Paigen K, Meisler M, Felton J, Chapman V
Cell. 1976 Dec;9(4 Pt 1):533-9. doi: 10.1016/0092-8674(76)90035-0.
The developmental program for beta-galactosidase in C57BL/6J and related strains of mice differs from that seen in most other mouse strains. Mice of the C57BL/6 group show a rise in liver enzyme activity during development that is not seen in mice of other strains. The developmental pattern of beta-galactosidase activity in heart and brain of C57BL/6 mice is similar to that in other strains. Physical, kinetic, and immunological tests indicate that the developmental increase in C57BL/6 enzyme activity is an increase in the number of molecules of the same species of enzyme protein that is present in other strains. In genetic crosses, the presence of the developmental rise in liver enzyme activity segregates as if determined by a single genetic factor showing additive expression in heterozygotes. This factor is closely linked to the beta-galactosidase structural gene on chromosome 9. The existence of a genetic variant with these properties is evidence that programmatic information capable of regulating the temporal expression of a structural gene can be encoded in DNA.
C57BL/6J及相关品系小鼠中β-半乳糖苷酶的发育程序与大多数其他小鼠品系不同。C57BL/6组小鼠在发育过程中肝脏酶活性升高，而其他品系小鼠未见此现象。C57BL/6小鼠心脏和大脑中β-半乳糖苷酶活性的发育模式与其他品系相似。物理、动力学和免疫学测试表明，C57BL/6酶活性的发育性增加是同一酶蛋白分子数量的增加，该酶蛋白也存在于其他品系中。在遗传杂交中，肝脏酶活性发育性升高的存在表现出分离现象，就好像是由一个单一遗传因子决定的，该因子在杂合子中表现出加性表达。这个因子与9号染色体上的β-半乳糖苷酶结构基因紧密连锁。具有这些特性的遗传变异的存在证明，能够调节结构基因时间表达的程序性信息可以编码在DNA中。
