Macdonald P M, Struhl G
Nature. 1986;324(6097):537-45. doi: 10.1038/324537a0.
After fertilization, the protein products of the Drosophila homeobox gene caudal (cad) accumulate in a concentration gradient spanning the anteroposterior axis of the developing embryo. Mutations in the cad gene that reduce or eliminate the gradient cause abnormal zygotic expression of at least one segmentation gene (fushi tarazu) and alter the global body pattern.
受精后，果蝇同源异型框基因尾端（cad）的蛋白质产物会在发育中胚胎的前后轴上形成浓度梯度累积。cad基因中降低或消除该梯度的突变会导致至少一种体节基因（分节基因）的合子异常表达，并改变整体身体模式。
