Warming up the system: higher predator feeding rates but lower energetic efficiencies

Predictions on the consequences of the rapidly increasing atmospheric CO₂ levels and associated climate warming for population dynamics, ecological community structure and ecosystem functioning depend on mechanistic energetic models of temperature effects on populations and their interactions. However, such mechanistic approaches combining warming effects on metabolic (energy loss of organisms) and feeding rates (energy gain by organisms) remain a key, yet elusive, goal. Aiming to fill this void, we studied the metabolic rates and functional responses of three differently sized, predatory ground beetles on one mobile and one more resident prey species across a temperature gradient (5, 10, 15, 20, 25 and 30 °C). Synthesizing metabolic and functional‐response theory, we develop novel mechanistic predictions how predator–prey interaction strengths (i.e., functional responses) should respond to warming. Corroborating prior theory, warming caused strong increases in metabolism and decreases in handling time. Consistent with our novel model, we found increases in predator attack rates on a mobile prey, whereas attack rates on a mostly resident prey remained constant across the temperature gradient. Together, these results provide critically important information that environmental warming generally increases the direct short‐term per capita interaction strengths between predators and their prey as described by functional‐response models. Nevertheless, the several fold stronger increase in metabolism with warming caused decreases in energetic efficiencies (ratio of per capita feeding rate to metabolic rate) for all predator–prey interactions. This implies that warming of natural ecosystems may dampen predator–prey oscillations thus stabilizing their dynamics. The severe long‐term implications; however, include predator starvation due to energetic inefficiency despite abundant resources.     

世界主要国家耕地动态变化及其影响因素

在世界人口持续攀升、全球耕地面积不断减少的背景下,探讨世界主要国家耕地变化其影响因素,对于分析预测未来世界耕地变化趋势、研究世界粮食安全具有积极意义。选择2050年人口过亿的17个国家和耕地面积排名前10的国家为研究对象,在分析1961—2007年耕地总量变化、人均耕地变化的基础上,探讨了耕地变化影响因素。研究结果表明,从20世纪60年代到2007年间的不同时期内,有越来越多的国家表现出耕地减少趋势,而人均耕地面积减少的国家个数高达90%以上。满足人口消费需求、城市化与经济发展是大多数国家耕地总量变化的主要动力;而人口快速增长、城市化则是导致许多国家人均耕地显著减少的重要原因。     

卒中单元护理管理模式在神经内科病房中的应用及康复效果评价

目的：探讨卒中单元管理模式对卒中患者康复效果的影响,并对此进行效果评价。方法：采用统计比较的方法,依据诊断标准,选取200例脑卒中患右,平均分为对照组和普通组,从康复依从性、生活能力、心理状态、平均住院日和住院费用进行分析。结果：对两组卒中患者进行康复依从性、生活能力、心理状态、平均住院日和住院费用进行统计分析,对照组与普通组间存在较大差异,有统计学意义。结论-卒中单元管理模式对脑卒中患者的康复有促进作用。     

关中-天水经济区生态系统服务权衡与协同关系

陆地表层植被作为生态系统主体,具有调节气候、水文调节、净化水质、保持水土等生态系统服务。理解生态系统服务权衡与协同的表现类型、形成机理、尺度依存和区域差异,对于制定区域发展与生态保护"双赢"的政策措施具有重要意义。以关天经济区为主要研究对象,利用相关模型,计算关天经济区生态系统NPP,固碳释氧,水文调节,水土保持,粮食生产等生态系统服务价值,利用ESCI和ESSI两个指数研究其生态系统服务价值时空变化,利用相关系数和空间制图的方法研究它们之间的相互权衡协同关系。结果表明:从时间角度分析,各项生态服务价值都呈现逐渐增加的趋势;从空间角度分析,2000年和2010年存在相似的空间分布格局,从北向南,NPP和固碳释氧的价值逐渐增大,水土保持价值变化量的大小也呈现不断增加的趋势,北部变化量小,南部变化量大,水文调节价值从西向东增大,从北向南增大,粮食生产价值量最小的是西安市市区,粮食生产价值量最大的是西安市的郊区和郊县及咸阳市。2000年到2010年间,调节型生态系统服务与供给型生态系统服务之间存在着此消彼长的权衡关系;各个区县的总生态服务价值指数从北向南、从西向东是不断增大的。     

Effects of Hydration on Steric and Electric Charge-Induced Interstitial Volume Exclusion—a Model

