P2X receptor trafficking in neurons is subunit specific

P2X receptors within the CNS mediate excitatory synaptic transmission and also act presynaptically to modulate neurotransmitter release. We have studied the targeting and trafficking of P2X4 and P2X2 receptors heterologously expressed in cultured olfactory bulb neurons. Homomeric P2X4 receptors had a punctate distribution, and many of the puncta colocalized with early endosomes. In contrast, P2X2 receptors were primarily localized at the plasma membrane. By antibody-labeling of surface receptors in living neurons, we showed that P2X4 receptors undergo rapid constitutive internalization and subsequent reinsertion into the plasma membrane, whereas P2X2 receptors were not regulated in such a way. The internalization of P2X4 receptors was dynamin-dependent, and the binding of ATP enhanced the basal rate of retrieval in a Ca2+-independent manner. The presence of the P2X4 subunit in a P2X4/6 heteromer governed the trafficking properties of the receptor. P2X receptors acted presynaptically to enhance the release of glutamate, suggesting that the regulated cycling of P2X4-containing receptors might provide a mechanism for modulation of synaptic transmission

A tree-decomposed transfer matrix for computing exact Potts model partition functions for arbitrary graphs, with applications to planar graph colourings

Combining tree decomposition and transfer matrix techniques provides a very general algorithm for computing exact partition functions of statistical models defined on arbitrary graphs. The algorithm is particularly efficient in the case of planar graphs. We illustrate it by computing the Potts model partition functions and chromatic polynomials (the number of proper vertex colourings using Q colours) for large samples of random planar graphs with up to N=100 vertices. In the latter case, our algorithm yields a sub-exponential average running time of ~ exp(1.516 sqrt(N)), a substantial improvement over the exponential running time ~ exp(0.245 N) provided by the hitherto best known algorithm. We study the statistics of chromatic roots of random planar graphs in some detail, comparing the findings with results for finite pieces of a regular lattice.Comment: 5 pages, 3 figures. Version 2 has been substantially expanded. Version 3 shows that the worst-case running time is sub-exponential in the number of vertice

Tigers on trails: occupancy modeling for cluster sampling

Occupancy modeling focuses on inference about the distribution of organisms over space, using temporal or spatial replication to allow inference about the detection process. Inference based on spatial replication strictly requires that replicates be selected randomly and with replacement, but the importance of these design requirements is not well understood. This paper focuses on an increasingly popular sampling design based on spatial replicates that are not selected randomly and that are expected to exhibit Markovian dependence. We develop two new occupancy models for data collected under this sort of design, one based on an underlying Markov model for spatial dependence and the other based on a trap response model with Markovian detections. We then simulated data under the model for Markovian spatial dependence and fit the data to standard occupancy models and to the two new models. Bias of occupancy estimates was substantial for the standard models, smaller for the new trap response model, and negligible for the new spatial process model. We also fit these models to data from a large-scale tiger occupancy survey recently conducted in Karnataka State, southwestern India. In addition to providing evidence of a positive relationship between tiger occupancy and habitat, model selection statistics and estimates strongly supported the use of the model with Markovian spatial dependence. This new model provides another tool for the decomposition of the detection process, which is sometimes needed for proper estimation and which may also permit interesting biological inferences. In addition to designs employing spatial replication, we note the likely existence of temporal Markovian dependence in many designs using temporal replication. The models developed here will be useful either directly, or with minor extensions, for these designs as well. We believe that these new models represent important additions to the suite of modeling tools now available for occupancy estimation in conservation monitoring. More generally, this work represents a contribution to the topic of cluster sampling for situations in which there is a need for specific modeling (e.g., reflecting dependence) for the distribution of the variable(s) of interest among subunits

Habitat‐dependent occupancy and movement in a migrant songbird highlights the importance of mangroves and forested lagoons in Panama and Colombia

