IDENTIFICATION OF C-FOS RELATED GENES AND THEIR INDUCTION BY NEURAL ACTIVATION IN RAINBOW-TROUT BRAIN

A number of studies have shown that the induction of c-fos gene is an indicator of the responses of cells and tissues to the environmental s timuli. In the present study, using RT-PCR-based strategy, we isolated , rom the brain of the rainbow trout, two partial cDNA clones (RT-fos1 and RT-fos2) that code proteins homologous to c-Fos proteins of highe r vertebrates. Sequence analysis of the two clones indicated that the two rainbow trout clones are very similar to each other over the entir e cloned region (88% amino acid identity) and showed moderate similari ty to c-Fos proteins of higher vertebrates (40% amino acid identity wi th human c-Fos). Two functionally important domains (i.e. the leucine zipper and zinc finger) are highly conserved among all the vertebrate species analyzed, although the region between the two domains was high ly variable between different species. Intraperitoneal administration of kainic acid, a stable agonist of glutamate receptors, transiently i nduced the mRNAs for both RT-fos1 and RT-fos2 in the rainbow trout bra in. These results indicate that the expression pattern of the two clon es can be utilized as a suitable anatomical marker for the increased n eural activities in salmonid fish brain to investigate the higher orde r behavior such as the learning and imprinting of odors of the home ri ver. (C) 1998 Elsevier Science B.V.