Differences in the distribution and nature of the interstitial telomeric (TTAGGG)n sequences in the chromosomes of the Giraffidae, okapi (Okapia johnstoni), and giraffe (Giraffa camelopardalis): evidence for ancestral telomeres at the okapi polymorphic rob(4;26) fusion site

Intrachromosomal telomeric sequences (TTAGGG)n were analyzed in the two members of the family Giraffidae, the giraffe and the okapi. The giraffe has a diploid chromosome number of 2n = 30, whereas the okapi chromosome number varies from 2n = 46 to 2n = 45 and 2n = 44 due to a “recent” Robertsonian fusion event. The interstitial telomeres that we detected in these species are of two types: (1) In the okapi, a long interstitial telomeric element is present at the fusion site of the rob(4;26). The nature of this interstitial telomeric element suggests that it is a remnant of the telomeres of the ancestral chromosomes that participated in the fusion event. (2) In the giraffe, short stretches or degenerate telomeric sequences which are part of the satellite DNA are present at intrachromosomal sites. The results of this study provide insights into the origin of interstitial telomeric sequences in the Giraffidae.