Abstract
Structural chromosome abnormalities, such as translocations and inversions occasionally occur in all livestock species and are typically associated with reproductive and developmental disorders. Curiously, only a few structural chromosome aberrations have been reported in camelids, and most involved sex chromosomes. This can be attributed to a high diploid number (2n = 74) and complex chromosome morphology, which makes unambiguous identification of camelid chromosomes difficult. Additionally, molecular tools for camelid cytogenetics are sparse and have become available only recently. Here we present a case report about an infertile male llama with teratozoospermia and abnormal chromosome number 2n = 73,XY. This llama carries an autosomal translocation of chromosomes 12 and 20, which is the likely cause of defective spermatogenesis and infertility in this individual. Our analysis underlines the power of molecular cytogenetics methods over conventional banding-based chromosome analysis for explicit identification of normal and aberrant chromosomes in camelid karyotypes. This is the first case of a translocation and the first autosomal aberration reported in any camelid species. It is proof of principle that, like in other mammalian species, structural chromosome abnormalities contribute to reproductive disorders in camelids.
Highlights
Numerical and structural chromosome abnormalities are well-documented causes of congenital abnormalities and reproductive disorders in all livestock species
Regardless, chromosome abnormalities are of concern in all livestock species and cytogenetic analysis is a routine approach for evaluating breeding animals and for testing animals with reproductive or developmental problems (Villagomez et al, 2009; Ducos et al, 2008; Lear and Bailey, 2008; Raudsepp and Chowdhary, 2016; Szczerbal and Switonski, 2016)
We revisit the prior partially studied case of the infertile male llama with an autosomal translocation (Avila et al, 2014b) and characterize it in detail clinically and cytogenetically using advanced semen imaging and conventional and molecular cytogenetic methods. This is the first autosomal translocation found in any camelid species
Summary
Numerical and structural chromosome abnormalities are well-documented causes of congenital abnormalities and reproductive disorders in all livestock species (reviewed by Villagomez et al, 2009; Raudsepp and Chowdhary, 2016; Szczerbal and Switonski, 2016) Aberrations such as aneuploidies, deletions and duplications result in genetic overdose or haploinsufficiency, and may severely affect viability, development and/or reproduction. We revisit the prior partially studied case of the infertile male llama with an autosomal translocation (Avila et al, 2014b) and characterize it in detail clinically and cytogenetically using advanced semen imaging and conventional and molecular cytogenetic methods. This is the first autosomal translocation found in any camelid species
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