Showing papers by "University of Guelph published in 2014"
Chalmers University of Technology1, Institut national de la recherche agronomique2, Agrocampus Ouest3, Aix-Marseille University4, University of Guelph5, Massey University6, Ege University7, Agro ParisTech8, Norwich Research Park9, Norwich University10, University of Massachusetts Amherst11, Spanish National Research Council12, Universidade Nova de Lisboa13, University of California, Davis14, Norwegian University of Life Sciences15, University of Greifswald16, Teagasc17
TL;DR: In this article, the authors proposed a general standardised and practical static digestion method based on physiologically relevant conditions that can be applied for various endpoints, which may be amended to accommodate further specific requirements.
Abstract: Simulated gastro-intestinal digestion is widely employed in many fields of food and nutritional sciences, as conducting human trials are often costly, resource intensive, and ethically disputable. As a consequence, in vitro alternatives that determine endpoints such as the bioaccessibility of nutrients and non-nutrients or the digestibility of macronutrients (e.g. lipids, proteins and carbohydrates) are used for screening and building new hypotheses. Various digestion models have been proposed, often impeding the possibility to compare results across research teams. For example, a large variety of enzymes from different sources such as of porcine, rabbit or human origin have been used, differing in their activity and characterization. Differences in pH, mineral type, ionic strength and digestion time, which alter enzyme activity and other phenomena, may also considerably alter results. Other parameters such as the presence of phospholipids, individual enzymes such as gastric lipase and digestive emulsifiers vs. their mixtures (e.g. pancreatin and bile salts), and the ratio of food bolus to digestive fluids, have also been discussed at length. In the present consensus paper, within the COST Infogest network, we propose a general standardised and practical static digestion method based on physiologically relevant conditions that can be applied for various endpoints, which may be amended to accommodate further specific requirements. A frameset of parameters including the oral, gastric and small intestinal digestion are outlined and their relevance discussed in relation to available in vivo data and enzymes. This consensus paper will give a detailed protocol and a line-by-line, guidance, recommendations and justifications but also limitation of the proposed model. This harmonised static, in vitro digestion method for food should aid the production of more comparable data in the future.
3,380 citations
University of British Columbia1, Canadian Institute for Advanced Research2, Monterey Bay Aquarium Research Institute3, Stony Brook University4, University of California, San Diego5, Marine Biological Laboratory6, Brown University7, University of Washington8, Dalhousie University9, National Center for Genome Resources10, Alfred Wegener Institute for Polar and Marine Research11, Rutgers University12, Texas A&M University13, University of Southern California14, University of Delaware15, Victoria University of Wellington16, University of Paris-Sud17, Columbia University18, University of Oslo19, University of Hawaii at Manoa20, University of Prince Edward Island21, University of Rhode Island22, Woods Hole Oceanographic Institution23, Jacobs University Bremen24, Max Planck Society25, Smith College26, University of South Alabama27, University of Geneva28, Saint Petersburg State University29, University of Connecticut30, Laval University31, University of Guelph32, University of North Carolina at Chapel Hill33, University of New Brunswick34, University of Camerino35, University of East Anglia36, Stazione Zoologica Anton Dohrn37, University of Georgia38, University of Technology, Sydney39, University of Puerto Rico40, University of Pisa41, Centre national de la recherche scientifique42, Colorado School of Mines43, Lund University44, University of Western Ontario45, California State University46, University of Texas at Austin47, Los Alamos National Laboratory48, Pierre-and-Marie-Curie University49, University of Oklahoma50, Plymouth Marine Laboratory51, Bigelow Laboratory For Ocean Sciences52, Princeton University53
TL;DR: In this paper, the authors describe a resource of 700 transcriptomes from marine microbial eukaryotes to help understand their role in the world's oceans and their biology, evolution, and ecology.
Abstract: Current sampling of genomic sequence data from eukaryotes is relatively poor, biased, and inadequate to address important questions about their biology, evolution, and ecology; this Community Page describes a resource of 700 transcriptomes from marine microbial eukaryotes to help understand their role in the world's oceans.
852 citations
TL;DR: Rhodopsins found in Eukaryotes, Bacteria, and Archaea consist of opsin apoproteins and a covalently linked retinal which is employed to absorb photons for energy conversion or the initiation of intra- or intercellular signaling.
Abstract: Organisms of all domains of life use photoreceptor proteins to sense and respond to light. The light-sensitivity of photoreceptor proteins arises from bound chromophores such as retinal in retinylidene proteins, bilin in biliproteins, and flavin in flavoproteins. Rhodopsins found in Eukaryotes, Bacteria, and Archaea consist of opsin apoproteins and a covalently linked retinal which is employed to absorb photons for energy conversion or the initiation of intra- or intercellular signaling.1 Both functions are important for organisms to survive and to adapt to the environment. While lower organisms utilize the family of microbial rhodopsins for both purposes, animals solely use a different family of rhodopsins, a specialized subset of G-protein-coupled receptors (GPCRs).1,2 Animal rhodopsins, for example, are employed in visual and nonvisual phototransduction, in the maintenance of the circadian clock and as photoisomerases.3,4 While sharing practically no sequence similarity, microbial and animal rhodopsins, also termed type-I and type-II rhodopsins, respectively, share a common architecture of seven transmembrane α-helices (TM) with the N- and C-terminus facing out- and inside of the cell, respectively (Figure (Figure11).1,5 Retinal is attached by a Schiff base linkage to the e-amino group of a lysine side chain in the middle of TM7 (Figures (Figures11 and and2).2). The retinal Schiff base (RSB) is protonated (RSBH+) in most cases, and changes in protonation state are integral to the signaling or transport activity of rhodopsins.
