The sea lamprey (Petromyzon marinus) is a jawless vertebrate at an evolutionary nexus between invertebrates and jawed vertebrates. Lampreys are known to possess the arginine vasotocin (AVT) hormone utilized by all non-mammalian vertebrates. We postulated that the lamprey would possess AVT receptor orthologs of predecessors to the arginine vasopressin (AVP)/oxytocin (OXT) family of G protein-coupled receptors found in mammals, providing insights into the origins of the mammalian V1A, V1B, V2 and OXT receptors. Among the earliest animals to diverge from the vertebrate lineage in which these receptors are characterized is the jawed, cartilaginous elephant shark, which has genes orthologous to all four mammalian receptor types. Therefore, our work was aimed at helping resolve the critical gap concerning the outcomes of hypothesized large-scale (whole-genome) duplication events. We sequenced one partial and four full-length putative lamprey AVT receptor genes and determined their mRNA expression patterns in 15 distinct tissues. Phylogenetically, three of the full-coding genes possess structural characteristics of the V1 clade containing the V1A, V1B and OXT receptors. Another full-length coding gene and the partial sequence are part of the V2 clade and appear to be most closely related to the newly established V2B and V2C receptor subtypes. Our synteny analysis also utilizing the Japanese lamprey (Lethenteron japonicum) genome supports the recent proposal that jawless and jawed vertebrates shared one-round (1R) of WGD as the most likely scenario.
Bibliographical noteFunding Information:
We thank Shannon RedBrook, Chris Osberg and Dr. Larry Wittmers for technical assistance, and Drs. Sara Zimmer, Kevin Diebel, Lynne Bemis, and Teresa Rose-Hellekant for reviewing the manuscript. This work is the result of research sponsored by the Minnesota Sea Grant College Program supported by the NOAA office of Sea Grant, United States Department of Commerce , under grant No. NA10OAR4170069 . The U.S. Government is authorized to reproduce and distribute reprints for government purposes, notwithstanding any copyright notation that may appear hereon. This paper is journal reprint No. JR-623 of the Minnesota Sea Grant College Program.
© 2016 Elsevier Inc.
Copyright 2016 Elsevier B.V., All rights reserved.
- Agnathan vertebrate
- G protein-coupled receptor
- Molecular evolution
- Sea lamprey
- Whole-genome duplication