A "hot spot" of recombination coincides with an interstitial telomeric sequence in the Armenian hamster

Abstract

The chromosomes of male Armenian hamsters (Cricetulus migratorius) exhibit highly localized terminal and interstitial chiasmata. An interstitial telomeric sequence detected by in situ hybridization was clearly visible at the primary constriction of a large metacentric in both mitotic and meiotic chromosomes. This telomeric sequence was the site of a chiasma in 69% of all 58 diakinesis/metaphase I cells examined. The frequency of meiotic exchange at this site was therefore 34.5%, an extraordinary "hot spot" of recombination. Subsequent chiasma interference can be assumed to reduce recombination and tighten linkage along both arms of male hamster chromosomes. These observations suggest that telomere-promoted recombination may represent a second pathway of recombination, mechanistically different from the more heterodispersed process of meiotic exchange.