Biogeochemical cyclic activity of the ars (arsenic resistance system) operon is arsB influx/effux encoded by the ecological of Pseudomonas putida.This suggests that studying arsenite-oxidizing bacteria may lead to a b...Biogeochemical cyclic activity of the ars (arsenic resistance system) operon is arsB influx/effux encoded by the ecological of Pseudomonas putida.This suggests that studying arsenite-oxidizing bacteria may lead to a better understanding of molecular geomicrobiology,which can be applied to the bioremediation of arsenic-contaminated mines.This is the first report in which multiple arsB-binding mechanisms have been used on indigenous bacteria.In ArsB (strains OS-5; ABB83931; OS-19; ABB04282 and RW-28; ABB88574...展开更多
Impact statement Arsenic is the most common toxic metalloid in the environment.Nearly all organisms have genes for arsenic detoxification.Arsenic detoxification genes are frequently organized in chromosomal or plasmid...Impact statement Arsenic is the most common toxic metalloid in the environment.Nearly all organisms have genes for arsenic detoxification.Arsenic detoxification genes are frequently organized in chromosomal or plasmid-encoded arsenic resistance(ars)operons,which are commonly regulated by members of the ArsR transcriptional repressors.To date,three As(Ⅲ)-responsive ArsRs with different As(III)binding sites have been identified.Here,we identify a new type of As(Ⅲ)-responsive ArsR repressor that has an atypical As(Ⅲ)binding site and controls transcription of the ars operon of Arsenicibacter rosenii SM-1.Our results provide new insights into the classification and evolution relationship of the ArsR transcriptional repressors.展开更多
Contamination of soil and water by arsenic is a global problem. In Australia, the dipping of cattle in arsenic-containing solution to control cattle ticks in last centenary has left many sites heavily contaminated wit...Contamination of soil and water by arsenic is a global problem. In Australia, the dipping of cattle in arsenic-containing solution to control cattle ticks in last centenary has left many sites heavily contaminated with arsenic and other toxicants. We had previously isolated five soil bacterial strains （CDB 1-5） highly resistant to arsenic. To understand the resistance mechanism, molecular studies have been carried out. Two chromosome-encoded arsenic resistance （ars） gene clusters have been cloned from CDB3 （Bacillus sp.）. They both function in Escherichia coli and cluster i exerts a much higher resistance to the toxic metalloid. Cluster 2 is smaller possessing four open reading frames （ORFs） arsRorf2BC, similar to that identified in Bacillus subtilis Skin element. Among the eight ORFs in cluster 1 five are analogs of common ars genes found in other bacteria, however, organized in a unique order arsRBCDA instead of arsRDABC. Three other putative genes are located directly downstream and designated as arsTIP based on the homologies of their theoretical translation sequences respectively to thioredoxin reductases, iron-sulphur cluster proteins and protein phosphatases. The latter two are novel of any known ars operons. The arsD gene from Bacillus species was cloned for the first time and the predict protein differs from the well studied E. coli ArsD by lacking two pairs of C-terminal cysteine residues. Its functional involvement in arsenic resistance has been confirmed by a deletion experiment. There exists also an inverted repeat in the intergenic region between arsC and arsD implying some unknown transcription regulation.展开更多
文摘为有效预测船舶油耗,提出一种基于混合核函数的船舶油耗预测模型。分别构建径向基函数(radial basis function,RBF)和多项式单核函数的支持向量回归(support vector regression,SVR)模型,并利用自适应随机搜索(adaptive random search,ARS)算法对两者进行优化。在此基础上,建立基于混合核函数ARS-SVR的船舶油耗预测模型。以一艘风帆助航的大型原油运输船(very large crude carrier,VLCC)为研究对象,基于实船监测数据开展船舶油耗预测。结果表明,与单一的RBF和多项式单核ARS-SVR相比,采用混合核函数ARS-SVR的模型的预测结果的均方根误差分别降低了19.8%和30.2%。所提出的船舶油耗预测模型可以提升风帆助航船油耗计算的准确率,有助于优化船舶能效和提升管理技术。
基金the Korea Science and Engineering Foundation (KOSEF) through the National Research Lab.Program funded by the Korean Ministry of Science and Technology (No.M10300000298-06J0000-29810).
文摘Biogeochemical cyclic activity of the ars (arsenic resistance system) operon is arsB influx/effux encoded by the ecological of Pseudomonas putida.This suggests that studying arsenite-oxidizing bacteria may lead to a better understanding of molecular geomicrobiology,which can be applied to the bioremediation of arsenic-contaminated mines.This is the first report in which multiple arsB-binding mechanisms have been used on indigenous bacteria.In ArsB (strains OS-5; ABB83931; OS-19; ABB04282 and RW-28; ABB88574...
基金supported by the Natural Science Foundation of China(Grant Nos.42077210 and 41930758 to Ke Huang and Fang-jie Zhao,respectively).
文摘Impact statement Arsenic is the most common toxic metalloid in the environment.Nearly all organisms have genes for arsenic detoxification.Arsenic detoxification genes are frequently organized in chromosomal or plasmid-encoded arsenic resistance(ars)operons,which are commonly regulated by members of the ArsR transcriptional repressors.To date,three As(Ⅲ)-responsive ArsRs with different As(III)binding sites have been identified.Here,we identify a new type of As(Ⅲ)-responsive ArsR repressor that has an atypical As(Ⅲ)binding site and controls transcription of the ars operon of Arsenicibacter rosenii SM-1.Our results provide new insights into the classification and evolution relationship of the ArsR transcriptional repressors.
基金supported by the University of Wollongong Internal Grant and the National Natural Science Foundation of China (No.30370047)
文摘Contamination of soil and water by arsenic is a global problem. In Australia, the dipping of cattle in arsenic-containing solution to control cattle ticks in last centenary has left many sites heavily contaminated with arsenic and other toxicants. We had previously isolated five soil bacterial strains （CDB 1-5） highly resistant to arsenic. To understand the resistance mechanism, molecular studies have been carried out. Two chromosome-encoded arsenic resistance （ars） gene clusters have been cloned from CDB3 （Bacillus sp.）. They both function in Escherichia coli and cluster i exerts a much higher resistance to the toxic metalloid. Cluster 2 is smaller possessing four open reading frames （ORFs） arsRorf2BC, similar to that identified in Bacillus subtilis Skin element. Among the eight ORFs in cluster 1 five are analogs of common ars genes found in other bacteria, however, organized in a unique order arsRBCDA instead of arsRDABC. Three other putative genes are located directly downstream and designated as arsTIP based on the homologies of their theoretical translation sequences respectively to thioredoxin reductases, iron-sulphur cluster proteins and protein phosphatases. The latter two are novel of any known ars operons. The arsD gene from Bacillus species was cloned for the first time and the predict protein differs from the well studied E. coli ArsD by lacking two pairs of C-terminal cysteine residues. Its functional involvement in arsenic resistance has been confirmed by a deletion experiment. There exists also an inverted repeat in the intergenic region between arsC and arsD implying some unknown transcription regulation.
