Setting sub-organellar sights: accurate targeting of multi-transmembrane-domain proteins to specific chloroplast membranes

Engineering novel chloroplast functions requires an understanding of how to accurately target proteins to specific chloroplast sub-compartments. This is particularly difficult in the case of membrane proteins where localization can be confounded by multiple membrane types. In an elegant study, Singhal and Fernandez (2017) have now provided greater insight into this challenge by dissecting out the signals that control differential targeting of two related proteins to specific chloroplast membranes. Further development of this information should inform attempts to direct engineered proteins to specific sub-organellar membranes, bringing about desired phenotypic changes

Polygenic adaptation of rosette growth in Arabidopsis thaliana

Altres ajuts: CERCA Programme/Generalitat de CatalunyaThe rate at which plants grow is a major functional trait in plant ecology. However, little is known about its evolution in natural populations. Here, we investigate evolutionary and environmental factors shaping variation in the growth rate of Arabidopsis thaliana. We used plant diameter as a proxy to monitor plant growth over time in environments that mimicked latitudinal differences in the intensity of natural light radiation, across a set of 278 genotypes sampled within four broad regions, including an outgroup set of genotypes from China. A field experiment conducted under natural conditions confirmed the ecological relevance of the observed variation. All genotypes markedly expanded their rosette diameter when the light supply was decreased, demonstrating that environmental plasticity is a predominant source of variation to adapt plant size to prevailing light conditions. Yet, we detected significant levels of genetic variation both in growth rate and growth plasticity. Genome-wide association studies revealed that only 2 single nucleotide polymorphisms associate with genetic variation for growth above Bonferroni confidence levels. However, marginally associated variants were significantly enriched among genes with an annotated role in growth and stress reactions. Polygenic scores computed from marginally associated variants confirmed the polygenic basis of growth variation. For both light regimes, phenotypic divergence between the most distantly related population (China) and the various regions in Europe is smaller than the variation observed within Europe, indicating that the evolution of growth rate is likely to be constrained by stabilizing selection. We observed that Spanish genotypes, however, reach a significantly larger size than Northern European genotypes. Tests of adaptive divergence and analysis of the individual burden of deleterious mutations reveal that adaptive processes have played a more important role in shaping regional differences in rosette growth than maladaptive evolution. The rate at which plants grow is a major functional trait in plant ecology. However, little is known about its genetic variation in natural populations. Here, we investigate genetic and environmental factors shaping variation in the growth rate of Arabidopsis thaliana and ask whether genetic variation in plant growth contributes to adaptation to local environmental conditions. We grew plants under two light regimes that mimic latitudinal differences in the intensity of natural light radiation, and measured plant diameter as it grew over time. When the light supply was decreased, plant diameter grew more slowly but reached a markedly larger final size, confirming that plants can adjust their growth to prevailing light conditions. Yet, we also detected significant levels of genetic variation both in growth rate and in how the growth dynamics is adjusted to the light conditions. We show that this variation is encoded by many loci of small effect that are hard to locate in the genome but overall significantly enriched among genes associated with growth and stress reactions. We further observe that Spanish genotypes tended to reach, on average, a significantly larger rosette size than Northern European genotypes. Tests of adaptive divergence indicate that these differences may reflect adaptation to local environmental conditions

Incorporation of Functional Rubisco Activases into Engineered Carboxysomes to Enhance Carbon Fixation.

The carboxysome is a versatile paradigm of prokaryotic organelles and is a proteinaceous self-assembling microcompartment that plays essential roles in carbon fixation in all cyanobacteria and some chemoautotrophs. The carboxysome encapsulates the central CO2-fixing enzyme, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), using a polyhedral protein shell that is selectively permeable to specific metabolites in favor of Rubisco carboxylation. There is tremendous interest in repurposing carboxysomes to boost carbon fixation in heterologous organisms. Here, we develop the design and engineering of α-carboxysomes by coexpressing the Rubisco activase components CbbQ and CbbO with α-carboxysomes in Escherichia coli. Our results show that CbbQ and CbbO could assemble into the reconstituted α-carboxysome as intrinsic components. Incorporation of both CbbQ and CbbO within the carboxysome promotes activation of Rubisco and enhances the CO2-fixation activities of recombinant carboxysomes. We also show that the structural composition of these carboxysomes could be modified in different expression systems, representing the plasticity of the carboxysome architecture. In translational terms, our study informs strategies for engineering and modulating carboxysomes in diverse biotechnological applications

