Ataxin-3 Regulates Aggresome Formation of Copper-Zinc Superoxide Dismutase (SOD1) by Editing K63-linked Polyubiquitin Chains

Polyubiquitination of misfolded proteins, especially K63-linked polyubiquitination, is thought to be associated with the formation of inclusion bodies. However, it is not well explored whether appropriate editing of the different types of ubiquitin linkages by deubiquitinating enzymes (DUBs) affects the dynamics of inclusion bodies. In this study, we report that a specific DUB, ataxin-3, is required for the efficient recruitment of the neurodegenerative disease-associated protein copper-zinc superoxide dismutase (SOD1) to aggresomes. The overexpression of ataxin-3 promotes mutant SOD1 aggresome formation by trimming K63-linked polyubiquitin chains. Moreover, knockdown of ataxin-3 decreases mutant SOD1 aggresome formation and increases cell death induced by mutant SOD1. Thus, our data suggest that the sequestration of misfolded SOD1 into aggresomes, which is driven by ataxin-3, plays an important role in attenuating protein misfolding-induced cell toxicity.     

The Regulation and Function of Histone Methylation

Histones are wrapped around by genomic DNA to form nucleosomes which are the basic units of chromatin. In eukaryotes histones undergo various covalent modifications such as methylation, phosphorylation, acetylation, ubiquitination and ribosylation. Histone modifications play a fundamental role in the epigenetic regulation of gene expression in multicellular eukaryotes. Histone methylation is one of the most important modifications occurring on Lysine (K) and Arginine (R) residues of histones, dynamically regulated by histone methyltransferases and demethylases. Identifications of such histone modification enzymes and to study how they work are the most fundamental questions needs to be answered. Uncovering the regulation and functions of the various histone methylation enzymes will help us to better understand the epigenetic code. This review summarizes the regulation of histone methyltransferases activity, the recruitment of methyltransferases and the distribution patterns and function of histone methylations.     

肝癌细胞系差异性表达的糖结合蛋白研究

糖结合蛋白(glycan-binding protein,GBP)在细胞生命周期中扮演着重要角色,如细胞识别、运输、免疫、代谢、增殖分化及细胞间的相互作用等.目前,对GBP的改变对细胞生物过程产生影响的研究甚少.本研究用糖芯片技术对肝癌细胞系Hep G2和正常肝细胞系L02表达的GBP进行研究;糖细胞化学验证确定差异表达GBP在肝癌细胞系中的变化和分布.结果显示,8种糖探针(如SL、LNT和Gal NAc等)和5种糖探针(如Man、Man-9-Glycan,Xyl等)分别对应的GBP在Hep G2细胞中表达上调或下调.糖细胞化学结果显示:Gal NAc识别的GBPs主要表达在Hep G2的胞膜、中央胞质、核周胞质区域,而在L02的相同区域表达减弱;Neu Ac识别的GBPs主要表达在L02的胞膜区及核周胞质区,而在Hep G2细胞的相同区域表达减弱.这些数据为寻找新的肝癌发病机制和抗肿瘤策略提供了有用信息.     

An efficient cloning of DNA fragments by a method based on uracil-DNA glycosylase and endonuclease IV

We introduced a novel method to clone random DNA fragments independent of ligation reaction. The method involves the generation of long protruding ends on PCR amplification DNA. Both oligonucleotides used for the amplification of the vector DNA carried one uracil residue at the tenth position from the 5′ end and this made the creation of the 3′ protruding ends of linearized vector possible by uracil-DNA glycosylase (UDG) and endonuclease IV (Endo IV). 76 groups of annealed oligonucleotides that had ten-nucleotides protruding at 3′-end, which were complementary to those at 3′-end of the linearized vector, were designed. The linearized vector and the annealed oligonucleotide were mixed together to transform E.coli directly without ligation reaction. The number of the clone that grew on the plates had been demonstrated to reach 1 × 10⁵ transformants/μg and 96.1% of transformants harbored the cloned fragments. From the results of transformation, we can confirm that the efficiency of the creation of 3′ protruding ends in our method is high and our cloning method is benefit to produce recombinants easily and efficiently.     

东北地区玉米适应气候变化措施对生产潜力的影响

为探求东北玉米未来如何更好地适应气候变化,本研究采用抗逆品种和推迟播种期两种适应措施,结合区域气候模式模拟的2010-2099年间RCP4.5、RCP8.5两种浓度路径逐日气象资料,分析了不同气候变化情景下东北玉米适应措施的生产潜力变化.结果表明: 2010-2099年间,东北区玉米气候生产潜力的空间分布特征基本为东南向西北减小的趋势,RCP4.5情景下东北玉米生产潜力高于RCP8.5情景,且RCP8.5情景出现极低值年份明显多于RCP4.5情景.所有抗逆品种的玉米生产潜力均高于原有品种,在RCP4.5情景下,耐高温品种的玉米生产潜力更高,在RCP8.5情景下,耐旱品种表现更好,双耐(耐高温、耐旱)品种的玉米生产潜力在2种气候变化情景下均最高.RCP4.5情景下,推迟播种均出现增产情况,其中,推迟30~40 d播种的玉米增产率达到最大;RCP8.5情景下,部分地区出现减产情况.说明适当推迟播种期有利于提高玉米气候生产潜力,但地区间存在差异.     

