Logue D N, Harvey M J
Res Vet Sci. 1978 Jul;25(1):7-12.
A chromosomal abnormality identified as a 14/20 Robertsonian translocation by measurement and banding studies has been found randomly in several Swiss Simmental cattle. These cases have all been traced back to one ancestral bull. The testicular function of three unselected male offspring, two heterozygotes and one normal was studied. All possessed apparently normal spermatogenesis. In a meiotic study no alteration of overall chiasma counts were found at diakinesis in the heterozygous bulls compared with the normal, while the presence of a trivalent confirmed the diagnosis of a Robertsonian translocation. Also in the heterozygotes a small number of secondary spermatocytes were identified but they were too few to draw any firm conclusions regarding alterations in non disjunction rate.
通过测量和染色体显带研究，在几头瑞士西门塔尔牛中随机发现了一种染色体异常，被鉴定为14/20罗伯逊易位。所有这些病例都可追溯到一头祖先公牛。对三头未经选择的雄性后代（两头杂合子和一头正常个体）的睾丸功能进行了研究。所有个体的精子发生过程显然正常。在减数分裂研究中，与正常公牛相比，杂合子公牛在终变期的交叉总数没有改变，而三价体的存在证实了罗伯逊易位的诊断。在杂合子中也发现了少量次级精母细胞，但数量太少，无法就不分离率的改变得出任何确凿结论。
