Fig. 5.

ORC function is required to allow both stages of replication initiation at DAFC-34B. DNA copy number was examined in a female-sterile allele of ORC, orc2^fs293, which reduces gene amplification. orc2^k43 is a null allele. Amplification in the sibling heterozygotes shows typical amplification levels. In orc2^fs293/orc2^k43, there was no specific increase in gene copy number by stage 10B at DAFC-34B. There was a 1.5- to 2-fold amplification by stage 13 at DAFC-34B, DAFC-62D, and DAFC-66D, likely due to low levels of ORC activity and delayed replication.