Parental exposure to sulfamethazine and nanoplastics alters the gut microbial communities in the offspring of marine madaka (Oryzias melastigma)

MicroRNA and Gut Microbiota Alter Intergenerational Effects of Paternal Exposure to Polyethylene Nanoplastics

Nanoplastics (NPs), as emerging contaminants, have been shown to cause testicular disorders in mammals. However, whether paternal inheritance effects on offspring health are involved in NP-induced reproductive toxicity remains unclear. In this study, we developed a mouse model where male mice were administered 200 nm polyethylene nanoparticles (PE-NPs) at a concentration of 2 mg/L through daily gavage for 35 days to evaluate the intergenerational effects of PE-NPs in an exclusive male-lineage transmission paradigm. We observed that paternal exposure to PE-NPs significantly affected growth phenotypes and sex hormone levels and induced histological damage in the testicular tissue of both F0 and F1 generations. In addition, consistent changes in sperm count, motility, abnormalities, and gene expression related to endoplasmic reticulum stress, sex hormone synthesis, and spermatogenesis were observed across paternal generations. The upregulation of microRNA (miR)-1983 and the downregulation of miR-122-5p, miR-5100, and miR-6240 were observed in both F0 and F1 mice, which may have been influenced by reproductive signaling pathways, as indicated by the RNA sequencing of testis tissues and quantitative real-time polymerase chain reaction findings. Furthermore, alterations in the gut microbiota and subsequent Spearman correlation analysis revealed that an increased abundance of Desulfovibrio (C21_c20) and Ruminococcus (gnavus) and a decreased abundance of Allobaculum were positively associated with spermatogenic dysfunction. These findings were validated in a fecal microbiota transplantation trial. Our results demonstrate that changes in miRNAs and the gut microbiota caused by paternal exposure to PE-NPs mediated intergenerational effects, providing deeper insights into mechanisms underlying the impact of paternal inheritance.

Understanding the links between micro/nanoplastics-induced gut microbes dysbiosis and potential diseases in fish: A review

At present, the quantity of micro/nano plastics in the environment is steadily rising, and their pollution has emerged as a global environmental issue. The tendency of their bioaccumulation in aquatic organisms (especially fish) has intensified people's attention to their persistent ecotoxicology. This review critically studies the accumulation of fish in the intestines of fish through active or passive intake of micro/nano plastics, resulting in their accumulation in intestinal organs and subsequent disturbance of intestinal microflora. The key lies in the complex toxic effect on the host after the disturbance of fish intestinal microflora. In addition, this review pointed out the characteristics of micro/nano plastics and the effects of their combined toxicity with adsorbed pollutants on fish intestinal microorganisms, in order to fully understand the characteristics of micro/nano plastics and emphasize the complex interaction between MNPs and other pollutants. We have an in-depth understanding of MNPs-induced intestinal flora disorders and intestinal dysfunction, affecting the host's systemic system, including immune system, nervous system, and reproductive system. The review also underscores the imperative for future research to investigate the toxic effects of prolonged exposure to MNPs, which are crucial for evaluating the ecological risks posed by MNPs and devising strategies to safeguard aquatic organisms.

High levels of cadmium altered soil archaeal activity, assembly, and co-occurrence network in volcanic areas

Soil microbial communities are essential to biogeochemical cycles. However, the responses of microorganisms in volcanic soil with high heavy metal levels remain poorly understood. Here, two areas with high levels of cadmium (Cd) from the same volcano were investigated to determine their archaeal composition and assembly. In this study, the Cd concentrations (0.32-0.38 mg/ kg) in the volcanic soils exceeded the standard risk screening values (GB15618-2018) and correlated with archaeal communities strongly (P < 0.05). Moreover, the area with elevated levels of Cd (periphery) exhibited a greater diversity of archaeal species, albeit with reduced archaeal activity, compared to the area with lower levels of Cd (center). Besides, stochastic processes mainly governed the archaeal communities. Furthermore, the co-occurrence network was simplest in the periphery. The proportion of positive links between taxa increased positively with Cd concentration. Moreover, four keystone taxa (all from the family Nitrososphaeraceae) were identified from the archaeal networks. In its entirety, this study has expanded our comprehension of the variations of soil archaeal communities in volcanic areas with elevated cadmium levels and serves as a point of reference for the agricultural development of volcanic soils in China.

