Showing papers by "University of Guelph published in 2013"
TL;DR: A persistent, species-level taxonomic registry for the animal kingdom is developed based on the analysis of patterns of nucleotide variation in the barcode region of the cytochrome c oxidase I (COI) gene.
Abstract: Because many animal species are undescribed, and because the identification of known species is often difficult, interim taxonomic nomenclature has often been used in biodiversity analysis. By assigning individuals to presumptive species, called operational taxonomic units (OTUs), these systems speed investigations into the patterning of biodiversity and enable studies that would otherwise be impossible. Although OTUs have conventionally been separated through their morphological divergence, DNA-based delineations are not only feasible, but have important advantages. OTU designation can be automated, data can be readily archived, and results can be easily compared among investigations. This study exploits these attributes to develop a persistent, species-level taxonomic registry for the animal kingdom based on the analysis of patterns of nucleotide variation in the barcode region of the cytochrome c oxidase I (COI) gene. It begins by examining the correspondence between groups of specimens identified to a species through prior taxonomic work and those inferred from the analysis of COI sequence variation using one new (RESL) and four established (ABGD, CROP, GMYC, jMOTU) algorithms. It subsequently describes the implementation, and structural attributes of the Barcode Index Number (BIN) system. Aside from a pragmatic role in biodiversity assessments, BINs will aid revisionary taxonomy by flagging possible cases of synonymy, and by collating geographical information, descriptive metadata, and images for specimens that are likely to belong to the same species, even if it is undescribed. More than 274,000 BIN web pages are now available, creating a biodiversity resource that is positioned for rapid growth.
1,571 citations
University of Florida1, University of Bonn2, Goddard Institute for Space Studies3, Commonwealth Scientific and Industrial Research Organisation4, Agro ParisTech5, Institut national de la recherche agronomique6, Michigan State University7, Blaise Pascal University8, International Water Management Institute9, University of Leeds10, CGIAR11, Counterintelligence Field Activity12, University of Tübingen13, University of Alberta14, International Atomic Energy Agency15, University of Reading16, University of Guelph17, University of Hohenheim18, Joint Global Change Research Institute19, Potsdam Institute for Climate Impact Research20, Indian Agricultural Research Institute21, Aarhus University22, Rothamsted Research23, Washington State University24, Wageningen University and Research Centre25, Chinese Academy of Sciences26, International Trademark Association27, Texas A&M University28
TL;DR: In this article, the authors present the largest standardized model intercomparison for climate change impacts so far, finding that individual crop models are able to simulate measured wheat grain yields accurately under a range of environments, particularly if the input information is sufficient.
Abstract: Projections of climate change impacts on crop yields are inherently uncertain(1). Uncertainty is often quantified when projecting future greenhouse gas emissions and their influence on climate(2). However, multi-model uncertainty analysis of crop responses to climate change is rare because systematic and objective comparisons among process-based crop simulation models(1,3) are difficult(4). Here we present the largest standardized model intercomparison for climate change impacts so far. We found that individual crop models are able to simulate measured wheat grain yields accurately under a range of environments, particularly if the input information is sufficient. However, simulated climate change impacts vary across models owing to differences in model structures and parameter values. A greater proportion of the uncertainty in climate change impact projections was due to variations among crop models than to variations among downscaled general circulation models. Uncertainties in simulated impacts increased with CO2 concentrations and associated warming. These impact uncertainties can be reduced by improving temperature and CO2 relationships in models and better quantified through use of multi-model ensembles. Less uncertainty in describing how climate change may affect agricultural productivity will aid adaptation strategy development and policymaking.
1,049 citations
TL;DR: It is found that large concentrations of microplastic and additives can harm ecophysiological functions performed by organisms, and this work indicates that global microplastics contamination accelerates.
881 citations
TL;DR: A broad review on the recent advances in the research and development of biobased plastics and bionanocomposites that are used in various applications such as packaging, durable goods, electronics and biomedical uses is presented in this paper.
863 citations
TL;DR: Research on the actions of the endocannabinoid system on anxiety, depression, neurogenesis, reward, cognition, learning, and memory, and the effects are at times biphasic--lower doses causing effects opposite to those seen at high doses.
