LEW3, encoding a putative α‐1,2‐mannosyltransferase (ALG11) in N‐linked glycoprotein,plays vital roles in cell‐wall biosynthesis and the abiotic stress response in Arabidopsis thaliana

N‐linked glycosylation is an essential protein modification that helps protein folding, trafficking and translocation in eukaryotic systems. The initial process for N‐linked glycosylation shares a common pathway with assembly of a dolichol‐linked core oligosaccharide. Here we characterize a new Arabidopsis thaliana mutant lew3 (leaf wilting 3), which has a defect in an α‐1,2‐mannosyltransferase, a homolog of ALG11 in yeast, that transfers mannose to the dolichol‐linked core oligosaccharide in the last two steps on the cytosolic face of the ER in N‐glycan precursor synthesis. LEW3 is localized to the ER membrane and expressed throughout the plant. Mutation of LEW3 caused low‐level accumulation of Man₃GlcNAc₂ and Man₄GlcNAc₂ glycans, structures that are seldom detected in wild‐type plants. In addition, the lew3 mutant has low levels of normal high‐mannose‐type glycans, but increased levels of complex‐type glycans. The lew3 mutant showed abnormal developmental phenotypes, reduced fertility, impaired cellulose synthesis, abnormal primary cell walls, and xylem collapse due to disturbance of the secondary cell walls. lew3 mutants were more sensitive to osmotic stress and abscisic acid (ABA) treatment. Protein N‐glycosylation was reduced and the unfolded protein response was more activated by osmotic stress and ABA treatment in the lew3 mutant than in the wild‐type. These results demonstrate that protein N‐glycosylation plays crucial roles in plant development and the response to abiotic stresses.     

Design and synthesis of 4-aryl-4-oxobutanoic acid amides as calpain inhibitors

The involvement of μ-calpain in neurological disorders, such as stroke and Alzheimer’s disease has attracted considerable interest in the use of calpain inhibitors as therapeutic agents. 4-Aryl-4-oxobutanoic acid amide derivatives 4 were designed as acyclic variants of μ-calpain inhibitory chromone and quinolinone derivatives. Of the compounds synthesized, 4c-2, which possesses a 2-methoxymethoxy group at the phenyl ring and a primary amide at the warhead region most potently inhibited μ-calpain (IC₅₀ = 0.34 μM). Our findings suggest that the 4-aryl-4-oxobutanoic acid amide derivatives should be considered as a new family of μ-calpain inhibitors.     

Dynamic kinetic asymmetric transfer hydrogenation of racemic 2,4-diaryl-2,3-dihydrobenzo[b][1,4]diazepines catalyzed by chiral phosphoric acids

Dynamic kinetic Transfer hydrogenation reaction of 2-methyl-2,4-diaryl-2,3-dihydrobenzo[b][1,4]diazepines, using phosphoric acids as catalysts and Hantzsch ester as hydride source, has been studied. A 3,3′-H8-binol derived phosphoric acid has been identified the optimal chiral catalyst for this transformation, affording 1,3-diamine derivatives with up to 8/1 dr, 86% ee and 94% ee for the major and minor diastereomers, respectively.     

Inhibitors of HIV-1 attachment. Part 4: A study of the effect of piperazine substitution patterns on antiviral potency in the context of indole-based derivatives

4-Fluoro- and 4-methoxy-1-(4-benzoylpiperazin-1-yl)-2-(1H-indol-3-yl)ethane-1,2-dione (2 and 3, respectively) have been characterized as potent inhibitors of HIV-1 attachment that interfere with the interaction of viral gp120 with the host cell receptor CD4. As part of an effort to understand fundamental aspects of this pharmacophore, discovered originally using a high throughput cell-based screen, modification and substitution of the piperazine ring was examined in the context of compounds 6a–ah. The piperazine ring was shown to be a critical element of the HIV-1 attachment inhibiting pharmacophore, acting as a scaffold to deploy the indole glyoxamide and benzamide in a topographical relationship that complements the binding site on gp120.     

