Estimates of sex- and age-class-specific survival probabilities for a southern Great Barrier Reef green sea turtle population

Sex- and age-class-specific survival probabilities of a southern Great Barrier Reef green sea turtle population were estimated using a capture - mark - recapture (CMR) study and a Cormack - Jolly - Seber (CJS) modelling approach. The CMR history profiles for 954 individual turtles tagged over a 9-year period ( 1984 - 1992) were classified into three age classes ( adult, subadult, juvenile) based on somatic growth and reproductive traits. Reduced-parameter CJS models, accounting for constant survival and time-specific recapture, fitted best for all age classes. There were no significant sex-specific differences in either survival or recapture probabilities for any age class. Mean annual adult survival was estimated at 0.9482 (95% CI: 0.92 - 0.98) and was significantly higher than survival for either subadults or juveniles. Mean annual subadult survival was 0.8474 ( 95% CI: 0.79 - 0.91), which was not significantly different from mean annual juvenile survival estimated at 0.8804 ( 95% CI: 0.84 - 0.93). The time-specific adult recapture probabilities were a function of sampling effort but this was not the case for either juveniles or subadults. The sampling effort effect was accounted for explicitly in the estimation of adult survival and recapture probabilities. These are the first comprehensive sex- and age-class-specific survival and recapture probability estimates for a green sea turtle population derived from a long-term CMR program.

Receptor binding studies disclose a novel class of high-affinity inhibitors of the Escherichia coli FimH adhesin

Mannose-binding type 1 pili are important virulence factors for the establishment of Escherichia coli urinary tract infections (UTIs). These infections are initiated by adhesion of uropathogenic E. coli to uroplakin receptors in the uroepithelium via the FimH adhesin located at the tips of type 1 pili. Blocking of bacterial adhesion is able to prevent infection. Here, we provide for the first time binding data of the molecular events underlying type 1 fimbrial adherence, by crystallographic analyses of the FimH receptor binding domains from a uropathogenic and a K-12 strain, and affinity measurements with mannose, common mono- and disaccharides, and a series of alkyl and aryl mannosides. Our results illustrate that the lectin domain of the FimH adhesin is a stable and functional entity and that an exogenous butyl alpha- D-mannoside, bound in the crystal structures, exhibits a significantly better affinity for FimH (K-d = 0.15 muM) than mannose (K-d = 2.3 muM). Exploration of the binding affinities of alpha-D-mannosides with longer alkyl tails revealed affinities up to 5 nM. Aryl mannosides and fructose can also bind with high affinities to the FimH lectin domain, with a 100-fold improvement and 15-fold reduction in affinity, respectively, compared with mannose. Taken together, these relative FimH affinities correlate exceptionally well with the relative concentrations of the same glycans needed for the inhibition of adherence of type 1 piliated E. coli. We foresee that our findings will spark new ideas and initiatives for the development of UTI vaccines and anti-adhesive drugs to prevent anticipated and recurrent UTIs.

Subgeometric rates of convergence for a class of continuous-time Markov process

Let (Phi(t))(t is an element of R+) be a Harris ergodic continuous-time Markov process on a general state space, with invariant probability measure pi. We investigate the rates of convergence of the transition function P-t(x, (.)) to pi; specifically, we find conditions under which r(t) vertical bar vertical bar P-t (x, (.)) - pi vertical bar vertical bar -> 0 as t -> infinity, for suitable subgeometric rate functions r(t), where vertical bar vertical bar - vertical bar vertical bar denotes the usual total variation norm for a signed measure. We derive sufficient conditions for the convergence to hold, in terms of the existence of suitable points on which the first hitting time moments are bounded. In particular, for stochastically ordered Markov processes, explicit bounds on subgeometric rates of convergence are obtained. These results are illustrated in several examples.

Cytokine expanded myeloid precursors function as regulatory antigen-presenting cells and promote tolerance through IL-10-producing regulatory T cells

The initiation of graft-vs-host disease (GVHD) after stem cell transplantation is dependent on direct Ag presentation by host APCs, whereas the effect of donor APC populations is unclear. We studied the role of indirect Ag presentation in allogenic T cell responses by adding populations of cytokine-expanded donor APC to hemopoietic grafts that would otherwise induce lethal GVHD. Progenipoietin-1 (a synthetic G-CSF/Flt-3 ligand molecule) and G-CSF expanded myeloid dendritic cells (DC), plasmacytoid DC, and a novel granulocyte-monocyte precursor population (GM) that differentiate into class II+,CD80/CD86(+),CD40(-) APC during GVHD. Whereas addition of plasmacytoid and myeloid donor DC augmented GVHD, GM cells promoted transplant tolerance by MHC class II-restricted generation of IL-10-secreting, Ag-specific regulatory T cells. Importantly, although GM cells abrogated GVHD, graft-vs-leukemia effects were preserved. Thus, a population of cytokine-expanded GM precursors function as regulatory APCs, suggesting that G-CSF derivatives may have application in disorders characterized by a loss of self-tolerance.

