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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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Samia Ammar Hayet Edziri Mohamed Ali Mahjoub Rym Chatter Abderrahman Bouraoui Zine Mighri 《Phytomedicine》2009,16(12):1156-1161
A sesquiterpenoid Bakkenolide (1), and two steroids, (3β, 22E)-Stigmasta-5, 22-diène-3-ol (Stigmasterol) (2) and stigmasterol 3β-glucoside (3), isolated from the Hertia cheirifolia (L.) chloroform extract, were evaluated respectively for their spasmolytic and anti-inflammatory activities. We note that these natural products were isolated and purified for the first time from the specie Hertia cheirifolia. Their structures have been established by spectroscopy (1 and 2D NMR experiences) and mass spectrometry. Chloroform-, ethyl acetate- and methanol-extracts were also tested for their spasmolytic and anti-inflammatory activities. Spasmolytic and anti-inflammatory screening were based respectively on the contractile response effects on rat isolated smooth muscles and on the dose-related carrageenan induced paw edema in rats. screening of the crude extracts showed spasmolytic and anti-inflammatory positive results. The antispasmodic effect of Bakkenolide was found in the same range as that of Alverine, a standard musculotropic spasmolytic agent. 相似文献
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Rym Zitari-Chatti Noureddine Chatti Domenico Fulgione Immacolata Caiazza Gennaro Aprea Ali Elouaer Khaled Said Teresa Capriglione 《Genetica》2009,136(3):439-447
In this study we analysed mitochondrial DNA variation in Penaeus kerathurus prawns collected from seven locations along a transect across the Siculo–Tunisian region in order to verify if any population
structuring exists over a limited geographical scale and to delineate the putative transition zone with sufficient accuracy.
Partial DNA sequences of COI and 16S genes were analysed. In contrast to the highly conservative 16S gene, the COI sequences
exhibited sufficient diversity for population analysis. The COI gene revealed low levels of haplotype and nucleotide diversities.
The size of the annual landings of this commercial species suggests large population sizes. Hence, the low genetic diversity
detected in this study could indicate a possible reduction in effective population sizes in the past. We detected significant
genetic differentiation between eastern and western populations likely due to restricted gene flow across the Siculo–Tunisian
boundary. We discuss the different evolutionary forces that may have shaped the genetic variation and suggest that the genetic
divide is probably maintained by present-day dispersal limitation.
R. Zitari-Chatti and N. Chatti are contributed equally to the work. 相似文献
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Rym Chamakh-Ayari Rachel Bras-Gon?alves Narges Bahi-Jaber Elodie Petitdidier Wafa Markikou-Ouni Karim Aoun Javier Moreno Eugenia Carrillo Poonam Salotra Himanshu Kaushal Narender Singh Negi Jorge Arevalo Francesca Falconi-Agapito Angela Privat Maria Cruz Julie Pagniez Gérard-Marie Papierok Faten Bel Haj Rhouma Pilar Torres Jean-Loup Lemesre Mehdi Chenik Amel Meddeb-Garnaoui 《PloS one》2014,9(5)
PSA (Promastigote Surface Antigen) belongs to a family of membrane-bound and secreted proteins present in several Leishmania (L.) species. PSA is recognized by human Th1 cells and provides a high degree of protection in vaccinated mice. We evaluated humoral and cellular immune responses induced by a L. amazonensis PSA protein (LaPSA-38S) produced in a L. tarentolae expression system. This was done in individuals cured of cutaneous leishmaniasis due to L. major (CCLm) or L. braziliensis (CCLb) or visceral leishmaniasis due to L. donovani (CVLd) and in healthy individuals. Healthy individuals were subdivided into immune (HHR-Lm and HHR-Li: Healthy High Responders living in an endemic area for L. major or L. infantum infection) or non immune/naive individuals (HLR: Healthy Low Responders), depending on whether they produce high or low levels of IFN-γ in response to Leishmania soluble antigen. Low levels of total IgG antibodies to LaPSA-38S were detected in sera from the studied groups. Interestingly, LaPSA-38S induced specific and significant levels of IFN-γ, granzyme B and IL-10 in CCLm, HHR-Lm and HHR-Li groups, with HHR-Li group producing TNF-α in more. No significant cytokine response