Meeting Abstract

34.1  Jan. 5  An androgen-receptor signaling system found in the sea lamprey, Petromyzon marinus BRYAN, M.B.*; SCOTT, A.P.; LI, W.; Michigan State University; The Centre for Environment, Fisheries and Aquaculture Science; Michigan State University bryanmar@msu.edu

The nuclear receptor superfamily is ancient lineage of transcription factors, which are predominately activated by small ligands. As part of this superfamily, the gonadal steroid receptors have received much attention due to both their importance as a key evolutionary innovation within the vertebrate lineage, and in regulation of development and reproduction. Current theories regarding the evolution of steroid receptors have relied heavily on information garnered from the sea lamprey, Petromyzon marinus. As one of only two extant Agnathan lines and as a vertebrate taxon that evolved over 500 million years ago, lampreys are a key group in which questions regarding the timing of vertebrate innovations, such as the steroid-receptor systems, can be examined. Here we present new findings showing the existence of an androgen receptor (AR) in the sea lamprey and thereby demonstrating that receptors for this class of steroid evolved before the agnathan-gnathostome divergence, which is much earlier than previous assumptions. The lamprey AR has binding characteristics that are typical of other vertebrate steroid receptors (e.g. it can be extracted from the nucleus as well as the cytoplasm and also binds to DNA). Although some ligand is found in plasma, it is mainly present in the testis (in association with the AR), and levels in the testis increase after stimulation with lamprey GnRH. We also demonstrate a putative hormonal role for androgens in lampreys. This research was supported by the Great Lake Fishery Commission and National Science Foundation #IOB 0450916.