The construction of a pest detection algorithm is an important step to couple"ground-space"characteristics,which is also the basis for rapid and accurate monitoring and detection of pest damage.In four exper...The construction of a pest detection algorithm is an important step to couple"ground-space"characteristics,which is also the basis for rapid and accurate monitoring and detection of pest damage.In four experimental areas in Sanming City,Jiangle County,Sha County and Yanping District in Fujian Province,sample data on pest damage in 182 sets of Dendrolimus punctatus were collected.The data were randomly divided into a training set and testing set,and five duplicate tests and one eliminating-indicator test were done.Based on the characterization analysis of the host for D.punctatus damage,seven characteristic indicators of ground and remote sensing including leaf area index,standard error of leaf area index(SEL)of pine forest,normalized difference vegetation index(NDVI),wetness from tasseled cap transformation(WET),green band(B2),red band(B3),near-infrared band(B4)of remote sensing image are obtained to construct BP neural networks and random forest models of pest levels.The detection results of these two algorithms were comprehensively compared from the aspects of detection precision,kappa coefficient,receiver operating characteristic curve,and a paired t test.The results showed that the seven indicators all were responsive to pest damage,and NDVI was relatively weak;the average pest damage detection precision of six tests by BP neural networks was 77.29%,the kappa coefficient was 0.6869 and after the RF algorithm,the respective values were 79.30%and 0.7151,showing that the latter is more optimized,but there was no significant difference(p>0.05);the detection precision,kappa coefficient and AUC of the RF algorithm was higher than the BP neural networks for three pest levels(no damage,moderate damage and severe damage).The detection precision and AUC of BP neural networks were a little higher for mild damage,but the difference was not significant(p>0.05)except for the kappa coefficient for the no damage level(p<0.05).An"over-fitting"phenomenon tends to occur in BP neural networks,while RF method is more robust,providing a detection effect that is better than the BP neural networks.Thus,the application of the random forest algorithm for pest damage and multilevel dispersed variables is thus feasible and suggests that attention to the proportionality of sample data from various categories is needed when collecting data.展开更多
Episodic memories are composed of various interrelated elements, including those specific to items of central interest and those pertaining to related features, such as the color, shape, size, spatial location, tempor...Episodic memories are composed of various interrelated elements, including those specific to items of central interest and those pertaining to related features, such as the color, shape, size, spatial location, temporal order, and media or modalities of presentation. Memory about a core item （such as a word, object, or picture） is called item memory while memory about the context or related fea- tures of a core item is defined as source memory. What determines which sources within an episode are successfully remembered is of particular interest to researchers. Behavioral evidence suggests that the orientation of a memory task influences whether the related source of the item will be re- membered later. This study explored changes in the hippocampus and prefrontal cortex while par- ticipants completed two tasks： an item-oriented task and a source-oriented task. We used functional MRI to investigate the neural mechanisms by which task orientation influences source encoding. We found that subsequent source memory effects in the right prefrontal cortex and hippocampus were modulated by task orientation, whereas task orientation modulated item memory effects in the prefrontal cortex. These findings highlight the possibility that the hippocampus contributes to the intentional encoding of item-source associations, whereas the prefrontal cortex is biased toward processing information to which attention is directed.展开更多
