Effects of elevated temperature and different crystal structures of TiO2 nanoparticles on the gut microbiota of mussel Mytilus coruscus.

Coastal habitats are exposed to increasing pressure of nanopollutants commonly combined with warming due to the seasonal temperature cycles and global climate change. To investigate the toxicological effects of TiO2 nanoparticles (TiO2 NPs) and elevated temperature on the intestinal health of the mussels (Mytilus coruscus), the mussels were exposed to 0.1 mg/L TiO2 NPs with different crystal structures for 14 days at 20 °C and 28 °C, respectively. Compared to 20 °C, the agglomeration of TiO2 NPs was more serious at 28 °C. Exposure to TiO2 NPs led to elevated mortality of M. coruscus and modified the intestinal microbial community as shown by 16S rRNA sequence analysis. Exposure to TiO2 NPs changed the relative abundance of Bacteroidetes, Proteobacteria and Firmicutes. The relative abundances of putative mutualistic symbionts Tenericutes and Fusobacteria increased in the gut of M. coruscus exposed to anatase, which have contributed to the lower mortality in this group. LEfSe showed the combined stress of warming and TiO2 NPs increased the risk of M. coruscus being infected with potential pathogenic bacteria. This study emphasizes the toxicity differences between crystal structures of TiO2 NPs, and will provides an important reference for analyzing the physiological and ecological effects of nanomaterial pollution on bivalves under the background of global climate change.

Reduced toxic effects of nano­copper sulfate in comparison of bulk CuSO4 on biochemical parameters in the Rohu (Labeo rohita).

Considering the wide application of nanoparticles in various fields of life and growing concern regarding their toxic effects, the present study was designed with the aim to evaluate the potential risks of using copper sulfate nanoparticles (CuSO4-NPs) in comparison to bulk form. Nanoparticles of CuSO4, having mean size of 73 nm were prepared by ball milling method, and fingerlings of Labeo rohita were exposed to two levels, 20 and 100 µg L-1 of CuSO4 in both bulk and nano forms for 28 days and their comparative effects on the metallothioneins (MTs), heat shock proteins 70 (HSP 70), lipid profile, cholesterol (CHOL) and triglyceraldehyde (TG) levels, activities of some metabolic enzymes Alanine transaminase (ALT), Aspartate transaminase (AST) Akaline phosphatase (ALP), and genes expressions of HSP-70, TNF-α and IL1-ß were investigated. CuSO4 showed the concentration and particle type dependent effects. The over expression of HSPs and MTs, significant decreases in CHOL, TG, low density lipid (LDL) levels and ALP activity, while significant increases in high density lipid (HDL)level as well as ALT and AST activities and HSP-70, TNF-α and IL1-ß expressions were observed in response to higher concentration of both bulk and nano form of copper sulfate. At lower concentration (20 µg L-1), however, only bulk form showed toxicity. Thus, low concentrations of CuSO4-NPs pose negligible threat to freshwater fish.

Physiological and histopathological effects of polystyrene nanoparticles on the filter-feeding fish Hypophthalmichthys molitrix.

Excessive use of plastics in daily life is causing plastic pollution in aquatic environment and threatening the aquatic life. Therefore, research on the plastic pollution in aquatic environment is crucial to understand its impact and develop effective solution for safeguarding aquatic life and ecosystem. The current study investigated the effects of water borne polystyrene nanoparticles (PS-NPs) on hemato-immunological indices, serum metabolic enzymes, gills, and liver antioxidant parameters, plasma cortisol level and histopathological changes in liver and gill tissues of the widely distributed fish Hypophthalmichthys molitrix. The fingerlings of H. molitrix were exposed to different concentrations (T1-0.5, T2-1.0, and T3-2.0 mg/L) of PS-NPs respectively for 15 days consecutively. Our results indicated the dose dependent negative effects of PS-NPs on the physiology and histopathology of H. molitrix. Immuno-hematological indices showed significant increase in WBCs count, phagocytic activity, and lysozyme activity, while decreased RBC count, Hct%, Hb level, total proteins, IgM, and respiratory burst activity were observed. The levels of antioxidant enzymes like SOD, CAT and POD showed the decreasing trends while metabolic enzymes (AST, ALT, ALP and LDH), LPO, ROS activities and relative expressions of SOD1, CAT, HIF1-α and HSP-70 genes increased with increased concentrations of PS-NPs. Moreover, blood glucose and cortisol levels also showed significant increasing trends with dose dependent manner. Histopathological examination indicated moderate to severe changes in the gills and liver tissues of the group treated with 2.0 mg/L of PS-NPs. Overall, the results showed the deleterious effects of PS-NPs on physiology, immunity, metabolism, and gene expressions of H. molitrix. It is concluded that particulate plastic pollution has deleterious effects on filter feeding fish, which might affect human health through food chain and particulate chemical toxicity.

