Enteric nervous system progenitors are coordinately controlled by the G protein-coupled receptor EDNRB and the receptor tyrosine kinase RET

The enteric nervous system (ENS) in vertebrates is derived mainly from vagal neural crest cells that enter the foregut and colonize the entire wall of the gastrointestinal tract. Failure to completely colonize the gut results in the absence of enteric ganglia (Hirschsprung's disease). Two signaling systems mediated by RET and EDNRB have been identified as critical players in enteric neurogenesis. We demonstrate that interaction between these signaling pathways controls ENS development throughout the intestine. Activation of EDNRB specifically enhances the effect of RET signaling on the proliferation of uncommitted ENS progenitors. In addition, we reveal novel antagonistic roles of these pathways on the migration of ENS progenitors. Protein kinase A is a key component of the molecular mechanisms that integrate signaling by the two receptors. Our data provide strong evidence that the coordinate and balanced interaction between receptor tyrosine kinases and G protein-coupled receptors controls the development of the nervous system in mammals.     

How should pathogen transmission be modelled?

Host-pathogen models are essential for designing strategies for managing disease threats to humans, wild animals and domestic animals. The behaviour of these models is greatly affected by the way in which transmission between infected and susceptible hosts is modelled. Since host-pathogen models were first developed at the beginning of the 20th century, the 'mass action' assumption has almost always been used for transmission. Recently, however, it has been suggested that mass action has often been modelled wrongly. Alternative models of transmission are beginning to appear, as are empirical tests of transmission dynamics.     

Iridodialysis in a rhesus macaque: a case report

During routine physical examination, a five-year-old male rhesus macaque (Macaca mulatta) was observed to have gaps in the right iris. Ophthalmic examination revealed inferior and superior iridodialysis with an anterior cortical cataract. The optic nerve head and fundus were normal. Uninvolved areas of the iris and anterior-chamber angle were normal on the basis of results of gonioscopy. Tonometry revealed normal intraocular pressure. The cause of the iridodialysis in this monkey's eye was not known. The animal had been housed individually since arrival due to requirements of the research protocol. Although the concomitant cataract supports a traumatic cause, there was no history of cranial or other ocular injuries. Trauma from fighting through the cage walls, self-trauma or falling inside the cage while under sedation cannot be ruled out. Multiple hematologic evaluations disclosed no abnormalities. This animal did not manifest behavioral abnormalities or any indication of pain. Therefore, treatment was not initiated. Intraocular pressure continues to be monitored at least semiannually.     

Dissecting sites important for complement regulatory activity in membrane cofactor protein (MCP; CD46)

Membrane cofactor protein (MCP; CD46), a widely distributed regulator of complement activation, is a cofactor for the factor I-mediated degradation of C3b and C4b deposited on host cells. MCP possesses four extracellular, contiguous complement control protein modules (CCPs) important for this inhibitory activity. The goal of the present study was to delineate functional sites within these modules. We employed multiple approaches including mutagenesis, epitope mapping, and comparisons to primate MCP to make the following observations. First, functional sites were located to each of the four CCPs. Second, some residues were important for both C3b and C4b interactions while others were specific for one or the other. Third, while a reduction in ligand binding was invariably accompanied by a parallel reduction in cofactor activity (CA), other mutants lost or had reduced CA but retained ligand binding. Fourth, two C4b-regulatory domains overlapped measles virus interactive regions, indicating that the hemagglutinin docks to a site important for complement inhibition. Fifth, several MCP regulatory areas corresponded to functionally critical, homologous positions in other CCP-bearing C3b/C4b-binding proteins. Based on these data and the recently derived crystal structure of repeats one and two, computer modeling was employed to predict MCP structure and examine active sites.     

Complete assignment of 1H, 13C and 15N chemical shifts for bovine β-lactoglobulin: Secondary structure and topology of the native state is retained in a partially unfolded form

