DPA, A MEMBER OF THE MCM FAMILY, IS REQUIRED FOR MITOTIC DNA-REPLICATION BUT NOT ENDOREPLICATION IN DROSOPHILA

We have isolated the Drosophila disc proliferation abnormal (dpa) gene , a member of the; MCM family of DNA replication factors. Members of t his family of proteins are required for DNA replication in yeast, A dp a null mutant dies during pupal stages because imaginal tissues necess ary for the formation of the adult fly fail to proliferate normally. B eginning in late embryogenesis BrdU labeling reveals DNA replication d efects in mitotically proliferating cells. In contrast, dpa is dispens able for endoreplication, a specialized cell cycle consisting of conse cutive rounds of S phases without intervening mitosis. Our studies sug gest an essential role for dpa in mitotic DNA replication but not in e ndoreplication, Thus, dpa is not a general replication factor but may play a specialized regulatory role in DNA replication.