Unique chromosome rearrangements in karyotypes of yellow-necked mice (Apodemus flavicollis) from various populations.
Cytogenetic monitoring of yellow-necked mouse populations in various parts of the species range revealed deviations from the standard chromosome set in two individuals (Female from the Bryanskaya region and Male from the Samarskaya region). In both of them the wholly acrocentric chromosome set was supplemented by a large unpaired submetacentric chromosome. The C-banding showed no structural homology between these newly formed chromosomes. Obviously, they had been produced by different mechanisms, which may include amplification of paracentromeric heterochromatin in a large chromosome (Female) and classical Robertsonian fusion of two acrocentrics (Male). The low frequency and nonhomologous state of these rearrangements suggest their mutational origin.