Exposure to polystyrene nanoplastics induces apoptosis, autophagy, histopathological damage, and intestinal microbiota dysbiosis of the Pacific whiteleg shrimp (Litopenaeus vannamei)

Nanoplastics (NPs) are widely distributed environmental pollutants that can disrupt intestinal immunity of crustaceans. In this study, the effects of NPs on gut immune enzyme activities, cell morphology, apoptosis, and microbiota diversity of Litopenaeus vannamei were investigated. L. vannamei was exposed to five concentrations of NPs (0, 0.1, 1, 5, and 10 mg/L) for 28 days. The results showed that higher concentrations of NPs damaged the intestinal villi, promoted formation of autophagosomes, increased intestinal non-specific immunoenzyme activities, and significantly increased apoptosis at 10 mg/L. In response to exposure to NPs, the expression levels of ATG3, ATG4, ATG12, Caspase-3, p53, and TNF initially increased and then decreased. In addition, the concentration of NPs was negatively correlated to the expression levels of the genes of interest and intestinal enzyme activities, suggesting that exposure to NPs inhibited apoptosis and immune function. The five dominant phyla of the gut microbiota (Proteobacteria, Firmicutes, Bacteroidetes, Acidobacteria, and Actinomycetes) were similar among groups exposed to different concentrations of NPs, but the abundances tended to differ. Notably, exposure to NPs increased the abundance of pathogenic bacteria. These results confirm that exposure to NPs negatively impacted intestinal immune function of L. vannamei. These findings provide useful references for efficient breeding of L. vannamei.

Responses of the intestinal microbiota to exposure of okadaic acid in marine medaka Oryzias melastigma

It is still limited that how the microalgal toxin okadaic acid (OA) affects the intestinal microbiota in marine fishes. In the present study, adult marine medaka Oryzias melastigma was exposed to the environmentally relevant concentration of OA (5 μg/L) for 10 days, and then recovered in fresh seawater for 10-days depuration. Analysis of taxonomic composition and diversity of the intestinal microbiota, as well as function prediction analysis and histology observation were carried out in this study. Functional prediction analysis indicated that OA potentially affected the development of colorectal cancer, protein and carbohydrate digestion and absorption functions, and development of neurodegenerative diseases like Parkinson's disease, which may be associated with changes in Proteobacteria and Firmicutes in marine medaka. Significant increases of C-reactive protein (CRP) and inducible nitric oxide synthase (iNOS) levels, as well as the changes of histology of intestinal tissue demonstrated that an intestinal inflammation was induced by OA exposure in marine medaka. This study showed that the environmental concentrations of OA could harm to the intestinal microbiota thus threatening the health of marine medaka, which hints that the chemical ecology of microalgal toxins should be paid attention to in future studies.

Surface functional groups on nanoplastics delay the recovery of gut microbiota after combined exposure to sulfamethazine in marine medaka (Oryzias melastigma)

Nanoplastics can interact with antibiotics, altering their bioavailability and the ensuing toxicity in marine organisms. It is reported that plain polystyrene (PS) nanoplastics decrease the bioavailability and adverse effects of sulfamethazine (SMZ) on the gut microbiota in Oryzias melastigma. However, the influence of surface functional groups on the combined effects with SMZ remains largely unknown. In this study, adult O. melastigma were fed diet amended with 4.62 mg/g SMZ and 3.65 mg/g nanoplastics (i.e., plain PS, PS-COOH and PS-NH2) for 30 days (F0-E), followed by a depuration period of 21 days (F0-D). In addition, the eggs produced on the last day of exposure were cultured under standard protocols without further exposure for 2 months (F1 fish). The results showed that the alpha diversity or the bacterial community of gut microbiota did not differ among the SMZ + PS, SMZ + PS-COOH, and SMZ + PS-NH2 groups in the F0-E and F1 fish. Interestingly, during the depuration, a clear recovery of gut microbiota (e.g., increases in the alpha diversity, beneficial bacteria abundances and network complexity) was found in the SMZ + PS group, but not for the SMZ + PS-COOH and SMZ + PS-NH2 groups, indicating that PS-COOH and PS-NH2 could prolong the toxic effect of SMZ and hinder the recovery of gut microbiota. Compared to plain PS, lower egestion rates of PS-COOH and PS-NH2 were observed in O. melastigma. In addition, under the simulated fish digest conditions, the SMZ-loaded PS-NH2 was found to desorb more SMZ than the loaded PS and PS-COOH. These results suggested that the surface -COOH and -NH2 groups on PS could influence their egestion efficiency and the adsorption/desorption behavior with SMZ, resulting in a long-lasting SMZ stress in the gut during the depuration phase. Our findings highlight the complexity of the carrier effect and ecological risk of surface-charged nanoplastics and the interactions between nanoplastics and antibiotics in natural environments.

