叶或茶多酚的高脂饲料,观察体重变化、睾丸脂肪垫重量、血清TG和TC、肝脏脂肪性变、肝匀浆甘油三酯和胆固醇含量.结果:各受试物组睾丸脂肪垫重量均较模型对照组减轻,云南绿茶组和四川绿茶组肝匀浆甘油三酯和胆固醇均明显低于模型对照;茶多酚组肝匀浆甘油三酯也明显低于模型对照组,但高于云南绿茶组和四川绿茶,茶多酚组肝匀浆胆固醇低于模型对照组,但明显高于云南绿茶组和四川绿茶组;云南红茶组肝匀浆甘油三酯和胆固醇与模型对照组相当.结论:云南绿茶和四川绿茶均对高脂饲料致大鼠脂肪肝的形成有明显抑制作用;茶多酚也有一定作用;但云南红茶作用不明显.     

构建RNA干扰载体特异性抑制绿色荧光蛋白表达的研究

目的:利用PCR构建RNA干扰质粒载体的方法,促进RNA干扰技术的广泛开展.方法:PCR方法获得小鼠U6 27启动子序列,以及干扰绿色荧光蛋白(EGFP)表达的siRNA的相应DNA模板序列.将其序列克隆入pUC19,获得RNA干扰载体pU6-siEGFP.将pU6-siEGFP及pcDNA3.1/EGFP共转导COS-7细胞,观察EGFP表达情况.结果:所构建的pU6-siEGFP能够成功干扰COS-7细胞中EGFP的表达.结论:PCR方法成功构建了RNA干扰载体,为RNA干扰技术在更多实验室的广泛开展奠定基础.     

神经干细胞的体外培养及增强型绿色荧光蛋白基因转染研究

目的探索大鼠胚胎神经干细胞(NSCs)的体外培养,探讨NSCs作为基因靶细胞,以及逆转录病毒介导增强型绿色荧光蛋白(EGFP)标记NSCs的可行性.方法胚胎大鼠脑组织分离神经干细胞,无血清培养,免疫组织化学技术鉴定.用Lipofectin将pLEGFP-N1逆转录病毒载体导入PA317包装细胞,用G418筛选获得抗性细胞克隆,扩增抗性细胞并收集病毒上清;病毒上清感染神经干细胞,用G418筛选,荧光显微镜下观察并挑选EGFP表达最强的克隆,并做免疫组化鉴定;进一步培养扩增,做传代细胞的分化鉴定.结果培养出大鼠胚胎神经干细胞.荧光显微镜下检测感染逆转录病毒的神经干细胞,以及免疫组化鉴定,均显示EGFP获得良好表达;而且感染细胞能够被诱导分化为神经元和神经胶质细胞.结论大鼠胚胎神经干细胞能够在体外适宜的条件下进行长期培养;神经干细胞可直接作为基因靶细胞;利用逆转录病毒载体,建立稳定表达EGFP的神经干细胞系具有可行性,为进一步做标记细胞移植研究奠定基础.     

丽春红2R-亮绿染色法显示大鼠皮质脊髓束的实验研究

目的:探索显示和区分皮质脊髓束在大鼠脑干和脊髓内定位的染色方法。方法:通过丽春红2R-亮绿双重染色法对正常SD大鼠延髓、脊髓(颈5、胸10、腰3、骶2节段)组织切片进行染色。结果:丽春红2R-亮绿染色后,延髓和脊髓白质中神经纤维束轴索、髓鞘呈橙红色,灰质背景呈淡绿色,其中神经元呈绿色。在延髓锥体、锥体交叉中及在脊髓颈、胸段后索腹侧最深层可见皮质脊髓束染成橙红色,着色略深,与其背侧的薄束和腹侧的灰质界限分明、对比清晰。结论:丽春红2R-亮绿染色法可以清楚地显示成年大鼠皮质脊髓束在脑干和脊髓内的位置,为中枢神经损伤与修复研究提供一种简便、快速、可靠的神经纤维束定位染色方法。     

Folliculogenesis following syngeneic transplantation of young murine ovaries into the testes

Background and Aim:  To examine the effects of intratesticular transplantation on the growth and maturation of young murine ovaries.
Methods:  Two-week-old ovaries from transgenic mice with enhanced green fluorescent protein expression were transplanted under the testicular capsule of 4-week-old non-transgenic mice.
Results:  Two months after transplantation all successfully grafted ovaries had survived, based on the presence of bright green fluorescence. The grafts showed various stages of folliculogenesis, including expanded follicles. The neighboring seminiferous tubules had a normal structure and mature sperm in their lumens, indicating active spermatogenesis, and all the recipient males were fertile. There was no evidence of extensive cell migration from the grafted ovaries into the testis. Similar findings were obtained for the grafted ovaries 6 months after surgery, although cell death (as evidenced by yellowish or pale fluorescence) was more frequent.
Conclusion:  Young murine ovaries can grow and mature autonomously for at least 6 months unaffected by the male hormonal environment. (Reprod Med Biol 2006; 5 : 71–77)     

人膀胱肿瘤细胞的荧光标记及其移植模型的整体荧光成像

目的对人膀胱移行细胞癌T24细胞进行荧光标记并建立其可在活体荧光成像系统下直接观察肿瘤生长及转移的简便、可靠的原位移植模型。方法以绿色荧光蛋白作为标记基因导入人类膀胱移行细胞癌T24细胞株中,经梯度浓度G418筛选获得稳定表达绿色荧光蛋白的细胞克隆并扩大培养,然后接种于裸小鼠膀胱壁内及颈部皮下,活体荧光成像系统直接观察肿瘤的生长与转移,并与常规石蜡切片苏木素-伊红(HE)染色比较。结果经绿色荧光蛋白标记的人膀胱肿瘤T24细胞在荧光显微镜下发出绿色荧光,并可在体内、外持续稳定表达。膀胱原位接种5×105个转染后的膀胱肿瘤细胞后1周即可在荧光成像系统下观察到下腹部新生膀胱肿瘤发出绿色荧光,2周后膀胱肿瘤可被触及,4周后经解剖可在荧光成像系统下观察到腹膜后及盆腔淋巴结等远处转移。结论绿色荧光蛋白能够在T24人膀胱肿瘤细胞中长期稳定表达,用绿色荧光蛋白标记的人膀胱肿瘤T24细胞建立的裸鼠原位移植模型为进一步研究膀胱肿瘤提供了一种简便、可行的新方法。     

TIMP-1绿色荧光蛋白真核表达载体的构建和鉴定

目的:构建并鉴定TIMP-1绿色荧光蛋白真核表达载体.方法:提取胃癌组织总RNA,用TIMP-1基因引物进行RT-PCR,将扩增产物克隆至pGEM-T载体,PCR鉴定及测序证实后,BamH Ⅰ和HindⅢ双酶切pGEM-T-TIMP-1重组体,回收TIMP-1,再将其亚克隆到绿色荧光蛋白真核表达载体pEGFP-C3中,并对阳性克隆进行酶切鉴定和测序分析.结果:构建的pEGFP-C3-TIMP-1表达载体分别作PCR及双酶切鉴定,证实其中有目的片段完整插入,插入片段测序结果与TIMP-1序列设计完全一致,将其转染人胃癌BGC-823细胞后,TIMP-1的表达定位在细胞胞浆内.结论:成功构建了TIMP-1绿色荧光蛋白真核表达载体,为TIMP-1的肿瘤靶向治疗研究奠定了基础.