In vitro selected peptides bind with thymidylate synthase mRNA and inhibit its translation

Thymidylate synthase (TS), an essential enzyme for catalyzing the biosynthesis of thymidylate, is a critical therapeutic target in cancer therapy. Recent studies have shown that TS functions as an RNA-binding protein by interacting with two different sequences on its own mRNA, thus, repressing translational efficiency. In this study, peptides binding TS RNA with high affinity were isolated using mRNA display from a large peptide library (＞1013 different sequences). The randomized library was subjected up to twelve rounds of in vitro selection and amplification. Comparing the amino acid composition of the selected peptides (12th round, R12) with those from the initial random library (round zero, R0), the basic and aromatic residues in the selected peptides were enriched significantly, suggesting that these peptide regions might be important in the peptide-TS mRNA interaction. Categorizing the amino acids at each random position based on their physicochemical properties and comparing the distributions with those of the initial random pool, an obvious basic charge characteristic was found at positions 1, 12, 17 and 18, suggesting that basic side chains participate in RNA binding. Secondary structure prediction showed that the selected peptides of R12 pool represented a helical propensity compared with R0 pool, and the regions were rich in basic residues. The electrophoretic gel mobility shift and in vitro translation assays showed that the peptides selected using mRNA display could bind TS RNA specifically and inhibit the translation of TS mRNA. Our results suggested that the identified peptides could be used as new TS inhibitors and developed to a novel class of anticancer agents.     

二色补血草OEE2基因的克隆和表达

从二色补血草中分离出一条含有完整开放读码框（ORF）序列的OEE2基因。该基因全长994bp,其中5’非翻译区27bp,3’非翻译区160bp,ORF全长807bp,共编码264个氨基酸,编码蛋白的分子量为28．2kDa,理论上的等电点为7．66。BlastP分析表叽二色补血草OEE2与马铃薯OEE2序列同源性最高,与喇叭水仙OEE2序列同源性最低,从9个物种的氨基酸多序列比对中可以看出,OEE2的氨基酸序列保守性较高。实时定量RT．PCR方法检测该基因对低温、NaCl和聚乙二醇（PEG）胁迫的基因表达模式的结果表明,PEG和低温能诱导OEE2基因在二色补血草叶中表达,这两种处理的OEE2基因表达量于胁迫48h后都达到高峰,而在NaCl胁迫下OEE2在二色补血草根和叶中表达都受抑制。     

多重连接探针扩增方法在假肥大性肌营养不良产前基因诊断中的应用

假肥大性肌营养不良(Duchenne/Becker muscular dystrophy, DMD/BMD)是一种由于DMD基因突变导致的X连锁隐性致死性遗传病。目前没有有效的治疗方法。为建立一种既可以对携带者进行检测又可以进行产前基因诊断的方法, 文章联合应用多重连接探针扩增技术(Multiplex ligation-dependent probe amplification, MLPA)和短串联重复序列(Short tandem repeats , STR)为遗传标记连锁分析的方法对26例有高风险再生育患儿的假肥大性肌营养不良家系的孕妇通过羊水穿刺进行产前基因诊断。26例进行产前基因诊断的羊水标本中有7例诊断为男性患儿, 4例诊断为女性携带者。MLPA可以作为筛查DMD基因缺失和重复突变的首选方法。联合应用MLPA和STR连锁分析, 可以提高假肥大性肌营养不良的产前基因诊断率。     

类芽胞杆菌碱性果胶裂解酶的纯化与酶学性质表征

从类芽胞杆菌Paenibacillus sp.WZ008的发酵上清液中纯化得到一个高活力碱性果胶裂解酶,经SDS-PAGE电泳估算其亚基相对分子质量为4.5×104。通过对该酶进行酶学性质研究发现：该酶能催化裂解果胶酸、低酯果胶和高酯果胶;酶催化反应最适温度范围为55～60℃,最适pH为9.6,在最适条件下以低酯果胶为底物酶的比酶活达3 021.6 U/mg;Ca2＋能增强该酶的活力,而Mn2＋,Ba2＋和EDTA强烈抑制该酶活力;当没有Ca2＋存在时,高度酯化的果胶是该酶的最适底物,在4 mmol/L Ca2＋存在时,该酶以果胶酸为底物比酶活最高（25 467 U/mg）。该酶N端序列比对分析发现与类芽胞杆菌Paenibacillus amylolyticus strain 27c64果胶裂解酶高度同源。     

寨卡病毒引发小头症?关系越确定,防治越迫切!