Potential nervous threat of nanoplastics to Monopterus albus: Implications from a metabolomics study

Nanoplastics, as a new class of environmental pollutants, have been frequently detected in environmental media and organisms. Monopterus albus (M. albus) is an important economic aquatic product with a high dietary consumption. However, the potential biological effects of nanoplastics on M. albus remain unknown. In this study, the effects of polystyrene nanoplastics (PS-NPs) at different concentrations (0, 0.5, 1, 5 and 10 mg/L) on M. albus were investigated using an untargeted metabolomics approach. The results showed that 59, 44, 24, and 31 individual differential metabolites and 16, 9, 6, and 2 significant differential metabolic pathways were significantly changed in 0.5, 1, 5, and 10 mg/L respectively, indicating the greater effect of PS-NPs at the relatively low concentrations. After further analysis, there are four same significant differential metabolic pathways for the 0.5 and 1 mg/L groups, i.e., ABC transporters, cAMP signaling pathway, Neuroactive ligand-receptor interaction, and Synaptic vesicle cycle. In addition, there was one mutual differential metabolic pathway (Neuroactive ligand-receptor interaction) among the four groups, indicative of the probably universal nervous influence of nanoplastics on M. albus. In a word, the current work suggests that PS-NPs might affect the nervous systems of M. albus through disturbing their liver metabolism, and nanoplastics at relatively low concentrations may possess a greater effect, which provides significant information for assessing the toxic effect and exposure risk of nanoplastics to organisms in aquatic environment.

Nanoplastics enhance the intestinal damage and genotoxicity of sulfamethoxazole to medaka juveniles (Oryzias melastigma) in coastal environment

Antibiotics and nanoplastics are widely detected in the coastal ecosystem. However, the transcriptome mechanism elucidating the effect of antibiotics and nanoplastics co-exposure on the gene expression of aquatic organisms in coastal environment is still unclear. Here, single and joint effects of sulfamethoxazole (SMX) and polystyrene nanoplastics (PS-NPs) on the intestinal health and gene expression of medaka juveniles (Oryzias melastigma), which live in coastal environment, were investigated. The SMX and PS-NPs co-exposure decreased intestinal microbiota diversity compared to the PS-NPs, and caused more adverse effect on the intestinal microbiota composition and intestinal damage compared to the SMX, indicating that PS-NPs might enhance the toxicity of SMX on the medaka intestine. The increased abundance of Proteobacteria in the intestine was observed in the co-exposure group, which might induce the intestinal epithelium damage. In addition, the differentially expressed genes (DEGs) were mainly involved in the drug metabolism-other enzymes, drug metabolism-cytochrome P450, metabolism of xenobiotics by cytochrome P450 pathways in visceral tissue after the co-exposure. The expression of the host immune system genes (e.g., ifi30) could be associated with the increased pathogens in intestinal microbiota. This study is useful for understanding the toxicity effect of antibiotics and NPs on aquatic organisms in coastal ecosystem.

