Elucidating the stress phenome in reef building corals through a multi-omics approach
Creators: name: Williams, Amanda R.
Publisher: name: No Publisher Supplied
Year: 2023

description: Since their radiation in the Middle Triassic period ~ 240 million years ago, stony corals have survived past climate fluctuations and five mass extinctions. Their long-term survival underscores the inherent resilience of corals, particularly when considering the nutrient-poor marine environments in which they have thrived. Unfortunately, current environmental changes have proven to be beyond anything since the last glaciation, causing a horrific trajectory of reef devastation. In my doctoral research, I applied multiomics approaches to thermally stressed coral samples to expose aspects of the bleaching mechanism and advance coral conservation by developing diagnostic tools. A stress-resistant Hawaiian coral species, Montipora capitata, was subjected to short-term thermal stress. Metabolomic, transcriptomic, proteomic, and metagenomic data were generated from these samples for individual and integrated analysis. Characterized metabolic features include central metabolites, such as amino acids, nucleotides, and sugar phosphates, as well as many secondary metabolites. The most significant metabolites correlated to thermal stress were a suite of dipeptides which showed a time- dependent increase under high-temperature stress. In contrast, Montiporic acids, a family of disubstituted acetylenes that exhibit antimicrobial activity and cytotoxicity, maintained high ion counts as bleaching progressed, despite the high energy required for their biosynthesis. With the transcriptomic data, gene co-expression networks showed that the early thermal stress response involves the downregulation of growth and DNA replication, whereas signaling and the immune response are strongly upregulated. Integration of gene-metabolite data demonstrated that the most significant animal response is to redox stress, with the detoxification of reactive oxygen species comprising many upregulated reactions. Differential regulation of the highly conserved cytochrome P450 gene family was of particular interest, as the downregulation of CYP1A1 involved in progesterone metabolism potentially explains the observed dysregulation of mass spawning in warming oceans. Accutest URS-10 Urine Reagent Strips, which are invitro diagnostic test devices to obtain qualitative and semi-quantitative reaction results, were used to measure biomarkers of coral stress during bleaching. Two of the ten enzymatic tests appear applicable to corals: ketone bodies and leukocytes. M. capitata, which can capture its energy needs through heterotrophic feeding, didn’t display any elevated ketone levels, but leukocyte test results displayed increased enzymatic activity throughout the thermal experiment. Lastly, I examined the interactions between the omics datasets across the coral holobiont and how well each dataset correlated with thermal stress. The data suggests that experimental factors impact each omics layer differently. Unlike the other omics data, polar metabolite data is significantly influenced by every factor tested, which may explain the complex signals displayed in the ordination plots not present in the transcriptomic and proteomic data. Altogether, my thesis highlights the potential, as well as the limits, of multiomics data applications concerning data interpretation and diagnostic test development for the coral holobiont.