Microbial lysis of dimethylsulfoniopropionate(DMSP)is a key step in marine organic sulfur cycling and has been recently demonstrated to play an important role in mediating interactions between bacteria,algae,and zoopl...Microbial lysis of dimethylsulfoniopropionate(DMSP)is a key step in marine organic sulfur cycling and has been recently demonstrated to play an important role in mediating interactions between bacteria,algae,and zooplankton.To date,microbes that have been found to lyse DMSP are largely confined to free‐living and surface‐attached bacteria.In this study,we report for the first time that a symbiont(termed“Rhodobiaceae bacterium HWgs001”)in the gill of the marine scallop Argopecten irradians irradians can lyse and metabolize DMSP.Analysis of 16S rRNA gene sequences suggested that HWgs001 accounted for up to 93%of the gill microbiota.Microscopic observations suggested that HWgs001 lived within the gill tissue.Unlike symbionts of other bivalves,HWgs001 belongs to Alphaproteobacteria rather than Gammaproteobacteria,and no genes for carbon fixation were identified in its small genome.Moreover,HWgs001 was found to possess a dddP gene,responsible for the lysis of DMSP to acrylate.The enzymatic activity of dddP was confirmed using the heterologous expression,and in situ transcription of the gene in scallop gill tissues was demonstrated using reverse‐transcription PCR.Together,these results revealed a taxonomically and functionally unique symbiont,which represents the first‐documented DMSP‐metabolizing symbiont likely to play significant roles in coastal marine ecosystems.展开更多
Geckos' ability to move on steep surfaces depends on their excellent adhesive structure, timely adjustments on locomotor behaviors, and elaborates control on reaction forces. However, it is still unclear how they ...Geckos' ability to move on steep surfaces depends on their excellent adhesive structure, timely adjustments on locomotor behaviors, and elaborates control on reaction forces. However, it is still unclear how they can generate a sufficient driving force that is necessary for locomotion, while ensuring reliable adhesion on steep inclines. We measured the forces acting on each foot and recorded the contact states between feet and substrates when geckos encountered smooth inclination challenges ranging from 0° to 180°. The critical angles of the resultant force vectors of the front and hind-feet increased with respect to the incline angles. When the incline angle became greater than 120°, the critical angles of the front- and hind-feet were similar, and the averages of the critical angles of the front - and hind-feet were both smaller than 120°, indicating that the complicated and accurate synergy among toes endows gecko's foot an obvious characteristic of "frictional adhesion" during locomotion. Additionally, we established a contact mechanical model for gecko's foot in order to quantify the contribution of the frictional forces generated by the heel, and the adhesion forces generated by the toes on various inclines. The synergy between multiple contact mechanisms(friction or adhesion) is critical for the reliable attachment on an inclined surface, which is impossible to achieve by using a single-contact mechanism, thereby increasing the animal's ability to adapt to its environment.展开更多
China’s urbanization has attracted a lot of attention due to its unprecedented pace and intensity in terms of land,population,and economic impact.However,due to the lack of consistent and harmonized data,little is kn...China’s urbanization has attracted a lot of attention due to its unprecedented pace and intensity in terms of land,population,and economic impact.However,due to the lack of consistent and harmonized data,little is known about the patterns and dynamics of the interaction between these different aspects over the past few decades.Along with the implementation of the 2030 Agenda for Sustainable Development,a standardized dataset for assessing the sustainability of urbanization in China is needed.In this paper,we used remote sensing data from multiple sources(time-series of Landsat and Sentinel images)to map the impervious surface area(ISA)at five-year intervals from 1990 to 2015 and then converted the results into a standardized dataset of the built-up area for 433 Chinese cities with 300,000 inhabitants or more.This dataset was produced following the well-established rules adopted by the United Nations(UN).Validation of the ISA maps in urban areas based on the visual interpretation of Google Earth images showed that the average overall accuracy(OA),producer’s accuracy(PA)and user’s accuracy(UA)were 91.24%,92.58%and 89.65%,respec-tively.Comparisons with other existing urban built-up area datasets derived from the National Bureau of Statistics of China,the World Bank and UN-habitat indicated that our dataset,namely the stan-dardized urban built-up area dataset for China(SUBAD-China),provides an improved description of the spatiotemporal character-istics of the urbanization process and is especially applicable to a combined analysis of the spatial and socio-economic domains in urban areas.Potential applications of this dataset include combin-ing the spatial expansion and demographic information provided by UN to calculate sustainable development indicators such as SDG 11.3.1.The dataset could also be used in other multidimensional syntheses related to the study of urbanization in China.展开更多
