Non-isotopical labeling of murine heterochromatin in situ by hybridization with in vitro-synthesized biotinylated gamma (major) satellite DNA

Degenerate probe DNA, homologous to part of the 234-bp repeated mouse gamma (major) satellite DNA, was generated by primer-directed in vitro DNA amplification using the polymerase chain reaction with oligonucleotide primers that anneal in the most conserved parts of the repeat. Probe labeling with biotin was performed during DNA polymerization. In situ hybridization of probe DNA with metaphase chromosome preparations showed exclusive binding of probe molecules to the centromeric region of mouse chromosomes. We applied the probe DNA for labeling of mouse heterochromatin in metaphase chromosomes, as well as interphase cell nuclei, and compared results of probe visualization using avidin tagged with either fluorescein or alkaline phosphatase in combination with a chromogenic substrate.