Fusarium graminearum forms mycotoxin producing infection structures on wheat

<p>Abstract</p> <p>Background</p> <p>The mycotoxin producing fungal pathogen <it>Fusarium graminearum </it>is the causal agent of Fusarium head blight (FHB) of small grain cereals in fields worldwide. Although <it>F. graminearum </it>is highly investigated by means of molecular genetics, detailed studies about hyphal development during initial infection stages are rare. In addition, the role of mycotoxins during initial infection stages of FHB is still unknown. Therefore, we investigated the infection strategy of the fungus on different floral organs of wheat (<it>Triticum aestivum </it>L.) under real time conditions by constitutive expression of the <it>dsRed </it>reporter gene in a <it>TRI5prom</it>::<it>GFP </it>mutant. Additionally, trichothecene induction during infection was visualised with a green fluorescent protein (GFP) coupled <it>TRI5 </it>promoter. A tissue specific infection pattern and <it>TRI5 </it>induction were tested by using different floral organs of wheat. Through combination of bioimaging and electron microscopy infection structures were identified and characterised. In addition, the role of trichothecene production for initial infection was elucidated by a Δ<it>TRI5</it>-<it>GFP </it>reporter strain.</p> <p>Results</p> <p>The present investigation demonstrates the formation of foot structures and compound appressoria by <it>F. graminearum</it>. All infection structures developed from epiphytic runner hyphae. Compound appressoria including lobate appressoria and infection cushions were observed on inoculated caryopses, paleas, lemmas, and glumes of susceptible and resistant wheat cultivars. A specific trichothecene induction in infection structures was demonstrated by different imaging techniques. Interestingly, a Δ<it>TRI5</it>-<it>GFP </it>mutant formed the same infection structures and exhibited a similar symptom development compared to the wild type and the <it>TRI5prom</it>::<it>GFP </it>mutant.</p> <p>Conclusions</p> <p>The different specialised infection structures of <it>F. graminearum </it>on wheat florets, as described in this study, indicate that the penetration strategy of this fungus is far more complex than postulated to date. We show that trichothecene biosynthesis is specifically induced in infection structures, but is neither necessary for their development nor for formation of primary symptoms on wheat.</p

Physically, physiologically and conceptually hidden: improving the description and communication of seed persistence

Seed persistence is a trait that is difficult to observe or measure and consequently, has remained conceptually obscure for 40 years since Grubb’s influential description of the regeneration niche. Seed persistence is the ability of seeds to persist in a viable state post-dispersal and is relevant to current research in plant community dynamics and conservation. However, categorisations of seed persistence as transient, short-term or long-term persistent do not acknowledge the variation in persistence times as a result of deterministic processes and are difficult to apply in a predictive capacity. Consequently, a more robust understanding of seed persistence is needed in niche descriptions that are temporally explicit and in predicting the distributional changes of species in the current and future climate. We surmise an alternative to the categorizations of seed persistence on the basis of seed bank type and argue that it is best expressed as a continuous variable. We review the methods available for estimating seed persistence in situ and provide a number of testable hypotheses to contribute to the development of this important research topic. We maintain that seed persistence has not been incorporated adequately into niche theory and highlight that it can make several contributions including properly defining metapopulation niche, population growth definition. This holistic approach by integrating seed persistence into niche theory would allow us to better predict the survival of plants in a changing environment

The effect of pH, grain size, and organic ligands on biotite weathering rates

Biotite dissolution rates were determined at 25 °C, at pH 2–6, and as a function of mineral composition, grain size, and aqueous organic ligand concentration. Rates were measured using both open- and closed-system reactors in fluids of constant ionic strength. Element release was non-stoichiometric and followed the general trend of Fe, Mg > Al > Si. Biotite surface area normalised dissolution rates (ri) in the acidic range, generated from Si release, are consistent with the empirical rate law: ri=kH,iaxiH+ where kH,i refers to an apparent rate constant, aH+ designates the activity of protons, and xi stands for a reaction order with respect to protons. Rate constants range from 2.15 × 10−10 to 30.6 × 10−10 (molesbiotite m−2 s−1) with reaction orders ranging from 0.31 to 0.58. At near-neutral pH in the closed-system experiments, the release of Al was stoichiometric compared to Si, but Fe was preferentially retained in the solid phase, possibly as a secondary phase. Biotite dissolution was highly spatially anisotropic with its edges being ∼120 times more reactive than its basal planes. Low organic ligand concentrations slightly enhanced biotite dissolution rates. These measured rates illuminate mineral–fluid–organism chemical interactions, which occur in the natural environment, and how organic exudates enhance nutrient mobilisation for microorganism acquisition

