Localization of cloned, repetitive DNA sequences in deer species and its implications for maintenance of gene territory

The deer family shows the largest variation in chromosome number known in mammals (2n = 6 to 2n = 70). The drastic rearrangement of the chromosomes allows to test the prediction, based un the chromosome field theory. according to which DNA sequences tend to occupy specific territories within the eukaryotic chromosome. Nuclear DNAs were isolated from eight Deer and two Bovidae species. These DNAs were cleaved with the restriction enzymes Eco RI and Alu I. Following Eco RI digestion highly repetitive sequences formed two bands which were common to all deer species. These bands had about 1520 and 2240 base pairs and were particularly clear in Capreolus cupreolus (2n = 70, roc deer). The 1520 band DNA was cloned in plasmid pUC9. nick translated. and hybridized with the DNAs of all ten species. The Cupreohis DNA showed a high homology with the DNAs of all the species including the Indian muntjac ( Muntiacus muntjak . 2n = 7, male) and the Chinese muntjac ( Muntiacus rewesi . 2n = 46). 3 H hybridization was carried out in situ with metaphasc chromosomes of Cervus elaphus (2n = 68, red deer). M. muntjak . and M. reevesi . In C. elaphus all the chromosomes are heavily labeled except the regions of the arms near the centrumere. In the muntjacs all chromosomes and most regions appear to he labeled. These results were checked with a different technique that involved the use of two antibodies and biotin labeling of the DNA. The hybridiiation picture was essentially the same as obtained with 'H. These results disclose that the 1520 bp DNA piece maintains its main territory independently of the drastic changes in chromosome number.