Environmental estrogen exposure converts lipid metabolism in male fish to a female pattern mediated by AMPK and mTOR signaling pathways

Estrogenic Responsiveness of Brown Trout Primary Hepatocyte Spheroids to Environmental Levels of 17α-Ethinylestradiol

Three-dimensional (3D) fish hepatocyte cultures are promising alternative models for replicating in vivo data. Few studies have attempted to characterise the structure and function of fish 3D liver models and illustrate their applicability. This study aimed to further characterise a previously established spheroid model obtained from juvenile brown trout (Salmo trutta) primary hepatocytes under estrogenic stimulation. The spheroids were exposed for six days to environmentally relevant concentrations of 17α-ethinylestradiol-EE2 (1-100 ng/L). The mRNA levels of peroxisome (catalase-Cat and urate oxidase-Uox), lipid metabolism (acyl-CoA long chain synthetase 1-Acsl1, apolipoprotein AI-ApoAI, and fatty acid binding protein 1-Fabp1), and estrogen-related (estrogen receptor α-ERα, estrogen receptor β-ERβ, vitellogenin A-VtgA, zona pellucida glycoprotein 2.5-ZP2.5, and zona pellucida glycoprotein 3a.2-ZP3a.2) target genes were evaluated by quantitative real-time polymerase chain reaction. Immunohistochemistry was used to assess Vtg and ZP protein expressions. At the highest EE2 concentration, VtgA and ZP2.5 genes were significantly upregulated. The remaining target genes were not significantly altered by EE2. Vtg and ZP immunostaining was consistently increased in spheroids exposed to 50 and 100 ng/L of EE2, whereas lower EE2 levels resulted in a weaker signal. EE2 did not induce significant changes in the spheroids' viability and morphological parameters. This study identified EE2 effects at environmentally relevant doses in trout liver spheroids, indicating its usefulness as a proxy for in vivo impacts of xenoestrogens.

Effects of Metabolic Disruption on Lipid Metabolism and Yolk Retention in Zebrafish Embryos

A subgroup of endocrine-disrupting chemicals have the ability to disrupt metabolism. These metabolism-disrupting chemicals (MDCs) can end up in aquatic environments and lead to adverse outcomes in fish. Although molecular and physiological effects of MDCs have been studied in adult fish, few studies have investigated the consequences of metabolic disruption in fish during the earliest life stages. To investigate the processes affected by metabolic disruption, zebrafish embryos were exposed to peroxisome proliferator-activated receptor gamma (PPARγ) agonist rosiglitazone, the PPARγ antagonist T0070907, and the well-known environmentally relevant MDC bisphenol A. Decreased apolipoprotein Ea transcript levels indicated disrupted lipid transport, which was likely related to the observed dose-dependent increases in yolk size across all compounds. Increased yolk size and decreased swimming activity indicate decreased energy usage, which could lead to adverse outcomes because the availability of energy reserves is essential for embryo survival and growth. Exposure to T0070907 resulted in a darkened yolk. This was likely related to reduced transcript levels of genes involved in lipid transport and fatty acid oxidation, a combination of responses that was specific to exposure to this compound, possibly leading to lipid accumulation and cell death in the yolk. Paraoxonase 1 (Pon1) transcript levels were increased by rosiglitazone and T0070907, but this was not reflected in PON1 enzyme activities. The present study shows how exposure to MDCs can influence biochemical and molecular processes involved in early lipid metabolism and may lead to adverse outcomes in the earliest life stages of fish. Environ Toxicol Chem 2024;43:1880-1893. © 2024 The Author(s). Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Examining effects of a novel estrogenic perfluoro-alcohol, 1H,1H,8H,8H-Perfluorooctane-1,8-diol (FC8-diol), using the fathead minnow EcoToxChip

In a previous in vivo study, adult male fathead minnows (Pimephales promelas) were exposed via water for 4 days to 1H,1H,8H,8H-perfluorooctane-1,8-diol (FC8-diol). The present study expands on the evaluation of molecular responses to this perfluoro-alcohol by analyzing 26 male fathead minnow liver RNA samples from that study (five from each test concentration: 0, 0.018, 0.051, 0.171, and 0.463 mg FC8-diol/L) using fathead minnow EcoToxChips Ver. 1.0. EcoToxChips are a quantitative polymerase chain reaction array that allows for simultaneous measurement of >375 species-specific genes of toxicological interest. Data were analyzed with the online tool EcoToxXplorer. Among the genes analyzed, 62 and 96 were significantly up- and downregulated, respectively, by one or more FC8-diol treatments. Gene expression results from the previous study were validated, showing an upregulation of vitellogenin mRNA (vtg) and downregulation of insulin-like growth factor 1 mRNA (igf1). Additional genes related to estrogen receptor activation including esr2a (estrogen receptor 2a) and esrrb (estrogen related receptor beta) were also affected, providing further confirmation of the estrogenic nature of FC8-diol. Furthermore, genes involved in biological pathways related to lipid and carbohydrate metabolism, innate immune response, endocrine reproduction, and endocrine thyroid were significantly affected. These results both add confidence in the use of the EcoToxChip tool for inferring chemical mode(s) of action and provide further insights into the possible biological effects of FC8-diol. Environ Toxicol Chem 2024;00:1-9. © 2024 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Degradation profile of environmental pollutant 17β-estradiol by human intestinal fungus Aspergillus niger RG13B1 and characterization of genes involved in its degradation

Environmental hormones have attracted more attention because of their adverse impact on the health and ecological security of human. Biodegradation is still an efficient tactics to remove environmental hormones, but human intestinal microbes remain to be elucidated in the role of their degradation. In the present work, we intended to perform the in vitro experiment for investigating the degradation of 17β-estradiol, the main environmental estrogen, by human intestinal microflora Aspergillus niger RG13B1. Its degradation led to the production of eighteen metabolites characterized by 1H, 13C, and 2D NMR, and HRMS spectra, including nine new (1-9) and nine known metabolites (10-18). Based on their structures, the degradation pathway of 17β-estradiol mediated by A. niger RG13B1 involved hydroxylation, oxidation, methylation, acetylation, and dehydrogenation, especially infrequent lactylation, and the key degradation enzymes were found in the gene cluster of A. niger. In addition, we found that metabolite 12 interacted with amino acid residues Lys37, Gln39, Lys93, and Asn115 of NF-κB p65 to suppress expressions of inflammatory genes or proteins, exerting its anti-inflammatory effect. This study first illustrated the role of human gut microbe in 17β-estradiol degradation and provided new insights into its degradation mechanism by A. niger RG13B1.

