Comparative study of the chemical composition and biological activities of the essential oils of Senecio gallicus from Tunisia.

The essential oils of flowers and remaining parts of the plant Senecio gallicus (Asteraceae), growing wild in Sfax (Tunisia), were obtained by hydrodistillation over a period of two years (2012 and 2013). Their analysis by Gas Chromatography-Mass Spectrometry (GC-MS), led to a total number of 36 components, belonging to different classes of chemical compounds. Oils compositions were characterized by the abundance of monoterpenes hydrocarbons, the major compounds present in flowers for the two years of study were  respectively the sabinene (49.45% and 28.86%), the α-pinene (9.67% and 9.1%), and the β-myrcene (9.88% and 10.97%). These compounds were also dominant in the essential oils of the plant without flowers where they represent (65.34% and 55%) for the sabinene, (4.14% and 7.3%) for α-pinene, and (6.86% and 0%) for β-myrcene. Obtained essential oils were tested for many biological activities and showed a moderate effect against the fungus Trichoderma reesei and bacteria such as Bacillus sp and Staphylococcus aureus. This study of the Senecio gallicus essential oils represents the first one in Tunisia

Purification and characterization of the first recombinant bird pancreatic lipase expressed in Pichia pastoris: The turkey

<p>Abstract</p> <p>Background</p> <p>The turkey pancreatic lipase (TPL) was purified from delipidated pancreases. Some biochemical properties and kinetic studies were determined using emulsified system and monomolecular film techniques. Those studies have shown that despite the accumulation of free fatty acids at the olive oil/water interface, TPL continues to hydrolyse efficiently the olive oil and the TC₄in the absence of colipase and bile salts, contrary to most classical digestive lipases which denaturate rapidly under the same conditions. The aim of the present study was to express TPL in the methylotrophic yeast <it>Pichia pastoris </it>in order to get a large amount of this enzyme exhibiting interesting biochemical properties, to purify and characterize the recombinant enzyme.</p> <p>Results</p> <p>The recombinant TPL was secreted into the culture medium and the expression level reached about 15 mg/l after 4 days of culture. Using Q-PCR, the number of expression cassette integrated on <it>Pichia </it>genomic DNA was estimated to 5. The purified rTPL, with molecular mass of 50 kDa, has a specific activity of 5300 U/mg on emulsified olive oil and 9500 U/mg on tributyrin. The optimal temperature and pH of rTPL were 37°C and pH 8.5. The stability, reaction kinetics and effects of calcium ions and bile salts were also determined.</p> <p>Conclusions</p> <p>Our results show that the expressed TPL have the same properties as the native TPL previously purified. This result allows us the use of the recombinant enzyme to investigate the TPL structure-function relationships.</p

Characteristics of epstein barr virus variants associated with gastric carcinoma in Southern Tunisia

<p>Abstract</p> <p>Backgroud</p> <p>EBV-associated Gastric Carcinoma (EBVaGC) has a distinct clinical features and its prevalence is variable worldwide.</p> <p>Results</p> <p>To determine the prevalence of EBVaGC in Tunisia, EBV-encoded small RNA (EBER) expression was assessed in 81 gastric carcinoma (GC) specimens. The nuclear EBER expression was detected in 12 out of 81 GC cases (14.81%) and concordance between the score range of EBER staining and the number of EBV DNA copies as estimate by QPCR is observed. On the other hand, we found that EBVaGC strongly correlated with age at diagnosis, and weakly with tumor differentiation and venous invasion.</p> <p>Furthermore, the EBVaGC specimens were subjected to determine the EBV DNA polymorphisms. Our results show a unique genetic profile of the EBV strains regarding the A and D types, the F prototype, the retention of <it>Xho</it>I restriction site and the 30 bp del-LMP1 variant. <b><it>According to our previous studies on nasopharyngeal carcinoma (NPC), we suggested that EBV strains associated to GC and NPC shared some similarities in Tunisian patients</it>.</b></p> <p>Conclusion</p> <p>The prevalence of EBVaGC is of 14.81% in the southern Tunisia and that common EBV strain are associated with both NPC and GC which are likely to differ from Asian strains. Our findings support therefore a certain geographical distribution of EBV strains which is not restricted to EBV-associated malignancies.</p

Purification and biochemical characterization of a secreted group IIA chicken intestinal phospholipase A2

