重点脆弱生态区生态系统服务权衡与协同关系时空特征

目前,有关生态系统服务权衡与协同关系的研究多集中在局地尺度,在宏观尺度上的研究较少。重点脆弱生态区是我国改善生态环境的主要目标区域,在定量评估我国重点脆弱生态区1990—2015年土壤保持、植被净初级生产力(NPP)和产水服务的基础上,利用相关系数法并结合植被分布场数据对生态系统服务权衡与协同关系进行研究。结果表明:(1)26年间,重点脆弱生态区的土壤保持服务、NPP、产水服务呈现出南多北少的分布格局,且3种服务的年际变化较小,但均有上升的趋势;(2)重点脆弱生态区的3种生态系统服务之间是整体上协同,局部权衡的关系,并且协同关系呈减弱的趋势;(3)生态恢复区的生态系统服务的协同程度大于非生态恢复区,权衡关系减弱的动态变化趋势高于非生态恢复区。定量评估生态系统服务权衡与协同关系的时空特征,有利于研究生态系统服务之间相互关系在时间上的非线性和空间上的异质性,对重点脆弱生态区生态系统的可持续发展具有重要意义。     

典型脆弱生态区生态技术评价方法及应用专题导读

全球经济发展和日益增强的人类活动给业已脆弱的生态系统带来了巨大挑战,寻求尊重自然规律、环境友好的生态治理与恢复技术成为实现联合国可持续发展目标的重要组成部分。近年来,国内外科学家和生态治理机构研发出了一系列技术体系和技术模式,对脆弱生态区退化生态系统展开了全面的治理和恢复。然而,缺乏对这些治理技术的评价和优选方法的研发和应用在很大程度上限制了优良技术的筛选和推广应用,造成了资金和人力的浪费和损失。针对这些问题,科技部在2016年启动了国家重点研发计划项目"生态技术评价方法、指标体系与全球生态治理技术评价",其中重要的任务之一是对生态技术进行梳理、评价和优选。本文旨在对已有的评价方法和指标体系的研究进展进行系统梳理,对生态技术的特征、生态技术评价的基本步骤和原则、生态技术的三阶段评估方法等进行了界定和深入分析,对本专题收录的14篇学术文章所涵盖的评价方法和模型研发、案例应用等进行了介绍,以期为筛选优良技术、提高生态技术应用效果、促进优良技术的输出和引进提供参考。     

中国典型生态脆弱区生态化学计量学研究进展

在人类活动和自然环境变化的相互作用下,生态脆弱区生态系统随之变迁,荒漠化、盐碱化、水土流失、植被生产力下降等是生态脆弱区面临的重要问题。生态化学计量学作为当前多学科交叉研究的热点领域,强调从生态系统能量与元素平衡角度,揭示元素生物地球化学循环和生态系统对环境变化的调控机制。为了促进对生态脆弱区碳（C）、氮（N）、磷（P）生态化学计量的深入理解,本文重点总结了近年来有关我国典型生态脆弱区植物、凋落物、土壤和土壤微生物量C、N、P生态化学计量及其对环境变化响应的研究成果,并展望未来研究方向,以期促进生态化学计量学的发展和生态脆弱区生态保护与恢复研究。研究表明,植物-凋落物-土壤-土壤微生物系统C、N、P化学计量具有较强相关性,并受土壤因子、气候因子、生物因子和人类活动的显著影响。在生态脆弱区,我国北方荒漠及荒漠化地区由于较高的N∶P比值易受P限制,而青藏高原脆弱区、西南岩溶石漠化地区和黄土高原脆弱区等生态脆弱区更易受N限制;随着植被恢复,养分限制逐渐由N限制向P限制转变。生态脆弱区相对较低的养分含量和C∶N∶P比值或许可在一定程度上解释植被生产力较低的原因,而具有较高N、P化学计量内稳性的植物在贫瘠环境中具有较强竞争力和更高稳定性。今后可加强多尺度、不同生态系统植物-凋落物-土壤-土壤微生物系统生态化学计量和长期、多因子交互控制实验的研究。     

Regional specificity of the gut-incretin response to small intestinal glucose infusion in healthy older subjects

The importance of the region, as opposed to the length, of small intestine exposed to glucose in determining the secretion of the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) remains unclear. We sought to compare the glycemic, insulinemic and incretin responses to glucose administered to the proximal (12–60 cm beyond the pylorus), or more distal ( > 70 cm beyond the pylorus) small intestine, or both. 10 healthy subjects (9M,1F; aged 70.3 ± 1.4 years) underwent infusion of glucose via a catheter into the proximal (glucose proximally; GP), or distal (glucose distally; GD) small intestine, or both (GPD), on three separate days in a randomised fashion. Blood glucose, serum insulin and plasma GLP-1, GIP and CCK responses were assessed. The iAUC for blood glucose was greater in response to GPD than GP (P < 0.05), with no difference between GD and GP. GP was associated with minimal GLP-1 response (P = 0.05), but substantial increases in GIP, CCK and insulin (P < 0.001 for all). GPD and GD both stimulated GLP-1, GIP, CCK and insulin (P < 0.001 for all). Compared to GP, GPD induced greater GLP-1, GIP and CCK responses (P < 0.05 for all). Compared with GPD, GD was associated with greater GLP-1 (P < 0.05), but reduced GIP and CCK (P < 0.05 for both), responses. We conclude that exposure of glucose to the distal small intestine appears necessary for substantial GLP-1 secretion, while exposure of both the proximal and distal small intestine result in substantial secretion of GIP.     

