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951.
Antoine MESS AN Lo c VIGUIER Lise PARESYS Jean-No l AUBERTOT Stefano CANALI Pietro IANNETTA Eric JUSTES Alison KARLEY Beatrix KEILLOR Laura KEMPER Fr d ric MUEL Barbara PANCINO Didier STILMANT Christine WATSON Helga WILLER Ra l ZORNOZA 《农业科学与工程前沿(英文版)》2021,8(3):474-480
952.
Seminal roots of wheat and barley seedlings were inoculated with G. graminis var tritici on regions 0, 5- and 15-days old, and assessed for intensity and extent of infection after standard times. Wheat roots were most heavily infected on young regions, whereas barley roots were most heavily infected on old ones. The effect of root age in wheat was similar in both unsterile and aseptic conditions, so it could not be ascribed to saprophytic rhizosphere micro-organisms interacting with G. graminis.The contrasting results for wheat and barley are explained by a single hypothesis, based on decreasing host-resistance in the root cortex but increasing resistance at or near the endodermis as the roots age. It is suggested that, under some conditions, even small amounts of non-pathogenic root cortex death can enhance infection by G. graiminis. This interpretation may explain several aspects of take-all and its biological control by other dark mycelial parasites. 相似文献
953.
Dora Zouiten Ines Ben Khemis Ahmed Slaheddin Masmoudi Christine Huelvan Chantal Cahu 《Aquaculture Research》2011,42(11):1723-1736
The quality of development in intensive or mesocosm hatchery‐reared Dicentrarchus labrax larvae was investigated using physiological indicators assessing ontogeny. Larvae were reared in intensive (120 L tanks) and in mesocosm systems (20 m3 enclosures) with the same feeding sequence, excluding the wild zooplankton naturally available in mesocosms. Faster growth was recorded since early development [16 day after hatching (DAH)] in the mesocosm. Maturation of the digestive system also occurred earlier as indicated by the higher amylase secretion ratios, the intestinal maturation index (alkaline phosphatase/leucine–alanine peptidase and aminopeptidase‐N/leucine–alanine peptidase ratios) and the more developed intestinal epithelium at 23 DAH. Nevertheless, the delay in digestive maturation in the intensive system seemed retrieved within few days. In both the groups, the number of vertebrae ranged between 24 and 26, with the dominant class being 25 vertebrae. However, the distributions differed between treatments for meristic characteristics, ossification stages and incidence of malformation types. Loss of a vertebra was more frequent in the intensive system, while the appearance of an additional vertebra was more frequent in the mesocosm. Ossification at 37 DAH was also more advanced in the mesocosm in addition to a lesser rate and severity of skeletal malformations. It is suggested that the early nutritional contribution of mesocosm wild zooplankton, yet at densities of 0.2–0.7 prey mL?1, had key effects on larvae development since the early stages. 相似文献
954.
Britt Bang Jensen Stian Nylund Julie Christine Svendsen Paul‐Martin R. Ski Harald Takle 《Journal of fish diseases》2019,42(6):825-833
Losses due to cardiomyopathy syndrome (CMS) keep increasing in salmon‐producing countries in the North‐Atlantic. Recently, Piscine myocarditis virus (PMCV) has been detected in post‐smolts shortly after sea‐transfer, indicating a possible carry‐over from the hatcheries. In addition, there are reports of prevalences of PMCV as high as 70%–90% in certain groups of broodfish, and a recent outbreak of CMS in the Faroe Islands has been linked to the importation of eggs from a CMS‐endemic area. Thus, there is a need to investigate whether PMCV can be transmitted vertically from infected broodstock to their progeny. In the present study, samples from eggs, larvae, fingerlings and presmolt originating from PMCV‐positive broodstock from two commercial Atlantic salmon producers were tested for PMCV. The prevalence of PMCV in the broodstock was 98% in the hearts, 69% in the roe and 59% in the milt. Piscine myocarditis virus was detected in all stages of the progeny until and including the 40 g stage. Piscine myocarditis virus was also detected in presmolt sampled for tissue tropism. This provides farmers with several options for minimizing the risk of transfer of PMCV from broodstock to progeny, including screening of broodstock and aiming to use only those that are negative for PMCV or have low levels of virus. 相似文献
955.
