Micro- and nano-plastic (MP/NP) pollution represents a threat not only to marine organisms and ecosystems, but also a danger for humans. The effects of these small particles resulting from the fragmentation of waste of various types have been well documented in mammals, although the consequences of acute and chronic exposure are not fully known yet. In this review, we summarize the recent results related to effects of MPs/NPs in different species of fish, both saltwater and freshwater, including zebrafish, used as model organisms for the evaluation of human health risk posed by MNPs. The expectation is that discoveries made in the model will provide insight regarding the risks of plastic particle toxicity to human health, with a focus on the effect of long-term exposure at different levels of biological complexity in various tissues and organs, including the brain. The current scientific evidence shows that plastic particle toxicity depends not only on factors such as particle size, concentration, exposure time, shape, and polymer type, but also on co-factors, which make the issue extremely complex. We describe and discuss the possible entry pathways of these particles into the fish body, as well as their uptake mechanisms and bioaccumulation in different organs and the role of blood response (hematochemical and hematological parameters) as biomarkers of micro- and nano-plastic water pollution.

Background: Obesity is a pathological condition that has reached epidemic proportions; hence, it is necessary to find novel strategies aimed at fighting this disease. The present study was designed to evaluate the effect of a flavonoid-rich extract of orange (Citrus sinensis) juice (OJe) in diet-induced obese zebrafish. Methods: Adult zebrafish were divided into four diet groups: (i) normally fed (NF); (ii) overfed (OF); (iii) NF supplemented with OJe (5 mL/L in fish water; NF + OJe); and (iv) OF supplemented with OJe (OF + OJe). Each week, body weight (BW) and body mass index (BMI) were measured, and, at the end of the fifth week, euthanized zebrafish were processed for both microscopic evaluations and qPCR analyses. Results: In OF zebrafish, OJe significantly decreased both BW and BMI values and lowered the visceral adipose tissue, while it had little effect in the NF group. Moreover, it significantly reduced adipocyte cell size in both NF and OF groups in both visceral and subcutaneous adipose tissues, as well as their number in OF fish. Finally, OJe modulated some obesity-related genes, such as leptin A, ghrelin, orexin, pro-opiomelanocortin (POMC), and neuropeptide Y (NPY), in both gut and brain. Conclusion: This study adds new insights into the anti-obesity properties of orange juice and its flavonoids, suggesting their role as weight management agents through a lipolytic action linked to a restoration of metabolism-regulating gene expression.

A caloric surplus and a sedentary lifestyle are undoubtedly known to be the leading causes of obesity. Natural products represent valuable allies to face this problematic issue. This study was planned to assess the effect of a white grape (Vitis vinifera) juice extract (WGJe) in diet-induced obese zebrafish (Danio rerio). Fish were divided into four different diet groups: (i) normally fed (NF); (ii) overfed (OF); (iii) WGJe-supplemented NF (5 mL/L in fish water); (iv) WGJe-supplemented OF. Body mass index (BMI) was extrapolated each week. After the fourth week, euthanized zebrafish were processed for both microscopic evaluations and gene expression analyses. OF zebrafish showed higher BMI values with respect to NF counterparts, an effect that was hindered by WGJe treatment. Moreover, histological analyses showed that the area of the adipose tissue, as well as the number, size, and density of adipocytes was significantly higher in OF fish. On the other hand, WGJe was able to avoid these outcomes both at the subcutaneous and visceral levels, albeit to different extents. At the gene level, WGJe restored the altered levels of ghrelin and leptin of OF fish both in gut and brain. Overall, our results support the anti-obesity property of WGJe, suggesting its potential role in weight management.

The amphibious teleost Giant mudskipper (Periophthalmodon schlosseri, Pallas 1770) inhabit muddy plains and Asian mangrove forests. It spends more than 90% of its life outside of the water, using its skin, gills, and buccal-pharyngeal cavity mucosa to breathe in oxygen from the surrounding air. All vertebrates have been found to have mast cells (MCs), which are part of the innate immune system. These cells are mostly found in the mucous membranes of the organs that come in contact with the outside environment. According to their morphology, MCs have distinctive cytoplasmic granules that are released during the degranulation process. Additionally, these cells have antimicrobial peptides (AMPs) that fight a variety of infections. Piscidins, hepcidins, defensins, cathelicidins, and histonic peptides are examples of fish AMPs. Confocal microscopy was used in this study to assess Piscidin1 expression in Giant Mudskipper branchial MCs. Our results demonstrated the presence of MCs in the gills is highly positive for Piscidin1. Additionally, colocalized MCs labeled with TLR2/5-HT and Piscidin1/5-HT supported our data. The expression of Piscidin1 in giant mudskipper MCs highlights the involvement of this peptide in the orchestration of teleost immunity, advancing the knowledge of the defense system of this fish.

Although the postmortem interval estimation still represents one of the main goals of forensic medicine, there are still several limitations that weigh on the methods most used for its determination: for this reason, even today, precisely estimating the postmortem interval remains one of the most important challenges in the forensic pathology field. To try to overcome these limitations, in recent years, numerous studies have been conducted on the potential use of the mRNA degradation time for reaching a more precise post mortem interval (PMI) estimation. An evidence-based systematic review of the literature has been conducted to evaluate the state of the art of the knowledge focusing on the potential correlation between mRNA degradation and PMI estimation. The research has been performed using the electronic databases PubMed and Scopus. The analysis conducted made it possible to confirm the potential applicability of mRNA for reaching a more precise PMI estimation. The analysis of the results highlighted the usefulness of some mRNAs, such as β-actin and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA, especially in short time frames, within a few hours or days of death. The matrices on which these analyses were conducted were also analyzed, resulting in less exposure to the external environment, including the heart, brain, and dental pulp. The major limitations were also reported, including the short time intervals analyzed in most of the articles, the lack of mathematical models, and the failure to report the error rate between the mRNA degradation time and PMI. Given the still small number of published articles, the lack of globally recognized standardized methods, and the numerous techniques used to evaluate the mRNA degradation times, numerous and larger studies are still necessary to reach more solid and shared evidence.

Obesity is a pathological condition, defined as an excessive accumulation of fat, primarily caused by an energy imbalance. The storage of excess energy in the form of triglycerides within the adipocyte leads to lipotoxicity and promotes the phenotypic switch in the M1/M2 macrophage. These changes induce the development of a chronic state of low-grade inflammation, subsequently generating obesity-related complications, commonly known as metabolic syndromes. Over the past decade, obesity has been studied in many animal models. However, due to its competitive aspects and unique characteristics, the use of zebrafish has begun to gain traction in experimental obesity research. To counteract obesity and its related comorbidities, several natural substances have been studied. One of those natural substances reported to have substantial biological effects on obesity are flavonoids. This review summarizes the results of studies that examined the effects of flavonoids on obesity and related diseases and the emergence of zebrafish as a model of diet-induced obesity.