Mechanism by which noninhibitory concentrations of glucose increase inhibitory activity ofp-coumaric acid on morning-glory seedling biomass accumulation.

Noninhibitory levels of glucose-C [≤ 72 µg carbon (C)/g soil] increased the inhibitory activity ofp-coumaric acid on morning-glory seedling biomass accumulation in Cecil Bt-horizon soil. The amount ofp-coumaric acid required for a given level of inhibition of shoot and seedling biomass accumulation decreased as the concentration of glucose increased. Soil extractions with neutral EDTA (0.25 M, pH 7) after addition of combinations ofp-coumaric acid and glucose (concentrations ranging from 0 to 1.25 µmol/g soil) to the soil showed that utilization ofp-coumaric acid by microbes decreased linearly as the concentration of glucose increased. The increased inhibitory activity of a given concentration ofp-coumaric acid in the presence of glucose was not due to a reduction in soil sorption ofp-coumaric acid or effects of nitrogen-limited microbial growth. Noninhibitory levels of phenylalanine andp-hydroxybenzoic acid slowed the utilization ofp-coumaric acid by microbes in a similar manner as glucose. The presence of methionine, however, did not affect the rate ofp-coumaric acid utilization by microbes. These observations suggest that differential utilization of individual molecules in organic mixtures by soil microbes can modify, and in this case increase, the effectiveness of a given concentration of an inhibitor such asp-coumaric acid on the inhibition of seedling growth such as morning-glory.

Use of water and EDTA extractions to estimate available (free and reversibly bound) phenolic acids in Cecil soils.

Sterile and microbe reinfested Cecil Ap and Bt soil materials amended with 0 to 5 µmol/g of ferulic acid,p-coumaric acid,p-hydroxybenzoic acid, or vanillic acid were extracted after varying time intervals with water, EDTA, or NaOH to characterize sorption of cinnamic and benzoic acid derivatives and to determine the effectiveness of water and EDTA extractions in estimating concentrations of free and reversibly bound phenolic acids in soils. Basic EDTA (0.5 M, pH 8) extractions and water extractions provided good estimates of both free and reversibly bound cinnamic acid derivatives, but not of benzoic acid derivatives. Neutral EDTA (0.25 M, pH 7) and water extractions, however, were effective for both cinnamic and benzoic acid derivatives Rapid initial sorption of both cinnamic and benzoic acid derivatives was followed by slow long-term sorption of the cinnamic acid derivatives. Slow long-term sorption was not observed for the benzoic acid derivatives. The amount of sorption of phenolic acids in soil materials was directly related to the concentration of phenolic acids added to soil materials. The addition of a second phenolic acid to the soil materials did not substantially affect the sorption of each individual phenolic acid. Sodium hydroxide extractions, which were made only after phenolic acids in phenolic acid-amended and non-amended soil material were depleted by microbes, confirmed that neutral EDTA and water extractions of soils can be used to make accurate estimates of baseline (residual) levels of free and reversibly bound phenolic acids available to soil microbes and, thus, potentially to seeds and roots.

Simultaneous effects of ferulic andp-coumaric acids on cucumber leaf expansion in split-root experiments.

Experiments were conducted to determine how plant responses to mixtures of allelochemicals may change as the proportion of roots in contact with allelochemicals is modified. Thirteen-day-old cucumber seedlings were treated with ferulic and/orp-coumaric acid in a split-root nutrient culture system. Leaf areas were determined just prior to treatment and at harvest, 24 hr after treatment. Ferulic acid was more inhibitory to cucumber leaf expansion thanp-coumaric acid. The effects of ferulic andp-coumaric acids on leaf expansion were additive. For individual acids, mixtures of ferulic andp-coumaric acids in the same container and combinations of ferulic andp-coumaric acids in separate containers, the inhibition of leaf expansion was directly related to the product of the concentration of the acid(s) and the proportion of roots treated with the acid(s). Pretreatment with 0.2 or 0.4 mM ferulic acid and subsequent treatment with 0.5 mM ferulic acid failed to show evidence of acclimation by cucumber seedlings.

Power studies in the estimation of genetic parameters and the localization of quantitative trait loci for backcross and doubled haploid populations.

