Dissection of a Y-autosome translocation in Cryptomys hottentotus (Rodentia, Bathyergidae) and implications for the evolution of a meiotic sex chromosome chain.
We describe the outcome of a comprehensive cytogenetic survey of the common mole-rat, Cryptomys hottentotus, based on G and C banding, fluorescence in situ hybridisation and the analysis of meiotic chromosomes using immunostaining of proteins involved in the formation of synaptonemal complex (SCP1 and SCP3). We identified the presence of a Y-autosome translocation that is responsible for a fixed diploid number difference between males (2n = 53) and females (2n = 54), a character that likely defines the C. hottentotus lineage. Immunostaining, combined with C banding of spermatocytes, revealed a linearised sex trivalent with X(1) at one end and X(2) at the other, with evidence of reduced recombination between Y and X(2) that seems to be heterochromatin dependant in the C. hottentotus lineage. We suggest that this could depict the likely initial step in the differentiation of a true neo-X, and that this may mimic an early stage in the mammalian meiotic chain formation, an evolutionary process that has been taken to an extreme in a monotreme mammal, the platypus.
Deuve
J L
JL
Evolutionary Genomics Group, Department of Botany and Zoology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa.
Bennett
N C
NC
Ruiz-Herrera
A
A
Waters
P D
PD
Britton-Davidian
J
J
Robinson
T J
TJ
D000818:Animals; D020223:Chromosome Painting; D019143:Evolution, Molecular; D005260:Female; D007621:Karyotyping; D008297:Male; D008540:Meiosis; D008677:Metaphase; D008954:Models, Biological; D008957:Models, Genetic; D051381:Rats; D013045:Species Specificity; D013090:Spermatocytes / Q000378:metabolism; D014178:Translocation, Genetic; D014998:Y Chromosome