Figure 1
Topology of the retinal proteins. (A) These membrane proteins contain seven α-helices (typically denoted helix A to G in microbial opsins and TM1 to 7 in the animal opsins) spanning the lipid bilayer. The N-terminus faces the outside of the cell ...
811 citations
California Institute of Technology1, University of California, Davis2, University of Tennessee3, Imperial College London4, Arizona State University5, United States Geological Survey6, Princeton University7, Indiana University8, University of Nantes9, Brown University10, Goddard Space Flight Center11, Ames Research Center12, State University of New York System13, Jacobs Engineering Group14, Planetary Science Institute15, University of Guelph16, Los Alamos National Laboratory17, University of Toulouse18, Smithsonian Institution19, Washington University in St. Louis20, University of Washington21, University of California, Berkeley22, University of Lyon23, University of Texas at Austin24, Rensselaer Polytechnic Institute25, Canadian Space Agency26, NASA Headquarters27, University of New Mexico28, University of Hawaii at Manoa29, Brock University30, Cornell University31, Carnegie Institution for Science32, Massachusetts Institute of Technology33, Lunar and Planetary Institute34
TL;DR: The Curiosity rover discovered fine-grained sedimentary rocks, which are inferred to represent an ancient lake and preserve evidence of an environment that would have been suited to support a martian biosphere founded on chemolithoautotrophy.
Abstract: The Curiosity rover discovered fine-grained sedimentary rocks, which are inferred to represent an ancient lake and preserve evidence of an environment that would have been suited to support a martian biosphere founded on chemolithoautotrophy. This aqueous environment was characterized by neutral pH, low salinity, and variable redox states of both iron and sulfur species. Carbon, hydrogen, oxygen, sulfur, nitrogen, and phosphorus were measured directly as key biogenic elements; by inference, phosphorus is assumed to have been available. The environment probably had a minimum duration of hundreds to tens of thousands of years. These results highlight the biological viability of fluvial-lacustrine environments in the post-Noachian history of Mars.
770 citations
TL;DR: The proposed method efficiently makes use of information from close and distant relatives for accurate genotype imputation and is fast, owing to its deterministic nature and, therefore, it can easily be used in large data sets where the use of other methods is impractical.
Abstract: Genotype imputation can help reduce genotyping costs particularly for implementation of genomic selection In applications entailing large populations, recovering the genotypes of untyped loci using information from reference individuals that were genotyped with a higher density panel is computationally challenging Popular imputation methods are based upon the Hidden Markov model and have computational constraints due to an intensive sampling process A fast, deterministic approach, which makes use of both family and population information, is presented here All individuals are related and, therefore, share haplotypes which may differ in length and frequency based on their relationships The method starts with family imputation if pedigree information is available, and then exploits close relationships by searching for long haplotype matches in the reference group using overlapping sliding windows The search continues as the window size is shrunk in each chromosome sweep in order to capture more distant relationships The proposed method gave higher or similar imputation accuracy than Beagle and Impute2 in cattle data sets when all available information was used When close relatives of target individuals were present in the reference group, the method resulted in higher accuracy compared to the other two methods even when the pedigree was not used Rare variants were also imputed with higher accuracy Finally, computing requirements were considerably lower than those of Beagle and Impute2 The presented method took 28 minutes to impute from 6 k to 50 k genotypes for 2,000 individuals with a reference size of 64,429 individuals The proposed method efficiently makes use of information from close and distant relatives for accurate genotype imputation In addition to its high imputation accuracy, the method is fast, owing to its deterministic nature and, therefore, it can easily be used in large data sets where the use of other methods is impractical
766 citations
TL;DR: This work couple fine-grained climate projections to thermal performance data from 38 ectothermic invertebrate species and contrast projections with those of a simple model to show that projections based on mean temperature change alone differ substantially from those incorporating changes to the variation, and to the mean and variation in concert.
Abstract: Increases in the frequency, severity and duration of temperature extremes are anticipated in the near future. Although recent work suggests that changes in temperature variation will have disproportionately greater effects on species than changes to the mean, much of climate change research in ecology has focused on the impacts of mean temperature change. Here, we couple fine-grained climate projections (2050–2059) to thermal performance data from 38 ectothermic invertebrate species and contrast projections with those of a simple model. We show that projections based on mean temperature change alone differ substantially from those incorporating changes to the variation, and to the mean and variation in concert. Although most species show increases in performance at greater mean temperatures, the effect of mean and variance change together yields a range of responses, with temperate species at greatest risk of performance declines. Our work highlights the importance of using fine-grained temporal data to incorporate the full extent of temperature variation when assessing and projecting performance.
714 citations
TL;DR: In this paper, a review of the legislative, chemical, agronomic and environmental literature on anaerobic digestates is presented, showing that digestates can be considered as organic amendments or organic fertilizers, when properly handled and managed.
