Biofilm formation by Mycobacterium avium isolates originating from humans, swine and birds

Background  

Mycobacterium avium includes the subspecies avium, silvaticum, paratuberculosis and hominissuis, and M. avium subspecies has been isolated from various environments all over the world including from biofilms in water distribution systems. The aim of this study was to examine isolates of M. avium subsp. avium and M. avium subsp. hominissuis of different origin for biofilm formation and to look for correlations between biofilm formation and RFLP-types, and to standardise the method to test for biofilm formation. In order to determine the best screening method, a panel of 14 isolates of M. avium subsp. avium and M. avium subsp. hominissuis, were tested for their ability to form biofilm in microtiter plates under different conditions. Subsequently, 83 additional isolates from humans, swine and birds were tested for biofilm formation. The isolates were tested for the presence of selected genes involved in the synthesis of glycopeptidolipids (GPLs) in the cell wall of M. avium, which is believed to be important for biofilm formation. Colony morphology and hsp65 sequvar were also determined.     

Metabolic effects of weight reduction in obese diabetics and nondiabetics.

A weight loss of about 10 kg was acheived by means of individual periods of total fasting, hypocaloric diets and physical activity in three groups of patients: maturity-onset diabetics, patients with pathological OGTT and overweight persons with normal OGTT. Adipocyte volume decreased in all groups, glucose tolerance improved. IRI curves showed a significant overall lowering and FFA concentrations during OGTT were dimished.     

Intraperitoneal injections of low doses of C75 elicit a behaviorally specific and vagal afferent-independent inhibition of eating in rats

Central and intraperitoneal C75, an inhibitor of fatty acid synthase and stimulator of carnitine palmitoyl-transferase-1, inhibits eating in mice and rats. Mechanisms involved in feeding inhibition after central C75 have been identified, but little is yet known about how systemic C75 might inhibit eating. One issue is whether intraperitoneal C75 reduces food intake in rats by influencing normal physiological controls of food intake or acts nonselectively, for example by eliciting illness or aversion. Another issue relates to whether intraperitoneal C75 acts centrally or, similar to some other peripheral metabolic controls of eating, activates abdominal vagal afferents to inhibit eating. To further address these questions, we investigated the effects of intraperitoneal C75 on spontaneous meal patterns and the formation of conditioned taste aversion (CTA). We also tested whether the eating inhibitory effect of intraperitoneal C75 is vagally mediated by testing rats after either total subdiaphragmatic vagotomy (TVX) or selective subdiaphragmatic vagal deafferentations (SDA). Intraperitoneal injection of 3.2 and 7.5 mg/kg of C75 significantly reduced food intake 3, 12, and 24 h after injection by reducing the number of meals without affecting meal size, whereas 15 mg/kg of C75 reduced both meal number and meal size. The two smaller doses of C75 failed to induce a CTA, but 15 mg/kg C75 did. The eating inhibitory effect of C75 was not diminished in either TVX or SDA rats. We conclude that intraperitoneal injections of low doses of C75 inhibit eating in a behaviorally specific manner and that this effect does not require abdominal vagal afferents.     

Drosophila Knickkopf and Retroactive are needed for epithelial tube growth and cuticle differentiation through their specific requirement for chitin filament organization

Precise epithelial tube diameters rely on coordinated cell shape changes and apical membrane enlargement during tube growth. Uniform tube expansion in the developing Drosophila trachea requires the assembly of a transient intraluminal chitin matrix, where chitin forms a broad cable that expands in accordance with lumen diameter growth. Like the chitinous procuticle, the tracheal luminal chitin cable displays a filamentous structure that presumably is important for matrix function. Here, we show that knickkopf (knk) and retroactive (rtv) are two new tube expansion mutants that fail to form filamentous chitin structures, both in the tracheal and cuticular chitin matrices. Mutations in knk and rtv are known to disrupt the embryonic cuticle, and our combined genetic analysis and chemical chitin inhibition experiments support the argument that Knk and Rtv specifically assist in chitin function. We show that Knk is an apical GPI-linked protein that acts at the plasma membrane. Subcellular mislocalization of Knk in previously identified tube expansion mutants that disrupt septate junction (SJ) proteins, further suggest that SJs promote chitinous matrix organization and uniform tube expansion by supporting polarized epithelial protein localization. We propose a model in which Knk and the predicted chitin-binding protein Rtv form membrane complexes essential for epithelial tubulogenesis and cuticle formation through their specific role in directing chitin filament assembly.     

Spatiotemporal dynamics of regulatory protein recruitment at DNA damage sites

Mammalian cells are constantly threatened by multiple types of DNA lesions arising from various sources like irradiation, environmental agents, replication errors or by-products of the normal cellular metabolism. If not readily detected and repaired these lesions can lead to cell death or to the transformation of cells giving rise to life-threatening diseases like cancer. Multiple specialized repair pathways have evolved to preserve the genetic integrity of a cell. The increasing number of DNA damage sensors, checkpoint regulators, and repair factors identified in the numerous interconnected repair pathways raises the question of how DNA repair is coordinated. In the last decade, various methods have been developed that allow the induction of DNA lesions and subsequent real-time analysis of repair factor assembly at DNA repair sites in living cells. This combination of biophysical and molecular cell biology methods has yielded interesting new insights into the order and kinetics of protein recruitment and identified regulatory sequences and selective loading platforms for the efficient restoration of the genetic and epigenetic integrity of mammalian cells.     

