Hagey Lee R, Møller Peter R, Hofmann Alan F, Krasowski Matthew D
Department of Medicine, University of California-San Diego, MC 0063, La Jolla, California 92093, USA.
Physiol Biochem Zool. 2010 Mar-Apr;83(2):308-21. doi: 10.1086/649966.
Bile salts are the major end metabolites of cholesterol and are also important in lipid and protein digestion, as well as shaping of the gut microflora. Previous studies had demonstrated variation of bile salt structures across vertebrate species. We greatly extend prior surveys of bile salt variation in fish and amphibians, particularly in analysis of the biliary bile salts of Agnatha and Chondrichthyes. While there is significant structural variation of bile salts across all fish orders, bile salt profiles are generally stable within orders of fish and do not correlate with differences in diet. This large data set allowed us to infer evolutionary changes in the bile salt synthetic pathway. The hypothesized ancestral bile salt synthetic pathway, likely exemplified in extant hagfish, is simpler and much shorter than the pathway of most teleost fish and terrestrial vertebrates. Thus, the bile salt synthetic pathway has become longer and more complex throughout vertebrate evolution. Analysis of the evolution of bile salt synthetic pathways provides a rich model system for the molecular evolution of a complex biochemical pathway in vertebrates.
胆汁盐是胆固醇的主要终末代谢产物，在脂质和蛋白质消化以及肠道微生物群的形成中也很重要。先前的研究已经证明了脊椎动物物种间胆汁盐结构的差异。我们极大地扩展了之前对鱼类和两栖动物胆汁盐差异的调查，特别是对无颌类和软骨鱼类胆汁胆汁盐的分析。虽然所有鱼类目之间胆汁盐存在显著的结构差异，但胆汁盐谱在鱼类目内通常是稳定的，并且与饮食差异无关。这个庞大的数据集使我们能够推断胆汁盐合成途径的进化变化。推测的祖先胆汁盐合成途径，可能以现存的盲鳗为例，比大多数硬骨鱼和陆生脊椎动物的途径更简单、更短。因此，在整个脊椎动物进化过程中，胆汁盐合成途径变得更长、更复杂。对胆汁盐合成途径进化的分析为脊椎动物复杂生化途径的分子进化提供了一个丰富的模型系统。
