Premigratory fat metabolism in hummingbirds： A Rumsfeldian approach

作     者：Raul K. SUAREZ 

作者机构：Department of Ecology Evolution and Marine Biology University of California Santa Barbara California 93106 USA 

出 版 物：《Current Zoology》 (动物学报（英文版）)

年 卷 期：2013年第59卷第3期

页      面：371-380页

核心收录：

学科分类：0710[理学-生物学] 090502[农学-动物营养与饲料科学] 07[理学] 0905[农学-畜牧学] 09[农学] 071002[理学-动物学] 

基　　金：I am deeply grateful to EW. Hochachka  C.L. Gass  K.C. Welch  Jr.  J.R.B. Lighton  C. Martinez del Rio and O. Mathieu-Costello for their contributions to the research that led to the ideas presented and questions raised in this paper. Research on which this article is based was funded by the U.S. National Science Foundation (IOB 0517694) 

主　　题：Lipid synthesis Metabolic rate Metabolic regulation Muscle energy metabolism Sugar oxidation 

摘      要：Hummingbird migration is a remarkable feat, given the small body sizes of migratory species, their high metabolic rates during flight and the long distances traveled using fat to fuel the effort. Equally remarkable is the ability of premigratory hummingbirds in the wild to accumulate fat, synthesized from sugar, at rates as high as 10% of body mass per day. This paper summarizes, using Rumsfeldian terminology, ＂known knowns＂ concerning the energetics of hummingbird migration and premi- gratory fattening. Energy metabolism during hover-feeding on floral nectar is fueled directly by dietary sugar through the path- way recently named the ＂sugar oxidation cascade＂. However, flight without feeding for more than a few minutes requires shifting to fat as a fuel. It is proposed that behavior and metabolic fuel choice are coadapted to maximize the rate of fat deposition during premigratory fattening. The hummingbird liver appears to possess extraordinarily high capacities for fatty acid synthesis. The analysis of ＂known knowns＂ leads to identification of ＂known unknowns＂, e.g., the fates of dietary glucose and fructose, the regulation of fat metabolism and metabolic interactions between liver and adipose tissue. The history of science behooves recog- nition of ＂tmknown unknowns＂ that, when discovered serendipitously, might shed new light on fundamental mechanisms as well as human pathological conditions .