Search

Stewart's wilt reactions of 98 food-grade, white corn hybrids, 3 yellow dent corn hybrids, and 23 sweet corn hybrids and infection of kernels by E. stewartii were evaluated in 1998, 1999, and 2000. Stewart's wilt symptoms were rated from 1 (no appreciable spread of symptoms) to 9 (dead plants) following inoculation. The mean Stewart's wilt ratings for the food-grade, white corn and yellow dent corn hybrids were 1.9, 2.4, and 2.9 in 1998, 1999, and 2000, respectively. The mean Stewart's wilt ratings for the sweet corn hybrids were 3.8, 4.2, and 4.6 in 1998, 1999, and 2000, respectively. Hybrids with ratings less than 3 were classified as resistant. Hybrids with ratings between 3 and 4.5 were classified as moderate. Hybrids with ratings greater than 4.5 were classified as susceptible. Ears harvested from each row in 1998 and 1999 were assayed for E. stewartii using an enzyme-linked immunosorbent assay (ELISA)-based seed health test. Kernels from 16 hybrids were positive for E. stewartii in 1998. Kernels from 11 hybrids were positive for E. stewartii in 1999. Kernel infection by E. stewartii was affected considerably by the level of host resistance (i.e., reactions of seed parent plants). For hybrids classified as resistant, estimates of kernel infection were 0.024 and 0.0007% in 1998 and 1999, respectively. For hybrids with moderate reactions to Stewart's wilt, estimates of kernel infection were 0.19 and 0.07% in 1998 and 1999, respectively. For hybrids with susceptible reactions to Stewart's wilt, estimates of kernel infection were 11.6 and 7.8% in 1998 and 1999, respectively. Based on high levels of Stewart's wilt resistance in food-grade, white corn hybrids, and low rates of kernel infection by E. stewartii in resistant and moderate hybrids, there is an exceedingly low probability of introducing E. stewartii to areas where it does not occur by transmitting the bacterium in grain of the food-grade, white corn hybrids evaluated in this study. Although all of the kernels harvested in these experiments were produced as grain on open-pollinated F1 hybrids, the rates of kernel infection observed for hybrids with resistant, moderate and susceptible reactions to Stewart's wilt are applicable to seed produced on inbred lines with equivalent Stewart's wilt reactions.

Rates of transmitting Erwinia stewartii from seed to seedlings were estimated from field grow-outs of seedlings grown from seed infected with E. stewartii. Infected seed were produced in 1998, 1999, and 2000 on a Stewart's wilt-susceptible sweet corn hybrid, Jubilee. Seedlings were inoculated repeatedly with pinprick inoculators and suspensions of E. stewartii were injected into ear shanks of the primary ears of each adult plant. Seed from inoculated plants were harvested and bulked. Single kernels were assayed for E. stewartii to estimate the proportion of kernels infected with E. stewartii. Estimates of E. stewartii-infection were 15.6 ± 4.3, 49.4 ± 3.9, and 12.5 ± 2.4% for seed produced in 1998, 1999, and 2000, respectively. Approximately 61,800 seedlings were grown in DeKalb, IL in 1999 and 83,400 and 60,000 seedlings were grown in Plover WI in 2000 and 2001, respectively, from infected seed lots produced the previous year. Approximately 10,000, 12,200, and 29,400 seedlings of susceptible sweet corn hybrids also were grown each year from commercial seed produced in Idaho where Stewart's wilt does not occur. Based on estimates of kernel infection in each seed lot and plant populations in each grow-out trial, about 9,600, 41,200, and 7,500 seedlings were grown from infected kernels in 1999, 2000, and 2001, respectively. Seedlings at the two- to three-leaf stage were examined for symptoms of Stewart's wilt. Infected plants were confirmed by microscopic observations of bacterial ooze and by enzyme-linked immunosorbent assay. When data were combined from all three trials, 59 of approximately 58,300 seedlings grown from infected seed were infected with E. stewartii based on symptoms of Stewart's wilt and E. stewartii-positive leaf tissue samples. Of these 59 seedlings, 22 probably were infected from seed-to-seedling transmission of E. stewartii and 37 probably were the result of natural infection due to the presence of flea beetles in DeKalb in 1999. Twenty-two infected seedlings from 58,300 infected kernels corresponds to a seed-to-seedling transmission rate of 0.038%. This rate of seed-to-seedling transmission of E. stewartii is substantially lower than seed transmission rates reported in the first half of the twentieth century; however, it is similar to seed-to-seedling transmission rates reported from other recent research.

Kleinschmidt, C. E., Clements, M. J., Maragos, C. M., Pataky, J. K., and White, D. G. 2005. Evaluation of food-grade dent corn hybrids for severity of Fusarium ear rot and fumonisin accumulation in grain. Plant Dis. 89:291-297. Fumonisins produced by Fusarium verticillioides (syn = F. moniliforme) and F. proliferatum have been associated with potentially serious toxicoses of animals and humans. Thus, hybrids with low fumonisin accumulation in grain will be valuable for the production of corn-based human food products. We evaluated 68 food-grade dent corn hybrids for severity of Fusarium ear rot and fumonisin accumulation in grain in inoculated trials in Urbana, IL in 2000 and 2001. Our inoculation technique was successful in initiating fumonisin accumulation that allowed discrimination among hybrids. We identified several hybrids that could have acceptable levels (

Our objective was to determine the value of corn (Zea mays) inbred Oh516 as a source of resistance to Aspergillus ear rot and aflatoxin accumulation in grain. Types and magnitudes of gene action associated with resistance were determined with generation means analysis. Molecular markers associated with resistance were identified from BCP1S1families developed from the cross of the susceptible inbred B73 and Oh516. In 2001 and 2002, B73 (P1), Oh516 (P2), and the F1, F2, F3, BCP1, BCP2, and BCP1S1generations were evaluated for aflatoxin concentration in grain, percent bright greenish yellow fluorescence (BGYF), and severity of Aspergillus ear rot following inoculation in Urbana, IL. BCP1S1families testcrossed with LH185 also were evaluated at three locations in 2002. Molecular marker-quantitative trait loci (QTL) associations with all traits were determined with single factor analysis of variance. Dominance gene action was associated with aflatoxin concentration in grain and percent BGYF. QTL associated with aflatoxin accumulation in grain were identified on chromosomes 2, 3, and 7 (bins 2.01 to 2.03, 2.08, 3.08, and 7.06). Alleles from inbred Oh516 on chromosomes 2, 3, and 7 should improve resistance of commercially used, B73-type inbreds.

