Chemical Composition and Insecticidal Activity against Tribolium Castaneum of Thapsia garganica L. Seed Essential Oil

Due to the several side effects of synthetic pesticides, including environmental pollution, threats to human health, and the development of pest resistance to insecticides, the use of alternative healthy, available and efficient agents in pest management strategies is necessary. Recently, the use of essential oil obtained from aromatic plants has shown significant potential for insect pest management. For this reason, the essential oil isolated from seeds of Thapsia garganica L. was investigated for the first time for its chemical profile, and its toxicity and repellency effects against Tribolium castaneum adults. Qualitative and quantitative analyses of the chemical composition by gas chromatography coupled to mass spectrometry (GC/MS) revealed the presence of 18 organic volatiles representing 96.8 % of the total constituents. The main compounds were 1,4-dimethylazulene (51.3 %) followed by methyl palmitate (8.2 %), methyl linoleate (6.2 %) and costol (5.1 %). Concerning the repellent effect, results revealed that SEO (Seed Essential Oil) was very repellent towards T. castaneum adults, with 100 % repellency after 2 h of exposure. Furthermore, the essential oil exhibited remarkable contact toxicity against T. castaneum (93.3 % of mortality) at the concentration of 10 % (v/v). The median lethal dose (LD₅₀) of the topical application of the seed essential oil was 4.4 %. These encouraging outcomes suggested that the essential oil from T. garganica seeds could be considered a potent natural alternative to residual persistent and toxic insecticides.     

Seasonal dynamics of zooplankton community in four Mediterranean reservoirs in humid area (Beni Mtir: north of Tunisia) and semi arid area (Lakhmes,Nabhana and Sidi Saâd: center of Tunisia)

The zooplankton community was studied in four Mediterranean reservoirs to assess the relative importance of environmental factors as determinants of zooplankton dynamic in the four seasons. The water temperature and hydrology variations affect the distribution of zooplankton. A positive correlation was established between the total zooplankton and the water temperature (r=0.9, n=9, p<0.05). Fourteen zooplankton species were identified. Seasonal changes in the density (ANOVA, F=3.7, d.f=36, p<0.01) and the biomass of total zooplankton (ANOVA, F=4.4, d.f=36, p<0.001) were observed. Our results suggest that planktivorous fish may not modify the zooplankton dynamics in Beni Mtir reservoir (oligotrophic). On the contrary, in Sidi Saâd reservoir (mesotrophic), fish predation has major effects on seasonal zooplankton dynamics.     

Chemical Composition and Insecticidal Activity of Crithmum Maritimum L. Essential Oil against Stored‐Product Beetle Tribolium Castaneum

Several plant essential oils have been used against diverse insect pests since, unlike conventional pesticides, they pose almost no risk to humans and the environment. For this reason, the essential oil (EO) isolated from the fresh leaves of Crithmum maritimum L. and its fractions (F₁–F₅) obtained by chromatographic simplification were investigated for their chemical profile, as well as for their toxicity and repellency effects against Tribolium castaneum (Herbst ) adults. The analysis by GC/MS allowed the identification of 92.8–99.1 % of the compositions of the total oil (EO) and of its fractions (F₁–F₅). The EO and its fractions F₃–F₅ were characterized by the presence of a high amount of phenylpropanoids (94.4, 94.8, 93.6, and 88.7 %, respectively): in all the samples, dill apiole was the most abundant component (EO: 94.1 %, F₃: 94.6 %, F₄: 93.4 %, and F₅: 83.3 %). In addition, the repellency assay results showed that the volatile fraction F₅ and the complete EO exhibited a higher repellency towards T. castaneum (97 % and 93 %, respectively) after 2 h of exposure at the dose of 0.04 μL/cm². The median lethal dose of the topical application of the EO was 9 %. Furthermore, the fraction F₁ possessed interesting contact toxicity against T. castaneum (80 % of mortality) at the concentration of 10 %. These results suggested that the essential oil of C. maritimum leaves might be used as an alternative to synthetic insecticides in order to prevent insects from damaging the stored products.     

