Was atmospheric CO2 capped at 1000ppm over the past 300 million years?

AbstractAtmospheric carbon dioxide concentration has shifted dynamically over the Phanerozoic according to mass balance models and the majority of proxy estimates. A new paleo-CO2 proxy method underpinned by mechanistic understanding of plant stomatal, isotopic and photosynthetic responses to CO2 has provocatively claimed that maximum paleoatmospheric CO2 was capped at 1000ppm for the majority of the past 300 million years. Here we evaluate the robustness of the new paleo-proxy CO2 model by testing its sensitivity to initial parameterization and to scaling factors employed to estimate paleophysiological function from anatomical and morphological traits. A series of sensitivity analyses find that the model is robust to modification in some of the constants employed, such as CO2 compensation point and mesophyll conductance, resulting in variability in paleo-CO2 estimates which are already accounted for in the error propagation of the model. We demonstrate high sensitivity in the model to key input parameters such as initial fossil plant assimilation rate, termed A0 and scaling factors used to estimate stomatal conductance from measurements of fossil stomata. Incorrect parameterization of A0 has resulted in under estimation of pCO2 by as much as 600ppm. Despite these uncertainties, our analysis highlights that the new mechanistic paleo-CO2 proxy of Franks et al. (2014) has significant potential to derive robust and more accurate CO2 estimates from fossil plant stomata, as long as parameterization of A0 is strongly justified with species appropriate morphological and anatomical data. We highlight methods that can be used to improve current estimates of fossil plant assimilation rates, reduce uncertainty associated with implementation of the Franks et al. (2014) model and importantly add to understanding of patterns of plant productivity over the Phanerozoic, for which there currently is no consensus

Climate- and Eustasy-Driven Cyclicity in Pennsylvanian Fusulinid Assemblages, Donets Basin (Ukraine)

A model of cyclic recurrence (~ 0.6–1.2 myr) of three fusulinid assemblages in the Middle Pennsylvanian siliciclastic–carbonate succession of the Donets Basin is proposed. Each cycle records progressive turnover of assemblages in shallow marine environments in response to sea-level and regional climate change. A Hemifusulina-assemblage (A), adapted to cooler and reduced salinity seawater records the onset of sea level rise accompanied by humid climatic conditions. Sea level high stand is captured by the Beedeina–Neostaffella–Ozawainella–Taitzehoella (or Beedeina-dominated) assemblage (B), characteristic of relatively deeper-water environments. The B assemblage is successively replaced by the most diverse population of the warm-water Fusulinella-dominated assemblage (C). This assemblage, which occurs in the upper limestones of each fusulinid cycle records the onset of sea level fall accompanied by a shift to drier conditions and likely increased seawater salinity. The proposed model permits robust interbasinal correlation of the Pennsylvanian successions of the Tethyan realm. Fusulinids of the A and C2 assemblages are the most provincial and therefore the most useful for paleogeographic reconstructions. Specifically, they delineate originally contiguous regions that subsequently were dispersed hundreds to thousands of kilometers, whereas fusulinids of the B assemblage hold the highest potential for global correlation. Extinction at the Moscovian–Kasimovian transition of fusulinid genera of the A and B assemblages, which inhabited predominately cooler and normal salinity (perhaps hyposaline) waters, can be explained by the onset of global warming in the earliest Late Pennsylvanian. Fusulinid assemblages define various types of distribution patterns that differ by tectonic setting of the studied basins suggesting that fusulinid assemblage patterns hold potential for reconstructing the paleogeography and tectonic evolution of Pennsylvanian basins of eastern Laurasia

Sequence Stratigraphy and Onlap History of the Donets Basin, Ukraine: Insight into Carboniferous Icehouse Dynamics

The degree to which Permo-Carboniferous cyclothemic successions archive evidence for long-term variations in ice volume during the Late Paleozoic Ice Age is insufficiently resolved. Here we develop the sequence stratigraphy and onlap-offlap history for a 33-my interval of the Carboniferous using the U-Pb calibrated succession of the Donets Basin, Ukraine, in order to assess the relationship between sea-level, high-latitude changes in glacial extent, and climate. Integrated subsurface and outcrop data permit meter-scale correlation of 242 biostratigraphically constrained limestones and coals, and in turn individual cyclothems, across ~250 km of the Donets Basin. Rapid uniform subsidence and basinwide continuity of marker beds indicate Pennsylvanian deposition under relatively stable tectonic conditions. Three scales of sequences (avg. durations of ~140 ky, ~480 ky and 1.6 my) are recognized on the basis of stratigraphic stacking patterns and basinwide architecture of marine to terrestrial facies assemblages. The hierarchy of sequences and the geographic and stratigraphic positions of shifts in base-level sensitive facies across the Donets ramp permit the construction of an onlap-offlap history at a sub-400 ky scale. Major sea-level lowstands occur across the mid-Carboniferous boundary and during the early Moscovian. These lowstands coincide with glacial maxima inferred from high-latitude glacigenic deposits. The middle to late Pennsylvanian is characterized by a stepwise onlap, culminating in an earliest Gzhelian highstand, suggesting contraction of Carboniferous ice sheets prior to the initiation of Early Permian glaciation. The stratigraphic position of climate sensitive facies within individual Donets cyclothems indicates a turnover from seasonal sub-humid or semi-arid climate to everwet conditions during the late lowstand and maximum ice sheet accumulation. Comparison of the stratigraphic and aerial distribution of coals and evaporites in the Donets Basin with the onlap-offlap history further indicates everwet conditions during lowstands and inferred glacial maxima and drier climate during onlap and inferred ice sheet contraction at the intermediate (~0.8 to 1.6 my) and long (106 yr) time-scales. Taken together, the relationship between inferred climate and glacioeustasy suggests a likely teleconnection between high-latitude ice sheet behavior and low-latitude atmospheric dynamics

