基于PCR-DGGE分析抗性淀粉对高脂饮食HFA小鼠肠道菌群的影响

本文研究了香蕉抗性淀粉对高脂饮食菌群人源化小鼠(HFA)肠道菌群的调控效果。将30只肠道菌群人源化昆明小鼠随机分为3组(10只/组),分别饲喂普通饮食、高脂饮食和高脂饮食+抗性淀粉。提取第0周和第8周新鲜粪便DNA,比较用16S r DNAV6-V8区段特异性引物扩增产物,以PCR-DGGE技术手段检测抗性淀粉组、高脂饮食组和普通饮食组肠道菌群差异。第0周,三组小鼠菌群总菌丰富度,多样性指数和均匀度无显著差异(p0.05),小鼠和粪便供者之间菌群相似性为36%;三组小鼠肠道菌群相似性达到60-93%,PCA分析显示三组小鼠的数据点都聚在一起,说明在干预前无明显差异,适用于分析抗性淀粉对肠道菌群的影响;膳食干涉第8周后小鼠肠道菌群的多样性指数和丰富度数值,抗性淀粉组都极显著低于高脂组和普通饲料组(p0.01),PCA分析也显示三组小鼠肠道菌群各组的数据点都分布在不同区域,说明抗性淀粉对高脂饮食HFA小鼠肠道菌群结构产生显著影响。     

世界自然环境探讨

依据联合国有关部门发布的资料，综合分析了全球陆地、天空和海洋主要的环境状况。对比介绍了世界主要地区突出的环境问题。对整体环境治理提出了4点建议。     

Large freshwater lakes in arid Australia: A review of their limnology and threats to their future

Large freshwater lakes in Australia’s arid zone are episodic due to highly variable inflows from allogenic rivers. A few receive enough inflow almost yearly to be permanent, despite large losses from high evaporation. Biodiversity is high, with most taxonomic groups represented, and is largely endemic at the continental scale. There is almost no regional endemism, which is at variance with other major aquatic habitat types in Australia. Abundance fluctuates greatly, with invertebrates and fish booming and busting with floodwater input, but birds generally reach greatest numbers later in the cycle as they gather on the more persistent waters. Invertebrate assemblages are influenced by the degree of lake permanence, turbidity and salinity, providing a temporally variable mosiac of environments throughout a lake system and between systems and with time. Unlike other groups, fish are not speciose, but are important predators in most systems with breeding coinciding with flooding. This favours native species against exotics in the Coongie Lakes but, in the Paroo, exotics are common in permanent waters. Waterbirds are the very obvious components in these variable systems, using their resources for feeding and breeding. Most are extremely nomadic to take advantage of the variable habitat. Two of the most important lake systems, the Coongie Lakes on Cooper Creek and the Paroo lakes in the northwestern Murray Darling catchment, are threatened by water abstraction upstream for irrigation, so that important habitat may be lost. In addition, the lakes will become less variable and, so, possibly compromise their character with cascading effects through the ecosystem. Some smaller lakes are adversely impacted by accelerated sedimentation.     

城市绿地系统视角下的生物多样性保护规划探讨——以绵阳市生物多样性保护规划为例

本文针对《城市园林绿化评价标准》对绿地系统规划中《城市生物多样性保护规划》的编制要求,从城市管理角度出发,以绵阳市生物多样性保护为例,提出不同空间层面生物多样性保护规划的主要内容。     

Lake Baringo: Addressing threatened biodiversity and livelihoods

Lake Baringo is a shallow, internal drainage, freshwater lake located in the Kenyan Rift Valley. The lake is an important source of water for humans and livestock, as well as a significant income source for local communities through activities such as tourism, biodiversity conservation, and fish sold in local markets. The lake has been subject to overfishing, as well as to greatly enhanced sedimentation as a result of land use changes in the drainage basin. This paper provides an analysis of the conditions prevailing at Lake Baringo, and examines in detail the management response to the problems facing the lake. The roles of the many and varied institutions in the lake basin's management are discussed, and an analysis of internationally funded projects designed to ameliorate the situation is provided.     

