Phase specific Ag-staining of nucleolar organizer regions (NORs) and kinetochores in the Australian ant Myrmecia croslandi

Abstract

Detailed localization of NORs on metaphase chromosomes of the Australian ant Myrmecia croslandi were examined using rDNA: DNA in situ hybridization. In individuals with 2K=1M₍₁₊₂₎+1SM ₁+1M₂ (2n=3) NORs are located at the proximal region of the short arm heterochromatin block in 1M₍₁₊₂₎, and at the chromosomal gap in the heterochromatic short arm of M₂. These findings were supported by cytological evidence that nucleoli appeared exactly at the expected NOR sites. There was no silver staining at any of the metaphase NORs in this ant, but rather the kinetochores stained faintly.