Abstract: The psychoactive constituent in cannabis, Δ9-tetrahydrocannabinol (THC), was isolated in the mid-1960s, but the cannabinoid receptors, CB1 and CB2, and the major endogenous cannabinoids (anandamide and 2-arachidonoyl glycerol) were identified only 20 to 25 years later. The cannabinoid system affects both central nervous system (CNS) and peripheral processes. In this review, we have tried to summarize research—with an emphasis on recent publications—on the actions of the endocannabinoid system on anxiety, depression, neurogenesis, reward, cognition, learning, and memory. The effects are at times biphasic—lower doses causing effects opposite to those seen at high doses. Recently, numerous endocannabinoid-like compounds have been identified in the brain. Only a few have been investigated for their CNS activity, and future investigations on their action may throw light on a wide spectrum of brain functions.
826 citations
TL;DR: This proof-of-principle study demonstrates that a stool substitute mixture comprising a multi-species community of bacteria is capable of curing antibiotic-resistant C. difficile colitis.
Abstract: Fecal bacteriotherapy (‘stool transplant’) can be effective in treating recurrent Clostridium difficile infection, but concerns of donor infection transmission and patient acceptance limit its use. Here we describe the use of a stool substitute preparation, made from purified intestinal bacterial cultures derived from a single healthy donor, to treat recurrent C. difficile infection that had failed repeated standard antibiotics. Thirty-three isolates were recovered from a healthy donor stool sample. Two patients who had failed at least three courses of metronidazole or vancomycin underwent colonoscopy and the mixture was infused throughout the right and mid colon. Pre-treatment and post-treatment stool samples were analyzed by 16 S rRNA gene sequencing using the Ion Torrent platform. Both patients were infected with the hyper virulent C. difficile strain, ribotype 078. Following stool substitute treatment, each patient reverted to their normal bowel pattern within 2 to 3 days and remained symptom-free at 6 months. The analysis demonstrated that rRNA sequences found in the stool substitute were rare in the pre-treatment stool samples but constituted over 25% of the sequences up to 6 months after treatment. This proof-of-principle study demonstrates that a stool substitute mixture comprising a multi-species community of bacteria is capable of curing antibiotic-resistant C. difficile colitis. This benefit correlates with major changes in stool microbial profile and these changes reflect isolates from the synthetic mixture. Clinical trial registration number: CinicalTrials.gov NCT01372943
677 citations
TL;DR: The importance of founding new SWM approaches for developing country contexts in post-normal science and complex, adaptive systems thinking is demonstrated.
640 citations
TL;DR: The rapid evolution and spread of "new" antibiotic resistance genes has been enhanced by modern human activity and its influence on the environmental resistome, which highlights the importance of including the role of the environmental vectors, such as bacterial genetic diversity within soil and water, in resistance risk management.
Abstract: Antibiotic resistance and associated genes are ubiquitous and ancient, with most genes that encode resistance in human pathogens having originated in bacteria from the natural environment (eg, β-lactamases and fluoroquinolones resistance genes, such as qnr). The rapid evolution and spread of "new" antibiotic resistance genes has been enhanced by modern human activity and its influence on the environmental resistome. This highlights the importance of including the role of the environmental vectors, such as bacterial genetic diversity within soil and water, in resistance risk management. We need to take more steps to decrease the spread of resistance genes in environmental bacteria into human pathogens, to decrease the spread of resistant bacteria to people and animals via foodstuffs, wastes and water, and to minimize the levels of antibiotics and antibiotic-resistant bacteria introduced into the environment. Reducing this risk must include improved management of waste containing antibiotic residues and antibiotic-resistant microorganisms.
504 citations
TL;DR: The drivers of endophyte community structure relating to plant growth promotion, the mechanisms of plant growth Promotion, and the current and future use of molecular techniques to study these communities are reviewed.
