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1.
Rekiki A Sidi-Boumedine K Souriau A Jemli J Hammami S Rodolakis A 《Veterinary research》2002,33(2):215-222
Chlamydiosis is one of the major diseases that can lead to abortion in ewes. Since 1997, in 5 regions of Tunisia, Chlamydia-related abortions have been reported in 15 sheep and goat flocks. One hundred and sixty-six sera and 50 vaginal swab samples were collected from adult ewes. Chlamydial antigens were detected in 29 (58%) of the vaginal swabs using Enzyme Linked Immunosorbent Assay (ELISA) while 9 (18%) were positive by cell culture. Five strains were recovered from 4 different sheep flocks. Monoclonal antibody profiles and restriction fragment length polymorphism (RFLP) analysis of the 16S-23S rRNA spacer region showed that these isolates were C. abortus. Using amplified fragment length polymorphism (AFLP), these Tunisian strains were shown to exhibit the same pattern as strains isolated in France. 相似文献
2.
Véronique Chable Alain Rival Thierry Beulé Joseph Jahier Frédérique Eber Valérie Cadot François Boulineau Armel Salmon Henri Bellis Maria J. Manzanares-Dauleux 《Euphytica》2009,170(3):275-287
Aberrant phenotypes of cauliflower were detected throughout the cultivation period and in any variety type. The rate of these phenotypes in the field has recently increased. We reported previously on the first part of our results which showed that (1) the rate of aberrant plants varied with genotype and cultivation area, (2) the aberrant phenotypes can evolve or reverse to normality during the plant cycle and (3) the capacity to express a variant phenotype can be transmitted to the progeny. An epigenetic hypothesis has been proposed to explain the determinism of the phenomenon. Further investigation on the “aberrant” character focussed on the flow cytometric estimation of ploidy levels and on the parallel observation of meiosis. Only a fraction of aberrant plants did show aneuploidy and various ploïdy levels were found for the same phenotype. Indeed, aneuploidy could not be related to the aberrant phenotype although it could probably be a consequence of the aberration phenomenon. HPLC analysis of global DNA methylation rates showed that DNA hypermethylation occurred in plants which exhibited an evolution of their phenotype during vegetative cycle. The epigenetic origin of aberrant phenotypes in cauliflower is discussed with reference to epigenetic diseases described in human beings. 相似文献
3.
Jean-Paul Laclau Joseph Levillain Philippe Deleporte Jean de Dieu Nzila Jean-Pierre Bouillet Laurent Saint André Antoine Versini Louis Mareschal Yann Nouvellon Armel Thongo M’Bou Jacques Ranger 《Forest Ecology and Management》2010
Tropical plantation forests are meeting an increasing proportion of global wood demand and comprehensive studies assessing the impact of silvicultural practices on tree and soil functioning are required to achieve sustainable yields. The objectives of our study were: (1) to quantify the effects of contrasting organic residue (OR) retention methods on tree growth and soil nutrient pools over a full Eucalyptus rotation and (2) to assess the potential of soil analyses to predict yields of fast-growing plantations established on tropical sandy soils. An experiment was set up in the Congo at the harvesting of the first rotation after afforestation of a native herbaceous savanna. Six treatments were set up in 0.26 ha plots and replicated in 4 blocks, with OR mass at planting ranging from 0 to 46.5 Mg ha−1. Tree growth over the whole rotation was highly dependent on OR management at planting. Over-bark trunk volume 7 years after planting ranged from 96 m3 ha−1 in the treatment with forest floor and harvest residue removal at planting to 164 m3 ha−1 in the treatment with the largest amount of OR. A comparison of nutrient stocks within the ecosystem at planting and at the end of the rotation suggested that nutrient contents in OR were largely involved in the different response observed between treatments. OR management treatments did not significantly modify most of the nutrient concentrations in the upper layers of the mineral soil. Conventional soil analyses performed before planting and at ages 1 and 3 years were unable to detect differences between treatments despite large differences in tree growth. In contrast, linear regressions between stand aboveground biomass at harvesting and OR mass at planting (independent variable) showed that OR mass was an excellent predictor of stand yield (R2 = 0.99). A large share of soil fertility comes from organic material above the mineral soil in highly weathered sandy soils and OR mass at planting might be used in conjunction with soil analyses to assess the potential of these soils to support forest plantations. 相似文献
4.
