Conserved signaling network involved in vertebrate body plan development

<p>While vertebrates have acquired diverse features throughout their evolution, they all share a common developmental phase which defines their basic structure of the body (body plan). Although the mechanisms behind this conservation have been largely unknown, recent researches, including us, have raised the possibility that intrinsic characteristics of organogenesis during development, namely stability, robustness against mutational and environmental perturbation, and the enrichment of pleiotropically expressed genes may be a contributing factors. In other words, these studies suggest that the body plan developing phse may have less potential to generate phenotypic variation, which may have led to their conservation, together with the body plan. On the other hand, there are findings and hypotheses that appear to be inconsistent with these findings. For example, it is hypothesized that the dense and interdependent signaling network among organ primordials in the body plan developing phase may make the embryo more prone to embryonic lethality. In fact, teratogens can cause lethal or severe malformations, and the organogenesis phase is often the main target of teratogens. In this presentation, I would like to discuss how recent findings can be interpreted consistently with previous findings in terms of robustness or vulnerability of developmental processes.</p>