Background:Digital hemispherical photography(DHP)is widely used to estimate the leaf area index(LAI)of forest plots due to its advantages of high efficiency and low cost.A crucial step in the LAI estimation of forest ...Background:Digital hemispherical photography(DHP)is widely used to estimate the leaf area index(LAI)of forest plots due to its advantages of high efficiency and low cost.A crucial step in the LAI estimation of forest plots via DHP is choosing a sampling scheme.However,various sampling schemes involving DHP have been used for the LAI estimation of forest plots.To date,the impact of sampling schemes on LAI estimation from DHP has not been comprehensively investigated.Methods:In this study,13 commonly used sampling schemes which belong to five sampling types(i.e.dispersed,square,cross,transect and circle)were adopted in the LAI estimation of five Larix principis-rupprechtii plots(25m×25 m).An additional sampling scheme(with a sample size of 89)was generated on the basis of all the sample points of the 13 sampling schemes.Three typical inversion models and four canopy element clumping index(Ωe)algorithms were involved in the LAI estimation.The impacts of the sampling schemes on four variables,including gap fraction,Ωe,effective plant area index(PAIe)and LAI estimation from DHP were analysed.The LAI estimates obtained with different sampling schemes were then compared with those obtained from litter collection measurements.Results:Large differences were observed for all four variable estimates(i.e.gap fraction,Ωe,PAIe and LAI)under different sampling schemes.The differences in impact of sampling schemes on LAI estimation were not obvious for the three inversion models,if the fourΩe algorithms,except for the traditional gap-size analysis algorithm were adopted in the estimation.The accuracy of LAI estimation was not always improved with an increase in sample size.Moreover,results indicated that with the appropriate inversion model,Ωe algorithm and sampling scheme,the maximum estimation error of DHP-estimated LAI at elementary sampling unit can be less than 20%,which is required by the global climate observing system,except in forest plots with extremely large LAI values(~>6.0).However,obtaining an LAI from DHP with an estimation error lower than 5%is impossible regardless of which combination of inversion model,Ωe algorithm and sampling scheme is used.Conclusion:The LAI estimation of L.principis-rupprechtii forests from DHP was largely affected by the sampling schemes adopted in the estimation.Thus,the sampling scheme should be seriously considered in the LAI estimation.One square and two transect sampling schemes(with sample sizes ranging from 3 to 9)were recommended to be used to estimate the LAI of L.principis-rupprechtii forests with the smallest mean relative error(MRE).By contrast,three cross and one dispersed sampling schemes were identified to provide LAI estimates with relatively large MREs.展开更多
Standardized Precipitation Index(SPI)and Standardized Precipitation Evapotranspiration Index(SPEI),traditionally derived at a monthly scale,are widely used drought indices.To overcome temporalresolution limitations,we...Standardized Precipitation Index(SPI)and Standardized Precipitation Evapotranspiration Index(SPEI),traditionally derived at a monthly scale,are widely used drought indices.To overcome temporalresolution limitations,we have previously developed and published a well-validated daily SPI/SPEI in situ dataset.Although having a high temporal resolution,this in situ dataset presents low spatial resolution due to the scarcity of stations.Therefore,based on the China Meteorological Forcing Dataset,which is composed of data from more than 1,000 ground-based observation sites and multiple remote sensing grid meteorological dataset,we present the first high spatiotemporal-resolution daily SPI/SPEI raster datasets over China.It spans from 1979 to 2018,with a spatial resolution of 0.1°×0.1°,a temporal resolution of 1-day,and the timescales of 30-,90-,and 360-days.Results show that the spatial distributions of drought event characteristics detected by the daily SPI/SPEI are consistent with the monthly SPI/SPEI.The correlation between the daily value of the 12-month scale and the monthly value of SPI/SPEI is the strongest,with linear correlation,Nash-Sutcliffe coefficient,and normalized root mean square error of 0.98,0.97,and 0.04,respectively.The daily SPI/SPEI is shown to be more sensitive to flash drought than the monthly SPI/SPEI.Our improved SPI/SPEI shows high accuracy and credibility,presenting enhanced results when compared to the monthly SPI/SPEI.The total data volume is up to 150 GB,compressed to 91 GB in Network Common Data Form(NetCDF).It can be available from Figshare(https://doi.org/10.6084/m9.figshare.c.5823533)and ScienceDB(https://doi.org/10.57760/sciencedb.j00076.00103).展开更多
