Institute National Agronomique Of Tunis

Tunis, Tunisia

Institute National Agronomique Of Tunis

Tunis, Tunisia
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Zened A.,French National Institute for Agricultural Research | Zened A.,National Polytechnic Institute of Toulouse | Troegeler-Meynadier A.,French National Institute for Agricultural Research | Troegeler-Meynadier A.,National Polytechnic Institute of Toulouse | And 3 more authors.
Journal of Dairy Science | Year: 2012

Among trans fatty acids, trans-10,. cis-12 CLA has negative effects on cow milk fat production and can affect human health. In high-yielding dairy cows, a shift from the trans-11 to the trans-10 pathway of biohydrogenation (BH) can occur in the rumen of cows receiving high-concentrate diets, especially when the diet is supplemented with unsaturated fat sources. In some but not all experiments, vitamin E has been shown to control this shift. To ascertain the effects of vitamin E on this shift of BH pathway, 2 studies were conducted. The first study explored in vitro the effects of addition of natural (RRR-α-tocopherol acetate) and synthetic (dl-α-tocopherol acetate) vitamin E. Compared with control and synthetic vitamin E, the natural form resulted in a greater trans-10/. trans-11 ratio; however, the effect was very low, suggesting that vitamin E was neither a limiting factor for rumen BH nor a modulator of the BH pathway. An in vivo study investigated the effect of natural vitamin E (RRR-α-tocopherol) on this shift and subsequent milk fat depression. Six rumen-fistulated lactating Holstein cows were assigned to a 2 × 2 crossover design. Cows received 20-kg DM of a control diet based on corn silage with 22% of wheat, and after 2 wk of adaptation, the diet was supplemented with 600 g of sunflower oil for 2. more weeks. During the last week of this 4-wk experimental period, cows were divided into 2 groups: an unsupplemented control group and a group receiving 11 g of RRR-α-tocopherol acetate per day. A trans-10 shift of ruminal BH associated with milk fat depression due to oil supplementation of a high-wheat diet was observed, but vitamin E supplementation of dairy cows did not result in a reversal toward a trans-11 BH pathway, and did not restore milk fat content. © 2012 American Dairy Science Association.

Kouzana L.,University of Tunis | Benassi R.,University of Tunis | Ben mammou A.,University of Tunis | Sfar felfoul M.,Institute National Agronomique Of Tunis
Journal of African Earth Sciences | Year: 2010

Coastal aquifers serve as major sources for freshwater supply in many countries around the world, especially in arid and semi arid zones. The fact that coastal zones contain some of the densely populated areas in the world makes the need for freshwater even more acute. The intensive extraction of groundwater from coastal aquifers reduces freshwater outflow to the sea and creates local water aquifer depression, causing seawater migration inland and rising toward the wells. This phenomenon, called seawater intrusion, has become one of the major constraints imposed on groundwater utilization. As seawater intrusion progresses, existing pumping wells become saline and have to be abandoned.In this paper, we have the results of the seawater intrusion study of the Korba aquifer by the geophysical and hydrochemical methods. In order to locate the zones affected by saltwater intrusion, 38 Vertical electrical sounding (VES) were distributed over the coastal area between Korba and Oued Lebna. The interpretation of these electric soundings using Winsev software, based on mechanical boreholes, carry out iso-resistivity and iso-depth maps of seawater intrusion. The maps of apparent iso-resistivity having different lengths of line and the pseudosections differentiate dry grounds, grounds saturated with fresh water and those saturated with brackish water and saltwater. Mapping of the boundaries between freshwater and saltwater is an ideal application for resistivity surveys because of the high electrical conductivity of the saltwater and its contrast with that of fresh water. The correlation of the different electric surveys allowed realizing geo-electric sections showing the vertical configuration of seawater intrusion. It comes out from this study that saltwater intrusion reached approximately a distance of 3. km inland.The high groundwater salinity anomaly observed in Diar El Hajjej, Garaet Sassi and Takelsa-Korba zones was explained by the presence of seawater intrusion in these areas. This hypothesis is based on high chloride concentrations, the inverse cationic exchange reactions, and the lower piezometric level compared to sea level. © 2010 Elsevier Ltd.

