Salicylate is a type of pollutant widely and persistently existed in environ- ment. Microbiological degradation of salicylate as one kind of biological remediation methods has the advantages of low cost, good effect a...Salicylate is a type of pollutant widely and persistently existed in environ- ment. Microbiological degradation of salicylate as one kind of biological remediation methods has the advantages of low cost, good effect and no secondary pollution, and also attracts wide attention both at home and abroad. Currently, many salicy- late-degrading bacteria are isolated and screened, while the molecular mechanism of salicylate metabolism is also worth deep research. The research about molecular mechanism of microorganism degradation was overviewed, various degrading path- ways including catechol meta-cleavage pathway and gentisate pathway were intro- duced, and the latest progress in regulating genes of salicylate degradation was summarized.展开更多
In this study,using a spontaneous emulsification/solvent extraction method,BCNU-loaded PLA nanoparticles (NPs) with small particle size and narrow size distribution have been acquired. The particle size of the NPs ran...In this study,using a spontaneous emulsification/solvent extraction method,BCNU-loaded PLA nanoparticles (NPs) with small particle size and narrow size distribution have been acquired. The particle size of the NPs ranged from 40~60 nm and 100~200 nm according to different requirements. SEM and TEM showed that the particle size considerably decreases with increasing emulsification concentration and decreasing PLA concentration and ratio of oil to water. The highest drug loading ratio and drug encapsulation efficiency of NPs were 5.63% and 33.45%. The results demonstrated that decrease of initial BCNU content resulted in a noticeably increased encapsulation yield. A thorough study in vitro showed that the drug could be steadily released from NPs for one week. In addition,drug-loaded NPs had higher antitumor activity,compared with free BCNU,and sustained drug release characteristics as well.展开更多
Ebola virus （EBOV） causes a highly lethal hemorrhagic fever syndrome in humans and has been associated with mortality rates of up to 91% in Zaire, the most lethal strain. Though the viral envelope glycoprotein （GP...Ebola virus （EBOV） causes a highly lethal hemorrhagic fever syndrome in humans and has been associated with mortality rates of up to 91% in Zaire, the most lethal strain. Though the viral envelope glycoprotein （GP） mediates widespread inflammation and cellular damage, these changes have mainly focused on alterations at the protein level, the role of microRNAs （miRNAs） in the molecular pathogenesis underlying this lethal disease is not fully understood. Here, we report that the miRNAs hsa-miR-1246, hsa-miR-320a and hsa-miR-196b-5p were induced in human umbilical vein endothelial cells （HUVECs） following expression of EBOV GP. Among the proteins encoded by predicted targets of these miRNAs, the adhesion-related molecules tissue factor pathway inhibitor （TFPI）, dystroglycan! （DAG1） and the caspase 8 and FADD-like apoptosis regulator （CFLAR） were significantly downregulated in EBOV GP-expressing HUVECs. Moreover, inhibition of hsa-miR-1246, hsa-miR-320a and hsa-miR-196b-5p, or overexpression of TFPI, DAG1 and CFLAR rescued the cell viability that was induced by EBOV GP. Our results provide a novel molecular basis for EBOV pathogenesis and may contribute to the development of strategies to protect against future EBOV pandemics.展开更多
The effects induced by streamwise conduction on the thermal characteristics of forced convection for single-phase liquid flow in rectangular microchannel heat sinks under imposed constant wall temperature have been st...The effects induced by streamwise conduction on the thermal characteristics of forced convection for single-phase liquid flow in rectangular microchannel heat sinks under imposed constant wall temperature have been studied. By employing the fin approach in the first law of analysis, models with and without streamwise conduction term in the energy equation were developed for hydrodynamically and thermally fully-developed flow under local thermal non-equilibrium for the solid and fluid phases. These two models were solved to obtain closed form analytical solutions for the fluid and solid temperature distributions and the analysis emphasized details of the variations induced by the streamwise conduction on the fluid temperature distributions. The effects of the Peclet number, aspect ratio, and thermal conductivity ratio on the thermal characteristics of forced convection in microchannel heat sinks were analyzed and discussed. This study reveals the conditions under which the effect of streamwise conduction is significant and should not be neglected in the forced convective heat transfer analysis of microchannel heat sinks.展开更多
Graphene oxide （GO） can be reduced to graphene in a normal aerobic setup under ambient conditions as mediated by microbial respiration of Shewanella cells. The microbially-reduced graphene （MRG） exhibited excellen...Graphene oxide （GO） can be reduced to graphene in a normal aerobic setup under ambient conditions as mediated by microbial respiration of Shewanella cells. The microbially-reduced graphene （MRG） exhibited excellent electrochemical properties. Extracellular electron transfer pathways at the cell/GO interface were systematically investigated, suggesting both direct electron transfer and electron mediators are involved in the GO reduction.展开更多
