• 98 Efficacy of commercial equine semen freezing extenders for cryopreservation of southern white rhinoceros (Ceratotherium simum simum) sperm

      Young, Carly; Ravida, Nicole; Pennington, Parker M.; Durrant, Barbara S. (2019)
      Once nearly extinct in the wild, the southern white rhinoceros is currently listed as near threatened by IUCN. This status is likely to change as poaching continues to escalate....
    • Characterization of Prdm9 in equids and sterility in mules

      Steiner, Cynthia C.; Ryder, Oliver A. (2013)
      Prdm9 (Meisetz) is the first speciation gene discovered in vertebrates conferring reproductive isolation. This locus encodes a meiosis-specific histone H3 methyltransferase that specifies meiotic recombination hotspots during gametogenesis. Allelic differences in Prdm9, characterized for a variable number of zinc finger (ZF) domains, have been associated with hybrid sterility in male house mice via spermatogenic failure at the pachytene stage. The mule, a classic example of hybrid sterility in mammals also exhibits a similar spermatogenesis breakdown, making Prdm9 an interesting candidate to evaluate in equine hybrids. In this study, we characterized the Prdm9 gene in all species of equids by analyzing sequence variation of the ZF domains and estimating positive selection. We also evaluated the role of Prdm9 in hybrid sterility by assessing allelic differences of ZF domains in equine hybrids. We found remarkable variation in the sequence and number of ZF domains among equid species, ranging from five domains in the Tibetan kiang and Asiatic wild ass, to 14 in the Grevy’s zebra. Positive selection was detected in all species at amino acid sites known to be associated with DNA-binding specificity of ZF domains in mice and humans. Equine hybrids, in particular a quartet pedigree composed of a fertile mule showed a mosaic of sequences and number of ZF domains suggesting that Prdm9 variation does not seem by itself to contribute to equine hybrid sterility.
    • Recalibrating Equus evolution using the genome sequence of an early Middle Pleistocene horse

      Orlando, Ludovic; Ginolhac, Aurélien; Zhang, Guojie; Froese, Duane; Albrechtsen, Anders; Stiller, Mathias; Schubert, Mikkel; Cappellini, Enrico; Petersen, Bent; Moltke, Ida; et al. (2013)
      …We estimate that the Przewalski’s and domestic horse populations diverged 38–72 kyr bp, and find no evidence of recent admixture between the domestic horse breeds and the Przewalski’s horse investigated. This supports the contention that Przewalski’s horses represent the last surviving wild horse population….