Abstract: Bacterial root endophytes reside in a vast number of plant species as part of their root microbiome, with some being shown to positively influence plant growth. Endophyte community structure (species diversity: richness and relative abundances) within the plant is dynamic and is influenced by abiotic and biotic factors such as soil conditions, biogeography, plant species, microbe-microbe interactions and plant-microbe interactions, both at local and larger scales. Plant-growth-promoting bacterial endophytes (PGPBEs) have been identified, but the predictive success at positively influencing plant growth in field conditions has been limited. Concurrent to the development of modern molecular techniques, the goal of predicting an organism's ability to promote plant growth can perhaps be realized by more thorough examination of endophyte community dynamics. This paper reviews the drivers of endophyte community structure relating to plant growth promotion, the mechanisms of plant growth promotion, and the current and future use of molecular techniques to study these communities.
488 citations
01 Jan 2013
TL;DR: This chapter presents an introduction to recurrent neural networks for readers familiar with artificial neural networks in general, and multi-layer perceptrons trained with gradient descent algorithms (back-propagation) in particular.
Abstract: This chapter presents an introduction to recurrent neural networks for readers familiar with artificial neural networks in general, and multi-layer perceptrons trained with gradient descent algorithms (back-propagation) in particular. A recurrent neural network (RNN) is an artificial neural network with internal loops. These internal loops induce recursive dynamics in the networks and thus introduce delayed activation dependencies across the processing elements (PEs) in the network.
468 citations
TL;DR: It is proposed that a life history classification system based on the grouping of functional traits, such as Grime's C-S-R (competitor, stress tolerator, ruderal) framework, can help to explain life history diversification in AM fungi, successional dynamics, and the spatial structure of AM fungal assemblages.
TL;DR: Most of the herbal products tested were of poor quality, including considerable product substitution, contamination and use of fillers, which suggests that the herbal industry should embrace DNA barcoding for authenticating herbal products through testing of raw materials used in manufacturing products.
Abstract: Background: Herbal products available to consumers in the marketplace may be contaminated or substituted with alternative plant species and fillers that are not listed on the labels According to the World Health Organization, the adulteration of herbal products is a threat to consumer safety Our research aimed to investigate herbal product integrity and authenticity with the goal of protecting consumers from health risks associated with product substitution and contamination Methods: We used DNA barcoding to conduct a blind test of the authenticity for (i) 44 herbal products representing 12 companies and 30 different species of herbs, and (ii) 50 leaf samples collected from 42 herbal species Our laboratory also assembled the first standard reference material (SRM) herbal barcode library from 100 herbal species of known provenance that were used to identify the unknown herbal products and leaf samples Results: We recovered DNA barcodes from most herbal products (91%) and all leaf samples (100%), with 95% species resolution using a tiered approach (rbcL + ITS2) Most (59%) of the products tested contained DNA barcodes from plant species not listed on the labels Although we were able to authenticate almost half (48%) of the products, one-third of these also contained contaminants and or fillers not listed on the label Product substitution occurred in 30/44 of the products tested and only 2/12 companies had products without any substitution, contamination or fillers Some of the contaminants we found pose serious health risks to consumers Conclusions: Most of the herbal products tested were of poor quality, including considerable product substitution, contamination and use of fillers These activities dilute the effectiveness of otherwise useful remedies, lowering the perceived value of all related products because of a lack of consumer confidence in them We suggest that the herbal industry should embrace DNA barcoding for authenticating herbal products through testing of raw materials used in manufacturing products The use of an SRM DNA herbal barcode library for testing bulk materials could provide a method for ‘best practices’ in the manufacturing of herbal products This would provide consumers with safe, high quality herbal products Background Globalization of trade is expanding natural product commodity markets that sustain life and promote good health, yet the challenging financial climate is squeezing profit margins and exacerbating the propensity for contamination, fraudulent market substitution and the use of unlabeled fillers This comes at a time when consumers are becoming increasingly concerned about the authenticity of the products they purchase North America is a major provider of goods such as herbal products, a commodity that has come under scrutiny recently in the media due to product substitution [1-3] The International Trade in herbal products is a major force in the global economy and the demand is increasing in both developing and developed nations There are currently more than 1,000 companies producing medicinal plant products with annual revenues in excess of US$60 billion Notably, medicinal herbs now constitute the most rapidly growing segment of the North American alternative medicine market [4,5], with over 29,000 herbal substances [6,7] generating billions of dollars in trade These statistics are indicative of the rapid growth
TL;DR: This work draws together research from several disciplines to understand the relationship between animal memory and movement processes, and frames the problem in terms of the characteristics, costs and benefits of memory as outlined in psychology and neuroscience.
