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931.
Jingjing Jiang Youjian Yu Heng Dong Lina Yao Zhixian Zhang Jiashu Cao 《Molecular biology reports》2014,41(1):537-544
Brassica campestris Male Fertility 21 (BcMF21) was previously isolated from the flower buds of Chinese cabbage (Brassica campestris L. ssp. chinensis Makino, syn. B. rapa ssp. chinensis) and expressed specifically in tapetum and microspores during the meiosis stage and the uninucleate stage of microspore development. Here, we used antisense RNA technology to knock down the expression level of BcMF21 in B. campestris and analyzed the phenotype of the transgenic plants. Alexander staining and scanning electron microscope revealed sterility and exine deformities in the mature pollen grains of BcMF21 antisense RNA transgenic plants. The germination furrow of the BcMF21 antisense RNA transgenic pollen was covered by lipid like materials. The pollen tubes burst and could not grow normally in vitro. Therefore, we presented here BcMF21 might be an important gene for pollen development and germination. 相似文献
932.
Jingjing Guo Yan Zhang Lulu Ning Pingzu Jiao Huanxiang Liu Xiaojun Yao 《Biochimica et Biophysica Acta (BBA)/General Subjects》2014
Background
The formation of amyloid fibrils is associated with many age-related degenerative diseases. Nevertheless, the molecular mechanism that directs the nucleation of these fibrils is not fully understood.Methods
Here, we performed MD simulations for the NFGAILS motif of hIAPP associated with the type II diabetes to estimate the stabilities of hIAPP22–28 protofibrils with different sizes: from 2 to 16 chains. In addition, to study the initial self-assembly stage, 4 and 8 IAPP22–28 chains in explicit solvent were also simulated.Results
Our results indicate that the ordered protofibrils with no more than 16 hIAPP22–28 chains will be structurally stable in two layers, while one-layer or three-layer models are not stable as expected. Furthermore, the oligomerization simulations show that the initial coil structures of peptides can quickly aggregate and convert to partially ordered β-sheet-rich oligomers.Conclusions
Based on the obtained results, we found that the stability of an IAPP22–28 oligomer was not only related with its size but also with its morphology. The driving forces to form and stabilize an oligomer are the hydrophobic effects and backbone H-bond interaction. Our simulations also indicate that IAPP22–28 peptides tend to form an antiparallel strand orientation within the sheet.General significance
Our finding can not only enhance the understanding about potential mechanisms of hIAPP nuclei formation and the extensive structural polymorphisms of oligomers, but also provide valuable information to develop potential β-sheet formation inhibitors against type II diabetes. 相似文献933.
Yirong Li Xiang Huang Jingjing Li Ji Zeng Fan Zhu Wen Fan Lihua Hu 《Current microbiology》2014,69(2):121-126
Staphylococcus aureus has been shown to bind to human platelets through a variety of surface molecules, including serine-rich adhesin for platelets (SraP). The SraP mutant strain of S. aureus is significantly impaired in its ability to initiate infection compared with the wild strain. SraP is a cell wall-anchored, glycosylated protein. A previous study revealed that SecY2, Asp1, Asp2, Asp3, and SecA2 in the SraP operon were required for the efficient transport of glycosylated SraP from the cytoplasm to the bacterial cell surface. However, no glycosyltransferase (Gtf) was found to be involved in the glycosylation of SraP. In this study, SraP was found in all of the 55 clinical isolates of S. aureus using a real-time polymerase chain reaction assay. Sequence and phylogenetic analysis showed that GtfA and GtfB in the SraP operon were highly conserved in most of these clinical isolates. Conserved domains analysis revealed that both GtfA and GtfB contained a GT1_GtfA-like domain. Structural homology analysis inferred that they are both Gtfs. We then constructed an in vivo glycosylation system in Escherichia coli using SraP1–743 as the substrate and GtfA and GtfB as the Gtfs. Using this system, we found that GtfA and GtfB were the Gtfs that transferred the N-acetylglucosamine-containing oligosaccharides to the recombinant SraP1–743. Deletion of either one or both of the Gtfs abolished the glycosylation of SraP. In summary, GtfA and GtfB in the SraP operon are highly conserved in most clinical isolates of S. aureus, and both GtfA and GtfB are required for SraP glycosylation. 相似文献
934.
935.
936.
