Comparative chromosome painting of pronghorn (Antilocapra americana) and saola (Pseudoryx nghetinhensis) karyotypes with human and dromedary camel probes.

Anastasia I Kulemzina,Darya A Grafodatskaya,Trung T Nguyen,Alexander S Graphodatsky,Mary Thompson,Melody E Roelke-Parker,Polina L Perelman

doi:10.1186/1471-2156-15-68

Abstract

BackgroundPronghorn (Antilocapridae, 2n = 58) and saola (Bovidae, 2n = 50) are members of Pecora, a highly diversified group of even-toed hoofed mammals. Karyotypes of these species were not involved in chromosome painting studies despite their intriguing phylogenetic positions in Pecora.ResultsTo trace the chromosome evolution during very fast radiation of main families from the common Pecoran ancestor, high-resolution comparative chromosome maps of pronghorn and saola with human (HSA) and dromedary camel (CDR) painting probes were established. The human and dromedary camel painting probes revealed 50 and 64 conserved segments respectively in the pronghorn genome, while 51 and 63 conserved segments respectively in the saola genome. Integrative analysis with published comparative maps showed that inversions in chromosomes homologous to CDR19/35/19 (HSA 10/20/10), CDR12/34/12 (HSA12/22/12/22), CDR10/33/10 (HSA 11) are present in representatives of all five living Pecoran families. The pronghorn karyotype could have formed from a putative 2n = 58 Pecoran ancestral karyotype by one fission and one fusion and that the saola karyotype differs from the presumed 2n = 60 bovid ancestral karyotype (2n = 60) by five fusions.ConclusionThe establishment of high-resolution comparative maps for pronghorn and saola has shed some new insights into the putative ancestral karyotype, chromosomal evolution and phylogenic relationships in Pecora. No cytogenetic signature rearrangements were found that could unite the Antilocapridae with Giraffidae or with any other Pecoran families. Our data on the saola support a separate position of Pseudorigyna subtribe rather than its affinity to either Bovina or Bubalina, but the saola phylogenetic position within Bovidae remains unresolved.

Highlights

Pronghorn (Antilocapridae, 2n = 58) and saola (Bovidae, 2n = 50) are members of Pecora, a highly diversified group of even-toed hoofed mammals
C-banding karyotype of pronghorn and chromosome painting on pronghorn chromosomes C-banding of pronghorn chromosomes (Figure 1) revealed that all autosomes of the pronghorn karyotype have centromeric constitutive heterochromatin blocks
Our data on the pronghorn karyotype (Figure 2), obtained with human and camel chromosome specific probes, are generally in agreement with the results revealed by localization of cattle Bacterial artificial chromosome (BAC)-clones and microdissected probes [12]

Summary

Introduction

Pronghorn (Antilocapridae, 2n = 58) and saola (Bovidae, 2n = 50) are members of Pecora, a highly diversified group of even-toed hoofed mammals. Karyotypes of these species were not involved in chromosome painting studies despite their intriguing phylogenetic positions in Pecora. The major group of hoofed mammals– Pecora includes five living families: Antilocapridae, Giraffidae, Moschidae, Cervidae, and Bovidae. This study is devoted to molecular cytogenetic investigation of karyotypes of two very interesting pecoran species belonging to Antilocapridae and Bovidae. It was necessary to attempt to find some cytogenetic markers that could clarify the phylogenetic position of Antilocapridae within the Pecoran families. A combination of well described human and dromedary camel painting probes was used in this study, to establish the high resolution comparative chromosome map for pronghorn

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