Parental-specific DNaseI HSSs near and around CGIs 4, 5, and 8. (A) DNaseI HSS on paternal allele near CGI8. Nuclei isolated from BPF₁ or PBF₁ primary fibroblast in mice were treated with an increasing amount of DNase I. After extraction, the DNA was digested with BclI or BclI and HindIII as indicated and subjected to Southern blotting analysis. The blots were probed with 1 kb of fragment amplified with the primer sets Lit-3 and Lit-5. The diagram shown below depicts Lit1 gene and CGI8 surrounded by restriction sites, with the start of transcription represented by the bent arrow; gray boxes below the gene represent CGI8a and 8b. Downward arrowhead indicates a nuclease HSS detected on the paternal chromosome, designated HSS-1. B, BclI; H,HindIII. HindIII is the polymorphic recognition site in PWK but not in B6 mouse. (B) HSS on maternal allele around CGIs 4 and 5. The same DNase I-treated DNA was used as above and treated similarly. DraI and BspH1 were used.BspH1 is the polymorphic restriction site in B6 mouse. The probe is a p57^Kip2 cDNA. The HSSs obtained were designated HSS-2 and HSS-3. D, DraI; B, BspH1.