title: Gene expression biomarkers of heat stress in scleractinian corals: Promises and limitations.
abstract: Gene expression biomarkers (GEBs) are emerging as powerful diagnostic tools for identifying and characterizing coral stress. Their capacity to detect sublethal stress prior to the onset of signs at the organismal level that might already indicate significant damage makes them more precise and proactive compared to traditional monitoring techniques. A high number of candidate GEBs, including certain heat shock protein genes, metabolic genes, oxidative stress genes, immune response genes, ion transport genes, and structural genes have been investigated, and some genes, including hsp16, Cacna1, MnSOD, SLC26, and Nf-kB, are already showing excellent potential as reliable indicators of thermal stress in corals. In this mini-review, we synthesize the current state of knowledge of scleractinian coral GEBs and highlight gaps in our understanding that identify directions for future work. We also address the underlying sources of variation that have sometimes led to contrasting results between studies, such as differences in experimental set-up and approach, intrinsic variation in the expression profiles of different experimental organisms (such as between different colonies or their algal symbionts), diel cycles, varying thermal history, and different expression thresholds. Despite advances in our understanding there is still no universally accepted biomarker of thermal stress, the molecular response of corals to heat stress is still unclear, and biomarker research in Symbiodinium still lags behind that of the host. These gaps should be addressed in future work.
authors: Department of Biosciences, Faculty of Science, University of Mauritius, Réduit 80837, Mauritius.
authors: Yohan D
authors: YD
authors: Louis
authors: Department of Marine & Ocean Science, Fisheries & Mariculture, Faculty of Ocean Studies, University of Mauritius, Réduit 80837, Mauritius. Electronic address: r.bhagooli@uom.ac.mu.
authors: Ranjeet
authors: R
authors: Bhagooli
authors: Australian Institute of Marine Science, PMB No. 3, Townsville MC, QLD 4810, Australia.
authors: Carly D
authors: CD
authors: Kenkel
authors: Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Cswy., Miami, FL, USA.
authors: Andrew C
authors: AC
authors: Baker
authors: Department of Biosciences, Faculty of Science, University of Mauritius, Réduit 80837, Mauritius.
authors: Sabrina D
authors: SD
authors: Dyall
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000235:genetics* / Q000378:metabolism; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods; D005786:Gene Expression Regulation; D005819:Genetic Markers; D018869:Heat-Shock Response; D013559:Symbiosis; D013696:Temperature
chemical_list: D005819:Genetic Markers
keywords: Coral; Gaps; Gene expression biomarkers; Thermal stress; Variations