Remote sensing spatiotemporal fusion models blend multi-source images of different spatial resolutions to create synthetic images with high resolution and frequency,contributing to time series research where high qual...Remote sensing spatiotemporal fusion models blend multi-source images of different spatial resolutions to create synthetic images with high resolution and frequency,contributing to time series research where high quality observations are not available with sufficient frequency.However,existing models are vulnerable to spatial heterogeneity and land cover changes,which are frequent in human-dominated regions.To obtain quality time series of satellite images in a human-dominated region,this study developed the Modified Flexible Spatial-temporal Data Fusion(MFSDAF)approach based on the Flexible Spatial-temporal Data Fusion(FSDAF)model by using the enhanced linear regression(ELR).Multiple experiments of various land cover change scenarios were conducted based on both actual and simulated satellite images,respectively.The proposed MFSDAF model was validated by using the correlation coefficient(r),relative root mean square error(RRMSE),and structural similarity(SSIM),and was then compared with the Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model(ESTARFM)and FSDAF models.Results show that in the presence of significant land cover change,MFSDAF showed a maximum increase in r,RRMSE,and SSIM of 0.0313,0.0109 and 0.049,respectively,compared to FSDAF,while ESTARFM performed best with less temporal difference of in the input images.In conditions of stable landscape changes,the three performance statistics indicated a small advantage of MFSDAF over FSDAF,but were 0.0286,0.0102,0.0317 higher than for ESTARFM,respectively.MFSDAF showed greater accuracy of capturing subtle changes and created high-precision images from both actual and simulated satellite images.展开更多
China’s rapid economic development has initiated the deterioration of its ecological environment,posing a threat to the sustainable development of human society.As a result,an assessment of regional sustainability is...China’s rapid economic development has initiated the deterioration of its ecological environment,posing a threat to the sustainable development of human society.As a result,an assessment of regional sustainability is critical.This paper researches China’s most forested province,Fujian Province,as the study area.We proposed a grid-based approach to assess the regional carbon footprint in accordance with the Intergovernmental Panel on Climate Change’s(IPCC)carbon emission guidelines.Our method of assessment also introduced carbon emission indicators with our improved and published Net Primary Production(NPP)based on process simulation.The carbon footprint in Fujian Province from 2005-2017 was calculated and examined from a spatiotemporal perspective.Ecological indicators were used in the sustainability assessment.The research draws the following conclusions:1)the carbon footprint in the eastern regions of Fujian Province was higher due to rapid economic development;2)that of the western regions was lower;3)an uptrend in the carbon footprint of Fujian Province was observed.All five ecological indicators based on carbon emissions and economic and social data showed an ecologically unsustainable trend over 13 years in the research area due to unsustainable economic development.Therefore,it is urgent to balance the relationship between economic development and environmental protection.Our research provides scientific references for achieving ecological civilization and sustainability in a similar region.展开更多
Considering growing concerns regarding polluted estuaries and their adverse effects on public health,this study aimed to identify concentrations of metal (Zn,Fe,Cr,Ni,Cd,Mn,As,Cu,and Pb) in Asiatic clams sampled along...Considering growing concerns regarding polluted estuaries and their adverse effects on public health,this study aimed to identify concentrations of metal (Zn,Fe,Cr,Ni,Cd,Mn,As,Cu,and Pb) in Asiatic clams sampled along the Lower Min River,China.Multivariate methods were used to identify and apportion pollution sources.Noncarcinogenic and carcinogenic health risk assessments were performed to gauge adverse consumer health effects.Results showed that Cr,Pb,and Zn concentrations were higher than the limits prescribed in Chinese government guidelines.In comparison with concentrations of selected metals in other rivers,Cr,Pb,Zn,and As concentrations in clams were generally higher.Pollution assessment using the metal pollution index showed that sampling sites surrounding developing industrial and residential areas were the most polluted.Principal component analysis indicated significant anthropogenic metal contributions in clams.Health risk assessment indicated significant risk for clam consumers along the Lower Min River in terms of hazard quotient and carcinogenic risk and,thus,clam consumption from the study area should be avoided.The present findings would help in establishing environmental monitoring plans and contribute to preserving public health as well as the development of water conservation strategies to alleviate the metal pollution.展开更多