Abstract: Memory is critical to understanding animal movement but has proven challenging to study. Advances in animal tracking technology, theoretical movement models and cognitive sciences have facilitated research in each of these fields, but also created a need for synthetic examination of the linkages between memory and animal movement. Here, we draw together research from several disciplines to understand the relationship between animal memory and movement processes. First, we frame the problem in terms of the characteristics, costs and benefits of memory as outlined in psychology and neuroscience. Next, we provide an overview of the theories and conceptual frameworks that have emerged from behavioural ecology and animal cognition. Third, we turn to movement ecology and summarise recent, rapid developments in the types and quantities of available movement data, and in the statistical measures applicable to such data. Fourth, we discuss the advantages and interrelationships of diverse modelling approaches that have been used to explore the memory–movement interface. Finally, we outline key research challenges for the memory and movement communities, focusing on data needs and mathematical and computational challenges. We conclude with a roadmap for future work in this area, outlining axes along which focused research should yield rapid progress.
TL;DR: It is demonstrated that cardiac Glp1r expression is localized to cardiac atria and that GLP-1R activation promotes the secretion of atrial natriuretic peptide (ANP) and a reduction of blood pressure, defining a gut-heart GLP–1R–dependent and ANP–dependent axis that regulates blood pressure.
Abstract: The peptide hormone GLP-1 has both antidiabetic and antihypertensive effects. Daniel Drucker and his colleagues now show that GLP-1 lowers blood pressure through indirect mechanisms involving the heart: GLP-1 acts on its receptor in atrial cardiomyocytes to stimulate secretion of the peptide hormone ANP, which in turn lowers blood pressure through direct effects on the vasculature and kidney. Glucagon-like peptide-1 receptor (GLP-1R) agonists exert antihypertensive actions through incompletely understood mechanisms. Here we demonstrate that cardiac Glp1r expression is localized to cardiac atria and that GLP-1R activation promotes the secretion of atrial natriuretic peptide (ANP) and a reduction of blood pressure. Consistent with an indirect ANP-dependent mechanism for the antihypertensive effects of GLP-1R activation, the GLP-1R agonist liraglutide did not directly increase the amount of cyclic GMP (cGMP) or relax preconstricted aortic rings; however, conditioned medium from liraglutide-treated hearts relaxed aortic rings in an endothelium-independent, GLP-1R–dependent manner. Liraglutide did not induce ANP secretion, vasorelaxation or lower blood pressure in Glp1r−/− or Nppa−/− mice. Cardiomyocyte GLP-1R activation promoted the translocation of the Rap guanine nucleotide exchange factor Epac2 (also known as Rapgef4) to the membrane, whereas Epac2 deficiency eliminated GLP-1R–dependent stimulation of ANP secretion. Plasma ANP concentrations were increased after refeeding in wild-type but not Glp1r−/− mice, and liraglutide increased urine sodium excretion in wild-type but not Nppa−/− mice. These findings define a gut-heart GLP-1R–dependent and ANP–dependent axis that regulates blood pressure.
Laurentian University1, Queen's University2, University of Texas at Austin3, University of Pennsylvania4, Carleton University5, University of Alberta6, Lawrence Berkeley National Laboratory7, University of Guelph8, University of Oxford9, University of Washington10, Los Alamos National Laboratory11, Massachusetts Institute of Technology12, Louisiana State University13, Brookhaven National Laboratory14, University of British Columbia15, TRIUMF16
TL;DR: In this paper, a combined analysis of solar neutrino data from all phases of the Sudbury Neutrino Observatory was presented, which showed that particle identification information obtained from the proportional counters installed during the third phase improved background rejection in that phase of the experiment.
