Chiara Carla Piccinetti

Appetite regulation: The central role of melatonin in Danio rerio

Melatonin is the hormonal mediator of photoperiodic information to the central nervous system in vertebrates and allows the regulation of energy homeostasis through the establishment of a proper balance between energy intake and energy expenditure. The aim of this study was to evaluate the role of melatonin in appetite central control analyzing the involvement of this hormone in the regulation of feeding behavior in the zebrafish Danio rerio. For this purpose, the effect of two different melatonin doses (100nM and 1μM) administered for 10 days, via water, to zebrafish adults was evaluated at both physiological and molecular level and the effect of melatonin was considered in relation to the most prominent systems involved in appetite regulation. For the first time, in fact, melatonin control of food intake by the modulation of leptin, MC4R, ghrelin, NPY and CB1 gene expression was evaluated. The results obtained indicate that melatonin significantly reduces food intake and the reduction is in agreement with the changes observed at molecular level. A significant increase in genes codifying for molecules involved in feeding inhibition, such as leptin and MC4R, and a significant reduction in the major orexigenic signals including ghrelin, NPY and CB1 are showed here. Taken together these results support the idea that melatonin falls fully into the complex network of signals that regulate food intake thus playing a key role in central appetite regulation.

BPA-Induced Deregulation Of Epigenetic Patterns: Effects On Female Zebrafish Reproduction

Bisphenol A (BPA) is one of the commonest Endocrine Disruptor Compounds worldwide. It interferes with vertebrate reproduction, possibly by inducing deregulation of epigenetic mechanisms. To determine its effects on female reproductive physiology and investigate whether changes in the expression levels of genes related to reproduction are caused by histone modifications, BPA concentrations consistent with environmental exposure were administered to zebrafish for three weeks. Effects on oocyte growth and maturation, autophagy and apoptosis processes, histone modifications, and DNA methylation were assessed by Real-Time PCR (qPCR), histology, and chromatin immunoprecipitation combined with qPCR analysis (ChIP-qPCR). The results showed that 5 μg/L BPA down-regulated oocyte maturation-promoting signals, likely through changes in the chromatin structure mediated by histone modifications, and promoted apoptosis in mature follicles. These data indicate that the negative effects of BPA on the female reproductive system may be due to its upstream ability to deregulate epigenetic mechanism.

Perspectives on endocrine disruptor effects on metabolic sensors.

Endocrine disrupting (EDs) chemicals can increase or block the metabolism of endogenous peptidergic or steroid hormones by activating or antagonizing nuclear receptors in the hypothalamus, besides adipose tissue, liver and gonads. Toxicological and epidemiological studies have suggested the involvement of different EDs in an increasing number of metabolic disorders such as obesity and diabetes. The aim of this review is to summarize the literature from experimental animal studies demonstrating the impairment of body weight raised by the deregulation of peptidergic signals as well as by the activation of key metabolic molecular targets. Regarding the modification of gene transcription levels induced by EDs, new data on DEHP effect on food intake and lipid metabolism in the experimental model zebrafish (Danio rerio) have also been included in this review providing evidences about the dangerousness of DEHP low doses.

Anandamide and AM251, via water, modulate food intake at central and peripheral level in fish.

The endocannabinoid system is a major regulator of food intake in many animal species. Studies conducted so far have mostly focused on mammals, and, therefore, in this study, the role of the endocannabinoid system in food intake in the sea bream Sparus aurata was investigated. The effect of different doses of the endocannabinoid anandamide (AEA), administered via water, was evaluated after different exposure times (30, 60 and 120 min) at both physiological and molecular levels. The results obtained indicate that fish exposed to AEA via water present approximately 1000-fold higher levels of AEA in both the brain and liver, which correlated with a significant increase in food intake and with the elevation of cannabinoid receptor 1 (CB(1)) and neuropeptide Y (NPY) mRNA levels in the brain. A peripheral effect of AEA was also observed, since a time-dependent increase in hepatic CB(1) mRNA and protein levels was detected. These effects were attenuated by the administration, again via water, of a selective cannabinoid CB(1) receptor antagonist (AM251). These findings indicate that the endocannabinoid AEA, at doses that stimulate food intake in fish, concomitantly stimulates the expression of the orexigenic peptide NPY as well that of its own receptor, thereby potentially enhancing its effect on food consumption. In agreement with a role of AEA in food intake in S. aurata, we found increased brain levels of both this and the other endocannabinoid, 2-arachidonoylglycerol (2-AG), following food deprivation.

Malnutrition may affect common sole (Solea solea L.) growth, pigmentation and stress response: Molecular, biochemical and histological implications

In the last decades there have been several evidences that traditionally used live preys like rotifers and Artemia salina have nutritional deficiencies that result in a general decrease of fish health, causing anomalies in the development, in growth and in pigmentation. In this study a partial of total replacement of traditional live preys with preserved copepods that represent the natural food of the larvae was evaluated during Solea solea culture. In this study a positive effect of co-feeding preserved copepods in sole larviculture was observed since larvae fed this diet growth and survived better, showed a better tolerance to captive conditions and had a better response to the final thermal/density stress-test with respect to larvae fed a traditional diet. Morphometric data were fully supported by molecular and biochemical ones. Moreover, liver histological investigations, revealed that the inclusion of preserved copepods in the larval diet was able to improve lipid assimilation. In conclusion, preserved copepods may be considered a suitable food for sole when used as a supplement to the traditional diet based on rotifers and Artemia nauplii.

