高浓度葡萄糖对小鼠囊胚Caspase-8表达的影响

目的:探讨高浓度葡萄糖对小鼠囊胚Caspase-8表达的影响.方法:通过促超排卵,获取妊娠3.5d小鼠囊胚,随机分成三组,即对照组(空白)、低糖组(葡萄糖浓度为7.5mmol/L)和高糖组(葡萄糖浓度为28.0mmol/L),分别培养在含0、7.5mmol/L和28.0mmol/L葡萄糖的M199培养基中,培养24h后,然后再吸出囊胚.每组随机吸取30个囊胚用免疫组织化学S-P法.检测不同浓度葡萄糖对小鼠囊胚Caspase-8表达状况,利用HPIAS-1000图像分析系统测定Caspase-8在以上三组中表达的平均光密度和平均阳性面积率.结果:Caspase-8表达结果:空白组中囊胚细胞胞浆中可见少量浅棕黄色颗粒,Caspase-8表达呈弱阳性.低糖组中囊胚细胞胞浆未见着色,Caspase-8表达呈阴性.高糖组囊胚细胞胞浆中可见较多的棕黄色颗粒,Caspase-8表达呈强阳性.空白组与低糖组囊胚Caspase-8表达的阳性面积率及平均光密度无显著性差异(P>0.05),高糖组与空白组和低糖组相比均存在显著性差异(P<0.01).结论:高浓度葡萄糖可诱导Caspase-8的过度表达,导致囊胚细胞数目过度减少,从而影响囊胚的正常发育和着床.     

血管生长抑素在小鼠胚泡中的调节作用

血管生长抑素（angiostatin,AS）是一种新血管生成的抑制蛋白,它可以有效抑制内皮细胞的增殖、迁移和管状形态的产生,是肿瘤转移的有效抑制剂.肿瘤转移和胚胎植入具有惊人的相似性,AS对小鼠胚胎植入是否有作用迄今尚无报道.采用体外培养、RT-PCR和蛋白质印迹等多种方法研究了AS对小鼠胚泡中血管内皮生长因子（VEGF）及其受体KDR、基质金属蛋白酶(MMPs)及其组织抑制剂(TIMPs)的影响.研究显示,AS下调了VEGF及其受体KDR、MMP-2和MMP-9的表达,而上调了TIMP-1和TIMP-2的表达.应用整合素αVβ3的特异性抑制剂Echistatin与AS共同处理胚泡,结果显示,Echistatin减弱了AS对MMP-2的下调作用及对TIMP-2的上调作用.以上结果提示：AS可能通过与整合素αVβ3相互作用调节胚泡中VEGF、MMPs和TIMPs的表达,从而影响胚泡的植入过程.     

牛血清白蛋白对小鼠原核期胚胎玻璃化冷冻的影响

以小鼠原核期胚胎为对象,以胚胎的存活率、卵裂率、囊胚率以及囊胚细胞数作为检测指标,在M2液的基础上添加8种浓度(0,2,4,8,16,32,64,96mg/mL)牛血清白蛋白(BSA)配置防冻液,探讨防冻液和玻璃化冷冻后对胚胎发育的影响。BSA防冻液对胚胎发育影响的实验结果表明,8个浓度组间以及与对照组间胚胎的卵裂率、囊胚率以及囊胚细胞数无显著差异(P>0.05),说明在防冻液中加入一定浓度的BSA对小鼠胚胎无毒性作用。防冻液经玻璃化冷冻后对胚胎发育影响的实验表明,8个浓度组间冷冻胚胎复苏后的存活率、卵裂率、囊胚率及囊胚细胞数无显著差异(P>0.05)。表明BSA在这种防冻液中没有明显的保护作用。从经济、实用、生物安全角度考虑,不支持在玻璃化防冻液中添加BSA。     

小鼠原核胚玻璃化冷冻保存技术的研究

目的　原核胚是转基因等生物技术所必需的主要材料 ,其冷冻保存使操作不受时间和空间的限制。另外 ,冷冻保存还可以避免体外培养过程中的细胞发育阻断期。方法　在室温 (2 0℃或 2 5℃ )条件下 ,以乙二醇、DMSO为主体抗冻保护剂配制成的玻璃化溶液 (EFS、EDT、EDFS) ,不借助冷冻仪 ,对小鼠原核胚进行一步法和二步法玻璃化冷冻保存。结果　 2 0℃室温条件下 ,用EDFS4 0平衡 1min一步法冷冻解冻后的原核胚 ,经培养后囊胚发育率最高仅为 4 7% ,与新鲜原核体外培养的对照组 (75 % )的差异极显著 (P <0 0 1) ;当原核在 10 %E +10 %D溶液中预处理 5min ,移入EDFS30中平衡 30s二步法冷冻保存 ,解冻后的囊胚发育率达 6 8%。而室温升至 2 5℃ ,二步法冷冻保存后原核胚的囊胚发育率高达 77% ,与对照组差异无显著性 (P >0 0 5 )。用最佳冷冻组的原核胚或解冻后培养到囊胚移植给受体母鼠均获得产仔。结论　本研究对小鼠原核胚实施玻璃化冷冻保存 ,经体外培养和移植结果与对照组无显著性差异 ,证明了本方法的可行性     

