The End-Permian mass extinction(EPME),Earth’s most severe biocrisis,occurred proximal to the Permian-Triassic Boundary(PTB),with marine ecosystems experiencing catastrophic collapse.This study employs stable carbon(...The End-Permian mass extinction(EPME),Earth’s most severe biocrisis,occurred proximal to the Permian-Triassic Boundary(PTB),with marine ecosystems experiencing catastrophic collapse.This study employs stable carbon(δ^(13)C)and oxygen isotopes from marine carbonates in the Haidai Section(Xuanwei,northeastern Yunnan)to decipher paleoenvironmental drivers.The well-preserved stratigraphic sequence encompasses the Upper Permian(Yangxin and Xuanwei Formations)transitioning into the Lower Triassic(Feixianguan and Jialingjiang Formations),providing a continuous marine sedimentary archive.A marked negativeδ^(13)C excursion(-9.66‰V-PDB)occurs at the PTB,initiating from+0.82‰with subsequent gradual recovery.This geochemical signature correlates with:90%reduction in primary productivity Biodiversity collapse exhibiting cluster extinction patterns Prolonged suppression of ecological recovery Concurrently,reconstructed seawater temperatures reveal extreme thermal fluctuations,surging from 23℃to 32℃at the PTB before precipitously declining to 16℃.These perturbations demonstrate coupled biogeochemical dynamics wherein:•Carbon cycle destabilization disrupted nutrient fluxes.•Temperature oscillations exceeded marine taxa thermal tolerances.•Synergistic environmental stresses amplified extinction selectivity.Theδ^(13)C-temperature covariance(r^(2)=0.085)establishes mechanistic linkages between physicochemical perturbations and biotic responses.Our findings demonstrate that the EPME was driven by positive feedback loops in which:Volcanic CO₂emissions triggered carbonate saturation decline Thermal stratification exacerbated anoxia Biogeochemical cycling perturbations suppressed primary producers This integrated geochemical record from the Haidai Section provides critical insights into environment-organism coevolution during Phanerozoic Earth’s most profound mass extinction.展开更多
目的:研究在非小细胞肺癌及癌旁组织中ceacam1通过选择性拼接而产生的两种转录产物的调控机制。方法:将用PCR方法获得ceacam1基因中从内含子5至外显子8长1 606 bp DNA片段插入到真核表达载体pCMV中,构建成ceacam1迷你基因模型并与ptb基...目的:研究在非小细胞肺癌及癌旁组织中ceacam1通过选择性拼接而产生的两种转录产物的调控机制。方法:将用PCR方法获得ceacam1基因中从内含子5至外显子8长1 606 bp DNA片段插入到真核表达载体pCMV中,构建成ceacam1迷你基因模型并与ptb基因共转染,用PCR法鉴定转染后的产物变化;根据外显子7序列设计的探针GAE(16-nt)及ACE(8-nt)进行凝胶阻滞分析实验。分离与探针结合的蛋白并进行质谱分析。结果:ptb3种cDNA与ceacam1迷你基因共转染后,CEACAM lL表达水平下降,其中ptb4对迷你基因的表达产物影响最大。仅转染迷你基因的细胞中ceacam1L在两条带中所占比例为76.7%,而与ptb3种重组质粒共转染后,比例分别下降至58.3%、64.8%和54.0%。凝胶阻滞实验表明,探针GAE能与核蛋白结合,而ACE基本不能与核蛋白结合,与GAE结合的蛋白经质谱分析为PTB。结论:PTB过表达与ceacam1低表达有明显的相关性,拼接因子PTB参与ceacam1的选择性拼接。展开更多
基金supported by the Scientific Research Fund of the Education Department of Yunnan Province(Grant Number:2019J0488).
文摘The End-Permian mass extinction(EPME),Earth’s most severe biocrisis,occurred proximal to the Permian-Triassic Boundary(PTB),with marine ecosystems experiencing catastrophic collapse.This study employs stable carbon(δ^(13)C)and oxygen isotopes from marine carbonates in the Haidai Section(Xuanwei,northeastern Yunnan)to decipher paleoenvironmental drivers.The well-preserved stratigraphic sequence encompasses the Upper Permian(Yangxin and Xuanwei Formations)transitioning into the Lower Triassic(Feixianguan and Jialingjiang Formations),providing a continuous marine sedimentary archive.A marked negativeδ^(13)C excursion(-9.66‰V-PDB)occurs at the PTB,initiating from+0.82‰with subsequent gradual recovery.This geochemical signature correlates with:90%reduction in primary productivity Biodiversity collapse exhibiting cluster extinction patterns Prolonged suppression of ecological recovery Concurrently,reconstructed seawater temperatures reveal extreme thermal fluctuations,surging from 23℃to 32℃at the PTB before precipitously declining to 16℃.These perturbations demonstrate coupled biogeochemical dynamics wherein:•Carbon cycle destabilization disrupted nutrient fluxes.•Temperature oscillations exceeded marine taxa thermal tolerances.•Synergistic environmental stresses amplified extinction selectivity.Theδ^(13)C-temperature covariance(r^(2)=0.085)establishes mechanistic linkages between physicochemical perturbations and biotic responses.Our findings demonstrate that the EPME was driven by positive feedback loops in which:Volcanic CO₂emissions triggered carbonate saturation decline Thermal stratification exacerbated anoxia Biogeochemical cycling perturbations suppressed primary producers This integrated geochemical record from the Haidai Section provides critical insights into environment-organism coevolution during Phanerozoic Earth’s most profound mass extinction.
文摘目的:研究在非小细胞肺癌及癌旁组织中ceacam1通过选择性拼接而产生的两种转录产物的调控机制。方法:将用PCR方法获得ceacam1基因中从内含子5至外显子8长1 606 bp DNA片段插入到真核表达载体pCMV中,构建成ceacam1迷你基因模型并与ptb基因共转染,用PCR法鉴定转染后的产物变化;根据外显子7序列设计的探针GAE(16-nt)及ACE(8-nt)进行凝胶阻滞分析实验。分离与探针结合的蛋白并进行质谱分析。结果:ptb3种cDNA与ceacam1迷你基因共转染后,CEACAM lL表达水平下降,其中ptb4对迷你基因的表达产物影响最大。仅转染迷你基因的细胞中ceacam1L在两条带中所占比例为76.7%,而与ptb3种重组质粒共转染后,比例分别下降至58.3%、64.8%和54.0%。凝胶阻滞实验表明,探针GAE能与核蛋白结合,而ACE基本不能与核蛋白结合,与GAE结合的蛋白经质谱分析为PTB。结论:PTB过表达与ceacam1低表达有明显的相关性,拼接因子PTB参与ceacam1的选择性拼接。
