植物中铵转运蛋白的研究进展

铵转运蛋白在众多生物中被克隆与鉴定,它是一种广泛存在于微生物、植物细胞及动物的细胞膜上主动转运铵离子的载体,分子量约为48kD,含有10～11个跨膜域.本文阐述了植物铵转运蛋白分离鉴定的过程,对于铵转运蛋白的结构、功能、基因表达调控等方面作了较详细叙述.不同氮素条件下,铵转运蛋白基因通过转录调控表现了对铵离子吸收转运的不同特点,使植物根系在较宽的浓度范围中吸收铵离子,为细胞内铵离子库的内稳态提供了理论依据.铵转运蛋白有助于作物更有效的吸收氮素,为农业生产粮食增收提供了有利保障.     

Hdac2 regulates the cardiac hypertrophic response by modulating Gsk3 beta activity

In the adult heart, a variety of stresses induce re-expression of a fetal gene program in association with myocyte hypertrophy and heart failure. Here we show that histone deacetylase-2 (Hdac2) regulates expression of many fetal cardiac isoforms. Hdac2 deficiency or chemical histone deacetylase (HDAC) inhibition prevented the re-expression of fetal genes and attenuated cardiac hypertrophy in hearts exposed to hypertrophic stimuli. Resistance to hypertrophy was associated with increased expression of the gene encoding inositol polyphosphate-5-phosphatase f (Inpp5f) resulting in constitutive activation of glycogen synthase kinase 3beta (Gsk3beta) via inactivation of thymoma viral proto-oncogene (Akt) and 3-phosphoinositide-dependent protein kinase-1 (Pdk1). In contrast, Hdac2 transgenic mice had augmented hypertrophy associated with inactivated Gsk3beta. Chemical inhibition of activated Gsk3beta allowed Hdac2-deficient adults to become sensitive to hypertrophic stimulation. These results suggest that Hdac2 is an important molecular target of HDAC inhibitors in the heart and that Hdac2 and Gsk3beta are components of a regulatory pathway providing an attractive therapeutic target for the treatment of cardiac hypertrophy and heart failure.     

Pyrazolo[3,4-d]pyrimidine derivatives containing a Schiff base moiety as potential antiviral agents

A series of pyrazolo[3,4-d]pyrimidine derivatives containing a Schiff base moiety were synthesized, characterised, and evaluated for their activity against tobacco mosaic virus (TMV). Biological assays indicated that several of the derivatives exhibited significant activity against TMV. In particularly, compounds 5y and 5aa displayed excellent inactivating activity against TMV, with half maximal effective concentration (EC₅₀) values of 70.3 and 53.65?μg/mL, respectively, which were much better than that of ribavirin (150.45?μg/mL), and 5aa was superior to ningnanmycin (EC₅₀?=?55.35?μg/mL). Interactions of compounds 5y and 5aa with TMV coat protein (TMV-CP) were investigated using microscale thermophoresis and molecular docking. Compounds 5y and 5aa displayed strong binding capability to TMV-CP with dissociation constant (K_d) values of 22.6 and 9.8?μM, respectively. These findings indicate that pyrazolo[3,4-d]pyrimidine derivatives containing a Schiff base may be potential antiviral agents.     

MicroRNA-221 promotes colorectal cancer cell invasion and metastasis by targeting RECK

MicroRNAs (miRNAs) have recently emerged as regulators of metastasis. We provide insight into the behavior of miR-221 in colorectal cancer (CRC) metastasis by showing that miR-221 is significantly upregulated in metastatic CRC cell lines and tissues. miR-221 overexpression enhances, whereas miR-221 depletion reduces CRC cell migration and invasion in vitro and metastasis in vivo. We identify RECK as a direct target of miR-221, reveal its expression to be inversely correlated with miR-221 in CRC samples and show that its re-introduction reverses miR-221-induced CRC invasiveness. Collectively, miR-221 is an oncogenic miRNA which may regulate CRC migration and invasion through targeting RECK.     

长时程增强诱导和维持过程中海马CA1区神经细胞粘附分子蛋白水平与mRNA表达的变化

既往研究发现,神经细胞粘附分子(neural cell adhesion molecules,NCAM)对海马CA1区突触传递长时程增强(longterm potentiation,LTP)的诱导和维持极为关键。本文采用原位杂交法和Western blot法,观察了大鼠海马腑片LTP诱导和维持过程中NCAM mRNA和蛋白水平的动态变化过程。结果显示,强直刺激诱发fEPSP斜率升高10 min时,海马CA1区NCAM mRNA染色阳性神经元数量显著增加(76.6±11.5个),NCAM蛋白水平亦明显升高(7.190±0.64任意单位/50μg蛋白)。强直刺激诱发fEPSP斜率升高1 h时,NCAM mRNA染色阳性神经元数量为73.3±14.0个,NCAM蛋白量为9.031±0.71任意单位/50 μg蛋白;与强直刺激后10 min比较,NCAM mRNA表达无显著变化,而NCAM蛋白水平变化明显。NMDA受体特异阻断剂AP-5在损害LTP的同时,显著抑制NCAM mRNA和蛋白的增加。实验结果表明,在大鼠海马LTP诱导和维持过程中,NCAM mRNA增强的表达相对稳定,而NCAM蛋白水平呈现先低后高的变化。     

金丝小枣基因组DNA的优化提取方法

采用SDS和CTAB两种方法分离提取金丝小枣基因组DNA,并比较其提取效果。结果表明,改进后的CTAB法可获得高质量、高得率的基因组DNA,可用于金丝小枣的各种分子生物学研究。     

Acute inducible ablation of GRP78 reveals its role in hematopoietic stem cell survival, lymphogenesis and regulation of stress signaling

GRP78, a master regulator of the unfolded protein response (UPR) and cell signaling, is required for inner cell mass survival during early embryonic development. However, little is known about its role in adult hematopoietic stem cells (HSCs) and hematopoiesis. Here we generated a conditional knockout mouse model that acutely deletes Grp78 in the adult hematopoietic system. Acute GRP78 ablation resulted in a significant reduction of HSCs, common lymphoid and myeloid progenitors, and lymphoid cell populations in the mutant mice. The GRP78-null induced reduction of the HSC pool could be attributed to increased apoptosis. Chimeric mice with Grp78 deletion only in the hematopoietic cells also showed a loss of HSCs and lymphopenia, suggesting a cell intrinsic effect. Analysis of GRP78 deficient bone marrow (BM) cells showed constitutive activation of all the major UPR signaling pathways, including activation of eIF2α, ATF6, xbp-1 splicing, as well as caspase activation. A multiplex cytokine assay further revealed alteration in select cytokine and chemokine serum levels in the mutant mice. Collectively, these studies demonstrate that GRP78 plays a pleiotropic role in BM cells and contributes to HSC survival and the maintenance of the lymphoid lineage.     

染色体步移技术研究进展

染色体步移技术是一种常用的克隆已知片段旁侧序列的技术.综述了近年来染色体步移技术的发展情况,介绍了结合基因组文库的染色体步移技术和基于PCR的染色体步移技术.同时总结了物理剪切法和限制性内切酶法构建亚克隆文库的优化步骤,以及连接成环PCR法、外源接头介导PCR法和半随机引物PCR法的原理,并且比较分析了他们之间的优缺点,以期对实际操作起到借鉴作用.