The Mg-carbonate-Fe interaction:Implication for the fate of subducted carbonates and formation of diamond in the lower mantle

The fate of subducted carbonates in the lower mantle and at the core-mantle boundary was modelled via experiments in the MgCO3-Fe^0 system at 70-150 GPa and 800-2600 Kin a laser-heated diamond anvil cell.Using in situ synchrotro n X-ray diffraction and ex situ transmission electron microscopy we show that the reduction of Mg-carbonate can be exemplified by:6 MgCO3+19 Fe=8 FeO+10(Mg0.6Fe^0.4)O+Fe7 C3+3 C.The presented results suggest that the interaction of carbonates with Fe^0 or Fe^0-bearing rocks can produce Fe-carbide and diamond,which can accumulate in the D"region,depending on its carbon to Fe ratio.Due to the sluggish kinetics of the transformation,diamond can remain metastable at the core-mantle boundary(CMB)unless it is in a direct contact with Fe-metal.In addition,it can be remobilized by redox melting accompanying the generation of mantle plumes.

Deep Volatiles as the Key for Energy and Environments of the Four-Dimensional Earth System

Carbon, hydrogen, oxygen, nitrogen, sulfur, and their compounds are volatile components that dominate the thin and fragile atmosphere, hydrosphere, and biosphere on Earth’s habitable surface. However, the vast majority of these volatiles are hidden in the deep interior, where the high pressure–temperature conditions drastically and categorically alter the physics and chemistry of the volatiles. Like the bloodstream of an organism, the circulations and interactions of volatiles in the deep Earth modulate climate, resources, energy, natural hazards, and other factors that define the Earth as a unique living and changing planet.

Tppp3~+synovial/tendon sheath progenitor cells contribute to heterotopic bone after trauma

Heterotopic ossification(HO)is a pathological process resulting in aberrant bone formation and often involves synovial lined tissues.During this process,mesenchymal progenitor cells undergo endochondral ossification.Nonetheless,the specific cell phenotypes and mechanisms driving this process are not well understood,in part due to the high degree of heterogeneity of the progenitor cells involved.Here,using a combination of lineage tracing and single-cell RNA sequencing(sc RNA-seq),we investigated the extent to which synovial/tendon sheath progenitor cells contribute to heterotopic bone formation.For this purpose,Tppp3(tubulin polymerization-promoting protein family member 3)-inducible reporter mice were used in combination with either Scx(Scleraxis)or Pdgfra(platelet derived growth factor receptor alpha)reporter mice.Both tendon injury-and arthroplasty-induced mouse experimental HO models were utilized.Sc RNA-seq of tendon-associated traumatic HO suggested that Tppp3 is an early progenitor cell marker for either tendon or osteochondral cells.Upon HO induction,Tppp3 reporter^(+)cells expanded in number and partially contributed to cartilage and bone formation in either tendon-or joint-associated HO.In double reporter animals,both Pdgfra^(+)Tppp3^(+)and Pdgfra^(+)Tppp3^(-) progenitor cells gave rise to HO-associated cartilage.Finally,analysis of human samples showed a substantial population of TPPP3^(-) expressing cells overlapping with osteogenic markers in areas of heterotopic bone.Overall,these data demonstrate that synovial/tendon sheath progenitor cells undergo aberrant osteochondral differentiation and contribute to HO after trauma.

基于图像相减和随机森林的AST3巡天暂现源及变源搜寻方法

AST3-2(Antarctic Survey Telescopes)光学巡天望远镜位于南极大陆最高点冰穹A,其产生的大量观测数据对数据处理的效率提出了较高要求.同时南极通信不便,数据回传有诸多困难,有必要在南极本地实现自动处理AST3-2观测数据,进行变源和暂现源观测的数据处理,但是受到低功耗计算机的限制,数据的快速自动处理的实现存在诸多困难.将已有的图像相减方案同机器学习算法相结合,并利用AST3-22016年观测数据作为测试样本,发展一套的暂现源及变源的筛选方法成为可行的选择.该筛选方法使用图像相减法初步筛选出可能的变源,再用主成分分析法抽取候选源的特征,并选择随机森林作为机器学习分类器,在测试中对正样本的召回率达到了97%,验证了这种方法的可行性,并最终在2016年观测数据中探测出一批变星候选体.

