(A) TR binding to the target gene TRβ leads to the recruitment of RNA polymerase α (Pol II) and loss of core histones during T3 induced metamorphosis in Xenopus tropicalis intestine. Tadpoles at stage 54 were treated with or without T3 for 2 days, and the intestine was isolated for ChIP assay with anti-TR, anti-Pol α, anti-H3, or anti-H2B antibody. The immunoprecipitated DNA was analyzed by qPCR for the presence of the TRE region of the TRβ promoter or a region of TRβ exon 5 as a negative control. Note that TR is bound to the promoter but not the exon 5 in the absence of T3 in premetamorphic tadpoles. In the presence of T3, TR binding to the TREs was increased at the promoter, accompanied by the recruitment Pol II and reduction in total histones at the TRE region. Increased Pol II was also observed in the exon region due to increased transcription in the presence of T3. Error bars indicate s.e.m. (n=3). The one and two stars indicate pairs of samples with significant differences, p < 0.05 and p < 0.01, respectively. (B). Changes in all histone activation marks but only one of the two repression marks correlate with gene activation by liganded TR. Premetamorphic tadpoles at stage 54 were treated with T3 for 2 days. The intestine was isolated and subjected to ChIP assay with anti-AcH3, anti-H3K79me3, anti-H3K27me3 or anti-H3K9me3 antibody. ChIP signals were normalized with the ChIP signals of histone H3 in (A) for the corresponding promoter/exon regions. Error bars indicate s.e.m. (n=3). The one and two stars indicate pairs of samples with significant differences, p < 0.05 and p < 0.01, respectively. See  for details.