Influence of bill and foot morphology on the ectoparasites of barn owls

Preening is the principle behavioral defense used by birds to combat ectoparasites. Most birds have a small overhang at the tip of their bills that is used to shear through the tough cuticle of ectoparasitic arthropods, making preening much more efficient. Birds may also scratch with their feet to defend against ectoparasites. This is particularly important for removing ectoparasites on the head, which birds cannot preen. Scratching may be enhanced by the comb-like serrations that are found on the claws of birds in many avian families. We examined the prevalence and intensity of ectoparasites of barn owls (Tyto alba pratincola) in southern Idaho in relation to bill hook length and morphological characteristics of the pectinate claw. The barn owls in our study were infested with 3 species of lice (Phthiraptera: Ischnocera): Colpocephalum turbinatum , Kurodaia subpachygaster, and Strigiphilus aitkeni . Bill hook length was associated with the prevalence of these lice. Owls with longer hooks were more likely to be infested with lice. Conventional wisdom suggests that the bill morphology of raptors has been shaped by selection for efficient foraging; our data suggest that hook morphology may also play a role in ectoparasite defense. The number of teeth on the pectinate claw was also associated with the prevalence of lice. Owls that had claws with more teeth were less likely to be infested with lice, which suggests that larger pectinate claws may offer relatively more protection against ectoparasitic lice. Experiments that manipulate the bill hook and pectinate claw are needed to confirm whether these host characters are involved in ectoparasite defense. Finally, we recovered mammalian ectoparasites from 4 barn owls. We recovered species of mammalian lice (Phthiraptera:Anoplura) and fleas (Siphonaptera) that are commonly found on microtine rodents. The owls probably acquired these parasites from recently eaten prey. This represents 1 of the few documented cases of parasites "straggling" from prey to predator.     

Fragment screening using capillary electrophoresis (CEfrag) for hit identification of heat shock protein 90 ATPase inhibitors

CEfrag is a new fragment screening technology based on affinity capillary electrophoresis (ACE). Here we report on the development of a mobility shift competition assay using full-length human heat shock protein 90α (Hsp90α), radicicol as the competitor probe ligand, and successful screening of the Selcia fragment library. The CEfrag assay was able to detect weaker affinity (IC(50) >500 μM) fragments than were detected by a fluorescence polarization competition assay using FITC-labeled geldanamycin. The binding site of selected fragments was determined by co-crystallization with recombinant Hsp90α N-terminal domain and X-ray analysis. The results of this study confirm that CEfrag is a sensitive microscale technique enabling detection of fragments binding to the biological target in near-physiological solution.     

N-Type Thermoelectric Performance of Functionalized Carbon Nanotube-Filled Polymer Composites

Carbon nanotubes (CNTs) were functionalized with polyethyleneimine (PEI) and made into composites with polyvinyl acetate (PVAc). CNTs were dispersed with different amounts of sodium dodecylbenzenesulfonate (SDBS) prior to the PEI functionalization. The resulting samples exhibit air-stable n-type characteristics with electrical conductivities as great as 1500 S/m and thermopowers as large as −100 µV/K. Electrical conductivity and thermopower were strongly affected by CNT dispersion, improving the properties with better dispersion with high concentrations of SDBS. This improvement is believed to be due to the increase in the number of tubes that are evenly coated with PEI in a better-dispersed sample. Increasing the amount of PEI relative to the other constituents positively affects thermopower but not conductivity. Air exposure reduces both thermopower and conductivity presumably due to oxygen doping (which makes CNTs p-type), but stable values were reached within seven days following sample fabrication.     

