Localization of centromeric satellite and telomeric DNA sequences in dorsal root ganglion neurons, in vitro.

Chromatin domains of interphase nuclei are organized in a tissue-specific, non-random manner. In the present work, the spatial arrangement of satellite (sDNA) and telomeric (tDNA) DNA was examined in nuclei of murine Dorsal Root Ganglion (DRG) cells, maintained in vitro. In situ hybridization in conjunction with three-dimensional reconstruction was employed. A mean number of 8.02 +/- 0.40 sDNA signals/nucleus was detected, of which 41.65 +/- 0.59% were associated with the nucleolus. The remaining fraction of signals was localized between the nucleolus and the nuclear membrane. sDNA signals were reproducibly localized at a mean distance of 3.15 +/- 0.06 microns from the nuclear center and measured 1-2 microns in diameter. Given a centromere complement of 40 per murine nucleus, the relatively low number of signals detected and their large signal volumes were interpreted to reflect clustering of centromeres, a phenomenon common in mammalian cells. An average of 37.00 +/- 1.52 tDNA signals was detected per nucleus. Of these, and in contrast to sDNA signals, only 18.45 +/- 0.41% of these signals were associated with the nucleolus while the remainder was distributed between the nucleolus and the nuclear membrane. Both centromeric and telomeric signals often occurred in pairs and were distributed throughout the nucleoplasm. No evidence for a classical Rabl configuration was found.