Genetic interactions and their environmental dependence.

The genetic interactions are indicated for three inverse LacI variants. Each row details the interactions between two mutations, each indicated by an X, either in a LacIwt background (denoted by a ○), or a single mutant background (denoted by a •). We consider three types of interactions: M, magnitude epistasis; S, sign epistasis; R, reciprocal sign epistasis. The mutation that changes sign is indicated between brackets. The data shows that most genetic interactions display different types of epistasis in each of the two environments. The significance of the phenotypic effect of mutations in LacI is tested with a t-test in conjunction with a Bonferroni correction for multiple comparisons (P本数据集呈现了三种反向乳糖抑制子（LacI）变体的遗传互作关系。每一行详细记录了两个突变之间的互作模式，每个突变以X标记；这些突变要么处于野生型乳糖抑制子（LacIwt）背景（以○标注），要么处于单突变体背景（以•标注）。本次研究定义了三类遗传互作类型：M代表量级上位性（magnitude epistasis），S代表符号上位性（sign epistasis），R代表反向符号上位性（reciprocal sign epistasis）。发生符号改变的突变会以括号标注。数据表明，多数遗传互作在两种环境下呈现出不同类型的上位性效应。乳糖抑制子（LacI）突变的表型效应显著性通过t检验结合邦费罗尼校正（Bonferroni correction）进行多重比较校正后的显著性检验（P