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Dimethylsulfoniopropionate (DMSP) is an important marine osmolyte. Aphotic environments are only recently being considered as potential contributors to global DMSP production. Here, our Mariana Trench study reveals a typical seawater DMSP/dimethylsulfide (DMS) profile, with highest concentrations in the euphotic zone and decreased but consistent levels below. The genetic potential for bacterial DMSP synthesis via the dsyB gene and its transcription is greater in the deep ocean, and is highest in the sediment.s DMSP catabolic potential is present throughout the trench waters, but is less prominent below 8000 m, perhaps indicating a preference to store DMSP in the deep for stress protection. Deep ocean bacterial isolates show enhanced DMSP production under increased hydrostatic pressure. Furthermore, bacterial dsyB mutants are less tolerant of deep ocean pressures than wild-type strains. Thus, we propose a physiological function for DMSP in hydrostatic pressure protection, and that bacteria are key DMSP producers in deep seawater and sediment. Dimethylsulfoniopropionate (DMSP) is an osmolyte produced by marine microbes that plays an important role in nutrient cycling and atmospheric chemistry. Here the authors go to the Mariana Trench—the deepest point in the ocean—and find bacteria are key DMSP producers, and that DMSP has a role in protection against high pressure.

Methane is supersaturated in surface seawater and shallow coastal waters dominate global ocean methane emissions to the atmosphere. Aerobic methane oxidation (MOx) can reduce atmospheric evasion, but the magnitude and control of MOx remain poorly understood. Here we investigate methane sources and fates in the East China Sea and map global MOx rates in shallow waters by training machine-learning models. We show methane is produced during methylphosphonate decomposition under phosphate-limiting conditions and sedimentary release is also source of methane. High MOx rates observed in these productive coastal waters are correlated with methanotrophic activity and biomass. By merging the measured MOx rates with methane concentrations and other variables from a global database, we predict MOx rates and estimate that half of methane, amounting to 1.8 ± 2.7 Tg, is consumed annually in near-shore waters (<50 m), suggesting that aerobic methanotrophy is an important sink that significantly constrains global methane emissions. Aerobic oxidation is a biological sink of methane that can reduce oceanic emissions to the atmosphere. This study estimates that half of methane from total loss, amounting to 1.8 ± 2.7 Tg, is oxidized annually in global 0–50 m near-shore waters

Biogenic dimethylated sulfur compounds could take part in the metabolic process of algal cells and are the key compounds in the biological cycle of sulfur in the marine system. In this study, seasonal and spatial variations of biogenic dimethylated sulfur compounds, including dimethylsulfide (DMS), dimethylsulfoniopropionate (DMSP), and dimethylsulfoxide (DMSO), and oceanographic parameters influencing their concentrations were measured in the East China Sea (ECS) during two cruises from 22 October 2015 to 13 November 2015 and from 31 May 2016 to 14 June 2016. Significant spatial variability was observed in seawater dimethylated sulfur compound concentrations with higher concentration in spring. In most cases, concentrations of DMS, particulate DMSP, and particulate DMSO showed significant relationships with the concentration of chlorophyll a under highly variable hydrographic conditions. In spring, bacterial abundance also significantly influenced DMS distribution. Photodegradation experiments showed that enhanced UV radiation could increase DMS photodegradation rate, and low seawater pH could facilitate DMS degradation rate under UVB radiation while it was decreased under UVA radiation. Preliminary estimates for the sea-to-air fluxes of DMS in spring showed a 2.3 μmolm−2 d−1 increase over autumn flux. Compared with total DMS emission of the global ocean to atmosphere, the contribution of the ECS to global DMS emissions was not negligible. At Sta. DH6-1, the contribution of biological consumption to DMS removal (85%) was higher than those of photolysis (10%) and sea-to-air exchanges (4%). These findings reveal that biological consumption probably dominates removal of DMS at this station.

