Effect of N-6 2'-O-dibutyryl adenosine 3'-5'monophosphate (dibutyryl cyclic AMP) on the condenstion of the X chromosome into the form of a Barr body]

Addition of exogen DB-c AMP in medium of human fibroblasts culture, with 46 XX karyotypes, enables us to observe a high frequency of Barr bodies, about 80 or 85%. This observation suggests that the condensation of the X chromosome in the form of Barr bodies depends on the level of endogen cyclic AMP.