The presence of collagen and charged macromolecules like glycosaminoglycans (GAGs) in the interstitial space limits the space available for plasma proteins and other macromolecules. This phenomenon, known as interstitial exclusion, is of importance for interstitial fluid volume regulation. Physical/mathematical models are presented for calculating the exclusion of electrically charged and neutral macromolecules that equilibrate in the interstitium under various degrees of hydration. Here, a central hypothesis is that the swelling of highly electrically charged GAGs with increased hydration shields parts of the neutral collagen of the interstitial matrix from interacting with electrically charged macromolecules, such that exclusion of charged macromolecules exhibits change due to steric and charge effects. GAGs are also thought to allow relatively small neutral, but also charged macromolecules neutralized by a very high ionic strength, diffuse into the interior of GAGs, whereas larger macromolecules may not. Thus, in the model, relatively small electrically charged macromolecules, such as human serum albumin, and larger neutral macromolecules such as IgG, will have quite similar total volume exclusion properties in the interstitium. Our results are in agreement with ex vivo and in vivo experiments, and suggest that the charge of GAGs or macromolecular drugs may be targeted to increase the tissue uptake of macromolecular therapeutic agents.     

Fire legacies in eastern ponderosa pine forests

Disturbance legacies structure communities and ecological memory, but due to increasing changes in disturbance regimes, it is becoming more difficult to characterize disturbance legacies or determine how long they persist. We sought to quantify the characteristics and persistence of material legacies (e.g., biotic residuals of disturbance) that arise from variation in fire severity in an eastern ponderosa pine forest in North America. We compared forest stand structure and understory woody plant and bird community composition and species richness across unburned, low‐, moderate‐, and high‐severity burn patches in a 27‐year‐old mixed‐severity wildfire that had received minimal post‐fire management. We identified distinct tree densities (high: 14.3 ± 7.4 trees per ha, moderate: 22.3 ± 12.6, low: 135.3 ± 57.1, unburned: 907.9 ± 246.2) and coarse woody debris cover (high: 8.5 ± 1.6% cover per 30 m transect, moderate: 4.3 ± 0.7, low: 2.3 ± 0.6, unburned: 1.0 ± 0.4) among burn severities. Understory woody plant communities differed between high‐severity patches, moderate‐ and low‐severity patches, and unburned patches (all p < 0.05). Bird communities differed between high‐ and moderate‐severity patches, low‐severity patches, and unburned patches (all p < 0.05). Bird species richness varied across burn severities: low‐severity patches had the highest (5.29 ± 1.44) and high‐severity patches had the lowest (2.87 ± 0.72). Understory woody plant richness was highest in unburned (5.93 ± 1.10) and high‐severity (5.07 ± 1.17) patches, and it was lower in moderate‐ (3.43 ± 1.17) and low‐severity (3.43 ± 1.06) patches. We show material fire legacies persisted decades after the mixed‐severity wildfire in eastern ponderosa forest, fostering distinct structures, communities, and species in burned versus unburned patches and across fire severities. At a patch scale, eastern and western ponderosa system responses to mixed‐severity fires were consistent.     

Novel GAA sequence variant c.1211 A > G reduces enzyme activity but not protein expression in infantile and adult onset Pompe disease

Pompe disease is a clinically and genetically heterogeneous autosomal recessive disorder caused by lysosomal acid α-glucosidase (GAA) deficiency. We report on two affected members of a non-consanguineous Caucasian family, including a classical infantile-onset patient with severe cardiomyopathy (IO) and his paternal grandmother with the adult-onset (AO) form. Two compound heterozygous sequence variants of the GAA gene were identified in each patient by mutation analyses (IO = c.1211A > G and c.1798C > T; AO = c.1211A > G and c.692 + 5G > T). For this study, the biochemical phenotype resulting from the missense mutation c.1211A > G in exon 8, which converts a highly conserved aspartate to glycine (p.Asp404Gly), was of specific interest because it had not been reported previously. Western blotting revealed a robust expression of all GAA isoforms in quadriceps muscle of both patients (fully CRIM positive), while enzymatic activity was 3.6% (IO) and 6.6% (AO) of normal controls. To further validate these findings, the c.1211A > G sequence variant was introduced in wild type GAA cDNA and over-expressed in HEK293T cells. Site-directed mutagenesis analyses confirmed that the mutation does not affect processing or expression of GAA protein, but rather impairs enzyme function. Similar results were reported for c.1798C > T (p.Arg600Cys), which further supports the biochemical phenotype observed in IO. The third mutation (c.692 + 5G > T, in intron 3) was predicted to affect normal splicing of the GAA mRNA, and qPCR indeed verified a 4-fold lower mRNA expression in AO. It is concluded that the novel sequence variant c.1211A > G results in full CRIM but significantly lower GAA activity, which in combination with c.1798C > T leads to infantile-onset Pompe disease. We surmise that the difference in disease severity between the two family members in this study is due to a milder effect of the intronic mutation c.692 + 5G > T (vs. c.1798C > T) on phenotype, partially preserving GAA activity and delaying onset in the proband (paternal grandmother).