In the nucleus, chromatin is folded into hierarchical architecture that is tightly linked to various nuclear functions. However, the underlying molecular mechanisms that confer these architectures remain incompletely ...In the nucleus, chromatin is folded into hierarchical architecture that is tightly linked to various nuclear functions. However, the underlying molecular mechanisms that confer these architectures remain incompletely understood. Here, we investigated the functional roles of H3 lysine 9 dimethylation(H3 K9 me2), one of the abundant histone modifications, in three-dimensional(3 D)genome organization. Unlike in mouse embryonic stem cells, inhibition of methyltransferases G9 a and GLP in differentiated cells eliminated H3 K9 me2 predominantly at A-type(active) genomic compartments, and the level of residual H3 K9 me2 modifications was strongly associated with B-type(inactive) genomic compartments. Furthermore, chemical inhibition of G9 a/GLP in mouse hepatocytes led to decreased chromatin-nuclear lamina interactions mainly at G9 a/GLP-sensitive regions, increased degree of genomic compartmentalization, and up-regulation of hundreds of genes that were associated with alterations of the 3 D chromatin. Collectively, our data demonstrated essential roles of H3 K9 me2 in 3 D genome organization.展开更多
Dear Editor,In the nucleus of higher eukaryotes,chromatin occupies only a small proportion of the nuclear space,while many proteins and RNAs segregate into membrane-less nuclear bodies(NBs).These NBs follow a stochast...Dear Editor,In the nucleus of higher eukaryotes,chromatin occupies only a small proportion of the nuclear space,while many proteins and RNAs segregate into membrane-less nuclear bodies(NBs).These NBs follow a stochastic or ordered assembly model and constantly exchange components with the surrounding nucleoplasm(Jain et al.,2016).展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.41501361,41401385,30871965)the China Postdoctoral Science Foundation(No.2018M630728)+2 种基金the Open Fund of Fujian Provincial Key Laboratory of Resources and Environment Monitoring&Sustainable Management and Utilization(No.ZD1403)the Open Fund of Fujian Mine Ecological Restoration Engineering Technology Research Center(No.KS2018005)the Scientific Research Foundation of Fuzhou University(No.XRC1345)
文摘The construction of a pest detection algorithm is an important step to couple"ground-space"characteristics,which is also the basis for rapid and accurate monitoring and detection of pest damage.In four experimental areas in Sanming City,Jiangle County,Sha County and Yanping District in Fujian Province,sample data on pest damage in 182 sets of Dendrolimus punctatus were collected.The data were randomly divided into a training set and testing set,and five duplicate tests and one eliminating-indicator test were done.Based on the characterization analysis of the host for D.punctatus damage,seven characteristic indicators of ground and remote sensing including leaf area index,standard error of leaf area index(SEL)of pine forest,normalized difference vegetation index(NDVI),wetness from tasseled cap transformation(WET),green band(B2),red band(B3),near-infrared band(B4)of remote sensing image are obtained to construct BP neural networks and random forest models of pest levels.The detection results of these two algorithms were comprehensively compared from the aspects of detection precision,kappa coefficient,receiver operating characteristic curve,and a paired t test.The results showed that the seven indicators all were responsive to pest damage,and NDVI was relatively weak;the average pest damage detection precision of six tests by BP neural networks was 77.29%,the kappa coefficient was 0.6869 and after the RF algorithm,the respective values were 79.30%and 0.7151,showing that the latter is more optimized,but there was no significant difference(p>0.05);the detection precision,kappa coefficient and AUC of the RF algorithm was higher than the BP neural networks for three pest levels(no damage,moderate damage and severe damage).The detection precision and AUC of BP neural networks were a little higher for mild damage,but the difference was not significant(p>0.05)except for the kappa coefficient for the no damage level(p<0.05).An"over-fitting"phenomenon tends to occur in BP neural networks,while RF method is more robust,providing a detection effect that is better than the BP neural networks.Thus,the application of the random forest algorithm for pest damage and multilevel dispersed variables is thus feasible and suggests that attention to the proportionality of sample data from various categories is needed when collecting data.
