Telomeric sequences localization and G-banding patterns in the identification of a polymorphic chromosomal rearrangement in the rodent Akodon cursor (2n=14, 15 and 16)

Akodon cursor is an exceptional example of high chromosomal variability, displaying diploid numbers from 14 to 16 and fundamental numbers (FN) from 18 to 26 as the result of a complex rearrangement in par 1 and pericentric inversions in three autosomal pairs. The difference in the diploid number is due to the presence of a large metacentric pair 1 in the 2n=14 karyotype, a large metacentric 1 and two different submetacentrics (la and Ib) in 2n=15 and la and Ib submetacentric pairs in homozygosis in the 2n=16 karyotype. Chromosomes la and Ib share homology with the short and long arms of the large metacentric 1 respectively. In this paper, evidence based on fluorescence in situ hybridization (FISH) with telomeric sequences and G-banding indicates that pericentric inversions and fusion of chromosomes la and Ib are the probable rearrangements giving rise to the large metacentric 1.