蚂蚁和紫胶蚧互利关系中的行为机制

研究了云南元江蚂蚁与紫胶蚧互利关系。结果表明,紫胶蚧寄生能招致互利共生的蚂蚁光顾。紫胶蚧寄生前后,蚂蚁造访久树的频率分别是3.5和11.2次.min-1,单枝上蚂蚁数量分别为3~8和11~23头,苏门答腊金合欢上活动的蚂蚁种类有部分差异,而久树上则完全不同。蚂蚁无取食紫胶蚧幼虫和驱赶或干扰其天敌的行为,蚂蚁光顾有利于紫胶蚧正常生长,对紫胶蚧的生殖力不产生显著影响,但增加泌胶量和虫体重。与紫胶蚧互利共生的蚂蚁有一定特异性,但随着不同时期、地区有一定差异。蚂蚁和紫胶蚧互利关系中的行为机制不是简单地提供和利用蜜露,蚂蚁喜欢取食刚刚分泌的蜜露,寄主植物的代谢生理、蜜露所含成分比例的变化影响蚂蚁和紫胶蚧的互利共生关系。     

Surface Plasmon as a Probe of Local Field Enhancement

New method of experimental determination of local field enhancement at metal nanoparticles is suggested. It uses surface plasmon as a probe. Alternating-sign shift of surface plasmon resonance in copper nanoparticles incorporated in silica matrix has been observed under irradiation by intense femtosecond laser pulse. The red shift of plasmon observed during the action of pump pulse is interpreted as a result of change of dielectric constant of silica matrix due to optical Kerr effect in electric field of pump pulse enhanced in a vicinity of metal nanoparticles. The field enhancement factor is estimated from the value of the observed red shift of plasmon resonance.     

凋缨菊属在广西的首次记录及其生物地理学意义

报道了广西菊科斑鸠菊族的1个新记录属——凋缨菊属,描述了凋缨菊的分类学特征,给出了详细的图解,绘制了整个凋缨菊属的分布图。这一发现表明了我国桂西南热带地区与滇南以及中南半岛在植物区系上的紧密联系。     

Kerr Constant of Vesicle-Like Droplets

The Kerr effect on vesicle-likedroplets (vesicles, cells or emulsion droplets) is described. Wegive a derivation of the Kerr constant for a dielectric fluiddroplet immersed in another fluid, assuming that the droplet in aweak electric field becomes a prolate ellipsoid. The Kerr constantis evaluated also for a droplet covered by a membrane of nonzerothickness. Comparing the theory with the experiment on dropletmicroemulsions from the literature, the bending rigidity constantof the surface layer is estimated.     

Dynamic structure of human serum transferrin from transient electric birefringence experiments

In order to investigate the secondary, tertiary, and dynamic structure of the iron-free (apo) and iron-saturated (holo) forms of human serum transferrin and its amino (N)-terminal lobe at the physiologically relevant pHs 7.4 and 5.0, we have combined ultraviolet circular dichroism (CD) spectroscopy with transient-electric birefringence (TEB) measurements. No significant changes are found in the protein's secondary structure under the different conditions studied. The tertiary structure as monitored by near-UV CD is affected by iron binding, but does not change upon decrease in pH. In contrast, TEB results indicate dramatic changes in the dynamic structure of transferrin both upon binding of iron and decrease of pH. In apotransferrin freedom of movement is found for the lobes with respect to each other, and for the domains within the lobes. The interlobal flexibility is considerably enhanced at the lower pH. Holotransferrin is found to behave as a rigid molecule. © 1995 Wiley-Liss, Inc.     

紫胶蚧寄生对寄主植物营养成分的影响

报道了1个世代中紫胶蚧Kerria laccaKerr寄生对寄主植物营养成分产生的影响。结果表明:紫胶蚧寄生对寄主植物营养成分有影响,被寄生枝条的氨基酸、无机盐和营养成分总量都出现变化。以久树Schleichera oleosa(Lour)为例,紫胶蚧寄生使久树枝条中氨基酸总量减少了35%。其中,天门冬氨酸、苏氨酸、丝氨酸、甘氨酸、丙氨酸、缬氨酸、异亮氨酸、亮氨酸、酪氨酸、苯丙氨酸的含量也都存在不同程度减少。但是,蛋氨酸、组氨酸、赖氨酸、精氨酸、色氨酸含量比对照枝条中高。被寄生枝条中氮、磷(P2O5)、铁等呈现下降趋势,钠元素含量几乎没有发生变化,而钾、钙、镁、铜、锌、锰等却有不同程度的增加,特别是钙元素含量,被寄生枝条中钙元素的含量是对照枝条的5.3倍左右。紫胶蚧寄生对枝条中总糖、蛋白质、脂肪、粗纤维、水溶性物质以及灰分含量都产生不同程度影响,被寄生枝条中蛋白质、粗纤维含量比对照枝条中含量低;而被寄生枝条中总糖、脂肪、水溶性物质、灰分含量比对照枝条中高。     

野生中泰南五味子果实的形态及营养成分分析

中泰南五味子( Kadsura ananosma Kerr )为五味子科( Schisandraceae)南五味子属( Kadsura Kaempf. ex Juss.)攀缘植物[1]14,其根、藤茎、果实是珍贵的傣药,具有收敛固涩、益气生津、补肾宁心的作用。对中泰南五味子化学成分的研究结果表明：中泰南五味子体内含有较多的木脂素类和三萜类成分,其中20多个成分为其特有成分,这些成分具有抗氧化、抗HIV病毒等药理活性[2-5]。中泰南五味子果实具有果大、肉多、酸甜可口等特点,还可作为野生水果食用,但目前对中泰南五味子果实的相关研究尚未见报道;相关志书[1]15,[6]234对其果实的基本描述也不完整,甚至空缺。为此,作者对野生中泰南五味子果实的形态特征进行观察,并对其营养成分进行分析,以期完善中泰南五味子果实的基础研究数据,为其深入开发和利用提供依据。