Relationship of telomere sequence and constitutive heterochromatin in the human and apes as detected by PRINS.

Hitherto, hominoid telomere sequences have been localized only at essential telomere regions of chromosome ends using ordinary FISH. In the present study, however, a PRINS technique revealed the new insight that chromosomes of humans and apes have many internal locations of the sequence. Moreover, a combination of PRINS and post-PRINS C-banding elucidated that the internal telomeric repeats corresponded with regions of constitutive heterochromatin. The PRINS reaction appeared more sensitive than the standard FISH technique, as it provided greater resolution of FITC signals. Furthermore, G- and R-like bands yielded by post- PRINS counter-staining with DAPI and PI, respectively, were informative in identification of chromosomes as well as the detailed characterization of those chromosomal structures signaling positive for the PRINS reaction. The combined efforts of FITC signals, DAPI-, PI-, and C-bands are most precisely analyzed through the use of a microscope mounted with a cooled CCD camera and an auto-wheel fluorescence filter set regulated by a computer.