Significance of root hairs for plant performance under contrasting field conditions and water deficit

Background and Aims Previous laboratory studies have suggested selection for root hair traits in future crop breeding to improve resource use efficiency and stress tolerance. However, data on the interplay between root hairs and open-field systems, under contrasting soils and climate conditions, are limited. As such, this study aims to experimentally elucidate some of the impacts that root hairs have on plant performance on a field scale. Methods A field experiment was set up in Scotland for two consecutive years, under contrasting climate conditions and different soil textures (i.e. clay loam vs. sandy loam). Five barley (Hordeum vulgare) genotypes exhibiting variation in root hair length and density were used in the study. Root hair length, density and rhizosheath weight were measured at several growth stages, as well as shoot biomass, plant water status, shoot phosphorus (P) accumulation and grain yield. Key Results Measurements of root hair density, length and its correlation with rhizosheath weight highlighted trait robustness in the field under variable environmental conditions, although significant variations were found between soil textures as the growing season progressed. Root hairs did not confer a notable advantage to barley under optimal conditions, but under soil water deficit root hairs enhanced plant water status and stress tolerance resulting in a less negative leaf water potential and lower leaf abscisic acid concentration, while promoting shoot P accumulation. Furthermore, the presence of root hairs did not decrease yield under optimal conditions, while root hairs enhanced yield stability under drought. Conclusions Selecting for beneficial root hair traits can enhance yield stability without diminishing yield potential, overcoming the breeder’s dilemma of trying to simultaneously enhance both productivity and resilience. Therefore, the maintenance or enhancement of root hairs can represent a key trait for breeding the next generation of crops for improved drought tolerance in relation to climate change

Theoretical design of stable hydride clusters: isoelectronic transformation in the EnAl4−nH7+n − series

Indexación: Web of Science; Scopus.New stable hydrogen-rich metallic hydrides are designed by systematic transformations of the stable known Al4H7 − species, carried out by successive isoelectronic substitutions of one aluminum atom by one E-H unit at a time (where E = Be, Mg, Ca, Sr and Ba atoms). Searches on the potential energy surfaces (PESs) of EAl3H8 −, E2Al2H9 −, E3AlH10 − and E4H11 − systems indicate that structural analogues of Al4H7 − become higher energy isomers as the number of E-H units increases. The electronic descriptors: Vertical Electron Affinity (VEA), Vertical Ionization Potential (VIP) and the HOMO-LUMO gap, suggest that the systems composed of EAl3H8 −, E2Al2H9 −, E3AlH10 −, with E = Be and Mg, would be the most stable clusters. Additionally, for a practical application, we found that the Be-H and Mg-H substitutions increase the hydrogen weight percentage (wt%) in the clusters, compared with the isoelectronic analogue Al4H7 −. The good capacity of beryllium and magnesium to stabilize the extra hydrogen atoms is supported by the increment of the bridge-like E-H-Al, 3center-2electron chemical bonds. Finally, explorations on the PESs of the neutral species (using Na+ as counterion) indicate that the NaBe2Al2H9, NaBe3AlH10 and NaMg3AlH10 minimum-energy structures retain the original geometric shapes of the anionic systems. This analysis supports the potential use of these species as building blocks for cluster-assembled hydrides in the gas phase.http://pubs.rsc.org/en/Content/ArticleLanding/2017/RA/C7RA01422H#!divAbstrac

Revision of the Astyanax orthodus species-group (Teleostei: Characidae) with descriptions of three new species

The Astyanax orthodus species-group includes nine species: Astyanax boliviensis sp. nov., A. bopiensis nom. nov., A. embera sp. nov., A. gandhiae sp. nov., A. moorii comb. nov., A. orthodus, A. superbus, A. villwocki and A. yariguies comb. nov. The group is diagnosed by the presence of a series of pinnate-shaped marks (chevrons) located along the lateral midline, which extends from the humeral region to the caudal peduncle. Astyanax bopiensis nom. nov. is proposed as a substitute name for Astyanacinus multidens, which, along with Astyanax yariguies comb. nov., we reassign to Astyanax.We also propose the synonymy of Astyanacinus with Astyanax. The members of the A. orthodus species-group are distributed in northwestern South America, occurring in the Patia River drainage (A. embera sp. nov.) of the Pacific coast of Colombia, the Atrato River Basin (A. orthodus), the Magdalena River Basin (A. yariguies comb. nov.) of Caribbean Colombia, streams of the southern flank of the Andes of the Orinoco Basin in Venezuela (A. superbus), in the upper Amazon River Basin of Colombia, Ecuador and Peru (A. villwocki, A. gandhiae sp. nov.), from the upper Paraguay River (A. moorii comb. nov.), the Madidi and Mamore Rivers, Bolivia (A. boliviensis sp. nov. and A. bopiensis nom. nov.). All species currently included in Astyanacinus are reassigned to the Astyanax orthodus species-group

A stretch of negatively charged amino acids of linker for activation of T-cell adaptor has a dual role in T-cell antigen receptor intracellular signaling

The adaptor protein linker for activation of T cells (LAT) has an essential role transducing activatory intracellular signals coming from the TCR/CD3 complex. Previous reports have shown that upon T-cell activation, LAT interacts with the tyrosine kinase Lck, leading to the inhibition of its kinase activity. LAT–Lck interaction seemed to depend on a stretch of negatively charged amino acids in LAT. Here, we have substituted this segment of LAT between amino acids 113 and 126 with a non-charged segment and expressed the mutant LAT (LAT-NIL) in J.CaM2 cells in order to analyze TCR signaling. Substitution of this segment in LAT prevented the activation-induced interaction with Lck. Moreover, cells expressing this mutant form of LAT showed a statistically significant increase of proximal intracellular signals such as phosphorylation of LAT in tyrosine residues 171 and 191, and also enhanced ZAP70 phosphorylation approaching borderline statistical significance (p = 0.051). Nevertheless, downstream signals such as Ca2+ influx or MAPK pathways were partially inhibited. Overall, our data reveal that LAT–Lck interaction constitutes a key element regulating proximal intracellular signals coming from the TCR/CD3 comple

Sequence conservation and antibody cross-recognition of the clade B HIV-1 Tat protein vaccine candidate in HIV-1-infected Italian, Ugandan and Soth African individuals

We determined immune cross-recognition and the degree of Tat conservation in patients infected by local human immunodeficiency virus (HIV) type 1 strains. The data indicated a similar prevalence of total and epitope-specific anti-Tat IgG in 578 serum samples from HIV-infected Italian (n=302), Ugandan (n=139), and South African (n=137) subjects, using the same B clade Tat protein that is being used in vaccine trials. In particular, anti-Tat antibodies were detected in 13.2%, 10.8%, and 13.9% of HIV-1-infected individuals from Italy, Uganda, and South Africa, respectively. Sequence analysis results indicated a high similarity of Tat from the different circulating viruses with BH-10 Tat, particularly in the 1-58 amino acid region, which contains most of the immunogenic epitopes. These data indicate an effective cross-recognition of a B-clade laboratory strain-derived Tat protein vaccine by individuals infected with different local viruses, owing to the high similarity of Tat epitopes