[Ozone Pollution in Suzhou During Early Summertime: Formation Mechanism and Interannual Variation].

This study investigated the concentrations of atmospheric pollutants in the urban area of Suzhou from May to June, 2017-2021. The variation characteristics and annual changes of ozone (O3), nitrogen oxide (NOx), total oxidant (Ox), carbon monoxide (CO), and volatile organic compounds (VOCs) were analyzed. The O3 formation mechanism and its annual changes were studied using an Observation-Based Model (OBM), and VOCs source apportionments and their trends were discussed. The results indicated that ① The volume fractions of Ox and the concentrations of NOx and CO have decreased in the urban area of Suzhou in recent years, while the volume fractions of VOCs have increased, and sufficient photochemical conditions for O3 formation still existed during polluted days. ② The O3-NOx-VOCs sensitivity in Suzhou was in the VOCs-limited regime. The long-term reduction ratio between VOCs and NOx should not be less than 5:1, and aromatics and alkenes were the critical VOCs for mitigating O3 pollution. ③ The results of VOCs source apportionment revealed that industrial emissions, gasoline vehicle exhaust, and diesel engine exhaust were the major sources of VOC emissions in Suzhou. Industrial emissions and solvent usage declined from 2017 to 2021; however, gasoline vehicle exhaust and gasoline evaporation, which possess higher O3 formation potential(OFP), increased significantly. ④ The OFP source apportionments results indicated that controlling VOC emissions from solvent usage and gasoline vehicle exhaust is crucial for O3 pollution control in Suzhou.

Bioinformatics analysis of ferroptosis in spinal cord injury.

Ferroptosis plays a key role in aggravating the progression of spinal cord injury (SCI), but the specific mechanism remains unknown. In this study, we constructed a rat model of T10 SCI using a modified Allen method. We identified 48, 44, and 27 ferroptosis genes that were differentially expressed at 1, 3, and 7 days after SCI induction. Compared with the sham group and other SCI subgroups, the subgroup at 1 day after SCI showed increased expression of the ferroptosis marker acyl-CoA synthetase long-chain family member 4 and the oxidative stress marker malondialdehyde in the injured spinal cord while glutathione in the injured spinal cord was lower. These findings with our bioinformatics results suggested that 1 day after SCI was the important period of ferroptosis progression. Bioinformatics analysis identified the following top ten hub ferroptosis genes in the subgroup at 1 day after SCI: STAT3, JUN, TLR4, ATF3, HMOX1, MAPK1, MAPK9, PTGS2, VEGFA, and RELA. Real-time polymerase chain reaction on rat spinal cord tissue confirmed that STAT3, JUN, TLR4, ATF3, HMOX1, PTGS2, and RELA mRNA levels were up-regulated and VEGFA, MAPK1 and MAPK9 mRNA levels were down-regulated. Ten potential compounds were predicted using the DSigDB database as potential drugs or molecules targeting ferroptosis to repair SCI. We also constructed a ferroptosis-related mRNA-miRNA-lncRNA network in SCI that included 66 lncRNAs, 10 miRNAs, and 12 genes. Our results help further the understanding of the mechanism underlying ferroptosis in SCI.

Identification of key genes involved in recovery from spinal cord injury in adult zebrafish.

Zebrafish are an effective vertebrate model to study the mechanisms underlying recovery after spinal cord injury. The subacute phase after spinal cord injury is critical to the recovery of neurological function, which involves tissue bridging and axon regeneration. In this study, we found that zebrafish spontaneously recovered 44% of their swimming ability within the subacute phase (2 weeks) after spinal cord injury. During this period, we identified 7762 differentially expressed genes in spinal cord tissue: 2950 were up-regulated and 4812 were down-regulated. These differentially expressed genes were primarily concentrated in the biological processes of the respiratory chain, axon regeneration, and cell-component morphogenesis. The genes were also mostly involved in the regulation of metabolic pathways, the cell cycle, and gene-regulation pathways. We verified the gene expression of two differentially expressed genes, clasp2 up-regulation and h1m down-regulation, in zebrafish spinal cord tissue in vitro. Pathway enrichment analysis revealed that up-regulated clasp2 functions similarly to microtubule-associated protein, which is responsible for axon extension regulated by microtubules. Down-regulated h1m controls endogenous stem cell differentiation after spinal cord injury. This study provides new candidate genes, clasp2 and h1m, as potential therapeutic intervention targets for spinal cord injury repair by neuroregeneration. All experimental procedures and protocols were approved by the Animal Ethics Committee of Tianjin Institute of Medical & Pharmaceutical Sciences (approval No. IMPS-EAEP-Q-2019-02) on September 24, 2019.

Neuroprotective effect of deferoxamine on erastininduced ferroptosis in primary cortical neurons.

The iron chelator deferoxamine has been shown to inhibit ferroptosis in spinal cord injury. However, it is unclear whether deferoxamine directly protects neurons from ferroptotic cell death. By comparing the survival rate and morphology of primary neurons and SH-SY5Y cells exposed to erastin, it was found that these cell types respond differentially to the duration and concentration of erastin treatment. Therefore, we studied the mechanisms of ferroptosis using primary cortical neurons from E16 mouse embryos. After treatment with 50 µM erastin for 48 hours, reactive oxygen species levels increased, and the expression of the cystine/glutamate antiporter system light chain and glutathione peroxidase 4 decreased. Pretreatment with deferoxamine for 12 hours inhibited these changes, reduced cell death, and ameliorated cellular morphology. Pretreatment with the apoptosis inhibitor Z-DEVD-FMK or the necroptosis inhibitor necrostain-1 for 12 hours did not protect against erastin-induced ferroptosis. Only deferoxamine protected the primary cortical neurons from ferroptosis induced by erastin, confirming the specificity of the in vitro ferroptosis model. This study was approved by the Animal Ethics Committee at the Institute of Radiation Medicine of the Chinese Academy of Medical Sciences, China (approval No. DWLL-20180913) on September 13, 2018.