Water,Water Compartments and Water Regulation in Some Nematodes Parasitic in Vertebrates

While nematodes are sometimes regarded as osmoconformers, at least one species is capable of short-term osmoregulation over a wide range of osmotic environments, and the principal site of osmoregulation is the body wall. This general osmoregulation is important to the life of the nematode not only in confronting variations in the environment, but also in maintaining its hydrostatic skeleton. There is also evidence suggesting that compartments exist in some nematodes and that water exchange between the compartments is limited and slow. The ability to regulate the internal movements of water is important in molting and in the infective process. Hormones may be the mediators of osmotic control.     

Water Flow in Wheat Seedlings after Small Water Deficits

Cultures of Scenedesmus obliquus when grown heterotrophically for 10 or 30 days without addition of fresh medium showed 85 and 98% loss of their photosynthetic capacity respectively. This loss in photosynthetic capacity was accompanied by an increase in quantum requirement. No major changes in the pigment amounts or types were detected which would explain the decay in photosynthetic capacity. Partial reactions mediated by photosystem II or I showed a more or less constant decay over a period of 30 days. Photosystem II reactions appeared less stable than those of photosystem I, decaying by 95% as compared with 70%, over this time period. The results of comparative studies on aged cells for their potential of cytochrome f photooxidation, fluorescence kinetics, 520 nm absorbance change and the variable influence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone on the photosynthetic capacity of such cells, suggest that it is the inherent ability of the cells to photooxidize plastohydroquinone which is affected primarily. In addition, secondary changes were noted in the activity of reactions on the water-splitting side of photosystem II and in the P700 — plastocyanin — cytochrome f complex.     

Occurrence of Mycobacteria in Water Treatment Lines and in Water Distribution Systems

The frequency of recovery of atypical mycobacteria was estimated in two treatment plants providing drinking water to Paris, France, at some intermediate stages of treatment. The two plants use two different filtration processes, rapid and slow sand filtration. Our results suggest that slow sand filtration is more efficient for removing mycobacteria than rapid sand filtration. In addition, our results show that mycobacteria can colonize and grow on granular activated carbon and are able to enter distribution systems. We also investigated the frequency of recovery of mycobacteria in the water distribution system of Paris (outside buildings). The mycobacterial species isolated from the Paris drinking water distribution system are different from those isolated from the water leaving the treatment plants. Saprophytic mycobacteria (present in 41.3% of positive samples), potentially pathogenic mycobacteria (16.3%), and unidentifiable mycobacteria (54.8%) were isolated from 12 sites within the Paris water distribution system. Mycobacterium gordonae was preferentially recovered from treated surface water, whereas Mycobacterium nonchromogenicum was preferentially recovered from groundwater. No significant correlations were found among the presence of mycobacteria, the origin of water, and water temperature.     

Traditional Water Resource Management and Water Quality in Rural Tanzania

Traditional resource management (TRM) is largely based on local ecological knowledge (LEK). In regions where formal institutional control of natural resources is limited due to a lack of coordination or stakeholder involvement, communities rely on TRM to manage common-pool resources. This paper examines TRM among the Sonjo in rural Northern Tanzania, with particular reference to catchment forest protection and water quality. We first document the ecological knowledge of traditional resource managers, and then describe the differences between traditionally managed water sources and formal, government managed resources. Using both qualitative and quantitative methods to examine water use, perceptions of water quality, and bacterial water quality, significant differences were detected among river basins within seasons and between seasons. Our findings indicate that the Sonjo, well known for their traditional forest conservation practices and irrigation management, may also benefit from TRM through improved water quality. The examination of traditional methods of water conservation provides insight into how communities in resource-stressed regions thrive despite seasonal droughts and flooding.     

