Spirov Alexander V, Holloway David M
Department of Applied Mathematics, The State University of New York at Stony Brook, New York 11794-3600, USA.
In Silico Biol. 2003;3(1-2):89-100. Epub 2002 Dec 16.
We quantify fluctuations in protein expression for three of the segmentation genes in the fruit fly, Drosophila melanogaster. These proteins are representative members of the first three levels of a signalling hierarchy which determines the segmented body plan: maternal (Bicoid protein); gap (Hunchback protein); and pair-rule (Even-skipped protein). We quantify both inter-embryo and inter-nucleus (within a single embryo) variability in expression, especially with respect to positional specification by concentration gradient reading. Errors are quantified both early and late in cleavage cycle 14, during which the protein patterns develop, to study the dynamics of error transmission. We find that Bicoid displays very large positional errors, while expression of the downstream genes, Hunchback and Even-skipped, displays far more precise positioning. This is evidence that the pattern formation of the downstream proteins is at least partially independent of maternal signal, i. e. evidence against simple concentration gradient reading. We also find that fractional errors in concentration increase during cleavage cycle 14.
我们对果蝇黑腹果蝇中三个参与体节形成的基因的蛋白质表达波动进行了量化。这些蛋白质是决定体节身体模式的信号层级前三个水平的代表性成员：母体（Bicoid蛋白）；间隙（驼背蛋白）；以及成对规则（偶数跳蛋白）。我们量化了胚胎间和细胞核间（在单个胚胎内）的表达变异性，特别是关于通过浓度梯度读取进行位置指定的变异性。在第14次卵裂周期的早期和晚期对误差进行了量化，在此期间蛋白质模式形成，以研究误差传递的动态。我们发现Bicoid显示出非常大的位置误差，而下游基因驼背和偶数跳的表达显示出更精确的定位。这证明下游蛋白质的模式形成至少部分独立于母体信号，即反对简单浓度梯度读取的证据。我们还发现，在第14次卵裂周期中，浓度的分数误差会增加。