Two sets of experiments were done to examine whether seed-treatment chemicals affected the ability of an enzyme-linked immunosorbent assay (ELISA)-based seed health test to detect Erwinia stewartii. The chemicals evaluated included Actellic, Apron, Captan, Cruiser, Gaucho, Maxim, Poncho, Thiram, and Vitavax in 11 seed-treatment combinations. In one experiment, seed-treatment chemicals were evaluated quantitatively in a critical region of ELISA absorbance values near 0.5 using maize seed that were spiked with uniform quantities of a liquid suspension of E. stewartii. The number of bacteria in each sample was estimated from ELISA absorbance values using standard curves. Log CFU of E. stewartii per sample were not significantly different among the untreated control and the 11 seed treatments compared with Tukey's Studentized Range Test (P = 0.05). Means of log CFU/ml for all treatments were tightly clustered around 5.70 which corresponded to an absorbance value of 0.440 and a bacterial population of about 500,000 CFU/ml. In a second set of experiments, seed treatment chemicals were evaluated based on qualitative decisions that resulted from the ELISA-based seed health test of seed lots of Jubilee and A632 infected with E. stewartii. The number of negative samples was not substantially greater than expected based on binomial probabilities except for samples of Captan/Vitavax-treated A632, which we considered to be a type I error. The mean absorbance values of positive samples ranged from 1.42 to 1.72 for A632 and from 1.51 to 1.91 for Jubilee and did not differ significantly among the seed treatments. There was no consistent evidence from these experiments that fungicide or insecticide seed treatments interfered with the sensitivity of the ELISA or altered low (e.g., 0.5) or high (e.g. 1.4 to 1.9) absorbance values. The ability of the ELISA-based seed health test to detect E. stewartii in maize seed was not affected by these seed treatments.

Our objectives were to determine if the corn (Zea mays) inbred MI82 has alleles for resistance to Aspergillus ear rot (caused by Aspergillus flavus) and aflatoxin accumulation in grain that can be transferred to commercially used inbreds, and to determine the types and magnitudes of gene action, heritabilities, and gain from selection for low levels of bright greenish-yellow fluorescence (BGYF), aflatoxin, and ear rot with MI82. Also, we hoped to determine if selection against BGYF would substantially reduce the concentration of aflatoxin in grain. Primary ears and ground grain from inbred MI82 (P1), the susceptible inbred B73 (P2), and the F1, F2, F3, BCP1S1, and BCP2S1generations developed from these inbreds were evaluated for BGYF, concentration of aflatoxin in grain, and severity of Aspergillus ear rot in 2000 and 2001. Dominance was the most important gene action associated with low levels of BGYF and a low concentration of aflatoxin in grain. Heritabilities for low levels of BGYF (83.5%), aflatoxin (74.1%), and ear rot (62.8%) were high. Correlation coefficients between aflatoxin and BGYF were high in both years (r = 0.75 and 0.79 for 2000 and 2001, respectively). Unlike aflatoxin, BGYF was not affected by the year in which plants were grown. Selection for low levels of BGYF prior to selection based on aflatoxin concentration is as effective as selection for either factor alone. MI82 has value in programs designed to improve the resistance of commercially used corn inbreds.

High-oil corn (Zea mays L.) grain is a valuable component of feed for monogastric livestock. One method of increasing the concentration of oil in corn grain is the TopCross method. With TopCross, ears of a cytoplasmic male-sterile, normal-oil hybrid are pollinated by a male-fertile, high-oil synthetic hybrid. The concentration of oil in the resulting grain is increased because of xenia effects. Kernels of high-oil corn typically have a larger germ and a smaller endosperm than kernels of comparable normal hybrids. The growth of Aspergillus flavus Link:Fr within germ tissue has been reported to be more extensive than that on the whole corn kernel; therefore, the severity of Aspergillus ear rot could be more extensive and aflatoxin concentrations could be higher in high-oil grain produced by TopCross than in grain with a lower concentration of oil. The objective of this study was to compare Aspergillus ear rot severity levels and aflatoxin concentrations in the grains of hybrids crossed with high-oil or normal-oil pollinators. Fifteen hybrids were evaluated in 1998 and 1999 in Urbana, Ill. Primary ears were inoculated with A. flavus and evaluated for susceptibility to Aspergillus ear rot and aflatoxin production in grain. Concentrations of aflatoxin and oil in corn kernels were significantly higher for high-oil hybrids than for normal-oil hybrids; however, ear rot severity was unaffected by the type of pollinator. These results suggest that grain from high-oil hybrids is at greater risk for aflatoxin contamination during some growing seasons.

Fumonisins have been associated with potentially serious toxicoses of animals and humans. Prior to initiating a corn (Zea mays) breeding program for resistance to these mycotoxins, an efficient inoculation technique must be developed. Four inoculation techniques were evaluated on 14 commercial corn hybrids in Urbana, IL in 1999 and 2000. The techniques were: injection of inoculum through the ear husk leaves at R2 (blister); silks sprayed with inoculum at R2 and covered with a shoot bag until harvest; silks sprayed with inoculum at R2, covered with a shoot bag, reinoculated 1 week thereafter, and covered with a shoot bag until harvest; and insertion of six Fusarium-colonized toothpicks into the silk channel at R2. Only injection of inoculum through the husk leaves significantly increased the concentration of fumonisin in grain and severity of Fusarium ear rot compared with a control. This technique effectively differentiated hybrids previously identified as resistant or susceptible to Fusarium ear rot. The rank order of hybrids inoculated with this technique did not significantly change in the 2 years of this study. This technique is suitable for efficiently evaluating a large number of corn genotypes for resistance to Fusarium ear rot and fumonisin concentration.

