Expressão de genes de crescimento, reprodução e resposta imune em tilápia-do-Nilo (Oreochromis niloticus) cultivadas em Tecnologia de Bioflocos (BFT)

Abstract

Biofloc technology (BFT) has emerged as a sustainable alternative in fish farming, reducing the need for water renewal and providing high-quality nutrients through microbial activity. However, information is lacking regarding the effect of this complex ecosystem on the expression of genes related to productive and reproductive performance and the immune system. Therefore, the objective of this study was to evaluate the expression of genes related to growth, such as insulin-like growth factor 1 (IGF-1), reproduction such as follicle-stimulating (FSH), luteinizing (LH) and their receptors (LH, FSH, LHR, FSHR, VTG) and immune response, lysozyme type C, interleukin-1, interleukin-8, tumor necrosis factor receptor 1 and lymphotoxin alpha (LYS, IL-1β, IL-8, TNF-β and LT) in Nile tilapia (Oreochromis niloticus) kept in a BFT system, compared to a conventional partial water exchange (TPA) system. The experimental units were polyethylene tanks with a total capacity of 1,000 L and a useful volume of 800 L (n = 10), under two different culture systems: TPA (n = 5) and BFT (n = 5). A total of two fish per aquarium (n=10), one male and one female, were slaughtered for tissue collection: liver, kidney, spleen, testis, pituitary gland, and ovary. At the end of the experimental period, biological samples were collected, stored, and molecular analyses were performed. Gene expression analysis by RT-qPCR demonstrated that the BFT system significantly increased the expression of the LH, FSHR, and VTG genes in females, suggesting greater stimulation of ovarian maturation. The IGF-1β gene showed greater expression in males, indicating a greater potential anabolic effect. In the immune system, only the LYS gene was significantly more expressed in BFT females, indicating possible activation of the innate immune response. The other immune genes showed no significant differences between treatments. The results indicate that BFT exerts a positive influence on the molecular modulation of essential physiological processes, with distinct effects between sexes, reinforcing its potential as a tool for improving tilapia production in sustainable systems.