Comparative 5-doxylstearoyllecithin and 3-doxylcholestane EPR spin labeling study of phospholipid bilayer perturbation by different oxidized lecithin species

A 3-doxylcholestane spin label was employed in addition to 5-doxylstearoyl lecithin for a more detailed study of the different effects exerted by variously oxidized lecithins on fatty acid alignment in phospholipid planar bilayers. Either spin label was enclosed in oriented PLPC planar samples also containing in turn a variety of conjugated-dienes lecithins and cleaved chain lecithins, in order to monitor EPR spectral angular dependence loss. Data obtained by use of arachidonoyl-hydroxystearoyl-PC and palmitoyl-hydroxylinoleoyl-PC confirm that the 5-DSPC nitroxide ring almost completely retains its orientation in CD-PCs-containing planar membranes, in contrast with angular dependence loss observed in the presence of the CC-PC molecular species palmitoyl-oxononanoyl-PC and palmitoyl-oxovaleroyl-PC, already seen with cleaved-chain palmitoyl-glutaroyl-PC and palmitoyl-azelaoyl-PC. However, the 3-DC nitroxide ring also loses its orientation with CD-PCs, in addition to being disoriented by cleaved chain-lecithins, similarly to 5DSPC. Joint information from the two spin labels will help to clarify whether OXPC-related disordering involved the whole bilayer structure or only the hydrophobic core. In addition, the propensity of different OXPCs to form bilayer vesicles in water suspension was also determined by Sepharose 4B gel-chromatography. The results suggest that CD-PCs might yield SPB bilayer structures with a disordered hydrophobic core, while pure CC-PC more probably forms non-bilayer disordered structures, possibly micelles or mixed micelle/bilayers.     

Short-term effects of thyroid hormones during development: Focus on signal transduction

Extranuclear or nongenomic effects of thyroid hormones are mediated by receptors located at the plasma membrane or inside cells, and are independent of protein synthesis. Recently the αVβ3 integrin was identified as a cell membrane receptor for thyroid hormones, and a wide variety of nongenomic effects have now been shown to be induced through binding of thyroid hormones to this receptor. However, also other thyroid hormone receptors can produce nongenomic effects, including the cytoplasmic TRα and TRβ receptors and probably also a G protein-coupled membrane receptor, and increasing importance is now given to thyroid hormone metabolites like 3,5-diiodothyronine and reverse T₃ that can mimick some nongenomic effects of T₃ and T₄. Signal transduction from the αVβ3 integrin may proceed through at least three independent pathways (protein kinase C, Src or mitogen-activated kinases) but the details are still unknown. Thyroid hormones induce nongenomic effects on at least three important Na⁺-dependent transport systems, the Na⁺/K⁺-ATPase, the Na⁺/H⁺ exchanger, and amino acid transport System A, leading to a mitogenic response in embryo cells; but modulation of the same transport systems may have different roles in other cells and at different developmental stages. It seems that thyroid hormones in many cases can modulate nongenomically the same targets affected by the nuclear receptors through long-term mechanisms. Recent results on nongenomic effects confirm the old theory that the primary role of thyroid hormones is to keep the steady-state level of functioning of the cell, but more and more mechanisms are discovered by which this goal can be achieved.     

Chromosomal loci important for cotyledon opening under UV-B in Arabidopsis thaliana

Background  

Understanding of the genetic architecture of plant UV-B responses allows extensive targeted testing of candidate genes or regions, along with combinations of those genes, for placement in metabolic or signal transduction pathways.     

Linking Changes in Epithelial Morphogenesis to Cancer Mutations Using Computational Modeling

Most tumors arise from epithelial tissues, such as mammary glands and lobules, and their initiation is associated with the disruption of a finely defined epithelial architecture. Progression from intraductal to invasive tumors is related to genetic mutations that occur at a subcellular level but manifest themselves as functional and morphological changes at the cellular and tissue scales, respectively. Elevated proliferation and loss of epithelial polarization are the two most noticeable changes in cell phenotypes during this process. As a result, many three-dimensional cultures of tumorigenic clones show highly aberrant morphologies when compared to regular epithelial monolayers enclosing the hollow lumen (acini). In order to shed light on phenotypic changes associated with tumor cells, we applied the bio-mechanical IBCell model of normal epithelial morphogenesis quantitatively matched to data acquired from the non-tumorigenic human mammary cell line, MCF10A. We then used a high-throughput simulation study to reveal how modifications in model parameters influence changes in the simulated architecture. Three parameters have been considered in our study, which define cell sensitivity to proliferative, apoptotic and cell-ECM adhesive cues. By mapping experimental morphologies of four MCF10A-derived cell lines carrying different oncogenic mutations onto the model parameter space, we identified changes in cellular processes potentially underlying structural modifications of these mutants. As a case study, we focused on MCF10A cells expressing an oncogenic mutant HER2-YVMA to quantitatively assess changes in cell doubling time, cell apoptotic rate, and cell sensitivity to ECM accumulation when compared to the parental non-tumorigenic cell line. By mapping in vitro mutant morphologies onto in silico ones we have generated a means of linking the morphological and molecular scales via computational modeling. Thus, IBCell in combination with 3D acini cultures can form a computational/experimental platform for suggesting the relationship between the histopathology of neoplastic lesions and their underlying molecular defects.     

