National Agronomic Institute of Tunis

Tunis, Tunisia

National Agronomic Institute of Tunis

Tunis, Tunisia
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Abid M.,Institute of Arid lands | Mansour E.,Institute of Arid lands | Yahia L.B.,Institute of Arid lands | Bachar K.,Institute of Arid lands | And 2 more authors.
Italian Journal of Animal Science | Year: 2016

Medicago sativa is the main perennial legume in many places in the world such as South-East Tunisian Oases. The widespread use of this species is due to its high adaptability, forage yield potential and to its good quality. Furthermore, the succession of drought years in South-East Tunisian Oases especially in Gabes influenced fodder distribution and digestibility. To a better understanding of the variation of the nutritive value of (Medicago sativa L.) plants, the effect of four drought levels (25%; 50%; 75% and 100% of field capacity) on nutritive quality was investigated for three populations [P1 (Gannouch); P2 (Chenini) and P3 (Tebelbou)] cultivated in these oases. Results showed that drought reduced leaves, shoots and roots dry matter, while this effect was more pronounced for above organs (values reached 1.2mg) than below organs (values reached 1.8mg). However, drought decreased phosphor, calcium, magnesium and nitrogen contents, neutral detergent fibre, acid detergent fibre and in acid detergent lignin content for P1 and P2, this stress enhanced potassium uptake, leaves shoots and roots shoots ratios especially for P3, values passed from 1.56 for control treatment to 2.06 for 25% of field capacity. This population seems to be the most resistant to drought by maintaining reduced leaf area and elevated ratios. This result indicates that Medicago sativa succeed to maintain a good nutritive value under stress conditions. To the best of our knowledge, it is important to study the effect of this stress on others varieties to more understand its effect on nutritive value. © 2016 The Author(s).


Gsim K.,National Agronomic Institute of Tunis | Romdhane M.S.,National Agronomic Institute of Tunis | Jupsin H.,University of Liège | Vasel J.L.,University of Liège | Marouani L.,National Sanitation Utility ONAS
Desalination and Water Treatment | Year: 2015

Korba’s wastewater treatment plant is a conventional activated sludge, followed by three maturation ponds in series. During this study, pH, temperature, dissolved oxygen (DO), chemical oxygen demand, biochemical oxygen demand, suspended solid, and feacal bacteria were monitored.The interactions between the physicochemical and biological parameters involved in the natural disinfection process are presented and discussed. In situ analyses were also conducted to study the seasonal variation of phytoplankton, zooplankton, and daily fluctuations of physicochemical parameters. This work shows the efficiency of the maturation ponds to improve the quality of treated water from existing activated sludge treatment plants. Light has a main role in the removal of feacal coliform in maturation ponds. It has a synergistic effect with pH, DO and temperature in the ponds. Regarding the influence of the operating conditions on the decay of Escherichia coli and streptococci in the ponds, a predominance of high pH, DO, and temperature was observed. The results show a direct relationship between DO increase and pH. Improving abiotic conditions in the spring (rise in temperature, photoperiod, and light intensity) and the presence of nutrients in summer promote more algal diversity and density of Cyanobacteria (Oscillatoria), chlorophyceae (Chlamydomonas sp.), Euglenophyceae (phacus), and Diatoms (Cyclotella). © 2014, © 2014 Balaban Desalination Publications. All rights reserved.


Bosch-Belmar M.,University of Salento | Bosch-Belmar M.,Consorzio Nazionale Interuniversitario per le Science Del Mare | M'Rabet C.,National Agronomic Institute of Tunis | Dhaouadi R.,Ecole Nationale de Medecine Veterinaire | And 6 more authors.
PLoS ONE | Year: 2016

