RUI: Effects of Dehydration During Growth on Avian Kidney Development

脱水是许多生物体在其一生中可能遇到的一种应激源，包括身体生长和器官发育时期。脱水会引起激素水平的变化，包括抗利尿激素水平的显著增加，而受限的水会抑制全身生长。这些因素加在一起可能会影响许多器官系统的生长和发育。这项研究将特别关注生长过程中脱水对肾脏发育的影响，肾脏是抗利尿激素的主要靶器官。美国国际和平研究所将在日本白鹤身上研究这一问题，这是一种雏鸟必须在孵化后不久就开始自己觅食的物种，因此在早期生命阶段存在非常真实的脱水可能性。初步数据表明，当鸟类长期限水时，肾脏区域(肾髓质)主要与脱水期间的水分保存有关。与此相关的是增强了浓缩尿液的能力，这应该有助于加强节水。这项拟议的研究将进一步探索慢性脱水的功能后果，特别是将检查增强注意力能力的基础。这是否反映了尿液形成速度的变化，激素水平的变化，或者细胞对激素反应的变化？脱水引起的形态变化与功能变化之间是如何关联的？这些变化是可逆的吗，还是在青年时期施加的压力会导致持续到成年的后果？这些研究将有助于确定动物对脱水的生理反应。他们还将研究鸟类肾脏的结构和功能之间的关系，对此仍有许多未知或推测。更广泛地说，这些研究将考察一个重要的动态平衡系统的灵活性，并将解决环境压力对发育途径的重要性这一普遍问题。这种方法应该确定鸟肾的设计和功能方面的限制。这既与个体适应不断变化的环境的能力有关，也与物种入侵和适应不同生境的能力有关。

Dehydration is a stressor that may be encountered by many organisms during their lifetimes, including the period of body growth and organ development. Dehydration induces changes in hormone levels, including prominently increases in levels of anti-diuretic hormone, and the restricted water inhibits general body growth. Together, these factors may influence the growth and the development of many organ systems. The research will focus particularly on the effects of dehydration during growth on development of the kidney, a principle target organ for anti-diuretic hormone. The PI will study this problem in bobwhite quail, a species in which the chicks must forage for themselves beginning shortly after hatching, and in which therefore there is a very real possibility of dehydration during the early life stages. Preliminary data suggest that the region of the kidney (the renal medulla) primarily concerned with water conservation during dehydration hypertrophies when the birds are chronically water restricted. Associated with this is an enhanced ability to concentrate the urine, which should contribute to enhanced water conservation. The proposed research will further explore the functional consequences of chronic dehydration, and in particular will examine the basis for the enhanced concentrating ability. Does this reflect changes in the rate of urine formation, changes in hormone levels, or changes in the cellular response to the hormone? How do morphological changes induced by dehydration correlate with changes in function? Are these changes reversible, or do stresses imposed during youth have consequences that continue into adulthood? These studies will help to define the physiological responses of animals to dehydration. They will also examine the relation between structure and function in the avian kidney, about which much remains unknown or speculative. More generally, these studies will examine the flexibility of an important homeostatic system, and will address the general issue of the importance of environmental stresses on developmental pathways. This approach should identify constraints in design and function of the avian kidney. This relates both to the ability of individuals to acclimate to changing environments, as well as to the ability of species to invade and adapt to different habitats.