Different Aquaporin-4 Expression in Glioblastoma Multiforme Patients with and without Seizures

Aquaporin-4 (AQP-4), the most important water channel in the brain, is expressed by astrocyte end feet abutting microvessels. Altered expression levels of AQP-4 and redistribution of the protein throughout the membranes of cells found in glioblastoma multiforme (GBM) lead to development of the edema often found surrounding the tumor mass. Dysregulation of AQP-4 also occurs in hippocampal sclerosis and cortical dysplasia in patients with refractory partial epilepsy. This work reports on analysis of the relationship between AQP-4 expression and the incidence of epileptic seizures in patients with GBM. Immunohistochemical and polymerase chain reaction techniques were used to evaluate AQP-4 in biopsy specimens from 19 patients with GBM, 10 of who had a history of seizures before surgery. AQP-4 mRNA levels were identical in the two groups of patients, but AQP-4 expression was more frequently detected on the GBM membranes from specimens of patients with seizures than from individuals without (10 versus 2, P < 0.001). We conclude that reduced expression of cell surface AQP-4 is characteristic of GBM patients without seizures, likely attributable to a posttranslational mechanism.     

NGF Modulates trkANGFR/p75NTR in αSMA-Expressing Conjunctival Fibroblasts from Human Ocular Cicatricial Pemphigoid (OCP)

Objective

In a previous study, we reported the upregulation of Nerve Growth Factor (NGF) and trkA^NGFR expression in Ocular Cicatricial Pemphigoid (OCP), an inflammatory and remodeling eye disease. Herein, we hypothesize a potential NGF-driven mechanism on fibroblasts (FBs) during OCP remodeling events. To verify, human derived OCP-FBs were isolated and characterized either at baseline or after NGF exposure.

Materials and Methods

Conjunctival biopsies were obtained from 7 patients having OCP and 6 control subjects (cataract surgery). Both conjunctivas and primary FB cultures were characterised for αSMA, NGF and trkA^NGFR/p75^NTR expression. Subcultures were exposed to NGF and evaluated for αSMA, NGF, trkA^NGFR/p75^NTR expression as well as TGFβ1/IL4 release. For analysis, early and advanced subgroups were defined according to clinical parameters.

Results

OCP-conjunctivas showed αSMA-expressing FBs and high NGF levels. Advanced OCP-FBs showed higher αSMA expression associated with higher p75^NTR and lower trkA^NGFR expression, as compared to early counterparts. αSMA expression was in keeping with disease severity and correlated to p75^NTR. NGF exposure did not affect trkA^NGFR levels in early OCP-FBs while decreased both αSMA/p75^NTR expression and TGFβ1/IL4 release. These effects were not observed in advanced OCP-FBs.

Conclusions

Taken together, these data are suggestive for a NGF/p75^NTR task in the potential modulation of OCP fibrosis and encourages further studies to fully understand the underlying mechanism occurring in fibrosis. NGF/p75^NTR might be viewed as a potential therapeutic target.     

Complexin synchronizes primed vesicle exocytosis and regulates fusion pore dynamics

ComplexinII (CpxII) and SynaptotagminI (SytI) have been implicated in regulating the function of SNARE proteins in exocytosis, but their precise mode of action and potential interplay have remained unknown. In this paper, we show that CpxII increases Ca²⁺-triggered vesicle exocytosis and accelerates its secretory rates, providing two independent, but synergistic, functions to enhance synchronous secretion. Specifically, we demonstrate that the C-terminal domain of CpxII increases the pool of primed vesicles by hindering premature exocytosis at submicromolar Ca²⁺ concentrations, whereas the N-terminal domain shortens the secretory delay and accelerates the kinetics of Ca²⁺-triggered exocytosis by increasing the Ca²⁺ affinity of synchronous secretion. With its C terminus, CpxII attenuates fluctuations of the early fusion pore and slows its expansion but is functionally antagonized by SytI, enabling rapid transmitter discharge from single vesicles. Thus, our results illustrate how key features of CpxII, SytI, and their interplay transform the constitutively active SNARE-mediated fusion mechanism into a highly synchronized, Ca²⁺-triggered release apparatus.     