Abstract: We report results from a combined analysis of solar neutrino data from all phases of the Sudbury Neutrino Observatory. By exploiting particle identification information obtained from the proportional counters installed during the third phase, this analysis improved background rejection in that phase of the experiment. The combined analysis resulted in a total flux of active neutrino flavors from 8B decays in the Sun of (5.25 \pm 0.16(stat.)+0.11-0.13(syst.))\times10^6 cm^{-2}s^{-1}. A two-flavor neutrino oscillation analysis yielded \Deltam^2_{21} = (5.6^{+1.9}_{-1.4})\times10^{-5} eV^2 and tan^2{\theta}_{12}= 0.427^{+0.033}_{-0.029}. A three-flavor neutrino oscillation analysis combining this result with results of all other solar neutrino experiments and the KamLAND experiment yielded \Deltam^2_{21} = (7.41^{+0.21}_{-0.19})\times10^{-5} eV^2, tan^2{\theta}_{12} = 0.446^{+0.030}_{-0.029}, and sin^2{\theta}_{13} =(2.5^{+1.8}_{-1.5})\times10^{-2}. This implied an upper bound of sin^2{\theta}_{13} < 0.053 at the 95% confidence level (C.L.).
TL;DR: It is shown that exposing mothers to high-density cues, accomplished via playbacks of territorial vocalizations, led to increased offspring growth rates in the absence of additional food resources, and females with naturally or experimentally increased glucocorticoids produced offspring that grew faster than controls.
Abstract: In fluctuating environments, mothers may enhance the fitness of their offspring by adjusting offspring phenotypes to match the environment they will experience at independence. In free-ranging red squirrels, natural selection on offspring postnatal growth rates varies according to population density, with selection favoring faster-growing offspring under high-density conditions. We show that exposing mothers to high-density cues, accomplished via playbacks of territorial vocalizations, led to increased offspring growth rates in the absence of additional food resources. Experimental elevation of actual and perceived density induced higher maternal glucocorticoid levels, and females with naturally or experimentally increased glucocorticoids produced offspring that grew faster than controls. Therefore, social cues reflecting population density were sufficient to elicit increased offspring growth through an adaptive hormone-mediated maternal effect.
TL;DR: In this article, the authors focus on controlling MICP treatment of one-dimensional flow, half-meter-scale column experiments, and optimize the treatment by varying procedural parameters in five pairs of experiments including flow rates, flow direction, and formulations of biological and chemical amendments.
Abstract: Implementation of laboratory-tested biomediated soil improvement techniques in the field depends on upscaling the primary processes and controlling their rates. Microbial-induced carbonate precipitation (MICP) holds the potential for increasing the shear stiffness and reducing the hydraulic conductivity by harnessing a natural microbiological process that precipitates calcium carbonate. The study presented herein focuses on controlling MICP treatment of one-dimensional flow, half-meter-scale column experiments. Treatment was optimized by varying procedural parameters in five pairs of experiments including flow rates, flow direction, and formulations of biological and chemical amendments. Monitoring of column experiments included spatial and temporal measurements of the physical, chemical, and biological properties essential to the performance of MICP, including shear wave velocity, permeability, calcium carbonate content, aqueous calcium, aqueous ammonium, aqueous urea, and bacterial density. Rela...
TL;DR: The TIV and LAIV vaccines can provide cross protection against non-matching circulating strains, and the point estimates for VE were different for matching versus non- matching strains, with overlapping CIs.
Abstract: Influenza vaccines are most effective when the antigens in the vaccine match those of circulating strains. However, antigens contained in the vaccines do not always match circulating strains. In the present work we aimed to examine the vaccine efficacy (VE) afforded by influenza vaccines when they are not well matched to circulating strains. We identified randomized clinical trials (RCTs) through MEDLINE, EMBASE, the Cochrane Library, and references of included RCTs. RCTs reporting laboratory-confirmed influenza among healthy participants vaccinated with antigens of matching and non-matching influenza strains were included. Two independent reviewers screened citations/full-text articles, abstracted data, and appraised risk of bias. Conflicts were resolved by discussion. A random effects meta-analysis was conducted. VE was calculated using the following formula: (1 - relative risk × 100%). We included 34 RCTs, providing data on 47 influenza seasons and 94,821 participants. The live-attenuated influenza vaccine (LAIV) showed significant protection against mismatched (six RCTs, VE 54%, 95% confidence interval (CI) 28% to 71%) and matched (seven RCTs, VE 83%, 95% CI 75% to 88%) influenza strains among children aged 6 to 36 months. Differences were observed between the point estimates for mismatched influenza A (five RCTs, VE 75%, 95% CI 41% to 90%) and mismatched influenza B (five RCTs, VE 42%, 95% CI 22% to 56%) estimates among children aged 6 to 36 months. The trivalent inactivated vaccine (TIV) also afforded significant protection against mismatched (nine RCTs, VE 52%, 95% CI 37% to 63%) and matched (eight RCTs, VE 65%, 95% CI 54% to 73%) influenza strains among adults. Numerical differences were observed between the point estimates for mismatched influenza A (five RCTs, VE 64%, 95% CI 23% to 82%) and mismatched influenza B (eight RCTs, VE 52%, 95% CI 19% to 72%) estimates among adults. Statistical heterogeneity was low (I2 <50%) across all meta-analyses, except for the LAIV meta-analyses among children (I2 = 79%). The TIV and LAIV vaccines can provide cross protection against non-matching circulating strains. The point estimates for VE were different for matching versus non-matching strains, with overlapping CIs.
