The present study aimed at evaluating the cellular and transcriptomic responses induced by the probiotic candidate Vibrio lentus with gnotobiotic European sea bass (Dicentrarchus labrax, Linnaeus 1785) larvae. For this, a histomorphological analysis was performed using the terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) and the anti-proliferating cell nuclear antigen (PCNA) assay. In addition, a global transcriptomic approach was adopted to study the whole body mRNA changes upon administration of V. lentus by microarrays with the custom Agilent sea bass oligonucleotide-microarray v2.0 (4 × 44 K). Following V. lentus administration, the apoptotic and cell proliferative indexes did not show significant differences between treatments for hindgut nor for midgut. However, V. lentus treatment did significantly modify the gene expression related not only to cell proliferation and cell death, but also to cell adhesion, reactive oxygen species metabolism, iron transport, and immune response.
Our data represent the first global analysis of the effects of the probiotic candidate V. lentus on the gene expression profile in gnotobiotic European sea bass, and as such, provides a first delineation of the mechanisms by which this agent interacts with its host and exerts its beneficial effects.