Effect comparisons of different conditioners and microbial agents on the degradation of estrogens during dairy manure composting

To investigate the degradation efficiency of conditioners and commercial microbial agents on estrogens (E1, 17α-E2, 17β-E2, E3, EE2, and DES) in the composting process of dairy manure, seven different treatments (RHB-BF, OSP-BF, SD-BF, MR-BF, MR-FS, MR-EM, and MR-CK) under forced ventilation conditions were composted and monitored regularly for 30 days. The results indicated that the removal rates of estrogens in seven treatments ranged from 95.35% to 99.63%, meanwhile the degradation effect of the composting process on 17β-Estradiol equivalent (EEQ) was evaluated, and the removal rate of ΣEEQ ranged from 96.42% to 99.72%. With the combined addition of rice husk biochar (RHB) or oyster shell powder (OSP) and bio-bacterial fertilizer starter cultures (BF), namely RHB-BF and OSP-BF obviously promoted the rapid degradation of estrogens. 17β-E2 was completely degraded on the fifth day of composting in OSP-BF. Microbial agents have some promotional effect and enhances the microbial degradation of synthetic estrogen (EE2, DES). According to the results of RDA, pH and EC were the main environmental factors affecting on the composition and succession of estrogen-related degrading bacteria in composting system. As predominant estrogens-degrading genera, Acinetobacter, Bacillus, and Pseudomonas effected obviously on the change of estrogens contents. The research results provide a practical reference for effective composting of dairy manure to enhancing estrogens removal and decreasing ecological risk.

Combined western diet and bisphenol A exposure induces an oxidative stress-based paraoxonase 1 response in larval zebrafish

Paraoxonase 1 (PON1) is an antioxidant enzyme linked to metabolic disorders by genome-wide association studies in humans. Exposure to metabolic disrupting chemicals (MDCs) such as bisphenol A (BPA), together with genetic and dietary factors, can increase the risk of metabolic disorders. The objective of this study was to investigate how PON1 responds to the metabolic changes and oxidative stress caused by a western diet, and whether exposure to BPA alters the metabolic and PON1 responses. Zebrafish larvae at 14 days post fertilization were fed a custom-made western diet with and without aquatic exposure to two concentrations of BPA for 5 days. A combination of western diet and 150 μg/L BPA exposure resulted in a stepwise increase in weight, length and oxidative stress, suggesting that BPA amplifies the western diet-induced metabolic shift. PON1 arylesterase activity was increased in all western diet and BPA exposure groups and PON1 lactonase activity was increased when western diet was combined with exposure to 1800 μg/L BPA. Both PON1 activities were positively correlated to oxidative stress. Based on our observations we hypothesize that a western diet caused a shift towards fatty acid-based metabolism, which was increased by BPA exposure. This shift resulted in increased oxidative stress, which in turn was associated with a PON1 activity increase as an antioxidant response. This is the first exploration of PON1 responses to metabolic challenges in zebrafish, and the first study of PON1 in the context of MDC exposure in vertebrates.

Waterborne Tebuconazole Exposure Induces Male-Biased Sex Differentiation in Zebrafish (Danio rerio) Larvae via Aromatase Inhibition

Tebuconazole is a widely used fungicide for various crops that targets sterol 14-α-demethylase (CYP51) in fungi. However, attention has shifted to aromatase (CYP19) due to limited research indicating its reproductive impact on aquatic organisms. Herein, zebrafish were exposed to 0.5 mg/L tebuconazole at different developmental stages. The proportion of males increased significantly after long-term exposure during the sex differentiation phase (0-60, 5-60, and 19-60 days postfertilization (dpf)). Testosterone levels increased and 17β-estradiol and cyp19a1a expression levels decreased during the 5-60 dpf exposure, while the sex ratio was equally distributed on coexposure with 50 ng/L 17β-estradiol. Chemically activated luciferase gene expression bioassays determined that the male-biased sex differentiation was not caused by tebuconazole directly binding to sex hormone receptors. Protein expression and phosphorylation levels were specifically altered in the vascular endothelial growth factor signaling pathway despite excluding the possibility of tebuconazole directly interacting with kinases. Aromatase was selected for potential target analysis. Molecular docking and aromatase activity assays demonstrated the interactions between tebuconazole and aromatase, highlighting that tebuconazole poses a threat to fish populations by inducing a gender imbalance.

Physico-chemical and biological remediation techniques for the elimination of endocrine-disrupting hazardous chemicals

Due to their widespread occurrence and detrimental effects on human health and the environment, endocrine-disrupting hazardous chemicals (EDHCs) have become a significant concern. Therefore, numerous physicochemical and biological remediation techniques have been developed to eliminate EDHCs from various environmental matrices. This review paper aims to provide a comprehensive overview of the state-of-the-art remediation techniques for eliminating EDHCs. The physicochemical methods include adsorption, membrane filtration, photocatalysis, and advanced oxidation processes. The biological methods include biodegradation, phytoremediation, and microbial fuel cells. Each technique's effectiveness, advantages, limitations, and factors affecting their performance are discussed. The review also highlights recent developments and future perspectives in EDHCs remediation. This review provides valuable insights into selecting and optimizing remediation techniques for EDHCs in different environmental matrices.

Dietary docosahexaenoic acid reduces fat deposition and alleviates liver damage induced by D-galactosamine and lipopolysaccharides in Nile tilapia (Oreochromis niloticus)

Liver health is important to maintain survival and growth of fish. Currently, the role of dietary docosahexaenoic acid (DHA) in improving fish liver health is largely unknown. This study investigated the role of DHA supplementation in fat deposition and liver damage caused by D-galactosamine (D-GalN) and lipopolysaccharides (LPS) in Nile tilapia (Oreochromis niloticus). Four diets were formulated as control diet (Con), Con supplemented with 1 % DHA, 2 % DHA and 4 % DHA diets, respectively. The diets were fed to 25 Nile tilapia (2.0 ± 0.1 g, average initial weight) in triplicates for four weeks. After the four weeks, 20 fish in each treatment were randomly selected and injected with a mixture of 500 mg D-GalN and 10 μL LPS per mL to induce acute liver injury. The results showed that the Nile tilapia fed on DHA diets decreased visceral somatic index, liver lipid content and serum and liver triglyceride concentrations than those fed on the Con diet. Moreover, after D-GalN/LPS injection, the fish fed on DHA diets decreased alanine aminotransferase and aspartate transaminase activities in the serum. The results of liver qPCR and transcriptomics assays together showed that the DHA diets feeding improved liver health by downregulating the expression of the genes related to toll-like receptor 4 (TLR4) signaling pathway, inflammation and apoptosis. This study indicates that DHA supplementation in Nile tilapia alleviates the liver damage caused by D-GalN/LPS through increasing lipid catabolism, decreasing lipogenesis, TLR4 signaling pathway, inflammation, and apoptosis. Our study provides novel knowledge on the role of DHA in improving liver health in cultured aquatic animals for sustainable aquaculture.

