不同红叶性状桃叶片花色素苷种类鉴定及呈色规律研究

以早熟桃(Prunus persica,‘早美’、‘春蕾’)和红叶桃(Prunus persica f.atropur purea,‘筑波5号’、‘洛格红叶’)两种不同叶片呈色类型桃品种为试材,在5~9月份对其呈色过程中叶片色泽、花色素组成进行了测定,并对其叶片色差值与色素组成间的相关性进行了分析,探讨早熟桃和红叶桃叶片呈色差异的生理机制。结果表明:(1)红叶桃叶片5月下旬叶片出现"返青"现象,叶片a*值由正值变为负值;相反早熟桃叶片6月份果实采收后叶片由鲜艳绿色逐渐变为红紫色,叶片a*值逐渐增大。(2)在试验所选的4个品种中共发现5类花色素苷,早熟桃含有3类,红叶桃含有4类,矢车菊素-3-葡萄糖苷和矢车菊素-3-芸香糖苷为两种类型桃叶片所共有的且含量相对较高的花色素苷;呈色过程中叶片花色素苷种类基本不变,但各色素含量发生了明显的变化。(3)多元回归分析显示:红叶桃叶片与早熟桃叶片的a*值分别与矢车菊素-3-葡萄糖苷、矢车菊素-3-芸香糖苷含量呈正相关关系,且均与Ant/Chl呈负相关关系。研究表明,矢车菊素为桃叶片呈现红色的物质基础,两种类型桃叶片呈色差异并非所含花色素苷种类不同所致,而与不同种类花色素苷含量有关。     

两种苹果砧木根系水力结构及其PV曲线水分参数对干旱胁迫的响应

研究干旱胁迫对平邑甜茶(Malus hupehensis)和楸子(Malus prunifolia)根系水力结构及其PV曲线水分参数的影响.设定正常与干旱2种水分处理,对2种苹果砧木进行氯化汞-巯基乙醇处理和压力室-容积(PV)曲线测定试验,并利用高压流速仪(HPFM),测定平邑甜茶和楸子根系水力结构.结果表明:随着水分胁迫的加重,平邑甜茶和楸子的根系导水率、根系叶比导水率、根系茎比导水率出现减少趋势.在适宜水分和重度干旱条件下,平邑甜茶根系叶比导水率分别为楸子根系叶比导水率的95％和92％,平邑甜茶根系茎比导水率分别为楸子根系茎比导水率的52％和62％,楸子与平邑甜茶相比在根系茎比导水率和根系叶比导水率上出现增加趋势.干旱胁迫可能会导致水通道蛋白的活性受到抑制,致使其根系导水率出现降低,继而导致了地上部分气体交换受到影响.严重干旱时,楸子与平邑甜茶相比可能具有更大的水孔蛋白表达量来抵御干旱胁迫.在2种水分条件下,楸子的初始质壁分离时的渗透势(ψstlp)、饱和含水时的渗透势(Ψssal)、初始质壁分离时的相对水含量(RWCtlp)、初始质壁分离时的相对渗透水含量(ROWCtlp)、组织细胞总体弹性模量(ε')值与平邑甜茶相比较均处于较低水平,束缚水含量(Va)值处在较高水平.对PV曲线水分参数进行隶属函数综合评价得出的△值为楸子大于平邑甜茶,平邑甜茶和楸子之间b值差异不明显.在适宜水分和重度干旱条件下楸子所体现出的输水策略优于平邑甜茶.PV曲线水分参数同苹果砧木根系的水力结构一样能够随着植物所处的环境做出相应的调整.对于PV曲线水分参数研究发现,楸子在膨压保持方面与平邑甜茶相比,其抗旱性优于平邑甜茶.     

Minimal cross-trial generalization in learning the representation of an odor-guided choice task

There is no single way to represent a task. Indeed, despite experiencing the same task events and contingencies, different subjects may form distinct task representations. As experimenters, we often assume that subjects represent the task as we envision it. However, such a representation cannot be taken for granted, especially in animal experiments where we cannot deliver explicit instruction regarding the structure of the task. Here, we tested how rats represent an odor-guided choice task in which two odor cues indicated which of two responses would lead to reward, whereas a third odor indicated free choice among the two responses. A parsimonious task representation would allow animals to learn from the forced trials what is the better option to choose in the free-choice trials. However, animals may not necessarily generalize across odors in this way. We fit reinforcement-learning models that use different task representations to trial-by-trial choice behavior of individual rats performing this task, and quantified the degree to which each animal used the more parsimonious representation, generalizing across trial types. Model comparison revealed that most rats did not acquire this representation despite extensive experience. Our results demonstrate the importance of formally testing possible task representations that can afford the observed behavior, rather than assuming that animals’ task representations abide by the generative task structure that governs the experimental design.     

肉食鸡中产超广谱β-内酰胺酶的耐药性大肠杆菌的检测和分析

[目的]本文对山东某屠宰场的肉食鸡内脏中的大肠杆菌进行了p-内酰胺类抗生素的耐药性监测和分析.[方法]从屠宰场的肉食鸡中获取内脏样品,处理并筛选得到对β-内酰胺类耐药的大肠杆菌.通过抑菌圈法对细菌耐药性进行分析.提取细菌DNA,进行系统发育亚型分析.检测并鉴定菌株中β-内酰胺酶基因和整合子的结构,并进行了接合转移实验....     

