title: A cytogenetic and comparative map of camelid chromosome 36 and the minute in alpacas.
abstract: Recent advances in camelid genomics have provided draft sequence assemblies and the first comparative and gene maps for the dromedary (CDR) and the alpaca (LPA). However, no map information is currently available for the smallest camelid autosome-chr36. The chromosome is also of clinical interest because of its involvement in the minute chromosome syndrome (MCS) in infertile alpacas. Here, we developed molecular markers for camelid chr36 by direct sequencing CDR36 and LPA minute and by bioinformatics analysis of alpaca unplaced sequence scaffolds. We constructed a cytogenetic map for chr36 in the alpaca, llama, and dromedary and showed its homology to human chromosome 7 (HSA7) at 49.8-55.5 Mb. The chr36 map comprised seven markers, including two genes-ZPBP and WVC2. Comparative status of HSA7 was further refined by cytogenetic mapping of 16 HSA7 orthologs in camelid chromosomes 7 and 18 and by the analysis of HSA7-conserved synteny blocks across 11 vertebrate species. Finally, mapping chr36 markers in infertile alpacas confirmed that the minute chromosome was a derivative of chr36, but the small size was not a result of a large deletion or a translocation. Instead, cytogenetic mapping of 5.8S, 18S, and 28S rRNA genes (nucleolus organizer region (NOR)) revealed that the size difference between chr36 homologs in infertile alpacas was due to a heterozygous presence of NOR, whereas chr36 in fertile alpacas had no NOR. We theorized that the heterozygous NOR might affect chr36 pairing, recombination, and segregation in meiosis and, thus fertility.
authors: Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, 77843-4458, USA.
authors: Felipe
authors: F
authors: Avila
authors: Malorie P
authors: MP
authors: Baily
authors: David A
authors: DA
authors: Merriwether
authors: Vladimir A
authors: VA
authors: Trifonov
authors: Jiři
authors: J
authors: Rubes
authors: Michelle A
authors: MA
authors: Kutzler
authors: Renuka
authors: R
authors: Chowdhary
authors: Jan
authors: J
authors: Janečka
authors: Terje
authors: T
authors: Raudsepp
mesh_terms: D000818:Animals; D002161:Camelids, New World / Q000235:genetics*; D002874:Chromosome Mapping; D033481:Chromosomes, Mammalian; D003582:Cytogenetics; D005260:Female; D005819:Genetic Markers; D015698:Genomic Library; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping
chemical_list: D005819:Genetic Markers
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