Nonlinear variation in clinging performance with surface roughness in geckos

Understanding the challenges faced by organisms moving within their environment is essential to comprehending the evolution of locomotor morphology and habitat use. Geckos have developed adhesive toe pads that enable exploitation of a wide range of microhabitats. These toe pads, and their adhesive mechanisms, have typically been studied using a range of artificial substrates, usually significantly smoother than those available in nature. Although these studies have been fundamental in understanding the mechanisms of attachment in geckos, it is unclear whether gecko attachment simply gradually declines with increased roughness as some researchers have suggested, or whether the interaction between the gekkotan adhesive system and surface roughness produces nonlinear relationships. To understand ecological challenges faced in their natural habitats, it is essential to use test surfaces that are more like surfaces used by geckos in nature. We tested gecko shear force (i.e., frictional force) generation as a measure of clinging performance on three artificial substrates. We selected substrates that exhibit microtopographies with peak‐to‐valley heights similar to those of substrates used in nature, to investigate performance on a range of smooth surfaces (glass), and fine‐grained (fine sandpaper) to rough (coarse sandpaper). We found that shear force did not decline monotonically with roughness, but varied nonlinearly among substrates. Clinging performance was greater on glass and coarse sandpaper than on fine sandpaper, and clinging performance was not significantly different between glass and coarse sandpaper. Our results demonstrate that performance on different substrates varies, probably depending on the underlying mechanisms of the adhesive apparatus in geckos.     

Adult polyphagous coleopterans overwintering in cereal boundaries: winter mortality and susceptibility to the entomopathogenic fungus Beauveria bassiana

Autumn-collected Bembidion lampros and Agonum dorsale were kept outdoors under semi field conditions to determine winter mortality. On three occasions (autumn, mid-winter and late winter) sub-samples of the population were incubated in the laboratory at room temperature and mortality was recorded. Generally the mortality was low in autumn and mid-winter, not exceeding 5%. A more pronounced post-winter mortality of up to 30% was observed at the end of hibernation. Only a negligible number were infected by the entomopathogenic fungi Beauveria bassiana and Paecilomyces farinosus. Infection experiments with B. bassiana isolates from Sitona lineatus, Tachyporus hypnorum and three species of ground beetles showed a similarly low susceptibility of B. lampros and A. dorsale to B. bassiana and, although Tachyporus spp. showed a distinct mycophagy and a significantly higher mortality, this could not be related to mycosis.     

Biogeography of Australasian flightless weevils (Curculionidae,Celeuthetini) suggests permeability of Lydekker's and Wallace's Lines

The Indo‐Australian region was formed by the collision of the Australian and Asian plates, and its fauna largely reflects this dual origin. Lydekker's and Wallace's Lines represent biogeographic transition boundaries between biotas although their permeability through geological times was rarely assessed. Here, we explore the evolutionary history of flightless weevils of the tribe Celeuthetini in this geologically highly complex region. We generated a DNA sequence data set of 2236 bp comprising two nuclear and two mitochondrial markers for 62 species of the Indo‐Australian tribe Celeuthetini. We used Bayesian Inference and Maximum Likelihood to reconstruct the first molecular phylogeny of the group. Based on this phylogenetic tree, we employed the program BioGeoBEARS to infer the biogeographical history of Celeuthetini in the region. The group's radiation begun east of Wallace's Line, probably during the mid‐Eocene. We unveil multiple transgressions of Lydekker's and Wallace's Lines mostly during the Miocene with a significant role of founder‐event speciation. The phylogeny of Celeuthetini is geographically highly structured with the first lineages occurring in New Guinea and the Moluccas, and a deep divergence between two clades largely confined to Sulawesi and their respective sister clades of the Lesser Sunda Islands. Wallace's Line was crossed once from Sulawesi and three times from the Lesser Sunda Islands to Java whilst Lydekker's Line was crossed once from New Guinea to the Moluccas. Although this beetle group shows extensive local diversification with little dispersal, the biogeographical demarcations of the Australasian region appear to have been rather porous barriers to dispersal.     

Different binding modes of tropeines mediating inhibition and potentiation of α1 glycine receptors

Tropeines are bidirectional modulators of native and recombinant glycine receptors (GlyRs) and promising leads for the development of novel modulatory agents. Tropisetron potentiates and inhibits agonist-triggered GlyR currents at femto- to nanomolar and micromolar concentrations respectively. Here, the potentiating and inhibitory effects of another tropeine, 3α-(3'-methoxy-benzoyloxy)nortropane (MBN) were examined by voltage-clamp electrophysiology at wild type and mutant α1 GlyRs expressed in Xenopus laevis oocytes. Several substitutions around the agonist-binding cavity of the α1 subunit interface (N46C, F63A, N102A, R119K, R131A, E157C, K200A, Y202L and F207A) were found to reduce or eliminate MBN inhibition of glycine activation. In contrast, the binding site mutations Q67A, R119A and S129A which did not affect MBN inhibition abolished the potentiation of chloride currents elicited by low concentrations of the partial agonist taurine following pre-incubation with MBN. Thus, potentiation and inhibition involve distinct binding modes of MBN in the inter-subunit agonist-binding pocket of α1 GlyRs. Homology modelling and molecular dynamics simulations disclosed two distinct docking modes for MBN, which are consistent with the differential effects of individual binding site substitutions on MBN inhibition and potentiation respectively. Together these results suggest that distinct binding modes at adjacent binding sites located within the agonist-binding pocket of the GlyR mediate the bidirectional modulatory effects of tropeines.     

Lipopolysaccharide induces a fibrotic‐like phenotype in endothelial cells

Endothelial dysfunction is crucial in endotoxaemia‐derived sepsis syndrome pathogenesis. It is well accepted that lipopolysaccharide (LPS) induces endothelial dysfunction through immune system activation. However, LPS can also directly generate actions in endothelial cells (ECs) in the absence of participation by immune cells. Although interactions between LPS and ECs evoke endothelial death, a significant portion of ECs are resistant to LPS challenge. However, the mechanism that confers endothelial resistance to LPS is not known. LPS‐resistant ECs exhibit a fibroblast‐like morphology, suggesting that these ECs enter a fibrotic programme in response to LPS. Thus, our aim was to investigate whether LPS is able to induce endothelial fibrosis in the absence of immune cells and explore the underlying mechanism. Using primary cultures of ECs and culturing intact blood vessels, we demonstrated that LPS is a crucial factor to induce endothelial fibrosis. We demonstrated that LPS was able and sufficient to promote endothelial fibrosis, in the absence of immune cells through an activin receptor–like kinase 5 (ALK5) activity–dependent mechanism. LPS‐challenged ECs showed an up‐regulation of both fibroblast‐specific protein expression and extracellular matrix proteins secretion, as well as a down‐regulation of endothelial markers. These results demonstrate that LPS is a crucial factor in inducing endothelial fibrosis in the absence of immune cells through an ALK5‐dependent mechanism. It is noteworthy that LPS‐induced endothelial fibrosis perpetuates endothelial dysfunction as a maladaptive process rather than a survival mechanism for protection against LPS. These findings are useful in improving current treatment against endotoxaemia‐derived sepsis syndrome and other inflammatory diseases.     

Structural elucidation of 13-acetoxylichesterinic and 13-acetoxyprotolichesterinic acids,two aliphatic lichen metabolites from Neuropogon trachycarpus

From the lichen Neuropogon trachycarpus, six aliphatic acids related to lichesterinic acid have been isolated: neuropogolic, murolic, isomuronic an