Estrogenic and non-estrogenic effects of bisphenol A and its action mechanism in the zebrafish model: An overview of the past two decades of work

Bisphenol A (BPA) is the most simple and predominant component of the Bisphenol family. BPA is widely present in the environment and the human body as a result of its extensive usage in the plastic and epoxy resins of consumer goods like water bottles, food containers, and tableware. Since the 1930s, when BPA's estrogenic activity was first observed, and it was labeled as a "mimic hormone of E2", studies on the endocrine-disrupting effects of BPA then have been widely conducted. As a top vertebrate model for genetic and developmental studies, the zebrafish has caught tremendous attention in the past two decades. By using the zebrafish, the negative effects of BPA either through estrogenic signaling pathways or non-estrogenic signaling pathways were largely found. In this review, we tried to draw a full picture of the current state of knowledge on the estrogenic and non-estrogenic effects of BPA with their mechanisms of action through the zebrafish model of the past two decades, which may help to fully understand the endocrine-disrupting effects of BPA and its action mechanism, and give a direction for the future studies.

Integrated lipidomics and transcriptomics analysis reveal lipid metabolism disturbance in scallop (Chlamys farreri) exposure to benzo[a]pyrene

Benzo[a]pyrene (B[a]P) commonly bioaccumulates in lipid-rich tissues due to its lipophilicity and further affects lipid metabolism. The present study systematically investigated the lipid metabolism disturbance in digestive glands of scallops (Chlamys farreri) exposure to B[a]P, based on lipidomics, transcriptomics, molecular and biochemical analysis. We exposed the scallops to environmentally relevant concentrations of B[a]P for 21 days. The bioaccumulation of B[a]P, lipid content and lipid peroxidation in digestive glands were measured. Integrated lipidomics and transcriptomics analysis, the differential lipid species were identified and key genes based on the pathways in which genes and lipid species involved together were selected in scallop exposure to 10 μg/L B[a]P. The changes of lipid profile showed that triglycerides (TGs) were accumulated after 21 days exposure, while the phospholipids (PLs) decreased demonstrated membrane structures were disrupted by B[a]P. In combination with the change of gene expression, we speculated that B[a]P could induce lipids accumulation by up-regulating lipid synthesis-related genes expression, down-regulating lipolysis-related genes expression and interfering with lipid transport. Overall, this study provides new insights into the mechanisms of lipid metabolism disturbance in bivalves exposed to PAHs, and establishes a foundation for understanding the bioaccumulation mechanism of B[a]P in aquatic organisms, which is of great importance for further ecotoxicological study.

Vitellogenin 1 is essential for fish reproduction by transporting DHA-containing phosphatidylcholine from liver to ovary

Vitellogenins (Vtgs) are essential for female reproduction in oviparous animals, yet the exact roles and mechanisms remain unknown. In the present study, we knocked out vtg1, which is the most abundant Vtg in zebrafish, Danio rerio via the CRISPR/Cas 9 technology. We aimed to identify the roles of Vtg1 and related mechanisms in reproduction and development. We found that, the Vtg1-deficient female zebrafish reduced gonadosomatic index, egg production, yolk granules and mature follicles in ovary compared to the wide type (WT). Moreover, the Vtg1-deficient zebrafish diminished hatching rates, cumulative survival rate, swimming capacity and food intake, but increased malformation rate, and delayed swim bladder development during embryo and early-larval phases. The Vtg1-deficiency in female broodstock inhibited docosahexaenoic acid-enriched phosphatidylcholine (DHA-PC) transportation from liver to ovary, which lowered DHA-PC content in ovary and offspring during larval stage. However, the Vtg1-deficient zebrafish increased gradually the total DHA-PC content via exogeneous food intake, and the differences in swimming capacity and food intake returned to normal as they matured. Furthermore, supplementing Vtg1-deficient zebrafish with dietary PC and DHA partly ameliorated the impaired female reproductive capacity and larval development during early phases. This study indicates that, DHA and PC carried by Vtg1 are crucial for female fecundity, and affect embryo and larval development through maternal-nutrition effects. This is the first study elucidating the nutrient and physiological functions of Vtg1 and the underlying biochemical mechanisms in fish reproduction and development.

High dissolved oxygen exacerbates ammonia toxicity with sex-dependent manner in zebrafish

Ammonia nitrogen is one of the important environmental factors, and causes negative effects for fish health in ecosystem and aquaculture. The toxic effects and mechanisms of ammonia in fish deserve further investigation. In the present study, we exposed female and male zebrafish (Danio rerio) to ammonia (50 mg/L NH₄Cl) with oxygenated (7.5-7.8 mg/L) or non‑oxygenated (3.8-4.5 mg/L) water, to identify the combined effects of dissolved oxygen and ammonia on fish with gender difference. The results showed that oxygenated ammonia exposure increased fish mortality, gill secondary lamellas damage and gill tissue spaces, gene expressions of proinflammatory interleukin 1 beta (il-1β) and apoptotic caspase8 as compared with non‑oxygenated ammonia. Besides, oxygenated ammonia elevated plasma ammonia contents, and decreased the discharge of body ammonia through gills by depressing the enzyme activity of Na⁺/K⁺-ATPase. Notably, when zebrafish were subjected to ammonia stress, more severe mortality, gill damage and tissue inflammatory response were observed in males than females. This is the first study to clarify the gender-dependent impacts of ammonia toxicity, and the adverse effects of oxygenation on ammonia resistance in zebrafish.

Metformin improves fish sperm quality by regulating glucose uptake capacity during in vitro storage

A suitable additive for fish sperm storage in vitro is necessary for artificial reproduction. In this study, we evaluated the effects of different concentrations (100, 200, 400, and 800 µmol/L) of metformin (Met) on Schizothorax prenanti and Onychostoma macrolepis sperm under storage in vitro for 72 h. Compared with the control group, 400 µmol/L Met was more effective at improving the quality and fertilization capacity of S. prenanti sperm by increasing the adenosine triphosphate (ATP) content within the sperm. Further study found that Met stabilized the ATP level by enhancing the glucose uptake in S. prenanti sperm, and this effect might be associated with the activation of AMP-activated protein kinase (AMPK) in sperm. In this study, we also found that glucose could be absorbed by the sperm of S. prenanti, which was mainly accumulated in the midpiece of S. prenanti sperm, where mitochondria were located. In addition, Compound C significantly inhibited the beneficial effects of Met on the quality and glucose uptake capacity of S. prenanti sperm by inhibiting AMPK phosphorylation. These results revealed that AMPK played an important role in vitro sperm storage, and Met maintained ATP content and increased the storage time of S. prenanti sperm in vitro for 72 h, possibly due to Met enhanced glucose uptake capacity of sperm by activating AMPK. Similarly, the beneficial effects of Met on S. prenanti sperm were also found in O. macrolepis sperm, suggesting that Met may hold great promise for the practice of storing fish in vitro.