This study determined the types and magnitude of gene action, estimated heritabilities, and predicted gain from selection for resistance to Aspergillus ear rot and aflatoxin production in the cross of resistant corn inbred CI2 to susceptible inbred B73 in 1998 and 1999. The warm, dry summer of 1998 favored aflatoxin production, whereas the conditions of 1999 did not. Resistance to ear rot was mainly controlled by additive gene action. Aflatoxin values were analyzed by individual years (environments) because of the highly significant generation × environment interaction. Resistance to aflatoxin production was mainly controlled by epistasis in 1998 and by additive gene action in 1999. Heritabilities for ear rot and aflatoxin production were higher in the F3generation than in the BCP1-selfed generation. In 1998, Spearman's correlation coefficients between Aspergillus ear rot ratings and aflatoxin values for the F3and the BCP1-selfed families were not significant (P > 0.05). In 1999, both were highly significant (P < 0.01), but low at 0.41 and 0.17 for the F3and BCP1-selfed generations, respectively. We found that CI2 is not an acceptable source of resistance due to lower heritabilities and disease resistance compared to other sources of resistance.

Changes occurring in stored solin/flax cultivars over 6 mo at temperatures ranging from 10 to 35 °C and moisture contents of 8.0, 9.5, 11.0 and 12.5% were observed. The cultivars were NorLin, McGregor, FP1001 (high linolenic acid), LinolaTM 947 (solin) and LinolaTM 989 (solin). Oil composition in all cultivars changed only slightly over 6 mo with a significant increase in palmitic acid. Doubling of free fatty acid levels was considered an indicator of quality deterioration. The deterioration occurred in 6 mo at 8% MC and 20 °C in FP1001 and in NorLin, McGregor, and LinolaTM 947 at 25 °C; LinolaTM 989 could be stored at 30 °C. LinolaTM 989 could be safely stored at moderately higher temperatures at a given moisture level than LinolaTM 947. Visible mold with corresponding germination loss was usually associated with Aspergillus glaucus group infection. Stored-product insects that could survive and develop on the solin/flax were the red flour beetle, Tribolium castaneum (Herbst), the confused flour beetle, T. confusum J. du Val, the sawtoothed grain beetle, Oryzaephilus surinamensis (L.) and the merchant grain beetle, O. mercator (Fauvel).In general, LinolaTM 947 and FP1001 were slightly more difficult to store than the other cultivars but there was no consistent difference between solin and flaxseed. Key words: Flaxseed, solin, storage, quality

The inheritance of resistance to aflatoxin production in corn (Zea mays) caused by the fungus Aspergillus flavus was studied following inoculation in progeny derived from the cross between the susceptible inbred B73 and the resistant inbred LB31. In 1993, the susceptible parent B73 (P1), resistant parent LB31 (P2), F1, F3, and BCP1-selfed generations were evaluated. In 1994, the study was expanded to include the F2, BCP1, and BCP2generations. Aflatoxin concentrations were higher in 1993 than 1994. Generation mean analysis showed that additive and dominant gene action were important for resistance to aflatoxin production. Potence ratios indicated dominance for resistance in both years. In 1993, aflatoxin values of the F1generation were significantly lower than the calculated mid-parent values, indicating dominant gene action favoring resistance. In 1994, values of the F1generation were not significantly lower than the calculated midparent value. The frequency distributions of aflatoxin values for families of the F3and BCP1-selfed generations were skewed toward the resistant parent, also indicating dominance. Heritability based on a progeny mean basis of F3families representing the additive variance plus one-fourth of the dominance variance was estimated at 66% over both years combined. Based on these results, selection for resistance to aflatoxin production in progeny derived from the cross between B73 and LB31 should be effective.

We examined 27 hepatectomy specimens to assess the frequency of foam cell endovasculitis and bile duct loss in chronic rejection. Arterial lesions, defined as total occlusion by subintimal foam cells and/or fibromuscular proliferation, were found mainly in hilar and septal arteries, whereas bile duct loss, defined as the absence of bile ducts in more than 50% of portal tracts, affected mainly small tracts. Both were found in 20 livers (74%). In two livers (7%) there was significant bile duct loss but no arterial lesions, whilst in five cases (19%) there were occlusive arterial lesions but no bile duct loss. Small arteries were involved in only 10% of the cases. These results indicate that in one-third of the cases arterial and bile duct lesions develop independently of each other, suggesting different pathogenetic pathways. In addition, liver biopsy may not be pathognomonic since small arteries are involved in only 10% of cases and bile duct loss may not be extensive. In such cases the diagnosis of chronic rejection should only be made in the presence of progressive clinical deterioration.

1. The role played by the endothelium-derived relaxing factor (EDRF), nitric oxide (NO) in the regulation of blood flow to the skeletal muscle vasculature of the dog skinned hindlimb has been determined by examining the effects of the NO synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME) upon (i) basal iliac artery blood flow, (ii) vasodilator responses to endothelium-dependent and -independent agonists and (iii) reactive hyperaemic responses to arterial occlusion. 2. L-NAME (0.1-3 mg min-1) infused directly into the iliac artery dose-dependently reduced basal iliac artery blood flow by a maximum of 48.6 +/- 6.9% (n = 4) and also increased mean systemic arterial blood pressure by 25.6 +/- 5.0 mmHg (n = 4) (at 3 mg min-1 L-NAME). 3. Over the same dose range, L-NAME also inhibited the peak vasodilator responses to intra-arterially administered, submaximal bolus doses of the endothelium-dependent agonists, bradykinin (3-300 ng) and acetylcholine (30-300 ng) by approximately 40%. In contrast, peak vasodilator responses to the endothelium-independent agonists, sodium azide (3-30 micrograms) and adenosine (0.3-1 mg), and peak reactive hyperaemic responses to arterial occlusion (60 s) were largely unaffected by L-NAME. 4. The dose-related effects of L-NAME on basal iliac artery blood flow, mean systemic arterial blood pressure and endothelium-dependent vasodilator responses were significantly attenuated by pretreatment with L-arginine (100 mg min-1) followed by co-infusion of L-arginine (100 mg min-1) with L-NAME. 5. In conclusion, these data suggest that NO plays some role in regulating basal blood flow and in mediating the vasodilator responses to the endothelium-dependent agonists bradykinin and acetylcholine in the skeletal muscle vasculature of the dog hindlimb. The substantial component (~60%) of the peak vasodilator responses to bradykinin and acetylcholine, unaffected by L-NAME, may be independent of NO, or be mediated by an alternative EDRF-dependent but L-NAME-insensitive mechanism.

