Meeting Abstract

20.5  Jan. 5  Isolation of a cDNA encoding a third form of Gonadotropin-Releasing Hormone from the Sea Lamprey Petromyzon marinus KAVANAUGH, S.I.*; SOWER, S.A.; Univ. of New Hampshire, Durham sik@unh.edu

As a member of the class Agnatha, sea lampreys, Petromyzon marinus, represent one of the two oldest lineages of vertebrates. Previously, two isoforms of GnRH have been isolated and cloned from the sea lamprey. Therefore, the objective of this study was to search the lamprey genome for evidence of a novel form of GnRH and then to determine the expression and its evolutionary relationship with current forms of GnRH. The mapping of the sea lamprey genome started in 2005 and has not yet been completed or annotated. However, 10,000,000 sequences have been released since 2005. Trace files were downloaded from: ftp.ncbi.nlm.gov/pub/TraceDB/petromyzon_marinus in FASTA format. These files were uncompressed and then �chopped� into smaller files to allow the BLASTing to be done locally against a complete NCBI non-redundant database using software provided by NCBI at: http://www.ncbi. nlm.nih.gov/Tools. Search parameters were blastall �p blastx �a 2 �d GnRH �e0.1 �v10 �b10. The results of this search indicated the presence of a third form of GnRH named lamprey GnRH-II. Similar to the other vertebrate GnRHs, lamprey GnRH-II is highly conserved with 10 amino acids and conserved C- and N-terminal ends. Lamprey GnRH-II has a novel amino acid, phenylalanine, in position 8, the most variable position of the GnRH family. Initial reverse transcriptase-polymerase chain reactions indicate lamprey GnRH-II is expressed in the brain and may be another neurohormone. Future anatomical, phylogenetic, and developmental studies will be required to determine if lamprey GnRH-II is a member of the GnRH-IV family proposed by Silver et al., 2004.