Performance assessment and validation of a paramagnetic particle-based enzyme-linked immunosorbent assay for chlorpyrifos in agricultural runoff waters

A commercial magnetic particle-based enzyme-linked immunosorbent assay (ELISA) kit for the insecticide chlorpyrifos [O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl) phosphorothioate] was evaluated for its specificity, precision, and accuracy, its susceptibility to matrix interferences in agricultural and environmental surface waters, and its comparability to a gas chromatographic/flame photometric (GC/FPD) method for the determination of organophosphorus pesticides in natural waters. Repeatability, reproducibility, and accuracy studies show that the kit satisfies current U.S. Environmental Protection Agency criteria for the assessment of analytical methods. Observable matrix effects were found to be present in all of the environmental test waters, with the slopes of calibration curves generated in each of the test matrices deviating from that of the control matrix by as much as 16%. Specificity studies indicate that the chlorpyrifos polyclonal antibody adequately differentiates the target compound from other structurally similar organophosphorus pesticides, with the exception of its methyl analogue. Cross-reactivity with chlorpyrifos-methyl was approximately 37%, while reactivity with diazinon, pyridaphenthion, diclofenthion, bromiphos-ethyl, bromiphos-methyl, pirimiphos-ethyl, and chlorpyrifos oxon ranged from 1.6 to 10.7%. Cross-reactivity with pirimiphos-methyl, 3,5,6-trichloro-2-pyridinol, diethyl phosphate, and diethyl thiophosphate was negligible (<1%). Validation of the paramagnetic particle ELISA format was accomplished using water samples from two monitoring studies that were collected, split, and analyzed directly by ELISA and by GC/FPD. Results of the two analytical methods were then compared using standard t tests, regression analysis, and differences against mean measurement (bias) plots. While the agreement between the two methods was determined to be satisfactory, ELISA exhibits consistent positive bias in environmental matrices. Several preanalysis mitigation steps were suggested that may help moderate bias, but additional study is recommended to explicate the exact factors responsible for its consistent overestimation of results.     

Replicative and cytopathic potential of HTLV-III/LAV with sor gene deletions

The genome of the human T-lymphotropic virus type III (HTLV-III/LAV) has the potential to encode at least three polypeptides in addition to those encoded by the gag, pol, and env genes. In this study, the product of the sor (short open reading frame) region, which overlaps the 3' end of the pol gene, was found to be a protein with a molecular weight of 23,000. An assay was developed for testing the ability of cloned HTLV-III proviruses to produce viruses cytopathic for T4+ lymphocytes. In the cell line used, C8166, neither the HTLV-III sor gene product nor the complete 3'-orf gene product were necessary for the replication or cytopathic effects of the HTLV-III.     

Feeding deterrents from Dictamnus dasycarpus Turcz against two stored-product insects

The screening for insecticidal principles from several Chinese medicinal herbs showed that the root bark of Dictamnus dasycarpus possessed significant feeding deterrence against two stored-product insects (Tribolium castaneum and Sitophilus zeamais). From the methanol extract, two feeding deterrents were isolated by bioassay-guided fractionation. The compounds were identified as fraxinellone and dictamnine from their spectroscopic data. Fraxinellone was demonstrated to possess feeding deterrent activity against adults and larvae of T. castaneum as well as S. zeamais adults with EC50 values of 36.4, 29.1, and 71.2 ppm, respectively. Dictamnine was shown to have feeding deterrent activity against adults and larvae of T. castaneum as well as S. zeamais adults with EC50 values of 57.6, 47.9, and 91.7 ppm, respectively.     

棕仁粕基础营养分析及其在尼罗罗非鱼养殖中的应用研究

本文对比研究了棕仁粕、豆柏、花生粕的基础营养及体外胃蛋白酶消化性,通过在实验饲料中添加2％、6％、10％的棕仁粕制备了四份等氮等能的饲料,初步评价了添加棕仁粕对罗非鱼生长、体组分以及血清学参数的影响.结果表明:棕仁柏作为蛋白水平相对略低,纤维含量较高的植物蛋白替代源,其体外胃蛋白酶消化率与豆粕和花生粕无明显差异,可以作为膳食饲料组分适量的添加到水产动物饲料中,而不会影响罗非鱼的正常生长;在罗非鱼养殖实验中,添加2％棕仁粕的饲料组,罗非鱼的增重率,饲料系数,蛋白利用率、鱼体的蛋白组分以及血清学参数与对照组相比无显著差异(P＞0.05),添加至6％～10％后,罗飞鱼的生长表现开始下降,饲料系数开始上升,鱼体蛋白组分下降(P＜0.05).作为棕仁粕在水产养殖领域的初步探索性应用研究,研究认为棕仁粕是可以用于水产饲料的成分使用的,添加比例不宜超过6％.     

Distribution and partial characterisation of acid hydrolysable organic nitrogen in six New Zealand soils

Six New Zealand topsoils of widely different origins and properties were subjected to 6m HC1 hydrolysis and the distribution of N fractions and amino acids were determined qualitatively and quantitatively.Of the total-N in the soils studied 83–91%, was hydrolysable with 6m HCl. The largest proportion of the hydrolysable N was α-amino acid N (38– 42%). followed by hydrolysable-unknown N (HUN) (14–24%), and NH₄⁺-N (14–22%). A significant proportion (25–50%) of the HUN fraction was accounted for by the non α-amino acid-N. Oxidative (3% H₂O₂) hydrolysis released N-phenoxy amino acid-N and possibly N-compounds which were complexed with phenols and sugars. All soils had a similar amino-acid composition with a predominance of acidic amino-acids.