Abstract: Intensive soil fertilization with mineral fertilizers has led to several issues such as high cost, nitrate pollution and loss of soil carbon. Fertilization with organic matter such as compost therefore represents an alternative for sustainable agriculture. Traditional organic amendments such as manures, composts and sewage sludge have been extensively studied in the past. However, applications of biogas digestates and their impacts on the environment and human health are still unexplored. Recent articles report the agricultural potential and conflicting results of digestate performances. As a consequence, the effectiveness of digestate as organic amendment and fertilizer is still under debate. Here we review the legislative, chemical, agronomic and environmental literature on anaerobic digestates. We found that digestates can be considered as organic amendments or organic fertilizers, when properly handled and managed. Indeed we further show that anaerobic digestates have a higher potential to harm the environment and human health than undigested animal manures and slurries. The main points are the following: (1) Most solid digestates comply with the European organic matter minimal requirement for an organic amendment; (2) the fertilizer values of liquid digestates lie between those of livestock manures and inorganic fertilizers; (3) anaerobic digestates have higher NH3 emission potential than undigested animal manures and slurries and, consequently, pose a greater risk to the broad environment; (4) high Cu and Zn concentrations in digestates from co-digestion of pig and cattle slurry feedstock could jeopardize the sustainability of agricultural soils and (5) high Mn concentrations in digestates can induce Mn toxicity in agricultural soils, upon repeated applications.
646 citations
University of Minnesota1, University of Maryland, College Park2, Iowa State University3, University of Oldenburg4, Utah State University5, Spanish National Research Council6, Wake Forest University7, University of Washington8, United States Department of Agriculture9, Colorado State University10, Michigan State University11, Trinity College, Dublin12, University of Queensland13, University of Toronto14, Lanzhou University15, University of California, San Diego16, Imperial College London17, University of Wisconsin-Madison18, University of Colorado Boulder19, United States Geological Survey20, Queensland University of Technology21, University of North Carolina at Chapel Hill22, University of Oxford23, University of Nebraska–Lincoln24, University of California, Berkeley25, University of Illinois at Urbana–Champaign26, University of Guelph27, University of Kentucky28, University of Melbourne29, Oregon State University30, Commonwealth Scientific and Industrial Research Organisation31, Swiss Federal Institute for Forest, Snow and Landscape Research32, Lancaster University33, Duke University34, University of California, Davis35
TL;DR: Testing the hypothesis that herbaceous plant species losses caused by eutrophication may be offset by increased light availability due to herbivory demonstrates that nutrients and herbivores can serve as counteracting forces to control local plant diversity through light limitation, independent of site productivity, soil nitrogen, herbivore type and climate.
Abstract: Human alterations to nutrient cycles and herbivore communities are affecting global biodiversity dramatically. Ecological theory predicts these changes should be strongly counteractive: nutrient addition drives plant species loss through intensified competition for light, whereas herbivores prevent competitive exclusion by increasing ground-level light, particularly in productive systems. Here we use experimental data spanning a globally relevant range of conditions to test the hypothesis that herbaceous plant species losses caused by eutrophication may be offset by increased light availability due to herbivory. This experiment, replicated in 40 grasslands on 6 continents, demonstrates that nutrients and herbivores can serve as counteracting forces to control local plant diversity through light limitation, independent of site productivity, soil nitrogen, herbivore type and climate. Nutrient addition consistently reduced local diversity through light limitation, and herbivory rescued diversity at sites where it alleviated light limitation. Thus, species loss from anthropogenic eutrophication can be ameliorated in grasslands where herbivory increases ground-level light.
639 citations
Durham University1, National Museum of Natural History2, University of Warwick3, New York University4, Uppsala University5, Swedish University of Agricultural Sciences6, University College London7, University of Pittsburgh8, Australian National University9, University of Aberdeen10, Oklahoma State University–Stillwater11, University of Copenhagen12, Ohio State University13, University of Guelph14, Washington University in St. Louis15, University of Missouri16, University of California, Davis17, University of Granada18
TL;DR: It is argued that although recent progress has been impressive, the next decade will yield even more substantial insights not only into how domestication took place, but also when and where it did, and where and why it did not.
Abstract: It is difficult to overstate the cultural and biological impacts that the domestication of plants and animals has had on our species. Fundamental questions regarding where, when, and how many times domestication took place have been of primary interest within a wide range of academic disciplines. Within the last two decades, the advent of new archaeological and genetic techniques has revolutionized our understanding of the pattern and process of domestication and agricultural origins that led to our modern way of life. In the spring of 2011, 25 scholars with a central interest in domestication representing the fields of genetics, archaeobotany, zooarchaeology, geoarchaeology, and archaeology met at the National Evolutionary Synthesis Center to discuss recent domestication research progress and identify challenges for the future. In this introduction to the resulting Special Feature, we present the state of the art in the field by discussing what is known about the spatial and temporal patterns of domestication, and controversies surrounding the speed, intentionality, and evolutionary aspects of the domestication process. We then highlight three key challenges for future research. We conclude by arguing that although recent progress has been impressive, the next decade will yield even more substantial insights not only into how domestication took place, but also when and where it did, and where and why it did not.
555 citations
TL;DR: A review of the research evidence concerning generational differences in a variety of work-related variables, including personality, work values, work attitudes, leadership, teamwork, work life balance and career patterns, assess its strengths and limitations, and provide directions for future research and theory as discussed by the authors.
