Enzyme-linked immunosorbent assay for the detection of yessotoxin and its analogues

Polyclonal antibodies were produced for the development of competitive enzyme-linked immunoassays for use in quantifying yessotoxins in shellfish, algal cells, and culture supernatants. Immunizing and plate coating antigens were prepared by derivatization of yessotoxin either by ozonolysis or bromination and conjugation to proteins. Two assays that were the most sensitive for yessotoxin were optimized and characterized. Cross-reactivity studies indicated that the antibodies raised have broad specificity and that binding to analogues was strongly affected by changes to the A-ring and, to a lesser extent, the K-ring regions of the toxin molecule. ELISA provides a sensitive and rapid analytical method that is suitable for screening large numbers of samples and detects all the yessotoxin analogues that the European Commission currently requires shellfish to be tested for. The assay limit of quantitation for yessotoxin in whole shellfish flesh is 75 microg/kg; therefore, assay sensitivity is sufficient to measure toxin levels well below the maximum permitted level set by the European Commission. The antibodies produced can be used in additional applications such as the immunolocalization of yessotoxins in shellfish and preparation of immunoaffinity columns.     

Canine nasal septum deviation can be a normal variation and correlates with increasing skull indices

Nasal septal deviation has been studied in relation to nasal pathology and mass effect in dogs. The purpose of this retrospective, cross‐sectional study was to compare the prevalence of nasal septal deviation in dogs with rhinitis, neoplasia, and those without nasal pathology based on the facial index, skull index, and cranial index. Computed tomographic studies of the nasal cavities of dogs performed over a 5‐year period were retrospectively reviewed. This study had 233 dogs meeting the inclusion criteria with 135 dogs with no nasal pathology, 63 dogs with nasal neoplasia, and 35 dogs with rhinitis. The prevalence of nasal septal deviation, the angle, maximum distance, and longitudinal extent of deviation were recorded, as well as measurements to calculate the facial index, cranial index, and skull index. The results showed no difference in the prevalence of nasal septal deviation between dogs with nasal pathology and those without. The mean longitudinal extent of deviation and maximum distance of deviation was statistically greater for those with neoplasia compared to those with rhinitis and without nasal pathology. The longitudinal extent of deviation was inversely proportional to the cranial index, facial index, and skull index. The angle of deviation was directly proportional to the facial index and skull index. In conclusion, nasal septal deviation is an anatomic variant in different breeds of dogs with no predilection based on nasal pathology. Nasal septal deviation should be interpreted cautiously in the assessment of canine nasal disease.     

Constitution of stable artificial oil bodies with triacylglycerol, phospholipid, and caleosin

Seed oil bodies are lipid storage organelles of 0.5-2 microm in diameter and comprise a triacylglycerol matrix shielded by a monolayer of phospholipids and proteins. These proteins include abundant structural proteins, oleosins, and at least two minor proteins termed caleosin and steroleosin. This study examined if artificial oil bodies (AOBs) composed of triacylglycerol and phospholipid could be stabilized by oleosin, caleosin, or steroleosin. Our results showed that stabilization effects could be realized by oleosin or caleosin but not by steroleosin. The sizes of the AOBs constituted with oleosin (0.5-2 microm) or caleosin (50-200 nm) were similar to or 10 times smaller than those of the native oil bodies. Recombinant caleosin expressed in Escherichia coli also encapsulated AOBs with a size, topology, and stability comparable to those encapsulated with native caleosin. A proteinase K digestion indicated that caleosin anchored the AOBs via its central hydrophobic domain of approximately 4 kDa. Isoelectrofocusing revealed that the isoelectric point of the caleosin-stabilized AOBs was pH 4.0. Aggregation of AOBs was observed at a pH lower than 4.5; thus, their stability and integrity were presumably contributed by surface caleosin via electronegative repulsion and steric hindrance. The caleosin-stabilized AOBs were thermostable up to 70 degrees C and potentially useful for biotechnological applications.     

