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251.
瑞氏木霉木糖醇脱氢酶基因的分离与鉴定 总被引:2,自引:0,他引:2
将在木聚糖上生长的瑞氏木霉(Trichoderma reesei)RutC-30的cDNA文库全部质粒转化已携带有毕赤氏酵(Pithia stipitis)木糖还原酶基因的重组酿酒酵母(Saccharomycescerevisiae)菌株H475,在H475中构建了瑞氏木霉的cDNA表达亚文库。在以木糖为唯一碳源的选择性酵母合成培养基上,从该亚文库中筛选到瑞氏木霉木糖醇脱氢酶cDNA基因.该基因片段长为1.3kb。Southern、Norhern印迹杂交分析和蛋白质凝胶电泳结果表明该基因确实来源于瑞氏木霉,所编码蛋白质分子量约为40kDa。携带有毕赤氏酵母木糖还原酶和瑞氏木霉木糖醇脱氢酶基因的重组酵母能够在以木糖为唯一碳源的培养基上生长,并能将90%以上的木糖转化为木糖醇、乙醇和其它副产品。 相似文献
252.
乙肝病毒表面抗原preS1与人肿瘤坏死因子α融合基因的表达 总被引:6,自引:0,他引:6
用PCR法获得了HBsAgpreS1(1-65)肽段基因,将该基因融合在肿瘤坏死因子(hTNFα)之后,插入表达载体PSB-92中,使融合基因的5′端直接置于大肠肝菌PL启动子下游,采用30℃培养,42℃诱导,获得了TNF与preS1(1-65)融合蛋白的表达产物。SDS-PAGE电泳显示表达产物为25kD,约占细菌总蛋白的35%。表达产物经Westernblot验证,能分别特异地与hTNFα抗体与preS1抗体结合,稀释复性后,该融合蛋白还具有TNF的生理功能(对L929细胞的细胞毒活性)。经DNA序列测定,preS1(1-65)肽基因正确地融合在hTNFα基因之后。该结果提供了一种制备preS1的新方法,为进一步开展治疗肝癌和乙肝的导向药物打下基础。 相似文献
253.
The ultrastructure of synergids of watermelon (Citrullus Lanatus L.) was investigated using transmission electron microscopy at following stages of embryo sacs: 1. Unpollination, on the first flowering day. 2. Unpollination, on 2nd day after anthesis (DAA). 3. Fertilization, on DAA 2. The synergids with distinct filiform apparatus at the micropylar end have abundant organelle, such as mitochondria, endoplasmic reticulum, and plastids in cytoplasm, which indicate that they are active on the first flowering day. No wall is present at the chalazal part of synergid, and there are some flocculent materials and vesicles in the spaces of cytoplasma membranes among synergid, egg cell and central cell in embryo sacs at the first and the second stages. On DAA 2, in unpollinated embryo sacs, the central large vacuole of synergid is divided into several smaller ones and the starch grains decrease in cytoplasm. There is no newly synthesized wall at the chalazal end of persistent synergid in fertilized embryo sacs. The contents of degenerated synergid, in the form of electron dense granules, are located in the wide space among central cell, zygote and persistent synergid, and some of them migrate into central cell through cytoplasma membrane. Therefore, it is deduced that the contents of synergid might serve as a nutrient supplement to the development of endosperm, but not embryo. 相似文献
254.
Platelet-derived growth factor C (PDGF-C), a novel growth factor that binds to PDGF alpha and beta receptor 总被引:12,自引:0,他引:12
Gilbertson DG Duff ME West JW Kelly JD Sheppard PO Hofstrand PD Gao Z Shoemaker K Bukowski TR Moore M Feldhaus AL Humes JM Palmer TE Hart CE 《The Journal of biological chemistry》2001,276(29):27406-27414
We have characterized platelet-derived growth factor (PDGF) C, a novel growth factor belonging to the PDGF family. PDGF-C is a multidomain protein with the N-terminal region homologous to the extracellular CUB domain of neuropilin-1, and the C-terminal region consists of a growth factor domain (GFD) with homology to vascular endothelial growth factor (25%) and PDGF A-chain (23%). A serum-sensitive cleavage site between the two domains allows release of the GFD from the CUB domain. Competition binding and immunoprecipitation studies on cells bearing both PDGF alpha and beta receptors reveal a high affinity binding of recombinant GFD (PDGF-CC) to PDGF receptor-alpha homodimers and PDGF receptor-alpha/beta heterodimers. PDGF-CC exhibits greater mitogenic potency than PDGF-AA and comparable or greater mitogenic activity than PDGF-AB and PDGF-BB on several mesenchymal cell types. Analysis of PDGF-CC in vivo in a diabetic mouse model of delayed wound healing showed that PDGF-CC significantly enhanced repair of a full-thickness skin excision. Together, these studies describe a third member of the PDGF family (PDGF-C) as a potent mitogen for cells of mesenchymal origin in in vitro and in vivo systems with a binding pattern similar to PDGF-AB. 相似文献
255.
256.
Photosynthetic activity and proteomic analysis highlights the utilization of atmospheric CO2 by Ulva prolifera (Chlorophyta) for rapid growth 下载免费PDF全文
Free‐floating Ulva prolifera is one of the causative species of green tides. When green tides occur, massive mats of floating U. prolifera thalli accumulate rapidly in surface waters with daily growth rates as high as 56%. The upper thalli of the mats experience environmental changes such as the change in carbon source, high salinity, and desiccation. In this study, the photosynthetic performances of PSI and PSII in U. prolifera thalli exposed to different atmospheric carbon dioxide (CO2) levels were measured. Changes in photosynthesis within salinity treatments and dehydration under different CO2 concentrations were also analyzed. The results showed that PSII activity was enhanced as CO2 increased, suggesting that CO2 assimilation was enhanced and U. prolifera thalli can utilize CO2 in the atmosphere directly, even when under moderate stress. In addition, changes in the proteome of U. prolifera in response to salt stress were investigated. Stress‐tolerance proteins appeared to have an important role in the response to salinity stress, whereas the abundance of proteins related to metabolism showed no significant change under low salinity treatments. These findings may be one of the main reasons for the extremely high growth rate of free‐floating U. prolifera when green tides occur. 相似文献
257.