Berri M Souriau A Crosby M Crochet D Lechopier P Rodolakis A 《The Veterinary record》2001,148(16):502-505
Two abortions associated with Coxiella burnetii occurred in a group of 34 pregnant ewes. The seroprevalence of C. burnetii infection was studied by using an ELISA and the immunofluorescence (IF) assay was applied to the contents of vaginal swabs. In addition, a PCR assay, with primers based on a transposon-like repetitive region of the C. burnetii genome (trans-PcR), was used for the highly sensitive and specific detection of C. burnetii in vaginal swabs, milk and faeces. Of the 34 animals tested at parturition, eight (24 per cent) were positive by ELISA, 11 (32 per cent) were positive by IF, and 15 (44 per cent) were positive when the vaginal swab extract was subjected to the trans-PCR assay. C. burnetii was therefore detected by PCR in the vaginal swabs of seven seronegative ewes. However, five weeks after lambing, 16 (47 per cent) of the animals tested were ELISA positive but only two animals (6 per cent) were positive by PCR. Among the ELISA- and PCR-positive animals, eight (25 per cent) shed coxiella in their milk and six (18 per cent) did so in their faeces. 相似文献
5.
Jean-Paul Laclau Jacques Ranger José Leonardo de Moraes Gonçalves Valérie Maquère Alex V. Krusche Armel Thongo M’Bou Yann Nouvellon Laurent Saint-André Jean-Pierre Bouillet Marisa de Cassia Piccolo Philippe Deleporte 《Forest Ecology and Management》2010,259(9):1771-1785
The sustainability of fast-growing tropical Eucalyptus plantations is of concern in a context of rising fertilizer costs, since large amounts of nutrients are removed with biomass every 6–7 years from highly weathered soils. A better understanding of the dynamics of tree requirements is required to match fertilization regimes to the availability of each nutrient in the soil. The nutrition of Eucalyptus plantations has been intensively investigated and many studies have focused on specific fluxes in the biogeochemical cycles of nutrients. However, studies dealing with complete cycles are scarce for the Tropics. The objective of this paper was to compare these cycles for Eucalyptus plantations in Congo and Brazil, with contrasting climates, soil properties, and management practices.The main features were similar in the two situations. Most nutrient fluxes were driven by crown establishment the two first years after planting and total biomass production thereafter. These forests were characterized by huge nutrient requirements: 155, 10, 52, 55 and 23 kg ha?1 of N, P, K, Ca and Mg the first year after planting at the Brazilian study site, respectively. High growth rates the first months after planting were essential to take advantage of the large amounts of nutrients released into the soil solutions by organic matter mineralization after harvesting. This study highlighted the predominant role of biological and biochemical cycles over the geochemical cycle of nutrients in tropical Eucalyptus plantations and indicated the prime importance of carefully managing organic matter in these soils. Limited nutrient losses through deep drainage after clear-cutting in the sandy soils of the two study sites showed the remarkable efficiency of Eucalyptus trees in keeping limited nutrient pools within the ecosystem, even after major disturbances. Nutrient input–output budgets suggested that Eucalyptus plantations take advantage of soil fertility inherited from previous land uses and that long-term sustainability will require an increase in the inputs of certain nutrients. 相似文献
6.
Primers targeting the conserved pmp gene family of Chlamydophila abortus were evaluated for their ability to improve the polymerase chain reaction (PCR) sensitivity. In purified DNA, specific pmp primers (named CpsiA and CpsiB) allowed at least a 10-fold increase of the PCR sensitivity compared to the specific ompA primers for C. abortus, but also for C. psittaci and C. caviae strains. No amplification was observed on C. felis, C. pecorum, C. pneumoniae and Chlamydia trachomatis strains. Tested on contaminated specimens such as genital swabs, the PCR sensitivity observed with CpsiA/CpsiB was also better than with the ompA primers. This study demonstrated that these specific pmp primers could serve as valuable, sensitive and common tools for a specific Chlamydophila diagnosis in ruminant, avian and human diseases. Digestion by AluI of the CpsiA/CpsiB fragments allowed a specific discrimination of the strains in function of their hosts and/or their serotypes. 相似文献
7.
