44 research outputs found
Identifying Sulfate Sources and Recycling Processes in the Atacama Desert with Sulfur, Strontium and Triple Oxygen Isotopes
Get PDFSulfate is the dominating salt in soils of the Atacama Desert, one of the oldest and driest deserts on Earth. Sulfate sources include marine sulfate, terrestrial weathering (e.g., redistribution of surface material), and sulfate that is formed within the atmosphere by oxidation of reduced sulfur species. The stable isotopic composition of sulfate (D17OSO4 , d18OSO4 , and d34SSO4) is characteristic for each formation process, wherefore it serves as a tool to identify respective sulfate sources. The classical stable isotope proxies (d18OSO4 and d34SSO4) mainly help to distinguish between marine and terrestrial sulfate. In addition to these, the novel triple oxygen isotope tool (D17OSO4) also allows to identify sulfate formed in the atmosphere. Under Earth’s surface conditions, the isotopic composition of sulfate only alters when the sulfate is processed by microbes or plants. Hence, the isotopic composition of sulfate allows identifying the sulfate sources and enables to draw conclusions on biological alteration processes. This is especially interesting for areas, where biological activity is limited due to the low water availability, like the Atacama Desert.
The first study presents a fast and easy to use method to determine D17OSO4 of natural sulfate samples. It includes a protocol for the quantitative dissolution of natural Ca- and Na-sulfates samples and subsequent conversion into sufficiently pure Ag-sulfate for pyrolysis analyses. Determined D17OSO4 values from multiple in-house standards are compared to previously published results from different laboratories using different methods (pyrolysis and fluorination). A normalization procedure results in excellent reproducibility of standards, comparable to other laboratories including those using those using the fluorination method, verifying the accuracy and precision of the presented method.
The second study aims to improve the understanding of sulfate deposition and the spatial distribution of hyperaridity. Samples taken along four E-W transects are analyzed for their isotopic compositions (D17OSO4 , d18OSO4 , d34SSO4 , and 86Sr/88Sr). Throughout positive D17OSO4 values, determined using the method developed in the first study, suggest a significant contribution from atmospheric sulfate for all Atacama Desert sediments. The combination of D17OSO4 and d34SSO4 allows distinguishing between marine sulfate and sulfate that derived from atmospheric oxidation of biogenic sulfur gases emitted from the Ocean. In addition, a clear trend is visible in the triple oxygen isotopic composition (D17OSO4 and d18OSO4) of all samples, pointing from the isotopic composition of atmospheric sulfate to that of biological cycled sulfate. This trend reflects a gradient in the degree of biological activity and can therefore be used as indicator for water availability in the Atacama Desert.
This work provides an optimized pyrolysis method for triple oxygen isotope analysis of sulfate from desert environments and expands our knowledge of sulfate source contribution, sulfate deposition, biological sulfate cycling, and water availability within the hyperarid Atacama Desert
World‑class amethyst‑agate geodes from Los Catalanes, Northern Uruguay: genetic implications from fluid inclusions and stable isotopes
Get PDFInformación suplemetaria en: doi.org/10.1007/s00126-024-01310-2The amethyst and agate geodes from the Los Catalanes Gemmological District in Uruguay represent one of the main deposits of its kind worldwide. The geometry of the deposit is horizontal, with an irregular distribution of amethyst geodes within the upper level of the basalt lava flows and shows strong variations in their abundance, as well as quality, geometry, and shape. Reliable exploration guides are scarce, and the limited knowledge of the geological parameters controlling its occurrence makes exploration unpredictable, leading to inaccurate reserve estimation. Based on cutting-edge methods including nucleation-assisted microthermometry of one-phase fluid inclusions and determination of triple oxygen isotope in silicates and carbonates, as well as analysis of geode-hosted water and groundwater, we estimate the crystallisation temperatures in the range between 15 and 60 °C. These low temperatures point to amethyst crystallisation after the emplacement of the complete basalt pile. The mineralising fluid shows isotopic signatures consistent with meteoric water and very low salinities from pure water up to rarely over 3 wt% NaCl-eq., likely sourced from the groundwater hosted in the aquifers in the basaltic