A 32-million year cycle detected in sea-level fluctuations over the last 545 Myr

Spectral analyses of past relative sea-level oscillations as represented by the ages of 57 Phanerozoic(the last 545 Myr)stratigraphic sequence boundaries from the Canadian Arctic show a strong spectral peak at 32 Myr(>99.9%confidence).These findings concur with previous reports of significant cycles with periods of around 30 Myr in various records of fluctuations of sea level,and in potentially related episodes of tectonism,volcanism,climate,and biotic extinctions.Sequence boundaries commonly coincide with stage boundaries based on biostratigraphy,and are correlated with episodes of extinction and times of flood-basalt volcanism.The connection between tectonics and sea-level variations may come from changes in rates of ocean-floor spreading and subduction,intraplate stresses from plate-reorganizations,and pulsations of hotspot volcanism.These coordinated periodic fluctuations in tectonics,sea level and climate may be modulated by cyclical activity in the Earth’s mantle,although some pacing by astronomical cycles is suspected.

Data-Driven Discovery in Mineralogy: Recent Advances in Data Resources, Analysis, and Visualization

Large and growing data resources on the diversity, distribution, and properties of minerals are ushering in a new era of data-driven discovery in mineralogy. The most comprehensive international mineral database is the IMA database, which includes information on more than 5400 approved mineral species and their properties, and the mindat.org data source, which contains more than 1 million species/locality data on minerals found at more than 300 000 localities. Analysis and visualization of these data with diverse techniques—including chord diagrams, cluster diagrams, Klee diagrams, skyline diagrams, and varied methods of network analysis—are leading to a greater understanding of the co-evolving geosphere and biosphere. New data-driven approaches include mineral evolution, mineral ecology, and mineral network analysis—methods that collectively consider the distribution and diversity of minerals through space and time. These strategies are fostering a deeper understanding of mineral co-occurrences and, for the first time, facilitating predictions of mineral species that occur on Earth but have yet to be discovered and described.

A pulse of the Earth: A 27.5-Myr underlying cycle in coordinated geological events over the last 260 Myr

We performed spectral analyses on the ages of 89 well-dated major geological events of the last 260 Myr from the recent geologic literature. These events include times of marine and non-marine extinctions,major ocean-anoxic events, continental flood-basalt eruptions, sea-level fluctuations, global pulses of intraplate magmatism, and times of changes in seafloor-spreading rates and plate reorganizations. The aggregate of all 89 events shows ten clusters in the last 260 Myr, spaced at an average interval of ~ 26.9 Myr, and Fourier analysis of the data yields a spectral peak at 27.5 Myr at the ≥96% confidence level. A shorter period of ~ 8.9 Myr may also be significant in modulating the timing of geologic events.Our results suggest that global geologic events are generally correlated, and seem to come in pulses with an underlying ~ 27.5-Myr cycle. These cyclic pulses of tectonics and climate change may be the result of geophysical processes related to the dynamics of plate tectonics and mantle plumes, or might alternatively be paced by astronomical cycles associated with the Earth’s motions in the Solar System and the Galaxy.

Optical system research of multi-object fiber spectroscopic survey telescope

In the first part of this paper,four different Cassegrain optical systems with their correctors are designed and studied for multi-object fiber slit spectroscopic survey.The aperture in 6.5 m and field of view 3°are taken for these optical systems.Assuming observation wavelength range is 0.365-0.95μm,the maximum zenith distance for observing is 60°,the maximum diameter of these lenses is 1.66 m,the altitude of the telescope site is 2500 m,two correctors are composed of 4-piece lenses and the other two are 5-piece lenses.The results obtained are:f-ratio about 3.7,the image quality for all four systems with EE80D≤0.60″,the linear diameter of the focal surface is about 1.2 m and 11 000 fibers can be set on it.Considering the limit of size of fused silica and optical glass,the maximum diameter for lens is about 1.7 m.Such a 6.5 m telescope is about the largest one if using the above correctors.Considering the multiobject spectroscopic survey is greatly important,we also studied some telescope optical systems having their aperture near or larger than 10 m used for the multi-object fiber spectroscopic survey.Such ideas are introduced in the last section of this paper.

Zircon O isotope composition of Sepon Au-Cu deposit, Laos

1.Objective The Sepon Au-Cu deposit(Fig.1)is the largest polymetal deposit ever discovered in Laos,of which the resources of gold and copper is 102 t(Au:1.6 g/t)and 1.96×10^6 t(TCu:2%)(Zhu HP et al.,2013)respectively.Sepon Au-Cu deposit is one of the most important super large deposits of the Truong Son Fold Belt.The Truong Son Fold Belt,located at the northeastern margin of the Indo-China terrane,is considered to be tectonically linked to the subduction of the Paleotethys Ocean and subsequent collision.The granodiorite porphyry samples from the Sepon deposit belong to I-type calc-alkaline series and tectonic settings are continental arc environment(Cromie PW,2010).LA-ICP MS zircon U-Pb dating results show that granodiorite porphyry samples from the Sepon deposit have ages of 302.1±2.9 Ma.The in situ zirconεHf(t)values range from+4.32 to+9.64,and TDM2(Hf)has an average age of 914 Ma(Wang XY et al.,2018).In this study,the authors present new in situ zircon oxygen isotopic data to identify the source of the magma.

