Showing papers by "Tunis University published in 2010"
TL;DR: The demonstration of multiple modes of transmission between individuals and to their progeny that include vertical and horizontal transmission routes, comprising a venereal one, indicate that AAB represent novel secondary symbionts of insects.
Abstract: Recent research in microbe-insect symbiosis has shown that acetic acid bacteria (AAB) establish symbiotic relationships with several insects of the orders Diptera, Hymenoptera, Hemiptera, and Homoptera, all relying on sugar-based diets, such as nectars, fruit sugars, or phloem sap. To date, the fruit flies Drosophila melanogaster and Bactrocera oleae, mosquitoes of the genera Anopheles and Aedes, the honey bee Apis mellifera, the leafhopper Scaphoideus titanus, and the mealybug Saccharicoccus sacchari have been found to be associated with the bacterial genera Acetobacter, Gluconacetobacter, Gluconobacter, Asaia, and Saccharibacter and the novel genus Commensalibacter. AAB establish symbiotic associations with the insect midgut, a niche characterized by the availability of diet-derived carbohydrates and oxygen and by an acidic pH, selective factors that support AAB growth. AAB have been shown to actively colonize different insect tissues and organs, such as the epithelia of male and female reproductive organs, the Malpighian tubules, and the salivary glands. This complex topology of the symbiosis indicates that AAB possess the keys for passing through body barriers, allowing them to migrate to different organs of the host. Recently, AAB involvement in the regulation of innate immune system homeostasis of Drosophila has been shown, indicating a functional role in host survival. All of these lines of evidence indicate that AAB can play different roles in insect biology, not being restricted to the feeding habit of the host. The close association of AAB and their insect hosts has been confirmed by the demonstration of multiple modes of transmission between individuals and to their progeny that include vertical and horizontal transmission routes, comprising a venereal one. Taken together, the data indicate that AAB represent novel secondary symbionts of insects.
280 citations
TL;DR: Improvements brought to BACTIBASE include incorporation of various tools for bacteriocin analysis, such as homology search, multiple sequence alignments, Hidden Markov Models, molecular modelling and retrieval through the taxonomy Browser.
Abstract: Background
BACTIBASE is an integrated open-access database designed for the characterization of bacterial antimicrobial peptides, commonly known as bacteriocins.
267 citations
TL;DR: This paper introduces a new variant of the Pareto dominance relation, called r-dominance, which has the ability to create a strict partial order among Pare to-equivalent solutions and provides competitive and better results when compared to other recently proposed preference-based EMO approaches.
Abstract: Evolutionary multiobjective optimization (EMO) methodologies have gained popularity in finding a representative set of Pareto optimal solutions in the past decade and beyond. Several techniques have been proposed in the specialized literature to ensure good convergence and diversity of the obtained solutions. However, in real world applications, the decision maker is not interested in the overall Pareto optimal front since the final decision is a unique solution. Recently, there has been an increased emphasis in addressing the decision-making task in searching for the most preferred alternatives. In this paper, we introduce a new variant of the Pareto dominance relation, called r-dominance, which has the ability to create a strict partial order among Pareto-equivalent solutions. This fact makes such a relation able to guide the search toward the interesting parts of the Pareto optimal region based on the decision maker's preferences expressed as a set of aspiration levels. After integrating the new dominance relation in the NSGA-II methodology, the efficacy and the usefulness of the modified procedure are assessed through two to ten-objective test problems a priori and interactively. Moreover, the proposed approach provides competitive and better results when compared to other recently proposed preference-based EMO approaches.
239 citations
TL;DR: In this paper, the authors explore whether six broad categories of knowledge transfer activities undertaken by academics: the creation and diffusion of knowledge through publications, transmission of knowledge via teaching, informal knowledge transfer, patenting, spin-off formation and consulting activities, are complementary, substitute, or independent, as well as the conditions under which complementarity, substitution and independence among these activities are likely to emerge.
165 citations
TL;DR: The GIS-based demarcation of artificial zones developed in this study was based on logical conditions and reasoning, so that the same techniques could be adopted elsewhere, especially in similar aquifer systems in arid areas where the occurrence of groundwater is restricted and subject to a greater complexity.
136 citations
TL;DR: The results here show that the ABA signaling pathway integrates PAs and AOs to regulate the generation of H2O2, which signals further stress responses or the PCD syndrome.
125 citations
TL;DR: Two- phase anaerobic digestion system has given the best performances concerning methane productivity, soluble COD (SCOD) and phenol removal efficiencies and effluent quality compared to those given by conventional one-phase an aerobic digestion (AD) reactors.