MicroRNAs, a class of small noncoding RNAs, play key roles in diverse biological and pathological processes. ER stress, resulting from the accumulation of unfolded or misfolded proteins in the ER lumen, is triggered b...MicroRNAs, a class of small noncoding RNAs, play key roles in diverse biological and pathological processes. ER stress, resulting from the accumulation of unfolded or misfolded proteins in the ER lumen, is triggered by various physiological events and pathological insults. Here, using RNA deep sequencing analysis, we found that the expression of some microRNAs was altered in HeLa and HEK293 cells under ER stress. Protein and RNA levels of DGCR8, Drosha, Exportin-5, Dicer, and Ago2 showed no significant alteration in ER-stressed cells, which suggested that the change in microRNA expression might not be caused by the microRNA biogenesis pathway but by other, unknown factors. Real-time PCR assays confirmed that hsa-miR-423-5p was up-regulated, whereas hsa-miR-221-3p and hsa-miR-452-5p were down-regulated, in both HeLa and HEK293 cells under ER stress. Luciferase activity and Western blot assays verified that CDKN1A was a direct target of hsa-miR-423-5p and that CDKN1B was a direct target of hsa-miR-221-3p and hsamiR-452-5p. We speculated that by regulating their targets, microRNAs might function cooperatively as regulators in the adaptive response to ER stress.展开更多
Natural products are often secondary metabolites in living organisms with a wide variety of biological activities. The diversification of their structures, aiming to the search for biologically active small molecules ...Natural products are often secondary metabolites in living organisms with a wide variety of biological activities. The diversification of their structures, aiming to the search for biologically active small molecules by expanding chemical and functional spaces, is a major area of current interest in synthetic chemistry. However, developing synthetic accessibility and efficiency often faces challenges associated with structural complexity. Synthetic biology has recently emerged and is promising to accomplish complex molecules; by contrast, the application to structural diversification of natural products relies on the understanding, development and utilization of compatible biosynthetic machinery. Here, we review the strategies primarily concerning the artificial evolution of microbial natural products whose biosynthesis features template enzymology, including ribosomaUy synthesized and post-translationally modified peptides as well as the assembly line-resultant polyketides, non-ribosomal peptides and hybrids. The establishment of these approaches largely facilitates the expansion of the molecular diversity and utility through bioengineering at different stages/levels of biosynthetic pathways.展开更多
文摘Salicylate is a type of pollutant widely and persistently existed in environ- ment. Microbiological degradation of salicylate as one kind of biological remediation methods has the advantages of low cost, good effect and no secondary pollution, and also attracts wide attention both at home and abroad. Currently, many salicy- late-degrading bacteria are isolated and screened, while the molecular mechanism of salicylate metabolism is also worth deep research. The research about molecular mechanism of microorganism degradation was overviewed, various degrading path- ways including catechol meta-cleavage pathway and gentisate pathway were intro- duced, and the latest progress in regulating genes of salicylate degradation was summarized.
文摘In this study,using a spontaneous emulsification/solvent extraction method,BCNU-loaded PLA nanoparticles (NPs) with small particle size and narrow size distribution have been acquired. The particle size of the NPs ranged from 40~60 nm and 100~200 nm according to different requirements. SEM and TEM showed that the particle size considerably decreases with increasing emulsification concentration and decreasing PLA concentration and ratio of oil to water. The highest drug loading ratio and drug encapsulation efficiency of NPs were 5.63% and 33.45%. The results demonstrated that decrease of initial BCNU content resulted in a noticeably increased encapsulation yield. A thorough study in vitro showed that the drug could be steadily released from NPs for one week. In addition,drug-loaded NPs had higher antitumor activity,compared with free BCNU,and sustained drug release characteristics as well.
基金supported by the National Natural Science Foundation of China(81230002,81300057,91019016,31361163004)National Basic Research Program of China(2012CB316503)+3 种基金Ministry of Health(201302017)Ministry of Science and Technology of China(2006AA02Z152)Program of Introducing Talents of Discipline to Universities(B08007)the support of the Science and Technology Commission of Shanghai Municipality(07pj14096)
文摘Ebola virus （EBOV） causes a highly lethal hemorrhagic fever syndrome in humans and has been associated with mortality rates of up to 91% in Zaire, the most lethal strain. Though the viral envelope glycoprotein （GP） mediates widespread inflammation and cellular damage, these changes have mainly focused on alterations at the protein level, the role of microRNAs （miRNAs） in the molecular pathogenesis underlying this lethal disease is not fully understood. Here, we report that the miRNAs hsa-miR-1246, hsa-miR-320a and hsa-miR-196b-5p were induced in human umbilical vein endothelial cells （HUVECs） following expression of EBOV GP. Among the proteins encoded by predicted targets of these miRNAs, the adhesion-related molecules tissue factor pathway inhibitor （TFPI）, dystroglycan! （DAG1） and the caspase 8 and FADD-like apoptosis regulator （CFLAR） were significantly downregulated in EBOV GP-expressing HUVECs. Moreover, inhibition of hsa-miR-1246, hsa-miR-320a and hsa-miR-196b-5p, or overexpression of TFPI, DAG1 and CFLAR rescued the cell viability that was induced by EBOV GP. Our results provide a novel molecular basis for EBOV pathogenesis and may contribute to the development of strategies to protect against future EBOV pandemics.
