Bridging the gap between chemistry, physiology, and evolution: quantifying the functionality of sperm whale myoglobin mutants

This work merges a large set of previously reported thermochemical data for myoglobin (Mb) mutants with a physiological model of O₂-transport and -storage. The model allows a quantification of the functional proficiency of myoglobin (Mb) mutants under various physiological conditions, i.e. O₂-consumption rate resembling workload, O₂ partial pressure resembling hypoxic stress, muscle cell size, and Mb concentration, resembling different organism-specific and compensatory variables. We find that O₂-storage and -transport are distinct functions that rank mutants and wild type differently depending on O₂ partial pressure. Specifically, the wild type is near-optimal for storage at all conditions, but for transport only at severely hypoxic conditions. At normoxic conditions, low-affinity mutants are in fact better O₂-transporters because they still have empty sites for O₂, giving rise to a larger [MbO₂] gradient (more varying saturation curve). The distributions of functionality reveal that many mutants are near-neutral with respect to function, whereas only a few are strongly affected, and the variation in functionality increases dramatically at lower O₂ pressure. These results together show that conserved residues in wild type (WT) Mb were fixated under a selection pressure of low P_O2.     

Simple rules describe bottom-up and top-down control in food webs with alternative energy pathways

Many human influences on the world's ecosystems have their largest direct impacts at either the top or the bottom of the food web. To predict their ecosystem-wide consequences we must understand how these impacts propagate. A long-standing, but so far elusive, problem in this endeavour is how to reduce food web complexity to a mathematically tractable, but empirically relevant system. Simplification to main energy channels linking primary producers to top consumers has been recently advocated. Following this approach, we propose a general framework for the analysis of bottom-up and top-down forcing of ecosystems by reducing food webs to two energy pathways originating from a limiting resource shared by competing guilds of primary producers (e.g. edible vs. defended plants). Exploring dynamical models of such webs we find that their equilibrium responses to nutrient enrichment and top consumer harvesting are determined by only two easily measurable topological properties: the lengths of the component food chains (odd-odd, odd-even, or even-even) and presence vs. absence of a generalist top consumer reconnecting the two pathways (yielding looped vs. branched webs). Many results generalise to other looped or branched web structures and the model can be easily adapted to include a detrital pathway.     

茉莉酸甲酯和虫害诱导棉花对棉蚜及其天敌选择行为的影响

以棉蚜及其天敌十一星瓢虫、叶色草蛉为对象,通过Y型嗅觉仪测定了3种昆虫对不同味源物的行为反应。结果表明,健康棉株叶片对棉蚜的吸引作用与虫害棉叶和茉莉酸甲酯(MeJA)处理棉叶未存在显著性差异;十一星瓢虫和叶色草蛉对虫害棉叶的选择性是健康棉叶的2.7和2.2倍(P<0.001),对MeJA处理棉叶的选择性明显高于健康叶片(P<0.001),其中0.02μmol.mL-1处理的棉叶对天敌的吸引力最强,单一的MeJA对十一星瓢虫和叶色草蛉也具有吸引作用。     

一种净化水质的复合生物修复系统

在实验室内利用人工模拟方法,选择水蕹菜(Ipomoea aquatica)、泥鳅(Misgurus anguillicaudatus)、沼泽红假单胞菌(Rhodopseudomonas palustris)为工程物种,构建一套水生经济植物-水生动物-微生物复合生物修复系统进行污水修复,研究该系统中动植物生物量及水质指标的变化。结果表明,在23d的实验周期中,水体铵态氮(NH4+-N)下降96.5%,硝态氮(NO3--N)下降82.2%,总磷(TP)下降53.2%,化学需氧量(CODMn)下降24.5%。水蕹菜平均增重31.2%,泥鳅平均增重6.1%。这种复合的生物修复模式具有较好的经济效益与环境效益。     

Paper‐Based Energy‐Storage Devices Comprising Carbon Fiber‐Reinforced Polypyrrole‐Cladophora Nanocellulose Composite Electrodes

Composites of polypyrrole (PPy) and Cladophora nanocellulose, reinforced with 8 μm‐thick chopped carbon filaments, can be used as electrode materials to obtain paper‐based energy‐storage devices with unprecedented performance at high charge and discharge rates. Charge capacities of more than 200 C g^?1 (PPy) are obtained for paper‐based electrodes at potential scan rates as high as 500 mV s^?1, whereas cell capacitances of ～60–70 F g^?1 (PPy) are reached for symmetric supercapacitor cells with capacitances up to 3.0 F (i.e.,0.48 F cm^?2) when charged to 0.6 V using current densities as high as 31 A g^?1 based on the PPy weight (i.e., 99 mA cm^?2). Energy and power densities of 1.75 Wh kg^?1 and 2.7 kW kg^?1, respectively, are obtained when normalized with respect to twice the PPy weight of the smaller electrode. No loss in cell capacitance is seen during charging/discharging at 7.7 A g^?1 (PPy) over 1500 cycles. It is proposed that the nonelectroactive carbon filaments decrease the contact resistances and the resistance of the reduced PPy composite. The present straightforward approach represents significant progress in the development of low‐cost and environmentally friendly paper‐based energy‐storage devices for high‐power applications.     

Carbonized Chicken Eggshell Membranes with 3D Architectures as High‐Performance Electrode Materials for Supercapacitors

Supercapacitor electrode materials are synthesized by carbonizing a common livestock biowaste in the form of chicken eggshell membranes. The carbonized eggshell membrane (CESM) is a three‐dimensional macroporous carbon film composed of interwoven connected carbon fibers containing around 10 wt% oxygen and 8 wt% nitrogen. Despite a relatively low surface area of 221 m² g^?1, exceptional specific capacitances of 297 F g^?1 and 284 F g^?1 are achieved in basic and acidic electrolytes, respectively, in a 3‐electrode system. Furthermore, the electrodes demonstrate excellent cycling stability: only 3% capacitance fading is observed after 10 000 cycles at a current density of 4 A g^?1. These very attractive electrochemical properties are discussed in the context of the unique structure and chemistry of the material.     

蚕豆种子贮藏蛋白质组分的比较研究

以10份蚕豆品种为材料,利用SDS-PAGE方法,对其种子贮藏蛋白亚基组成进行了分析,结果表明:不同品种间的种子贮藏蛋白具有一定的差异,表现出一定的多态性;共分离出23条迁移率不同的亚基条带,13条具有多态性;利用贮藏蛋白亚基条带的信息,分析了品种间的蛋白相似度,相似度指数0.619～0.947,平均0.744;并通过聚类分析,在遗传相似系数0.8260水平上,将供试材料分为了3类,其中第2类具有较丰富的多样性,多样性指数达3.9296;共筛选出7对亲缘关系较远的杂交组合,可为蚕豆品种选育提供一定的科学依据。