<p>Abstract</p> <p>Background</p> <p>Secretory phospholipase A2 group IIA (IIA PLA2) is a protein shown to be highly expressed in the intestine of mammals. However, no study was reported in birds.</p> <p>Results</p> <p>Chicken intestinal group IIA phospholipase A₂(ChPLA₂-IIA) was obtained after an acidic treatment (pH.3.0), precipitation by ammonium sulphate, followed by sequential column chromatographies on Sephadex G-50 and mono-S ion exchanger. The enzyme was found to be a monomeric protein with a molecular mass of around 14 kDa. The purified enzyme showed a substrate preference for phosphatidylethanolamine and phosphatidylglycerol, and didn't hydrolyse phosphatidylcholine. Under optimal assay conditions, in the presence of 10 mM NaTDC and 10 mM CaCl_2,a specific activity of 160 U.mg^-1for purified ChPLA₂-IIA was measured using egg yolk as substrate. The fifteen NH2-terminal amino acid residues of ChPLA₂-IIA were sequenced and showed a close homology with known intestinal secreted phospholipases A₂. The gene encoding the mature ChPLA₂-IIA was cloned and sequenced. To further investigate structure-activity relationship, a 3D model of ChPLA₂-IIA was built using the human intestinal phospholipase A₂structure as template.</p> <p>Conclusion</p> <p>ChPLA2-IIA was purified to homogeneity using only two chromatographic colomns. Sequence analysis of the cloned cDNA indicates that the enzyme is highly basic with a pI of 9.0 and has a high degree of homology with mammalian intestinal PLA₂-IIA.</p

Clinical Significance of Epigenetic Inactivation of hMLH1 and BRCA1 in Tunisian Patients with Invasive Breast Carcinoma

Aberrant hypermethylation of gene promoter regions is one of the mechanisms for inactivation of tumour suppressor genes in many human cancers including breast carcinoma. In the current study, we aimed to assess by MSP, the methylation pattern of two cancer-related genes involved in DNA repair: hMLH1 (mutL homolog 1, colon cancer, nonpolyposis type 2 (E. coli) and BRCA1 (breast cancer 1, early onset) in 78 primary breast cancers from Tunisian patients. The methylation frequencies were 24.36% for hMLH1 and 46% for BRCA1. BRCA1 methylation correlated with age at diagnosis (P = .015) and 5-years disease free survival (P = .016) while hMLH1 methylation was more frequent in larger tumors (P = .002) and in presence of distant metastasis (P = .004). Furthermore, methylation of hMLH1 significantly correlated with high level of P53 expression (P = .006) and with overall survival (P = .015) suggesting that silencing of hMLH1 through aberrant promoter methylation could be used as a poor prognosis indicator in breast cancer

Purification and biochemical characterization of pancreatic phospholipase A2 from the common stingray Dasyatis pastinaca

<p>Abstract</p> <p>Background</p> <p>Mammalian sPLA2-IB are well characterized. In contrast, much less is known about aquatic ones. The aquatic world contains a wide variety of living species and, hence represents a great potential for discovering new lipolytic enzymes.</p> <p>Results</p> <p>A marine stingray phospholipase A₂(SPLA2) was purified from delipidated pancreas. Purified SPLA2, which is not glycosylated protein, was found to be monomeric protein with a molecular mass of 14 kDa. A specific activity of 750 U/mg for purified SPLA2 was measured at optimal conditions (pH 8.5 and 40 °C) in the presence of 4 mM NaTDC and 8 mM CaCl₂using PC as substrate. The sequence of the first twenty first amino-acid residues at the N-terminal extremity of SPLA2 was determined and shows a close similarity with known mammal and bird pancreatic secreted phospholipases A2. SPLA2 stability in the presence of organic solvents, as well as in acidic and alkaline pH and at high temperature makes it a good candidate for its application in food industry.</p> <p>Conclusions</p> <p>SPLA2 has several advantageous features for industrial applications. Stability of SPLA2 in the presence of organic solvents, and its tolerance to high temperatures, basic and acidic pH, makes it a good candidate for application in food industry to treat phospholipid-rich industrial effluents, or to synthesize useful chemical compounds.</p

Biochemical properties of pancreatic colipase from the common stingray Dasyatis pastinaca

Pancreatic colipase is a required co-factor for pancreatic lipase, being necessary for its activity during hydrolysis of dietary triglycerides in the presence of bile salts. In the intestine, colipase is cleaved from a precursor molecule, procolipase, through the action of trypsin. This cleavage yields a peptide called enterostatin knoswn, being produced in equimolar proportions to colipase. In this study, colipase from the common stingray Dasyatis pastinaca (CoSPL) was purified to homogeneity. The purified colipase is not glycosylated and has an apparent molecular mass of around 10 kDa. The NH2-terminal sequencing of purified CoSPL exhibits more than 55% identity with those of mammalian, bird or marine colipases. CoSPL was found to be less effective activator of bird and mammal pancreatic lipases than for the lipase from the same specie. The apparent dissociation constant (Kd) of the colipase/lipase complex and the apparent Vmax of the colipase-activated lipase values were deduced from the linear curves of the Scatchard plots. We concluded that Stingray Pancreatic Lipase (SPL) has higher ability to interact with colipase from the same species than with the mammal or bird ones.The fact that colipase is a universal lipase cofactor might thus be explained by a conservation of the colipase-lipase interaction site. The results obtained in the study may improve our knowledge of marine lipase/colipase.Persona