Nagorcka B N
CSIRO, Division of Entomology, Canberra ACT, Australia.
J Theor Biol. 1988 Jun 7;132(3):277-306. doi: 10.1016/s0022-5193(88)80216-9.
It is known that cells are already committed to a particular segment at the cellular blastoderm stage during embryogenesis of Drosophila melanogaster. Recently, several segmentation genes have been observed to be expressed in a sequence of banded spatial patterns in the syncytial blastoderm, prior to the formation of the cellular blastoderm. It is demonstrated in this paper that a two component reaction-diffusion (RD) system with net production functions which are antisymmetric with respect to the uniform steady-state values, is capable of producing a sequence of seven spatial patterns in the syncytial blastoderm. The sequence of patterns obtained exhibit a strong preference for banded or striped patterns. The first pattern is a simple anteroposterior gradient while the second is a gradient in the dorsoventral direction. The next five patterns are a sequence of banded patterns which exhibit frequency doubling, i.e. the number of bands in each pattern tend to be double the number in the previous pattern. The predicted pattern sequence is comparable to that observed in the expression of some segmentation genes. It is suggested that a pattern formation mechanism based on such an RD system may exist in the embryo where it produces a sequence of prepatterns to regulate the expression of various segmentation genes leading ultimately to a segmented embryo. There is sufficient spatial information in the sequence of banded prepatterns for the segments to be unique.
已知在黑腹果蝇胚胎发生过程中，细胞在细胞胚盘阶段就已经确定发育为特定的体节。最近，人们观察到几个体节基因在合胞体胚盘形成细胞胚盘之前，以一系列带状空间模式的形式表达。本文证明，一个具有相对于均匀稳态值呈反对称净产生函数的双组分反应扩散（RD）系统，能够在合胞体胚盘中产生一系列七种空间模式。所得到的模式序列强烈倾向于带状或条纹状模式。第一种模式是简单的前后梯度，而第二种模式是背腹方向的梯度。接下来的五种模式是一系列带状模式，呈现频率加倍的现象，即每种模式中的带数往往是前一种模式中带数的两倍。预测的模式序列与在一些体节基因表达中观察到的序列相当。有人提出，基于这种RD系统的模式形成机制可能存在于胚胎中，它产生一系列预模式来调节各种体节基因的表达，最终导致胚胎分节。带状预模式序列中存在足够的空间信息，使得体节是唯一的。
