Range expansion in an invasive small mammal: influence of life-history and habitat quality.

Invasive species pose a major threat to biodiversity but provide an opportunity to describe the processes that lead to changes in a species’ range. The bank vole (Myodes glareolus) is an invasive rodent that was introduced to Ireland in the early twentieth century. Given its continuing range expansion, the substantial empirical data on its spread thus far, and the absence of any eradication program, the bank vole in Ireland represents a unique model system for studying the mechanisms influencing the rate of range expansion in invasive small mammals. We described the invasion using a reaction–diffusion model informed by empirical data on life history traits and demographic parameters. We subsequently modelled the processes involved in its range expansion using a rule-based spatially explicit simulation. Habitat suitability interacted with density-dependent parameters to influence dispersal, most notably the density at which local populations started to donate emigrating individuals, the number of dispersing individuals and the direction of dispersal. Whilst local habitat variability influenced the rate of spread, on a larger scale the invasion resembled a simple reaction–diffusion process. Our results suggest a Type 1 range expansion where the rate of expansion is generally constant over time, but with some evidence for a lag period following introduction. We demonstrate that a two-parameter empirical model and a rule-based spatially explicit simulation are sufficient to accurately describe the invasion history of a species that exhibits a complex, density-dependent pattern of dispersal.

‘Papers from ‘A Symposium with Professor Roger Brownsword: Super-stewardship in the Context of Public Health’’

This special issue seeks to engage the term 'stewardship' and the practical and theoretical work around it, both of which are destined to remain items of unfinished business as governance struggles to keep up and connect with its fast moving technological and societal targets. While this special issue is testament to that observation, it also helps to foster much needed scholarly discussion and critique – and to ensure this field is not unwittingly formed and deployed by and as a legitimating support for governance, but rather opened up, elaborated and contested. The articles provide innovative insights and food for thought on the conception and legal-political practice and potential of stewardship and ‘super-stewardship’ in national, supranational and international settings.

An Introduction to 'A Symposium with Professor Roger Brownsword: Super-stewardship in the Context of Public Health'

Introduces the articles in the special issue.

Consensus statements for management of Barrett's dysplasia and early-stage esophageal adenocarcinoma, based on a Delphi process

Esophageal adenocarcinoma (EA) is increasingly common among patients with Barrett's esophagus (BE). We aimed to provide consensus recommendations based on the medical literature that clinicians could use to manage patients with BE and low-grade dysplasia, high-grade dysplasia (HGD), or early-stage EA.

The role of ECE1 variants in cognitive ability in old age and Alzheimer's disease risk

The ß-amyloid peptide may play a central role in Alzheimer's disease (AD) pathogenesis. We have evaluated variants in seven Aß-degrading genes (ACE, ECE1, ECE2, IDE, MME, PLAU, and TF) for association with AD risk in the Genetic and Environmental Risk in Alzheimer's Disease Consortium 1 (GERAD1) cohort, and with three cognitive phenotypes in the Lothian Birth Cohort 1936 (LBC1936), using 128 and 121 SNPs, respectively. In GERAD1, we identified a significant association between a four-SNP intragenic ECE1 haplotype and risk of AD in individuals that carried at least one APOE e4 allele (P = 0.00035, odds ratio = 1.61). In LBC1936, we identified a significant association between a different two-SNP ECE1 intragenic haplotype and non-verbal reasoning in individuals lacking the APOE e4 allele (P = 0.00036, ß = -0.19). Both results showed a trend towards significance after permutation (0.05 <P <0.10). A follow-up cognitive genetic study evaluated the association of ECE1 SNPs in three additional cohorts of non-demented older people. Meta-analysis of the four cohorts identified the significant association (Z <0.05) of SNPs in the ECE-1b promoter with non-verbal reasoning scores, particularly in individuals lacking the APOE e4 allele. Our genetic findings are not wholly consistent. Nonetheless, the AD associated intronic haplotype is linked to the 338A variant of known ECE1b promoter variant, 338C>A (rs213045). We observed significantly less expression from the 338A variant in two human neuroblastoma cell lines and speculate that this promoter may be subject to tissue-specific regulation.

Live-cell visualization of transmembrane protein oligomerization and membrane fusion using two-fragment haptoEGFP methodology

Protein interactions play key roles throughout all subcellular compartments. In the present paper, we report the visualization of protein interactions throughout living mammalian cells using two oligomerizing MV (measles virus) transmembrane glycoproteins, the H (haemagglutinin) and the F (fusion) glycoproteins, which mediate MV entry into permissive cells. BiFC (bimolecular fluorescence complementation) has been used to examine the dimerization of these viral glycoproteins. The H glycoprotein is a type II membrane-receptor-binding homodimeric glycoprotein and the F glycoprotein is a type I disulfide-linked membrane glycoprotein which homotrimerizes. Together they co-operate to allow the enveloped virus to enter a cell by fusing the viral and cellular membranes. We generated a pair of chimaeric H glycoproteins linked to complementary fragments of EGFP (enhanced green fluorescent protein)--haptoEGFPs--which, on association, generate fluorescence. Homodimerization of H glycoproteins specifically drives this association, leading to the generation of a fluorescent signal in the ER (endoplasmic reticulum), the Golgi and at the plasma membrane. Similarly, the generation of a pair of corresponding F glycoprotein-haptoEGFP chimaeras also produced a comparable fluorescent signal. Co-expression of H and F glycoprotein chimaeras linked to complementary haptoEGFPs led to the formation of fluorescent fusion complexes at the cell surface which retained their biological activity as evidenced by cell-to-cell fusion.

RNA interference targeting cathepsin B of the carcinogenic liver fluke, Opisthorchis viverrini

Functional genomics have not been reported for Opisthorchis viverrini or the related fish-borne fluke, Clonorchis sinensis. Here we describe the introduction by square wave electroporation of Cy3-labeled small RNA into adult O. viverrini worms. Adult flukes were subjected to square wave electroporation employing a single pulse for 20 ms of 125V in the presence of 50 µg/ml of Cy3-siRNA. The parasites tolerated this manipulation and, at 24 and 48 h after electroporation, fluorescence from the Cy3-siRNA was evident throughout the parenchyma of the worms, with strong fluorescence evident in the guts and reproductive organs of the adult worms. Second, other worms were treated using the same electroporation settings with double stranded RNA targeting an endogenous papain-like cysteine protease, cathepsin B. This manipulation resulted in a significant reduction in specific mRNA levels encoding cathepsin B, and a significant reduction in cathepsin B activity against the diagnostic peptide, Z-Arg-Arg-AMC. This appears to be the first report of introduction of reporter genes into O. viverrini and the first report of experimental RNA interference (RNAi) in this fluke. The findings indicated the presence of an intact RNAi pathway in these parasites which, in turn, provides an opportunity to probe gene functions in this neglected tropical disease pathogen.