Studies on plant diversity are usually based on the total number of species in a community.However,few studies have examined species richness(SR)of different plant life forms in a community along largescale environmen...Studies on plant diversity are usually based on the total number of species in a community.However,few studies have examined species richness(SR)of different plant life forms in a community along largescale environmental gradients.Particularly,the relative importance(RIV)of different plant life forms in a community and how they vary with environmental variables are still unclear.To fill these gaps,we determined plant diversity of ephemeral plants,annual herbs,perennial herbs,and woody plants from 187 sites across drylands in China.The SR patterns of herbaceous plants,especially perennial herbs,and their RIV in plant communities increased with increasing precipitation and soil nutrient content;however,the RIV of annual herbs was not altered along these gradients.The SR and RIV of ephemeral plants were affected mainly by precipitation seasonality.The SR of woody plants had a unimodal relationship with air temperature and exhibited the highest RIV and SR percentage in plant communities under the harshest environments.An obvious shift emerged in plant community composition,SR and their critical impact factors at 238.5 mm of mean annual precipitation(MAP).In mesic regions(>238.5 mm),herbs were the dominant species,and the SR displayed a relatively slow decreasing rate with increasing aridity,which was mediated mainly by MAP and soil nutrients.In arid regions(<238.5 mm),woody plants were the dominant species,and the SR displayed a relatively fast decreasing rate with increasing aridity,which was mediated mainly by climate variables,especially precipitation.Our findings highlight the importance of comparative life form studies in community structure and biodiversity,as their responses to gradients differed substantially on a large scale.展开更多
Fusarium ear rot(FER),caused by Fusarium verticillioides,is a destructive fungal disease of maize.FER resistance is a complex,quantitatively inherited trait controlled by multiple minor-effect genes.In this study,we e...Fusarium ear rot(FER),caused by Fusarium verticillioides,is a destructive fungal disease of maize.FER resistance is a complex,quantitatively inherited trait controlled by multiple minor-effect genes.In this study,we employed two recombinant inbred line(RIL)populations with the common resistant parental line CML304 to identify FER-resistance loci.Initial QTL analysis identified 23 FER-resistance QTL,each explaining 5.21%-30.51%of the total phenotypic variation.Notably,one major QTL,qRfv2,on chromosome 2 was repeatedly detected,accounting for 11.92%-30.51%of the total phenotypic variation.qRfv2 was fine mapped to an interval of 1.01 Mb,flanked by the markers IDP8 and IDP10.qRfv2 is a semidominant resistance gene that could reduce the disease severity index(DSI)by 12.4%-20%,suggesting its potential for enhancing FER resistance in maize.Transcriptome analysis showed that 22 of the 28 annotated functional genes in the qRfv2 region displayed differential expression between parental lines in response to FER.One of the candidate genes,ZmLOX6,was validated to presumably provide a positive effect on FER resistance.Our study provides a basis for the potential cloning and application of FER resistance genes in maize breeding.展开更多
The future distribution of invading species depends on the climate space available and certain life history traits that facilitate invasion.Here,to predict the spread potential of plant species introduced in North Ame...The future distribution of invading species depends on the climate space available and certain life history traits that facilitate invasion.Here,to predict the spread potential of plant species introduced in North America north of Mexico(NAM),we compiled distribution and life history data(i.e.,seed size,life form,and photosynthetic pathways)for 3021 exotic plant species introduced to NAM.We comparatively examined the species’range size and climate space in both native and exotic regions and the role of key life history traits.We found that large climate space for most exotic plants is still available in NAM.The range sizes in global exotic regions could better predict the