Fucoidans of Moroccan Brown Seaweed as Elicitors of Natural Defenses in Date Palm Roots     

Soukaina Bouissil  Zainab El Alaoui-Talibi  Guillaume Pierre  Halima Rchid  Philippe Michaud  Cdric Delattre  Cherkaoui El Modafar 《Marine drugs》2020,18(12)

Fucoidans from Moroccan brown seaweed Bifurcaria bifurcata and Fucus spiralis were tested for their elicitor activity after their purification and complete characterization. The fucoidans of B. bifurcata (BBF) and of F. spiralis (FSF) were extracted and purified then characterized by infrared spectroscopy, proton nuclear magnetic resonance spectroscopy and size exclusion chromatography. The results show that BBF and FSF are mainly sulfated with 45.49 and 49.53% (w/w) sulfate, respectively. Analysis of neutral sugars determined by gas chromatography–mass spectrometry showed that FSF and BBF were mainly composed of 64% and 91% fucose and 20% and 6% galactose, respectively, with a few other sugars such as glucose (8% in FSF), rhamnose (1% in BBF) and mannose (8% in FSF and, 2% in BBF). The eliciting activity of these sulfated polysaccharides in stimulating the natural defenses of the date palm was evaluated through the activity of phenylalanine ammonia-lyase (PAL), and the increase in phenols and lignin content in the roots. The results obtained clearly show that the two fucoidans early and intensely stimulate the natural defenses of the date palm after 24 h of treatments. This remarkable elicitor effect seems to be linked to the sulfated groups compared to non-sulfate alginates extracted from the same algae. These results open promising perspectives for a biological control approach against date palm diseases.  相似文献   

Utilization of Marine Waste to Obtain β-Chitin Nanofibers and Films from Giant Humboldt Squid Dosidicus gigas     

Gustavo Cabrera-Barjas  Cristian Gonzlez  Aleksandra Nesic  Kelly P. Marrugo  Oscar Gmez  Cdric Delattre  Oscar Valdes  Heng Yin  Gaston Bravo  Juan Cea 《Marine drugs》2021,19(4)

β-chitin was isolated from marine waste, giant Humboldt squid Dosidicus gigas, and further converted to nanofibers by use of a collider machine under acidic conditions (pH 3). The FTIR, TGA, and NMR analysis confirmed the efficient extraction of β-chitin. The SEM, TEM, and XRD characterization results verified that β-chitin crystalline structure were maintained after mechanical treatment. The mean particle size of β-chitin nanofibers was in the range between 10 and 15 nm, according to the TEM analysis. In addition, the β-chitin nanofibers were converted into films by the simple solvent-casting and drying process at 60 °C. The obtained films had high lightness, which was evidenced by the CIELAB color test. Moreover, the films showed the medium swelling degree (250–290%) in aqueous solutions of different pH and good mechanical resistance in the range between 4 and 17 MPa, depending on film thickness. The results obtained in this work show that marine waste can be efficiently converted to biomaterial by use of mild extractive conditions and simple mechanical treatment, offering great potential for the future development of sustainable multifunctional materials for various industrial applications such as food packaging, agriculture, and/or wound dressing.  相似文献   

Vole outbreaks in a landscape context: evidence from a six year study of Microtus arvalis   总被引：1，自引：0，他引：1  

Delattre  P.  De Sousa  B.  Fichet-Calvet  E.  Quéré  J.P.  Giraudoux  P. 《Landscape Ecology》1999,14(4):401-412

Landscape Ecology - Analysis of population variations in space and time suggests that landscape may act as a substrate for several kinds of interactions: neighborhood effects, edge effects,...  相似文献   

Kinetic study on the changes in the susceptibility of egg white proteins to enzymatic hydrolysis induced by heat and high hydrostatic pressure pretreatment     

Van der Plancken I  Delattre M  Indrawati I  Van Loey A  Hendrickx ME 《Journal of agricultural and food chemistry》2004,52(18):5621-5626

A kinetic study was conducted on the effect of heat pretreatment in the temperature range of 50-85 degrees C at atmospheric pressure and of high hydrostatic pressure pretreatment (100-700 MPa) at four temperatures (10, 25, 40, and 60 degrees C) on the susceptibility of egg white solutions (10% v/v, pH 7.6) to subsequent enzymatic hydrolysis by a mixture of trypsin and alpha-chymotrypsin at 37 degrees C and pH 8.0. Both heat pretreatment at atmospheric pressure and high-pressure pretreatment resulted in an increase in degree of hydrolysis (DH) after 10 min of enzymatic reaction (DH10) of egg white solutions, as measured using the pH-stat method, which could be described by a fractional conversion model (based on an apparent first-order reaction kinetic model). The temperature dependence of the corresponding rate constants could be described by the Arrhenius equation. At elevated pressure, a negative apparent activation energy was obtained, implying an antagonistic effect of pressure and temperature. The pressure dependence of the rate constants could be described by the Eyring equation, and negative activation volumes were observed, which demonstrates the positive effect of pressure on the susceptibility of egg white solutions to subsequent enzymatic hydrolysis.  相似文献   

