Molecular polymorphism, gene regulation and adaptive evolution of duplicated amylase genes in Drosophila.

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DNA sequences of several polymorphic isozymes at duplicated amylase genes were determined in Drosophila melanogaster and its sibling species. Large differences in base sequences between different allozymes compared with identical allozymes indicated long history of different isozymes. In addition, differences between the two duplicated amylase genes within species were much smaller than those of the equivalent locus between different species, indicating the existence of concerted evolution between duplicated genes within species the evidence of concerted evolution was observed only in the coding region but not in the spacer regions. Theoretical study is still under way, concerning the molecular mechanism of this phenomenon. We also cloned a transfacting regulatory gene on the X-chromosome, which appears to affect the inducibility of amylase. The function of this gene is being investigated using P-element mediated transformation technique.