Microplastic Characteristics in Equus kiang (Tibetan Wild Ass) Feces and Soil on the Southern Tibetan Plateau, China.

Microplastics (MPs) are emerging pollutants, and limited research has focused on their exposure to terrestrial wildlife and transport mode on the remote Tibetan Plateau (TP). Therefore, we investigated MPs in the southern soil and feces of Equus kiang (Tibetan wild ass), a species peculiar to the TP, which is known as the "third pole." We found that MP median abundances were 102 and 4.01 particles/g of dry feces and soil, respectively. In both media, the MP morphology mainly comprised ∼50 µm slender fibrous particles. In total, 29 MP types were identified in the feces, compared to 26 types in the soil. Among them, the acrylate copolymer (35.9%) and polyurethane (24.9%) were predominant in the feces, while polyurethane (22.5%) and silicone (20.4%) were predominant in the soil. After ingesting MPs at one location, E. kiang may become a source of MP pollution when moving to other meadows on the TP. The potential MP transport flux of a herd of 20 kiangs has been estimated at 1736 particles m-2 a-1. A unique "source-sink-source" MP transport model comprising an "atmospheric deposition-vegetation-feces-atmosphere" cycle on the TP was observed based on atmospheric transport simulations and terrestrial food chain transfer processes. Owing to human settlements in south and East Asia adjacent to the TP, atmospheric long-distance transmission is an essential route for MPs to enter the TP.

Cosmogenic radionuclide Beryllium-7 and Beryllium-10 characteristics and influencing factors in different natural climate regions, China.

The cosmogenic radionuclide 7Be (T1/2: 53.29 days) and 10Be (T1/2: 1.39 My), as unique tracers, play an excellent indicative role in atmospheric environmental changes and Earth surface processes. Currently, their different characteristics and influencing factors in various natural climate environments are still vague. Here, we used a state-of-the-art accelerator mass spectrometry to synchronously measure the ultra-trace 7Be and 10Be in aerosols, obtaining the spatial and temporal variability of daily-resolution atmospheric 7Be and 10Be in different natural climate regions (n = 11) of China. The survey results show that the 10Be and 7Be concentrations in the central/southern regions of China (22-38°N, 85-119°E) in 2020/21 are (0.5-18.7)·104 and (0.4-6.1)·104 atoms·m-3, respectively, with 10Be/7Be ratios of 0.7-3.3. Except for the Tibetan Plateau, there are differences in the concentration thresholds of 10Be and 7Be in various regions, especially in 10Be concentration. These 10Be/7Be thresholds are consistent in areas with an altitude range of 4-3420 m a.s.l and reach their highest values throughout the spring of the year. The analysis results indicate that both 7Be and 10Be are influenced by local meteorological conditions such as rainfall and boundary layer disturbances, while also exhibiting different distribution states. This distribution states is due to the re-suspended soil dust 10Be interference caused by soil wind erosion to varying degrees in different regions, with an average contribution to aerosol 10Be of 5.0 ± 2.6 %-24.2 % ± 13.3 %, and is controlled by local annual rainfall (r = 0.8, p < 0.01). Furthermore, unlike the characteristics of 10Be and 7Be concentrations influenced by local meteorological conditions, the daily variation of corrected 10Be/7Be exhibits independence from meteorological processes other than stratosphere troposphere transport, and its significant seasonal oscillations indicate changes in atmospheric circulation in the East Asian monsoon region.

Mitochondrial Uncoupling Protein-2 Ameliorates Ischemic Stroke by Inhibiting Ferroptosis-Induced Brain Injury and Neuroinflammation.