current range sizes in NAM than those in global native regions or global native plus exotic regions.C3 species had larger ranges on average than C4 and CAM plants,and herbaceous species consistently showed stronger relationships in range size between native and exotic regions than woody species,as was the case within the C3 species group.Seed size was negatively related to range size both in native regions and in NAM.However,seed size surprisingly showed a positive correlation with global exotic range size and no correlation with the current actual global(native plus exotic)range size.Our findings underline the importance of species’native distribution and life history traits in predicting the spread of exotic species.Future studies should continue to identify potential climate space and use underappreciated species traits to better predict species invasions under changing climate.展开更多
运用连续颗粒物采样仪（URG Model 2000-01J）对贵阳市城区大气颗粒物PM2.5进行了连续3个月（9-11月）的采集与分析,探讨了PM2.5的浓度分布特征、气象条件的影响。结果显示,贵阳市大气颗粒物PM2.5的平均质量浓度为53±27μg/m^3,变...运用连续颗粒物采样仪（URG Model 2000-01J）对贵阳市城区大气颗粒物PM2.5进行了连续3个月（9-11月）的采集与分析,探讨了PM2.5的浓度分布特征、气象条件的影响。结果显示,贵阳市大气颗粒物PM2.5的平均质量浓度为53±27μg/m^3,变化范围为3.7-186μg/m^3;初步推断大气颗粒物PM2.5的污染来源主要是燃料燃烧、生物质燃烧、汽车尾气等人为源;相对湿度、风速、风向、温度等气象条件是影响大气颗粒物浓度及分布的重要因素。展开更多
利用连续颗粒物采样仪（URG Model 2000-01 J）和黑碳仪（Aethalometer）对贵阳市城区2008年9—11月大气黑碳浓度进行了连续观测,结果表明,贵阳市城区秋冬季大气24h黑碳浓度变化范围为1.6~12μg.m-3,平均值为4.1μg.m-3;12 h黑碳浓度观...利用连续颗粒物采样仪（URG Model 2000-01 J）和黑碳仪（Aethalometer）对贵阳市城区2008年9—11月大气黑碳浓度进行了连续观测,结果表明,贵阳市城区秋冬季大气24h黑碳浓度变化范围为1.6~12μg.m-3,平均值为4.1μg.m-3;12 h黑碳浓度观测值主要分布在2~5μg.m-3,白昼黑碳浓度变化范围介于1.9~9.2μg.m-3,平均值3.9μg.m-3,夜间黑碳浓度变化范围0.48~15μg.m-3,平均值4.3μg.m-3;黑碳浓度与大气PM2.5浓度变化一致,呈正相关关系（r=0.84,P〈0.0001,n=178）,大气黑碳浓度的变化趋势还明显受相对湿度、温度和风速的影响。展开更多
Single-strand breaks （SSBs） can occur in cells either directly, or indirectly following initiation of base excision repair （BER）. SSBs generally have blocked termini lacking the conventional 5＇-phosphate and 3＇-...Single-strand breaks （SSBs） can occur in cells either directly, or indirectly following initiation of base excision repair （BER）. SSBs generally have blocked termini lacking the conventional 5＇-phosphate and 3＇-hydroxyl groups and require further processing prior to DNA synthesis and ligation. XRCC1 is devoid of any known enzymatic activity, but it can physically interact with other proteins involved in all stages of the overlapping SSB repair and BER pathways, including those that conduct the rate-limiting end-tailoring, and in many cases can stimulate their enzymatic activities. XRCC1^-/- mouse fibroblasts are most hypersensitive to agents that produce DNA lesions repaired by monofunctional glycosylase-initiated BER and that result in formation of indirect SSBs. A requirement for the deoxyribose phosphate lyase activity of DNA polymerase β （pol β） is specific to this pathway, whereas pol β is implicated in gap-filling during repair of many types of SSBs. Elevated levels of strand breaks, and diminished repair, have been demonstrated in MMS- treated XRCC1^-/-, and to a lesser extent in pol β^-/- cell lines, compared with wild-type cells. Thus a strong correlation is observed between cellular sensitivity to MMS and the ability of cells to repair MMS-induced damage. Exposure of wild-type and polβ^-/- cells to an inhibitor of PARP activity dramatically potentiates MMS-induced cytotoxicity. XRCC1^-/- cells are also sensitized by PARP inhibition demonstrating that PARP-mediated poly（ADP-ribosyl）ation plays a role in modulation of cytotoxicity beyond recruitment of XRCC 1 to sites of DNA damage.展开更多
Post-translational modification is central to protein stability and to the modulation of protein activity. Various types of protein modification, such as phosphorylation, methylation, acetylation, myristoylation, glyc...Post-translational modification is central to protein stability and to the modulation of protein activity. Various types of protein modification, such as phosphorylation, methylation, acetylation, myristoylation, glycosylation, and ubiquitination, have been reported. Among them, ubiquitination distinguishes itself from others in that most of the ubiquitinated proteins are targeted to the 26S proteasome for degradation. The ubiquitin/26S proteasome system constitutes the major protein degradation pathway in the cell. In recent years, the importance of the ubiquitination machinery in the control of numerous eukaryotic cellular functions has been increasingly appreciated. Increasing number of E3 ubiquitin ligases and their substrates, including a variety of essential cellular regulators have been identified. Studies in the past several years have revealed that the ubiquitination system is important for a broad range of plant developmental processes and responses to abiotic and biotic stresses. This review discusses recent advances in the functional analysis of ubiquitination-associated proteins from plants and pathogens that play important roles in plant-microbe interactions.展开更多
