Fungicidal activity of beta-thujaplicin analogues

The fungicidal activity of analogues of beta-thujaplicin, a natural product responsible for the durability of heartwood of several cupressaceous trees, was investigated in vitro on the growth of different white and brown rot fungi involved in wood biodegradation, Coriolus versicolor, Phanerochaete chrysosporium, Poria placenta and Gloephyllum trabeum. The study shows that 2-hydroxycyclohepta-2,4,6-trienone (tropolone), easily prepared according to a literature procedure, possesses interesting fungicidal activity when compared to beta-thujaplicin, azaconazole, tebuconazole and copper oxine, which suggests this compound should be examined further as a potential biocide for wood preservation.     

Adjustment of soil-surface pH and comparison with conventional fungicide treatments for control of lettuce drop (Sclerotinia minor)

The use of soil-surface applications of finely powdered calcium hydroxide (Ca(OH)₂) to inhibit Sclerotinia minor sclerotial germination and infection at the collar region of lettuce plants is described. In the laboratory, a pH > 8·0 reduced sclerotial germination of the three S. minor isolates tested. In the glasshouse, surface applications of 2–10 t Ca(OH)₂ ha⁻¹ raised the pH of the top 1–2 cm of a duplex sandy loam soil above 8·5 for at least 8 weeks without affecting soil pH within the transplant root zone. There was a linear relationship between the rate of Ca(OH)₂ applied and disease control, with complete disease suppression at 10 t Ca(OH)₂ ha⁻¹. In field trials on two soil types (duplex sandy loam, pH 6·0; and red ferrosol, pH 6·9), a rate of 2·5 t Ca(OH)₂ ha⁻¹, maintained soil-surface pH above 8·5 for 1–3 weeks and provided up to 58% reduction in lettuce drop. Application of polyvinyl alcohol (a soil-conditioning polymer) over the Ca(OH)₂ layer appeared to reduce Ca(OH)₂ loss by wind, but did not improve retention of raised soil-surface pH or disease suppression. Ca(OH)₂ treatment gave similar disease control to the industry standard treatment of a procymidone-based fungicide seedling drench. A combined treatment of Ca(OH)₂ and fungicide drench gave greater control than either individual treatment, and equivalent control to fungicide drench and three procymidone foliar sprays, offering integrated management options. The use of soil-surface-applied Ca(OH)₂ with fungicides, rotation and drip irrigation offers an opportunity for enhanced and sustainable control of lettuce drop.     

小剂量砷化物对实验兔生长和繁殖性能的影响

为研究As2O3对实验兔生长和繁殖性能的影响,选择年龄和体重相近的40只实验兔(32只母兔,8只公兔)随机分成4组.对照组饲喂不含As2O3的基础日粮,试验Ⅰ组、试验Ⅱ组和试验Ⅲ组分别饲喂含As2O3 0.5mg/kg、1.0mg/kg和1.5mg/kg的日粮.生长发育和繁殖性能的测定结果显示,试验Ⅰ组与对照组相比,差异不显著(P＞0.05),试验Ⅱ组性能表现优于对照组,差异显著(P＜0.05),试验Ⅲ组出现中毒症状.本实验表明,适量的As2O3对实验兔生长和繁殖具有促进作用.     

流感病毒M2基因变异与盐酸金刚烷胺耐药性的关系

盐酸金刚烷胺是治疗流感的常用药物,但流感病毒极易产生耐药性并发生变异.本文仅就使用盐酸金刚烷胺后流感病毒M2基因的变异情况作一综述.     

HPLC法测定盐酸氨丙啉的含量及对杂质2-甲基吡啶进行检查

采用高效液相色谱法测定盐酸氨丙啉的含量及对杂质2-甲基吡啶进行检查.用Waters XTerraTM RP C18色谱柱,以乙腈-甲醇-庚烷磺酸钠溶液(将12 g的1-庚烷磺酸钠溶于1000 mL水中,加24mL冰醋酸,6 mL的三乙胺制得)(5:35:60)为流动相,用紫外检测器于254nm处检测,柱温30℃,流速1.0 mL/min.在该条件下盐酸氨丙啉和2-甲基吡啶的分离度很好,盐酸氨丙啉浓度在0.05～0.50 mg/mL范围内,其色谱峰面积与浓度呈良好的线性关系,回归方程为y=3.07×107x-3.90×104,r=0.999 9,RSD=0.76%.该法适用于盐酸氨丙啉原料药的质量控制.     

