Identification of a new phospholipase D in Carica papaya latex

Phospholipase D (PLD) is a lipolytic enzyme involved in signal transduction, vesicle trafficking and membrane metabolism. It catalyzes the hydrolysis and transphosphatidylation of glycerophospholipids at the terminal phosphodiester bond. The presence of a PLD in the latex of Carica papaya (CpPLD1) was demonstrated by transphosphatidylation of phosphatidylcholine (PtdCho) in the presence of 2% ethanol. Although the protein could not be purified to homogeneity due to its presence in high molecular mass aggregates, a protein band was separated by SDS-PAGE after SDS/chloroform-methanol/TCA-acetone extraction of the latex insoluble fraction. This material was digested with trypsin and the amino acid sequences of the tryptic peptides were determined by micro-LC/ESI/MS/MS. These sequences were used to identify a partial cDNA (723 bp) from expressed sequence tags (ESTs) of C. papaya. Based upon EST sequences, a full-length gene was identified in the genome of C. papaya, with an open reading frame of 2424 bp encoding a protein of 808 amino acid residues, with a theoretical molecular mass of 92.05 kDa. From sequence analysis, CpPLD1 was identified as a PLD belonging to the plant phosphatidylcholine phosphatidohydrolase family.     

<Emphasis Type="Italic">Frankia inefficax</Emphasis> sp. nov., an actinobacterial endophyte inducing ineffective,non nitrogen-fixing,root nodules on its actinorhizal host plants

Strain EuI1c^T is the first actinobacterial endophyte isolated from Elaeagnus umbellata that was shown to be infective on members of Elaeagnaceae and Morella but lacking the ability to form effective root nodules on its hosts. The strain can be easily distinguished from strains of other Frankia species based on its inability to produce vesicles, the specialized thick-walled structures where nitrogen fixation occurs. Chemotaxonomically, strain EuI1c^T contains phosphatidylinositol, diphosphatidylglycerol, two glycophospholipids and phosphatidylglycerol as phospholipids. The whole cell sugars were composed of glucose, galactose, mannose, ribose, rhamnose and fucose as diagnostic sugars of the species. Major fatty acids were iso-C_16:0, C_17:1 ω8c and C_15:0 and C_17:0 and the predominant menaquinones were MK-9(H₆), MK-9(H₈) and MK-9(H₄). Analysis of the 16S rRNA gene sequence of strain EuI1c^T showed 97, 97.4 and 97.9% identity with Frankia elaeagni DSM 46783^T, Frankia casuarinae DSM 45818^T and Frankia alni DSM 45986^T, respectively. Digital DNA:DNA hybridizations with type strains of the three Frankia species with validly/effectively published names are significantly below 70%. These results warrant distinction of EuI1c^T (= DSM 45817^T = CECT 9037^T) as the type strain of a novel species designated Frankia inefficax sp. nov.     

Molecular Diagnostic and Prognostic Subtyping of Gliomas in Tunisian Population

It has become increasingly evident that morphologically similar gliomas may have distinct clinical phenotypes arising from diverse genetic signatures. To date, glial tumours from the Tunisian population have not been investigated. To address this, we correlated the clinico-pathology with molecular data of 110 gliomas by a combination of HM450K array, MLPA and TMA-IHC. PTEN loss and EGFR amplification were distributed in different glioma histological groups. However, 1p19q co-deletion and KIAA1549:BRAF fusion were, respectively, restricted to Oligodendroglioma and Pilocytic Astrocytoma. CDKN2A loss and EGFR overexpression were more common within high-grade gliomas. Furthermore, survival statistical correlations led us to identify Glioblastoma (GB) prognosis subtypes. In fact, significant lower overall survival (OS) was detected within GB that overexpressed EGFR and Cox2. In addition, IDH1R132H mutation seemed to provide a markedly survival advantage. Interestingly, the association of IDHR132H mutation and EGFR normal status, as well as the association of differentiation markers, defined GB subtypes with good prognosis. By contrast, poor survival GB subtypes were defined by the combination of PTEN loss with PDGFRa expression and/or EGFR amplification. Additionally, GB presenting p53-negative staining associated with CDKN2A loss or p21 positivity represented a subtype with short survival. Thus, distinct molecular subtypes with individualised prognosis were identified. Interestingly, we found a unique histone mutation in a poor survival young adult GB case. This tumour exceptionally associated the H3F3A G34R mutation and MYCN amplification as well as 1p36 loss and 10q loss. Furthermore, by exhibiting a remarkable methylation profile, it emphasised the oncogenic power of G34R mutation connecting gliomagenesis and chromatin regulation.     