Belkhodja H.,Institute Superieur Of Peche Et Daquaculture Of Bizerte | Jaafoura M.H.,Institute Mohamed Kassab DOrthopedie | Missaoui H.,Direction Generale de la Peche et de LAquaculture de Tunis | Romdhane M.S.,Institute National Agronomique Of Tunis
Cahiers de Biologie Marine | Year: 2011

This study devised a staging system for and monitored the gonad development of the limpet Patella caerulea in La Goulette harbour (Gulf of Tunis) using a Gonad Somatic Index (GSI) and histological techniques. Sex ratio varied along the study period, where samples always presenting more males than females. Maturation began in August/September for both sexes. In males, spawning took place from March to August 2006 and from April to June 2007. Regarding females, spawning took place from May to July 2006 and from April to July 2007. A secondary spawning peak was observed in January 2007 for both sexes. No statistical differences were registered between GSI of both sexes; however, the use of the GSI in determining the annual reproductive cycle is discussed. High wind speed under optimum conditions of temperature and salinity appear to induce spawning in the limpets.

Belkhodja H.,Institute Superieur Of Peche Et Daquaculture Of Bizerte | Missaoui H.,Direction Generale de la peche et de lAquaculture de Tunis | Romdhane M.S.,Institute National Agronomique Of Tunis
Cahiers de Biologie Marine | Year: 2012

The limpets Patella caerulea was evaluated as possible biomonitor of heavy metal contamination in marine coastal areas. Water samples and specimens of the limpet were sampled seasonally during 2006-2007, from three different stations in the North coasts of Tunisia (Bizerta Channel: CB, La Goulette: LG and Sidi Rais: SR) to measure their accumulated heavy metal concentrations. The concentrations of Fe, Mn, Cu, Cd, Cr, Ni, Al and Pb were determined by ICP-OES methods. In water samples, only 3 metals (Mn, Cu and Al) were detected at different stations while in the limpet all the investigated metals were found. Iron and Aluminium concentrations in soft tissues of P. caerulea were significantly higher (ANOVA, p < 0.05) than the concentration of the other metals in all the stations while the lowest one was cadmium concentration. The order of metal accumulation in the animal at different stations was: Fe >> Al >> Mn - Cu > Ni - Pb > Cr > Cd. The highest mean values of the heavy metals in soft tissues of P. caerulea were found at CB station, for Cd, Cr and Fe. We also noticed at the same station relatively high mean values for Ni, Al and Pb; at LG station, for Mn, Cu and Pb and at SR station for Al.

Boukef S.,Institute National Agronomique Of Tunis | McDonald B.A.,ETH Zurich | Yahyaoui A.,International Center for Agricultural Research in the Dry Areas | Rezgui S.,Institute National Agronomique Of Tunis | Brunner P.C.,ETH Zurich
European Journal of Plant Pathology | Year: 2012

The occurrence of fungicide resistance in Mycosphaerella graminicola populations from Tunisia was investigated by examining mutations known to be associated with strobilurin and azole resistance. Few mutations associated with fungicide resistance were detected. No evidence for strobilurin resistance was found among 357 Tunisian isolates and only two among 80 sequenced isolates carried mutations associated with azole resistance. A network analysis suggested that these mutations emerged independently from mutations found in previously described European populations. The population genetic structure of M. graminicola in Tunisia was analyzed using variation at 11 microsatellite loci. Populations in Tunisia were characterized by high gene and genotype diversity. All populations were in gametic equilibrium and mating type proportions did not deviate from the 1:1 ratio expected under random mating, consistent with regular cycles of sexual reproduction. In combination with a high degree of gene flow among sampling sites, M. graminicola must be considered a pathogens with high evolutionary potential. Thus, control strategies against Septoria blotch in Tunisia should be optimized to reduce the emergence and spread of resistant isolates. © 2011 KNPV.

