Fig. 4. Polytene chromosome distribution of H3S10ph in response to heat shock treatment. (A-F) Acid-free polytene chromosome squash preparations from female third instar Drosophila larvae triple labeled with antibodies to Pol IIo^ser2 (green), H3S10ph (red), and with Hoechst (DNA, blue/gray). H3S10ph labeling with antibodies from Epitomics (A), Cell Signaling (C) or Upstate (E) with (+HS) and without (-HS) heat shock treatment. (B,D,F) Higher magnification images of the heat shock-induced puffs 87A/C (boxed regions) labeled by H3S10ph antibodies from Epitomics (B), Cell Signaling (D) or Upstate (F). (G) Immunoblots of protein extracts from salivary glands from wild-type larvae without heat shock treatment (wt) and with heat shock treatment [wt (HS)] labeled with H3S10ph antibody from Cell Signaling, Epitomics or Upstate. Labeling with histone H3 (H3) antibody was used as a loading control. (H) Immunoblots of protein extracts from salivary glands from wild-type larvae without heat shock treatment (wt) and with heat shock treatment [wt (HS)] labeled with Pol IIo^ser2 antibody. Labeling with lamin antibody was used as a loading control.