Toxic effects and transcriptional responses in zebrafish liver cells following perfluorooctanoic acid exposure

As a typical type of persistent organic pollutant, perfluorooctanoic acid (PFOA) is pervasive in the environment. Multiple studies have found that PFOA has hepatotoxicity, but the mechanism remains poorly understood. In this study, the toxic effects of different concentrations of PFOA on zebrafish liver cells were systematically assessed by recording cell survival, ultrastructural observations, and transcriptome analyses. The results showed that the inhibition of cell viability and the massive accumulation of autophagic vacuoles were observed at 400 µM PFOA, while transcriptomic changes occurred with treatments of 1 and 400 µM PFOA. The transcription levels of 1055 (977 up- and 78 down-regulated genes) and 520 (446 up- and 74 down-regulated genes) genes were significantly changed after treatment with 1 and 400 µM PFOA, respectively. Based on Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis, significant expression changes were observed in autophagy, tight junction, signal transduction, immune system, endocrine system, and metabolism-related pathways, indicating that such processes were greatly affected by PFOA exposure. The findings of this study will provide a scientific basis for the toxic effects and potential toxic mechanisms of PFOA on zebrafish, and provide information for ecological risk assessments.

Metabolomic responses in livers of female and male zebrafish (Danio rerio) following prolonged exposure to environmental levels of zinc oxide nanoparticles

Zinc oxide nanoparticles (ZnONPs) are widespread pollutants that are present in diverse environmental samples. Here, we determined metabolomic and bioenergetic responses in the liver of female and male zebrafish exposed to a prolonged environmentally relevant concentration of ZnONPs. Metabolome analysis revealed that exposure to 500 μg/L ZnONPs reduced the abundance of metabolites in the tricarboxylic acid (TCA) cycle by modulating the activities of rate-limiting enzymes α-ketoglutarate dehydrogenase and isocitrate dehydrogenase. Moreover, oxidative phosphorylation (OXPHOS) was negatively impacted in the liver based upon decreased activities of mitochondrial Complex I and V in both female and male livers. Our results revealed that bioenergetic responses were not attributed to dissolved Zn²⁺ and were not sex-specific. However, the metabolic responses in liver following exposure to ZnONPs did show sex-specific responses. Females exposed to ZnONPs compensated for the energetic stress via increasing fatty acids and amino acids metabolism, while males compensated to ZnONPs exposure by adjusting amino acids metabolism, based upon transcript profiles. This study demonstrates that zebrafish adjust the transcription of metabolic enzymes in the liver to compensate for metabolic disruption following ZnONPs exposure. Taken together, this study contributes to a comprehensive understanding of risks related to ZnONPs exposure in relation to metabolic activity in the liver. Environmental implication Zinc oxide nanoparticles (ZnONPs) are widely used in industry and are subsequently released into environments. However, biological responses between female and male following ZnONPs exposure has never been compared. Our data revealed for the first time that female and male zebrafish showed comparable bioenergetic responses, but different metabolic responses to ZnONPs at an environmentally relevant dose. Females compensated for the energetic stress via increasing fatty acids and amino acids metabolism, while males compensated to ZnONPs exposure by adjusting amino acids metabolism in livers. This study reveals that sex may be an important variable to consider in risk assessments of nanoparticles released into environments.

UPLC-QTOF/MS Metabolomics and Biochemical Assays Reveal Changes in Hepatic Nutrition and Energy Metabolism during Sexual Maturation in Female Rainbow Trout (Oncorhynchus mykiss)

Mobilization and repartition of nutrients and energy are prerequisites for the normal sexual maturity of broodstock. However, there are few studies on the mechanisms of hepatic nutrients and energy metabolism during sexual maturation in female rainbow trout (Oncorhynchus mykiss). This study investigated hepatic metabolite changes and explored the potential nutritional regulation mechanism between mature and immature female rainbow trout by combining UPLC-QTOF/MS metabolomics and biochemical assays. It was observed that hepatic biochemical assays differed considerably between the two groups, such as glucose, triglycerides, hexokinase, lipase, and aspartate aminotransferase. Liver metabolomics showed that various differential metabolites involved in amino acid and lipid metabolism markedly increased, suggesting the enhancement of lipid metabolism and amino acid anabolism in the liver provides the necessary material basis for ovarian development. Meanwhile, glycogen catabolism and glycolysis hold the key to maintaining organismal energy homeostasis with normal sexual maturation of female rainbow trout. Overall, the results from this study suggested that the liver undergoes drastic reprogramming of the metabolic profile in response to mobilization and repartition of nutrients and energy during the sexual maturation of female rainbow trout. This study further deepened the understanding of the reproductive biology of rainbow trout, and provided the theoretical basis and practical ramifications for nutritional requirements of breeding high-quality broodstock in the artificial propagation of rainbow trout.

The multiple biotoxicity integrated study in grass carp (Ctenopharyngodon idella) caused by Ochratoxin A: Oxidative damage, apoptosis and immunosuppression

Ochratoxin A (OTA) is a common hazardous food contaminant that seriously endangers human and animal health. However, limited study is focused on aquatic animal. This research investigated the multiple biotoxicity of OTA on spleen (SP) and head kidney (HK) in grass carp and its related mechanism. Our data showed that, dietary supplemented with OTA above 1209 μg/kg caused histopathological damages by decreasing the number of lymphocytes and necrotizing renal parenchymal cells. Meanwhile, OTA caused oxidative damage and reduced the isoforms mRNAs transcripts of antioxidant enzymes (e.g., GPX1, GPX4, GSTO) partly due to suppressing NF-E2-related factor 2 (Nrf2). OTA triggered apoptosis through mitochondria and death receptor pathway potentially by p38 mitogen-activated protein kinase (p38MAPK) activation. Besides, OTA exacerbated inflammation by down-regulation of anti-inflammatory factor (e.g., IL-10, IL-4) and up-regulations of pro-inflammatory factors (e.g., TNF-α, IL-6), which could be ascribed to signaling meditation of Janus kinase / signal transducer and activator of transcription (JAK/STAT). Additionally, the safe upper limits of OTA were estimated to be 677.6 and 695.08 μg/kg based on the immune-related indexes (C3 contents in the SP and LZ activities in the HK, respectively). Our study has provided a wide insight for toxicological assessment of feed pollutant in aquatic animals.