Toward sharing brain images: Differentially private TOF-MRA images with segmentation labels using generative adversarial networks

Sharing labeled data is crucial to acquire large datasets for various Deep Learning applications. In medical imaging, this is often not feasible due to privacy regulations. Whereas anonymization would be a solution, standard techniques have been shown to be partially reversible. Here, synthetic data using a Generative Adversarial Network (GAN) with differential privacy guarantees could be a solution to ensure the patient's privacy while maintaining the predictive properties of the data. In this study, we implemented a Wasserstein GAN (WGAN) with and without differential privacy guarantees to generate privacy-preserving labeled Time-of-Flight Magnetic Resonance Angiography (TOF-MRA) image patches for brain vessel segmentation. The synthesized image-label pairs were used to train a U-net which was evaluated in terms of the segmentation performance on real patient images from two different datasets. Additionally, the Fréchet Inception Distance (FID) was calculated between the generated images and the real images to assess their similarity. During the evaluation using the U-Net and the FID, we explored the effect of different levels of privacy which was represented by the parameter ϵ. With stricter privacy guarantees, the segmentation performance and the similarity to the real patient images in terms of FID decreased. Our best segmentation model, trained on synthetic and private data, achieved a Dice Similarity Coefficient (DSC) of 0.75 for ϵ = 7.4 compared to 0.84 for ϵ = ∞ in a brain vessel segmentation paradigm (DSC of 0.69 and 0.88 on the second test set, respectively). We identified a threshold of ϵ <5 for which the performance (DSC <0.61) became unstable and not usable. Our synthesized labeled TOF-MRA images with strict privacy guarantees retained predictive properties necessary for segmenting the brain vessels. Although further research is warranted regarding generalizability to other imaging modalities and performance improvement, our results mark an encouraging first step for privacy-preserving data sharing in medical imaging

Plant attributes explain the distribution of soil microbial communities in two contrasting regions of the globe

We lack strong empirical evidence for links between plant attributes (plant community attributes and functional traits) and the distribution of soil microbial communities at large spatial scales. Using datasets from two contrasting regions and ecosystem types in Australia and England, we report that aboveground plant community attributes, such as diversity (species richness) and cover, and functional traits can predict a unique portion of the variation in the diversity (number of phylotypes) and community composition of soil bacteria and fungi that cannot be explained by soil abiotic properties and climate. We further identify the relative importance and evaluate the potential direct and indirect effects of climate, soil properties and plant attributes in regulating the diversity and community composition of soil microbial communities. Finally, we deliver a list of examples of common taxa from Australia and England that are strongly related to specific plant traits, such as specific leaf area index, leaf nitrogen and nitrogen fixation. Together, our work provides new evidence that plant attributes, especially plant functional traits, can predict the distribution of soil microbial communities at the regional scale and across two hemispheres

Assessing diverse evidence to improve conservation decision-making

Meeting the urgent need to protect and restore ecosystems requires effective decision‐making through wisely considering a range of evidence. However, weighing and assessing evidence to make complex decisions is challenging, particularly when evidence is of diverse types, subjects, and sources, and varies greatly in its quality and relevance. To tackle these challenges, we present the Balance Evidence Assessment Method (BEAM), an intuitive way to weigh and assess the evidence relating to the core assumptions underpinning the planning and implementation of conservation projects, strategies, and actions. Our method directly tackles the question of how to bring together diverse evidence whilst assessing its relevance, reliability, and strength of support for a given assumption, which can be mapped, for example to a Theory of Change. We consider how simple principles and safeguards in applying this method could help to respectfully, and equitably, include more local forms of knowledge when assessing assumptions, such as by ensuring diverse groups of individuals contribute and assess evidence. The method can be flexibly applied within existing decision‐making tools, platforms, and frameworks whenever assumptions (i.e., claims and hypotheses) are made. This method could greatly facilitate and improve the weighing of diverse evidence to make decisions in a range of situations, from local projects to global policy platforms

Experimental observations of CO2-water-basaltic glass interaction in a large column reactor experiment at 50 °C