121 citations
TL;DR: The results suggest that cICDH, previously considered mainly as an enzyme involved in amino acid synthesis, plays a role in redox signalling linked to pathogen responses.
Abstract: Cytosolic NADP-dependent isocitrate dehydrogenase (cICDH) produces 2-oxoglutarate (2-OG) and NADPH, and is encoded by a single gene in Arabidopsis thaliana. Three allelic lines carrying T-DNA insertions in this gene showed less than 10% extractable leaf ICDH activity, but only relatively small decreases in growth compared to wild-type Col0. Metabolite profiling by gas chromatography-time of flight-mass spectrometry (GC-TOF-MS) and high-performance liquid chromatography (HPLC) revealed that loss of cICDH function produced only small effects on leaf compounds involved in carbon and nitrogen assimilation. To analyse whether cICDH contributes to NADPH production under conditions of oxidative stress, the icdh mutation was introduced into the cat2 background, in which increased availability of H(2)O(2) causes perturbed redox homeostasis and induction of stress-related genes. Accumulation of oxidized glutathione and pathogen-related responses were enhanced in double cat2 icdh mutants compared to cat2. Single icdh mutants presented constitutive induction of PR genes, and enhanced resistance to bacteria in icdh, cat2 and cat2 icdh was quantitatively correlated with PR gene expression. However, the effect of icdh in both Col0 and cat2 backgrounds was not associated with enhanced accumulation of salicylic acid (SA). The results suggest that cICDH, previously considered mainly as an enzyme involved in amino acid synthesis, plays a role in redox signalling linked to pathogen responses.
118 citations
TL;DR: To ameliorate the current 100‐kDa horse plasma antivenom serum (PAS)‐derived Fab′2 to more quickly reach the highly diffusible scorpion toxins, the designed bispecific NbF12‐10 against AahI′/AahII toxins succeeded in neutralizing 5 LD50.
Abstract: Envenoming following scorpion sting is a common emergency in many parts of the world Our aim was to ameliorate the current 100-kDa horse plasma antivenom serum (PAS)-derived Fab'(2) to more quickly reach the highly diffusible scorpion toxins (7 kDa) We immunized dromedaries with toxins from Androctonus australis hector (Aah) scorpions and cloned the single-domain antibody fragments or nanobodies (15 kDa) from their B cells Nanobodies against AahI' toxin (with AahII the most toxic compound of the venom) were retrieved from the libraries, and their AahI'-toxin neutralization was monitored in mice Remarkably, the NbAahI'F12 fully protected mice against 100 LD(50) of AahI' administered intracerebroventricularly Moreover, where PAS failed completely to neutralize 2 LD(50) of crude venom injected subcutaneously, the designed bispecific NbF12-10 against AahI'/AahII toxins succeeded in neutralizing 5 LD(50) Finally, in a challenge assay in which mice were subcutaneously injected with a lethal dose of scorpion venom, the subsequent intravenous injection of 85 microg of NbF12-10 protected all mice, even if the whole procedure was repeated 3 times Furthermore, the NbF12-10 remained fully protective when mice with severe signs of envenoming were treated a few minutes before the untreated mice died
105 citations
TL;DR: In this article, the authors examined income smoothing practices in Islamic banks using Beidleman's and Eckel's coefficients and found that more than 75 percent of the examined banks have a determination coefficient between 0.5 and 1 and 44 percent have a variation coefficient less than 0.
Abstract: Purpose – The paper seeks to examine income smoothing practices in Islamic banks. It first focuses on detecting income smoothing practices. It then seeks to test whether loan loss provisions (LLPs) are used for earnings management purposes.Design/methodology/approach – The paper explores income smoothing practices on a sample of 66 Islamic banks over the period 2001‐2006 using Beidleman's and Eckel's coefficients. Data are obtained from the Bankscope database. To test the use of LLPs to smooth Islamic banks results, a regression model was developed and tested.Findings – The results provide evidence on an extensive use of income smoothing by Islamic banks. More than 75 per cent of the examined banks have a determination coefficient between 0.5 and 1 and 44 per cent have a variation coefficient less than 0.5. However, income smoothing is not achieved through LLPs. The variable earnings before taxes and provisions are not significant in all model specifications. The paper advances that these smoothed incomes...
103 citations
TL;DR: In this paper, the results of the seawater intrusion study of the Korba aquifer by the geophysical and hydrochemical methods are presented, where 38 vertical electrical sounding (VES) were distributed over the coastal area between Korba and Oued Lebna.
