氮肥对2个杨树品种碳氮代谢的影响

研究以‘丹红’杨(美洲黑杨)和‘通辽1号’杨(小叶杨)为材料,在田间进行施氮肥和不施氮肥处理,分析2个杨树品种的生长性状、碳氮相关代谢物和发育木质部转录组的变化特征,探讨不同杨树品种氮肥利用的生理机制,为杨树的氮高效利用遗传育种奠定基础。结果表明:(1)‘丹红’杨和‘通辽1号’杨的总生物量在施氮处理后分别比不施氮处理提高了1.69倍和1.10倍;‘丹红’杨的总生物量在施氮肥和不施氮肥条件下分别是‘通辽1号’杨的13倍和10倍。(2)施氮处理显著抑制‘丹红’杨和‘通辽1号’杨树皮和木质部中总氮和多种水解氨基酸的含量,但是没有明显影响木质部的总碳、纤维素、半纤维素和木质素含量。(3)施氮处理显著影响了2个杨树品种发育木质部碳固定、糖代谢、氨基酸合成等碳氮代谢途径的基因的高表达,从而促进了植株生物量的积累。研究发现,施氮处理可以显著促进杨树发育木质部碳氮代谢途径相关基因的高表达,从而促进了杨树生物量的积累和生长;‘丹红’杨的木材产量在不同的氮素环境下都远远高于‘通辽1号’杨,更加适合人工林的大面积推广和种植。     

植物竞争研究综述

概述了竞争的概念、理论 (包括最大生长率理论、最小资源需求理论和资源动态两阶段说 )、特性 (主要有竞争不对称性和环境相关性 )及其影响因素 ,竞争与群落组成、结构和动态的关系。并对近几十年来生态学上关于植物竞争的争论焦点作了论述 ,即竞争对个体生长、繁殖和存活及群落演替的相对重要性 ,主要介绍了Grime、Newman&Tilman和Deborah&Ariel的 3种观点 ,其中Grime认为竞争不重要 ,相反Newman&Tilman认为竞争比较重要 ,Deborah&Ariel则提出了资源动态两阶段说 ,认为竞争重要与否取决于两个条件 :一为植物对土壤资源的吸收利用与非生物因素两者分别在多大程度上决定了资源可利用性的渐次降低 ;二为资源正波动期因竞争引起的生长量减少在多大程度上决定了资源负波动期个体的存活率     

The effect of injury and infection by Gibberella zeae on the polyacrylamide gel electrophoretic pattern of soluble proteins in potato tuber tissue

Polyacrylamide gel electrophoretic patterns of soluble proteinsfrom intact potato tubers and from wounded tuber tissue wereidentical. The patterns from diseased tissue showed some minordifferences not before 3–4 days after inoculation. Itis concluded that primarily proteins of minor fractions areinvolved in protein synthesis after wounding or infection. (Received March 22, 1969; )     

Low Resolution Structure of Glyceraldehyde 3-Phosphate Dehydrogenase

The structure of the holo enzyme shows that the four chemically identical sub-units are arranged with almost perfect 222 symmetry. There are indications, however, that the active centre regions might only be related in pairs.     

番茄碱对棉铃虫的毒性作用机理初探

采取荧光光谱法分析了番茄碱及虫体内钙调蛋白的图谱,从钙调蛋白的角度探讨了番茄碱的作用机理.结果显示:(1)番茄碱对棉铃虫具有毒性,随浓度的增加及饲喂时间的延长,对棉铃虫的杀伤力增强;(2)番茄碱对虫体内钙调蛋白的影响较大,随番茄碱浓度的增加,钙调蛋白的含量逐渐降低;(3)钙离子的加入增强了钙调蛋白的刚性,荧光图谱出现了红移(由350 nm移至416.58 nm);(4)番茄碱的加入破坏了钙调蛋白-钙离子复合物的刚性,荧光图谱出现了蓝移(416.58 nm移至377.65 nm).以上可以说明,番茄碱可能作为钙调蛋白的拮抗剂,拮抗钙调蛋白被钙离子激活的位点,影响其与靶酶的结合而发挥作用.此项的研究为探讨番茄碱的杀虫机理提供了科学依据.     

Proteolytic activity in the ectoperitrophic fluid of blood-fed Culex nigripalpus

In blood-fed Culex nigripalpus Theobald, proteolytic activity appeared in the ectoperitrophic fluid after 3 h, but only after 6 h in a homogenate of the blood-filled midgut. The activity continued to be higher in ectoperitrophic fluid than in whole gut homogenate until about 40 h after the meal, when most of the intact clot had disappeared. Apparently, undigested blood inhibits proteolytic activity. The blood clot lacked activity and the inhibitor could not be removed by washing. The results are compatible with a hypothesis that the peritrophic membrane separates the digestion from the ingestion compartment.     

Gene flow and genetic structure of the aquatic macrophyte Sparganium emersum in a linear unidirectional river

1. River systems offer special environments for the dispersal of aquatic plants because of the unidirectional (downstream) flow and linear arrangement of suitable habitats.
2. To examine the effect of this flow on microevolutionary processes in the unbranched bur-reed ( Sparganium emersum ) we studied the genetic variation within and among nine (sub)populations along a 103 km stretch of the Niers River (Germany–The Netherlands), using amplified fragment length polymorphisms.
3. Genetic diversity in S. emersum populations increased significantly downstream, suggesting an effect of flow on the pattern of intrapopulation genetic diversity.
4. Gene flow in the Niers River is asymmetrically bidirectional, with gene flow being approximately 3.5 times higher in a downstream direction. The observed asymmetry is probably caused by frequent hydrochoric dispersal towards downstream locations on the one hand, and sporadic zoochoric dispersal in an upstream direction on the other. The spread of vegetative propagules (leaf and stem fragments) is probably not an important mode of dispersal for S. emersum , suggesting that gene flow is mainly via seed dispersal. Realized dispersal distances exceeded 60 km, revealing a potential for long-distance dispersal in S. emersum .
5. There was no correlation between geographical and genetic distances among the nine S. emersum populations (i.e. no isolation by distance), which may be due to the occurrence of long-distance dispersal and/or colonization and extinction dynamics in the Niers River.
6. Overall, the genetic population structure and regional dispersal patterns of S. emersum in the Niers River are best explained by a linear metapopulation model. Our study shows that flow can exert a strong influence on population genetic processes of plants inhabiting stream systems.