气孔特征与叶片功能性状之间关联性沿海拔梯度的变化规律——以长白山为例

气孔是陆生植物与外界环境进行水分和气体交换的主要通道,控制着植物的光合作用和蒸腾过程。植物往往通过多种性状的组合来适应变化的环境,叶片功能性状之间的紧密关系已经在不同尺度得到证实。然而,植物气孔特征与叶片其它功能性状是否存在关联性以及这种关联性是否会受到环境变化梯度的影响仍鲜少报道。沿长白山北坡6个海拔梯度,测定了150种植物的气孔特征和叶片功能性状。结果发现,气孔密度(SD)与比叶面积(SLA)负相关,与单位面积的叶氮含量(N_(area))正相关;除了SLA和N_(area)外,气孔长度(SL)与SLA、叶片厚度(LT)和单位质量的叶氮含量(N_(mass))均存在显著的相关性(P0.05)。然而,气孔特征与叶片功能性状的相关性只在部分海拔梯度存在。此外,发现SD与SL之间存在稳定一致的负相关关系。这些结果表明,植物气孔特征与叶片形态和化学特征对环境变化的适应存在一定的协同变异性,但这种关系不具有普适性,主要与气孔特征和叶片功能性状的选择压力存在差异以及物种分布范围相关。未来仍需要在更多物种和不同区域内来验证气孔特征与植物功能性状之间的关联关系。     

Changes in interspecies association patterns of Atlantic bottlenose dolphins,Tursiops truncatus,and Atlantic spotted dolphins,Stenella frontalis,after demographic changes related to environmental disturbance

Animal populations can be affected by environmental disturbances in many ways including demographic and behavioral changes. This can affect interspecies associations for regularly interacting sympatric species, like bottlenose and spotted dolphins in the Bahamas (observed since 1985 and interspecies associations analyzed since 1993). After two hurricanes in 2004 each species lost roughly 30% of their respective communities resulting in differing social structure and behavioral changes. During mixed species encounters (MSE) group sizes for spotted dolphins ( = 14.1 ± 9.2) were significantly larger than bottlenose dolphins ( = 6.0 ± 7.3; F = 11.74, df = 1, P < 0.001), however, t‐tests revealed no differences between aggressive vs. affiliative encounters. Sexual/aggressive behavior regularly seen previously was not observed posthurricanes and aggressive encounters were greatly reduced. Generally results were similar to prehurricane data including high resightings of spotted dolphins with male alliances prevalent (including new juvenile alliances seen only posthurricane), and individualized bottlenose participation with few male alliances. However temporal associations varied compared to prehurricane. Interspecies association and behavior patterns were altered and likely affected by the changes in intraspecies association patterns following the hurricanes. However both species still participated in MSE, suggesting this is an important component of their ability to coexist as sympatric species.     

Interspecies gene transfer provides soybean resistance to a fungal pathogen

Fungal pathogens pose a major challenge to global crop production. Crop varieties that resist disease present the best defence and offer an alternative to chemical fungicides. Exploiting durable nonhost resistance (NHR) for crop protection often requires identification and transfer of NHR‐linked genes to the target crop. Here, we identify genes associated with NHR of Arabidopsis thaliana to Phakopsora pachyrhizi, the causative agent of the devastating fungal disease called Asian soybean rust. We transfer selected Arabidopsis NHR‐linked genes to the soybean host and discover enhanced resistance to rust disease in some transgenic soybean lines in the greenhouse. Interspecies NHR gene transfer thus presents a promising strategy for genetically engineered control of crop diseases.     

环境微生物群落结构与功能多样性研究方法

微生物群落的结构及群落内种间相互作用是影响其生态功能的决定性因素。尽管微生物群落是地球生物化学循环的主要驱动者,但是由于传统的微生物培养方法只能分离约1%10%的环境微生物,对复杂的环境微生物群落结构和功能多样性了解甚少。元基因组学、单细胞分析和群落遗传学等方法的出现,及其与微生物学的交叉融合,使得人们能够从微生物群落组成、物种功能、种间相互作用和预测模型等方面分析微生物群落。重点综述了元基因组学、单细胞分析和群落遗传学等方法及其在环境微生物群落结构和功能多样性中的应用进展。     

Application of Uncertainty Factors in the Priority Substances Program and International Harmonization

The Canadian Environmental Protection Act (CEPA) authorizes the Ministers of the Environment and of Health in Canada to investigate a wide variety of substances that may contaminate the environment and cause adverse effects on the environment and/or on human health. Under the Act, assessments have been completed for 44 environmental contaminants on the first Priority Substances List (PSL) and are relatively advanced for 25 compounds on the second PSL. The principles developed for the application of uncertainty factors in assessment of risks to human health for Priority Substances under CEPA are outlined, with emphasis on those aspects which are somewhat unique and/or evolving. The interface of developments in the Priority Substances program with an initiative of the International Programme on Chemical Safety in this area to effect greater harmonization of approaches is also described.     