TL;DR: In this article, a plate-and-frame membrane module has been used in sweeping gas membrane distillation process, which is based on Navier-Stokes equations coupled with the Darcy-Brinkman-Forcheimer formulation in transient regime in two dimensions.
TL;DR: The results indicated that the plants treated with 10μM of zinc exhibited better growth, however, higher concentrations of zinc were harmful for plants.
Abstract: The effects of zinc (Zn) on plant chlorophyll fluorescence were investigated in 10-day-old tomato ( Solanum lycopersicum ) seedlings subjected for 7 days to a series of zinc (10, 50, 100 and 150 μM) applied via the nutrient solution. The chlorophyll fluorescence spectra of leaves were recorded in the spectral region 650–800 nm using the spectroscopic technique of ultraviolet light emitting diode induced fluorescence spectroscopy (UV-LED IFS). These spectra have been used to analyze the effect of several doses of zinc on the photosynthetic activities of tomato plants. The fluorescence intensity ratios (FIR) at the two maxima ( F 690 / F 735 ) of control as well as treated tomato plants were calculated by evaluating curve-fitted parameters using a Gaussian spectral function. The variable chlorophyll fluorescence decrease ratio ( R Fd ) values were determined from the fluorescence induction kinetics curves recorded at 690 nm and 735 nm. In addition, Zn accumulation in plants, plant growth, photosynthetic pigments content and malondialdehyde level (MDA, an index of lipid peroxidation) were also estimated. The results indicated that the plants treated with 10 μM of zinc exhibited better growth, however, higher concentrations of zinc were harmful for plants. Excess Zn induced a decrease in the R Fd values, which was associated with a strong decline of the total chlorophylls content and an increase of MDA level. The total chlorophylls content decline could also be followed via an increase of the chlorophyll fluorescence ratio F 690 / F 735 .
TL;DR: A necessary and sufficient condition is given for the existence of an unknown input observer for state affine systems and its application to fault detection is considered.
TL;DR: Specific virulence factors adapted to the insect intestine might exist in B. thuringiensis and B. entomophila, which suggests a co-evolution between host and pathogens and supports the close links between B. cereus and more distant links to their relative B. anthracis.
TL;DR: A field study was carried out to evaluate long-term heavy metal accumulation in the top 20 cm of a Tunisian clay-ey loam soil amended for four consecutive years with municipal solid waste compost at three levels (0, 40 and 80 t/ha/y) as mentioned in this paper.
Abstract: A field study was carried out to evaluate long-term heavy metal accumulation in the top 20 cm of a Tunisian clayey loam soil amended for four consecutive years with municipal solid waste compost at three levels (0, 40 and 80 t/ha/y). Heavy metals uptake and translocation within wheat plants grown on these soils were also investigated. Compared to untreated soils, compost-amended soils showed significant increases in the content of all measured metals: cadmium, chromium, copper, nickel, lead and zinc in the last three years, especially for plots amended with municipal solid waste compost at 80 t/ha/y. Wheat plants grown on compost-amended soils showed a general increase in metal uptake and translocation, especially for chromium and nickel. This heavy metal uptake was about three folds greater in plots amended at 80 t/ha/y as compared to plots amended at 40 t/ha/y. At the end of the experimental period, the diluting effect resulting from enhanced growth rates of wheat plants due to successive compost applications resulted in lower concentrations in the plants (grain part) grown on treated plots. On the other hand, chromium and nickel were less mobile in the aerial part of wheat plants and were accumulated essentially in root tissues. Plant/soil transfer coefficients for compost-amended treatments were higher than threshold range reported in the literature, indicating that there was an important load/transfer of metal ions from soils to wheat plants.
TL;DR: This paper proposes a novel encoding method that uses amino-acid substitution matrices to define similarity between motifs during the extraction step and shows that SVM, coupled with this method, can be an efficient protein classification system.
Abstract: Background
This paper deals with the preprocessing of protein sequences for supervised classification. Motif extraction is one way to address that task. It has been largely used to encode biological sequences into feature vectors to enable using well-known machine-learning classifiers which require this format. However, designing a suitable feature space, for a set of proteins, is not a trivial task. For this purpose, we propose a novel encoding method that uses amino-acid substitution matrices to define similarity between motifs during the extraction step.
TL;DR: The results obtained show the existence of many different genetic lineages within the studied Apodemus species, suggesting the isolation and differentiation of populations in multiple refuge areas, and higher genetic diversities in some regions such as Yunnan, Sichuan (China), and eastern Russia suggest these areas are potential refuges for these species.
