Variation at the vernalisation genes Vrn-H1 and Vrn-H2 determines growth and yield stability in barley (Hordeum vulgare) grown under dryland conditions in Syria

Key message

Spring growth in barley controlled by natural variation at Vrn-H1 and Vrn-H2 improved yield stability in marginal Syrian environments.

Abstract

The objective of the present study was to identify QTL influencing agronomic performance in rain-fed Mediterranean environments in a recombinant inbred line (RIL) population, ARKE derived from the Syrian barley landrace, Arta and the Australian feed cultivar, Keel. The population was field tested for agronomic performance at two locations in Syria for 4 years with two sowing dates, in autumn and winter. Genotypic variability in yield of the RIL population was mainly affected by year-to-year variation presumably caused by inter-annual differences in rainfall distribution. The spring growth habit and early flowering inherited from the Australian cultivar Keel increased plant height and biomass and improved yield stability in Syrian environments. QTL for yield and biomass coincided with the map location of flowering time genes, in particular the vernalisation genes Vrn-H1 and Vrn-H2. In marginal environments with terminal drought, the Vrn-H1 allele inherited from Keel improved final biomass and yield. Under changing climate conditions, such as shorter winters, reduced rainfall, and early summer drought, spring barley might thus outperform the traditional vernalisation-sensitive Syrian landraces. We present the ARKE population as a valuable genetic resource to further elucidate the genetics of drought adaptation of barley in the field.     

Large-scale patterns in morphological diversity and species assemblages in Neotropical Triatominae (Heteroptera: Reduviidae)

We analysed the spatial variation in morphological diversity (MDiv) and species richness (SR) for 91 species of Neotropical Triatominae to determine the ecological relationships between SR and MDiv and to explore the roles that climate, productivity, environmental heterogeneity and the presence of biomes and rivers may play in the structuring of species assemblages. For each 110 km x 110 km-cell on a grid map of America, we determined the number of species (SR) and estimated the mean Gower index (MDiv) based on 12 morphological attributes. We performed bootstrapping analyses of species assemblages to identify whether those assemblages were more similar or dissimilar in their morphology than expected by chance. We applied a multi-model selection procedure and spatial explicit analyses to account for the association of diversity-environment relationships. MDiv and SR both showed a latitudinal gradient, although each peaked at different locations and were thus not strictly spatially congruent. SR decreased with temperature variability and MDiv increased with mean temperature, suggesting a predominant role for ambient energy in determining Triatominae diversity. Species that were more similar than expected by chance co-occurred near the limits of the Triatominae distribution in association with changes in environmental variables. Environmental filtering may underlie the structuring of species assemblages near their distributional limits.     

Fast Two-Dimensional Bubble Analysis of Biopolymer Filamentous Networks Pore Size from Confocal Microscopy Thin Data Stacks

The average pore size ξ₀ of filamentous networks assembled from biological macromolecules is one of the most important physical parameters affecting their biological functions. Modern optical methods, such as confocal microscopy, can noninvasively image such networks, but extracting a quantitative estimate of ξ₀ is a nontrivial task. We present here a fast and simple method based on a two-dimensional bubble approach, which works by analyzing one by one the (thresholded) images of a series of three-dimensional thin data stacks. No skeletonization or reconstruction of the full geometry of the entire network is required. The method was validated by using many isotropic in silico generated networks of different structures, morphologies, and concentrations. For each type of network, the method provides accurate estimates (a few percent) of the average and the standard deviation of the three-dimensional distribution of the pore sizes, defined as the diameters of the largest spheres that can be fit into the pore zones of the entire gel volume. When applied to the analysis of real confocal microscopy images taken on fibrin gels, the method provides an estimate of ξ₀ consistent with results from elastic light scattering data.     

