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.     

河南淅川始新世核桃园组兔类化石

这里记述了河南淅川核桃园组中两种始新世兔类:石皮沟壮兔 (Strenulagus shipigouensis gen. et sp. nov.) 和丹江卢氏兔 (Lushilagus danjiangensis sp. ov.).从这些原始兔类标本上似可证实:上前臼齿和臼齿的中央主尖分别相当于前尖(或并尖)和后尖;两者的舌侧沟(次沟)似乎不同源.兔类上臼齿上的外凹、釉质圆环和舌侧沟的出现,是与三角座和跟座之间沟的形变密切相关.     

延胡索分类的化学证据

东阳产延胡索与大连产齿瓣延胡索经成分分离和TLC、HPLC对比,发现延胡索以啊扑啡类生物碱如glaucine为主,而齿瓣延胡索则含corynoline类生物碱。根据生物碱的类型及含量比较,二者有明显差异,结合延胡索的植物形态和植化分类特征判断,将延胡索作为与齿瓣延胡索近缘的独立种处理较为合理,即为Corydalis yanhusuo W. T. Wang ex Z.Y. Su et C. Y. Wu     

龟鳖类寄生血簇虫六新种

血簇虫(Haemogregarina Danilewsky,1885)属真球虫目(Eucoccidia)血簇虫科(Haemogregarinidae),这一属的寄生虫,其寄主以爬行动物为主,两栖动物和鱼类也有寄生。至今已记载有300余种。龟鳖类的血簇虫研究,国内尚无报道。作者在1984年3月—1985年3月,对我国龟鳖类寄生的血簇虫进行了调查研究,共解剖检查了中华     

甘蓝型油菜芥酸和二十碳烯酸含量的基因效应

以甘蓝型油菜的4种纯合芥酸基因型之间所有可能的6个杂交组合的P_1、P_2、F_1、P_2、B_1和B_2世代为材料,用生统遗传学方法研究了芥酸和二十碳烯酸的基因作用形式及效应。发现无论亲本是单基因差异还是二基因差异,F_1和F_2代的芥酸含量都接近中亲值,F_1略大于中亲值和F_(20)世代均值分析表明,芥酸含量的遗传符合加性显性模型,加性效应占绝对优势,显性效应不显著。用数量遗传学方法估计的芥酸基因数与已知的结果相近。     

四川宝兴雉类生态和垂直分布的调查研究

宝兴位于四川盆地西缘山地,境内纵贯世界闻名的大雪山——即夹金山。 自19世纪30年代至20世纪30年代,先后有Verreaux(1838—1871),Geoffroy(1866),David(1871),Seinhoe(1871),Sharpe(1875),David et Oustalet(1877),Oustaler (1891—92),Styan(1899),Laubmann(1920),La Touch(1925—30),Smith(1931—34),Bangs(1932),Seys(1934)等对宝兴进行过调查和采集,而我     

刺激隐神经中C类纤维诱发的小脑浦肯野细胞简单锋电位反应

用玻璃微电极记录了猫小脑浦肯野细胞的简单锋电位(PC-SS)。在标准化互协方差函数图中,PC-SS自发放电无明显波峰;弱刺激隐神经只引起A类纤维传入时,PC-SS出现A类诱发放电反应(A-CED),它包括潜伏期为16.7±0.9ms的早反应和270.8±12.8ms的晚反应。用极化电流选择性阻滞A类纤维传导后,强刺激只引起C类纤维单独传入时,出现潜伏期为142.4±4.3ms的C类诱发反应(C-CED)。强刺激同时引起A类和C类纤维传入时,只出现A-CED而不出现C-CED。按标准化功率谱密度函数分析,PC-SS自发放电可分为两种类型。一类为高峰型,最大能量峰值平均为15.7±4.7×10~(-3),峰频为4.07±1.67Hz;刺激A类纤维使峰值增大,而刺激C类纤维却使峰值减小。另一类为低峰型,峰值为8.4±1.4×10~(-3),峰频为3.67±2.90Hz。刺激A类和C类纤维均使峰值增大,前者增大更多,但峰频均无显著性变化。上述结果表明,C类纤维传入可以到达小脑浦肯野细胞,引起特异的PC-SS放电反应。     

强化后期氮素营养对提高水稻结实率及改善米质的作用

加强后期氮素营养能提高杂交水稻碳氨同化能力和结实率,稻米的蛋白质和八种必需氨基酸含量、谷类蛋白的赖氨酸和苏氨酸也有提高。