Web building and silk properties functionally covary among species of wolf spider

Although phylogenetic studies have shown covariation between the properties of spider major ampullate (MA) silk and web building, both spider webs and silks are highly plastic so we cannot be sure whether these traits functionally covary or just vary across environments that the spiders occupy. As MaSp2‐like proteins provide MA silk with greater extensibility, their presence is considered necessary for spider webs to effectively capture prey. Wolf spiders (Lycosidae) are predominantly non‐web building, but a select few species build webs. We accordingly collected MA silk from two web‐building and six non‐web‐building species found in semirural ecosystems in Uruguay to test whether the presence of MaSp2‐like proteins (indicated by amino acid composition, silk mechanical properties and silk nanostructures) was associated with web building across the group. The web‐building and non‐web‐building species were from disparate subfamilies so we estimated a genetic phylogeny to perform appropriate comparisons. For all of the properties measured, we found differences between web‐building and non‐web‐building species. A phylogenetic regression model confirmed that web building and not phylogenetic inertia influences silk properties. Our study definitively showed an ecological influence over spider silk properties. We expect that the presence of the MaSp2‐like proteins and the subsequent nanostructures improves the mechanical performance of silks within the webs. Our study furthers our understanding of spider web and silk co‐evolution and the ecological implications of spider silk properties.     

Foraging Strategies of Artisanal Fishers in a Brazilian Reservoir

Ecological models derived from Optimal Foraging Theory have been used to understand the decision-making processes and optimization of artisanal fisheries. However, many studies do not consider the influence of fishing techniques or seasonality on foraging strategies. We analyzed the optimization strategies and decision-making processes of the fishers at a Brazilian reservoir. Data were collected through interviews and questionnaires involving 65 artisanal fishers, and daily catches were monitored in July/2015 and January/2016. Fishing techniques and seasonality influenced the fishers’ behavior. The fishery activities monitored here were partially or totally consistent with the predictions of the Central-Place Foraging model, but due to the complexity of these activities, other factors also influenced the decision-making of individual fishers. Furthermore, the adoption of strategies that involve “non-ideal” behaviors may be advantageous for the fishers in the context of their individual necessities.     

Mismatches between habitat preferences and risk avoidance for birds in intensive Mediterranean farmland

Land use intensification may create habitats that organisms perceive as suitable, but where reproduction or survival is insufficient to maintain self-sustaining populations. Such conditions may qualify as ecological traps, but their existence is often hard to prove. Here, we provide a practical framework to evaluate a potential ecological trap resulting from mismatch between habitat preferences and predation risk, focusing on ground-nesting farmland birds of conservation concern. The framework is based on species-specific associations with safe or unsafe habitat types (i.e. field and landscape types with high or low nest survival), and the occurrence of risk avoidance (i.e. negative responses to predator abundances or to nest failure rates after controlling for habitat effects). Bird densities were far more influenced by field characteristics than landscape context. Corn bunting and fan-tailed warbler were associated with tall swards (safe habitats), and did not show risk avoidance. Tawny pipit and and Galerida larks were associated with short swards (unsafe habitats), with the former avoiding fields with high nest predation rates, and the later avoiding high mongoose abundances. Short-toed lark was associated with fields with short swards and low nest trampling rates. Results suggest that short-toed lark may be the most vulnerable to ecological trapping, because it nests on unsafe habitats and did not show predation risk avoidance. Our approach provides a practical first step to infer vulnerability to a potential ecological trap, though further research is needed to confirm this effect. Management actions increasing nest survival in short sward fields will likely favour grassland bird conservation in intensive Mediterranean farmland.     