STREAM HABITAT MODELLING FOR CONSERVING A THREATENED HEADWATER FISH IN THE UPPER CUMBERLAND RIVER,KENTUCKY

The conservation of stream biodiversity requires more explicit knowledge on the distribution of aquatic species within the context of their specific environmental settings and stresses. Although species distribution models (SDMs) have been widely used for organisms occupying contiguous spatial extents, the implementation of SDMs in relatively complex and segmented riverine networks is still at its early stage. In this study, we explicitly modelled the headwater stream habitat for the threatened blackside dace (Phoxinus cumberlandensis) endemic to the upper Cumberland River, Kentucky, USA. An occurrence record data set, along with variables describing stream properties and land use impacts, was used to predict the fish habitat suitability at the stream segment level. An approach combining geographic information systems and the maximum entropy species distribution modelling (MaxEnt) was adopted. Results demonstrated that natural conditions and land use disturbances, respectively, form the primary and secondary environmental constraints on the species' habitat. We generated regional‐scale management‐friendly maps showing subwatershed habitat suitability and locations of the clustered suitable habitats (hotspots) and thus set an example for spatially explicit management of threatened and endangered riverine species. This study demonstrates the usefulness of SDMs for stream network–based environments in the facilitation of biogeographic conservation efforts and studies. Copyright © 2012 John Wiley & Sons, Ltd.     

Impact of weirs on fish communities in a piedmont stream

The impact of large dams on fish communities is much better documented than that of weirs. This paper investigates the influence of weirs on fish community patterns along a piedmont river (the River Viaur). Presence/absence of species was obtained distant from a weir (NW), and immediately downstream (DW) and immediately upstream (UW) of the weir. More than half of the species captured were non‐native, probably introduced when upstream reservoirs were built. Most of these species were eurytopic or limnophilic. Species richness at UW sites and the number of introduced species found at each site did not depend on the distance from the source (DFS). UW sites had more introduced and limnophilic species than NW sites. Conversely, NW had more rheophilic species than UW. Furthermore, total species richness (SRT) was higher at DW than NW suggesting a direct influence of the weir on the downstream community. UW sites were characterized by the presence of tench, roach and bleak which were scarce in NW sites where brown trout predominated. Weirs appear to modify habitat to favour the colonization of introduced species, and therefore have influenced the structure of fish communities. The study underlines the importance of local conditions in artificially‐influenced rivers. Copyright © 2007 John Wiley & Sons, Ltd.     

Diversity and food quality properties of farmers' varieties of sorghum from Bénin

Farmers' varieties of sorghum from three communities in different regions of northern Bénin were analysed for their food quality and agro‐morphological properties, and also for their genetic diversity using amplified fragment length polymorphism (AFLP). Farmers' varieties of sorghum differed greatly with respect to their morphology and agronomic and food traits. Most of the varieties had long (>200 cm) stems (87%), loose panicles (79%) and a red or pink colour (52%). Most were susceptible to drought (54%) and to attacks by striga (79%), insects (99%) and birds (77%). Farmers evaluated the quality of the seeds for preparing porridges as being high for 60% of the varieties and 26% of the varieties were regarded as suitable for making beverages. Late‐maturing, large‐seeded, red or pink varieties are preferred by farmers for porridges and beverages. Gene diversity among varieties within regions, as measured by neutral markers, was similar for the three regions (0.211–0.240). However, across regions the short (<150 cm) stem varieties showed relatively high genetic diversity compared with long or medium stem varieties (0.378 vs 0.184–0.216 for long–medium stem varieties). Genetic differentiation (F_st) among regions and among stem lengths of varieties was significant and ranged between 0.086 and 0.135. Grain colour, stem length and panicle shape varied significantly with the region/stem length and correlated with the genetic differentiation of regions. No relationship could be detected between the genetic differentiation of the varieties and their food quality as expressed by the farmers. Implications of the findings for crop conservation and breeding are discussed. Copyright © 2006 Society of Chemical Industry     

Genetic doping algorithm (GenD): theory and applications

Abstract: This paper describes an evolutionary algorithm, GenD, conceived by Buscema in 1998 at the Centro Ricerche di Scienze della Comunicazione – Semeion in Rome, where it is still successfully used and has been further developed. Unlike classic genetic algorithms, the GenD system maintains an inner instability during evolution, presenting a continuous evolution of the evolution and a natural increase in biodiversity during the progress of the algorithm. The theory which leads to defining the GenD system is outlined. Specific characteristics of GenD, such as the definition of a species‐health aware evolutionary law, the use of genetic operators and the adoption of a structured organization of individuals (tribes), are described. In order to measure GenD capabilities, we investigated also different problems, such as that known as the travelling sales person problem, which belongs to the class of full NP problems.