Morphological Trait Evolution in Solanum (Solanaceae): Evolutionary Lability of Key Taxonomic Characters

Solanum is one of the world\u27s largest and economically most important plant genera, including 1245 currently accepted species and several major and minor crops (e.g., tomato, potato, brinjal eggplant, scarlet eggplant, Gboma eggplant, lulo, and pepino). Here we provide an overview of the evolution of 25 key morphological traits for the major and minor clades of this giant genus based on stochastic mapping using a well-sampled recently published phylogeny of Solanum. The most evolutionarily labile traits (showing \u3e100 transitions across the genus) relate to plant structure (growth form and sympodial unit structure), herbivore defence (glandular trichomes), pollination (corolla shape and colour), and dispersal (fruit colour). Ten further traits show evolutionary lability with 50–100 transitions across the genus (e.g., specialised underground organs, trichome structure, leaf type, inflorescence position and branching, stamen heteromorphism). Our results reveal a number of highly convergent traits in Solanum, including tubers, rhizomes, simple leaves, yellow corollas, heteromorphic anthers, dioecy, and dry fruits, and some unexpected pathways of trait evolution that could be explored in future studies. We show that informally named clades of Solanum can be morphologically defined by trait combinations providing a tool for identification and enabling predictive phylogenetic placement of unsampled species

Switching between different vortex states in 2-dimensional easy-plane magnets due to an ac magnetic field

Using a discrete model of 2-dimensional easy-plane classical ferromagnets, we propose that a rotating magnetic field in the easy plane can switch a vortex from one polarization to the opposite one if the amplitude exceeds a threshold value, but the backward process does not occur. Such switches are indeed observed in computer simulations.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let

Phylogenomic discordance suggests polytomies along the backbone of the large genus Solanum

Premise Evolutionary studies require solid phylogenetic frameworks, but increased volumes of phylogenomic data have revealed incongruent topologies among gene trees in many organisms both between and within genomes. Some of these incongruences indicate polytomies that may remain impossible to resolve. Here we investigate the degree of gene-tree discordance in Solanum, one of the largest flowering plant genera that includes the cultivated potato, tomato, and eggplant, as well as 24 minor crop plants. Methods A densely sampled species-level phylogeny of Solanum is built using unpublished and publicly available Sanger sequences comprising 60% of all accepted species (742 spp.) and nine regions (ITS, waxy, and seven plastid markers). The robustness of this topology is tested by examining a full plastome dataset with 140 species and a nuclear target-capture dataset with 39 species of Solanum (Angiosperms353 probe set). Results While the taxonomic framework of Solanum remained stable, gene tree conflicts and discordance between phylogenetic trees generated from the target-capture and plastome datasets were observed. The latter correspond to regions with short internodal branches, and network analysis and polytomy tests suggest the backbone is composed of three polytomies found at different evolutionary depths. The strongest area of discordance, near the crown node of Solanum, could potentially represent a hard polytomy. Conclusions We argue that incomplete lineage sorting due to rapid diversification is the most likely cause for these polytomies, and that embracing the uncertainty that underlies them is crucial to understand the evolution of large and rapidly radiating lineages.Peer reviewe

Yellow fever virus NS2B/NS3 protease: Hydrolytic Properties and Substrate Specificity

Here we report the hydrolytic behavior of recombinant YFV NS2B/NS3 protease against FRET substrates mimicking the prime and non-prime region of the natural polyprotein cleavage sites. While the P2-P'1 motif is the main factor associated with the catalytic efficiency of Dengue (DV) and West Nile Virus (WNV) protease, we show that the k(cat)/K-m of YFV NS2B/NS3 varied by more than two orders of magnitude, despite the presence of the same motif in all natural substrates. the catalytic significance of this homogeneity - a unique feature among worldwide prominent flavivirus - was kinetically analyzed using FRET peptides containing all possible combinations of two and three basic amino acids in tandem, and Arg and Lys residues produced distinct effects on k(cat)/K-m. the parallel of our data with those obtained in vivo by Chambers et al. (1991) restrains the idea that these sites co-evolved with the NS2B/NS3 protease to promote highly efficient hydrolysis and supports the notion that secondary substrate interaction distant from cleavage sites are the main factor associated with the different hydrolytic rates on YFV NS2B-NS3pro natural substrates. (C) 2011 Elsevier Inc. All rights reserved

Amino acid substitutions in the DNA-binding domain of the human androgen receptor are a frequei.t cause of receptor binding positive androgen resistance

Snake venom metalloproteinases (SVMPs) belonging to P-I class are able to hydrolyze extracellular matrix proteins and coagulation factors triggering local and systemic reactions by multiple molecular mechanisms that are not fully understood. BmooMP alpha-I, a P-I class SMVP from Bothrops moojeni venom, was active upon neuro- and vaso-active peptides including angiotensin I, bradykinin, neurotensin, oxytocin and substance P. Interestingly, BmooMPa-I showed a strong bias towards hydrolysis after proline residues, which is unusual for most of characterized peptidases. Moreover, the enzyme showed kininogenase activity similar to that observed in plasma and cells by kallikrein. FRET peptide assays indicated a relative promiscuity at its S-2-S '(2) subsites, with proline determining the scissile bond. This unusual post-proline cleaving activity was confirmed by the efficient hydrolysis of the synthetic combinatorial library MCA-GXXPXXQ-EDDnp, described as resistant for canonical peptidases, only after Pro residues. Structural analysis of the tripeptide LPL complexed with BmooMP alpha-I, generated by molecular dynamics simulations, assisted in defining the subsites and provided the structural basis for subsite preferences such as the restriction of basic residues at the S-2 subsite due to repulsive electrostatic effects and the steric impediment for large aliphatic or aromatic side chains at the Si subsite. These new functional and structural findings provided a further understanding of the molecular mechanisms governing the physiological effects of this important class of enzymes in envenomation process. (c) 2014 Elsevier B.V. All rights reserved