基金funded by the General Program of the National Natural Science Foundationof China,No.31271090,31100728,90924013the Philosophy and Social Sciences Education Special-Program during the 12th Five-Year Plan Period of Shanghai City,No.2012JJY001the Whole Advancement Sociology Research Program of "985 Engineering" Phase III ofFudan University in China,No.2011SHKXZD008
文摘Episodic memories are composed of various interrelated elements, including those specific to items of central interest and those pertaining to related features, such as the color, shape, size, spatial location, temporal order, and media or modalities of presentation. Memory about a core item （such as a word, object, or picture） is called item memory while memory about the context or related fea- tures of a core item is defined as source memory. What determines which sources within an episode are successfully remembered is of particular interest to researchers. Behavioral evidence suggests that the orientation of a memory task influences whether the related source of the item will be re- membered later. This study explored changes in the hippocampus and prefrontal cortex while par- ticipants completed two tasks： an item-oriented task and a source-oriented task. We used functional MRI to investigate the neural mechanisms by which task orientation influences source encoding. We found that subsequent source memory effects in the right prefrontal cortex and hippocampus were modulated by task orientation, whereas task orientation modulated item memory effects in the prefrontal cortex. These findings highlight the possibility that the hippocampus contributes to the intentional encoding of item-source associations, whereas the prefrontal cortex is biased toward processing information to which attention is directed.
基金the National Science Foundation of China(Grant Nos.41871233,41371330 , 41001203).
文摘Background:Digital hemispherical photography(DHP)is widely used to estimate the leaf area index(LAI)of forest plots due to its advantages of high efficiency and low cost.A crucial step in the LAI estimation of forest plots via DHP is choosing a sampling scheme.However,various sampling schemes involving DHP have been used for the LAI estimation of forest plots.To date,the impact of sampling schemes on LAI estimation from DHP has not been comprehensively investigated.Methods:In this study,13 commonly used sampling schemes which belong to five sampling types(i.e.dispersed,square,cross,transect and circle)were adopted in the LAI estimation of five Larix principis-rupprechtii plots(25m×25 m).An additional sampling scheme(with a sample size of 89)was generated on the basis of all the sample points of the 13 sampling schemes.Three typical inversion models and four canopy element clumping index(Ωe)algorithms were involved in the LAI estimation.The impacts of the sampling schemes on four variables,including gap fraction,Ωe,effective plant area index(PAIe)and LAI estimation from DHP were analysed.The LAI estimates obtained with different sampling schemes were then compared with those obtained from litter collection measurements.Results:Large differences were observed for all four variable estimates(i.e.gap fraction,Ωe,PAIe and LAI)under different sampling schemes.The differences in impact of sampling schemes on LAI estimation were not obvious for the three inversion models,if the fourΩe algorithms,except for the traditional gap-size analysis algorithm were adopted in the estimation.The accuracy of LAI estimation was not always improved with an increase in sample size.Moreover,results indicated that with the appropriate inversion model,Ωe algorithm and sampling scheme,the maximum estimation error of DHP-estimated LAI at elementary sampling unit can be less than 20%,which is required by the global climate observing system,except in forest plots with extremely large LAI values(~>6.0).However,obtaining an LAI from DHP with an estimation error lower than 5%is impossible regardless of which combination of inversion model,Ωe algorithm and sampling scheme is used.Conclusion:The LAI estimation of L.principis-rupprechtii forests from DHP was largely affected by the sampling schemes adopted in the estimation.Thus,the sampling scheme should be seriously considered in the LAI estimation.One square and two transect sampling schemes(with sample sizes ranging from 3 to 9)were recommended to be used to estimate the LAI of L.principis-rupprechtii forests with the smallest mean relative error(MRE).By contrast,three cross and one dispersed sampling schemes were identified to provide LAI estimates with relatively large MREs.
