小麦根系特征对干旱胁迫的响应

干旱胁迫时, 小麦(Triticum aestivum)根系率先产生应激响应, 同时向地上部发出信号, 诱导地上部发生生理反应, 从而提高植株抗旱能力。根系构型包括平面几何性状和立体几何结构(即拓扑构型), 具有遗传稳定性和可塑性。干旱胁迫影响根系理化特性, 如根源化学信号、根系细胞酶类和根系渗透作用的响应。根系通过调整其解剖学结构和水分吸收动力等来适应干旱胁迫。该文从根系构型、理化特性和解剖学结构3个方面, 系统阐述了小麦根系特征对干旱胁迫的响应, 并探讨了其与干旱胁迫的关系和当前研究中存在的问题, 以期为相关研究提供参考。     

Hierarchical Dragonfly Wing: Microstructure-Biomechanical Behavior Relations

The dragonfly wing,which consists of veins and membrane,is of biological hierarchical material.We observed the cross-sections of longitudinal veins and membrane using Environmental Scanning Electron Microscopy (ESEM).Based on the experiments and previous studies,we described the longitudinal vein and the membrane in terms of two hierarchical levels of organization of composite materials at the micro- and nano-scales.The longitudinal vein of dragonfly wing has a complex sandwich structure with two chitinous shells and a protein layer,and it is considered as the first hierarchical level of the vein.Moreover,the chitinous shells are concentric multilayered structures.Clusters of nano-fibrils grow along the circumferential orientation embedded into the protein layer.It is considered as the second level of the hierarchy.Similarly,the upper and lower epidermises of membrane constitute the first hierarchical level of organization in micro scale.Similar to the vein shell,the membrane epidermises were found to be a paralleled multilayered structure,defined as the second hierarchical level of the membrane.Combining with the mechanical behavior analysis of the dragonfly wing,we concluded that the growth orientation of the hierarchical structure of the longitudinal vein and membrane is relevant to its biomechanical behavior.     

A novel and stable "two-hit" acute lung injury model induced by oleic acid in piglets

Background  

Children are susceptible to pulmonary injury, and acute lung injury (ALI) often results in a high mortality and financial cost in pediatric patients. Evidence has showed that oleic acid (OA) plays an important role in ALI. Therefore, it has special significance to study ALI in pediatric patients by using OA-induced animal models. Unfortunately, the animal model hs a high mortality due to hemodynamic instability. The aim of this study was to establish a novel hemodynamically stable OA-induced ALI model in piglets with two hits.     

Elevated temperature and waterlogging decrease cottonseed quality by altering the accumulation and distribution of carbohydrates,oil and protein

Soil waterlogging and high‐temperature events have occurred simultaneously in recent years in the Yangtze River basin cotton belt region of China, negatively affecting the development and quality of cottonseed. This study investigated the effects of the combination of elevated temperature (ET) (34.1/29.0°C) and waterlogging (3 or 6 days) on the accumulation and distribution of oil, protein and carbohydrates in cottonseed during flowering and boll development. The results showed that ET resulted in greater decreases in cottonseed biomass under waterlogging than under control conditions. The combination of waterlogging and ET significantly limited the accumulation of carbohydrates and oil contents. However, ET promoted protein accumulation and compensated for the negative effects of 3‐day waterlogging on the final protein content. The combined ET and 6‐day waterlogging significantly decreased the final contents of oil and protein by limiting carbon flux and NADPH supply because of the decreased activities of phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) and glucose‐6‐phosphate dehydrogenase (G6PDH, EC 1.1.1.49). The PEPC activity was correlated more with protein content than oil content. In addition, simultaneous exposure to waterlogging and ET resulted in lower unsaturated fatty acid/saturated fatty acid ratios and essential amino acid/non‐essential amino acid ratios than did exposure to the individual factors alone. These findings could provide the theoretical support for the prospective assessment of effects of high temperature and waterlogging stresses on cotton production under climate change, and they can help to develop effective techniques in cotton cultivation.     

基于“策略—反馈”的琶洲中东区韧性城市设计

珠江三角洲（简称“珠三角”）城市普遍受到气候变化和城市扩张的干扰，广州琶洲中东区作为珠三角的微观城市组团，是珠三角韧性演进表达的载体，以其为例探索整合城市与生态环境的韧性设计机制。首先辨析了城市韧性的分析方法、策略及评价体系，对珠三角的脆弱性进行背景研究；然后通过对琶洲中东区的脆弱性分析和灾害模拟，提出3 个层次的韧性整合策略，包括连接现有破碎的蓝绿系统的结构性策略，构建基于公共交通为导向（TODs）、垂直水岸的步行可达空间的连接方式以及分散式雨水存储系统与多用堤岸模式的节点处理；最后利用GIS、Fragstats 和Depthmap 等软件平台和数据分析手段，对韧性策略和设计方案进行评估并给予反馈，从而构建起微观城市组团层面全过程的“分析—策略—方案—反馈”的韧性城设计框架。结果表明：运用基于“策略—反馈”机制的方案设计有助于提升景观连接度、空间集成度，有效适应洪涝干扰，更好地落实城市韧性。