Phenolic contents and antioxidant activity of ethanolic extract of Capparis spinosa

Caper plant (Capparis spinosa) extracts have been associated with diverse biological activities including anti-oxidant properties. In this work, we characterized the hydro-ethanolic extract obtained from C. spinosa leaves [hydroethanolic extract of C. spinosa (HECS)] by analyzing the content in anti-oxidant compounds such as polyphenols, flavonoids and anthocyanins. Further, we evaluated HECS antioxidant activities in vitro using bleaching of 1,1-diphenyl-2-picrylhydrazyl radical and ABTS test as well as by pretreatment of HeLa cells exposed to Fe²⁺ or H₂O₂. Our findings indicate that HECS contains high amount of total phenolic compounds and high levels of flavonoids and anthocyanins. Furthermore, HECS exhibited antioxidant activity in both chemical and biological tests. Specially, pretreatment of HeLa cells with different concentrations of the extract conferred protection against lipid peroxidation and modulated activities of two antioxidant enzymes, SOD and catalase. These results revealed HECS antioxidant effects and suggest that C. spinosa leaves are a potential source of natural antioxidant molecules with possible applications in industry and medicine.     

Arg-129 plays a specific role in the confirmation of antithrombin and in the enhancement of factor Xa inhibition by the pentasaccharode sequence of heparin

Small amounts of a variant antithrombin (AT) bearing an Arg-129 to Gln mutation were purified from plasma by means of affinity chromatography on insolubilized herapin at very low ionic strength. As a control, two variant antithrombins, one bearing on Pro-41 to Leu mutation and the other an Arg-47 to His mutation, were purified in the same way. The biochemical characterization of the variants and the kinetic study of thrombin and activated factor X (F Xa) inhibition in the presence of heparin and heparin derivatives suggest that Arg-129 plays a specific role in AT conformation and F Xa inhibition enhancement. Indeed, the purified variant adopted the locked conformation described ,for AT submitted to mild denaturing conditions (Carrell, R.W., Evans, D.Li and Stein, P.E. (1991) Nature 353, 576–578) and resembling the latent form of plasminogen activator inhibitor (PAI) (Mottonen J., Strand, A., Symersky, J., Sweet, R.M., Danley, D.E., Geohegan, K.F., Gerard, R.D. and Goldsmith, E.J. (1992) Nature 355, 270–273). Moreover, the mutant AT was partially reactivated by heparin for thrombin inhibition, but did not respond to the specific pentasaccharide domain of heparin for F Xa inhibition.     

Secretion of active xylanase C from Streptomyces lividans is exclusively mediated by the Tat protein export system

The bacterial twin-arginine translocation (Tat) pathway transports folded proteins across the cytoplasmic membrane. The precursors targeted to the Tat pathway have signal peptides bearing the consensus motif (S/T-R-R-X-F-L-K). The xylanase C (XlnC) of Streptomyces lividans is a 20-kDa secreted enzyme. The XlnC signal peptide is 49 amino acids long and contains the S-R-R-G-F-L-G sequence, which is similar to the twin-arginine consensus motif. In S. lividans, XlnC secretion was impaired in a tatC insertion mutant, which is unable to secrete proteins that are dependent on the Tat system. When the signal peptide of XlnC was replaced by the Sec-dependent signal peptide of xylanase A, XlnC was secreted as an inactive form and demonstrated rapid proteolytic degradation in the culture supernatant, thus indicating that XlnC was specifically secreted through the Tat system. Deletions of the n-region of the XlnC signal sequence showed that a minimum of six amino acids residues preceding the twin-arginine motif was required to secrete XlnC. Replacement of one or both arginines by lysine residues in the twin arginine motif decreased four- and sevenfold, respectively, the enzyme production but did not abolish it. However, pulse chase experiments showed that the half-life of the precursor was from 2 to 3 h instead of 11 min for the wild- type precursor. Since XlnC is not associated with cofactors to exhibit activity, it is therefore a newly identified prokaryotic non-redox Tat substrate.     

