185 research outputs found

    Paleoproterozoic metamorphism and deformation in Central Lapland, Finland

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    Three main ductile deformations, D1-D3, and contemporaneous and later shear zones account for most structures in Central Lapland. The oldest tectono-metamorphic feature is the bedding-parallel, mostly microscopic S1, overprinted by the main foliation S2, which is the most prominent structural feature seen in almost all rock types throughout the study area. Subhorizontal S2 is an axial plane foliation to tight or isoclinal, inclined to recumbent F2 folds. Kinematic indicators in the central and southern parts of the study area indicate a northward transport direction, but close to the S and SW border the Lapland Granulite Belt it may be of opposite direction. F3 folds deform the D2 structures. F3 folding show an extreme variety regarding the fold vergence with N-vergent folds in south, SW-W-vergent folds in north and E-vergent folds in west close to the Kolari shear system. Apparently, the F3 folding seems to be associated with complex tectonic movement directions, from S to N direction in the south, from NE to SW in the north and northeast part, and from W to E in the western part of the study area. Several metamorphic zones have been mapped in the area. These are I) granulite facies migmatitic amphibolites south of the granulite complex (including the so called Tanaelv belt next to the granulites); II) high pressure mid-amphibolite facies rocks south of Zone I, characterised by garnet-kyanite-biotite-muscovite assemblages with local migmatisation in metapelites, garnet-hornblende-plagioclase assemblages in mafic rocks, local cordierite-orthoamphibole rocks intercalated with mafic volcanics; III) low-pressure mid-amphibolite facies rocks south of Zone II, garnet-andalusite-staurolite- chlorite-muscovite assemblages with retrograde chloritoid and kyanite in metapelites, hornblende-plagioclase-quartz±garnet in metabasites; IV) greenschist facies rocks of the Central Lapland Greenstone Belt, fine-grained white mica-chlorite-biotite-albite-quartz in metapelites, actinolite-albite-chlorite-epidote-carbonate in metabasites; V) prograde metamorphism south of Zone IV from lower amphibolite facies (andalusite-kyanite- staurolite-muscovite-chlorite±chloritoid schists, V.1-2) to mid-amphibolite facies (kyanite-andalusite-staurolite-biotite-muscovite gneisses, V.3) and upper amphibolite facies garnet-sillimanite-biotite gneisses (V.5); VI) amphibolite facies pluton-derived metamorphism related with heat flow from central and western Lapland granitoids, where Zone VI.2 represents both andalusite and sillimanite-present, and Zone VI.3 only sillimanite-present, andalusite absent gneisses. Pelitic rocks exhibit decompressional PT paths where andalusite grade metamorphism was preceded by higher pressure. Metamorphism was partly related with tectonic thickening during overthrusting of the Lapland Granulite Belt to the south, but the present metamorphic structure may record later, postmetamorphic faulting and folding events.</p

    LITHOSPHERE 2021: ELEVENTH SYMPOSIUM ON STRUCTURE, COMPOSITION AND EVOLUTION OF THE LITHOSPHERE: PROGRAMME AND EXTENDED ABSTRACTS

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    The Central Svecofennian Arc Complex (CSAC) and the Southern Svecofennian Arc Complex (SSAC) showdifferent ages of peak metamorphism: ~1.88 Ga in the CSAC and ~1.83 Ga in the SSAC. In the present project we study the age of the metamorphism in SW Finland. We have collected two samples. Of these the Eurajoki leucosome zircons were > 1.92 Ga, i.e.,inherited, but monazites show two populations: ~1.83 Ga and ~1.7 Ga. The zircons from the Rauma leucosome yielded two populations: ~1.86 Ga and ~1.83 Ga. The monazites show ages of ~1.83 Ga and ~1.7 Ga. We interpret that the ~1.86 Ga zircons represent the older metamorphism and the 1.83 Ga zircon and monazite group to represent the younger metamorphism. The 1.7 Ga group is unusual and needs further investigation.</p

    Seipin Facilitates Triglyceride Flow to Lipid Droplet and Counteracts Droplet Ripening via Endoplasmic Reticulum Contact

