LOCALIZATION OF TELOMERES IN PLANT INTERPHASE NUCLEI BY INSITU HYBRIDIZATION AND 3D CONFOCAL MICROSCOPY

We investigated the three-dimensional (3D) arrangement of telomeres in structurally well preserved, interphase nuclei of Pisum sativum and Vicia faba root tips using in situ hybridization of a probe to telomeric sequences. The probe was labelled with either digoxygenin or biotin and hybridized sequences were detected by immunofluorescence. Three-dimensional data sets were collected by confocal optical microscopy or using a cooled CCD camera. Twelve stacks of optical sections of P. sativum nuclei and nine of V. faba nuclei were studied in detail. Projections through the stacks of optical sections revealed that, in both species, most of the telomeres were adjacent to the nuclear envelope except for a small number next to the nucleolar periphery. In V. faba nuclei, the telomeres were clearly clustered at one pole while in P. sativum there was only a slight tendency for clustering. In V. faba, clusters were found at opposite poles in pairs of sister nuclei rather than at adjacent poles as would be expected if the arrangement at telophase were maintained into interphase.