Evidence for strain-specific exometabolomic responses of the coccolithophore Emiliania huxleyi to grazing by the dinoflagellate oxyrrhis marina

© The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Frontiers in Marine Science 3 (2016): 1, doi:10.3389/fmars.2016.00001.The coccolithophore Emiliania huxleyi forms massive blooms and plays a critical role in global elemental cycles, sequestering significant amounts of atmospheric carbon dioxide on geological time scales via production of calcium carbonate coccoliths and emitting dimethyl sulfoniopropionate (DMSP), which has the potential for increasing atmosph-eric albedo. Because grazing in pelagic systems is a major top-down force structuring microbial communities, the influence of grazers on E. huxleyi populations has been of interest to researchers. Roles of DMSP (and related metabolites) in interactions between E. huxleyi and protist grazers have been investigated, however, little is known about the release of other metabolites that may influence, or be influenced by, such grazing interactions. We used high-resolution mass spectrometry in an untargeted approach to survey the suite of low molecular weight compounds released by four different E. huxleyi strains in response to grazing by the dinoflagellate Oxyrrhis marina. Overall, a strikingly small number of metabolites were detected from E. huxleyi and O. marina cells, but these were distinctly informative to construct metabolic footprints. At most, E. huxleyi strains shared 25% of released metabolites. Furthermore, there appeared to be no unified metabolic response in E. huxleyi strains to grazing; rather, these responses were strain specific. Concentrations of several metabolites also positively correlated with grazer activities, including grazing, ingestion, and growth rates; however, no single metabolite responded uniformly across all strains of E. huxleyi tested. Regardless, grazing clearly transformed the constituents of dissolved organic matter produced by these marine microbes. This study addresses several technical challenges, and presents a platform to further study the influence of chemical cues in aquatic systems and demonstrates the impact of strain diversity and grazing on the complexity of dissolved organic matter in marine systems.Funding for this work was provided by the Gordon and Betty Moore Foundation, Grant #3301 awarded to A Vardi, BAS. Van Mooy, K Bidle, MJ, and TM. Additional funding for this work was provided by an award from the Flatley Discovery Lab to TM

Vectors with autonomy: what distinguishes animal-mediated nutrient transport from abiotic vectors?

Animal movements are important drivers of nutrient redistribution that can affect primary productivity and biodiversity across various spatial scales. Recent work indicates that incorporating these movements into ecosystem models can enhance our ability to predict the spatio-temporal distribution of nutrients. However, the role of animal behaviour in animal-mediated nutrient transport (i.e. active subsidies) remains under-explored. Here we review the current literature on active subsidies to show how the behaviour of active subsidy agents makes them both ecologically important and qualitatively distinct from abiotic processes (i.e. passive subsidies). We first propose that animal movement patterns can create similar ecological effects (i.e. press and pulse disturbances) in recipient ecosystems, which can be equal in magnitude to or greater than those of passive subsidies. We then highlight three key behavioural features distinguishing active subsidies. First, organisms can transport nutrients counter-directionally to abiotic forces and potential energy gradients (e.g. upstream). Second, unlike passive subsidies, organisms respond to the patterns of nutrients that they generate. Third, animal agents interact with each other. The latter two features can form positive- or negative-feedback loops, creating patterns in space or time that can reinforce nutrient hotspots in places of mass aggregations and/or create lasting impacts within ecosystems. Because human-driven changes can affect both the space-use of active subsidy species and their composition at both population (i.e. individual variation) and community levels (i.e. species interactions), predicting patterns in nutrient flows under future modified environmental conditions depends on understanding the behavioural mechanisms that underlie active subsidies and variation among agents' contributions. We conclude by advocating for the integration of animal behaviour, animal movement data, and individual variation into future conservation efforts in order to provide more accurate and realistic assessments of changing ecosystem function

An AAC-Enabled Internet: From User Requirements to Guidelines

Ensuring that WWW pages are accessible and usable for people with complex communication needs provides a particular challenge for WWW page designers. Despite advances in commercially available assistive technologies, people using augmentative and alternative communication (AAC) comment on continuing difficulty and frustration in physical access to technology and subsequent reliance on non-disabled partners (Clarke et al., 2001 and 2002). The EU WWAAC (World Wide Augmentative and Alternative Communication) project, which began in January 2001, has been engaged in a number of research and development activities in order to overcome some of these problems, including the: • Development of Internet applications, including an adapted Web browser, tailored to the needs of people who use AAC • Contribution to the development of Web accessibility guidelines • Development of a communication infrastructure and protocol to support symbol-based communication on the Web, based upon open-sourced concept coding • Development of a Dreamweaver extension to enable Web developers to symbol embellish their Web pages via the on-line concept coding database. This paper will concentrate on the first 2 activities to demonstrate how the design, development and evaluation of an adapted Web browser with people who use AAC will lead to more accessible and usable software. This work is also contributing to the development of WWW accessibility guidelines, which will feed into the work of the World Wide Web Consortium–Web Accessibility Initiative (W3C–WAI). It is important, however, to consider these activities in light of the concept coding stream of the work, which is briefly described below. Concept coding will facilitate the sharing of symbol-based content between different symbol users using different symbol language systems. It will also enable symbols to be converted into text and vice versa. This might mean, for example, that a person who uses AAC could open an Internet bank account by completing an on-line form using their own symbol system. The vision of concept coding is that instead of images and symbols having to be transferred from one computer to another, it is possible to share a unique code designating the meaning of the symbol needing to be transferred. In addition to efficiency in handling images used for communication purposes, this concept would also allow personalised or idiosyncratic symbols specific to one person to be used by them in Internet-based communication. An open source concept coding, in combination with more accessible and usable software, is the driving force behind the WWAAC project

