Isolation and identification of two learning-induced brain peptides.
Goldfish were trained either to avoid the blue compartment of a tank and swim into the green compartment or, conversely, to avoid green and prefer blue. Preliminary experiments indicated that acquisition of the avoidance behavior was associated with the presence in the brain of two peptides, one found in blue avoiding (BA), another in green avoiding (GA) fish. With the help of behavioral bioassays, the peptides were isolated and purified, and their structure was determined by ultrasmicroanalytical techniques. The sequence of the BA peptide, pglu-ile-gly-ala-val-phe-pro-leu-lys-tyr-gly-ser-lys-OH was reproduced by synthesis. Sequential analysis of the GA peptide gave two alternative structures, NAc-lys-gly-gln-ile-ala-val-phe-pro-leu-lys-tyr-gly-ser-OH or NAc-lys-gly-ala-val-gln-ile-phe-pro-lys-tyr-gly-ser-OH, both of which are being synthetized to be compared with the natural compound. Overlapping sequences between the BA and GA peptides suggest the existence of a family of peptides associated with behavior based on color discrimination.
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001362:Avoidance Learning; D001923:Brain Chemistry; D003530:Cyprinidae / Q000378:metabolism*; D006054:Goldfish / Q000378:metabolism*; D006868:Hydrolysis; D010455:Peptides / Q000032:analysis*; D014357:Trypsin
D000596:Amino Acids; D010455:Peptides; D014357:Trypsin