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排序方式: 共有121条查询结果,搜索用时 46 毫秒
41.
ABSTRACT Plasmopara viticola is a strictly biotrophic oomycete that causes downy mildew, which is one of the most important grapevine diseases. Control of the disease is most often achieved by fungicide applications, which may have severe environmental consequences. Therefore, alternative control strategies based on biocontrol agents (BCAs) are currently in development. Thousands of potential BCAs have to be screened for their antagonist efficacy against Plasmopara viticola. Evaluation of their effect on the pathogen can be achieved by detecting the amount of P. viticola DNA in leaves treated with potential antagonists and infected with the pathogen. In this study, a rapid high-throughput method was developed for relative quantification of P. viticola DNA directly from Vitis vinifera leaves by means of multiplex real-time quantitative polymerase chain reaction (PCR) with TaqMan chemistry. This method allows simultaneous amplification, but independent detection, of pathogen and host DNA by using species-specific primers and TaqMan probes that are labeled with different fluorescent dyes. Including detection of V. vinifera DNA in the tests is fundamental because it provides an endogenous reference and allows normalization for variations caused by sample-to-sample differences in DNA extraction, PCR efficiencies, and pipetting volumes. The developed method allows highly sensitive and specific detection of P. viticola DNA (minimal detectable quantity of 0.1 pg). Moreover, high precision and reproducibility of TaqMan assays were observed over a linear range of four orders of magnitude, confirming the reliability of the developed PCR assay. Potential applications range from screening for BCA efficiency to evaluation of fungicide efficacy, or assessment of host resistance. 相似文献
42.
Böhnel H Schwagerick B Gessler F 《Journal of veterinary medicine. A, Physiology, pathology, clinical medicine》2001,48(6):373-383
There are reports of a hitherto unknown bovine disease in Germany. The symptoms are, in general, indigestion (constipation alternating with diarrhoea), non-infectious chronic laminitis, engorged veins, oedemas, retracted abdomen, emaciation and apathy. Most cases occur during the peripartal period and often result in unexpected death. In addition, there are findings of delayed growth and wasting in heifers, as well as decreasing milk yield. Clinical and standard laboratory examinations leave the origin undisclosed. Bioassays for Clostridium botulinum, its spores and toxins in animals of affected farms revealed the presence of free botulinum toxin in the contents of the lower sections of the intestine. In two control farms without signs of the disease, the tests remained negative. This seems to support our hypothesis that long-lasting absorption of low quantities of botulinum toxin may interfere with the neurological control of intestinal physiology. The authors propose to name this disease complex 'visceral botulism'. 相似文献
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Locci E Piras C Mereu S Cesare Marincola F Scano P 《Journal of agricultural and food chemistry》2011,59(17):9497-9505
Nuclear magnetic resonance (NMR) spectroscopy combined with multivariate data analysis (MVA) was used to investigate the molecular components of the aqueous extract of samples of bottarga, that is, salted and dried mullet (Mugil cephalus) roe, manufactured in Sardinia (Italy) from mullets of known and unknown geographical provenience. Principal component analysis (PCA) applied to the processed (1)H NMR spectra indicated that samples tend to cluster according to their geographical origin and also on the basis of storage and manufacturing procedures. The most important metabolites that characterized grouping of samples are the free amino acids methionine (Met), glutamate (Glu), histidine (His), phenylalanine (Phe), tyrosine (Tyr), and isoleucine (Ile); trimethylamine (TMA) and dimethylamine (DMA), both biomarkers of degradation; nucleotides and derivatives; choline (Cho) and phosphorylcholine (P-cho); and lactate (Lac). 相似文献
45.
Robert M Zablotowicz L Jason Krutz Cesare Accinelli Krishna N Reddy 《Pest management science》2009,65(6):658-664
BACKGROUND: The objectives of these laboratory experiments were: (1) to assess bromoxynil sorption, mineralization, bound residue formation and extractable residue persistence in a Dundee silt loam collected from 0–2 cm and 2–10 cm depths under continuous conventional tillage and no‐tillage; (2) to assess the effects of autoclaving on bromoxynil mineralization and bound residue formation; (3) to determine the partitioning of non‐extractable residues; and (4) to ascertain the effects of bromoxynil concentration on extractable and bound residues and metabolite formation. RESULTS: Bromoxynil Kd values ranged from 0.7 to 1.4 L kg?1 and were positively correlated with soil organic carbon. Cumulative mineralization (38.5% ± 1.5), bound residue formation (46.5% ± 0.5) and persistence of extractable residues (T1/2 < 1 day) in non‐autoclaved soils were independent of tillage and depth. Autoclaving decreased mineralization and bound residue formation 257‐fold and 6.0‐fold respectively. Bromoxynil persistence in soil was rate independent (T1/2 < 1 day), and the majority of non‐extractable residues (87%) were associated with the humic acid fraction of soil organic matter. CONCLUSIONS: Irrespective of tillage or depth, bromoxynil half‐life in native soil is less than 1 day owing to rapid incorporation of the herbicide into non‐extractable residues. Bound residue formation is governed principally by biochemical metabolite formation and primarily associated with soil humic acids that are moderately bioavailable for mineralization. These data indicate that the risk of off‐site transport of bromoxynil residues is low owing to rapid incorporation into non‐extractable residues. Published 2009 by John Wiley & Sons, Ltd 相似文献
46.
