Identificação e análise de polimorfismo em genes relacionados ao estresse oxidativo em tambaqui (Colossoma macropomum)

Abstract

Aerobic organisms need an effective defense system against reactive oxygen species (ROS) to survive in oxygen-rich environments. Although physiological concentrations of ROS in aerobic organisms are beneficial and involve cell signaling pathways and survival of invading pathogens, an elevated and unbalanced concentration of ROS can contribute to disease development. When ROS production exceeds the body's ability to eliminate these reactive species using antioxidants, oxidative stress occurs. To protect against damaging ROS, the aerobic organisms have developed a system to prevent or repair the effects of oxidative stress, and these can be enzymatic or non-enzymatic molecules. Like all other organisms, aquatic animals must balance ROS production and antioxidant defenses. The study of the mechanisms controlling oxidative stress in fish is of particular interest because these organisms are exposed to many stressors, such as temperature variations, osmotic stress, changes in oxygen availability, pollution, and other anthropogenic impacts, which can directly affect their oxidative balance. The tambaqui, Colossoma macropomum, is a migratory species native to the Amazon and Orinoco River basins. It has good adaptation to aquaculture, a high growth rate, tolerance to low water quality, and excellent market acceptance, and these characteristics have facilitated its introduction into several Brazilian regions. The diversification of the cultural environments has created a promising scenario for increased selective pressure on genes related to the oxidative stress response. A total of 146,743 SNPs were obtained and aligned with BLAST, generating 311 genotype alignments in 229 animals, with DNA sequences related to genes involved in the oxidative stress response process. After applying the allele frequency filter (MAF) greater than 0.05 and sample and marker recall rate > 80%, 169 genotyped markers remained in 211 animals. The 169 sequences allowed alignment with 56 genes from 40 different species for 224 alignments. We identified variation in important oxidative stress response genes in fish. The evaluation of the genetic response of tambaqui to the selective pressures suffered by populations bred in different regions of Brazil helps us understand this species's ability to adapt to stressors that may impair its production.