Oryza sativa rice plants contain molecules that activate different quorum-sensing N-acyl homoserine lactone biosensors and are sensitive to the specific AiiA lactonase

Gram-negative bacteria most often use N-acyl homoserine lactones (AHLs) as intercellular quorum-sensing signal molecules. In this study, it was demonstrated that rice plants contain AHL mimic molecules that are very sensitive to the highly specific AiiA lactonase enzyme and can activate three different AHL bacterial biosensors, indicating that the compounds have a homoserine lactone structure and could be AHLs. The possible source and biological significance of this finding are discussed.     

Association of body iron stores with low molecular weight iron and oxidant damage of human atherosclerotic plaques

The association between iron, an oxidant catalyst, and atherosclerosis is controversial. In particular, it is unknown whether: (1) stored iron, namely serum ferritin, is correlated with catalytic iron and oxidant damage of human atherosclerotic plaques; (2) catalytic iron is related to oxidative injury within such plaques; (3) plaque oxidant burden is associated with the severity of atherosclerosis. Thus, we assessed low molecular weight iron (LMWI), which represents the metal catalytically active form, together with fluorescent damage products of lipid peroxidation (FDPL) and lipid hydroperoxides (LOOH), in 38 atherosclerotic plaques surgically removed from 38 patients who had undergone selective carotid endarterectomy. In each patient, the levels of serum ferritin were measured and correlated with those of plaque LMWI and lipoperoxides by the Spearman rank correlation test with Spearman rank correlation coefficient (r(S)) calculation. Moreover, in patients selected from the same study population, we compared plaque analyte levels between two groups with different severity of atherosclerotic carotid stenosis, i.e., <90% (group A, n = 25) or > or =90% (group B, n = 13), and between another two groups without (group C, n = 27) and with (group D, n = 11) associated contralateral carotid stenosis > or =50%, indicative of "extensive" and more severe atherosclerotic disease. In group A patients, serum ferritin was directly and significantly correlated with plaque LMWI (r(S) = 0.46, P < 0.025) and FDPL (r(S) = 0.58, P < 0.005), while its correlation with plaque LOOH, albeit direct, did not attain statistical significance. Moreover, a direct and significant relationship was evident between the plaque content of LMWI and that of both FDPL (r(S) = 0.61, P < 0.0025) and LOOH (r(S) = 0.51, P < 0.025), suggesting a prooxidant role of catalytic iron within human atherosclerotic plaques. Considering the 13 patients of group B, a positive and significant correlation was observed between the levels of serum ferritin and those of plaque LMWI (r(S) = 0.83, P < 0.0001); on the other hand, serum ferritin, as well as plaque LMWI, showed no significant correlation with either plaque FDPL or LOOH, conceivably reflecting the small number of patients belonging to group B. Finally, plaque LMWI, FDPL, and LOOH content was significantly higher in group B than in group A, and in group D than in group C. These data suggest a role for catalytic iron in atherosclerotic plaque oxidation and in the severity of atherosclerosis, which appears indeed associated with plaque oxidant burden.     

Kinetics of albumin- and alpha-fetoprotein-production during rat liver development

Synthesis of most of the plasma proteins is one of the main functions of the hepatocytes. Albumin synthesis is quantitatively the most abundant. In the present study we investigated albumin- and alpha-fetoprotein-gene-expression, and the function of the secretory apparatus during rat liver development. To this purpose we used the method of radioactive biosynthetic labeling of newly synthesized albumin and alpha-fetoprotein (AFP) to monitor the secretory capacity of endodermal cells derived from ventral foregut region (embryonic day 10, E10), and of embryonic and fetal hepatoblasts. Synthesis and secretion of albumin and AFP were already detected in the low numbered ventral foregut endodermal cells; fibrinogen synthesis was detectable in the E12 hepatoblasts, which were in higher number. The whole secretory machinery was functional from the earliest stages of liver development, and the speed of secretion was comparable with that of the adult hepatocytes. There was almost 4-fold increase of hepatoblasts cell volume in fetal stage compared with embryonic stage. The model used suggests that the hepatocyte secretory apparatus is already functional before the emergence of the liver bud. This is the first comparative report to analyze the hepatocyte secretory function, cell proliferation and cell volume during liver development.     

Limits of life in MgCl2-containing environments: chaotropicity defines the window