was observed in individuals immune to L. braziliensis or L. donovani infection. Phenotypic analysis showed a significant increase in CD4+ T cells producing IFN-γ after LaPSA-38S stimulation, in CCLm. A high positive correlation was observed between the percentage of IFN-γ-producing CD4+ T cells and the released IFN-γ. We showed that the LaPSA-38S protein was able to induce a mixed Th1 and Th2/Treg cytokine response in individuals with immunity to L. major or L. infantum infection indicating that it may be exploited as a vaccine candidate. We also showed, to our knowledge for the first time, the capacity of Leishmania PSA protein to induce granzyme B production in humans with immunity to L. major and L. infantum infection. 相似文献
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Composition of a molluscan assemblage associated with macrophytes in Menzel Jemil (Bizerte lagoon,SW Mediterranean Sea) 下载免费PDF全文
Wahiba Zaabar Rym Zakhama‐Sraieb Faouzia Charfi‐Cheikhrouha Mohamed Sghaïer Achouri 《African Journal of Ecology》2018,56(3):537-547
The molluscan species composition and diversity associated with macrophytes was studied throughout 1 year at Menzel Jemil station (Bizerte lagoon, north‐west of Tunisia). A total of 7,539 individuals belonging to 13 species were collected. The molluscan assemblage was mainly composed of gastropods (98.12%, nine species), followed by bivalves (1.88%, four species). Hydrobia acuta ranked first with 49.97% of total abundance, followed by Bittium reticulatum (17.97%), Tritia mutabilis (11.38%), Haminoea navicula (8.98%), Phorcus articulatus (5.17%) and Cerithium vulgatum (3.94%). The large number of juvenile molluscs collected confirms the importance of macroalgae and seagrass for mollusc recruitment. Significant temporal variations of species richness, density and diversity indices of the mollusc assemblage have been observed during the year. Multivariate analyses applied to our data revealed significant relationships between the macrophyte composition and associated molluscan assemblage. The BIOENV analysis indicated that water temperature, phosphates concentration and macrophyte biomass were environmental variables most closely associated with the temporal variation of molluscan assemblage. 相似文献
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Béatrice Roche Rym Agrebi Allison Huguenot Sandrine Ollagnier de Choudens Frédéric Barras Béatrice Py 《PLoS genetics》2015,11(5)
Fe-S bound proteins are ubiquitous and contribute to most basic cellular processes. A defect in the ISC components catalyzing Fe-S cluster biogenesis leads to drastic phenotypes in both eukaryotes and prokaryotes. In this context, the Frataxin protein (FXN) stands out as an exception. In eukaryotes, a defect in FXN results in severe defects in Fe-S cluster biogenesis, and in humans, this is associated with Friedreich’s ataxia, a neurodegenerative disease. In contrast, prokaryotes deficient in the FXN homolog CyaY are fully viable, despite the clear involvement of CyaY in ISC-catalyzed Fe-S cluster formation. The molecular basis of the differing importance in the contribution of FXN remains enigmatic. Here, we have demonstrated that a single mutation in the scaffold protein IscU rendered E. coli viability strictly dependent upon a functional CyaY. Remarkably, this mutation changed an Ile residue, conserved in prokaryotes at position 108, into a Met residue, conserved in eukaryotes. We found that in the double mutant IscUIM ΔcyaY, the ISC pathway was completely abolished, becoming equivalent to the ΔiscU deletion strain and recapitulating the drastic phenotype caused by FXN deletion in eukaryotes. Biochemical analyses of the “eukaryotic-like” IscUIM scaffold revealed that it exhibited a reduced capacity to form Fe-S clusters. Finally, bioinformatic studies of prokaryotic IscU proteins allowed us to trace back the source of FXN-dependency as it occurs in present-day eukaryotes. We propose an evolutionary scenario in which the current mitochondrial Isu proteins originated from the IscUIM version present in the ancestor of the Rickettsiae. Subsequent acquisition of SUF, the second Fe-S cluster biogenesis system, in bacteria, was accompanied by diminished contribution of CyaY in prokaryotic Fe-S cluster biogenesis, and increased tolerance to change in the amino acid present at the 108th position of the scaffold. 相似文献
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