Coral-zooxanthellae meta-transcriptomics reveals integrated response to pollutant stress

Area of Science:

• Marine Biology
• Ecotoxicology
• Symbiotic Interactions

Background:

• Corals are symbiotic meta-organisms reliant on coral animals, zooxanthellae, and microbes for stress resilience.
• Investigated integrated responses in Acropora formosa to the emerging marine pollutant 1,3,5-trinitro-1,3,5 triazine (RDX).

Purpose of the Study:

• To examine the integrated transcriptomic responses of coral animals and their symbiotic zooxanthellae to RDX exposure.
• To understand the physiological and molecular mechanisms of coral holobiont adaptation to RDX.

Main Methods:

• Exposure of Acropora formosa to varying concentrations of RDX (0-7.2 mg/L) for 5 days.
• Quantification of RDX accumulation using bioconcentration factors.
• Meta-transcriptomic analysis of coral and zooxanthellae gene expression using microarray.
• Analysis of differentially expressed transcripts (DET) and gene networks.

Main Results:

• RDX readily accumulated in coral tissues (BCF 1.1-1.5).
• Coral exhibited increased expression of xenobiotic detoxification genes (cytochrome P450, UGT2) and mucocyte density at low RDX concentrations.
• Zooxanthellae showed decreased expression of energy metabolism and photosynthesis genes at RDX concentrations ≥1.8 mg/L.
• Coral demonstrated increased expression of energy production genes.

Conclusions:

• Coral and zooxanthellae displayed correlated transcriptional responses in energy metabolism, suggesting compensatory mechanisms within the holobiont.
• RDX exposure elicits complex, integrated responses in the coral holobiont.
• Understanding holobiont-species interactions is crucial for assessing pollutant impacts.