Superoxide dismutase from Helicobacter pylori suppresses the production of pro-inflammatory cytokines during in vivo infection

Abstract

Background

Helicobacter pylori has undergone considerable adaptation to allow chronic persistence within the gastric environment. While H. pylori-associated diseases are driven by an excessive inflammation, severe gastritis is detrimental to colonization by this pathogen. Hence, H. pylori has developed strategies to minimize the severity of gastritis it triggers in its host. Superoxide dismutase (SOD) is well known for its role in protecting against oxidative attack; less recognized is its ability to inhibit immunity, shown for SOD from mammalian sources and those of some bacterial species. This study examined whether H. pylori SOD (HpSOD) has the ability to inhibit the host immune response to these bacteria.

Materials and Methods

The ability of recombinant HpSOD to modify the response to LPS was measured using mouse macrophages. A monoclonal antibody against HpSOD was generated and injected into H. pylori-infected mice.

Results

Addition of HpSOD to cultures of mouse macrophages significantly inhibited the pro-inflammatory cytokine response to LPS stimulation. A monoclonal antibody was generated that was specific for SOD from H. pylori. When injected into mice infected with H. pylori for 3 months, this antibody was readily detected in both sera and gastric tissues 5 days later. While treatment with anti-HpSOD had no effect on H. pylori colonization at this time point, it significantly increased the levels of a range of pro-inflammatory cytokines in the gastric tissues. This did not occur with antibodies against other antioxidant enzymes.

Conclusions

SOD from H. pylori can inhibit the production of pro-inflammatory cytokine during in vivo infection.

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Letter to the Editor concerning “Can standard anterior Smith–Robinson supramanubrial approach be utilized for approach down to T2 or T3?” by Singhatanadgige W, Zebala LP, Luksanapruksa P, Riew KD [Eur Spine J (2017) 26:2357–2362]

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[Rezension von] Bernd Roling, Physica sacra: Wunder, Naturwissenschaft und historischer Schriftsinn zwischen Mittelalter und Früher Neuzeit (Mittellateinische Studien und Texte 45), Leiden/Boston 2013

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Der Humanist und die Scholastiker. Alte Reaktionen auf ein Neues Testament?

The opposition to Erasmus' Novum Instrumentum was manifold. While Erasmus himself tried to present the debate about his work as an antagonism between humanism and scholasticism, the real reactions did not blend in such a simple scheme. Taking as an example the two theologians Maarten van Dorp and John Mair who were working at the universities of Louvain and Paris and who criticized Erasmus' work from very different perspectives, this article illustrates the complexity of the (sometimes even humanist) motifs that stimulated their criticisms and reactions to Erasmus' work.

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Paired isotope records of carbonate and organic matter from the Middle Ordovician of Argentina: Intrabasinal variation and effects of the marine chemocline

Publication date: 15 January 2018
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 490
Author(s): Miles A. Henderson, Fernanda Serra, Nicolás A. Feltes, Guillermo L. Albanesi, Linda C. Kah
We investigate the expression of the Middle Darriwilian isotope carbon excursion (MDICE) across marine shelf environments in the Argentine Precordillera. Previous work identified the MDICE in the Las Chacritas Formation in Argentina, but did not recognize the expression of the MDICE in time-equivalent strata of the deeper-water Las Aguaditas Formation (Albanesi et al., 2013; Palaeogeography, Palaeoclimatology, Palaeoecology, v. 398, p. 48–66). Recent biostratigraphic investigations of these units have, for the first time, provided the opportunity for high-resolution correlation, which suggest that the MDICE, or at least the initiation of the MDICE, should be observed in both the Las Chacritas and Las Aguaditas formations. Here we present new paired carbon isotope data of carbonate and organic carbon from the Las Chacritas and Las Aguaditas formations. We identify a 2‰ positive shift in the isotopic composition of marine carbonate in the Las Chacritas Formation, whereas values abruptly fall to < −1‰ in equivalent strata of the Las Aguaditas Formation. This is the first record of divergence from the globally recognized MDICE event. There are also small, yet distinct differences in the isotopic composition of marine organic matter between these two sections. We suggest that the divergent C-isotope trends of carbonate in the Las Chacritas and Las Aguaditas formations represent deposition in fundamentally different parts of the water column — above and below the marine chemocline, respectively — during the MDICE interval. This interpretation is consistent with data from the Las Aguaditas Formation that shows elevated Mn and Fe concentrations in carbonate phases with little evidence for recrystallization, and with a growing consensus for regionally anoxic conditions for the Middle Ordovician. Our data indicate that redox gradients can play a critical role in the behavior of marine carbon isotope excursions.



