Ecological Correlates of Roost Fidelity in the Tent-Making Bat Artibeus watsoni

Roost switching is a common occurrence in bats, yet the causes and consequences of such behavior are poorly understood. In this study we explore the ecological correlates of roost fidelity in the tent‐making bat Artibeus watsoni, particularly focusing on the effect of sex, reproductive status, and roost availability using a three‐factor general linear model (GLM). We estimated roost fidelity of radio‐tracked individuals and found that the GLM was significant (R² = 0.72, F_10,34 = 8.91, p < 0.001). Significant interaction terms were observed for relative roost availability and sex (F_4,34 = 16.96, p < 0.001), and relative roost availability and reproductive status (F_6,34 = 7.62, p < 0.001), indicating that variation in roost fidelity among males and females, and among individuals under different breeding conditions, depended on relative roost availability at the site where they were radio‐tracked. Individuals in areas of high roost availability exhibited lower roost fidelity than those sampled in areas of lower roost availability. Females exhibited less roost fidelity than males for all roost availability categories, but the difference between males and females was only significant at high roost availability. The general pattern of decreased roost fidelity as roost availability increased was also prevalent among individuals in different breeding conditions. Additionally, satellite males exhibited higher roost fidelity than resident males in areas of low roost availability, and lactating females had higher roost fidelity than non‐breeding females in areas of medium roost availability. Our study thus demonstrates that sex, reproductive status, and roost availability all affect roost fidelity in the tent‐making bat A. watsoni, and also suggests that roost availability is the most important factor influencing roost fidelity in this bat, providing the first quantitative evidence that roost fidelity is correlated with roost abundance in a single species.     

A derepression system based on the Bacillus subtilis sporulation pathway offers dynamic control of heterologous gene expression

By rewiring the sporulation gene-regulatory network of Bacillus subtilis, we generated a novel expression system relying on derepression. The gene of interest is placed under the control of the abrB promoter, which is active only when Spo0A is absent, and Spo0A is controlled via an IPTG (isopropyl-beta-d-thiogalactopyranoside)-inducible promoter.     

Production of dehydroamino acid-containing peptides by Lactococcus lactis

Nisin is a pentacyclic peptide antibiotic produced by some Lactococcus lactis strains. Nisin contains dehydroresidues and thioether rings that are posttranslationally introduced by a membrane-associated enzyme complex, composed of a serine and threonine dehydratase NisB and the cyclase NisC. In addition, the transporter NisT is necessary for export of the modified peptide. We studied the potential of L. lactis expressing NisB and NisT to produce peptides whose serines and threonines are dehydrated. L. lactis containing the nisBT genes and a plasmid coding for a specific leader peptide fusion construct efficiently produced peptides with a series of non-naturally occurring multiple flanking dehydrobutyrines. We demonstrated NisB-mediated dehydration of serines and threonines in a C-terminal nisin(1-14) extension of nisin, which implies that also residues more distant from the leader peptide than those occurring in prenisin or any other lantibiotic can be modified. Furthermore, the feasibility and efficiency of generating a library of peptides containing dehydroresidues were demonstrated. In view of the particular shape and reactivity of dehydroamino acids, such a library provides a novel source for screening for peptides with desired biological and physicochemical properties.     

Molecular structure, bioavailability and bioactivity of [Cu(o-phen)2(cnge)](NO3)2.2H2O and [Cu(o-phen)(cnge)(H2O)(NO3)2] complexes

