Characterisation of Phase I genes from invertebrate detoxification mechanisms: The Mytilus sp. case-study

• Autor(a) principal: Vitorino, João Daniel Brás
• Data de Publicação: 2023
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/163524
• topic: Mussel; Phase I; Detoxification; Sequencing; Biomarkers; B[α]P; Domínio/Área Científica::Engenharia e Tecnologia::Outras Engenharias e Tecnologias

In vertebrates, Cytochrome P450 Family 1 (CYP1) of mixed-function oxidases plays a crucial function in the detoxification of numerous polycyclic aromatic hydrocarbons (PAHs). However, despite cytochromes being relatively well-conserved among eukaryotes, the role of CYPs and other enzymes involved in phase I of detoxification remains obscure and often a matter of controversy. In the case of invertebrates, there have been efforts to characterise the gene and the expression products in organisms pertinent to biomonitoring and toxicity testing proce-dures. The existence of functional homologues in aquatic invertebrates is not universally ac-cepted, particularly in bivalve molluscs, which serve as one of the most significant models for aquatic toxicologists. This thesis aims to contribute to the investigation of phase I detoxification mechanisms in the mussel Mytilus sp. as model, by isolating full coding sequences of CYP1A-Like and Epoxide Hydrolase 4; study the expression of CYP1A-Like and EH4 under toxicolog-ical challenge by B[α]P and associate gene expression with biomarkers and histopathology to determinate B[α]P effects. Following the isolation and sequencing of a CYP1A-like mRNA from Mytilus sp., phylogenetic analyses revealed a similarity to sequences belonging to both the CYP1 and 2 Families. Histology revealed that specimens had Increased histopathological in-juries with increased B[α]P concentrations. When subjected to lower B[α]P concentrations, biomarker activity levels were normal, but their activity decreased when exposed to higher concentrations. When exposed to lower B[α]P concentrations, CYP expression was normal, whereas expression had tendency to diminish when exposed to higher concentrations. This may indicate that either B[α]P in higher concentrations inhibits detoxification mechanisms or that other CYPs may be responsible for detoxification.