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Boosting Bifunctional Oxygen Electrocatalysis with 3D Graphene Aerogel-Supported Ni/MnO Particles

Abstract

Electrocatalysts for oxygen-reduction and oxygen-evolution reactions (ORR and OER) are crucial for metal–air batteries, where more costly Pt- and Ir/Ru-based materials are the benchmark catalysts for ORR and OER, respectively. Herein, for the first time Ni is combined with MnO species, and a 3D porous graphene aerogel-supported Ni/MnO (Ni–MnO/rGO aerogel) bifunctional catalyst is prepared via a facile and scalable hydrogel route. The synthetic strategy depends on the formation of a graphene oxide (GO) crosslinked poly(vinyl alcohol) hydrogel that allows for the efficient capture of highly active Ni/MnO particles after pyrolysis. Remarkably, the resulting Ni–MnO/rGO aerogels exhibit superior bifunctional catalytic performance for both ORR and OER in an alkaline electrolyte, which can compete with the previously reported bifunctional electrocatalysts. The MnO mainly contributes to the high activity for the ORR, while metallic Ni is responsible for the excellent OER activity. Moreover, such bifunctional catalyst can endow the homemade Zn–air battery with better power density, specific capacity, and cycling stability than mixed Pt/C + RuO₂ catalysts, demonstrating its potential feasibility in practical application of rechargeable metal–air batteries.

A bifunctional 3D porous graphene aerogel-supported Ni/MnO (Ni–MnO/rGO aerogel) catalyst is reported that exhibits excellent electrocatalytic activity and stability for the oxygen-reduction and oxygen-evolution reactions in alkaline media. The Ni–MnO/rGO-driven Zn–air batteries can be stably charged and discharged over 100 cycles with high voltaic efficiency, outperforming the more costly Pt/C + RuO₂ catalyst-driven Zn–air batteries.

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High-Performance As-Cast Nonfullerene Polymer Solar Cells with Thicker Active Layer and Large Area Exceeding 11% Power Conversion Efficiency

Abstract

In this work, a nonfullerene polymer solar cell (PSC) based on a wide bandgap polymer donor PM6 containing fluorinated thienyl benzodithiophene (BDT-2F) unit and a narrow bandgap small molecule acceptor 2,2′-((2Z,2′Z)-((4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl)bis(methanylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (IDIC) is developed. In addition to matched energy levels and complementary absorption spectrum with IDIC, PM6 possesses high crystallinity and strong π–π stacking alignment, which are favorable to charge carrier transport and hence suppress recombination in devices. As a result, the PM6:IDIC-based PSCs without extra treatments show an outstanding power conversion efficiency (PCE) of 11.9%, which is the record value for the as-cast PSC devices reported in the literature to date. Moreover, the device performances are insensitive to the active layer thickness (≈95–255 nm) and device area (0.20–0.81 cm²) with PCEs of over 11%. Besides, the PM6:IDIC-based flexible PSCs with a large device area of 1.25 cm² exhibit a high PCE of 6.54%. These results indicate that the PM6:IDIC blend is a promising candidate for future roll-to-roll mass manufacturing and practical application of highly efficient PSCs.

An efficient polymer solar cell (PSC) based on a polymer donor PM6 containing BDT-2F unit and an n-type organic semiconductor acceptor 2,2′-((2Z,2′Z)-((4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl)bis(methanylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (IDIC) is developed. The power conversion efficiencies of PSCs without extra treatments reach up to 11.9% and are insensitive to the active layer thickness (95–225 nm) and device area (0.20–0.81 cm²) with the values of over 11%.

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Sedimentary evolution of the Yangtze River mouth (East China Sea) over the past 19,000years, with emphasis on the Holocene variations in coastal currents

Publication date: 15 January 2018
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 490
Author(s): Baocheng Zhao, Xuexin Yan, Zhanghua Wang, Yujin Shi, Zhongyuan Chen, Jianlei Xie, Jing Chen, Zhongfa He, Qing Zhan, Xiao Li
Water mass variations in the early Yangtze estuary during the postglacial transgression have not been thoroughly studied. This research gap has hampered the understanding of riverine sediment 'source to sink' processes in this region. This study presents the results of integrated analyses of grain size, pollen-spore-dinocyst assemblages, benthic foraminifera and ostracods from a borehole, H5, located at the northern Yangtze mouth, to investigate the complete sedimentary history and associated variations in coastal currents since 19ka. At the core site, a fluvial floodplain developed from ca. 19–11.3ka, whereas an estuary to shelf to subaqueous delta prevailed during most of the Holocene. Based on changes in the dominant microfauna species, which mainly consist of Chinese coastal water species, two main current patterns were distinguished: one dominated by the Yellow Sea coastal current (YSCC) before ca. 7.9ka and one dominated by the Yangtze dilute water (YDW). Marked increases in open-sea saline species, including Bolivina robusta, and stratified water dinocyst species Spiniferites ramous and Spiniferites spp. were interpreted as the encroachment of the Taiwan warm current (TWWC) and the intensification of the YDW, respectively. The YDW and TWWC penetrated the area dominated by the YSCC before 7.9ka, which was likely related to intensity variations in the Kuroshio Current (KC) and Asian summer monsoon (ASM). Under maximal ASM and KC conditions, upwelling resulted from the intensified intrusion of the TWWC, as indicated by the blooming of Bolivina robusta from 7.9–6.3ka. After ca. 6ka, the YDW clearly weakened due to the decline of the ASM, yet the Yangtze plume prevailed due to the rapid seaward migration of the Yangtze mouth. Considering the dominance of the YSCC in the early Holocene, Yellow River-derived sediment likely represented a large proportion of the material delivered to the early Yangtze estuary.



