Amelioration of aluminum toxicity to sorghum seedlings by chelating agents

At the pH levels found in acid soils (4.5 to 5.5), theoretical equilibrium models predict that Al will be complexed on a nearly one to one molar basis by NTA, EGTA. oxalate (OX) and citrate (CIT). Growth chamber experiments were initiated using solutions containing Al (0, 2, or 10 μM), Ca (400 μ.M). and a chelate (0 or 10 μM) growing sorghum [Sorghum bicolor (L.) Moench cv. AT×399 × RT×430] for four days following germination to test the equilibrium models. The pH and concentration of Al in the solutions were measured before and after each experiment. Plant root length and weight, and shoot weights were used as a bioassay for the uncomplexed, toxic Al. Root length showed the greatest response to aluminum and chelate treatments, although root weight and shoot weight gave the same general results. Chelate effectiveness in reducing Al toxicity was NTA > OX = CIT > EGTA. The pH values were altered very little by NTA or EGTA and averaged 5.2 to 5.3; however, the pH was raised 0.2 to 0.9 units by OX and CIT. Thus, some detoxifying effect from the latter two could be a pH effect. No chelate effect was evident at pH values near 6 for CIT, but the chelate was effective in reducing Al toxicity at pH 5.6, indicating the importance of pH in Al toxicity. NTA alone did not affect root length, but the other chelates all decreased root length to a small degree at 0 μM Al indicating that the chelate itself was detrimental to growth. It was concluded that NTA was an effective chelate to detoxify Al and EGTA was not. Also it was found that OX and CIT behave quite differently from NTA and EGTA in that they affect pH and lower solution Al concentration. The method did not confirm the equilibrium models for EGTA, OX, or CIT because of complicating factors such as pH variation and damage to the roots by the chelates. The equilibrium model for NTA, though, was confirmed.     

Antioxidant properties of bran extracts from "Akron" wheat grown at different locations

Bran extracts of Akron wheat grown at four nonirrigated and one irrigated testing locations were examined and compared for their free radical scavenging properties against the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH(*)) and the radical cation ABTS(*)(+), chelating capacities, and total phenolic content (TPC) to determine the potential effects of environmental factors on the antioxidant properties of hard winter wheat. The environmental factors included total solar radiation, average daily solar radiation, and number of hours exceeding 32 degrees C. The results showed that bran samples from different growing locations may significantly differ in their radical scavenging activities against both DPPH(*) and ABTS(*)(+), chelating capacities, and TPC. A significant negative correlation was detected between the chelating activities of the bran samples from the four nonirrigated locations and total solar or daily average solar radiation (r = -0.999 and P = 0.001). These data suggest potential influences of growing conditions on the antioxidant properties of hard winter wheat and the possibility of producing wheat that is strong in a selected antioxidant property by optimizing the growing conditions of a selected wheat variety. More research is required to further investigate the relationship among antioxidant properties and environmental factors using different wheat varieties and larger sample sizes.     

The process of antagonism of Sclerotium cepivorum in white rot affected onion roots by Trichoderma koningii

Trichoderma koningii (strain Tr5) grew in the epidermal mucilage of onion roots without entering healthy epidermal tissue. When placed on the epidermis of Sclerotium cepivorum -infected roots, T. koningii colonized epidermal passage cells, with little colonization of other epidermal tissues, then branched and spread throughout the root cortical tissues damaged by enzymes and toxins which diffused ahead of S. cepivorum hyphae, and impeded the path of the infection. When T. koningii colonized infected tissue, many S. cepivorum hyphae became detached at septa, cell walls dissolved and many hyphal apices burst. Contact between hyphae was not necessary for lysis to occur. T. koningii produced two endochitinases ( R _f 0·15 and 0·24) and two exo-acting chitinolytic enzymes ( R _f 0·46 and 0·62) during degradation of crabshell chitin and S. cepivorum cell walls. The R f 0·24 and 0·46 proteins were detected when T. koningii colonized S. cepivorum -infected roots and are likely to be a component of the antagonism process.     

