In the eye of the beholder: the effect of rater variability and different rating scales on QTL mapping     

Poland JA  Nelson RJ 《Phytopathology》2011,101(2):290-298

The agronomic importance of developing durably resistant cultivars has led to substantial research in the field of quantitative disease resistance (QDR) and, in particular, mapping quantitative trait loci (QTL) for disease resistance. The assessment of QDR is typically conducted by visual estimation of disease severity, which raises concern over the accuracy and precision of visual estimates. Although previous studies have examined the factors affecting the accuracy and precision of visual disease assessment in relation to the true value of disease severity, the impact of this variability on the identification of disease resistance QTL has not been assessed. In this study, the effects of rater variability and rating scales on mapping QTL for northern leaf blight resistance in maize were evaluated in a recombinant inbred line population grown under field conditions. The population of 191 lines was evaluated by 22 different raters using a direct percentage estimate, a 0-to-9 ordinal rating scale, or both. It was found that more experienced raters had higher precision and that using a direct percentage estimation of diseased leaf area produced higher precision than using an ordinal scale. QTL mapping was then conducted using the disease estimates from each rater using stepwise general linear model selection (GLM) and inclusive composite interval mapping (ICIM). For GLM, the same QTL were largely found across raters, though some QTL were only identified by a subset of raters. The magnitudes of estimated allele effects at identified QTL varied drastically, sometimes by as much as threefold. ICIM produced highly consistent results across raters and for the different rating scales in identifying the location of QTL. We conclude that, despite variability between raters, the identification of QTL was largely consistent among raters, particularly when using ICIM. However, care should be taken in estimating QTL allele effects, because this was highly variable and rater dependent.  相似文献   

Authenticity of the traditional cypriot spirit "zivania" on the basis of metal content using a combination of coupled plasma spectroscopy and statistical analysis     

Kokkinofta R  Petrakis PV  Mavromoustakos T  Theocharis CR 《Journal of agricultural and food chemistry》2003,51(21):6233-6239

Sixty-eight alcoholic beverages ranging in alcoholic degree between 40 and 55 from different countries were analyzed for their 16 most abundant metal elements using inductively coupled plasma (ICP) spectroscopy. The results were analyzed statistically using two different types of analytical methods: canonical discriminant analysis and classification binary trees. The aim of this study was to investigate which of the metals analyzed constitute diagnostic parameters that establish authenticity of the traditional Cypriot spirit zivania. The two statistical methods revealed that Mg, Zn, and Cu are promising distinctive parameters capable of differentiating zivania from other spirits similar in alcoholic degree. It is believed that this differentiation in metals between the alcoholic beverages examined is related to the unique geological and climatic conditions existing on the island of Cyprus.  相似文献   

Phenolic acids in foods: an overview of analytical methodology   总被引：10，自引：0，他引：10  

Robbins RJ 《Journal of agricultural and food chemistry》2003,51(10):2866-2887

Phenolic acids are aromatic secondary plant metabolites, widely spread throughout the plant kingdom. Existing analytical methods for phenolic acids originated from interest in their biological roles as secondary metabolites and from their roles in food quality and their organoleptic properties. Recent interest in phenolic acids stems from their potential protective role, through ingestion of fruits and vegetables, against oxidative damage diseases (coronary heart disease, stroke, and cancers). High performance liquid chromatography (HPLC) as well as gas chromatography (GC) are the two separation techniques reviewed. Extraction from plant matrixes and cleavage reactions through hydrolysis (acidic, basic, and enzymatic) are discussed as are the derivatization reagents used in sample preparation for GC. Detection systems discussed include UV-Vis spectroscopy, mass spectrometry, electrochemical, and fluorometric detection. The most common tandem techniques are HPLC/UV and GC/MS, yet LC/MS is becoming more common. The masses and MS fragmentation patterns of phenolic acids are discussed and tabulated as are the UV absorption maxima.  相似文献   

Determination of hydrolyzable tannins (gallotannins and ellagitannins) after reaction with potassium iodate     

Hartzfeld PW  Forkner R  Hunter MD  Hagerman AE 《Journal of agricultural and food chemistry》2002,50(7):1785-1790

A widely used method for analyzing hydrolyzable tannins afer reaction with KIO(3) has been modified to include a methanolysis step followed by oxidation with KIO(3). In the new method, hydrolyzable tannins (gallotannins and ellagitannins) are reacted at 85 degrees C for 20 h in methanol/sulfuric acid to quantitatively release methyl gallate. Dried plant samples can be methanolyzed under the same conditions to convert hydrolyzable tannins to methyl gallate. Oxidation of the methyl gallate by KIO(3) at pH 5.5, 30 degrees C, forms a chromophore with lambda(max) 525 nm, which is determined spectrophotometrically. The detection limit of the method is 1.5 microg of methyl gallate, and with plant samples, relative standard deviations of less than 3% were obtained.  相似文献   