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Terrestrial Permian–Triassic boundary in southern China: New stratigraphic, structural and palaeoenvironment considerations

Publication date: 15 January 2018
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 490
Author(s): Sylvie Bourquin, Camille Rossignol, Marc Jolivet, Marc Poujol, Jean Broutin, Jianxin Yu




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Late Quaternary coastal evolution and aeolian sedimentation in the tectonically-active southern Atacama Desert, Chile

Publication date: 15 January 2018
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 490
Author(s): David J. Nash, Mark D. Bateman, Joanna E. Bullard, Claudio Latorre
Analyses of aeolianites and associated dune, surficial carbonate and marine terrace sediments from north-central Chile (27° 54′ S) yield a record of environmental change for the coastal southern Atacama Desert spanning at least the last glacial-interglacial cycle. Optically stimulated luminescence dating indicates phases of aeolian dune construction at around 130, 111–98, 77–69 and 41–28ka. Thin-section and stable carbon and oxygen isotope analyses suggest a predominantly marine sediment source for the three oldest dune phases. Aeolianites appear to have accumulated mainly from tectonically-uplifted interglacial marine sediments that were deflated during windier and/or stormier intervals. Bedding orientations indicate that sand-transporting winds varied in direction from S-ESE during MIS 5e and WNW-ESE during MIS 5c-5a. Winds from the southeast quadrant are unusual today in this region of the Atacama, suggesting either major shifts in atmospheric circulation or topographic airflow modification. Thin-section evidence indicates that the aeolianites were cemented by two phases of vadose carbonate, tentatively linked to wetter periods around 70 and 45ka. Tectonic uplift in the area has proceeded at an average rate of 305–542mmkyr⁻¹. The study illustrates the complexity of understanding onshore-offshore sediment fluxes in the context of Late Quaternary sea-level fluctuations for an area undergoing rapid tectonic uplift.



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New insights on the stepwise collapse of the Carboniferous Coal Forests: Evidence from cyclothems and coniferopsid tree-stumps near the Desmoinesian–Missourian boundary in Peoria County, Illinois, USA

Publication date: 15 January 2018
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 490
Author(s): Howard J. Falcon-Lang, W. John Nelson, Philip H. Heckel, William A. DiMichele, Scott D. Elrick
The first phase in the stepwise collapse of the Carboniferous Coal Forests occurred near the Desmoinesian–Missourian boundary (early Kasimovian, ~307Ma), and involved extirpation of Lycospora-producing lepidodendrids, and some other lycopsids, across most of tropical Euramerica. In this paper, we follow-up on historical reports of silicified tree-stumps in Peoria County, northwest-central Illinois, USA, which have significant implications for understanding Carboniferous Coal Forest collapse. Rooted near the paleoweathered top of the Lonsdale Limestone, and widespread across an area of ~250km², the silicified tree-stumps belong to Amyelon-type coniferopsids. A key feature of the fossil wood is the occurrence of abundant axial parenchyma arranged along irregular growth interruptions, suggestive of climatic seasonality, an inference consistent with silicic preservation. The silicified fossil forest directly underlies the Exline Limestone and Athensville Coal, the horizons that mark the US-wide loss of Lycospora, and demonstrate that lowland areas were colonized by dryland coniferopsid forests following Coal Forest collapse. Placed in a cyclothem context, the silicified fossil forest horizon lies above the Maria Creek mudstone paleosol (top of Piasa cyclothem), in which earlier d¹⁸O analyses have identified a major pulse of global warming, and coincides with the 'Hanna City' paleosol (top of Lonsdale cyclothem), which is correlative with the Seminole Sandstone, a Midcontinent incised valley-fill representative of one of the most profound glacioeustatic falls seen in the Pennsylvanian record. Our new findings therefore demonstrate that Coal Forest collapse was closely linked to intensification of glacial cycle amplitude near the Desmoinesian–Missourian boundary, involving both extreme episodes of global warming and cooling.