Abstract: The phylogeography of four Apodemus species (Apodemus agrarius, Apodemus peninsulae, Apodemus latronum, and Apodemus draco) was studied in the Far East of Asia, based on sequences of the mitochondrial DNA cytochrome b gene. The results obtained show the existence of many different genetic lineages within the studied Apodemus species, suggesting the isolation and differentiation of populations in multiple refuge areas. Higher genetic diversities in some regions such as Yunnan, Sichuan (China), and eastern Russia suggest these areas are potential refuges for these species. The existence of such complex genetic structures could be linked to the presence of many biogeographic barriers (Himalaya Mountains, Tien-shan Mountains, Altai Mountains, Tibetan Plateau, Gobi desert, Yunnan Guizhou Plateau, Dzungaria basin, and others) in these regions, which were probably reinforced during the Quaternary climate changes. These barriers also played an important role concerning the low dispersal abilities of the two studied Apodemus species adapted to forest habitats (A. latronum and A. draco) with respect to colonizing regions other than China. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 797-821.
TL;DR: In this article, the main restricting factors for urban development, such as lithology, topography, slope, seismotectonic, water table depth, flooding susceptibility and seismic-induced effects were considered in the preparation of maps.
TL;DR: In this article, a hexagonal tungsten oxide nanorods have been synthesized by hydrothermal strategy using Na 2 WO 4 ·2H 2 O as source, aniline and sulfate sodium as structure-directing templates.
TL;DR: This paper illustrates a computational infrastructure that allows an analyst to estimate the security of a system in terms of the loss that each stakeholder stands to sustain as a result of security breakdowns by means of an e-commerce application.
Abstract: In earlier works we presented a computational infrastructure that allows an analyst to estimate the security of a system in terms of the loss that each stakeholder stands to sustain as a result of security breakdowns. In this paper we illustrate this infrastructure by means of an e-commerce application.
TL;DR: In this article, the performance and stability of a 0.64m 2 mini solar pond were experimentally and numerically studied, and the experimental results showed that the daily average temperatures of the mini pond increased quickly to reach 54°C in the lower convective zone after only 20 days.
TL;DR: The role of the cell wall in Cd tolerance might be important at two levels: in the reinforcement of the tissue cohesion and in the sequestration of Cd.
TL;DR: Biomethanisation experiments performed with raw OMW or pre-treated OMW proved that pre-treatments with ((Al-Fe)PILC/H(2)O(2)) system, for more than 2 h, resulted in higher methane production.
TL;DR: In this article, a SnO2 thin film has been grown using spray pyrolysis technique on glass substrates under a substrate temperature of T = 440°C using methanol CH4O and anhydrous tin tetrachloride XRD analyses yielded strong X-ray diffraction peaks which are characteristics to tetragonal crystals.
TL;DR: In this article, a generalization and a variant of Cowling-Price's theorem, Beurling's theorem and Donoho-Stark's uncertainty principle are obtained for the Dunkl transform.
Abstract: The Dunkl transform satisfies some uncertainty principles similar to the Euclidean Fourier transform. A generalization and a variant of Cowling-Price’s theorem, Beurling’s theorem and Donoho-Stark’s uncertainty principle are obtained for the Dunkl transform.
TL;DR: In this article, Guerrera et al. presented a research supported by MIUR-Urbino University, Cofin/2003 Grant (responsible F. Guerrera); CGL2005-03887 and CGL2009-09249 (Spanish Ministry of Education and Science) and Research Groups and projects of the Generalitat Valenciana from Alicante University (CTMA-IGA).
TL;DR: In this article, the mid-late Aptian inner-tropical carbonate ramp deposits of the Serdj Formation at Djebel Serdj, north-central Tunisia are studied in detail with regard to microfacies, lithology, biostratigraphy and chemostratigas.
