The fine-scale utilization of forest edges by mammalian mesopredators related to patch size and conservation issues in Central European farmland

The marked negative impact of habitat fragmentation and the edge effect on many populations of bird species is a recent major concern in conservation biology. Here, we focus on the edge effect in different sized forest patches in Central European farmland. In particular, we tested whether the distribution of mammalian mesopredators is related to fragment size and distance to habitat edge, and whether the contribution of these factors is additive or interactive. To assess fine-scale utilization of forest edges, we established transects of four scent stations at different distances from forest edges into the interior (0, 25, 50, 100 m) in 146 forest fragments of variable patch size (3.2–5099.6 ha) from May to June, 2008–2009. This large sample size allowed us to perform detailed analyses separately for all detected species. Our findings confirm that mammalian mesopredators strongly prefer habitat edges and small forest fragments. The probability of occurrence tended to decrease with increasing distance from the edge for all seven carnivore species detected. The carnivores’ occurrence was also negatively correlated with forest fragment area. All detected species tended to prefer small fragments, with the exception of the Eurasian badger (showing the reverse but non-significant pattern) and the red fox (no effect of fragment size). In addition, the non-significant interaction between fragment size and distance to edge suggests that both of these factors contribute independently and additively to mesopredator-mediated effects on biota in a fragmented landscape.     

Factors Affecting Sleep/vigilance Behaviour in Incubating Mallards

Vigilance is a behavioural tactic that allows individuals to control their surroundings and to assess predation risk. In contrast, sleep is unique behavioural state with widely hypothesized restorative and energy‐saving functions, but reducing attentiveness and increasing susceptibility to predation. Sleeping birds resolve this conflict by interrupting sleep with short periods of eye opening (termed ‘scans’) during vigilant sleep. Miscellaneous environmental factors and sleeping postures may affect the perception of risk and corresponding vigilance level. Here, we investigated the influence of nest vegetation concealment, time of day and sleeping postures on the sleep/vigilance trade‐off in incubating Mallards (Anas platyrhynchos). We found that incubating females increased their vigilance with increasing nest vegetation cover facing the vigilant eye during both the day and the night periods; however, mean nest vegetation concealment did not affect female vigilance. Females also reduced their total vigilance along with scan frequency during the night period, while displaying the opposite pattern during the daylight. The rest‐sleeping position was preferred more during the night compared with the daylight period, and females were more vigilant in this position at night. Our data show that the nest vegetation concealment regardless of visual abilities during different light conditions, time of day and sleeping posture play an underlying role in antipredator vigilance during sleep in this cryptic ground‐nesting bird.     

Patterns of host–parasite associations in tropical lice and their passerine hosts in Cameroon

Coevolutionary processes that drive the patterns of host–parasite associations can be deduced through congruence analysis of their phylogenies. Feather lice and their avian hosts have previously been used as typical model systems for congruence analysis; however, such analyses are strongly biased toward nonpasserine hosts in the temperate zone. Further, in the Afrotropical region especially, cospeciation studies of lice and birds are entirely missing. This work supplements knowledge of host–parasite associations in lice using cospeciation analysis of feather lice (genus Myrsidea and the Brueelia complex) and their avian hosts in the tropical rainforests of Cameroon. Our analysis revealed a limited number of cospeciation events in both parasite groups. The parasite–host associations in both louse groups were predominantly shaped by host switching. Despite a general dissimilarity in phylogeny for the parasites and hosts, we found significant congruence in host–parasite distance matrices, mainly driven by associations between Brueelia lice and passerine species of the Waxbill (Estrildidae) family, and Myrsidea lice and their Bulbul (Pycnonotidae) host species. As such, our study supports the importance of complex biotic interactions in tropical environments.     

