Separate breeding colonies of C57BL/6 ("B6") mice maintained at the Jackson Laboratories ("J") and NIH ("N") have led to the emergence of two distinct substrains of C57BL/6 mice: C57BL/6J and C57BL/6N. Molecular genetic studies indicate simple sequence-length polymorphisms, single-nucleotide polymorphisms, and copy-number variants among B6 substrains that may contribute to phenotypic differences. We examined differences in motor coordination, pain sensitivity, and conditional fear in the C57BL/6J strain and three N strains: C57BL/6NCrl (Charles River), C57BL/6NTac (Taconic), and C57BL/6NHsd (Harlan Sprague Dawley). Male C57BL/6J mice demonstrated enhanced motor coordination, as measured by the rotarod assay, markedly enhanced pain sensitivity in two assays of acute thermal nociception (e.g., tail withdrawal and hot plate), and a reduced level of conditional fear. The tail withdrawal result was confirmed in a separate laboratory. We also provide a table reviewing previously reported behavioral differences among various B6 substrains and discuss the significance of environmental differences due to obtaining mice form different vendors. These data may be seen as a potential problem and as a potential opportunity. Great care must be taken when working with mice engineered by using B6 embryonic stem cell lines because control groups, backcrosses, and intercrosses could inadvertently introduce behaviorally significant polymorphic alleles or environmental confounds. On the other hand, deliberate crosses between B6 substrains may provide an opportunity to map polymorphic loci that contribute to variability in a trait on largely homogenous backgrounds, which has the potential to improve mapping resolution and aid in the selection of candidate genes.

中文翻译：

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C57BL/6 亚株之间的行为差​​异：对转基因和基因敲除研究的影响。

在杰克逊实验室 (“J”) 和 NIH (“N”) 饲养的 C57BL/6 (“B6”) 小鼠的单独繁殖群导致出现两种不同的 C57BL/6 小鼠亚系：C57BL/6J 和 C57BL /6N。分子遗传学研究表明，可能导致表型差异的 B6 亚株之间存在简单的序列长度多态性、单核苷酸多态性和拷贝数变异。我们检查了 C57BL/6J 菌株和三种 N 菌株在运动协调性、疼痛敏感性和条件恐惧方面的差异：C57BL/6NCrl（查尔斯河）、C57BL/6NTac（Taconic）和 C57BL/6NHsd（Harlan Sprague Dawley）。通过旋转棒试验测量，雄性 C57BL/6J 小鼠表现出增强的运动协调性，在两种急性热伤害感受试验中显着增强了疼痛敏感性（例如，尾部退出和热板），以及降低的条件恐惧水平。拔尾结果在单独的实验室中得到证实。我们还提供了一个表格，回顾了先前报告的各种 B6 亚系之间的行为差​​异，并讨论了由于从不同供应商处获得小鼠而导致的环境差异的重要性。这些数据可能被视为潜在问题和潜在机会。在处理使用 B6 胚胎干细胞系改造的小鼠时必须非常小心，因为对照组、回交和互交可能会无意中引入具有行为意义的多态性等位基因或环境混淆。另一方面，