Pyrrolomycins as potential anti-staphylococcal biofilms agents

With the goal of discovering new anti-infective agents active against microbial biofilms, this investigation focused on some natural pyrrolomycins, a family of halogenated pyrrole antibiotics. In this study the anti-staphylococcal biofilm activity of pyrrolomycins C, D, F1, F2a, F2b, F3 and of the synthesized related compounds I, II, III were investigated. The susceptibility of six staphylococcal biofilms was determined by methyltiazotetrazolium staining. Most of the compounds were active at concentrations of 1.5 μg ml^?1 with significant inhibition percentages. A few of the compounds were active at the lowest screening concentration of 0.045 μg ml^?1. The population log reduction of activity against the two best biofilm forming Staphylococcus aureus strains as determined by viable plate counts is also reported. In order to adequately assess the utility of these compounds, their toxicity against human cells was evaluated. It is concluded that pyrrolomycins and synthetic derivatives are promising compounds for developing novel effective chemical countermeasures against staphylococcal biofilms.     

Impact of metal accumulation on Quercus ilex L. leaf traits

Plant and Soil - The aims of this research were: i) to compare Cr, Cu, Ni and Pb concentrations in Quercus ilex L. leaves collected at urban/industrial and urban areas; ii) to investigate the main...     

Genetic and molecular characterization of the human Osteosarcoma 3AB‐OS cancer stem cell line: A possible model for studying osteosarcoma origin and stemness

Finding new treatments targeting cancer stem cells (CSCs) within a tumor seems to be critical to halt cancer and improve patient survival. Osteosarcoma is an aggressive tumor affecting adolescents, for which there is no second‐line chemotherapy. Uncovering new molecular mechanisms underlying the development of osteosarcoma and origin of CSCs is crucial to identify new possible therapeutic strategies. Here, we aimed to characterize genetically and molecularly the human osteosarcoma 3AB‐OS CSC line, previously selected from MG63 cells and which proved to have both in vitro and in vivo features of CSCs. Classic cytogenetic studies demonstrated that 3AB‐OS cells have hypertriploid karyotype with 71–82 chromosomes. By comparing 3AB‐OS CSCs to the parental cells, array CGH, Affymetrix microarray, and TaqMan® Human MicroRNA array analyses identified 49 copy number variations (CNV), 3,512 dysregulated genes and 189 differentially expressed miRNAs. Some of the chromosomal abnormalities and mRNA/miRNA expression profiles appeared to be congruent with those reported in human osteosarcomas. Bioinformatic analyses selected 196 genes and 46 anticorrelated miRNAs involved in carcinogenesis and stemness. For the first time, a predictive network is also described for two miRNA family (let‐7/98 and miR‐29a,b,c) and their anticorrelated mRNAs (MSTN, CCND2, Lin28B, MEST, HMGA2, and GHR), which may represent new biomarkers for osteosarcoma and may pave the way for the identification of new potential therapeutic targets. J. Cell. Physiol. 228: 1189–1201, 2013. © 2012 Wiley Periodicals, Inc.     

Neurogenin 2 regulates progenitor cell-cycle progression and Purkinje cell dendritogenesis in cerebellar development

By serving as the sole output of the cerebellar cortex, integrating a myriad of afferent stimuli, Purkinje cells (PCs) constitute the principal neuron in cerebellar circuits. Several neurodegenerative cerebellar ataxias feature a selective cell-autonomous loss of PCs, warranting the development of regenerative strategies. To date, very little is known as to the regulatory cascades controlling PC development. During central nervous system development, the proneural gene neurogenin 2 (Neurog2) contributes to many distinct neuronal types by specifying their fate and/or dictating development of their morphological features. By analyzing a mouse knock-in line expressing Cre recombinase under the control of Neurog2 cis-acting sequences we show that, in the cerebellar primordium, Neurog2 is expressed by cycling progenitors cell-autonomously fated to become PCs, even when transplanted heterochronically. During cerebellar development, Neurog2 is expressed in G1 phase by progenitors poised to exit the cell cycle. We demonstrate that, in the absence of Neurog2, both cell-cycle progression and neuronal output are significantly affected, leading to an overall reduction of the mature cerebellar volume. Although PC fate identity is correctly specified, the maturation of their dendritic arbor is severely affected in the absence of Neurog2, as null PCs develop stunted and poorly branched dendrites, a defect evident from the early stages of dendritogenesis. Thus, Neurog2 represents a key regulator of PC development and maturation.     

