Inhibition of protein synthesis in a polyribosome-dependent cell-free system by a specific ribonuclease prepared from the follicles of two different stages of development of the silkmothAntherea pernyi

Summary Crude, cell-free protein-synthesizing systems were prepared from follicles of two different stages of development in the ovariole of the silkmothAntherea pernyi. The efficiency of the translation of natural and synthetic mRNAs in these systems was compared with that in a cell-free wheat germ system. A postmitochondrial extract (S-30) from the follicles almost completely inhibited protein synthesis in a polyribosome-dependent, cell-free systems. A specific ribonuclease, obtained from the post mitochondrial extract by ammonium sulphate precipitation, heat denaturation and DEAE-cellulose chromatography, inhibited polyribosome-dependent protein synthesis. The effect of this specific ribonuclease on the structural integrity of radioactive RNAs and ribosomal subunits, which were isolated from Ehrlich ascites tumor cells, was also studied.     

Mapping of a Gene for Long QT Syndrome to Chromosome 4q25-27

Long QT syndrome (LQTS) is a heterogeneous inherited disorder causing syncope and sudden death from ventricular arrhythmias. A first locus for this disorder was mapped to chromosome 11p15.5. However, locus heterogeneity has been demonstrated in several families, and two other loci have recently been located on chromosomes 7q35-36 and 3p21-24. We used linkage analysis to map the locus in a 65-member family in which LQTS was associated with more marked sinus bradycardia than usual, leading to sinus node dysfunction. Linkage to chromosome 11p15.5, 7q35-36, or 3p21-24 was excluded. Positive linkage was obtained for markers located on chromosome 4q25-27. A maximal LOD score of 7.05 was found for marker D4S402. The identification of a fourth locus for LQTS confirms its genetic heterogeneity. Locus 4q25-27 is associated with a peculiar phenotype within the LQTS entity.     

Invasive and adherent bacterial pathogens co-Opt host clathrin for infection

Infection by the bacterium Listeria monocytogenes depends on host cell clathrin. To determine whether this requirement is widespread, we analyzed infection models using diverse bacteria. We demonstrated that bacteria that enter cells following binding to cellular receptors (termed "zippering" bacteria) invade in a clathrin-dependent manner. In contrast, bacteria that inject effector proteins into host cells in order to gain entry (termed "triggering" bacteria) invade in a clathrin-independent manner. Strikingly, enteropathogenic Escherichia coli (EPEC) required clathrin to form actin-rich pedestals in host cells beneath adhering bacteria, even though this pathogen remains extracellular. Furthermore, clathrin accumulation preceded the actin rearrangements necessary for Listeria entry. These data provide evidence for a clathrin-based entry pathway allowing internalization of large objects (bacteria and ligand-coated beads) and used by "zippering" bacteria as part of a general mechanism to invade host mammalian cells. We also revealed a nonendocytic role for clathrin required for extracellular EPEC infections.     

Risk Factors for Contamination of Hotel Water Distribution Systems by Legionella Species

The Legionella colonization frequency at 385 Greek hotel hot and cold water distribution systems was 20.8%. Legionella contamination was associated with the presence of an oil heater (odds ratio [OR] = 2.04, 95% confidence interval [CI] = 1.12 to 3.70), with the sample temperature (OR = 0.26, 95% CI = 0.1 to 0.5), with seasonal operation (OR = 3.23, 95% CI = 1.52 to 6.87), and with the presence of an independent disinfection system (OR = 0.30, 95% CI = 0.15 to 0.62). The same water temperatures, free-chlorine levels, and pHs differently affect the survival of various Legionella spp.     

Regulation of [<Superscript>3</Superscript>H] <Emphasis Type="SmallCaps">d</Emphasis>-Aspartate Release from Mammalian Isolated Retinae by Hydrogen Sulfide

Hydrogen sulfide (H₂S), can produce pharmacological effects on neural and non-neural tissues from several mammalian species. The present study investigates the pharmacological action of H₂S, (using sodium hydrosulfide, NaHS, and/or sodium sulfide, Na₂S as donors) on amino acid neurotransmission (using [³H] d-aspartate as a marker for glutamate) from isolated, superfused bovine and porcine retinae. Isolated neural retinae were incubated in Krebs solution containing [³H] d-aspartate at 37°C. Release of [³H] d-aspartate was elicited by high potassium (K⁺ 50 mM) pulse. Both NaHS and Na₂S donors caused an inhibition of K⁺-evoked [³H] d-aspartate release from isolated bovine retinae without affecting basal [³H] d-aspartate efflux yielding IC₅₀ values of 0.006 and 6 μm, respectively. Furthermore, NaHS inhibited depolarization-evoked release of [³H] d-aspartate from isolated porcine retinae with an IC₅₀ value of 8 μM. The inhibitory action of NaHS on [³H] d-aspartate release from porcine retinae was blocked by propargyglycine, a selective inhibitor of cystathionine γ-lyase (CSE). Our results indicate that H₂S donors can inhibit amino acid neurotransmission from both isolated bovine and porcine retinae, an effect that is dependent, at least in part, on intramural biosynthesis of H₂S.     