CONSORT声明被广泛用于提高随机对照临床试验的报告质量。Kenneth Schulz等对CONSORT声明的最新版本CONSORT2010作了详细说明,该版本基于新获得的方法学证据和经验的积累对报告指南作了更新。为了鼓励更多的人使用"CONSORT2010声明...CONSORT声明被广泛用于提高随机对照临床试验的报告质量。Kenneth Schulz等对CONSORT声明的最新版本CONSORT2010作了详细说明,该版本基于新获得的方法学证据和经验的积累对报告指南作了更新。为了鼓励更多的人使用"CONSORT2010声明",本文可从bmj.com免费获取,也将在Lancet,Obstetrics and Gynecology,PLoS Medicine,Annals of Internal Medicine,Open Medicine,Journal of Clinical Epidemiology,BMC Medicine和Trials等杂志发表。展开更多
The effect of sulfur dioxide （SO2） on the formation of polychlorinated dibenzo-p-dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs） has been studied in an entrained-flow reactor （EFR） under simulated wa...The effect of sulfur dioxide （SO2） on the formation of polychlorinated dibenzo-p-dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs） has been studied in an entrained-flow reactor （EFR） under simulated waste combustion conditions. A chlorination model based on conditional probability was employed to evaluate the homologue patterns of PCDDs and PCDFs. Results revealed that the presence of SO2 did not alter the formation pathway although SO2 suppressed PCDD/F formation. The prediction model of PCDF showed good agreement with the experimental data （R--0.95）, whereas the prediction for PCDDs did not correlate well with the experimental data. This may be explained because potential chlorination pathways play a significant role in PCDF formation, whereas PCDDs are mainly formed through condensation reactions. Furthermore, the result indicated that the steric hindrance during formation has more effects on PCDD than on PCDF due to the symmetric molecular structures of PCDDs.展开更多
基金supported by the National Key Research and Development Program of China(2023YFF0805602)National Natural Science Foundation of China(32225032,32001192,32271597)+1 种基金the Innovation Base Project of Gansu Province(2021YFF0703904)the Science and Technology Program of Gansu Province(24JRRA515,22JR5RA525,23JRRA1157).
文摘Studies on plant diversity are usually based on the total number of species in a community.However,few studies have examined species richness(SR)of different plant life forms in a community along largescale environmental gradients.Particularly,the relative importance(RIV)of different plant life forms in a community and how they vary with environmental variables are still unclear.To fill these gaps,we determined plant diversity of ephemeral plants,annual herbs,perennial herbs,and woody plants from 187 sites across drylands in China.The SR patterns of herbaceous plants,especially perennial herbs,and their RIV in plant communities increased with increasing precipitation and soil nutrient content;however,the RIV of annual herbs was not altered along these gradients.The SR and RIV of ephemeral plants were affected mainly by precipitation seasonality.The SR of woody plants had a unimodal relationship with air temperature and exhibited the highest RIV and SR percentage in plant communities under the harshest environments.An obvious shift emerged in plant community composition,SR and their critical impact factors at 238.5 mm of mean annual precipitation(MAP).In mesic regions(>238.5 mm),herbs were the dominant species,and the SR displayed a relatively slow decreasing rate with increasing aridity,which was mediated mainly by MAP and soil nutrients.In arid regions(<238.5 mm),woody plants were the dominant species,and the SR displayed a relatively fast decreasing rate with increasing aridity,which was mediated mainly by climate variables,especially precipitation.Our findings highlight the importance of comparative life form studies in community structure and biodiversity,as their responses to gradients differed substantially on a large scale.
