Chromatin structure of telomere domain in human sperm

Telomeres in human sperm nucleus are clustered at the nuclear periphery. Ch romosomes in the sperm are highly condensed with protamines, however, a sma ll portion of DNA remains associated with histones; the role of the nucleoh istone is unknown. To examine structure of the telomeric chromatin, the spe rm nuclei were treated with micrococcal nuclease. Chromatin released by the digestion was free from protamines, but contained histones and revealed nu cleosomal organization. It was enriched with telomeric DNA organized into c losely spaced nucleosomes with a periodicity of 148 +/- bp. Thus, while the most of the sperm genome is packed into extremely dense nucleoprotamine st ructure, at least a part of the telomeric DNA is arranged into nucleosomes and can be released by the nuclease. We suggest that telomeres might be amo ng the first structures in the sperm nucleus that respond to oocyte signals for male pronucleus development at fertilization. (C) 2000 Academic Press.