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1.
Résumé. Des plantules de mais sont cultivées à partir de la graine, à 1'obscurite ct i la lumiere, sur des solutions tamponnées (pH5,8) d'hydrazidemalfrque (HM) de concentrations allant de 10' a 10−3 M. AUX faibles concentrations (10° et 10−6 M), I'HM stimule la croissance et la formation des racines; aux autres concentrations, it est inhibiteur. L'inhibition de croissance provoquee par I'HM est accompagnee d'une augmentation de poids sec et de la teneur en anthocyanes.
L'HM n'influence pas in vitro la destruction de I'auxine par des extraits de mais, mais les extraits de plantes traitees par cette substance degradent l'hormone moins rapidement; parallelement, l'activite catalasique est diminuee mais l'activite péroxydasique est augmented. Le mode d'action de I'HM sur la croissanee et la rhizogenpse, compart à celui de la lumierc, est discute en rapport avec ses effets sur le raetabolisme auxinique. 相似文献
L'HM n'influence pas in vitro la destruction de I'auxine par des extraits de mais, mais les extraits de plantes traitees par cette substance degradent l'hormone moins rapidement; parallelement, l'activite catalasique est diminuee mais l'activite péroxydasique est augmented. Le mode d'action de I'HM sur la croissanee et la rhizogenpse, compart à celui de la lumierc, est discute en rapport avec ses effets sur le raetabolisme auxinique. 相似文献
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Pot and field experiments were performed in Burkina Faso in 1987 and 1988 to evaluate the resistance of selected ‘low-stimulant’ sorghum (Sorghum bicolor (L.) Moench) varieties to the parasitic weed (Striga hermonthica (Del.) Benth. In a pot experiment, the variety IS-7777 supported the lowest number and had the latest emergence of Striga, compared with the other varieties tested. The varieties IS-14825, IS-6961, IS-7739, IS-14928 and IS-14975 also had signifi cantly lower numbers of emerged Striga per pot than the resistant control Framida. The resist ance of IS-7777 was confirmed in field experi ments, as was that of IS-7739, IS-6961 and IS-14928. However, the yield potential of these poorly adapted varieties was low in Striga-infested fields. The varieties IS-14975, IS–14825 and Seguetana Niarabougou exhibited a low susceptibility associated with a grain yield equivalent to that of the other varieties in farm fields infested by Striga. As Seguetana is already grown by Sahelian farmers, its use could be recommended in the absence of resistant varieties adapted to Sahelian agroclimatic conditions. The exceptionally high level of restance exhibited by IS-7777 could be exploited in studies on the genetics and mechanisms of resistance of the host plant to the parasite, as well as in sorghum improvement programmes. 相似文献
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Immunogenicity of vaccines from a virulent and an a virulent strain of Aeromonas salmonicida 总被引：1，自引：0，他引：1
Abstract. Injected vaccines consisting of formalin-killed cells and extracellular antigens prepared from a virulent and an avirulent strain of Aeromonas salmonicida were tested for their efficacy in protecting juvenile coho salmon. Oncorhychus kisutch (Walbaum). Against experimental furunculosis following active and passive immunization. Sera used in the passive immunization experiments were raised in subadult coho salmon and in rabbits. Results indicated that the avirulent strain was inferior to the virulent strain in its immunogenicity for coho salmon. Thus, even though avirulent cells possessed at least one immunogen–an immunogen that was show in passive immunization experiments to be well recognized by rabbits–the immunogen was only inefficiently protection when vaccinated with avirulent cells. Furher, extracellular antigens of the avirulent strain were not protective for coho salmon even though they elicited the production of anti- A. salmonicida agglutinins. In contrast, the killed cells and extracellular antigens of the virulent strain were both immunogenic in coho salmon. By passively immunizing coho salmon with rabbit sera raised against the virulent and the virulent strain produced at least two immunogens, only one of which was shared in common with the avirulent strain. The extra immunogen possessed by the virulent strain is presumably responsible for its superior immunogenicity in coho salmon; the immunogen had the properties of a protein and is believed to be the A-protein. 相似文献
