Molecular characterization and evolution of the amylase multigene family of Drosophila ananassae

Drosophila ananassae is known to produce numerous alpha-amylase variants. W e have cloned seven different Amy genes in an African strain homozygous for the AMY1,2,3,4 electrophoretic pattern. These genes are organized as two m ain clusters: the first one contains three intronless copies on the 2L chro mosome arm, two of which are tandemly arranged. The other cluster, on the 3 L arm, contains two intron-bearing copies. The amylase variants AMY1 and AM Y2 have been assigned to the intronless cluster, and AMY3 and AMY4 to the s econd one. The divergence of coding sequences between clusters is moderate (6.1% in amino acids), but the flanking regions are very different, which c ould explain their differential regulation. Within each cluster, coding and noncoding regions are conserved. Two very divergent genes were also cloned , both on chromosome 3L, but very distant from each other and from the othe r genes. One is the Amyrel homologous (41% divergent), the second one, Amyc 1 (21.6% divergent) is unknown outside the D. ananassae subgroup. These two genes have unknown functions.