An adult Chinese red panda ( Ailurus fulgens styani) transported by airplane from Florida to a North Dakota zoo died 1 week after arrival. Grossly, an interscapular abscess, subcutaneous inflammation, lymphadenitis, and pulmonary abscesses were observed. Microscopic findings included necrotizing inflammation in liver, lung, lymph node, and spleen. Chromobacterium violaceum was cultured from the interscapular abscess, liver, lung, and spleen and was injected into Swiss Webster mice. These mice died 18 hours postinoculation, and C. violaceum was cultured from liver, lung, and spleen. Chromobacterium violaceum is a sporadically reported but highly virulent pathogenic bacterium of both animals and humans typically found as a soil and water inhabitant of tropical and subtropical regions.

Flaxseed (Linum usitatissimum L. 'McGregor') stored at 10, 20, 30, 40, and 50 °C and 35, 50, 60, and 70% relative humidity (RH) for up to 12 mo deteriorated in quality in −1 dry seed (0.51% free fatty acids in oil) rarely increased more than 1.5-fold over 12 mo at 10 or 20 °C and up to 10% MC, or at 30 °C and 7 to 8% MC. Using FAV as a storage quality-loss criterion, flaxseed at 8–9% MC could be stored for 6 mo at 30 °C, 1–2 mo at 40 °C, or a few weeks at 50 °C with less than a 1.5-fold increase. A twofold increase in FAV was correlated to a discoloured or charred appearance of seeds and a rapid loss in seed germination. Seed germination did not decrease during 12 mo at 10 or 20 °C and 70% RH, or at 30 °C and 60% RH. The fungi Aspergillus glaucus group, A. candidus Link, and Penicillium spp. infected seed at some temperatures and relative humidities with low frequency by 6 mo, and A. flavus Link also occurred at 12 mo. Visible microflora were absent after 6 mo on seed at 40 and 50 °C. The beetles Oryzaephilus mercator (Fauvel), O. surinamensis L., Tribolium castaneum (Herbst), and T. confusum J. duVal survived and produced some larvae on both whole and ground flaxseed in 2 mo. McGregor was slightly more suitable for insect reproduction than NorMan or NorLin. Five other insect species could not survive. Extensive infestation of flaxseed by stored-product insects is unlikely. Key words: Flaxseed, storage, free fatty acids, germination, microflora, insects

Restriction endonuclease digestion of Acanthamoeba whole-cell DNA was used to study the relationship between 33 morphologically identical strains from keratitis cases (30 strains), contact lens storage containers (2 strains), and soil (1 strain). Samples digested with BglII, EcoRI, or HindIII and separated by agarose gel electrophoresis contained detectable mitochondrial DNA restriction fragment length polymorphisms (RFLPs). By comparing RFLPs, the strains could be assigned to seven multiple-strain and three single-strain groups. The largest of these contained nine strains, eight of which were isolated in keratitis cases in various locations worldwide and may indicate a group particularly associated with keratitis. Restriction endonuclease analysis of whole-cell DNA is proposed as a valuable technique for detecting mitochondrial DNA RFLPs in the differentiation of morphologically identical Acanthamoeba strains and may therefore be useful in resolving the complex taxonomy of the genus, which has hitherto been founded on subjective morphological criteria.

Three populations derived from crosses of selected resistant inbreds (061, B37HtN, and DS:74:1071) with susceptible inbred FR1141 and a population derived from a cross of B37 × B37HtN were evaluated for gray leaf spot severity in 1992 and 1993 at Urbana, IL, and Andrews, NC. Populations included the susceptible parent (P1), the resistant parent (P2), F1 and F2 generations, backcrosses BCP1 and BCP2, and, when space and seed were available, one or more of the F3, BCP1S1, and BCP2S1 generations. Plants at Urbana were inoculated, and naturally occurring disease was relied upon at Andrews. Individual plants were rated by visually estimating the percent leaf area blighted (necrotic). Generation mean analysis of data combined over years or locations indicated that a simple additive-dominance model was able to explain the inheritance of resistance for all populations. Dominance effects were detected in all population evaluated. For the FR1141 × 061 and FR1141 × B37HtN populations, dominance was significant at early ratings, but not at late ratings. Results from generation mean analysis for individual years, locations, and rating were variable.

The inheritance of resistance to Aspergillus ear rot and aflatoxin production in corn (Zea mays L.) caused by Aspergillus flavus was studied in progeny derived from crosses between the resistant corn inbred cv. Tex6 and susceptible inbred cvs. B73 and Mo17. From 1994 to 1996, plant generations included were the P1(susceptible B73 or Mo17), P2(resistant Tex6), F1, F2, F3, BCP1, BCP1-selfed, and BCP2. The BCP2-selfed generation was added in 1995 and 1996 for the B73 × Tex6 cross. Primary ears were pinboard inoculated and evaluated for Aspergillus ear rot severity. F1means deviated from the midparent value toward resistance for aflatoxin production and toward susceptibility for ear rot in both crosses. Analyses of generation means indicate that additive gene action was most important in the resistance to both ear rot and aflatoxin production in the B73 × Tex6 cross. Mo17 was somewhat resistant to both traits, so resistance from Tex6 was not well defined in this cross. Broad-sense heritabilities for ear rot and aflatoxin production were 58 and 63% for Mo17 × Tex6, and 66 and 65% for B73 × Tex6. Narrow-sense heritabilities for ear rot and aflatoxin production were 39 and 45% for B73 × Tex6. It is estimated that one cycle of selection for resistance within B73 × Tex6 F3families would reduce the percentage of ear rot severity by 8.5% and aflatoxin concentration by 19 ng/g.

The susceptible parent FR1141, the resistant parent 061, the F1 cross, and 301 families selfed once from backcrosses to the susceptible parent were evaluated for gray leaf spot (GLS) severity for two years in Urbana, IL, and one year in Andrews, NC. Linkage between ear height and GLS severity was suspected. Therefore, plant height characteristics were noted for two years in Urbana, IL. Eighty-six polymorphic probes were used to construct a random fragment length polymorphism linkage map, and the presence, locations, effects, and interactions of quantitative trait loci (QTL) associated with GLS, plant and ear height were determined. Five QTL were significantly associated with GLS resistance across all environments and rating periods. These five regions are associated with additive effects on phenotype and account for between 51.0 and 58.7% of the phenotypic variation associated with GLS severity. Additionally, six QTL were identified with maturity-dependent associations to GLS severity. Heritability of GLS resistance was estimated to be approximately 0.73. Four QTL were identified with associations to ear height relative to total plant height. One of the four was associated with higher ear height and GLS resistance.