Ischemic stroke is a devastating disease in which mitochondrial damage or dysfunction substantially contributes to brain injury. Mitochondrial uncoupling protein-2 (UCP2) is a member of the UCP family, which regulates production of mitochondrial superoxide anion. UCP2 is reported to be neuroprotective for ischemic stroke-induced brain injury. However, the molecular mechanisms of UCP2 in ischemic stroke remain incompletely understood. In this study, we investigated whether and how UCP2 modulates neuroinflammation and regulates neuronal ferroptosis following ischemic stroke in vitro and in vivo. Wild-type (WT) and UCP2 knockout (Ucp2-/-) mice were subjected to middle cerebral artery occlusion (MCAO). BV2 cells (mouse microglial cell line) and HT-22 cells (mouse hippocampal neuronal cell line) were transfected with small interfering (si)-RNA or overexpression plasmids to knockdown or overexpress UCP2 levels. Cells were then exposed to oxygen-glucose deprivation and reoxygenation (OGD/RX) to simulate hypoxic injury in vitro. We found that UCP2 expression was markedly reduced in a time-dependent manner in both in vitro and in vivo ischemic stroke models. In addition, UCP2 was mainly expressed in neurons. UCP2 deficiency significantly enlarged infarct volumes, aggravated neurological deficit scores, and exacerbated cerebral edema in mice after MCAO. In vitro knockdown of Ucp2 and in vivo genetic depletion of Ucp2 (Ucp2-/- mice) increased neuronal ferroptosis-related indicators, including Fe2+, malondialdehyde, glutathione, and lipid peroxidation. Overexpression of UCP2 in neuronal cells resulted in reduced ferroptosis. Moreover, knockdown of UCP2 exacerbated neuroinflammation in BV2 microglia and mouse ischemic stroke models, suggesting that endogenous UCP2 inhibits neuroinflammation following ischemic stroke. Upregulation of UCP2 expression in microglia appeared to decrease the release of pro-inflammatory factors and increase the levels of anti-inflammatory factors. Further investigation showed that UCP2 deletion inhibited expression of AMPKα/NRF1 pathway-related proteins, including p-AMPKα, t-AMPKα, NRF1, and TFAM. Thus, UCP2 protects the brain from ischemia-induced ferroptosis by activating AMPKα/NRF1 signaling. Activation of UCP2 represents an attractive strategy for the prevention and treatment of ischemic stroke.

Unraveling the process of aerosols secondary formation and removal based on cosmogenic beryllium-7 and beryllium-10.

The secondary formation and diffusion processes of aerosol are extraordinarily complex and significantly impact the environment and human health. Therefore, exploring the process of aerosol formation and diffusion based on independent new tracer has always been a concern. The 7Be and 10Be, which are generated only by the action of cosmic rays, are chemically stable and adsorbed on aerosol for transmission, so they have the potential characteristics of aerosol tracers. Here, we obtained the daily resolution atmospheric 7Be, 10Be, and 10Be/7Be without dust interference in Xi'an autumn and winter (heavy pollution period in a typical polluted area) by accelerator mass spectrometry. It is found that during the rapid formation of secondary aerosols (SA) under the stable 10Be/7Be ratio, which indicates the stable atmospheric vertical structure, the concentration of 7Be and 10Be is significantly negatively correlated (R2 > 0.9) with the aerosol concentration. Therefore, SA relative content in aerosols can be estimated by the dilution amount of 7Be and 10Be to reveal the secondary-formation process of aerosol (33% average contribution to aerosols during the winter heavy air pollution period). Furthermore, we also revealed the physical removal process of aerosols based on 7Be, 10Be, and 10Be/7Be, including precipitation removal and diffusion of vertical atmospheric movement caused by stratospheric air intrusion. In summary, meteoric cosmogenic 7Be and 10Be will provide a new way to study the secondary chemical formation and physical removal of aerosols.

Ubiquitin-Specific Protease 29 Exacerbates Cerebral Ischemia-Reperfusion Injury in Mice.

Oxidative stress and apoptosis contribute to the progression of cerebral ischemia/reperfusion (I/R) injury. Ubiquitin-specific protease 29 (USP29) is abundantly expressed in the brain and plays critical roles in regulating oxidative stress and cell apoptosis. The purpose of the present study is to investigate the role and underlying mechanisms of USP29 in cerebral I/R injury. Neuron-specific USP29 knockout mice were generated and subjected to cerebral I/R surgery. For USP29 overexpression, mice were stereotactically injected with the adenoassociated virus serotype 9 vectors carrying USP29 for 4 weeks before cerebral I/R. And primary cortical neurons were isolated and exposed to oxygen glucose deprivation/reperfusion (OGD/R) stimulation to imitate cerebral I/R injury in vitro. USP29 expression was elevated in the brain and primary cortical neurons upon I/R injury. Neuron-specific USP29 knockout significantly diminished, whereas USP29 overexpression aggravated cerebral I/R-induced oxidative stress, apoptosis, and neurological dysfunction in mice. In addition, OGD/R-induced oxidative stress and neuronal apoptosis were also attenuated by USP29 silence but exacerbated by USP29 overexpression in vitro. Mechanistically, neuronal USP29 enhanced p53/miR-34a-mediated silent information regulator 1 downregulation and then promoted the acetylation and suppression of brain and muscle ARNT-like protein, thereby aggravating oxidative stress and apoptosis upon cerebral I/R injury. Our findings for the first time identify that USP29 upregulation during cerebral I/R may contribute to oxidative stress, neuronal apoptosis, and the progression of cerebral I/R injury and that inhibition of USP29 may help to develop novel therapeutic strategies to treat cerebral I/R injury.