Armi Z.,Institute National Des Science Et Technology Of La Mer | Armi Z.,Institute National Agronomique Of Tunis | Turki S.,Institute National Des Science Et Technology Of La Mer | Trabelsi E.,Laboratoire Des Analyses Of Leau Of Mer | Ben Maiz N.,Laboratoire Des Analyses Of Leau Of Mer
Environmental Monitoring and Assessment | Year: 2010

Coolia monotis is a potentially toxic epiphytic dinoflagellate widespread along the Mediterranean coasts, where it is frequently detected year round at low concentrations. However, it only proliferates recurrently in some localities. The North Lake of Tunis is one of the affected areas in the southwestern part of the Mediterranean Sea. This site is one of the most productive aquatic Tunisian areas (Recreational Fisheries and shellfish collecting). In the south part of this area of study, recurrent C. monotis proliferation (5 ×10 5 cells per liter) took place in late spring and early summer of 2006. During this proliferation, the spatial distribution of C. monotis species, phytoplankton community, and abiotic factors were studied. The composition of the phytoplankton community exhibited a clear dominance of dinoflagellates over other genera. We suggest that proliferation development of C. monotis was linked to climatic conditions, water temperature (r=0.24, p<0.05) and high concentrations of nitrogenous nutrients, essentially NH 4 + (r=0.18, p<0.05) and NO 3 - (r=0.21, p<0.05). © 2009 Springer Science+Business Media B.V.

Sabbahi S.,Institute National Of Recherche En Genie Rural Eaux Et Forets Inrgref | Ben Ayed L.,Institute National Agronomique Of Tunis | Boudabbous A.,Laboratoire Microorganismes et Biomolecules Actives
Journal of Water and Health | Year: 2013

The aim of this study was to evaluate the photobactericidal effect of four photosensitizers (PSs) with different structural and physico-photochemical properties, namely mesotetracationic porphyrin (T4MPyP), dianionic rose Bengal (RB), monocationic methylene blue (MB) and neutral red (NR). Their photokilling activity was tested in vitro on pathogenic bacteria such as Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) suspended in nutrient broth (NB) and in phosphate buffered saline (PBS) through following their influence on the PSs antimicrobial efficacy. Photodynamic inactivation (PDI) experiments were performed using visible light (L) and different PSs concentrations (20-70 μM). The ability of these PSs to mediate bacterial photodynamic inactivation was investigated as a function of type of PS and its concentrations, spectral and physico-chemical properties, bacterial strain, irradiation time and suspending medium. Indeed, they showed antibacterial effects against S. aureus and P. aeruginosa with significant difference in potency. Staphylococcus aureus suspended in NB showed 0.92 log units reduction in viable count in the presence of T4MPyP at 20 μM. Changing the suspending medium from NB to PBS, S. aureus was successfully photoinactivated by T4MPyP (20 μM) when suspended in PBS at least time exposure (10 and 30 min), followed by MB and RB. © IWA Publishing 2013.

Khomsi S.,CNRS Georesources lab | Khomsi S.,King Abdulaziz University | Echihi O.,ETAP | Slimani N.,Institute National Agronomique Of Tunis
Comptes Rendus - Geoscience | Year: 2012

