Streptomycetes are Gram-positive bacteria with high GC DNA content. They produce the most abundant secondary metabolites including over two-thirds of the clinically used antibiotics of natural origin (Barka et al., 20...Streptomycetes are Gram-positive bacteria with high GC DNA content. They produce the most abundant secondary metabolites including over two-thirds of the clinically used antibiotics of natural origin (Barka et al., 2016), for example,the important broad-spectrum antimicrobials oxytetracycline(OTC) and chlortetracycline, which are the tetracycline antibiotics。展开更多
Streptomyces produces many valuable and important biomolecules with clinical and pharmaceutical applications.The development of simple and highly efficient gene editing tools for genetic modification of Streptomyces i...Streptomyces produces many valuable and important biomolecules with clinical and pharmaceutical applications.The development of simple and highly efficient gene editing tools for genetic modification of Streptomyces is highly desirable.In this study,we developed a screening system for targeted gene knockout using a uracil auxotrophic host(ΔpyrF)resistant to the highly toxic uracil analog of 5-fluoroorotic acid(5-FOA)converted by PyrF,and a non-replicative vector pKC1132-pyrF carrying the complemented pyrF gene coding for orotidine-5'-phosphate decarboxylase.The pyrF gene acts as a positive selection and counterselection marker for recombinants during genetic modifications.Single-crossover homologous integration mutants were selected on minimal medium without uracil by reintroducing pyrF along with pKC1132-pyrF into the genome of the mutantΔpyrF at the targeted locus.Double-crossover recombinants were generated,from which the pyrF gene,plasmid backbone,and targeted gene were excised through homologous recombination exchange.These recombinants were rapidly screened by the counterselection agent,5-FOA.We demonstrated the feasibility and advantage of using this pyrF-based screening system through deleting the otcR gene,which encodes the cluster-situated regulator that directly activates oxytetracycline biosynthesis in Streptomyces rimosus M4018.This system provides a new genetic tool for investigating the genetic characteristics of Streptomyces species.展开更多
Efficient regulation of thermal radiation is an effective way to conserve energy consumption of buildings.Because windows are the least energy-efficient part of buildings,their thermal radiation regulation is highly d...Efficient regulation of thermal radiation is an effective way to conserve energy consumption of buildings.Because windows are the least energy-efficient part of buildings,their thermal radiation regulation is highly demanded,especially in the changing environment,but is still a challenge.Here,by employing a kirigami structure,we design a variable-angle thermal reflector as a transparent envelope of windows for their thermal radiation modulation.The envelope can be easily switched between heating and cooling modes by loading different pre-stresses,which endow the envelope windows with the ability of temperature regulation,and the interior temperature of a building model can be reduced by~3.3°C under cooling mode and increased by~3.9°C under heating mode in the outdoor test.The improved thermal management of windows by the adaptive envelope provides an extra heating,ventilation,and air-conditioning energy savings percentage of 13%to 29%per year for buildings located in different climate zones around the world,making the kirigami envelope windows a promising way for energy-saving utilization.展开更多
基金supported by grants from Shengxue Dacheng Pharmaceutical Co.,Ltd in Shijiazhuang,Chinathe National Natural Science Foundation of China(31570031)
文摘Streptomycetes are Gram-positive bacteria with high GC DNA content. They produce the most abundant secondary metabolites including over two-thirds of the clinically used antibiotics of natural origin (Barka et al., 2016), for example,the important broad-spectrum antimicrobials oxytetracycline(OTC) and chlortetracycline, which are the tetracycline antibiotics。
基金This work is supported by the Natural Science Foundation of Hebei Province(No.C2019209399)Tangshan Science and Technology Project(No.20130208b)+1 种基金the Science and Technology Program of Hebei(No.18222916)the Research Fund for Top Discipline Construction of North China University of Science and Technology(No.18060720),China.
文摘Streptomyces produces many valuable and important biomolecules with clinical and pharmaceutical applications.The development of simple and highly efficient gene editing tools for genetic modification of Streptomyces is highly desirable.In this study,we developed a screening system for targeted gene knockout using a uracil auxotrophic host(ΔpyrF)resistant to the highly toxic uracil analog of 5-fluoroorotic acid(5-FOA)converted by PyrF,and a non-replicative vector pKC1132-pyrF carrying the complemented pyrF gene coding for orotidine-5'-phosphate decarboxylase.The pyrF gene acts as a positive selection and counterselection marker for recombinants during genetic modifications.Single-crossover homologous integration mutants were selected on minimal medium without uracil by reintroducing pyrF along with pKC1132-pyrF into the genome of the mutantΔpyrF at the targeted locus.Double-crossover recombinants were generated,from which the pyrF gene,plasmid backbone,and targeted gene were excised through homologous recombination exchange.These recombinants were rapidly screened by the counterselection agent,5-FOA.We demonstrated the feasibility and advantage of using this pyrF-based screening system through deleting the otcR gene,which encodes the cluster-situated regulator that directly activates oxytetracycline biosynthesis in Streptomyces rimosus M4018.This system provides a new genetic tool for investigating the genetic characteristics of Streptomyces species.
基金The authors acknowledge financial support from the National Key R&D Program of China(grant no.2018YFA0209200)Key R&D Program of Hubei Province(2022BAA028)+1 种基金National Natural Science Foundation of China(62274071 and 61674064)Shenzhen Science and Technology Program(JCYJ20220530160808018).
文摘Efficient regulation of thermal radiation is an effective way to conserve energy consumption of buildings.Because windows are the least energy-efficient part of buildings,their thermal radiation regulation is highly demanded,especially in the changing environment,but is still a challenge.Here,by employing a kirigami structure,we design a variable-angle thermal reflector as a transparent envelope of windows for their thermal radiation modulation.The envelope can be easily switched between heating and cooling modes by loading different pre-stresses,which endow the envelope windows with the ability of temperature regulation,and the interior temperature of a building model can be reduced by~3.3°C under cooling mode and increased by~3.9°C under heating mode in the outdoor test.The improved thermal management of windows by the adaptive envelope provides an extra heating,ventilation,and air-conditioning energy savings percentage of 13%to 29%per year for buildings located in different climate zones around the world,making the kirigami envelope windows a promising way for energy-saving utilization.
