Validation of a new antiserum directed towards the synthetic c-terminus ofthe FOS protein in avian species: immunological, physiological and behavioral evidence

In the past 10 years, the study of the expression of immediate early genes, such as c-fos, in the brain has become a common method for the identificat ion of brain areas involved in the regulation of specific physiological and behavioral functions. The use of this method in avian species has been lim ited by the paucity of suitable antibodies that cross-react with the FOS pr otein in birds. We describe in this paper the preparation of an antibody di rected against a synthetic fragment of the protein product of the c-fos gen e in chickens (Gallus domesticus). We demonstrate that this new antibody ca n be used in several avian species to study FOS expression induced by a var iety of pharmacological, physiological and behavioral stimuli. Western blot studies indicated that this antibody recognizes a protein of the expected size (47 kDa) but also cross reacts to some extent with proteins of lower m olecular weight that share sequence homology with FOS (Fos-related antigens ). FOS immunocytochemistry was performed with this antibody in four species of birds in three different laboratories utilizing diverse variants of the immunocytochemical procedure. In all cases the antibody provided a reliabl e identification of the FOS antigen. The new antibody described here appear s to be suitable for the study of FOS expression in several different avian species and situations. It is available in substantial amounts and will th erefore make it possible to use FOS expression as a tool to map brain activ ity in birds as has now been done for several years in mammalian species. ( C) 1999 Elsevier Science B.V. All rights reserved.