The biosphere of planet Earth is delineated by physico-chemical conditions that are too harsh for, or inconsistent with, life processes and maintenance of the structure and function of biomolecules. To define the window of life on Earth (and perhaps gain insights into the limits that life could tolerate elsewhere), and hence understand some of the most unusual biological activities that operate at such extremes, it is necessary to understand the causes and cellular basis of systems failure beyond these windows. Because water plays such a central role in biomolecules and bioprocesses, its availability, properties and behaviour are among the key life-limiting parameters. Saline waters dominate the Earth, with the oceans holding 96.5% of the planet's water. Saline groundwater, inland seas or saltwater lakes hold another 1%, a quantity that exceeds the world's available freshwater. About one quarter of Earth's land mass is underlain by salt, often more than 100 m thick. Evaporite deposits contain hypersaline waters within and between their salt crystals, and even contain large subterranean salt lakes, and therefore represent significant microbial habitats. Salts have a major impact on the nature and extent of the biosphere, because solutes radically influence water's availability (water activity) and exert other activities that also affect biological systems (e.g. ionic, kosmotropic, chaotropic and those that affect cell turgor), and as a consequence can be major stressors of cellular systems. Despite the stressor effects of salts, hypersaline environments can be heavily populated with salt-tolerant or -dependent microbes, the halophiles. The most common salt in hypersaline environments is NaCl, but many evaporite deposits and brines are also rich in other salts, including MgCl(2) (several hundred million tonnes of bischofite, MgCl(2).6H(2)O, occur in one formation alone). Magnesium (Mg) is the third most abundant element dissolved in seawater and is ubiquitous in the Earth's crust, and throughout the Solar System, where it exists in association with a variety of anions. Magnesium chloride is exceptionally soluble in water, so can achieve high concentrations (> 5 M) in brines. However, while NaCl-dominated hypersaline environments are habitats for a rich variety of salt-adapted microbes, there are contradictory indications of life in MgCl(2)-rich environments. In this work, we have sought to obtain new insights into how MgCl(2) affects cellular systems, to assess whether MgCl(2) can determine the window of life, and, if so, to derive a value for this window. We have dissected two relevant cellular stress-related activities of MgCl(2) solutions, namely water activity reduction and chaotropicity, and analysed signatures of life at different concentrations of MgCl(2) in a natural environment, namely the 0.05-5.05 M MgCl(2) gradient of the seawater : hypersaline brine interface of Discovery Basin - a large, stable brine lake almost saturated with MgCl(2), located on the Mediterranean Sea floor. We document here the exceptional chaotropicity of MgCl(2), and show that this property, rather than water activity reduction, inhibits life by denaturing biological macromolecules. In vitro, a test enzyme was totally inhibited by MgCl(2) at concentrations below 1 M; and culture medium with MgCl(2) concentrations above 1.26 M inhibited the growth of microbes in samples taken from all parts of the Discovery interface. Although DNA and rRNA from key microbial groups (sulfate reducers and methanogens) were detected along the entire MgCl(2) gradient of the seawater : Discovery brine interface, mRNA, a highly labile indicator of active microbes, was recovered only from the upper part of the chemocline at MgCl(2) concentrations of less than 2.3 M. We also show that the extreme chaotropicity of MgCl(2) at high concentrations not only denatures macromolecules, but also preserves the more stable ones: such indicator molecules, hitherto regarded as evidence of life, may thus be misleading signatures in chaotropic environments. Thus, the chaotropicity of MgCl(2) would appear to be a window-of-life-determining parameter, and the results obtained here suggest that the upper MgCl(2) concentration for life, in the absence of compensating (e.g. kosmotropic) solutes, is about 2.3 M.     

Pendrin overexpression affects cell volume recovery, intracellular pH and chloride concentration after hypotonicity-induced cell swelling

The pendrin (SLC26A4 or PDS) gene is responsible, when mutated, for the Pendred syndrome, a recessive disorder characterized by sensorineural hearing loss often accompanied by thyroid dysfunctions. Pendrin protein is an anion exchanger and we focused on a still unexplored function that it might play in view of its importance in the inner ear: Cl(-) fluxes regulation during cellular volume control. We challenged HEK-293 Phoenix cells over-expressing wild type pendrin (PDS HEK cells) together with the EYFP (Enhanced Yellow Fluorescent Protein) or over-expressing the EYFP alone (control HEK cells) with hypo-osmolar solutions. Taking advantage of the confocal optical sectioning we measured the cell volume. In addition, we determined the intracellular pH and chloride concentration with fluorescent probes (EYFP and seminaphthorhodafluor-5F, SNARF-5F). Consequently, we could estimate simultaneously Cl(-) fluxes, cellular volume and intracellular pH variations. Cl(-) movements markedly differed between PDS and control HEK cells upon hypotonic shock and are accompanied by an attenuation of the swelling induced pH drop in PDS HEK cells. The contemporary measurements of the three variables not yet reported in living cells, allowed to assess a possible influence of pendrin upregulation in volume homeostasis and evidenced its participation to Cl(-) fluxes.     

Study of 'Redhaven' peach and its white-fleshed mutant suggests a key role of CCD4 carotenoid dioxygenase in carotenoid and norisoprenoid volatile metabolism

Background  

Carotenoids are plant metabolites which are not only essential in photosynthesis but also important quality factors in determining the pigmentation and aroma of flowers and fruits. To investigate the regulation of carotenoid metabolism, as related to norisoprenoids and other volatile compounds in peach (Prunus persica L. Batsch.), and the role of carotenoid dioxygenases in determining differences in flesh color phenotype and volatile composition, the expression patterns of relevant carotenoid genes and metabolites were studied during fruit development along with volatile compound content. Two contrasted cultivars, the yellow-fleshed 'Redhaven' (RH) and its white-fleshed mutant 'Redhaven Bianca' (RHB) were examined.     