Convergence and functional evolution of longirostry in crocodylomorphs

During the Mesozoic, Crocodylomorpha had a much higher taxonomic and morphological diversity than today. Members of one particularly successful clade, Thalattosuchia, are well‐known for being longirostrine: having long, slender snouts. It has generally been assumed that Thalattosuchia owed their success in part to the evolution of longirostry, leading to a feeding ecology similar to that of the living Indian gharial, Gavialis. Here, we compare form and function of the skulls of the thalattosuchian Pelagosaurus and Gavialis using digital reconstructions of the skull musculoskeletal anatomy and finite element models to show that they had different jaw muscle arrangements and biomechanical behaviour. Additionally, the relevance of feeding‐related mandibular traits linked to longirostry in the radiation of crocodylomorph clades was investigated by conducting an evolutionary rates analysis under the variable rates model. We find that, even though Pelagosaurus and Gavialis share similar patterns of stress distribution in their skulls, the former had lower mechanical resistance. This suggests that compared to Gavialis, Pelagosaurus was unable to process large, mechanically less tractable prey, instead operating as a specialized piscivore that fed on softer and smaller prey. Secondly, innovation of feeding strategies was achieved by rate acceleration of functional characters of the mandible, a key mechanism for the diversification of certain clades like thalattosuchians and eusuchians. Different rates of functional evolution suggest divergent diversification dynamics between teleosaurids and metriorhynchids in the Jurassic.     

Development of a panel of genome-wide ancestry informative markers to study admixture throughout the Americas

Most individuals throughout the Americas are admixed descendants of Native American, European, and African ancestors. Complex historical factors have resulted in varying proportions of ancestral contributions between individuals within and among ethnic groups. We developed a panel of 446 ancestry informative markers (AIMs) optimized to estimate ancestral proportions in individuals and populations throughout Latin America. We used genome-wide data from 953 individuals from diverse African, European, and Native American populations to select AIMs optimized for each of the three main continental populations that form the basis of modern Latin American populations. We selected markers on the basis of locus-specific branch length to be informative, well distributed throughout the genome, capable of being genotyped on widely available commercial platforms, and applicable throughout the Americas by minimizing within-continent heterogeneity. We then validated the panel in samples from four admixed populations by comparing ancestry estimates based on the AIMs panel to estimates based on genome-wide association study (GWAS) data. The panel provided balanced discriminatory power among the three ancestral populations and accurate estimates of individual ancestry proportions (R2 > 0.9 for ancestral components with significant between-subject variance). Finally, we genotyped samples from 18 populations from Latin America using the AIMs panel and estimated variability in ancestry within and between these populations. This panel and its reference genotype information will be useful resources to explore population history of admixture in Latin America and to correct for the potential effects of population stratification in admixed samples in the region.     

Characterization of a bacteriocin-producing strain of Enterococcus faecalis from cow’s milk used in the production of Moroccan traditional dairy foods

A bacteriocin-producing lactic acid bacterium (strain 2.5) isolated from cow’s milk used in cheese production from Northern Morocco was selected for its strong anti-listerial activity. The producer strain was identified as Enterococcus faecalis by molecular methods. Strain 2.5 carried the genetic determinants for the two-peptide enterococcal bacteriocin enterocin 1071, and the active bacteriocin was purified to homogeneity by reversed-phase chromatography from culture broths of the producer strain. Strain 2.5 carried two plasmids (of ∼7 and 40 kb). Characterization of strain 2.5 at biosafety level indicated that this strain is non-haemolytic, and lacks the genetic determinants for most of the virulence factors described in enterococci (cylB, cylM, gelE, ace and agg) although it carried the genetic determinants cylA, efaAfs as well as determinants for the sex pheromone peptides cpd, cob, and ccf. Strain 2.5 was resistant to tetracycline, rifampicin, and ciprofloxacin, but it was sensitive to penicillin, ampicillin, vancomycin, and teicoplanin. Results from the present study support the potential role of strain 2.5 as an anti-listerial agent to be tested in traditional fermented foods.