Derivation of Mouse Trophoblast Stem Cells from Blastocysts

Specification of the trophectoderm is one of the earliest differentiation events of mammalian development. The trophoblast lineage derived from the trophectoderm mediates implantation and generates the fetal part of the placenta. As a result, the development of this lineage is essential for embryo survival. Derivation of trophoblast stem (TS) cells from mouse blastocysts was first described by Tanaka et al. 1998. The ability of TS cells to preserve the trophoblast specific property and their expression of stage- and cell type-specific markers after proper stimulation provides a valuable model system to investigate trophoblast lineage development whereby recapitulating early placentation events. Furthermore, trophoblast cells are one of the few somatic cell types undergoing natural genome amplification. Although the molecular pathways underlying trophoblast polyploidization have begun to unravel, the physiological role and advantage of trophoblast genome amplification remains largely elusive. The development of diploid stem cells into polyploid trophoblast cells in culture makes this ex vivo system an excellent tool for elucidating the regulatory mechanism of genome replication and instability in health and disease. Here we describe a protocol based on previous reports with modification published in Chiu et al. 2008.Download video file.^{(116M, mp4)}     

Reprogramming of the MicroRNA Transcriptome Mediates Resistance to Rapamycin

The mammalian target of rapamycin (mTOR) is a central regulator of cell proliferation that is often deregulated in cancer. Inhibitors of mTOR, including rapamycin and its analogues, are being evaluated as antitumor agents. For their promise to be fulfilled, it is of paramount importance to identify the mechanisms of resistance and develop novel therapies to overcome it. Given the emerging role of microRNAs (miRNAs) in tumorigenesis, we hypothesized that miRNAs could play important roles in the response of tumors to mTOR inhibitors. Long-term rapamycin treatment showed extensive reprogramming of miRNA expression, characterized by up-regulation of miR-17–92 and related clusters and down-regulation of tumor suppressor miRNAs. Inhibition of members of the miR-17–92 clusters or delivery of tumor suppressor miRNAs restored sensitivity to rapamycin. This study identifies miRNAs as new downstream components of the mTOR-signaling pathway, which may determine the response of tumors to mTOR inhibitors. It also identifies potential markers to assess the efficacy of treatment and provides novel therapeutic targets to treat rapamycin-resistant tumors.     

小鼠囊胚植入三维模型的实验研究

将人纤维蛋白凝胶作为小鼠囊胚体外三维培养的支持物,建立小鼠囊胚体外三维植入模型,用以观察囊胚在体外的立体生长情况。通过实验表明人纤维蛋白凝胶对培养小鼠囊胚的孵出率、扩展率均无影响。在人纤维蛋白凝胶上培养的囊胚可以保持囊胚的立体结构,并有滋养层细胞极性的迁移和部分细胞的植入,使其更接近于体内囊胚的着床行为。说明人纤维蛋白凝胶可以作为小鼠囊胚三维培养的支持物,为研究小鼠囊胚植入机制建立实验基础。     

Long Term Culture of Cells Derived from Mouse Blastocysts

The development of mouse blastocysts in primary culture has been followed for up to two months. The trophectoderm layer of the blastocyst gives rise to a monolayer of trophoblast cells; cells resembling both ectoplacental cone cells and primary giant cells are observed. The former can transform to giant cells, presumably secondary trophoblast, after several days in culture. Giant trophoblast cells are evident in the culture for much longer than the normal gestation period. Under the culture conditions described, the proportion of blastocysts showing substantial inner cell mass (ICM) proliferation in vitro is higher than that noted in previous studies. The ICM clumps develop into either egg cylinder-like structures, or, more commonly, into spherical, fluid-filled vesicles. The vesicles, which resemble yolk sac morphologically and biochemically [10, 11], continue to enlarge in size during several weeks of culture. The vesicles are attached to the underlying trophoblast monolayers by a stalk. Cells appear to migrate from this stalk out along the culture dish. The result after two to four weeks of culture is the appearance of a mixed monolayer containing a variety of different cell types. Secondary cultures of blastocyst cells have been continuously maintained in vitro for more than one year. Four lines of cells, all developing from the same pool of blastocysts, have been monitored for morphological, growth and biochemical properties, as well as chromosome number. Each line contained two or more morphologically distinct cell types, clearly indicated by cloning studies after eight months of culture. Doubling times and saturation densities among the four lines differed, as did biochemical properties. Although none of the cell lines resembled trophoblast biochemically after 7.5 months in culture, one line, MB4, possessed a number of biochemical properties in common with midgestation yolk sac. After a further five months of culture, some enzymes in the four lines were relatively unchanged; in other cases, notably with alkaline phosphatase, a sharp drop in enzyme activity was observed. One cell line, MB2, and specifically one of the cell types in this line, produced a yellow-orange pigment with a spectrum resembling that of a heme protein. After 7.5 months of culture, two of the four lines, MB21 and MB31, contained large numbers of cells with a diploid number of chromosomes. However, by 12.5 months in culture, the large majority of metaphases in all four cell lines possessed a hypotetraploid chromosome number. In a number of studies carried out to date, none of the cell lines generated tumors when injected into syngeneic hosts.     