Optimization of Synthetic Proteins: Identification of Interpositional Dependencies Indicating Structurally and/or Functionally Linked Residues

Protein alignments are commonly used to evaluate the similarity of protein residues, and the derived consensus sequence used for identifying functional units (e.g., domains). Traditional consensus-building models fail to account for interpositional dependencies – functionally required covariation of residues that tend to appear simultaneously throughout evolution and across the phylogentic tree. These relationships can reveal important clues about the processes of protein folding, thermostability, and the formation of functional sites, which in turn can be used to inform the engineering of synthetic proteins. Unfortunately, these relationships essentially form sub-motifs which cannot be predicted by simple “majority rule” or even HMM-based consensus models, and the result can be a biologically invalid “consensus” which is not only never seen in nature but is less viable than any extant protein. We have developed a visual analytics tool, StickWRLD, which creates an interactive 3D representation of a protein alignment and clearly displays covarying residues. The user has the ability to pan and zoom, as well as dynamically change the statistical threshold underlying the identification of covariants. StickWRLD has previously been successfully used to identify functionally-required covarying residues in proteins such as Adenylate Kinase and in DNA sequences such as endonuclease target sites.     

长江宜宾江段铜鱼属鱼类种间食物关系

采用碳、氮稳定同位素技术对2012年4-5月长江宜宾江段铜鱼和圆口铜鱼的食物组成进行了分析,并利用多元统计分析方法探讨了铜鱼和圆口铜鱼种间食物关系,包括饵料相似性指数、重叠系数及2种鱼的摄食器官形态差异对食物组成的影响.结果表明:1)铜鱼的δ13C和δ15N变化范围分别为-21.15‰～-20.31‰和9.67‰～ 10.21‰,为偏动物性的杂食性鱼类;圆口铜鱼的δ13C和δ15N分别为-23.30‰～-21.18‰和7.40‰～ 9.21‰,相对铜鱼为偏植物性的杂食性鱼类,铜鱼和圆口铜鱼均与传统肠含物分析的结果存在一定的差异;2)两种鱼的食物相似性指数和食物重叠系数分别为78.7％和55.6％;3)主成分分析(PCA)表明,铜鱼和圆口铜鱼摄食器官形态特征存在一定的差异.长江宜宾江段铜鱼和圆口铜鱼种间竞争不激烈,作为向家坝蓄水前最后一次对长江宜宾江段铜鱼和圆口铜鱼食性及种间食物关系的调查,研究结果可为分析向家坝蓄水对宜宾江段鱼类营养结构的影响提供数据参考.     

崖柏群落优势乔木树种种间关系

采用样方调查法,对组成崖柏群落的乔木树种进行调查。通过计算重要值确定崖柏群落优势乔木树种,研究优势树种的总体联结性、2物种间的联结性和种间协变。结果表明:崖柏群落内的15个优势树种总体间存在负关联;2物种间具有显著正联结的种对有:高山栎-川陕鹅耳枥、高山栎-华中八角、大叶青冈-乌岗栎、铁杉-华西花楸、华千金榆-青榨槭、华千金榆-大叶青冈、大叶青冈-川鄂山茱萸、川陕鹅耳枥-华中八角;呈显著负联结的种对是高山栎-青榨槭;崖柏与其他优势树种的联结性均未达到显著程度;有26个种对表现出明显的正协变,12个种对表现出明显的负协变;种对正协变的存在是由于这些物种对环境资源的利用具有相似性所致。     

中国特有植物——华南五针松群落的种间关系

采用连续样带取样法,在分析广东南岭华南五针松群落结构的基础上,测定了优势种群的种间协变系数,并将典范对应分析（Canonical Correspondence Analysis,CCA）和聚类分析（Cluster Analysis）相结合,探讨了华南五针松与群落中其它种群的种间相互关系.结果表明：（1）广东南岭华南五针松群落以A级频度占绝对优势,华南五针松在主林层占据显著地位,但在演替层和更新层中的优势远不及其他优势种群;（2）Spearman秩相关分析和相关分析的计算结果基本一致,华南五针松群落优势种群正协变种对数显著多于负协变的种对数,且Spearman秩相关比相关分析具有更高的灵敏度.华南五针松与长叶木姜存在显著负协变,与其它优势种群种对间协变关系不明显;（3）海拔高度、坡度、坡位、坡形、腐殖质层厚度以及枯枝落叶层厚度与3个排序轴都有较强的相关性,环境因子在第一和第二排序轴的位置明显反映其生态特点.105 个乔木种类沿第一排序轴的分类完全与物种的性状特征相符.海拔高度是影响华南五针松分布的主导因素;（4）华南五针松群落种间关系揭示了群落内不同乔木种类因受小生境因子影响而体现在空间分布上的差异.典范对应分析和聚类分析结果共同揭示环境因子影响物种的分布,并通过生态习性表达出来.