The Lantern Vol. 50, No. 1, Fall 1983

• Reaching for My Dream • All Hail • Appreciation • Egotism • Me (Dedicated to...) • Butterfly • Balloon and Bird • Never Again • Mother • The Deaf Ears • Healing • Distress • Silent Death • Whose Reality Is It Anyway? • To Helen • Luna Llena y Soledad • Saved • Jenny • Slope • A Poem in C Minor • A Birth of Proficiency • The Traveling Man • Competing With the Sea • To R. • The Child • And Besides • An Actress\u27 Demise • A Loving Tribute to Francis • Rapunzel • Memorieshttps://digitalcommons.ursinus.edu/lantern/1123/thumbnail.jp

Value-Driven Analysis of New Paradigms in Space Architectures: An Ilities-Based Approach

Current commercial, civil, and military space architecture designs perform exquisitely and reliably. However, today’s architecture paradigms are also characterized by expensive launches, large and expensive high-performance spacecraft, long development cycles, and wide variations in ground architectures. While current assets provide high-quality services, and future assets are slated to improve performance within the same design frameworks, proposed future architectures may not be capitalizing on technology improvements, system innovations, or policy alternatives explored during the last two decades. This paper identifies five “trends” along which space architectures may develop, aimed at granting systems several “ilities,” such as resiliency, robustness, flexibility, scalability, and affordability. The trends examined include: commercialization of space, significant reductions in launch costs and the development of hybrid or reusable launch systems, development of on-orbit infrastructure and servicing, aggregation or disaggregation of orbital assets, and the automation and standardization of ground architectures. Further refinement of these key technological and system trends could result in major paradigm shifts in the development and fielding of space operations as well as lead to space architecture designs in the future that are radically different from those today. Within the framework of systems engineering ilities and risk management, this paper reviews current literature surrounding these new change trends and justifies their potential to cause significant paradigm shifts. By examining the work and research conducted so far through an ilities-based approach, systems engineers can more fully appreciate the value being offered by these trends

A cross-scale analysis to understand and quantify the effects of photosynthetic enhancement on crop growth and yield across environments

Abstract Photosynthetic manipulation provides new opportunities for enhancing crop yield. However, understanding and quantifying the importance of individual and multiple manipulations on the seasonal biomass growth and yield performance of target crops across variable production environments is limited. Using a state-of-the-art cross-scale model in the APSIM platform we predicted the impact of altering photosynthesis on the enzyme-limited (Ac) and electron transport-limited (Aj) rates, seasonal dynamics in canopy photosynthesis, biomass growth, and yield formation via large multiyear-by-location crop growth simulations. A broad list of promising strategies to improve photosynthesis for C3 wheat and C4 sorghum were simulated. In the top decile of seasonal outcomes, yield gains were predicted to be modest, ranging between 0% and 8%, depending on the manipulation and crop type. We report how photosynthetic enhancement can affect the timing and severity of water and nitrogen stress on the growing crop, resulting in nonintuitive seasonal crop dynamics and yield outcomes. We predicted that strategies enhancing Ac alone generate more consistent but smaller yield gains across all water and nitrogen environments, Aj enhancement alone generates larger gains but is undesirable in more marginal environments. Large increases in both Ac and Aj generate the highest gains across all environments. Yield outcomes of the tested manipulation strategies were predicted and compared for realistic Australian wheat and sorghum production. This study uniquely unpacks complex cross-scale interactions between photosynthesis and seasonal crop dynamics and improves understanding and quantification of the potential impact of photosynthesis traits (or lack of it) for crop improvement research

Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson