Biological effects of native and exotic plant residues on plant growth, microbial biomass and N availability under controlled conditions     

M.D. Diallo  R. Duponnois  A. Guisse  S. Sall  J.-L. Chotte  J. Thioulouse 《European Journal of Soil Biology》2006,42(4):238-246

The leaf litter of six tropical tree species (Acacia holosericea, Acacia tortilis, Azadirachta indica, Casuarina equisetifolia, Cordyla pinnata and Faidherbia albida) frequently used in agroforestry plantations in Sahelian and Soudano-Sahelian areas were tested for their influence on soil nitrogen content, microbial biomass and plant growth under controlled greenhouse conditions. Half of the soil was planted with onion (Allium cepa L.) seedlings and the other half was not. Two herbaceous species, Andropogon gayanus and Eragrostis tremula, were also studied. Co-inertia analysis (CIA) and one-way analysis of variance (ANOVA) analysis showed that C. pinnata and F. albida leaf powder amendment induced the highest plant growth, whereas leaf powder of E. tremula is associated to higher microbial biomass and NH₄⁺ content. Higher onion seedlings growth is associated with higher concentration of nitrogen and lignin in leaf powders. Conversely, lower plant growth is associated to higher rates of cellulose, hemicellulose and phenols in leaves. Higher rates of cellulose and hemicellulose are associated with higher microbial biomass and NH₄⁺, whereas phenols are associated to lower microbial biomass. The results showed that amendment of A. holosericea leaf powder (high concentrations of phenol) to the soil resulted in a lower microbial biomass and lower onion seedlings growth. Data showed that the plant residue quality index (PRQI) could be a useful tool to predict the effects of litter materials on root growth in glasshouse conditions. The highest values on soil and plant parameters were recorded with C. pinnata litter. While powdered leaf material increased the accessibility of substrates to microbes, more research with C. pinnata leaf litter (under a wider range of ecological conditions) is needed. It could add deeper on its agronomic impact in the tropics.  相似文献   

Assessment of strawberry aroma through SPME/GC and ANN methods. Classification and discrimination of varieties   总被引：2，自引：0，他引：2  

Urruty L  Giraudel JL  Lek S  Roudeillac P  Montury M 《Journal of agricultural and food chemistry》2002,50(11):3129-3136

To provide an efficient and running analytical tool to strawberry plant breeders who have to characterize and compare the aromatic properties of new cultivars to those already known, a HS-SPME/GC-MS analysis method has been coupled with a statistical treatment method issued from the current development of artificial neuron networks (ANN), and more specifically, the unsupervised learning systems called Kohonen self-organizing maps (SOMs). So, 70 strawberry samples harvested at CIREF from 17 known varieties have been extracted by using a DVB/Carboxen/PDMS SPME fiber according to the headspace procedure, and then chromatographed. A panel of 23 characteristic aromatic constituents has been selected according to published results relative to strawberry aroma. The complex resulting matrix, collecting the relative abundance of the 23 selected constituents for each sample, has been input into the SOM software adapted and optimized from the Kohonen approach described by one of the authors. After a period of training, the self-organized system affords a map of virtual strawberries to which real samples are compared and plotted in the best matching unit (BMU) of the map. The efficiency for discriminating the real samples according to their variety is dependent on the number of units selected to define the map. In this case, a 24-unit map allowed the complete discrimination of the 17 selected varieties. Moreover, to test the validity of this approach, two additional samples were blind-analyzed and the results were computed according to the same procedure. At the end of this treatment, both samples were plotted into the same unit as those of the same variety used for training the map.  相似文献   

Investigation of Nitrification and Denitrification in the Sediment of Wastewater Stabilization Ponds     

Chema Keffala  Marcello Galleguillos  Ahmed Ghrabi  Jean-Luc Vasel 《Water, air, and soil pollution》2011,219(1-4):389-399

Kinetic studies of nitrification and denitrification were carried out on reconstituted cores of sediments taken from wastewater stabilization ponds. This study aims to quantify the nitrification and denitrification in the sediment and to offer kinetic models to describe the processes. Sediment cores were collected, and laboratory studies were performed. The result showed that nitrification and denitrification processes are absent in the water column of stabilization ponds of the Bertrix (Belgium) wastewater treatment plant. On the contrary, nitrification and denitrification rates measured on 18 cores of sediment are, respectively, in the range of 0.12?C1.56 g N-NH ₄ ⁺ /m² day and 0.1?C1.2 g N/m² day. In order to describe nitrification and denitrification processes, two kinetic models were developed using the Monod standard equation.  相似文献   

Computed tomography or rhinoscopy as the first-line procedure for suspected nasal tumor: A pilot study     

Marlène Finck  Frédérique Ponce  Laurent Guilbaud  Cindy Chervier  Franck Floch  Jean-Luc Cadoré  Thomas Chuzel  Marine Hugonnard 《The Canadian veterinary journal. La revue veterinaire canadienne》2015,56(2):185-192

There are no evidence-based guidelines as to whether computed tomography (CT) or endoscopy should be selected as the first-line procedure when a nasal tumor is suspected in a dog or a cat and only one examination can be performed. Computed tomography and rhinoscopic features of 17 dogs and 5 cats with a histopathologically or cytologically confirmed nasal tumor were retrospectively reviewed. The level of suspicion for nasal neoplasia after CT and/or rhinoscopy was compared to the definitive diagnosis. Twelve animals underwent CT, 14 underwent rhinoscopy, and 4 both examinations. Of the 12 CT examinations performed, 11 (92%) resulted in the conclusion that a nasal tumor was the most likely diagnosis compared with 9/14 (64%) for rhinoscopies. Computed tomography appeared to be more reliable than rhinoscopy for detecting nasal tumors and should therefore be considered as the first-line procedure.  相似文献   

Direct detection of the Yarkovsky effect by radar ranging to asteroid 6489 Golevka     

Chesley SR  Ostro SJ  Vokrouhlicky D  Capek D  Giorgini JD  Nolan MC  Margot JL  Hine AA  Benner LA  Chamberlin AB 《Science (New York, N.Y.)》2003,302(5651):1739-1742

Radar ranging from Arecibo, Puerto Rico, to the 0.5-kilometer near-Earth asteroid 6489 Golevka unambiguously reveals a small nongravitational acceleration caused by the anisotropic thermal emission of absorbed sunlight. The magnitude of this perturbation, known as the Yarkovsky effect, is a function of the asteroid's mass and surface thermal characteristics. Direct detection of the Yarkovsky effect on asteroids will help constrain their physical properties, such as bulk density, and refine their orbital paths. Based on the strength of the detected perturbation, we estimate the bulk density of Golevka to be 2.7(+0.4)(-0.6) grams per cubic centimeter.  相似文献   

New developments in the estimation of spores of Pasteuria penetrans     

Kounbobr Roch Dabiré  Jean-Luc Chotte  Joel Fardoux  Thierry Mateille 《Biology and Fertility of Soils》2001,33(4):340-343

New developments in the estimation of free spores of Pasteuria penetrans, a hyperparasite of plant-parasitic nematodes, including Meloidogyne spp., have been tested in contrasted textured soils. They were dedicated to improving the recovery of spores. Different methods of increasing energy of aggregate dispersion were compared in their efficiency in recovering spores inoculated in a sandy clay soil and a clay soil. The dispersion of the soils by the less energetic method (method A) allowed only 50% and 20% of the spore inoculum to be recovered from the sandy clay soil and clay soil, respectively. For these soils, 76% and 81% of the particle-size fraction (0-20 µm) isolated by this method were still aggregated in coarser structures. With increasing energy (methods B and C), these coarse aggregates disappeared entirely in both soils. At the same time, the recovery of spores increased sharply, representing about 87% and 75% of the inoculum of the sandy clay soil and clay soil, respectively. Therefore, at most 25% of the pool of spores remained undetectable. The formation of artificial aggregates during the enumeration procedure could not be advocated to explain this result, since the dispersion of the fraction collected for the enumeration did not improve spore recovery.  相似文献   

Emergence of a new lagovirus related to Rabbit Haemorrhagic Disease Virus     

Ghislaine Le Gall-Reculé  Antonio Lavazza  Stéphane Marchandeau  Stéphane Bertagnoli  Fran?oise Zwingelstein  Patrizia Cavadini  Nicola Martinelli  Guerino Lombardi  Jean-Luc Guérin  Evelyne Lemaitre  Anouk Decors  Samuel Boucher  Bernadette Le Normand  Lorenzo Capucci 《Veterinary research》2013,44(1):81

Since summer 2010, numerous cases of Rabbit Haemorrhagic Disease (RHD) have been reported in north-western France both in rabbitries, affecting RHD-vaccinated rabbits, and in wild populations. We demonstrate that the aetiological agent was a lagovirus phylogenetically distinct from other lagoviruses and which presents a unique antigenic profile. Experimental results show that the disease differs from RHD in terms of disease duration, mortality rates, higher occurrence of subacute/chronic forms and that partial cross-protection occurs between RHDV and the new RHDV variant, designated RHDV2. These data support the hypothesis that RHDV2 is a new member of the Lagovirus genus. A molecular epidemiology study detected RHDV2 in France a few months before the first recorded cases and revealed that one year after its discovery it had spread throughout the country and had almost replaced RHDV strains. RHDV2 was detected in continental Italy in June 2011, then four months later in Sardinia.  相似文献   

Characterization of European Plasmopara viticola isolates with reduced sensitivity to cymoxanil     

Jean-Luc Genet  Grazyna Jaworska 《European journal of plant pathology / European Foundation for Plant Pathology》2013,135(2):383-393

Cymoxanil has been used for over 30 years to control grape downy mildew (Plasmopara viticola) in European vineyards, prevalently in mixture with other fungicides active on this disease. In the 1990’s cases of P. viticola resistant to cymoxanil were detected using a leaf disc assay. In this study, we establish that the presence of only 1 % of resistant isolates in a P. viticola population will allow the detection of cymoxanil resistance in the leaf disc assay. A poor correlation (R?=?0.194) was observed between the leaf disc assay and a whole- plant test for 38 P. viticola field populations collected in 2004. Over 60 % of these populations were characterized as fully sensitive in a whole-plant assay compared to 10 % in the leaf disc assay. Five P. viticola field isolates resistant to cymoxanil reverted to full sensitivity after six to nine transfers to untreated vines, indicating that cymoxanil resistance in P. viticola is unstable. Two European P. viticola populations sensitive to cymoxanil became resistant when transferred 12–14 times on vines treated with cymoxanil. In contrast, two populations originating from the USA and three monozoospore isolates from France retained full sensitivity to the fungicide after 13 cycles on cymoxanil-treated plants. Whole-plant experiments were conducted in the laboratory to compare the efficiency of spray programs to delay the development of cymoxanil resistance. Whereas the continuous use of cymoxanil alone quickly selected for resistance, the mixture of cymoxanil and folpet applied either continuously or in strict or block alternation effectively prevented the development of resistance over 10 generations of the fungus. These results demonstrate that resistance to cymoxanil in P. viticola can be managed with appropriate spray programs.  相似文献   

Biological activities of purified marennine, the blue pigment responsible for the greening of oysters     

Gastineau R  Pouvreau JB  Hellio C  Morançais M  Fleurence J  Gaudin P  Bourgougnon N  Mouget JL 《Journal of agricultural and food chemistry》2012,60(14):3599-3605

Marennine, the blue pigment produced by the diatom Haslea ostrearia , exists in two different forms, the intra- and extracellular forms. We investigated the antibacterial, antiviral, and antiproliferative properties of both of these forms. Both forms of marennine inhibited the development of marine bacteria, in particular the pathogenic organism Vibrio aesturianus , at concentrations as low as 1 μg/mL, but they did not display any effect on a wide range of pathogenic bacteria that are relevant for food safety. Both forms of the pigment produced by H. ostrearia also exhibited antiviral activity against the HSV1 herpes virus, with intra- and extracellular marennine having EC(50) values of 24.0 and 27.0 μg/mL, respectively. These values are 2 orders of magnitude higher than the value for the reference drug, Zovirax. Moreover, both forms of marennine were effective in slowing or inhibiting the proliferation of cancer cells. This study confirms the potential of marennine as a biologically active organic molecule, which could have a protective effect on bivalves, which filter seawater and fix the pigment on their gills. Moreover, marennine could be used in food engineering and chemistry as a natural blue pigment. However, despite that it is eaten and possibly assimilated by green oyster consumers, it also deserves in depth evaluation before being considered for use as a nutraceutical.  相似文献   

QTL × genetic background interaction: predicting inbred progeny value     

Jean-Luc Jannink 《Euphytica》2008,161(1-2):61-69

Failures of the additive infinitesimal model continue to provide incentive to study other modes of gene action, in particular, epistasis. Epistasis can be modeled as a QTL by genetic background interaction. Association mapping models lend themselves to fitting such an interaction because they often include both main marker and genetic background factors. In this study, I review a model that fits the QTL by background interaction as an added random effect in the now standard mixed model framework of association analyses. The model is applied to four-generation pedigrees where the objective is to predict the genotypic values of fourth-generation individuals that have not been phenotyped. In particular, I look at how well epistatic effects are estimated under two levels of inbreeding. Interaction detection power was 8% and 65% for pedigrees of 240 randomly mated individuals when the interaction generated 6% and 20% of the phenotypic variance, respectively. Power increased to 21% and 94% for these conditions when evaluated individuals were inbred by selfing four times. The interaction variance was estimated in an unbiased way under both levels of inbreeding, but its mean squared error was reduced by 40% to 70% when estimated in inbred relative to randomly mated individuals. The performance of the epistatic model was also enhanced relative to the additive model by inbreeding. These results are promising for the application of the model to typically self-pollinating crops such as wheat and soybean. The U.S. Government's right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged.  相似文献