Identification of new promising <Emphasis Type="Italic">Plasmodium falciparum</Emphasis> superoxide dismutase allosteric inhibitors through hierarchical pharmacophore-based virtual screening and molecular dynamics

Malaria is the world’s most widespread protozoan infection, being responsible for more than 445,000 annual deaths. Among the malaria parasites, Plasmodium falciparum is the most prevalent and lethal. In this context, the search for new antimalarial drugs is urgently needed. P. falciparum superoxide dismutase (PfSOD) is an important enzyme involved in the defense mechanism against oxidative stress. The goal of this study was to identify through hierarchical screening on pharmacophore models and molecular dynamics (MD), promising allosteric PfSOD inhibitors that do not show structural requirements for human inhibition. MD simulations of 1000 ps were performed on PfSOD using GROMACS 5.1.2. For this, the AMBER99SB-ILDN force field was adapted to describe the metal-containing system. The simulations indicated stability in the developed system. Therefore, a covariance matrix was generated, in which it was possible to identify residues with correlated and anticorrelated movements with the active site. These results were associated with the results found in the predictor of allosteric sites, AlloSitePro, which affirmed the ability of these residues to delimit an allosteric site. Then, after successive filtering of the Sigma-Aldrich® compounds database for HsSOD1 and PfSOD pharmacophores, 152 compounds were selected, also obeying Lipinski’s rule of 5. Further filtering of those compounds based on molecular docking results, toxicity essays, availability, and price filtering led to the selection of a best compound, which was then submitted to MD simulations of 20,000 ps on the allosteric site. The study concludes that the ZINC00626080 compound could be assayed against SODs.

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Graphical Abstract Plasmodium falciparum superoxide dismutase

     

Pharmacophore modeling,docking and molecular dynamics to identify <Emphasis Type="Italic">Leishmania major</Emphasis> farnesyl pyrophosphate synthase inhibitors

Leishmaniasis is caused by protozoa of the genus Leishmania spp. and is considered the second most important protozoa in the world due to the number of cases and mortality. Despite its importance in terms of public health, the treatment of patients is limited and has mostly low levels of efficacy and safety. Farnesyl pyrophosphate synthase (FPPS) acts in the early stages of isoprenoid synthesis, and is important for maintaining the integrity of the lipid bilayer of the parasite that causes the disease. The aim of this work was to identify one potential inhibitor of the FPPS of Leishmania major through virtual screening by pharmacophore modeling and docking. A total of 85,000 compounds from a natural products database (ZINC¹⁵) was submitted for virtual hierarchical screening, and the top ranked molecule in both methods was analyzed by intermolecular interaction profile and 20 ns molecular dynamics simulations. These results showed a promising compound from natural products that mimic the major interactions present in the substrate/inhibitor.     

A new species of <Emphasis Type="Italic">Isospora</Emphasis> Schneider, 1881 (Apicomplexa: Eimeriidae) from the twist-necked turtle <Emphasis Type="Italic">Platemys platycephala</Emphasis> (Schneider) (Testudines: Chelidae) in Brazil

A new coccidian species of the genus Isospora Schneider 1881 (Apicomplexa, Eimeriidae) is reported from a single specimen of chelid turtle, Platemys platycephala (Schneider, 1792), obtained in a flooded area of the Amazonian municipality of Altamira, in Pará State, northern Brazil. The oöcysts of Isospora platemysi n. sp. are subspheroidal, 19.0–24.0 × 22.5–18.5 (22.6 × 20.8) µm in size [length/width ratio 1.0–1.1 (1.1)], with a colourless wall, 1.0–1.9 (1.4) wide, with two smooth layers; polar granule is present, oöcyst residuum and micropyle are both absent. The sporocyst is ovoidal, 10.0–12.1 × 8.0–10.0 (11.0 × 9.1) µm [length/width ratio 1.1–1.3 (1.2), with a knob-like Stieda body. Sub-Stieda body is present, rounded irregular-trapezoidal; para-Stieda body is absent. Sporocyst residuum is dispersed and composed of granules of differing sizes. This is only the fifth record of Isospora in chelonians, and the first report of a coccidian parasite of the genus Platemys.