Jellyfish are of particular concern for marine finfish aquaculture. In recent years repeated mass mortality episodes of farmed fish were caused by blooms of gelatinous cnidarian stingers, as a consequence of a wide range of hemolytic, cytotoxic, and neurotoxic properties of associated cnidocytes venoms. The mauve stinger jellyfish Pelagia noctiluca (Scyphozoa) has been identified as direct causative agent for several documented fish mortality events both in Northern Europe and the Mediterranean Sea aquaculture farms. We investigated the effects of P. noctiluca envenomations on the gilthead sea bream Sparus aurata by in vivo laboratory assays. Fish were incubated for 8 hours with jellyfish at 3 different densities in 300 l experimental tanks. Gill disorders were assessed by histological analyses and histopathological scoring of samples collected at time intervals from 3 hours to 4 weeks after initial exposure. Fish gills showed different extent and severity of gill lesions according to jellyfish density and incubation time, and long after the removal of jellyfish from tanks. Jellyfish envenomation elicits local and systemic inflammation reactions, histopathology and gill cell toxicity, with severe impacts on fish health. Altogether, these results shows P. noctiluca swarms may represent a high risk for Mediterranean finfish aquaculture farms, generating significant gill damage after only a few hours of contact with farmed S. aurata. Due to the growth of the aquaculture sector and the increased frequency of jellyfish blooms in the coastal waters, negative interactions between stinging jellyfish and farmed fish are likely to increase with the potential for significant economic losses. © 2016 Bosch-Belmar et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


PubMed | Ecole Nationale de Medecine Veterinaire, CSIC - Institute of Marine Sciences, University of Salento, Institute Superieur Of Peche Et Daquaculture Bizerte and 2 more.
Type: Journal Article | Journal: PloS one | Year: 2016

Jellyfish are of particular concern for marine finfish aquaculture. In recent years repeated mass mortality episodes of farmed fish were caused by blooms of gelatinous cnidarian stingers, as a consequence of a wide range of hemolytic, cytotoxic, and neurotoxic properties of associated cnidocytes venoms. The mauve stinger jellyfish Pelagia noctiluca (Scyphozoa) has been identified as direct causative agent for several documented fish mortality events both in Northern Europe and the Mediterranean Sea aquaculture farms. We investigated the effects of P. noctiluca envenomations on the gilthead sea bream Sparus aurata by in vivo laboratory assays. Fish were incubated for 8 hours with jellyfish at 3 different densities in 300 l experimental tanks. Gill disorders were assessed by histological analyses and histopathological scoring of samples collected at time intervals from 3 hours to 4 weeks after initial exposure. Fish gills showed different extent and severity of gill lesions according to jellyfish density and incubation time, and long after the removal of jellyfish from tanks. Jellyfish envenomation elicits local and systemic inflammation reactions, histopathology and gill cell toxicity, with severe impacts on fish health. Altogether, these results shows P. noctiluca swarms may represent a high risk for Mediterranean finfish aquaculture farms, generating significant gill damage after only a few hours of contact with farmed S. aurata. Due to the growth of the aquaculture sector and the increased frequency of jellyfish blooms in the coastal waters, negative interactions between stinging jellyfish and farmed fish are likely to increase with the potential for significant economic losses.


Ben Ammar I.,University of Lorraine | Ben Ammar I.,National Agronomic Institute of Tunis | Teletchea F.,University of Lorraine | Milla S.,University of Lorraine | And 4 more authors.
Fish Physiology and Biochemistry | Year: 2015

The effect of a constant photoperiod on the inhibition of male and female reproductive cycles was studied in pikeperch Sander lucioperca. Over a 153-day period, batches of pikeperch (2 years, 950 g) breeders were kept under either under natural or artificial photoperiod conditions (24L:0D) (30–35 fish/tank, triplicate) and sampled in late June (start of the photoperiod decrease in natural conditions), late August (start of temperature decrease) and late November (exogenous vitellogenesis) (7–10 fish/tank/sampling date). Morphological parameters, sexual steroids, alkaline-labile phosphate (µg/mL) levels and gamete developmental stages were investigated. Gonado-somatic index (%), developmental stages and sexual steroid levels (17β-estradiol, testosterone and 11-ketotestosterone, ng/mL) in both sexes and oocyte diameter (µm) and plasma alkaline-labile phosphate (µg/mL) in females were lower in response to a continuous lighting (24L:0D). In both sexes, continuous lighting applied in June for 153 days totally inhibited or delayed the onset of the reproductive cycle. In conclusion, photoperiod manipulation can be used to delay the pikeperch reproductive cycle, even if temperature decreases. This is the first report of the inhibitory effect of photoperiod on the onset of the reproductive cycle in pikeperch. © 2014, Springer Science+Business Media Dordrecht.