Rosuvastatin 20 mg restores normal HDL-apoA-I kinetics in type 2 diabetes

Catabolism of HDL particles is accelerated in type 2 diabetes, leading to a reduction in plasma residence time, which may be detrimental. Rosuvastatin is the most powerful statin to reduce LDL-cholesterol, but its effects on HDL metabolism in type 2 diabetes remain unknown. We performed a randomized double-blind cross-over trial of 6-week treatment period with placebo or rosuvastatin 20 mg in eight patients with type 2 diabetes. An in vivo kinetic study of HDL-apolipoprotein A-I (apoA-I) with ¹³C leucine was performed at the end of each treatment period. Moreover, a similar kinetic study was carried out in eight nondiabetic normolipidemic controls. Rosuvastatin significantly reduced plasma LDL-cholesterol (−51%), triglycerides (TGs) (−38%), and HDL-TG (−23%). HDL-apoA-I fractional catabolic rate (FCR) was decreased by rosuvastatin (0.25 ± 0.06 vs. 0.32 ± 0.07 pool/day, P = 0.011), leading to an increase in plasma HDL-apoA-I residence time (4.21 ± 1.02 vs. 3.30 ± 0.73 day, P = 0.011). Treatment with rosuvastatin was associated with a concomitant reduction of HDL-apoA-I production rate. The decrease in HDL-apoA-I FCR, induced by rosuvastatin, was correlated with the reduction of plasma TGs and HDL-TG. HDL apoA-I FCR and production rate values in diabetic patients on rosuvastatin were not different from those found in controls. Rosuvastatin is responsible for a 22% reduction of HDL-apoA-I FCR and restores to normal the increased HDL turnover observed in type 2 diabetes. These kinetic modifications may have beneficial effects by increasing HDL plasma residence time.     

Improved isolation of glucuronan from algae and the production of glucuronic acid oligosaccharides using a glucuronan lyase

A new source for the production of bioactive glucuronic acid oligosaccharides (GlcUAOs) from the depolymerization of green seaweed Ulva lactuca glucuronan (Algal glucuronan) has been investigated. Algal glucuronan purification was optimized by the acidic precipitation method which allowed us to separate the polysaccharide mixture extracted from the cell wall of Ulva lactuca using hot water containing sodium oxalate. A series of the GlcUAOs were obtained by enzyme degradation of algal glucuronan with a glucuronan lyase (GL) isolated from Trichoderma strain. The putative bioactive GlcUAOs generated were then purified by size-exclusion chromatography in gram quantity and characterized by ¹H/¹³C NMR spectroscopy and ESI-Q/TOF-mass spectrometry.     

Tropical soils degraded by slash‐and‐burn cultivation can be recultivated when amended with ashes and compost

In many tropical regions, slash‐and‐burn agriculture is considered as a driver of deforestation; the forest is converted into agricultural land by cutting and burning the trees. However, the fields are abandoned after few years because of yield decrease and weed invasion. Consequently, new surfaces are regularly cleared from the primary forest. We propose a reclamation strategy for abandoned fields allowing and sustaining re‐cultivation. In the dry region of south‐western Madagascar, we tested, according to a split‐plot design, an alternative selective slash‐and‐burn cultivation technique coupled with compost amendment on 30–year‐old abandoned fields. Corn plants (Zea mays L.) were grown on four different types of soil amendments: no amendment (control), compost, ashes (as in traditional slash‐and‐burn cultivation), and compost + ashes additions. Furthermore, two tree cover treatments were applied: 0% tree cover (as in traditional slash‐and‐burn cultivation) and 50% tree cover (selective slash‐and‐burn). Both corn growth and soil fertility parameters were monitored during the growing season 2015 up to final harvest. The amendment compost + ashes strongly increased corn yield, which was multiplied by 4–5 in comparison with ashes or compost alone, reaching 1.5 t/ha compared to 0.25 and 0.35 t/ha for ashes and compost, respectively. On control plots, yield was negligible as expected on these degraded soils. Structural equation modeling evidenced that compost and ashes were complementary fertilizing pathways promoting soil fertility through positive effects on soil moisture, pH, organic matter, and microbial activity. Concerning the tree cover treatment, yield was reduced on shaded plots (50% tree cover) compared to sunny plots (0% tree cover) for all soil amendments, except ashes. To conclude, our results provide empirical evidence on the potential of recultivating tropical degraded soils with compost and ashes. This would help mitigating deforestation of the primary forest by increasing lifespan of agricultural lands.     

Proteomic profiling of cell envelope-associated proteins from Staphylococcus aureus

The emergence of highly virulent community acquired Staphylococcus aureus and continued progression of resistance to multiple antimicrobials, including methicillin and vancomycin, marks the reemergence of S. aureus as a serious health care threat. Investigation of proteins localized to the cell surface could help to elucidate mechanisms of virulence and antibiotic resistance in S. aureus. In this study, proteomic profiling methods were developed to solubilize, display, and evaluate abundance levels of proteins present in the supernatants of the lysostaphin-digested cell envelope from cultured vancomycin-intermediate S. aureus (VISA) cells. Combining approaches of 2-DE or chromatographic separation of proteins with MS analyses resulted in the identification of 144 proteins of particular interest. Of these proteins, 48 contained predicted cell wall localization or export signal motifs, including 14 with distinct covalent peptidoglycan-anchor sites, four of which are uncharacterized to date. One of the two most abundant cell envelope proteins, which showed remarkably high variations in MW and pI in the 2-DE gel display, was the S. aureus surface protein G. The display of numerous secreted proteins that are not covalently cell wall-anchored, suggests that, in the exponential growth phase, secreted proteins can be retained physiologically in the cell envelope and may interact with cell wall-anchored proteins and carbohydrate structures in a manner yet to be determined. The remaining 96 proteins, devoid of recognizable motifs, were repeatedly profiled in the VISA cell envelope fractions. We describe a novel semiquantitative method to determine abundance factors of such proteins in 2-DE gels of cell envelope fractions relative to whole cell lysates and discuss these data in the context of true cell envelope localization versus experimentally caused cell lysis.