H3K4me1 ChIP-Seq experiment using cells from stage 15 Drosophila melanogaster embryos sorted by reporter gene activity
Embryos were collected during a 1h window in apple juice agar plates. Then, the plates were incubated at 25 °C for 12 h leading to a population composed exclusively by stage 15 embryos. These embryos were then dechorionated and fixed with paraformaldehyde according to standard procedures (Sullivan, William, Michael Ashburner, and R. Scott Hawley's Drosophila protocols. Cold Spring Harbor Laboratory Press, 2000.). Stage 15 embryos from a line containing svb_E10::GFP and svb_7::dsRed transgenes were cross-linked and dissociated. Then the E10::GFP and 7::dsRed nuclei were isolated by fluorescence activated cell sorter. Chromatin from 250,000 nuclei of each cell sub-populations was isolated and used for ChIP with anti-H3K4me1 (Merck, 07-436) and anti-H3 antibodies (abcam, ab1791) using the iDeal ChIP-seq kit from Diagenode, according to the manufacturer's instructions (https://www.diagenode.com/en/p/ideal-chip-seq-kit-x24-24-rxns). Libraries were prepared using the Ovation Ultralow V2 DNA-Seq library preparation kit (NuGen, https://lifesciences.tecan.com/ultralow-dna-seq-library-prep-kit) according to the manufacturer's instructions.