Comparative FISH-mapping of the survival of motor neuron gene (SMN) in domestic bovids

A comparative fluorescence in situ mapping of SMN gene was performed on R-banded chromosome preparations of cattle (Bos taurus, BTA, 2n=60), river buffalo (Bubalus bubalis, BBU, 2n=50), sheep (Ovis aries, OAR, 2n=54) and goat (Capra hircus, CHI, 2n=60), as well as on those of a calf from Piedmont breed affected by arthrogryposis. SMN was located on BTA20q13.1, OAR16q13.1, CHI20q13.1 and BBU19q13. These chromosomes and chromosome bands are believed to be homoeologous, confirming the high degree of chromosome homoeologies among bovids. The position of SMN was refined in cattle, comparing to the two previous localizations, while it is a new gene assignment in the other three bovids. A comparative fiber-FISH performed on extended chromatin of both normal cattle and calf affected by arthrogryposis revealed more extended FITC-signals in the calf, compared to the normal cattle (control), suggesting a possible duplication of SMN-gene in the calf affected by arthrogryposis.