The Genetic Basis of Tooth Size Differences in Cavefish
Start Date
2023 4:00 PM
Location
Alter Hall Poster Session 2 - 2nd floor
Abstract
The Mexican tetra (Astyanax mexicanus) fish consists of two interfertile forms: the sighted surface-dwelling morph and the blind cave-dwelling morph. When comparing the two morphs, the cavefish has acquired many distinct traits that are tailored to life in total darkness, while the surface fish embodies phenotypes similar to those of other river-dwelling species. Both forms are tractable laboratory species, allowing for genetic experimentation aiming to understand the genes underlying the evolution of morphological changes. Previous studies have identified genetic associations between regions of the cavefish genome and craniofacial phenotypes, including tooth size differences between surface and cavefish. Toward that end, we set out to discover the gene/s involved in determining tooth size and shape during development. The genes within the target region were first investigated using the genomic database Ensembl for their Gene Ontology terms, which provided information on the molecular function, biological processes, and cellular components for each gene. I surveyed 21 genes for genetic mutations using sequences extracted from natural populations in Mexico using a threshold of a 75% sequence difference or greater coupled with a significant amino acid change (nonsynonymous polymorphism). From the sequences that met the criteria, we designed genetic primers and performed PCR to amplify genetic sequences. Our PCR products were submitted for DNA sequencing and analysis. These sequences were then aligned to the A. mexicanus genome to determine if the mutations were present in our laboratory populations. Results showed that there are currently two confirmed mutations in the genes rnf32 and en2a on Chromosome 16. Future work will seek to further characterize the roles of these genes to tooth development using in situ hybridization. Ultimately, transgenic fish will be generated to determine the functional role of candidate genes in tooth development. The work produced by this project provides insight into how the Mexican tetra is an excellent genetic model for studying tooth development, and will continue to be valuable in other facets of evolutionary exploration.
The Genetic Basis of Tooth Size Differences in Cavefish
Alter Hall Poster Session 2 - 2nd floor
The Mexican tetra (Astyanax mexicanus) fish consists of two interfertile forms: the sighted surface-dwelling morph and the blind cave-dwelling morph. When comparing the two morphs, the cavefish has acquired many distinct traits that are tailored to life in total darkness, while the surface fish embodies phenotypes similar to those of other river-dwelling species. Both forms are tractable laboratory species, allowing for genetic experimentation aiming to understand the genes underlying the evolution of morphological changes. Previous studies have identified genetic associations between regions of the cavefish genome and craniofacial phenotypes, including tooth size differences between surface and cavefish. Toward that end, we set out to discover the gene/s involved in determining tooth size and shape during development. The genes within the target region were first investigated using the genomic database Ensembl for their Gene Ontology terms, which provided information on the molecular function, biological processes, and cellular components for each gene. I surveyed 21 genes for genetic mutations using sequences extracted from natural populations in Mexico using a threshold of a 75% sequence difference or greater coupled with a significant amino acid change (nonsynonymous polymorphism). From the sequences that met the criteria, we designed genetic primers and performed PCR to amplify genetic sequences. Our PCR products were submitted for DNA sequencing and analysis. These sequences were then aligned to the A. mexicanus genome to determine if the mutations were present in our laboratory populations. Results showed that there are currently two confirmed mutations in the genes rnf32 and en2a on Chromosome 16. Future work will seek to further characterize the roles of these genes to tooth development using in situ hybridization. Ultimately, transgenic fish will be generated to determine the functional role of candidate genes in tooth development. The work produced by this project provides insight into how the Mexican tetra is an excellent genetic model for studying tooth development, and will continue to be valuable in other facets of evolutionary exploration.