Effect of landscape structure on Common Vole (Microtus arvalis) distribution and abundance at several space scales     

P. Delattre  P. Giraudoux  J. Baudry  J. P. Quéré  E. Fichet 《Landscape Ecology》1996,11(5):279-288

This paper aims to answer the following question: are the fluctuations of abundance of Common Vole (Microtus arvalis) specific to different types of landscapes? The research was carried out in landscapes where grassland was dominant. The sampling method was based upon a partition in both landscape types and landscape units. Tracking of vole indices was used to evaluate their relative abundance. Six landscape transects were sampled during two successive years. Results show that population variation and diffusion of demographic states are closely related to landscape types. The possible causes of this are discussed. The landscape units can be used as global variables to assess outbreak risk and landscape design can be used to prevent them.  相似文献   

Structure of the membrane protein FhaC: a member of the Omp85-TpsB transporter superfamily     

Clantin B  Delattre AS  Rucktooa P  Saint N  Méli AC  Locht C  Jacob-Dubuisson F  Villeret V 《Science (New York, N.Y.)》2007,317(5840):957-961

In Gram-negative bacteria and eukaryotic organelles, beta-barrel proteins of the outer membrane protein 85-two-partner secretion B (Omp85-TpsB) superfamily are essential components of protein transport machineries. The TpsB transporter FhaC mediates the secretion of Bordetella pertussis filamentous hemagglutinin (FHA). We report the 3.15 A crystal structure of FhaC. The transporter comprises a 16-stranded beta barrel that is occluded by an N-terminal alpha helix and an extracellular loop and a periplasmic module composed of two aligned polypeptide-transport-associated (POTRA) domains. Functional data reveal that FHA binds to the POTRA 1 domain via its N-terminal domain and likely translocates the adhesin-repeated motifs in an extended hairpin conformation, with folding occurring at the cell surface. General features of the mechanism obtained here are likely to apply throughout the superfamily.  相似文献   

Landscape effects on the population dynamics of the fossorial form of the water vole (Arvicola terrestris sherman)     

Duhamel  Rémi  Quéré  Jean-Pierre  Delattre  Pierre  Giraudoux  Patrick 《Landscape Ecology》2000,15(2):89-98

The dynamics of microtine rodents show large variations among species and even among populations of a single species. Several studies have shown that landscape structure and predation play a role in these variations. We studied the influence of landscape structure on the spatial distribution and the population dynamics of the fossorial form of the water vole (Arvicola terrestris sherman). The sampling was based on a preliminary five-year survey of a rodent cycle on a regional scale, as well as a method of abundance estimation using surface indices. This survey led to distinguishing epicentres where outbreaks started, and diffusion sections where outbreaks occurred later. Results showed differences in dynamics of spatial distribution of the vole colonies between these two types of sections. This distribution pattern is related to landscape composition and structure. Epicentres are characterized by a higher ratio of open landscape, a lower ratio of forest, and less fragmentation when compared to the diffusion sections. Therefore landscape analysis has the potential of providing a valuable framework for the designing of programs for the early control of A. terrestris populations.  相似文献   

Inhaled fluticasone reduces bronchial responsiveness and airway inflammation in cats with mild chronic bronchitis   总被引：4，自引：0，他引：4  

Kirschvink N  Leemans J  Delvaux F  Snaps F  Jaspart S  Evrard B  Delattre L  Cambier C  Clercx C  Gustin P 《Journal of Feline Medicine and Surgery》2006,8(1):45-54

This study investigated the effect of inhaled fluticasone on lower airway inflammation and bronchial responsiveness (BR) to inhaled carbachol in cats with very mild, chronic bronchitis (n = 5) that were compared with healthy cats serving as controls (n = 6). Chest radiographs, BR tests performed non-invasively by barometric whole body plethysmography (BWBP) and bronchoalveolar lavage (BAL) were performed before and after treatment. BR was quantified by calculating the concentration of carbachol inducing bronchoconstriction (C-Penh300%), defined as a 300% increase of baseline Penh, an index of bronchoconstriction obtained by BWBP. BAL fluid was analyzed cytologically and the oxidant marker 8-iso-PGF2alpha was determined. At test 1, healthy cats and cats with bronchitis were untreated, whereas for test 2 inhalant fluticasone (250 microg once daily) was administrated for 2 consecutive weeks to cats with bronchitis. Control cats remained untreated. Inhaled fluticasone induced a significant increase in C-Penh300% and a significant decrease of BAL fluid total cells, macrophages, neutrophils and 8-iso-PGF2alpha in cats with bronchitis, whilst untreated control cats did not show significant changes over time. This study shows that a 2-week fluticasone treatment significantly reduced lower airway inflammation in very mild bronchitis. BR could be successfully monitored in cats using BWPB and decreased significantly in response to inhaled fluticasone. 8-Iso-PGF2alpha in BAL fluid was responsive to treatment and appeared as a sensitive biomarker of lower airway inflammation in cats.  相似文献