Primed in situ labeling (PRINS) can be used to localize single-copy genes and unique sequences. Using a modified PRINS method that incorporates multiple primers for the same sequence, single-step annealing and extension, anti- Taq DNA polymerase antibody, and stringent washing, we localized the human SRYgene to Yp11.31-p11.32 in chromosome preparations in situ. Locus-specific oligonucleotide probes (i.e., PRINS primers) were annealed to chromosomal DNA fixed on glass slides and extended in the presence of the four trinucleotide precursors, biotin-16-2'-deoxyuridine 5'-triphosphate, Tris-HCl, KCl, MgCl 2, bovine serum albumin, and Taq DNA polymerase. After reaction with avidin-conjugated fluorophores, the resulting signals could be visualized by fluorescence microscopy in metaphase spreads and in interphase nuclei. This method could prove useful for unique sequences in general.
Key Words: PRINS; chromosome; gene localization; single-copy genes; unique sequences; SRY gene; FISH.
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