Toxicological and biochemical characterizations of malathion sensitivity in two field populations of Oxya chinensis （Orthoptera： Acridoidea）

We evaluate comparative toxicity of malathion in the two populations of the grasshopper Oxya chinensis, collected from Daixian and Fanshi of Shanxi province, China. General esterases and acetylcholinesterase （ACHE） from the two populations were characterized and compared. LD50 of the Daixian population （7.58 μg/g body weight） was 2.02-fold higher than that of the Fanshi population （3.75μg/g body weight）. General esterase-specific activities in the Daixian population were 1.91,130 and 1.85-fold higher than those in the Fanshi population, when α-NA, α-NB and β-NA were used as a substrate, respectively. Kinetic studies of general esterase showed that Vmax values of general esterases hydrolyzing α-NA,α-NB and β-NA in the Daixian population were 2.15-, 1.12-, and 1.47-fold, respectively, higher than those in the Fanshi population. The AChE activity of the Fanshi population was 1.54-fold higher than that of the Daixian population. Kinetic analysis of AChE showed that significant differences were presented between the two populations in the Km values; and the Vmax value in the Fanshi population was higher than that in the Daixian population. Inhibition studies of AChE indicated that AChE from the Daixian population was 2.56-, 2.80-, and 2.29-fold less sensitive to inhibition by paraoxon, chlorpyrifos-oxon, and demeton-S-methyl, respectively, than that from the Fanshi population. These biochemical characterizations of general esterases and AChE were consistent with malathion bioassay in the two populations. It is inferred that the reduced sensitivity of altered AChE and increased general esterase activities play an important role in the differences of insusceptibility of Oxya chinensis to malathion between the two populations.     

濒危植物南方红豆杉濒危原因分析

南方红豆杉是我国第三纪孑遗特有树种,为国家1级濒危保护植物,主要分布于在长江流域、南岭山脉以及广东、广西、江西、河南、陕西、甘肃、台湾和山西等省（区）的山地。南方红豆杉分布区的生态环境特征是：热量充足,温暖潮湿。南方红豆杉濒危的主要原因有：（1）种子产生量少,萌发率和幼苗成活率较低（2）种群缺乏较强的竞争力,（3）地理分布的局限性,（4）对生境要求的特殊性和（5）人为破坏严重。此外,针对南方红豆杉濒危现状和原因,还提出了科学保护和可持续利用的对策。     

贵州九香虫营养成分分析

分析贵州产九香虫Aspongopus chinensis Dallas体内的营养成分。结果表明:从江和习水产九香虫都具有丰富的营养,其中粗蛋白分别为350.9mg·g-1和356.5mg·g-1、粗脂肪432.6mg·g-1和436.2mg·g-1、粗灰分22.9mg·g-1和22.8mg·g-1;总氨基酸含量为334.3mg·g-1和253mg·g-1,其中必需氨基酸占总氨基酸的41.22%和33.34%,必需氨基酸与非必需氨基酸之比分别为0.70和0.50;九香虫体内脂肪酸多以油酸和软脂酸为主,其中油酸占总脂肪酸的49.48%和41.54%;含有丰富的矿物质和微量元素,尤其是Mg的含量达到1.26mg·g-1和1.32mg·g-1,且不含有对人体有害的Hg、Pb和As;含有多种维生素,其中维生素C含量最为丰富,为0.78mg·g-1和0.79mg·g-1。作为具有保健功能的中药昆虫,同时具有丰富的营养成分,九香虫是极具潜力的药食两用食品。     

氟虫脲对东亚飞蝗和中华稻蝗几丁质合成酶基因表达的影响

为了探讨氟虫脲可能的作用靶标及毒性机制, 本研究以重要农业害虫东亚飞蝗Locusta migratoria manilensis (Meyen)和中华稻蝗Oxya chinensis (Thunberg)为材料, 采用简并引物扩增中华稻蝗几丁质合成酶1基因（OcCHS1）的部分cDNA序列; 以氟虫脲浸渍法处理2龄中期中华稻蝗及1, 2和3龄东亚飞蝗若虫为处理组, 丙酮处理为对照组, 使用RT-PCR和实时荧光定量PCR方法分析氟虫脲对蝗虫几丁质合成酶基因mRNA表达的影响。结果获得的OcCHS1部分cDNA序列, 其长度为312 bp, 编码104个氨基酸, GenBank登录号为HM214491, 与东亚飞蝗几丁质合成酶1基因（LmCHS1）在氨基酸水平上相似度达95％。RT-PCR结果显示, 处理组几丁质合成酶1扩增带均强于对照组。实时荧光定量PCR结果表明: 与对照组相比, 处理组中华稻蝗2龄中期若虫OcCHS1 mRNA表达提高了1.02倍, 东亚飞蝗1, 2, 3龄若虫LmCHS1 mRNA表达分别提高了34%, 82%和89%, 差异显著（P<0.05）。分析基因表达提高的原因是几丁质合成受阻后基因表达水平的一种代偿性增加, 由此推测几丁质合成酶可能是氟虫脲作用的靶标之一。     

