Mayr B, Gruber K, Brem G, Mayrhofer G
Genet Res. 1989 Apr;53(2):111-8. doi: 10.1017/s0016672300027993.
Experimentally produced monozygotic twins, natural opposite sex blood chimeras (freemartins), and several pedigrees were used to evaluate the genetic influences on the nucleolus organizer region (NOR) patterns in cattle. In monozygotic twins, the NOR patterns of both twins are extremely similar. In chimeras, NOR patterns of genetically identical, peripheral blood lymphocytes (PBL) from the two partners resemble each other. In contrast, genetically different PBL (sib organ) differ significantly in the same environment. A high heritability of the individual NOR patterns is also demonstrated in our 23 pedigrees. In conclusion, our data demonstrate that variation in NOR expression is predominantly due to genetic factors.
通过实验产生的单卵双胞胎、自然形成的异性血液嵌合体（双胎雌犊）以及几个家系被用于评估基因对牛核仁组织区（NOR）模式的影响。在单卵双胞胎中，两个双胞胎的NOR模式极其相似。在嵌合体中，来自两个个体的基因相同的外周血淋巴细胞（PBL）的NOR模式彼此相似。相比之下，基因不同的PBL（同胞器官）在相同环境中差异显著。在我们的23个家系中也证明了个体NOR模式具有高遗传性。总之，我们的数据表明NOR表达的变异主要是由基因因素引起的。
