桑叶农药残留的酶抑制速测与生物检测比较

采用家蚕生物毒性测定方法验证CL-B Ⅲ残留农药测定仪检测桑叶农药残留,建立了两种方法对十余种常用有机磷和氨基甲酸酯类农药的对应关系。结果表明：随着桑叶添毒时间的延长,家蚕死亡率和残留农药测定仪的检测抑制率均呈现下降趋势,绝大部分农药对家蚕的死亡率与检测抑制率之间同步性较好,但乙酰甲胺磷的检测抑制率明显偏低,易出现假阴性结果。因此,酶抑制速测法可作为养蚕前桑叶农药残留粗筛检测,也可在家蚕中毒事故发生后作为判断农药种类的快速检测方法。     

龙须菜苯丙烷类抑藻活性物质的分离纯化及其对6种赤潮微藻的抑藻活性

采用溶剂浸提、液液萃取、硅胶柱层析和硅胶薄层层析等分离方法以及红外光谱、质谱和核磁共振谱等光谱技术,初次从龙须菜中纯化得到4种苯丙烷类化合物:邻苯二丙酸、gossonorol、7,10-epoxy-ar-bisabol-11-ol和对羟基苯乙醇,并进一步分析了此4种苯丙烷类化合物对强壮前沟藻、赤潮异弯藻、米氏凯伦藻、球形棕囊藻、东海原甲藻和中肋骨条藻生长的影响。结果表明,它们对以上6种赤潮微藻的生长表现出明显的选择性抑制作用。其中,邻苯二丙酸、gossonorol和对羟基苯乙醇表现出更为广泛的抑藻活性。比较此4种苯丙烷类化合物和重铬酸钾对赤潮微藻生长的半抑制效应浓度EC50-96 h,发现邻苯二丙酸对强壮前沟藻、赤潮异弯藻和球形棕囊藻,gossonorol和羟基苯乙醇对赤潮异弯藻和球形棕囊藻,7,10-epoxy-ar-bisabol-11-ol对赤潮异弯藻和米氏凯伦藻在生长抑制方面比重铬酸钾更具有优势。     

Pharmacodynamic effects of ivabradine, a negative chronotropic agent, in healthy cats

Objective

To determine the pharmacodynamic effects of oral ivabradine in cats.

Animals

Eight healthy, adult domestic short hair cats.

Methods

Each cat underwent four study periods of 24 h, receiving either one dose of placebo or ivabradine (0.1 mg/kg, 0.3 mg/kg, and 0.5 mg/kg) in a single-blind randomized crossover study. Clinical tolerance was assessed hourly for the first 8 h, at 12 h, and at the end of the 24-h study period. Heart rate and blood pressure were monitored continuously for 18–24 h via radiotelemetry after each treatment. Response to stress (acoustic startle) was studied before (t = 0) and after treatment (t = 4 h). Statistical comparisons were made using a linear mixed models and 1-way and 2-way repeated measures ANOVA.

Results

Heart rate (min⁻¹) decreased significantly (P < 0.05) in a dose-dependent manner with peak negative chronotropic effects observed 3 h after ivabradine (mean ± SD; placebo, 144 ± 20; ivabradine 0.1 mg/kg, 133 ± 22; ivabradine 0.3 mg/kg, 112 ± 20; and ivabradine 0.5 mg/kg, 104 ± 11). Heart rate (min⁻¹) was still reduced (P < 0.05) 12 h after ivabradine (0.3 mg/kg; 128 ± 18 and 0.5 mg/kg; 124 ± 16) compared to placebo (141 ± 21). The tachycardic response to acoustic startle was significantly (P < 0.01) blunted at all 3 doses of ivabradine. Myocardial oxygen consumption estimated by the rate-pressure product was significantly reduced (P < 0.05) for all doses of ivabradine. No effect of ivabradine on systolic, diastolic, and mean blood pressure was identified and no clinically discernable side effects were observed.

Conclusion

These findings indicate that a single oral dose of ivabradine predictably lowers heart rate, blunts the chronotropic response to stress, and is clinically well tolerated in healthy cats. This makes ivabradine potentially interesting in the treatment of feline heart disease where ischemia is of pathophysiologic importance.     