Parasitoid foraging decisions mediated by artificial vibrations

In any host-parasitoid interaction, the detection of the host in its microhabitat is a crucial step in the interaction that has a major influence on the parasitoid's fitness. We used bioassays to investigate whether the parasitoid Sympiesis sericeicornis (Hymenoptera: Eulophidae) uses the vibrations of its host Phyllonorycter sp. gr. blancardella (Lepidoptera: Gracillariidae) to detect it in the leaf mine. From the large variety of signals produced by the host, we identified a unitary signal that could be reproduced artificially. We then sent this signal into emptied mines to analyse the reaction of the parasitoid. The wasps reacted by increasing both the time spent foraging on the mine and the number of insertions of the ovipositor to detect the ‘virtual’ host. This study is the first to show that parasitoids detect host vibrations.     

Impacts of nanoparticles and phosphonates in the behavior and oxidative status of the mediterranean mussels (Mytilus galloprovincialis)

The current study investigated the exposure of the Mediterranean mussel (Mytilus galloprovincialis) to gold nanoparticles decorated zinc oxide (Au-ZnO NPs) and phosphonate [Diethyl (3-cyano-1-hydroxy-1-phenyl-2-methylpropyl)] phosphate (PC). The mussels were exposed to concentrations of 50 and 100 µg L^-1 of both compounds alone, as well as to a mixture of both pollutants (i.e. Mix). The singular and the combined effect of each pollutant was investigated by measuring the concentration of various metals (i.e., Cu, Fe, Mn, Zn and Au) in the the digestive glands and gills of mussels, their filtration capacity (FC), respiration rate (RR) and the response of oxidative biomarkers, respectively, following 14 days of exposure. The concentrations of Cu, Fe, Mn, Zn and Au increased directly with Au-ZnO NPs in mussel tissues, but significantly only for Zn. In contrast, the mixture of Au-ZnO100 NPs and PC100 did not induce any significant increase in the content of metals in digetsve glands and gills, suggesting antagonistic interactions between contaminants. In addition, FC and RR levels decreased following exposure to Au-ZnO100 NPs and PC100 treatments and no significant alterations were observed after the exposure to 50 µg.L^-1 of both contaminants and Mix. Hydrogen peroxide (H₂O₂) level, GSH/GSSG ratio, superoxide dismutase (SOD), catalase (CAT) and acetylcholinesterase (AChE) activities showed significant changes following the exposure to both Au-ZnO NPs and PC, in the gills and the digestive glands of the mussel. However, no significant modifications were observed in both organs following the exposure to Mix. The current study advances the understanding of the toxicity of NPs and phosphonates on M. galloprovincialis and sets the path for future ecotoxicological studies regarding the synergic effects of these substances on marine species. Moreover, the current experiment suggests that the oxidative stress and the neurotoxic pathways are responsive following the exposure of marine invertebrates to both nanoparticles and phosphonates, with potential antagonist interactions of these substances on the physiology of targeted species.     

The effect of post-lunch napping on mood,reaction time,and antioxidant defense during repeated sprint exercice

To compare the effects of two nap opportunities (20 and 90 min) to countermeasure the transient naturally occurring increased sleepiness and decreased performances during the post-lunch dip (PLD). Fourteen highly trained judokas completed in a counterbalanced and randomized order three test sessions (control (No-nap), 20- (N20) and 90-min (N90) nap opportunities). Test sessions consisted of the running-based anaerobic sprint test (RAST), simple and multiple-choice reaction times (MCRT) and the Epworth sleepiness scale (ESS). From the RAST, the maximum (P_max), mean (P_mean) and minimum (P_min) powers were calculated. Blood samples were taken before and after the RAST to measure the effect of pre-exercise napping on energetic and muscle damage biomarkers and antioxidant defense. N20 increased P_max and P_mean compared to No-nap (p < 0.001, d = 0.59; d = 0.66) and N90 (p < 0.001, d = 0.98; d = 0.72), respectively. Besides, plasma lactate and creatinine increased only when the exercise was performed after N20. Both N20 (p < 0.001, d = 1.18) and N90 (p < 0.01, d = 0.78) enhanced post-exercise superoxide dismutase activity compared to No-nap. However, only N20 enhanced post-exercise glutathione peroxidase activity (p < 0.001, d = 1.01) compared to pre-nap. Further, MCRT performance was higher after N20 compared to No-nap and N90 (p < 0.001, d = 1.15; d = 0.81, respectively). Subjective sleepiness was lower after N20 compared to No-nap (p < 0.05, d = 0.92) and N90 (p < 0.01, d = 0.89). The opportunity to nap for 20 min in the PLD enhanced RAST, MCRT performances, and antioxidant defense, and decreased sleepiness. However, the opportunity of 90 min nap was associated with decreased repeated sprint performances and increased sleepiness, probably because of the sleep inertia.     

