Nucleosome structure in Aspergillus nidulans

The structure of chromatin from Aspergillus nidulans was studied using micrococcal nuclease and DNAase I. Limited digestion with micrococcal nuclease revealed a nucleosomal repeat of 154 base pairs for Aspergillus and 198 base pairs for rat liver. With more extensive digestion, both types of chromatin gave a similar quasi-limit product with a prominent fragment at 140 base pairs. The similarity of the two limit digests suggests that the structure of the 140 base pair nucleosome core is conserved. This implies that the difference in nucleosome repeat lengths between Aspergillus and rat liver is caused by a difference in the length of the DNA between two nucleosome cores. Digestion of Aspergillus chromatin with DNAase I produced a pattern of single-stranded fragments at intervals of 10 bases which was similar to that produced from rat liver chromatin.