sequence and underlying units. Based on the insights provided by the new data, we propose the combination of open- and closed-system crystallisation inside pre-existing cavities due to the episodic infiltration of meteoric water in a rather stable geological context
Non-Targeted Metabolite Profiling Reveals Host Metabolomic Reprogramming during the Interaction of Black Pepper with Phytophthora capsici
Get PDFPhytophthora capsici is one of the most destructive pathogens causing quick wilt (foot rot)
disease in black pepper (Piper nigrum L.) to which no effective resistance has been defined. To better
understand the P. nigrum–P. capsici pathosystem, we employed metabolomic approaches based on
flow‐infusion electrospray–high‐resolution mass spectrometry. Changes in the leaf metabolome
were assessed in infected and systemic tissues at 24 and 48 hpi. Principal Component Analysis of
the derived data indicated that the infected leaves showed a rapid metabolic response by 24 hpi
whereas the systemic leaves took 48 hpi to respond to the infection. The major sources of variations
between infected leaf and systemic leaf were identified, and enrichment pathway analysis indicated,
major shifts in amino acid, tricarboxylic acid cycle, nucleotide and vitamin B6 metabolism upon
infection. Moreover, the individual metabolites involved in defensive phytohormone signalling
were identified. RT‐qPCR analysis of key salicylate and jasmonate biosynthetic genes indicated a
transient reduction of expression at 24 hpi but this increased subsequently. Exogenous application
of jasmonate and salicylate reduced P. capsici disease symptoms, but this effect was suppressed with
the co‐application of abscisic acid. The results are consistent with abscisic acid reprogramming, salicylate
and jasmonate defences in infected leaves to facilitate the formation of disease. The augmentation
of salicylate and jasmonate defences could represent an approach through which quick wilt
disease could be controlled in black pepper
Infection prevention and control interventions in the first outbreak of methicillin-resistant Staphylococcus aureus infections in an equine hospital in Sweden
Get PDF<p>Abstract</p> <p>Background</p> <p>The first outbreak of methicillin-resistant <it>Staphylococcus aureus </it>(MRSA) infection in horses in Sweden occurred in 2008 at the University Animal Hospital and highlighted the need for improved infection prevention and control. The present study describes interventions and infection prevention control in an equine hospital setting July 2008 - April 2010.</p> <p>Method</p> <p>This descriptive study of interventions is based on examination of policy documents, medical records, notes from meetings and cost estimates. MRSA cases were identified through clinical sampling and telephone enquiries about horses post-surgery. Prospective sampling in the hospital environment with culture for MRSA and genotyping of isolates by <it>spa</it>-typing and pulsed-field gel electrophoresis (PFGE) were performed.</p> <p>Results</p> <p>Interventions focused on interruption of indirect contact spread of MRSA between horses via staff and equipment and included: Temporary suspension of elective surgery; and identification and isolation of MRSA-infected horses; collaboration was initiated between authorities in animal and human public health, human medicine infection control and the veterinary hospital; extensive cleaning and disinfection was performed; basic hygiene and cleaning policies, staff training, equipment modification and interior renovation were implemented over seven months.</p> <p>Ten (11%) of 92 surfaces sampled between July 2008 and April 2010 tested positive for MRSA <it>spa</it>-type 011, seven of which were from the first of nine sampling occasions. PFGE typing showed the isolates to be the outbreak strain (9 of 10) or a closely related strain. Two new cases of MRSA infection occurred 14 and 19 months later, but had no proven connections to the outbreak cases.