CDK phosphorylates the polarisome scaffold Spa2 to maintain its localization at the site of cell growth 下载免费PDF全文
Hao Zou Guisheng Zeng Jiaxin Gao Yanming Wang Ada Hang‐Heng Wong Yue Wang 《Molecular microbiology》2016,101(2):250-264
Polarisome is a protein complex that plays an important role in polarized growth in fungi by assembling actin cables towards the site of cell growth. For proper morphogenesis, the polarisome must localize to the right place at the right time. However, the mechanisms that control polarisome localization remain poorly understood. In this study, using the polymorphic fungus Candida albicans as a model, we have discovered that the cyclin‐dependent kinase (CDK) Cdc28 phosphorylates the polarisome scaffold protein Spa2 to govern polarisome localization during both yeast and hyphal growth. In a yeast cell cycle, Cdc28‐Clb2 phosphorylates Spa2 and controls the timing of polarisome translocation from the bud tip to the bud neck. And during hyphal development, Cdc28‐Clb2 and the hyphal‐specific Cdc28‐Hgc1 cooperate to enhance Spa2 phosphorylation to maintain the polarisome at the hyphal tip. Blocking the CDK phosphorylation causes premature tip‐to‐neck translocation of Spa2 during yeast growth and inappropriate septal localization of Spa2 in hyphae and abnormal hyphal morphology under certain inducing conditions. Together, our results generate new insights into the mechanisms by which fungi regulate polarisome localization in the control of polarized growth. 相似文献
258.
Zhaozhou?Li Xiujin?ChenEmail author Zhili?Li Daomin?Li Yao?Wang Hongli?Gao Li?Cao Yuze?Hou Songbiao?Li Jianping?Liang 《Biotechnology letters》2016,38(6):983-989
Objectives
To improve cellulase production and activity, Trichoderma viride GSICC 62010 was subjected to mutation involving irradiation with an electron beam and subsequently with a 12C6+-ion beam.Results
Mutant CIT 626 was the most promising cellulase producer after preliminary and secondary screening. Soluble protein production and cellulase activities were increased mutifold. The optimum temperature, pH and culture time for the maximum cellulase production of the selected mutant were 35 °C, pH 5 and 6 days. The highest cellulase production was obtained using wheat bran. The prepared cellulases from T. viride CIT 626 had twice the hydrolytic performance with sawdust (83 %) than that from the parent strain (42.5 %). Furthermore, molecular studies demonstrated that there were some key mutation sites suggesting that some amino acid changes in the protein caused by base mutations had led to the enhanced cellulase production and activity.Conclusions
Mutagenesis with electron and 12C6+-ion beams could be developed as an effective tool for improvement of cellulase producing strains.259.
Bing Zhu Tierra R. Farris Sarah L. Milligan Haosi Chen Ruijuan Zhu Aailing Hong Xiaochuan Zhou Xiaolian Gao Jere W. McBride 《Biochemistry and Biophysics Reports》2016
SUMOylation and ubiquitination are two essential post translational modifications (PTMs) involved in the regulation of important biological processes in eukaryotic cells. Identification of ubiquitin (Ub) and small ubiquitin-related modifier (SUMO)-conjugated lysine residues in proteins is critical for understanding the role of ubiquitination and SUMOylation, but remains experimentally challenging. We have developed a powerful in vitro Ub/SUMO assay using a novel high density peptide array incorporated within a microfluidic device that allows rapid identification of ubiquitination and SUMOylation sites on target proteins. We performed the assay with a panel of human proteins and a microbial effector with known target sites for Ub or SUMO modifications, and determined that 80% of these proteins were modified by Ub or specific SUMO isoforms at the sites previously determined using conventional methods. Our results confirm the specificity for both SUMO isoform and individual target proteins at the peptide level. In summary, this microfluidic high density peptide array approach is a rapid screening assay to determine sites of Ub and SUMO modification of target substrates, which will provide new insights into the composition, selectivity and specificity of these PTM target sites. 相似文献
260.
Regulation and Methylation of Tumor Suppressor MiR-124 by Androgen Receptor in Prostate Cancer Cells
Prostate cancer (PCa) is the most frequently diagnosed cancer for men in the developed world. Androgen receptor signaling pathway plays an important role in prostate cancer progression. Recent studies show that microRNA miR-124 exerts a tumor suppressive function in prostate cancer. However, the relationship between AR and miR-124 is unclear. In the present study, we found a negative feedback loop between AR and miR-124 expression. On one hand, miR-124 was a positively regulated target gene of the AR, on the other hand, overexpression of miR-124 inhibited the expression of AR. In addition, we found that miR-124-2 and miR-124-3 promoters were hypermethylated in AR-negative PCa cells. Furthermore, overexpression of miR-124 inhibited proliferation rates and invasiveness capacity of PCa cells in vitro, and suppressed xenograft tumor growth in vivo. Taken together, our results support a negative feedback loop between AR and miR-124 expression. Methylation of miR-124-2 and miR-124-3 may serve as a biomarker for AR-negative PCa cells, and overexpression of miR-124 might be of potential therapeutic value for the treatment of PCa. 相似文献