Effect of acclimation on thermal limits and hsp70 gene expression of the New Zealand sea urchin Evechinus chloroticus.

Autor: Delorme NJ; Cawthron Institute, Private Bag 2, Nelson 7042, New Zealand; Institute of Marine Science, Leigh Marine Laboratory, University of Auckland, P.O. Box 349, Warkworth 0941, New Zealand; School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. Electronic address: natali.delorme@cawthron.org.nz., Frost EJ; School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand., Sewell MA; School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
Jazyk: angličtina
Zdroj: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology [Comp Biochem Physiol A Mol Integr Physiol] 2020 Dec; Vol. 250, pp. 110806. Date of Electronic Publication: 2020 Sep 12.
DOI: 10.1016/j.cbpa.2020.110806
Abstrakt: Seawater temperature is projected to increase globally due to climate change, affecting physiological responses, fitness and survival of marine organisms. Thermal tolerance studies are critical to determine the ability of animals to adapt to future environmental conditions. In this study, we aimed to determine if the thermal limits of the New Zealand Evechinus chloroticus would shift with animal's thermal history. We tested the effect of six thermal regimes on the righting ability, temperature of loss of righting (T LOR ), median lethal temperature (LT 50 ), lethal temperature (LT) and the gene expression of the heat shock protein 70 (hsp70) of the New Zealand sea urchin E. chloroticus when exposed to a thermal shock of 1 °C day -1 (duration of 7-16 days depending on the treatment). Treatments consisted of laboratory acclimation for one and four weeks to 18 °C and 24 °C (mean winter (15 °C) and summer temperature (21 °C) + 3 °C of warming, respectively), compared to non-acclimated sea urchins collected during winter (14.6 °C) and summer seasons (20.4 °C). Thermal history did not have a significant effect on the righting ability of E. chloroticus (T LOR ranged between 28 and 29 °C for all treatments) and LT 50 (ranged between 29 and 30 °C for all treatments). However, LT of E. chloroticus collected during winter season was significantly lower than animals acclimated for one week at 18 °C. Maximum expression of hsp70 mRNA (T max ) was observed at around 27-28 °C regardless of treatment; however, relative hsp70 mRNA levels were significantly higher in animals acclimated for four weeks at 24 °C. Despite proving to be a thermotolerant species with LTs around 30 °C, E. chloroticus was unable to increase thermal tolerance and T max when acclimated to high temperatures, suggesting that E. chloroticus may have a limited adaptive capacity to modify its phenotype; however, evolutionary adaptations may allow E. chloroticus to adapt to future ocean temperatures.
(Copyright © 2020 Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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