Ben-Gurion 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
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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