Prediction of HLA-DQ3.2 beta ligands: evidence of multiple registers in class II binding peptides

Motivation: While processing of MHC class II antigens for presentation to helper T-cells is essential for normal immune response, it is also implicated in the pathogenesis of autoimmune disorders and hypersensitivity reactions. Sequence-based computational techniques for predicting HLA-DQ binding peptides have encountered limited success, with few prediction techniques developed using three-dimensional models. Methods: We describe a structure-based prediction model for modeling peptide-DQ3.2 beta complexes. We have developed a rapid and accurate protocol for docking candidate peptides into the DQ3.2 beta receptor and a scoring function to discriminate binders from the background. The scoring function was rigorously trained, tested and validated using experimentally verified DQ3.2 beta binding and non-binding peptides obtained from biochemical and functional studies. Results: Our model predicts DQ3.2 beta binding peptides with high accuracy [area under the receiver operating characteristic (ROC) curve A(ROC) > 0.90], compared with experimental data. We investigated the binding patterns of DQ3.2 beta peptides and illustrate that several registers exist within a candidate binding peptide. Further analysis reveals that peptides with multiple registers occur predominantly for high-affinity binders.

Unicellular pheromone glands of the pentatomid bug Nezara viridula (Heteroptera : Insecta): Ultrastructure, classification, and proposed function

Male Nezara viridula produce sex pheromones from many independent single cells, each with a duct that opens onto the ventral abdominal surface. Despite the presence of along duct and an associated end complex (in the form of a cupule and microvillus saccule), the structural organization of the cells that comprise the gland conform to Class 1 epidermal gland cell classification : a single cell surrounds the entire secretory complex. Each cuticular cupule contains a central bed of filaments and opens into a narrow tubular ductule that leads from the base of the cupule through the epidermis to the cuticle to open externally as a pore. The cuticle of the cupule is continuous with that of the ductule and has the appearance of three layers, although the inner (middle) layer may be a gap formed during construction of the complex. In young adult males, just molted, the ultrastructure of the cells and their inclusions indicate that they are not active. The region of the cell that is distal to the abdominal cuticle is reduced and the proximal region, surrounding the duct, is enlarged when compared with sexually mature (3-4 weeks old) adult males. At maturity the pheromone cells are enlarged distally around the cupule, but are reduced to a narrow sleeve proximally, around the ductule. Two characteristic cell profiles are evident, based on the shape of the cupule and the organelle content. Type A shows a broad opening to the cupule, an abundance of mitochondria, and few vesicular bodies. Type B has an elongated, narrow, vase-like opening to the cupule, few mitochondria, and numerous vesicular bodies. Type B cells are smaller and more abundant than Type A. Distribution within the epidermal layer also differs. It is likely that the different types represent cells producing different secretion profiles. However, the secretions retained by the standard fixation protocol within mature cells of both types look similar and appear to collect as crystalline bodies within the lumen. This may represent a common storage mechanism.

Evaluation of resynchronization of contractile function following biventricular pacing using colour tissue Doppler imaging

Biventdcular (BV) pacing is evaluated as an alternative treatment for patients with dilated cardiomyppathy (both ischemic and non-ischemic) and end-stage heart failure. Colour tissue Doppler imaging using echocardiography allows noninvasive, quantitative assessment of radial motion in the long-axis with measurement of peak systolic velocity timing. The aim of the present study was to evaluate quantitatively, the systolic performance of the left ventricle and the resynchrenization of contraction (before vs after implantation). Patients and methods: 25 patients with dilated cardiomyopathy (11 ischemic), NYHA class III or IV, QRS duration >120 ms received a biventricular pacemaker. Routine 2D echo and colour tissue Doppler imaging were performed before and within 1 week following implantation. LVEF was assessed using the biplane Sampson's method.Peak systolic velocity (PSV) and time to PSV (TPV) were assessed in 4 regions (basal anterior, inferior, lateral and septal). By averaging the TPV from all 4 regions, a synchronization index was dedved from these measurements. Reaults: LVEF improved by 9±9% following pacing; 17 patients improved LVEF 5% or more. The change in PSV in the septal and lateral regions related significantly to the change in LVEF (r=0.74, r=0.62).The change in synchronization index before vs after pacing (as a measurement of REsynchronization) was related to the change in LVEF (y=120x+5.6, r=0.79, P