This paper presents the first measurement of multi-decadal thickness and volume changes(1969?2000)of the Dongkemadi Ice Field(DIF)in the Tanggula Mountains,central Qinghai-Tibetan Plateau,China,using multi-source remo...This paper presents the first measurement of multi-decadal thickness and volume changes(1969?2000)of the Dongkemadi Ice Field(DIF)in the Tanggula Mountains,central Qinghai-Tibetan Plateau,China,using multi-source remote sensing data.These include the Shuttle Radar Topography Mission(SRTM)Digital Elevation Model(DEM)acquired in February,2000,a DEM generated by digitising analogue topographic maps from 1969,and Landsat ETM?imagery from 2000.Digital glacier outlines and GIS-based processing were used to calculate an elevation difference map to evaluate the relative elevation error of these two DEMs over ice-free areas.This methodwas also used to identify regions of glacier elevation thinning and thickening corresponding to glacier mass loss and gain.Analysis of 67,520 points on flat grass and rock terrain surrounding the DIF,with a slope less than 258,showed a mean elevation difference of?0.90 m and a standard deviation of 5.58 m.A thickness change error within 96 m was estimated.Between 1969 and 2000,76.51%of the whole DIF area appeared to be thinning while 23.49%showed thickening.The average glacier surface thinning was?12.58 m with a standard deviation of 18.29 m and the estimated volume loss was 1.17 km 3.The standard deviation of volume change was 0.0006 km 3 over the DIF.A thinning rate up to 0.4190.194 m a?1 or 0.038 km 3 a?1 for the volume loss was observed for the whole ice field,which seems to be evidence for the ongoing retreat of glaciers on the Qinghai-Tibetan Plateau.It was found that the spatial thickness change pattern derived from the remote sensing method was consistent with the thickness change results of the Small Dongkemadi Glacier(SDG)from field measurements.The estimated error of the annual thickness change rate was on the order of 5%.The relationship between elevation change and absolute glacier elevation over typical glaciers was also analysed,showing considerable variability.These changes have possibly resulted from increased temperature and decreased precipitation in this region.展开更多
To the Editor:A 44-year-old female presented at the local hospital for repeated episodes of having palp Nations,accompanied with cold sweats,amaurosis,vomiting,and limb weakness in the previous 2 months.An electrocard...To the Editor:A 44-year-old female presented at the local hospital for repeated episodes of having palp Nations,accompanied with cold sweats,amaurosis,vomiting,and limb weakness in the previous 2 months.An electrocardiogram indicated "ventricular tachycardia" when she was not feeling well.The symptoms alleviated significantly after injections of"amiodarone"(dose unknown),after which the patient was discharged.A local physician recommended ablation,so the patient was transferred to our hospital.The patient was generally healthy and had lived in a region with pastures.According to the patient5 self-report,she had been diagnosed as having liver hydatidosis 30 years ago,but had recovered after surgical treatment at the local hospital.Furthermore,the patient claimed to have no other medical history.展开更多
基金supported by the Key Research and Development Program of Shandong Province(No.2021 ZLGX03)the start-up fund from Ocean University of China(No.862101013141).
文摘Microbial lysis of dimethylsulfoniopropionate(DMSP)is a key step in marine organic sulfur cycling and has been recently demonstrated to play an important role in mediating interactions between bacteria,algae,and zooplankton.To date,microbes that have been found to lyse DMSP are largely confined to free‐living and surface‐attached bacteria.In this study,we report for the first time that a symbiont(termed“Rhodobiaceae bacterium HWgs001”)in the gill of the marine scallop Argopecten irradians irradians can lyse and metabolize DMSP.Analysis of 16S rRNA gene sequences suggested that HWgs001 accounted for up to 93%of the gill microbiota.Microscopic observations suggested that HWgs001 lived within the gill tissue.Unlike symbionts of other bivalves,HWgs001 belongs to Alphaproteobacteria rather than Gammaproteobacteria,and no genes for carbon fixation were identified in its small genome.Moreover,HWgs001 was found to possess a dddP gene,responsible for the lysis of DMSP to acrylate.The enzymatic activity of dddP was confirmed using the heterologous expression,and in situ transcription of the gene in scallop gill tissues was demonstrated using reverse‐transcription PCR.Together,these results revealed a taxonomically and functionally unique symbiont,which represents the first‐documented DMSP‐metabolizing symbiont likely to play significant roles in coastal marine ecosystems.
基金supported by the National Natural Science Foundation of China (Grant No. 51435008 to Z.D. and 31601870 to Z.W.)Natural Science Foundation of Jiangsu Province, China (Grant No.SBK2016040649 to Z.W.).
文摘Geckos' ability to move on steep surfaces depends on their excellent adhesive structure, timely adjustments on locomotor behaviors, and elaborates control on reaction forces. However, it is still unclear how they can generate a sufficient driving force that is necessary for locomotion, while ensuring reliable adhesion on steep inclines. We measured the forces acting on each foot and recorded the contact states between feet and substrates when geckos encountered smooth inclination challenges ranging from 0° to 180°. The critical angles of the resultant force vectors of the front and hind-feet increased with respect to the incline angles. When the incline angle became greater than 120°, the critical angles of the front- and hind-feet were similar, and the averages of the critical angles of the front - and hind-feet were both smaller than 120°, indicating that the complicated and accurate synergy among toes endows gecko's foot an obvious characteristic of "frictional adhesion" during locomotion. Additionally, we established a contact mechanical model for gecko's foot in order to quantify the contribution of the frictional forces generated by the heel, and the adhesion forces generated by the toes on various inclines. The synergy between multiple contact mechanisms(friction or adhesion) is critical for the reliable attachment on an inclined surface, which is impossible to achieve by using a single-contact mechanism, thereby increasing the animal's ability to adapt to its environment.
