DNA replication-dependent formation of joint DNA molecules in Physarum polycephalum.
Two-dimensional neutral/neutral agarose gel electrophoresis is used extensively to localize replication origins. This method resolves DNA structures containing replication forks. It also detects X-shaped recombination intermediates in meiotic cells, in the form of a typical vertical spike. Intriguingly, such a spike of joint DNA molecules is often detectable in replicating DNA from mitotic cells. Here, we used naturally synchronous DNA samples from Physarum polycephalum to demonstrate that postreplicative, DNA replication-dependent X-shaped DNA molecules are formed between sister chromatids. These molecules have physical properties reminiscent of Holliday junctions. Our results demonstrate frequent interactions between sister chromatids during a normal cell cycle and suggest a novel phase during DNA replication consisting of transient, joint DNA molecules formed on newly replicated DNA.
Bénard
M
M
Institut André Lwoff, UPR-1983, Laboratoire Organisation Fonctionnelle du Noyau, 94801 Villejuif, France.
Maric
C
C
Pierron
G
G
D000818:Animals; D002453:Cell Cycle / Q000235:genetics; D002842:Chromatids / Q000648:ultrastructure; D004247:DNA / Q000648:ultrastructure*; D004261:DNA Replication / Q000235:genetics*; D015180:Electrophoresis, Gel, Two-Dimensional; D006918:Hydroxyurea / Q000494:pharmacology; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D016839:Physarum polycephalum / Q000235:genetics*; D018741:Replication Origin; D016196:S Phase / Q000235:genetics; D013696:Temperature
D004247:DNA; D008274:Magnesium; D006918:Hydroxyurea