Imaging the inside of thick structures using cosmic rays

The authors present here a new method to image reinforcement elements inside thick structures and the results of a demonstration measurement performed on a mock-up wall built at Los Alamos National Laboratory. The method, referred to as "multiple scattering muon radiography", relies on the use of cosmic-ray muons as probes. The work described in this article was performed to prove the viability of the technique as a means to image the interior of the dome of Florence Cathedral Santa Maria del Fiore, one of the UNESCO World Heritage sites and among the highest profile buildings in existence. Its result shows the effectiveness of the technique as a tool to radiograph thick structures and image denser object inside them

Usability evaluation of an eHealth intervention for family carers of individuals affected by psychosis: A mixed-method study

Background Existing research suggests that eHealth interventions targeting family carers of individuals with long-term illness offer a promising approach to care delivery. In particular, digital psychoeducational interventions with interactive psychosocial support are well-received with high rates of satisfaction and acceptability. However, development of such interventions for psychosis carers is lacking. We developed a multi-component eHealth intervention specifically for carers of individuals affected by psychosis, called COPe-support (Carers fOr People with Psychosis e-support). Objective Using mixed methods to evaluate usability, system heuristics and perceived acceptability, we conducted a usability study to establish the suitability of the intervention prototype for the target user group. Methods Twenty-three carers were recruited to the study and participated in a think-aloud test or a remote online trial of the intervention. Qualitative feedback, post-use System Usability Scale (SUS) scores, and real-world usage data collected from the tests were analysed. These were also supplemented with heuristic evaluation data provided by an independent eLearning technology expert. Results Participants evaluated the intervention content as useful and helpful, and indicated that the system had satisfactory usability with a mean SUS score of 73%, above the usability quality benchmark threshold. Study results identified some minor usability issues, which were corroborated with the eLearning expert’s heuristic evaluation findings. We used these results to refine the COPe-support intervention. Conclusions The usability study with end-users and service providers identified real-life usage and usability issues. The study results helped us refine COPe-support and its delivery strategy before its launch as part of a large-scale clinical trial

Inosine can increase DNA's susceptibility to photo-oxidation by a Ru(II) complex due to structural change in the minor groove

Key to the development of DNA-targeting phototherapeutic drugs is determining the interplay between the photoactivity of the drug and its binding preference for a target sequence. For the photo- oxidising lambda-[Ru(TAP)2(dppz)]2+ (Ʌ-1) complex bound to either d{T1C2G3G4C5G6C7C8G9A10}2 (G9) or d{TCGGCGCCIA}2 (I9), the X- ray crystal structures shows the dppz intercalated at the terminal T1C2;G9A10 step or T1C2;I9A10 step. Thus substitution of the G9 nucleobase by inosine does not affect intercalation in the solid state although with I9 the dppz is more deeply inserted. In solution it is found that the extent of guanine photo-oxidation, and the rate of back electron transfer, as determined by ps and ns time-resolved infrared and transient visible absorption spectroscopy, is enhanced in I9, despite it containing the less oxidisable inosine. This is attributed to the nature of the binding in the minor groove due to the absence of an NH2 group. Similar behaviour and the same binding site in the crystal.are found for d{TTGGCGCCAA}2 (A9), In solution we propose that intercalation occurs at the C2G3;C8I9 or T2G3;C8A9 steps, respectively, with G3 the likely target for photo-oxidation. This demonstrates how changes in the minor groove (in this case removal of an NH2 group) can facilitate binding of Ru(II)dppz complexes and hence influence any sensitised reactions occurring at these sites. No similar enhancement of photooxidation on binding to I9 is found for the delta enantiomer

Large-scale synchrony of gap dynamics and the distribution of understory tree species in maple-beech forests

Large-scale synchronous variations in community dynamics are well documented for a vast array of organisms, but are considerably less understood for forest trees. Because of temporal variations in canopy gap dynamics, forest communities—even old-growth ones—are never at equilibrium at the stand scale. This paucity of equilibrium may also be true at the regional scale. Our objectives were to determine (1) if nonequilibrium dynamics caused by temporal variations in the formation of canopy gaps are regionally synchronized, and (2) if spatiotemporal variations in canopy gap formation aVect the relative abundance of tree species in the understory. We examined these questions by analyzing variations in the suppression and release history of Acer saccharum Marsh. and Fagus grandifolia Ehrh. from 481 growth series of understory saplings taken from 34 mature stands. We observed that (1) the proportion of stems in release as a function of time exhibited a U-shaped pattern over the last 35 years, with the lowest levels occurring during 1975–1985, and that (2) the response to this in terms of species composition was that A. saccharum became more abundant at sites that had the highest proportion of stems in release during 1975–1985. We concluded that the understory dynamics, typically thought of as a stand-scale process, may be regionally synchronized