Figure 1.
H3-K9 methylation associated with the immunoglobulin heavy chain gene segments in Rag1−/− bone marrow pro–B cells, thymocytes and bone marrow–derived macrophages. (a) Chromatin immunoprecipitation assays, with anti–dimethylated H3-K9, of primary Rag1−/− bone marrow pro–B cells after short-term culture in IL-7; primary thymocytes; and bone marrow–derived macrophages. Bottom (c-Myc), the Myc promoter serves as a negative control. Wedges indicate 1:5 serial dilutions of 1% input DNA and 1:2 dilutions of H3-K9 immunoprecipitated fraction DNA; each begins (far left) with an undiluted sample. (b) Immunoprecipitated (IP) DNA from a, quantified with a phosphorimager; the results are presented as percentage of input. Data are from one experiment representative of multiple experiments (four pro–B cell cultures, five thymocyte preparations and three macrophage cultures). BD (below detection), intensities that were not at least twofold greater than that of the Myc promoter or background cannot be accurately quantified. −(far right), negative control. Bottom, the VH locus and relative location of the gene segments. (c) Chromatin immunoprecipitation assays, done as described in a with primers for Xist (X3), the VH gene V10b RSS and the Myc promoter, of embryonic fibroblasts from female mice (Female MEFs). Input dilutions begin at 1:5. Right, band intensities of immunoprecipitated DNA, presented as percentage of input (vertical axis), representative of three experiments.