Understanding the accurate temporal and spatial regulation of gene expression during development requires knowledge of the spectrum of transcription factors and cofactors involved and their functional interplay with chromatin. Chromatin immunoprecipitation (ChIP) has become a powerful technique that allows us to do so. A typical ChIP assay involves (1) treating cells or tissues with formaldehyde to rapidly crosslink chromatin-associated proteins to DNA, (2) shearing chromatin by sonication into small fragments, (3) immunoprecipitation of the proteins of interest, (4) reversal of crosslinking, and (5) quantitating the specific associated DNA sequences by PCR. Here we present and discuss the protocols we have developed over the years for ChIP assays usingXenopusoocytes and tadpole tissues as experimental materials.