Application of Advanced Analytics and Visualization in Mineral Systems

The key to answering many compelling and complex questions in Earth,planetary,and life science lies in breaking down the barriers between scientific fields and harnessing the integrated,multi-disciplinary power of Earth,planetary,and bioscience data resources.We have a unique opportunity to integrate large and rapidly expanding"big data"resources,to enlist powerful analytical and visualization methods,and to answer multi-disciplinary questions that cannot be addressed by one field alone.

Correlation of the largest craters,stratigraphic impact signatures,and extinction events over the past 250 Myr

The six largest known impact craters of the last 250 Myr(≥70 km in diameter),which are capable of causing significant environmental damage,coincide with four times of recognized extinction events at 36(with 2 craters),66,and 145 Myr ago,and possibly with two provisional extinction events at 168 and215 Myr ago.These impact cratering events are accompanied by layers in the geologic record interpreted as impact ejecta.Chance occurrences of impacts and extinctions can be rejected at confidence levels of99.96%(for 4 impact/extinctions)to 99.99%(for 6 impact/extinctions).These results argue that several extinction events over the last 250 Myr may be related to the effects of large-body impacts.

The Deep Carbon Observatory: A Ten-Year Quest to Study Carbon in Earth

1. Overview The Deep Carbon Observatory (DCO) is a ten-year research program to investigate the quantities, movements, forms, and origins of carbon in Earth. More than 90% of Earth’s carbon may reside in the planet’s deep interior, and DCO’s overarching mission is to understand Earth’s entire carbon cycle—beyond the atmosphere, oceans, and shallow crustal environments, which have drawn most previous research attention—to include the deep carbon cycle [1,2]. A decade of focused research has led to major discoveries by DCO scientists on the physical, chemical, and biological roles of carbon in Earth.

Elasticity of high-pressure clinoenstatite under mantle conditions:Implications for the origin of the X-discontinuity

The X-discontinuity is characterized by 2–8% wave impedance contrasts and indistinguishable seismological Clapeyron slopes. Its origin is not yet entirely understood and attributed to a variety of plausible causes, among which the coesite-stishovite transition is a popular mechanism due to its large impedance contrasts. However, the sole coesite-stishovite transition is insufficient to explain indistinguishable seismological Clapeyron slopes of the X-discontinuity. The orthopyroxene(OPX) to high-pressure clinopyroxene(HPCPX) transition has been excluded as a candidate mechanism in recent seismic studies because it can only cause small impedance contrasts based on the first-order estimate from the Birch’s law without direct sound velocity measurements. In this study, we performed first-principles calculations to obtain the elasticity of high-pressure clinoenstatite at high pressure and temperature. Our results show that the impedance contrast caused by the OPX-HPCPX transition is ~5.7% for P wave and ~6.9% for S wave, which are much larger than the previous empirical estimation and hence cannot be ignored. Given that eclogite is subject to partial melting in hot or wet regions, which will promote the enrichment of orthopyroxene by consuming silica, we suggested that both the coesite-stishovite transition and the OPX-HPCPX transition may be dominant mechanisms for the X-discontinuity, with the former dominating where eclogite is hard to melt and the latter dominating where partial melting of eclogite occurs. The model is consistent with seismological observations, indicating the important role of the OPX-HPCPX transition in the X-discontinuity and extensive occurrence of partial melting of eclogite. The proposed origin of the X-discontinuity provides a plausible way to illuminate the melting situation of eclogite in the deep earth.