Genetic diversity among 22 Escherichia coli strains isolated from chickens with swollen-head syndrome (SHS), an acute respiratory disease of domestic poultry, and 93 strains isolated from birds with colibacillosis was assessed on the basis of allelic variation at 20 enzyme-encoding loci detected by multilocus enzyme electrophoresis. SHS isolates from Spain and Canada were polymorphic at 14 loci and were classified into 19 multilocus genotypes, defining clones that differed on average at 34% of the loci. In most cases, SHS isolates of different clonal genotypes were distinct in O:H serotype and expressed different fimbrial antigens. Comparisons with 93 isolates obtained from birds with colibacillosis revealed enzyme polymorphisms at 17 of 20 loci, with an average of 3.5 alleles per locus. In the total sample, 56 clonal genotypes were distinguished, with 27 (23%) of the isolates belonging to one of three common clones. Both SHS and colibacillosis isolates were genetically diverse, with an average single-locus diversity of 0.36, indicating that a wide variety of naturally occurring bacterial clones is associated with these acute avian infections. Six previously defined groups of clones identified in diseased birds from the United States were represented in isolates from Spain, indicating that similar clones occur in widely separated geographic areas. In addition, one group of SHS isolates was closely related to a recognized widespread clone complex incriminated in human septicemia and meningitis. The results suggest that certain strains implicated in SHS infections belong to a clone complex whose members have special attributes that promote involvement in invasive diseases in humans and animals.

Antibiotics are used in food animal production to treat diseases and also to improve performance. Antibiotics are not used on all farms, and antibiotic resistance is occasionally found on farms that do not use antibiotics. Rendered animal protein products are often included in poultry feeds and could potentially serve as a source of antibiotic-resistant bacteria. One hundred sixty-five rendered animal protein products from cattle, poultry, and fish were aseptically collected from poultry feed mills. Fifty-five percent of the poultry meal samples had detectable levels of gram-negative bacteria ranging from 40 to 10,440 colony-forming units/g of sample. Poultry meal and meat and bone meal had the greatest number of samples with bacteria resistant to five or more antibiotics. A high percentage of feed samples (85%) contained bacteria resistant to amoxicillin, ampicillin, clavulanic acid, or cephalothin, whereas few samples contained bacteria resistant to ciprofloxacin, kanamycin, or trimethoprim/sulfamethoxazole. Acinetobacter calcoaceticus, Citrobacter freundii, and Enterobacter cloacae were the most commonly isolated antibiotic-resistant bacteria. Isolation for Salmonella was also performed, with 14% of the meat and bone meal samples containing Salmonella sp. Only one of the meat and bone meal isolates, Salmonella livingstone, was resistant to five or more antibiotics. Many of the antibiotic-resistant bacteria contained integrons, genetic elements that mediate multiple drug resistance.

Thirty-six inbred lines selected in West and Central Africa for moderate to high resistance to maize ear rot under conditions of severe natural infection were screened for resistance to aflatoxin contamination using the previously established kernel screening assay. Results showed that more than half the inbreds accumulated aflatoxins at levels as low as or lower than the resistant U.S. lines GT-MAS:gk or MI82. In 10 selected aflatoxin-resistant or aflatoxin-susceptible inbreds, Aspergillus flavus growth, which was quantified using an A. flavus transformant containing a GUS-beta-tubulin reporter gene construct, was, in general, positively related to aflatoxin accumulation. However, one aflatoxin-resistant inbred supported a relatively high level of fungal infection, whereas two susceptibles supported relatively low fungal infection. When kernels of the 10 tested lines were profiled for proteins using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, significant variations from protein profiles of U.S. lines were observed. Confirmation of resistance in promising African lines in field trials may significantly broaden the resistant germplasm base available for managing aflatoxin contamination through breeding approaches. Biochemical resistance markers different from those being identified and characterized in U.S. genotypes, such as ones inhibitory to aflatoxin biosynthesis rather than to fungal infection, may also be identified in African lines. These discoveries could significantly enhance the host resistance strategy of pyramiding different traits into agronomically useful maize germplasm to control aflatoxin contamination.

1. We have investigated the receptors mediating endothelin-induced contraction of rabbit isolated jugular vein (RJV) and rat isolated thoracic aorta (RTA). 2. Endothelin-1 (ET-1) and endothelin-3 (ET-3) contracted RJV preparations with similar potency (EC50 values approximately 1 nM), whereas, ET-1 (EC50:4.5 nM) was approximately 80 fold more potent than ET-3 in contracting RTA. In addition, the ETB receptor-selective agonist [Ala1,3,11,15]ET-1 contracted RJV (EC50:2.1 nM) but not RTA. 3. The ETA receptor antagonist, BQ123, competitively antagonized (pA2 6.93) the contraction of RTA produced by ET-1, but had no effect (at 10 microM) on the contractile effects of either ET-1, ET-3 or [Ala1,3,11,15]ET-1 in RJV. 4. These data suggest that both ETA and ETB receptors can mediate vascular smooth muscle contraction.

This study reports the presence of two fractions from corn seeds inhibitory to aflatoxin formation. Using a sensitive laboratory assay that can measure both inhibition of fungal growth and inhibition of aflatoxin biosynthesis, we examined aqueous extracts from seeds of Tex6, a corn inbred shown to be highly resistant to aflatoxin accumulation in field and laboratory evaluations. In these extracts, we identified two biologically active fractions. One inhibited growth of Aspergillus flavus and, thus, aflatoxin accumulation, and the other inhibited aflatoxin formation with little effect on fungal growth. The compounds responsible for these activities appear to be proteaceous, as they are water soluble, heat labile, and sensitive to proteinase K treatment. The compounds were partially purified by ultrafiltration and chromatography. The estimated molecular mass of the growth inhibitor is approximately 28 kDa, and that of the aflatoxin biosynthesis inhibitor appears to be greater than 100 kDa. Partially purified preparations of the growth inhibitor and aflatoxin biosynthesis inhibitor cause 50% inhibition at 26 and 75 μg of protein/ml, respectively. The presence of these compounds in Tex6 may explain its resistance to aflatoxin accumulation.