BRCA1基因在人食管癌中的表达

目的本研究利用组织芯片检测BRCA1基因在人食管癌中的表达与食管癌的生长、分化和转移等临床特征的关系,期望找到BRCA1与食管癌发生、发展的关系。方法收集48例食管癌患者标本,分别取其肿瘤组织、癌前病变组织及正常组织制成组织微阵列,免疫组织化学SP法检测BRCA1蛋白的表达,分析BRCA1在各种组织的表达特点及其与肿瘤的关系。选择其中10例患者的上述组织的新鲜标本,采用Western blot检测BRCA1蛋白的表达。结果免疫组织化学结果显示,BRCA1在肿瘤组织阳性占70.50%,癌前组织阳性占43.10%,正常组织阳性占39.00%,食管癌组织与癌前病变组织、食管癌组织与正常组织相比BRCA1的表达均存在显著差异（P〈0.01）。BRCA1的表达与食管癌的病理分化有统计学上的差异（P〈0.05）。Western blot显示,BRCA1在食管癌肿瘤组织、癌前病变组织及正常组织中表达量依次降低,差异具有统计学意义（P〈0.05）;BRCA1在高、中、低分化程度的食管癌组织中表达量依次降低,差异具有统计学意义（P〈0.05）。结论BRCA1与食管癌发生发展有关,BRCA1的表达与食管癌的分化呈正相关。     

决策失利后情绪的接近性效应与ERP证据

接近性效应是一种决策失利后的情绪体验受实际结果与意愿结果的接近程度影响的现象. 本研究采用事件相关电位(ERP)研究技术, 运用抽奖赌博任务实验范式考察了这一效应. 行为评定结果表明, 被试在实际结果与意愿结果很接近时更可能体验到后悔情绪, 且体验强度较高, 在实际结果与意愿结果相差较远时更可能体验到失望情绪, 且体验强度较低. 脑电结果显示, 接近性主效应在P300上表现显著, 同时, 与接近性的中、远水平条件相比, 近水平条件诱发一个新异晚正成分(LPC). 决策失利后实际结果与意愿结果接近程度不仅影响决策后情绪的性质, 而且调节情绪的强度.     

Replication Protein A (RPA1a) Is Required for Meiotic and Somatic DNA Repair But Is Dispensable for DNA Replication and Homologous Recombination in Rice