A set of different data including high resolution seismic sections, petroleum wire-logging well data, borehole piezometry, structural cross-sections and outcrop analysis allowed us to characterise the tectonic framework, and its relationships with the deep aquifers seated in Cretaceous-Miocene deep reservoirs. The structural framework, based on major structures, controls the occurrence of deep aquifers and sub-basin aquifer distributions. Five structural domains can be defined, having different morphostructural characteristics. The northernmost domain lying on the north-south axis and Zaghouan thrust system is a domain of recharge by underflow of the different subsurface reservoirs and aquifers from outcrops of highly fractured reservoirs. On the other hand, the morphostructural configuration controls the piezometry of underground flows in the Plio-Quaternary unconfined aquifer. In the subsurface the Late Cretaceous-Miocene reservoirs are widespread with high thicknesses in many places and high porosities and connectivities especially along major fault corridors and on the crestal parts of major anticlines. Among all reservoirs, the Oligo-Miocene, detritic series are widespread and present high cumulative thicknesses. Subsurface and fieldwork outline the occurrence of 10 fractured sandy reservoirs for these series with packages having high hydrodynamic and petrophysical characteristics. These series show low salinities (maximum 5. g/l) in the northern part of the study area and will constitute an important source of drinkable water for the next generations. A regional structural cross-section is presented, compiled from all the different data sets, allowing us to define the major characteristics of the hydrogeological-hydrogeothermal sub-basins. Eight hydrogeological provinces are defined from north-west to south-east. A major thermal anomaly is clearly identified in the south-eastern part of the study area in Sfax-Sidi Il Itayem. This anomaly is possibly related to major faults pertaining to the Sirt basin and controlled by a deep thermal anomaly. Many exploration targets are identified especially along the Cherichira-Kondar thrust where the Oligocene subcropping reservoirs are well developed. They are highly fractured and show good hydrodynamic characteristics. © 2012 Académie des sciences.

El Adib S.,Institute National Agronomique Of Tunis | Aissi O.,Institute National Des Science Appliquees Et Of Technology | Charrouf Z.,Mohammed V University | Ben Jeddi F.,Institute National Agronomique Of Tunis | Messaoud C.,Institute National Des Science Appliquees Et Of Technology
Chemistry and Biodiversity | Year: 2015

Argania spinosa includes two varieties, var. apiculata and var. mutica. These argan varieties were introduced into Tunisia in ancient times and are actually cultivated in some botanic gardens. Little is known about the chemical differentiation among these argan varieties. Hence, the aim of this study was to determine the fatty-acid composition, the total phenolic and flavonoid contents, and the antioxidant and α-amylase-inhibitory activities of leaf, seed, and pulp extracts of both argan varieties harvested during the months of January to April. The fatty-acid distribution was found to depend on the argan variety, the plant organ, and the harvest time. Significant variations in the phenolic contents were observed between the investigated varieties as well as between leaves, pulps, and seeds of each variety. As expected, phenolic compounds were found to be contributors to the antioxidant and α-amylase-inhibitory activities of both argan varieties. The chemical differentiation observed among the two argan varieties, based mainly on the fatty-acid composition, might have some chemotaxonomic value. Copyright © 2015 Verlag Helvetica Chimica Acta AG, Zürich.

Najar T.,Institute National Agronomique Of Tunis
Environmental Earth Sciences | Year: 2011

The quantity of herbage intake by sicilo-sarde dairy ewes, under a rotational grazing system, was determined by the method of count bite. Measurements were taken on a mountainous area of Béja (northern west of Tunisia) being the pasture mainly constituted by herbaceous species, especially of the graminaceous ones, its composition as well as bite weight and rate were estimated. Grazing time was around 7 h per day. Average ewes dairy production was around 0.8 kg per day (0.4-1.3 kg). All ewes were supplemented by avena hay ad labitum, and 0.35-0.70 kg of concentrate. Concentrate feed consisted of a mixture of barley, wheat bran, and soybean meal. The results obtained show that biting rate varies between dairy ewes according to their milk production, and pasture availability. The average pasture consumption varied between 420 and 640 g/day. Pasture consumption increases with the level of production and concentrate in the diet. Individual intake variability was also observed, and can be related to other zootechnical factors such as age and weight of the animals. © Springer-Verlag Berlin Heidelberg 2011.

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