Centromere Repositioning in Cattle (Bos taurus) Chromosome 17.

Eukaryotic organisms have developed a structure, called centromere, able to preserve the integrity of the genome during cell division. A young bull from the Marchigiana breed, with a normal external phenotype, underwent routine cytogenetic analysis to enter the reproduction center. All metaphases analyzed showed an unusual biarmed chromosome of medium size despite a diploid set of chromosomes (2n = 60,XY). FISH analysis excluded a pericentric inversion or a reciprocal translocation, but highlighted a repositioning of the centromere in BTA17. The satellite DNA was still in an acrocentric position. The telomeres were normally present. The primary constriction on the abnormal chromosome was C-band negative. Finally, the absence of a large genomic deletion in the BTA17 pericentromeric region was demonstrated by both array-CGH analysis and SNP array. To our knowledge, this is the first case of centromere repositioning reported in cattle.