of 30-nm fiber structure, no periodicity is observed in Micro-C ligation products (e.g., interactions between nucleosome N and nucleosomes N + 6, N + 12, N + 18, etc., as expected from solenoid models), although the use of the short-length crosslinker formaldehyde in 3C methods necessarily limits the ability to identify such longer-distance signals (Grigoryev et al. 2009). That said, Micro-C products between nucleosomes N and N + 2 were found to be as abundant as N/N + 1 products, generally supporting “two-start” fiber models such as zig-zag 30-nm fiber. Future studies with different length crosslinkers will be needed to further explore the finer-scale details of chromosome fiber structure.
