Evolution of a New Function by Degenerative Mutation in Cephalochordate Steroid Receptors
A) Hormone-activated transcription of a luciferase reporter gene by the ligand-binding domains of BfSR (black) and BfER (gray) is shown as fold activation relative to vehicle-only control. All hormone treatments were at 1 µM concentration. DES, diethylstilbesterol; DHT, dihydrotestosterone; DHEA, dehydroepiandrosterone; Prog, progesterone. Mean+/−SE of three replicates is shown. B) Dose-response relationship for transcriptional activation by BfSR LBD in the presence of increasing concentrations of estradiol (black) and estrone (gray).