title: 'Obesity' is healthy for cetaceans? Evidence from pervasive positive selection in genes related to triacylglycerol metabolism.
abstract: Cetaceans are a group of secondarily adapted marine mammals with an enigmatic history of transition from terrestrial to fully aquatic habitat and subsequent adaptive radiation in waters around the world. Numerous physiological and morphological cetacean characteristics have been acquired in response to this drastic habitat transition; for example, the thickened blubber is one of the most striking changes that increases their buoyancy, supports locomotion, and provides thermal insulation. However, the genetic basis underlying the blubber thickening in cetaceans remains poorly explored. Here, 88 candidate genes associated with triacylglycerol metabolism were investigated in representative cetaceans and other mammals to test whether the thickened blubber matched adaptive evolution of triacylglycerol metabolism-related genes. Positive selection was detected in 41 of the 88 candidate genes, and functional characterization of these genes indicated that these are involved mainly in triacylglycerol synthesis and lipolysis processes. In addition, some essential regulatory genes underwent significant positive selection in cetacean-specific lineages, whereas no selection signal was detected in the counterpart terrestrial mammals. The extensive occurrence of positive selection in triacylglycerol metabolism-related genes is suggestive of their essential role in secondary adaptation to an aquatic life, and further implying that 'obesity' might be an indicator of good health for cetaceans.
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China.
authors.forename: Zhengfei
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China.
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China.
authors.forename: Shixia
authors.initials: S
authors.lastname: Xu
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China.
authors.forename: Wenhua
authors.initials: W
authors.lastname: Ren
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China.
authors.forename: Kaiya
authors.initials: K
authors.lastname: Zhou
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China.
authors.forename: Guang
authors.initials: G
authors.lastname: Yang
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002591:Cetacea / Q000235:genetics* / Q000378:metabolism*; D016000:Cluster Analysis; D019295:Computational Biology / Q000379:methods; D050356:Lipid Metabolism / Q000235:genetics; D008322:Mammals; D053858:Metabolic Networks and Pathways / Q000235:genetics; D009765:Obesity / Q000235:genetics* / Q000378:metabolism*; D012641:Selection, Genetic; D014280:Triglycerides / Q000378:metabolism*
chemical_list: D014280:Triglycerides