Thyroid hormone deiodinase type 2 mRNA levels in sea lamprey (Petromyzon marinus) are regulated during metamorphosis and in response to a thyroid challenge

► A deiodinase type 2 (D2) cDNA was isolated and sequenced from Petromyzon marinus. ► P. marinus D2 mRNA is the longest yet reported (>9 Kb). ► D2 mRNA levels in the liver and intestine vary during P. marinus metamorphosis. ► Intestinal and hepatic D2 mRNA levels were altered in response to thyroid challenges.