Trio-binning of a hinny refines the comparative organization of the horse and donkey X chromosomes and reveals novel species-specific features. Academic Article uri icon

abstract

  • We generated single haplotype assemblies from a hinny hybrid which significantly improved the gapless contiguity for horse and donkey autosomal genomes and the X chromosomes. We added over 15Mb of missing sequence to both X chromosomes, 60Mb to donkey autosomes and corrected numerous errors in donkey and some in horse reference genomes. We resolved functionally important X-linked repeats: the DXZ4 macrosatellite and ampliconic Equine Testis Specific Transcript Y7 (ETSTY7). We pinpointed the location of the pseudoautosomal boundaries (PAB) and determined the size of the horse (1.8Mb) and donkey (1.88Mb) pseudoautosomal regions (PARs). We discovered distinct differences in horse and donkey PABs: a testis-expressed gene, XKR3Y, spans horse PAB with exons1-2 located in Y and exon3 in the X-Y PAR, whereas the donkey XKR3Y is Y-specific. DXZ4 had a similar~8kb monomer in both species with 10 copies in horse and 20 in donkey. We assigned hundreds of copies of ETSTY7, a sequence horizontally transferred from Parascaris and massively amplified in equids, to horse and donkey X chromosomes and three autosomes. The findings and products contribute to molecular studies of equid biology and advance research on X-linked conditions, sex chromosome regulation and evolution in equids.

published proceedings

  • Sci Rep

author list (cited authors)

  • Jevit, M. J., Castaneda, C., Paria, N., Das, P. J., Miller, D., Antczak, D. F., ... Raudsepp, T.

complete list of authors

  • Jevit, Matthew J||Castaneda, Caitlin||Paria, Nandina||Das, Pranab J||Miller, Donald||Antczak, Douglas F||Kalbfleisch, Theodore S||Davis, Brian W||Raudsepp, Terje

publication date

  • November 2023