Objective To devellop directly molecular evolution Of nitrite oxido-reductase using DNA-shuffling technique because nitrobacteria grow extremelly slow and are unable to nitrify effectively inorganic nitrogen in wastew...Objective To devellop directly molecular evolution Of nitrite oxido-reductase using DNA-shuffling technique because nitrobacteria grow extremelly slow and are unable to nitrify effectively inorganic nitrogen in wastewater treatmem. Methods The norB gene coding the ntitrite oxido-reductase in nitrobacteria was cloned and sequenced. Then, directed molecular evolution of nitrite oxido-reductase was developed by DNA-shuffling of 15 norB genes from different nitrobacteria. Results After DNA-shuffling with sexual PeR and staggered extension process PCR, the sequence was differem from its parental DNA fragmems and the homology ranged from 98% to 99%. The maximum nitrification rate of the modified bacterium of X16 by DNA-shuffling was up to 42.9 mg/L.d, which was almost 10 times higher than that of its parental bacteria. Furthermore, the modified bacterium had the same characteristics of its parental bacteria of E. coli and could grow rapidly in normal cultures. Conclusion DNA-shuffling was successfully used to engineer E. coli, which had norB gene and could degrade inorganic nitrogen effectively.展开更多
Eplgenetlc gene control is maintained by chromatln-assoclated Polycomb group (PcG)and Trithorax group (TrxG)genes,which act antagonistically via the interplay between PcG and TrxG regulation to generate silenced or pe...Eplgenetlc gene control is maintained by chromatln-assoclated Polycomb group (PcG)and Trithorax group (TrxG)genes,which act antagonistically via the interplay between PcG and TrxG regulation to generate silenced or permissive transcriptional states. In this study,we searched for PcG/TrxG genes in 180 arthropod genomes,covering all the sequenced arthropod genomes at the time of conducting this study,to perform a global investigation of PcG/TrxG genes in a phylogenetic frame.Results of ancestral state reconstruction analysis revealed that the ancestor of arthropod species has an almost complete repertoire of PcG/TrxG genes,and most of these genes were seldom lost above order level. The domain diversity analysis indicated that the PcG/TrxG genes show variable extent of domain structure changes;some of these changes could be associated with lineage-specific events.The likelihood ratio tests for selection pressure detected a number of PcG/TrxG genes which underwent episodic positive selection on the branch leading to the insects with holometabolous development.These results suggest that,despite their high conservation across arthropod species,different members of PcG/TrxG genes showed considerable differences in domain structure and sequence divergence in arthropod evolution.Our cross species comparisons using large-scale genomic data provide insights into divergent evolutionary pattern on highly conserved genes in arthropods.展开更多
基金This study was supported by the National High Technology Research and Development Program of China (863 Program) (No. 2001AA214191).
文摘Objective To devellop directly molecular evolution Of nitrite oxido-reductase using DNA-shuffling technique because nitrobacteria grow extremelly slow and are unable to nitrify effectively inorganic nitrogen in wastewater treatmem. Methods The norB gene coding the ntitrite oxido-reductase in nitrobacteria was cloned and sequenced. Then, directed molecular evolution of nitrite oxido-reductase was developed by DNA-shuffling of 15 norB genes from different nitrobacteria. Results After DNA-shuffling with sexual PeR and staggered extension process PCR, the sequence was differem from its parental DNA fragmems and the homology ranged from 98% to 99%. The maximum nitrification rate of the modified bacterium of X16 by DNA-shuffling was up to 42.9 mg/L.d, which was almost 10 times higher than that of its parental bacteria. Furthermore, the modified bacterium had the same characteristics of its parental bacteria of E. coli and could grow rapidly in normal cultures. Conclusion DNA-shuffling was successfully used to engineer E. coli, which had norB gene and could degrade inorganic nitrogen effectively.
基金the National Natural Science Foundation of China (Nos.31672353 and 31472047)The State Key Laboratory of Integrated Management of Pest Insects and Rodents (Grant No.ChineseIPM1708).
文摘Eplgenetlc gene control is maintained by chromatln-assoclated Polycomb group (PcG)and Trithorax group (TrxG)genes,which act antagonistically via the interplay between PcG and TrxG regulation to generate silenced or permissive transcriptional states. In this study,we searched for PcG/TrxG genes in 180 arthropod genomes,covering all the sequenced arthropod genomes at the time of conducting this study,to perform a global investigation of PcG/TrxG genes in a phylogenetic frame.Results of ancestral state reconstruction analysis revealed that the ancestor of arthropod species has an almost complete repertoire of PcG/TrxG genes,and most of these genes were seldom lost above order level. The domain diversity analysis indicated that the PcG/TrxG genes show variable extent of domain structure changes;some of these changes could be associated with lineage-specific events.The likelihood ratio tests for selection pressure detected a number of PcG/TrxG genes which underwent episodic positive selection on the branch leading to the insects with holometabolous development.These results suggest that,despite their high conservation across arthropod species,different members of PcG/TrxG genes showed considerable differences in domain structure and sequence divergence in arthropod evolution.Our cross species comparisons using large-scale genomic data provide insights into divergent evolutionary pattern on highly conserved genes in arthropods.