The role of altered uterine-embryo synchrony on conceptus growth in the pig

This study was conducted to determine whether inducing an embryo-uterine asynchrony during the preimplantation period would alter fetal and(or) placental size at term. Yorkshire gilts (n = 24) were checked twice daily for estrus and bred to a Yorkshire boar 24 h after the first exhibition of estrus. Embryos (1 to 4 cells) were flushed from the oviducts of each donor gilt on d 2.5 of gestation and transferred in equal numbers to the oviducts of a recipient gilt on d 1.5, 2.5, or 3.5 of the estrous cycle. Gilts were slaughtered on d 112 of gestation (calculated on the age of the conceptus) and fetal and placental weight, placental surface area, and implantation site lengths were determined. Although litter sizes were similar (9.1+/-0.9), conceptuses transferred to d 3.5 recipients became heavier fetuses (1.44+/-0.05 vs 1.23+/-0.04 kg, P < 0.001), with larger placental surface areas (1,793+/-60 vs 1,459+/-43 cm2, P < 0.01), and longer implantation sites (32.1+/-1.5 vs 24.9+/-0.6 cm, P < 0.001) than those transferred to recipients on d 2.5. These data demonstrate that oviductal transfer of embryos into a reproductive tract that is more advanced by as little as 24 h can result in alterations in placental growth and function during gestation.     

Arthrodesis of the equine proximal interphalangeal joint: a biomechanical comparison of three 4.5-mm and two 5.5-mm cortical screws

OBJECTIVE--To compare the biomechanical characteristics and mode of failure of 2 parallel-screw techniques for proximal interphalangeal joint arthrodesis in horses. STUDY DESIGN--Randomized block design, blocking for horse (1-5), method of screw fixation (three 4.5-mm vs two 5.5-mm), side (left limb vs right limb), and end (front limb vs hind limb). Constructs were loaded to failure in 3-point bending in a dorsal-to-palmar (plantar) direction. SAMPLE POPULATION--Twenty limbs (10 limb pairs) from 5 equine cadavers. METHODS--A combined aiming device was used to facilitate consistent screw placement. Three parallel 4.5-mm cortical screws were placed in lag fashion in 1 limb of a pair, and 2 parallel 5.5-mm cortical screws were placed in lag fashion in the contralateral limb. Arthrodesis constructs were tested in 3-point bending in a dorsal-to-palmar (plantar) direction using a materials-testing machine. Loading rate was 19 mm/s. Maximal bending moment at failure and composite stiffness were obtained from bending moment-angular deformation curves. Data were analyzed using ANOVA and chi(2) analysis. RESULTS--There were no significant differences in bending moment (P >.05, power = 0.8 @ delta = 19%) or composite stiffness (P >.05, power = 0.8 @ delta = 19%) between the 2 fixation techniques. Higher maximal bending moment was found in front limbs than hind limbs, and front limbs with two 5.5-mm screws than hind limbs with two 5.5-mm screws. In all cases, constructs completely failed. A greater number of 4.5-mm cortical screws failed than 5.5-mm cortical screws. CONCLUSIONS-In pastern arthrodesis constructs loaded in 3-point bending, end (front limb vs hind limb) affected maximal bending moment at failure of constructs. There was no significant effect of horse, treatment, or side on maximal bending moment or stiffness. Two 5.5-mm cortical screws should provide a surgically simpler pastern arthrodesis than three 4.5-mm cortical screws while maintaining similar biomechanical characteristics. CLINICAL RELEVANCE--Three 4.5-mm screws or two 5.5-mm screws will provide similar biomechanical characteristics in bending when performing equine pastern arthrodesis.     

Natural infection of a horse with Fascioloides magna.

A 25-year-old Quarterhorse mare was euthanized for a variety of medical reasons. At necropsy, 7 liver flukes, identified as Fascioloides magna, were recovered from the liver. This is the first report of F. magna in a horse.     

