Assessing the faecal source sensitivity and specificity of ruminant and human genetic microbial source tracking markers in the central Ethiopian highlands

This study tested genetic microbial source tracking (MST) methods for identifying ruminant- (BacR) and human-associated (HF183/BacR287, BacHum) bacterial faecal contaminants in Ethiopia in a newly created regional faecal sample bank (n = 173). BacR performed well, and its marker abundance was high (100% sensitivity (Sens), 95% specificity (Spec), median log₁₀ 8·1 marker equivalents (ME) g⁻¹ ruminant faeces). Human-associated markers tested were less abundant in individual human samples (median: log₁₀ 5·4 and 4·2 (ME + 1) g⁻¹) and were not continuously detected (81% Sens, 91% Spec for BacHum; 77% Sens, 91% Spec for HF183/BacR287). Furthermore, the pig-associated Pig2Bac assay was included and performed excellent (100% Sens, 100% Spec). To evaluate the presence of MST targets in the soil microbiome, representative soil samples were tested during a whole seasonal cycle (n = 60). Only BacR could be detected, but was limited to the dry season and to sites of higher anthropogenic influence (log₁₀ 3·0 to 4·9 (ME + 1) g⁻¹ soil). In conclusion, the large differences in marker abundances between target and non-target faecal samples (median distances between distributions ≥log₁₀ 3 to ≥log₁₀ 7) and their absence in pristine soil indicate that all tested assays are suitable candidates for diverse MST applications in the Ethiopian area.     

绿色基础设施的生态及社会功能研究进展

随着城市化进程的加快,城市硬化地表不断挤占透水表面,使得绿色基础设施规模不断下降、破碎化程度逐渐加大,严重影响了绿色基础设施服务功能的有效发挥。绿色基础设施的发展经历了早期萌芽、初步形成和快速发展三个阶段,主要在宏观尺度研究区域生态安全,中观尺度促进城市可持续发展,微观尺度解决社区生态环境问题。目前绿色基础设施的研究内容集中在其生态功能和社会功能两个方面,主要关注调蓄降雨径流、消减非点源污染、调节区域微气候、居民健康与福祉和空间布局公平性。而供需结构的合理配置也是决定绿色基础设施服务水平的关键因素。未来的研究应加强与相关学科的交叉融合,完善绿色基础设施功能的测度与评估方法,将绿色基础设施建设与实际规划相结合,以期为区域可持续发展和国家生态文明建设提供支撑与保障。     

基于MSPA和MCR模型的秦岭(陕西段)山地生态网络构建

快速的城市化发展破坏了生境斑块的连通性,而在应对此环境变化中,从斑块层构建区域生态网络的研究不足。本研究以秦岭(陕西段)为对象,采用形态学空间格局分析(MSPA)辨别生态源地,利用最小阻力模型(MCR)提取潜在生态廊道,构建秦岭生态网络;基于重力模型对生态网络内部斑块的重要性进行分级,并分析了网络的结构特征及景观构成。结果表明: 秦岭(陕西段)生态网络由10个生态源地、45条潜在生态廊道和38个脚踏石构成,生态源地总面积29686.15 km²;网络闭合度(0.11)、线点率(1.18)、网络连接度(0.42)、成本比(0.99)综合表明,网络结构中潜在生态廊道和生态节点的连通性较好,而源地间的连通程度低,构建网络的成本较高;重要生态廊道主要由林地、草地、耕地等景观类型构成,其中,林地面积最大,为571.00 km²,约占廊道总面积的89.2%,景观结构良好;在生态网络中应加强保护生态源地,优先建立并保护重要生态廊道和生态节点。研究结果可为秦岭生态环境保护与高质量发展提供科学的参考和依据。     

The effect of temperature changes and K supply on the reproduction and growth of Bolboschoenus planiculmis

温度变化和钾添加对扁秆藨草生长及繁殖的影响 人类活动导致的气候变暖和农业面源污染已被认为是影响湿地植物生长和繁殖的重要因素。为了预 测和缓解这些人类活动的影响,研究沼泽植物如何响应这些环境变化具有重要意义。本研究选取在欧亚 大陆广泛分布的莎草科球茎植物扁秆藨草(Bolboschoenus planiculmis)为研究对象,考察气温变化(恒温： 15、20、25 °C及交替温度：20/10和30/15 °C)和钾添加(0、1、3、9 和18 mmol/L)对其生长和繁殖性状 的影响。研究结果表明,高的恒温(20、25 °C)比高的交替温度(30/15 °C)更有利于扁秆藨草球茎的形成, 而地上生物量和株高一般在较高温度下(30/15、25 °C)达到最大值。扁秆藨草的繁殖和生长性状均与施钾量 呈驼峰型关系,最适施钾量在1–3 mmol/L K。高恒温效应和最适钾浓度的交互作用对繁殖性状的促进作 用最大,但是,较高的温度(30/15和25 °C)和0–9 mmol/L的钾浓度只促进了生长性状的生长。综上所述, 扁秆藨草的种群优势度可能受益于全球变暖和额外的钾添加。     

