Hsp60 expression profiles in the reef-building coral Seriatopora caliendrum subjected to heat and cold shock regimes

- Different regimes of both short-term heat and cold shocks were tested in Seriatopora caliendrum.
- Specific thresholds of tolerance were detected through the combined analysis of the Hsp60 expression and tissue pigmentation.
- An Hsp60 modulation was observed following cold stresses.
- The physiological response appeared related to the intensity of the stress, whether it is a heat or cold shock.
- Both the severe cold and heat shocks produced a strong down-regulation of the Hsp60 expression.

Climate changes have increased the intensity/frequency of extreme thermal events, which represent serious threats to the health of reef-building corals. Since the vulnerability of corals exposed to thermal stresses are related to their ability to regulate Heat shock proteins (Hsps), we have analyzed together the time related expression profiles of the mitochondrial Hsp60 and the associated changes in tissue pigmentation in Seriatopora caliendrum subjected to 48 h of heat and cold treatments characterized by moderate (±2 °C) and severe (±6 °C) shocks. For the first time, an Hsp60 response was observed in a scleractinian coral exposed to cold stresses. Furthermore, the Hsp60 modulations and the changes in the tissue coloration were found to be specific for each treatment. A strong down-regulation at the end of the treatments was observed following both the severe shocks, but only the severe heat stress led to bleaching in concert with the lowest levels of Hsp60, suggesting that a severe heat shock can be more deleterious than an exposure to a severe cold temperature. On the contrary, a moderate cold stress seems to be more harmful than a moderate temperature increase, which could allow coral acclimation. Our results can provide a potential framework for understanding the physiological tolerance of corals under possible future climate changes.