Effect of GRAS compounds on mycelial growth, pectic enzyme activity and disease severity of postharvest pathogens on rambutan (Nephelium lappaceum)

The GRAS compounds cinnamaldehyde (at 30 ppm), acetaldehyde (at 70 ppm), benzalde-hyde (at 50 ppm) and potassium metabisulphite (at 250 ppm) either completely inhibited or significantly reduced thein vitro mycelial growth ofGliocephalotrichum microchlamydosponim,Colletotrichum gloeosporioides andBotryodiplodia theobromae, the causative fungi of brown spot, anthracnose and stem end rot, respectively, of rambutan fruits,Nephelium lappaceum. The four compounds also significantly reduced the severity of all three diseases and the activity of pectic lyase and polygalacturonase enzymes secreted by the three fungi.     

Evaluation of temporal and spatial clustering of horses with Corynebacterium pseudotuberculosis infection

OBJECTIVE: To determine whether horses with Corynebacterium pseudotuberculosis infections that were examined at a veterinary medical teaching hospital between July 1, 1992, and June 30, 1994 had patterns of temporal or spatial clustering. ANIMALS: 134 case and 800 control horses randomly selected from all non-case horses admitted during the study period. PROCEDURES: Admission date and geographic location were determined. Scan, Cuzick & Edwards', and Knox tests were applied to determine whether case horses had patterns of temporal or spatial clustering. RESULTS: For all windows > or = 3 days (134 case horses) and > or = 7 days (subset of 69 case horses), results of the Scan test were significant. Results of Cuzick & Edwards' test were significant for all data sets. A significant spatial cluster of case horses was observed for October, November, and December 1992. Results of the Knox test were significant for temporal intervals between 7 and 56 days and spatial intervals between 4.3 and 6.5 km. Higher Knox(x) proportions were observed for temporal intervals of 0 to 7, 8 to 14, 22 to 28, and 29 to 35 days. CONCLUSIONS: Significant spatial and temporal clustering of horses with C pseudotuberculosis infection was detected. CLINICAL RELEVANCE: Analysis of the results strongly indicates that this disease is directly or indirectly (ie, short distance and time) transmitted. In addition, data analyses indicated an incubation period of 3 to 4 weeks. The disease could be transmitted through horse-to-horse contact or from infected to susceptible horses via insects, other vectors, or contaminated soil.     

Comparison of models to estimate genetic effects of weaning weight of Angus cattle

Weaning weights from nine sets of Angus field data from three regions of the United States were analyzed. Six animal models were used to compare two approaches to account for an environmental dam-offspring covariance and to investigate the effects of sire x herd-year interaction on the genetic parameters. Model 1 included random direct and maternal genetic, maternal permanent environmental, and residual effects. Age at weaning was a covariate. Other fixed effects were age of dam and a herd-year-management-sex combination. Possible influence of a dam's phenotype on her daughter's maternal ability was modeled by including a regression on maternal phenotype (fm) (Model 3) or by fitting grandmaternal genetic and grandmaternal permanent environmental effects (Model 5). Models 2, 4, and 6 were based on Models 1, 3, and 5, respectively, and additionally included sire x herd-year (SH) interaction effects. With Model 3, estimates of fm ranged from -.003 to .014, and (co)variance estimates were similar to those from Model 1. With Model 5, grandmaternal heritability estimates ranged from .02 to .07. Estimates of maternal heritability and direct-maternal correlation (r(am)) increased compared with Model 1. With models including SH, estimates of the fraction of phenotypic variance due to SH interaction effects were from .02 to .10. Estimates of direct and maternal heritability were smaller and estimates of r(am) were greater than with models without SH interaction effects. Likelihood values showed that SH interaction effects were more important than fm and grandmaternal effects. The comparisons of models suggest that r(am) may be biased downward if SH interaction and(or) grandmaternal effects are not included in models for weaning weight.