Facial bristle feather histology and morphology in New Zealand birds: Implications for function

Knowledge of structure in biology may help inform hypotheses about function. Little is known about the histological structure or the function of avian facial bristle feathers. Here we provide information on morphology and histology, with inferences for function, of bristles in five predominantly insectivorous birds from New Zealand. We chose species with differing ecologies, including: brown kiwi (Apteryx mantelli), morepork (Ninox novaezealandae), hihi (Notiomystis cincta), New Zealand robin (Petroica australis), and New Zealand fantail (Rhipidura fuliginosa). Average bristle length corrected for body size was similar across species. Bristles occurred in distinct groups on different parts of the head and upper rictal bristles were generally longest. The lower rictal bristles of the fantail were the longest possessed by that species and were long compared to bristles of other species. Kiwi were the only species with forehead bristles, similar in length to the upper rictal bristles of other species, and the lower rictal bristles of fantails. Herbst corpuscles (vibration and pressure sensitive mechanoreceptors) were found in association with bristle follicles in all species. Nocturnal and hole‐nesting birds had more heavily encapsulated corpuscles than diurnal open‐nesting species. Our results suggest that avian facial bristles generally have a tactile function in both nocturnal and diurnal species, perhaps playing a role in prey handling, gathering information during flight, navigating in nest cavities and on the ground at night and possibly in prey‐detection. These differing roles may help explain the observed differences in capsule thickness of the corpuscles. J. Morphol., 2011. © 2010 Wiley‐Liss, Inc.     

The impact of acquired brain damage in terms of epidemiology,economics and loss in quality of life

Background  

Patients with acquired brain damage (ABD) have suffered a brain lesion that interrupts vital development in the physical, psychological and social spheres. Stroke and traumatic brain injury (TBI) are the two main causes. The objectives of this study were to estimate the incidence and prevalence of ABD in the population of the Basque Country and Navarre in 2008, to calculate the associated cost of the care required and finally to assess the loss in health-related quality of life.     

Integrin-linked kinase (ILK) modulates wound healing through regulation of hepatocyte growth factor (HGF)

Integrin-linked kinase (ILK) is an intracellular effector of cell–matrix interactions and regulates many cellular processes, including growth, proliferation, survival, differentiation, migration, invasion and angiogenesis. The present work analyzes the role of ILK in wound healing in adult animals using a conditional knock-out of the ILK gene generated with the tamoxifen-inducible Cre-lox system (CRE-LOX mice). Results show that ILK deficiency leads to retarded wound closure in skin. Intracellular mechanisms involved in this process were analyzed in cultured mouse embryonic fibroblast (MEF) isolated from CRE-LOX mice and revealed that wounding promotes rapid activation of phosphatidylinositol 3-kinase (PI3K) and ILK. Knockdown of ILK resulted in a retarded wound closure due to a decrease in cellular proliferation and loss of HGF protein expression during the healing process, in vitro and in vivo. Alterations in cell proliferation and wound closure in ILK-deficient MEF or mice could be rescued by exogenous administration of human HGF. These data demonstrate, for the first time, that the activation of PI3K and ILK after skin wounding are critical for HGF-dependent tissue repair and wound healing.     

The influence of the type of contraction on the masseter muscle EMG power spectrum

Different behaviours of the EMG power spectrum across increasing force levels have been reported for the masseter muscle. A factor that could explain these different behaviours may be the type of contraction used, as was recently shown for certain upper limb muscles⁵. The purpose of this study was to compare, between two types of isometric contractions, the behaviour of EMG power spectrum statistics (median frequency (MF) and mean power frequency (MPF)) obtained across increasing force levels. Ten women exerted, while biting in the intercuspal position, three 5 s ramp contractions that increased linearly from 0 to 100% of the maximal voluntary contraction (MVC). They also completed three step contractions (constant EMG amplitude) at each of the following levels: 20, 40, 60 and 80% MVC. EMG signals from the masseter muscle were recorded with miniature surface electrodes. The RMS, as well as the MPF and MF of the power spectrum were calculated at 20, 40, 60 and 80% MVC for each type of contraction. As expected, the RMS values showed similar increases with increasing levels of effort for both types of contractions. Different behaviours for both MPF (contraction^*force interaction, ANOVA, P<0.05) and MF (contraction^*force interaction, ANOVA, P>0.05) across increasing levels of effort were found between the two types of contraction. The use of step contractions gave rise to a decrease of both MPF and MF with increasing force, while the use of ramp contractions gave rise to an increase in both statistics up to at least 40% MVC followed by a decrease at higher force levels. These findings suggest that the type of contraction used does influence the behaviour of the spectral statistics across increasing force levels and that this could explain the differences obtained in previous studies for the masseter muscle.     

