Cellular and transcriptomic response to treatment with the probiotic candidate Vibrio lentus in gnotobiotic sea bass (Dicentrarchus labrax) larvae.

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.

Fish as research tools: alternatives to in vivo experiments.

The use of fish in scientific research is increasing worldwide, due to both the rapid expansion of the fish farming industry and growing awareness of questions concerning the humane use of mammalian models in basic research and chemical testing. As fish are lower on the evolutionary scale than mammals, they are considered to be less sentient. Fish models are providing researchers, and those concerned with animal welfare, with opportunities for adhering to the Three Rs principles of refinement, reduction and replacement. However, it should be kept in mind that fish should also be covered by the principles of the Three Rs. Indeed, various studies have shown that fish are capable of nociception, and of experiencing pain in a manner analogous to that in mammals. Thus, emphasis needs to be placed on the development of alternatives that replace, as much as possible, the use of all living vertebrate animals, including fish. This review gives the first comprehensive and critical overview of the existing alternatives for live fish experimental studies. The alternative methods described range from cell and tissue cultures, organ and perfusion models, and embryonic models, to in silico computer and mathematical models. This article aspires to guide scientists in the adoption of the correct alternative methods in their research, and, whenever possible, to reduce the use of live fish.