Cytogenetic comparison between Vietnamese sika deer and cattle: R-banded karyotypes and FISH mapping.

R-banded chromosomes of Vietnamese sika (VS) deer (Cervus nippon pseudaxis, 2N = 66), a threatened subspecies of sika deer endemic to Vietnam, are presented for the first time and were compared with bovine R-banded chromosomes to define a standard karyotype. Nineteen VS deer autosomes (CNP) were identified on the basis of the banding pattern relative to bovine chromosomes (BTA), while hypotheses for the remaining thirteen were proposed from comparisons with the published deer genetic map, BTA 1, 2, 5, 6, 8 and 9 each equivalent to two separate acrocentric CNP chromosomes and BTA 26 and 28 associated in a tandem fusion. To confirm these hypotheses, probes for the twenty-nine Texas nomenclature type I markers specific for each cattle autosome, sixteen other type I and fourteen microsatellite markers were used in FISH experiments on VS deer chromosomes. CNP7 presented the most complex rearrangement as compared with cattle chromosomes. A complete correspondence between VS deer and cattle chromosomes was established and it was extended with a comparison with the human karyotype to transfer human map information to this species of scientific and economic interest. Moreover, this work anchors the deer genetic linkage map to chromosome-specific markers.