</p> <p>Conclusions</p> <p>Collaboration between relevant authorities and the veterinary hospital and formation of an infection control committee with an executive working group were required to move the intervention process forward. Support from hospital management and the dedication of staff were essential for the development and implementation of new, improved routines. Demonstration of the outbreak strain in the environment was useful for interventions such as improvement of cleaning routines and interior design, and increased compliance with basic hygienic precautions. The interventions led to a reduction in MRSA-positive samples and the outbreak was considered curbed as no new cases occurred for over a year.</p
Conserved Regulation of p53 Network Dosage by MicroRNA–125b Occurs through Evolving miRNA–Target Gene Pairs
Get PDFMicroRNAs regulate networks of genes to orchestrate cellular functions. MiR-125b, the vertebrate homologue of the Caenorhabditis elegans microRNA lin-4, has been implicated in the regulation of neural and hematopoietic stem cell homeostasis, analogous to how lin-4 regulates stem cells in C. elegans. Depending on the cell context, miR-125b has been proposed to regulate both apoptosis and proliferation. Because the p53 network is a central regulator of both apoptosis and proliferation, the dual roles of miR-125b raise the question of what genes in the p53 network might be regulated by miR-125b. By using a gain- and loss-of-function screen for miR-125b targets in humans, mice, and zebrafish and by validating these targets with the luciferase assay and a novel miRNA pull-down assay, we demonstrate that miR-125b directly represses 20 novel targets in the p53 network. These targets include both apoptosis regulators like Bak1, Igfbp3, Itch, Puma, Prkra, Tp53inp1, Tp53, Zac1, and also cell-cycle regulators like cyclin C, Cdc25c, Cdkn2c, Edn1, Ppp1ca, Sel1l, in the p53 network. We found that, although each miRNA–target pair was seldom conserved, miR-125b regulation of the p53 pathway is conserved at the network level. Our results lead us to propose that miR-125b buffers and fine-tunes p53 network activity by regulating the dose of both proliferative and apoptotic regulators, with implications for tissue stem cell homeostasis and oncogenesis
Gender and gangs: A Comparative Study on Why Men and Women Become Involved in Gang-related Crime.
No full textDenna studie syftar till att undersöka vilka förklaringar som kan finnas till varför killar/män respektive tjejer/kvinnor hamnar i kriminella gäng. Det undersöks även hur könsroller och maskulinitet kommer till uttryck inom de kriminella gängens ramar. Under arbetet jämförs dessa faktorer utifrån ett genusperspektiv där könsroller och maskulinitet i gäng diskuteras och analyseras. Genom en litteraturstudie har det kunnat ge oss en grund för att besvara vårt syfte. En tematisk analys har använts för att få fram fyra olika huvudteman. De teman som har identifierats genom empirin är: omgivningen påverkar risken för kriminalitet, trygghet söks i gängen, samt skillnader i makt inom gäng. Genom teorier som genus-, maskulinitet-, samt anknytningsteori har detta resultat kunnat analyseras för att slutligen nå en slutsats. Denna tematiska litteraturstudie har kommit fram till att det finns tydliga skillnader och likheter mellan tjejer/ kvinnor och killar/män, när det kommer till deras benägenhet att hamna i kriminella gäng. Där killar/män främst går med på grund av status och pengar, medan tjejer/kvinnor går med på grund av deras egen utsatthet och strävan efter kontroll. Förutom de märkbara skillnaderna i anledningar att gå med i gäng, har denna studie även kunnat se hur tydliga maktstrukturer och normer framträder i gängen. Stora könsskillnader och makthierarki där kvinnor i större utsträckning är i underläge, framför allt i mansdominerade gäng. Genom att forska ur ett genusperspektiv kan man identifiera de olika faktorerna, som i sin tur kan bidra till eventuella åtgärder som tillhandahåller individens behov bäst, för att därmed minska gängkriminaliteten
Identifying water availability in the Atacama Desert (Chile) by triple oxygen isotope analyses of sulfates
No full text