Heterologous expression and secretion of an antifungal Bacillus subtilis chitosanase (CSNV26) in Escherichia coli

The aims of the study were the production improvement, the purification, the characterization and the activity investigation of chitosanase CSNV26 of Bacillus subtilis (V26). The gene csnV26 encoding for this protein was amplified and cloned in the pBAD vector then expressed in Escherichia coli (Top10). The SDS-PAGE and zymogram analysis of the recombinant protein showed that it has two active forms sized 27 and 31 kDa, corresponding to the protein with and without signal peptide. This protein has the particularity of being secreted by Top10-pBAD-csnV26 with a high yield of 6.2 g/l. The HPLC purification of CSNV26 from supernatant confirmed the presence of the two sizes. The investigation of the CSNV26 thermostability showed that the pure protein is highly stable keeping 68 % of its activity after 30-min treatment at 100 °C, contrarily to the protein present within the supernatant of E. coli and B. subtilis (V26). The molecular dynamics study of the predicted structure of protein in both forms showed that the presence of the peptide signal in the form of 31 kDa gave it a remarkable thermal stability. The antifungal activity of CSNV26 was evidenced on Rhizopus nigricans and Rhizopus oryzae. Indeed, it has provoked an alteration and embrittlement of their hyphae with onset of protoplast.     

Date Seeds (Phoenix dactylifera): Antioxidant Potential and Profile of Free and Bound Polyphenols from Different Cultivars

In this study, the antioxidant activities and detailed phenolic profiling of extracts from seven cultivars of date seeds were investigated. Significant differences were detected among cultivars. Total phenolic content (TP) ranged between 135.9±12.1 and 284.86±21.9 mg GAE/g DM. The total flavonoid value varied between 34.20±0.34 and 94.46±1.04 mg RE/g DM. The condensed tannin ranged from 24.17±1.13 to 201.60±9.95 mg CTE/g DM. Phloroglucinolysis was used to depolymerize the bound polyphenols. Results show the presence of phenolic acids: Hydroxybenzoic acid, hydroxycinnamic acid, and a high amount of flavan-3ols (monomers, dimers, and trimers). Before depolymerization, the highest amount of total polyphenols was identified in Kenta (8.48 g/kg) and the lowest was detected in Hessa (4.74 g/kg). After depolymerization, the flavan-3-ols increased significantly, ranging between 46.91g/kg in Hessa and 72.38 g/kg in Deglet Nour, with a high degree of polymerization (DP) in all cultivars. It can be concluded that date seeds represent a good source of bioactive compounds.     

A 1,100-year-old founder effect mutation in IL12B gene is responsible for Mendelian susceptibility to mycobacterial disease in Tunisian patients

Mendelian susceptibility to mycobacterial disease (MSMD) is a rare disorder predisposing apparently healthy individuals to infections caused by weakly virulent mycobacteria such as bacille Calmette–Guerin (BCG), environmental mycobacteria, and poorly virulent Salmonella strains. IL-12p40 deficiency is the first reported human disease due to a cytokine gene defect and is one of the deficiencies that cause MSMD. Nine mutant alleles only have been identified in the IL12B gene, and three of them are recurrent mutations due to a founder effect in specific populations. IL-12p40 deficiency has been identified especially in countries where consanguinity is high and where BCG vaccination at birth is universal. We investigated, in such settings, the clinical, cellular, and molecular features of six IL-12p40-deficient Tunisian patients having the same mutation in IL12B gene (c.298_305del). We found that this mutation is inherited as a common founder mutation arousing ~1,100 years ago. This finding facilitates the development of a preventive approach by genetic counseling and prenatal diagnosis especially in affected families.