In mammalian spermatozoa, most of the genome is densely packaged by protamines, whereas only a very small percentage of nucleosomes is retained. Genome-wide nucleosome occupancy studies in mouse spermatozoa containing one percent residual histones now demonstrate that nucleosomes in sperm mainly localize to unmethylated CpG-rich sequences in a histone variant–specific manner and are differentially modified.
- Serap Erkek
- Mizue Hisano
- Antoine H F M Peters