Kernels of a maize inbred that demonstrated resistance to aflatoxin production in previous studies were inoculated with an Aspergillus flavus strain containing the Escherichia coli beta-D-glucuronidase reporter gene linked to a beta-tubulin gene promoter and assessed for both fungal growth and aflatoxin accumulation. Prior to inoculation, kernels were pin-wounded through the pericarp to the endosperm, pin-wounded in the embryo region, or left unwounded. After 7 days incubation with the fungus, beta-glucuronidase activity (fungal growth) in the kernels was quantified using a fluorogenic assay and aflatoxin B content of the same kernels was analyzed. Kernels of a susceptible inbred, similarly treated, served as controls. Results indicate a positive relationship between aflatoxin levels and the amount of fungal growth. However, resistant kernels wounded through the pericarp to the endosperm before inoculation supported an increase in aflatoxin B over levels observed in nonwounded kernels, without an increase in fungal growth. Wounding kernels of the resistant inbred through the embryo resulted in both the greatest fungal growth and the highest levels of aflatoxin B1 for this genotype. Maintenance of resistance to aflatoxin B1 in endosperm-wounded kernels may be due to the action of a mechanism which limits fungal access to the kernel embryo.

Thirty-six cases of Salmonella enteritidis phage type (PT) 4 infection, mainly in children, were notified in one local authority in the two weeks beginning on 23 October 1995. Twenty-four cases and 42 controls nominated by cases were included in a case control study, which showed a significant association between illness and the consumption of marshmallow confectionery from a bakery. S. enteritidis PT4 was isolated from samples of the marshmallow, and all isolates had the same plasmid and pulsed field gel electrophoresis profiles. The marshmallow had been made using raw egg white, which shows that not all caterers follow the Department of Health's advice.

Thirty-nine Escherichia coli isolates from broiler chickens with cellulitis were serotyped and analyzed for clonal relationships by multilocus enzyme electrophoresis. The isolates were further characterized with respect to hemagglutination (HA); serum resistance; antibiotic susceptibility; production of aerobactin, colicin V, and hemolysin; expression of K1 or K5 capsule; sensitivity to cloacin DF13 after treatment with diphenylamine; expression of iron-regulated outer membrane proteins; and virulence in 1-day-old chickens. In addition, the isolates were examined for the presence of DNA sequences related to F1A (fim) and P (pap) fimbriae, aerobactin synthesis (iuc) and transport (iut), hemolysin operon hly, and TraT lipoprotein-induced serum resistance (traT). Only 38.4% of the isolates were typeable with standard O antisera, and of these, serogroups O25 and O78 were the most frequently observed. Multilocus enzyme electrophoresis, based on 20 enzymes, resolved 17 electrophoretic types, forming seven clusters. Isolates from four of these clusters fell into E. coli clone complexes that have been previously reported to be commonly associated with avian colibacillosis. All isolates expressed two to five iron-regulated outer membrane proteins, were resistant to serum and cloacin DF13, and possessed DNA sequences homologous to fim and iuc/iut. Most isolates (72%) were positive for traT, and a majority produced colicin V and aerobactin (92 and 82%, respectively). Assays for the presence of fim and pap DNA sequences, for HA, and for virulence gave variable results but suggest that cellulitis isolates may express F1A and/or other mannose-resistant HA fimbriae different from P and may be virulent in 1-day-old chickens. Our results support the hypothesis that cellulitis in broilers in many cases is caused by E. coli clones identical to other pathogenic avian E. coli strains. Certain clones may be specific to cellulitis, because 25% of the isolates tested belong to clusters not related to known clone complexes.

Seventy-two laboratory confirmed cases of Campylobacter infection were identified in people who attended a large festival in England. A case-control study was undertaken to identify the vehicle of infection. Potential risk factors included the water supply to the site, and food, bottled spring water and unpasteurised milk sold at the event. Only the consumption of unpasteurised milk showed a statistical association with having a Campylobacter infection, strongly suggesting that this was the vehicle of infection.

1. A number of putative endothelin (ET) receptor ligands were synthesized with a view to assessing their relative affinity for human recombinant ET receptors. 2. Human (h) and endothelin ETA and ETB receptor open reading frames were cloned by reverse transcription-polymerase chain reaction into the mammalian expression vector pcDNA1 and stable cell lines were created by transfection of Chinese hamster ovary cells. 3. Scatchard analyses of saturation isotherms for the specific binding of [125I]-endothelin-1 ([125I]-ET-1) to membranes, prepared from Chinese hamster ovary cells transfected with hETA or hETB receptors, yielded values for equilibrium dissociation constants (Kd) of 20.5 +/- 1.8 pM and 25.5 +/- 5.5 pM, respectively. Hill coefficients did not differ significantly from unity, suggesting binding to homogeneous, non-interacting receptor populations. 4. Pharmacological characterization of the transfected hETA and hETB receptors was undertaken by measuring the relative abilities of ETA and ETB receptor-selective peptide ligands to inhibit binding of [125I]ET-1. For interaction with hETA receptors, the relative order of potency was ET-1 > ET-3 = FR139317 = BQ123 >[Ala1,3,11,15]-ET-1 = sarafotoxin S6c (S6c). In contrast, the relative order of potency, at hETB receptors, was ET-1 = ET-3 = [Ala1,3,11,15]-ET-1 = S6c >> FR139317 = BQ123. 5. The novel non-peptide ligands, Ro 46-2005, SB 209670 and BMS 182874, were found to inhibit [125I]-ET-1 binding to human recombinant ETA and ETB receptors. At hETA receptors, the calculated pIC50 values were 6.7 (Ro 46-2005), 8.7 (SB 209670) and 5.8 (BMS 182874), while at hETB receptors, the corresponding pIC50 values were 6.8, 7.5 and

We developed an isolated working heart preparation to investigate hyperacute rejection of discordant xenografts. It is possible to correlate organ failure with the rejection process, and end points of rejection are easily identified. This unique model permits easy sampling of perfusates and examination of the rejected organ. The perfusate may be modified in ways not possible in in vivo preparations. Investigation of the discordant rabbit-to-pig combination with the technique has confirmed that hyperacute xenograft rejection can be reproduced. Rejection appears to be a complement-mediated immunologic phenomenon rather than the consequence of a nonspecific physical incompatibility. Hyperacute xenograft rejection can be prevented by depletion of C3 from the perfusing blood by treatment with cobra venom factor.