MicroRNA Transcriptome Profile Analysis in Porcine Muscle and the Effect of miR-143 on the MYH7 Gene and Protein

Porcine skeletal muscle fibres are classified based on their different physiological and biochemical properties. Muscle fibre phenotype is regulated by several independent signalling pathways, including the mitogen-activated protein kinase (MAPK), nuclear factor of activated T cells (NFAT), myocyte enhancer factor 2 (MEF2) and peroxisome proliferator-activated receptor (PPAR) signalling pathways. MicroRNAs are non-coding small RNAs that regulate many biological processes. However, their function in muscle fibre type regulation remains unclear. The aim of our study was to identify miRNAs that regulate muscle fibre type during porcine growth to help understand the miRNA regulation mechanism of fibre differentiation. We performed Solexa/Illumina deep sequencing for the microRNAome during 3 muscle growth stages (63, 98 and 161 d). In this study, 271 mature miRNAs and 243 pre-miRNAs were identified. We detected 472 novel miRNAs in the muscle samples. Among the mature miRNAs, there are 23 highest expression miRNAs (over 10000 RPM), account for 85.3% of the total counts of mature miRNAs., including 10 (43.5%) muscle-related miRNAs (ssc-miR-133a-3p, ssc-miR-486, ssc-miR-1, ssc-miR-143-3p, ssc-miR-30a-5p, ssc-miR-181a, ssc-miR-148a-3p, ssc-miR-92a, ssc-miR-21, ssc-miR-126-5p). Particularly, both ssc-miR-1 and ssc-miR-133 belong to the MyomiRs, which control muscle myosin content, myofibre identity and muscle performance. The involvement of these miRNAs in muscle fibre phenotype provides new insight into the mechanism of muscle fibre regulation underlying muscle development. Furthermore, we performed cell transfection experiment. Overexpression/inhibition of ssc-miR-143-3p in porcine skeletal muscle satellite cell induced an/a increase/reduction of the slow muscle fibre gene and protein (MYH7), indicating that miR-143 activity regulated muscle fibre differentiate in skeletal muscle. And it regulate MYH7 through the HDAC4-MEF2 pathway.     

Cryopreservation of Mouse Embryos by Ethylene Glycol-Based Vitrification

Cryopreservation of mouse embryos is a technological basis that supports biomedical sciences, because many strains of mice have been produced by genetic modifications and the number is consistently increasing year by year. Its technical development started with slow freezing methods in the 1970s¹, then followed by vitrification methods developed in the late 1980s². Generally, the latter technique is advantageous in its quickness, simplicity, and high survivability of recovered embryos. However, the cryoprotectants contained are highly toxic and may affect subsequent embryo development. Therefore, the technique was not applicable to certain strains of mice, even when the solutions are cooled to 4°C to mitigate the toxic effect during embryo handling. At the RIKEN BioResource Center, more than 5000 mouse strains with different genetic backgrounds and phenotypes are maintained³, and therefore we have optimized a vitrification technique with which we can cryopreserve embryos from many different strains of mice, with the benefits of high embryo survival after vitrifying and thawing (or liquefying, more precisely) at the ambient temperature⁴.Here, we present a vitrification method for mouse embryos that has been successfully used at our center. The cryopreservation solution contains ethylene glycol instead of DMSO to minimize the toxicity to embryos⁵. It also contains Ficoll and sucrose for prevention of devitrification and osmotic adjustment, respectively. Embryos can be handled at room temperature and transferred into liquid nitrogen within 5 min. Because the original method was optimized for plastic straws as containers, we have slightly modified the protocol for cryotubes, which are more easily accessible in laboratories and more resistant to physical damages. We also describe the procedure of thawing vitrified embryos in detail because it is a critical step for efficient recovery of live mice. These methodologies would be helpful to researchers and technicians who need preservation of mouse strains for later use in a safe and cost-effective manner.     

不同品系小鼠胚胎玻璃化冷冻保存的比较研究

目的　研究甘油作为冷冻保护剂、不同基因型小鼠对胚胎玻璃化冷冻的影响。方法　采用 6 5mol L的甘油作为冷冻保护剂 ,采用二步法对CBA、NOD、C57BL 6J、ICR及CD1小鼠 3 5d的胚胎进行玻璃化冷冻 ,并比较了不同品系小鼠胚胎的复苏率及移植受孕率。结果和结论　CBA、NOD、C57BL 6J,ICR及CD1的复苏率分别为 5 7 6 %、4 8%、31 3%、86 5 %及 88% ,移植受孕率为 2 1%、2 3 5 %、11%、38%和 35 5 % ,封闭群小鼠的胚胎复苏率、移植受孕率均显著高于近交系小鼠。这提示胚胎的复苏率及移植受孕率可能与小鼠的不同基因型有关。五个品系中 ,桑椹胚及早期囊胚的体外复苏率均显著高于扩张囊胚。这说明不同基因型及胚胎的不同发育阶段对胚胎玻璃化冷冻效果有影响