Short-term Effects of Harvest Technique and Mechanical Site Preparation on Arthropod Communities in Jack Pine Plantations

Arthropods play a key role in the functioning of forest ecosystems and contribute to biological diversity. However, the influence of current silvicultural practices on arthropod communities is little known in jack pine (Pinus banksiana) forests, a forest type comprising a major portion of the Canadian boreal forest. In this study, the effects of silvicultural treatments on arthropod communities were compared to identify those treatments that minimize ecological impacts on arthropods. The influence of harvesting techniques and mechanical site preparations on insect family richness and abundance of arthropods (total, by orders and by trophic groups) was examined in young (three-year-old) jack pine plantations of northern Ontario. Each of the following treatments were conducted in three plots: (1) tree length harvest and trenching; (2) full tree harvest and trenching; (3) full tree harvest and blading; and (4) full tree harvest and no site preparation. Arthropods were collected using sweepnets and pitfall traps over two years. Blading significantly reduced insect family richness, the total abundance of arthropods, abundance of Orthoptera, Heteroptera, Hymenoptera, Diptera, insect larvae, and plant feeders when compared to the other treatments. The use of either full tree or tree length harvesting had similar short-term effects on family richness and the abundance of arthropods. Arthropod diversity declined with increasing post-harvest site disturbance. These results suggest that arthropod communities in the understory and on the ground are reduced most on sites mechanically prepared by blading, but are similar under conditions immediately following either full tree or tree length harvesting. The implications for regenerating jack pine in the boreal forest are discussed.     

Mitochondrial haplotypes reveal olive fly (Bactrocera oleae) population substructure in the Mediterranean

The olive fly (Bactrocera oleae) is the most important olive tree (Olea europaea) pest. In the Mediterranean basin, where 98?% of its main hosts are concentrated, it causes major agricultural losses, due to its negative effect on production and quality of both olive and olive oil. Previous phylogeographic analyses have established that Mediterranean olive fly populations are distinct from other Old World populations, but did not agree on the specific population substructure within this region. In order to achieve a higher resolution of the diversity of olive fly populations, particularly in Central and Western Mediterranean (home to 70?% of the world production), we comparatively analyzed a set of samples from Portugal in the context of published mitochondrial sequences across the species' worldwide range. Strong evidence of population substructure was found in the Central and Western Mediterranean area, with two clearly separate phylogenetic branches. Together with previously published data, our results strongly support the existence of at least three distinct Mediterranean populations of the olive fly, raise the possibility of additional regional substructure and suggest specific avenues for future research. This knowledge can be instrumental in the development of better management and control strategies for a major pest of Mediterranean agriculture.     

An Extracellular Ion Pathway Plays a Central Role in the Cooperative Gating of a K2P K+ Channel by Extracellular pH

Proton-gated TASK-3 K⁺ channel belongs to the K_2P family of proteins that underlie the K⁺ leak setting the membrane potential in all cells. TASK-3 is under cooperative gating control by extracellular [H⁺]. Use of recently solved K_2P structures allows us to explore the molecular mechanism of TASK-3 cooperative pH gating. Tunnel-like side portals define an extracellular ion pathway to the selectivity filter. We use a combination of molecular modeling and functional assays to show that pH-sensing histidine residues and K⁺ ions mutually interact electrostatically in the confines of the extracellular ion pathway. K⁺ ions modulate the pK_a of sensing histidine side chains whose charge states in turn determine the open/closed transition of the channel pore. Cooperativity, and therefore steep dependence of TASK-3 K⁺ channel activity on extracellular pH, is dependent on an effect of the permeant ion on the channel pH_o sensors.     

S100A6 Amyloid Fibril Formation Is Calcium-modulated and Enhances Superoxide Dismutase-1 (SOD1) Aggregation

S100A6 is a small EF-hand calcium- and zinc-binding protein involved in the regulation of cell proliferation and cytoskeletal dynamics. It is overexpressed in neurodegenerative disorders and a proposed marker for Amyotrophic Lateral Sclerosis (ALS). Following recent reports of amyloid formation by S100 proteins, we investigated the aggregation properties of S100A6. Computational analysis using aggregation predictors Waltz and Zyggregator revealed increased propensity within S100A6 helices H_I and H_IV. Subsequent analysis of Thioflavin-T binding kinetics under acidic conditions elicited a very fast process with no lag phase and extensive formation of aggregates and stacked fibrils as observed by electron microscopy. Ca²⁺ exerted an inhibitory effect on the aggregation kinetics, which could be reverted upon chelation. An FT-IR investigation of the early conformational changes occurring under these conditions showed that Ca²⁺ promotes anti-parallel β-sheet conformations that repress fibrillation. At pH 7, Ca²⁺ rendered the fibril formation kinetics slower: time-resolved imaging showed that fibril formation is highly suppressed, with aggregates forming instead. In the absence of metals an extensive network of fibrils is formed. S100A6 oligomers, but not fibrils, were found to be cytotoxic, decreasing cell viability by up to 40%. This effect was not observed when the aggregates were formed in the presence of Ca²⁺. Interestingly, native S1006 seeds SOD1 aggregation, shortening its nucleation process. This suggests a cross-talk between these two proteins involved in ALS. Overall, these results put forward novel roles for S100 proteins, whose metal-modulated aggregation propensity may be a key aspect in their physiology and function.