title: Occurrence of two functionally distinct proopiomelanocortin genes in all modern lampreys.
abstract: The lampreys (family Petromyzontidae) are divided into three subfamilies, the Petromyzontinae in the Northern Hemisphere and the Geotriinae and Mordaciinae in the Southern Hemisphere. We previously found two proopiomelanocortin subtypes, proopiocortin (POC) and proopiomelanotropin (POM) in sea lamprey, Petromyzon marinus (Petromyzontinae). POC encoding adrenocorticotropic hormone (ACTH) and beta-endorphin (beta-END) is expressed in the pars distalis of the pituitary, while POM encoding melanophore-stimulating hormone (MSH)-A and B together with a different beta-END is expressed in the pars intermedia of the pituitary. All these hormonal segments are encoded on the third exon in both POC and POM. Here, we demonstrate the presence of both POC and POM genes in Geotria australis (Geotriinae) and Mordacia mordax (Mordaciinae) by molecular cloning of the third exons with the polymerase chain reaction using genomic DNA or pituitary cDNA. Molecular phylogenetic analysis showed that the POC and POM are distinctly different for the Southern Hemisphere lampreys as they are for P. marinus. Moreover, the relationship of each hormonal segments in POC and POM between Geotria, Mordacia, and Petromyzon is inconsistent. Immunocytochemical studies showed that the distribution of POC and POM in the pituitaries of the Southern Hemisphere lampreys is the same as that in the Northern Hemisphere. Taken together, these findings suggest that the duplication event which generated the two genes may have occurred in a common ancestor of the three extant lamprey subfamilies.
authors.affiliation: Laboratory of Molecular Endocrinology, School of Fisheries Sciences, Kitasato University, Sanriku, Ofunato, Iwate 022-0101, Japan. akiyoshi@kitasato-u.ac.jp
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Takahashi
authors.forename: Osamu
authors.initials: O
authors.lastname: Nakata
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Moriyama
authors.forename: Masumi
authors.initials: M
authors.lastname: Nozaki
authors.forename: Jean M P
authors.initials: JM
authors.lastname: Joss
authors.forename: Stacia A
authors.initials: SA
authors.lastname: Sower
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawauchi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D040461:Gene Components; D007798:Lampreys / Q000235:genetics*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism; D011333:Pro-Opiomelanocortin / Q000235:genetics* / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics; D013045:Species Specificity; D014018:Tissue Distribution
chemical_list: D020033:Protein Isoforms; D011333:Pro-Opiomelanocortin