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Aucune lutte chimique n'est actuellement utilisable contre la plus grave maladie du champignon de couche, causée par Pseudomonas tolaasii. La lutte biologique avec ?antagoniste P. fluorescens a reduit les pertes de 30 à 60%, mais dans la pratique ce résultat est insuffisant et exige une amélioration; parmi les différentes voies possibles, nous avons retenu ?utilisation de bactériophages. Plusieurs phages ont été purifyés à partir de carpophores malades. Leur sélectivité vis-à-vis de différentes bactéries pathogènes ou saprophytes isolées de plusieurs écosystèmes a étéétudiée. Nous avons retenu les phages fortement agressifs pour P. tolaasii et tempérés pour la souche de P. fluorescens utilisée en lutte biologique. On a done conçu un système ?apport de phages par traitement des cultures avec un mélange de ?antagoniste P. fluorescens et des phages. Au cours de premiers essais, ?addition des effets de ?antagoniste et des phages lytiques a permis de réduire significativement les pertes en culture (>80%), mais plusieurs paramètres restent à préciser avant une utilisation à plus grande échelle. Ce travail amène aussi à s'interroger sur le rôle des bactériophages dans la dynamique des populations naturelles des Pseudomonas spp., utiles ou nuisibles pour les champignons. 相似文献
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The principal effect of x-irradiated Schistosoma mansoni cercariae may be to slow the migration and development of the worms of a challenge infection. This would account for the smaller number of worms found in the portal system in the early weeks and the delayed accumulation of recoverable worms and eggs. 相似文献
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OLIVIER TAEYMANS SYLVIE DAMINET LUC DUCHATEAU JIMMY H. SAUNDERS 《Veterinary radiology & ultrasound》2007,48(3):262-269
Primary hypothyroidism is a frequent endocrine disorder in the adult dog. However, false-positive diagnoses are common because of the relatively low accuracy of most commonly used biochemical tests. The purpose of this study was to describe the ultrasonographic features of the thyroid gland in hypothyroid dogs, to calculate the diagnostic sensitivity of gray-scale ultrasound using a combination of clinical symptoms and biochemical thyroid tests as gold standard, and to investigate the evolution of the ultrasonographic features after treatment of hypothyroidism. Eighteen dogs were studied prospectively. All dogs underwent an ultrasound examination at first presentation and 13 underwent one or two additional ultrasound examinations over time. At first presentation, a sensitivity of 76.5% (95% CI [50.0-93.0% 1) for decreased echogenicity, 64.7% (95% CI [38.385.8% 1) for inhomogeneity, 70.6% (95% CI 144.0-89.7%]) for irregular capsule delineation, 64.7% (95% CI [38.3-85.8%]) for abnormal lobe shape and 47.1% (95% CI 123.0-72.2%]) for decreased relative thyroid volume was obtained. Combining these five parameters together resulted in an overall sensitivity of 94.1% (95% CI [71.3-99.9%]) for gray-scale ultrasound in the detection of acquired hypothyroidism at first presentation. A continuous decrease of thyroid volume was seen over time after treatment, while the other investigated parameters did not change significantly during the follow-up period. None of the thyroid glands were considered normal at the last presentation. Grayscale ultrasound is a sensitive and quick test for the diagnosis of primary hypothyroidism in dogs. 相似文献
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Abstract. Western blot (WB) and electroimmunotransfer blot (EITB) methods were used to monitor bacterial soluble antigens and scroconversion profiles, respectively, in Atlantic salmon, Salmo salar L., experimentally challenged with Renibacterium salmoninarum. The two challenged populations exhibited differences in susceptibility to R. salmoninarum permitting an evaluation of the methods in fish populations harbouring different levels of the pathogen, WB detection of R. salmoninarum soluble antigens in serum provided a sensitive method for detecting pathogen presence during the active infection stages. For comparison, results for drop-plate culture and direct fluorescent antibody techniques were obtained. During the recovery phase, surviving fish were negative for the pathogen by these methods. However, >90% of challenged fish sampled from early infection stages to the end of the experimental period (141 days post-infection) were scropositive by the EITB assay for Atlantic salmon immunoglobulin reactive with R. salmoninarum soluble antigens. The results suggest that these methods for detecting R. salmoninarum or its soluble antigens may be useful during active infections. However, asymptomatic fish populations exposed to the pathogen, perhaps having recovered from an active infection and representing potential disease carrier sources, may be more readily identified by antigen-specific antibodies using methods such as the EITB assay. 相似文献
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Evaluation of the Sensitivity and Specificity of Diagnostic Criteria for Sepsis in Dogs 总被引：2，自引：0，他引：2
J. G. HAUPTMAN DVM MS Diplomate ACVS R. WALSHAW BVMS Diplomate ACVS N. B. OLIVIER DVM PhD Diplomate ACVIM 《Veterinary surgery : VS》1997,26(5):393-397
Objective— To evaluate the ability of various individual criteria and grouped criteria to diagnose sepsis in dogs.
