Science Inventory

The Toxicogenome of Hyalella azteca: A Model for Sediment Ecotoxicology and Evolutionary Toxicology

Citation:

Poynton, H., S. Hasenbein, J. Benoit, M. Sepulveda, M. Poelchau, D. Hughes, S. Murali, S. Chen, K. Glastad, M. Goodisman, M. Friedrich, J. Jones, H. Robertson, R. Feyereisen, A. Mechler-Hickson, N. Mathers, C. Lee, J. Colbourne, A. Biales, J. Johnston, G. Wellborn, A. Rosendale, A. Cridge, M. Munoz-Torres, P. Bain, A. Manny, K. Major, F. Lambert, C. Vulpe, P. Tuck, B. Blalock, Y. Lin, J. Werren, M. Smith, H. Ochoa-Acuna, M. May Chen, C. Childers, J. Qu, S. Dugan, S. Lee, H. Chao, H. Dinh, Y. Han, H. Dossapaneni, K. Worley, D. Muzny, R. Gibbs, AND S. Richards. The Toxicogenome of Hyalella azteca: A Model for Sediment Ecotoxicology and Evolutionary Toxicology. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 52(10):6009–6022, (2018). https://doi.org/10.1021/acs.est.8b00837

Impact/Purpose:

Sediment quality assessments serve as a metric for overall habitat integrity. Sediments are the foundation for aquatic food webs, providing habitat for invertebrate species and insect larvae. However, sediments integrate and concentrate pollution over time, especially hydrophobic contaminants that sorb to sediments, leading to bioaccumulation in the food web.While concentrations of a few legacy contaminants are declining in the United States due to regulatory efforts; chemicals designed as their replacements are becoming emerging contaminants and levels are increasing. This is particularly true of newer generation pesticides, which have become problematic in urban areas, and complex mixtures of pharmaceuticals and personal heath care products.

Description:

Hyalella azteca is a cryptic species complex of epibenthic amphipods of interest to ecotoxicology and evolutionary biology. It is the primary crustacean used in North America for sediment toxicity testing and an emerging model for molecular ecotoxicology. To provide molecular resources for sediment quality assessments and evolutionary studies, we sequenced, assembled, and annotated the genome of the H. azteca U.S. Lab Strain. The genome quality and completeness is comparable with other ecotoxicological model species. Through targeted investigation and use of gene expression data sets of H. azteca exposed to pesticides, metals, and other emerging contaminants, we annotated and characterized the major gene families involved in sequestration, detoxification, oxidative stress, and toxicant response. Our results revealed gene loss related to light sensing, but a large expansion in chemoreceptors, likely underlying sensory shifts necessary in their low light habitats. Gene family expansions were also noted for cytochrome P450 genes, cuticle proteins, ion transporters, and include recent gene duplications in the metal sequestration protein, metallothionein. Mapping of differentially expressed transcripts to the genome significantly increased the ability to functionally annotate toxicant responsive genes. The H. azteca genome will greatly facilitate development of genomic tools for environmental assessments and promote an understanding of how evolution shapes toxicological pathways with implications for environmental and human health.