Chromatrap has published a new technical article that discusses and describes methodologies to increase Chromatin Immunoprecipitation (ChIP) efficiency by making sure chromatin in your samples is sheared to the correct size range.
The authors describe how for every chromatin preparation it is essential to check the chromatin is sheared to fragments between 100-500bp. They emphasise using a microfluidics platform is the most accurate measure of quantifying DNA.
Problems associated with over or under sheared Chromatin fragments are discussed and a protocol for optimised enzymatic shearing described. As some cells are resistant to lysis the authors also describe an optimised sonication methodology to ensure a successful ChIP result.