The ATP binding cassette transporter AtMRP5 modulates anion and calcium channel activities in Arabidopsis guard cells

Stomatal guard cells control CO(2) uptake and water loss between plants and the atmosphere. Stomatal closure in response to the drought stress hormone, abscisic acid (ABA), results from anion and K(+) release from guard cells. Previous studies have shown that cytosolic Ca(2+) elevation and ABA activate S-type anion channels in the plasma membrane of guard cells, leading to stomatal closure. However, membrane-bound regulators of abscisic acid signaling and guard cell anion channels remain unknown. Here we show that the ATP binding cassette (ABC) protein AtMRP5 is localized to the plasma membrane. Mutation in the AtMRP5 ABC protein impairs abscisic acid and cytosolic Ca(2+) activation of slow (S-type) anion channels in the plasma membrane of guard cells. Interestingly, atmrp5 insertion mutant guard cells also show impairment in abscisic acid activation of Ca(2+)-permeable channel currents in the plasma membrane of guard cells. These data provide evidence that the AtMRP5 ABC transporter is a central regulator of guard cell ion channel during abscisic acid and Ca(2+) signal transduction in guard cells.     

Complement C2 receptor inhibitor trispanning: a novel human complement inhibitory receptor

The complement system presents a powerful defense against infection and is tightly regulated to prevent damage to self by functionally equivalent soluble and membrane regulators. We describe complement C2 receptor inhibitor trispanning (CRIT), a novel human complement regulatory receptor, expressed on hemopoietic cells and a wide range of tissues throughout the body. CRIT is present in human parasites through horizontal transmission. Serum complement component C2 binds to the N-terminal extracellular domain 1 of CRIT, which, in peptide form, blocks C3 convertase formation and complement-mediated inflammation. Unlike C1 inhibitor, which inhibits the cleavage of C4 and C2, CRIT only blocks C2 cleavage but, in so doing, shares with C1 inhibitor the same functional effect, of preventing classical pathway C3 convertase formation. Ab blockage of cellular CRIT reduces inhibition of cytolysis, indicating that CRIT is a novel complement regulator protecting autologous cells.     

Heavy metal toxicity: cadmium permeates through calcium channels and disturbs the plant water status

Because plant wilting has been described as a consequence of cadmium (Cd2+) toxicity, we investigate Cd2+ effects on plant water losses, gas exchanges and stomatal behaviour in Arabidopsis thaliana L. Effects of 1-week Cd2+ application in hydroponic condition (CdCl2 10-100 micro m) were analyzed. A 10- micro m Cd2+ concentration had no significant effect on the plant-water relationship and carbon assimilation. At higher Cd2+ concentrations, a Cd2+ -dependent decrease in leaf conductance and CO2 uptake was observed despite the photosynthetic apparatus appeared not to be affected as probed by fluorescence measurements. In epidermal strip bioassays, nanomolar Cd2+ concentrations reduced stomatal opening under light in A. thaliana, Vicia faba and Commelina communis. Application of 5 micro m ABA limited the root-to-shoot translocation of cadmium. However, the Cd2+-induced stomatal closure was likely ABA-independent, since a 5-day treatment with 50 micro m Cd2+ did not affect the plant relative water content. Additionally, a similar Cd2+-induced stomatal closure was observed in the ABA insensitive mutant abi1-1. Interestingly, this mutant displayed a higher transpiration rate than the wild type but did not accumulate more Cd2+, arguing that Cd2+ uptake is not dependent only on the transpiration flow. Application of putative calcium channels inhibitors suppressed the inhibitory effect of Cd2+ in epidermal strip experiments, suggesting that Cd2+ could enter the guard cell through calcium channels. Patch-clamp studies with V. faba guard cell protoplasts showed that plasma membrane K+ channels were insensitive to external Cd2+ application whereas Ca2+ channels were found permeable to Cd2+. In conclusion, we propose that Cd2+ affects guard cell regulation in an ABA-independent manner by entering the cytosol via Ca2+ channels.     

Spontaneous haemolytic activity of Atlantic halibut (Hippoglossus hippoglossus L.) and sea bass (Dicentrarchus labrax) serum

The spontaneous haemolytic (SH) activity of sera was compared in groups of cultured halibut and sea bass. The optimum assay temperature was determined for each species and different red blood cell donors were tested. The effects of heat inactivation, storage temperature and of different agents like EDTA, EGTA, yeast cell components and bacterial LPS were compared. Halibut sera gave optimum lysis with sheep red blood cells (RBC) at 16 degrees C whereas sea bass sera showed optimum lysis with rabbit RBC at 37 degrees C. The haemolytic activity of halibut sera was inactivated at 45 degrees C while sea bass sera were inactivated at 56 degrees C. The haemolytic activity of halibut sera was significantly reduced during short-term storage at -80 degrees C, whereas the sea bass sera maintained fairly good activity after 1-year storage at -80 degrees C. EGTA and EDTA inhibited the spontaneous haemolytic activity of sera from both the species. Zymosan and MacroGard from yeast cells also inhibited the haemolytic activity of the sera of both species, whereas LPS had a very slight effect. Considerable variation in haemolytic activity was observed within both the halibut and sea bass groups studied.