High potential for weathering and climate effects of non-vascular vegetation in the Late Ordovician

It has been hypothesized that predecessors of today’s bryophytes significantly increased global chemical weathering in the Late Ordovician, thus reducing atmospheric CO2 concentration and contributing to climate cooling and an interval of glaciations. Studies that try to quantify the enhancement of weathering by non-vascular vegetation, however, are usually limited to small areas and low numbers of species, which hampers extrapolating to the global scale and to past climatic conditions. Here we present a spatially explicit modelling approach to simulate global weathering by non-vascular vegetation in the Late Ordovician. We estimate a potential global weathering flux of 2.8 (km3 rock) yr−1, defined here as volume of primary minerals affected by chemical transformation. This is around three times larger than today’s global chemical weathering flux. Moreover, we find that simulated weathering is highly sensitive to atmospheric CO2 concentration. This implies a strong negative feedback between weathering by non-vascular vegetation and Ordovician climate

Modulation of Human Mesenchymal Stem Cell Immunogenicity through Forced Expression of Human Cytomegalovirus US Proteins

BACKGROUND: Mesenchymal stem cells (MSC) are promising candidates for cell therapy, as they migrate to areas of injury, differentiate into a broad range of specialized cells, and have immunomodulatory properties. However, MSC are not invisible to the recipient's immune system, and upon in vivo administration, allogeneic MSC are able to trigger immune responses, resulting in rejection of the transplanted cells, precluding their full therapeutic potential. Human cytomegalovirus (HCMV) has developed several strategies to evade cytotoxic T lymphocyte (CTL) and Natural Killer (NK) cell recognition. Our goal is to exploit HCMV immunological evasion strategies to reduce MSC immunogenicity. METHODOLOGY/PRINCIPAL FINDINGS: We genetically engineered human MSC to express HCMV proteins known to downregulate HLA-I expression, and investigated whether modified MSC were protected from CTL and NK attack. Flow cytometric analysis showed that amongst the US proteins tested, US6 and US11 efficiently reduced MSC HLA-I expression, and mixed lymphocyte reaction demonstrated a corresponding decrease in human and sheep mononuclear cell proliferation. NK killing assays showed that the decrease in HLA-I expression did not result in increased NK cytotoxicity, and that at certain NK∶MSC ratios, US11 conferred protection from NK cytotoxic effects. Transplantation of MSC-US6 or MSC-US11 into pre-immune fetal sheep resulted in increased liver engraftment when compared to control MSC, as demonstrated by qPCR and immunofluorescence analyses. CONCLUSIONS AND SIGNIFICANCE: These data demonstrate that engineering MSC to express US6 and US11 can be used as a means of decreasing recognition of MSC by the immune system, allowing higher levels of engraftment in an allogeneic transplantation setting. Since one of the major factors responsible for the failure of allogeneic-donor MSC to engraft is the mismatch of HLA-I molecules between the donor and the recipient, MSC-US6 and MSC-US11 could constitute an off-the-shelf product to overcome donor-recipient HLA-I mismatch

Identification and characterization of a rich population of CD34mesenchymal stem/stromal cells in human parotid, sublingual and submandibular glands

Mesenchymal stem/stromal cells (MSCs) play crucial roles in maintaining tissue homeostasis during physiological turnovers and injuries. Very little is known about the phenotype, distribution and molecular nature of MSCs in freshly isolated human salivary glands (SGs) as most reports have focused on the analysis of cultured MSCs. Our results demonstrate that the cell adhesion molecule CD34 was widely expressed by the MSCs of human major SGs, namely parotid (PAG), sublingual (SLG) and submandibular (SMG) glands. Further, gene expression analysis of CD34+ cells derived from fetal SMGs showed significant upregulation of genes involved in cellular adhesion, proliferation, branching, extracellular matrix remodeling and organ development. Moreover, CD34+ SMG cells exhibited elevated expression of genes encoding extracellular matrix, basement membrane proteins, and members of ERK, FGF and PDGF signaling pathways, which play key roles in glandular development, branching and homeostasis. In vitro CD34+ cell derived SG-MSCs revealed multilineage differentiation potential. Intraglandular transplantation of cultured MSCs in immunodeficient mice led to their engraftment in the injected and uninjected contralateral and ipsilateral glands. Engrafted cells could be localized to the stroma surrounding acini and ducts. In summary, our data show that CD34+ derived SG-MSCs could be a promising cell source for adoptive cell-based SG therapies, and bioengineering of artificial SGs