Abstract: Summary
Generational differences in the workplace have been a popular topic over the past two decades, generating a volume of articles, book chapters and books. We critically review the research evidence concerning generational differences in a variety of work-related variables, including personality, work values, work attitudes, leadership, teamwork, work–life balance and career patterns, assess its strengths and limitations, and provide directions for future research and theory. Our review indicates that the growing body of research, particularly in the past 5 years, remains largely descriptive, rather than exploring the theoretical underpinnings of the generation construct. Evidence to date is fractured, contradictory and fraught with methodological inconsistencies that make generalizations difficult. The results of time-lag, cross-temporal meta-analytic and cross-sectional studies provide sufficient “proof of concept” for generation as a workplace variable, but further theoretical and qualitative work is needed to flesh out mediators and moderators in the relationship between generation and work-related variables. We conclude by arguing for a more nuanced and theoretical research agenda that views generation as a social force in organizations rather than as merely a demographic variable. We also call for qualitative research, greater consideration of context and more methodological rigor. Copyright © 2013 John Wiley & Sons, Ltd.
539 citations
TL;DR: This work reviews recent advances in the processes used for lipopolysaccharide biosynthesis and export, emphasizing the reactions that are essential for viability.
Abstract: Lipopolysaccharide molecules represent a unique family of glycolipids based on a highly conserved lipid moiety known as lipid A. These molecules are produced by most gram-negative bacteria, in which they play important roles in the integrity of the outer-membrane permeability barrier and participate extensively in host-pathogen interplay. Few bacteria contain lipopolysaccharide molecules composed only of lipid A. In most forms, lipid A is glycosylated by addition of the core oligosaccharide that, in some bacteria, provides an attachment site for a long-chain O-antigenic polysaccharide. The complexity of lipopolysaccharide structures is reflected in the processes used for their biosynthesis and export. Rapid growth and cell division depend on the bacterial cell's capacity to synthesize and export lipopolysaccharide efficiently and in large amounts. We review recent advances in those processes, emphasizing the reactions that are essential for viability.
TL;DR: In this article, the authors present a theory of employee engagement that reconciles and integrates Kahn's (1990) theory of engagement and the Job Demands-Resources (JD-R) model.
Abstract: Employee engagement has become one of the most popular topics in management. In less than 10 years, there have been dozens of studies published on employee engagement as well as several meta-analyses. However, there continue to be concerns about the meaning, measurement, and theory of employee engagement. In this article, we review these concerns as well as research in an attempt to determine what we have learned about employee engagement. We then offer a theory of employee engagement that reconciles and integrates Kahn's (1990) theory of engagement and the Job Demands–Resources (JD-R) model (Bakker & Demerouti, 2007). We conclude that there continues to be a lack of consensus on the meaning of employee engagement as well as concerns about the validity of the most popular measure of employee engagement. Furthermore, it is difficult to make causal conclusions about the antecedents and consequences of employee engagement due to a number of research limitations. Thus, there remain many unanswered questions and much more to do if we are to develop a science and theory of employee engagement.
TL;DR: In this paper, current nanocomposite technologies to enhance the mechanical and barrier properties of synthetic polymers and biopolymers for food packaging are reviewed, including antimicrobial, oxygen scavenging, and shelf-life extension of food.
Abstract: In this article, current nanocomposite technologies to enhance the mechanical and barrier properties of synthetic polymers and biopolymers for food packaging are reviewed. In addition, nanotechnology developments targeting active packaging applications are discussed, including antimicrobial, oxygen scavenging, and shelf-life extension of food. Nanotechnologies that are currently being exploited for the development of intelligent packaging with enhanced communication function are presented, focusing mainly on oxygen, humidity and freshness indicators. Nanostructured coatings that enhance the barrier properties of packaging films are reviewed. And finally, the perspectives of nanotechnology in food packaging applications are discussed.
Lehigh University1, University of Hawaii at Manoa2, Bowdoin College3, University of Eastern Finland4, University of Exeter5, Eton College6, Stockholm University7, University of Southampton8, Queen Mary University of London9, University of Wisconsin–La Crosse10, University of Gloucestershire11, University of Toulouse12, Adam Mickiewicz University in Poznań13, University of Toronto14, Université du Québec à Montréal15, Lund University16, University of California, Los Angeles17, United States Geological Survey18, University of Copenhagen19, University of Helsinki20, University of Nottingham21, Laval University22, Geological Survey of Finland23, University of Aberdeen24, McGill University25, Columbia University26, Université de Montréal27, Champlain College28, Agriculture and Agri-Food Canada29, University of Guelph30, University of Amsterdam31, Southern Illinois University Carbondale32, Chinese Academy of Sciences33
TL;DR: In this paper, the authors present results from the most comprehensive compilation of Holocene peat soil properties with associated carbon and nitrogen accumulation rates for northern peatlands, which consists of 268 peat cores from 215 sites located north of 45°N.
