DNA is packaged in the cell nucleus by wrapping around basic proteins called histones. The histone/DNA complex is called chromatin. Most chromatin consists of histones H2A, H2B, H3, H4 and a linker histone H1. The erythrocytes in mammals do not have a nucleus and therefore have no net protein or DNA synthesis.
Amphibians and avians do have a nucleus but the genetic apparatus is shutdown, presumably by the presence of the linker histone H5. We are studying the role that H5 plays in the control of replication and transcription by studying the relative binding affinity of H5 compared to H1. Thermal denaturation curves and isothermal titration calorimetry are the primary tools being used to study the binding affinity of the linker histones.