Understanding renal posttransplantation anemia in the pediatric population

Advances in renal transplantation management have proven to be beneficial in improving graft and patient survival. One of the properties of a well-functioning renal allograft is the secretion of adequate amounts of the hormone erythropoietin to stimulate erythropoiesis. Posttransplantation anemia (PTA) may occur at any point in time following transplantation, and the cause is multifactoral. Much of our understanding of PTA is based on studies of adult transplant recipients. The limited number of studies that have been reported on pediatric renal transplant patients appear to indicate that PTA is prevalent in this patient population. Erythropoietin deficiency or resistance is commonly associated with iron deficiency. An understanding of the risk factors, pathophysiology and management of PTA in the pediatric renal transplant population may provide guidelines for clinicians and researchers in the pursuit of larger prospective randomized control studies aimed at improving our limited knowledge of PTA. Recognition of PTA through regular screening and evaluation of the multiple factors that may contribute to its development are recommended after transplantation

Syngas Production, Storage, Compression and Use in Gas Turbines

This chapter analyses syngas production through pyrolysis and gasification, its compression and its use in gas turbines. Syngas compression can be performed during or after thermal treatment processes. Important points are discussed related to syngas ignition, syngas explosion limit at high temperatures and high pressures and syngas combustion kinetics. Kinetic aspects influence ignition and final emissions which are obtained at the completion of the combustion process. The chapter is organized into four subsections, dealing with (1) innovative syngas production plants, (2) syngas compressors and compression process, (3) syngas ignition in both heterogeneous and homogeneous systems and (4) syngas combustion kinetics and experimental methods. Particular attention is given to ignition regions that affect the kinetics, namely systems that operate at temperatures higher than 1000 K can have strong ignition, whereas those operating at lower temperatures have weak ignition. Keywords: Pyrogas Pyrolysis Ignition Syngas Compression GasificationacceptedVersio

Strontium isotopic geochemistry of Pan-African/Brasiliano rocks, Chapada copper deposit, Goiás, Brazil

