芒果蒂腐病菌对芒果采后乙烯释放和ACC含量的影响

测定芒果蒂腐病菌(Botryodiplodia theobromae)对芒果果实乙烯代谢的影响,结果表明:B.theobromae在芒果果肉培养基上不产生乙烯,但是B.theobromae代谢活动能诱导芒果果肉中产生大量的1-氨基环丙烷-1-羧酸(ACC),导致芒果快速释放乙烯,随着发病程度增加和贮藏期延长,乙烯释放速率快速增加。高浓度乙烯使芒果果肉快速软化,在25℃条件下,果实在发病后3～5 d就完全腐烂。     

Detection and Pharmacokinetics of Etoricoxib in Thoroughbred Horses

Etoricoxib, a selective inhibitor of cyclooxygenase-2, is used in the treatment of many inflammatory diseases and dental pain in humans. The aim of this study was to determine the pharmacokinetics and metabolism of etoricoxib in horses. Six horses weighing an average of 475 ± 25 kg were administered a single oral dose of etoricoxib at 1 mg/kg body weight. The results show that the drug reached a maximum concentration of 505.2 ± 67.8 ng/mL in 48 minutes after administration. The elimination half-life was calculated to be 10.20 ± 1.30 hours. Mass spectrometric analysis confirmed that etoricoxib is metabolized in horses via the oxidation of its 6′-methyl group to form a hydroxyl methyl etoricoxib which can further be oxidized to form either an acid or be glucuronidated. In addition, the 1′-N terminal of 6′-hydroxymethyl metabolite is oxidized to form the corresponding 1′-N oxide metabolite. The present results have clearly demonstrated that etoricoxib is mainly excreted in urine as metabolites. From these data, it is also possible to postulate a detection time for the metabolites which in turn can assist in the control of illegal use of the drug in horse racing.     

有机生产模式下牧草粘虫防治方法的初步研究

为探索牧草有机生产模式下的粘虫(Mythimna separata Walker)防治,对有机牧草种植区和非有机牧草种植区的5种牧草,通过生物农药BT、农业防治即时刈割利用牧草和化学合成农药溴氰菊酯、辛硫磷处理,进行草地上的粘虫防治试验。结果表明:生物农药BT防效与常规农药校正防效无显著差异,校正防效达到91.67%～98.59%;其次为即时刈割利用牧草,校正防效达到52.78%～81.35%,该法与有机生产理念高度吻合,可作为有机牧草生产中首选的防治方法之一。     

新疆棉区杂交棉养分吸收分配特点研究

[目的]研究新疆棉区杂交棉养分吸收分配的特点。[方法]以杂交棉标杂A1、鲁棉研15和常规棉新陆早13号为材料进行试验。[结果]在新疆棉区种植条件下,杂交棉单铃重、衣分、皮棉产量均高于常规棉,且达极显著水平。杂交棉与常规棉对N、P2O5和K2O的吸收均呈Logistic函数曲线变化。但养分积累量和吸收强度不同。杂交棉在各生育阶段养分净积累量高于常规棉,养分吸收强度大于常规棉,养分最大吸收速率出现的时间较常规棉晚。杂交棉养分分配规律和常规棉一致,但在生育后期,养分向生殖器官（籽棉）分配较常规棉多,向营养器官分配低于常规棉。[结论]为制定相应的高产施肥方案和施肥模式提供理论依据。     

绣球小冠花等35种植物提取物对粘虫的杀卵作用研究

采用浸卵法测定了绣球小冠花等35种植物提取物对粘虫的杀卵作用。结果表明,欧当归种子丙酮提取物、蛇床种子氯仿提取物、蓖麻种子甲醇、石油醚与乙酸乙酯提取物、绣球小冠花根甲醇、乙醇、丙酮与乙酸乙酯提取物对粘虫具有很强的杀卵作用,5 d的校正未孵化率均达100%;欧当归根75%甲醇与石油醚提取物、欧当归种子甲醇与石油醚提取物具有较强的杀卵作用,校正未孵化率分别为39.65%与35.31%,55.99%与34.51%,绣球小冠花根、曼陀罗种子和苘麻种子石油醚提取物具有一定的杀卵作用,校正未孵化率分别为11.45%,11.79%和10.60%,其他提取物杀卵作用很弱或无杀卵作用。绣球小冠花、欧当归、蛇床和蓖麻4种高效杀卵植物具有研究和开发利用价值。     

黏虫体内两种微管蛋白基因cDNA序列的克隆与序列分析

以黏虫4龄幼虫为材料提取总RNA,利用RT-PCR和cDNA末端快速扩增技术(RACE),分别扩增得到该虫的α和β微管蛋白基因的cDNA序列各1条。其中α微管蛋白基因的cDNA序列1 443个碱基,包括一个1 353个碱基的开放阅读框,编码一个含450个氨基酸的蛋白,分子量约为50.0ku。氨基酸的142~148位存在一个微管蛋白标志信号片段GGGTGSG,在氨基酸序列的C-端有一个酪氨酸残基,N-端存在一个对转录后调控非常重要的保守区MRECI序列,以上特点与其他昆虫α微管蛋白氨基酸序列相同。黏虫β微管蛋白基因cDNA序列含1 906个碱基,开放读码框1 344个碱基,编码氨基酸447个,分子量约为50.2ku,等电点4.75。1~4个氨基酸MREI为β微管蛋白转录后调控信号,140~146GGGTGSG位同样存在一个微管蛋白标志信号片段。序列比对表明,克隆的α和β微管蛋白基因与其他昆虫的α和β微管蛋白基因在核苷酸和氨基酸水平上都是高度同源的,黏虫与家蚕(Bombyx mori)α微管蛋白的氨基酸序列同源性达到99.3%,与其他3种夜蛾科昆虫α微管蛋白的氨基酸序列同源性更是达到100%。黏虫与家蚕β微管蛋白的氨基酸序列同源性达到98.7%,与烟草天蛾β微管蛋白的氨基酸序列同源性达到99.6%。两个基因的cDNA序列已经登录GenBank并获得登录号分别为EU100016和EU234504。     

