Mechanisms of developmental buffering

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PROJECT SUMMARY/ABSTRACT: The long-term objective of this proposal is to understand genetic buffering, or how some individuals overcome the effects of a harmful genetic mutation. We generated a zebrafish model of buffering in order to understand how individuals who should have gotten sick are somehow able to live unaffected healthy lives. In our model, we used selective breeding to generate two strains of zebrafish that develop dramatically different head skeletons in response to the same harmful genetic mutation. In one strain, the mutation causes severe, lethal skeletal defects. Meanwhile, the other strain is remarkably buffered against the mutation. The buffered fish develop essentially normal head skeletons, surviving to be fertile, viable adults. We compare these strains to understand the natural buffering mechanisms that are present in some fish, and likely in some humans too. We hypothesize that buffering is due to factors that tune developmental processes to restore balance. For example, in Aim1 we will determine how DNA sequences which oppose the mutant gene can be turned down. In Aim 2 we examine how factors encoded in the DNA which perform the same function as the mutant gene can be turned up. In Aim 3 we will determine how changes that do not necessarily involve alterations in the DNA sequence can buffer the harmful mutation. These three specific aims test how interacting mechanisms function together to buffer development. We designed experiments to address these aims using state of the art methods like genome editing and sequencing, colorful cell and tissue labeling, quantitative measurements of large numbers of fish skeletons, and rigorous statistical analyses. The mechanisms we propose to study here are present in many developmental systems and organisms and therefore will likely be applicable in wide- ranging settings. This study of buffering mechanisms could lead to novel therapeutic approaches, buffering mechanisms might be manipulated in the future to manage disease symptoms. This work will also lead to a better understanding of the factors that make predicting genetic disease from gene sequences difficult. Thus, this line of research will potentially inform and improve medical practices, including genetic disease management, disease diagnosis, and counseling, falling squarely within the mission of the NIDCR to improve dental, oral and craniofacial health through research.