Characterization of two microsatellites in chicken monoamine oxidase A

We surveyed two polymorphic microsatellites in a candidate gene for fear response, monoamine oxidase A (MAOA), in chicken. Two hundred and eighty chickens from five breeds (Nagoya, Mikawa, White Leghorn, White Plymouth Rock, and Rhode Island Red) were investigated. A thymine (T) repeat and an adenine (A) repeat were found on MAOA intron 4 (CMin4T) and intron 9 (CMin9A), respectively. Nine alleles (127-bp to 166-bp) in CMin4T and six alleles (184-bp to 198-bp) in CMin9A were detected. A 128-bp allele in CMin4T was observed in the Nagoya breed only, implying a highly useful marker for discriminating the Nagoya breed from other breeds. In addition, the Mikawa breed had the fixed 127-bp and 198-bp alleles in CMin4T and CMin9A, respectively. The Nagoya breed chickens show densely cowardly behavior, but the Mikawa breed chickens do not show the same behavior. The current results may indicate that MAOA is an informative candidate gene for breed difference.