&lt;p&gt;Ca-Sulfates (Gypsum and Anhydrite) are the most common salts accumulating in the soil of the Chilean Atacama Desert. Sulfate sources include sea spray, redeposition of playa sediments, terrestrial weathering, and deposition of sulfate formed in the atmosphere (secondary atmospheric sulfate = SAS). Sulfate from sea spray, playa lakes, and terrestrial weathering have a triple oxygen isotope composition (&amp;#916;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;SO4&lt;/sub&gt;) at or slightly below zero reflecting reaction with water and oxygen. Positive &amp;#916;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;SO4&lt;/sub&gt; are generally the result of atmospheric SO&lt;sub&gt;2&lt;/sub&gt; oxidation by ozone or hydrogen peroxide. Sulfate oxygen is only altered with ambient water by cycling through biological activity resulting in &amp;#916;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;SO4&lt;/sub&gt; &amp;#8776; 0&amp;#8240;. Therefore, &amp;#916;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;SO4&lt;/sub&gt; aids in quantifying the relative contribution of SAS to the desert soil and in identifying bioactivity and water availability in the hyperarid Atacama Desert. The spatial quantification of different sulfate sources may serve to improve the understanding of sulfate deposition in this region.&lt;/p&gt;&lt;p&gt;Samples were analysed by continuous flow IRMS using the pyrolysis of Ag&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt; to determine &amp;#916;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;SO4&lt;/sub&gt; from O&lt;sub&gt;2&lt;/sub&gt;. An optimized sample preparation to form clean silver sulfate and intra-day calibration against two in-house standards resulted in an external reproducibility of 0.12&amp;#8240;. An inter laboratory comparison including data derived from the laser-fluorination method confirmed the accuracy of our analyses.&lt;/p&gt;&lt;p&gt;We analyzed desert soil surface samples from four E-W transects in the Atacama Desert reaching from the Pacific coast across the Coastal Cordillera, the Central Depression, and up the alluvial fans protruding from the Pre-Andean Cordillera. Transects begin at Pisagua (19.5&amp;#176;S), Salar Grande (21.0&amp;#176;S), Antofagasta (24.0&amp;#176;S), and Paposo (25.0&amp;#176;S). Values of &amp;#916;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;SO4&lt;/sub&gt; vary between 0.3 and 1.1&amp;#8240;. The lowest &amp;#916;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;SO4 &lt;/sub&gt;values were measured near Salar Grande and on the Pre-Andean alluvial fans. The highest &amp;#916;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;SO4 &lt;/sub&gt;values are observed at the highest altitudes in the Coastal Cordillera - east of Paposo - well above the coastal fog zone (&gt; 1200 m). At similar or higher altitudes on the Pre-Andean fans, &amp;#916;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;SO4&lt;/sub&gt; converge towards zero.&lt;/p&gt;&lt;p&gt;The spatial distribution is the result of source contributions and subsequent biological reset. Positive &amp;#916;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;SO4&lt;/sub&gt; values throughout suggest a significant contribution from SAS. We quantified sea spray contributions using Cl-&amp;#160;concentration, which drop dramatically above the fog-zone [1]. Furthermore, salt distribution suggests minimal weathering and redistribution in recent times. The lowest contribution from such near zero &amp;#916;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;SO4&lt;/sub&gt; sulfate sources are expected in the Coastal Cordillera, which is consistent with our data. Within the Coastal Cordillera there is a north to south &amp;#916;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;SO4 &lt;/sub&gt;trend, which is also an elevation trend. Increased water availability from fog at lower elevations facilitates more efficient resetting of &amp;#916;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;SO4&lt;/sub&gt; via microbial activity. These observations suggest that the driest place in the Atacama Desert is situated within the Coastal Cordillera above the fog zone.&lt;/p&gt;&lt;p&gt;[1] Voigt et al. (2020) Global and Planetary Change &lt;strong&gt;184&lt;/strong&gt;&lt;/p&gt;
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