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Nanoscale resetting of the Th/Pb system in an isotopically-closed monazite grain: A combined atom probe and transmission electron microscopy study

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Geoscience Frontiers 2019年第1期10卷 65-76页

作者： A.-M.Seydoux-Guillaume D.Fougerouse A.T.Laurent E.Gardés S.M.Reddy D.W.Saxey Univ Lyon UJM-Saint-Etienne CNRS IRD CNRS Université Clermont Auvergne School of Earth and Planetary Sciences Curtin University Geoscience Atom Probe Advanced Resource Characterisation Facility John de Laeter Centre Curtin University Centre de recherche sur les Ions les Matériaux et la Photonique (CIMAP) Department of Physics and Astronomy Curtin University

Understanding the mechanisms of parent-daughter isotopic mobility at the nanoscale is key to rigorous interpretation of Ue The Pb data and associated dating. Until now, all nanoscale geochronological studies on geological samples have relied on either Transmission Electron Microscope(TEM) or Atom Probe Microscopy(APM) characterizations alone, thus suffering from the respective weaknesses of each technique. Here we focus on monazite crystals from a ~1 Ga, ultrahigh temperature granulite from Rogaland(Norway). This sample has recorded concordant UeP b dates(measured by LA-ICP-MS) that range over 100 My, with the three domains yielding distinct isotopic Ue Pb ages of 1034 ± 6 Ma(D1; Srich core), 1005 ± 7 Ma(D2), and 935 ± 7 Ma(D3), respectively. Combined APM and TEM characterization of these monazite crystals reveal phase separation that led to the isolation of two different radiogenic Pb(Pb*) reservoirs at the nanoscale. The S-rich core of these monazite crystals contains Cae Srich clusters, 5 -10 nm in size, homogenously distributed within the monazite matrix with a mean interparticle distance of 40 -60 nm. The clusters acted as a sink for radiogenic Pb(Pb*) produced in the monazite matrix, which was reset at the nanoscale via Pb diffusion while the grain remained closed at the micro-scale. Compared to the concordant ages given by conventional micro-scale dating of the grain,the apparent nano-scale age of the monazite matrix in between clusters is about 100 Myr younger, which compares remarkably well to the duration of the metamorphic event. This study highlights the capabilities of combined APM-TEM nano-structural and nano-isotopic characterizations in dating and timing of geological events, allowing the detection of processes untraceable with conventional dating methods.

关键词： Monazite Nanoscale resetting Nano-clusters APM TEM UHT metamorphism

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Distinct roles of H3K27me3 and H3K36me3 in vernalization response,maintenance,and resetting in winter wheat

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Science China(Life Sciences) 2024年第10期67卷 2251-2266页

作者： Xuemei Liu Min Deng Bingxin Shi Kehui Zhu Jinchao Chen Shujuan Xu Xiaomin Bie Xiansheng Zhang Xuelei Lin Jun Xiao Key Laboratory of Plant Cell and Chromosome Engineering Institute of Genetics and Developmental BiologyChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Institute of Science and Technology Austria(ISTA) Klosterneuburg 3400Austria National Key Laboratory of Wheat Improvement College of Life SciencesShandong Agricultural UniversityTai’an 271018China Centre of Excellence for Plant and Microbial Science(CEPAMS) JIC-CASBeijing 100101China

Winter plants rely on vernalization,a crucial process for adapting to cold conditions and ensuring successful ***,understanding the role of histone modifications in guiding the vernalization process in winter wheat remains *** this study,we investigated the transcriptome and chromatin dynamics in the shoot apex throughout the life cycle of winter wheat in the *** core histone modifications,H3K27me3 and H3K36me3,exhibited opposite patterns on the key vernalization gene VERNALIZATION1(VRN1),correlating with its induction during cold ***,the H3K36me3 level remained high at VRN1 after cold exposure,which may maintain its active *** in FERTILIZATION-INDEPENDENT ENDOSPERM(TaFIE)and SET DOMAIN GROUP 8/EARLY FLOWERING IN SHORT DAYS(TaSDG8/TaEFS),components of the writer complex for H3K27me3 and H3K36me3,respectively,affected flowering ***,VRN1 lost its high expression after the cold exposure memory in the absence of *** embryo development,VRN1 was silenced with the removal of active histone modifications in both winter and spring wheat,with selective restoration of H3K27me3 in winter *** mutant of Tafie-cr-87,a component of H3K27me3“writer”complex,did not influence the silence of VRN1during embryo development,but rather attenuated the cold exposure requirement of winter *** gene expression with H3K27me3 and H3K36me3 patterns identified potential regulators of *** study unveils distinct roles of H3K27me3 and H3K36me3 in controlling vernalization response,maintenance,and resetting in winter wheat.

关键词： vernalization H3K27me3 H3K36me3 winter wheat resetting maintenance

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resetting OF Sm-Nd ISOTOPIC SYSTEM AMONG MINERALS——DISCOVERY FROM DATING OF CHENCAI GROUP

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Chinese Science Bulletin 1992年第9期37卷 764-767页

作者：凌洪飞章邦桐沈渭洲刘继顺杨杰东陶仙聪 Department of Earth Sciences Nanjing University Nanjingv210008 PRC Department of Geology Central-South Industry University Changsha 410083 PRC Modern Analysis Centre Nanjing University Nanjing 210008 PRC

The original rock formation age and metamorphic history of Chencai Group are one of the keys to understanding tectonics and early crustal evolution of Zhejiang and Fujian provinces. For the purpose of obtaining the original rock formation age and metamorphic age, Sm-Nd and Rb-Sr isotopic compositions of metamorphic rocks and minerals were determined. Although only the metamorphic age was obtained, Sm-Nd isotopic system resetting among minerals under amphibolite facies metamorphism was discovered, which is of significance for Sm-Nd chronology of metamorphic rocks.

关键词： whole-rock Rb-Sr isochron mineral Sm-Nd isochron Sm-Nd isotopic system resetting amphibolite facies metamorphism

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