Parental exposure to waterborne selenite induces transgenerational development toxicity in zebrafish offspring

Selenium Nanoparticles vs Selenite Fertilizers: Implications for Toxicological Profiles, Antioxidant Defense, and Ferroptosis Pathways

Selenium (Se) foliar fertilizers enhance crop nutrition and address human selenium deficiency, while improper application may lead to excessive intake and residue accumulation. Our study comprehensively assessed the toxicity and function of novel selenium nanoparticles and traditional sodium selenite fertilizers across cell, zebrafish, and murine models. Both fertilizers enhanced antioxidant pathways at low doses, but selenium nanoparticles exhibited stronger antioxidant and ferroptosis-modulating effects with lower toxicity at a high dose. Sodium selenite increased total and lipid ROS production, leading to decreased viability of cells and increased distortion and mortality of zebrafish. In mice, sodium selenite induced hepatic toxicity and decreased GPX4. Transcriptome analysis revealed that sodium selenite downregulated c-JUN and APOA4, weakening the antioxidant defense, whereas selenium nanoparticles promoted ferroptosis resistance through FGF21. These findings suggest selenium nanoparticles as a safer alternative for Se biofortification, mitigating health risks while supporting food security and environmental sustainability.

Advancing thyroid disease research: The role and potential of zebrafish model

Thyroid disorders significantly affect human metabolism, cardiovascular function, skeletal health, and reproductive systems, presenting a complex challenge due to their multifactorial nature. Understanding the underlying mechanisms and developing novel therapeutic approaches require appropriate models. Zebrafish, with their genetic tractability, short life cycle, and physiological relevance, have emerged as a valuable model for investigating thyroid diseases. This review provides a comprehensive analysis of the zebrafish thyroid gland's structure and function, explores its application in modeling thyroid pathologies such as hypothyroidism, hyperthyroidism, and thyroid cancer, and discusses current limitations and possible improvements. Furthermore, it outlines future directions for zebrafish-based research, focusing on enhancing the model's relevance to human thyroid disease and its potential to expedite the development of clinical therapies.

Selenium toxicity in fishes: A current perspective

Anthropogenic activities have led to increased levels of contaminants that pose significant threats to aquatic organisms, particularly fishes. One such contaminant is Selenium (Se), a metalloid which is released by various industrial activities including mining and fossil fuel combustion. Selenium is crucial for various physiological functions, however it can bioaccumulate and become toxic at elevated concentrations. Given that fishes are key predators in aquatic ecosystems and a major protein source for humans, Se accumulation raises considerable ecological and food safety concerns. Selenium induces toxicity at the cellular level by disrupting the balance between reactive oxygen species (ROS) production and antioxidant capacity leading to oxidative damage. Chronic exposure to elevated Se impairs a wide range of critical physiological functions including metabolism, growth and reproduction. Selenium is also a potent teratogen and induces various types of adverse developmental effects in fishes, mainly due to its maternal transfer to the eggs. Moreover, that can persist across generations. Furthermore, Se-induced oxidative stress in the brain is a major driver of its neurotoxicity, which leads to impairment of several ecologically important behaviours in fishes including cognition and memory functions, social preference and interactions, and anxiety response. Our review provides an up-to-date and in-depth analysis of the various adverse physiological effects of Se in fishes, while identifying knowledge gaps that need to be addressed in future research for greater insights into the impact of Se in aquatic ecosystems.

Effects of Insecticide and Herbicides on Thyroid Disturbances in Zebrafish

Thyroid cancer usually begins with thyroid dysfunction and nodules and has become the most common cancer globally, especially in women. Although the causes of thyroid dysfunction are complex, the presence of environmental pollutants, especially certain pesticides as established mutagens, has been widely accepted. Zebrafish (Danio rerio) have similar toxic reactions and signal transduction pathways to humans and are very similar to humans in physiology, development, and metabolic function. Here, the direct toxicity effects and mechanisms of different insecticides and herbicides on zebrafish thyroid functions and indirect toxicity effects originating from thyroid dysfunction were summarized and compared. The overall toxicity of insecticides on the zebrafish thyroid was greater than that of herbicides based on effective concentrations. Penpropathrin and atrazine were more typical thyroid disruptors than other pesticides. Meanwhile, chiral pesticides showed more sophisticated single/combined toxicity effects on both parental and offspring zebrafish. Besides thyroid hormone levels and HPT axis-related gene expression alteration, developmental toxicity, immunotoxicity, and oxidative damage effects were all observed. These data are necessary for understanding the thyroid interference effect of pesticides on humans and for screening for thyroid disruptors in surface water with zebrafish models for the pre-assessment of human health risks and ecological risk control in the future.

Selenized non-Saccharomyces yeasts and their potential use in fish feed

Selenium (Se) is a vital trace element, essential for growth and other biological functions in fish. Its significance lies in its role as a fundamental component of selenoproteins, which are crucial for optimal functioning of the organism. The inclusion of Se in the diets of farmed animals, including fish, has proved invaluable in mitigating the challenges arising from elemental deficiencies experienced in captivity conditions due to limitations in the content of fishmeal. Supplementing diets with Se enhances physiological responses, particularly mitigates the effects of the continuous presence of environmental stress factors. Organic Se has been shown to have higher absorption rates and a greater impact on bioavailability and overall health than inorganic forms. A characteristic feature of yeasts is their rapid proliferation and growth, marked by efficient mineral assimilation. Most of the selenized yeasts currently available in the market, and used predominantly in animal production and aquaculture, are based on Saccharomyces cerevisiae, which contains selenomethionine (Se-Met). The object of this review is to highlight the importance of selenized yeasts. In addition, it presents metabolic and productive aspects of other yeast genera that are important potential sources of organic selenium. Some yeast strains discussed produce metabolites of interest such as lipids, pigments, and amino acids, which could have applications in aquaculture and further enrich their usefulness.