Proteomics in drug hypersensitivity

21 p.-4 fig.-1 tab.Drug hypersensitivity reactions result from the activation of the immune system by drugs or their metabolites. The clinical presentations of drug hypersensitivity can range from relatively mild local manifestations to severe systemic syndromes that can be life-threatening. As in other allergic reactions, the causes are multifactorial as genetic, metabolic and concomitant factors may influence the occurrence of drug hypersensitivity. Formation of drug protein adducts is considered a key step in drug adverse reactions, and in particular in the immunological recognition in drug hypersensitivity reactions. Nevertheless, non-covalent interactions of drugs with receptors in immune cells or with MHC clefts and/or exposed peptides can also play an important role. In recent years, development of proteomic approaches has allowed the identification and characterization of the protein targets for modification by drugs in vivo and in vitro, the nature of peptides exposed on MHC molecules, the changes in protein levels induced by drug treatment, and the concomitant modifications induced by danger signals, thus providing insight into context factors. Nevertheless, given the complexity and multifactorial nature of drug hypersensitivity reactions, understanding the underlying mechanisms also requires the integration of knowledge from genomic, metabolomic and clinical studies.This work has been supported by grants SAF2012-36519 and SAF2015-68590R from MINECO/FEDER and RETIC RD12/0013/0008 from ISCIII to D.P.-S., and by RETIC RD12/0013/0001 and CP15/00103 from ISCIII, and PI-0699-2011 and PI-0179-2014 from Junta de Andalucía to M.I.M.Peer reviewe

Bioactive phenolic compounds : production and extraction by solid-state fermentation. A review

Interest in the development of bioprocesses for the production or extraction of bioactive compounds from natural sources has increased in recent years due to the potential applications of these compounds in food, chemical, and pharmaceutical industries. In this context, solid-state fermentation (SSF) has received great attention because this bioprocess has potential to successfully convert inexpensive agro-industrial residues, as well as plants, in a great variety of valuable compounds, including bioactive phenolic compounds. The aim of this review, after presenting general aspects about bioactive compounds and SSF systems, is to focus on the production and extraction of bioactive phenolic compounds from natural sources by SSF. The characteristics of SSF systems and variables that affect the product formation by this process, as well as the variety of substrates and microorganisms that can be used in SSF for the production of bioactive phenolic compounds are reviewed and discussed.We acknowledge the financial support of Science and Technology Foundation of Portugal through grants SFRH/BD/40439/2007 and SFRH/BPD/38212/2007, and Mexican Council of Science and Technology through program SEP-CONACYT-24348/2007-2010

Informational life of the marginalized : a study of digital access in three Mexican towns

Spanish version available in IDRC Digital Library: Vida informacional de los marginados : un estudio sobre acceso digital en tres localidades MexicanasThe weight of family networks plays a crucial role in learning about ICTs. These networks fuel a sense of confidence required to handle knowledge and practices that are initially alien to sectors at the base of the pyramid. Results confirm that so-called “non-instrumental uses” promote “instrumental uses” involving new digital skills and human capital, when children with access to the internet can teach their parents how it can be used. The livelihoods framework focuses on understanding the role played by information and communication in poor communities. Training regarding the use of information geared to the needs of each context is important

Chronostratigraphy and paleoclimatology of the lodève Basin, France: Evidence for a pan-tropical aridification event across the carboniferous-permian boundary

