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81.
Fulgencio Marin-Iniesta Moncef Nasri Pascal Dhulster Jean-Nöel Barbotin Daniel Thomas 《Applied microbiology and biotechnology》1988,28(4-5):455-462
Summary Cells of Escherichia coli K12, carrying the recombinant plasmid pTG201, were immobilized in -carrageenan gel in order to improve the following plasmid parameters: (i) maintenance of a high level of plasmid copy number, (ii) good plasmid stability and (iii) good expression of plasmid encoded gene. The experiments were carried out on LB medium without antibiotic selection in continuous and batch cultures supplied with air or pure oxygen. Parallel experiments with free cells were also performed. In all the cases immobilized cells presented better plasmid stability parameters than free cells. Best results were obtained with immobilized cells supplied with pure oxygen. In this case, an average plasmid copy number of 60 and a value of plasmid-carrying cells close to 100% were maintained with little change during more than 200 generations. In addition, an optical microscopy analysis is proposed to allow the quantitation of cell growth in gel beads. 相似文献
82.
Thibaut Galissier Christophe Schneider Saviz Nasri Lukshe Kanagaratnam Caroline Fichel Christelle Coquelet Marie-Danièle Diebold Reza Kianmanesh Georges Bellon Stéphane Dedieu Aude Marchal Bressenot Camille Boulagnon-Rombi 《PloS one》2016,11(4)
Medical research projects become increasingly dependent on biobanked tissue of high quality because the reliability of gene expression is affected by the quality of extracted RNA. Hence, the present study aimed to determine if clinical, surgical, histological, and molecular parameters influence RNA quality of normal and tumoral frozen colonic tissues. RNA Quality Index (RQI) was evaluated on 241 adenocarcinomas and 115 matched normal frozen colon tissues collected between October 2006 and December 2012. RQI results were compared to patients’ age and sex, tumor site, kind of surgery, anastomosis failure, adenocarcinoma type and grade, tumor cell percentage, necrosis extent, HIF-1α and cleaved caspase-3 immunohistochemistry, and BRAF, KRAS and microsatellites status. The RQI was significantly higher in colon cancer tissue than in matched normal tissue. RQI from left-sided colonic cancers was significantly higher than RQI from right-sided cancers. The RNA quality was not affected by ischemia and storage duration. According to histological control, 7.9% of the samples were unsatisfactory because of inadequate sampling. Biobanked tumoral tissues with RQI ≥5 had lower malignant cells to stromal cells ratio than samples with RQI <5 (p <0.05). Cellularity, necrosis extent and mucinous component did not influence RQI results. Cleaved caspase-3 and HIF-1α immunolabelling were not correlated to RQI. BRAF, KRAS and microsatellites molecular status did not influence RNA quality. Multivariate analysis revealed that the tumor location, the surgical approach (laparoscopy versus open colectomy) and the occurrence of anastomotic leakage were the only parameters influencing significantly RQI results of tumor samples. We failed to identify parameter influencing RQI of normal colon samples. These data suggest that RNA quality of colonic adenocarcinoma biospecimens is determined by clinical and surgical parameters. More attention should be paid during the biobanking procedure of right-sided colon cancer or laparoscopic colectomy specimen. Histological quality control remains essential to control sampling accuracy. 相似文献
83.
Sawssen Hajji Sameh Ben Khedir Ibtissem Hamza-Mnif Marwa Hamdi Ines Jedidi Rim Kallel Sami Boufi Moncef Nasri 《Biochimica et Biophysica Acta (BBA)/General Subjects》2019,1863(1):241-254
The aim of the present study was to prepare chitosan-PVA-silver nanoparticles (CS-AgNPs) through green method. Chitosan and PVA polymers acted as stabilizing agents. DLS and TEM analyses showed that CS-AgNPs were homogeneously dispersed in matrix with an average size of 190–200?nm. The CS-AgNPs were tested for their antioxidant and antibacterial properties and the results revealed that they exhibited higher antioxidant activity than CS powder. Moreover, CS-AgNPs were characterized by a low cytotoxicity effect at 5–200?μg/ml against Chinese Hamster Ovary (CHO-K1) cells. In addition, the prepared CS-Ag NPs were found to promote significantly the wound healing, as determined by the wound contraction ratio and histological examination. A significant improvement in wound healing progression and in oxidative stress damage were observed for CS, CS-PVA and CS-AgNPs-treated wound tissues, when compared to control and CICAFLORA®-treated groups. The wound healing effect could be attributed to the antibacterial and antioxidant synergy of AgNPs and CS. Results strongly support the possibility of using CS-AgNPs for wound care applications. 相似文献
84.