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    Seipin is an oligomeric integral endoplasmic reticulum (ER) protein involved in lipid droplet (LD) biogenesis. To study the role of seipin in LD formation, we relocalized it to the nuclear envelope and found that LDs formed at these new seipin-defined sites. The sites were characterized by uniform seipin-mediated ER-LD necks. At low seipin content, LDs only grew at seipin sites, and tiny, growth-incompetent LDs appeared in a Rab18-dependent manner. When seipin was removed from ER-LD contacts within 1 h, no lipid metabolic defects were observed, but LDs became heterogeneous in size. Studies in seipin-ablated cells and model membranes revealed that this heterogeneity arises via a biophysical ripening process, with triglycerides partitioning from smaller to larger LDs through droplet-bilayer contacts. These results suggest that seipin supports the formation of structurally uniform ER-LD contacts and facilitates the delivery of triglycerides from ER to LDs. This counteracts ripening-induced shrinkage of small LDs.Peer reviewe

    HSP70 induces liver X receptor pathway activation and cholesterol reduction in vitro and in vivo

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    Objective: Heat Shock Proteins (HSPs) maintain cellular homeostasis under stress. HSP70 represents a major stress-inducible family member and has been identified as a druggable target in inherited cholesterol-sphingolipid storage diseases. We investigated if HSP70 modulates cholesterol accumulation in more common conditions related to atherogenesis. Methods: We studied the effects of recombinant HSP70 in cholesterol-laden primary macrophages from human blood donors and pharmacological HSP70 upregulation in high-cholesterol diet fed zebrafish. Results: Recombinant HSP70 facilitated cholesterol removal from primary human macrophage foam cells. RNA sequencing revealed that HSP70 induced a robust transcriptional re-programming, including upregulation of key targets of liver X receptors (LXR), master regulators of whole-body cholesterol removal. Mechanistically, HSP70 interacted with the macrophage LXRalpha promoter, increased LXRalpha and its target mRNAs, and led to elevated levels of key proteins facilitating cholesterol efflux, including ATP-binding cassette transporters A1 and G1. Pharmacological augmentation of endogenous HSP70 in high-cholesterol diet fed zebrafish activated LXR and its target mRNAs and reduced cholesterol storage at the whole organism level. Conclusion: These data demonstrate that HSP70 exerts a cholesterol lowering effect in primary human cells and animals and uncover a nuclear action of HSP70 in mediating cross-talk between HSP and LXR transcriptional regulation. (C) 2019 The Authors. Published by Elsevier GmbH.Peer reviewe

    Seipin regulates ER-lipid droplet contacts and cargo delivery

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    Seipin is an endoplasmic reticulum (ER) membrane protein implicated in lipid droplet (LD) biogenesis and mutated in severe congenital lipodystrophy (BSCL2). Here, we show that seipin is stably associated with nascent ER-LD contacts in human cells, typically via one mobile focal point per LD Seipin appears critical for such contacts since ER-LD contacts were completely missing or morphologically aberrant in seipin knockout and BSCL2 patient cells. In parallel, LD mobility was increased and protein delivery from the ER to LDs to promote LD growth was decreased. Moreover, while growing LDs normally acquire lipid and protein constituents from the ER, this process was compromised in seipin-deficient cells. In the absence of seipin, the initial synthesis of neutral lipids from exogenous fatty acid was normal, but fatty acid incorporation into neutral lipids in cells with pre-existing LDs was impaired. Together, our data suggest that seipin helps to connect newly formed LDs to the ER and that by stabilizing ER-LD contacts seipin facilitates the incorporation of protein and lipid cargo into growing LDs in human cells.Peer reviewe

