Abstract
Many replication initiation sites are synchronously activated in the early stage of carrot (Daucus carota L.) somatic embryogenesis. Using this experimental system, we tried to label replication initiation sites with bromodeoxyuridine (BrdU). We performed pulse labeling of DNA with BrdU during development of globular stage embryos. After 15 min. of labeling, cell nuclei were isolated, and the genomic DNA fiber was spread on slides. Replication initiation sites were visualized by immunolabeling with FITC-conjugated antibody. The replicon size in the early glubular stage was singnificantly shorter than that in other stages. This result was consistent with the observation by Fujimura et al (1981 in this meeting). We successfully isolated labeled regions of DNA fiber by laser microdissectioning.