Study Design— Prospective acquisition of clinical data.
Animals or Sample Population— Client-owned dogs; 30 septic and 320 nonseptic.
Methods— Rectal temperature, heart rate, respiratory rate, white blood cell (WBC) count with percent bands, platelet count, and serum glucose concentration were obtained on day 0. True sepsis was determined on days 0 to 3 according to the following criteria: (1) histological, microbiological, and/or gross confirmation of infection, and (2) systemic illness caused by infection. Data were analyzed by the Mann-Whitney U test and multiple logistic regression. Sensitivity and specificity were calculated.
Results— The mean temperature, heart rate, WBC count, and percent bands were greater, whereas the mean platelet count was less in septic compared with nonseptic dogs. There was no difference in respiratory rate or glucose concentration. WBC/bands were the best individual criterion for the diagnosis of sepsis (sensitivity 87%; specificity 69%). The sensitivity and specificity of the grouped criteria (two of four; temperature, heart rate, respiratory rate, WBC) varied according to ranges of normal used. Muliple logistic regression resulted in little improvement in the sensitivity/specificity of these diagnostic criteria for the diagnosis of sepsis.
Conclusions— These criteria are useful for the diagnosis of sepsis when limits are used that result in a high sensitivity (eg, 97%). The high sensitivity was associated with a low false-negative and a high false-positive rate; sepsis was overdiagnosed with these grouped criteria.
Clinical Relevance— These criteria may be used for a sensitive, but nonspecific, diagnosis of sepsis in dogs. 相似文献
Study Design— Prospective acquisition of clinical data.
Animals or Sample Population— Client-owned dogs; 30 septic and 320 nonseptic.
Methods— Rectal temperature, heart rate, respiratory rate, white blood cell (WBC) count with percent bands, platelet count, and serum glucose concentration were obtained on day 0. True sepsis was determined on days 0 to 3 according to the following criteria: (1) histological, microbiological, and/or gross confirmation of infection, and (2) systemic illness caused by infection. Data were analyzed by the Mann-Whitney U test and multiple logistic regression. Sensitivity and specificity were calculated.
Results— The mean temperature, heart rate, WBC count, and percent bands were greater, whereas the mean platelet count was less in septic compared with nonseptic dogs. There was no difference in respiratory rate or glucose concentration. WBC/bands were the best individual criterion for the diagnosis of sepsis (sensitivity 87%; specificity 69%). The sensitivity and specificity of the grouped criteria (two of four; temperature, heart rate, respiratory rate, WBC) varied according to ranges of normal used. Muliple logistic regression resulted in little improvement in the sensitivity/specificity of these diagnostic criteria for the diagnosis of sepsis.
Conclusions— These criteria are useful for the diagnosis of sepsis when limits are used that result in a high sensitivity (eg, 97%). The high sensitivity was associated with a low false-negative and a high false-positive rate; sepsis was overdiagnosed with these grouped criteria.
Clinical Relevance— These criteria may be used for a sensitive, but nonspecific, diagnosis of sepsis in dogs. 相似文献