Bisphenol A decreases the developmental toxicity and histopathological alterations caused by polystyrene nanoplastics in developing marine medaka Oryzias melastigma

Nanoplastics (NPs) are emerging pollutants posing risks to marine biota and human health due to their small size and high bioavailability. However, there are still knowledge gaps regarding effects of co-existing pollutants on NPs toxicity to marine organisms at their respective environmentally relevant concentrations. Herein we investigated developmental toxicity and histopathological alterations caused by co-exposure of polystyrene nanoplastics (PS-NPs) and bisphenol A (BPA) to marine medaka, Oryzias melastigma. Embryos at 6 h post-fertilization were exposed to 50-nm PS-NPs (55 μg/L) or BPA (100 μg/L) or co-exposed to a combination of both. Results showed that PS-NPs exhibited decreased embryonic heart rate, larval body length, and embryonic survival as well as larval deformities such as hemorrhaging and craniofacial abnormality. When co-exposed, BPA mitigated all the adverse developmental effects caused by PS-NPs. PS-NPs also led to an increase in histopathological condition index of liver with early inflammatory responses, while co-exposure of BPA with PS-NPs did not. Our data suggest that the toxicity reduction of PS-NPs in the presence of BPA might result from the decreased bioaccumulation of PS-NPs caused by the interaction between BPA and PS-NPs. This study unveiled the impact of BPA on the toxicity of nanoplastics in marine fish during early developmental stages and highlight the need of more research on the long-term effects of complex mixtures in the marine environment by applying omics approaches to better understand the toxicity mechanism.

Nanoplastic exposure inhibits feeding and delays regeneration in a freshwater planarian

The concentration of nanoplastics (NPs) is expected to increase in aquatic environments thus potentially threatening freshwater organisms through interactions with plastic particles that variously float, circulate in the water column or sink into the benthos. Studies into the mechanisms of any NP effects are still scarce, particularly with respect to the regenerative ability of biota for which there is no recognised model organism. The present study therefore aimed to investigate behavioural and regeneration responses of the freshwater planarian Girardia tigrina after 10 days exposed to along a gradient 0.01-10 mg/L of poly (styrene-co-methyl methacrylate) NPs (∼426 ± 175 nm). Exposure to NPs induced a significant reduction in planarian feeding rate even at low concentrations (LOEC of 0.01 mg/L), while head regeneration was delayed in a clear dose response way (LOEC of 0.1 mg/L for blastema length). Planaria locomotion assessed was not affected. Our results highlight the potential adverse effects of exposure to poly (styrene-co-methyl methacrylate) NPs and show that feeding behaviour and regeneration of a freshwater benthic organism can be indicators of the resulting toxicity. Planarians are becoming widely used model organisms in ecotoxicology and can help to address potential effects of plastic polymers on regeneration.

Polylactic acid (PLA), polyethylene terephthalate (PET), and polystyrene (PS) microplastics differently affect the gut microbiota of marine medaka (Oryzias melastigma) after individual and combined exposure with sulfamethazine

Microplastics and the antibiotic sulfamethazine (SMZ) are two prevalent pollutants in regions with high human activity, particularly in coastal marine environments. In this study, the individual and joint effects of microplastics (i.e., the bio-based microplastics polylactic acid (PLA), the petroleum-based microplastics polyethylene terephthalate (PET), and the petroleum-based microplastics polystyrene (PS) at 0.5 and 5 mg/g) and sulfamethazine (SMZ, at 5 mg/g) on the gut microbiota of marine medaka (Oryzias melastigma) via dietary route were investigated. For the individual microplastics exposure, two petroleum-based microplastics PET and PS significantly decreased the alpha diversity and the complexity of co-occurrence networks of gut microbiota. Differently, the adverse effects caused by the bio-based microplastic PLA were more modest, suggesting that PLA was less hazardous than PET and PS. For the combined exposure, SMZ alone dramatically impaired the homeostasis of gut microbiota by decreasing the alpha diversity and the complexity of co-occurrence networks, while the presence of PLA or PET alleviated these adverse effects caused by SMZ. Interestingly, such an alleviation effect was not observed in the SMZ + PS groups, suggesting that different types of microplastics might exhibit distinct joint effects with SMZ. Our findings contribute to a better understanding of the ecological risk of different types of microplastics to marine ecosystems, especially in a scenario of combined pollution with antibiotics.