长鞘卷叶甲生物学特性及防治研究

长鞘卷叶甲Leptispa longipennis(Gestro)是为害绿竹等丛生竹的新害虫,该虫在福建永定一年发生1代,以成虫在卷起的竹叶内越冬。翌年4月上旬开始交尾产卵,卵期10无;5月中旬开始化蛹,蛹期8无：5月中下旬第一代成虫开始羽化。以幼虫及成虫在卷起的竹叶内取食及繁殖。在对其生物学特性进行系统研究的基础上,找到了该虫生活史中的薄弱环节,提出了在7月份新羽化成虫在卷起的竹叶内取食盛期喷洒灭多粉、1605粉荆;初孵化幼虫喷洒白僵菌粉剂、25%灭幼脲粉剂、灭多粉粉荆、1605粉剂的防治技术。     

Solvent-free enzymatic synthesis of 1,3-diconjugated linoleoyl glycerol optimized by response surface methodology

An operation mode with N(2) bubbling under vacuum was employed for the solvent-free synthesis of 1,3-diconjugated linoleoyl glycerol (1,3-dCLG) from conjugated linoleic acid (CLA) catalyzed by Novozym 435. The response surface methodology (RSM) was adopted for the optimization of the reaction conditions with five major factors (incubation time, temperature, enzyme load, substrate mole ratio, and system vacuum) and three responses (CLA conversion, 1,3-dCLG yield, and acyl migration). Two sets of optimal conditions were recommended. Validation of the RSM model was verified by the good agreement between the experimental and the predicted values of 1,3-dCLG yield. Under the optimal conditions, the yield of 1,3-dCLG up to 93% was obtained. The reaction was scaled up to a production level of 100 g of 1,3-dCLG at a yield of 90.7%, indicating a promising feature of the technology in industrial applications.     

Nicotianamine,a Novel Enhancer of Rice Iron Bioavailability to Humans

Background

Polished rice is a staple food for over 50% of the world''s population, but contains little bioavailable iron (Fe) to meet human needs. Thus, biofortifying the rice grain with novel promoters or enhancers of Fe utilization would be one of the most effective strategies to prevent the high prevalence of Fe deficiency and iron deficiency anemia in the developing world.

Methodology/Principal Findings

We transformed an elite rice line cultivated in Southern China with the rice nicotianamine synthase gene (OsNAS1) fused to a rice glutelin promoter. Endosperm overexpression of OsNAS1 resulted in a significant increase in nicotianamine (NA) concentrations in both unpolished and polished grain. Bioavailability of Fe from the high NA grain, as measured by ferritin synthesis in an in vitro Caco-2 cell model that simulates the human digestive system, was twice as much as that of the control line. When added at 1∶1 molar ratio to ferrous Fe in the cell system, NA was twice as effective when compared to ascorbic acid (one of the most potent known enhancers of Fe bioavailability) in promoting more ferritin synthesis.

Conclusions

Our data demonstrated that NA is a novel and effective promoter of iron utilization. Biofortifying polished rice with this compound has great potential in combating global human iron deficiency in people dependent on rice for their sustenance.     

ITE and TCDD Differentially Regulate the Vascular Remodeling of Rat Placenta via the Activation of AhR

Vascular remodeling in the placenta is essential for normal fetal development. The previous studies have demonstrated that in utero exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, an environmental toxicant) induces the intrauterine fetal death in many species via the activation of aryl hydrocarbon receptor (AhR). In the current study, we compared the effects of 2-(1′H-indole-3′-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE) and TCDD on the vascular remodeling of rat placentas. Pregnant rats on gestational day (GD) 15 were randomly assigned into 5 groups, and were exposed to a single dose of 1.6 and 8.0 mg/kg body weight (bw) ITE, 1.6 and 8.0 µg/kg bw TCDD, or an equivalent volume of the vehicle, respectively. The dams were sacrificed on GD20 and the placental tissues were gathered. The intrauterine fetal death was observed only in 8.0 µg/kg bw TCDD-exposed group and no significant difference was seen in either the placental weight or the fetal weight among all these groups. The immunohistochemical and histological analyses revealed that as compared with the vehicle-control, TCDD, but not ITE, suppressed the placental vascular remodeling, including reduced the ratio of the placental labyrinth zone to the basal zone thickness (at least 0.71 fold of control), inhibited the maternal sinusoids dilation and thickened the trophoblastic septa. However, no marked difference was observed in the density of fetal capillaries in the labyrinth zone among these groups, although significant differences were detected in the expression of angiogenic growth factors between ITE and TCDD-exposed groups, especially Angiopoietin-2 (Ang-2), Endoglin, Interferon-γ (IFN-γ) and placenta growth factor (PIGF). These results suggest ITE and TCDD differentially regulate the vascular remodeling of rat placentas, as well as the expression of angiogenic factors and their receptors, which in turn may alter the blood flow in the late gestation and partially resulted in intrauterine fetal death.