Das Trägergestein der Chapada Kupferlagerstätte in Goiás ist in metamorpher Hoch-Amphibolitfazies ausgebildet. Gesamtgesteins- und individuelle Mineral Rb-Sr-Isochronen mit einem 87 Sr/ 86 Sr-Initialwert (I) von 0,70414±0.00005 ergeben für die Kristallisation der Vulkanite und Magmatite, die die Metamorphose vordatieren, ein Alter von 561±9 Mio Jahre. Die Datierung der Metamorphose während der panafrikanisch/brasilianischen Orogenese (700 bis 450 Mio Jahre) ergibt 532±1 Mio Jahre. Das Mineral-Isochronenalter eines Dioritkörpers porphyrischen Gefüges, der in die Schiefer intrudierte, beträgt 534±16 Mio Jahre (I=0,70415 ±0,00004). Das Ergebnis niedriger Initial-Werte dieser Isochronen ergibt für die Schiefer bei Chapada ein Ausgangs-Material im Bereich des oberen Mantels oder der tieferen Kruste; diese Ausgangswerte sind charakteristisch für magmatische Tätigkeit in Verbindung mit Inselbögen. Das unterkambrische Alter des Trägergesteins bei Chapada steht im Widerspruch zu dem bisher angenommenen mittelproterozoischen Alter und ist ein Hinweis auf eine mögliche Phase intensiverer pan-afrikanisch/brasilianischer magmatischer Aktivität in Zentral-Brasilien als ursprünglich angenommen wurde. Whole rock and mineral Rb-Sr isochrons from the upper amphibolite grade metamorphic host rocks of the Chapada copper deposit in Goiás, Brazil, yield an age of 561±9 Ma, with a 87 Sr/ 86 Sr initial (I) of 0.70414±0.00005, for the crystallization of pre-metamorphic volcanic and igneous rocks and 532 ±1 Ma for their metamorphism during the Pan-African/Brasiliano orogeny (700-450 Ma). A porphyritic diorite stock which intruded the host schists yields a mineral isochron age of 534±16 Ma (I=0.70415±0.00004). The low I values determined from these isochrons suggest that the host schists at Chapada were derived from upper mantle or lower crust material and are characteristic of magmatic products associated with island arcs. The Early Cambrian age of the host rocks at Chapada contradicts the previously assigned mid-Proterozoic age and suggests that Pan-African/Brasiliano magmatic activity may have been more extensive in central Brazil than previously thought. Les roches qui contiennent le gisement de cuivre de Chapada (Goias, Brésil) sont des schistes cristallins appartenent au facies dupérieur des amphibolites. Dans des volcanites et des roches orthomagmatiques appartenant à cet ensemble, des isochrones Rb-Sr sur roches totales et sur minéraux donnent un âge de 561±9 Ma avec un rapport initial de 0,70414±0,00005 pour la cristallisation pré-métamorphique et un âge de 532±1 Ma pour le métamorphisme, lié à l'orogenèse pan-africaine / brésilienne. Un pluton de diorite porphyrique, qui intrude les schistes cristallins donne, par isochrone sur minéraux, un âge de 534±16 Ma (rapport initial de 0,70415±0,00004). Les valeurs basses des rapports initiaux de ces diverses roches suggèrent que les schistes de Chapada sont dérivés de matériaux mantelliques ou crustaux profonds et présentent les caractères des produits magmatiques associés aux arcs insulaires. Leur âge éo-cambrien, en contradiction avec l'âge mésoprotérozoïque admis jusqu'ici, permet de penser que l'activité magmatique pan-africaine/brésilienne dans le centre du Brésil a été plus intense que ce qu'on croyait jusqu'ici. Вмещающие породы зал ежи меди Chapada в Goiбs представляют собой а мфиболитовую фацию в ысшей степени метаморфизм а. Цельная порода и отд ельные минералы дают для кри сталлизации вулкани тов и магматитов до метаморфизма нача льное значение соотн ошения стронция в 0,70414±0,00005, что раз решает принять их возраст в 561± 9 Мио лет, а возраст мет аморфизма в 532±1 Мио, т. е. отнести его к периоду панафриканского -бра зильского орогенеза / 700 до 450 Мио /. При определении в озраста минералов из диоритных тел порфиритовых тек стур, интрудированны х в сланец, получили дат ы в 534±16 Мио лет / 1 = 0,70415 = 0,00004 /. Такое низкое значе ние исходных величин соотношения изотопов разрешает п редполагать, что материал для Chapada при несен был из мантии, или глубинных регион ов коры. Эти исходные з начения характерны для магма тической деятельнос ти типа островных дуг. Во зраст вмещающих поро д считают средне-протерозойск им; это стоит в противо речии с новейшими данными, п о которым он может быт ь только нижнекембрий ским. Это также указыв ает на то, что фаза пан-африка нско-бразильской маг матической активности в централ ьной Бразилии протек ала, возможно, гораздо инт енсивнее, чем принима ли это до сих пор.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47849/1/531_2005_Article_BF01830182.pd

Environmental effects of ozone depletion, UV radiation and interactions with climate change : UNEP Environmental Effects Assessment Panel, update 2017

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