Toxicity of nanoplastics to aquatic organisms: Genotoxicity, cytotoxicity, individual level and beyond individual level

Due to the small size, high mobility and large surface area, nanoplastics (NPs) showed high potential risks to aquatic organisms. This paper reviews the toxicity of NPs to aquatic organism at various trophic levels including bacteria, plankton (algae), zooplankton, benthos, and nekton (fish). The effects at individual level caused by NPs were explained and proved by cytotoxicity and genotoxicity, and the toxicity of NPs beyond individual level was also illustrated. The toxicity of NPs is determined by the size, dosage, and surface property of NPs, as well as environmental factors, the presence of co-contaminants and the sensitivity of tested organisms. Furthermore, the joint effects of NPs with other commonly detected pollutants such as organic pollutants, metals, and nanoparticles etc. were summarized. In order to reflect the toxicity of NPs in the real natural environment, studies on toxicity assessment of NPs with the coexistence of various environmental factors and contaminants, particularly under the concentrations in natural environment are suggested.

Polystyrene micro- and nano-particle coexposure injures fetal thalamus by inducing ROS-mediated cell apoptosis

The adverse effects of plastic on adult animal and human health have been receiving increasing attention. However, its potential toxicity to fetuses has not been fully elucidated. Herein, biodistribution of polystyrene (PS) particles was determined after the maternal mice were orally given PS micro- and/or nano-particles with and without surface modifications during gestational days 1 to 17. The results showed that PS microplastics (MPs) and nanoparticles (NPs) mainly emerged in the alimentary tract, brain, uterus, and placenta in maternal mice, and only the latter infiltrated into the fetal thalamus. PS NPs and carboxyl-modified NPs induced differentially expressed genes mainly enriched in oxidative phosphorylation and GABAergic synapse. Maternal administration of PS particles during gestation led to anxiety-like behavior of the progenies and their γ-aminobutyric acid (GABA) reduction in the prefrontal cortex and amygdala at Week 8. N-Acetylcysteine (NAC), an antioxidant, alleviated PS particles-induced oxidative injury in the fetal brain and rescued the anxiety-like behavior of the progenies. Additionally, PS nanoparticles caused excessive ROS and apoptosis in neuronal cell lines, which were prevented by glutathione supplementation. These results suggested that PS particles produced a negative effect on fetuses by inducing oxidative injury and suppressing GABA synthesis in their brain. The findings contribute to estimating the risk for PS particles to human and animal health.

Single and combined effects of antibiotics and nanoplastics from surgical masks and plastic bottles on pathogens

Over the last decade, pollution of plastics and antibiotics has increased in its threat to the environment and human health. However, very limited information is available concerning impact of co-presence of plastics and antibiotics on environment and human health. Moreover, the potential ingestion and inhalation of nano(micro)plastics due to the disposable materials has dramatically increased. With the outbreak and spread of the COVID-19 in the world, disposable surgical masks and plastic bottles have been widely used by the public, and their rapid use and improper dispensing can cause to increase plastic pollution risk on human. However, impacts of co-presence of nano(micro)plastics and antibiotics on pathogens have yet been demonstrated. Therefore, this study aims to investigate the impact the individual and combined influences of nano-sized plastics (surgical mask and plastic bottles) and antibiotics (amoxicillin and spiramycin) towards the main susceptible bacterium (Staphylococcus epidermidis, Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa) by microbial activity, biofilm formation and their biochemical characteristics. The results showed that antimicrobial efficiencies of the tested antibiotics were reduced (approximately 10-98%) with the plastics. Moreover, the biochemical pathways of the microbial activity changed by the plastics entrance. Polymer structure and sorption play the role on the reduction in the inhibition of pathogens. In the meantime, the biofilm formation changed and characteristic of the extracellular polymeric substance with the co-presence of plastics and antibiotics mostly depended on the polymer structure, exposure time and sorption.

Potential involvement of the microbiota-gut-brain axis in the neurotoxicity of triphenyl phosphate (TPhP) in the marine medaka (Oryzias melastigma) larvae

