In PNAS this week, researchers at Harvard and MIT report their method to measure DNA damage in a high-throughput manner, which captures single cells into a microwell array and reveals damage through gel electrophoresis. "Spatial encoding enables simultaneous assays of multiple experimental conditions performed in parallel with fully automated analysis," the team writes, adding that their "method also enables novel functionalities, including multiplexed labeling for parallel single cell assays, as well as DNA damage measurement in cell aggregates." The team has also produced 24- and 96-well versions.
International investigators report that transcription factors bZIP19 and bZIP23 regulate the adaptation to zinc deficiency in Arabidopsis thaliana in PNAS this week. The team identified the basic-region leucine-zipper transcription factors using a yeast-one-hybrid screening method. "The bZIP19 and bZIP23 transcription factors, their target genes, and the characteristic cis zinc deficiency response elements they can bind to are conserved in higher plants," the authors write, suggesting that their findings will help to "unravel the molecular mechanism of zinc homeostasis in plants."
Research led by investigators at the Hospital for Sick Children in Toronto published in PNAS this week highlights the genome-wide locations of active and repressive histone modifications in multiple stem cell types. "Our results show that the active modification H3K4me3 has a similar role in the three stem cell types, but the repressive modification H3K27me3 varies in abundance and genome-wide distribution," and suggest alternate mechanisms mediate transcriptional repression in embryonic stem cells, the authors write. This study emphasizes the importance of analyzing progenitor cells both in vitro and in vivo, the researchers conclude.
Researchers report that the ubiquitin ligase Mdm2 targets p53 for proteasomal degradation in PNAS this week. The Karlsruhe Institute of Technology, Germany-led team shows that Mdm2 "facilitates, or at least enhances, the associations of p53 with the proteasome," and that "phosphorylation of the central domain of Mdm2 regulates this process."