Copper foam in situ loaded with precious metal nanoparticles as transmission SEIRAS substrate for rapid detection of dithiocarbamate pesticides.

A transmission surface-enhanced infrared absorption spectroscopy (SEIRAS) substrate based on copper foam (CF) was developed for the rapid detection of dithiocarbamate (DTC) pesticides. The transmission SEIRAS substrate was prepared by immersing CF in a mixed solution of a precious metal solution and a polyvinyl pyrrolidone (PVP) solution. Then CF could be in situ loaded with precious metal nanoparticles (MNPs) by PVP-modified displacement reaction in seconds. PVP could be helpful for the uniform distribution of MNPs. Experimental parameters were evaluated with 11-mercaptoundecanoic acid (MUA) as a probe molecule, including the concentration of the precious metal solution, the amount of PVP, and the reaction time. Taking CF loaded with gold nanoparticles (Au NPs-CF) as an example, the signal intensity of DTC pesticide (Ziram) could be enhanced by two orders of magnitude, and the R2 of the calibration curve was 0.999. In addition, the Pt NPs-CF substrate was applied to the rapid detection of other DTC pesticides (Ferbam). In summary, we have developed a new method to prepare the transmission SEIRAS substrate and apply it to the rapid detection of DTC pesticides in liquid.

Rapid screening of rhodamine B in food by hydrogel solid-phase extraction coupled with direct fluorescence detection.

Rhodamine B (RhB), which is vividly colored, although illegal and potentially carcinogenic, has been reported widely as present in various foods, including chili powder, preserved plums, sausage and sweets, presenting a significant health risk. In this work, solid-phase extraction (SPE), coupled with direct fluorescence detection on the same extraction medium, is proposed for rapid onsite screening for RhB in food without sample pretreatment. Parameters that affected extraction of RhB were explored. The lowest amount of RhB, detected on glass, was 2 ng and the lowest detectable concentration in food samples was 0.5 mg/kg, as verified by HPLC. The analysis time was less than 5 min, including sampling. In addition, the recovery rate of this method was found to be triple of that from the cotton gauze reported in literature. The proposed method has promise as a rapid, onsite screening protocol for food safety.

Histone Deacetylase Inhibitor MS-275 Alleviates Postoperative Cognitive Dysfunction in Rats by Inhibiting Hippocampal Neuroinflammation.

Neuroinflammation in the hippocampus plays essential roles in postoperative cognitive dysfunction (POCD). Histone deacetylases (HDACs) have recently been identified as key regulators of neuroinflammation. MS-275, an inhibitor of HDAC, has been reported to have neuroprotective effects. Therefore, the present study aimed to test the hypothesis that pretreatment with MS-275 prevents POCD by inhibiting neuroinflammation in rats. In this study, anesthesia/surgery impaired cognition, demonstrated by an increase escape latency and reduction in the number of platform crossings in Morris water maze (MWM) trials, through activating microglia neuroinflammation and decreasing PSD-95 expression. However, pretreatment with MS-275 attenuated postoperative cognitive impairment severity. Furthermore, pretreatment with MS-275 decreased activated microglia levels and increased PSD95 protein expression in the hippocampus. Pretreatment with MS-275 reduced NF-κB-p65 protein expression and nuclear accumulation as well as the neuroinflammatory response (production of proinflammatory cytokines including TNF-α and IL-1ß) in the hippocampus. Additionally, MS-275 reduced HDAC2 expression and HDAC activity in the hippocampus, which were enhanced in vehicle-treated rats. These results suggest that MS-275 alleviates postoperative cognitive dysfunction by reducing neuroinflammation in the hippocampus of rats via HDAC inhibition.