Comparison of heat-shock responses between the hydrothermal vent shrimp Rimicaris exoculata and the related coastal shrimp Palaemonetes varians

Abstract

The deep-sea vent shrimp Rimicaris exoculata is believed to occur at the hot end of the hydrothermal biotope in order to provide essential elements to its epibiosis. Because it is found close to hot venting water, R. exoculata lives in a highly fluctuating environment where temperature (2-40°C in the swarms) can exceed its critical maximal temperature (33-38.5± 2°C). In order to understand how this vent shrimp copes with hyperthermia, we compared its molecular heat stress response following an acute but non-lethal heat-shock (1 h at 30°C) with that of its monophyletic shallow-water relative, the shrimp Palaemonetes varians, known to frequently undergo prolonged exposure at temperatures up to 30°C in its natural environment during summer. We isolated four isoforms of heat-shock proteins 70 (HSP70) in R. exoculata (2 constitutive and 2 inducible isoforms) and two isoforms in P. varians (1 constitutive and 1 inducible isoform) and quantitatively compared their magnitude of induction at mRNA level, using real-time PCR, in the case of experimentally heat-stressed shrimps, with respect to control (unstressed) animals. Here, we report the first quantification of the expression of multiple hsp70 genes following heat stress in a deep-sea vent species living at 2300 m depth. Our results show a strong increase of hsp70 inducible genes in the vent shrimp (∼400-fold) compared to the coastal shrimp (∼15-fold). We therefore propose that, the highly inducible molecular response observed in R. exoculata may contribute to the ability of this species to tolerate thermal extremes.

The role of ontogeny in physiological tolerance: decreasing hydrostatic pressure tolerance with development in the northern stone crabLithodes maja

“…These results are consistent with previous studies demonstrating increased transcription of genes coding for heat-shock proteins in response to the effects of high hydrostatic pressure and/or low temperature [26,27,29]. Increases in hydrostatic pressure have long been known to affect protein folding, impacting quaternary, tertiary and secondary structure [63].…”

Characterising multi-level effects of an acute pressure exposure on a shallow-water invertebrate: insights into the kinetics and hierarchy of the stress response

“…Results of this study confirm that the hsp70 (form 1) gene is responsive to acute hydrostatic pressure stress. The relative fold change of the hsp70 (form 1) gene shown in this study is lower, however, than observed in previous research in response to a large temperature shock (Cottin et al, 2010;Ravaux et al, 2012). The hsp70 (form 2) gene showed no changes in expression at any time points, thus in response to pressure stress alone, the gene remains constitutively expressed.…”

“…In this study, significant increases in the transcription of four genes; narg, gapdh, hsp70 (form 1) and actin were recorded in both the head and abdomen of Palaemonetes varians at various time points from 0 to 24 h following exposure to an acute 2 h hydrostatic pressure treatment. A second hsp70 isoform, hsp70 (form 2), which has previously been characterised as non-inducible following a heat stress (Cottin et al, 2010), was not transcriptionally regulated at any of the time points. Furthermore, respiration rates of the shrimp showed similar patterns to that revealed by the expression of the genes described above.…”

“…For the molecular aspect of this study, genes were chosen that had been previously shown to exhibit differential expression in response to acute temperature and hydrostatic pressure exposures (Cottin et al, 2010(Cottin et al, , 2012Morris et al, 2015). The gapdh gene and the two hsp70 isoforms constitute part of the universal CSR (Kültz, 2005).…”

Stress levels over time in the introduced ascidian Styela plicata: the effects of temperature and salinity variations on hsp70 gene expression

“…Stress response mechanisms allow marine organisms to cope with unexpected or sharp fluctuations in one or several biotic or abiotic factors (Aruda et al 2011;Clark and Peck 2009;Cottin et al 2010;Huang et al 2011;Lockwood et al 2010). Depending on the extent and duration of the stress, organisms can recover, survive for a time with an impaired fitness, or die.…”