Achieving universal, safely managed water and sanitation services by 2030, as envisioned by the United Nations (UN) Sustainable Development Goal (SDG) 6, is projected to require capital expenditures of USD 114 billion per year (1). Investment on that scale, along with accompanying policy reforms, can be motivated by a growing appreciation of the value of water. Yet our ability to value water, and incorporate these values into water governance, is inadequate. Newly recognized cascading negative impacts of water scarcity, pollution, and flooding underscore the need to change the way we value water (2). With the UN/World Bank High Level Panel on Water having launched the Valuing Water Initiative in 2017 to chart principles and pathways for valuing water, we see a global opportunity to rethink the value of water. We outline four steps toward better valuation and management (see the box), examine recent advances in each of these areas, and argue that these four steps must be integrated to overcome the barriers that have stymied past efforts

Pericytes are believed to originate from either mesenchymal or neural crest cells. It has recently been reported that pericytes play important roles in the central nervous system (CNS) by regulating blood-brain barrier homeostasis and blood flow at the capillary level. However, the origin of CNS microvascular pericytes and the mechanism of their recruitment remain unknown. Here, we show a new source of cerebrovascular pericytes during neurogenesis. In the CNS of embryonic day 10.5 mouse embryos, CD31+F4/80+ hematopoietic lineage cells were observed in the avascular region around the dorsal midline of the developing midbrain. These cells expressed additional macrophage markers such as CD206 and CD11b. Moreover, the CD31+F4/80+ cells phagocytosed apoptotic cells as functionally matured macrophages, adhered to the newly formed subventricular vascular plexus, and then divided into daughter cells. Eventually, these CD31+F4/80+ cells transdifferentiated into NG2/PDGFRβ/desmin-expressing cerebrovascular pericytes, enwrapping and associating with vascular endothelial cells. These data indicate that a subset of cerebrovascular pericytes derive from mature macrophages in the very early phase of CNS vascular development, which in turn are recruited from sites of embryonic hematopoiesis such as the yolk sac by way of blood flow.

ABSTRACT. As pressures on water resources increase, the demand for innovative institutional arrangements, which address the overuse of water, and underprovision of ecosystem health, is rising. One new and emerging approach is the use of legal personality to protect water systems in law through the granting of legal rights to rivers. This constitutes a significant development in the fields of environmental law and water resources management, yet little analysis is available of how the approach has been used and applied. We critically examine the new legal rights for rivers using three case studies from Australia, New Zealand, and India. We analyze how legal rights have been created in each case, and the complexity of enforcing these legal rights to protect the rivers. We conclude that legal personality could be a useful alternative approach for river management, provided that the new legal rights are given sufficient force and effect.