Insights into disruption of lipid metabolism in digestive gland of female scallop Chlamys farreri under B[a]P exposure

Lipids are the main energy support during gametogenesis. Digestive gland is the key organ of aquatic animal metabolism for storing nutrition and supplying energy. It participates in a variety of life activities (such as growth, digestion, immunity, and reproduction). Nutrients stored in digestive glands, especially lipids, provide energy for reproductive behaviors such as gametogenesis and ovulation. A large number of studies have confirmed the accumulation of lipids from digestive gland to gonad during gametogenesis. At present, the research on the interference mechanism of persistent organic pollutants (POPs) on lipid metabolism of aquatic animals and the adaptive response of aquatic animals to POPs stress focus on biochemical levels or a few genes. The potential molecular mechanism of lipid metabolism interference needs to be further studied. In addition, as an important stage of aquatic animals, the reproductive period is a vigorous period of lipid metabolism. However, at present, there is no report on the molecular mechanism of POPs interfering with the lipid metabolism of the digestive gland in the reproductive process of aquatic animals. In this study, female scallop C. farreri was cultured in natural seawater and exposed to 4 μg/L B[a]P in seawater. Transcriptome analysis of digestive glands at multiple stages (proliferative stage, growth stage, mature stage and spawn stage) was performed, and iPath pathway analysis was used to analyze lipid metabolism pathways and differential genes. The interference mechanism of lipid metabolism in bivalves during reproductive period was revealed. This study will provide valuable genomic information on the role of digestive glands in lipid metabolism and reproduction of C. farreri, and will contribute to further functional genomics of bivalves and other closely related species.

Peroxisome proliferator-activated receptor gamma is essential for stress adaptation by maintaining lipid homeostasis in female fish

Reduction of lipid synthesis often causes free fatty acid (FFA) overload, resulting consequential oxidative stress and health damage. Environmental stresses also induce cellular oxidative stress in organisms. The functional peroxisome proliferator-activated receptor gamma (pparg) gene is essential for lipid synthesis and homeostatic lipid maintenance. However, the relationship between the pparg-mediated lipid synthesis and environmental stress adaptation awaits full elucidation. Here, we generated a pparg-knockout zebrafish model. The conversion of free fatty acids into triglycerides in the female pparg mutants was hampered by reduced esterification efficiency, thus induced lipotoxicity, as evidenced by high oxidative stress and damaged health in these mutants, which led to reduced resistance to cold, heat and ammonia nitrogen stresses. Activating pparg in the wild-type female fish via dietary supplementation with rosiglitazone (a pparg agonist), or reducing oxidative stress in the female pparg mutants via dietary supplementation with N-acetylcysteine (an antioxidant), or promoting mitochondrial fatty acid β-oxidation in the female pparg mutants via dietary supplementation with l-carnitine, resulted in significantly reduced cellular injury, and improved environmental stress resistance. Collectively, our findings reveal that the regulative function of pparg in FFA esterification is important in stress resistance in female fish, and highlight the tight correlation existing between lipotoxicity and environmental adaptation.

Transcriptomic and Physiological Responses of Chlorella pyrenoidosa during Exposure to 17α-Ethinylestradiol

17α-ethinylestradiol (17α-EE₂) is frequently detected in water bodies due to its use being widespread in the treatment of prostate and breast cancer and in the control of alopecia, posing a threat to humans and aquatic organisms. However, studies on its toxicity to Chlorella pyrenoidosa have been limited to date. This study investigated the effects of 17α-EE₂ on the growth, photosynthetic activity, and antioxidant system of C. pyrenoidosa and revealed related molecular changes using transcriptomic analysis. The cell density of algae was inhibited in the presence of 17α-EE₂, and cell morphology was also altered. Photosynthetics were damaged, while reactive oxygen species (ROS), superoxide dismutase (SOD), and malondialdehyde (MDA) content increased. Further transcriptomic analysis revealed that the pathways of photosynthesis and DNA replication were affected at three concentrations of 17α-EE₂, but several specific pathways exhibited various behaviors at different concentrations. Significant changes in differentially expressed genes and their enrichment pathways showed that the low-concentration group was predominantly impaired in photosynthesis, while the higher-concentration groups were biased towards oxidative and DNA damage. This study provides a better understanding of the cellular and molecular variations of microalgae under 17α-EE₂ exposure, contributing to the environmental risk assessment of such hazardous pollutants on aquatic organisms.

Estrogen Receptors Mediated Negative Effects of Estrogens and Xenoestrogens in Teleost Fishes-Review

Estrogen receptors (ERs) play a key role in many biochemical and physiological processes, that are involved in maintaining organism homeostasis. At the most basic level, they can be divided into nuclear estrogen receptors and membrane estrogen receptors that imply their effect in two ways: slower genomic, and faster non-genomic. In these ways, estrogens and xenoestrogens can negatively affect animal health and welfare. Most of the available literature focuses on human and mammalian physiology, and clearly, we can observe a need for further research focusing on complex mutual interactions between different estrogens and xenoestrogens in aquatic animals, primarily fishes. Understanding the mechanisms of action of estrogenic compounds on the ERs in fishes and their negative consequences, may improve efforts in environmental protection of these animals and their environment and benefit society in return. In this review, we have summarized the ER-mediated effects of xenoestrogens and estrogens on teleost fishes metabolism, their carcinogenic potential, immune, circulatory, and reproductive systems.

Gut microbiota disturbance exaggerates battery wastewater-induced hepatotoxicity through a gut-liver axis

As the primary source of electricity for various devices, batteries are important contributors to the overall electronic waste generated; and are widely considered a source of highly ecotoxic pollutants. Material leakage in battery manufacturing has not been completely solved, and the elucidation of the toxic mechanisms of battery wastewater exposure is needed. We demonstrated that battery waste exposure disrupted the intestinal flora and aggravated hepatotoxicity via the gut-liver axis. Under battery waste exposure, colon epithelium suffered physiological damage, and gene and protein expression levels related to gut barrier function (ZO-1, claudin-1, and Occludin) were significantly downregulated. Meanwhile, battery waste reduced the richness and diversity of the flora, causing metabolites produced by intestinal microbes to enter the gut-liver axis. Gut microbial dysbiosis impaired mitochondrial respiratory function in liver tissue cells, and mitophagy, apoptosis, and the disorder of glycolipids and amino acid metabolism were induced in hosts exposed to battery toxins. Altogether, these results provided novel insights into the underlying mechanisms of battery wastewater-related hepatotoxicity induced by gut microbiota via the gut-liver axis, which has public health implications where humans and animals are exposed to industrial toxins generated by uncontained battery disposal.