Pain management in horses and farm animals

Objective: This review discusses the different analgesic drugs and routes of administration used in large animals for acute pain management. General guidelines and doses are given to assist in choosing techniques that provide effective analgesia. Etiology: Noxious stimuli are perceived, recognized, and localized by specialized sensory systems located at spinal and supraspinal levels. Diagnosis: Localizing the source of the noxious stimulus as well as understanding the behavioral aspects and physiological changes that result from such insult is important to adequately diagnose and treat pain. Pain assessment is far from being definite and objective; not only are there species differences, but also individual variation. In addition, the behavioral and physiological manifestations vary with the acute or chronic nature of pain. Therapy: Pain management should include (1) selecting drugs that better control the type of pain elicited by the insult; (2) selecting techniques of analgesic drug administration that act on pathways or anatomical locations where the nociceptive information is being processed or originating from; (3) combining analgesic drugs that act on different pain pathways; and (4) provide the best possible comfort for the animal. Prognosis: Providing pain relief improves the animal's well being and outcome; however, interpreting and diagnosing pain remains difficult. Continuing research in pain management will contribute to the evaluation of the pathophysiology of pain, pain assessment, and newer analgesic drugs and techniques.     

Phylogenetic Analysis of Sugarcane Rusts Based on Sequences of ITS, 5.8 S rDNA and D1/D2 Regions of LSU rDNA

Phylogenetic analysis of sugarcane rusts based on sequences of ITS and the 5.8 S rDNA revealed two highly divergent ITS groups among isolates of Puccinia sp. sensu Muta, 1987 and P. kuehnii specimens. Although there is sufficient divergence (exceeding normal intraspecific variation) between the ITS regions of the two groups to support separation into different species, unusually high homology of the ITS group I sequences with those of members of Cronartium and identical sequences of the D1/D2 regions of the LSU rDNA for all the isolates of “Puccinia sp.” and P. kuehnii that otherwise exhibited different ITS sequences, suggest that the two highly divergent sequences may have resulted from abnormal genetic events leading to non-orthologous, intraspeciflc polymorphisms. The other sugarcane rust, P. melanocephala and the grass rusts, P. miscanthi and P. rufipes, were separated from “Puccinia sp.” and P. kuehnii and from each other in D1/D2 region analyses, indicating that D1/D2 region sequences may more correctly reflect phylogenetic relationships in these rusts than do the ITS regions. Further studies to examine differences in patho-genicity or finer morphological features within P. kuehnii that may be correlated with the high divergence in ITS sequences and experiments to determine if these two sequence types represent intraspeciflc polymorphism are necessary. Received 11 October 2000/ Accepted in revised form 24 November 2000     

Cutting weeds with a CO2 laser

Stems of Chenopodium album . and Sinapis arvensis . and leaves of Lolium perenne . were cut with a CO₂ laser or with a pair of scissors. Treatments were carried out on greenhouse-grown pot plants at three different growth stages and at two heights. Plant dry matter was measured 2 to 5 weeks after treatment. The relationship between dry weight and laser energy was analysed using a non-linear dose–response regression model. The regression parameters differed significantly between the weed species. At all growth stages and heights S. arvensis was more difficult to cut with a CO₂ laser than C. album . When stems were cut below the meristems, 0.9 and 2.3 J mm⁻¹ of CO₂ laser energy dose was sufficient to reduce by 90% the biomass of C. album and S. arvensis respectively. Regrowth appeared when dicotyledonous plant stems were cut above meristems, indicating that it is important to cut close to the soil surface to obtain a significant effect. When cutting L. perenne plants with 2-true leaves at a height of 2 cm from the soil surface with a laser, the biomass decreased significantly compared with plants cut by scissors, indicating a delay in regrowth. This delay was not observed for the dicotyledonous plants nor for the other growth stages of L. perenne .     

超临界流体萃取技术在农药残留分析中的应用进展

从萃取过程控制的角度，综述了近几年来国外超临界流体技术不同形态的基体的农药残留分析中的应用情况、研究现状及前景。