Endothelin (ET) ETA receptors on vascular smooth muscle are believed to mediate the vasoconstrictor effects of ET isopeptides, and ETB receptors on the endothelium are thought to mediate the vasodilator effects. This study has investigated the receptors mediating endothelin-induced contraction of isolated ring preparations of rat thoracic aorta (RTA) and rabbit carotid artery (RCA), pulmonary artery (RPA), and jugular vein (RJV). In RTA and RCA, ET-1 (EC50 4.5 and 5.2 nM, respectively) was 82- and 108-fold, respectively, more potent than ET-3, whereas the ETB receptor-selective agonists sarafotoxin S6c (S6c) and Ala1,3,11,15-ET-1 (4-Ala-ET-1) were without effect up toor = 1 microM. In contrast, in RPA and RJV, ET-1 (EC50 3.1 and 0.7 nM, respectively) and ET-3 (EC50 4.4 and 0.9 nM, respectively) were equipotent, and 4-Ala-ET-1 (EC50 10.7 and 2.1, respectively) and S6c (EC50 0.4 and 0.1 nM, respectively) were potent contractile agonists. The ETA receptor antagonist BQ123 (D-Val-Leu-D-Trp-D-Asp-Pro) competitively antagonized the effects of ET-1 in RTA and RCA (pA2 values 6.9 +/- 0.1 and 6.8 +/- 0.2, respectively) but did not antagonize (at 10 microM) contractions to ET-1, ET-3, or 4-Ala-ET-1 in RPA and RJV. In conclusion, contraction of vascular smooth muscle by endothelins can be mediated by both ETA and ETB receptors.

Four hundred twenty turkey and 80 chicken Escherichia coli isolates from colisepticemic birds were examined for the following properties: heat-labile toxin (LT), heat-stable enterotoxin, verotoxin, colicinogenicity, hemolysin, and hydroxamate/aerobactin production. Twenty-four (5.7%) of the 420 turkey isolates and six (7.5%) of the 80 chicken isolates produced an LT that was cytotoxic for both Vero and Y-1 cells. In contrast, 48 (11.4%) of the turkey isolates and 18 (22.5%) of the chicken isolates produced a distinct LT that was cytotoxic only for Vero cells. In addition, 64 (80.0%) of the chicken isolates and 309 (74.0%) of the turkey isolates produced aerobactin. Colicinogenicity occurred in 51 (64.0%) of the chicken isolates, with 41 (51.0%) producing colicin V. By contrast, 254 (61.0%) of the turkey isolates produced a colicin, of which 176 (42.0%) produced colicin V. None of the chicken and turkey isolates produced hemolysin or heat-stable enterotoxin.

Laboratories that reported isolations of Streptococcus sanguis from blood cultures to the Communicable Disease Surveillance Centre (CDSC) Colindale were requested to submit strains to Bath Public Health Laboratory to allow the prevalence of penicillin tolerance within different biotypes of this species to be studied. One hundred and fifty one Streptococcus spp were received from 78 United Kingdom laboratories in one year. Strains were identified using the API 20 Strep, and minimum inhibitory concentrations (MICs) of penicillin were determined using the spiral gradient plate method. Penicillin tolerance was detected by spraying beta-lactamase over inoculated gradient plates, reincubating for 48 hours and counting the number of surviving organisms represented by colonies. There were 57 different API identification profiles encountered in the survey. Most S sanguis I/1 strains were penicillin tolerant, most S sanguis II strains were non-tolerant. The overall geometric mean MIC of penicillin was considerably lower for S sanguis I/1 than for all other biotypes. The distribution of biotypes and the geometric mean MIC of penicillin for each biotype were not significantly different for infective endocarditis strains than for all strains tested, suggesting little or no association between penicillin tolerance and the seeding of endocardium. When the reactions obtained using API 20 Strep were compared with a recent taxonomic study of viridans streptococci, 22 of 38 S sanguis I/1 strains could be reclassified as S gordonii; all these strains were penicillin tolerant. Such reclassification would allow likely penicillin tolerant strains to be predicted.

Four hundred twenty turkey and 80 chicken Escherichia coli isolates from colisepticemic birds were examined for the following properties: heat-labile toxin (LT), heat-stable enterotoxin, verotoxin, colicinogenicity, hemolysin, and hydroxamate/aerobactin production. Twenty-four (5.7%) of the 420 turkey isolates and six (7.5%) of the 80 chicken isolates produced an LT that was cytotoxic for both Vero and Y-1 cells. In contrast, 48 (11.4%) of the turkey isolates and 18 (22.5%) of the chicken isolates produced a distinct LT that was cytotoxic only for Vero cells. In addition, 64 (80.0%) of the chicken isolates and 309 (74.0%) of the turkey isolates produced aerobactin. Colicinogenicity occurred in 51 (64.0%) of the chicken isolates, with 41 (51.0%) producing colicin V. By contrast, 254 (61.0%) of the turkey isolates produced a colicin, of which 176 (42.0%) produced colicin V. None of the chicken and turkey isolates produced hemolysin or heat-stable enterotoxin.

Oviposition and larval development of Tribolium castaneum (Herbst) and Cryptolestes ferrugineus (Stephens) were used as criteria of the nutritional value of 28 ground or 29 ball-milled cultivars of two-rowed barley, six-rowed barley, oat, triticale, durum and common wheat for these insects. Oviposition by individual adult T. castaneum, on 28 ground cultivars, was lowest only on Benito wheat and all oat except Terra (hulless). On 29 ball-milled cultivars, Coulter and Medora durum wheat were optimal for egg production while the least number of eggs was produced on Glenlea (wheat), TR 212 and 219 (two-rowed barley), Bonanza and Conquest (six-rowed barley) and all oat. Oviposition by C. ferrugineus on ball-milled cultivars was also optimal on durum wheat and was lowest on all oat. The pattern of egg laying for both species over three 4-d periods varied with the payability and texture of the ground and ball-milled cultivars. Rate of larval development for T. castaneum on three ball-milled oat and three durum wheat cultivars was slower on oat than on durum wheat and C. ferrugineus larvae rarely survived on oat; there were no significant differences among the cultivars of a crop. Environmental indices based on time to pupation and oviposition indicated the relative nutritive value of the various cereals and cultivars to both insect species.Key words: Oviposition, development, Ball-milled, Cereal, Tribolium castaneum, Cryptolestes ferrugineus

The effects of various seed moisture contents in hulless (cv. Terra) and hulled oats (cv. Random) on susceptibility to mite infestation and on mycofloral growth and germination loss were studied at weekly intervals. Fat acidity values were determined for Terra oats only after 4 wk of storage. Moisture content-relative humidity adsorption and desorption curves were determined for Terra at 22 °C and at relative humidities of 35–100%. Terra oats, which had a higher level of Penicillium infection at 90–100% RH than Random oats, lost viability more rapidly than Random. Fat acidity values of Terra increased rapidly from 35 mg KOH/100 g of seed to 87–118 mg KOH/100 g of seed, only when seeds were stored at 90–100% RH. Terra offered a more favorable substrate for the multiplication of the mites Tyrophagus putrescentiae, Acarus farris, and Lepidoglyphus destructor than did Random. With the exception of susceptibility to mite infestation, safe storage criteria are similar for hulled and hulless oats at usual moisture contents.