Ames Research Center1, University of Texas at Austin2, University of Arizona3, Indiana University4, United States Geological Survey5, Max Planck Society6, University of Copenhagen7, Cornell University8, University of Guelph9, Lunar and Planetary Institute10, State University of New York System11, California Institute of Technology12, Planetary Science Institute13, Chesapeake Energy14, University of California, Davis15, Centre national de la recherche scientifique16, Oregon State University17, Finnish Meteorological Institute18, Goddard Space Flight Center19, Rensselaer Polytechnic Institute20, Carnegie Institution for Science21, University of Tennessee22, Johns Hopkins University Applied Physics Laboratory23, Princeton University24, Arizona State University25, Search for extraterrestrial intelligence26
TL;DR: The Rocknest aeolian deposit is similar to aeOLian features analyzed by the Mars Exploration Rovers Spirit and Opportunity and implies locally sourced, globally similar basaltic materials or globally and regionally sourced basALTic components deposited locally at all three locations.
Abstract: The Rocknest aeolian deposit is similar to aeolian features analyzed by the Mars Exploration Rovers (MERs) Spirit and Opportunity. The fraction of sand <150 micrometers in size contains ~55% crystalline material consistent with a basaltic heritage and ~45% x-ray amorphous material. The amorphous component of Rocknest is iron-rich and silicon-poor and is the host of the volatiles (water, oxygen, sulfur dioxide, carbon dioxide, and chlorine) detected by the Sample Analysis at Mars instrument and of the fine-grained nanophase oxide component first described from basaltic soils analyzed by MERs. The similarity between soils and aeolian materials analyzed at Gusev Crater, Meridiani Planum, and Gale Crater implies locally sourced, globally similar basaltic materials or globally and regionally sourced basaltic components deposited locally at all three locations.
TL;DR: The current paradigms regarding the influence of AMPK in regulating skeletal muscle fatty acid metabolism and mitochondrial biogenesis at rest and during exercise are discussed, and the potential implications in the development of insulin resistance are highlighted.
TL;DR: These findings highlight previously overlooked, anatomically significant effects of metal nanoparticles, and recommend considering detailed anatomical investigations in tandem with the standard developmental phytotoxicity assays (germination and root elongation) as the latter ones appear less sensitive for screening plant responses to nanomaterial insults.
TL;DR: Future changes to terrestrial high-latitude CH4 emissions will be more proximately related to changes in moisture, soil temperature, and vegetation composition than to increased availability of organic matter following permafrost thaw.