Replication protein A (RPA), a highly conserved single-stranded DNA-binding protein in eukaryotes, is a stable complex comprising three subunits termed RPA1, RPA2, and RPA3. RPA is required for multiple processes in DNA metabolism such as replication, repair, and homologous recombination in yeast (Saccharomyces cerevisiae) and human. Most eukaryotic organisms, including fungi, insects, and vertebrates, have only a single RPA gene that encodes each RPA subunit. Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa), however, possess multiple copies of an RPA gene. Rice has three paralogs each of RPA1 and RPA2, and one for RPA3. Previous studies have established their biochemical interactions in vitro and in vivo, but little is known about their exact function in rice. We examined the function of OsRPA1a in rice using a T-DNA insertional mutant. The osrpa1a mutants had a normal phenotype during vegetative growth but were sterile at the reproductive stage. Cytological examination confirmed that no embryo sac formed in female meiocytes and that abnormal chromosomal fragmentation occurred in male meiocytes after anaphase I. Compared with wild type, the osrpa1a mutant showed no visible defects in mitosis and chromosome pairing and synapsis during meiosis. In addition, the osrpa1a mutant was hypersensitive to ultraviolet-C irradiation and the DNA-damaging agents mitomycin C and methyl methanesulfonate. Thus, our data suggest that OsRPA1a plays an essential role in DNA repair but may not participate in, or at least is dispensable for, DNA replication and homologous recombination in rice.In a population of organisms, it is crucial to maintain the integrity of genome among individuals as well as shuffle genetic information at the population level. To maintain such genetic integrity, cells have evolved elaborate mechanisms such as base excision repair (BER; Hegde et al., 2008), nucleotide excision repair (NER; Shuck et al., 2008), homologous recombination (HR; Li and Heyer, 2008) repair, and nonhomologous end joining (Weterings and Chen, 2008) pathways to repair diverse types of DNA damage. To allow for variation, however, organisms utilize meiosis to shuffle genetic material so as to increase genetic diversity in populations and in the species.DNA double-strand break (DSB) repair is particularly important in maintaining the integrity of genome among individuals and shuffling genetic information among population, because DSBs are generated not only in meiotic cells but also from the action of certain endogenous or exogenous DNA-damaging agents and during repair of other kinds of DNA lesions by NER or BER (West et al., 2004; Bleuyard et al., 2006). The past decade has witnessed an explosion in understanding of this complex process by using yeast (Saccharomyces cerevisiae) as a model organism (Aylon and Kupiec, 2004). Cells can repair DSBs by the relatively inaccurate process of rejoining the two broken ends directly (i.e. nonhomologous end joining) or much more accurately by HR (Bleuyard et al., 2006; Wyman and Kanaar, 2006). These two pathways appear to compete for DSBs, but the balance between them differs widely among species, between different cell types of a single species, and during different cell cycle phases of a single cell type (Shrivastav et al., 2008). According to the current general model for meiotic DSB repair (Bishop and Zickler, 2004; Ma, 2006; San Filippo et al., 2008), when DSBs occur the MRN complex (composed of Mre11, Rad50, and NBS1) resects the DSBs to generate 5′→3′ single-stranded DNA (ssDNA) ends. Subsequently, the replication protein A (RPA) protein complex binds to the ssDNA ends to protect them from attack by endogenous exonucleases; then, in concert with catalysis by Rad52, Rad55, and Rad57, the recombinase Rad51 displaces RPA, resulting in the generation of a Rad51 nucleoprotein filament that in turn catalyzes the search and invasion into the recombination partner with the help of proteins belonging to the RAD52 epistasis group to form a D loop that accompanies DNA synthesis. Thereafter, at least two competing mechanisms may come into play. One is the DSB repair pathway, in which the capture of the second DSB end and additional DNA synthesis result in an intermediate that harbors two Holliday junctions. The subsequent resolution of Holliday junctions results in the formation of crossovers. Alternatively, in the synthesis-dependent strand annealing pathway, the D loop dissociates and the invading single strand with newly synthesized DNA reanneals with the other DSB end, followed by gap-filling DNA synthesis and ligation, forming only noncrossover products (Ma, 2006; San Filippo et al., 2008).RPA is comprised of three subunits of RPA1, 2, and 3, alternatively termed as RPA70, 32, and 14, respectively, according to their apparent M_rs (Wold, 1997; Iftode et al., 1999). RPA is an essential protein in various DNA metabolism pathways such as DNA replication, repair, and HR (Wold, 1997; Iftode et al., 1999). In these pathways, the most basic function of RPA is binding to ssDNA to protect it from exonucleases, and its general roles in DNA metabolism depend on its interactions with other proteins in various pathways (Wold, 1997; Iftode et al., 1999). For example, in human NER pathway, RPA binds to damaged DNA and interacts with xeroderma pigmentosum damage-recognition protein, XPA, in the damage recognition step, and then the endonucleases XPG and ERCC1/XPF are recruited to the RPA-XPA-damaged DNA complex in the excision step (He et al., 1995). Interactions of RPA with those proteins are critical in this process (Wold, 1997; Iftode et al., 1999). A great deal of protein dynamics research has indicated that the interactions between RPA and other DNA-metabolism proteins are choreographed on the ssDNA to recruit the required protein present at the proper time (Fanning et al., 2006).Human, animals, and fungi have single copy for each subunit of RPA (http://www.ncbi.nlm.nih.gov/sutils/genom_table.cgi). Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa), however, have multiple genes for most RPA subunits (Ishibashi et al., 2006; Shultz et al., 2007). Most of them have not unveiled exact function up to now. To elucidate the molecular basis of meiosis in rice, we performed a large-scale screen for sterile mutants using our T-DNA insertion mutant library (Wu et al., 2003). Previously, we reported the cloning of OsPAIR3, a novel gene required for homologous chromosome pairing and synapsis in rice (Yuan et al., 2009). Here we report the characterization of another sterile mutant with a T-DNA insertion in OsRPA1a. Our results indicate that OsRPA1a is essential for DNA repair but may play redundant roles in DNA replication and recombination in rice.     

