M.K. DeSalvo, S. Sunagawa, C.R. Voolstra, M. Medina.
Marine Ecology Progress Series, volume 402, pp. 97-113, (2010)
The emergence of genomic tools for reef-building corals and symbiotic
anemones comes at a time when alarming losses in coral cover are being
observed worldwide. These tools hold great promise in elucidating novel
and unforeseen cellular processes underlying the successful mutualism
between corals and their dinoflagellate endosymbionts Symbiodinium
spp. Since thermal stress triggers a breakdown in the symbiosis (coral
bleaching), measuring the transcriptomic response to thermal
stress-induced bleaching offers an extraordinary view of cellular
processes that are specific to coral–algal symbioses. In the present
study, we utilized a cDNA microarray containing 2059 genes of the
threatened Caribbean elkhorn coral Acropora palmata to identify
genes that are differentially expressed upon thermal stress. Fragments
from replicate colonies were exposed to elevated temperature for 2 d,
and samples were frozen for microarray analysis after 24 and 48 h.
Totals of 204 and 104 genes were differentially expressed in samples
that were collected 1 and 2 d after thermal stress, respectively.
Analysis of the differentially expressed genes indicates a cellular
stress response in A. palmata involving (1) growth arrest, (2)
chaperone activity, (3) nucleic acid stabilization and repair, and (4)
removal of damaged macromolecules. Other differentially expressed
processes include sensory perception, metabolite transfer between host
and endosymbiont, nitric oxide signaling, and modifications to the actin
cytoskeleton and extracellular matrix. The results are compared with
those from a previous coral microarray study of thermal stress in Montastraea faveolata, and point to an overall evolutionary conserved bleaching response in scleractinian corals.