Abstract: Methane (CH4) emissions from the northern high-latitude region represent potentially significant biogeochemical feedbacks to the climate system. We compiled a database of growing-season CH4 emissions from terrestrial ecosystems located across permafrost zones, including 303 sites described in 65 studies. Data on environmental and physical variables, including permafrost conditions, were used to assess controls on CH4 emissions. Water table position, soil temperature, and vegetation composition strongly influenced emissions and had interacting effects. Sites with a dense sedge cover had higher emissions than other sites at comparable water table positions, and this was an effect that was more pronounced at low soil temperatures. Sensitivity analysis suggested that CH4 emissions from ecosystems where the water table on average is at or above the soil surface (wet tundra, fen underlain by permafrost, and littoral ecosystems) are more sensitive to variability in soil temperature than drier ecosystems (palsa dry tundra, bog, and fen), whereas the latter ecosystems conversely are relatively more sensitive to changes of the water table position. Sites with near-surface permafrost had lower CH4 fluxes than sites without permafrost at comparable water table positions, a difference that was explained by lower soil temperatures. Neither the active layer depth nor the organic soil layer depth was related to CH4 emissions. Permafrost thaw in lowland regions is often associated with increased soil moisture, higher soil temperatures, and increased sedge cover. In our database, lowland thermokarst sites generally had higher emissions than adjacent sites with intact permafrost, but emissions from thermokarst sites were not statistically higher than emissions from permafrost-free sites with comparable environmental conditions. Overall, these results suggest that future changes to terrestrial high-latitude CH4 emissions will be more proximately related to changes in moisture, soil temperature, and vegetation composition than to increased availability of organic matter following permafrost thaw.
TL;DR: In this paper, a review of the existing approaches to analyze data obtained from a check-all-that-apply (CATA) questionnaires is presented, which includes a generalization of Cochran's Q to test for product differences across all attributes, and a more informative penalty analysis.
TL;DR: The catalytic defunctionalization of a series of biomass-derived molecules to provide linear alkanes suitable for use as transportation fuels and is applicable to a range of precursors with different carbon content (chain length).
Abstract: The development of methodology to convert biomass into fuels and chemical feedstocks is part of a drive to reduce the world's dependence on crude oil. Here, the catalytic defunctionalization of a series of biomass-derived molecules is described, which allows the selective generation of alkanes with carbon chain lengths between eight and sixteen for use as transportation fuels.
University of Florida1, University of Alaska Fairbanks2, University of Vermont3, Max Planck Society4, Bowdoin College5, CSIRO Marine and Atmospheric Research6, Florida State University7, Lund University8, Centre national de la recherche scientifique9, Idaho State University10, University of California11, United States Geological Survey12, Oak Ridge National Laboratory13, Stockholm University14, Argonne National Laboratory15, Lawrence Berkeley National Laboratory16, National Center for Atmospheric Research17, National Park Service18, Cooperative Institute for Research in Environmental Sciences19, University of Oxford20, University of Guelph21, Los Alamos National Laboratory22
TL;DR: In this article, the authors used a survey to quantify variability in the perception of the vulnerability of permafrost C to climate change and found that approximately 1700 Pg of soil carbon (C) are stored in the northern circumpolar permafure zone, more than twice as much C than in the atmosphere.
Abstract: Approximately 1700 Pg of soil carbon (C) are stored in the northern circumpolar permafrost zone, more than twice as much C than in the atmosphere. The overall amount, rate, and form of C released to the atmosphere in a warmer world will influence the strength of the permafrost C feedback to climate change. We used a survey to quantify variability in the perception of the vulnerability of permafrost C to climate change. Experts were asked to provide quantitative estimates of permafrost change in response to four scenarios of warming. For the highest warming scenario (RCP 8.5), experts hypothesized that C release from permafrost zone soils could be 19–45 Pg C by 2040, 162–288 Pg C by 2100, and 381–616 Pg C by 2300 in CO2 equivalent using 100-year CH4 global warming potential (GWP). These values become 50 % larger using 20-year CH4 GWP, with a third to a half of expected climate forcing coming from CH4 even though CH4 was only 2.3 % of the expected C release. Experts projected that two-thirds of this release could be avoided under the lowest warming scenario (RCP 2.6). These results highlight the potential risk from permafrost thaw and serve to frame a hypothesis about the magnitude of this feedback to climate change. However, the level of emissions proposed here are unlikely to overshadow the impact of fossil fuel burning, which will continue to be the main source of C emissions and climate forcing.
TL;DR: A polymicrobial signature of Gram-negative anaerobic bacteria is associated with colorectal carcinoma tissue, associated with over-expression of numerous host genes, including the gene encoding the pro-inflammatory chemokine Interleukin-8.
