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Groups of zebrafish (Danio rerio) embryos receive radiations of different frequencies and intensities by means of new prototype devices. They are exposed to static (B0, 0 Hz), extremely low-frequency (ELF, 0.2 Hz), low-frequency (LF, 270 kHz), very-high-frequency (VHF, 100 MHz), and ultra-high-frequency (UHF, 900 MHz) field irradiations. The applied magnetic field intensities are 40 mT at 0 Hz, 40 mT at 0.2 Hz, 470 μT at 270 kHz, 240 nT at 100 MHz, and 240 nT at 900 MHz. Such combinations are meant to cover environmental radiations from geomagnetic fields and cosmic magnetism to electromagnetic radiation of electronic instruments such as GSM and UMTS transmission-mode mobile systems. For each frequency, fish are monitored for up to 5 days. Unexposed embryos are used as controls. Notably, exposure to the different radiations brings alterations of body pigmentation in zebrafish embryos and larvae in terms of total number, area, and morphology of (black) melanophores. This research may contribute to evaluating the roles and effects of magnetic radiation on living matter.

The dis(re)organization of the cytoskeletal actin in enterocytes mediates epithelial barrier dys(re)function, playing a key role in modulating epithelial monolayer’s integrity and remodeling under transition from physiological to pathological states. Here, by fluorescence-based morphological and morphometric analyses, we detected differential responses of cytoskeletal actin in intestinal epithelial Caco-2 cell monolayers at two different stages of their spontaneous differentiation, i.e., undifferentiated cells at 7 days post-seeding (dps) and differentiated enterocyte-like cells at 21 dps, upon challenge in vitro with the inflammation-mimicking stimulus of phorbol-12-myristate-13-acetate (PMA). In addition, specific responses were found in the presence of the natural dipeptide carnosine detecting its potential counteraction against PMA-induced cytoskeletal alterations and remodeling in differentiated Caco-2 monolayers. In such an experimental context, by both immunocytochemistry and Western blot assays in Caco-2 monolayers, we identified the expression of the allograft inflammatory factor 1 (AIF-1) as protein functionally related to both inflammatory and cytoskeletal pathways. In 21 dps monolayers, particularly, we detected variations of its intracellular localization associated with the inflammatory stimulus and its mRNA/protein increase associated with the differentiated 21 dps enterocyte-like monolayer compared to the undifferentiated cells.

Zebrafish (Danio rerio) is a well-established animal model, used in a number of research areas. In the last decade, it has also emerged as a tool to evaluate the effects of diets and dietary components and to test novel paradigms in nutrigenomics, nutrigenetics, and nutritional physiology. Despite its worldwide use, the standardization of the zebrafish rearing conditions, including daily nutritional and good feed management practices, is not yet achieved. This is surprising when compared with what is available for other reared animals, such as rodents or other (e.g., commercial) fishes. To date, a major applicative goal in zebrafish nutritional physiology research is to define common, standard, and reproducible protocols of rearing and feeding conditions to generate reliable and comparable results among research laboratories. This review aims to focus on limitations and disadvantages of the current rearing and feeding practices and on some recent technological solutions provided by research groups and/or biotech companies in the field of facility design, with emphasis on automated feeding distribution systems. A general overview of some common schemes of zebrafish husbandry is also given.

Food intake is a vital process that supplies necessary energy and essential nutrients to the body. Information regarding luminal composition in the gastrointestinal tract (GIT) collected through mechanical and nutrient sensing mechanisms are generally conveyed, in both mammals and fish, to the hypothalamic neurocircuits. In this context, ghrelin, the only known hormone with an orexigenic action, and the intestinal peptide transporters 1 and 2, involved in absorption of dietary di- and tripeptides, exert important and also integrated roles for the nutrient uptake. Together, both are potentially involved in signaling pathways that control food intake originating from different segments of the GIT. However, little is known about the role of different paralogs and their response to fasting. Therefore, after 3 weeks of acclimatization, 12 Atlantic salmon (Salmo salar) post-smolt were fasted for 4 days to explore the gastrointestinal response in comparison with fed control (n = 12). The analysis covered morphometric (weight, length, condition factor, and wet content/weight fish %), molecular (gene expression variations), and correlation analyses. Such short-term fasting is a common and recommended practice used prior to any handling in commercial culture of the species. There were no statistical differences in length and weight but a significant lower condition factor in the fasted group. Transcriptional analysis along the gastrointestinal segments revealed a tendency of downregulation for both paralogous genes slc15a1a and slc15a1b and with significant lowered levels in the pyloric ceca for slc15a1a and in the pyloric ceca and midgut for slc15a1b. No differences were found for slc15a2a and slc15a2b (except a higher expression of the fasted group in the anterior midgut), supporting different roles for slc15 paralogs. This represents the first report on the effects of fasting on slc15a2 expressed in GIT in teleosts. Transcriptional analysis of ghrelin splicing variants (ghrl-1 and ghrl-2) showed no difference between treatments. However, correlation analysis showed that the mRNA expression for all genes (restricted to segment with the highest levels) were affected by the residual luminal content. Overall, the results show minimal effects of 4 days of induced fasting in Atlantic salmon, suggesting that more time is needed to initiate a large GIT response.

Alamandine is a peptide of the Renin Angiotensin System (RAS), either generated from Angiotensin A via the Angiotensin Converting Enzyme 2 (ACE2), or directly from Ang-(1–7). In mammals, it elicits cardioprotection via Mas-related G-protein-coupled receptor D (MrgD), and the NOS/NO system. In teleost fish, RAS is known to modulate heart performance. However, no information is available on the presence of a cardioactive ACE2/Alamandine axis. To fill this gap, we used the cyprinid teleost Carassius auratus (goldfish) for in silico and in vitro analyses. Via the NCBI Blast P suite we found that in cyprinids ace2 is phylogenetically detectable in a subcluster of proteins including ace2-like isoforms, and is correlated with a hypoxia-dependent pathway. By real-time PCR, Western Blotting, and HPLC, ACE2 and Alamandine were identified in goldfish heart and plasma, respectively. Both increased after chronic exposure to low O2 (2.6 mg O2 L−1). By using an ex-vivo working goldfish-heart preparation, we observed that in vitro administration of exogenous Alamandine dose-dependently stimulates myocardial contractility starting from 10−11 M. The effect that involved Mas-related receptors and PKA occurred via the NOS/NO system. This was shown by exposing the perfused heart to the NOS inhibitor L-NMMA (10−5 M) that abolished the cardiac effect of Alamandine and was supported by the increased expression of the phosphorylated NOS enzyme in the extract from goldfish heart exposed to 10−10 M Alamandine. Our data are the first to show that an ACE2/Alamandine axis is present in the goldfish C. auratus and, to elicit cardiac modulation, requires the obligatory involvement of the NOS/NO system.