Two Cu(II) complexes with cyanoguanidine (cnge) and o-phenanthroline, [Cu(o-phen)(2)(cnge)](NO(3))(2).2H(2)O (1) and [Cu(o-phen)(cnge)(H(2)O)(NO(3))(2)] (2), have been synthesized using different experimental techniques and characterized by elemental analyses, FTIR, diffuse and UV-vis spectra and EPR and magnetic moment measurements techniques. The crystal structures of both complexes were solved by X-ray diffraction methods. Complex (1) crystallizes in the monoclinic space group C2/c with a=12.621(5), b=31.968(3), c=15.39(1)A, beta=111.68(4) degrees, and Z=8 and complex (2) in the monoclinic space group P2(1)/n with a=10.245(1), b=13.923(2), c=12.391(2)A, beta=98.07(1) degrees, and Z=4. The environments of the copper(II) center are trigonal bipyramidal (TBP) for [Cu(o-phen)(2)(cnge)](2+) and an elongated octahedron for [Cu(o-phen)(cnge)(H(2)O)(NO(3))(2)]. Solution studies have been performed to determine the species distribution. The superoxide dismutase (SOD) activities of both complexes have also been tested in order to determine if these compounds mimic the enzymatic action of the enzyme SOD that protects cells against peroxide radicals.     

Antioxidant activity of twenty five plants from Colombian biodiversity

The antioxidant activity of the crude n-hexane, dichloromethane, and methanol extracts from 25 species belonging to the Asteraceae, Euphorbiaceae, Rubiaceae, and Solanaceae families collected at natural reserves from the Eje Cafetero Ecorregión Colombia, were evaluated by using the spectrophotometric 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging method. The strongest antioxidant activities were showed by the methanol and dichloromethane extracts from the Euphorbiaceae, Alchornea coelophylla (IC50 41.14 mg/l) and Acalypha platyphilla (IC50 111.99 mg/l), respectively. These two species had stronger DPPH radical scavenging activities than hydroquinone (IC50 151.19 mg/l), the positive control. The potential use of Colombian flora for their antioxidant activities is discussed.     

The crystal structure of the extracellular domain of the inhibitor receptor expressed on myeloid cells IREM-1

The immune receptors expressed on myeloid cells (IREM) are type I transmembrane proteins encoded on human chromosome 17 (17q25.1), whose function is believed to be important in controlling inflammation. To date, three IREM receptors have been identified. IREM-1 functions as an inhibitory receptor, whereas IREM-2 and IREM-3 serve an activating function. Here, we report the crystal structure of IREM-1 extracellular domain at 2.6 A resolution. The overall fold of IREM-1 resembles that of a V-type immunoglobulin domain, and reveals overall close homology with immunoglobulin domains from other immunoreceptors such as CLM-1, TREM-1, TLT-1 and NKp44. Comparing the surface electrostatic potential and hydrophobicity of IREM-1 with its murine homologous CLM-1, we observed unique structural properties for the complementary determining region of IREM-1, which suggests that they may be involved in recognition of the IREM-1 ligand. Particularly interesting is the structural conformation and physical properties of the antibody's equivalent CDR3 loop, which we show to be a structurally variable region of the molecule and therefore could be the main structural determinant for ligand discrimination and binding. In addition, the analysis of the IREM-1 structure revealed the presence of four structurally different cavities. Three of these cavities form a continuous hydrophobic groove on the IREM-1 surface, which point to a region of the molecule capable of accommodating potential ligands.     

Low seroprevalence of Neospora caninum infection associated with the limousin breed in cow-calf herds in Andorra, Europe

Neospora caninum seroprevalence and risk factors affecting seroprevalence in beef cattle in Andorra were investigated. Antibodies to N. caninum were evaluated by enzyme-linked immunosorbent assay performed on a yearly basis in 1,758 animals older than 6 mo, belonging to 26 herds. Mean seroprevalence of antibodies to N. caninum for the herds was 7.4 +/- 1.2% (130/1,758). Logistic regression analyses were performed on data from each animal, considering N. caninum seropositivity as the dependent variable, and herd, grazing area, year of sampling, repeat-test animal (animals sampled twice or more), sex, breed, age (animals <4 yr old or > or =5 yr old), and country of birth as possible risk factors. Based on the odds ratio, the prevalence of infection was 2.1 times higher (P < 0.01) in animals from the Ordino grazing area, 1.64 times higher in animals older than 5 yr (P < 0.01), and 6.7 times (1/0.15) lower in Limousin-mixed Limousin cattle (P < 0.002). The results suggest that the particular grazing location could promote the horizontal transmission of this parasite and that certain breeds are less susceptible to N. caninum infection than others.