Ecophysiological and transcriptomic response of two intertidal mollusc species to thermal stress

• Autor(a) principal: Casalís Cantalló, Harold
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/32828
• topic: Nucella lapillus; Mytilus galloprovincialis; Climate change; Fitness; RNAseq

Climate change is currently associated with an increased rate of global warming, largely due to greenhouse gases produced by human activities. Thus, in the Chapter 1 is addressed how intertidal ecosystems are especially fragile to the expected impacts derived from climate change, since survival rates of the species inhabiting in this tight zone are influenced in great part by the sea level to maintain their lifestyle. Therefore, were targeted two mollusc species from Portugal coasts, Nucella lapillus and Mytilus galloprovincialis. Then, in the Chapter 2, the mesocosms experimental system was designed to hold individuals of the predator snail N. lapillus and the mussel M. galloprovincialis collected from the rocky shore Belinho-Mar Beach, Esposende, Portugal. Specifically, in Chapter 3, were assessed the Physiological Responses of N. lapillus and M. galloprovincialis to thermal stress. After specimen’s acclimation to laboratorial conditions, some individuals were exposed to thermal stress ranging from 7 up to 28°C for four weeks in a bath-based system. This study aimed to assess the behaviour, physiological fitness-related responses of these two keystone species. At the end of the experiments, the metabolic and mortality rates for both species were quantified and modelled, as well as the trophic interaction and the reproductive effort in N. lapillus. To explore the molecular mechanism underlying the thermal resistance, in the Chapter 4 was profiled The transcriptomic responses of the gills from the Mediterranean mussel M. galloprovincialis under thermal stress. The whole RNA sequencing of the gills from M. galloprovincialis was sequenced after the specimen’s exposure to an acute thermal stress period using an Illumina NovaSeq 6000 150bp (base-pair) platform, further analysed with the tools included in the software OmicsBox v1.4.11. The annotated transcriptome of M. galloprovincialis revealed 1411 Expressed Genes (DEGs) within the temperature range. Some heat biomarkers were identified among DEGs, including heat shock proteins. A General Discussion in Chapter 5 led to the General Conclusions given in Chapter 6 that, in general, both species showed to be tolerant to the thermic stress applied. Remarkably, we found the upper thermal tolerance limit for N. lapillus over 28°C, showing a Temperature-dependent tendency in Predation (maximum at 19°C) and Reproductive output range (10-22°C, maxed at 16°C), both without statistical significance. The molecular response to thermal stress included 46 DEGs with homology to heat defensive biomarkers, namely heat shock proteins (Hsp70 and Hsp90) and other chaperone proteins at the maximum tested (28°C).