基金financially funded by the National Natural Science Foundation of China(U2004205)the China Agricultural University-Syngenta Project.
文摘Fusarium ear rot(FER),caused by Fusarium verticillioides,is a destructive fungal disease of maize.FER resistance is a complex,quantitatively inherited trait controlled by multiple minor-effect genes.In this study,we employed two recombinant inbred line(RIL)populations with the common resistant parental line CML304 to identify FER-resistance loci.Initial QTL analysis identified 23 FER-resistance QTL,each explaining 5.21%-30.51%of the total phenotypic variation.Notably,one major QTL,qRfv2,on chromosome 2 was repeatedly detected,accounting for 11.92%-30.51%of the total phenotypic variation.qRfv2 was fine mapped to an interval of 1.01 Mb,flanked by the markers IDP8 and IDP10.qRfv2 is a semidominant resistance gene that could reduce the disease severity index(DSI)by 12.4%-20%,suggesting its potential for enhancing FER resistance in maize.Transcriptome analysis showed that 22 of the 28 annotated functional genes in the qRfv2 region displayed differential expression between parental lines in response to FER.One of the candidate genes,ZmLOX6,was validated to presumably provide a positive effect on FER resistance.Our study provides a basis for the potential cloning and application of FER resistance genes in maize breeding.
文摘The future distribution of invading species depends on the climate space available and certain life history traits that facilitate invasion.Here,to predict the spread potential of plant species introduced in North America north of Mexico(NAM),we compiled distribution and life history data(i.e.,seed size,life form,and photosynthetic pathways)for 3021 exotic plant species introduced to NAM.We comparatively examined the species’range size and climate space in both native and exotic regions and the role of key life history traits.We found that large climate space for most exotic plants is still available in NAM.The range sizes in global exotic regions could better predict the current range sizes in NAM than those in global native regions or global native plus exotic regions.C3 species had larger ranges on average than C4 and CAM plants,and herbaceous species consistently showed stronger relationships in range size between native and exotic regions than woody species,as was the case within the C3 species group.Seed size was negatively related to range size both in native regions and in NAM.However,seed size surprisingly showed a positive correlation with global exotic range size and no correlation with the current actual global(native plus exotic)range size.Our findings underline the importance of species’native distribution and life history traits in predicting the spread of exotic species.Future studies should continue to identify potential climate space and use underappreciated species traits to better predict species invasions under changing climate.
文摘运用连续颗粒物采样仪（URG Model 2000-01J）对贵阳市城区大气颗粒物PM2.5进行了连续3个月（9-11月）的采集与分析,探讨了PM2.5的浓度分布特征、气象条件的影响。结果显示,贵阳市大气颗粒物PM2.5的平均质量浓度为53±27μg/m^3,变化范围为3.7-186μg/m^3;初步推断大气颗粒物PM2.5的污染来源主要是燃料燃烧、生物质燃烧、汽车尾气等人为源;相对湿度、风速、风向、温度等气象条件是影响大气颗粒物浓度及分布的重要因素。
