O efeito da dieta na sobrevivência e no desenvolvimento esquelético e digestivo de larvas e juvenis de peixe-zebra Danio rerio (Hamilton, 1822)

Silva, João Pedro Gonçalves Cardeira da

http://hdl.handle.net/10400.1/672

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Authors

Silva, João Pedro Gonçalves Cardeira da

Advisor(s)

Cancela, Leonor

Gavaia, Paulo J.

Abstract(s)

Zebrafish is a freshwater teleost which, due to several biological and genetic characters, has been widely used as a vertebrate model in a variety of research fields, with great potential in molecular biology. As a consequence of the increasing interest in zebrafish, the optimization of its rearing conditions becomes essential, such as the determination of a standardized feeding regime appropriate to this species’. Four different dietary regimes, composed of rotifers Brachionus sp., Artemia nauplii and inert food (Cyclop-eezeTM e BeneluxNV), were carried out. The effect of diet in zebrafish larvae and juvenile fish was evaluated by the determination of the survival and growth parameters as well as by the analysis of the development at the tissue, cellular and molecular levels in three distinct developmental stages. For that, histological, gene expression and immunohistochemical tools applied to molecular markers of the skeletal development (matrix Gla protein – mgp – and osteocalcin – oc) and digestive tract development (amylase and trypsin) were used. The assessment of bone remodeling regions and a histological analysis of the digestive system were also carried out. The obtained data suggest that rotifers are not appropriate for the larval requirements of this species, presenting the lowest survival and growth values. These data were also supported at the molecular level. Artemia nauplii and a weaning to inert food at 15 days post fertilization does not seem to be, also, an appropriate feeding regime. Comparatively, a diet composed exclusively by Artemia nauplii presented higher development-related parameters. These data suggest that this is a suitable food regime, as it has been argued by several authors. A daily mixture of foods also seems to be suitable to zebrafish healthy development. This work showed that, in zebrafish early development Artemia nauplii should used as food and could be, possibly, supplemented with other foods to obtain better results.