Parental exposure to Cypermethrin causes intergenerational toxicity in zebrafish offspring

Cypermethrin (CYP), a synthetic pyrethroid pesticide, has been detected in agriculture and aquaculture. However, there is limited knowledge about the transgenerational impacts. This study aimed to investigate the developmental toxicity of CYP on F1 larvae offspring of adult zebrafish exposed to various CYP concentrations (5, 10, and 20 μg/L) for 28 days. The results indicated that CYP accumulated in parental zebrafish, and CYP was below the limit of quantification in offspring. Paternal exposure impacted the hatching rate and heart rate of the F1 generation. Furthermore, CYP significantly impacted the development of swim bladders in progeny and dysregulated the genes relevant to swim bladder development. The neutrophil migrated to the swim bladder. The mRNA levels of the inflammatory factors were also significantly elevated. According to network toxicology, PI3-AKT may be the signaling pathway for CYP-influenced bladder development. Subsequent molecular docking and Western blot analysis showed CYP affected the PI3-AKT signaling pathway. Notably, MK-2206, a specific Akt inhibitor, rescued the CYP-induced damage of swim bladder development in offspring. The present study highlights the potential risks of CYP on the development of offspring and lasting impact in aquatic environments.

The beneficial and toxic effects of selenium on zebrafish. A systematic review of the literature

Selenium is an important and essential trace element in organisms, but its effects on organisms are also a "double-edged sword". Selenium deficiency or excess can endanger the health of humans and animals. In order to thoroughly understand the nutritional value and toxicity hazards of selenium, researchers have conducted many studies on the model animal zebrafish. However, there is a lack of induction and summary of relevant research on which selenium acts on zebrafish. This paper provides a review of the reported studies. Firstly, this article summarizes the benefits of selenium on zebrafish from three aspects: Promoting growth, Enhancing immune function and anti-tumor ability, Antagonizing some pollutants, such as mercury. Then, three aspects of selenium toxicity to zebrafish are introduced: nervous system and behavior, reproductive system and growth, and damage to some organs. This article also describes how different forms of selenium compounds have different effects on zebrafish health. Finally, prospects for future research directions are presented.

Chronic Paternal/Maternal Exposure to Environmental Concentrations of Imidacloprid and Thiamethoxam Causes Intergenerational Toxicity in Zebrafish Offspring

Imidacloprid (IMI) and thiamethoxam (THM) are ubiquitous in aquatic ecosystems. Their negative effects on parental fish are investigated while intergenerational effects at environmentally relevant concentrations remain unclear. In this study, F0 zebrafish exposed to IMI and THM (0, 50, and 500 ng L-1) for 144 days post-fertilization (dpf) was allowed to spawn with two modes (internal mating and cross-mating), resulting in four types of F1 generations to investigate the intergenerational effects. IMI and THM affected F0 zebrafish fecundity, gonadal development, sex hormone and VTG levels, with accumulations found in F0 muscles and ovaries. In F1 generation, paternal or maternal exposure to IMI and THM also influenced sex hormones levels and elevated the heart rate and spontaneous movement rate. LncRNA-mRNA network analysis revealed that cell cycle and oocyte meiosis-related pathways in IMI groups and steroid biosynthesis related pathways in THM groups were significantly enriched in F1 offspring. Similar transcriptional alterations of dmrt1, insl3, cdc20, ccnb1, dnd1, ddx4, cox4i1l, and cox5b2 were observed in gonads of F0 and F1 generations. The findings indicated that prolonged paternal or maternal exposure to IMI and THM could severely cause intergenerational toxicity, resulting in developmental toxicity and endocrine-disrupting effects in zebrafish offspring.

Environmentally relevant concentrations of selenite trigger reproductive toxicity by affecting oocyte development and promoting larval apoptosis

As a trace element, selenium (Se) has been widely added to food to maintain the physiological homeostasis of the organism. The adverse effects of Se on the reproduction of zebrafish have been investigated, however, the effects of Se on the maturation and apoptosis of zebrafish oocytes remain unclear. In this study, zebrafish embryos (2 h post fertilization, hpf) were exposed to 0, 12.5, 25, 50, and 100 μg Se/L for 120 days. The results demonstrated that exposure to selenite decreased the gonad-somatic index (GSI) and cumulative production of eggs, inhibited oocyte maturation (OM), and increased oocyte apoptosis in females. Exposure to selenite decreased the contents of sex hormones (E2) in the serum and increased the levels of reactive oxygen species (ROS) and cyclic adenosine monophosphate (cAMP) in the ovary. Furthermore, exposure to selenite downregulated the transcription level of genes on the HPG axis, decreased the phosphorylation level of CyclinB and the protein content of cAMP-dependent protein kinase (Pka), and upregulated the expression of genes (eif2s1a and chop) and proteins (Grp78, Chop) related to endoplasmic reticulum stress (ERS) and apoptosis. Moreover, maternal exposure to selenite resulted in the apoptosis of offspring and upregulated the content of ROS and the transcription level of genes related to ERS and apoptosis.