3,4-Dihydroxy-2-butanone 4-phosphate （DHBP） and GTP are the precursors for riboflavin biosynthesis. In this research, improving the precursor supply for riboflavin production was attempted by overexpressing ribB and...3,4-Dihydroxy-2-butanone 4-phosphate （DHBP） and GTP are the precursors for riboflavin biosynthesis. In this research, improving the precursor supply for riboflavin production was attempted by overexpressing ribB and engineering purine pathway in a riboflavin-producing Escherichia colt strain. Initially, ribB gene was overexpressed to increase the flux from ribulose 5-phosphate （Ru-5-P） to DHBP. Then ndk and grnk genes were overexpressed to enhance GTP supply. Subsequently, a R419L mutation was introduced into purA to reduce the flux from IMP to AMP. Finally, co-overexpression of mutant purF and prs genes further increased riboflavin production. The final strain RF18S produced 387.6 mg riboflavin · L-1 with a yield of 44.8 mg riboflavin per gram glucose in shake-flask fermentations. The final titer and yield were 72.2% and 55.6% higher than those of RF01S, respectively. It was concluded that simultaneously engineering the DHBP synthase and GTP biosynthetic pathway by rational metabolic engineering can efficiently boost riboflavin production in E. coll.展开更多
Primary biliary cirrhosis （PBC） is a progressive cho- lestatic liver disease characterized by the immune- mediated destruction of biliary epithelial cells in small intrahepatic bile ducts. The disease is characteriz...Primary biliary cirrhosis （PBC） is a progressive cho- lestatic liver disease characterized by the immune- mediated destruction of biliary epithelial cells in small intrahepatic bile ducts. The disease is characterized by circulating antimitochondrial antibodies （AMAs） as well as disease-specific antinuclear antibodies, cholestatic liver function tests, and characteristic histological fea- tures, including granulomas. A variety of organisms are involved in granuloma formation, of which mycobacte- ria are the most commonly associated. This has led to the hypothesis that mnycobacteria may be involved in the pathogenesis of PBC, along with other infectious agents. Additionally, AMAs are found in a subgroup of patients with rnycobacterial infections, such as lep- rosy and pulmonary tuberculosis. Antibodies against species-specific mycobacterial proteins have been re- ported in patients with PBC, but it is not clear whether these antibodies are specific for the disease. In addi- tion, data in support of the involvement of the role of molecular mimicry between rnycobacterial and human mitochondrial antigens as triggers of cross-reactive im- mune responses leading to the loss of immunological tolerance, and the induction of pathological features have been published. Thus, antibodies against myco- bacterial heat shock protein appear to cross-recognize AMA-specific autoantigens, but it is not clear whether these autoantibodies are mycobacterium-species-spe- cific, and whether they are pathogenic or incidental. The view that mycobacteria are infectious triggers of PBC is intriguing, but the data provided so far are not conclusive.展开更多
The paper proposes a novel hardware-based private information retrieval （HWPIR） protocol. By partially reshuffling previously accessed items in each round, instead of frequently reshuffling the whole database, the s...The paper proposes a novel hardware-based private information retrieval （HWPIR） protocol. By partially reshuffling previously accessed items in each round, instead of frequently reshuffling the whole database, the scheme makes better use of shuffled data copies and achieves the computation overhead at O（/N/K）,where N and k are the sizes of the database and secure storage respectively. For securestorage with moderate size, e.g. k = O（/N）, the overhead is 0（4/N）. The result is much better than the state-of-art schemes （as compared to e.g. O（log2N））. Without increasing response time and communication cost, the proposed protocol is truly practicable regardless of the database size. The security and preformance of the protocol is formally analyzed.展开更多
基金supported by National High-tech R&D Program of China [2012AA02A702, 2012AA022103]
文摘3,4-Dihydroxy-2-butanone 4-phosphate （DHBP） and GTP are the precursors for riboflavin biosynthesis. In this research, improving the precursor supply for riboflavin production was attempted by overexpressing ribB and engineering purine pathway in a riboflavin-producing Escherichia colt strain. Initially, ribB gene was overexpressed to increase the flux from ribulose 5-phosphate （Ru-5-P） to DHBP. Then ndk and grnk genes were overexpressed to enhance GTP supply. Subsequently, a R419L mutation was introduced into purA to reduce the flux from IMP to AMP. Finally, co-overexpression of mutant purF and prs genes further increased riboflavin production. The final strain RF18S produced 387.6 mg riboflavin · L-1 with a yield of 44.8 mg riboflavin per gram glucose in shake-flask fermentations. The final titer and yield were 72.2% and 55.6% higher than those of RF01S, respectively. It was concluded that simultaneously engineering the DHBP synthase and GTP biosynthetic pathway by rational metabolic engineering can efficiently boost riboflavin production in E. coll.
文摘Primary biliary cirrhosis （PBC） is a progressive cho- lestatic liver disease characterized by the immune- mediated destruction of biliary epithelial cells in small intrahepatic bile ducts. The disease is characterized by circulating antimitochondrial antibodies （AMAs） as well as disease-specific antinuclear antibodies, cholestatic liver function tests, and characteristic histological fea- tures, including granulomas. A variety of organisms are involved in granuloma formation, of which mycobacte- ria are the most commonly associated. This has led to the hypothesis that mnycobacteria may be involved in the pathogenesis of PBC, along with other infectious agents. Additionally, AMAs are found in a subgroup of patients with rnycobacterial infections, such as lep- rosy and pulmonary tuberculosis. Antibodies against species-specific mycobacterial proteins have been re- ported in patients with PBC, but it is not clear whether these antibodies are specific for the disease. In addi- tion, data in support of the involvement of the role of molecular mimicry between rnycobacterial and human mitochondrial antigens as triggers of cross-reactive im- mune responses leading to the loss of immunological tolerance, and the induction of pathological features have been published. Thus, antibodies against myco- bacterial heat shock protein appear to cross-recognize AMA-specific autoantigens, but it is not clear whether these autoantibodies are mycobacterium-species-spe- cific, and whether they are pathogenic or incidental. The view that mycobacteria are infectious triggers of PBC is intriguing, but the data provided so far are not conclusive.
文摘The paper proposes a novel hardware-based private information retrieval （HWPIR） protocol. By partially reshuffling previously accessed items in each round, instead of frequently reshuffling the whole database, the scheme makes better use of shuffled data copies and achieves the computation overhead at O（/N/K）,where N and k are the sizes of the database and secure storage respectively. For securestorage with moderate size, e.g. k = O（/N）, the overhead is 0（4/N）. The result is much better than the state-of-art schemes （as compared to e.g. O（log2N））. Without increasing response time and communication cost, the proposed protocol is truly practicable regardless of the database size. The security and preformance of the protocol is formally analyzed.