Seasonal Differences in Water Pollution and Liver Histopathology of Iberian Barbel (Luciobarbus bocagei) and Douro Nase (Pseudochondrostoma duriense) in an Agricultural Watershed

Histopathology has been used as a very useful tool to provide information on the severity of tissue damage, injuries, and organ functionality. Thus, this work aimed to assess whether seasonal variations (summer and winter) in water quality had consequences on the liver histology of Iberian barbel (Luciobarbus bocagei) and Douro nase (Pseudochondrostoma duriense). The research was carried out in the Vilariça River, a tributary of the Sabor River in Portugal, which is used as spawning grounds by these endemic cyprinids. The liver histopathological changes, assessed through a semi-quantitative system, allowed the identification of 13 histopathological changes located in the hepatic parenchyma, bile duct, and blood vessels. The histopathological changes with a higher prevalence in both species were vacuolization of hepatocytes, endothelial rupture, necrosis, fibrosis, and degenerative vacuolization. The results showed that the severity degree of liver histological alterations ranged between moderate and severe, and the major severity degree was observed in L. bocagei, in the summer season, and at the sampling points located in the downstream and middle stream. The canonical analysis indicated that the exposure of fish to metals may increase the potential risk of liver damage. Thus, in the summer, the high concentrations of Fe, Cu, Zn, As, and Mn justified the prevalence of the biliary duct epithelial detachment, in both species, and the hyperplasia of biliary epithelium, in L. bocagei. In the winter, the high TSS and Cd, Ni, and Cr concentrations justified the prevalence of congestion of blood vessels and degenerative vacuolization in both species. The higher hepatosomatic index of fish caught in the winter was due to the high presence of degenerative vacuolization and hepatocyte vacuolization. The severity of liver histopathological changes reflected differences in the type of contaminants in different seasons and sampling periods, and was thus proven as a valuable indicator of water quality.

Gestational bisphenol A exposure impairs hepatic lipid metabolism by altering mTOR/CRTC2/SREBP1 in male rat offspring

Lipid metabolism is an important biochemical process in the body. Recent studies have found that environmental endocrine disruptors play an important role in the regulation of lipid metabolism. Bisphenol A (BPA), a common environmental endocrine disruptor, has adverse effects on lipid metabolism, but the mechanism is still unclear. This study aimed to investigate the effects of gestational BPA exposure on hepatic lipid metabolism and its possible mechanism in male offspring. The pregnant Sprague-Dawley rats were exposed to BPA (0, 0.05, 0.5, 5 mg/kg/day) from day 5 to day 19 of gestation to investigate the levels of triglyceride (TG) and total cholesterol (TC), and the expression of liver lipid metabolism-related genes in male offspring rats. The results showed that compared with the control group, the TG and TC levels in serum and liver in BPA-exposed groups was increased. And the expressions of liver fatty acid oxidation related genes, such as peroxisome proliferators-activated receptor α (PPARα) and carnitine palmitoyl transferase 1α (CPT1α), were down-regulated. However, the expressions of fatty acid synthesis related genes, such as sterol regulatory element binding proteins 1 (SREBP-1), acetyl-CoA carboxylase 1 (ACC1), fatty acid synthase (FAS) and stearoyl-CoA desaturase 1 (SCD-1), were up-regulated. The increased protein levels of mTOR and p-CRTC2 suggested that CREB-regulated transcription coactivator 2 (CRTC2) might be an important mediator in the mTOR/SREBP-1 pathway. In conclusion, these results demonstrated that mTOR/CRTC2/SREBP-1 could be affected by gestational BPA exposure, which may involve in the lipid metabolic disorders in later life.

Role of nuclear pregnane X receptor in Cu-induced lipid metabolism and xenobiotic responses in largemouth bass (Micropterus salmoides)

The pregnane X receptor (PXR) is a master xenobiotic-sensing receptor in response to toxic byproducts, as well as a key regulator in intermediary lipid metabolism. Therefore, the present study was conducted to investigate the potential role of PXR in mediating the lipid dysregulation and xenobiotic responses under Cu-induced stress in largemouth bass (Micropterus salmoides). Four groups of largemouth bass (52.66 ± 0.03 g) were treated with control, Cu waterborne (9.44 μmol/L), Cu+RIF (Rifampicin, 100 mg/kg, PXR activator), and Cu+KET (Ketoconazole, 20 mg/kg, PXR inhibitor) for 48 h. Results showed that Cu exposure significantly elevated the plasma stress indicators and triggered antioxidant systems to counteract Cu-induced oxidative stress. Acute Cu exposure caused liver steatosis, as indicated by the significantly higher levels of plasma triglycerides (TG), lipid droplets, and mRNA levels of lipogenesis genes in the liver. Liver injuries were detected, as shown by hepatocyte vacuolization and severe apoptotic signals after Cu exposure. Importantly, Cu exposure significantly stimulated mRNA levels of PXR, suggesting the response of this regulator in the xenobiotic response. The pharmacological intervention of PXR by the agonist and antagonist significantly altered hepatic mRNA levels of PXR, implying that RIF and KET were effective agents of PXR in largemouth bass. Administration of RIF significantly exacerbated liver steatosis, and such alterations were dependent on the regulations on pparγ and cd36 rather than srebp1 signaling, which suggested that PXR-PPARγ might be another pathway for Cu-induced lipid deposition in fish. Whereas, KET administration showed reverse effects on lipid metabolism as indicated by the lower hepatic TG levels, suppressed mRNA levels of pparγ and cd36. Activation of PXR stimulated autophagy and inhibited apoptosis, leading to lower hepatic vacuolization; while inhibition of PXR showed higher apoptotic signals, inhibition of autophagic genes and stimulation of apoptotic genes. Taken together, PXR played a cytoprotective role in Cu-induced hepatotoxicity through regulations on autophagy and apoptosis. Overall, our data has demonstrated for the first time on the dual roles of PXR as a co-regulator in mediating xenobiotic responses and lipid metabolism in fish, which implying the potential of PXR as a therapy target for xenobiotics-induced lipid dysregulation and hepatotoxicity.

Transcriptome and in silico approaches provide new insights into the mechanism of male reproductive toxicity induced by chronic exposure to DEHP

Di-(2-ethylhexyl) phthalate (DEHP) can affect the male reproductive system in vertebrates, but the underlying molecular mechanism is still elusive. Therefore, in this study, we aimed to dig the in-depth mechanism of DEHP-induced reproductive toxicity on male zebrafish via testicular transcriptome using embryo exposed at the environmentally relevant concentration (ERC) of 100 μg/L for 111 days. Moreover, our results were further confirmed via in silico technique and bioassay experimental in vitro (cell lines) and in vivo (zebrafish). The results showed DEHP exposure could affect male spermatogenesis, altered gonad histology, and reduced egg fertilization rate. Transcriptome analysis identified 1879 significant differentially expressed genes enriched in the exposure group. Twenty-seven genes related to three pathways of reproduction behavior were further validated by qPCR. In silico molecular docking revealed that DEHP and its metabolism bind to the zebrafish progesterone receptor (Pgr), suggesting the potential disruption of DEHP to the normal Pgr signaling. To further validate it, a wild-type Pgr plasmid and its mutants on specific binding sites were constructed. The transfection and microinjection experiment demonstrated that these binding sites mutations of Pgr affected the expression levels of male reproductive toxicity. Taken together, our study provided new insight into the molecular mechanisms of male reproductive toxicity induced by DEHP, and Pgr may serve as an important target binding by DEHP pollution, which needs further study in the future.

