Fork restart: unloading FANCD2 to travel ahead.

In this issue of Molecular Cell, Brunner et al.1 reveal that eliminating FANCD2 from stalled forks via FBXL12-mediated degradation enables cells to tolerate oncogene-induced replication stress, making FBXL12 a promising target for cancer treatment.

Analysis of DNA Replication in Fission Yeast by Combing.

DNA replication studies based on population experiments give an average estimate of replication kinetics from many cells. This average replication profile masks the stochastic nature of origin firing in eukaryotes, which is revealed by using single-molecule techniques, such as DNA combing. The analysis of replication kinetics by DNA combing involves isolating DNA from cells that have been pulse-labeled with thymidine analogs and stretching it on a silanized coverslip. The analog-labeled patches on the stretched DNA fibers can then be detected using fluorescent antibodies against the analog. Each fiber represents a part of the genome from a single cell; therefore, it is possible to study the variation in behavior of individual origins from one cell to another. Furthermore, each DNA fiber is uniformly stretched, making it possible to measure distances accurately at kilobase resolution. It is also possible to stretch a high density of fibers on coverslips enabling quantitative data collection.