The longitudinal relationship between body composition and patella cartilage in healthy adults

Background: Although obesity is a risk factor for patellofemoral osteoarthritis (OA), it is unclear whether the components of body composition, such as muscle and fat mass, are major determinants of articular cartilage properties at the patella. Objective: The aim of this study was to determine whether anthropometric and body composition measures, assessed over 10 years, were related to articular patella cartilage volume and defects in healthy adults with no clinical knee OA. Methods and Procedures: Two hundred and ninety‐seven healthy, community‐based adults aged 50–79 years with no clinical history of knee OA were recruited. Anthropometric and body composition (fat‐free mass and fat mass) data were measured at baseline (1990–1994) and follow‐up (2003–2004). Patella cartilage volume and defects were assessed at follow‐up (2003–2004) using magnetic resonance imaging (MRI). Results: After adjustment for potential confounders, increased measures of obesity (weight, BMI, waist circumference, and fat mass) at baseline and follow‐up were associated with an increased risk for the presence of patella cartilage defects at follow‐up for both men and women (all P ≤ 0.03). Increased baseline values for these variables tended to be associated with reduced patella cartilage volume at follow‐up for women (all P ≤ 0.11), but not men (all P ≤ 0.87). Discussion: We have demonstrated that increased anthropometric measures of obesity, as well as fat mass, are associated with an increased risk for the presence of patella cartilage defects in both men and women. Women, but not men, with greater baseline body mass, particularly adipose‐derived mass, appear to have an associated reduction in their patella cartilage volume. Interventions targeting a reduction in adipose tissue may help reduce the risk for the onset and progression of patellofemoral OA, particularly in women.     

Hairpin ribozyme-antisense RNA constructs can act as molecular Lassos

We have developed a novel class of antisense agents, RNA Lassos, which are capable of binding to and circularizing around complementary target RNAs. The RNA Lasso consists of a fixed sequence derived from the hairpin ribozyme and an antisense segment whose size and sequence can be varied to base pair with accessible sites in the target RNA. The ribozyme catalyzes self-processing of the 5'- and 3'-ends of a transcribed Lasso precursor and ligates the processed ends to produce a circular RNA. The circular and linear forms of the self-processed Lasso coexist in an equilibrium that is dependent on both the Lasso sequence and the solution conditions. Lassos form strong, noncovalent complexes with linear target RNAs and form true topological linkages with circular targets. Lasso complexes with linear RNA targets were detected by denaturing gel electrophoresis and were found to be more stable than ordinary RNA duplexes. We show that expression of a fusion mRNA consisting of a sequence from the murine tumor necrosis factor-alpha (TNF-alpha) gene linked to luciferase reporter can be specifically and efficiently blocked by an anti-TNF Lasso. We also show in cell culture experiments that Lassos directed against Fas pre-mRNA were able to induce a change in alternative splicing patterns.     

Analysis of two genes encoding heat-labile toxins and located on a single Ent plasmid from Escherichia coli.

A clinical isolate of Escherichia coli harbored two copies of the heat-labile toxin (LT)-encoding gene (elt) on a 157-kb plasmid. The arrangement of the gene copies is different from the cholera toxin-encoding gene duplication described for some strains of Vibrio cholerae. The nucleotide sequences of the elt alleles are not identical (differing by 2 bp) and the duplicated region flanking the alleles extends 314 bp on one side and 1122 bp on the other side of each copy. Different partial copies of IS600 were identified 280 bp 3' to the stop codon of each allele. Partial and complete copies of other IS were also identified near the elt alleles. The data suggest that the regions surrounding the genes are hot spots for IS which would account for the observed heterogeneity in DNA flanking elt genes.     

Effect of temperature on seed production in the invasive grass Glyceria maxima (Hartm.) Holmb. (Poaceae) in South Africa

Temperature is one of the main factors that determine sexual reproduction in terrestrial and emergent aquatic plant species. The effect of temperature on sexual reproduction and seed production of Glyceria maxima (Hartm.) Holmb. in the southern hemisphere is unknown. Glyceria maxima collections in February 2010 at three isolated infestations in KwaZulu-Natal failed to yield a single seed, only empty panicles. Laboratory experiments showed that vernalisation had no consistent effect on seed production. Field- and laboratory-grown plants produced seeds in the 2010/2011 season, because of having sufficient time at optimum temperatures required for seed production (1 491 and 1 585 hours, respectively), compared to a shorter period (1 352 hours) of suitable temperatures during the 2009/2010 growing season. An inadequate period of optimum temperatures (15–25°C) during seed production resulted in the lack of seeds in the field in the 2009/2010 growing season. This study showed that temperature and duration of exposure thereto during the seed-production period play vital roles in G. maxima sexual reproduction.