Molecular Ontogeny of First-Feeding European Eel Larvae

• Published in: Frontiers in Physiology
• Main Authors: Politis, Sebastian N., Sorensen, Sune R., Mazurais, David, Servili, Arianna, Zambonino-Infante, Jose-Luis, Miest, Joanna J., Clemmesen, Catriona M., Tomkiewicz, Jonna, Butts, Ian A. E.
• Other Authors: DTU Aqua, National Institute of Aquatic Resources, Danmarks Tekniske Universitet = Technical University of Denmark (DTU), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Helmholtz Centre for Ocean Research Kiel (GEOMAR), University of Greenwich
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: ACL; Digestion; Aquaculture; digestive enzymes; japanese eel; ingestion; dicentrarchus-labrax; gene-expression; anguilla-japonica; Anguilla anguilla; Gene Expression; glass-eels; leptocephalus larvae; nucleic-acid; RNA/DNA; rna/dna ratios; sea bass larvae; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; Rotifer
• Online Access: https://hal.science/hal-02640326; https://hal.science/hal-02640326/document; https://hal.science/hal-02640326/file/Politis_etal_FPhys_2018.pdf; https://doi.org/10.3389/fphys.2018.01477

WOS:000448007700001 International audience Digestive system functionality of fish larvae relies on the onset of genetically pre-programmed and extrinsically influenced digestive functions. This study explored how algal supplementation (green-water) until 14 days post hatch (dph) and the ingestion of food [enriched rotifer (Brachionus plicatilis) paste] from 15 dph onward affects molecular maturation and functionality of European eel larval ingestion and digestion mechanisms. For this, we linked larval biometrics to expression of genes relating to appetite [ghrelin (ghrl), cholecystokinin (cck)], food intake [proopiomelanocortin (pomc)], digestion [trypsin (try), triglyceride lipase (tgl), amylase (amyl)], energy metabolism [ATP synthase F0 subunit 6 (atp6), cytochrome-c-oxidase 1 (cox1)], growth [insulin-like growth factor (igf1)] and thyroid metabolism [thyroid hormone receptors (thr alpha A, thr beta B)]. Additionally, we estimated larval nutritional status via nucleic acid analysis during transition from endogenous and throughout the exogenous feeding stage. Results showed increased expression of ghrl and cck on 12 dph, marking the beginning of the first-feeding window, but no benefit of larviculture in green-water was observed. Moreover, expression of genes relating to protein (try) and lipid (tgl) hydrolysis revealed essential digestive processes occurring from 14 to 20 dph. On 16 dph, a molecular response to initiation of exogenous feeding was observed in the expression patterns of pomc, atp6, cox1, igf1, thr alpha A and thr beta B. Additionally, we detected increased DNA contents, which coincided with increased RNA contents and greater body area, reflecting growth in feeding compared to non-feeding larvae. Thus, the here applied nutritional regime facilitated a short-term benefit, where feeding larvae were able to sustain growth and better condition than their non-feeding conspecifics. However, RNA:DNA ratios decreased from 12 dph onward, indicating a generally low larval nutritional condition, ...