微孔草种子油的三萜醇和甾醇成分

微孔草Microula sikkimensis Hemsl,种子油中的不皂化物含量为0.6％。从不皂化物中分离出三萜醇和甾醇。已鉴定有4个三萜醇(β—香树脂醇、环阿屯醇、羽扇醇和24—次甲基环阿屯醉),11个甾醇(胆甾醉,△~7胆甾醇、菜油甾醇,24—甲墓△~7—胆甾醇、β—谷甾醇,22-二氢菠菜甾醇、菜子甾醇、豆甾烯醇、5,24(28)—豆甾烯醇、△~7—燕麦甾醇和7,24(28)-麦角甾醇)。     

植物甾醇与心血管疾病的研究进展和应用现状

植物甾醇是植物中存在的一大类化学物质的总称,包括植物甾醇和植物甾烷醇。植物甾醇的化学结构与胆固醇相似,对脂代谢具有调节作用。本文对植物甾醇/植物甾烷醇降血脂、预防动脉粥样硬化等心血管疾病研究进展及其应用现状进行综述。     

新金色分枝杆菌ksdD基因的敲除及其对菌株AD(D)合成的影响

新金色分枝杆菌(Mycobacterium neoaurum)能将植物甾醇转化为药物中间体4-烯-雄甾-3,17-二酮(AD)和1,4-二烯-雄甾-3,17-二酮(ADD),其中3-甾酮-△1-脱氢酶(KSDD)是AD转化为ADD的关键酶.本实验室在筛菌过程中筛选到一株能将甾醇转化为AD(D)的菌株,经鉴定为M.neo...     

狭叶花椒化学成分研究(Ⅱ)

从芸香科植物狄叶花椒(Zanthoxylum stenophyllum Hemls)根皮中分到5个化合物。通过IR,Uv,MS,¹HNMR,¹³CNMR,¹H-¹Hcosy,¹³CNMR-APT,¹³CNMR-DEPT,元素分析等手段,单体分别鉴定为β-谷甾醇(β-sitosterol),双狭叶花椒碱(bistenofine),鹅掌楸宁(liridenine),Decarine,Arnottianamide。其中双狭叶花椒碱是一种新生物碱。     

食物密度对镜湖萼花臂尾轮虫不同克隆生活史特征的影响

对镜湖萼花臂尾轮虫（Brachionus calyciflorus）夏季种群内4个生化遗传特征上互不相同的克隆（克隆A、B、C和D）在4个斜生栅藻（Scenedesmus obliquus）密度（1.0×10⁶、2.0×10⁶、4.0×10⁶和8.0×10⁶ cells·L^-1）下的生活史特征进行了研究.结果表明：食物密度对各克隆轮虫的存活率和繁殖率均有不同的影响.4克隆中克隆C的世代时间最短,克隆B的世代时间、生命期望和平均寿命最长,克隆A的后代混交雌体百分率最高;净生殖率和个体适合度在4克隆间无显著差异.镜湖萼花臂尾轮虫在2.0×10⁶ cells·L^-1的食物密度下净生殖率最低;在1.0×10⁶cells·L^-1的食物密度下平均寿命和生命期望最短,而后代混交雌体百分率却最高;在8.0×10⁶cells·L^-1的食物密度下种群内禀增长率最高,平均寿命和生命期望最长;在高食物密度（4.0、8.0×10⁶cells·L^-1）下个体适合度较大.克隆C的个体适合度在密度为3.9×10⁶cells·L^-1时最小,而克隆D的个体适合度在食物密度为6.34×10⁶cells·L^-1时最大.食物密度的变化可能是7月份之后镜湖萼花臂尾轮虫从水环境中消失的原因,而4克隆轮虫个体适合度的相似性则可能是镜湖轮虫共存于同一水体的原因之一.     