Influence of environmental conditions on the distribution of Amphipoda,Talitridae, in the lagoon complex of Ghar El Melh (north‐east of Tunisia) 下载免费PDF全文
Raja Jelassi Hajer Khemaissia Martin Zimmer Dieter Garbe‐Schönberg Karima Nasri‐Ammar 《African Journal of Ecology》2017,55(4):451-464
The study of the spatiotemporal distribution of talitrid amphipods was carried out along a transect in three stations belonging to the lagoon complex of Ghar El Melh, namely the supralittoral zones of the old harbour of Ghar El Melh, the opposite to Boughaz and Sidi Ali Mekki lagoon. Four species belonging to Talitridae family with two different genera were identified at all stations. These species are Orchestia gammarellus, Orchestia mediterranea, Orchestia stephenseni and Platorchestia platensis. The first two species were collected during the four seasons. The study of the density showed that the most important global mean density in talitrid was found in the supralittoral zone of opposite to Boughaz. In addition, statistical analysis showed a significant difference in the seasonal distribution of amphipods based on plant associations. Furthermore, the highest diversity of talitrid was observed in the winter in the supralittoral zone of opposite to Boughaz and in summer in the supralittoral zones of Sidi Ali Mekki lagoon and the old harbour of Ghar El Melh. Results showed that at all stations, a highly significant correlation of amphipod community with Cymodocea banquette was observed. Moreover, principal component analysis showed that the distribution of the different species depends on climatic and edaphic factors. 相似文献
85.
Anissa Haddar Ali Bougatef Rym Agrebi Alya Sellami-Kamoun Moncef Nasri 《Process Biochemistry》2009,44(1):29-35
An extracellular bleach stable protease producing strain was isolated from marine water sample and identified as Bacillus mojavensis A21 on the basis of the 16S rRNA gene sequencing and biochemical properties. The A21 alkaline protease was purified from the culture supernatant to homogeneity using acetone precipitation, Sephadex G-75 gel filtration and CM-Sepharose ion exchange chromatography, with a 6.43-fold increase in specific activity and 16.56% recovery. The molecular weight of the purified enzyme was estimated to be 20 kDa by SDS-PAGE and gel filtration. The enzyme was highly active over a wide range of pH from 7.0 to 13.0, with an optimum at pH 8.5. The relative activities at pH 11.0 and 12.0 were about 80 and 71.7% of that obtained at pH 8.5. The enzyme was extremely stable in the pH range of 7.0–12.0. It exhibited maximal activity at 60 °C. The thermostability of the enzyme was significantly increased by the addition of CaCl2. The activity of the enzyme was totally lost in the presence of PMSF, suggesting that the purified enzyme is a serine protease.The N-terminal amino acid sequence of the first 20 amino acids of the purified protease was DINGGGATLPQKLYQTSGVL. B. mojavensis A21 protease showed low homology with bacterial peptidases, suggesting that the enzyme is a new protease.The alkaline protease showed high stability towards anionic (0.1% SDS) and non-ionic (1 and 5% Tween 80 and 1% Triton X-100) surfactants. In addition, the enzyme was relatively stable towards oxidizing agents, retaining more than 79 and 70% of its initial activity after 1 h incubation in the presence of 1% H2O2 and 0.1% sodium perborate, respectively. The enzyme showed excellent stability with a wide range of commercial solid and liquid detergents at 30 and 40 °C. Considering its promising properties, B. mojavensis A21 may find potential application in laundry detergents. 相似文献
86.