Neuropathic pain (NP) is a common symptom of many diseases and is caused by direct or indirect damage to the nervous system. Tricyclic antidepressants and serotonin-norepinephrine reuptake inhibitors are typical drugs used in clinical practice to suppress pain. However, these drugs have drawbacks, including a short duration of action, a limited analgesic effect, and possible dependence and side effects. Therefore, developing more effective NP treatment strategies has become a priority in medical research and has attracted much research attention. P2X7 receptor (P2X7R) is a non-selective cation channel activated by adenosine triphosphate and is mainly expressed in microglia in the central nervous system. Microglial P2X7R plays an important role in pain regulation, suggesting that it could be a potential target for drug development. This review comprehensively and objectively discussed the latest research progress of P2X7R, including its structural characteristics, functional properties, relationship with microglial activation and polarization, mechanism of action, and potential therapeutic strategies in multiple NP models. This study aimed to provide in-depth insights into the association between P2X7R and NP and explore the mechanism of action of P2X7R in the pathological process of NP and the translational potential and clinical application prospects of P2X7R antagonists in pain treatment, providing a scientific basis for the precise treatment of NP.

Intervertebral disc degeneration (IVDD) is a common chronic musculoskeletal disease that causes chronic low back pain and imposes an immense financial strain on patients. The pathological mechanisms underlying IVDD have not been fully elucidated. The development of IVDD is closely associated with abnormal epigenetic changes, suggesting that IVDD progression may be controlled by epigenetic mechanisms. Consequently, this study aimed to investigate the role of epigenetic regulation, including DNA methyltransferase 3a (DNMT3a)‐mediated methylation and peroxisome proliferator‐activated receptor γ (PPARγ) inhibition, in IVDD development. The expression of DNMT3a and PPARγ in early and late IVDD of nucleus pulposus (NP) tissues was detected using immunohistochemistry and western blotting analyses. Cellularly, DNMT3a inhibition significantly inhibited IL‐1β‐induced apoptosis and extracellular matrix (ECM) degradation in rat NP cells. Pretreatment with T0070907, a specific inhibitor of PPARγ, significantly reversed the anti‐apoptotic and ECM degradation effects of DNMT3a inhibition. Mechanistically, DNMT3a modified PPARγ promoter hypermethylation to activate the nuclear factor‐κB (NF‐κB) pathway. DNMT3a inhibition alleviated IVDD progression. Conclusively, the results of this study show that DNMT3a activates the NF‐κB pathway by modifying PPARγ promoter hypermethylation to promote apoptosis and ECM degradation. Therefore, we believe that the ability of DNMT3a to mediate the PPARγ/NF‐κB axis may provide new ideas for the potential pathogenesis of IVDD and may become an attractive target for the treatment of IVDD.

Carbonyl sulfide (COS), dimethyl sulfide (DMS), and carbon disulfide (CS₂) concentrations were determined in seawater and the overlying atmosphere of the Changjiang Estuary and the adjacent area during two cruises from 22 February 2016 to 15 March 2016 and from 03 July 2016 to 25 July 2016. The concentration ranges of COS, DMS, and CS₂ in seawater during winter were 121–388 pmol L−1, 0.321–1.59 nmol L−1, and 10.3–46.8 pmol L−1, respectively, and those during summer were 98–346 pmol L−1, 0.397–9.13 nmol L−1, and 13.3–65.4 pmol L−1. The DMS concentration in surface seawater varied seasonally, whereas the COS and CS₂ concentrations varied little. The atmospheric mixing ratios of COS, DMS, and CS₂ were 459–777 pptv, 5.2–96.8 pptv, and 96.9–164 pptv during winter and 417–644 pptv, 133–365 pptv, and 15.8–89.8 pptv during summer, respectively. A correlation analysis revealed that COS concentration was related to the concentrations of DMS and CS₂. The estimated fluxes of COS, DMS, and CS₂ were in the range of 1.19–2.06 μg m−2 d−1, 15.11–164.81 μg m−2 d−1, and 0.27–1.32 μg m−2 d−1 during winter and 0.61–0.97 μg m−2 d−1, 71.76–2511 μg m−2 d−1, and 0.38–1.47 μg m−2 d−1 during summer, respectively. These results indicate that the study area is a sink for COS, but served as a source of atmospheric DMS and CS₂ during the study period.

