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1.
While the adaptive function of black eumelanin-based coloration is relatively well known, the function of reddish-brown pheomelanin-based coloration is still unclear. Only a few studies have shown or suggested that the degree of reddish-brownness is associated with predator–prey relationships, reproductive parameters, growth rate and immunity. To gain insight into the physiological correlates of melanin-based coloration, I collected barn owl (Tyto alba) cadavers and examined the covariation between this colour trait and ovary size, an organ that increases in size before reproduction. A relationship is expected because melanin-based coloration often covaries with sexual activity. The results showed that reddish-brown juveniles had larger ovaries than whiter juveniles particularly in individuals in poor condition and outside the breeding season, while in birds older than 2 years lightly coloured females had larger ovaries than reddish-brown conspecifics. As barn owls become less reddish-brown between the first and second year of age, the present study suggests that reddish-brown pheomelanic and whitish colorations are associated with juvenile- and adult-specific adaptations, respectively.  相似文献   

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以鲫鱼为材料,研究了钙和铅相互作用对鲫鱼毒性效应的影响.试验分为5组,分别为空白对照Ⅰ组、单独染铅Ⅱ组(0.1 mg·L-1)及铅钙联合组(Ⅲ组:0.1 mg·L-1铅+2 mmol·L-1钙,Ⅳ组:0.1 mg·L-1铅+4 mmol·L-1钙,Ⅴ组:0.1 mg·L-1铅+6 mmol·L-1钙),处理35 d后,检测鲫鱼肌肉、鳃中铅含量,以及肝胰脏中总抗氧化能力(T-AOC)、过氧化氢酶(CAT)活性和丙二醛(MDA)含量.结果表明,与Ⅰ组比较,Ⅱ、Ⅲ组鲫鱼肌肉、鳃中铅含量增高(p0.05),Ⅴ组鲫鱼肌肉中铅含量降低(p0.05),与Ⅱ组比较,Ⅳ、Ⅴ组鲫鱼肌肉、鳃中铅含量降低(p0.05);与Ⅰ组比较,Ⅱ组CAT活性降低(p0.05),Ⅲ、Ⅳ和Ⅴ组CAT活性升高(p0.05),与Ⅱ组比较,Ⅳ、Ⅴ组CAT活性升高(p0.05);与Ⅰ组比较,Ⅱ、Ⅲ和Ⅴ组T-AOC活性降低(p0.05),与Ⅱ组比较,Ⅲ、Ⅳ和Ⅴ组T-AOC活性增高(p0.05);与Ⅰ组比较,Ⅱ、Ⅲ、Ⅳ和Ⅴ组MDA含量升高(p0.05),与Ⅱ组比较,Ⅲ、Ⅳ和Ⅴ组MDA含量降低(p0.05).由此可见,钙可竞争鲫鱼对铅的吸收,降低铅在其肌肉、鳃中的蓄积,提高鲫鱼肝胰脏的抗氧化能力,表明钙能降低铅的毒性效应.  相似文献   

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Biomineralization has become a research focus in wastewater treatment due to its much lower costs compared to traditional methods. However, the low sodium chloride (NaCl)-tolerance of bacteria limits applications to only water with low NaCl concentrations. Here, calcium ions in hypersaline wastewater (10% NaCl) were precipitated by free and immobilized Halovibrio mesolongii HMY2 bacteria and the differences between them were determined. The results show that calcium ions can be transformed into several types of calcium carbonate with a range of morphologies, abundant organic functional groups (C-H, C-O-C, C=O, etc), protein secondary structures (β-sheet, α-helix, 310 helix, and β-turn), P=O and S-H indicated by P2p and S2p, and more negative δ13CPDB (‰) values (-16.8‰ to -18.4‰). The optimal conditions for the immobilized bacteria were determined by doing experiments with six factors and five levels and using response surface method. Under the action of two groups of immobilized bacteria prepared under the optimal conditions, by the 10th day, Ca2+ ion precipitation ratios had increased to 79%-89% and 80%-88% with changes in magnesium ion cencentrations. Magnesium ions can significantly inhibit the calcium ion precipitation, and this inhibitory effect can be decreased under the action of immobilized bacteria. Minerals induced by immobilized bacteria always aggregated together, had higher contents of Mg, P, and S, lower stable carbon isotope values and less well-developed protein secondary structures. This study demonstrates an economic and eco-friendly method for recycling calcium ions in hypersaline wastewater, providing an easy step in the process of desalination.  相似文献   

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Whales repetitively dive deep to feed and should be susceptible to decompression syndrome, though they are not known to suffer the associated pathologies. Avascular osteonecrosis has been recognized as an indicator of diving habits of extinct marine amniotes. Vertebrae of 331 individual modern and 996 fossil whales were subjected to macroscopic and radiographic examination. Avascular osteonecrosis was found in the Oligocene basal odontocetes (Xenorophoidea) and in geologically younger mysticetes, such as Aglaocetus [a sister taxon to Balaenopteridae + (Balaenidae + Eschrichtiidae) clade]. These are considered as early "experiments" in repetitive deep diving, indicating that they independently converged on their similar specialized diving physiologies.  相似文献   