Seasonal and environmental influences on the calling behaviour of Eurasian Scops Owls

Capsule Spontaneous calls and replies to playback of Scops Owls were significantly more frequent during the breeding period, when paired birds defend territories. The probability of spontaneous calls varied with moon phase, with a peak occurring during nights with a full moon. In some cases, during the winter, Scops Owls responded to playback calls of Little Owls, thus suggesting possible intra-guild competition between these species.     

Design of a novel LOX-1 receptor antagonist mimicking the natural substrate

The lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), the major receptor for oxidized low-density lipoprotein (ox-LDL) in endothelial cells, is overexpressed in atherosclerotic lesions. LOX-1 specific inhibitors, urgently necessary to reduce the rate of atherosclerotic and inflammation processes, are not yet available. We have designed and synthesized a new modified oxidized phospholipid, named PLAzPC, which plays to small scale the ligand-receptor recognition scheme. Molecular docking simulations confirm that PLAzPC disables the hydrophobic component of the ox-LDL recognition domain and allows the interaction of the l-lysine backbone charged groups with the solvent and with the charged/polar residues located around the edges of the LOX-1 hydrophobic tunnel. Binding assays, in a cell model system expressing human LOX-1 receptors, confirm that PLAzPC markedly inhibits ox-LDL binding to LOX-1 with higher efficacy compared to previously identified inhibitors.     

Substrate-induced conformational changes of the mitochondrial oxoglutarate carrier: a spectroscopic and molecular modelling study

The structural and dynamic properties of the oxoglutarate carrier were investigated by introducing a single tryptophan in the Trp-devoid carrier in position 184, 190 or 199 and by monitoring the fluorescence spectra in the presence and absence of the substrate oxoglutarate. In the absence of substrate, the emission maxima of Arg190Trp, Cys184Trp and Leu199Trp are centered at 342, 345 and 348 nm, respectively, indicating that these residues have an increasing degree of solvent exposure. The emission intensity of the Arg190Trp and Cys184Trp mutants is higher than that of Leu199Trp. Addition of substrate increases the emission intensity of Leu199Trp, but not that of Cys184Trp and Arg190Trp. A 3D model of the oxoglutarate carrier was built using the structure of the ADP/ATP carrier as a template and was validated with the experimental results available in the literature. The model identifies Lys122 as the most likely candidate for the quenching of Trp199. Consistently, the double mutant Lys122Ala-Leu199Trp exhibits a higher emission intensity than Leu199Trp and does not display further fluorescence enhancement in response to substrate addition. Substitution of Lys122 with Cys and evaluation of its reactivity with a sulphydryl reagent in the presence and absence of substrate confirms that residue 122 is masked by the substrate, likely through a substrate-induced conformational change.     

Retinoic Acid Specifically Enhances Embryonic Stem Cell Metastate Marked by Zscan4

Pluripotency confers Embryonic Stem Cells (ESCs) the ability to differentiate in ectoderm, endoderm, and mesoderm derivatives, producing the majority of cell types. Although the majority of ESCs divide without losing pluripotency, it has become evident that ESCs culture consists of multiple cell populations with different degrees of potency that are spontaneously induced in regular ESC culture conditions. Zscan4, a key pluripotency factor, marks ESC subpopulation that is referred to as high-level of pluripotency metastate. Here, we report that in ESC cultures treated with retinoic acid (RA), Zscan4 ESCs metastate is strongly enhanced. In particular, we found that induction of Zscan4 metastate is mediated via RA receptors (RAR-alpha, RAR-beta, and RAR-gamma), and it is dependent on phosphoinositide-3-kinase (PI3K) signaling. Remarkably, Zscan4 metastate induced by RA lacks canonical pluripotency genes Oct3/4 and Nanog but retained both self-renewal and pluripotency capabilities. Finally we demonstrated that the conditional ablation of Zscan4 subpopulation is dispensable for both endoderm and mesoderm but is required for ectoderm lineage. In conclusion, our research provides new insights about the role of RA signaling during ESCs high pluripotency metastate fluctuation.