Abstract: Here, we present results from the most comprehensive compilation of Holocene peat soil properties with associated carbon and nitrogen accumulation rates for northern peatlands. Our database consists of 268 peat cores from 215 sites located north of 45°N. It encompasses regions within which peat carbon data have only recently become available, such as the West Siberia Lowlands, the Hudson Bay Lowlands, Kamchatka in Far East Russia, and the Tibetan Plateau. For all northern peatlands, carbon content in organic matter was estimated at 42 ± 3% (standard deviation) for Sphagnum peat, 51 ± 2% for non-Sphagnum peat, and at 49 ± 2% overall. Dry bulk density averaged 0.12 ± 0.07 g/cm3, organic matter bulk density averaged 0.11 ± 0.05 g/cm3, and total carbon content in peat averaged 47 ± 6%. In general, large differences were found between Sphagnum and non-Sphagnum peat types in terms of peat properties. Time-weighted peat carbon accumulation rates averaged 23 ± 2 (standard error of mean) g C/m2/yr during the Holocene on the basis of 151 peat cores from 127 sites, with the highest rates of carbon accumulation (25-28 g C/m2/yr) recorded during the early Holocene when the climate was
University of Guelph1, Mount Holyoke College2, Manchester Metropolitan University3, Stockholm University4, University of Bristol5, University of Helsinki6, McGill University7, University of Edinburgh8, University of Jyväskylä9, University of Eastern Finland10, McMaster University11, Indiana University12, United States Geological Survey13, University of Greifswald14
TL;DR: It is suggested that water table and temperature are dominant controls on methane flux in pristine bogs and swamps, while other processes, such as vascular transport in pristine fens, have the potential to partially override the effect of these controls in other wetland types.
Abstract: Wetlands are the largest natural source of atmospheric methane. Here, we assess controls on methane flux using a database of approximately 19 000 instantaneous measurements from 71 wetland sites located across subtropical, temperate, and northern high latitude regions. Our analyses confirm general controls on wetland methane emissions from soil temperature, water table, and vegetation, but also show that these relationships are modified depending on wetland type (bog, fen, or swamp), region (subarctic to temperate), and disturbance. Fen methane flux was more sensitive to vegetation and less sensitive to temperature than bog or swamp fluxes. The optimal water table for methane flux was consistently below the peat surface in bogs, close to the peat surface in poor fens, and above the peat surface in rich fens. However, the largest flux in bogs occurred when dry 30-day averaged antecedent conditions were followed by wet conditions, while in fens and swamps, the largest flux occurred when both 30-day averaged antecedent and current conditions were wet. Drained wetlands exhibited distinct characteristics, e.g. the absence of large flux following wet and warm conditions, suggesting that the same functional relationships between methane flux and environmental conditions cannot be used across pristine and disturbed wetlands. Together, our results suggest that water table and temperature are dominant controls on methane flux in pristine bogs and swamps, while other processes, such as vascular transport in pristine fens, have the potential to partially override the effect of these controls in other wetland types. Because wetland types vary in methane emissions and have distinct controls, these ecosystems need to be considered separately to yield reliable estimates of global wetland methane release.
University of Minnesota1, Utah State University2, Iowa State University3, University of Oldenburg4, University of Guelph5, Lancaster University6, University of Washington7, University of Queensland8, Lanzhou University9, University of New Mexico10, Spanish National Research Council11, University of Wisconsin-Madison12, University of Colorado Boulder13, United States Department of Agriculture14, Queensland University of Technology15, University of Maryland, College Park16, Colorado State University17, University of Nebraska–Lincoln18, University of California, Berkeley19, Southwest Forestry University20, University of Kentucky21, University of Melbourne22, Oregon State University23, Commonwealth Scientific and Industrial Research Organisation24, Swiss Federal Institute for Forest, Snow and Landscape Research25, National Centre for Biological Sciences26, University of Oxford27
TL;DR: This paper analyzed diversity-stability relationships from 41 grasslands on five continents and examined how these relationships are affected by chronic fertilization, one of the strongest drivers of species loss globally.
Abstract: Studies of experimental grassland communities have demonstrated that plant diversity can stabilize productivity through species asynchrony, in which decreases in the biomass of some species are compensated for by increases in others. However, it remains unknown whether these findings are relevant to natural ecosystems, especially those for which species diversity is threatened by anthropogenic global change. Here we analyse diversity-stability relationships from 41 grasslands on five continents and examine how these relationships are affected by chronic fertilization, one of the strongest drivers of species loss globally. Unmanipulated communities with more species had greater species asynchrony, resulting in more stable biomass production, generalizing a result from biodiversity experiments to real-world grasslands. However, fertilization weakened the positive effect of diversity on stability. Contrary to expectations, this was not due to species loss after eutrophication but rather to an increase in the temporal variation of productivity in combination with a decrease in species asynchrony in diverse communities. Our results demonstrate separate and synergistic effects of diversity and eutrophication on stability, emphasizing the need to understand how drivers of global change interactively affect the reliable provisioning of ecosystem services in real-world systems.
Douglas W. Ming, P. D. Archer, Daniel P. Glavin1, Jennifer L. Eigenbrode1 +439 more•Institutions (55)
TL;DR: Higher abundances of chlorinated hydrocarbons in the mudstone compared with Rocknest windblown materials previously analyzed by Curiosity suggest that indigenous martian or meteoritic organic carbon sources may be preserved in the Mudstone; however, the carbon source for the chlorinatedHydrocarbons is not definitively of martian origin.
Abstract: H2O, CO2, SO2, O2, H2, H2S, HCl, chlorinated hydrocarbons, NO, and other trace gases were evolved during pyrolysis of two mudstone samples acquired by the Curiosity rover at Yellowknife Bay within Gale crater, Mars. H2O/OH-bearing phases included 2:1 phyllosilicate(s), bassanite, akaganeite, and amorphous materials. Thermal decomposition of carbonates and combustion of organic materials are candidate sources for the CO2. Concurrent evolution of O2 and chlorinated hydrocarbons suggests the presence of oxychlorine phase(s). Sulfides are likely sources for sulfur-bearing species. Higher abundances of chlorinated hydrocarbons in the mudstone compared with Rocknest windblown materials previously analyzed by Curiosity suggest that indigenous martian or meteoritic organic carbon sources may be preserved in the mudstone; however, the carbon source for the chlorinated hydrocarbons is not definitively of martian origin.
University of New South Wales1, University of California, Los Angeles2, Max Planck Society3, Queen's University4, University of Guelph5, University of Innsbruck6, University of Arizona7, VU University Amsterdam8, National University of Cordoba9, Royal Botanic Gardens10, Centre national de la recherche scientifique11, Austral University of Chile12, ETH Zurich13, Goethe University Frankfurt14, University of Oldenburg15, Tohoku University16, Macquarie University17, University of Life Sciences in Lublin18, Moscow State University19, Kyoto University20, Spanish National Research Council21, Universidade Federal do Rio Grande do Sul22, Hokkaido University23, Syracuse University24, Empresa Brasileira de Pesquisa Agropecuária25, University of Amsterdam26, University of Aberdeen27, Michigan State University28, University of Wisconsin–Eau Claire29, University of Tartu30
TL;DR: This work quantified the strength of the relationships between temperature and precipitation and 21 plant traits from 447,961 species-site combinations worldwide and used meta-analysis to provide an overall answer to the question.
Abstract: Question: Are plant traits more closely correlated with mean annual temperature, or with mean annual precipitation? Location: Global. Methods: We quantified the strength of the relationships between temperature and precipitation and 21 plant traits from 447,961 species-site combinations worldwide. We used meta-analysis to provide an overall answer to our question.
TL;DR: The up‐regulation of cold signaling genes by melatonin may stimulate the biosynthesis of cold‐protecting compounds and contribute to the increased growth of plants treated with exogenous melatonin under cold stress.
Abstract: Melatonin (N-acetyl-5-methoxytryptamine) has been implicated in abiotic and biotic stress tolerance in plants. However, information on the effects of melatonin in cold-stress tolerance in vivo is limited. In this study, the effect of melatonin was investigated in the model plant Arabidopsis thaliana challenged with a cold stress at 4⁰C for 72 and 120 hr. Melatonin-treated plants (10 and 30 μm) had significantly higher fresh weight, primary root length, and shoot height compared with the nontreated plants. To aid in the understanding of the role of melatonin in alleviating cold stress, we investigated the effects of melatonin treatment on the expression of cold-related genes. Melatonin up-regulated the expression of C-repeat-binding factors (CBFs)/Drought Response Element Binding factors (DREBs), a cold-responsive gene, COR15a, a transcription factor involved in freezing and drought-stress tolerance CAMTA1 and transcription activators of reactive oxygen species (ROS)-related antioxidant genes, ZAT10 and ZAT12, following cold stress. The up-regulation of cold signaling genes by melatonin may stimulate the biosynthesis of cold-protecting compounds and contribute to the increased growth of plants treated with exogenous melatonin under cold stress.
TL;DR: For advancing the field of polyploid population genetics, most priority should be given to development of new molecular approaches that allow efficient dosage determination, and to further development of analytical approaches to circumvent dosage uncertainty and to accommodate ‘flexible’ modes of inheritance.
Abstract: Despite the importance of polyploidy and the increasing availability of new genomic data, there remain important gaps in our knowledge of polyploid population genetics. These gaps arise from the complex nature of polyploid data (e.g. multiple alleles and loci, mixed inheritance patterns, association between ploidy and mating system variation). Furthermore, many of the standard tools for population genetics that have been developed for diploids are often not feasible for polyploids. This review aims to provide an overview of the state-of-the-art in polyploid population genetics and to identify the main areas where further development of molecular techniques and statistical theory is required. We review commonly used molecular tools (amplified fragment length polymorphism, microsatellites, Sanger sequencing, next-generation sequencing and derived technologies) and their challenges associated with their use in polyploid populations: that is, allele dosage determination, null alleles, difficulty of distinguishing orthologues from paralogues and copy number variation. In addition, we review the approaches that have been used for population genetic analysis in polyploids and their specific problems. These problems are in most cases directly associated with dosage uncertainty and the problem of inferring allele frequencies and assumptions regarding inheritance. This leads us to conclude that for advancing the field of polyploid population genetics, most priority should be given to development of new molecular approaches that allow efficient dosage determination, and to further development of analytical approaches to circumvent dosage uncertainty and to accommodate ‘flexible’ modes of inheritance. In addition, there is a need for more simulation-based studies that test what kinds of biases could result from both existing and novel approaches.
TL;DR: In this article, the feasibility of two different thermal pre-treatments, torrefaction and hydrothermal carbonization (HTC), followed by densification, was evaluated in terms of the strength, storage, and combustion properties for energy applications.
TL;DR: The concept of carryover effects provides an explicit but highly flexible context for examining the mechanisms that drive non-lethal interactions between distinct periods of an organism's lifetime, and unites the currently disparate fields investigating these effects in ecological systems.