Effect of management practices and cropping systems on earthworm abundance and microbial activity in Sanborn Field: a 115-year-old agricultural field

Sanborn Field, an agricultural demonstration field at the University of Missouri-Columbia, has over 100 years of cropping histories and management practices implemented at this site. We examined the effect of these cropping systems and management practices on earthworm populations and microbial activity. A field experiment was conducted to characterize and quantify earthworms and to determine the microbial activity in the same selected plots. We sampled 14 plots at the site, six of which were the original plots established in 1888 with the same cropping histories and management, and eight of which had been modified over the years to accommodate changing farmer needs and scientific questions. Earthworms and soil samples were collected in the spring and fall of 1999. Aporrectodea trapezoides, Aporrectodea caliginosa, and Lumbricus terrestris were the dominant species found in this field. Lumbricus terrestris was commonly associated with the no-tillage plot at Sanborn Field. Due partly to soil moisture conditions, most of the species were found and identified during the spring. Microbial activity, as expected, was greatest during the spring. Manure, no-tillage and crop rotations that include legumes had the greatest earthworm abundance and microbial activity. In general, where no fertility treatments were added to soil or where food sources were lacking, earthworm abundance decreased significantly. The abundance of earthworms found in this field reflected the cropping history and management practices used recently and within the last 100 years. In most cases, microbial activity showed similar trends as earthworm density. However, some dynamic microbial transformations, like nitrification, do not always follow the same trend as potential soil quality biotic indicators. Earthworms, along with microbial activity, may serve as useful soil quality indicators in sustained and short-term field trials.     

Determination of nabam fungicide in crops by liquid chromatography with postcolumn reaction detection

The ethylenebisdithiocarbamate (EBDC) fungicide, nabam, was determined in several crop matrixes using liquid chromatography with postcolumn reaction detection. After separation by micellar liquid chromatography, nabam (EBDC sodium salt) was acid hydrolyzed to ethylenediamine and fluorigenically labeled with o-phthalaldehyde-mercaptoethanol (OPA-MERC). Standard curves were linear from the detection limit of ca 1 ng to 1000 ng. Nabam was recovered in high yield (89 plus or minus 7.7%) over a range of concentrations (0.1 to 20 ppm) from fortified samples of papaya, lettuce, cucumber, spinach, and applesauce using a simple extraction method. Efforts to convert the more popular EBDC fungicides, maneb and mancozeb, to nabam are discussed.     

Determination of zearalenone in cornflakes and other corn-based foods by thin layer chromatography, high pressure liquid chromatography, and gas-liquid chromatography/high resolution mass spectrometry

A simple cleanup procedure based on pH adjustments was used to obtain extracts of corn foods. The method gave good recoveries of zearalenone determined by thin layer chromatography (TLC) and high pressure liquid chromatography (HPLC). As little as 5 ng zearalenone was detected by TLC, using Fast Violet B Salt as the spray reagent; the lower limit of detection in cornflakes was about 20 microgram/kg. With HPLC on Spherisorb silica (5 micrometer) and detection by fluorescence at an excitation maximum of 310 nm as little as 5 microgram zearalenone/kg cornflakes could be determined. While the TLC method was also applicable to corn chips, cornmeal, popcorn, and frozen corn, an interference was observed in HPLC of the latter 3 products. This interference was separated from zearalenone by adding a second HPLC analytical column (Spherisorb ODS). Gas-liquid chromatography coupled with mass spectrometric single ion monitoring at high resolution, although of limited availability, was shown to be the most sensitive and selective method for determining zearalenone in corn foods. The natural occurrence of zearalenone in a sample of cornflakes (13-20 microgram/kg) was demonstrated by all 3 detection procedures.     

饲料卫生和家禽健康

每年，仅仅肉鸡就合消耗一亿吨以上的成品饲料。饲料产品中一小部分受到污染就会使养鸡者和消费者付出高昂的代价。污染的饲料是不卫生的，不适合用于饲喂畜禽，因为这样的饲料合危害育禽的生产性能参数，比如健康、体重、饲料转化率、死亡率以及蛋鸡和种鸡的产蛋率。