Methotrexate-Loaded Chitosan- and Glycolchitosan-Based Nanoparticles: A Promising Strategy for the Administration of the Anticancer Drug to Brain Tumors

Brain tumor treatment employing methotrexate (MTX) is limited by the efflux mechanism of Pg-p on the blood–brain barrier. We aimed to investigate MTX-loaded chitosan or glycol chitosan (GCS) nanoparticles (NPs) in the presence and in the absence of a coating layer of Tween 80 for brain delivery of MTX. The effect of a low Tween 80 concentration was evaluated. MTX NPs were formulated following the ionic gelation technique and size and zeta potential measurements were acquired. Transport across MDCKII-MDR1 monolayer and cytotoxicity studies against C6 glioma cell line were also performed. Cell/particles interaction was visualized by confocal microscopy. The particles were shown to be cytotoxic against C6 cells line and able to overcome MDCKII-MDR1 cell barrier. GCS-based NPs were the most cytotoxic NPs. Confocal observations highlighted the internalization of Tween 80-coated fluorescent NPs more than Tween 80-uncoated NPs. The results suggest that even a low concentration of Tween 80 is sufficient for enhancing the transport of MTX from the NPs across MDCKII-MDR1 cells. The nanocarriers represent a promising strategy for the administration of MTX to brain tumors which merits further investigations under in vivo conditions.     

The genomic ancestry of individuals from different geographical regions of Brazil is more uniform than expected

Based on pre-DNA racial/color methodology, clinical and pharmacological trials have traditionally considered the different geographical regions of Brazil as being very heterogeneous. We wished to ascertain how such diversity of regional color categories correlated with ancestry. Using a panel of 40 validated ancestry-informative insertion-deletion DNA polymorphisms we estimated individually the European, African and Amerindian ancestry components of 934 self-categorized White, Brown or Black Brazilians from the four most populous regions of the Country. We unraveled great ancestral diversity between and within the different regions. Especially, color categories in the northern part of Brazil diverged significantly in their ancestry proportions from their counterparts in the southern part of the Country, indicating that diverse regional semantics were being used in the self-classification as White, Brown or Black. To circumvent these regional subjective differences in color perception, we estimated the general ancestry proportions of each of the four regions in a form independent of color considerations. For that, we multiplied the proportions of a given ancestry in a given color category by the official census information about the proportion of that color category in the specific region, to arrive at a "total ancestry" estimate. Once such a calculation was performed, there emerged a much higher level of uniformity than previously expected. In all regions studied, the European ancestry was predominant, with proportions ranging from 60.6% in the Northeast to 77.7% in the South. We propose that the immigration of six million Europeans to Brazil in the 19th and 20th centuries--a phenomenon described and intended as the "whitening of Brazil"--is in large part responsible for dissipating previous ancestry dissimilarities that reflected region-specific population histories. These findings, of both clinical and sociological importance for Brazil, should also be relevant to other countries with ancestrally admixed populations.     

Functional magnetic resonance imaging reveals different neural substrates for the effects of orexin-1 and orexin-2 receptor antagonists

Orexins are neuro-modulatory peptides involved in the control of diverse physiological functions through interaction with two receptors, orexin-1 (OX1R) and orexin-2 (OX2R). Recent evidence in pre-clinical models points toward a putative dichotomic role of the two receptors, with OX2R predominantly involved in the regulation of the sleep/wake cycle and arousal, and the OX1R being more specifically involved in reward processing and motivated behaviour. However, the specific neural substrates underlying these distinct processes in the rat brain remain to be elucidated. Here we used functional magnetic resonance imaging (fMRI) in the rat to map the modulatory effect of selective OXR blockade on the functional response produced by D-amphetamine, a psychostimulant and arousing drug that stimulates orexigenic activity. OXR blockade was produced by GSK1059865 and JNJ1037049, two novel OX1R and OX2R antagonists with unprecedented selectivity at the counter receptor type. Both drugs inhibited the functional response to D-amphetamine albeit with distinct neuroanatomical patterns: GSK1059865 focally modulated functional responses in striatal terminals, whereas JNJ1037049 induced a widespread pattern of attenuation characterised by a prominent cortical involvement. At the same doses tested in the fMRI study, JNJ1037049 exhibited robust hypnotic properties, while GSK1059865 failed to display significant sleep-promoting effects, but significantly reduced drug-seeking behaviour in cocaine-induced conditioned place preference. Collectively, these findings highlight an essential contribution of the OX2R in modulating cortical activity and arousal, an effect that is consistent with the robust hypnotic effect exhibited by JNJ1037049. The subcortical and striatal pattern observed with GSK1059865 represent a possible neurofunctional correlate for the modulatory role of OX1R in controlling reward-processing and goal-oriented behaviours in the rat.