Microtubules Are Essential for Guard-Cell Function in Vicia and Arabidopsis

Radially arranged cortical microtubules are a prominent feature of guard cells. Guard cells expressing GFP- tubulin showed consistent changes in the appearance of microtubules when stomata opened or closed. Guard cells showed fewer microtubule structures as stomata closed, whether induced by transfer to darkness, ABA, hydrogen per- oxide, or sodium hydrogen carbonate. Guard cells kept in the dark （closed stomata） showed increases in microtubule struc- tures and stomatal aperture on light treatment. GFP-EB1, marking microtubule growing plus ends, showed no change in number of plus ends or velocity of assembly on stomatal closure. Since the number of growing plus ends and the rate of plus-end growth did not change when microtubule structure numbers declined, microtubule instability and/or rearrange- ment must be responsible for the apparent loss of microtubules. Guard cells with closed stomata showed more cytosolic GFP-fluorescence than those with open stomata as cortical microtubules became disassembled, although with a large net loss in total fluorescence. Microtubule-targeted drugs blocked guard-cell function in Vicia and Arabidopsis. Oryzalin dis- rupted guard-cell microtubules and prevented stomatal opening and taxol stabilized guard-cell microtubules and delayed stomatal closure. Gas exchange measurements indicated that the transgenes for fluorescent-labeled proteins did not dis- rupt normal stomatal function. These dynamic changes in guard-cell microtubules combined with our inhibitor studies provide evidence for an active role of microtubules in guard-cell function.

Proteomics Analysis Reveals Post-Translational Mechanisms for Cold-Induced Metabolic Changes in Arabidopsis

Cold-induced changes of gene expression and metabolism are critical for plants to survive freezing. Largely by changing gene expression, exposure to a period of non-freezing low temperatures increases plant tolerance to freezing--a phenomenon known as cold acclimation. Cold also induces rapid metabolic changes, which provide instant protection before temperature drops below freezing point. The molecular mechanisms for such rapid metabolic responses to cold remain largely unknown. Here, we use two-dimensional difference gel electrophoresis （2-D DIGE） analysis of sub-cellular fractions ofArabidopsis thaliana proteome coupled with spot identification by tandem mass spectrometry to identify early cold-responsive proteins in Arabidopsis. These proteins include four enzymes involved in starch degradation, three HSP100 proteins, several proteins in the tricarboxylic acid cycle, and sucrose metabolism. Upon cold treatment, the Disproportio- nating Enzyme 2 （DPE2）, a cytosolic transglucosidase metabolizing maltose to glucose, increased rapidly in the centrifugation pellet fraction and decreased in the soluble fraction. Consistent with cold-induced inactivation of DPE2 enzymatic activity, the dpe2 mutant showed increased freezing tolerance without affecting the C-repeat binding transcription factor （CBF） transcriptional pathway. These results support a model that cold-induced inactivation of DPE2 leads to rapid accumulation of maltose, which is a cold-induced compatible solute that protects cells from freezing damage. This study provides evidence for a key role of rapid post-translational regulation of carbohydrate metabolic enzymes in plant protection against sudden temperature drop.

Plant Metabolic Network 15:A resource of genome-wide metabolism databases for 126 plants and algae

To understand and engineer plant metabolism, we need a comprehensive and accurate annotation of all metabolic information across plant species. As a step towards this goal, we generated genome-scale metabolic pathway databases of 126 algal and plant genomes, ranging from model organisms to crops to medicinal plants(https://plantcyc.org).Of these, 104 have not been reported before.We systematically evaluated the quality of the databases, which revealed that our semi-automated validation pipeline dramatically improves the quality. We then compared the metabolic content across the 126 organisms using multiple correspondence analysis and found that Brassicaceae,Poaceae, and Chlorophyta appeared as metabolically distinct groups. To demonstrate the utility of this resource, we used recently published sorghum transcriptomics data to discover previously unreported trends of metabolism underlying drought tolerance. We also used single-cell transcriptomics data from the Arabidopsis root to infer cell typespecific metabolic pathways. This work shows the quality and quantity of our resource and demonstrates its wide-ranging utility in integrating metabolism with other areas of plant biology.

地幔条件下斜方辉石高压相的弹性性质:对X不连续面成因的启示

位于深度250~350km的X不连续面具有2~8%的波阻抗跳变和较弱的深度-温度相关性,其成因尚未完全清楚.在各种可能机制中,柯石英-斯石英相变由于具有大的波阻抗跳变逐渐成为一种主流的机制.然而,单一的柯石英-斯石英相变不足以解释X不连续面深度-温度的弱相关性特征.而斜方辉石(OPX)到其高压相(HPCPX)的相变对应的波阻抗差较小,因此在近期的多个地震学研究中均将其排除在备选机制之外.但这个小的波阻抗差是基于Birch定律的一阶估计,并非来自直接的声波测量.文章用第一性原理计算获得了纯镁端元的斜方辉石高压相在高温高压下的弹性性质.结果表明,OPX-HPCPX相变会造成5.7%的P波波阻抗跳变和6.9%的S波波阻抗跳变,远大于之前的经验估计,因此OPX-HPCPX相变机制不可忽略.在热或湿的区域榴辉岩可能发生部分熔融从而产生富硅熔体,这将消耗二氧化硅并促进OPX的富集,由此提出柯石英-斯石英相变和OPX-HPCPX相变可能都是X不连续面的主要机制,前者在榴辉岩难以熔融的区域占主导地位,后者在榴辉岩发生部分熔融的区域占主导地位.该模型与地震学观测一致,表明OPX-HPCPX相变在X不连续面成因中的重要作用以及榴辉岩部分熔融的广泛发生.文章提出的X不连续面的成因机制为认识地球深部榴辉岩的熔融状态提供了一种新的可能途径.

