Baumgartner S, Noll M
Institute of Molecular Biology II, University of Zurich, Switzerland.
Mech Dev. 1990 Dec;33(1):1-18. doi: 10.1016/0925-4773(90)90130-e.
A model of the trans-regulation of the Drosophila pair-rule segmentation gene, paired (prd), has been derived from the observed alterations in the distribution of prd transcripts during early embryogenesis in single and double pair-rule mutants. Important aspects of the model include the following features and implications: (i) The regulation of prd is subject to a regulatory hierarchy among pair-rule genes. In particular, it shows that prd is at the bottom of this hierarchy, mediating the transition from pair-rule to segment-polarity genes. The transition of the early 'pair-rule' to the 'segment-polarity' pattern of prd expression is regulated by the secondary pair-rule genes opa and odd. The model predicts the distributions of pair-rule gene products regulating prd at late syncytial blastoderm, e.g., that of opa. (ii) The initial activation of prd is independent of pair-rule genes. (iii) The regulation of prd is combinatorial and hence probably cooperative. Combination of one pair-rule gene product with different pair-rule proteins may lead to opposite regulatory effects on prd. Furthermore, we discuss a two-step conversion of the initial analogue specification of position along the anteroposterior axis into a digital code specified by combinations of active segment-polarity and homeotic genes.
果蝇成对规则基因配对（prd）的反式调控模型，源自对单对规则突变体和双对规则突变体早期胚胎发育过程中prd转录本分布变化的观察。该模型的重要方面包括以下特征和含义：（i）prd的调控受制于成对规则基因之间的调控层级。具体而言，它表明prd处于该层级的底部，介导从成对规则基因到体节极性基因的转变。prd表达从早期的“成对规则”模式到“体节极性”模式的转变，由次级成对规则基因opa和odd调控。该模型预测了在晚期合胞体胚盘调控prd的成对规则基因产物的分布，例如opa的分布。（ii）prd的初始激活独立于成对规则基因。（iii）prd的调控是组合式的，因此可能是协同性的。一种成对规则基因产物与不同的成对规则蛋白结合，可能对prd产生相反的调控作用。此外，我们讨论了沿前后轴位置的初始类似物指定向由活性体节极性基因和同源异型基因组合指定的数字代码的两步转换。