文摘利用连续颗粒物采样仪（URG Model 2000-01 J）和黑碳仪（Aethalometer）对贵阳市城区2008年9—11月大气黑碳浓度进行了连续观测,结果表明,贵阳市城区秋冬季大气24h黑碳浓度变化范围为1.6~12μg.m-3,平均值为4.1μg.m-3;12 h黑碳浓度观测值主要分布在2~5μg.m-3,白昼黑碳浓度变化范围介于1.9~9.2μg.m-3,平均值3.9μg.m-3,夜间黑碳浓度变化范围0.48~15μg.m-3,平均值4.3μg.m-3;黑碳浓度与大气PM2.5浓度变化一致,呈正相关关系（r=0.84,P〈0.0001,n=178）,大气黑碳浓度的变化趋势还明显受相对湿度、温度和风速的影响。
基金Financial support was provided by the following sources to convene a meeting of the CONSORT Group in Montebello Canada+9 种基金in January 2007:the American Society of Clinical OncologyBMJCanadian Institutes for Health ResearchJohnson & JohnsonThe LancetNordic Cochrane CentrePLoS Medicine UK Cochrane Centreand UK National Co-ordinating Centre for Research Methodology.DM is supported by a University of Ottawa Research Chair.国家重点基础研究发展计划(973计划)项目资助(No.2006CB504602)。
文摘背景:对于与随机对照试验(randomized controlled trial,RCT)有关的学术会议论文或期刊中发表的文章来说,清楚、明了、信息量充足的摘要是十分重要的,因为读者经常仅仅根据报告的摘要对一个临床试验作出评价。为此,我们需要对"临床试验报告的统一标准(Consolidated Standards of Reporting Trials,CONSORT)声明"进行扩充,制定一个期刊与学术会议论文摘要中报告RCT的必备条目清单。今后在任何期刊发表的论文或学术会议论文摘要中,作者对RCT结果的报告都要包含这些内容。方法与结果:我们根据现有的质量评价工具和基于经验的证据总结出一个条目清单。运用三轮修正式德尔菲法(modified-Delphi process)进行条目筛选。邀请共计109人参与电子网络调查,反馈率为61%。调查结果于2007年1月在加拿大蒙特贝罗举行的CONSORT小组会议中公布,与会的26人中有临床试验实施人员、统计学家、流行病学家以及生物医学编辑。经过讨论最终确定条目,随后对其进行修订以保证这些条目体现了会议期间以及会后的讨论思路。摘要CONSORT建议RCT报告的摘要需要有一个结构化的格式,其中应该包括具体的试验目的、试验设计(随机分配的方法、盲法或遮蔽等)、研究对象(对象描述、随机分组的样本量以及用于分析的样本量)、每组实施的干预、实施的干预对主要疗效结果的影响及其危害、试验结论、试验注册名称和编号以及资金来源。本文对每一条能够找到例子的纳入条目都配有良好报告范例、基本原理以及证据等,十分明了易懂,因此我们建议与清单同时使用。结论:摘要CONSORT旨在改善期刊与学术会议中发表的论文摘要的质量,这将有助于摘要提供详尽清晰的信息,这些信息能够帮助读者对试验的有效性和试验结果的适用性做出正确的评价。
文摘Single-strand breaks （SSBs） can occur in cells either directly, or indirectly following initiation of base excision repair （BER）. SSBs generally have blocked termini lacking the conventional 5＇-phosphate and 3＇-hydroxyl groups and require further processing prior to DNA synthesis and ligation. XRCC1 is devoid of any known enzymatic activity, but it can physically interact with other proteins involved in all stages of the overlapping SSB repair and BER pathways, including those that conduct the rate-limiting end-tailoring, and in many cases can stimulate their enzymatic activities. XRCC1^-/- mouse fibroblasts are most hypersensitive to agents that produce DNA lesions repaired by monofunctional glycosylase-initiated BER and that result in formation of indirect SSBs. A requirement for the deoxyribose phosphate lyase activity of DNA polymerase β （pol β） is specific to this pathway, whereas pol β is implicated in gap-filling during repair of many types of SSBs. Elevated levels of strand breaks, and diminished repair, have been demonstrated in MMS- treated XRCC1^-/-, and to a lesser extent in pol β^-/- cell lines, compared with wild-type cells. Thus a strong correlation is observed between cellular sensitivity to MMS and the ability of cells to repair MMS-induced damage. Exposure of wild-type and polβ^-/- cells to an inhibitor of PARP activity dramatically potentiates MMS-induced cytotoxicity. XRCC1^-/- cells are also sensitized by PARP inhibition demonstrating that PARP-mediated poly（ADP-ribosyl）ation plays a role in modulation of cytotoxicity beyond recruitment of XRCC 1 to sites of DNA damage.
