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21.
Eya Khemis Mayssa Ben Mustapha Ikbel Chaieb Roberta Ascrizzi Guido Flamini Abdel Halim Harrath Hichem Ben Jannet Afifa Zardi-Bergaoui 《化学与生物多样性》2023,20(2):e202200646
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. 相似文献
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Mustapha Faghire Farissi Mohamed Khadijattou Taoufiq Rachid Fghire Adnane Bargaz Btissam Mandri Khalid Oufdou Amenc Laury Jean-Jacques Drevon Cherki Ghoulam 《Symbiosis (Philadelphia, Pa.)》2013,60(3):115-122
The effect of salt stress, under glasshouse conditions, was studied on plant biomass, nodulation, and activities of acid phosphatases (APase, EC 3.1.3.2) and trehalose 6-phosphate phosphatase (TPP, EC 3.1.3.12) in the symbiosis common bean (Phaseolus vulgaris L.)-rhizobia nodules. Four common bean recombinant inbred lines (147, 115, 104 and 83) were separately inoculated, with CIAT 899 or RhM11 strains and grown in hydroaeroponic culture. Two NaCl levels (0 and 25 mM NaCl plant?1 week?1 corresponding, respectively, to the control and the salt treatment) were applied and the culture was assessed during 42 days after their transplantation. The results showed that the nodulation of these lines was not affected by salinity except for the line 83 inoculated with CIAT 899, whose nodule dry weight decreased by 48.24 % compared with the corresponding controls. For the other symbiotic combinations, shoot and root biomasses were not significantly affected by salt constraint. Salinity stress generally reduced acid phosphatise and trehalose phosphate phosphatase activities in nodules that were less affected in plants inoculated with RhM11. Based on our data, it appears that nodule phosphatase activity may be involved in salinity tolerance in common beans and the levels of salt tolerance depend principally on specific combination of the rhizobial strain and the host cultivar. 相似文献
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Balkiss Bouhaouala-Zahar Rym Benkhalifa Najet Srairi Ilhem Zenouaki Caroline Ligny-Lemaire Pascal Drevet Fran?ois Sampieri Marcel Pelhate Mohamed El Ayeb André Ménez Habib Karoui Frédéric Ducancel 《European journal of biochemistry》2002,269(12):2831-2841
BotXIV and LqhalphaIT are two structurally related long chain scorpion alpha-toxins that inhibit sodium current inactivation in excitable cells. However, while LqhalphaIT from Leiurus quinquestriatus hebraeus is classified as a true and strong insect alpha-toxin, BotXIV from Buthus occitanus tunetanus is characterized by moderate biological activities. To assess the possibility that structural differences between these two molecules could reflect the localization of particular functional topographies, we compared their sequences. Three structurally deviating segments located in three distinct and exposed loops were identified. They correspond to residues 8-10, 19-22, and 38-43. To evaluate their functional role, three BotXIV/LqhalphaIT chimeras were designed by transferring the corresponding LqhalphaIT sequences into BotXIV. Structural and antigenic characterizations of the resulting recombinant chimera show that BotXIV can accommodate the imposed modifications, confirming the structural flexibility of that particular alpha/beta fold. Interestingly, substitution of residues 8-10 yields to a new electrophysiological profile of the corresponding variant, partially comparable to that one of alpha-like scorpion toxins. Taken together, these results suggest that even limited structural deviations can reflect functional diversity, and also that the structure-function relationships between insect alpha-toxins and alpha-like scorpion toxins are probably more complex than expected. 相似文献
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Natochin M Gasimov KG Moussaif M Artemyev NO 《The Journal of biological chemistry》2003,278(39):37574-37581
Three cytoplasmic loops in the G protein-coupled receptor rhodopsin, C2, C3, and C4, have been implicated as key sites for binding and activation of the visual G protein transducin. Non-helical portions of the C2- and C3-loops and the cytoplasmic helix-8 from the C4 loop were targeted for a "gain-of-function" mutagenesis to identify rhodopsin residues critical for transducin activation. Mutant opsins with residues 140-148 (C2-loop), 229-244 (C3-loop), or 310-320 (C4-loop) substituted by poly-Ala sequences of equivalent lengths served as templates for mutagenesis. The template mutants with poly-Ala substitutions in the C2- and C3-loops formed the 500-nm absorbing pigments but failed to activate transducin. Reverse substitutions of the Ala residues by rhodopsin residues have been generated in each of the templates. Significant ( approximately 50%) restoration of the rhodopsin/transducin coupling was achieved with re-introduction of residues Cys140/Lys141 and Arg147/Phe148 into the C2 template. The reverse substitutions of the C3-loop residues Thr229/Val230 and Ser240/Thr242/Thr243/Gln244 produced a pigment with a full capacity for transducin activation. The C4 template mutant was unable to bind 11-cis-retinal, and the presence of Asn310/Lys311 was required for correct folding of the protein. Subsequent mutagenesis of the C4-loop revealed the role of Phe313 and Met317. On the background of Asn310/Lys311, the inclusion of Phe313 and Met317 produced a mutant pigment with the potency of transducin activation equal to that of the wild-type rhodopsin. Overall, our data support the role of the three cytoplasmic loops of rhodopsin and suggest that residues adjacent to the transmembrane helices are most important for transducin activation. 相似文献
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Three innovative and complementary morphological approaches were employed to study the T cell/antigen presenting cell (APC) interaction: (i) high resolution three-dimensional confocal microscopy of the T cell-APC contact site; (ii) time lapse video recording in living T cells of [Ca2+]I and changes in distribution of various GFP fusion proteins with TCR/CD3-zeta complex associated- and other signaling components; (iii) measurement of lateral TCR mobility and that of recruited signaling components using techniques based on fluorescence recovery after photo-bleaching. These approaches were combined with biochemical and functional experiments to investigate two principal issues: (A) Recruitment and the three-dimensional arrangement of receptors and signaling components at the contact site between human CD4+ T lymphocytes and APCs, (B) Structure of the immunological synapse formed at the contact site between cytotoxic T lymphocytes (CTLs) and target cells. We discuss evidence indicating that TCR engagement and triggering can occur in the absence of large-scale molecular segregation into the T cell-APC contact site. Taken together our results indicate that although not required for TCR engagement and triggering, formation of the IS is important to reinforce TCR-mediated signal transduction and achieve full T cell activation. 相似文献
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Bahassi el M Yin M Robbins SB Li YQ Conrady DG Yuan Z Kovall RA Herr AB Stambrook PJ 《Cell division》2011,6(1):4