Berger F G, Breen G A, Paigen K
Genetics. 1979 Aug;92(4):1187-203. doi: 10.1093/genetics/92.4.1187.
The identification and mode of action of genetic loci that program gene expression during development are important for understanding differentiation in higher organisms. Previous work from this laboratory has identified two patterns for the postnatal development of liver beta-galactosidase among inbred mouse strains: type I, where activity levels remain constant after about 30 days of age, is found in strains DBA/2J, CBA/J, and BALB/cJ, among others; type II, where activity levels increase between 25 and 50 days of age to reach a new adult level, is found in strain C57BL/6J and related strains. It has been shown that the type I vs. type II developmental difference between strains C57BL/6J and DBA/2J is due to variation at a locus, Bgl-t, that maps with the beta-galactosidase complex, [Bgl], on chromosome 9. In the present study, we have confirmed the existence of Bgl-t as a temporal locus within [Bgl] by analysis of both a congenic strain carrying the beta-galactosidase complex of strain CBA/J in the C57BL/6J genetic background and a cross of strains CBA/J and C57BL/6J. The existence of additional temporal loci for beta-galactosidase that segregate independently of the structural gene and participate in determination of the type I vs. type II difference was revealed by analysis of: (1) a congenic strain containing the beta-galactosidase complex of strain BALB/cJ in the C57BL/10Sn background; (2) recombinant inbred lines derived from progenitor strains C57BL/6ByJ and BALB/cByJ; and (3) a genetic cross between strains C57BL/6ByJ and BALB/cByJ. Thus, for these pairs of strains, the type I vs. type II developmental difference is due to variation at a temporal locus (or loci) unlinked to the enzyme structural gene, and not at Bgl-t. These facts, together with information gathered from an examination of the distribution of beta-galactosidase phenotypes among over 100 inbred strains (Breen, Lusis and Paigen 1977), have led us to conclude that the postnatal developmental pattern for liver beta-galactosidase is determined by a set of interacting temporal genes. One of these, Bgl-t, is located within [Bgl], and one or more are separable from [Bgl] by recombination. A possible mode of interaction among the temporal and instructural loci is suggested.
在发育过程中对基因表达进行编程的基因座的鉴定及其作用方式，对于理解高等生物的分化至关重要。本实验室之前的工作已经确定了近交系小鼠品系中肝脏β-半乳糖苷酶出生后发育的两种模式：I型，在约30日龄后活性水平保持恒定，见于DBA/2J、CBA/J和BALB/cJ等品系；II型，在25至50日龄之间活性水平升高至新的成年水平，见于C57BL/6J品系及相关品系。已经表明，C57BL/6J和DBA/2J品系之间I型与II型发育差异是由于一个基因座Bgl-t的变异，该基因座与9号染色体上的β-半乳糖苷酶复合体[Bgl]连锁。在本研究中，我们通过分析在C57BL/6J遗传背景下携带CBA/J品系β-半乳糖苷酶复合体的近交系以及CBA/J和C57BL/6J品系的杂交，证实了Bgl-t作为[Bgl]内一个时间基因座的存在。通过对以下材料的分析揭示了β-半乳糖苷酶其他时间基因座的存在，这些基因座独立于结构基因分离并参与I型与II型差异的决定：（1）在C57BL/10Sn背景下含有BALB/cJ品系β-半乳糖苷酶复合体的近交系；（2）源自祖系C57BL/6ByJ和BALB/cByJ的重组近交系；以及（3）C57BL/6ByJ和BALB/cByJ品系之间的遗传杂交。因此，对于这些品系对，I型与II型发育差异是由于与酶结构基因不连锁的一个（或多个）时间基因座的变异，而非Bgl-t。这些事实，连同从对100多个近交系中β-半乳糖苷酶表型分布的研究中收集到的信息（Breen、Lusis和Paigen，1977），使我们得出结论，肝脏β-半乳糖苷酶出生后的发育模式由一组相互作用的时间基因决定。其中一个基因Bgl-t位于[Bgl]内，一个或多个可通过重组与[Bgl]分离。文中提出了时间基因座与结构基因座之间一种可能的相互作用模式。