Rym Agrebi Anissa Haddar Noomen Hmidet Kemel Jellouli Laila Manni Moncef Nasri 《Process Biochemistry》2009,44(11):1252-1259
A novel fibrinolytic enzyme, subtilisin BSF1, from a newly isolated Bacillus subtilis A26 was purified, characterized and the gene was isolated and sequenced. The subtilisin BSF1 was purified to homogeneity by five-step procedure with a 4.97-fold increase in specific activity and 6.28% recovery. The molecular weight of the purified enzyme was estimated to be 28 kDa by SDS-PAGE and gel filtration. The purified enzyme exhibited high fibrinolytic activity on fibrin agar plates.Interestingly, the enzyme was highly active over a wide range of pH from 7.0 to 12.0, with an optimum at pH 9.0. The relative activities at pH 10.0 and 11.0 were 97.8% and 85.2% of that at pH 9.0. The optimum temperature for enzyme activity was 60 °C. The activity of subtilisin BSF1 was totally lost in the presence of PMSF, suggesting that the purified enzyme is a serine protease. The N-terminal amino acid sequence of the first 11 amino acids (aa) of the purified fibrinolytic enzyme was AQSVPYGISQI.The bsf1 gene encoding the subtilisin BSF1 was isolated and its DNA sequence was determined. The bsf1 gene consisted of 1146 bp encoding a pre-pro-protein of 381 amino acids organized into a signal peptide (29 aa), a pro-peptide (77 aa) and a mature domain (275 aa). The deduced amino acids sequence of the mature enzyme (BSF1) differs from those of nattokinase from B. subtilis natto and subtilisin DFE from Bacillus amyloliquefaciens DC-4 by 5 and 39 amino acids, respectively. 相似文献
87.
Ghorbel-Bellaaj O Hmidet N Jellouli K Younes I Maâlej H Hachicha R Nasri M 《International journal of biological macromolecules》2011,48(4):596-602
A Box-Bhenken design with four variables (shrimp shell concentration (SSC), glucose concentration, incubation time and inoculum size) and three levels was used for the determination of the deproteinization and demineralization efficiencies in fermented shrimp shells by Pseudomonas aeruginosa A2. The fermentation variables were selected in accordance with Plackett-Burman design. Maximum demineralization of 96%, with about 89% of protein removal occurs under the following conditions: SSC 50 g/l, glucose 50 g/l, 5 days and inoculum of 0.05 OD. This environment friendly method (biological treatment) can be considered as an effective pretreatment to produce a high-quality chitin. 相似文献
88.
89.
Dalel Daâssi Héla Zouari-Mechichi Alicia Prieto María Jesús Martínez Moncef Nasri Tahar Mechichi 《World journal of microbiology & biotechnology》2013,29(11):2145-2155
A white-rot basidiomycete, isolated from decayed acacia wood (from Northwest of Tunisia) and identified as Trametes sp, was selected in a broad plate screening because of its ability to decolorize and dephenolize olive oil mill wastewater (OMW) efficiently. The major laccase was purified and characterized as a monomeric protein with apparent molecular mass of 61 kDa (SDS-PAGE). It exhibits high enzyme activity over broad pH and temperature ranges with optimum activity at pH 4.0 and a temperature of 60 °C. The purified laccase is stable at alkaline pH values. The enzyme retained 50 % of its activity after 90 min of incubation at 55 °C. Using ABTS, this laccase presented K m and V max values of 0.05 mM and 212.73 μmoL min?1 mg?1, respectively. It has shown a degrading activity towards a variety of phenolic compounds. The purified laccase was partially inhibited by Fe2+, Zn2+, Cd2+ and Mn2+, while Cu2+ acted as inducer. EDTA (10 mM) and NaN3 (10 mM) were found to completely inhibit its activity. 73 % OMW was dephenolized after 315 min incubation at 30 °C with 2 U mL?1 of laccase and 2 mM HBT. 相似文献
90.
Hajer Khemaissia Raja Jelassi Catherine Souty‐Grosset Karima Nasri‐Ammar 《African Journal of Ecology》2018,56(1):38-50
In Tunisia, while wetlands are considered as remarkable habitats for their faunal and floral diversity, few studies on the biogeography and the diversity of terrestrial isopods were performed. To fill this gap, we carried out a field study in the supralittoral zone of 146 Tunisian wetlands belonging to eight types (lagoon, river, lake, sebkha, dam, hill reservoir, beach and chott) and to five bioclimatic zones (humid, subhumid, semi‐arid, arid and Saharan). Field work was carried out in spring 2010. Terrestrial isopods were collected in the morning by hand search each time with the same sampling effort. During the study, 22 species of terrestrial isopods belonging to nine families were collected. Porcellio variabilis, Porcellio laevis, Chaetophiloscia elongata and Armadillidium pelagicum are the most common species identified. From the northern to the southern regions, a gradual decrease in species richness has been shown. The identified species belonged to different biogeographical categories: Mediterranean, Mediterranean‐Atlantic, North Africa with circum‐Sicilian islands, semi‐arid and Saharan species. Some of these species are endemic to Tunisia (Porcellio dominici) or to North Africa (Armadillidium sulcatum, Armadillidium tunisiense, Porcellio marginenotatus and P. variabilis). Terrestrial isopod species differ according to wetland type and bioclimatic zone. 相似文献