GABAB receptor intracellular trafficking after internalization in Paramecium

The number of neurotransmitter receptors on the plasma membrane is regulated by the traffic of intracellular vesicles. Golgi-derived vesicles provide newly synthesized receptors to the cell surface, whereas clathrin-coated vesicles are the initial vehicles for sequestration of surface receptors, which are ultimately degraded or recycled. We have previously shown that GABAB receptors display a punctuate vesicular pattern dispersed on the cell surface and throughout the cytoplasm and are internalized via clathrin-dependent and -independent endocytosis. Here we have studied constitutive GABAB receptor trafficking after internalization in Paramecium primaurelia by confocal laser scanning microscopy and multiple immunofluorescence analysis. After internalization, receptors are targeted to the early endosomes characterized by the molecular markers EEA1 and rab5. Some of these receptors, destined for recycling back to the plasma membrane, traffic from the early endosomes to the endosomal recycling compartment that is characterized by the presence of rab4-immunoreactivity (IR). Receptors that are destined for degradation exit the endosomal pathway at the early endosomes and traffic to the late endosome-lysosome pathway. In fact, some of the GABAB-positive compartments were identified as lysosomal structures by double staining with the lysosomal marker LAMP-1. GABAB vesicle structures also colocalize with TGN38-IR and rab11-IR. TGN38 and rab11 are proteins found in association with post-Golgi and recycling endosomes, respectively.     

Interplay between Structural and Thermoelectric Properties in Epitaxial Sb2+xTe3 Alloys

In recent years strain engineering is proposed in chalcogenide superlattices (SLs) to shape in particular the switching functionality for phase change memory applications. This is possible in Sb₂Te₃/GeTe heterostructures leveraging on the peculiar behavior of Sb₂Te₃, in between covalently bonded and weakly bonded materials. In the present study, the structural and thermoelectric (TE) properties of epitaxial Sb_2+xTe₃ films are shown, as they represent an intriguing option to expand the horizon of strain engineering in such SLs. Samples with composition between Sb₂Te₃ and Sb₄Te₃ are prepared by molecular beam epitaxy. A combination of X‐ray diffraction and Raman spectroscopy, together with dedicated simulations, allows unveiling the structural characteristics of the alloys. A consistent evaluation of the structural disorder characterizing the material is drawn as well as the presence of both Sb₂ and Sb₄ slabs is detected. A strong link exists among structural and TE properties, the latter having implications also in phase change SLs. A further improvement of the TE performances may be achieved by accurately engineering the intrinsic disorder. The possibility to tune the strain in designed Sb_2+xTe₃/GeTe SLs by controlling at the nanoscale the 2D character of the Sb_2+xTe₃ alloys is envisioned.     

Histatin-induced alterations in Candida albicans: a microscopic and submicroscopic comparison

Despite the numerous studies performed in an attempt to clarify the issue, the mechanism of action of salivary histatins remains unclear. The aim of the present study was to correlate histatin-induced morphological changes in Candida albicans by fluorescence microscopy (FM), transmission electron microscopy (TEM), and high resolution scanning electron microscopy (HRSEM). Each of the fluorescent dyes used by FM (i.e., tetramethylrhodamine methyl ester perchlorate for mitochondrial potential, Lysotracker for lysosome acidic compartment, and 4',6-diamino-2-phenylindole dihydrochloride for DNA) exhibited a specific staining in control cells. Following histatin treatment, we observed a recurring staining pattern, corresponding to fluorescence concentration along the cell periphery, suggesting a loss of dye specificity. To assess histatin-induced cytoplasmic modifications, ultrastructural analysis was then carried out. After treatments with histatins, TEM revealed characteristic intracellular modifications including: vacuole overgrowth, nuclear disappearance, loss of organelle identity, as well as the appearance of electron-dense membranes, likely of mitochondrial origin. Additionally, structures resembling autophagosomes were occasionally observed. By HRSEM, mitochondrial swelling was invariably the first sign of a histatin-induced effect. Other modifications included intracellular membrane disarrangement, organelles in disarray, and a large central cavity with deformed bodies displaced to the cell periphery, similar to what was detected by TEM. In summary, our study illustrates the occurrence of ultrastructural modifications following administration of histatins. Observations made with FM, TEM, and HRSEM provided different views of the same signs, demonstrating a definite action of histatins on C. albicans morphology. The possible functional meanings of these morphological results is discussed in light of the most recent biochemical data on histatin fungicidal activity.     

Long-term transport behavior of psychoactive compounds in sewage-affected groundwater

The present study provides a model-based characterization of the long-term transport behavior of five psychoactive compounds (meprobamate, pyrithyldione, primidone, phenobarbital and phenylethylmalonamide) introduced into groundwater via sewage irrigation in Berlin, Germany. Compounds are still present in the groundwater despite the sewage farm closure in the year 1980. Due to the limited information on (i) compound concentrations in the source water and (ii) substance properties, a total of 180 cross-sectional model realizations for each compound were carried out, covering a large range of possible parameter combinations. Results were compared with the present-day contamination patterns in the aquifer and the most likely scenarios were identified based on a number of model performance criteria. The simulation results show that (i) compounds are highly persistent under the present field conditions, and (ii) sorption is insignificant. Thus, back-diffusion from low permeability zones appears as the main reason for the compound retardation.     

