title: A paradox revealed: karyotype evolution in the four-horned antelope occurs by tandem fusion (Mammalia, Bovidae, Tetracerus quadricornis).
abstract: The four-horned antelope, Tetracerus quadricornis, is a karyotypic novelty in Bovidae since chromosomal evolution in this species is driven by tandem fusions in contradiction to the overwhelming influence of Robertsonian fusions in other species within the family. Using a combination of differential staining and molecular cytogenetic techniques, we provide the first description of the species' karyotype, draw phylogenetic inferences from the cytogenetic data and discuss possible mechanisms underlying the formation of the tandem fusions in this species. We show (a) that pairs 1-6 of Tetracerus correspond to a combination of Bos taurus orthologous chromosomes that are tandemly fused head to tail, (b) the presence of interstitial centromeric satellite DNA at the junctions of orthologous blocks defined by the cross-species painting data and (c) that in some instances, residual telomeric sequences persist at these sites. We conclude that the attendant result of each fusion is an enlarged acrocentric fusion element comprising a single functional centromere and two terminal telomeres that, collectively, led to a reduction of the 2n = 58 bovid ancestral acrocentric chromosomal complement to the 2n = 38 detected in the four-horned antelope.
authors.affiliation: Department of Botany and Zoology, University of Stellenbosch, Matieland, South Africa. ropiquet@sun.ac.za
authors.forename: Anne
authors.initials: A
authors.lastname: Ropiquet
authors.forename: Alexandre
authors.initials: A
authors.lastname: Hassanin
authors.forename: Eva
authors.initials: E
authors.lastname: Pagacova
authors.forename: Michèle
authors.initials: M
authors.lastname: Gerbault-Seureau
authors.forename: Halina
authors.initials: H
authors.lastname: Cernohorska
authors.forename: Svatka
authors.initials: S
authors.lastname: Kubickova
authors.forename: Céline
authors.initials: C
authors.lastname: Bonillo
authors.forename: Jiri
authors.initials: J
authors.lastname: Rubes
authors.forename: Terence J
authors.initials: TJ
authors.lastname: Robinson
mesh_terms: D000818:Animals; D000866:Antelopes / Q000235:genetics*; D005075:Biological Evolution; D002503:Centromere; D033481:Chromosomes, Mammalian; D007621:Karyotyping; D010802:Phylogeny; D026801:Synteny; D016615:Telomere