The activity of ion channels and transporters generates ion-specific fluxes that encode electrical and/or chemical signals with biological significance. Even though it is long known that some of those signals are crucial for regeneration, only in recent years the corresponding molecular sources started to be identified using mainly invertebrate or larval vertebrate models. We used adult zebrafish caudal fin as a model to investigate which and how ion transporters affect regeneration in an adult vertebrate model. Through the combined use of biophysical and molecular approaches, we show that V-ATPase activity contributes to a regeneration-specific H+ ef`flux. The onset and intensity of both V-ATPase expression and H+ efflux correlate with the different regeneration rate along the proximal-distal axis. Moreover, we show that V-ATPase inhibition impairs regeneration in adult vertebrate. Notably, the activity of this H+ pump is necessary for aldh1a2 and mkp3 expression, blastema cell proliferation and fin innervation. To the best of our knowledge, this is the first report on the role of V-ATPase during adult vertebrate regeneration.

Zebrafish is already one of the most used model organisms in biomedical sciences and other research fields. It is therefore becoming increasingly important to assure that zebrafish maintained in laboratory aquaculture conditions are raised and housed under rigorous standards that promote health and welfare to guarantee the required quality and reproducibility of research data. Specifying the programs each facility is adopting would be the first step to achieve this by allowing other facilities to compare, improve, and discuss their protocols and fish performance. We provide in this article a detailed description of an integrated facility health management program, with protocols and readouts, fully designed and aimed at maximizing fish health, welfare, and performance for research.

Zebrafish are able to regenerate the spinal cord and recover motor and sensory functions upon severe injury, through the activation of cells located at the ependymal canal. Here, we show that cells surrounding the ependymal canal in the adult zebrafish spinal cord express Foxj1a. We demonstrate that ependymal cells express Foxj1a from their birth in the embryonic neural tube and that Foxj1a activity is required for the final positioning of the ependymal canal. We also show that in response to spinal cord injury, Foxj1a ependymal cells actively proliferate and contribute to the restoration of the spinal cord structure. Finally, this study reveals that Foxj1a expression in the injured spinal cord is regulated by regulatory elements activated during regeneration. These data establish Foxj1a as a pan-ependymal marker in development, homeostasis and regeneration and may help identify the signals that enable this progenitor population to replace lost cells after spinal cord injury.

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Zebrafish (Danio rerio) is one of the top model organisms used in biomedical research. Therefore, it is fundamental that zebrafish facilities continuously improve husbandry methods to provide fish with the best physiological and welfare conditions that suit each experimental purpose. Nutrition is a husbandry aspect that needs further optimization, as it greatly affects growth, reproduction, health and behaviour. Here, we have compared the impact of different feeding regimens on zebrafish survival, growth and reproductive performance. Mutant and wild-type zebrafish were raised using several combinations of two cold-extruded processed feeds—Skretting®GemmaMicro and Sparos®Zebrafeed—and one live feed (rotifers). Zebrafeed® outperformed GemmaMicro® in terms of survival rate, and embryo viability was also higher when the spawners were fed with Zebrafeed® either from larval stage or upon sexual maturation. In contrast, GemmaMicro® favoured growth, both in size and weight. The use of rotifers until 60 days post-fertilization improved survival of fish co-fed with GemmaMicro®, while delaying their growth. Zebrafeed® performance was not affected by co-feeding rotifers. Overall, we showed that different nutritional formulas affect physiological parameters, allowing for the establishment of feeding protocols adapted to the objectives of each facility. At the same time, we validated Skretting®GemmaMicro and Sparos®Zebrafeed as two commercially available feeds that are well suited for zebrafish nutrition in a laboratory environment.

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spinal cord. The level of adult neurogenesis in vertebrates seems to correspond to the plasticity of the brain. In zebrafish many distinct constitutive proliferation zones have been described along the whole anterior-posterior axis of the brain [Grandel et al. Dev. Biol. 295 (2006) 263-277].The cns of teleosts has an enormous capacity to regenerate after brain incisions or removal of whole brain parts, as well as after transection of the spinal cord. Neural regeneration has been demonstrated in several teleost species suggesting that it is a common feature of teleost fishes in general [Kaslin et al. Philos. Trans. R Soc. Lond. B Biol. Sci. 363 (2008) 101-122]. To investigate regenerative processes in the cns of adult zebrafish we have established a stab-wound lesion paradigm in the telencephalon. The temporal course of regenerative events was analyzed. After lesion a marked increase in proliferation was detected in the constitutive proliferation zones, as well as ectopic proliferation proximal to the lesion. We are currently analyzing the identity and proliferative properties of cells contributing to regeneration using BrdU to specifically label cycling cells combined with immunohistological detection of neuronal and glial marker proteins.