A REVERSE TRANSCRIPTION-POLYMERASE CHAIN-REACTION (RT-PCR) APPROACH FOR CLONING AH RECEPTORS FROM DIVERSE VERTEBRATE SPECIES - PARTIAL SEQUENCE OF AN AH RECEPTOR FROM THE TELEOST FUNDULUS-HETEROCLITUS

The aromatic hydrocarbon receptor (AhR) is a ligand-activated transcri ption factor that mediates many of the biological effects of 2,3,7,8-t etrachlorodibenzo-p-dioxin (TCDD) and related halogenated aromatic hyd rocarbons. AhR proteins are expressed in most vertebrate animals, incl uding teleost and elasmobranch fish, but the relationship between pisc ine and mammalian Ah receptors is uncertain. In the present studies, c loning of an Ah receptor cDNA from the teleost Fundulus heteroclitus w as pursued using a reverse transcription-polymerase chain reaction (RT -PCR) approach. Degenerate oligodeoxynucleotides were designed based o n conserved regions of mammalian Ah receptors and the related PAS prot eins Per, ARNT and Sim. The oligonucleotides were used as primers in t he RT-PCR to amplify a portion of an AhR expressed in Fundulus liver. A fragment of approximately 700 bp was amplified and directly sequence d. The deduced amino acid sequence of this fragment (212 residues) sha res significant sequence identity with the PAS domains of the mouse (6 4%), rat (64%) and human (62%) Ah receptors. These data reveal conserv ation of Ah receptor structure between mammals and fish, vertebrate gr oups separated by over 400 million years of evolution. The successful use of RT-PCR to amplify a Fundulus AhR establishes the utility of thi s approach in the phylogenetic analysis of Ah receptor structure and f unction. Copyright (C) 1996 Elsevier Science Ltd