DOI: 10.5061/dryad.0zpc86746
title: Effect of the histone deacetylase inhibitor Trichostatin A on facial development in cichlid fishes

description: A central question in biology is the molecular origins of phenotypic
 diversity. While genetic changes are key to the genotype-phenotype
 relationship, alterations to chromatin structure and the physical
 packaging of histone proteins may also be important drivers of vertebrate
 divergence. We investigate the impact of such an epigenetic mechanism,
 histone acetylation, within a textbook example of an adaptive radiation.
 Cichlids of Lake Malawi have adapted diverse craniofacial structures, and
 here we investigate how histone acetylation influences morphological
 variation in these fishes. Specifically, we assessed the effect of
 inhibiting histone deacetylation using the drug trichostatin A (TSA) on
 developing facial structures. We examined this during three critical
 developmental windows in two cichlid species with alternate adult
 morphologies. Exposure to TSA during neural crest cell (NCC) migration and
 as post-migratory NCCs proliferate into the pharyngeal arches resulted in
 significant changes in lateral and ventral shape in Maylandia, but not in
 Tropheops. This included an overall shortening of the head, widening of
 the lower jaw, and steeper craniofacial profile, all of which are
 paedomorphic morphologies. In contrast, treatment with TSA during early
 chondrogenesis did not result in significant morphological changes in
 either species. Together, these data suggest a sensitivity to epigenetic
 alterations that are both time- and species-dependent. We find that
 morphologies are due to non-autonomous or potentially indirect effects on
 NCC development, including in part a global developmental delay. Our
 research bolsters the understanding that proper histone acetylation is
 essential for early craniofacial development and identifies a
 species-specific robustness to developmental change. Overall, this study
 demonstrates how epigenetic regulation may play an important role in both
 generating and buffering morphological variation.
description: # Effect of the histone deacetylase inhibitor Trichostatin A on facial
 development in cichlid fishes
 [https://doi.org/10.5061/dryad.0zpc86746](https://doi.org/10.5061/dryad.0zpc86746) The files deposited in this repository were collected to examine the effects of a chemical treatment (Trichostatin A) on craniofacial morphology in Tropheops sp. "red fin" (Tropheops) and Maylandia zebra (Maylandia) during development. Each species was analyzed separately. Files named \_TPS files include ventral (named Species\_ventral) and lateral (named Species\_lateral) landmark data used for geometric morphometric shape analysis. \_PCscores.csv contain the principal component scores from the geometric morphometric analysis. The "Maylandia\_dev\_delay" files were collected to see if the effects of the Trichostain A treatment were causing a developmental delay in Maylandia. Timepoints are indicated in file and sample names based on days of cichlid development during which treatments occurred. That is, samples marked 2\_3 were treated from 2 dpf to 3 dpf (stage 10-11), 3\_4 is from 3 dpf to 4 dpf (stage 11-15) and 5\_6 is from 5 dpf to 6 dpf (stage 17-18) based on Fujimura & Okada, 2007.