First insights into region-specific lipidome alterations of prefrontal cortex and hippocampus of mice exposed chronically to microcystins

Spatiotemporal dynamics of microcystin contamination in fish across the Lake Chaohu basin under the Yangtze River ten-year fishing ban: Ecological and human health implications

Microcystins (MCs), produced by harmful cyanobacterial blooms, pose a threat to aquatic ecosystems and public health in the Yangtze River basin, including Lake Chaohu, which implemented a ten-year fishing ban in 2021 for ecological restoration. This study provides the first basin-wide assessment of MC contamination in fish muscle tissues from Lake Chaohu and its major tributaries during the ban's initial phase (2022-2023), with comparisons to pre-ban data. Using UHPLC-MS/MS, we quantified MC-LR and MC-RR in fish from four trophic levels (planktivorous, omnivorous, herbivorous, and carnivorous). Results revealed that MC-RR was the predominant variant, and planktivorous fish exhibited the highest MC levels, followed by omnivorous, herbivorous, and carnivorous species, reflecting dynamics of trophic transfer. Overall, fish MC concentrations were significantly lower during the ban compared to pre-ban levels, demonstrating positive initial effects. Seasonal analysis revealed higher MC levels in warmer seasons, but detectable MCs persisted during cold seasons, reflecting ongoing contamination. Spatially, while fish in the lake exhibited higher MC concentrations, contamination was also detected in riverine fish, highlighting the basin-wide spread. Despite a lower overall health risk from fish consumption relative to the pre-ban period, high consumption of planktivorous species, especially during warm seasons and in lake regions, may still pose potential health risks. Additionally, MCs likely pose ecological risks to fish populations. These findings provide a crucial baseline for evaluating the long-term effectiveness of the fishing ban and underscore the need for integrated watershed management to safeguard both ecological and public health.

Nanoconfinement Effect and Nanozyme Catalysis Enhance ILu/HOF-14 Electrochemiluminescence for Biosensing

A low collision frequency and an insufficient number of free radicals are the main problems leading to the low electroluminescence (ECL) efficiency of luminol and its derivatives. In order to solve the above issues, this work used nanoconfinement combined with nanozyme catalysis to significantly enhance the ECL efficiency. We assembled isoluminol (ILu) into the hydrogen-bonded organic framework HOF-14 and prepared a novel ECL emitter ILu/HOF-14 for the first time. Surprisingly, compared with the ILu/H2O2 system, the ECL signal of ILu/HOF-14/H2O2 was increased by 33 times. This was because the porous structure of HOF-14 effectively limited the movement of free radicals and increased their collision frequency. Therefore, the reaction rate between free radicals was significantly improved to achieve an ECL signal amplification. To further increase the number of free radicals, we introduced hybrid nanozyme Zn SAC@CuO2 NPs with superior peroxidase (POD)-like activity. It could effectively catalyze the coreactant H2O2 to produce a large amount of ROS (OH• and O2•-), accelerating the reaction rate of ILu with ROS and further improving the ECL signal. Based on the above research, a novel dual-mode biosensing and imaging platform was constructed to detect microcystin-LR (MC-LR). We used the nonspecific trans-cleavage activity of the CRISPR-Cas12a system to enhance the dynamic continuity and signal amplification capability of this biosensing platform, further improving the detection sensitivity and broadening the avenues of molecular diagnostic strategies.

Microcystin-LR induces fatty liver metabolic disease in zebrafish through the PPARα-NOD1 pathway: In vivo, in vitro, and in silico investigations

Hepatic lipid metabolism dysfunction caused by cyanobacteria bloom-released microcystin-LR (MC-LR) contributes to the development of nonalcoholic fatty liver disease and nonalcoholic steatohepatitis (NASH), thereby severely impacting the health and safety of animals and humans. In this study, the effects and mechanisms of different environmental concentrations of MC-LR (0, 0.1, 1, and 10 μg/L) on fatty liver metabolic disease in zebrafish were investigated using in vivo, in vitro, and in silico models. Exposure to 10 μg/L of MC-LR-induced NASH in zebrafish, characterized by hepatic steatosis, toxic saturated fatty acid (SFA) accumulation, and inflammation. Analyses of the liver transcriptome, molecular docking, molecular dynamics simulation, and in vitro experiments indicated that PPARα might be a key molecular target in MC-LR-induced steatosis and in toxic-SFA accumulation. The results obtained from molecular docking, molecular dynamics simulation, and NOD1-inhibitor experiments further revealed that MC-LR-derived SFAs, such as palmitic acid, could target the NOD1 protein to initiate hepatitis in zebrafish. The benchmark dose model identified palmitic acid as a sensitive indicator of MC-LR-induced NASH, and the point of departure value was estimated to be 1.634 μg/L. In conclusion, our findings offer new insights into the mechanism of MC-LR-induced NASH and aid in the prognosis and treatment of MC-LR-related liver metabolic diseases, as well as in assessing the health risks associated with cyanobacterial blooms.

