Age-related thermal response: the cellular resilience of juveniles

Abstract

Understanding species' responses to environmental challenges is key to predicting future biodiversity. However, there is currently little data on how developmental stages affect responses and also whether universal gene biomarkers to environmental stress can be identified both within and between species. Using the Antarctic clam, Laternula elliptica, as a model species, we examined both the tissue-specific and age-related (juvenile versus mature adult) gene expression response to acute non-lethal warming (12 h at 3°C). In general, there was a relatively muted response to this sub-lethal thermal challenge when the expression profiles of treated animals, of either age, were compared with those of 0°C controls, with none of the Bclassical^stress response genes up-regulated. The expression profiles were very variable between the tissues of all animals, irrespective of age with no single transcript emerging as a universal biomarker of thermal stress. However, when the expression profiles of treated animals of the different age groups were directly compared, a very different pattern emerged. The profiles of the younger animals showed significant up-regulation of chaperone and antioxidant transcripts when compared with those of the older animals. Thus, the younger animals showed evidence of a more robust cellular response to warming. These data substantiate previous physiological analyses showing a more resilient juvenile population.

Variability and change in the west Antarctic Peninsula marine system: Research priorities and opportunities

“…Antarctic fish (Bilyk and DeVries 2011) and invertebrates (Morley et al 2016;Peck 2018;Peck et al 2009Peck et al , 2014 have very limited tolerance to warming in laboratory-based experiments, indicating that acclimation to elevated temperature is poor in Antarctic species (Peck et al 2014). Thermal tolerances are influenced by a number of different species-specific factors (Clark et al 2017), including heat shock responses to warming (Clark and Peck 2009;Clark et al 2008), and upper temperature limits being set by accumulation of toxic metabolic end-products (Heise et al 2007), limitation of energy reserves (Peck 2018;Peck et al 2014), and temperature sensitivity of critical enzymes (Clark et al 2016). In general, the rate of oxygen supply to tissues (Pörtner and Farrell 2008;Pörtner et al 2012) does not exert a major limitation on thermal tolerance (e.g.…”

Oceanography and Marine Biology

“…Thus, it is likely that not all members of the HSP70 family were identified. In the same series of experiments, no HSR was detected in the amphipod Paraceradocus miersi, (Clark et al 2008b), but subsequent thermal challenges using discovery-led next-generation sequencing (NGS) did in fact reveal the possession of a thermally inducible form of HSP70 (Clark et al 2016). In the Antarctic krill Euphausia superba and E. crystallorophias, gene duplication events were shown to have occurred that produced several forms of HSP70 but even so change has to have only resulted in a weak HSR (Cascella et al 2015).…”

“…In a recent study using acute warming of 1°C h −1 , Clark et al (2016) showed that the HSR varied markedly between six different species of Antarctic marine invertebrate, with each species having its own response to warming. They used a combined transcriptomic and metabolomics approach to evaluate the response to acute warming and demonstrated that the upregulation of the production of members of the HSP70 family occurred in three species, (the amphipod Paraceradocus miersi, the rhynchonelliform brachiopod Liothyrella uva and the bivalve mollusc Laternula elliptica), whereas in three others (the gastropod mollusc Marseniopsis mollis, the holothurian Cucumaria georgiana and the bivalve mollusc Aequiyoldia eightsii), there was no indication of any change in HSP70 production at this particular rate of thermal change.…”

Expression pattern of heat shock proteins during acute thermal stress in the Antarctic sea urchin, Sterechinus neumayeri

“…The expression of Grp78 has been evaluated in gonad tissue in the Antarctic seastar O. validus [20,22], showing that its expression is not inducible during thermal stress at different temperatures (2, 6 and 10°C). In contrast, the expression of Grp78 in L. elliptica molluscs increased in the gills, mantle and siphon [20,48]. In S. neumayeri, the overexpression of this gene has a delayed response.…”

“…This demonstrates the necessity to broaden the number of tissues studied, as the expression of chaperones could be tissue specific and one tissue could respond more than another to a certain thermal stress condition as seen in other models [19,48].…”