自2015年初至今,寨卡病毒(Zika virus,ZIKV)以巴西为首先后在数十个国家和地区暴发流行。几乎同时,与日俱增的小头症患儿使全球对此陷入警惕状态。目前,全球正在积极探索ZIKV感染所引发的各种神经系统疾病。在越来越多证据表明在细胞水平和动物模型中ZIKV能直接损伤胚胎脑部发育的同时,ZIKV感染者的防治需求也越来越迫切。本文从ZIKV的流行病学、与小头畸形因果关系的研究进展及其预防疫苗和治疗药物的研究现状等方面进行概述。     

二代玉米螟为害玉米产量损失研究

【目的】研究二代亚洲玉米螟Ostrinia furnacalis(Guenee)为害对玉米产量的影响。【方法】以"先玉335"为供试玉米品种,通过人工接虫模拟二代玉米螟不同发生量为害玉米对产量损失的影响。【结果】随着接卵量增加,虫孔数和蛀孔隧道长度增加,玉米单穗粒重降低。单株虫孔数每增加1个,玉米产量损失率增加4.52%;隧道长度每增加10 cm,产量损失率增加8.34%。接卵量与玉米产量损失率的关系符合方程z=-10.0297+4.034 ln(x)。【结论】根据害虫经济阈值的定义,推算出二代玉米螟的防治指标为百株累积卵量12.8块,对二代玉米螟的防治决策具有重要指导作用。     

E3KARP mediates the association of ezrin and protein kinase A with the cystic fibrosis transmembrane conductance regulator in airway cells

Although it is generally recognized that cystic fibrosis transmembrane conductance regulator (CFTR) contains a PSD-95/Disc-large/ZO-1 (PDZ)-binding motif at its COOH terminus, the identity of the PDZ domain protein(s) that interact with CFTR is uncertain, and the functional impact of this interaction is not fully understood. By using human airway epithelial cells, we show that CFTR associates with Na(+)/H(+) exchanger (NHE) type 3 kinase A regulatory protein (E3KARP), an EBP50/NHE regulatory factor (NHERF)-related PDZ domain protein. The PDZ binding motif located at the COOH terminus of CFTR interacts preferentially with the second PDZ domain of E3KARP, with nanomolar affinity. In contrast to EBP50/NHERF, E3KARP is predominantly localized (>95%) in the membrane fractions of Calu-3 and T84 cells, where CFTR is located. Moreover, confocal immunofluorescence microscopy of polarized Calu-3 monolayers shows that E3KARP and CFTR are co-localized at the apical membrane domain. We also found that ezrin associates with E3KARP in vivo. Co-expression of CFTR with E3KARP and ezrin in Xenopus oocytes potentiated cAMP-stimulated CFTR Cl(-) currents. These results support the concept that E3KARP functions as a scaffold protein that links CFTR to ezrin. Since ezrin has been shown previously to function as a protein kinase A anchoring protein, we suggest that one function served by the interaction of E3KARP with both ezrin and CFTR is to localize protein kinase A in the vicinity of the R-domain of CFTR. Since ezrin is also an actin-binding protein, the formation of a CFTR.E3KARP.ezrin complex may be important also in stabilizing CFTR at the apical membrane domain of airway cells.     

虎纹捕鸟蛛的饲养与繁殖技术

本文简要介绍饲养、繁殖虎纹捕鸟蛛的技术,包括它的形态特征、生活习性、食物种类及饲养器具等,并介绍了在饲养和繁殖中应注意的一些问题。     

酿酒酵母S.cerevisiae高密度培养条件优化研究

考察了培养基组成和培养条件对酿酒酵母Saccharomyces cerevisiae发酵的影响。以TB培养基为初始培养基,通过正交实验设计优化培养基组成,确定了影响酵母细胞产量最主要的因素是葡萄糖,最适培养基组成为:酪蛋白胨15 g/L,酵母粉25 g/L,葡萄糖30 g/L,KH2PO42.4g/L,K2HPO4.3H2O 16.34 g/L。并确定了最佳培养条件:温度30℃,转速150 r/min。采用优化培养基及培养条件下进行发酵,菌液最高OD600值和细胞密度分别达15.82和2.03×108/mL,比优化前分别提高24.2%和22.0%。     

SO_2胁迫下桤木叶片硫含量及其生理响应

采用人工模拟熏气法,研究SO_2胁迫下桤木Alnus cremastogyne的生理响应机制及净化能力。结果表明:(1)桤木叶片在SO_2 4.29 mg·m~(-3)和8.57 mg·m~(-3)处理下分别在14 d和7 d时出现伤害症状;(2)随SO_2浓度增加,桤木叶片叶绿素总量、叶绿素a/b值和净光合速率呈下降趋势,其中净光合速率在SO_2 4.29 mg·m~(-3)处理下与CK无显著差异,而气孔导度、蒸腾速率和胞间CO_2浓度呈现先增后降趋势;(3)叶片脯氨酸、可溶性糖、可溶性蛋白质、丙二醛含量均随SO_2浓度升高而增加;(4)叶片过氧化物酶和超氧化物歧化酶活性随SO_2浓度增加而升高,过氧化氢酶活性呈先降低后升高的趋势;(5)桤木叶片硫含量随SO_2浓度增加呈递增趋势。桤木幼树能通过调节自身保护机制应对低浓度SO_2逆境胁迫并维持正常生长,可将其用作工厂附近或SO_2污染区域造林树种,以改善环境空气质量。