The relationship between the reduction of nonstructural carbohydrate induced by defoliator and the growth and mortality of trees

Large scale herbivorous insect outbreaks can cause death of regional forests, and the events are expected to be exacerbated with climate change. Mortality of forest and woodland plants would cause a series of serious consequences, such as decrease in vegetation production, shifts in ecosystem structure and function, and transformation of forest function from a net carbon sink into a net carbon source. There is thus a need to better understand the impact of insects on trees. Defoliation by insect pests mainly reduces photosynthesis (source decrease) and increases carbon consumption (sink increase), and hence causes reduction of nonstructural carbohydrate (NSC). When the reduction in NSC reaches to a certain level, trees would die of carbon starvation. External environment and internal compensatory mechanisms can also positively or negatively influence the process of tree death. At present, the research of carbon starvation is a hotspot because the increase of tree mortality globally with climate change, and carbon starvation is considered as one of the dominating physiological mechanisms for explaining tree death. In this study, we reviewed the definition of carbon starvation, and the relationships between the reduction of NSC induced by defoliation and the growth and death of trees, and the relationships among insect outbreaks, leaf loss and climate change. We also presented the potential directions of future studies on insect-caused defoliation and tree mortality.     

pH值对葡萄酒除铁与澄清的影响

葡萄酒采用菲丁除铁及单宁明胶澄清工艺中，葡萄酒的ｐＨ值是显影响除铁与澄清效果。经试验，菲丁除铁时ｐＨ３￣４为宜，单宁明胶澄清时将葡萄酒的ｐＨ值提高约０．２个单位就能达到澄清目的。     

蛋白激酶C与细胞增殖调控

介绍了蛋白激酶Ｃ家族的分子结构和基本酶学特征，以及在细胞信号传导、细胞增殖、转化和分化、程序死亡过程中的重要作用，探讨ＰＫＣ研究在临床肿瘤治疗中的意义。     

土壤中铁的根际效应及其吸收机理

本文介绍了近10年来土壤中铁的根际效应及其吸收机理,以及近几年来该领域的热点——植物铁载体方面的研究进展,并简要评述了今后的研究方向。     

玉米铁甲虫卵在玉米植株上的垂直分布及其二阶抽样技术研究

玉米铁甲虫Dactylispa setifera(chapuis)卵的调查技术,近年来一直沿用全株检查的简单随机抽样估计法,以一定玉米株的卵密度估计百株或全田卵量。为了达到抽样技术的“准确、迅速、简便、价廉”标准,就需对其生物学特性、作物生长期以及抽样理论进行综合研究。本文就虫卵的立体空间分布规律进行了探讨,提出了卵密度调查的二阶抽样技术,为该虫的预测预报和防治提供必要的依据。     

部分氧化的铁钼蛋白的圆二色散谱和电子顺磁共振谱的研究

棕色固氮菌固氮酶FeMo蛋白与过量（5－6个当量）的酸性靛蓝保温30－60分钟后,蛋白中的P－金属原子族全部氧化,然而蛋白中的FeMoCo全都处于还原状态。Na2S2O4使这种部分氧化的FeMo蛋白中的P-ciuster重新不,甲基紫精可加快这种还原,而亚甲蓝等氧化剂则使这种蛋白中的FeMoCo受到氧化,对这种部分氧化的FeMo蛋白分别进行CD还原滴定和测定氧化过程中的EPR／ABS的变化已经得到p-Cluster和FeMoCo的氧化还原当量数目。     

转铁蛋白结构与功能的研究——骆驼血清转铁蛋自的分离纯化及其含单一铁结合部位的结构域的制备和鉴定

分离纯化获得的骆驼血清转铁蛋白由分子量为73,000和63,000两个组分组成。两者至少N-端五肽顺序相同(Met-Pro-Asp-Lys-Thr)。骆驼血清转铁蛋白在生理pH下不能与人胎盘转铁蛋白受体结合。用胰蛋白酶酶解骆驼转铁蛋白可以同时得到两个合单一铁结合部位的结构域,分别来自转铁蛋白分子的N-端称N-端结构域(分子量34,700和40,700)和C-端称C-端结构域(分子量35,100)。在上述结果的基础上指出并讨论了反刍动物转铁蛋白在结构和功能上存在更多的共同性,而与其它哺乳动物的转铁蛋白有着明显的区别。