Effect of rare earth element lanthanum on lipid deposition and Wnt10b signaling in the liver of male zebrafish

This paper investigates the effect of lanthanum (La) on lipid deposition and Wnt10b signaling in the liver of male zebrafish with exposure of 0, 10, 20, and 30 μmol/L La. It suggests that La can be accumulated in liver, and its treatments decrease the activities and gene expression of enzymes related to fatty acid synthesis. The levels of total cholesterol (TC), triglyceride (TG), and nonesterified fatty acids (NEFA) as well as the size of lipid droplets are decreased by La treatments. Moreover, La treatments affect the composition of fatty acids and the content of nutrient elements. Meanwhile, they also induce the gene expression of wnt10b, β-catenin, pparα, and pparγ, but inhibit gsk-3β gene expression in liver. Further study on the result of wnt10b gene interference shows that Wnt10b/β-catenin signaling plays a crucial role in the regulatory process of hepatic lipid deposition. Taken together, our observations suggest that La accumulation affects lipid deposition in the liver of male zebrafish, and Wnt10b signaling pathway may be involved in this process.

Cloning and characterization of AMP-activated protein kinase genes in Daphnia pulex: Modulation of AMPK gene expression in response to polystyrene nanoparticles

Energy metabolism is essential for almost all organisms. At the molecular level, adenosine monophosphate activated protein kinase (AMPK) plays a vital role in cellular energy homeostasis. Its molecular characterization in invertebrates, including Daphnia pulex, and the understanding of its role in response to environmental contaminants is limited. In this study, three subunits of AMPK (AMPKα, β, and γ) were cloned in D. pulex, and assigned the GenBank accession numbers MT536758, MT536759, and MT536760, respectively. Their full lengths were 2,000, 1,384, and 2594 bp, respectively, and contained open reading frames of 526, 274, and 580 amino acids, respectively. Bioinformatic analysis revealed that the three AMPK subunits all have features representative of the AMPK superfamily, and were correspondingly clustered with each orthologue branch. The three AMPK subunit genes, AMPKα, β, and γ, had the highest similarity to those of other organisms at 82%, 94%, and 71%, respectively. Nanoplastics significantly increased AMPKα expression, but decreased that of AMPKβ and γ. These results identified AMPKα, β, and γ in D. pulex, and showed that they all encode proteins with conserved functional domains. This study provides basic information on how three types of AMPK in aquatic organisms respond to environmental contaminants.

Dietary polystyrene nanoplastics exposure alters liver lipid metabolism and muscle nutritional quality in carnivorous marine fish large yellow croaker (Larimichthys crocea)

Nanoplastics (NPs) cause various adverse effects on marine fish. However, effects of dietary NPs exposure on liver lipid metabolism and muscle nutritional quality of carnivorous marine fish are not fully understood. In this study, a 21-day feeding test was conducted to simulate the food chain transfer of polystyrene nanoplastics (PS NPs) and then evaluate effects of different dietary PS NPs levels on the survival, growth performance, liver lipid metabolism, and muscle nutritional quality of large yellow croaker Larimichthys crocea. Results indicated that the survival and growth of large yellow croaker decreased with the increase of PS NPs levels. Moreover, PS NPs induced excessive liver lipid accumulation by down-regulating the expression of lipolysis-related genes and inhibiting the AMPK-PPARα signaling pathway. In vitro, PS NPs could be accumulated in hepatocytes, reduce cell viability, and disrupt lipid metabolism of hepatocytes. Also, we found for the first time that PS NPs altered fatty acid composition and texture of fish muscle by enhancing oxidative stress and disrupting lipid metabolism. Overall, this study indicated that PS NPs induced liver lipid deposition by inhibiting lipolysis, and demonstrated that PS NPs altered the nutritional quality of fish, which might cause potential health effects for human consumers.

Metformin Weakens the Angiogenic Potential of Human Bone Marrow Mesenchymal Stem Cells (hBMSCs) by Activating Mammalian Target of Rapamycin (mTOR) Signaling

To study metformin’s effect on the angiogenesis of human bone marrow mesenchymal stem cells (hBMSCs). Cells were treated with metformin (0.5, 1, 10, 50, 100, 200 and 500 βM) for 14 days, followed by analysis of cell viability and total fatty acid profile, level of VEGFR-2, Tie-2, VE-Cadherin and mTOR signaling protein, cell differentiation by microtubule generation and cell migration by transwell assay. Metformin dose dependently decreased cell survival and reduced palmitate, oleate, stearate and linoleate content. In addition, it downregulated VEGFR-2 and Tie-2 and decreased the angiogenic potential of BMSCs and down-regulated VE-Cadherin. Western blot and PCR analysis showed that metformin activated mTOR signaling and up-regulated the transcription of autophagyrelated genes. Metformin can reduce BMSCs angiogenic potential by regulating mTOR signal pathway.

New insights into bisphenols induced obesity in zebrafish (Danio rerio): Activation of cannabinoid receptor CB1

Bisphenols (BPs), as widely used plastic additives, penetrate into our daily lives. BPs are considered endocrine disruptors and could potentially induce obesity. In this study, the effects of bisphenol A (BPA) and tetrabromobisphenol A (TBBPA) on food intake and lipid metabolism in zebrafish were determined. Moreover, the impact of BPA and TBBPA on the endocannabinoid system (ECS) of zebrafish was further explored by metabolomics, transcriptomics, and molecular docking analysis. Here we show that exposure to BPA and TBBPA at concentrations commonly found in the environment (20, 100, and 500 μg/L) led to hyperphagia and obesity in adult male zebrafish. Metabolomics and histopathological analysis revealed significant lipid accumulation in the liver of zebrafish exposed to BPA and TBBPA. The expression of ECS-related genes, in conjunction with RNA-Seq results, further indicated that BPA and TBBPA increased appetite and induced obesity by activating cannabinoid receptor type 1(CB1). Furthermore, molecular docking revealed that six representative BPs including BPA and TBBPA could bind to the CB1 receptor. Collectively, these findings indicate that CB1 may be a potential target for BPs to induce obesity.