潭江流域森林碳蓄积与能源燃烧碳释放

研究了潭江流域典型区中小尺度森林碳库与人类活动化石能源碳释放.结果表明,自1990年 以来,森林一直起着碳汇的作用,并且随着经济发展与时间延长,汇的作用得到加强,1990 年森林净吸收碳量为1.0579×10⁷ t,到2002年森林净吸收碳量增至1.28061×10⁷ t,年平均净吸收碳量为1.856×10⁵ t.化石能源的碳释放与经济增长呈正相关,1990年的化石能源碳排放为9.508×10⁵ t,2002年为1.8562×10⁶ t,年平均增加量7.0×10⁴ t,2003年达到2.1968×10⁶ t,比2002年增加3.406×10⁵ t.2002年,潭江流域万元GDP能耗为2.21 t标煤,高于珠江三角洲平均水平.如果提高能源利用效率,使能耗降低至平均水平,则可削减3.360×10⁵ t碳排放,大于2002年流域森林净吸收的碳量. 从流域净吸收与净增排放的碳量来看,流域碳平衡与人类活动的关系有待进一步研究.     

△^5—3β，7β-二羟基甾醇及其C-7差向异构体波谱特征及胆碱酯酶的抑制活性

本文对△^5-3β,7β-二羟基甾醇（1—3）和△^5-3β,7α-二羟基甾醇（4～6）的一些核磁共振波谱特征进行了比较。活性测试表明化合物1—6对乙酰胆碱酯酶（AChE）无明显的抑制活性,对丁酰胆碱酯酶（BuChE）则有较强的抑制活性,其中24-亚甲基胆甾-5-烯-3β,7α-二醇（6）的IC50值为9．5μM。通过活性数据比较我们发现7α-羟基甾醇对丁酰胆碱酯酶的抑制活性明显比相应的7β-羟基甾醇高。我们通过计算7位羟基和四环平面之间的二面角角度来尝试解释这些活性差别。     

新的C4及CAM光合途径植物

以稳定性碳同位素比(δ¹³C)鉴别禾本科、莎草科、苋科和萝摩科共46种植物的光合作用途径,发现了36种新的C₄植物(δ¹³C-10.43到-13.66‰)和1种CAM植物(δ¹³C-15.24‰)。根据Hattersley区分C₄植物三种亚类型的不同δ¹³C值,提出在36种C₄中有8种具δ₁₃C值-10.4到-10.9‰者是NADP-ME型,6种具δ¹³C值-13‰左右的是NAD-ME型,其余种类可能是NADP-ME或PCK型。     

硼对吲哚乙酸在植物体内运输的影响

以绿豆为指示作物,研究缺硼对侧芽生长及³H-吲哚乙酸（IAA）在完整植株体内运输的影响.结果表明：缺硼诱导侧芽生长,导致³H-IAA移动峰靠近植株顶端,茎中³H-IAA的放射性活度也低于供硼充分的植株,说明缺硼抑制了³H-IAA在植株体内的极性运输;无论缺硼与否侧芽中均未检测到³H-IAA,所以侧芽的生长与³H-IAA在其中的积累没有关系,表明硼并不是通过调节IAA在侧芽中的积累,而是通过调节IAA在主茎的移动流调控侧芽生长;给缺硼植株供硼24 h能够恢复IAA在植株体内的极性运输能力.     

三江平原典型湿地土壤剖面有机碳及全氮分布与积累特征

研究了三江平原2类典型湿地(毛果苔草沼泽和芦苇沼泽)沉积物剖面有机碳、全氮的分布特征与积累现状.结果表明,2类沼泽剖面有机碳分布均具有明显的储碳层和淀积层;上层的储碳层厚度约为60 cm,有机碳平均含量分别为96和184 g·kg^-1,全氮平均含量分别为7.4和17.6 g·kg^-1;下层的淀积层内有机碳和全氮含量低而稳定.2类沼泽剖面有机碳和全氮含量随剖面深度增加而下降, 有机碳、全氮与容重之间相关均极显著(P＜0.01).2类典型湿地有机碳密度在20～40 cm剖面内最大.储碳层内,有机碳储量分别为1.83×10⁴和1.73×10⁴ t·km^-2,全氮储量分别为1.45×10³和1.67×10³ t·km^-2;100 cm以内,有机碳储量分别为2.86×10⁴和262×10⁴ t·km^-2,全氮储量分别为2.18×10³和2.49×10³ t·km^-2.植被类型对湿地剖面有机碳、全氮含量及储量均具有不同程度的影响.     

