SILVER, M.S.*; LEE, K.J.; TAKAHASHI, A; KAWAUCHI, H; JOSS, J; SOWER, S.A.: Molecular Phylogenetic Analysis Within The Petromyzontiforme Lineage Using The cDNA For Lamprey Gonadotropin Releasing Hormone-III

The lamprey lineage is generally considered to be divided into three families, the Petromyzonidae, or holarctic family, found in the northern hemisphere, and the two southern hemisphere families, the Geotriidae and Mordaciidae. The phylogeny of these families has been primarily based on size, shape, and distribution of dentition. The objective of this research was to isolate and sequence the cDNA precursor of lamprey GnRH-III in representative species of each of the three families of lamprey in order to assess their phylogenetic relationship. The cDNA encoding prepro-lamprey GnRH-III was isolated from two holarctic species, Petromyzon marinus and Lampetra tridentatus, and one from each southern hemisphere species, Geotria australis and Mordacia mordax. Initial segments of the transcript where isolated using PCR on cDNA constructed from total RNA that were extracted from each respective species hypothalami. 5?RACE was used to amplify the rest of the template using the Marathon cDNA Amplification Kit (CLONTECH) and full-length transcripts were isolated. Using PAUP v4.0, the molecular phylogenetic relationship of lamprey GnRH-III between the three families of lamprey was investigated. These data suggest that the lamprey GnRH-III cDNAs of the two southern hemisphere species are highly divergent from the lamprey GnRH-III cDNA of the holarctic species. (Supported by the NSF to SAS and Intl NSF-JSPS to SAS and HK).