Effects of nickel hyperaccumulation on physiological characteristics of Alyssum murale grown on metal contaminated waste amended soil

A pot experiment was conducted to investigate the effect of nickel concentration on physiological characteristics of Alyssum murale when grown in a soil mixed with sewage sludge (at the rate of 2.8%). Two types of sludge were used: agricultural sewage sludge (S1) and industrial sewage sludge with an increasing nickel concentration (S2, S3, and S4). Results showed that Ni in shoots was higher than Ni in roots. A. murale is able to concentrate up to 12730 mg/kg Ni in leaves. The highest dry matter yield was observed with plants grown with agricultural sewage sludge. An addition of S2 and S3 increased shoot biomass. However, application of S4 reduced 40% shoot dry weight as compared to the control Ni treatment did not affect all chlorophyll fluorescence parameters. The F(v)/F(m) ratio was stable between Ni treatments. Photosynthesis rate (A) increased with agricultural sewage sludge, but remained stable with variable Ni rates from the industrial sludge. The chlorophyll content increased with S1, S2 and S3 but it remains constant with S4 when compared to the control Therefore, high nickel concentration did not affect the function of the photosynthetic machine of A. murale.     

Short-term response of wild grapevines (<Emphasis Type="Italic">Vitis vinifera</Emphasis> L<Emphasis Type="Italic">. ssp. sylvestris</Emphasis>) to NaCl salinity exposure: changes of some physiological and molecular characteristics

The physiological and molecular response to salt stress was studied in two wild grapevine (Vitis vinifera L. ssp. sylvestris or Vitis sylvestris) accessions “Khédhayria” and “Houamdia”, previously identified as salt-tolerant and salt-sensitive pair wise. Plants from both accessions were subjected to a progressive salt stress by the use of a nutritional solution containing up to 150 mM NaCl for 2 weeks. Salt stress adversely affected growth and water potential since the first day of exposure to 150 mM NaCl. However, chlorophyll fluorescence parameters were unchanged until 14 days of salt exposure. At that time point the predawn water potential (Ψ_PD), the non-photochemical quenching of fluorescence (NPQ) and the coefficient of photochemical quenching (q_p) were significantly less altered in the tolerant accession. At the molecular level semi-quantitative RT-PCR assays revealed a differential expression of (Vs α-gal/SIP and Vs DHN) genes within these contrasting accessions after exposure to 24 h and 14 days of salt. Comparably, the Vs RD22 gene had increased slightly after only 14 days of treatment in both accessions. These results were the first pieces of information reported on the early and late regulation of salt response genes in wild grapevines. Furthermore, genotype-dependent parameters such as NPQ, q_p, mRNA levels of Vs α-gal/SIP and Vs DHN could be used to screen salt-tolerant wild grapevine genotypes.     

The effect of players' standard and tactical strategy on game demands in men's basketball

The purpose of the present study was to examine the effects of competitive level and team tactic on game demands in men's basketball. Sixteen international-level male basketball players (INPs) and 22 national-level male basketball players (NLPs) were studied during 6 games. Time-motion analysis was performed to track game activities. Game physiological demands were assessed by monitoring heart rate (HR) and blood-lactate concentration. Results showed that INPs sprinted significantly more and performed more high-intensity shuffling than did NLPs (p < 0.05). Game-activity changes and frequency of high-intensity bouts were similar in man-to-man and zone-marking games (1,053 vs. 1,056 and 253 vs. 224, respectively, p > 0.05). Time spent in the maximal (>95% of HRmax) and high-intensity zone (85-95% of HRmax) was greater in the INPs than in the NLPs (17.8 vs. 15.2%, p < 0.01 and 59.1 vs. 54.4%, p < 0.05, respectively). No significant differences in mean HR were evident between man-to-man and zone-marking games (93.3 ± 2.1 vs. 92.8 ± 1.8% of HRmax, p > 0.05). Blood-lactate concentration was higher in the INPs than in the NLPs (6.60 ± 1.22 vs. 5.66 ± 1.19 mmol·L?1 at halftime and 5.65 ± 1.21 vs. 4.43 ± 1.43 mmol·L?1 at full time, p < 0.05). No mean or peak blood-lactate concentration differences resulted between man-to-man and zone-marking games (5.15 ± 1.32 vs. 5.83 ± 1.10 and 5.90 ± 1.25 vs. 6.30 ± 1.27 mmol·L?1, respectively, p > 0.05). These results suggest an effect of competitive level over game demands in men's basketball. No marking strategy effect was evident. Basketball coaches and fitness trainers should develop the ability to repeatedly perform high-intensity activity during the game. Repeated sprinting and high-intensity shuffling ability should be trained to successfully play man-to-man and zone defense, respectively.     

