INTERPHASE CHROMOSOMES OF FRIEND-S CELLS ARE ATTACHED TO THE MATRIX STRUCTURES THROUGH THE CENTROMERIC TELOMERIC REGIONS

DNA of the attachment sites of Friend erythroleukemia cells, isolated according to the conventional procedure, represents short, nuclease-re sistant fragments with sizes below 400 bp, belonging to the class of m ouse satellite. A number of experiments have indicated that their unus ual resistance is due to complexing with RNA. By various approaches, i t was confirmed that similar fragments might be recovered from total D NA following extensive digestion with DNase I. In situ hybridizations revealed further that at mitosis the sequences of the attachment sites are located at the centromeric/telomeric regions of the chromosomes, while at interphase they are redistributed into 9-13 well-defined clus ters spread throughout the entire nuclear area. Parallel biochemical a nd electronomicroscopic studies have clarified, moreover, that the all three compartments of the matrix harbor such sequences. Thus, it appe ars that the attachment sites described function only at interphase, a nchoring the both ends of each interphase chromosome to the matrix str uctures.