Evidence of feminization in seahorses from a tropical estuary

Intersex has been reported regularly in wild populations of gonochoristic fish. The authors investigated the possible feminization of seahorses in a population of Hippocampus reidi in Brazil, as well as report a case of a brood pouch reduction after reproductive stimuli. The female seahorses of this population showed two kinds of morphological anomalies. The proportion of the animals affected in the study population was consistent and was uncorrelated with the sex ratio. The study indicates the changes in the sexual profile of the individual.

Endocrine disrupting chemicals and metabolic disorders in the liver: What if we also looked at the female side?

Endocrine disrupting chemicals (EDCs) are linked to the worldwide epidemic incidence of metabolic disorders and fatty liver diseases, which affects quality of life and represents a high economic cost to society. Energy homeostasis exhibits strong sexual dimorphic traits, and metabolic organs respond to EDCs depending on sex, such as the liver, which orchestrates both drug elimination and glucose and lipid metabolism. In addition, fatty liver diseases show a strong sexual bias, which in part could also originate from sex differences observed in gut microbiota. The aim of this review is to highlight significant differences in endocrine and metabolic aspects of the liver, between males and females throughout development and into adulthood. It is also to illustrate how the male and female liver differently cope with exposure to various EDCs such as bisphenols, phthalates and persistent organic chemicals in order to draw attention to the need to include both sexes in experimental studies. Interesting data come from analyses of the composition and diversity of the gut microbiota in males exposed to the mentioned EDCs showing significant correlations with hepatic lipid accumulation and metabolic disorders but information on females is lacking or incomplete. As industrialization increases, the list of anthropogenic chemicals to which humans will be exposed will also likely increase. In addition to strengthening existing regulations, encouraging populations to protect themselves and promoting the substitution of harmful chemicals with safe products, innovative strategies based on sex differences in the gut microbiota and in the gut-liver axis could be optimistic outlook.

Screening of potential oestrogen receptor α agonists in pesticides via in silico, in vitro and in vivo methods

In modern agricultural management, the use of pesticides is indispensable. Due to their massive use worldwide, pesticides represent a latent risk to both humans and the environment. In the present study, 1056 frequently used pesticides were screened for oestrogen receptor (ER) agonistic activity by using in silico methods. We found that 72 and 47 pesticides potentially have ER agonistic activity by the machine learning methods random forest (RF) and deep neural network (DNN), respectively. Among endocrine-disrupting chemicals (EDCs), 14 have been reported as EDCs or ER agonists by previous studies. We selected 3 reported and 7 previously unreported pesticides from 76 potential ER agonists to further assess ERα agonistic activity. All 10 selected pesticides exhibited ERα agonistic activity in human cells or zebrafish. In the dual-luciferase reporter gene assays, six pesticides exhibited ERα agonistic activity. Additionally, nine pesticides could induce mRNA expression of the pS2 and NRF1 genes in MCF-7 cells, and seven pesticides could induce mRNA expression of the vtg1 and vtg2 genes in zebrafish. Importantly, the remaining 48 out of 76 potential ER agonists, none of which have previously been reported to have endocrine-disrupting effects or oestrogenic activity, should be of great concern. Our screening results can inform environmental protection goals and play an important role in environmental protection and early warnings to human health.

Transcriptome analysis of gender-biased CYP genes in gonads of the sea cucumber Apostichopus japonicus

Gender differences in physiological characteristics are widespread in animals. Herein, differentially expressed genes (DEGs) in gonads of the sea cucumber Apostichopus japonicus were analysed by transcriptomics, and the results showed that 19,973 genes were commonly expressed in the males and females, 4186 were female-biased, and 2540 were male-biased, 4695 genes were up-regulated in the females and 3436 genes were up-regulated in the males. These DEGs were mainly associated with metabolism, including lipid metabolism, amino acid metabolism, nucleotide metabolism, energy metabolism, and cofactor and vitamin metabolism. 29 Cytochrome P450 (CYP) superfamily genes with gender differential expression were selected, and performed gene identification, phylogenetic, and functional analyses. The results indicated significant roles in multiple metabolic pathways, such as steroid hormone biosynthesis, ovarian steroidogenesis, cortisol synthesis and secretion, arachidonic acid metabolism, linoleic acid metabolism, and retinol metabolism. The findings provide insight into the molecular characteristics of physiological gender differences in sea cucumbers, and will help lay the foundation for the establishment of effective sea cucumber breeding technologies.

Chronic exposure to PPCPs mixture at environmentally relevant concentrations (ERCs) altered carbohydrate and lipid metabolism through gut and liver toxicity in zebrafish

Pharmaceuticals and personal care products (PPCPs) have been widely distributed and posed ecotoxicological risks in the aquatic environment. This study aims to evaluate the toxic effects after chronic exposure to PPCPs mixture at the environment relevant concentrations (ERCs). Our results indicated that PPCPs induced serious metabolic effects by disturbing the carbohydrate and lipid metabolism pathways. Chronic exposure caused a significant reduction in the hepatosomatic index (HSI), the gut weight ratios, and histological alterations in liver and gut tissues. Further, exposure to the combined PPCPs disrupted the carbohydrate metabolism via significant upregulation of hk1, gk, pck1, and insr genes. The lipid metabolism was affected with higher ppars expression levels that increased the fatty acid β-oxidation and ultimately decreased the lipidogenesis. Moreover, the altered responses of the insulin growth factor (IGF) pathway more in male gut tissue than that of female revealed sex-dependent disturbance in the gut homeostasis induced by PPCPs mixture. In conclusion, chronic exposure to PPCPs mixtures at ERCs can induce developmental effects and metabolic dysfunction in both male and female fish. The consumption and environmental disposal of these PPCPs should be regulated to ensure ecological health and environmental safety.

Effects of BPA on zebrafish gonads: Focus on the endocannabinoid system

Bisphenol A (BPA), a monomer used for polycarbonate manufacture, has been widely reported as an endocrine-disrupting chemical (EDC). Among other alterations, BPA induces reproductive dysfunctionalities. Changes in the endocannabinoid system (ECS) have been recently shown to be associated with reproductive disorders. The ECS is a lipid-based signaling system (cannabinoid receptors, endocannabinoids and enzymatic machinery) involved in several physiological functions. The main goal of the present study was to assess the effects of two environmental concentrations of BPA (10 and 20 μg/L) on the ECS in 1-year old zebrafish gonads. In males, BPA increased the gonadosomatic index (GSI) and altered testicular levels of endocannabinoids as well as reduced the testicular area occupied by spermatogonia. In male liver, exposure to 20 μg/L BPA significantly increased vitellogenin (vtg) transcript levels. In female zebrafish, BPA altered ovarian endocannabinoid levels, elevated hepatic vtg mRNA levels as well as increased the percentage of vitellogenic oocytes in the ovaries. In conclusion, exposure to two environmentally relevant concentrations of BPA altered the ECS and consequently, gonadal function in both male and female zebrafish.