槟榔多酚提取物对α-葡萄糖苷酶活性的抑制动力学研究

为了研究槟榔多酚提取物对α-葡萄糖苷酶活性的影响,以75%乙醇为提取溶剂,利用超声波辅助法提取槟榔多酚（槟榔籽和槟榔壳多酚）,采用S-8大孔树脂对粗提物进行纯化,探讨纯化前后的槟榔多酚提取物对α-葡萄糖苷酶活性的抑制作用,通过动力学实验判断对酶活性的抑制类型,同时对添加不同浓度槟榔多酚提取物的α-葡萄糖苷酶的荧光光谱和同步荧光光谱进行分析。结果表明：槟榔籽多酚提取物纯化前后的IC₅₀分别为(0.34±0.12)、(0.33±0.10) μg/mL,槟榔壳多酚提取物纯化前后的IC₅₀分别为(1.73±0.31)、(0.14±0.09)mg/mL,纯化后的槟榔壳多酚提取物对α-葡萄糖苷酶活性的抑制作用显著增强。动力学实验表明,槟榔多酚提取物对α-葡萄糖苷酶活性的抑制作用类型为竞争性与非竞争性的混合型抑制。荧光光谱和同步荧光光谱分析结果显示,槟榔多酚提取物对α-葡萄糖苷酶内源性荧光具有淬灭作用,但对酶的构象没有影响。槟榔籽和槟榔壳多酚提取物对α-葡萄糖苷酶活性的抑制作用均较强,可为天然α-葡萄糖苷酶抑制剂的开发提供参考。     

苯酚对废水生物硝化过程的抑制

由于硝化细菌对水产养殖水质可以起到明显调节作用,近年来在水产养殖领域的应用日益广泛。但废水中有毒有害物质的存在常常会导致硝化细菌的活性受到严重抑制,从而严重影响养殖水体及水产品的质量。本文利用富集培养的硝化污泥研究了苯酚对生物硝化过程的抑制效应。结果表明,苯酚对氨氮生物硝化过程的抑制属于非竞争性抑制,抑制常数K1和EC50均为2．61mg／L。泥龄相同的条件下,有苯酚抑制剂存在时氨氮的出水浓度高于无抑制情况,且苯酚浓度越高,氨氮出水浓度也越大;而达到相同的氨氮出水浓度,抑制剂存在条件下的泥龄大于无抑制条件,且抑制程度越高,所需泥龄越长。     

杉木枯枝落叶分解12个月后化感物质对杉木的化感作用

采用有机溶剂与蒸馏水混合浸提杉木枯枝落叶分解12个月后化感物质,应用杉木种子发芽试验进行生物检测。结果表明:与对照相比,不同浓度杉木枯枝落叶及腐殖土中的化感物质对杉木种子绝对发芽势、绝对发芽势、胚根长、胚轴长、干物质量及鲜物质量均表现为抑制作用;杉木枯枝落叶中的弱极性化感物质200mg/kg处理的绝对发芽率、绝对发芽势、胚根长、胚轴长、鲜物质量及干物质量分别比对照降低45.73%、47.71%、41.89%、57.50%、56.92%及33.33%,而腐殖土中的极性化感物质200mg/kg处理对种子绝对发芽率、绝对发芽势、胚根长、胚轴长、鲜物质量和干物质量与对照相比分别降低28.20%、28.08%、48.20%、66.88%、69.74%及48.48%。     

蛇床子素对植物病原真菌抑制机制的初步研究

天然化合物蛇床子素(osthol)对草坪纹枯病菌Rhizoctonia solani、芒果炭疽病菌Colletotrichum musae、苹果叶枯病菌Rhizoctonia solani、辣椒疫霉病菌Phytophora capsici、辣椒炭疽(红)病菌Collectotrum gloesporioides、番茄灰霉病菌Botrytis cinerea Pers、油菜菌核病菌Sclerotinia sclerotiorum、小麦赤霉病菌Fusarium graminearum、苹果轮纹病菌Macrophoma kawatsukai、水稻稻瘟病菌Pyricularia grisea、西瓜枯萎病菌Fusarium oxysporum f.sp.niveum、棉花枯萎病菌Fusarium oxysporum f.sp.vasinfectum、棉花黄萎病菌Verticillium dahliae等有不同的抑制活性,对大多数病菌其抑制中浓度(EC50值)在21.15~61.62 μg/mL之间。以小麦赤霉病菌为研究对象,结果表明50 μg/mL蛇床子素对其孢子萌发有显著的抑制作用;100 μg/mL蛇床子素处理24 h后,菌丝大量断裂,可溶性蛋白含量增加,菌体葡萄糖含量呈"V"型变化,几丁质水解酶活性和几丁糖含量均高于对照。     

