CHANGES IN THE NUCLEAR MATRIX OF CHICKEN ERYTHROCYTES THAT ACCOMPANY MATURATION

The protein composition and structure of nuclear matrices isolated fro m adult chicken immature and mature erythrocytes were analysed. Visual ization of nuclear matrices by electron microscopy showed that immatur e-erythrocyte nuclear matrices had internal structures, while most mat ure-erythrocyte nuclear matrices did not. Both mature- and immature-er ythrocyte nuclear matrices were surrounded by a fibrous network of int ermediate filaments. Two-dimensional gel electrophoretic analysis of p roteins obtained from fractionated nuclear matrices led to the assignm ent of the proteins as components of the nuclear porelamina, internal matrix, or cytoskeleton. Common and different proteins belonging to on e of the three groups were identified in nuclear matrices of immature and mature erythrocytes. Investigation of the partitioning of histone deacetylase activity, an enzyme associated with the internal matrix, a mong the erythroid nuclear matrix fractions provided evidence that mat ure- and immature-erythrocyte nuclear matrices have internal structure s. However, the activity of histone deacetylase and level of internal matrix proteins from mature-erythrocyte nuclear matrices were less tha n those from immature-erythrocyte matrices. The low levels of nuclear RNA and internal matrix proteins may account for lack of visual eviden ce for an internal matrix in mature erythrocytes.