Dietary exposure to nTiO2 reduces byssus performance of mussels under ocean warming.

Nano­titanium dioxide (nTiO2) is a widely used nanomaterial posing potential ecological risk for marine ecosystems that might be enhanced by elevated temperatures such as expected during climate change. nTiO2 may affect benthic filter feeders like mussels through waterborne exposures and via food chain due to the adsorption on/in algae. Mussel byssus are proteinaceous fibers secreted by byssal glands of the mussels for attachment. Byssus production and mechanical properties are sensitive to environmental stressors but the combined effects of warming and nTiO2 on byssus performance of mussels are unclear hampering our understanding of the predation and dislodgement risk of mussels under the multiple stressor scenarios. We explored the effects of a short-term (14-day) single and combined exposures to warming (28 °C) and 100 µg L-1 nTiO2 (including food co-exposure) on the byssus performance of the thick shell mussel Mytilus coruscus. The mechanical strength (measured as the breaking force) of the byssal threads was impaired by warming and nTiO2 (including food co-exposure), but the number and length of the byssal threads were increased. The mRNA expression levels of mussel foot proteins (mfp-3, mfp-5) and pre-collagens (preCOL-D, preCOL-P, preCOL-NG) were up-regulated to varying degrees, with the strongest effects induced by warming. This indicates that the physiological and molecular mechanisms of byssus secretion are plastic. However, downregulation of the mRNA expression of preCOL-D and preCOL-P under the combined warming and nTiO2 exposures indicate the limits of these plasticity mechanisms and suggest that the attachment ability and survival of the mussels may be impaired if the pollution or temperature conditions further deteriorate.

Combined toxic effects of nanoplastics and norfloxacin on mussel: Leveraging biochemical parameters and gut microbiota.

Antibiotics and nanoplastics (NPs) are among the two most concerned and studied marine emerging contaminants in recent years. Given the large number of different types of antibiotics and NPs, there is a need to apply efficient tools to evaluate their combined toxic effects. Using the thick-shelled mussel (Mytilus coruscus) as a marine ecotoxicological model, we applied a battery of fast enzymatic activity assays and 16S rRNA sequencing to investigate the biochemical and gut microbial response of mussels exposed to antibiotic norfloxacin (NOR) and NPs (80 nm polystyrene beads) alone and in combination at environmentally relevant concentrations. After 15 days of exposure, NPs alone significantly inhibited superoxide dismutase (SOD) and amylase (AMS) activities, while catalase (CAT) was affected by both NOR and NPs. The changes in lysozyme (LZM) and lipase (LPS) were increased over time during the treatments. Co-exposure to NPs and NOR significantly affected glutathione (GSH) and trypsin (Typ), which might be explained by the increased bioavailable NOR carried by NPs. The richness and diversity of the gut microbiota of mussels were both decreased by exposures to NOR and NPs, and the top functions of gut microbiota that were affected by the exposures were predicted. The data fast generated by enzymatic test and 16S sequencing allowed further variance and correlation analysis to understand the plausible driving factors and toxicity mechanisms. Despite the toxic effects of only one type of antibiotics and NPs being evaluated, the validated assays on mussels are readily applicable to other antibiotics, NPs, and their mixture.

Differential physiological response of marine and freshwater microalgae to polystyrene microplastics.

Effects of microplastics on microalgae have not been compared from different habitat. To answer this question, three marine microalgae species (Chlorella marined, Nannochloropsis oculate, and Phaeodactylum tricornutum) and two freshwater species (Chlorella vulgaris and Tetradesmus obliquus) were selected and exposed to the environment relevant concentrations of polystyrene microplastics. The results indicated that microplastics have a significant concentration effect on the growth of microalgae. The attachment of microalgae to microplastics surface and the aggregation of microalgae with each other were observed. Under exposure of microplastics, the photosynthesis of microalgae was inhibited while the antioxidant system was activated, indicating that microplastics had a negative impact on microalgae. At the end of exposure, the oxidative stress status caused by microplastics in marine microalgae were alleviated, but the antioxidant system of freshwater microalgae was still at high levels, indicating a stress response. In addition, integrated biomarker response (IBR) indicated that the effects of microplastics on freshwater microalgae were severer than marine microalgae, which might relate to their differences in removing reactive oxygen species (ROS) effectively and membrane structure. Our study provides a reliable data for understanding the complex effects of microplastics on microalgae, and especially for comparing the differential effects of microplastics among different microalgae.

Clinical application of PEAK PlasmaBlade to remove distal tracheal granulation in patients after tracheostomy.

