Assessment of HSP70 and catalase in Brachidontes rodriguezii (d’Orbigny, 1842) a mussel from the Argentinean coast

Abstract

Introduction: Intertidal ecosystems are complex environments of great importance for the ecological balance of coastal zones and are vulnerable areas to effects caused by natural stressors of global relevance such as temperature. Mussels, are often exposed to drastic variations of temperature and can show intracellular mechanisms of compensation that allow them to counteract exposure in the short and medium term at high temperatures. Heat shock proteins are chaperones that allow thermal stability of proteins against abrupt changes in temperature and catalase is an antioxidant enzyme that aid cells to fight against oxidative stress caused by diverse environmental stressors [1,2].

Materials and methods: Mussel samples were homogenized in PBS buffer (phosphate saline solution, pH =7.4) and centrifuged (10,000×g for 15 min at 4 °C). Afterwards, the supernatants were transferred to 1.5 ml microtubes and stored at −80 °C until analysis. The HSP70 (Heat shock Proteins) levels were determined in individuals from both sexes, exposed at different temperatures (20 °C, 24 °C, 26 °C y 28 °C) for 7 and 14 days. Organisms sampled at T0 were also analysed. The HSP70 levels were determined by ELISA (Enzyme Linked Immunosorbent Assay) as described by Madeira et al. [2] and catalase following the method described in Diniz et al. [3].

Results and discussion: The preliminary results show an absence of significant differences between sexes of HSP70 levels at T0, 20 °C and 24 °C. However, at 26 °C and 28 °C, a differentiated response was observed in organisms exposed at higher temperatures, where the females had higher levels of HSP70 in the short term (7 days) compared to male individuals (p <0.05). In the medium term (14 days) it was observed that females have similar or lower values than males.

Conclusions: The results show the ability to evaluate thermal stress by determining biomarkers such as HSP70 or antioxidant enzymes in tissues of B. rodriguezii providing valuable information to a better understanding of the effects of natural stressors on marine organisms. It also establishes that the sex of animals is a major factor of importance when evaluating this type of responses related to thermal stress.

Acknowledgements

This work was supported by the Unidade de Ciências Biomoleculares Aplicadas-UCIBIO which is financed by national funds from FCT/MEC (UID/Multi/04378/2013) and co-financed by the ERDF under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007728).