    Global transpiration data from sap flow measurements: The SAPFLUXNET database

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    Plant transpiration links physiological responses of vegetation to water supply and demand with hydrological, energy, and carbon budgets at the land-atmosphere interface. However, despite being the main land evaporative flux at the global scale, transpiration and its response to environmental drivers are currently not well constrained by observations. Here we introduce the first global compilation of whole-plant transpiration data from sap flow measurements (SAPFLUXNET, https://sapfluxnet.creaf.cat/, last access: 8 June 2021). We harmonized and quality-controlled individual datasets supplied by contributors worldwide in a semi-automatic data workflow implemented in the R programming language. Datasets include sub-daily time series of sap flow and hydrometeorological drivers for one or more growing seasons, as well as metadata on the stand characteristics, plant attributes, and technical details of the measurements. SAPFLUXNET contains 202 globally distributed datasets with sap flow time series for 2714 plants, mostly trees, of 174 species. SAPFLUXNET has a broad bioclimatic coverage, with woodland/shrubland and temperate forest biomes especially well represented (80% of the datasets). The measurements cover a wide variety of stand structural characteristics and plant sizes. The datasets encompass the period between 1995 and 2018, with 50% of the datasets being at least 3 years long. Accompanying radiation and vapour pressure deficit data are available for most of the datasets, while on-site soil water content is available for 56% of the datasets. Many datasets contain data for species that make up 90% or more of the total stand basal area, allowing the estimation of stand transpiration in diverse ecological settings. SAPFLUXNET adds to existing plant trait datasets, ecosystem flux networks, and remote sensing products to help increase our understanding of plant water use, plant responses to drought, and ecohydrological processes. SAPFLUXNET version 0.1.5 is freely available from the Zenodo repository (10.5281/zenodo.3971689; Poyatos et al., 2020a). The "sapfluxnetr"R package-designed to access, visualize, and process SAPFLUXNET data-is available from CRAN. © 2021 Rafael Poyatos et al.This research was supported by the Minis-terio de Economía y Competitividad (grant no. CGL2014-55883-JIN), the Ministerio de Ciencia e Innovación (grant no. RTI2018-095297-J-I00), the Ministerio de Ciencia e Innovación (grant no. CAS16/00207), the Agència de Gestió d’Ajuts Universitaris i de Recerca (grant no. SGR1001), the Alexander von Humboldt-Stiftung (Humboldt Research Fellowship for Experienced Researchers (RP)), and the Institució Catalana de Recerca i Estudis Avançats (Academia Award (JMV)). Víctor Flo was supported by the doctoral fellowship FPU15/03939 (MECD, Spain)

    An Aged Canid with Behavioral Deficits Exhibits Blood and Cerebrospinal Fluid Amyloid Beta Oligomers

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    Many of the molecular and pathological features associated with human Alzheimer disease (AD) are mirrored in the naturally occurring age-associated neuropathology in the canine species. In aged dogs with declining learned behaviour and memory the severity of cognitive dysfunction parallels the progressive build up and location of Aβ in the brain. The main aim of this work was to study the biological behaviour of soluble oligomers isolated from an aged dog with cognitive dysfunction through investigating their interaction with a human cell line and synthetic Aβ peptides. We report that soluble oligomers were specifically detected in the dog’s blood and cerebrospinal fluid via anti-oligomer- and anti-Aβ specific binders. Importantly, our results reveal the potent neurotoxic effects of the dog’s cerebrospinal fluid on cell viability and the seeding efficiency of the cerebrospinal fluid-borne soluble oligomers on the thermodynamic activity and the aggregation kinetics of synthetic human Aβ. The value of further characterising the naturally occurring Alzheimer-like neuropathology in dogs using genetic and molecular tools is discussed

    Global transpiration data from sap flow measurements : the SAPFLUXNET database

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    Plant transpiration links physiological responses of vegetation to water supply and demand with hydrological, energy, and carbon budgets at the land-atmosphere interface. However, despite being the main land evaporative flux at the global scale, transpiration and its response to environmental drivers are currently not well constrained by observations. Here we introduce the first global compilation of whole-plant transpiration data from sap flow measurements (SAPFLUXNET, https://sapfluxnet.creaf.cat/, last access: 8 June 2021). We harmonized and quality-controlled individual datasets supplied by contributors worldwide in a semi-automatic data workflow implemented in the R programming language. Datasets include sub-daily time series of sap flow and hydrometeorological drivers for one or more growing seasons, as well as metadata on the stand characteristics, plant attributes, and technical details of the measurements. SAPFLUXNET contains 202 globally distributed datasets with sap flow time series for 2714 plants, mostly trees, of 174 species. SAPFLUXNET has a broad bioclimatic coverage, with woodland/shrubland and temperate forest biomes especially well represented (80 % of the datasets). The measurements cover a wide variety of stand structural characteristics and plant sizes. The datasets encompass the period between 1995 and 2018, with 50 % of the datasets being at least 3 years long. Accompanying radiation and vapour pressure deficit data are available for most of the datasets, while on-site soil water content is available for 56 % of the datasets. Many datasets contain data for species that make up 90 % or more of the total stand basal area, allowing the estimation of stand transpiration in diverse ecological settings. SAPFLUXNET adds to existing plant trait datasets, ecosystem flux networks, and remote sensing products to help increase our understanding of plant water use, plant responses to drought, and ecohydrological processes. SAPFLUXNET version 0.1.5 is freely available from the Zenodo repository (https://doi.org/10.5281/zenodo.3971689; Poyatos et al., 2020a). The "sapfluxnetr" R package - designed to access, visualize, and process SAPFLUXNET data - is available from CRAN.Peer reviewe
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