Regulation of the small regulatory RNA MicA by ribonuclease III: a target-dependent pathway

MicA is a trans-encoded small non-coding RNA, which downregulates porin-expression in stationary-phase. In this work, we focus on the role of endoribonucleases III and E on Salmonella typhimurium sRNA MicA regulation. RNase III is shown to regulate MicA in a target-coupled way, while RNase E is responsible for the control of free MicA levels in the cell. We purified both Salmonella enzymes and demonstrated that in vitro RNase III is only active over MicA when in complex with its targets (whether ompA or lamB mRNAs). In vivo, MicA is demonstrated to be cleaved by RNase III in a coupled way with ompA mRNA. On the other hand, RNase E is able to cleave unpaired MicA and does not show a marked dependence on its 5' phosphorylation state. The main conclusion of this work is the existence of two independent pathways for MicA turnover. Each pathway involves a distinct endoribonuclease, having a different role in the context of the fine-tuned regulation of porin levels. Cleavage of MicA by RNase III in a target-dependent fashion, with the concomitant decay of the mRNA target, strongly resembles the eukaryotic RNAi system, where RNase III-like enzymes play a pivotal role.     

Phylogeny and taxonomy of Potamotrygonocotyle Mayes, Brooks & Thorson, 1981 (Monogenoidea: Monocotylidae) with a description of four new species

The marine-derived stingrays of Potamotrygonidae, endemic to South American river systems, host an interesting parasite fauna equally related to marine lineages. Among those lineages, the diversity and phylogenetic relationships within Potamotrygonocotyle - a monocotylid monogenoidean specific to potamotrygonids - are poorly known, since 9 of 10 species attributed to this genus have been described in the past 3 years. Here, we readdress the diversity of Potamotrygonocotyle after examining the gills of 436 potamotrygonid individuals representing 12 described and 14 potentially undescribed species of freshwater stingrays from 19 major river systems of South America (i.e. sub-basins). We recognized 12 valid species within the parasite genus, of which four are described in this study. Our taxonomic decisions were based on the phylogenetic analysis of 14 ingroup terminal taxa and 12 morphological characters, which resulted in the following hypothesis of sister-group relationships: ((P. dromedarius, P. tatianae sp. nov.), (P. rionegrense, P. auriculocotyle sp. nov., ((P. quadracotyle, P. umbella), (P. septemcotyle sp. nov., (P. chisholmae, P. uruguayense)), (P. tsalickisi, P. eurypotamoxenus, P. rarum, (P. tocantinsense sp. nov., P. aramasae))))). According to our hypothesis, the absence of autapomorphic features for some nominal species, and the re-evaluation of morphological variation among populations, led us to consider P. eurypotamoxenus and P. uruguayense as junior synonymys of P. tsalicksi and P. chisholmae, respectively. Finally, we address the importance of biogeographic and host representation, in order to fully understand the patterns of morphological variation and host specificity within this group. We found that hypotheses of species delimitation depend greatly on efforts to sample specimens throughout its distributional range and that host specificity within this genus varies dramatically among lineages.     

Increased Th2 cytokine secretion, eosinophilic airway inflammation, and airway hyperresponsiveness in neurturin-deficient mice

Neurotrophins such as nerve growth factor and brain-derived neurotrophic factor have been described to be involved in the pathogenesis of asthma. Neurturin (NTN), another neurotrophin from the glial cell line-derived neurotrophic factor family, was shown to be produced by human immune cells: monocytes, B cells, and T cells. Furthermore, it was previously described that the secretion of inflammatory cytokines was dramatically stimulated in NTN knockout (NTN(-/-)) mice. NTN is structurally similar to TGF-β, a protective cytokine in airway inflammation. This study investigates the implication of NTN in a model of allergic airway inflammation using NTN(-/-) mice. The bronchial inflammatory response of OVA-sensitized NTN(-/-) mice was compared with wild-type mice. Airway inflammation, Th2 cytokines, and airway hyperresponsiveness (AHR) were examined. NTN(-/-) mice showed an increase of OVA-specific serum IgE and a pronounced worsening of inflammatory features. Eosinophil number and IL-4 and IL-5 concentration in the bronchoalveolar lavage fluid and lung tissue were increased. In parallel, Th2 cytokine secretion of lung draining lymph node cells was also augmented when stimulated by OVA in vitro. Furthermore, AHR was markedly enhanced in NTN(-/-) mice after sensitization and challenge when compared with wild-type mice. Administration of NTN before challenge with OVA partially rescues the phenotype of NTN(-/-) mice. These findings provide evidence for a dampening role of NTN on allergic inflammation and AHR in a murine model of asthma.     