基金funded by the Strategic Priority Research Program of the Chinese Academy of Sciences[XDA19030104,XDA19090121]the Key Research and Development Projects of Hainan Province[ZDYF2019008].
文摘China’s urbanization has attracted a lot of attention due to its unprecedented pace and intensity in terms of land,population,and economic impact.However,due to the lack of consistent and harmonized data,little is known about the patterns and dynamics of the interaction between these different aspects over the past few decades.Along with the implementation of the 2030 Agenda for Sustainable Development,a standardized dataset for assessing the sustainability of urbanization in China is needed.In this paper,we used remote sensing data from multiple sources(time-series of Landsat and Sentinel images)to map the impervious surface area(ISA)at five-year intervals from 1990 to 2015 and then converted the results into a standardized dataset of the built-up area for 433 Chinese cities with 300,000 inhabitants or more.This dataset was produced following the well-established rules adopted by the United Nations(UN).Validation of the ISA maps in urban areas based on the visual interpretation of Google Earth images showed that the average overall accuracy(OA),producer’s accuracy(PA)and user’s accuracy(UA)were 91.24%,92.58%and 89.65%,respec-tively.Comparisons with other existing urban built-up area datasets derived from the National Bureau of Statistics of China,the World Bank and UN-habitat indicated that our dataset,namely the stan-dardized urban built-up area dataset for China(SUBAD-China),provides an improved description of the spatiotemporal character-istics of the urbanization process and is especially applicable to a combined analysis of the spatial and socio-economic domains in urban areas.Potential applications of this dataset include combin-ing the spatial expansion and demographic information provided by UN to calculate sustainable development indicators such as SDG 11.3.1.The dataset could also be used in other multidimensional syntheses related to the study of urbanization in China.
基金supported by the Major State Basic Research Development Program of China(973 Program)(Nos.2010CB951403,2009CB723901)a grant from the Ministry of Science and Technology of the People’s Republic of China(No.2006FY110200).
文摘This paper presents the first measurement of multi-decadal thickness and volume changes(1969?2000)of the Dongkemadi Ice Field(DIF)in the Tanggula Mountains,central Qinghai-Tibetan Plateau,China,using multi-source remote sensing data.These include the Shuttle Radar Topography Mission(SRTM)Digital Elevation Model(DEM)acquired in February,2000,a DEM generated by digitising analogue topographic maps from 1969,and Landsat ETM?imagery from 2000.Digital glacier outlines and GIS-based processing were used to calculate an elevation difference map to evaluate the relative elevation error of these two DEMs over ice-free areas.This methodwas also used to identify regions of glacier elevation thinning and thickening corresponding to glacier mass loss and gain.Analysis of 67,520 points on flat grass and rock terrain surrounding the DIF,with a slope less than 258,showed a mean elevation difference of?0.90 m and a standard deviation of 5.58 m.A thickness change error within 96 m was estimated.Between 1969 and 2000,76.51%of the whole DIF area appeared to be thinning while 23.49%showed thickening.The average glacier surface thinning was?12.58 m with a standard deviation of 18.29 m and the estimated volume loss was 1.17 km 3.The standard deviation of volume change was 0.0006 km 3 over the DIF.A thinning rate up to 0.4190.194 m a?1 or 0.038 km 3 a?1 for the volume loss was observed for the whole ice field,which seems to be evidence for the ongoing retreat of glaciers on the Qinghai-Tibetan Plateau.It was found that the spatial thickness change pattern derived from the remote sensing method was consistent with the thickness change results of the Small Dongkemadi Glacier(SDG)from field measurements.The estimated error of the annual thickness change rate was on the order of 5%.The relationship between elevation change and absolute glacier elevation over typical glaciers was also analysed,showing considerable variability.These changes have possibly resulted from increased temperature and decreased precipitation in this region.
文摘To the Editor:A 44-year-old female presented at the local hospital for repeated episodes of having palp Nations,accompanied with cold sweats,amaurosis,vomiting,and limb weakness in the previous 2 months.An electrocardiogram indicated "ventricular tachycardia" when she was not feeling well.The symptoms alleviated significantly after injections of"amiodarone"(dose unknown),after which the patient was discharged.A local physician recommended ablation,so the patient was transferred to our hospital.The patient was generally healthy and had lived in a region with pastures.According to the patient5 self-report,she had been diagnosed as having liver hydatidosis 30 years ago,but had recovered after surgical treatment at the local hospital.Furthermore,the patient claimed to have no other medical history.