Abstract: Numerous cancers have been linked to microorganisms. Given that colorectal cancer is a leading cause of cancer deaths and the colon is continuously exposed to a high diversity of microbes, the relationship between gut mucosal microbiome and colorectal cancer needs to be explored. Metagenomic studies have shown an association between Fusobacterium species and colorectal carcinoma. Here, we have extended these studies with deeper sequencing of a much larger number (n = 130) of colorectal carcinoma and matched normal control tissues. We analyzed these data using co-occurrence networks in order to identify microbe-microbe and host-microbe associations specific to tumors. We confirmed tumor over-representation of Fusobacterium species and observed significant co-occurrence within individual tumors of Fusobacterium, Leptotrichia and Campylobacter species. This polymicrobial signature was associated with over-expression of numerous host genes, including the gene encoding the pro-inflammatory chemokine Interleukin-8. The tumor-associated bacteria we have identified are all Gram-negative anaerobes, recognized previously as constituents of the oral microbiome, which are capable of causing infection. We isolated a novel strain of Campylobacter showae from a colorectal tumor specimen. This strain is substantially diverged from a previously sequenced oral Campylobacter showae isolate, carries potential virulence genes, and aggregates with a previously isolated tumor strain of Fusobacterium nucleatum. A polymicrobial signature of Gram-negative anaerobic bacteria is associated with colorectal carcinoma tissue.
TL;DR: The present review tries to bring out the recent trend of research on electrospun CA fibers of nanoscale regime in the context of developmental strategies of their blends and nanocomposites for advanced applications.
TL;DR: In this article, a comparative study of two wetland communities in Trinidad and Tobago, a country that is expected to bear some of the most severe impacts of climate change, was conducted.
TL;DR: This research shows how biodiversity can be crucial for ecosystem stability despite appearing functionally insignificant beforehand, a relationship probably applicable to many ecosystems given the globally prevalent combination of intensive long-term land management and species loss.
Abstract: Long-term and persistent human disturbances have simultaneously altered the stability and diversity of ecological systems, with disturbances directly reducing functional attributes such as invasion resistance, while eliminating the buffering effects of high species diversity. Theory predicts that this combination of environmental change and diversity loss increases the risk of abrupt and potentially irreversible ecosystem collapse, but long-term empirical evidence from natural systems is lacking. Here we demonstrate this relationship in a degraded but species-rich pyrogenic grassland in which the combined effects of fire suppression, invasion and trophic collapse have created a species-poor grassland that is highly productive, resilient to yearly climatic fluctuations, and resistant to invasion, but vulnerable to rapid collapse after the re-introduction of fire. We initially show how human disturbance has created a negative relationship between diversity and function, contrary to theoretical predictions. Fire prevention since the mid-nineteenth century is associated with the loss of plant species but it has stabilized high-yield annual production and invasion resistance, comparable to a managed high-yield low-diversity agricultural system. In managing for fire suppression, however, a hidden vulnerability to sudden environmental change emerges that is explained by the elimination of the buffering effects of high species diversity. With the re-introduction of fire, grasslands only persist in areas with remnant concentrations of native species, in which a range of rare and mostly functionally redundant plants proliferate after burning and prevent extensive invasion including a rapid conversion towards woodland. This research shows how biodiversity can be crucial for ecosystem stability despite appearing functionally insignificant beforehand, a relationship probably applicable to many ecosystems given the globally prevalent combination of intensive long-term land management and species loss.
TL;DR: This paper covers measures of field colony strength, by which the authors mean population measures of adult bees and brood, and parameters that do not directly measure colony strength yet give important indicators of colony state: flight activity at the hive entrance; comb construction; and two proxy measures of colony fitness.
Abstract: This paper covers measures of field colony strength, by which we mean population measures of adult bees and brood. There are generally two contexts in which an investigator wishes to measure colony strength: 1. at the beginning of a study as part of manipulations to produce uniform colonies and reduce experimental error and; 2. as response variables during or at the end of an experiment. Moreover, there are two general modes for measuring colony strength: 1. an objective mode which uses empirical measures and; 2. a subjective mode that relies on visual estimates by one or more observers. There is a third emerging mode for measuring colony strength; 3. computer-assisted digital image analysis. A final section deals with parameters that do not directly measure colony strength yet give important indicators of colony state: flight activity at the entrance; comb construction; and two proxy measures of colony fitness: production of queen cells and drone brood. How to conduct different types of experiments are described, including infectious dose, dose effects, course of infection and longevity tests.