Genetic Control of Chicken Plasma Alkaline Phosphatase Isozymes and the Contribution of Isozymes to Enzymic Activity

A large number of studies on a lkaline phosphatase (AP) of chicken plasma have been made during the past forty years. Most of those studies are on the enzymic activity and the polymorphic studies are relatively few . In most of the polymorphic studies of chicken plasma AP, a starch gel electrophoresis has been employed. Major results by other investigators'"' may be summarized as follows. AP comprises two isozymes and they are classified into two types: the one is the .F type having a faster rhoving band in zymogram, the other is the S type having a slower moving band. The gene controlling the F type is completely dominant to the one controlling the S type. By the neuraminidase treatment the F type can be converted to the S type, while the S type is not affected by the same treatment." This means that the enzyme of the F type has sialic acid, while that of the S type has not sialic acid. The mean level in the enzymic activity of the F type is higher than that of the S type." There are two conflicting arguments""' on the association of chicken AP isozyme type and egg production : first, t hat there is no direct association bet\.yeen t hem, and second, that S type is superior in egg production to the F type. Above-mentioned results imply three points to be elucidated as fo llows. Firstly, it is not clear yet how many isozymes chicken plasma AP is composed of. Because, in the result"' from our laboratory, while the zymogram of the S type had only one band by the starch gel electrophoresis, that of the F type showed distinctly two bands by the same procedure. The result suggests that if the adequate electrophoresis other than starch gel be used, the S type as well as the F type may have two bands or more. If the chicken plasma AP be composed of more than two isozymes, their genetic control should be elucidated. Secondarily, activity difference between isozyme types has been noted only by a comparison of mean level while the details of distribution of AP activity have not been elucidated. And if possible, it is necessary to elucidate the biological meaning of the activity difference. Thirdly, it is not clear which argument is cor rect on the association of isozyme type and egg production. The purpose of the present study is to resolve the above three points.