Abstract: During the Aptian, some carbonate platforms of the sub-tropical realm (for example, on the northern Tethys margin or in the Gulf of Mexico) were affected repeatedly by severe perturbations in the carbonate production factory and drowning, preferentially during global warming events such as the Early Aptian Oceanic Anoxic Event 1a and a prominent mid-Late Aptian warming interval. These platform growth crises have been explained mainly by strongly increased coastal runoff (for example, siliciclastics and nutrients) in combination with pronounced eustatic sea-level rises. In the last few years, increasing evidence suggests that carbonate platforms of lower latitudes were generally less or even not affected by environmental perturbations during these events. This raises the question as to the responsible factors that promoted platform growth or decline in different latitudinal areas. In this study, Upper Aptian (Middle Gargasian to Uppermost Clansayesian) inner-tropical carbonate ramp deposits of the Serdj Formation at Djebel Serdj, north-central Tunisia are studied in detail with regard to microfacies, lithology, biostratigraphy and chemostratigraphy. These data allow reconstruction of the palaeoenvironmental evolution of the Tunisian carbonate platform margin and investigation of its response to the prominent mid-Late Aptian warming interval. The unusually expanded, 600 m thick Serdj Formation consists of limestones, marlstones and siltstones, suggesting deposition within mid-ramp to inner-ramp palaeoenvironments. Deposits of the mid-Late Aptian are represented by quartz-rich platform carbonates and siltstones, probably resulting from increased coastal runoff on the Tunisian shelf as a response to global warming and accelerated water cycling. The siliciclastic input was accompanied by elevated nutrient levels as indicated by a partial decline in the abundance of oligotrophic biota and mass occurrences of orbitolines and green algae. Carbonate platform drowning during the mid-Late Aptian, as reported from the sub-tropical realm, has not been identified. A comparison with other tropical river-influenced platforms suggests that none of them drowned during the mid-Late Aptian. One important reason might be widespread arid to semi-arid climatic conditions within lower latitudes during that time, promoting platform growth due to comparably low nutrient runoff.
TL;DR: Clinical differences between LRRK2, PINK1 and genetically undefined familial PD appear more pronounced than previously appreciated, and may prove useful in clinical practice.
Abstract: Genetic classification of Parkinson9s disease (PD) subtypes may become the preferred diagnostic tool for neurologists. Herein we compare clinical features from a large cohort of patients with familial PD of unknown aetiology or attributable to distinct genetic forms. Comprehensive neurological examinations were performed in 231 familial PD patients from Tunisia. Analysis was previously performed to screen for mutations in leucine rich repeat kinase 2 ( LRRK2 ), PTEN induced kinase 1 ( PINK1 ) and parkin ( PRKN ). Clinical features were compared between patients with genetically undefined PD (n=107) and those with LRRK2 (n=73) and PINK1 (n=42) mutations using regression analyses adjusted for gender, age of onset and disease duration. PRKN cases (n=9) were too few for meaningful statistical analysis. In comparison with genetically undefined patients, LRRK2 mutation carriers had more severe motor symptoms (median Unified Parkinson9s Disease Rating Scale scores ∼1.6 times higher, p PINK1 mutation carriers presented an increased rate of drug induced dyskinesia (OR 3.81, p=0.007) and a lower rate of postural tremor (OR 0.16, p PINK1 patients had younger ages and ages at disease onset, and a longer disease duration compared with LRRK2 mutation carriers and genetically undefined patients. Clinical differences between LRRK2 , PINK1 and genetically undefined familial PD appear more pronounced than previously appreciated, and may prove useful in clinical practice. As future therapies are targeted to specific protein abnormalities, identifying the genetic causes and associated clinical and pathological features will determine diagnosis, preventative medicine and drug intervention strategies.
TL;DR: According to the norms adopted by the National Network of observation of the marine life quality (RNO 1997) and US National Oceanic and Atmospheric Administration (US NOAA 1999), the superficial sediments of the Bizerte lagoon (northern Tunisia) show a contamination by nickel, which is the probable consequence of the closeness to the industrial zone, and by lead, the result of detrital material rich in lead of the geological lands of Jbel Kchabta and Jbel Messeftine as mentioned in this paper.
Abstract: According to the norms adopted by the National Network of observation of the marine life quality (RNO 1997) and US National Oceanic and Atmospheric Administration (US NOAA 1999), the superficial sediments of the Bizerte lagoon (northern Tunisia) show a contamination by nickel, which is the probable consequence of the closeness to the industrial zone, and by lead, the result of detrital material rich in lead of the geological lands of Jbel Kchabta and Jbel Messeftine. In the lagoon southern and eastern sectors, the contamination of superficial sediments is essentially by copper, zinc, nickel and iron. This pollution is related, on one hand, to the rejections of the steelworks El Fouledh and the military arsenal, and on the other hand, to Menzel Bourguiba waste disposal. The rest of the lagoon is exempted from any metallic contamination of the surface sediments. The enriched zones in manganese and zinc correspond to the higher contents in kaolinite and in smectite. Positive correlations were recorded between the percentage in fine fraction on the one hand, and the sedimentary contents in TOC, total nitrogen and heavy metals on the other hand. The majority of the analysed elements are “argilophilous” except zinc and manganese, which are clayey organophile. These results show that this lagoon receives concentrations in anthropogenic metals that risk provoking more or less important disruptions, which are harmful and irreversible on the fauna and flora of this lagoon and on the whole ecobiological equilibrium.