Cecilia Castro Laura Gazza Roberto Ciccoritti Norberto Pogna Cesare Oliviero Rossi Cesare Manetti 《Journal of Cereal Science》2010
Spikes and seeds from diploid ‘einkorn’ wheat Triticum monococcum and two near-isogenic hard and soft common wheat (Triticum aestivum) lines were harvested at regular intervals from 7 days post-anthesis (dpa) and analysed by non-destructive magnetic resonance imaging (MRI) and time domain-nuclear magnetic resonance (TD-NMR). A large amount of free water occurred in rachises, glumes and awns of spikes collected at 7 dpa, and accumulated in the physiologically active cells of the endosperm at 21 dpa. In the final stages of kernel development, awns and seed embryos exhibited a high MR signal due to the presence of free water likely associated with biological activities. TD-NMR relaxation time distributions obtained by discrete exponential fitting, distributed exponential fitting and SLICING multivariate analysis offered detailed information on mobility behaviour of water molecules in developing seeds and were able to differentiate two soft and hard isolines from common wheat cv. Enesco at early stages of seed development. 相似文献
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Robert M. Zablotowicz L. Jason Krutz Mark A. Weaver Cesare Accinelli Krishna N. Reddy 《Biology and Fertility of Soils》2008,45(1):19-26
The co-application of glufosinate with nitrogen fertilizers may alter atrazine cometabolism, thereby extending the herbicide’s
residual weed control in adapted soils. The objective of this study was to assess the effects of glufosinate, ammonium sulfate,
and the combination of glufosinate and ammonium sulfate on atrazine mineralization in a Dundee silt loam exhibiting enhanced
atrazine degradation. Application of glufosinate at rates of 10 to 40 mg kg−1 soil extended the lag phase 1 to 2 days and reduced the maximum degradation rate by 15% to 30%. However, cumulative atrazine
mineralization averaged 85% 21 days after treatment and was independent of treatment. Maximum daily rates of atrazine mineralization
were reduced from 41% to 55% by application of 1 to 8 g kg−1 of ammonium sulfate. Similarly, cumulative atrazine mineralization was inversely correlated with ammonium sulfate rates ranging
from 1.0 to 8 g kg−1 soil. Under the conditions of this laboratory study, atrazine degradation was relatively insensitive to exogenous mineral
nitrogen, in that 8 g (NH4)2SO4 per kilogram soil repressed but did not completely inhibit atrazine mineralization. Moreover, an additive effect on reducing
atrazine mineralization was observed when glufosinate was co-applied with ammonium sulfate. In addition, ammonium fertilization
alters the partitioning of 14C-atrazine metabolite accumulation and nonextractable residues, indicating that ammonium represses cleavage of the triazine
ring. Consequently, results indicate that the co-application of glufosinate with N may increase atrazine persistence under
field conditions thereby extending atrazine residual weed control in adapted soils. 相似文献
50.
Accinelli C Koskinen WC Becker JM Sadowsky MJ 《Journal of agricultural and food chemistry》2008,56(3):1025-1028
Although a number of studies have been done describing the fate of Bacillus thuringiensis insecticidal endotoxins in soil, there is conflicting information on the persistence of this class of insecticidal toxins. This is partly due to methodological limitations in many of the previous studies. In the experiments reported here, 14C-labeled B. thuringiensis Cry1Ac endotoxin was used to study its mineralization in soil incubated under controlled conditions. Fifty-nine percent of the radiolabeled Cry1Ac was recovered as 14CO2 at the end of the 20 day incubation period. The addition of 4.5% corn residues stimulated mineralization of [14C]Cry1Ac toxin, and mineralization of glucose was 3.6 times faster than that of the Cry1Ac toxin, indicating that the soil was microbiologically and metabolically active. Because only low mineralization (approximately 6%) of the radiolabeled toxin was observed in autoclaved soil, the current findings indicate that microbial processes play a major role in the dissipation of the Cry1Ac endotoxin in soil. The results of this study suggest that there may be limited risk of the bioaccumulation of Cry1Ac in soil due to the eventual release of this insecticidal toxin by Bt-protected crops. 相似文献