A statistical model for doubled haploids and backcrosses based on the interval-mapping methodology has been used to carry out power studies to investigate the effects of different experimental designs, heritabilities of the quantitative trait, and types of gene action, using two test statistics, the F of Fisher-Snedecor and the LOD score. The doubled haploid experimental design is more powerful than backcrosses while keeping actual type I errors similar to nominal ones. For the doubled haploid design, individual QTLs, showing heritabilities as low as 5% were detected in about 90% of the cases using only 250 individuals. The power to detect a given QTL is related to its contribution to the heritability of the trait. For a given nominal type I error, tests using F values are more powerful than with LOD scores. It seems that more conservative levels should be used for the LOD score in order to increase the power and obtain type I errors similar to nominal ones.

Modification of an inhibition curve to account for effects of a second compound.

Three methods are proposed for modifying a logistic inhibition curve for a primary compound to account for the role of a second compound. The assumptions underlying each of the three resulting models-similar joint action, multiplicative, and modification-are discussed. The models are compared and model selection procedures are given. An example is presented in which the inhibiting effect ofp-coumaric acid on the growth of morning-glory plants is modified by the addition of glucose.

Modification of allelopathic effects ofp-coumaric acid on morning-glory seedling biomass by glucose, methionine, and nitrate.

Studies of allelopathy have emphasized primarily the identification and quantification of phytotoxins in soils, with only limited attention directed toward how organic (carbon) and inorganic constituents (nutrients) in the soil may modify the action of such phytotoxins. In the present study, increasing carbon (C) levels (up to 108µg C/g soil) supplied as glucose, phenylalanine, orp-hydroxybenzoic acid did not alter morning-glory biomass, but similar C levels supplied as leucine, methionine, orp-coumaric acid were inversely related to morning-glory biomass. Similar joint action and multiplicative analyses were used to describe morning-glory biomass response to various C sources and to generate dose isolines for combinations ofp-coumaric acid and methionine at two NO3-N levels and for combinations ofp-coumaric acid and glucose at one NO3-N level. Methionine, glucose, and NO3-N treatments influenced the inhibitory action ofp-coumaric acid on biomass production of morning-glory seedlings. For example, results from the multiplicative analysis indicated that a 10% inhibition of morning-glory biomass required 7.5µgp-coumaric acid/g soil, while the presence of 3.68µg methionine/g soil thep-coumaric acid concentration required for 10% inhibition was only 3.75µg/ g soil. Similar response trends were obtained forp-coumaric acid and glucose. The higher NO3-N (14 vs. 3.5µg/g) treatments lowered the methionine and increased thep-coumaric acid concentrations required for 10% inhibition of morning-glory biomass. These results suggested that allelopathic interactions in soil environments can be a function of interacting neutral substances (e.g., glucose), promoters (e.g., NO3-N), and/or inhibitors (e.g., methionine andp-coumaric acid) of plant growth.

Effects of dietary protein source on Basenjis with immunoproliferative enteropathy.

The effects of 3 experimental diets that varied only in the source of dietary protein (ie, poultry, cereal, red meat) were compared in Basenjis (n = 8) with immunoproliferative enteropathy and healthy Beagles (n = 8). Significant differences in fecal character, serum IgA concentration, and intestinal digestive and absorptive function were not induced by the different sources of dietary protein. The results of this study do not support a causal role for dietary protein source in the pathogenesis of immunoproliferative enteropathy of Basenjis.

Allelopathic activity in wheat-conventional and wheat-no-till soils: Development of soil extract bioassays.