Publisher's version (útgefin grein).Mineralization of water dissolved carbon dioxide injected into basaltic rocks occurs within two years in field-scale settings. Here we present the results from a CO2-water-basaltic glass laboratory experiment conducted at 50 °C and 80 bar pressure in a Ti high-pressure column flow reactor. We explore the possible sequence of saturation with Fe-Mg-Ca-carbonate minerals versus Fe-Mg-clay and Ca-zeolite saturation states, which all compete for divalent cations and pore space during injection of CO2 into basaltic rocks. Pure water (initially with atmospheric CO2) – basaltic glass reactions resulted in high pH (9–10) water saturated with respect to Mg-Fe-clays (saponites), Ca-zeolites, and Ca-carbonate. As CO2-charged water (˜20 mM) entered the column and mixed with the high pH water, all the Fe-Mg-Ca-carbonates became temporarily supersaturated along with clays and zeolites. Injected waters with dissolved CO2 reached carbonate mineral saturation within 12 h of fluid-rock interaction. Once the pH of the outflow water stabilized below 6, siderite was the only thermodynamically stable carbonate throughout the injection period, although no physical evidence of its precipitation was found. When CO2 injection stopped while continuing to inject pure water, pH rose rapidly in the outflow and all carbonates became undersaturated, whereas zeolites became more saturated and Mg-Fe-saponites supersaturated. Resuming CO2 injection lowered the pH from >8 to about 6, resulting in an undersaturation of the clays and Na-zeolites. These results along with geochemical modelling underscore the importance of initial pCO2 and pH values to obtain a balance between the formation of carbonates versus clays and zeolites. Moreover, modelling indicates that pauses in CO2 injection while still injecting water can result in enhanced large molar volume Ca-Na-zeolite and Mg-Fe-clay formation that consumes pore space within the rocks.This publication has been produced with support from the European Commission through the projects CarbFix (EC Project 283148), CO2-React (EC Project 317235), and S4CE (EC Project 764810). The authors would like to thank editor Charles Jenkins for handling the manuscript and to the anonymous reviewers for their constructive comments that helped improve the manuscript. Special thanks to Giulia Alessandrini for her indispensable assistance in running the experiment, Sydney Gunnarson for material preparation, and Þorsteinn Jónsson for preparing, setting up, and taking apart the column. We would also like to acknowledge Rebecca Neely and Tobias Linke for their help in the laboratory in addition to Eric Oelkers, Peter Rendel, and the CarbFix group for their support.Peer Reviewe

Paternal Diet Defines Offspring Chromatin State and Intergenerational Obesity

The global rise in obesity has revitalized a search for genetic and epigenetic factors underlying the disease. We present a Drosophila model of paternal-diet-induced intergenerational metabolic reprogramming (IGMR) and identify genes required for its encoding in offspring. Intriguingly, we find that as little as 2 days of dietary intervention in fathers elicits obesity in offspring. Paternal sugar acts as a physiological suppressor of variegation, desilencing chromatin-state-defined domains in both mature sperm and in offspring embryos. We identify requirements for H3K9/K27me3-dependent reprogramming of metabolic genes in two distinct germline and zygotic windows. Critically, we find evidence that a similar system may regulate obesity susceptibility and phenotype variation in mice and humans. The findings provide insight into the mechanisms underlying intergenerational metabolic reprogramming and carry profound implications for our understanding of phenotypic variation and evolution

Rapid solubility and mineral storage of CO2 in basalt

The long-term security of geologic carbon storage is critical to its success and public acceptance. Much of the security risk associated with geological carbon storage stems from its buoyancy. Gaseous and supercritical CO2 are less dense than formation waters, providing a driving force for it to escape back to the surface. This buoyancy can be eliminated by the dissolution of CO2 into water prior to, or during its injection into the subsurface. The dissolution makes it possible to inject into fractured rocks and further enhance mineral storage of CO2 especially if injected into silicate rocks rich in divalent metal cations such as basalts and ultra-mafic rocks. We have demonstrated the dissolution of CO2 into water during its injection into basalt leading to its geologic solubility storage in less than five minutes and potential geologic mineral storage within few years after injection [1–3]. The storage potential of CO2 within basaltic rocks is enormous. All the carbon released from burning of all fossil fuel on Earth, 5000 GtC, can theoretically be stored in basaltic rocks [4]