双氧木脂素E对东方粘虫幼虫体壁肌超微结构及Na+-K+-ATPase、Ca2+-ATPase的影响

双氧木脂素E（haedoxane E）是从杀虫植物透骨草Phryma leptostachya L.中分离出的一种对多种农林害虫和卫生害虫具有杀虫活性的化合物。本研究以东方粘虫Mythimna separata为供试昆虫,对双氧木脂素E对其幼虫杀虫作用部位进行了初步研究。电镜观察表明,双氧木脂素E对东方粘虫幼虫体壁肌具有致毒作用,能使肌细胞发生明显病变,细胞核皱缩变形,染色质浓缩,线粒体肿胀、大面积空泡化,肌质网扩张,肌原纤维排列紊乱,胞质内出现大量多泡体。酶活力测定结果也显示,双氧木脂素E能不同程度抑制Na+-K+-ATPase和Ca2+-ATPase活力。因此推测双氧木脂素E是一种作用于东方粘虫肌肉组织的肌肉毒剂。     

Metabolic adaptations to heat stress in growing cattle

To differentiate between the effects of heat stress (HS) and decreased dry matter intake (DMI) on physiological and metabolic variables in growing beef cattle, we conducted an experiment in which a thermoneutral (TN) control group (n = 6) was pair fed (PF) to match nutrient intake with heat-stressed Holstein bull calves (n = 6). Bulls (4 to 5 mo old, 135 kg body weight [BW]) housed in climate-controlled chambers were subjected to 2 experimental periods (P): (1) TN (18 °C to 20 °C) and ad libitum intake for 9 d, and (2) HS (cyclical daily temperatures ranging from 29.4 °C to 40.0 °C) and ad libitum intake or PF (in TN conditions) for 9 d. During each period, blood was collected daily and all calves were subjected to an intravenous insulin tolerance test (ITT) on day 7 and a glucose tolerance test (GTT) on day 8. Heat stress reduced (12%) DMI and by design, PF calves had similar nutrient intake reductions. During P1, BW gain was similar between environments and averaged 1.25 kg/d, and both HS and PF reduced (P < 0.01) average daily gain (-0.09 kg/d) during P2. Compared to PF, HS decreased (P < 0.05) basal circulating glucose concentrations (7%) and tended (P < 0.07) to increase (30%) plasma insulin concentrations, but neither HS nor PF altered plasma nonesterified fatty acid concentrations. Although there were no treatment differences in P2, both HS and PF increased (P < 0.05) plasma urea nitrogen concentrations (75%) compared with P1. In contrast to P1, both HS and PF had increased (16%) glucose disposal, but compared with PF, HS calves had a greater (67%; P < 0.05) insulin response to the GTT. Neither period nor environment acutely affected insulin action, but during P2, calves in both environments tended (P = 0.11) to have a blunted overall glucose response to the ITT. Independent of reduced nutrient intake, HS alters post-absorptive carbohydrate (basal and stimulated) metabolism, characterized primarily by increased basal insulin concentrations and insulin response to a GTT. However, HS-induced reduction in feed intake appears to fully explain decreased average daily gain in Holstein bull calves.     

家蚕有色茧主要色素物质在幼虫体内的代谢变化

为探讨有色茧色素物质在蚕体内的代谢机制,检测了有色茧主要色素物质的含量及其在家蚕5龄幼虫不同时期中肠、血液、丝腺组织中的消长变化,分析色素物质从中肠进入血液再转运到丝腺的时序差异。有色茧中,黄茧的色素以类胡萝卜素化合物为主,绿茧的色素以黄酮类化合物为主。黄酮类化合物、类胡萝卜素化合物在家蚕5龄幼虫中肠、血液、中部丝腺、后部丝腺中的含量均呈现龄初低、龄末高的趋势,其中,黄酮类化合物在熟蚕组织中的含量是中肠>血液>中部丝腺>后部丝腺;类胡萝卜素化合物在熟蚕组织中的含量是中部丝腺>后部丝腺>中肠>血液。2种色素物质含量变幅最大的是后部丝腺组织,结黄茧蚕和结绿茧蚕的黄酮类化合物分别增加406.55%、202.50%,类胡萝卜素化合物分别增加211.80%、250.84%。黄酮类化合物在5龄幼虫丝腺组织的绝对含量是结绿茧蚕大于结黄茧蚕,类胡萝卜素化合物在5龄幼虫丝腺组织的绝对含量是结黄茧蚕显著大于结绿茧蚕,与在不同颜色蚕茧中检测到的2种色素物质含量一致。研究结果提示:黄酮类化合物在5龄幼虫中肠组织中积累较多,类胡萝卜素化合物在丝腺组织中积累较多;丝腺组织中2种色素物质的含量与茧色密切相关;来自桑叶中的2种色素物质经中肠消化吸收后,再通过血液进入丝腺组织并产生累积效应。