Effects of dietary sterols on development and reproduction of southwestern corn borer Diatraea grandiosella Dyar

Southwestern corn borer larvae, Diatraea grandiosella Dyar, were reared on artificial diets containing individual sterols (cholesterol, sitosterol, or stigmasterol) in concentrations ranging from 0.05 to 0.2%. Female larvae developed to pupae more rapidly as sitosterol and stigmasterol were increased in the diets. Increased cholesterol concentrations did not affect the larval period significantly, and development was not as rapid as with the phytosterols. Female larvae developed at significantly slower rates in all diets than did males, except at the highest concentrations of sitosterol and stigmasterol. Female pupae and adults were significantly heavier than the males, and pupal and adult weight increased as sterol concentrations increased. Number of eggs laid per fertilized female and egg hatchability were significantly increased as concentrations of the three sterols were increased in the larval diets. Sitosterol-reared females produced more eggs than did females reared on other sterols but egg hatchability was not significantly different among sterols.     

Sterol utilization in honey bees fed a synthetic diet: Analysis of prepupal sterols

The sterols of prepupal honey bees, Apis mellifera L., from brood reared by workers fed chemically-defined synthetic diets containing cholesterol, campesterol, sitosterol, stigmasterol, 24-methylenecholesterol, or no sterol over a 12-week period were isolated, identified, and quantified. The major sterol present in each prepupal sample was 24-methylenecholesterol, but significant levels of sitosterol and isofucosterol were also present in every case, as was a very small percentage of desmosterol (usually < 1%). This is the first report of isofucosterol being identified in the sterols of the honey bee. A considerably larger percentage of each dietary sterol was found in prepupae reared by workers fed that particular sterol in the diet. This was most dramatic in the case of the cholesterol diet in which case cholesterol content increased to as much as 17.2% of the prepupal sterols, whereas cholesterol had not exceeded 2.2% in samples from other diet regimens. However, stigmasterol comprised no more than 6.3% of the total sterols in any sample from prepupae fed the stigmasterol diet. The preponderance of 24-methylenecholesterol in all prepupae, regardless of the dietary sterol provided to the workers, as well as the lesser quantities of sitosterol and isofucosterol present in all samples, suggest a unique system of utilization and metabolism of these dietary sterols by the worker bees. Apparently they make available to the brood varying amounts of unchanged dietary sterol plus considerable and fairly constant portions of 24-methylenecholesterol, sitosterol, and isofucosterol drawn from their own sterol pools.     

低温处理对亚洲玉米螟幼虫抗寒性的诱导效应

室内条件下将亚洲玉米螟Ostrinia furnacalis (Guenée)幼虫放置在5℃(LT1处理组)和0℃(LT2处理组)下低温处理2 h后,分别测定了其低温诱导识别温度、存活率、抗寒性、过冷却点、体内水分和脂质含量百分率,并进行抗冻特异蛋白的诱导; 利用SDS-PAGE方法分析了低温诱导后亚洲玉米螟5 龄幼虫血清中抗冻特异蛋白。结果表明：亚洲玉米螟3、4和5龄幼虫的低温诱导识别温度分别为-13.5℃、-16.5℃和-18.5℃; 3、4和5龄幼虫存活率LT2组>LT1组>对照组(P<0.05);随虫龄增加,幼虫抗寒性逐步增强;对幼虫过冷却点无明显影响(P>0.05); 幼虫水分和脂质含量百分率为LT2组>LT1组>对照组,且随虫龄增加,虫体含水率和脂质含量百分率增高(P<0.05); 低温诱导产生了一种分子量约为29.0 kD的抗冻特异蛋白。研究结果表明低温诱导可以增强亚洲玉米螟幼虫的抗寒性。     

