Sequential developmental events, starting from the moment of fertilization, are crucial for the acquisition of animal body plan. Subtle modifications in such early events are likely to have major impacts in later morphogenesis, bringing along morphological diversification. Here, comparing the blind cave and the surface morphotypes of Astyanax mexicanus fish, we found heterochronies during gastrulation, producing organizer and axial mesoderm tissues with different properties, including differences in expression of dkk1b, that may have contributed to cavefish brain evolution. These variations observed during gastrulation depend fully on maternal factors. The developmental evolution of retinal morphogenesis and hypothalamic patterning are among those traits that retained significant maternal influence at larval stages. Transcriptomic analysis of fertilized eggs from both morphotypes and reciprocal F1 hybrids showed a strong and specific maternal signature. Our work strongly suggests that maternal effect genes and developmental heterochronies occurring during gastrulation have impacted morphological brain change during cavefish evolution.
- Sylvie Rétaux
- Sylvie Rétaux
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: Animal experimentation: Animals were treated according to the French and European regulationsfor handling of animals in research. SR's authorization for use of animals in research including Astyanax mexicanus is 91-116 and Paris Centre-Sud Ethic Committee authorization numbers are 2012-0052, -0053, and -0054.
- Marianne E Bronner, California Institute of Technology, United States
- Received: July 12, 2019
- Accepted: October 30, 2019
- Accepted Manuscript published: October 31, 2019 (version 1)
© 2019, Torres-Paz et al.
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