Munc18-1 promotes larger dense-core vesicle docking.

AbstractSecretory vesicles dock at the plasma membrane before Ca2+ triggers their exocytosis. Exocytosis requires the assembly of SNARE complexes formed by the vesicle protein Synaptobrevin and the membrane proteins Syntaxin-1 and SNAP-25. We analyzed the role of Munc18-1, a cytosolic binding partner of Syntaxin-1, in large dense-core vesicle (LDCV) secretion. Calcium-dependent LDCV exocytosis was reduced 10-fold in mouse chromaffin cells lacking Munc18-1, but the kinetic properties of the remaining release, including single fusion events, were not different from controls. Concomitantly, mutant cells displayed a 10-fold reduction in morphologically docked LDCVs. Moreover, acute overexpression of Munc18-1 in bovine chromaffin cells increased the amount of releasable vesicles and accelerated vesicle supply. We conclude that Munc18-1 functions upstream of SNARE complex formation and promotes LDCV docking

The DNA of coral reef biodiversity: predicting and protecting genetic diversity of reef assemblages

Conservation of ecological communities requires deepening our understanding of genetic diversity patterns and drivers at community-wide scales. Here, we use seascape genetic analysis of a diversity metric, allelic richness (AR), for 47 reef species sampled across 13 Hawaiian Islands to empirically demonstrate that large reefs high in coral cover harbour the greatest genetic diversity on average. We found that a species’s life history (e.g. depth range and herbivory) mediates response of genetic diversity to seascape drivers in logical ways. Furthermore, a metric of combined multi-species AR showed strong coupling to species richness and habitat area, quality and stability that few species showed individually. We hypothesize that macro-ecological forces and species interactions, by mediating species turnover and occupancy (and thus a site’s mean effective population size), influence the aggregate genetic diversity of a site, potentially allowing it to behave as an apparent emergent trait that is shaped by the dominant seascape drivers. The results highlight inherent feedbacks between ecology and genetics, raise concern that genetic resilience of entire reef communities is compromised by factors that reduce coral cover or available habitat, including thermal stress, and provide a foundation for new strategies for monitoring and preserving biodiversity of entire reef ecosystems

Populations of double white dwarfs in Milky Way satellites and their detectability with LISA

Context. Milky Way dwarf satellites are unique objects that encode the early structure formation and therefore represent a window into the high redshift Universe. So far, their study has been conducted using electromagnetic waves only. The future Laser Interferometer Space Antenna (LISA) has the potential to reveal Milky Way satellites through gravitational waves emitted by double white dwarf (DWD) binaries. Aims. We investigate gravitational wave signals that will be detectable by LISA as a possible tool for the identification and characterisation of the Milky Way satellites. Methods. We used the binary population synthesis technique to model the population of DWDs in dwarf satellites and we assessed the impact on the number of LISA detections when making changes to the total stellar mass, distance, star formation history, and metallicity of satellites. We calibrated predictions for the known Milky Way satellites on their observed properties. Results. We find that DWDs emitting at frequencies ≳3 mHz can be detected in Milky Way satellites at large galactocentric distances. The number of these high frequency DWDs per satellite primarily depends on its mass, distance, age, and star formation history, and only mildly depends on the other assumptions regarding their evolution such as metallicity. We find that dwarf galaxies with M⋆ >  106 M⊙ can host detectable LISA sources; the number of detections scales linearly with the satellite’s mass. We forecast that out of the known satellites, Sagittarius, Fornax, Sculptor, and the Magellanic Clouds can be detected with LISA. Conclusions. As an all-sky survey that does not suffer from contamination and dust extinction, LISA will provide observations of the Milky Way and dwarf satellites galaxies, which will be valuable for Galactic archaeology and near-field cosmology

Efficient loading of dendritic cells following cryo and radiofrequency ablation in combination with immune modulation induces anti-tumour immunity

Dendritic cells (DC) are professional antigen-presenting cells that play a pivotal role in the induction of immunity. Ex vivo-generated, tumour antigen-loaded mature DC are currently exploited as cancer vaccines in clinical studies. However, antigen loading and maturation of DC directly in vivo would greatly facilitate the application of DC-based vaccines. We formerly showed in murine models that radiofrequency-mediated tumour destruction can provide an antigen source for the in vivo induction of anti-tumour immunity, and we explored the role of DC herein. In this paper we evaluate radiofrequency and cryo ablation for their ability to provide an antigen source for DC and compare this with an ex vivo-loaded DC vaccine. The data obtained with model antigens demonstrate that upon tumour destruction by radiofrequency ablation, up to 7% of the total draining lymph node (LN) DC contained antigen, whereas only few DC from the conventional vaccine reached the LN. Interestingly, following cryo ablation the amount of antigen-loaded DC is almost doubled. Analysis of surface markers revealed that both destruction methods were able to induce DC maturation. Finally, we show that in situ tumour ablation can be efficiently combined with immune modulation by anti-CTLA-4 antibodies or regulatory T-cell depletion. These combination treatments protected mice from the outgrowth of tumour challenges, and led to in vivo enhancement of tumour-specific T-cell numbers, which produced more IFN-γ upon activation. Therefore, in situ tumour destruction in combination with immune modulation creates a unique, ‘in situ DC-vaccine' that is readily applicable in the clinic without prior knowledge of tumour antigens

Performance-based financing as a health system reform : mapping the key dimensions for monitoring and evaluation