OBJECTIVE: Tracheal granulation is one of the common long term complications in patients after tracheostomy. Hypertrophic tracheal granulation may cause airway obstruction and further operation may be required to recreate an airway. Distal tracheal granulation is clinically challenging because of its position and surgical field limitation. This retrospective case review study evaluated the outcomes of PEAK PlasmaBlade-assisted tracheal surgery in patients with distal tracheal granulation. METHODS: This study retrospectively reviewed patients with distal tracheal granulation following long-term tracheostomy. All patients received PEAK PlasmaBlade assistance tracheal surgery (PATS) between February 2013 and December 2019. The surgery was performed using the PEAK PlasmaBlade with TnA type tip, powered by a PULSAR Generator, and guided by a 45 ° rigid endoscope. Patients were regularly followed up for a minimum of 12 months. RESULTS: A total 21 patients had completed PATS. None of the patients experience immediate life-threatening complications during or after the procedure. All the 21 patients were free of recurrent obstructive granulation within 12 months after operation. CONCLUSION: PATS is practical, effective, and safe for distal tracheal granulation and can be performed by single surgeon. Furthermore, it is technically less demanding than other surgical approaches and it has a rapid learning curve.

Effects of Microplastics on Immune Responses of the Yellow Catfish Pelteobagrus fulvidraco Under Hypoxia.

Compared with marine organisms, research on microplastics (MPs) in freshwater organisms is still less although MPs have been widely found in the freshwater ecosystem. Hypoxia is a ubiquitous issue in freshwater aquaculture, and under such scenarios, the toxic effects of MPs on typical aquaculture fish need to be clarified. In this study, we studied the effects of MPs (polystyrene) on specific growth rate (SGR), hypoxia-inducible factor-1α (HIF-1α), tumor necrosis factor-α (TNF-α), interleukin-8 (IL-8), and interferon (IFN) in the yellow catfish (Pelteobagrus fulvidraco) under hypoxic conditions. After 15 days of exposure, the SGR was not affected by MPs or hypoxia. MPs significantly increased the expressions of HIF-1α and TNF-α but inhibited the expression of IFN at high concentration MPs under normoxia. However, hypoxia significantly inhibited the expression of IL-8 and TNF-α under high MP concentration and low MP concentration, respectively. In addition, MPs had significant concentration-dependent inhibitory effects on IFN under hypoxia. Surprisingly, a positive correction between HIF-1α and TNF-α was found in fish. Although hypoxia might alleviate the effects of MPs with low concentrations, the interaction of hypoxia and MPs aggravated the negative effects of MPs on immune factors at high concentration MPs. This study provided new insight into the complex effects of hypoxia and MPs on aquatic organisms, and future studies should focus on the cellular pathways of immune cells in fish. Given that MPs could induce the immune response in fish, considerations should be paid to the impacts of MPs on freshwater aquaculture, and hypoxia should be taken into consideration when evaluating the effects of MPs.

Oxidative stress induced by nanoplastics in the liver of juvenile large yellow croaker Larimichthys crocea.

There are many toxicological studies on microplastics, but little is known about the effect of nanoplastics (NPs). Here, we evaluated the oxidative stress responses induced by NPs (10, 104 and 106 particles/l) in juvenile Larimichthys crocea during 14-d NPs exposure followed by a 7-d recovery. After exposure, the activities of antioxidant enzymes (SOD, CAT, GPx) and MDA levels increased in the liver of fish at the highest NPs concentration. SOD and CAT activities remained elevated above the baseline after recovery under high-concentration NPs but returned to the baseline in two other NP treatments. Although lipid peroxidation in liver was reversible, juvenile fish in NPs treatments exhibited a lower survival rate than the control during both exposure and recovery. Furthermore, IBR value and PCA analysis showed the potential adverse effects of NPs. Considering that NPs can reduce the survival of fish juveniles, impacts of NPs on fishery productivity should be considered.

Microplastics aggravate the adverse effects of BDE-47 on physiological and defense performance in mussels.

The highly hydrophobic surfaces make microplastics a potential carrier of organic pollutants in the marine environment. In order to explore the toxic effects of polybrominated diphenyl ethers (BDE-47) combined with microplastics on marine organisms, we exposed the marine mussel Mytilus coruscus to micro-PS combined with BDE-47 for 21 days to determine the immune defense, oxidative stress and energy metabolism of the mussels. The results showed that the clearance rate (CR) of mussels exposed to single micro-PS, single BDE-47 or both was lower than control group. In general, compared to single BDE-47 exposure, the combination of micro-PS and BDE-47 significantly increased respiration rate (RR), activities of acid phosphatase (ACP) and alkaline phosphatase (ALP), reactive oxygen species (ROS) production and malondialdehyde (MDA) concentrations, but significantly decreased lactate dehydrogenase (LDH) activity and the relative expression of heat shock protein (Hsp70 and 90). Overall, combined stress has more adverse effects on defense performance and energy metabolism in mussels and micro-PS seem to exacerbate the toxicological effects of BDE-47. As microplastics pollution may deteriorate in the future, the health of mussels may be threatened in organically polluted environment, which eventually change the stability of the structure and function of intertidal ecosystem.