喜树碱对小菜蛾体内保幼激素及蜕皮激素滴度的影响

为明确喜树碱对小菜蛾Plutella xylostella生长发育的抑制作用及其机制,设置0.5、1.0、2.0mg/m L剂量处理其3龄幼虫,采用浸叶饲喂法和高效液相色谱法测定了喜树碱对小菜蛾体内蜕皮激素和保幼激素滴度的影响。结果显示,喜树碱各剂量处理均显著抑制了小菜蛾幼虫的生长发育,抑制率最高达到28.42%;各处理小菜蛾化蛹时间均延迟,异常蛹增多,羽化率降低;其中2.0 mg/m L处理后4 d其化蛹率为6.67%,对照组化蛹率为86.60%。0.5、1.0 mg/m L处理下,小菜蛾体内蜕皮激素滴度显著低于对照组,仅为对照组的0.06倍;而保幼激素滴度增加,分别可达到28.74mg/m L和36.29 mg/m L,是对照组的9倍左右。表明喜树碱可影响小菜蛾体内蜕皮激素和保幼激素的平衡,延迟和影响了小菜蛾的正常发育进程,可实现对小菜蛾种群的控制作用。     

Alfalfa, rice by-products and their incorporation for weed control in rice

Two alfalfa varieties, namely Rasen and Yuba , and rice by-products of Koshihikari ( Oryza sativa L. cv. Japonica ), including hull and bran were used for weed control in rice. Rasen and Yuba were sequentially evaluated to have the strongest allelopathic potential among eight common alfalfa varieties in Japan. Rasen , Yuba and rice by-products in a laboratory experiment exhibited suppression of emergence of lettuce ( Lactuca sativa L.), barnyardgrass ( Echinochloa oryzicola Vasing.), and monochoria ( Monochoria vaginalis Presl var. plantaginea Solms-Laub.). In a paddy field experiment, at 15 days after application, a dose of 1 ton ha⁻¹ of alfalfa, rice by-products and the incorporated alfalfa-rice by-products significantly inhibited weed growth and reduced weed species, except for rice bran. However, at 40 days after application, the greatest weed control was sequentially recorded with Yuba (95.2%), Rasen (90.5%) and the incorporated Rasen -hull (88.3%). Rice hull exhibited stronger (51.7%) weed control than the negligible weed control of rice bran (25.1%). Inhibition of both Rasen and Yuba on weed emergence after application became more vigorous, whereas those of rice by-products were gradually devitalized. Rasen had a maximum increase of rice yield (80.6%) compared to the control and it was slightly higher (9.6%) than the herbicide treatment. Findings showed that Rasen was the most promising material for weed control among those studied. Results denoted that weed control capability of allelopathic materials had an impetuous effect on rice growth and yield.     

几种苯甲酸类化合物对甜菜夜蛾多酚氧化酶活性的影响

为了探讨环境友好杀虫剂的开发途径,以对羟基苯甲酸等5种苯甲酸类化合物为效应物,研究了该类化合物对甜菜夜蛾多酚氧化酶(PPO)活性的影响。结果表明:5种化合物均对该酶表现出一定的抑制作用,其中以对羟基苯甲酸的抑制作用最为显著,I50为0.23 mg/mL,其次为5-甲氧基水杨酸。进一步研究这两种化合物对甜菜夜蛾多酚氧化酶的抑制机理,发现对羟基苯甲酸属于可逆反应的混合型抑制剂,其Ki与Kis分别为0.46 mg/mL和0.02 mg/mL;5-甲氧基水杨酸属于竞争性抑制剂,Ki为0.87 mg/mL。