Triphenyl phosphate (TPhP), a prevalent pollutant in the aquatic environment, has been reported to induce neurotoxicity (e.g., a suppression in locomotor activity) in fish larvae, posing a great threat to fish populations. However, the underlying mechanism was not fully revealed. In this study, the Oryzias melastigma larvae (21 dph) were exposed to waterborne TPhP (20 and 100 μg/L) for 7 days and a decreased locomotor activity was found. After exposure, the brain transcriptome and communities of gut microbiota were investigated to explore the potential mechanism underlying the suppressed locomotor activity by TPhP. The results showed that 1160 genes in the brain were dysregulated by TPhP, of which 24 genes were identified as being highly associated with the neural function and development (including nerve regeneration, neuronal growth and differentiation, brain ion homeostasis, production of neurotransmitters and etc), suggesting a general impairment in the central nervous system. Meanwhile, TPhP caused disorders in the gut microbiota. The relative abundance of Gammaproteobacteria and Alphaproteobacteria, which can influence the brain functions of host via the microbiota-gut-brain axis, were significantly altered by TPhP. Furthermore, the Redundancy analysis (RDA) revealed positive correlations between the intestinal genera Ruegeria, Roseivivax and Nautella and the dysregulated brain genes by TPhP. These results suggest that TPhP might impair the central nervous system of the O. melastigma larvae not only directly but also through the microbiota-gut-axis (indirectly), contributing to the suppressed locomotor activity. These findings enrich our mechanistic understanding of the toxicity of TPhP in fish larvae and shed preliminary light on the involvement of microbiota-gut-brain axis in the neurotoxicity of environmental pollutants.

Occurrence of antibiotics and antibiotic resistance genes in cultured prawns from rice-prawn co-culture and prawn monoculture systems in China

Antibiotics and antibiotic resistance genes (ARGs) in the aquatic environment have raised great concerns, as the deleterious effects of residual antibiotics and the emergence of ARGs are challenges to aquaculture. This study analyzed feed, water, sediment and prawns' tissues from six culture ponds (integrated culture: rice-prawn pond; monoculture: prawn pond) in Tianjin, Northeast China. Eighteen types of antibiotics were detected in all ponds, which conferring to four classes of antibiotics including sulfonamides, tetracyclines, fluoroquinolones, macrolides. The mean log bioaccumulation factor (BAF) values for five antibiotics were analyzed in the hepatopancreas, muscle, and plasma, and we found the maximum Log BAF (1.45) for enrofloxacin in prawn plasma. Correlation analysis of antibiotic concentrations between the plasma and the other two tissues indicated that enrofloxacin, norfloxacin, and erythromycin levels in the hepatopancreas and muscle can be predicted by their plasma concentrations. We also conducted a hazard quotient analysis and found that the risk to human health of eating antibiotic-exposed prawns from the two types of aquaculture method was relatively low. Compared with monoculture, rice-prawn co-culture could significantly decrease the abundance of ARGs; additionally, significant correlations were detected among ARGs, antibiotics, and non-antibiotic environmental factors (e.g., total nitrogen, total ammonia nitrogen, and chemical oxygen demand) in prawn. The present study indicated that the rice-prawn co-culture system is more effective than monoculture for mitigating the bioaccumulation of antibiotics and the occurrence of ARGs in prawn.

Subchronic toxicity of dietary sulfamethazine and nanoplastics in marine medaka (Oryzias melastigma): Insights from the gut microbiota and intestinal oxidative status

Antibiotics and nanoplastics are two prevalent pollutants in oceans, posing a great threat to marine ecosystems. As antibiotics and nanoplastics are highly bioconcentrated in lower trophic levels, evaluating their impacts on marine organisms via dietary exposure route is of great importance. In this study, the individual and joint effects of dietborne sulfamethazine (SMZ) and nanoplastic fragments (polystyrene, PS) in marine medaka (Oryzias melastigma) were investigated. After 30 days of dietary exposure, 4.62 mg/g SMZ decreased the Chao1 index (60.86% for females and 26.85% for males) and the Shannon index (68.95% for females and 65.05% for males) and significantly altered the structure of gut microbial communities in both sexes. The female fish exposed to 4.62 mg/g SMZ exhibited higher intestinal sod (43.5%), cat (38.5%) and gpx (39.6%) transcripts, indicating oxidative stress in the gut. PS alone at 3.45 mg/g slightly altered the composition of the gut microbiota. Interestingly, the mixture of SMZ and PS caused more modest effects on the gut microbiota and intestinal antioxidant physiology than the SMZ alone, suggesting that the presence of PS might alleviate the intestinal toxicity of SMZ in a scenario of dietary co-exposure. This study helps better understand the risk of antibiotics and nanoplastics to marine ecosystems.