title: Daily rhythms of clock gene expression and feeding behavior during the larval development in gilthead seabream, Sparus aurata.
abstract: Light is the main environmental time cue which synchronizes daily rhythms and the molecular clock of vertebrates. Indeed, alterations in photoperiod have profound physiological effects in fish (e.g. reproduction and early development). In order to identify the changes in clock genes expression in gilthead seabream larvae during ontogeny, three different photoperiods were tested: a regular 12L:12D cycle (LD), a continuous light 24L:0D (LL) and a two-phases photoperiod (LL + LD) in which the photoperiod changed from LL to LD on day 15 after hatching (dph). Larvae were sampled on 10, 18, 30 and 60 days post-hatch (dph) during a 24 h cycle. In addition to the expression of clock genes (clock, bmal1, cry1 and per3), food intake was measured. Under LD photoperiod, larvae feed intake and clock genes expression showed a rhythmic pattern with a strong light synchronization, with the acrophases occurring at the same hour in all tested ages. Under LL photoperiod, the larvae also showed a rhythmic pattern but the acrophases occurred at different times depending on the age, although at the end of the experiment (60 dph) clock genes expression and feed intake rhythms were similar to those larvae exposed to LD photoperiod. Moreover, the expression levels of bmal1 and cry1 were much lower than in LD photoperiod. Under the LL + LD photoperiod, the 10 dph larvae showed the same patterns as LL treatment while 18 and 30 dph larvae showed the same patterns as LD treatment. These results revealed the presence of internal factors driving rhythmic physiological responses during larvae development under constant environmental conditions. The LL + LD treatment demonstrates the plasticity of the clock genes expression and the strong effect of light as synchronizer in developing fish larvae.
authors: a Instituto de Ciencias Marinas de Andalucía (ICMAN-CSIC) , Puerto Real, Cádiz , Spain .
authors: José Antonio
authors: JA
authors: Mata-Sotres
authors: a Instituto de Ciencias Marinas de Andalucía (ICMAN-CSIC) , Puerto Real, Cádiz , Spain .
authors: Gonzalo
authors: G
authors: Martínez-Rodríguez
authors: b Nutrigenomics and Fish Growth Endocrinology Group, Institute of Aquaculture Torre de la Sal (IATS-CSIC) , Ribera de Cabanes, Castellón , Spain , and.
authors: Jaume
authors: J
authors: Pérez-Sánchez
authors: c Department of Physiology , University of Murcia, Regional Campus of International Excellence "Campus Mare Nostrum" , Murcia , Spain.
authors: F Javier
authors: FJ
authors: Sánchez-Vázquez
authors: a Instituto de Ciencias Marinas de Andalucía (ICMAN-CSIC) , Puerto Real, Cádiz , Spain .
authors: Manuel
authors: M
authors: Yúfera
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D057906:Circadian Clocks / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D015870:Gene Expression / Q000502:physiology*; D008027:Light; D009043:Motor Activity / Q000502:physiology; D017440:Photoperiod; D021541:Sea Bream / Q000254:growth & development; D013997:Time Factors
keywords: Clock genes; daily entrainment cycles; fish larvae; food intake; gilthead seabream; photoperiod