Adverse outcome pathway of Alzheimer's disease-like changes resulting from autophagy flux blockade after MC-LR exposure

Microcystins (MCs) pollution is a worldwide environmental issue concerning about human health. Microcystin-leucine-arginine (MC-LR), the most common type of MCs produced by cyanobacteria, could enter the brain and bring about damage to the nervous system. Up to date, it is not clear about the mechanism of MC-LR-induced neurotoxicity. Amyloid-β (Aβ) deposits are hallmark of Alzheimer's disease (AD). In this study, we revealed that MC-LR exposure at environment-related doses (1, 7.5, 15 μg/L) could promote Aβ accumulation in mouse brain. Mechanically, we firstly found that Aβ accumulation is closely associated with abnormal Aβ degradation due to autophagy flux blockade and lysosome dysfunctions in neurons after MC-LR exposure. Moreover, an adverse outcome pathway (AOP) framework oriented to neurotoxicity of MC-LR was conducted in this study. MC-LR inhibited the activity of protein phosphatase 2A (PP2A) in neurons, which is regarded as a molecular initiating event (MIE). In addition, the abnormalities in autophagy were observed after MC-LR exposure. The hindered autophagosome-lysosome fusion and disrupted lysosomal function were key events (KEs) after MC-LR exposure, which contributed to proteostasis dysregulation, ultimately leading to Aβ abnormal degradation and learning deficits as adverse outcomes (AO) of neurotoxicity. This study provided novel information about MC-LR neurotoxicity and new insights into understanding the mechanisms underlying the environmental chemicals-induced neurodegeneration diseases, which has deep implications for public health.

Investigation of the structural changes in the hippocampus and prefrontal cortex using FTIR spectroscopy in sleep deprived mice

Sleep is a basic, physiological requirement for living things to survive and is a process that covers one third of our lives. Melatonin is a hormone that plays an important role in the regulation of sleep. Sleep deprivation affect brain structures and functions. Sleep deprivation causes a decrease in brain activity, with particularly negative effects on the hippocampus and prefrontal cortex. Despite the essential role of protein and lipids vibrations, polysaccharides, fatty acid side chains functional groups, and ratios between amides in brain structures and functions, the brain chemical profile exposed to gentle handling sleep deprivation model versus Melatonin exposure remains unexplored. Therefore, the present study, aims to investigate a molecular profile of these regions using FTIR spectroscopy measurement's analysis based on lipidomic approach with chemometrics and multivariate analysis to evaluate changes in lipid composition in the hippocampus, prefrontal regions of the brain. In this study, C57BL/6J mice were randomly assigned to either the control or sleep deprivation group, resulting in four experimental groups: Control (C) (n = 6), Control + Melatonin (C + M) (n = 6), Sleep Deprivation (S) (n = 6), and Sleep Deprivation + Melatonin (S + M) (n = 6). Interventions were administered each morning via intraperitoneal injections of melatonin (10 mg/kg) or vehicle solution (%1 ethanol + saline), while the S and S + M groups underwent 6 h of daily sleep deprivation from using the Gentle Handling method. All mice were individually housed in cages with ad libitum access to food and water within a 12-hour light-dark cycle. Results presented that the brain regions affected by insomnia. The structure of phospholipids, changed. Yet, not only changes in lipids but also in amides were noticed in hippocampus and prefrontal cortex tissues. Additionally, FTIR results showed that melatonin affected the lipids as well as the amides fraction in cortex and hippocampus collected from both control and sleep deprivation groups.

Introducing fluorescent probe technology for detecting microcystin-LR in the water and cells

BACKGROUND

For a long time, the environment hazards caused by cyanobacteria bloom and associated microcystins have attracted attention worldwide. Microcystin-LR (MC-LR) is the most widely distributed and most toxic toxin. At present, numerous MC-LR detection methods exist many drawbacks. Therefore, a quick and accurate method for identifying and detecting MC-LR is crucial and necessary. In this work, we strived to introduce a novel fluorescence assay to detect MC-LR in the water and cells.

RESULTS

According to the special spatial configuration and physicochemical properties of MC-LR, we designed and constructed six fluorescent probes. The design concepts of the probes were exhaustively elaborated. MC-YdTPA, MC-YdTPE, MC-RdTPA, and MC-RdTPE could show significant fluorescence enhancement in MC-LR solution. Significantly, MC-YdTPA, MC-YdTPE, and MC-RdTPA could also response well in the cells treated with MC-LR, demonstrating these fluorescent probes' values. The recognition mechanism between probes and MC-LR were also deeply explored: (1) The polyphenylene ring structure of probes may have nested or hydrogen bond weak interaction with the ring structure of MC-LR. (2) The probes can generate a reaction to the hydrogen ions ionized by MC-LR.

SIGNIFICANCE

We proposed the novel ideas for designing MC-LR probes. This research can provide valuable experiences and important assistance in synthesizing MC-LR fluorescent probes. We expect that this work may bring new ideas to develop fluorescent probes for researching MC-LR in vivo and in vitro.