北京市水足迹

水资源短缺、水质污染等已成为北京可持续发展的制约因素,水资源利用问题愈发受到关注。水足迹的研究将人们的生产、消费与水资源的消耗联系起来,全面真实地揭示水资源利用情况。本文基于水足迹理论评价了北京水资源利用情况,结果表明:(1)2012年,北京市水足迹为352.6亿m3,人均水足迹为1704 m3,远超统计数据中总供水量35.9亿m3和人均用水量193.3 m3,水资源面临巨大压力。(2)北京市城镇和农村居民对虚拟水的消耗存在差异性,除动物产品外,农村居民对于粮食虚拟水的消耗相对较高,人均每年103.5 m3,而城镇人均每年72.5 m3,次于干鲜瓜果92.4 m3。(3)动物产品在虚拟水消耗中占据了最大的比重,说明了北京市居民对动物产品消耗量相对较高,也反映出动物产品单位产品虚拟水含量较高。为此,在虚拟水贸易中,可适当增加动物产品进口代替本地动物产品的养殖生产,降低水资源的消耗。     

Water Stress in Plants

The abscisic acid (ABA) content was determined quantitatively in the leaves from wilted and unwilted tomato plants (Lycopersicon esculentum Mill. CV. Revermun) by the use of the wheat coleoptile test and gas-liquid chromatography (GLC). Plants which have received an insufficient daily water supply for 18 days showed adaptation to wilting conditions. The plants adjust to the added amount of water by regulating their water loss through transpiration. The concentration of ABA was not higher in the leaves of plants adapted to water stress than in plants that were watered abundantly. Wilted detached leaves and leaves from rapidly wilted intact plants showed the well-known reaction by increasing the ABA level. A possible role of ABA in the early stages of the adaptation process is discussed.     

Water channels in membranes

A systematic programme of comparative nuclear magnetic resonance measurements of the membrane permeability for water (Pd) and of activation energy (E_a,d) of this process in red blood cells of various wild, laboratory and domestic animals was carried out here. The RBC from humans, cow, sheep and kangaroos had P_d values around 5·10^?3 cm/s at 25 °C, 7 · 10^?3 cm/s at 37 °C with E_a,d values around 25 kJ/mol. For RBC from other ten marsupial species and from mouse, rat and rabbit, the P_d values were more than twice as high as for human RBC. For mosr RBC a high value of Pd was associated with a low value of E_a,d (range from 15 to 21 kJ/mol), pointing to specialized channels for water diffusion incorporated in membrane proteins. Recently a channel-forming integral protein of 28 kDa (CHIP 28) was identified as a major water channel protein in the RBC membrane. A procedure for quantitating the purified CHIP 28 by densitometry of silver-stained polyacrylmide gel electrophoreograms was developed. The analysis of a purified fraction of CHIP 28 showed that the 28 kDa component represents approximately two-thirds of the sample with the remainder comprising the glycosylated high-molecular-weight component. A correlation between the content in CHIP 28 and the relative water permeability among RBC from different vertebrate species was attempted.     

Water Justice and Integrated Water Resources Management: Constitutionality Processes Favoring Sustainable Water Governance in Mexico

This research analyzes four ongoing water conflicts in Jalisco state, Mexico, through the lens of constitutionality. Constitutionality refers to a bottom-up institution building process based on the activation of emic perceptions of people who are often marginalized in policymaking, as well as on alliances with external actors, with the aim of achieving recognition by the state of self-created institutions. Results show that the constitutionality concept helps to link analysis of local people’s resistance movements against top-down water policies with an emerging process of institutional innovation that aims for more sustainable water governance. Local institutional innovations embody the principles of water justice; these are recognized by the state as being part of its own Integrated Water Resources Management (IWRM) policy, and thus find their way into state policy arenas. This analysis provided the basis for the formulation of a conceptual framework that integrates water conflicts, water justice, and IWRM into the concept of constitutionality.     

节水应优先于调水

就规划中的南水北调西线工程受水区情况,本刊记者访问了刘昌明院士和陶传进博士。尽管他们对南水北调西线工程的必要性看法不同,却表达了一个共同的声音：受水区应把挖掘自身的节水潜力摆在优先。