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The paths and timing of late Paleozoic ice revisited: New stratigraphic and paleo-ice flow interpretations from a glacial succession in the upper Itararé Group (Paraná Basin, Brazil)

Publication date: 15 January 2018
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 490
Author(s): Thammy Ellin Mottin, Fernando Farias Vesely, Mérolyn Camila Naves de Lima Rodrigues, Felipe Kipper, Paulo Alves de Souza
This paper examines a glacial diamictite-bearing succession from the upper Itararé Group (Taciba Formation) in eastern Paraná Basin, Brazil. The object of study provides the opportunity to investigate in detail the late stages of glacial sedimentation during the Late Paleozoic Ice Age (LPIA) in this sector of SW Gondwana, with implications for glacial cyclicity and regional paleo-ice flow reconstructions. Sedimentology, geological mapping and palynological analysis allowed the recognition of four facies associations, comprising subaqueous outwash, mass-transport, tide-influenced delta-front, and tide-influenced delta plain deposits. The succession records at least two episodes of ice-margin advance and retreat into a marine-influenced environment and can be placed in the earliest Permian based on the palynomorph assemblage. Cross stratification in outwash facies and deltaic deposits indicate sediment transport to the SW, the same revealed by deformational structures in mass-transport diamictites derived from downslope resedimentation of glaciomarine sediments during deglaciation. A glacial source to NE is therefore indicated and is in agreement with paleo-ice flow directions obtained from previously studied localities to the north. This north-derived early Permian glaciation contrasts with glacial sources to the SE recognized in the lower and middle intervals of the Itararé Group. The scenario suggests a geometric reconfiguration of the Paraná Basin during the LPIA and the migration of ice centers with time during the Late Paleozoic Ice Age in SW Gondwana.



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Paleoecological and taphonomical aspects of the Late Miocene vertebrate coprolites (Urumaco Formation) of Venezuela

Publication date: 15 January 2018
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 490
Author(s): Paula Dentzien-Dias, Jorge Domingo Carrillo-Briceño, Heitor Francischini, Rodolfo Sánchez
Coprolites (fossil feces) provide important paleoecological information, such as diet of the producer, parasite infestation and gut microbiota, which cannot be accessed through body remains. The Upper Miocene Urumaco Formation, in western Venezuela, has a diverse vertebrate fauna composed of ground sloths, rodents, reptiles, fishes and amphibians, as well as coprolites. Here we describe 106 coprolites produced by a range of carnivorous and herbivorous vertebrates, classified into five different morphotypes based on their size and shape, suggesting different producers. Herbivorous morphotypes (M1, M2 and M5) are the most abundant (59%). The most common inclusions in these coprolites are Poaceae remains, although Eudicotyledoneae fragments, bacteria and cyanobacteria filaments were also found. The M1 morphotype has a bullet shape with longitudinal grooves; the M2 morphotype is rounded to oval, with at least one distinctive tapered end; and the M5 morphotype is a short cylinder with a rough surface, and rounded ends. In contrast, the morphotypes M3 and M4 are attributed by us to carnivores and have different inclusions. While M3 is a large cylinder with rounded ends and contains bacteria, nematode eggs and phytoliths, M4 is sausage-shaped and has muscle cells preserved inside. Based on the co-occurring fauna and the morphology of the coprolites, the probable producers were inferred as the following: M1, a rodent; M2, a notoungulate; M3, a crocodilian; M4, an indeterminate carnivore; and M5, a sirenian. The preservation of herbivorous and carnivorous coprolites with bacterial, parasitological and muscle remains in the same formation and even the same outcrop is rare in the geological record. This unique association and preservation suggests early lithification promoted by rapid burial, although the presence of the boring trace Gastrochaenolites in a single specimen indicates some degree of time-averaging.

Graphical abstract

from # All Medicine by Alexandros G. Sfakianakis via alkiviadis.1961 on Inoreader http://ift.tt/2ylasrb

Editorial Board

Publication date: 15 January 2018
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 490





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The effects of predation on the preservation of ontogenetically young individuals