Temperature,size and developmental plasticity in birds

As temperatures increase, there is growing evidence that species across much of the tree of life are getting smaller. These climate change-driven size reductions are often interpreted as a temporal analogue of the observation that individuals within a species tend to be smaller in the warmer parts of the species'' range. For ectotherms, there has been a broad effort to understand the role of developmental plasticity in temperature–size relationships, but in endotherms, this mechanism has received relatively little attention in favour of selection-based explanations. We review the evidence for a role of developmental plasticity in warming-driven size reductions in birds and highlight insulin-like growth factors as a potential mechanism underlying plastic responses to temperature in endotherms. We find that, as with ectotherms, changes in temperature during development can result in shifts in body size in birds, with size reductions associated with warmer temperatures being the most frequent association. This suggests developmental plasticity may be an important, but largely overlooked, mechanism underlying warming-driven size reductions in endotherms. Plasticity and natural selection have very different constraining forces, thus understanding the mechanism linking temperature and body size in endotherms has broad implications for predicting future impacts of climate change on biodiversity.     

森林火灾污染物质释放及其影响研究进展

森林火灾是大气中气体污染物和颗粒物的重要来源,可对全球气候系统、大气环境以及生态系统产生重要影响,对全球温室气体和含碳颗粒物释放具有重要的贡献,是推动全球气候变化的重要因素。森林火灾释放污染物已成为区域乃至全球范围内重要污染源之一,这些污染物质与辐射、能见度以及温室效应等问题直接相关。准确地描述森林火灾释放的气体和颗粒污染物释放机理、释放总量、时空分布特征、不同尺度的扩散过程模拟,以及对区域大气环境的影响,对于量化森林火灾释放污染物总量及区域影响具有重要意义。基于森林火灾污染物质释放方面的国内外文献,从火灾释放的污染物质对环境的影响、森林火灾释放污染物定量化和传输路径监测的研究方法、污染物质的扩散和运输模型以及跨区域影响等几个方面进行了综述。森林火灾释放的CO、PM₁₀和PM_2.5对环境和人的生命安全造成巨大威胁,而且森林火灾释放的污染物质能够随气流长距离传输,不仅对当地的空气造成污染,污染物也能够随着气团进行长距离传输,并在传输过程与当地气溶胶混合,形成跨区域污染。森林火灾释放污染物扩散、传输模拟通过不同模型相互耦合完成,包括可燃物载量估算模型、可燃物消耗和释放模型、污染物扩散传输模型,以及污染物预测和可视化模型等。总结了国内外森林火灾释放污染物质主要研究方法,并展望了今后研究重点:目前我国关于森林火灾释放物质相关的研究尚不足以支撑我国森林火灾温室气体释放、污染物释放等方面的研究,并且我国目前还没有发展出适合于我国的森林火灾污染物释放模型,以及污染物扩散、传输系统。森林火灾排放因子库大多数引用国外研究结果,在一定程度上增加不确定性,缺乏森林火灾对区域大气环境影响的定量化研究。因此,今后我国应加强对森林火灾污染物质释放与影响的研究,尤其是污染物质扩散和传输模型的预测和可视化研究以及排放因子的测量。     

Nonfullerene n‐Type Organic Semiconductors for Perovskite Solar Cells

Compared to inorganic semiconductors and/or fullerene derivatives, nonfullerene n‐type organic semiconductors present some advantages, such as low‐temperature processing, flexibility, and molecule structure diversity, and have been widely used in perovskite solar cells (PSCs). In this research news article, the recent advances in nonfullerene n‐type organic semiconductors which function as electron‐transporting, interface‐modifying, additive, and light‐harvesting materials in PSCs are summarized. The remaining challenges and promising future directions of nonfullerene‐based PSCs are also discussed.     

Impacts of recreational trampling on sub-alpine vegetation and soils in Northwest Yunnan, China

Controlled trampling experiments were undertaken to assess impacts of recreation in a sub-alpine environment in an upper-Mekong mountainous protected area in China. Hiking and recreational horse-riding were applied at different trampling intensity to two typical, widespread vegetation types (Carex grassland and low Rhododendron shrubland) and trampling effects were assessed to study vegetation resistance and soil compaction. The results indicate: (1) low shrub vegetation is highly vulnerable to trampling damage while the graminoids-dominated grassland is more resistant; (2) dry soil with low organic matter, which often is found in the shrubland, is more susceptible to compaction than wet soil and (3) horses cause substantially more damage than hikers at equivalent trampling levels. These data are useful to develop a visitor’s management strategy that allows to minimize the impact from recreation on the vegetation.     

肌肉特异性基因启动子的上游转录调控元件研究进展

真核生物启动子位于基因5’端上游转录起始位点附近,是包含核心启动子以及上游转录调控元件的一段DNA序列,这些转录调控元件控制着基因表达的强度和特异性。肌肉特异性启动子的上游调控元件种类、数量和排列顺序决定着基因在肌肉中的特异性表达。深入研究肌肉启动子的上游调控元件,可以进一步了解肌肉基因表达机制,从而为肌肉性状的改良、增殖分化的机理和疾病的基因治疗等研究提供重要依据。该文回顾了近年来肌肉特异性启动子研究领域中的新发现,包括肌肉特异性启动子转录调控元件的分子机制、建立人工合成肌肉启动子的方法及应用,并探讨该领域中急需解决的问题和发展前景。