Prediction of T Cell Epitopes from Leishmania major Potentially Excreted/Secreted Proteins Inducing Granzyme B Production

Leishmania-specific cytotoxic T cell response is part of the acquired immune response developed against the parasite and contributes to resistance to reinfection. Herein, we have used an immune-informatic approach for the identification, among Leishmania major potentially excreted/secreted proteins previously described, those generating peptides that could be targeted by the cytotoxic immune response. Seventy-eight nonameric peptides that are predicted to be loaded by HLA-A*0201 molecule were generated and their binding capacity to HLA-A2 was evaluated. These peptides were grouped into 20 pools and their immunogenicity was evaluated by in vitro stimulation of peripheral blood mononuclear cells from HLA-A2⁺-immune individuals with a history of zoonotic cutaneous leishmaniasis. Six peptides were identified according to their ability to elicit production of granzyme B. Furthermore, among these peptides 3 showed highest affinity to HLA-A*0201, one derived from an elongation factor 1-alpha and two from an unknown protein. These proteins could constitute potential vaccine candidates against leishmaniasis.     

Recirculating Intestinal IgA-Producing Cells Regulate Neuroinflammation via IL-10

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Chemical composition and biological activities of essential oils of Salvia officinalis aerial parts as affected by diurnal variations

The main objective of this work is to evaluate the impact of the diurnal variation on the essential oil (EO) of Salvia officinalis and on their antioxidant, antifungal and insecticidal potentials. Obtained results showed that the chemical composition of EOs of sage varied significantly during the day. For the EO, the 7 am extract was characterized by the most significant antiradical activity. The EOs of 12 and 5 pm used at a dose of 10 μL were found to have the most effective potential to inhibit the growth of Botrytis cinerea whereas, the EO of 5 pm used at the same dose (10 μL) was the most effective against Fusarium sambucinum. For the fumigant test, the EO from 7 am had the highest activity against Spodoptera littoralis. The EO of 12 pm had the largest repellency activity against Trogoderma granarium. In addition, the EO from 7 am belongs to the repulsive class III, those of 12 and 5 pm belong to the repulsive class IV. The results of this study indicate how to optimize the best harvesting hour to obtain extracts characterized by the best yield of active compounds and by the more effective biological activity.     

Characterization of Coxsackievirus B4 virus-like particles VLP produced by the recombinant baculovirus-insect cell system expressing the major capsid protein

Molecular Biology Reports - Coxsackievirus B4 (CV-B4) is suspected to be an environmental factor that has the intrinsic capacity to damage the pancreatic beta cells and therefore causes insulitis...     

Abundance and biomass of rotifers in relation to the environmental factors in geothermal waters in Southern Tunisia

The spatial and temporal dynamics of rotifers in relation to the physico-chemical parameters in Fish-Culture Research Station (Southern Tunisia) were studied monthly from February 2005 to January 2006. Thirteen rotifer species were found: Brachionus urceolaris, Brachionus calyciflorus, Brachionus sp., Lecane stichaea, Lecane rhytida, Lecane sp., Hexarthra mira, Rotaria tardigrada, Conochiloides natans, Trichocerca marina, Keratella quadrata, Keratella cochlearis and Notommata codonella. The most dominant rotifer was B. urceolaris (76% of total abundance). Rotifer density and water temperature were negatively correlated (r=−0.94, n=12, p=0.001). The highest abundance of rotifers was found in basin 4 (1.5×10⁵ ind m⁻³, in June 2005).     

Survival and adhesion ability of <Emphasis Type="Italic">Shigella</Emphasis> spp. strains after their incubation in seawater microcosms

In this study, we investigated the survival and adhesion ability of Shigella after their incubation in seawater microcosms at ambient temperature and at 4°C during 1 month. Our results showed that the number of cells was considerably decreased after this period of stress. In addition, we have revealed some modifications in the biochemical and enzymatic profiles of stressed cells. These modification were noted by the appearance or/and the disappearance of some activities. Indeed, antibiotic susceptibility of stressed cells has been changed. Adherence assays to KB cells showed on increase in the number of adherent cells from 0.7 to 6.7% after 1 month of incubation in seawater.