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REDD+ (reducing emissions from deforestation and forest degradation and related forest activities) is a climate change mitigation mechanism currently being negotiated under the United Nations Framework Convention on Climate Change (UNFCCC). It calls for developed countries to financially support developing countries for their actions to reduce forest-sector carbon emissions. In this paper, we undertake a meta-analysis of the links, if any, between multiple and diverse drivers of deforestation operating at different levels and the benefits accruing from and being shared through REDD+ projects. We do so by assessing the nature of this link in (a) scholarly analysis, through an in-depth analysis of the posited relationship between drivers and REDD+ benefit-sharing, as examined in the peer-reviewed literature; and (b) in policy practice, through analysing how this link is being conceptualised and operationalised, if at all, in REDD+ project design documents. Our meta-analysis suggests that while some local, direct drivers and a few regional indirect drivers of deforestation and forest degradation are being targeted by specific REDD+ interventions and associated benefit-sharing mechanisms at the project-level, most national and international indirect drivers are not. We conclude that the growing academic analyses of REDD+ projects do not (as yet) advance viable theories of change, i.e. there is currently little focus on how REDD+ benefits could play a transformative role in catalysing action on drivers.  相似文献   

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As climate change adaptation planning moves beyond short term National Adaptation Programmes of Action (NAPA) to longer-term approaches, it is instructive to review the NAPA process and examine how well it was linked to national development planning. This paper reviews 41 NAPAs submitted by Least Developed Countries (LDCs) to the United Nations Framework Convention on Climate Change (UNFCCC), to assess the NAPA process in terms of NAPAs integration with countries’ national development strategies. The review outlines the actors involved in developing NAPAs and identifies the range of interventions included in countries’ priority adaptation actions. The paper uses the example of population as an issue related to both climate change and national development to assess how it is addressed as part of LDCs’ adaptation and national development agendas. The analysis shows that although countries recognize population pressure as an issue related to the ability to cope with climate change and as a factor hindering progress in meeting development goals, it is not well incorporated into either adaptation planning or in national development strategies. Among the 41 NAPAs, 37 link high and rapid population growth to climate change. Moreover, six NAPAs clearly state that slowing population growth or investments in reproductive health/family planning (RH/FP) should be considered among the country’s priority adaptation actions. Furthermore, two NAPAs actually propose a project with components of RH/FP among their priority adaptation interventions, although none of them has yet been funded. The paper points to structural issues that hamper better alignment between climate change adaptation and national development planning and offers recommendations for longer-term adaptation strategies that better meet the development needs of countries.  相似文献   

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Despite a reasonable scientific interest in sexual selection, the general principles of health signalisation via ornamental traits remain still unresolved in many aspects. This is also true for the mechanism preserving honesty of carotenoid-based signals. Although it is widely accepted that this type of ornamentation reflects an allocation trade-off between the physiological utilisation of carotenoids (mainly in antioxidative processes) and their deposition in ornaments, some recent evidence suggests more complex interactions. Here, we further develop the models currently proposed to explain the honesty of carotenoid-based signalisation of heath status by adding the handicap principle concept regulated by testosterone. We propose that under certain circumstances carotenoids may be dangerous for the organism because they easily transform into toxic cleavage products. When reserves of other protective antioxidants are insufficient, physiological trade-offs may exist between maintenance of carotenoids for ornament expression and their removal from the body. Furthermore, we suggest that testosterone which enhances ornamentation by increasing carotenoid bioavailability may also promote oxidative stress and hence lower antioxidant reserves. The presence of high levels of carotenoids required for high-quality ornament expression may therefore represent a handicap and only individuals in prime health could afford to produce elaborate colourful ornaments. Although further testing is needed, this ‘carotenoid maintenance handicap’ hypothesis may offer a new insight into the physiological aspects of the relationship between carotenoid function, immunity and ornamentation.  相似文献   

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大气CO2浓度升高对水稻生理生态效应的影响   总被引:1,自引:0,他引:1  
目前大气中CO2浓度在逐步上升,以CO2为主的温室气体浓度增加而引起的温室效应对人类农业生产可能产生很大影响。本文介绍了大气CO2浓度升高对水稻一系列的生理生态效应的影响。未来高CO2浓度下,水稻的生育期会缩短;光合作用有所提高;干物质积累增加,产量显著提高;含N量降低,P吸收增加;促进了根系生长和土壤呼吸等。并对未来的研究作了进一步探讨。  相似文献   