Presymbiotic growth and sporal morphology are affected in the arbuscular mycorrhizal fungus Gigaspora margarita cured of its endobacteria

Some arbuscular mycorrhizal fungi contain endocellular bacteria. In Gigaspora margarita BEG 34, a homogenous population of beta-Proteobacteria is hosted inside the fungal spore. The bacteria, named Candidatus Glomeribacter gigasporarum, are vertically transmitted through fungal spore generations. Here we report how a protocol based on repeated passages through single-spore inocula caused dilution of the initial bacterial population eventually leading to cured spores. Spores of this line had a distinct phenotype regarding cytoplasm organization, vacuole morphology, cell wall organization, lipid bodies and pigment granules. The absence of bacteria severely affected presymbiotic fungal growth such as hyphal elongation and branching after root exudate treatment, suggesting that Ca. Glomeribacter gigasporarum is important for optimal development of its fungal host. Under laboratory conditions, the cured fungus could be propagated, i.e. could form mycorrhizae and sporulate, and can therefore be considered as a stable variant of the wild type. The results demonstrated that - at least for the G. margarita BEG 34 isolate - the absence of endobacteria affects the spore phenotype of the fungal host, and causes delays in the growth of germinating mycelium, possibly affecting its ecological fitness. This cured line is the first manipulated and stable isolate of an arbuscular mycorrhizal fungus.     

HDL Size is More Accurate than HDL Cholesterol to Predict Carotid Subclinical Atherosclerosis in Individuals Classified as Low Cardiovascular Risk

Background

Misclassification of patients as low cardiovascular risk (LCR) remains a major concern and challenges the efficacy of traditional risk markers. Due to its strong association with cholesterol acceptor capacity, high-density lipoprotein (HDL) size has been appointed as a potential risk marker. Hence, we investigate whether HDL size improves the predictive value of HDL-cholesterol in the identification of carotid atherosclerotic burden in individuals stratified to be at LCR.

Methods and Findings

284 individuals (40–75 years) classified as LCR by the current US guidelines were selected in a three-step procedure from primary care centers of the cities of Campinas and Americana, SP, Brazil. Apolipoprotein B-containing lipoproteins were precipitated by polyethylene glycol and HDL size was measured by dynamic light scattering (DLS) technique. Participants were classified in tertiles of HDL size (<7.57; 7.57–8.22; >8.22 nm). Carotid intima-media thickness (cIMT) <0.90 mm (80^th percentile) was determined by high resolution ultrasonography and multivariate ordinal regression models were used to assess the association between cIMT across HDL size and levels of lipid parameters. HDL-cholesterol was not associated with cIMT. In contrast, HDL size >8.22 nm was independently associated with low cIMT in either unadjusted and adjusted models for age, gender and Homeostasis Model Assessment 2 index for insulin sensitivity, ethnicity and body mass index (Odds ratio 0.23; 95% confidence interval 0.07–0.74, p = 0.013).

Conclusion

The mean HDL size estimated with DLS constitutes a better predictor for subclinical carotid atherosclerosis than the conventional measurements of plasma HDL-cholesterol in individuals classified as LCR.     

Irreversible gelation of thermally unfolded proteins: structural and mechanical properties of lysozyme aggregates

The formation of protein aggregates is important in many fields of life science and technology. The morphological and mechanical properties of protein solutions depend upon the molecular conformation and thermodynamic and environmental conditions. Non-native or unfolded proteins may be kinetically trapped into irreversible aggregates and undergo precipitation or gelation. Here, we study the thermal aggregation of lysozyme in neutral solutions. We characterise the irreversible unfolding of lysozyme by differential scanning calorimetry. The structural properties of aggregates and their mechanisms of formation with the eventual gelation are studied at high temperature by spectroscopic, rheological and scattering techniques. The experiments show that irreversible micron-sized aggregates are organised into larger clusters according to a classical mechanism of diffusion and coagulation, which leads to a percolative transition at high concentrations. At a smaller length scale, optical and atomic force microscopy images reveal the existence of compact aggregates, which are the origin of the aggregation irreversibility.