Publication date: 15 January 2018
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 490
Author(s): Matthew J. Pruden, Steven E. Mendonca, Lindsey R. Leighton
Size-frequency distributions are an integral part of understanding species interactions and population dynamics. Numerous studies have observed that the mode of the size-frequency distribution of fossil assemblages is shifted towards the larger size classes, relative to the mode of live assemblages, suggesting there is a loss of individuals from the smaller size fractions in fossil assemblages. The loss of these individuals is often attributed to size-selective taphonomy, however, selective predation on younger, smaller individuals may also play a role. This study analyzes the effect of predation on the preservation of ontogenetically young individuals by examining predation traces relative to size of biconvex and concavo-convex brachiopods from the Ordovician, Devonian, and Pennsylvanian. We constructed sets of two size-frequency distributions: one based on the size of the brachiopod preserved in the fossil record, and another based on the size of the brachiopod when it was attacked, as indicated by repair scars. For the concavo-convex brachiopods, the size-at-attack and fossil death assemblage curves are different; repairs occurred early in ontogeny, at sizes at which fossils were not preserved. Thus, predation on concavo-convex brachiopods focused on small individuals, the same size that is missing from the fossil record. Furthermore, as the repair frequencies of concavo-convex brachiopods increase, so does the difference between the medians of the distributions, i.e., as repair frequency increases, the fewer ontogenetically young individuals are preserved (Spearman's rank correlation [r=+0.892, p=0.012, n=7]). If size-selective taphonomy had been solely responsible for the loss of ontogenetically young individuals, then there should have been a preferential loss of all small bodied individuals, regardless of taxon or age, but this pattern was not observed. The results presented herein suggest that predation plays a larger role on the preservation of ontogenetically young individuals than has been previously thought.



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A record of Late Ordovician to Silurian oceanographic events on the margin of Baltica based on new carbon isotope data, elemental geochemistry, and biostratigraphy from two boreholes in central Poland

Publication date: 15 January 2018
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 490
Author(s): Nicholas B. Sullivan, David K. Loydell, Paul Montgomery, Stewart G. Molyneux, Jan Zalasiewicz, Kenneth T. Ratcliffe, Elaine Campbell, James D. Griffiths, Gavin Lewis
New stable isotope data from organic carbon (δ¹³Corg) and inorganic elemental geochemistry data have been generated from Upper Ordovician to Silurian strata in two boreholes in the Lublin Basin of Poland: Grabowiec-6 and Zwierzyniec-1. They have been integrated here with biostratigraphical data from graptolites, acritarchs, and chitinozoans. Faunal assemblages from Grabowiec-6 indicate that it spans from the Katian (clingani graptolite Biozone) to the Gorstian (scanicus graptolite Biozone); δ¹³Corg values from this section record the Sheinwoodian Ireviken Excursion, the Homerian Mulde Excursion, and a minor positive shift associated with the lower Ludfordian leintwardinensis Biozone. The second section, Zwierzyniec-1, spans the Sandbian through Gorstian (nilssoni Biozone); δ¹³Corg values record the Hirnantian carbon isotope excursion (HICE) and the Ireviken Excursion as well.Elemental geochemistry data is used to recognize subtle changes in provenance and lithology. Significant increases in the abundance of V and Mo are recognized in strata deposited above the Ireviken Excursion. The enrichment of these redox sensitive elements suggests that persistent regional anoxia and euxinia may be associated with the aftermath of these oceanographic disturbances. Some of these same trace elements, along with Fe2O3, and Pb are also abundant in strata coeval with, or just below the Ireviken and HICE excursions. This may have a causal link with malformed palynomorphs observed at these intervals by some workers, which are thought to reflect toxic levels of dissolved heavy metals in the world's oceans.



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Paired carbonate-organic carbon and nitrogen isotope variations in Lower Mississippian strata of the southern Great Basin, western United States

