B. Nadel et al., CELL-SPECIFIC ORGANIZATION OF THE 5S RIBOSOMAL-RNA GENE-CLUSTER DNA LOOP DOMAINS IN SPERMATOZOA AND SOMATIC-CELLS, Biology of reproduction, 53(5), 1995, pp. 1222-1228
DNA in eucaryotic cells is organized into loop domains, ranging in siz
e from 25 to 100 kb, that are attached at their bases to the structura
l component of the nucleus termed the nuclear matrix. These DNA loop d
omains have been shown to be important in the regulation of both DNA r
eplication and RNA transcription, In this study we have compared the s
tructural organization of the DNA loop domains of the 5S rRNA gene clu
ster in sperm, liver, and brain nuclei in the Syrian golden hamster, T
he individual loop domains were visualized by fluorescent in situ hybr
idization to protamine (sperm)- and histone (somatic)-depleted nuclei,
termed nuclear matrix halo preparations. We found that in sperm nucle
i, the 5S rRNA gene cluster was organized into three small loop domain
s that were approximately 48 kb each. In both types of somatic cell nu
clei examined, the 5S rRNA gene cluster was organized into a single, m
uch larger loop domain that was up to 480 kb in length. The data sugge
st that at least some of the compaction that sperm DNA undergoes durin
g spermiogenesis is mediated by the nuclear matrix independent of prot
amine binding. Additionally, this sperm-specific DNA organization may
be involved in the specific patterns of DNA replication and transcript
ion of the paternal genome in the embryo.