Molecular evolution and gene expression pattern of antioxidant enzymes of hypoxia-tolerant aquatic mammals

• Grant number: 22/01183-0
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: September 01, 2022
• End date: May 01, 2027
• Field of knowledge: Biological Sciences - Genetics - Animal Genetics
• Principal Investigator: Vera Nisaka Solferini
• Grantee: Giovanna Selleghin Veiga
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated scholarship(s): 23/09947-2 - Investigating gene expression patterns in aquatic mammal lineage cells under hypoxia and oxidative stress induced by reoxygenation, BE.EP.DD

Abstract

Cetaceans, pinnipeds, and sirenians are three independent lineages of mammals that occupied the aquatic environment, and consequently, they faced different selective pressures from the rest of the terrestrial mammalian lineages. For example, the amount of oxygen available is limited to how much the animal can carry in its blood and lungs during diving. Thus, the high control of vasoconstriction that allows the revascularization of priority tissues in the use of oxygen was one of the adaptations that allowed the evolution of the diving habit. However, this adaptation leads to ischemia of more peripheral tissues and reperfusion during return to the surface, when the animal restores the oxygen levels. During blood reperfusion, this abrupt increase in the oxygen supply activates pathways that produce toxic molecules called Reactive Oxygen Species (ROS), such as the O2- and H2O2. The system with antioxidant properties is responsible for removing these molecules in the cell, preventing oxidative damage, and maintaining homeostasis. This system has been identified in the groups of pinnipeds and cetaceans, with high activity of antioxidant enzymes, preventing tissue damage from occurring even in high amounts of ROS. However, little is known about the molecular characteristics of these genes in aquatic mammals and whether the expression patterns in this group differ from the rest of other mammals. In this context, the main objective of this project is to investigate the molecular evolution of antioxidant genes that may have contributed to the adaptation of aquatic mammals to situations of intense oxidative stress during diving. We will characterize the gene sequences and expression patterns of antioxidant genes between aquatic and terrestrial mammals using comparative genomics and transcriptome. The results will contribute to a broader understanding of genomic and possibly convergent evolution during the occupation of new environments. (AU)