不同管理模式对茶树碳氮磷含量及其生态化学计量比的影响

植物不同器官的碳(C)、氮(N)、磷(P)含量及其生态化学计量特征能够反映植物内部的养分分配与平衡关系。该研究以福建安溪3种不同管理模式的铁观音茶园为研究对象, 设置了常规管理模式下的茶园(M1)、间作套种模式下的茶园(M2)和现代技术管理模式下的茶园(M3) 3种样地, 分析茶树根、茎、叶器官的C、N、P含量及其化学计量学特征, 养分的变异特征与异速生长关系。结果表明: M2和M3管理模式下茶树根、茎、叶N、P含量均显著高于M1管理模式, C含量差异不明显; 茶树根、茎、叶C:N、C:P、N:P均表现为M1 > M2 > M3。茶树不同器官C、N、P含量差异较大, 根据变异来源分析, 管理模式因素对C、N、P含量变异的影响均达到显著水平。根茎叶N-P的异速生长关系表明茶树不同器官的养分需求存在相似性; 土壤pH和容重是影响C:N、C:P、N:P的重要因素, 而土壤含水量和盐度对茶树根和叶C含量的影响较大。总体来讲, 间作套种以及现代化滴灌、水肥等管理模式可以改善茶树对养分的吸收效率, 对解决土壤养分不均衡问题具有正面效应。     

Metabolic dynamics across prolonged diapause development in larvae of the sawfly,Cephalcia chuxiongica (Hymenoptera: Pamphiliidae)

Nutrient metabolism is crucial for the survival of insects through the diapause. However, little is known about the metabolic mechanism of prolonged diapause. The sawfly, Cephalcia chuxiongica (Hymenoptera: Pamphiliidae), is a notorious defoliator of pine trees in southwest China. One of the distinguishing biological characteristics of this pest is the prolonged diapause of about 1.5 years. In this study, the body lipid, carbohydrate (total body sugar, glycogen, trehalose, and glucose), protein, and glycerol contents were measured in diapausing larvae of C. chuxiongica. The results showed that the changes of biochemical composition in C. chuxiongica are associated with the diapause initiation, maintenance, and termination phases. During the initiation phase, trehalose, glucose, and glycerol increased significantly, but glycogen decreased sharply. In general, the lipid, carbohydrate, and glycerol levels decreased gradually across the maintenance phase. At termination phase, the contents of glycogen and lipid persistently decreased, while an increase of trehalose, glucose, and glycerol contents were detected. The protein level was significantly higher at maintenance phase than at initiation and termination phases. It was also found that elevation of trehalose, glucose, and glycerol contents occurred in winter. These implies that the metabolites with altered levels in diapausing larvae of C. chuxiongica are responsible for maintaining a prolonged development and overwintering.     

Introduction: International conference on forest ecosystems: Ecology,conservation and sustainable management

Abstract

A pollen diagram from a small lake, Kutulahdenlampi, in northern Finland is interpreted in terms of the development of forest vegetation during the Holocene. The abundance of each of the forest taxa is considered independently by means of pollen accumulation rates (PARs), using as the reference material, long term average pollen deposition values monitored by a network of pollen traps. Particular attention is paid to the arrival of spruce and to the species in the original forests that this newcomer replaces. A model of pollen dispersal and deposition developed by Sugita is used to estimate the area around the lake that the pollen assemblage is most clearly reflecting. This relevant source area of pollen (RSAP), for the present day situations is c. 1,500 m. Pollen loadings calculated for a simulated landscape that mimics (i) that of the present day and (ii) for the situation at 8,000 BP (as deduced from the PARs) are compared with the pollen assemblages from the diagram at those points in time, and are seen to be compatible. The advantages of combining PAR and modelling to look at the spatial scale of vegetation reconstructions are discussed.     

α‐N‐Protected dipeptide acids: a simple and efficient synthesis via the easily accessible mixed anhydride method using free amino acids in DMSO and tetrabutylammonium hydroxide

The importance of dipeptides both in medicinal and pharmacological fields is well documented and many efforts have been made to find simple and efficient methods for their synthesis. For this reason, we have investigated the synthesis of α‐N‐protected dipeptide acids by reacting the easily accessible mixed anhydride of α‐N‐protected amino acids with free amino acids under different reaction conditions. The combination of TBA‐OH and DMSO has been found to be the best to overcome the low solubility of amino acids in organic solvents. Under these experimental conditions, the homogeneous phase condensation reaction occurs rapidly and without detectable epimerization. The present method is also applicable to side‐chain unprotected Tyr, Trp, Glu, and Asp but not Lys. This latter residue is able to engage two molecules of mixed anhydride giving the corresponding isotripeptide. Moreover, the applicability of this protocol for the synthesis of tri‐ and tetrapeptides has been tested. This approach reduces the need for protecting groups, is cost effective, scalable, and yields dipeptide acids that can be used as building blocks in the synthesis of larger peptides. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.