Interaction of flavonoids with bovine serum albumin: a fluorescence quenching study   总被引：6，自引：0，他引：6  

Papadopoulou A  Green RJ  Frazier RA 《Journal of agricultural and food chemistry》2005,53(1):158-163

The interaction between four flavonoids (catechin, epicatechin, rutin, and quercetin) and bovine serum albumin (BSA) was investigated using tryptophan fluorescence quenching. Quenching constants were determined using the Stern-Volmer equation to provide a measure of the binding affinity between the flavonoids and BSA. The binding affinity was strongest for quercetin and ranked in the order quercetin > rutin > epicatechin = catechin. The pH in the range of 5-7.4 does not affect significantly (p < 0.05) the association of rutin, epicatechin, and catechin with BSA, but quercetin exhibited a stronger affinity at pH 7.4 than at lower pH (p < 0.05). Quercetin has a total quenching effect on BSA tryptophan fluorescence at a molar ratio of 10:1 and rutin at approximately 25:1. However, epicatechin and catechin did not fully quench tryptophan fluorescence over the concentration range studied. Furthermore, the data suggested that the association between flavonoids and BSA did not change molecular conformation of BSA and that hydrogen bonding, ionic, and hydrophobic interaction are equally important driving forces for protein-flavonoid association.  相似文献   

WCVM GLOBAL VETS          下载免费PDF全文

Mairead Drain  Emma Agg  Leanne Boyd  Suzanne Lynde  Rebecca Korven  Karen Kemp  Patrick Garcia  Sarah Flint    Shannon Burns 《The Canadian veterinary journal. La revue veterinaire canadienne》2003,44(2):121-122

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The laboratory maintenance of field-collected Lymnaea tomentosa for the production of Fasciola hepatica metacercariae     

H.V. Whitlock  D.C.M. Chow  J.D. Kelly 《Veterinary parasitology》1976,1(4):317-325

A culture method is described for the production of Fasciola hepatica metacercariae in Lymnaea tomentosa collected from the field habitat. Two-litre glass jars, filled with artificial spring (A.S.) water and having a substratum of soil-bentonite (S.B.) agar to provide habitat and food, maintain groups of 40 to 100 snails graded according to size. Small quantities of washed lettuce are fed as a supplement. Compressed air, pre-warmed to 25°C, is piped to each jar to maintain thermoregulation, aeration, filtration and circulation of the water. Infection is achieved by reducing the A.S. water level to 3–4 mm and exposing the snails to miracidia for 6 h. During the aquatic developmental phase of 5–6 weeks, twice-weekly changes of A.S. water and the filter minimise proliferation of protozoans and Chaetogaster spp. Accumulation of mature cercariae is achieved by sustaining the infected snails on moist S.B. agar while humidification within the jar is maintained. Alternatively, groups of five to ten snails may be held in disposable petri dishes lined with S.B. agar. Maturation of cercariae may be delayed by refrigeration at 4–5°C. Upon maximum accumulation, the cercariae are harvested by dissection of the snails and metacercariae are stored in plastic containers at 4°C.  相似文献   

Equine ehrlichial colitis (Potomac horse fever): recognition of the disease in Pennsylvania, New Jersey, New York, Ohio, Idaho, and Connecticut   总被引：5，自引：0，他引：5  

J E Palmer  R H Whitlock  C E Benson 《Journal of the American Veterinary Medical Association》1986,189(2):197-199

Equine ehrlichial colitis (Potomac horse fever), a newly identified colitis of the horse, was first recognized in Maryland. In this report, we document occurrence of the disease in Pennsylvania, New Jersey, New York, Ohio, Idaho, and Connecticut. Enzootic areas were recognized by a characteristic pattern. Frequently there was a seasonal pattern and high prevalence of sporadic colitis in unstressed horses. The attack rate per farm generally was low. Horses on pasture, as well as those stabled, were affected. Clinical signs varied from fever and depression to severe diarrhea and laminitis. Occasionally horses developed profound ileus and severe colic. Diagnosis was based on detection of an increase or decrease in serum antibody titers to Ehrlichia risticii, using an indirect fluorescent antibody technique.  相似文献   

CLIOXANIDE, A NEW ANTHELMINTIC ACTIVE AGAINST FASCIOLA HEPATIC A AND HAEMONCHUS CONTORTUS IN SHEEP     

I. G. Pearson  B.V.Sc.  H. V. Whitlock  A.A.I.M.L.T.  C. P. DeGoosh  D.V.M.  K. J. Farrington  M.Sc.  R. C. Jones  B.Sc.  Ph.D. J. A. Haigh 《Australian veterinary journal》1970,46(10):480-484

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The relationship between hematocrit, erythrocyte volume, and weight in sheep     

J H Whitlock  R A Menzies  J R Georgi 《The Cornell veterinarian》1967,57(2):276-291

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