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Biofilms have important effects on nutrient cycling in aquatic ecosystems.However,publications about the community structure and functions under laboratory conditions are rare.This study focused on the developmental and physiological properties of cultured biofilms under various phosphorus concentrations performed in a closely controlled continuous flow incubator.The results showed that the biomass(Chl a)and photosynthesis of algae were inhibited under P-limitation conditions,while the phosphatase activity and P assimilation rate were promoted.The algal community structure of biofilms was more likely related to the colonization stage than with the phosphorus availability.Cyanobacteria were more competitive than other algae in biofilms,particularly when cultured under low P levels.A dominance shift occurred from non-filamentous algae in the early stage to filamentous algae in the mid and late stages under P concentrations of 0.01,0.1 and 0.6 mg/L.However,the total N content,dry weight biomass and bacterial community structure of biofilms were unaffected by phosphorus availability.This may be attributed to the low respiration rate,high accumulation of extracellular polymeric substances and high alkaline phosphatase activity in biofilms when phosphorus availability was low.The bacterial community structure differed over time,while there was little difference between the four treatments,which indicated that it was mainly affected by the colonization stage of the biofilms rather than the phosphorus availability.Altogether,these results suggested that the development of biofilms was influenced by the phosphorus availability and/or the colonization stage and hence determined the role that biofilms play in the overlying water.  相似文献   

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为进一步了解附植藻类对沉水植物的影响,以狐尾藻为研究对象,通过室内模拟实验,研究了有无附植藻类情况下,狐尾藻根长、株长、生物量、可溶性蛋白含量、叶绿素含量、MDA含量、SOD、POD以及CAT等的变化情况.结果表明:未添加藻类处理组中狐尾藻的生物量最大是添加藻类处理组的2.49倍,实验末期未添加藻类处理组的叶绿素含量是添加藻类处理组的1.87倍,说明附植藻类的大量繁殖会影响狐尾藻生物量的合成,降低狐尾藻的叶绿素含量;添加附植藻类处理组的POD和CAT酶活性在实验后期均显著高于无附植藻类的处理组,且实验末期狐尾藻的MDA含量显著上升,说明附植藻类的大量繁殖使狐尾藻细胞膜损害严重,影响了抗氧化保护酶系统,最终导致狐尾藻衰败显著.附植藻类的大量繁殖是沉水植物衰败的原因之一.  相似文献   

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有机质腐解对穗花狐尾藻生长及生理的影响   总被引:1,自引:0,他引:1       下载免费PDF全文
以原沉积物和分别添加0.5%与1%有机质(植物残体)的沉积物作为底质培养沉水植物,采用室内模拟实验研究了有机质的腐解过程对穗花狐尾藻生长及生理作用的影响.结果表明,在试验的早期阶段,有机质的腐解对狐尾藻的生长有一定的抑制,但在整个培养阶段,与原沉积物组相比,0.5%有机质的加入,在一定程度上可促进植株生长, 狐尾藻生物量和根系生物量平均增加了12.99%和125.31%,而1%有机质的加入,狐尾藻生长受到抑制.在培养的前16d,有机质的添加抑制了沉水植物狐尾藻叶绿素和可溶性蛋白含量的增加,在培养中后期,0.5%有机质的加入,可促进植株体内可溶性蛋白和叶绿素含量的积累.0.5%有机质添加条件下, 超氧化物歧化酶(SOD)活性持续升高,添加1%有机质和较长时间处理时,狐尾藻抗氧化酶系统活性先升高后降低. 在培养前期,1%有机质添加组植株丙二醛(MDA)含量比原沉积物组提高了20.13%,但与0.5%组差异不显著,即低浓度有机质的增加能促进狐尾藻生长及生理代谢,但随着有机质增加量的升高对狐尾藻的生理活动将产生不利影响.  相似文献   

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介绍了当前国内外电子废物管理的法律法规,通过对国内外电子废物管理法规在完备程度、主管机构、准备时间、处罚力度以及责任制等方面进行比较,分析了当前我国电子废物管理法规存在的问题。并提出了制定电子废物专项法律、完善配套法规标准、适当延长法律法规从颁布到实施的时间间隔,明确电子电器产品及电子废物主管部门,加强相关部门间的协调、加强对电子废物违法行为的处罚力度、明确责任机制.建立国家电子废物基金等对策和建议。  相似文献   

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大型城市紧凑度与能源效率的关系研究   总被引:1,自引:0,他引:1  
田成诗  李金 《自然资源学报》2018,33(10):1781-1795
采用超效率DEA和熵值法测算了2003—2014年29个大型城市的能源效率与紧凑度,进而通过象限图法对城市紧凑度与能源效率的关系进行分析。分析表明,我国大型城市能源效率普遍偏低但在缓慢提升;城市紧凑度与能源效率以低级协调为主。从区域看,二者关系的地区差异明显,东部以高级协调为主,中西部低级协调关系显著。城市规模越大,紧凑度和能源效率水平越高,且城市突出关系类型由低级协调变为高级协调。剔除紧凑度外其他可能影响能源效率的因素后的象限图再次印证提高紧凑度有利于改善城市能源效率的结论。为通过提升城市紧凑度来提高能源效率,需加大公共服务和基础设施投入,加强工业用地的集约使用,完善城市功能体系,实现经济、人文和生态的多功能复合利用。  相似文献   

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