Publication date: 15 January 2018
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 490
Author(s): Dev Maharjan, Ganqing Jiang, Yongbo Peng, Robert A. Henry
The Early Mississippian K-O (Kinderhookian-Osagean) carbon isotope (δ¹³C) excursion or TICE (mid-Tournaisian carbon isotope excursion) is one of the most prominent positive δ¹³C excursions of the Phanerozoic. Recent studies raise uncertainties about the representative shape (single vs. double spikes) and magnitude of this δ¹³C excursion (3‰ to ≥6‰ in South China; ≥5.5‰ in Europe; and ≥7‰ in North America) and the 3‰ unidirectional increase in nitrogen isotopes across the δ¹³C excursion, which is unanticipated considering the amount of organic carbon burial required to form the δ¹³C excursion and the resultant oxygen increase and global cooling. To test if stratigraphic completeness and spatial isotope variations caused such uncertainties, we have conducted paired carbonate carbon (δ¹³Ccarb), organic carbon (δ¹³Corg) and nitrogen (δ¹⁵N) isotope analyses across the K-O interval in two well-exposed sections of the southern Great Basin, western United States. The two sections represent proximal shallow-water and distal deep-water depositional settings of a west-dipping carbonate ramp. In the distal ramp section where no exposure surface is present, both δ¹³Ccarb and δ¹³Corg show double spikes with peak δ¹³Ccarb values up to 7‰ and a negative shift down to 4‰ between the peaks. In the proximal shallower-water section where two karstic disconformities are observed, δ¹³Corg shows similar double spikes but δ¹³Ccarb displays only a single peak with the highest value of 5.5‰. The missing δ¹³Ccarb spike is likely caused by diagenetic alteration below a karstic disconformity that lowered δ¹³Ccarb but not δ¹³Corg values, resulting in smaller magnitude of the δ¹³Ccarb excursion. These features suggest that the 7‰ magnitude and double spikes are more representative of the K-O δ¹³C excursion in the southern Great Basin. The smaller magnitude of the K-O δ¹³Ccarb excursion in some sections of the Great Basin and the TICE in other sections globally may have overprinted with local environmental/diagenetic signal or resulted from stratigraphic hiatus/truncation, which needs to be clarified in future research.The δ¹⁵N across the K-O δ¹³C excursion in the distal ramp section is decoupled from δ¹³C, with the majority of δ¹⁵N values around 4±1‰ that do not show any obvious temporal trend. In contrast, δ¹⁵N values in the shallow-water section is coupled with the K-O δ¹³C excursion, with a 3‰ positive shift from 4‰ to 7‰ at the rising limb of the δ¹³C excursion and a negative shift from 7‰ to 1–2‰ at the falling limb of the δ¹³C excursion. The δ¹⁵N trend from the distal ramp section is, in some extent, comparable with that documented from a section in South China, while the coupled δ¹³C–δ¹⁵N pattern in the proximal section seems better explain the potential redox change across a prominent δ¹³C excursion. Considering the sensitivity of δ¹⁵N to redox conditions of depositional environments, a more comprehensive δ¹⁵N study in a broader paleogeographic context is required to better understand the interactions between carbon and nitrogen cycles across the K-O interval—a critical transition from the mid-Paleozoic greenhouse clime to Late Paleozoic Ice Age (LPIA).



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Soil phytoliths as indicators of initial human impact on San Cristóbal Island, Galápagos

Publication date: 15 January 2018
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 490
Author(s): Fernando J. Astudillo
I analyzed phytoliths from soil profiles on San Cristóbal Island in the Galápagos Islands to determine whether historical human impact and recent vegetation dynamics are visible in the phytolith record. I extracted phytoliths from soil samples taken from four test pits located at the village, an abandoned field, a forest, and an active agricultural field - all located within the former El Progreso plantation (AD 1860–1920). Changes in the ratio of tree to grass phytoliths with depth in all four samples suggest changes in vegetation composition from forest to open vegetation dominated by grasses, which reflects the removal of forest with colonization and the first permanent human occupation of the archipelago in the middle 19th century. This paper shows that the changes in vegetation brought about by colonization and land clearing for plantations are documented in the soil phytoliths record, and suggests that phytoliths can be used as an indicator of past vegetation change in future work on the historical ecology of the Galápagos archipelago.



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Photosynthetic pathway of grass fossils from the upper Miocene Dove Spring Formation, Mojave Desert, California

Publication date: 15 January 2018
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 490
Author(s): Hannah M. Liddy, Sarah J. Feakins, Frank A. Corsetti, Rowan Sage, Nancy Dengler, David P. Whistler, Gary T. Takeuchi, Mark Faull, Xiaoming Wang
The spread of grasslands in the Miocene and of C4 grasses in the late Miocene-Pliocene represents a major development in terrestrial plant evolution that affected the climate system and faunal evolution. The macrofossil record of grasses is sparse, likely due to the limited preservation potential of grasses. Diagnosis of the C3 or C4 photosynthetic pathway depends on preservation of both cellular structures and organic carbon for isotope analysis. Here we analyze the anatomical and isotopic composition of newly-collected grass fossils from the Dove Spring Formation, Red Rock Canyon State Park, California, USA, located in the El Paso Basin on the western side of the Basin and Range Province, a site previously identified as one of the earliest known C4 grass fossil bearing localities. We analyzed the anatomical and geochemical characteristics of these new grass fossils dated to 12.01–12.15Ma. The fossils analyzed in this study include grass shoots and in cross-section display anatomy indicative of the C3 photosynthetic pathway. We isolated organic carbon from the stem fossils and determined the carbon isotopic composition to be −24.8±0.5‰. Together, the anatomical and geochemical analyses confirm that these plants used the C3 photosynthetic pathway. Our findings are consistent with dietary evidence based on tooth enamel from grazing mammals of available C3 resources in the same sections. These newly reported Miocene-age C3 grass fossils contribute to a sparse macrofossil record of grass evolution. Overall, paleoecological reconstructions at this site indicate more humid conditions during the Miocene compared to the modern Mojave Desert with C3 grasses and diverse grazing mammals.



from # All Medicine by Alexandros G. Sfakianakis via alkiviadis.1961 on Inoreader http://ift.tt/2yl9ScU

Paleodietary change and its implications for aridity indices derived from δ18O of herbivore tooth enamel