Rat Cerebellar Slice Cultures Exposed to Bilirubin Evidence Reactive Gliosis,Excitotoxicity and Impaired Myelinogenesis that Is Prevented by AMPA and TNF-α Inhibitors

The cerebellum is one of the most affected brain regions in the course of bilirubin-induced neurological dysfunction. We recently demonstrated that unconjugated bilirubin (UCB) reduces oligodendrocyte progenitor cell (OPC) survival and impairs oligodendrocyte (OL) differentiation and myelination in co-cultures of dorsal root ganglia neurons and OL. Here, we used organotypic cerebellar slice cultures, which replicate many aspects of the in vivo system, to dissect myelination defects by UCB in the presence of neuroimmune-related glial cells. Our results demonstrate that treatment of cerebellar slices with UCB reduces the number of myelinated fibres and myelin basic protein mRNA expression. Interestingly, UCB addition to slices increased the percentage of OPC and decreased mature OL content, whereas it decreased Olig1 and increased Olig2 mRNA expression. These UCB effects were associated with enhanced gliosis, revealed by an increased burden of both microglia and astrocytes. Additionally, UCB treatment led to a marked increase of tumor necrosis factor (TNF)-α and glutamate release, in parallel with a decrease of interleukin (IL)-6. No changes were observed relatively to IL-1β and S100B secretion. Curiously, both α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist and TNF-α antibody partially prevented the myelination defects that followed UCB exposure. These data point to a detrimental role of UCB in OL maturation and myelination together with astrocytosis, microgliosis, and both inflammatory and excitotoxic responses, which collectively may account for myelin deficits following moderate to severe neonatal jaundice.     

Characterization of a thermotolerant laccase produced by Streptomyces sp. SB086

Laccases have become desirable enzymes for application in many industrial processes. Nowadays, most of these enzymes are obtained from fungi. Among prospective studies for bacterial laccase genes, some have included actinomycetes, but only a few studies have characterized the enzyme produced. Thus, we have isolated a laccase-producing actinomycete from forest soil under restoration process and further aimed to characterize its produced enzyme. The isolate SB086 was assigned to the Streptomyces genus by a combination of phenotypical, chemical and phylogenetic properties. Our data indicate that the bacterium produces a thermotolerant laccase. The maximum activity was obtained in the pH range 4.0–5.0 and at 50 °C in reaction mixture containing 5 mM CuSO₄; thermal stability was noted at 60 °C and 70 °C—a well-desired characteristic for industry. The active enzyme presented a high molecular mass (over 100 kDa) and was less sensitive to inhibition by metal ions than generally described for bacterial laccases. Our findings support in silico data of bacterial laccase secretion, and reinforce the view that actinomycetes may be a rich source of laccase for industrial application.     

Integrated Proteomics Identified Up-Regulated Focal Adhesion-Mediated Proteins in Human Squamous Cell Carcinoma in an Orthotopic Murine Model

Understanding the molecular mechanisms of oral carcinogenesis will yield important advances in diagnostics, prognostics, effective treatment, and outcome of oral cancer. Hence, in this study we have investigated the proteomic and peptidomic profiles by combining an orthotopic murine model of oral squamous cell carcinoma (OSCC), mass spectrometry-based proteomics and biological network analysis. Our results indicated the up-regulation of proteins involved in actin cytoskeleton organization and cell-cell junction assembly events and their expression was validated in human OSCC tissues. In addition, the functional relevance of talin-1 in OSCC adhesion, migration and invasion was demonstrated. Taken together, this study identified specific processes deregulated in oral cancer and provided novel refined OSCC-targeting molecules.     

On the Prospect of Identifying Adaptive Loci in Recently Bottlenecked Populations

Identifying adaptively important loci in recently bottlenecked populations – be it natural selection acting on a population following the colonization of novel habitats in the wild, or artificial selection during the domestication of a breed – remains a major challenge. Here we report the results of a simulation study examining the performance of available population-genetic tools for identifying genomic regions under selection. To illustrate our findings, we examined the interplay between selection and demography in two species of Peromyscus mice, for which we have independent evidence of selection acting on phenotype as well as functional evidence identifying the underlying genotype. With this unusual information, we tested whether population-genetic-based approaches could have been utilized to identify the adaptive locus. Contrary to published claims, we conclude that the use of the background site frequency spectrum as a null model is largely ineffective in bottlenecked populations. Results are quantified both for site frequency spectrum and linkage disequilibrium-based predictions, and are found to hold true across a large parameter space that encompasses many species and populations currently under study. These results suggest that the genomic footprint left by selection on both new and standing variation in strongly bottlenecked populations will be difficult, if not impossible, to find using current approaches.     

Intrapulmonary Vascular Dilatation Evaluated by 99mTc-MAA Scintigraphy and Its Association with Portal Hypertension in Schistosomiasis

Background

Portal hypertension is responsible for various complications in patients with schistosomiasis, among them intrapulmonary vascular dilations (IPVD). In cirrhotic patients the presence of IPVD is a sign of poor prognosis, but in patients with hepatosplenic schistosomiasis (HSS) there are no studies assessing the significance of this change. The aim of this study was to evaluate the occurrence of IPVD through ^99mTc-MAA scintigraphy in patients with HSS and its relationship with clinical, laboratory, endoscopic and ultrasound parameters.

Methods

Cross-sectional study evaluating 51 patients with HSS. Patients were diagnosed with IPVD when the brain uptake of ^99mTc-MAA was higher than 6%. Subsequently, they were divided according to presence (G1) or absence (G2) of IPVD and variables were compared between groups.

Results

Overall, 51 patients with mean age of 56±12 years were assessed. IPVD was observed in 31 patients (60%). There was no statistically significant differences between groups when clinical, laboratory and endoscopic parameters were compared. Regarding ultrasound parameters, the splenic vein diameter was smaller in G1 (0.9±0.3 cm) compared to G2 (1.2±0.4 cm), p = 0.029.

Conclusion

In patients with HSS, the occurrence of IPVD by ^99mTc-MAA scintigraphy was high and was associated with lower splenic vein diameter, which can be a mechanism of vascular protection against portal hypertension. However, more studies are needed to determine the clinical significance of the early diagnosis and natural evolution of IPVD in this population.