急性酒精中毒是一种有害的临床病理状态,短时间内摄入大量的乙醇,会造成多脏器功能损害,通常包括中枢神经抑制、呼吸循环功能障碍、代谢紊乱及免疫系统异常,严重者导致死亡.为了探索急性酒精中毒导致死亡的原因,采用腹腔注射的方法构建了重度急性酒精中毒小鼠模型,发现在模型早期(至迟0.5 h)高迁移率族蛋白1(high mobility group box-1 protein,HMGB1)已显著升高,体外实验也证实酒精导致细胞HMGB1释放,应用单克隆抗体阻断HMGB1有显著的保护作用,这种保护作用是通过降低损伤性炎症反应实现的.在此模型中发现,HMGB1在急性酒精中毒中有着重要的中介作用,调控急性系统性炎症反应,并决定了急性酒精中毒疾病的进程与结局. 相似文献
937.
938.
Biodegradation of cellulose involves synergistic action of the endoglucanases, exoglucanases and β-glucosidases in cellulase. However, the yield of glucose is limited by the lack of β-glucosidase to hydrolyze cellobiose into glucose. In this study, β-glucosidase as a supplemental enzyme along with cellulase are co-immobilized on a pHresponsive copolymer, poly (MAA-co-DMAEMA-co-BMA) (abbreviated PMDB, where MAA is α-methacrylic acid, DMAEMA is 2-dimethylaminoethyl methacrylate and BMA is butyl methacrylate). The thermal and storage stabilities of PMDB with immobilized enzymes are improved greatly, compared with those of free cellulase. Biodegradation of cellulose is carried out in a pH-responsive recyclable aqueous two-phase system composed of poly (AA-co- DMAEMA-co-BMA) (abbreviated PADB 3.8, where AA is acrylic acid) and PMDB. Insoluble substrate and PMDB with immobilized cellulase and β-glucosidase (Celluclast 1.5L FG and Novozyme 188, respectively) were biased to the bottom phase, while the product was partitioned to the top phase in the presence of 40 mM (NH4)2SO4. When the degradation reaction of cellulose is carried out with PMDB containing immobilized cellulase and β-glucosidase, the concentration of glucose reaches 4.331 mg/mL after 108 h. The yield of glucose is 50.25% after PMDB containing the immobilized enzymes is recycled five times. 相似文献
939.
Inoculated fermentation by selected indigenous yeast strains from a specific location could provide the wine with unique regional sensory characteristics. The identification and differentiation of local yeasts are the first step to understand the function of yeasts and develop a better strain-selection program for winemaking. The indigenous yeasts in five grape varieties, Chardonnay, Cabernet Franc, Cabernet Sauvignon, Marselan, and Merlot cultivated in Xiangning, Shanxi, China were investigated. Eight species of seven genera including Aureobasidium pullulans, Candida zemplinina, Hanseniaspora uvarum, Hanseniaspora occidentalis, Issatchenkia terricola, Metschnikowia pulcherrima, Pichia kluyveri, and Saccharomyces cerevisiae were identified using Wallerstein Laboratory Nutrient medium with sequencing of the 26S rDNA D1/D2 domain. H. uvarum and S. cerevisiae were the predominant species, while most non-Saccharomyces species were present in the whole fermentation process at different levels among the grape varieties. The genotypes of S. cerevisiae from each microvinification were determined by using interdelta sequence analysis. The 102 isolates showed eight different genotypes, and genotype III was the predominant genotype found. The distribution of S. cerevisiae strains during the fermentation of Marselan was also studied. Six genotypes were observed among the 92 strains with different genotypes of competitiveness at different sampling stages. Genotype V demonstrated the potential for organizing starter strains and avoiding inefficient fermentation. In general, this study explored the yeast species in the grapes grown in Xiangning County and provided important information of relationship of local yeast diversity and its regional wine sensory characteristics. 相似文献
940.
目的:建立利用荧光标记法检测氨肽酶抑制剂和肿瘤细胞结合的方法。方法:以异硫氰酸荧光素(FITC)标记氨肽酶N抑制剂LYRM03和Bestatin,制备荧光探针F1TC—LYRM03、FITC—Bestatin,应用荧光显微成像观察和流式细胞仪检测标记化合物FITC—LYRM03、FITC-Bestatin对肿瘤细胞的结合与氨肽酶N抑制活性的相关性。结果:化合物LYRM03和Bestatin具有肿瘤细胞的氨肽酶N抑制活性,荧光标记化合物FITC—LYRM03、FITC-Bestatin能与肿瘤细胞有不同程度的结合。结论:标记化合物FITC—LYRM03、FITC—Bestatin和肿瘤细胞的结合与对肿瘤细胞的氨肽酶N抑制活性相一致。 相似文献