Publication date: 15 January 2018
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 490
Author(s): J. Tyler Faith
A large body of research provides reconstructions of ancient water deficit—the difference between potential evapotranspiration and precipitation—using an aridity index derived from the δ¹⁸O values of tooth enamel from evaporation sensitive (ES) and evaporation insensitive (EI) mammalian herbivores. The former are typically ruminants that obtain most of their water from leafy dicots (the δ¹⁸O of their enamel reflects evaporation of leaf water), whereas the latter are non-ruminants dependent on surface water (the δ¹⁸O of their enamel reflects local meteoric water). Use of the index requires that fossil taxa are correctly classified as ES or EI. This study examines how paleodietary change can influence such classifications. In modern ruminant ungulates, dependence on drinking water is related to the proportion of grass versus dicots in the diet. This means that paleodietary change in ruminant ungulates should be associated with shifts in drinking behavior, altering enamel δ¹⁸O values and biasing the aridity index. Such bias is evident in estimates of water deficit derived from the enrichment of enamel δ¹⁸O in fossil Tragelaphini relative to Hippopotamidae from East African fossil sites spanning the last ~4.4Myr. Elevated grass consumption (measured by enamel δ¹³C) in the former is associated with reduced enrichment of enamel δ¹⁸O relative to the latter, translating to lower estimates of water deficit. In conducting such analyses of fossil ungulates, the diet of those ungulates must be screened to ensure consistency with the assumptions of the method.



from # All Medicine by Alexandros G. Sfakianakis via alkiviadis.1961 on Inoreader http://ift.tt/2AAmbIk

Late Middle Miocene volcanism in Northwest Borneo, Southeast Asia: Implications for tectonics, paleoclimate and stratigraphic marker

Publication date: 15 January 2018
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 490
Author(s): Mu. Ramkumar, M. Santosh, R. Nagarajan, S.S. Li, M. Mathew, D. Menier, N. Siddiqui, J. Rai, A. Sharma, S. Farroqui, M.C. Poppelreiter, J. Lai, V. Prasad
Explosive volcanic events often produce pyroclastic materials that can be recognized from the geological record. These discrete pyroclastics form regional marker beds. Here we report the occurrence of a tephra layer interbedded within very thick coal beds near Mukah, Sarawak, Borneo. Traceable for tens of kilometers in the Mukah area of Sarawak, this tephra layer can be considered as regional stratigraphic marker with precise chronostratigraphic control. Systematic sedimentological, mineralogical, geochemical and zircon UPb geochronological studies have revealed a major effusive volcanic event during the latest Middle Miocene, presumably contemporaneous and/or related to a magmatic event of an earlier phase of the Mt. Kinabalu pluton or magmatism in West Sarawak or East Sabah. The volcanic event had promoted catastrophic flooding of coastal swamps and fall-out from the ash clouds that formed a regionally monotonous tephra layer across the Serravallian- Tortonian boundary. In conjunction with the regional occurrences of trap rocks, structural trends and known tectonic events, we constrained the regional depositional environments, and climate. The tephra layer was deposited in a coastal plain-swamp,- seasonal, shallow, high-moderate energy, fluvial channel-lacustrine environmental setting, wherein atmospheric fallout and eroded material from regoliths formed over older basement and volcanic rocks of the hinterland which were mixed to produce the tephra layer. This tephra layer is sandwiched between the very thick coal beds. A pre-existent volcanic chamber that was active for a long time, also experienced periodic explosive activity from probably the same magma chamber and conduit and including a major explosive activity that recycled early-formed crystals and felsic magma (rhyolite-dacite) during the major effusive event are also recognized. Our findings provide robust evidence for the prevalence of intensive chemical weathering under a wet-humid climate, and relative tectonic quiescence before the major effusive event, and the existence of vast, monotonously gently-sloping coastal plains and luxuriant vegetation akin to the present.

Graphical abstract

from # All Medicine by Alexandros G. Sfakianakis via alkiviadis.1961 on Inoreader http://ift.tt/2ykWuoX

Late Pleistocene glacial forest elements of Brazilian Amazonia

Publication date: 15 January 2018
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 490
Author(s): W.J.S. Lima, M.C.L. Cohen, D.F. Rossetti, M.C. França
Pollen data recovered from the sedimentary record of western Amazonia is still inadequate to fully address climate changes over the Last Glaciation in this region. The present work focuses vegetation dynamics from an area of southwestern Amazonia during the past 42,000cal yr B.P. based on the integration of previous and new pollen data. Sediment cores were sampled from two sites covered by tropical rainforest in fluvial terraces of the Madeira River, a major southern Amazonian tributary. The results indicated a significant proportion of cold-adapted Andean tree species, represented by Alnus (0–20%), Hedyosmum (1–15%), Podocarpus (0–5%), Illex (1–11%) and Weinmannia (0–1%) at least between >43,163–42,018cal yr B.P. and 10,394–10,240cal yr B.P. During the Holocene, only pollen representative of herbs and modern Amazonian vegetation persisted. The new pollen record confirmed previous documented results that vegetation communities presently restricted to Andean areas at altitudes higher than 2000–3000m, occupied this region of the Amazonian lowlands close to the onset and probably also during the Last Glacial Maximum.