The primary objective of this research was to determine if soil extracts could be used directly in bioassays for the detection of allelopathic activity. Here we describe: (1) a way to estimate levels of allelopathic compounds in soil; (2) how pH, solute potential, and/or ion content of extracts may modify the action of allelopathic compounds on germination and radicle and hypocotyl length of crimson clover (Trifolium incarnatum L.) and ivyleaved morning glory (Ipomoea hederacea L. Jacquin.); and (3) how biological activity of soil extracts may be determined. A water-autoclave extraction procedure was chosen over the immediate-water and 5-hr EDTA extraction procedures, because the autoclave procedure was effective in extracting solution and reversibly bound ferulic acid as well as phenolic acids from wheat debris. The resulting soil extracts were used directly in germination bioassays. A mixture of phenolic acids similar to that obtained from wheat-no-till soils did not affect germination of clover or morning glory and radicle and hypocotyl length of morning glory. The mixture did, however, reduce radicle and hypocotyl length of clover. Individual phenolic acids also did not inhibit germination, but did reduce radicle and hypocotyl length of both species. 6-MBOA (6-methoxy-2,3-benzoxazolinone), a conversion product of 2-o-glucosyl-7-methoxy-1,4-benzoxazin-3-one, a hydroxamic acid in living wheat plants, inhibited germination and radicle and hypocotyl length of clover and morning glory. 6-MBOA, however, was not detected in wheat debris, stubble, or soil extracts. Total phenolic acids (FC) in extracts were determined with Folin and Ciocalteu's phenol reagent. Levels of FC in wheat-conventionaltill soil extracts were not related to germination or radicle and hypocotyl length of either species. Levels of FC in wheat-no-till soil extracts were also not related to germination of clover or morning glory, but were inversely related to radicle and hypocotyl length of clover and morning glory. FC values, solute potential, and acidity of wheat-no-till soil extracts appeared to be independent (additive) in action on clover radicle and hypocotyl length. Radicle and hypocotyl length of clover was inversely related to increasing FC and solute potential and directly related to decreasing acidity. Biological activity of extracts was determined best from slopes of radicle and hypocotyl length obtained from bioassays of extract dilutions. Thus, data derived from the water-autoclave extraction procedure, FC analysis, and slope analysis for extract activity in conjunction with data on extract pH and solute potential can be used to estimate allelopathic activity of wheat-no-till soils.

Clinical evaluation of 1% cyclosporine for topical treatment of keratoconjunctivitis sicca in dogs.

Keratoconjunctivitis sicca (KCS) is a prevalent and often vision-threatening condition in dogs. In several reports, 2% cyclosporine (cyclosporin A, CsA) was described as effective in modulating the clinical signs of KCS. This study was designed to compare the efficacy of 1% CsA vs a placebo, using a randomized double-blind clinical trial. Topical administration of 1% CsA significantly improved Schirmer wetting values and subjective markers of corneal health as compared with the placebo. In the dogs treated with topical administration of 1% CsA, the clinical signs of KCS were improved in 81.8% of cases.

Efficacy and toxicity of doxorubicin/cyclophosphamide maintenance therapy in dogs with multicentric lymphosarcoma.

Doxorubicin/cyclophosphamide were evaluated as maintenance drugs for dogs with multicentric lymphosarcoma (n = 28). Median remission time of all dogs was 173 days. Remission duration was shorter, however, in dogs with stage IV/V disease, in dogs with pretreatment hypoalbuminemia, and in dogs that had received glucocorticoids before initiation of chemotherapy (P less than 0.04). Nineteen dogs were evaluable for toxicity. Dose-limiting gastrointestinal toxicosis was observed in three dogs, neutropenia was observed in three dogs, and cardiomyopathy was observed in three dogs. The doxorubicin/cyclophosphamide protocol described in this report is safe and effective in treating canine multicentric lymphosarcoma. Clinical stage, pretreatment steroid therapy, and hypoalbuminemia are prognostic factors for response to this protocol.

Interlaboratory comparison of titers of antibody to Borrelia burgdorferi and evaluation of a commercial assay using canine sera.

Sixty canine serum samples were sent to 10 different diagnostic laboratories for anti-Borrelia burgdorferi antibody analysis. All laboratories knew of the study prior to receiving the samples. Agreement among all laboratories for all interpretations was 91% (546 of 600 samples). There was complete agreement among all the laboratories for only 32 (53%) of the samples. Most of the disagreements were due to differences reported by either one (15 samples) or two (7 samples) laboratories per sample. When discrepancies in interpretations existed, the interpretation reported by the majority of the laboratories was considered the standard for comparison. One laboratory had no discrepant interpretations from this standard, while the laboratory with the most discrepancies had 16. The median number of discrepancies per laboratory was five. By using pairwise comparisons between each laboratory and the majority standard, eight of the laboratories showed strong agreement and the remaining two showed fair to good agreement. The type of test used (enzyme-linked immunosorbent assay versus indirect immunofluorescence assay) did not appear to influence the number of discrepant interpretations reported. Sera considered to be positive by the majority of the laboratories usually reacted to more than five antigens in immunoblots, with at least three or more of those being intense reactions. For positive samples, reactivity was consistently present in the 60-, 41-, 31-, and 22- or 24-kDa regions. Samples considered negative usually reacted to fewer than three bands, with reactivity usually being faint. A commercially available, rapid dot blot assay showed strong agreement with the majority standard.

