SUMMARY RNase H2-dependent Ribonucleotide Excision Repair (RER) removes ribonucleotides incorporated during DNA replication. When RER is defective, ribonucleotides in the nascent leading strand of the yeast genome are associated with replication stress and genome instability. Here we provide evidence that topoisomerase I (Top1) initiates an independent form of repair to remove ribonucleotides from genomic DNA. This Top1-dependent process activates the S phase checkpoint. Deleting TOP1 reverses this checkpoint activation and also relieves replication stress and genome instability in RER-defective cells. The results reveal an additional removal pathway for a very common lesion in DNA, and they imply that the “dirty” DNA ends created when Top1 incises ribonucleotides in DNA are responsible for the adverse consequences of ribonucleotides in RNase H2-defective cells.

While awareness of post-traumatic stress disorder (PTSD) and sexual abuse continues to grow, it has only been during the past few years that the military has realized the prevalence and impact of sexual abuse inflicted upon women while on active military duty. Though Veteran Administration (VA) agencies throughout the United States have given concerted attention to this problem, published resources specific to PTSD and military sexual abuse have been limited. In this article the authors present the results of a 2(1/2)-year endeavor to address the problem of PTSD and military sexual abuse at the Tulsa VA Outpatient Clinic. The project started with a research study and the subsequent initiation of a PTSD women veterans support group, and culminated in the development of resource manuals for both professional staff and women veterans.