Rabinow L, Nguyen-Huynh A T, Birchler J A
Biological Laboratories, Harvard University, Cambridge, Massachusetts 02138.
Genetics. 1991 Oct;129(2):463-80. doi: 10.1093/genetics/129.2.463.
A trans-acting regulatory gene, Inr-a, that alters the level of expression of the white eye color locus as an inverse function of the number of its functional copies is described. Several independent lines of evidence demonstrate that this regulatory gene interacts with white via the promoter sequences. Among these are the observations that the inverse regulatory effect is conferred to the Adh gene when fused to the white promoter and that cis-regulatory mutants of white fail to respond. The phenotypic response to Inr-a is found in all tissues in which white is expressed, and mutants of the regulator exhibit a recessive lethality during larval periods. Increased white messenger RNA levels in pupal stages are found in Inr-a/+ individuals versus +/+ and a coordinate response is observed for mRNA levels from the brown and scarlet loci. All are structurally related and participate in pigment deposition. These experiments demonstrate that a single regulatory gene can exert an inverse effect on a target structural locus, a situation postulated from segmental aneuploid studies of gene expression and dosage compensation.
描述了一种反式作用调节基因Inr-a，其改变白眼颜色基因座的表达水平，该水平与其功能拷贝数呈反比。几条独立的证据表明，这种调节基因通过启动子序列与白眼基因相互作用。其中包括以下观察结果：当与白眼启动子融合时，反式调节作用赋予了乙醇脱氢酶（Adh）基因，并且白眼的顺式调节突变体没有反应。在所有表达白眼的组织中都发现了对Inr-a的表型反应，并且调节基因的突变体在幼虫期表现出隐性致死性。与野生型（+/+）相比，Inr-a/+个体在蛹期的白眼信使核糖核酸（mRNA）水平增加，并且观察到来自棕色和猩红色基因座的mRNA水平有协同反应。所有这些基因在结构上相关并参与色素沉积。这些实验表明，单个调节基因可以对靶结构基因座产生反向作用，这种情况是从基因表达和剂量补偿的染色体片段非整倍体研究中推测出来的。