Climate change is predicted to impact tropical mangrove forests due to decreased rainfall, sea‐level rise, and increased seasonality of flooding. Such changes are likely to influence habitat quality for migratory songbirds occupying mangrove wetlands during the tropical dry season. Overwintering habitat quality is known to be associated with fitness in migratory songbirds, yet studies have focused primarily on territorial species. Little is known about the ecology of nonterritorial species that may display more complex movement patterns within and among habitats of differing quality. In this study, we assess within‐season survival and movement at two spatio‐temporal scales of a nonterritorial overwintering bird, the prothonotary warbler (Protonotaria citrea), that depends on mangroves and tropical lowland forests. Specifically, we (a) estimated within‐patch survival and persistence over a six‐week period using radio‐tagged birds in central Panama and (b) modeled abundance and occupancy dynamics at survey points throughout eastern Panama and northern Colombia as the dry season progressed. We found that site persistence was highest in mangroves; however, the probability of survival did not differ among habitats. The probability of warbler occupancy increased with canopy cover, and wet habitats were least likely to experience local extinction as the dry season progressed. We also found that warbler abundance is highest in forests with the tallest canopies. This study is one of the first to demonstrate habitat‐dependent occupancy and movement in a nonterritorial overwintering migrant songbird, and our findings highlight the need to conserve intact, mature mangrove, and lowland forests

Tourism stakeholder exclusion and conflict in a small island

Research in the Isle of Man, British Isles, reveals limited and dysfunctional collaboration between stakeholders, and in particular between public and private sector actors. Power and influence over tourism decision making is generally felt to be restricted to a small and opaque network. Moreover, different levels of interest in and support for tourism further divide stakeholders. Various negative consequences are shown to arise from this absence of collaboration, including a lack of shared vision or future strategy for local tourism, and high levels of mutual mistrust between stakeholders. Resulting conflict, wasted resources, lost enthusiasm and lack of strategic direction appear to undermine the current and future management of island tourism. Emphasised by research is the importance of stakeholder collaboration to sustainable tourism management and underlying factors which may enhance or undermine. Focus on dysfunctional collaboration and the small island setting makes a unique contribution to the existing literature

A different appetite for sovereignty? Independence movements in subnational island jurisdictions

Local autonomy in a subnational jurisdiction is more likely to be gained, secured or enhanced where there are palpable movements or political parties agitating for independence in these smaller territories. A closer look at the fortunes, operations and dynamics of independence parties from subnational island jurisdictions can offer some interesting insights on the appetite for sovereignty and independence, but also the lack thereof, in the twenty-first century.peer-reviewe

Indirect eff ects of childhood pneumococcal conjugate vaccination on invasive pneumococcal disease: a systematic review and meta-analysis

Background The full extent to which childhood pneumococcal conjugate vaccines (PCV) can indirectly reduce illness in unvaccinated populations is not known. We aimed to estimate the magnitude and timing of indirect eff ects of PCVs on invasive pneumococcal disease. Methods In this systematic review and meta-analysis, we searched bibliographic databases for non-randomised quasiexperimental or observational studies reporting invasive pneumococcal disease changes following PCV introduction in unvaccinated populations (studies published Sept 1, 2010, to Jan 6, 2016), updating the previous systematic review of the same topic (studies published Jan 1, 1994, to Sept 30, 2010). Two reviewers extracted summary data by consensus. We used a Bayesian mixed-eff ects model to account for between-study heterogeneity to estimate temporal indirect eff ects by pooling of invasive pneumococcal disease changes by serotype and serogroup. Findings Data were extracted from 70 studies included in the previous review and 172 additional studies, covering 27 high-income and seven middle-income countries. The predicted mean times to attaining a 90% reduction in invasive pneumococcal disease were 8·9 years (95% credible interval [CrI] 7·8–10·3) for grouped serotypes contained in the seven-valent PCV (PCV7), and 9·5 years (6·1–16·6) for the grouped six additional serotypes contained in the 13-valent PCV (PCV13) but not in PCV7. Disease due to grouped serotypes contained in the 23-valent pneumococcal polysaccharide vaccine (PPV23) decreased at similar rates per year in adults aged 19–64 years (relative risk [RR] 0·85, 95% CrI 0·75–0·95) and 65 years and older (0·87, 0·84–0·90). However, we noted no changes in either group in invasive pneumococcal disease caused by the additional 11 serotypes covered by PPV23 but not PCV13. Interpretation Population childhood PCV programmes will lead, on average, to substantial protection across the whole population within a decade. This large indirect protection should be considered when assessing vaccination of older age groups

Quantifying the contribution of immigration to population dynamics : a review of methods, evidence and perspectives in birds and mammals

© 2019 Cambridge Philosophical Society.Peer reviewedPostprin