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.     

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.     

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。     

Water and Seed Survival

Between about –350 and –14 MPa the rate of lossof viability in orthodox seeds is a positive function of waterpotential. The relative effect of water potential has been analysedin an oily seed (lettuce) and a non-oily seed (barley) and foundto be more or less identical. The lower limit for the relationin various species coincides with a seed moisture content (wetbasis) between about 2 and 6%. Below this level there is littleor no improvement in longevity with reduction in moisture content.The upper limit coincides with moisture contents of between15 and 28%, depending on whether the seeds are oily or non-oily.A water potential of about –14 MPa is the threshold forrespiration which increases more-or-less linearly with increasein water potential above this level. Above this threshold, andproviding oxygen is available to sustain respiration, seed longevityincreases with increase in water potential except that, unlessthe seeds are dormant, germination may be initiated at a waterpotential of about –1·5 to –0·5 MPa.In the absence of oxygen there may be a slight further declinein longevity with increase in water potential above –14MPa before longevity reaches a minimum value Since they cannot be dried very much without immediate lossof viability, recalcitrant seeds survive longest in the presenceof oxygen at maximum water potential commensurate with preventinggermination. The threshold water potential for immediate lossof viability has not been determined for most species but itis probable that it is close to the water potential typicalof the permanent wilting point in these plants, say –2MPa Lactuca saliva L., lettuce, Hordeum oulgare L., barley, seed storage, moisture content, relative humidity, water potential, temperature, oxygen     

Cytokinins and Water Stress

It is almost impossible to find a single process in plant life that is not affected by both stress and hormones directly or indirectly. This minireview is focused on the interactions between water stress and cytokinins (CKs). The attention was paid mainly to changes in endogenous CK content and composition under water stress, involvement of CK in plant responses to water stress mainly in stomatal regulation of gas exchange, water relations of transgenic plants with elevated CK content, and possibilities to ameliorate the negative effects of water stress by application of exogenous CKs.     

Water,Water, Everywhere

Abstract

Math and Science Across Culture: Activities and Investigations from the Exploratorium. Maurice Bazin, Modesto, and the Exploratorium Teacher Institute. New York: The New Press, 2002. 176 pp. $19.95 (paperback). ISBN 1-56584-541-2

History Beneath the Sea—Nautical Archaeology in the Classroom. K. C. Smith and Amy Douglass (Editors). Washington, D.C.: Society for American Archaeology, 2001. 28 pp. $5.95 (paperback). ISBN 0-932839-17-7.     

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.     

Response of Indoor-Grown Cassava to Water Deficits and Recovery of Leaf Water Potential and Stomatal Activity after Water Stress

Wilting of the leaves occurred in acropetal succession at leafwater potentials between –0.9 and –1.1 MPa. Onlysevere water stress caused the discoloration and abscissionof the basal leaves. Leaf resistance was independent of leafwater potential above –0.5 MPa but increased as the potentialdropped below this value. When the stressed plants were rewatered,leaf water potentials recovered rapidly within the first h.Subsequently, the rate of recovery declined gradually. The maximumvalue of leaf water potential after rewatering was dependenton the severity of the water stress.