Effects of mixtures of four phenolic acids on leaf area expansion of cucumber seedlings grown in Portsmouth B1 soil materials.

Cucumber seedlings growing in a 1∶2 mixture of soil (Portsmouth B1) and sand adjusted to pH 5.2 were treated every other day five times with 0, 0.0625, 0.125, 0.25, or 0.5 µmol/g soil of ferulic, caffeic,p-coumaric,p-hydroxybenzoic, protocatechuic, sinapic, syringic, or vanillic acids. Treatments began when seedlings were 8 days old. The effects on mean absolute rates of leaf expansion were used to estimate the relative potencies of these phenolic acids to ferulic acid. Based on the results of this experiment, ferulic,p-coumaric,p-hydroxybenzoic, and vanillic acids were chosen for further study. Materials and procedures were identical in the second study, but treatments consisted of mixtures of the four phenolic acids at concentration combinations designed to achieve 40 % or 60 % inhibition of absolute rates of leaf expansion. Using joint action analysis, a model describing the action of the phenolic acid mixtures was developed. A model involving only two factor terms was sufficient to describe the observed responses of cucumber leaf area to the phenolic acid mixtures. The action ofp-hydroxybenzoic acid on absolute rates of leaf expansion was inhibited by the presence of the other three phenolic acids. No other antagonisms or synergisms existed among the four compounds.

Phenolic acid content of soils from wheat-no till, wheat-conventional till, and fallow-conventional till soybean cropping systems.

Soil core (0-2.5 and/or 0-10 cm) samples were taken from wheat no till, wheat-conventional till, and fallow-conventional till soybean cropping systems from July to October of 1989 and extracted with water in an autoclave. The soil extracts were analyzed for seven common phenolic acids (p-coumaric, vanillic,p-hydroxybenzoic, syringic, caffeic, ferulic, and sinapic; in order of importance) by high-performance liquid chromatography. The highest concentration observed was 4 µg/g soil forp-coumaric acid. Folin & Ciocalteu's phenol reagent was used to determine total phenolic acid content. Total phenolic acid content of 0- to 2.5-cm core samples was approximately 34% higher than that of the 0- to 10-cm core samples. Phenolic acid content of 0- to 2.5-cm core samples from wheat-no till systems was significantly higher than those from all other cropping systems. Individual phenolic acids and total phenolic acid content of soils were highly correlated. The last two observations were confirmed by principal component analysis. The concentrations were confirmed by principal component analysis, tions of individual phenolic acids extracted from soil samples were related to soil pH, water content of soil samples, total soil carbon, and total soil nitrogen. Indirect evidence suggested that phenolic acids recovered by the water-autoclave procedure used came primarily from bound forms in the soil samples.

Evaluation of four commercial anaerobic systems for identification of Eubacterium suis.

Four commercial anaerobic systems (CASs) were evaluated for usefulness in identification of Eubacterium suis. Twelve strains were evaluated in each system in triplicate, and results were interpreted independently by 5 individuals. Statistically significant differences (P less than 0.01) due to strain variation and reader interpretation accounted for discrepancies encountered. The reactivity, repeatability, and unique profiles generated made both CAS-1 and CAS-2 suitable adjuncts for identification of E. suis when colony morphology and Gram reaction were considered. Limited reactivity in CAS-3 limited its use as an aid in identification. Variability in test observations and the large number of numerical profiles generated precluded use of CAS-4.

Effects of mixtures of phenolic acids on phosphorus uptake by cucumber seedlings.

To determine how individual phenolic acids in a mixture might affect phosphorus (P) uptake, 15-day-old cucumber seedlings grown in solution culture were treated with ferulic, vanillic,p-coumaric, or equimolar mixtures of these phenolic acids. Phenolic acid and P uptake were determined by solution depletion. The joint action of the mixtures of these phenolic acids on P uptake was primarily additive. Thus, as the number of phenolic acids increased in the mixture, the concentrations of the individual phenolic acids in the mixture required to bring about a given response declined. Seedling uptake of individual phenolic acids from solution mixtures of phenolic acids was reduced when compared to the uptake of phenolic acids from single phenolic acid solutions. The magnitude of the reduction varied with phenolic acid and concentration. The dose required for 50% inhibition of P uptake was approximately two to three times higher for vanillic acid (6.73 mM) than for ferulic (2.27 mM) andp-coumaric acids (3.00 mM) when dose was based on the initial treatment concentrations. The dose required for 50% inhibition of P uptake was not significantly different for the three phenolic acids (42 ± 5 µmol/g root fresh weight) when dose was based on phenolic acid uptake. Potential reasons for these differences are discussed.

