Stripe formation in the early fly embryo: principles, models, and networks.

Early development of animal embryos begins from spatially distributed products of gene expression, i.e., gradients. While maternal and early zygotic genes form broad and/or terminal gradients, their direct targets appear later on as relatively narrow stripes, which foreshadow presumptive germ layers or future segments. Evidently, stripe expression of the zygotic genes is among the key mechanisms of embryo patterning. In this paper, known qualitative and quantitative models for the stripe formation are considered on the example of early embryogenesis of Drosophila. The current model analysis emphasizes the role of spatial information flow in development. Discussion is given on frequent network motifs, pointing to spatial stripe formation solutions.