Effects of BPA on female reproductive function: The involvement of epigenetic mechanism.

Epigenetic modifications are classified as heritable and reversible chemical modifications of chromatin that do not cause changes in DNA sequence. Changes in epigenetic modifications can be caused by exposure to certain environmental factors, such as contaminants like bisphenol A (BPA). Bisphenol A is ubiquitous in the environment and produced in large quantities, and known to have hormone-like activity, whereby disrupting endocrine function. Because of evidence for disruption of sex steroid mediated pathways, there is a concern that BPA could have adverse effects on female reproduction. The purpose of this review is to summarize the effects of BPA on adult female reproduction with focus on epigenetic changes that can be heritable.

Melatonin and peripheral circuitries: insights on appetite and metabolism in Danio rerio.

Melatonin is a neuroendocrine transducer of circadian/circannual rhythms able to synchronize organisms physiological activity. On the basis of our recent findings on appetite regulation by melatonin in the zebrafish brain, the aim of this study was to evaluate melatonins role in peripheral circuitries regulating food intake, growth, and lipid metabolism. For this purpose, the effect of two melatonin doses (100 nM and 1 μM) administered for 10 days, via water, to adult zebrafish was evaluated at both physiological and molecular levels. The major signals controlling energy homeostasis were analyzed together. Additionally, the effect of melatonin doses on muscle metabolic resources was evaluated. The results obtained indicate that melatonin reduces food intake by stimulating molecules involved in appetite inhibition, such as leptin (LPT), in the liver and intestine and MC4R, a melanocortin system receptor, in the liver. Moreover, melatonin decreases hepatic insulin-like growth factor-I (IGF-I) gene expression, involved in growth process and other signals involved in lipid metabolism such as proliferator-activated receptors (PPARα, β, and γ) and sterol regulatory element-binding protein (SREBP). These results were correlated with lower levels of lipids in the muscles as evidenced by the macromolecular pools analyses. The findings obtained in this study could be of great interest for a better understanding of the molecular mechanisms as the basis of food intake control and, in turn, can be a useful tool for medical and aquaculture applications.

Marine ornamental species culture: From the past to “Finding Dory”

The present article revises the major topics related to fish and coral reproduction. In particular after a short review of the ornamental trade and the destructive fishing methods that are still used in some areas, the present review revises the principal modes of fish and coral reproduction introducing the main critical bottlenecks in their captive propagation. Regarding fish these include sexing the fish, pair forming, the embryo development, the hatching process and of course the transition from an endogenous to an exogenous feeding by the larvae. As concerns corals, great attention is given to the main modes of reproduction as well as to nutrition and lightening.

Herbivory in the soft coral Sinularia flexibilis (Alcyoniidae)

Our work provides strong support for the hypothesis that Sinularia flexibilis ingests diatoms such as Thalassiosira pseudonana. We assessed algal ingestion by S. flexibilis through estimates of algal removal, histological analyses, scanning electron microscopy observations, and gene expression determination (18S and silicon transporter 1) by real time PCR. Cell counts are strongly suggestive of algal removal by the coral; light and scanning microscopy provide qualitative evidence for the ingestion of T. pseudonana by S. flexibilis, while molecular markers did not prove to be sufficiently selective/specific to give clear results. We thus propose that previous instances of inability of corals to ingest algae are reconsidered using different technical approach, before concluding that coral herbivory is not a general feature.

Measurement of the 100 MHz EMF radiation in vivo effects on zebrafish D. rerio embryonic development: A multidisciplinary study

The augmented exposure of both environment and human being to electromagnetic waves and the concomitant lack of an unequivocal knowledge about biological consequences of these radiations, raised public interest on electromagnetic pollution. In this context, the present study aims to evaluate the biological effects on zebrafish (ZF) embryos of 100 MHz radiofrequency electromagnetic field (RF-EMF) exposure through a multidisciplinary protocol. Because of the shared synteny between human and ZF genomes that validated its use in biomedical research, toxicology and developmental biology studies, ZF was here selected as experimental model and a measurement protocol and biological analyses have been set up to clearly discriminate between RF-EMF biological and thermal effects. The results showed that a 100 MHz EMF was able to affect ZF embryonic development, from 24 to 72 h post fertilization (hpf) in all the analyzed pathways. Particularly, at the 48 hpf stage, a reduced growth, an increased transcription of oxidative stress genes, the onset of apoptotic/autophagic processes and a modification in cholesterol metabolism were detected. ZF embryos faced stress induced by EMF radiation by triggering detoxification mechanisms and at 72 hpf they partially recovered from stress reaching the hatching time in a comparable way respect to the control group. Data here obtained showed unequivocally the in vivo effects of RF-EMF on an animal model, excluding thermal outcomes and thus represents the starting point for more comprehensive studies on dose response effects of electromagnetic fields radiations consequences.