Response of goats to vaccination with temperature-sensitive mutants of Chlamydia psittaci obtained by nitrosoguanidine mutagenesis 总被引：1，自引：0，他引：1
Two temperature-sensitive strains of ovine Chlamydia psittaci, 1B and 1H, obtained by mutagenesis were used as live-organism vaccines; 31 goats were given 4 X 10(6) plaque-forming units (PFU) of strain 1B, and 31 were given 5 X 10(6) PFU of strain 1H 2 months before they were bred. The consequences of the vaccination of the goats were studied during pregnancy by recording complement-fixation antibody titer, chlamydial excretion, and kidding performances and were compared with those of goats inoculated under the same conditions with 100 X smaller dose of virulent caprine abortive strain AC1. The vaccination did not disturb pregnancy, and none of the vaccinated goats excreted chlamydiae. In contrast, 2 of 28 goats inoculated with AC1 aborted and shed chlamydiae. One year after the goats were vaccinated, they were challenge exposed by intradermal inoculation of 10(6) PFU of the caprine strain AC1 at 79 to 98 days of pregnancy. Although 13 of the 14 control nonvaccinated goats aborted and excreted chlamydiae, none of the pregnant goats vaccinated with 1H and only 1 of the pregnant goats vaccinated with 1B aborted and excreted chlamydiae. 相似文献
8.
Véronique Chable Alain Rival Valérie Cadot François Boulineau Armel Salmon Henri Bellis Maria J. Manzanares-Dauleux 《Euphytica》2008,164(2):325-337
For more than a decade, the number of “aberrant plants” showing various developmental abnormalities in cultivated cauliflowers
has dramatically increased, thus hampering the registration of new varieties in some cases. The aberrant phenotype occurred
during the cultivation period and in any variety type (pure line or F1 hybrid). The number of aberrant plants increased considerably
from 1994 onwards. The rate of aberrant plants observed among F1 hybrids in the field was found to vary according to genotype
and cultivation area. Besides morphological changes, aberrant phenotypes showed various patterns of evolution, i.e. stable,
evolving toward another phenotype or reversing toward normality. Vegetative and seed progenies were obtained in order to investigate
the genetic control of these phenotypic variations. Given that the aberrant phenotypes can evolve towards either normality
or another abnormality during the life cycle of the plant and that the aberration capacity and/or the “acquired morphological
disorder” can be transmitted to the progeny, an epigenetic hypothesis has been proposed for the determinism of this phenomenon. 相似文献
9.
Patrick A. Jones Dean A. Kopsell Gregory R. Armel Gregory K. Breeden 《Journal of plant nutrition》2015,38(2):177-188
Preemergence (PRE) herbicides negatively impacting turfgrass root growth may compromise macro- and micronutrient accumulation in foliar tissue. Research was conducted to determine the effects of indaziflam (35 and 52.5 g ha?1), prodiamine (0.84 kg ha?1), oxadiazon (3.36 kg ha?1), and isoxaben (1.12 kg ha?1) applications in hydroponic culture on hybrid bermudagrass [C. dactylon (L.) Pers. x C. transvaalensis Burtt-Davy] tissue nutrient content. Prodiamine, indaziflam, and isoxaben reduced visual root mass relative to non-treated plants. Consequently, these herbicides reduced phosphorus (P), sulfur (S), and potassium (K) content in turf foliar tissue. Treatment with indaziflam reduced magnesium (Mg) and manganese (Mn) content in turf foliar tissue compared to non-treated plants. This response was not observed with prodiamine and could explain the significant foliar injury (>70%) observed with both rates of indaziflam. Data in the current study illustrate that PRE herbicide applications affect hybrid bermudagrass nutrient content. Future studies should evaluate foliar applications of Mg and Mn for either preventing or remediating leaf tissue injury following PRE herbicide application. 相似文献
10.
An enzyme linked immunosorbent assay (ELISA) for the detection of Chlamydia psittaci in vaginal swabs of aborted ewes and goats has been developed using microtiter plates coated with sheep anti-Chlamydia immunoglobulin G. This technique was compared to the direct isolation of the agent by plaque assay on McCoy cells. Among 89 specimens from animals in infected flocks, 58 were positive by both methods, seven were only positive by ELISA, and nine others were only positive by direct isolation (plaque assay). None of the 75 specimens from animals in healthy flocks gave a positive response in ELISA or the plaque assay. Unlike direct isolation in cell culture, the ELISA technique permitted the detection of Chlamydia even in the absence of special care in sampling and conservation of specimens. 相似文献