1. 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.
- Author
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do Espírito Santo AH, López-Olmeda JF, de Alba G, Costa LS, de Oliveira Guilherme H, Sánchez-Vázquez FJ, Luz RK, and Ribeiro PAP
- Subjects
- Animals, Larva growth & development, Larva metabolism, Photoperiod, Glucosephosphate Dehydrogenase metabolism, Glucosephosphate Dehydrogenase genetics, Aspartate Aminotransferases metabolism, Alanine Transaminase metabolism, Temperature, Cichlids growth & development, Cichlids metabolism, Cichlids physiology, Cichlids genetics, Circadian Rhythm physiology
- Abstract
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., Competing Interests: Declaration of competing interest The authors whose names are listed immediately below certify that they have NO affi liations with or involvement in any organization or entity with any fi nancial interest (such as honoraria; educational grants; participation in speakers' bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-fi nancial interest (such as personal or professional relationships, affi liations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript., (Copyright © 2024 Elsevier Inc. All rights reserved.)
- Published
- 2024
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