EVALUATION OF EXTRACTS FROM BAMBOO FOR BIOLOGICAL ACTIVITY AGAINST CULEX PIPIENS PALLENS

Abstract The extracts from 7 species of bamboo were tested for larvicidal activity against Culex pipiens pallens . At the tested concentration, the extracts of selected bamboo had different degree of toxic effects on the fourth instar larvae of Culex pipiens pallens . Among them, the extracts of Pleioblastus juxianensis, Brachystachyum albostriatum, Phyllostachys platyglossa and Pleioblastus amarus were found to be effective with LC₅₀values at 24 h of 30.65 mg/L, 53.94 mg/L, 41.21 mg/L and 54.49 mg/L respectively, against Culex pipiens pallens larvae. The extract of Pleioblastus juxianensis by Soxhlet method showed stronger activity than the extract obtained by interval-shaking, the LC₅₀ of which were 30.65 mg/L and 48.34 mg/L, respectively. The diethyl ether extract of Pleioblastus juxianensis exhibited better larvicidal activity than the methanol extract and the petroleum ether extract. The results would help to provide the basis for the study of environment acceptable pesticide for mosquito control, and also help to comprehensively utilize the source of bamboo.     

渗透胁迫下稻苗中铁催化的膜脂过氧化作用

在－０．７ＭＰａ渗透胁迫下,水稻幼苗体内和Ｈ２Ｏ２大量产生,Ｆｅ２＋积累,膜脂过氧化作用加剧。水稻幼苗体内Ｆｅ２＋含量与膜脂过氧化产物ＭＤＡ含量呈极显著的正相关。外源Ｆｅ２＋、Ｆｅ３＋、Ｈ２Ｏ２、Ｆｅ２＋＋Ｈ２Ｏ２、ＤＤＴＣ均能刺激膜脂过氧化作用,而铁离子的螯合剂ＤＴＰＡ则有缓解作用。ＯＨ的清除剂苯甲酸钠和甘露醇能明显地抑制渗透胁迫下Ｆｅ２＋催化的膜脂过氧化作用。这都表明渗透胁迫下水稻幼苗体内铁诱导的膜脂过氧化作用主要是由于其催化Ｆｅｎｔｏｎ型Ｈａｂｅｒ－Ｗｅｉｓｓ反应形成ＯＨ所致。     

黄瓜幼苗的冷锻炼与低温引起的光抑制

黄瓜幼苗的冷锻炼与低温引起的光抑制李晓萍,陈贻竹,李平,郭俊彦（中国科学院华南植物研究所,广州５１０６５０）关键词：低温引起的光抑制,荧光猝灭,冷锻炼,黄瓜幼苗低温使植物利用光能的能力降低从而引起或加剧光抑制（ｈａｓ等１９８３）。在光抑制中常以叶绿素...     

Repair effect of thymine radical anion by echinocoside using pulse radiolysis

Repair activities of thymine radical anion by echinocoside, isolated from Pedicularis plicata. were studied using pulse radiolysis technique. The thymine radical anion was produced by the reaction of hydrated electron with thymine. Echinocoside. one of the polyphenols of phenylpropanoid glycoside, was added to the thymine aqueous solution saturated with N2. Kinetic analysis by transient absorption spectrum showed that thymine radical anion was formed at first, and then after several decades of microseconds of pulse radiolysis. the spectrum of thymine radical anion was changed to that of echinocoside radical anion. The evidence indicated that thymine radical anion was repaired through one-electron-transfer between the DNA base radical anion and echinocoside. The rate constant of electron transfer by echinocoside was 1.45× 109 dm3 · mol1 · s 1.     

有机磷农药对土壤动物群落结构的影响研究

本文研究了有机磷农药废水灌溉对土壤动物群落结构的影响,并探讨了影响机理,结果表明,土壤动物种类和数量随着农药影响程度的增加而减少,在农药污染影响严重的１、２区,计有土壤动物２１类和２２类,动物平均密度为２８５７１个／ｍ＾２和５１２６９个／ｍ＾２,受中度和轻蔗污染影响的３、４区分别有３５类和４７类,平均密度为５９２８５个／ｍ＾２,１５６５８７个／ｍ＾２。污染区土壤动物种类的减少主要由于常见类群和稀有