from # All Medicine by Alexandros G. Sfakianakis via alkiviadis.1961 on Inoreader http://ift.tt/2yluzW4

Uranium series dating of Great Artesian Basin travertine deposits: Implications for palaeohydrogeology and palaeoclimate

Publication date: 15 January 2018
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 490
Author(s): Stacey C. Priestley, Karl E. Karlstrom, Andrew J. Love, Laura J. Crossey, Victor J. Polyak, Yemane Asmerom, Karina T. Meredith, Ryan Crow, Mark N. Keppel, Marie A. Habermehl
Travertine deposits precipitated by groundwater discharging from the Great Artesian Basin (GAB) are widespread in central Australia and have the potential to provide a record of palaeohydrogeology and palaeoclimate. The GAB is one of the largest artesian basins in the world and a relationship between travertine deposits and recharge sites has potential importance regarding the time and position of past climate events, given that the travertines growth forms from precipitation discharge. We sampled numerous travertine sites in the southwest section of the GAB as a first approach to test this relationship. U-series dating of the travertine deposits reveal that spring discharge has likely been episodic for the last several hundred thousand years. Spring travertine deposition occurred episodically around 465±50ka, 370±20ka, 335±15ka, 285–240ka, 185±10ka, 160–150ka, 110–100ka and during the past 30ka. The periodicity of travertine ages observed with simultaneous deposition at multiple locations, argues for regional palaeohydrologic controls. Comparison of the travertine deposit ages with climate proxies in Australia shows that elevated travertine deposition rates are synchronous with wet periods in both central and southern Australia. Due to the large size of the GAB and that the recharge zones extend over multiple climatic regions of Australia, the times of travertine deposition are interpreted to represent times of high rainfall regionally. This study shows that the travertine deposits of central Australia provide a datable archive of past climate and hydrogeology of importance for understanding the groundwater evolution of the Great Artesian Basin, and that further more comprehensive studies are warranted.



from # All Medicine by Alexandros G. Sfakianakis via alkiviadis.1961 on Inoreader http://ift.tt/2Ayly1J

Palaeobiodiversity research based on stable isotopes: Correction of the sea spray effect on bone carbonate δ13C and δ18O by Gaussian Mixture Model clustering

Publication date: 15 January 2018
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 490
Author(s): Andrea Göhring, Markus Mauder, Marina Vohberger, Olaf Nehlich, Claus von Carnap-Bornheim, Volker Hilberg, Peer Kröger, Gisela Grupe
Transport of sea spray aerosol in coastal areas ("sea spray" effect) can have a marked influence on isotopic ratios of terrestrial ecosystems shifting terrestrial isotopic ratios towards unusual high values masking the original terrestrial signature. It is unclear so far if and to what extend sea spray influences other stable isotopes besides sulphur. In this study, we examined if the effect was also detectable in carbon, nitrogen, and oxygen stable isotopes of bone collagen and carbonate, respectively.Multi-isotope data of mammals sampled from the Viking Haithabu and medieval Schleswig sites in Northern Germany were analysed according to a previously developed approximation procedure and Gaussian Mixture Model (GMM) clustering in order to quantify the sea spray effect in the isotopes under study.While we were able to approximate an influence of the sea spray effect of at least 32.8% and 62.8% in δ¹³Ccarb and δ¹⁸Ocarb, respectively, it was not possible to validate or approximate this effect in δ¹³Ccoll and δ¹⁵Ncoll. Indeed, detection of the sea spray effect not only in δ³⁴Scoll, but also in δ¹³Ccarb and δ¹⁸Ocarb is of particular importance for studies on both prehistoric and recent material.GMM clustering on terrestrial herbivorous and marine piscivorous mammals was used to confirm the existing influence and to validate the approximated correction for the sea spray effect in the respective isotopic ratios (δ¹³Ccarb, δ¹⁸Ocarb, δ³⁴Scoll) and the correction for the limnic influence on δ¹⁵Ncoll approximated in a previous study. After correction, the clustering results markedly changed corresponding to the actual diet and habitat preference of the examined species. Although our study focused on palaeoecology, we suggest that GMM clustering also constitutes a very useful tool for modern landscape ecology based on stable isotope analyses.



from # All Medicine by Alexandros G. Sfakianakis via alkiviadis.1961 on Inoreader http://ift.tt/2ylupxW