Study bystanders and ethical treatment of study participants—A proof of concept

The ethics of research on human subjects is often construed as a fine balance between the interests of patients in need of novel health interventions, and those of study participants who should remain safe in the process. But there is a third group in the mix. Some people belong to neither category, yet research can affect or jeopardize them. Call such people “bystanders.” This article shows that thinking about bystander protection can question whether there is an upper limit on the risks that studies may legitimately visit upon their participants. Thus, thinking about appropriate bystander protection can shed light on the appropriate protection of study participants. Core research ethics, which focuses on the latter, must consider the former as well.     

Two ethical concerns about the use of persuasive technology for vulnerable people

Persuasive technologies for health-related behaviour change give rise to ethical concerns. As of yet, no study has explicitly attended to ethical concerns arising with the design and use of these technologies for vulnerable people. This is striking because these technologies are designed to help people change their attitudes or behaviours, which is particularly valuable for vulnerable people. Vulnerability is a complex concept that is both an ontological condition of our humanity and highly context-specific. Using the Mackenzie, Rogers and Dodds’ taxonomy of vulnerability, this paper identifies (a) the wrongs or harms to which a person is vulnerable, (b) the source of this vulnerability, and (c) the safeguards needed in response. Two ethical concerns with the design of persuasive technology for vulnerable people are discussed: the concerns of taking into account users' interests and their autonomy.     

Induction and adaptation of chaperone-assisted selective autophagy CASA in response to resistance exercise in human skeletal muscle

Chaperone-assisted selective autophagy (CASA) is a tension-induced degradation pathway essential for muscle maintenance. Impairment of CASA causes childhood muscle dystrophy and cardiomyopathy. However, the importance of CASA for muscle function in healthy individuals has remained elusive so far. Here we describe the impact of strength training on CASA in a group of healthy and moderately trained men. We show that strenuous resistance exercise causes an acute induction of CASA in affected muscles to degrade mechanically damaged cytoskeleton proteins. Moreover, repeated resistance exercise during 4 wk of training led to an increased expression of CASA components. In human skeletal muscle, CASA apparently acts as a central adaptation mechanism that responds to acute physical exercise and to repeated mechanical stimulation.     

The detectability of the colour pattern in the aposematic firebug,Pyrrhocoris apterus: an image‐based experiment with human ‘predators’

Crypsis and aposematism are often regarded as two opposite protective strategies. However, there is large variation in prey appearance within both strategies. In this article, we investigated the conspicuousness of the aposematic red‐and‐black firebug, Pyrrhocoris apterus, by presenting images of natural and digitally manipulated phenotypes in their natural habitat on a computer screen to human ‘predators’, and comparing the detection times. We asked whether the natural colour pattern can be made more or less conspicuous by rearranging the spatial distribution of colour elements. Hence, we created a phenotype in which the black colour elements were moved to the body outline to test for a possible disruptive effect. In the ‘black’ and ‘red’ manipulations, we removed one of the two colours, creating two uniform colour variants. We found that some of our manipulations increased, but none reduced, the detection time significantly; this indicates that the naturally coloured firebug is highly conspicuous. The detection time varied among backgrounds and there was a significant relationship between detection time and chromatic similarity between the bug and the background for the natural and black phenotypes. Although background colour composition has an important effect on the signal, we argue that the coloration of P. apterus has evolved for high conspicuousness. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 806–816.     

Effect of daily hyperhydration on fluid-electrolyte changes in endurance-trained volunteers during prolonged restriction of muscular activity

The aim of this investigation was to evaluate the effect of a daily intake of fluid and salt supplementation on fluid and electrolyte losses in endurance-trained volunteers during prolonged restriction of muscular activity (hypokinesia). The studies were performed on 30 long-distance runners aged 23–26 who had a peak oxygen uptake of 65.5 mL/kg/min and had taken 13.8 km/d on average prior to their participation in the study. The volunteers were divided into three groups: The volunteers in the first group were placed under normal ambulatory conditions (control subjects), the second group of volunteers subjected to hypokinesia alone (hypokinetic subjects), and the third group of volunteers was submitted to HK and consumed daily 0.1 g sodium chloride (NaCl)/kg body wt and 26 mL water/kg body wt (hyperhydrated subjects). The second and third group of volunteers were kept under an average of 2.7 km/d for 364 d. During the pre-experimental period of 60 d and during the experimental period of 364 d sodium, potassium, calcium, and magnesium in urine and plasma were determined. Blood was also assayed for osmolality, hemoglobin, hematocrit, plasma volume, plasma renin activity and plasma aldosterone. Mean arterial blood pressure was also determined. In the hyperhydrated volunteers plasma volume and arterial blood pressure increased, whereas plasma osmolality, plasma renin activity, plasma aldosterone, hematocrit, hemoglobin concentration, and urinary excretion and concentrations of electrolytes in plasma decreased. In the hypokinetic volunteers, plasma volume and arterial blood pressure decreased significantly, whereas hematocrit values, hemoglobin concenfration, plasma osmolality, plasma renin activity, plasma aldosterone, and electrolytes in urine and plasma increased significantly during the experimental period. It was concluded that chronic hyperhydration may be used in minimizing fluid and electrolyte losses in endurance-trained volunteers during prolonged restriction of muscular activity.