Diel modulation of Hsp70 and Hsp60 in corals living in a shallow reef

In corals, different biological processes are associated with the daily variation of temperature and light, which in shallow reefs can vary widely and regularly reach extreme levels. The expression of cellular defense mechanisms such as the heat shock proteins Hsp70 and Hsp60 was analyzed in coral colonies adapted to live in a shallow lagoon, during three consecutive days characterized by the same temperature/light trend. Each of the three species investigated showed a significant diel modulation of both Hsps, which also displayed a coordinated expression. However, the diel modulations of both Hsps were species specific and only that of the branching Acropora tenuis appeared correlated with the temperature. All the species displayed high Hsp levels at 13.00 and 16.00, probably as protection for the cellular stress produced by the elevated temperature and light. Taken together, the results may provide useful information about the cellular mechanisms involved in the corals adaptation to extreme conditions.