基金the China meteorological forcing dataset.Thanks to the Natural Science Foundation of Fujian Province(No.2021J01627,No.2020J01465)the National Natural Science Foundation of China(No.41601562,No.32071776)for their financial support.
文摘Standardized Precipitation Index(SPI)and Standardized Precipitation Evapotranspiration Index(SPEI),traditionally derived at a monthly scale,are widely used drought indices.To overcome temporalresolution limitations,we have previously developed and published a well-validated daily SPI/SPEI in situ dataset.Although having a high temporal resolution,this in situ dataset presents low spatial resolution due to the scarcity of stations.Therefore,based on the China Meteorological Forcing Dataset,which is composed of data from more than 1,000 ground-based observation sites and multiple remote sensing grid meteorological dataset,we present the first high spatiotemporal-resolution daily SPI/SPEI raster datasets over China.It spans from 1979 to 2018,with a spatial resolution of 0.1°×0.1°,a temporal resolution of 1-day,and the timescales of 30-,90-,and 360-days.Results show that the spatial distributions of drought event characteristics detected by the daily SPI/SPEI are consistent with the monthly SPI/SPEI.The correlation between the daily value of the 12-month scale and the monthly value of SPI/SPEI is the strongest,with linear correlation,Nash-Sutcliffe coefficient,and normalized root mean square error of 0.98,0.97,and 0.04,respectively.The daily SPI/SPEI is shown to be more sensitive to flash drought than the monthly SPI/SPEI.Our improved SPI/SPEI shows high accuracy and credibility,presenting enhanced results when compared to the monthly SPI/SPEI.The total data volume is up to 150 GB,compressed to 91 GB in Network Common Data Form(NetCDF).It can be available from Figshare(https://doi.org/10.6084/m9.figshare.c.5823533)and ScienceDB(https://doi.org/10.57760/sciencedb.j00076.00103).
基金This research received financial support by the National Natural Science Foundation of China(Grant Nos.41601562 and 41761014)the National Key Research and Development Program of China(No.2017YFC1502404)+1 种基金the China Institute of Water Resources and Hydropower Research Team Construction and Talent Development Project(No.JZ0145B752017)the Research Project for Young Teachers of Fujian Province(No.JAT160085).
文摘Remote sensing spatiotemporal fusion models blend multi-source images of different spatial resolutions to create synthetic images with high resolution and frequency,contributing to time series research where high quality observations are not available with sufficient frequency.However,existing models are vulnerable to spatial heterogeneity and land cover changes,which are frequent in human-dominated regions.To obtain quality time series of satellite images in a human-dominated region,this study developed the Modified Flexible Spatial-temporal Data Fusion(MFSDAF)approach based on the Flexible Spatial-temporal Data Fusion(FSDAF)model by using the enhanced linear regression(ELR).Multiple experiments of various land cover change scenarios were conducted based on both actual and simulated satellite images,respectively.The proposed MFSDAF model was validated by using the correlation coefficient(r),relative root mean square error(RRMSE),and structural similarity(SSIM),and was then compared with the Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model(ESTARFM)and FSDAF models.Results show that in the presence of significant land cover change,MFSDAF showed a maximum increase in r,RRMSE,and SSIM of 0.0313,0.0109 and 0.049,respectively,compared to FSDAF,while ESTARFM performed best with less temporal difference of in the input images.In conditions of stable landscape changes,the three performance statistics indicated a small advantage of MFSDAF over FSDAF,but were 0.0286,0.0102,0.0317 higher than for ESTARFM,respectively.MFSDAF showed greater accuracy of capturing subtle changes and created high-precision images from both actual and simulated satellite images.
基金supported by the National Natural Science Foundation of China(Grant No.41601562)sponsored by China Scholarship Council(No.201806655014)+1 种基金the Research Project for Young Teachers of Fujian Province(No.JAT160085)the Scientific Research Foundation of Fuzhou University(No.XRC-1536).