Moisture content-relative humidity (MC-RH) adsorption and desorption curves were determined for triticale (× - Triticosecale Wittmack), cv. Welsh, at 22 °C and 35–100% RH. The effects of various seed moisture contents on free fatty acid level, microfloral growth and germination loss were determined after 5 wk of storage at various RH and 22 °C. Infection of seeds by Penicillium and Aspergillus glaucus group occurred above 80–85% RH and seed germination correspondingly began to decrease. Five common stored-product mites which infested triticale stored at 20 °C and 85% RH were: Acarus siro, A. farris, Aëroglyphus robustus, Lepidoglyphus destructor and Tyrophagus putrescentiae. A. farris and L. destructor also multiplied on wheat cv. Neepawa which was an inferior substrate to triticale for A. farris.

The suitability of the API ZYM system for identifying thermophilic Naegleria species, based on enzyme presence and activity, was investigated. Replicate testing on strains of N fowleri, N lovaniensis, and N australiensis cultured in a monoxenic and an axenic medium showed that the system could provide a rapid and reproducible means of identifying the species soon after primary isolation. No single enzyme was found specific for any one species, but considerable differences were found in the patterns of activity of acid phosphatase and leucine arylamidase. When these were compared the species could be differentiated. Use of the system in conjunction with a simple culture method is proposed as a readily available means of monitoring environmental and public bathing sites to prevent primary amoebic meningoencephalitis.

Ethyl[2-(p-phenoxyphenoxy)ethyl]carbamate designated as LY 198468 (fenoxycarb), an insect growth regulator, was obtained from Elanco, Division of Eli-Lilly Canada, as a 50% EC formulation. The material was diluted in acetone and applied to plywood and galvanized steel panels (11 cm x 11 cm) with a Paasche air brush at 69 KPa pressure at rates of 0, 0.2, 0.5, 1.0, and 2.0 g (AI)/m2. Four replicate surfaces were used for each insect-surface-dosage combination. Insects used for bioassay were fouth instar larvae, pupae, and adults of Tribolium castaneum (Herbst), and adults of Cryptolestes ferrugineus (Stephens). Four replicates of 20 insects were exposed to treated and control surfaces, inside copper rings 5 cm diam and 3 cm high, for 24th at 25°C and 50% RH 1 day after treatment of the surfaces. The insects were then placed in plastic vials on wheat flour and brewers yeast (19:1, w:w) T. castaneum) or whole wheat + wheat germ (19:1, w:w) C. ferrugineus) and held at 30±1°C and 60±5% RH. Mortality was determined at 1 and 2 wk for the exposed immatures of T. castaneum and 1, 2 and 4 wk for the exposed adults of both species. Numbers of larvae produced by the exposed adults were observed at 4 wk. Following removal of the insects from the treated surfaces, wheat + wheat germ (19:1, w:w) was placed in the copper rings to a depth of 2 cm to simulate grain residues in empty granaries. Four replicates of 20 adult insects of each species were then placed in the grain and the numbers of adults and immatures present after 5 wk of storage at 25±2°C and 50 ±10% RH noted.

A rapid and inexpensive method has been developed for the analysis of zearalenone and zearalenol in grains and animal feeds. The method involves extraction with 75% methanol, precipitation of pigments with lead acetate, and defatting with petroleum ether. The mycotoxins are subsequently partitioned into toluene–ethyl acetate, chromatographed on high performance thin layer chromatographic plates, and detected after treatment with Fast Violet B salt solution. Sensitivity of the method is better than 80 ng/g for zearalenone and 200 ng/g for zearalenol. Ten samples can be completed in less than 2 h. The method is applicable for zearalenone in corn, wheat, barley, millet, and swine feeds.

Energy availability above various temperatures is important and productivity must be considered with energy availability for effective control.

A Bacillus thuringiensis var. thuringiensis (Bt) Berliner formulation, designated SAN 410 and containing a beta exotoxin (1% AI), was obtained from Sandoz, Zoecon Corp. Cracked wheat at 16.0% moisture content was treated with various concentrations of the insecticide. Five replicates of 20 adult Oryzaephilus surinamensis, O. mercator, Cryptolestes ferrugineus, and Tribolium castaneum were exposed to the medium treated with 0, 500, or 1000 ppm (AI) for 2 wk at 25 ± 1°C, 70 ± 5% RH. Mortality was assessed at 1 and 2 wk. Five replicates of 20 late-stage larvae of O. surinamensis, O. mercator, and C. ferrugineus were exposed to cracked wheat treated with 0, 5, 20, 50, or 200 ppm B. thuringiensis for 2 wk at 25 ± 1°C and 70 ± 5% RH. Mortality was assessed at 1 and 2 wk.

Wheat flour was treated by pipette with 3 insecticides in acetone to yield 0.1, 0.5, 1.0, 2.0, and 5.0 ppm. A layer of flour 3-mm deep was placed in the bottom of a 387-ml-capacity glass bottle, with 3 replicate bottles/treatment, then hard red spring wheat was added to a depth of 8 cm. The bottles were sealed with ventilated lids. Twenty-five adults, 12 females and 13 males less than 2 wk old, were placed in each bottle and held at 25 ± 1°C, 70 ± 5%RH for 4, 8, or 12 wk, when adults and immatures were counted. Controls were as above, except untreated flour (acetone only), was substituted for the treated flour under the wheat. Three controls were run for each sampling period. Data were analyzed separately for numbers of adults and immatures on each sampling date by ANOVA and DMRT.