Nguyen Van Hung Peter Bossier Nguyen Thi X. Hong Christine Ludeseve Linsey Garcia‐Gonzalez Nancy Nevejan Peter De Schryver 《Journal of fish diseases》2019,42(6):777-787
The natural amorphous polymer poly‐β‐hydroxybutyrate (PHB‐A: lyophilized Ralstonia eutropha containing 75% PHB) was used as a biological agent to control bacterial pathogens of blue mussel (Mytilus edulis) larvae. The larvae were supplied with PHB‐A at a concentration of 1 or 10 mg/L for 6 or 24 hr, followed by exposure to either the rifampicin‐resistant pathogen Vibrio splendidus or Vibrio coralliilyticus at a concentration of 105 CFU/ml. Larvae pretreated 6 hr with PHB‐A (1 mg/L) survived a Vibrio challenge better relative to 24 hr pretreatment. After 96 hr of pathogen exposure, the survival of PHB‐A‐treated mussel larvae was 1.41‐ and 1.76‐fold higher than the non‐treated larvae when challenged with V. splendidus and V. coralliilyticus, respectively. Growth inhibition of the two pathogens at four concentrations of the monomer β‐HB (1, 5, 25 and 125 mM) was tested in vitro in LB35 medium, buffered at two different pH values (pH 7 and pH 8). The highest concentration of 125 mM significantly inhibited the pathogen growth in comparison to the lower levels. The effect of β‐HB on the production of virulence factors in the tested pathogenic Vibrios revealed a variable pattern of responses. 相似文献
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959.
Seddighi R Egger CM Rohrbach BW Cox SK Doherty TJ 《Veterinary anaesthesia and analgesia》2011,38(3):195-202
ObjectiveTo determine the possible additive effect of midazolam, a GABAA agonist, on the end-tidal concentration of isoflurane that prevents movement (MACNM) in response to noxious stimulation.Study designRandomized cross-over experimental study.AnimalsSix healthy, adult intact male, mixed-breed dogs.MethodsAfter baseline isoflurane MACNM (MACNM-B) determination, midazolam was administered as a low (LDS), medium (MDS) or high (HDS) dose series of midazolam. Each series consisted of two dose levels, low and high. The LDS was a loading dose (Ld) of 0.2 mg kg?1 and constant rate infusion (CRI) (2.5 μg kg?1 minute?1) (LDL), followed by an Ld (0.4 mg kg?1) and CRI (5 μg kg?1 minute?1) (LDH). The MDS was an Ld (0.8 mg kg?1) and CRI (10 μg kg?1 minute?1) (MDL) followed by an Ld (1.6 mg kg?1) and CRI (20 μg kg?1 minute?1) (MDH). The HDS was an Ld (3.2 mg kg?1) and CRI (40 μg kg?1 minute?1) (HDL) followed by an Ld (6.4 mg kg?1) and CRI (80 μg kg?1 minute?1) (HDH). MACNM was re-determined after each dose in each series (MACNM-T).ResultsThe median MACNM-B was 1.42. MACNM-B did not differ among groups (p >0.05). Percentage reduction in MACNM was significantly less in the LDS (11 ± 5%) compared with MDS (30 ± 5%) and HDS (32 ± 5%). There was a weak correlation between the plasma midazolam concentration and percentage MACNM reduction (r = 0.36).Conclusion and clinical relevanceMidazolam doses in the range of 10–80 μg kg?1 minute?1 significantly reduced the isoflurane MACNM. However, doses greater than 10 μg kg?1 minute?1 did not further decrease MACNM indicating a ceiling effect. 相似文献
960.
New multiple-herbicide crop resistance and formulation technology to augment the utility of glyphosate 总被引:2,自引:0,他引:2
Glyphosate has performed long and well, but now some weed communities are shifting to populations that survive glyphosate, and growers need new weed management technologies to augment glyphosate performance in glyphosate-resistant crops. Unfortunately, most companies are not developing any new selective herbicides with new modes of action to fill this need. Fortunately, companies are developing new herbicide-resistant crop technologies to combine with glyphosate resistance and expand the utility of existing herbicides. One of the first multiple-herbicide-resistant crops will have a molecular stack of a new metabolically based glyphosate resistance mechanism with an active-site-based resistance to a broad spectrum of ALS-inhibiting herbicides. Additionally, new formulation technology called homogeneous blends will be used in conjunction with glyphosate and ALS-resistant crops. This formulation technology satisfies governmental regulations, so that new herbicide mixture offerings with diverse modes of action can be commercialized more rapidly and less expensively. Together, homogeneous blends and multiple-herbicide-resistant crops can offer growers a wider choice of herbicide mixtures at rates and ratios to augment glyphosate and satisfy changing weed management needs. 相似文献