Utilization of Δ5,7 - and Δ8-sterols by larvae of Heliothis zea

Larvae from two populations of Heliothis zea were reared on artificial diets containing various sterols, which supported suboptimal growth, and their tissue sterols were characterized in order to determine how these dietary sterols are utilized by this insect. The sterols studied included Δ^5,7-sterols (7-dehydrocholesterol or ergosterol), Δ⁸-sterols (lanosterol and/or 24-dihydrolanosterol), and a Δ⁵-sterol (4,4-dimethylcholesterol). Although larvae did not develop on 4,4-dimethylcholesterol, those fed primarily Δ⁸-4,4,14-trimethylsterols developed to the third instar. When the latter sterols were spared with cholesterol, the larvae reached the sixth instar and contained 4,4,14-trimethylsterols as well as cholesterol in their tissues. When larvae were fed 7-dehydrocholesterol, <1% of the larvae from one population developed to the sixth instar and these larvae contained 7-dehydrocholesterol as their principal sterol. The other larvae successfully completed their larval stage when they were transferred from the diet containing 7-dehydrocholesterol (or no sterol) to a diet containing cholesterol within at least 9 days. The sterol composition of larvae transferred from a diet containing cholesterol to a diet containing 7-dehydrocholesterol, after they had reached 60% of their final weight, was 54% cholesterol and 46% 7-dehydrocholesterol. The major sterol isolated from the tissues of the larvae fed ergosterol was also 7-dehydrocholesterol. Therefore, although the larva of H. zea can dealkylate and saturate the side chain of the Δ^5,7,22-24β-methylsterol, it carries out little metabolism of the B ring of the nucleus. These studies demonstrate that, when Δ^5,7- or Δ⁸-sterols are the principal sterols in the diet of H. zea, they are absorbed and incorporated into its tissues, although they slow the rate of growth and may prevent complete development of the larva.     

Intermediates of stigmasterol metabolism in Spodoptera littoralis

Stigmasterol-24,28-epoxide, 22E-stigmasta-5,22,24(28E)-trien-3 beta-ol, and 22E-cholesta-5,22,24-trien-3 beta-ol were identified as normal metabolites of [3H]stigmasterol in Spodoptera littoralis larvae. Relative concentrations of all three of these metabolites increased when a diazasterol inhibitor was fed in combination with stigmasterol in the artificial diet. Identification of these sterols as intermediates in the conversion of stigmasterol to cholesterol in this insect indicates that intermediates analogous to fucosterol and fucosterol-24,28-epoxide in the conversion of sitosterol to cholesterol are produced in the metabolism of stigmasterol. This is the first published identification of stigmasterol-24,28-epoxide and 22E-stigmasta-5,22,24(28E)-trien-3 beta-ol as intermediates in this pathway in an insect.     

Sterol utilization in honey bees fed a synthetic diet: Effects on brood rearing

The dietary sterols, cholesterol, campesterol, sitosterol, stigmasterol and 24-methylenecholesterol, were tested for their ability to support brood rearing in the honey bee, Apis mellifera L., by adding them singly to a chemically-defined worker bee diet. Diet supplemented with 24-methylenecholesterol supported the greatest survival of worker bees, but diet supplemented with either 24-methylenecholesterol or cholesterol supported the production of nearly equivalent amounts of sealed brood and more than any of the other three sterols tested. Diets containing stigmasterol, sitosterol, campesterol, or no supplement produced less sealed brood, in decreasing order.     

甘蔗、玉米气味对亚洲玉米螟成虫产卵和幼虫取食的影响

【目的】农作物间套作对害虫的影响很大程度上取决于害虫的行为反应,通过研究玉米/甘蔗套作系统中植物气味对亚洲玉米螟Ostrinia furnacalis(Guenee)行为的影响,将为利用化学生态手段防治套作田中的害虫提供依据。【方法】通过昆虫触角电位实验、成虫产卵和幼虫取食实验,测定了甘蔗、玉米植株及二氯甲烷漂洗物对亚洲玉米螟成虫产卵、幼虫取食的影响。【结果】亚洲玉米螟成虫在甘蔗植株上的落卵量(卵粒数、卵块数)与玉米植株差异不显著,取食甘蔗植株的幼虫数量显著低于玉米植株。亚洲玉米螟对甘蔗、玉米叶片漂洗物均可产生EAG反应,且在同一浓度下的反应值之间无显著差异。成虫产卵量(卵粒数、卵块数)在0.1 gE/mL浓度的甘蔗和玉米漂洗物间差异不显著;幼虫对经甘蔗叶片漂洗物处理过的饲料的相对取食率均低于65.00%,显著低于玉米漂洗物处理的饲料。【结论】甘蔗和玉米气味对亚洲玉米螟产卵的影响没有差异,但甘蔗气味会导致初孵幼虫表现出很强的逃逸行为。     

