Combinatorial signals of activin/nodal and bone morphogenic protein regulate the early lineage segregation of human embryonic stem cells

Cell fate commitment of pre-implantation blastocysts, to either the inner cell mass or trophoblast, is the first step in cell lineage segregation of the developing human embryo. However, the intercellular signals that control fate determination of these cells remain obscure. Human embryonic stem cells (hESCs) provide a unique model for studying human early embryonic development. We have previously shown that Activin/Nodal signaling contributes to maintaining pluripotency of hESCs, which are derivatives of the inner cell mass. Here we further demonstrate that the inhibition of Activin/Nodal signaling results in the loss of hESC pluripotency and trophoblast differentiation, similar to BMP4-induced trophoblast differentiation from hESCs. We also show that the trophoblast induction effect of BMP4 correlates with and depends on the inhibition of Activin/Nodal signaling. However, the activation of BMP signaling is still required for trophoblast differentiation when Activin/Nodal signaling is inhibited. These data reveal that the early lineage segregation of hESCs is determined by the combinatorial signals of Activin/Nodal and BMP.     

EMS和^60Co对海甘蓝种子萌发及其M1代农艺性状的影响

用ＥＭＳ及＾６０Ｃｏ处理海甘蓝种子,对其萌发种子细胞内呼吸代谢有明显的影响。低浓度的ＥＭＳ或低剂量的＾６０Ｃｏ刺激呼吸,可提高抗坏血酸氧化酶和过氧化物酶的活性,促进种子的萌发和幼苗的生长。较高剂量的ＥＭＳ和＾６０Ｃｏ抑制呼吸,与之有关的抗坏血酸氧化酶和过氧化物酶的活性,种子发芽势和发芽率、幼苗生长高度和根系活力等随之下降,用不同剂量的ＥＭＳ和＾６０Ｃｏ处理海甘蓝种子,对Ｍ１代的产量和抗病性等有一定     

水稻体细胞杂交研究进展

水稻是世界重要的粮食作物,全世界约有120个国家种植水稻。水稻的近缘或远缘种具有一些优良性状,如抗病、抗虫、抗逆等。将这些性状导入水稻,是科学家们所希望的,但因用普通杂交方法存在交配系统的不亲和性等难题而进展不大。随着组织培养技术的发展,特别是植物原生质体培养技术的日趋成熟,使得人类能够在细胞水平通过体细胞杂交方法实现遗传信息的重组。     

cⅠ857基因的体外定位同义突变

 ｃⅠ８５７基因的体外定位同义突变陈南春,高辉,陈苏民,杨萍,刘新平（西安第四军医大学分子生物学研究所,西安７１００３２）外源基因要在大肠杆菌中获得高表达,需要合适的ＳＤ序列和可调控的强启动子［１］。ＰＬ启动子在原核启动子中属强启动子,它受ｃⅠ基因产物...     

红铃虫性诱剂开口纤维剂型及其在棉田中的竞争引诱作用

Hummel等1973年鉴定了红铃虫的性外激素是顺,顺-和顺,反-7,11-十六碳二烯-1-醇醋酸酯的复合物,并命名为“红铃虫性诱剂”(简称“Gossyplure”)。Biel等1974年用触角电图和大田诱捕试验,证明当两种异构体的配比为1∶1时效果最好。为延长性诱剂在大田中的有效期,研究工作者曾设计了多种释放器和可控缓释剂型。Shorey等1976年用铝圆筒包上尼龙纱作为释放器,红铃虫性诱剂的释放量为每晚5毫克/公顷,全年用量为9克/公顷。Gaston等1977年用内径0.22毫米、外径0.45毫米、长104毫米,一端开口一端封闭的塑料空心纤维,绕成直径22毫米的环作释放器,每次用量6.6克/公顷,全年用33克/公顷。Boncss等1977和1978年用聚乙烯盖作释放器,每次用量5克/公顷,胶囊剂     

GADD45α mediates arsenite‐induced cell apoptotic effect in human hepatoma cells via JNKs/AP‐1‐dependent pathway

