Ontogeny of daily rhythms in the expression of metabolic factors in Nile tilapia (Oreochromis niloticus) kept at two different temperature regimes: Thermocycle and constant temperature

• Published in: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology Vol. 296; p. 111687
• Main Authors: do Espírito Santo, Amanda Hastenreiter, López-Olmeda, José Fernando, de Alba, Gonzalo, Costa, Leandro Santos, de Oliveira Guilherme, Helder, Sánchez-Vázquez, Francisco Javier, Luz, Ronald Kennedy, Ribeiro, Paula Adriane Perez
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.2024
• Subjects: Biological clock; Gene expression; Larviculture; Metabolic physiology; Biological clock; Gene expression; Metabolic physiology; Larviculture
• ISSN: 1095-6433; 1531-4332; 1531-4332
• DOI: 10.1016/j.cbpa.2024.111687

The daily variations of temperature are one of the main synchronizers of the circadian rhythms. In addition, water temperature influences the embryonic and larval development of fish and directly affects their metabolic processes. The application of thermocycles to fish larvae has been reported to improve growth and the maturation of the digestive system, but their effects on metabolism are poorly understood. The aim of the present study was to evaluate the effect of two different temperature regimes, cycling versus constant, on the daily rhythms of metabolic factors of Nile tilapia (Oreochromis niloticus) larvae. For this purpose, fertilized eggs were divided into two groups: one reared in a 31 °C:25 °C day:night thermocycle (TCY) and another group maintained in a constant 28 °C temperature (CTE). The photoperiod was set to a 12:12 h light/dark cycle. Samples were collected every 4 h during a 24-h cycle on days 4, 8 and 13 post fertilization (dpf). The expression levels of alanine aminotransferase (alt), aspartate aminotransferase (ast), malic enzyme, glucose-6-phosphate dehydrogenase (g6pd), phosphofructokinase (pfk) and pyruvate kinase (pk) were analyzed by qPCR. Results showed that, in 13 dpf animals, most of the genes analyzed (alt, ast, malic, g6pd and pfk) showed daily rhythms in TCY, but not in the group kept at constant temperature, with most acrophases detected during the feeding period. An increase in nutrient metabolism around feeding time can improve food utilization and thus increase larval performance. Therefore, the use of thermocycles is recommended for tilapia larviculture. [Display omitted] •Temperature cycles are crucial for optimizing developmental physiology and metabolism in Nile tilapia larvae.•Tilapia larvae of 13 dpf showed daily rhythms in the gene expression of several metabolic enzymes.•Rearing larvae under thermocycles seemed to elicit a higher number of rhythmic factors than constant water temperature.•Metabolic rhythms can anticipate the time of feeding, improving the efficiency of nutrient utilization