The Lac repressor provides a reversible gene expression system in undifferentiated and differentiated embryonic stem cell

Control of mammalian gene promoters by the bacterial LacI repressor provides reversible regulation and dose-response levels of derepressed expression by the lactose analog isopropyl thiogalactose (IPTG). Here, we show that insertion of LacI-binding sites in the ubiquitous β-actin promoter confers a strong and dose-dependent IPTG-regulatable expression of transiently transfected reporter genes in mouse embryonic stem (ES) cells expressing LacI. We established ES cell lines stably expressing reporter genes under inducible control and found a five- to tenfold IPTG induction of transgene expression. The kinetics of induction is rapid and stable, and can be rapidly reversed after IPTG removal. Importantly, this regulatable expression was maintained throughout the differentiation process of ES cells, and observed in individual differentiated cardiomyocyte-like cells and neuronal-like cells. This reversible system is the first to function from undifferentiated to individual welldifferentiated ES cells, providing a very useful tool to understand molecular mechanisms underlying ES cell self-renewal, commitment and differentiation.Received 17 March 2005; received after revision 19 April 2005; accepted 25 April 2005     

Effects of retinoic acid on ascites cells of the TA3 mouse mammary carcinoma

Summary Retinoic acid caused a decrease in adhesiveness but no growth change in the allotransplantable TA3-Ha cell and no change in adhesiveness or growth in the strain specific TA3-St cell. The retinoic acid binding protein was detected in the TA3-Ha, but not the TA3-St, cell.This study was supported in pat by Public Health Service Grants CA-08418 and CA-18600 from the National Cancer Institute, National Institutes of Health. This is publication 955 of the Robert W. Lovett Group for the Study of Diseases Causing Deformities. We gratefully acknowledge the contributions of Drs Luigi M. De Luca and Anton M. Jetten of the Laboratory of Cellular Carcinogenesis and Tumor Promotion, National Cancer Institute, National Institutes of Health, Bethesda, MD, without whose help this study would not have been possible.     

乙硫氨酸对小鼠脂肪代谢影响的研究

目的观察乙硫氨酸所致小鼠脂肪肝模型不同时间脂代谢的变化,为利用该模型研究抗脂肪肝药物及选择适宜的给药时间提供科学依据。方法小鼠分为6组,分别检测正常组血脂、肝脂及灌服乙硫氨酸后6、12、24、36、48h各组动物的血脂、肝脂变化。结果小鼠灌服乙硫氨酸后,血清TG在造型后6～48h显著升高,血清TC在造型后6～36h显著升高;肝脏TG在造型后6～36h显著升高,肝脏TC在造型后24～36h显著降低。结论乙硫氨酸诱导的小鼠脂肪肝模型在6～36h比较稳定。     

10种常用SPF级实验大、小鼠体重及主要脏器的测定

目的测定10种常用SPF级大、小鼠体重、脏器及肠道等正常参考值。方法解剖10种品系实验动物,称量各组织脏器的相对重量,用尺测量肠道长度,共对9种脏器指标进行了测定。结果不同品系动物的各种脏器指标有明显差别,即使是同种品系,不同性别间也存在差异。     

10种常见SPF级实验大、小鼠血液学及生化指标正常参考值的探讨

目的建立10种常见SPF级实验大、小鼠血液及生化正常参考值。方法采用半自动生化测定仪及血球计数仪对不同周龄、不同性别的常见10种SPF大鼠的血液学指标及生化指标值进行测定。结果取得4周龄和8周龄不同周龄、不同性别大、小鼠血液学及生化值平均值及正常参考范围;多数生化指标受年龄及性别的影响,除了不同品系、年龄和性别的大、小鼠ALP呈现规律性变化,其他指标也与相关报道有差异。结论在基础生物学研究中,要充分考虑到性别和年龄对实验动物血液学及血清生化指标的影响。     