文摘The effects induced by streamwise conduction on the thermal characteristics of forced convection for single-phase liquid flow in rectangular microchannel heat sinks under imposed constant wall temperature have been studied. By employing the fin approach in the first law of analysis, models with and without streamwise conduction term in the energy equation were developed for hydrodynamically and thermally fully-developed flow under local thermal non-equilibrium for the solid and fluid phases. These two models were solved to obtain closed form analytical solutions for the fluid and solid temperature distributions and the analysis emphasized details of the variations induced by the streamwise conduction on the fluid temperature distributions. The effects of the Peclet number, aspect ratio, and thermal conductivity ratio on the thermal characteristics of forced convection in microchannel heat sinks were analyzed and discussed. This study reveals the conditions under which the effect of streamwise conduction is significant and should not be neglected in the forced convective heat transfer analysis of microchannel heat sinks.
基金Y. L. acknowledges the financial support of this work in part by national science foundation （NSF） （No. CBET 1034222） and faculty research funds granted by the University of California, Santa Cruz. XPS was performed at the Center for Nanoscale Systems at Harvard University, which is supported by the NSF （No. ECS-0335765）. We thank H. Lin of Harvard University for technical assistance. Work at Lawrence Livermore National Laboratory was conducted under Contract No. DE-AC52-07NA27344.
文摘Graphene oxide （GO） can be reduced to graphene in a normal aerobic setup under ambient conditions as mediated by microbial respiration of Shewanella cells. The microbially-reduced graphene （MRG） exhibited excellent electrochemical properties. Extracellular electron transfer pathways at the cell/GO interface were systematically investigated, suggesting both direct electron transfer and electron mediators are involved in the GO reduction.
基金supported by the National Basic Research Program of China (2011CBA01103)the National Natural Science Foundation of China (81372215, 31301069, 81171074, and 91232702)+2 种基金the Science Foundation of the Chinese Academy of Sciences (KJZD-EW-L01-2)Anhui Provincial Natural Science Foundation (1408085MC42)the Fundamental Research Funds for the Central Universities (WK2070000034)
文摘MicroRNAs, a class of small noncoding RNAs, play key roles in diverse biological and pathological processes. ER stress, resulting from the accumulation of unfolded or misfolded proteins in the ER lumen, is triggered by various physiological events and pathological insults. Here, using RNA deep sequencing analysis, we found that the expression of some microRNAs was altered in HeLa and HEK293 cells under ER stress. Protein and RNA levels of DGCR8, Drosha, Exportin-5, Dicer, and Ago2 showed no significant alteration in ER-stressed cells, which suggested that the change in microRNA expression might not be caused by the microRNA biogenesis pathway but by other, unknown factors. Real-time PCR assays confirmed that hsa-miR-423-5p was up-regulated, whereas hsa-miR-221-3p and hsa-miR-452-5p were down-regulated, in both HeLa and HEK293 cells under ER stress. Luciferase activity and Western blot assays verified that CDKN1A was a direct target of hsa-miR-423-5p and that CDKN1B was a direct target of hsa-miR-221-3p and hsamiR-452-5p. We speculated that by regulating their targets, microRNAs might function cooperatively as regulators in the adaptive response to ER stress.
基金supported by the National Natural Science Foundation of China (81402831, 21520102004, 31430005, 21472231)Science and Technology Commission of Shanghai Municipality (Shanghai, China) (14JC1407700, 15JC1400400) of China
文摘Natural products are often secondary metabolites in living organisms with a wide variety of biological activities. The diversification of their structures, aiming to the search for biologically active small molecules by expanding chemical and functional spaces, is a major area of current interest in synthetic chemistry. However, developing synthetic accessibility and efficiency often faces challenges associated with structural complexity. Synthetic biology has recently emerged and is promising to accomplish complex molecules; by contrast, the application to structural diversification of natural products relies on the understanding, development and utilization of compatible biosynthetic machinery. Here, we review the strategies primarily concerning the artificial evolution of microbial natural products whose biosynthesis features template enzymology, including ribosomaUy synthesized and post-translationally modified peptides as well as the assembly line-resultant polyketides, non-ribosomal peptides and hybrids. The establishment of these approaches largely facilitates the expansion of the molecular diversity and utility through bioengineering at different stages/levels of biosynthetic pathways.
