This investigation was to assess the joint effects of metal binary mixtures on seed germination,root and shoot growth,bacterial bioluminescence,and gene mutation based on the one toxic unit（1 TU）approach.Different s...This investigation was to assess the joint effects of metal binary mixtures on seed germination,root and shoot growth,bacterial bioluminescence,and gene mutation based on the one toxic unit（1 TU）approach.Different sensitivities and orders of toxicity of metal mixtures were observed among the bioassays.In general,mostly additive or antagonistic effects were observed,while almost no synergistic effects by the binary metal mixtures in all bioassays.Therefore,the combined effects of heavy metals in the different bioassays were difficult to generalize since they were dependent on both chemical type and the organism used in each bioassay.However, these results indicate that a battery of bioassays with mixture chemicals as opposed to just a single assay with single metal is a better strategy for the bioassessment of environmental pollutants.展开更多
Coronaviruses (CoVs) are generally associated with respiratory and enteric infections and have long been recognized as important pathogens of livestock and companion animals. Mouse hepatitis virus (MHV) is a widely st...Coronaviruses (CoVs) are generally associated with respiratory and enteric infections and have long been recognized as important pathogens of livestock and companion animals. Mouse hepatitis virus (MHV) is a widely studied model system for Coronavirus replication and pathogenesis. In this study,we created a MHV-A59 temperature sensitive (ts) mutant Wu"-ts18(cd) using the recombinant vaccinia reverse genetics system. Virus replication assay in 17C1-1 cells showed the plaque phenotype and replication characterization of constructed Wu"-ts18(cd) were indistinguishable from the reported ts mutant Wu"-ts18. Then we cultured the ts mutant Wu"-ts18(cd) at non-permissive temperature 39.5°C,which "forced" the ts recombinant virus to use second-site mutation to revert from a ts to a non-ts phenotype. Sequence analysis showed most of the revertants had the same single amino acid mutation at Nsp16 position 43. The single amino acid mutation at Nsp16 position 76 or position 130 could also revert the ts mutant Wu"-ts18 (cd) to non-ts phenotype,an additional independent mutation in Nsp13 position 115 played an important role on plaque size. The results provided us with genetic information on the functional determinants of Nsp16. This allowed us to build up a more reasonable model of CoVs replication-transcription complex.展开更多
fruA∷TcΩ5 is a development deficient strain of M.Xamthus.Transposon TnV was used to randomly mutagenize various sites of fruA ∷TcΩ5 chromosome.Fruiting body formation was restored in one TnV insertion mutant,desig...fruA∷TcΩ5 is a development deficient strain of M.Xamthus.Transposon TnV was used to randomly mutagenize various sites of fruA ∷TcΩ5 chromosome.Fruiting body formation was restored in one TnV insertion mutant,designated XM1206.The TnV\|inserted DNA fragment from XM1206 chromosome was cloned,which may be served as a probe to isolate the corresponding allele from wild\|type strain.展开更多
The mechanical properties dependence on the microstructure was reviewed and analyzed,and the ultrafine grained duplex microstructure of BCC matrix and large fractioned austenite was given as one of the optimum structu...The mechanical properties dependence on the microstructure was reviewed and analyzed,and the ultrafine grained duplex microstructure of BCC matrix and large fractioned austenite was given as one of the optimum structures to develop the third generation steel with high strength and high ductility.The medium-Mn steels with different carbon contents processed by austenite reverted transformation(ART-annealing) were studied thoroughly to fabricate the ultrafine duplex steels with large fractioned austenite.The lamellar typed ultrafine structure,the granular typed ultrafine duplex structure and the corresponding mechanical properties of the medium-Mn steels processed by ART-annealing were demonstrated in this paper.It was revealed that the duplex structure with large fraction of austenite and ultrafine grain structure is capable of producing steels with excellent combination of strength and ductility,i.e.,Rm A about 30-50 GPa%,which is about two times of that of the conventional automobile steels and close to that of the TWIP steels.It was concluded that the ART-annealing of the medium-Mn steels would be at least one of the promising ways to fabricate the third generation automobile steels in the near future.展开更多
基金supported by the Basic Science Research Project through the National Research Foundation of Korea funded by the Ministry of Education,Science and Technology (No. 2012-0007703)
文摘This investigation was to assess the joint effects of metal binary mixtures on seed germination,root and shoot growth,bacterial bioluminescence,and gene mutation based on the one toxic unit（1 TU）approach.Different sensitivities and orders of toxicity of metal mixtures were observed among the bioassays.In general,mostly additive or antagonistic effects were observed,while almost no synergistic effects by the binary metal mixtures in all bioassays.Therefore,the combined effects of heavy metals in the different bioassays were difficult to generalize since they were dependent on both chemical type and the organism used in each bioassay.However, these results indicate that a battery of bioassays with mixture chemicals as opposed to just a single assay with single metal is a better strategy for the bioassessment of environmental pollutants.
基金Research Grants from State Key Laboratory of Pathogen and Biosecurity (SKLPBS0918)
文摘Coronaviruses (CoVs) are generally associated with respiratory and enteric infections and have long been recognized as important pathogens of livestock and companion animals. Mouse hepatitis virus (MHV) is a widely studied model system for Coronavirus replication and pathogenesis. In this study,we created a MHV-A59 temperature sensitive (ts) mutant Wu"-ts18(cd) using the recombinant vaccinia reverse genetics system. Virus replication assay in 17C1-1 cells showed the plaque phenotype and replication characterization of constructed Wu"-ts18(cd) were indistinguishable from the reported ts mutant Wu"-ts18. Then we cultured the ts mutant Wu"-ts18(cd) at non-permissive temperature 39.5°C,which "forced" the ts recombinant virus to use second-site mutation to revert from a ts to a non-ts phenotype. Sequence analysis showed most of the revertants had the same single amino acid mutation at Nsp16 position 43. The single amino acid mutation at Nsp16 position 76 or position 130 could also revert the ts mutant Wu"-ts18 (cd) to non-ts phenotype,an additional independent mutation in Nsp13 position 115 played an important role on plaque size. The results provided us with genetic information on the functional determinants of Nsp16. This allowed us to build up a more reasonable model of CoVs replication-transcription complex.
文摘fruA∷TcΩ5 is a development deficient strain of M.Xamthus.Transposon TnV was used to randomly mutagenize various sites of fruA ∷TcΩ5 chromosome.Fruiting body formation was restored in one TnV insertion mutant,designated XM1206.The TnV\|inserted DNA fragment from XM1206 chromosome was cloned,which may be served as a probe to isolate the corresponding allele from wild\|type strain.
基金supported by the National Basic Research Program of China "973 program" (Grant No. 2010CB630803)
文摘The mechanical properties dependence on the microstructure was reviewed and analyzed,and the ultrafine grained duplex microstructure of BCC matrix and large fractioned austenite was given as one of the optimum structures to develop the third generation steel with high strength and high ductility.The medium-Mn steels with different carbon contents processed by austenite reverted transformation(ART-annealing) were studied thoroughly to fabricate the ultrafine duplex steels with large fractioned austenite.The lamellar typed ultrafine structure,the granular typed ultrafine duplex structure and the corresponding mechanical properties of the medium-Mn steels processed by ART-annealing were demonstrated in this paper.It was revealed that the duplex structure with large fraction of austenite and ultrafine grain structure is capable of producing steels with excellent combination of strength and ductility,i.e.,Rm A about 30-50 GPa%,which is about two times of that of the conventional automobile steels and close to that of the TWIP steels.It was concluded that the ART-annealing of the medium-Mn steels would be at least one of the promising ways to fabricate the third generation automobile steels in the near future.
