Meeting Abstract
Hydrostatic pressure influences the physiology of deep-sea animals through multiple mechanisms, such as altering enzyme kinetics and increasing phospholipid membrane viscosity. The Ctenophora, or “comb jellies”, have repeatedly colonized most of the water column, from sea level to ~7 km deep, where ambient pressure is about 700 atm. Consequently, we have chosen these animals as a system for studying biochemical adaptation to pressure in an evolutionary context.
Here we discuss ways to identify molecular determinants of pressure tolerance by comparing the transcriptomes of 34 ctenophore species. These bioinformatic techniques can be applied to a variety of environmental parameters. Correlations of protein-coding sequence to habitat depth are probed functionally through a cloning/reciprocal mutagenesis experiment in which ctenophore pyruvate kinase orthologs are expressed and assayed over a 900-atm pressure range. We also present a phylogenetic comparative analysis of fatty acid composition in ctenophores vis-a-vis regulating membrane viscosity at high pressure, and search for transcriptomic signatures of this critical biochemical trait.
Our immediate objective for the approaches presented is to characterize the scope of convergent evolution in ctenophores: When lineages adapt independently to a similar habitat, does homoplasy appear at the scale of metabolic pathways? Of genes? Of individual amino acid sites? More broadly, our methods are intended to have utility for any investigator exploring mechanisms of extreme environmental tolerance though related species’ transcriptomes.