Ensibi C.,University of Carthage | M'rabet C.,National Agronomic Institute of Tunis | Chalghaf M.,Higher Institute of Fisheries and Aquaculture of Bizerte | Daly-Yahia M.N.,University of Carthage
Aquaculture International | Year: 2016

During the last decade, massive blooms of jellyfish have occurred in the Mediterranean basin, putting great concern on cultured fish in offshore cage. Current studies enter in this task, and they consist on examining the antioxidant responses as well as lipid peroxidation and mucous secretion in gills of the gilthead sea bream (Sparus aurata). This is done upon exposure to the scyphozoan jellyfish Pelagia noctiluca at environmentally realistic densities (3, 7 and 15 individus per tanks). This finding revealed that P. noctiluca was a highly toxic organism to the cultured fish. Morphological examination showed lesions of the secondary gill lamellae in fish exposed to jellyfish. Enzymatic activities were measured after 0, 1, 2, 7, 15 and 30 days after initiating the exposure. The set of analyzed activities included catalase (CAT) and glutathione reductase (GR) activities. Lipid peroxidation was measured by quantifying malondialdehyde (MDA). Estimation of mucus secretion was done by using the phenol sulfuric acid assay protocol. The results showed that jellyfish induced antioxidant enzyme activities (CAT, GR) at different densities. Gills MDA content was significantly increased in all treated groups versus the control groups throughout the exposure periods. Our results show also that fish exposed to jellyfish swarms showed mucus hypersecretion on gills. Based on the results of this study, we consider the scyphozoan jellyfish P. noctiluca to be harmful in aquaculture system. The observed changes in analyzed parameters (especially CAT and GR activities, MDA contents and mucous production) suggest that these parameters could be useful tools in environmental monitoring programs of the aquaculture where jellyfish blooms occur. © 2016 Springer International Publishing Switzerland


Somai-Jemmali L.,National Agronomic Institute of Tunis | Randoux B.,University of Lille Nord de France | Siah A.,University of Lille Nord de France | Magnin-Robert M.,University of Lille Nord de France | And 3 more authors.
European Journal of Plant Pathology | Year: 2016

Bread wheat (BW) and durum wheat (DW) are both strongly affected by Septoria tritici blotch caused by the hemibiotrophic fungus Zymoseptoria tritici. However, only the BW-Z. tritici pathosystem has been well studied so far. Here, we compared compatible interactions between Z. tritici and both BW and DW species at the cytological, biochemical and molecular levels. Fungal infection process investigations showed close spore germination and leaf penetration features in both interactions, although differences in the patterns of these events were observed. During the necrotrophic phase, disease severity and sporulation levels were associated in both interactions with increases of the two cell-wall degrading enzyme activities endo-β-1,4-xylanase and endo-β-1,3-glucanase as well as protease. An analysis of plant defense responses during the first five days post inoculation revealed inductions of GLUC, Chi4, POX and PAL and a repression of LOX gene expressions in both wheat species, although differences in kinetics and levels of induction or repression were observed. In addition, peroxidase, catalase, glucanase, phenylalanine ammonia-lyase and lipoxygenase activities were induced in both wheat species, while only weak accumulations of hydrogen peroxide and polyphenols were detected at the fungal penetration sites. Our study revealed overall a similarity in Z. tritici infection process and triggered wheat defense pathways on both pathosystems. © 2016 Koninklijke Nederlandse Planteziektenkundige Vereniging


Guettaya I.,National Agronomic Institute of Tunis | El Ouni M.R.,National Agronomic Institute of Tunis
Frontiers of Structural and Civil Engineering | Year: 2014

The present paper examines the evaluation of liquefaction potential of an earth dam foundation in Tunisia. The assessment of soil liquefaction was made using deterministic and probabilistic simplified procedures developed from several case histories. The data collected from the field investigation performed before and after the vibrocompaction are analyzed and the results are reported. The obtained results show that after vibrocompaction, a significant improvement of the soil resistance reduces the liquefaction potential of the sandy foundation. Indeed, in the untreated layers, the factor of safety FS drops below 1 which means that the soil is susceptible for liquefaction. However, in the compacted horizons, the values of FS exceed the unit which justifies the absence of liquefaction hazard of the foundation. © 2014, Higher Education Press and Springer-Verlag Berlin Heidelberg.

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