Figure 5.
Localization of H2Av and histone modifications at sites of transgene arrays. Polytene chromosomes from third instar larvae were dissected from a strain carrying one copy (strain 6-2; A–D,I–L) or six copies (strain DX1; E–H,M–P) of a P-element transgene carrying the white gene. Chromosomes were subjected to FISH using sequences from the white gene as a probe and immunohistochemistry with rabbit polyclonal anti-H2Av or anti-H4 acetyl Lys 12 antibodies. The bound antibodies were detected using FITC-labeled goat anti-rabbit (green) and the DNA was detected using Texas red-labeled goat anti-mouse secondary antibodies (red). Arrows indicate the location of the insertion site of the transgene. (A,E,I,M) DNA stained with DAPI. (B) Localization of H2Av in the 6-2 strain at the site of transgene insertion. (C) FISH signal in the 6-2 strain at the site of transgene insertion. (D) Merge of panels A, B, and C.(F) Localization of H2Av in the DX1 strain at the site of transgene insertion. (G) FISH signal in the DX1 strain at the site of transgene insertion. (H) Merge of panels E, F, and G.(J) Localization of H4 acetylated in Lys 12 at the site of transgene insertion in strain 6-2. (K) FISH signal at the site of transgene insertion in strain 6-2. (L) Merge of panels I, J, and K. (N) Localization of H4 acetylated in Lys 12 at the site of transgene insertion in strain DX1. (O) FISH signal at the site of transgene insertion in strain DX1. (P) Merge of panels M, N, and O.