Abstract: The term 'carryover effect' originally arose from repeated measures clinical experiments. However, the term has more recently been applied to ecological and evolutionary studies, often in migratory systems, which has led to an emphasis on non-lethal effects across seasons. In this article, we suggest that ecological carryover effects can also occur between life-history stages, developmental stages, physiological states, or social situations, and each will be associated with a discrete time-scale. Therefore, we propose the working definition: In an ecological context, carryover effects occur in any situation in which an individual's previous history and experience explains their current performance in a given situation. This concept of carryover effects provides an explicit but highly flexible context for examining the mechanisms that drive non-lethal interactions between distinct periods of an organism's lifetime, and unites the currently disparate fields investigating these effects in ecological systems. Greater communication among research fields and identifying mechanisms of carryover effects at different time scales will ultimately lead to a better understanding of the factors influencing variation in individual fitness.
State University of New York System1, United States Geological Survey2, Arizona State University3, University of Leicester4, California Institute of Technology5, University of Guelph6, Space Science Institute7, Los Alamos National Laboratory8, Goddard Space Flight Center9, Ames Research Center10, University of Lyon11, Mount Holyoke College12, Centre national de la recherche scientifique13, University of Toulouse14, University of New Mexico15, Smithsonian Institution16, Imperial College London17, Australian National University18, University of Nantes19, Rensselaer Polytechnic Institute20, Canadian Space Agency21, Princeton University22, Brock University23, Open University24, University of California, Davis25, Planetary Science Institute26
TL;DR: The absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low-temperature, circumneutral pH, rock-dominated aqueous conditions during the early history of Mars.
Abstract: Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion and deposition. The absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low-temperature, circumneutral pH, rock-dominated aqueous conditions. Analyses of diagenetic features (including concretions, raised ridges, and fractures) at high spatial resolution indicate that they are composed of iron- and halogen-rich components, magnesium-iron-chlorine–rich components, and hydrated calcium sulfates, respectively. Composition of a cross-cutting dike-like feature is consistent with sedimentary intrusion. The geochemistry of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of Mars.
University of Toronto1, University of Guelph2, University of Nebraska–Lincoln3, Yale University4, University of California, Los Angeles5, University of California, San Diego6, University of Göttingen7, University of Wisconsin-Madison8, University of British Columbia9, Queen Mary University of London10, Imperial College London11, University of Sheffield12, Stockholm University13, University of Canterbury14
TL;DR: This framework provides a mechanistic and more unified understanding of the temperature dependence of trophic dynamics in terms of ecological rates, biomass ratios and stability and characterises key asymmetries in species responses to temperature that produce these distinct dynamic behaviours.
Abstract: Changing temperature can substantially shift ecological communities by altering the strength and stability of trophic interactions. Because many ecological rates are constrained by temperature, new approaches are required to understand how simultaneous changes in multiple rates alter the relative performance of species and their trophic interactions. We develop an energetic approach to identify the relationship between biomass fluxes and standing biomass across trophic levels. Our approach links ecological rates and trophic dynamics to measure temperature-dependent changes to the strength of trophic interactions and determine how these changes alter food web stability. It accomplishes this by using biomass as a common energetic currency and isolating three temperature-dependent processes that are common to all consumer-resource interactions: biomass accumulation of the resource, resource consumption and consumer mortality. Using this framework, we clarify when and how temperature alters consumer to resource biomass ratios, equilibrium resilience, consumer variability, extinction risk and transient vs. equilibrium dynamics. Finally, we characterise key asymmetries in species responses to temperature that produce these distinct dynamic behaviours and identify when they are likely to emerge. Overall, our framework provides a mechanistic and more unified understanding of the temperature dependence of trophic dynamics in terms of ecological rates, biomass ratios and stability.
Book•
29 May 2014TL;DR: In this article, the authors presented a unique presentation of Einstein's theory by developing powerful methods that can be applied to astrophysical systems, such as planetary motion around the Sun, the timing of binary pulsars, and gravitational waves emitted by binary black holes.
Abstract: This textbook explores approximate solutions to general relativity and their consequences. It offers a unique presentation of Einstein's theory by developing powerful methods that can be applied to astrophysical systems. Beginning with a uniquely thorough treatment of Newtonian gravity, the book develops post-Newtonian and post-Minkowskian approximation methods to obtain weak-field solutions to the Einstein field equations. The book explores the motion of self-gravitating bodies, the physics of gravitational waves, and the impact of radiative losses on gravitating systems. It concludes with a brief overview of alternative theories of gravity. Ideal for graduate courses on general relativity and relativistic astrophysics, the book examines real-life applications, such as planetary motion around the Sun, the timing of binary pulsars, and gravitational waves emitted by binary black holes. Text boxes explore related topics and provide historical context, and over 100 exercises present challenging tests of the material covered in the main text.
TL;DR: It is shown that next-generation sequencing (NGS) of cytochrome c oxidase subunit I (COI) DNA barcodes can accurately detect 83.5% of individually sequenced species in a bulk sample of terrestrial arthropods from a Costa Rican species-rich site.