Arsenite (As(III)), an effective chemotherapeutic agent for the acute promyelocytic leukemia (APL) and multiple myeloma (MM), might be also a promise for the therapy of other cancers, including the solid tumors. However, the molecular bases of arsenite‐induced cytotoxicity in the tumor cells have not been fully defined. In this study, we have disclosed that arsenite effectively induces the apoptotic response in the HepG2 human hepatoma cells by triggering GADD45α induction and the subsequent activation of JNKs/AP‐1 cell death pathway. However, signaling events relating to GADD45α/JNKs/AP‐1 pathway activation have not been observed in HL7702 human diploid hepatic cells under the same arsenite exposure condition. Our results thus have illustrated the selective pro‐apoptotic role of arsenite in the hepatoma cells by activating GADD45α‐dependent cell death pathway whereas with little effect on the normal hepatic cells. The approaches to up‐regulate GADD45α levels might be helpful in improving the chemotherapeutic action of arsenite on certain solid tumors including hepatoma. J. Cell. Biochem. 109: 1264–1273, 2010. © 2010 Wiley‐Liss, Inc.     

重庆市爬行动物物种多样性研究及保护

1996～2004年对重庆市35个县(区、市)进行野外调查采集,结合有关资料记载,重庆市共有爬行动物2目12科38属58种,其中龟鳖目4种,有鳞目蜥蜴亚目12种、蛇亚目42种(含重庆市蛇类新记录3属4种)。建议加强对该市爬行动物物种多样性及其生境的保护,合理利用爬行动物资源。     

波罗的海希瓦氏菌AI-2/LuxS对生物被膜和致腐的调控

【目的】波罗的海希瓦氏菌(Shewanella baltica)是冷藏海产鱼类的特定腐败菌。研究群体感应信号AI-2/Lux S对鱼源S.baltica生物被膜和致腐的调控作用。【方法】扩增SB11分离株的lux S基因,用自杀性质粒构建lux S基因缺失株,通过结晶紫染色、珠涡流法、显微镜观察和HPLC,比较分析野生株与缺失株△lux S在4°C和28°C下生物被膜形成、粘附能力、泳动性和致腐产物的差异。【结果】S.baltica SB11中扩增获得lux S基因,生物信息学分析显示Lux S蛋白由169个氨基酸构成,含有保守的His-Thr-Leu-Glu-His(HTLEH)模体和关键氨基酸位点,蛋白三维空间结构与其他细菌相似。与野生株相比,△lux S缺失株上清荧光信号散失,但不影响生长,生物被膜形成期和成熟期的含量显著低于野生株,在4°C培养96 h和28°C培养24 h被膜分别减少20.1%和27.9%。缺失株在不锈钢片的粘附能力明显减弱,其中在4°C培养72 h和28°C培养24 h后的粘附量比野生株分别减少6.48%和6.57%。荧光显微镜观察发现,野生株能快速粘附于玻璃片,聚集形成大量生物被膜,而△lux S仅形成平坦稀疏的被膜,粘附细菌降低,CLSM证实野生株和△lux S的成熟被膜厚度分别为68.95μm和36.44μm。并且,△lux S株在4°C和28°C下泳动性均显著强于野生株。然而,野生株和△lux S株三甲胺和腐胺积累无差异。【结论】鱼源S.baltica中Lux S蛋白保守,AI-2/Lux S参与被膜、粘附能力及泳动性等多种生物被膜形成相关的调控作用,然而不是该菌致腐能力的功能性群体感应信号。     

Effects of Cadmium on Root Growth, Cell Division and Nucleoli in Root Tip Cells of Garlic

The effects of different concentrations (10⁻⁷ to 10⁻² M) of cadmium chloride on root growth, cell division and nucleoli in root tip cells of Allium sativum L. were investigated. At lower concentrations of Cd²⁺ (10⁻⁷ to 10⁻⁶ M), Cd²⁺ did not influence the root growth, even had a stimulation effects during a short treatment. The results showed that the rate of root growth per day at the treatment groups (10⁻⁴ to 10⁻² M Cd²⁺) decreased with increasing duration of the treatment and increasing Cd²⁺ concentration. Cd²⁺ induced c-mitosis, anaphase bridges, chromosome stickiness and on nucleoli, causing some particles of similar silver-stained material scattered in the nuclei and making the silver staining reaction at the periphery of the nucleolus weaker. This revised version was published online in July 2006 with corrections to the Cover Date.