A Comparison of Protein and mRNA Expression during Development of the Soil Dwelling Prokaryote (S. coelicolor)

In this paper, correlation analysis of protein and mRNA levels in the soil dwelling bacteria Streptomyces coelicolor (S. coelicolor M145) is presented during development of the population as it grew in liquid medium using three biological and two technical replicates, measured during exponential growth, and its entry into the stationary phase. The proteome synthesis time series are compared with the gene expression time series measured previously under identical experimental conditions. Results reveal that about one third of protein/mRNA synthesis profiles are well correlated while another third are correlated negatively. Functional analysis of the highly correlated groups is presented. Based on numerical simulation, the negative correlation between protein and mRNA is shown to be caused by the difference between the rate of translation and protein degradation.     

Plasmonic Properties of Gold Nanostructures on Gold Film

This paper reports on a systematic study of the plasmonic properties of periodic arrays of gold cylindrical nanoparticles in contact with a gold thin film. Depending on the gold film thickness, it observes several plasmon bands. Using a simple analytical model, it is able to assign all these modes and determine that they are due to the coupling of the grating diffraction orders with the propagating surface plasmons travelling along the film. With finite difference time domain (FDTD) simulations, it demonstrates that large field enhancement occurs at the surface of the nanocylinders due to the resonant excitation of these modes. By tilting the sample, it also observes the evolution of the spectral position of these modes and their tuning through nearly the whole visible range is possible. Such plasmonic substrates combining both advantages of the propagative and localised surface plasmons could have large applications in enhanced spectroscopies.

     

Positive selection and convergent evolution shape molecular phenotypic traits of innate immunity receptors in tits (Paridae)

Despite widespread variability and redundancy abounding animal immunity, little is currently known about the rate of evolutionary convergence (functionally analogous traits not inherited from a common ancestor) in host molecular adaptations to parasite selective pressures. Toll‐like receptors (TLRs) provide the molecular interface allowing hosts to recognize pathogenic structures and trigger early danger signals initiating an immune response. Using a novel combination of bioinformatic approaches, here we explore genetic variation in ligand‐binding regions of bacteria‐sensing TLR4 and TLR5 in 29 species belonging to the tit family of passerine birds (Aves: Paridae). Three out of the four consensual positively selected sites in TLR4 and six out of 14 positively selected positions in TLR5 were located on the receptor surface near the functionally important sites, and based on the phylogenetic pattern evolved in a convergent (parallel) manner. This type of evolution was also seen at one N‐glycosylation site and two positively selected phosphorylation sites, providing the first evidence of convergence in post‐translational modifications in evolutionary immunology. Finally, the overall mismatch between phylogeny and the clustering of surface charge distribution demonstrates that convergence is common in overall TLR4 and TLR5 molecular phenotypes involved in ligand binding. Our analysis did not reveal any broad ecological traits explaining the convergence observed in electrostatic potentials, suggesting that information on microbial symbionts may be needed to explain TLR evolution. Adopting state‐of‐the‐art predictive structural bionformatics, we have outlined a new broadly applicable methodological approach to estimate the functional significance of positively selected variation and test for the adaptive molecular convergence in protein‐coding polymorphisms.     

Effect of the concentration of protein and nanoparticles on the structure of biohybrid nanocomposites

We present colloidal nanocomposites formed by incorporating magnetite Fe₃O₄ nanoparticles (MNPs) with lysozyme amyloid fibrils (LAFs). Preparation of two types of solutions, with and without addition of salt, was carried out to elucidate the structure of MNPs-incorporated fibrillary nanocomposites and to study the effect of the presence of salt on the stability of the nanocomposites. The structural morphology of the LAFs and their interaction with MNPs were analyzed by atomic force microscopy and small-angle x-ray scattering measurements. The results indicate that conformational properties of the fibrils are dependent on the concentration of protein, and the precise ratio of the concentration of the protein and MNPs is crucially important for the stability of the fibrillary nanocomposites. Our results confirm that despite the change in fibrillary morphology induced by the varying concentration of the protein, the adsorption of MNPs on the surface of LAF is morphologically independent. Moreover, most importantly, the samples containing salt have excellent stability for up to 1 year of shelf-life.