Biogenic dimethylated sulfur compounds, comprising dimethylsulfide (DMS), dimethylsulfoniopropionate (DMSP), and dimethylsulfoxide, play a vital role in the physiological metabolism processes of marine algae, climate regulation, and global sulfur cycles, but the contribution of each transformation pathway and the factors that control them remain uncertain. For the first time, from 27 March 2017 to 15 April 2017, the rates of major transformation pathways of biogenic dimethylated sulfur compounds and the fluxes of DMS at the sea–air and seawater–sediment interfaces were measured simultaneously in the East China Continental Sea. Rapid biological turnover times of total DMSP (0.53 d), dissolved DMSP (0.29 d), and DMS (0.43 d) were observed, indicating that DMS and DMSP were renewed more than twice daily. Bacterial consumption contributed nearly 50% of the total DMSP loss, approximately 38% of which was converted into DMS. Microbial consumption, photolysis, and ventilation accounted for 56%, 34%, and 10% of DMS removal processes, respectively. Sediment had a small but positive flux of DMS, making the sediment-seawater interface a tiny source of DMS to the water column. Finally, although only about 10% of DMS was emitted to the atmosphere, the study region was identified as a “hotspot” for atmospheric DMS. The DMS budget model of the mixed layer developed in this study has provided a systematic and comprehensive understanding of the organosulfur cycle in continental shelf seas.

The ocean serves as a significant contributor of atmospheric Hydrogen (H2) with indirect greenhouse effects. However, uncertainties persist regarding internal production and consumption processes of marine H2, as well as controlling factors. Our study examined the spatial distribution and source‐sink dynamics of marine H2 in the Eastern Indian Ocean. H2 concentrations in surface seawater exhibited a range of 2.95–21.96 nmol L−1. High concentrations of H2 were observed in the anoxic water in the Bay of Bengal. Rates of H2 photo‐production and microbial consumption in surface seawater ranged from 1.80 to 17.78 nmol L−1 h−1 and 1.02–9.18 nmol L−1 h−1, respectively. When considering the entire mixed layer, photo‐production contribute to approximately 31%–43% of the total H2 removal, with cyanobacteria potentially serving as another source in the mixed layer. Compared with the sea‐to‐air exchange, microbial consumption was the primary removal pathway of H2 in seawater. Plain Language Summary Atmospheric hydrogen (H2) can influence the environment and climate by consuming hydroxyl radicals (OH·) and indirectly raising greenhouse gas concentrations. Although the ocean serves as a significant source of atmospheric H2, the biogeochemical processes governing its presence in seawater remain poorly understood. The Eastern Indian Ocean, characterized by a substantial inflow of freshwater, exerts a distinct impact on the local ecosystem. We conducted a field investigation in the Eastern Indian Ocean to clarify the sources, sinks, and controlling factors of H2, including the Bay of Bengal with relatively higher primary productivity and the Eastern Equatorial Indian Ocean with low primary productivity, respectively. Our study involved the quantitative assessment of H2 photo‐production, microbial consumption, and sea‐to‐air exchange in seawater, along with the calculation of the H2 budget in the mixed layer. This investigation enhances our understanding of H2 cycling processes in seawater and contributes to the assessment of H2 emissions from the ocean and their impact on the atmospheric budget. Key Points The distribution of H2 was significantly affected by river input in the Eastern Indian Ocean Photo‐production was an important source of H2 in the mixed layer Microbial consumption was the primary sink for H2 in the mixed layer