Effects of mixtures of phenolic acids on leaf area expansion of cucumber seedlings grown in different pH portsmouth A1 soil materials.

Cucumber seedlings growing in A1horizon Portsmouth soil material adjusted to pH 5.2, 6.0, or 6.9 were treated with 0, 0.25 or 0.5, µmol/ g soil ferulic acid,p-coumaric acid, vanillic acid, or an equal mixture (0.5 µmol/g total) of two acids every other day. A total of five treatments was given starting with day 7 from seeding. Absolute rates of leaf expansion were determined for seedlings. The experiment was terminated when seedlings were 17 days old. All three phenolic acids inhibited leaf expansion. The dose required for 50% inhibition of absolute rates of leaf expansion increased as pH of the soil systems increased. The order of toxicity based on 50% dose and relative potency were as follows: ferulic acid > vanillic acid =p-coumaric acid. Effects of mixtures of phenolic acids on absolute rates of leaf expansion, when compared to the effects of individual phenolic acids, were found to be antagonistic for the ferulic-vanillic acid mixture and the ferulic-p-coumaric acid mixture in the pH 5.2 soil systems. Several phenolic acid treatments were required before antagonistic effects of mixtures were evident. In all other instances, when treatment effects were significant, the effects of individual phenolic acids were additive.

Statistical analysis of the joint inhibitory action of similar compounds.

A statistical model is presented that characterizes the joint action of similar compounds when the response variable is continuous. The model allows for antagonistic and synergistic as well as similar joint (additive) action of compounds. It also allows for differential potencies in the compounds. A method of statistical analysis using nonlinear regression analysis is presented along with sample SAS code for carrying it out. An efficient experimental design is given in the form of a set of mixture combinations. Two generalizations of the model are discussed. An example is presented relating the joint action of ferulic and vanillic acids to the growth of cucumber seedlings.

Experimental cryptosporidiosis and infectious bursal disease virus infection of specific-pathogen-free chickens.

Specific-pathogen-free chickens orally inoculated at 4 days of age with a moderately pathogenic vaccine strain of infectious bursal disease virus (IBDV) and/or at 5 days of age with Cryptosporidium baileyi oocysts remained free of overt clinical signs throughout a 16-day period postinoculation (PI). The prepatency period for C. baileyi oocyst shedding was shorter in chickens receiving higher numbers of oocysts, but once shedding was detected, there were no obvious differences in shedding patterns among groups receiving 10(3) through 10(6) oocysts. On days 8 and 16 PI, cryptosporidia were located primarily in the bursae of Fabricius. IBDV exposure was associated with bursal follicle atrophy, whereas C. baileyi infection resulted in bursal epithelial hypertrophy and hyperplasia, mild follicle atrophy, and heterophil infiltration of the bursal mucosa. Examination of experimental groups of 30 birds each indicated that concurrent infection with both agents resulted in more severe bursal lesions, more infected birds, and greater numbers of cryptosporidia in infected tissues. At the termination of the trial, 16 days PI, Cryptosporidium infection was associated with a 6% decrease in mean body weight compared with controls.

Intestinal and bursal cryptosporidiosis in turkeys following inoculation with Cryptosporidium sp. isolated from commercial poults.

Cryptosporidium meleagridis oocysts, originally isolated from droppings of commercial turkey poults with increased mortality due to viral (reovirus) hepatitis and enteritis, were treated with peracetic acid to kill companion bacteria and viruses and then propagated by passage in young turkeys. Thirty-eight 5-day-old large white turkey poults were inoculated by crop gavage with 500,000 cryptosporidial oocysts and compared with 40 uninoculated poults. Cryptosporidial oocysts shedding began 3 days postinoculation (PI), peaked on day 4 PI, and persisted at a low level for the duration of the 21-day trial. Low to moderate cryptosporidial infections of the ileal mucosa (days 3, 6, and 15 PI), cecal mucosa (days 3, 6, and 21 PI), and bursa of Fabricius (days 6, 12, 15 and 21 PI) were found on histopathological examination. There were no differences in mean body weights between the inoculated and uninoculated groups, and no mortality or clinical signs of disease were seen in either group.