Summary What is already known about this topic?There is a toilet flush-soil stack-floor drain pathway of aerosol transmission in multistory and high-rise buildings,but the influencing factors are not completely clear....Summary What is already known about this topic?There is a toilet flush-soil stack-floor drain pathway of aerosol transmission in multistory and high-rise buildings,but the influencing factors are not completely clear.What is added by this report?The poor airtightness of the connecting parts of the floor drain,as well as pressure fluctuations in the sewage pipe during toilet flushing caused by blockage of the soil stack vent,may lead to the cross-floor transmission of viral aerosols through the soil stack and floor drains.展开更多
Glycyrrhizin(GL)and Glycyrrhetic Acid 3-O-mono-β-D-glucuronide(GAMG)are the typical triterpenoid glycosides found in the root of licorice,a popular medicinal plant that exhibits diverse physiological effects and phar...Glycyrrhizin(GL)and Glycyrrhetic Acid 3-O-mono-β-D-glucuronide(GAMG)are the typical triterpenoid glycosides found in the root of licorice,a popular medicinal plant that exhibits diverse physiological effects and pharmacological manifestations.However,only few reports are available on the glycosylation enzymes involved in the biosynthesis of these valuable compounds with low conversion yield so far.In mammals,glycosyltransferases are involved in the phase II metabolism and may provide new solutions for us to engineer microbial strains to produce high valued compounds due to the substrate promiscuity of these glycosyltransferases.In this study,we mined the genomic databases of mammals and evaluated 22 candidate genes of O-glycosyltransferases by analyzing their catalytic potential for O-glycosylation of the native substrate,glycyrrhetinic acid(GA)for its glycodiversification.Out of 22 selected glycosyltransferases,only UGT1A1 exhibited high catalytic performance for biosynthesis of the key licorice compounds GL and GAMG.Molecular docking results proposed that the enzymatic activity of UGT1A1 was likely owing to the stable hydrogen bonding interactions and favorite conformations between the amino acid residues around substrate channels(P82~R85)and substrates.Furthermore,the complete biosynthesis pathway of GL was reconstructed in Saccharomyces cerevisiae for the first time,resulting in the production of 5.98±0.47 mg/L and 2.31±0.21 mg/L of GL and GAMG,respectively.展开更多
Summary What is already known about this topic?Aerosol transmission of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)via sanitary pipelines in high-rise buildings is possible,however,there is a lack of ex...Summary What is already known about this topic?Aerosol transmission of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)via sanitary pipelines in high-rise buildings is possible,however,there is a lack of experimental evidence.展开更多
The coronavirus disease 2019(COVID-19)pandemic is an unpreedented global event.It has become clear that COVID-19 is transmitted by virus-containing droplets(>5μm)and aerosols(<5μm),and that all human exhalator...The coronavirus disease 2019(COVID-19)pandemic is an unpreedented global event.It has become clear that COVID-19 is transmitted by virus-containing droplets(>5μm)and aerosols(<5μm),and that all human exhalatory activities(e.g.,breathing,speaking,singing,shouting,coughing,and sneezing)result in the emission of suspended droplets/aerosols of various sizes.As an example,COVID-19 patients exhale millions of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)RNA copies into the air per hour[1].SARS-CoV-2-laden aerosols play a profound role in disease transmission,as they can linger and remain viable in the air for a long duration(~16 h)[2]and travel a long distance(~4.8 m)due to their smaller size[3].展开更多
基金Supported by the Key Program of National Natural Science Foundation of China(No.92043201).
文摘Summary What is already known about this topic?There is a toilet flush-soil stack-floor drain pathway of aerosol transmission in multistory and high-rise buildings,but the influencing factors are not completely clear.What is added by this report?The poor airtightness of the connecting parts of the floor drain,as well as pressure fluctuations in the sewage pipe during toilet flushing caused by blockage of the soil stack vent,may lead to the cross-floor transmission of viral aerosols through the soil stack and floor drains.
基金supported by the National Key Research and Development Program of China(2018YFA0901800)the Key Research and Development Program of Hebei Province(21374301D)+2 种基金the Natural Science Foundation of China(No.22078171)the Natural Science Foundation of Hebei Province(No.C2019105055)the Scientific Research Foundation of Tangshan Normal University(No.2021B34).
文摘Glycyrrhizin(GL)and Glycyrrhetic Acid 3-O-mono-β-D-glucuronide(GAMG)are the typical triterpenoid glycosides found in the root of licorice,a popular medicinal plant that exhibits diverse physiological effects and pharmacological manifestations.However,only few reports are available on the glycosylation enzymes involved in the biosynthesis of these valuable compounds with low conversion yield so far.In mammals,glycosyltransferases are involved in the phase II metabolism and may provide new solutions for us to engineer microbial strains to produce high valued compounds due to the substrate promiscuity of these glycosyltransferases.In this study,we mined the genomic databases of mammals and evaluated 22 candidate genes of O-glycosyltransferases by analyzing their catalytic potential for O-glycosylation of the native substrate,glycyrrhetinic acid(GA)for its glycodiversification.Out of 22 selected glycosyltransferases,only UGT1A1 exhibited high catalytic performance for biosynthesis of the key licorice compounds GL and GAMG.Molecular docking results proposed that the enzymatic activity of UGT1A1 was likely owing to the stable hydrogen bonding interactions and favorite conformations between the amino acid residues around substrate channels(P82~R85)and substrates.Furthermore,the complete biosynthesis pathway of GL was reconstructed in Saccharomyces cerevisiae for the first time,resulting in the production of 5.98±0.47 mg/L and 2.31±0.21 mg/L of GL and GAMG,respectively.
基金Supported by the Key Program of National Natural Science Foundation of China(92043201).
文摘Summary What is already known about this topic?Aerosol transmission of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)via sanitary pipelines in high-rise buildings is possible,however,there is a lack of experimental evidence.
基金supported by the National Institute of Environmental Health(NIEH)the Chinese Center for Disease Control and Prevention(GWTX05 and SWJC05)the Capital Health Development Scientific Research Project(2021-1G-2172)。
文摘The coronavirus disease 2019(COVID-19)pandemic is an unpreedented global event.It has become clear that COVID-19 is transmitted by virus-containing droplets(>5μm)and aerosols(<5μm),and that all human exhalatory activities(e.g.,breathing,speaking,singing,shouting,coughing,and sneezing)result in the emission of suspended droplets/aerosols of various sizes.As an example,COVID-19 patients exhale millions of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)RNA copies into the air per hour[1].SARS-CoV-2-laden aerosols play a profound role in disease transmission,as they can linger and remain viable in the air for a long duration(~16 h)[2]and travel a long distance(~4.8 m)due to their smaller size[3].