穆棱东北红豆杉年轮-气候关系及其濒危机制

东北红豆杉是国家I级重点保护野生濒危植物,其径向生长与气候的关系对于探讨其种群濒危机制具有极其重要的意义。利用穆棱自然保护区内天然东北红豆杉树木年轮样本,建立了长300多年的树轮年表(1700—2005年)。分析径向生长特征发现东北红豆杉总体上呈波动式下降的生长方式,在1770年和1930年左右存在两个生长释放区,该地区调查的样本最大年龄达到370a左右。年表与气候变量之间相关分析表明,冬春季节最低气温、平均气温是树木生长的主要限制因子,其他气候因子也有一定的影响,但不起主要作用。1942年以后东北红豆杉年轮指数与Wilson重建的北半球气温变化吻合度降低,温度对东北红豆杉的径向生长限制性降低,这表明气候变暖可能有利于东北红豆杉的径向生长,但不足以说明气候变暖与东北红豆杉衰退的关系,其他气候因子的年轮气候响应分析也不能确定气候变化在东北红豆杉衰退中的主导作用。人为破坏可能是东北红豆杉衰退的主要因素,但气候变化在其中起到多大的贡献还有待深入研究。     

南方红豆杉不同扦插时间对成活率影响

南方红豆杉种子产量低,休眠期长,自然存有量和栽植数量少,人工造林种苗需求量大。为促进南方红豆杉的可持续利用,对南方红豆杉不同扦插时间繁殖作进一步探索。通过试验,插床的蔽光度为60%,用清水沙做基质、一年生枝条做插条,经过药剂处理,湿度保持在70%~80%,得出南方红豆杉以11月下旬扦插繁殖效果较好,成活率达78%。能批量生产,满足人工造林的种苗需求。     

Hypoglycemic effects of the wood of Taxus yunnanensis on streptozotocin-induced diabetic rats and its active components

Hypoglycemic effects of the H(2)O and MeOH extracts of the wood of Taxus yunnanensis were examined in streptozotocin (STZ)-induced diabetic rats. The H(2)O extract significantly lowered the fasting blood glucose level by 33.7% at a 100mg/kg dose on intraperitoneal administration. From the active H(2)O extract of the wood, three lignans, i.e., isotaxiresinol (1), secoisolariciresinol (2) and taxiresinol (3), were isolated as major components. These lignans were further tested for their hypoglycemic effects on the same experimental model. At a dose of 100mg/kg (i.p.), isotaxiresinol (1) reduced the fasting blood glucose level of diabetic rats by 34.5%, while secoisolariciresinol (2) and taxiresinol (3) reduced by 33.4% and 20.9%, respectively. The blood glucose lowering effects of 1 and 2 were stronger than the mixture of tolbutamide (200mg/kg) and buformin (1mg/kg) used as a positive control, which lowered fasting blood glucose level by 24.0%.     

In vivo anti-osteoporotic activity of isotaxiresinol, a lignan from wood of Taxus yunnanensis

Isotaxiresinol, the main lignan isolated from the water extract of wood of Taxus yunnanensis, was investigated for its effect on bone loss, on serum biochemical markers for bone remodeling and on uterine tissue, using ovariectomized (OVX) rats as the model of postmenopausal osteoporosis. After oral administration of isotaxiresinol (50 and 100mg/kg/d) for 6 weeks, bone mineral content (BMC) and bone mineral density (BMD) in total and cortical bones were increased as compared to those of OVX control rats, and decreases of three bone strength indexes induced by OVX surgery were prevented. Serum biochemical markers for bone remodeling revealed that isotaxiresinol slightly increased bone formation and significantly inhibited bone resorption without side effect on uterine tissue. These results suggest that isotaxiresinol may be useful for treatment of postmenopausal osteoporosis, especially for prevention of bone fracture induced by estrogen deficiency.     

中华青荚叶的一个新环烯醚萜甙

从山茱萸科中华青荚叶（Helwingia chinensis）的乙酸乙酯部份分离得到一个新环烯醚萜和三个已知环烯醚萜化合物,通过现代波谱技术,确定其结构为10-O-trans—cinnamoyl。leoside（1）,10-hydroxyoleoside 11-methylester（2）,jasminoside（3）and 10-hydroxyoleumpein（4）。