UNDERSTANDING TEMPERATURE ACCLIMATION IN SYMBIODINIUM: AN INTERDISCIPLINARY APPROACH
Open Access
- Author:
- Diaz Almeyda, Erika
- Graduate Program:
- Biology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- May 07, 2015
- Committee Members:
- Monica Medina, Dissertation Advisor/Co-Advisor
- Keywords:
- Symbiodinium
temperature acclimation
transcriptomics
symbiosis
coral bleaching
global warming
climate change - Abstract:
- I quantified the thermotolerance in 11 cultures from different populations of five species of Symbiodinium clade A. we grew cultures at 26°C and 32°C over 18 days, measuring growth and photochemical efficiency (Fv/Fm). Thermotolerance was not restricted to a single species but it was widespread across species and cultures, showing a gradient from susceptible to tolerant. All cultures at 32°C decreased growth and Fv/Fm. To test the synergistic effect of temperature and light, we cultured three strains (tolerant, intermediate, and susceptible) in five different light intensities at 26°C and 32°C. Strains surviving stressful light and temperature exhibited less growth and quicker damage by light. To investigate the mechanisms behind thermoacclimation, we cultured S. microadriaticum (CassKB8) with intermediate thermotolerance at 26°C and 32°C. Gene expression was explored first using cDNA microarrays before (day -2), and during acclimation (day 6 and 16). Differentially expressed genes (DEG) due to increased temperature were time dependent. DEG on day 16 were likely a result of the start of the stationary phase in culture. Similarly, RNA-Seq data (day 5 and 7) suggest temporal variation in gene expression with major changes in heat-shock proteins and chaperones. Retrotransposons were highly expressed on day 7, indicating high stress during thermal exposure. Adaptation to higher temperatures is not restricted to a single clade or species but it is widespread within species. However, acclimating to higher temperatures compromises health and increases chaperone activity.