文摘China’s rapid economic development has initiated the deterioration of its ecological environment,posing a threat to the sustainable development of human society.As a result,an assessment of regional sustainability is critical.This paper researches China’s most forested province,Fujian Province,as the study area.We proposed a grid-based approach to assess the regional carbon footprint in accordance with the Intergovernmental Panel on Climate Change’s(IPCC)carbon emission guidelines.Our method of assessment also introduced carbon emission indicators with our improved and published Net Primary Production(NPP)based on process simulation.The carbon footprint in Fujian Province from 2005-2017 was calculated and examined from a spatiotemporal perspective.Ecological indicators were used in the sustainability assessment.The research draws the following conclusions:1)the carbon footprint in the eastern regions of Fujian Province was higher due to rapid economic development;2)that of the western regions was lower;3)an uptrend in the carbon footprint of Fujian Province was observed.All five ecological indicators based on carbon emissions and economic and social data showed an ecologically unsustainable trend over 13 years in the research area due to unsustainable economic development.Therefore,it is urgent to balance the relationship between economic development and environmental protection.Our research provides scientific references for achieving ecological civilization and sustainability in a similar region.
基金the Natural Science Foundation of Fujian Province (Nos.2018J01745 and 2013J01045)the China Scholarship Council (No.201406655031)the Science and Technology Development Foundation of Fuzhou University (No.2013-XQ-19).
文摘Considering growing concerns regarding polluted estuaries and their adverse effects on public health,this study aimed to identify concentrations of metal (Zn,Fe,Cr,Ni,Cd,Mn,As,Cu,and Pb) in Asiatic clams sampled along the Lower Min River,China.Multivariate methods were used to identify and apportion pollution sources.Noncarcinogenic and carcinogenic health risk assessments were performed to gauge adverse consumer health effects.Results showed that Cr,Pb,and Zn concentrations were higher than the limits prescribed in Chinese government guidelines.In comparison with concentrations of selected metals in other rivers,Cr,Pb,Zn,and As concentrations in clams were generally higher.Pollution assessment using the metal pollution index showed that sampling sites surrounding developing industrial and residential areas were the most polluted.Principal component analysis indicated significant anthropogenic metal contributions in clams.Health risk assessment indicated significant risk for clam consumers along the Lower Min River in terms of hazard quotient and carcinogenic risk and,thus,clam consumption from the study area should be avoided.The present findings would help in establishing environmental monitoring plans and contribute to preserving public health as well as the development of water conservation strategies to alleviate the metal pollution.
基金supported by the National Key R&D Program of China(Grant No.2018YFC1003500 awarded to BW)the National Natural Science Foundation of China(Grant No.31771435 awarded to BW)
文摘In the nucleus, chromatin is folded into hierarchical architecture that is tightly linked to various nuclear functions. However, the underlying molecular mechanisms that confer these architectures remain incompletely understood. Here, we investigated the functional roles of H3 lysine 9 dimethylation(H3 K9 me2), one of the abundant histone modifications, in three-dimensional(3 D)genome organization. Unlike in mouse embryonic stem cells, inhibition of methyltransferases G9 a and GLP in differentiated cells eliminated H3 K9 me2 predominantly at A-type(active) genomic compartments, and the level of residual H3 K9 me2 modifications was strongly associated with B-type(inactive) genomic compartments. Furthermore, chemical inhibition of G9 a/GLP in mouse hepatocytes led to decreased chromatin-nuclear lamina interactions mainly at G9 a/GLP-sensitive regions, increased degree of genomic compartmentalization, and up-regulation of hundreds of genes that were associated with alterations of the 3 D chromatin. Collectively, our data demonstrated essential roles of H3 K9 me2 in 3 D genome organization.
文摘Dear Editor,In the nucleus of higher eukaryotes,chromatin occupies only a small proportion of the nuclear space,while many proteins and RNAs segregate into membrane-less nuclear bodies(NBs).These NBs follow a stochastic or ordered assembly model and constantly exchange components with the surrounding nucleoplasm(Jain et al.,2016).