Microbial acetate metabolism is an important part of marine carbon cycling. We present a comprehensive study to constrain microbial acetate metabolism and its regulation in surface seawater of the northwest Pacific Ocean. We found that acetate oxidation (rate constant k: 0.016–0.506 day−1) accounted for 77.6%–99.4% of the total microbial acetate uptake, suggesting that acetate was predominantly used as a microbial energy source. Acetate also served as a significant biomass carbon source, as reflected by the elevated contribution of acetate assimilation to bacterial carbon production. Acetate turnover was largely influenced by water mass mixing and nutrient conditions. Atmospheric deposition was a source of acetate in surface water and this process can also impact the microbial acetate uptake. Microbial utilization of acetate could account for up to 25.9% of the bacterial carbon demand, suggesting the significant role of acetate metabolism in microbial carbon cycling in the open ocean. Plain Language Summary Acetate is a key metabolic intermediate during the mineralization of organic matter and microbial acetate metabolism plays a crucial role in marine carbon cycling. However, the microbial metabolism of acetate and its environmental controls in pelagic waters remain poorly understood. We investigated biogeochemical cycling of acetate in the Kuroshio‐Oyashio extension region of northwest Pacific Ocean. Acetate concentrations in surface waters were generally low and atmospheric deposition was a source of acetate in the upper ocean. Acetate was used preferentially as a microbial energy source and the proportion of acetate devoted to bacterial growth or respiration largely depended on local nutrient conditions. Rapid biological turnover of acetate contributed significantly to bacterial carbon demand, exceeding the contributions of other compounds such as methanol. These results constrain the atmospheric sources and microbial sinks of marine acetate and reveal the ecological significance of microbial acetate metabolism in the open ocean. Key Points Microbial uptake rates of acetate ranged from 1.7 to 495 nmol L−1 day−1 in surface waters of the northwest Pacific Ocean Acetate is used preferentially as a microbial energy source rather than as a biomass carbon source Microbial acetate metabolism is influenced by water mass mixing and atmospheric deposition

Methanol metabolism can play an important role in marine carbon cycling. We made contemporaneous measurements of methanol concentration and consumption rates in the northwest Pacific Ocean to constrain the pathways and dynamics of methanol cycling. Methanol was detected in relatively low concentrations (<12–391 nM), likely due to rapid biological turnover. Rates of methanol oxidation to CO2 (0.9–130.5 nmol L−1 day−1) were much higher than those of assimilation into biomass (0.09–6.8 nmol L−1 day−1), suggesting that >89.7% of methanol was utilized as an energy source. Surface water acted as a net methanol sink at most sites, with an average flux of 9 μmol L−1 day−1. Atmospheric deposition accounted for 22.7% of microbial methanol consumption in the mixed layer, illustrating that the atmosphere is less important than internal processes for driving methanol cycling in these pelagic waters. Plain Language Summary Methanol is one of the most abundant oxygenated volatile organic compounds in the atmosphere and microbial methanol metabolism is an important part of the marine carbon cycle. However, only a limited number of studies describe methanol cycling in marine waters, and the sources and sinks of methanol remain largely unconstrained in the Pacific Ocean. We investigated the distribution and microbial consumption of methanol in the Kuroshio‐Oyashio extension region of northwest Pacific Ocean. Methanol was used primarily as an energy source and the rapid biological turnover of methanol contributed to relatively low‐standing stocks of methanol. Air‐sea flux estimates suggested that the atmosphere was a net source of methanol to the study area. Compared to in situ production and consumption rates, air‐sea exchange represented a less important process for methanol cycling in the mixed layer. Our results add to the global database of methanol concentrations and help to constrain the biological sources and sinks of methanol in the surface ocean. Key Points Methanol was detected in relatively low concentrations due to rapid biological consumption in the Kuroshio‐Oyashio extension region Much higher oxidation rates than assimilation rates suggested methanol was predominantly used as an energy source Atmospheric deposition is a source of methanol in the mixed layer and accounted for 22.7% of microbial methanol consumption