玫烟色拟青霉对小菜蛾致病力的时间-剂量-死亡率模型模拟

小菜蛾Plutella xylostella是我国南方十字花科蔬菜上的重要害虫,已对田间常用的化学杀虫剂产生了严重的抗性。为寻找有效的小菜蛾生物防治措施,本实验研究了一株分离自家白蚁的玫烟色拟青霉Paecilomyces fumosoroseus (SCAU-PFCF01)对小菜蛾2～4龄幼虫的致病力。实验采用浸液法,供试浓度为1×10³、1×10⁴、1×10⁵、1×10⁶和1×10⁷个孢子/mL。结果表明：随玫烟色拟青霉孢子浓度的升高,小菜蛾的感病死亡率增加,在浓度为1×10⁷ /mL时,小菜蛾2、3和4龄幼虫的累计死亡率分别为96%、85%和80%。玫烟色拟青霉对小菜蛾各龄幼虫的致病力与供试龄期有关,其感病的敏感顺序为2龄、3龄和4龄。用时间 剂量 死亡率模型（time-dose-mortality model,TDM）对各龄幼虫的致病力数据进行模拟,所建模型均顺利通过Hosmer-Lemeshow拟合异质性检验,表明模型拟合良好,并由模型估计出了该菌株对小菜蛾各龄幼虫的致死剂量与致死时间。2龄幼虫接种后第7天、3龄幼虫接种后第5天、4龄幼虫接种后第4天的LC₅₀估计值分别为1.17×10⁴、1.44×10⁴和5.21×10⁴ /mL,LC₉₀估计值分别为1.98×10⁶、3.82×10⁷和1.29×10⁸ /mL。玫烟色拟青霉对小菜蛾幼虫的致死时间与浓度相关,供试各龄幼虫的LT₅₀值随着孢子悬浮液浓度的增加而递减,在1×10⁵～1×10⁷ /mL的范围内,2龄幼虫的LT₅₀值从3.16天降低到1.72天,3龄幼虫的LT₅₀从3.21天降低到1.83天,4龄幼虫的LT₅₀从3.69天降低到2.04天。即2龄幼虫致死所需的时间最短,其次为3龄幼虫,4龄幼虫致死所需的时间最长。结果显示了该株玫烟色拟青霉在小菜蛾的生物防治中具较强的应用潜力。     

Evaluation of transgenic Bt corn for resistance to the Asian corn borer (Lepidoptera: Pyralidae)

The Asian corn borer, Ostrinia furnacalis (Guenée), is the most important insect pest on corn in China. Bt transgenic corn provides a new tool for Asian corn borer control. Monsanto's YieldGard Bt transgenic corn expressing Cry1Ab protein, and a non-Bt control, were evaluated in Beijing. Laboratory bioassays were carried out by exposing neonates to an agar-free diet containing Bt corn whorl leaves, tassels, and anthers, or by exposing neonates directly to fresh silk and pollen. These are the tissues initially attacked by neonates in the field. All of these tissues, with the exception of pollen, contained sufficient insecticidal protein to kill > or = 95% of larvae within 7 d. Surviving larvae had also not grown beyond first instar and weighed < or = 0.1 mg. Although larvae feeding on Bt corn pollen were significantly smaller than those on non-Bt corn pollen, there was no significant difference in mortality. Field trials were also conducted with artificial infestations of Asian corn borer at mid whorl, late whorl, and silking stages. Damage ratings and number of larvae surviving per plant indicated that Bt corn was highly resistant to Asian corn borer. Therefore, YieldGard offers the potential for season-long protection against first- and second-generation Asian corn borer.     

保幼激素类似物及蜕皮甾类对亚洲玉米螟幼虫酚氧化酶活性的影响

分别用1 μg/头、0.1 μg/头和0.01 μg/头浓度的保幼激素类似物methoprene（蒙五一五）体外处理亚洲玉米螟5龄幼虫,测定幼虫体壁组织、血清和血细胞溶离物中酚氧化酶的活性。结果表明： 1 μg/头 methoprene处理组和0.1 μg/头处理组幼虫体壁组织中酚氧化酶活性与对照组相比有显著提高（P<0.01）,血清和血细胞溶离物中酚氧化酶活性也显著上升（P<0.01）。将含有20-羟基蜕皮酮的人工饲料饲喂亚洲玉米螟5龄幼虫,处理组幼虫体壁组织的酚氧化酶活性下降(P<0.05),血清和血细胞溶离物中的酚氧化酶活性均低于对照组 （P<0.01）。这些结果表明methoprene可以诱导亚洲玉米螟5龄幼虫体内酚氧化酶活性的上升,而20-羟基蜕皮酮则抑制了酚氧化酶的活性。