Local acclimatisation-driven differential gene and protein expression
patterns of Hsp70 in Acropora muricata: implications for coral tolerance
to bleaching
Abstract
Corals show spatial acclimatisation to local environment conditions.
However, the various cellular mechanisms involved in local
acclimatisation and variable bleaching patterns in corals remain to be
thoroughly understood. In this study, the modulation of a protein
implicated in cellular heat stress tolerance, the Heat shock protein 70,
was compared at both gene (hsp70) and protein (Hsp70) expression level
in bleaching tolerant near-coast Acropora muricata colonies and
bleaching susceptible reef colonies, in the lagoon of Belle Mare
(Mauritius). The relative Hsp70 levels varied significantly between
colonies from the two different locations, colonies having different
health conditions and the year of collection. Before the bleaching event
of 2016, near-coast colonies had higher basal levels of both Hsp70 gene
and protein compared to reef colonies. During the bleaching event, the
near-coast colonies did not bleach and had significantly higher relative
levels of both Hsp70 gene and protein compared to bleached reef
colonies. No significant genetic differentiation between the two studied
coral populations was observed and all the colonies analysed were
associated with Symbiodiniaceae of the genus Symbiodinium (Clade A)
irrespective of location and sampling period. These findings provide
further evidence of the involvement of Hsp70 in conferring bleaching
tolerance to corals. Moreover, the consistent expression differences of
Hsp70 gene and protein between the near-coast and reef coral populations
in a natural setting indicate that the modulation of this Hsp is
involved in local acclimatisation of corals to their environments.