Heat-shock response and antioxidant defense during air exposure in Patagonian shallow-water limpets from different climatic habitats

Abstract

Climate warming involves not only a rise of air temperature means, but also more frequent heat waves in many regions on earth, and is predicted to intensify physiological stress especially in extremely changeable habitats like the intertidal. We investigated the heat-shock response (HSR) and enzymatic antioxidant defense levels of Patagonian shallow-water limpets, adapted to distinct tidal exposure conditions in the sub-and intertidal. Limpets were sampled in the temperate Northern Patagonia and the subpolar Magellan region. Expression levels of two Hsp70 genes and activities of the antioxidants superoxide dismutase (SOD) and catalase (CAT) were measured in submerged and 2-and 12-h air-exposed specimens. Air-exposed Patagonian limpets showed a tiered HSR increasing from South to North on the latitudinal gradient and from high to low shore levels on a tidal gradient. SOD activities in the Magellan region correlated with the tidal rhythm and were higher after 2 and 12 h when the tide was low at the experimental site compared to the 6 h value taken at high tide. This pattern was observed in intertidal and subtidal specimens, although subtidal individuals are little affected by tides. Our study shows that long-term thermal adaptation shapes the HSR in limpets, while the oxidative stress response is linked to the tidal rhythm. Close to the warm border of their distribution range, energy expenses to cope with stress might become overwhelming and represent one cause why the limpets are unable to colonize the shallow intertidal zone.

Age-dependent expression of stress and antimicrobial genes in the hemocytes and siphon tissue of the Antarctic bivalve, Laternula elliptica, exposed to injury and starvation

“…The systemic occurrence of a starved phenotype may not be primarily apparent in the tissues tested in this experiment, especially the hemocytes, as one of the first biochemical symptoms would be mobilization of stored energy reserves, such as fat or protein. In addition, the induction of stress response genes in Antarctic invertebrates is potentially attenuated in Antarctic species compared with comparable temperate invertebrates (see the tiered response of heat shock genes to tidal emersion in Antarctic and Patagonian limpets in Pöhlmann et al 2011).…”

Oxygen isotopic composition of limpet shells from the Beagle Channel: implications for seasonal studies in shell middens of Tierra del Fuego

“…However it is worth noting that these species inhabit different shore levels and display different physiological strategies to survive to thermal stress and air exposure during tidal emersion (e.g. Malanga et al, 2004;Pöhlmann et al, 2011). In particular, it has been demonstrated that N. magellanica has a more efficient response to short periods of tidal exposure and enhanced temperatures compared with N. deaurata (Pöhlmann et al, 2011).…”

“…Malanga et al, 2004;Pöhlmann et al, 2011). In particular, it has been demonstrated that N. magellanica has a more efficient response to short periods of tidal exposure and enhanced temperatures compared with N. deaurata (Pöhlmann et al, 2011). Therefore, aforementioned differences could to some extent reflect different specie-specific physiological responses to environmental stress.…”

Role of sequential low-tide-period conditions on the thermal physiology of summer and winter laboratory-acclimated fingered limpets, Lottia digitalis

“…Arial exposure may act as an important factor modulating upper temperature tolerance, as this is a predictable aspect of environmental change in the intertidal zone (Gracey et al 2008;Miller et al 2009;Pöhlmann et al 2011;Connor and Gracey 2012;Bjelde and Todgham 2013;Han et al 2013;Huang et al 2015).…”