文摘Post-translational modification is central to protein stability and to the modulation of protein activity. Various types of protein modification, such as phosphorylation, methylation, acetylation, myristoylation, glycosylation, and ubiquitination, have been reported. Among them, ubiquitination distinguishes itself from others in that most of the ubiquitinated proteins are targeted to the 26S proteasome for degradation. The ubiquitin/26S proteasome system constitutes the major protein degradation pathway in the cell. In recent years, the importance of the ubiquitination machinery in the control of numerous eukaryotic cellular functions has been increasingly appreciated. Increasing number of E3 ubiquitin ligases and their substrates, including a variety of essential cellular regulators have been identified. Studies in the past several years have revealed that the ubiquitination system is important for a broad range of plant developmental processes and responses to abiotic and biotic stresses. This review discusses recent advances in the functional analysis of ubiquitination-associated proteins from plants and pathogens that play important roles in plant-microbe interactions.
文摘CONSORT声明被广泛用于提高随机对照临床试验的报告质量。Kenneth Schulz等对CONSORT声明的最新版本CONSORT2010作了详细说明,该版本基于新获得的方法学证据和经验的积累对报告指南作了更新。为了鼓励更多的人使用"CONSORT2010声明",本文可从bmj.com免费获取,也将在Lancet,Obstetrics and Gynecology,PLoS Medicine,Annals of Internal Medicine,Open Medicine,Journal of Clinical Epidemiology,BMC Medicine和Trials等杂志发表。
基金United Kingdom National Institute for Health ResearchCanadian Institutes of Health Research+4 种基金Presidents FundCanadian Institutes of Health ResearchJohnson & JohnsonBMJthe American Society for Clinical Oncology
文摘大量证据显示随机对照临床试验(randomised controlled trial,RCT)的报告质量不理想。报告不透明,则读者既不能评判试验结果是否真实可靠,也不能从中提取可用于系统综述的信息。最近的方法学分析表明,报告不充分和设计不合理与对治疗效果产生评价偏倚有关。这种系统误差对RCT损害严重,而RCT正是以其能减少或避免偏倚而被视为评价干预措施的金标准。为了提高RCT的报告质量,一个由专家和编辑组成的工作组制定了临床试验报告的统一标准(Consolidated Standards of Reporting Trials,CONSORT)声明。CONSORT声明于1996年首次发表,并于2001年更新。声明由对照检查清单和流程图组成,供作者在报告RCT时使用。许多核心医学期刊和主要国际性编辑组织都已认可CONSORT声明。该声明促进了对RCT的严格评价和解释。2001年,在对CONSORT进行修订时,人们就已经清楚地认识到,解释和说明制定CONSORT声明的原理,有助于研究人员等撰写或评价临床试验报告。一篇CONSORT说明与详述文章于2001年同2001版CONSORT声明一起发表。2007年1月的专家会议之后,对CONSORT声明作了进一步修订并已发表,即"CONSORT2010声明"。这次更新对原版对照检查清单作了文字上的修改,使其更为明晰,并收入了与一些新近才认识到的主题相关的建议,如选择性报告结局产生的偏倚。说明与详述文件旨在加强人们对CONSORT声明的理解、应用和传播,这次也作了大量修订,对每一项新增或更新的清单条目的含义和增改理由进行了解释,提供了优秀的报告实例,还尽可能地提供了相关的经验性研究的参考文献。文中收入了若干流程图实例。"CONSORT2010声明"、其说明与详述文件,以及相关网站(www.consort-statement.org),对于改进随机临床试验报告必将有所裨益。
基金Project supported by the China Scholarship Council Foundation (2003) the National Natural Science Foundation of China (No. 50576082).
文摘The effect of sulfur dioxide （SO2） on the formation of polychlorinated dibenzo-p-dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs） has been studied in an entrained-flow reactor （EFR） under simulated waste combustion conditions. A chlorination model based on conditional probability was employed to evaluate the homologue patterns of PCDDs and PCDFs. Results revealed that the presence of SO2 did not alter the formation pathway although SO2 suppressed PCDD/F formation. The prediction model of PCDF showed good agreement with the experimental data （R--0.95）, whereas the prediction for PCDDs did not correlate well with the experimental data. This may be explained because potential chlorination pathways play a significant role in PCDF formation, whereas PCDDs are mainly formed through condensation reactions. Furthermore, the result indicated that the steric hindrance during formation has more effects on PCDD than on PCDF due to the symmetric molecular structures of PCDDs.