Abstract: Conventional assessments of ecosystem sample composition are based on morphology-based or DNA barcode identification of individuals. Both approaches are costly and time-consuming, especially when applied to the large number of specimens and taxa commonly included in ecological investigations. Next-generation sequencing approaches can overcome the bottleneck of individual specimen isolation and identification by simultaneously sequencing specimens of all taxa in a bulk mixture. Here we apply multiple parallel amplification primers, multiple DNA barcode markers, 454-pyrosequencing, and Illumina MiSeq sequencing to the same sample to maximize recovery of the arthropod macrobiome and the bacterial and other microbial microbiome of a bulk arthropod sample. We validate this method with a complex sample containing 1,066 morphologically distinguishable arthropods from a tropical terrestrial ecosystem with high taxonomic diversity. Multiamplicon next-generation DNA barcoding was able to recover sequences corresponding to 91% of the distinguishable individuals in a bulk environmental sample, as well as many species present as undistinguishable tissue. 454-pyrosequencing was able to recover 10 more families of arthropods and 30 more species than did conventional Sanger sequencing of each individual specimen. The use of other loci (16S and 18S ribosomal DNA gene regions) also added the detection of species of microbes associated with these terrestrial arthropods. This method greatly decreases the time and money necessary to perform DNA-based comparisons of biodiversity among ecosystem samples. This methodology opens the door to much cheaper and increased capacity for ecological and evolutionary studies applicable to a wide range of socio-economic issues, as well as a basic understanding of how the world works.
TL;DR: In this article, the microstructure, melting and crystallization behavior, rheological properties and oil binding capacity of crystalline networks of plant-derived waxes in edible oil were studied and then compared amongst different wax types.
Abstract: The microstructure, melting and crystallization behavior, rheological properties and oil binding capacity of crystalline networks of plant-derived waxes in edible oil were studied and then compared amongst different wax types. The critical concentrations for oleogelation of canola oil by rice bran wax (RBX), sunflower wax, candelilla wax, and carnauba wax were 1, 1, 2, and 4 %, respectively, suggesting RBX and sunflower wax are more efficient structurants. A phenomenological two-phase exponential decay model was implemented to quantify the oil-binding capacity of these oleogels. Parameters obtained from this empirical model were then evaluated against microscale structural attributes such as crystal size, mass distribution and porosity to determine the structural dependence of oil-binding capacity. Gels containing candelilla wax exhibited the greatest oil-binding capacity, as they retained nearly 90 % of their oil. This is due to the small crystal size as well as the spatial distribution of these crystals. Using a microscopic to macroscopic approach, this study examines how the structural characteristics unique to each wax and resulting oleogel system affect functionality and macroscopic behavior.
TL;DR: Variation in the vulnerability of C stored in permafrost soils based on inherent differences in organic matter decomposability is demonstrated, and point toward C : N as an index of decomposable that has the potential to be used to scalepermafrost C loss across landscapes.
Abstract: High-latitude ecosystems store approximately 1700 Pg of soil carbon (C), which is twice as much C as is currently contained in the atmosphere. Permafrost thaw and subsequent microbial decomposition of permafrost organic matter could add large amounts of C to the atmosphere, thereby influencing the global C cycle. The rates at which C is being released from the permafrost zone at different soil depths and across different physiographic regions are poorly understood but crucial in understanding future changes in permafrost C storage with climate change. We assessed the inherent decomposability of C from the permafrost zone by assembling a database of long-term (>1 year) aerobic soil incubations from 121 individual samples from 23 high-latitude ecosystems located across the northern circumpolar permafrost zone. Using a three-pool (i.e., fast, slow and passive) decomposition model, we estimated pool sizes for C fractions with different turnover times and their inherent decomposition rates using a reference temperature of 5 °C. Fast cycling C accounted for less than 5% of all C in both organic and mineral soils whereas the pool size of slow cycling C increased with C : N. Turnover time at 5 °C of fast cycling C typically was below 1 year, between 5 and 15 years for slow turning over C, and more than 500 years for passive C. We project that between 20 and 90% of the organic C could potentially be mineralized to CO2 within 50 incubation years at a constant temperature of 5 °C, with vulnerability to loss increasing in soils with higher C : N. These results demonstrate the variation in the vulnerability of C stored in permafrost soils based on inherent differences in organic matter decomposability, and point toward C : N as an index of decomposability that has the potential to be used to scale permafrost C loss across landscapes.
TL;DR: This study tested the congruence of OTUs resulting from the application of three analytical methods to sequence data for Australian hypertrophine moths, revealing 124 OTUs of Hypertrophinae, a more than twofold increase from the currently recognized 51 species.
Abstract: The analysis of DNA barcode sequences with varying techniques for cluster recognition provides an efficient approach for recognizing putative species (operational taxonomic units, OTUs). This approach accelerates and improves taxonomic workflows by exposing cryptic species and decreasing the risk of synonymy. This study tested the congruence of OTUs resulting from the application of three analytical methods (ABGD, BIN, GMYC) to sequence data for Australian hypertrophine moths. OTUs supported by all three approaches were viewed as robust, but 20% of the OTUs were only recognized by one or two of the methods. These OTUs were examined for three criteria to clarify their status. Monophyly and diagnostic nucleotides were both uninformative, but information on ranges was useful as sympatric sister OTUs were viewed as distinct, while allopatric OTUs were merged. This approach revealed 124 OTUs of Hypertrophinae, a more than twofold increase from the currently recognized 51 species. Because this analytical protocol is both fast and repeatable, it provides a valuable tool for establishing a basic understanding of species boundaries that can be validated with subsequent studies.
TL;DR: Results suggest that colonic fermentation may alter the biological activity of blueberry polyphenols.