Biological control of take-all in wheat by endophytic Bacillus subtilis E1R-j and potential mode of action

The bacterial strain E1R-j, isolated as an endophyte from wheat roots, exhibited high antifungal activity to Gaeumannomyces graminis var. tritici (Ggt). Strain E1R-j was identified as Bacillus subtilis based on morphological, physiological and biochemical methods as well as on 16S rDNA analysis. This strain inhibited mycelium growth in vitro of numerous plant pathogenic fungi, especially of Ggt, Coniothyrium diplodiella, Phomopsis sp. and Sclerotinia sclerotiorum. In greenhouse experiments, soil drenches with cell densities of 10⁶, 10⁹ and 10¹² CFU ml⁻¹ E1R-j reduced significantly take-all disease, caused by Ggt, in wheat seedling by 62.6%, 68.6% and 70.7%, respectively, compared to the inoculated control, 4 weeks after sowing. Growth parameters such as lengths and fresh weights of roots and shoots of Ggt-inoculated control plants were significantly lower compared to Ggt-inoculated and E1R-j treated plants. Field experiments in the season 2006/2007, heights of wheat plants in the Ggt inoculated plots were significantly reduced compared to the non inoculated treatments. Yield parameters such as kernels per head and thousand kernel weight (TKW) in inoculated control plants were lower compared to the other treatments. In the experimental year 2007/2008, independent treatments with the bacterial strain E1R-j and the fungicide Triadimefon reduced take-all disease in wheat roots by 55.3% and 61.9%, compared to the inoculated control plants. In this season plant height in inoculated control was significantly lower and also the yield parameters seeds per head and especially TKW were drastically reduced compared to the other treatments. E1R-j treatment alleviated the detrimental effects of take-all on grain yield parameters to a similar extent as Triadimefon application. SEM studies revealed that in the presence of E1R-j, hyphae of Ggt showed leakage, appeared ruptured, swollen and shriveled. Following root drench, strain E1R-j was able to colonize endophytically roots and leaves of wheat seedlings. While the population of the bacterial strain in wheat roots steadily increased from the second to the fourth leaf stage, in the leaf tissue the population of the strain rapidly declined. TEM studies also showed that cells of E1R-j were present in roots of wheat seedlings and effectively retarded infection and colonization of Ggt in root tissue; suppression of Ggt by E1R-j was accompanied by disintegration of hyphal cytoplasm. In addition, in the presence of E1R-j cells in Ggt-infected root tissue morphological defense reactions were triggered such as formation of wall appositions and papillae. The results presented indicate that the endophytic strain E1R-j of B. subtilis meets demands required for biocontrol of take-all.     

LRP1 controls intracellular cholesterol storage and fatty acid synthesis through modulation of Wnt signaling

The low-density lipoprotein receptor-related protein LRP1 is a cell surface receptor with functions in diverse physiological pathways, including lipid metabolism. Here we show that LRP1-deficient fibroblasts accumulate high levels of intracellular cholesterol and cholesteryl-ester when stimulated for adipocyte differentiation. We demonstrate that LRP1 stimulates a canonical Wnt5a signaling pathway that prevents cholesterol accumulation. Moreover, we show that LRP1 is required for lipolysis and stimulates fatty acid synthesis independently of the noradrenergic pathway, through inhibition of GSK3beta and its previously unknown target acetyl-CoA carboxylase (ACC). As a result of ACC inhibition, mature LRP1-deficient adipocytes of adult mice are hypotrophic, and lower uptake of fatty acids into adipose tissue leads to their redistribution to the liver. These results establish LRP1 as a novel integrator of adipogenic differentiation and fat storage signals.