© 2015 Elsevier B.V. Paleosols preserved within the Carboniferous-Permian succession of the Lodève Basin, Massif Central, France change stratigraphically from Histosols to calcic Vertisols and Calcisols to gypsic Vertisols and ultimately back to calcic Vertisols and Calcisols. New high-precision U-Pb zircon ages (CA-IDTIMS) for tuff beds within the Lodève and adjacent Graissessac basins significantly revise the chronostratigraphy of these and correlated Permian terrestrial basins of eastern Euramerica. Under the newly revised chronostratigraphy presented here these stratigraphic changes in morphology indicate a substantial drying of paleoenvironments across the Carboniferous-Permian boundary with a trend toward progressively more arid and seasonal climates through most of the early Permian. This newly-realized chronology provides a paleoenvironmental and paleoclimatic timeline for eastern tropical Pangea that is contemporaneous with similar records in western Pangea and suggests pan-tropical, progressive climate change toward aridity and seasonality occurred from the Late Carboniferous through early Permian

Reply to the comment on "Chronostratigraphy and paleoclimatology of the Lodève Basin, France: Evidence for a pan-tropical aridification event across the Carboniferous-Permian boundary" by Michel et al., (2015). Palaeogeography, Palaeoclimatology, Palaeoecology 430, 118-131

© 2015. Michel et al. (2015) present new radioisotopic age estimates coupled with paleosol data from the Lodève basin, France that indicate a Pennsylvanian-Permian trend toward aridity that is similar to trends seen in other western equatorial basins across tropical Pangaea. In their comment, Pochat and Van Den Driessche (2015) call into question these newly published U-Pb zircon chemical-abrasion isotope dilution thermal ionization mass spectrometry (CAIDTIMS) age estimates from volcanic ash layers preserved within the Lodève Basin. Furthermore, Pochat and Van Den Driessche (2015) reject our assertion that the rates of sediment accumulation for the Carboniferous-Permian strata in the Lodève basin are in need of recalculation as a result of the new geochronological dates. Finally, Pochat and Van Den Driessche (2015) suggest that the paleosol data presented in Michel et al. (2015) do not providemeaningful proxies of paleoclimate change, and reassert the position presented in Pochat and Van Den Driessche (2011) that sedimentary strata are not strongly affected by paleoclimatic change compared with the influence of tectonic processes of the Lodève basin

The influence of the carrier molecule on amoxicillin recognition by specific IgE in patients with immediate hypersensitivity reactions to betalactams

10 p.-4 fig.-1 tab.The optimal recognition of penicillin determinants, including amoxicillin (AX), by specific IgE antibodies is widely believed to require covalent binding to a carrier molecule. The nature of the carrier and its contribution to the antigenic determinant is not well known. Here we aimed to evaluate the specific-IgE recognition of different AX-derived structures. We studied patients with immediate hypersensitivity reactions to AX, classified as selective or cross-reactors to penicillins. Competitive immunoassays were performed using AX itself, amoxicilloic acid, AX bound to butylamine (AXO-BA) or to human serum albumin (AXO-HSA) in the fluid phase, as inhibitors, and amoxicilloyl-poli-L-lysine (AXO-PLL) in the solid-phase. Two distinct patterns of AX recognition by IgE were found: Group A showed a higher recognition of AX itself and AX-modified components of low molecular weights, whilst Group B showed similar recognition of both unconjugated and conjugated AX. Amoxicilloic acid was poorly recognized in both groups, which reinforces the need for AX conjugation to a carrier for optimal recognition. Remarkably, IgE recognition in Group A (selective responders to AX) is influenced by the mode of binding and/or the nature of the carrier; whereas IgE in Group B (cross-responders to penicillins) recognizes AX independently of the nature of the carrier.The present study has been supported by Institute of Health “Carlos III” of the Ministry of Economy and Competitiveness (grants cofunded by European Regional Development Fund (ERDF): PI12/02529, PI15/01206, CP15/00103,Red de Reacciones Adversas a Alergenos y Farmacos RD12/0013/0001, RD12/0013/0003 and RD12/0013/0008,RD09/0076/00112 for the Biobank network and PT13/0010/0006 for the Biobank platform) and by State Secretariat for Research, Development and Innovation of the Ministry of Economy and Competitiveness (grants cofunded by European Regional Development Fund (ERDF): MINECO SAF2012-36519, SAF2015-68590-R/FEDER and CTQ2013-41339-P). Andalusian Regional Ministry of Economy and Knowledge (grants cofunded by European Regional Development Fund (ERDF): CTS-06603); Andalusian Regional Ministry Health (grants:PI-0699-2011, PI-0159-2013 and PI-0179-2014) and Merck-Serono Research Grant from Fundación Salud 2000. CM holds a ‘Nicolas Monardes’ research contract by Andalusian Regional Ministry Health: C-0044-2012 SAS 2013. MIM holds a ‘Miguel Servet I’ research contract by Institute of Health “Carlos III” of the Ministry of Economy and Competitiveness (grants cofunded by European Social Fund (ESF)): CP15/00103. AA thanks “pFIS fellowship” (FI08/00385) from ISCIII and Andalucia “Talent Hub Fellowship” (TAHUB/II-004) cofunded by the Junta de Andalucia and the European Union, VII Framework Programme of the European Commission (grant agreement No. 291780).Peer reviewe