Site of initiation of replication of the ribosomal genes of pea (Pisum sativum) detected by two-dimensional gel electrophoresis.

The time course of replication of the 9 kb ribosomal DNA repeats of synchronized root cells of pea was followed by two-dimensional gel electrophoresis. The temporal order of appearance of single-stranded replication intermediates shows that replication begins within the subrepeats located in the intergenic spacer region about 1.5 kb downstream from the 3' end of the 25S gene. Hybridization to specific probes indicated that this location is identical to that established earlier by a different method.