Resistance of the honey bee, Apis mellifera to the acarian parasite Varroa destructor: behavioural and electroantennographic data

Abstract. One way in which Apis mellifera honey bees resist Varroa destructor is by detection and elimination of nestmates. This study uses behavioural tests and electroanntennography to assess the role of chemostimuli in recognition by honey bees of this acarian ectoparasite. Behavioural tests using living or dead parasites involved observation of honey bee grooming activity (antennation) under controlled conditions in Petri dishes, and removal behaviour (uncapping and elimination of parasitized and unparasitized control brood cells) under natural conditions. Some bees from colonies with both small and large parasite populations showed aggressive behaviour (biting). No difference was observed according to whether the mite was dead or alive. Under natural conditions, bees uncapped more parasitized cells than control cells. Electroantennographic tests were performed to measure sensitivity to various Varroa extracts at three concentrations (10, 20 and 30 Varroa Equivalents). Only 30 Varroa Equivalent methanol extracts made from Varroa collected from brood cells elicited significantly greater antennal response than controls (pure solvent). All three methanol extracts elicited significantly greater antennal response than controls. No response was observed using Varroa extracts made with acetone or hexane. These findings suggest that polar products may act as chemostimuli for recognition of V. destructor by honey bees. Further study will be necessary to determine which polar products are involved in this recognition and assess grooming and removal behaviour using these products.     

Dissecting drug and vehicle metabolic effects in rats by a metabonomic approach

A combined application of high resolution (1)H NMR spectroscopy and multivariate statistical techniques focused on establishing a consistent statistical approach to metabonomic studies was tested. The data reduction, which is preliminary to the application of multivariate analysis to NMR spectra, was carried out by means of two complementary methods: pure Pattern Recognition (PR) and Assigned Signal Analysis (ASA). The simultaneous use of both approaches allowed us to obtain additional information in the analysis of metabonomic data, compared to the use of PR alone. This additional information consists in the possibility of a biochemical interpretation of the effects induced by treatment with xenobiotics, such as drugs or drug vehicles, on the metabolic networks of the systems under investigation. This approach allowed us to ascertain that a single-dose treatment with ST1959 vehicled by Sesame oil affects the production of hepatic glucose associated to an increment of the amino acid ketogenic process.     

Glycosaminoglycans facilitate procathepsin B activation through disruption of propeptide-mature enzyme interactions

Lysosomal cysteine cathepsin B participates in numerous diverse cellular processes. In acquiring its activity, the proregion, which blocks the substrate-binding site in the proenzyme, needs to be cleaved off. Here we demonstrate that polyanionic polysaccharides, glycosaminoglycans (GAGs), can accelerate the autocatalytic removal of the propeptide and subsequent activation of cathepsin B. We show that naturally occurring GAGs such as chondroitin sulfates and heparin, as well as the synthetic analog dextran sulfate, accelerate the processing in a concentration-dependent manner. Heparin oligosaccharides down to the size of tetrasaccharides were efficient in accelerating the procathepsin B processing, whereas disaccharides were without effect. Further, the ability of the GAGs to accelerate procathepsin B processing was sensitive to increasing NaCl concentrations, indicating that electrostatic interaction between the GAGs and procathepsin B are operative in the accelerating effect. Also the processing of the catalytic procathepsin B mutant by wild type cathepsin B was enhanced in the presence of GAGs, suggesting that GAGs induce a conformational change in procathepsin B, converting it into a better substrate. Site-directed mutagenesis showed that His(28), Lys(39), and Arg(40), located within the procathepsin B propeptide, have significant roles in the acceleration of procathepsin B activation induced by short GAGs. Because procathepsin B and GAGs often co-localize in vivo, we propose that GAGs may play a physiological role in the activation of procathepsin B.     

Antimicrobial activity of various cationic molecules on foodborne pathogens

Antibacterial effects of various arginine- and lysine-rich polycationic proteins and polymers were evaluated by broth and solid dilution assay on a range of foodborne pathogens, Gram-positive and Gram-negative bacteria. The Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC) of α-poly-l-lysine (poly-lys), α-poly-l-arginine (poly-arg) and protamines from herring sperm (clupeine sulphate) and salmon sperm (salmine sulphate) were determined on Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium, Shigella sonnei, Escherichia coli O157:H7 and Pseudomonas aeruginosa. All these molecules showed antibacterial activity on all strains with different MIC and MBC values. The molecular mechanisms underlying the effect of α-poly-l-arginine might be related to the entrance of the molecule into the cell. In fact α-poly-l-arginine labelled with 7-Diethylamino coumarin-3-carboxylic acid, succinimidyl ester (DEAC,SE) showed ability to permeate the cell membrane of B. cereus and E. coli O157:H7.     

Feijoa sellowiana derived natural Flavone exerts anti-cancer action displaying HDAC inhibitory activities

Curative properties of some medicinal plants such as the Feijoa sellowiana Bert. (Myrtaceae), have been often claimed, although the corresponding molecular mechanism(s) remain elusive. We report here that the Feijoa acetonic extract exerts anti-cancer activities on solid and hematological cancer cells. Feijoa extract did not show toxic effects on normal myeloid progenitors thus displaying a tumor-selective activity. In the Feijoa acetonic extract, fractionation and subsequent purification and analyses identified Flavone as the active component. Flavone induces apoptosis which is accompanied by caspase activation and p16, p21 and TRAIL over-expression in human myeloid leukemia cells. Use of ex vivo myeloid leukemia patients blasts confirms that both the full acetonic Feijoa extract and its derived Flavone are able to induce apoptosis. In both cell lines and myeloid leukemia patients blasts the apoptotic activity of Feijoa extract and Flavone is accompanied by increase of histone and non-histone acetylation levels and by HDAC inhibition. Our findings show for the first time that the Feijoa apoptotic active principle is the Flavone and that this activity correlates with the induction of HDAC inhibition, supporting the hypothesis of its epigenetic pro-apoptotic regulation in cancer systems.