淋巴细胞脉络丛脑膜炎病毒(LCMV)PCR检测方法的建立与初步应用

目的建立检测淋巴细胞脉络丛脑膜炎病毒(LCMV)的PCR方法。方法根据LCMV CDNA S片段的GPC和NP基因设计合成4对引物,对标准毒株进行套式PCR扩增并克隆测序,并对15份已知阳性或阴性小鼠鼠脑进行检测。结果目的片断与LCMV cDNA序列99%同源,对鼠脑的检测结果为10只阳性,5只阴性。结论检测小鼠鼠脑LCMV的结果准确,证明套式PCR能够应用于LCMV的实验室检测。     

(鼠标)模拟动态数字输入的识别之轨迹数据采集

在研究动态数字输入识别方法中,如何实现鼠标模拟动态数字输入的识别方法,首先最关键的问题是怎样获取鼠标轨迹的数据.在以OnMouseMove函数获取鼠标移动消息的方法中,该函数响应时间太长,其函数的数据不能完全表达鼠标的轨迹信息.通过采用连线取点的方法较好的克服以上的不足,得以获取完整的鼠标轨迹信息.     

三氯化铝对小鼠性腺的影响研究

为测定三氯化铝 (AlCl3)染毒后小鼠各性腺的重量及微量元素Zn、Cu含量 ,从微量元素角度探讨铝对小鼠性腺的毒性作用。采用二级昆明品系雄性小鼠 ,随机分为 3组 ,正常对照组 (简称对照组 )、三氯化铝低剂量染毒组 (简称低铝组 )、三氯化铝高剂量染毒组 (简称高铝组 )。实验结束后测定小鼠各性腺的重量和微量元素锌、铜含量。数据均经统计学处理。结果为高铝组使小鼠精囊腺和前列腺重量下降 (P <0 .0 5) ,使睾丸和包皮腺重量显著下降 (P <0 .0 1 ) ,对附睾重量不影响。微量元素含量与对照组比较 ,低铝组锌、铜含量虽有变化趋势 ,但尚未达到统计学意义 ,而高铝组与对照比较锌、铜含量显著变化 (P <0 .0 1 )。结论 :高剂量铝可影响雄性小鼠性腺重量和微量元素含量 ,使其微量元素失衡 ,对雄性小鼠性腺有毒性作用     

小鼠无鱼粉日粮的进一步研究

在无鱼粉日粮基础上 ,添加复合维生素、复合微量元素、限制性氨基酸组成的全价饲料饲喂小鼠 ,其小鼠的生长发育和繁殖性能都有所提高 ,表明复合添加剂提高了无鱼粉日粮的质量 ,豆粕—血肉骨粉—复合添加剂型饲料可以有效地用于饲喂繁殖生产小鼠     

Study for interrelationship between human herpes simplex virus type 2 and leukemia

Two different strains of human herpes simplex virus type 2 (HHSV-2) and /or murine leukemia virus (MLV) were inoculated into newborn mice. In mice of mixed infection with MLV plus HHSV-2(333) or MLV plus HHSV-2(Wu)incidences of leukemia were respectively 79.16% and 75.00%,and in those inoculated with MLV alone were 41.02% and 44.74% in the experiment for 3 months. The differences of incidences between the two conditions were highly significant (p<0.01). On the contrary, no leukemia was detected in mice that were inoculated with HHSV-2 (333) or HHSV-2 (Wu) alone and in controls. Leukemia developing time of mice infected with two viruses was earlier than with MLV alone. It is obvious that the induction of murine leukemia resulted from infection of MLV and was independent of HHSV-2 (333) and HHSV-2(Wu). Both risen incidences and shortened latencies of murine leukemia were in close relationship with infection of HHSV-2(333) and HHSV-2(Wu). Foundation item: Supported by the National Natural Science Foundation of China (No. 59678017) Biography: Liu Jian-jun (1954-), male, associate research fellow, research direction: experimental oncology.