Approaching the upper boundary of driver-response relationships:identifying factors using a novel framework integrating quantile regression with interpretable machine learning

The identification of factors that may be forcing ecological observations to approach the upper boundary provides insight into potential mechanisms affecting driver-response relationships,and can help inform ecosystem management,but has rarely been explored.In this study,we propose a novel framework integrating quantile regression with interpretable machine learning.In the first stage of the framework,we estimate the upper boundary of a driver-response relationship using quantile regression.Next,we calculate“potentials”of the response variable depending on the driver,which are defined as vertical distances from the estimated upper boundary of the relationship to observations in the driver-response variable scatter plot.Finally,we identify key factors impacting the potential using a machine learning model.We illustrate the necessary steps to implement the framework using the total phosphorus(TP)-Chlorophyll a(CHL)relationship in lakes across the continental US.We found that the nitrogen to phosphorus ratio(N:P),annual average precipitation,total nitrogen(TN),and summer average air temperature were key factors impacting the potential of CHL depending on TP.We further revealed important implications of our findings for lake eutrophication management.The important role of N:P and TN on the potential highlights the co-limitation of phosphorus and nitrogen and indicates the need for dual nutrient criteria.Future wetter and/or warmer climate scenarios can decrease the potential which may reduce the efficacy of lake eutrophication management.The novel framework advances the application of quantile regression to identify factors driving observations to approach the upper boundary of driver-response relationships.

SWEET蛋白家族研究进展

SWEET是新发现的一类具有7次跨膜?-螺旋的糖运输蛋白,它们由2个重复的具有3次跨膜?-螺旋的MtN3 motif和一个起连接作用的跨膜?-螺旋组成.SWEET广泛存在于真核单细胞生物、高等植物以及动物中.它们在生殖发育、植物与微生物的相互作用、植物的逆境反应及衰老等许多方面起重要作用.最近的研究显示,原核生物中存在与真核生物SWEET类似的、只含有一个3次跨膜?-螺旋的蛋白,这些蛋白属于MtN3或PQ-Loop家族.从慢生根瘤菌中克隆的SWEET同源蛋白BjSemiSWEET1和已经鉴定的部分真核生物SWEET蛋白一样具有运输蔗糖的能力,这个结果与其他相关研究一起暗示真核生物7次跨膜?-螺旋的糖或氨基酸运输蛋白可能由原核生物中3次跨膜?-螺旋的小分子蛋白通过复制或横向基因转移融合进化而来,并且它们在行使功能时可能形成和其他许多膜转运蛋白相似的、具有12次跨膜结构的功能单位.对SWEET的研究将为揭示多种生命现象提供重要线索.

BZS1, a B-box Protein, Promotes Photomorphogenesis Downstream of Both Brassinosteroid and Light Signaling Pathways

Photomorphogenesis is controlled by multiple signaling pathways, including the light and brassinosteroid （BR） pathways. BR signaling activates the BZR1 transcription factor, which is required for suppressing photomorphogen- esis in the dark, We identified a suppressor of the BR hypersensitive mutant bzrl-lD and named it bzrl-lD suppressorl- Dominant （bzsl-D）. The bzsl-D mutation was caused by overexpression of a B-box zinc finger protein BZS1, which is transcriptionally repressed by BZR1. Overexpression of BZS1 causes de-etiolation in the dark, short hypocotyls in the light, reduced sensitivity to BR treatment, and repression of many BR-activated genes. Knockdown of BZS1 by co-suppression partly suppressed the short hypocotyl phenotypes of BR-deficient or insensitive mutants. These results support that BZSl is a negative regulator of BR response. BZS1 overexpressors are hypersensitive to different wavelengths of light and loss of function of BZS1 reduces plant sensitivity to light and partly suppresses the constitutive photomorphogenesis 1 （cop1） mutant in the dark, suggesting a positive role in light response. BZS1 protein accumulates at an increased level after light treatment of dark-grown BZSl-OXplants and in the cop1 mutants, and BZS1 interacts with COP1 in vitro, suggesting that light regulates BZS1 through COPl-mediated ubiquitination and proteasomal degradation. These results demonstrate that BZS1 mediates the crosstalk between BR and light pathways.