TNF-α Blocker Effect of Naringenin-Loaded Sericin Microparticles that Are Potentially Useful in the Treatment of Psoriasis

This study aims to evaluate the effect of combined use of the racemic flavanone Naringenin (NRG) and the protein sericin as TNF-α blockers. Sericin (SMs) and (R/S) NRG-loaded Sericin (SNRGMs) microparticles were prepared by spray-drying, characterized in terms of morphology and particle size distribution, and encapsulation efficiency was determined. Concerning morphology and particle size distribution of microparticles, results indicated that they were not affected by the presence of NRG. The encapsulation efficiency was almost quantitative (93%), thus proving that sericin can be advantageously loaded with (R/S) NRG. Biological evaluation of (R/S) NRG, SMs and SNRGMs was then performed in lipopolysaccharide (LPS)-stimulated human peripheral blood mononuclear cells (hPBMC). SNRGMs resulted cytotoxic at the higher dose used (200 μg/mL) and the effect was greater than (R/S) NRG alone. Moreover, even if sericin alone was not effective in suppressing LPS-induced serum TNF-α levels, SNRGMs loaded with 9.3% of (R/S) NRG were significantly more potent than (R/S) NRG alone. In summary, this study provides the proof of concept that sericin-based microspheres loaded with TNF-α-blockers could contribute to the down regulation of the cytokine and represents the starting point for the development of new topical formulations for the treatment of middle-stage psoriasis.     

Mean stress relaxation during cyclic straining of high strength aluminum alloys

Cycle-dependent relaxation may alter mean stress values and thus affect fatigue crack initiation life. This phenomenon is an issue both for accuracy of estimated fatigue lives and for the success of methods of intentionally introducing beneficial mean stresses. Although rigorous plasticity theories may describe cycle-dependent relaxation, it is not feasible to incorporate their complex mathematics into strain-based life estimates when loading histories contain millions of cycles. Empirical models are, on the other hand, more numerically efficient and, therefore, for the present purpose, constitute a better choice for modeling this transient phenomenon. Experiments have been performed to study mean stress relaxation in aluminum alloys 7075-T6511 and 7249-T76511. Preliminary tests were also conducted on alloy 7475-T651. Two empirical models are used to illustrate the experimentally observed cycle-dependent relaxation.     

Study of different kinds of “Pesto Genovese” by the analysis of their volatile fraction and chemometric methods

The volatile fraction of different kinds of Pestogenovese, a typical Italian basil-based pasta sauce, was analysed by Headspace Sorptive Extraction (HSSE)-Gas Chromatography–Mass Spectrometry (GC–MS) coupled with chemometric methods. Three kinds of commercial samples were considered: (a) non heat-processed shop manufactured, (b) heat-processed industrial and (c) non heat-processed industrial samples. The category of heat-processed samples was easily discriminated by the amounts of the terpene hydrocarbon α-terpinene. In order to distinguish the three categories, multivariate statistical analysis was then performed. Good prediction results were obtained by the combination of Linear Discriminant Analysis (LDA) and Stepwise LDA (STEPLDA): the percentage of correct predictions was 92 for food industry manufactured non heat-processed samples and 100 both for shop manufactured, non heat-processed samples, and for food industry manufactured, heat-processed samples.     

Antifungal activity of Meyerozyma guilliermondii: Identification of active compounds synthesized during dough fermentation and their effect on long-term storage of wheat bread

Preliminarily, 146 strains of yeasts were screened for the antifungal activity toward the indicator Penicillium roqueforti DPPMAF1. The strain Meyerozyma guilliermondii LCF1353 was selected and used for dough fermentation. The water/salt soluble extract of the dough was analyzed by HPLC and GC/MS-SPME. The synthesis of the extracellular cell wall-degrading enzyme β-1,3-glucanase and ethyl-acetate was shown. The effect on conidia germination mainly suggested a fungistatic activity. M. guilliermondii LCF1353 was used as starter for dough fermentation in combination with Wickeramomyces anomalus 1695 and Lactobacillus plantarum 1A7, which were previously selected for antifungal activity. The growth of the strains was monitored by plate count and molecular techniques, and competitive or antagonistic interactions among them were excluded. Bread started with the combination of M. guilliermondii LCF1353, W. anomalus LCF1695 and L. plantarum 1A7 showed a more prolonged shelf life compared to the other breads. Fungal growth was delayed at least until 14 days of storage, under conditions of high artificial inoculum. The bread manufactured with the above combination showed good chemical and textural characteristics and, as shown by sensory analysis, it was appreciated for elasticity, color and taste.