Although -lactoglobulin (-LG) has been studied extensively for more than 50 years, its physical properties in solution are not yet understood fully in terms of its three-dimensional (3D) structure. For example, despite a recent high-resolution crystal structure, it is still not clear why the two common variants of bovine -LG which differ by just two residues have different aggregation properties during milk processing. We have conducted solution-state NMR studies on a recombinant form of the A variant of -LG at low pH conditions where the protein is partially unfolded and exists as a monomer rather than a dimer. Using a¹³ C,¹⁵N-labelled sample, expressed in Pichia pastoris, we have employed the standard combination of 3D heteronuclear NMR techniques to obtain near complete assignments of proton, carbon and nitrogen resonances. Using a novel pulse sequence we were able to obtain additional assignments, in particular those of methyl groups in residues preceding proline within the sequence. From chemical shifts and on the basis of inter-residue NOEs, we have inferred the secondary structure and topology of monomeric -LG A. It includes eight antiparallel -strands arranged in a barrel, flanked by an -helix, which is typical of a member of the lipocalin family. A detailed comparison with the crystal structure of the dimeric form (for a mixture of A and B variants) at pH 6.5 reveals a close resemblance in both secondary structure and overall topology. Both forms have a ninth -strand which, at the higher pH, forms part of the dimer interface. These studies represent the first full NMR assignment of -LG and will form the basis for a complete characterisation of the solution structure and dynamics of this protein and its variants.     

Inferring Cetacean Population Densities from the Absolute Dynamic Topography of the Ocean in a Hierarchical Bayesian Framework

We inferred the population densities of blue whales (Balaenoptera musculus) and short-beaked common dolphins (Delphinus delphis) in the Northeast Pacific Ocean as functions of the water-column’s physical structure by implementing hierarchical models in a Bayesian framework. This approach allowed us to propagate the uncertainty of the field observations into the inference of species-habitat relationships and to generate spatially explicit population density predictions with reduced effects of sampling heterogeneity. Our hypothesis was that the large-scale spatial distributions of these two cetacean species respond primarily to ecological processes resulting from shoaling and outcropping of the pycnocline in regions of wind-forced upwelling and eddy-like circulation. Physically, these processes affect the thermodynamic balance of the water column, decreasing its volume and thus the height of the absolute dynamic topography (ADT). Biologically, they lead to elevated primary productivity and persistent aggregation of low-trophic-level prey. Unlike other remotely sensed variables, ADT provides information about the structure of the entire water column and it is also routinely measured at high spatial-temporal resolution by satellite altimeters with uniform global coverage. Our models provide spatially explicit population density predictions for both species, even in areas where the pycnocline shoals but does not outcrop (e.g. the Costa Rica Dome and the North Equatorial Countercurrent thermocline ridge). Interannual variations in distribution during El Niño anomalies suggest that the population density of both species decreases dramatically in the Equatorial Cold Tongue and the Costa Rica Dome, and that their distributions retract to particular areas that remain productive, such as the more oceanic waters in the central California Current System, the northern Gulf of California, the North Equatorial Countercurrent thermocline ridge, and the more southern portion of the Humboldt Current System. We posit that such reductions in available foraging habitats during climatic disturbances could incur high energetic costs on these populations, ultimately affecting individual fitness and survival.     

Oral Migalastat HCl Leads to Greater Systemic Exposure and Tissue Levels of Active α-Galactosidase A in Fabry Patients when Co-Administered with Infused Agalsidase

Migalastat HCl (AT1001, 1-Deoxygalactonojirimycin) is an investigational pharmacological chaperone for the treatment of α-galactosidase A (α-Gal A) deficiency, which leads to Fabry disease, an X-linked, lysosomal storage disorder. The currently approved, biologics-based therapy for Fabry disease is enzyme replacement therapy (ERT) with either agalsidase alfa (Replagal) or agalsidase beta (Fabrazyme). Based on preclinical data, migalastat HCl in combination with agalsidase is expected to result in the pharmacokinetic (PK) enhancement of agalsidase in plasma by increasing the systemic exposure of active agalsidase, thereby leading to increased cellular levels in disease-relevant tissues. This Phase 2a study design consisted of an open-label, fixed-treatment sequence that evaluated the effects of single oral doses of 150 mg or 450 mg migalastat HCl on the PK and tissue levels of intravenously infused agalsidase (0.2, 0.5, or 1.0 mg/kg) in male Fabry patients. As expected, intravenous administration of agalsidase alone resulted in increased α-Gal A activity in plasma, skin, and peripheral blood mononuclear cells (PBMCs) compared to baseline. Following co-administration of migalastat HCl and agalsidase, α-Gal A activity in plasma was further significantly increased 1.2- to 5.1-fold compared to agalsidase administration alone, in 22 of 23 patients (95.6%). Importantly, similar increases in skin and PBMC α-Gal A activity were seen following co-administration of migalastat HCl and agalsidase. The effects were not related to the administered migalastat HCl dose, as the 150 mg dose of migalastat HCl increased α-Gal A activity to the same extent as the 450 mg dose. Conversely, agalsidase had no effect on the plasma PK of migalastat. No migalastat HCl-related adverse events or drug-related tolerability issues were identified.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01196871","term_id":"NCT01196871"}}NCT01196871