{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T12:30:19Z","timestamp":1786624219130,"version":"build-2736575974"},"reference-count":41,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T00:00:00Z","timestamp":1786579200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100006692","name":"University of Turin","doi-asserted-by":"publisher","award":["BIAD_RILO_23_01"],"award-info":[{"award-number":["BIAD_RILO_23_01"]}],"id":[{"id":"10.13039\/501100006692","id-type":"DOI","asserted-by":"publisher"}]},{"award":["BIAD_RILO_23_01"],"award-info":[{"award-number":["BIAD_RILO_23_01"]}],"id":[{"id":"https:\/\/ror.org\/048tbm396","id-type":"ROR","asserted-by":"publisher"}]},{"DOI":"10.13039\/100008921","name":"Ministry of Agriculture","doi-asserted-by":"publisher","award":["MZE-RO0523"],"award-info":[{"award-number":["MZE-RO0523"]}],"id":[{"id":"10.13039\/100008921","id-type":"DOI","asserted-by":"publisher"}]},{"award":["MZE-RO0523"],"award-info":[{"award-number":["MZE-RO0523"]}],"id":[{"id":"https:\/\/ror.org\/049wftm75","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Genes"],"abstract":"<jats:p>Background\/Objectives: The domestic yak (Bos grunniens) is a livestock species of major relevance in high-altitude environments and an important model for studying adaptation and reproductive isolation within Bovini. Despite its close phylogenetic relationship with cattle (Bos taurus), yak \u00d7 cattle hybrids show a marked sex-biased fertility pattern, with fertile females and generally sterile F1 males, suggesting that subtle chromosomal or genomic differences may underlie post-zygotic reproductive barriers. In this study, we performed a cytogenetic characterization of eight adult yak bulls imported and reared in Central Italy using conventional and molecular cytogenetic approaches. Results: GTG-, RBG-, RBA- and CBA-banding confirmed the yak diploid number as 2n = 60 and the fundamental number as NF = 62, with banding patterns highly comparable to the standardized cattle karyotype. CBA-banding showed an X chromosome lacking evident constitutive heterochromatin and a Y chromosome with distal C-positive blocks. Chromosome instability was low, with 3.75% abnormal metaphases, mainly represented by chromatid and iso-chromatid breaks, while the mean sister chromatid exchange (SCE) rate was 5.19 \u00b1 2.14 per cell. Sequential Ag-NOR\/RBA staining localized nucleolar organizer regions (NORs) at the telomeres of autosomes 2, 3, 4, 11 and 25, as in cattle. Zoo-FISH using bovine chromosome paints for X, Y, 5 and 15 showed complete hybridization to the corresponding yak chromosomes, and BAC-FISH mapped the Y-linked ZFY and SRY genes to positions homologous to those reported in cattle. A comparative bioinformatics analysis of available yak genome assemblies confirmed the overall genome-wide correspondence with cattle, while revealing chromosome orientation issues and small local inconsistencies that may be relevant for comparative mapping and probe design. Conclusions: Overall, at the resolution tested, these findings support broad macrostructural conservation of yak and cattle karyotypes and provide cytogenetic reference data for yak populations reared outside of their traditional range. The persistence of F1 male sterility despite this large-scale chromosomal conservation suggests that fine-scale sex chromosome differences, particularly involving pseudoautosomal regions, recombination boundaries, or heterochromatin organization, may deserve targeted investigation.<\/jats:p>","DOI":"10.3390\/genes17080943","type":"journal-article","created":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T09:31:09Z","timestamp":1786613469000},"page":"943","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Cytogenetic Characterization of the Yak (Bos grunniens) Prometaphase Chromosomes and Comparison with Cattle (Bos taurus)"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3140-9373","authenticated-orcid":false,"given":"Alfredo","family":"Pauciullo","sequence":"first","affiliation":[{"name":"Department of Agricultural, Forest and Food Sciences, University of Torino, Largo Paolo Braccini 2, 10095 Grugliasco, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Davide","family":"Nicodemo","sequence":"additional","affiliation":[{"name":"Directorate for Agriculture and Rural Development, European Commission, Rue de La Loi 130, 1000 Brussels, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3438-5119","authenticated-orcid":false,"given":"Neyrouz","family":"Letaief","sequence":"additional","affiliation":[{"name":"Department of Agricultural, Forest and Food Sciences, University of Torino, Largo Paolo Braccini 2, 10095 Grugliasco, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2426-804X","authenticated-orcid":false,"given":"Halina","family":"\u010cernohorsk\u00e1","sequence":"additional","affiliation":[{"name":"Veterinary Research Institute, Hudcova 296\/70, 62100 Brno, Czech Republic"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Svatava","family":"Kubi\u010dkov\u00e1","sequence":"additional","affiliation":[{"name":"Veterinary Research Institute, Hudcova 296\/70, 62100 Brno, Czech Republic"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9076-8221","authenticated-orcid":false,"given":"Milu\u0161e","family":"Vozdov\u00e1","sequence":"additional","affiliation":[{"name":"Veterinary Research Institute, Hudcova 296\/70, 62100 Brno, Czech Republic"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1544-6673","authenticated-orcid":false,"given":"Pietro","family":"Parma","sequence":"additional","affiliation":[{"name":"Department of Agriculture and Environmental Sciences, University of Milano, Via Celoria 2, 20133 Milano, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5445-883X","authenticated-orcid":false,"given":"Leopoldo","family":"Iannuzzi","sequence":"additional","affiliation":[{"name":"Institute for the Animal Production System in the Mediterranean Environment, National Research Council of Italy, Piazzale Enrico Fermi 1, 80055 Portici, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6006-4987","authenticated-orcid":false,"given":"Gianfranco","family":"Cosenza","sequence":"additional","affiliation":[{"name":"Department of Agriculture, University of Napoli Federico II, Piazza Carlo di Borbone 1, 80055 Portici, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"163","DOI":"10.1093\/oxfordjournals.jhered.a105607","article-title":"Yaks and yak-cattle hybrids in Asia","volume":"37","author":"Phillips","year":"1946","journal-title":"J. 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