黑胸散白蚁肠道共生甲烷菌的初步研究

通过对黑胸散白蚁(Reticulitermes chinensis Snyder)肠道的显微观察发现在后肠肠壁上有很多甲烷菌。共生甲烷菌形态多为短杆状和长杆状,其中短杆状居多。同时,用非培养法,对黑胸散白蚁肠道共生甲烷菌的16SrR NA基因进行扩增并克隆,对代表不同RFLP谱型的五个克隆测序,系统发育分析表明,这些克隆均属于甲烷杆菌目。     

GC-MS分析三白草脂溶性成分

经甲醇室温下浸泡、石油醚萃取得到三白草脂溶性部位,用气相色谱-质谱(GC-MS)联用技术检测其脂溶性成分,从中鉴定出15种化合物,占色谱总馏分出峰面积的43.77%,其脂溶性成分主要为脂肪酸(酯)和呋喃类.     

委陵菜胚和胚乳的发育类型

观察了委陵菜胚和胚乳的发育过程,结果表明,其胚乳属核型胚乳.合子横向分裂,产生基细胞和顶端细胞.顶端细胞和基细胞都进行横向分裂,形成直线状4-细胞的原胚.胚柄上部的细胞参加胚体的建成,其胚属藜型胚.     

Population fluctuation and persistence of one-host–two-parasitoid systems depending on resource distribution: from parasitizing behavior to population dynamics

Population dynamics and variability were examined in one-host–two-parasitoid experimental systems with different resource distributions: resource-clumped and resource-sparse conditions. The system consists of a seed beetle host, Callosobruchus chinensis, and two parasitoid wasps, Anisopteromalus calandrae (Pteromalidae) and Heterospilus prosopidis (Braconidae). In the resource-clumped condition, suitable hosts for parasitism (the late fourth-instar larvae and pupae) were clumped in 1 large resource patch, but they were scattered evenly among 16 small patches in the resource-sparse condition. Population censuses were conducted at 10-day intervals in long-term cultures, renewing 10 g of azuki beans (Vigna angularis). In both resource conditions, the first period was a single-species system of C. chinensis only, and A. calandrae was added in the second period. The one-host–one-parasitoid system with C. chinensis and A. calandrae showed stable population dynamics with small fluctuations. After addition of H. prosopidis in the third period, two of three replicates persisted to day 800 in each resource condition, although one replicate in each went to extinction at an immediate outbreak of the H. prosopidis population after the introduction. Population variabilities of C. chinensis and H. prosopidis were significantly higher and the mean population size of A. calandrae was significantly smaller in the resource-sparse condition than that in the resource-clumped one. A short-term experiment on parasitism efficiencies revealed that H. prosopidis parasitized significantly more at a low host density in the resource-sparse condition than in the resource-clumped one. Mutual interference of H. prosopidis was weak enough at low parasitoid densities but became abruptly stronger with high densities. Providing fresh hosts in a mixture of already parasitized ones, host-searching behaviors of a parasitoid were recorded by video for 3 h and were compared between the two wasp species. H. prosopidis could parasitize fresh hosts more efficiently than A. calandrae through frequent long-distance walks (walking to distant beans at one bout or outside a clump of beans with hosts and back soon on a distant bean of the clump) after reencounters with parasitized hosts. Considering all the experimental results, populations were judged to be more fragile and more likely to go to extinction in the resource-sparse condition than in the resource-clumped one. A higher attacking efficiency of H. prosopidis destabilized population dynamics more in the resource-sparse condition. Received: December 23, 1998 / Accepted: January 20, 1999     

制约黄连产业化发展的因素及发展对策--以石柱县为例

以石柱县为例,从经营模式、栽培品种、农药残留量及重金属含量等6个方面系统地分析了制约我国黄连产业化发展的因素;在此基础上,提出了相应的发展对策.     

光质对水仙叶片组织培养的效应

在水仙(Narcissus tazetta var.chinensis)离体培养过程中,不同光质对其脱分化和植株再生有不同的效应。愈伤组织诱导率为:黄光>绿光>蓝光>黑暗>白光>红光;愈伤组织分化情况是:绿光对植株再生有促进作用。     

粤西地区主要荔枝品种的形态及微形态分析

粤西地区已经成为广东省的荔枝主产区,本研究选择该地区较为广泛种植的4个荔枝品种为研究对象,它们分别是“黑叶”、“桂味”、“白糖罂”和“白腊”,通过野外调查以及对这些不同品种荔枝的叶和花的形态、微观形态的观察,并加以比较和分析,来探讨荔枝品种在形态特征上的差异及其与荔枝产量的关系,并为荔枝品种的早期鉴定提供依据.     

HPLC法测定陆英花和果实中齐墩果酸和熊果酸的含量

建立高效液相色谱法同时分离和测定陆英花和果实中齐墩果酸和熊果酸的含量。选用Kromasil C18色谱柱,流动相为甲醇∶水∶磷酸(90∶10∶0.2),检测波长210nm,流速0.8mL/min,柱温25℃。齐墩果酸进样量在0.55～5.50μg,熊果酸进样量在1.02~10.20μg时呈现良好的线性关系,相关系数均为0.9999,齐墩果酸和熊果酸的平均回收率分别为99.3%(RSD为1.9%)和101.2%(RSD为2.3%)。本法具有准确、灵敏、数据可靠的优点,可用于陆英花和果实的齐墩果酸和熊果酸的分离与测定。     

黑胸散白蚁肠道鞭毛虫共生细菌的初步研究

黑胸散白蚁(Reticulitermes chinensis)是在我国广泛分布的一种木食性白蚁,它的肠道内共生着大量的原生动物和原核生物。对其肠道内共生微生物的研究,有助于阐明木食性白蚁消化木质纤维素等植物源食物的机制。运用分子克隆技术对该白蚁肠道中鞭毛虫(Pyrsonympha grandis)相关共生细菌进行系统发育分析的结果。构建了与黑胸散白蚁肠道内共生鞭毛虫P.grandis相关的共生细菌的16SrDNA文库,通过对挑选克隆的RFLP分析选择了4个克隆进行测序,系统发育分析表明这4个克隆分别属于拟杆菌,"白蚁菌群1(Termite group 1)",γ-紫细菌,和β-紫细菌。     

一株产紫杉醇内生真菌的分离及鉴定

从中国南方红豆杉三龄树树皮中分离得到内生真菌ZU07,经液体发酵,用高效液相色谱技术对该真菌的发酵液提取物进行了分析,结果表明菌株ZU07能合成抗癌药物紫杉醇,其紫杉醇含量约为214.45μg/L.