Ben-Gurio​n University of the Negev, May 9-10, 2022​

​Dedicated to Eric Davidson, 1937- 2015

Organizers: Ute Deichmann, Michel Morange, and Ellen Rothenberg

Ben-Gurion University of the Negev, May 09 – 10, 2022

 

Constancy and predictability are, with few exceptions, fundamental characteristics of embryonic development, as Eric Davidson has pointed out many times: Within each species the outcome of development is extremely reproducible; largely independent of the environment, animals beget similar offspring. In the words of Benny Shilo, "through a continuum of cell divisions and migrations, in a constantly changing environment, the final shape of the embryo is generated each time an organism is formed with amazing precision and reproducibility." In his lifework, Davidson explored the importance of developmental gene regulatory networks (GRNs) to generating such robust developmental outcomes. GRNs consist of regulatory genes and signaling pathways that execute a cascade of molecular mechanisms to transform an egg cell into a complex organism, plus the sequences that control the expression of each of these genes. Davidson’s model of development through GRNs also has implications for evolution: The most central genetic circuits controlling development, the “kernels” of the hierarchical GRNs, are so constrained that their variations are rare, a hypothesis that explains the remarkable degree of constancy in evolution, i.e. the phenotypic stability of animal body plans that has persisted at least since the early Cambrian period 520 million years ago. According to this model, such changes in the "kernels" that lead to viable organisms, can result in dramatic changes in developmental processes that could under certain conditions lead to the generation of new body plans in evolution.

The fruitfulness of Davidson's model of developmental GRNs has been widely acknowledged by many biological scientists. However, there are phenomena that cannot be explained by this model, and some of its key concepts have been challenged and amended in recent years. 


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