Peer reviewedPublisher PD

Milky Way Satellites Shining Bright in Gravitational Waves

The population of Milky Way satellite galaxies is of great interest for cosmology, fundamental physics, and astrophysics. They represent the faint end of the galaxy luminosity function, are the most dark-matter dominated objects in the local Universe, and contain the oldest and most metal-poor stellar populations. Recent surveys have revealed around 60 satellites, but this could represent less than half of the total. Characterization of these systems remains a challenge due to their low luminosity. We consider the gravitational wave observatory LISA as a potential tool for studying these satellites through observations of their short-period double white dwarf populations. LISA will observe the entire sky without selection effects due to dust extinction, complementing optical surveys, and could potentially discover massive satellites hidden behind the disk of the galaxy.Comment: 7 pages, 2 figure

High Levels of Genetic Divergence Detected in Sacramento Perch Suggests Two Divergent Translocation Sources

Translocation has been used to conserve imperiled fishes and create new fisheries. One species for which translocation has played a significant role is the Sacramento Perch Archoplites interruptus. Extirpated from its native range, the Sacramento Perch has been introduced throughout California and Nevada through multiple translocation events, though historical records are incomplete. Recent assessments of eight previously uncharacterized Sacramento Perch populations have prompted reevaluation of range-wide population structure to inform a genetic management plan for long-term resiliency of this species. We examined Sacramento Perch genetic diversity and population structure across the current range of the species using 12 microsatellite markers. We analyzed samples from the eight uncharacterized populations and seven populations previously studied by Schwartz and May (2008). Bayesian clustering supported two distinct clusters of Sacramento Perch herein designated as A and B. Within these two clusters we detected hierarchical substructure, likely due to genetic drift after population founding. Genetic differentiation among populations within the same cluster was relatively low (FST = 0.023–0.176), while differentiation among populations from different clusters was higher (FST = 0.190–0.320). The existence of two strongly divergent genetic clusters in Sacramento Perch suggests two distinct translocation sources, and we recommend that these clusters be treated as genetic management units (GMUs). The B GMU populations had fairly low levels of genetic diversity relative to the A GMU populations. All populations showed evidence of past bottlenecks, and most had effective population sizes placing them at risk for inbreeding depression. Human-facilitated gene flow is recommended to prevent further genetic diversity loss. Due to uncertainty surrounding Sacramento Perch translocation history and strong levels of divergence between the two GMUs, translocations should be facilitated only between populations within the same GMU

Chronic Loss of Melanin-Concentrating Hormone Affects Motivational Aspects of Feeding in the Rat

Current epidemic obesity levels apply great medical and financial pressure to the strenuous economy of obesity-prone cultures, and neuropeptides involved in body weight regulation are regarded as attractive targets for a possible treatment of obesity in humans. The lateral hypothalamus and the nucleus accumbens shell (AcbSh) form a hypothalamic-limbic neuropeptide feeding circuit mediated by Melanin-Concentrating Hormone (MCH). MCH promotes feeding behavior via MCH receptor-1 (MCH1R) in the AcbSh, although this relationship has not been fully characterized. Given the AcbSh mediates reinforcing properties of food, we hypothesized that MCH modulates motivational aspects of feeding

The Effectiveness of Deep Brain Stimulation in Dystonia:A Patient-Centered Approach

Background: To systematically evaluate the effectiveness of deep brain stimulation of the globus pallidus internus (GPi-DBS) in dystonia on pre-operatively set functional priorities in daily living. Methods: Fifteen pediatric and adult dystonia patients (8 male; median age 32y, range 8-65) receiving GPi-DBS were recruited. All patients underwent a multidisciplinary evaluation before and 1-year post DBS implantation. The Canadian Occupational Performance Measure (COPM) first identified and then measured changes in functional priorities. The Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) was used to evaluate dystonia severity. Results: Priorities in daily functioning substantially varied between patients but showed significant improvements on performance and satisfaction after DBS. Clinically significant COPM-score improvements were present in 7/8 motor responders, but also in 4/7 motor non-responders. Discussion: The use of a patient-oriented approach to measure GPi-DBS effectiveness in dystonia provides an unique insight in patients' priorities and demonstrates that tangible improvements can be achieved irrespective of motor response. Highlights: Functional priorities in life of dystonia patients and their caregivers vary greatlyThe effect of DBS on functional priorities did not correlate with motor outcomeHalf of the motor 'non-responder' patients reported important changes in their prioritiesThe effect of DBS in dystonia should not be measured by motor outcome alone

Docking of Secretory Vesicles Is Syntaxin Dependent

Secretory vesicles dock at the plasma membrane before they undergo fusion. Molecular docking mechanisms are poorly defined but believed to be independent of SNARE proteins. Here, we challenged this hypothesis by acute deletion of the target SNARE, syntaxin, in vertebrate neurons and neuroendocrine cells. Deletion resulted in fusion arrest in both systems. No docking defects were observed in synapses, in line with previous observations. However, a drastic reduction in morphologically docked secretory vesicles was observed in chromaffin cells. Syntaxin-deficient chromaffin cells showed a small reduction in total and plasma membrane staining for the docking factor Munc18-1, which appears insufficient to explain the drastic reduction in docking. The sub-membrane cortical actin network was unaffected by syntaxin deletion. These observations expose a docking role for syntaxin in the neuroendocrine system. Additional layers of regulation may have evolved to make syntaxin redundant for docking in highly specialized systems like synaptic active zones