IL-17 inhibits human Th1 differentiation through IL-12Rβ2 downregulation

Th17 cells are critical in adaptive immunity and autoimmune disease. The polarized development of Th17, Th1 and Th2 cells is dependent on counterregulatory effects on each other. Whereas IFN-γ inhibits Th17 development, the effect of IL-17 in human Th1 development is not known. We report a novel negative regulatory role of IL-17 on IL-12Rβ2 expression associated with reduced IL-12 responsiveness. IL-17 decreased IL-12-induced IFN-γ expression in PBMC and developing Th1 cells, associated with a selective reduction in IL-12Rβ2, and not IL-23R, IL-12Rβ1 or T-bet. Counterregulatory effects of human Th17 on Th1 lineage cytokines may contribute to lineage divergence. In autoimmune disease, IL-17 may reinforce its own developmental programme by reducing IL-12 responsiveness, thus limiting inhibitory effects of IFN-γ on Th17 development.     

IL-17RA and IL-17RC receptors are essential for IL-17A-induced ELR+ CXC chemokine expression in synoviocytes and are overexpressed in rheumatoid blood

IL-17A is a cytokine secreted by the newly described Th17 cells implicated in rheumatoid arthritis (RA). Less is known about its receptors in synoviocytes. IL-17RA and IL-17RC were found to be overexpressed in RA peripheral whole blood and their expression was detected locally in RA synovium. In vitro, IL-17A synergized with TNF-alpha to induce IL-6, IL-8, CCL-20, and matrix metalloproteinase-3. Using microarrays, a specific up-regulation of Glu-Leu-Arg+ CXC chemokines was observed in IL-17A-treated synoviocytes. Using both posttranslational inhibitions by silencing interfering RNA and extracellular blockade by specific inhibitors, we showed that both IL-17RA and IL-17RC are implicated in IL-17A-induced IL-6 secretion, whereas in the presence of TNF-alpha, the inhibition of both receptors was needed to down-regulate IL-17A-induced IL-6 and CCL-20 secretion. Thus, IL-17A-induced IL-6, IL-8, and CCL20 secretion was dependent on both IL-17RA and IL-17RC, which are overexpressed in RA patients. IL-17A-induced pathogenic effects may be modulated by IL-17RA and/or IL-17RC antagonism.     

Les associations des calpionelles du Berriasien et du Valanginien inférieur de la Tunisie septentrionale. Comparaison avec les associations du Rif externe (Maroc)

The study of ten thin sections from outcrops from Lower Cretaceous deposits and several thin sections obtained from three petroleum wells, allow us to better characterize the associations of calpionellid zones and subzones of the Berriasian and Lower Valanginian in northern Tunisia. The B and C zones, respectively, show three and two levels with calpionellid associations corresponding to B1, B2, B3 and C1, C2 subzones. In the D zone, associations of the D1 and D2 subzones were identified. The E zone has been characterized for the first time in Tunisia and in southern-Tethyan margin of North Africa, on the basis of its index specie and associated species.