Figure 3. Altered cell cycle distribution and replication fork progression in ORC1 knockdown cells.

(A) DNA samples from log phase cultures were subjected to neutral-neutral 2D gel analysis following digestion with HindIII and enrichment for RIs on BND cellulose. Left panels: blots were probed with the rDNA 5′ NTS probe (wild type (WT) and ORC1 knockdown (ORC1-KD) strains. Right panel, schematic of the palindromic HindIII fragment spanning the two inverted copies of the 5′ NTS, promoter (pro) and replication origins (D1 and D2). (B) Representative images for DNA fibers sequentially labeled with IdU and CldU. Inter-origin distance and fork velocity were measured in log phase CU428 and ORC1-KD cells (see Materials and Methods for details).