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The Clarion–Clipperton Fracture Zone (CCFZ) in the eastern central Pacific Ocean is the world's largest area for potential deep‐sea polymetallic nodule mining and is attracting increased scientific and commercial interest. Recent studies indicate that biogenic magnetite, generated intracellularly by magnetotactic bacteria (MTB), can carry a biogeochemical remanent magnetization in polymetallic nodules, although whether biogenic or physical‐chemical processes are responsible for nodule formation remain poorly constrained. Here, we report a combination of magnetic, electron microscope and geochemical analyses on seafloor surface sediments from the eastern CCFZ to understand the spatial distribution of biogenic magnetite and possible relationships between MTB and polymetallic nodules. Experimental results indicate that sedimentary magnetic minerals from the northern and southern regions are dominated by detrital (eolian loess and volcanic material) and biogenic magnetic minerals (magnetosomes), respectively. Sediments from the intermediate region contain both detrital and biogenic magnetic minerals. Quantitative first‐order reversal curve‐principal component analysis indicates that biogenic magnetite has the highest concentration in the intermediate CCFZ region, coincident with the highest polymetallic nodule density. Combined with previous research, we speculate that MTB growth on the CCFZ seafloor is driven mainly by local redox conditions. Manganese nodule surfaces are rich in organic biofilms, which results in a relatively thick oxic‐anoxic transition zone in high‐abundance manganese nodule regions, which generates an optimal microenvironment for both MTB growth and magnetite biomineralization. This study provides new clues for understanding the ecological distribution of MTB and the biogeochemical remanent magnetization recorded by biogenic magnetite in deep‐sea sediments. Plain Language Summary: Polymetallic nodules are an important seafloor resource because they contain economically important minerals (e.g., Ni, Co, and Mn) that are not common on land. Hence, there is increased economic and scientific interest in understanding the formation mechanisms of these materials. Several studies indicate that biogenic magnetite crystals produced by magnetotactic bacteria (MTB) occur within polymetallic nodules. Testing the relationship between MTB abundance and polymetallic nodule distribution can help to better understand how these materials formed. Here, we study seafloor sediments from the Clarion‐Clipperton Fracture Zone (CCFZ) and find that they mainly contain biogenic and detrital magnetic minerals. Detrital magnetic minerals come from volcanic chains and eolian dust, while biogenic magnetite forms within bacterial cells. We find that increased biogenic magnetite abundance coincides with higher polymetallic nodule occurrences in the CCFZ. This implies that MTB activity may play a significant role in the formation and growth of polymetallic nodules. Key Points: Biogenic and detrital magnetic minerals are quantified in seafloor surface sediments from the Clarion–Clipperton Fracture ZoneBiogenic magnetite concentrations and polymetallic nodule density are increased in the central Clarion–Clipperton Fracture ZonePolymetallic nodule growth likely produced reducing, organic‐rich microenvironments suitable for magnetotactic bacteria [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) constitutes a major global health threat due to the high incidence and mortality. Sorafenib is known as the first-line medication for advanced HCC; however, it only extends the limited benefit for HCC patients as the development of acquired resistance. Withaferin A exerts broad pharmaceutical applications in several cancers. However, its effects on HCC cell metastatic potential and sorafenib resistance remain elusive. Here, we corroborated that Withaferin A greatly restrained cell viability, invasion, vasculogenic mimicry (VM) formation, and VE-cadherin levels in HepG2 and SNU449 cells. Moreover, Withaferin A sensitized sorafenib (SR)-resistant HCC cells to sorafenib. In striking contrast to the parental cells, lower ferroptosis was observed in SR-resistant cells as the lower ROS, MDA, and higher intracellular GSH levels in SR-resistant cells. Of interest, Withaferin A enhanced ferroptosis in SR-resistant cells, which was reversed by ferroptosis antagonist liproxstation-1. Notably, Withaferin A elevated Keap1 expression to mitigate Nrf2 signaling activation-mediated epithelial to mesenchymal transition (EMT) and ferroptosis-related protein xCT expression. Importantly, blockage of the Keap1/Nrf2 signaling overturned Withaferin A-evoked ferroptosis and facilitated sorafenib resistance. In addition, knockdown of Keap1 antagonized the inhibitory efficacy of Withaferin A on HCC cell viability, invasion, and VM formation. Consequently, Withaferin A may attenuate the metastatic potential and sorafenib resistance by regulating Keap1/Nrf2-associated EMT and ferroptosis. Thus, Withaferin A may serve as a promising agent for HCC therapy, especially for advanced HCC. [ABSTRACT FROM AUTHOR]

The anhysteretic remanent magnetization (ARM) is an important magnetic parameter for quantifying the concentration of "fine", mostly sub‐micron ferrimagnetic particles in rocks and sediments. A sound understanding of ARM carriers is needed to interpret magnetic and environmental information in sedimentary archives. This is often not achieved for marine sediments, which routinely contain several magnetic mineral components. Here, we analyze marine sediment records over different timescales for four sediment cores from the Eastern Pacific Ocean (Hole 1218A), the Antarctic margin (core P4‐1), the Arctic Ocean (core ARC5‐ICE4), and the South China Sea (core L07), using coercivity spectra analyses of ARM, first‐order reversal curve principal component analysis (FORC‐PCA), transmission electron microscopy (TEM), and unmixing of isothermal remanent magnetization (IRM) curves. By combining rock magnetic and TEM results, we find that the ARM is mainly carried by non‐interacting single domain (SD) biogenic magnetite (magnetofossils) in the studied sediments over all timescales. Low‐coercivity magnetic particles (detrital and fine‐grained extracellular magnetite) also contribute to the bulk ARM. Variable magnetofossil chain structures are detected and have a significant influence on ARM data interpretation. Quantitative FORC‐PCA endmember analyses based on quantile contours and coercivity distributions provide valuable information on the nature of endmembers and improve ARM data interpretation. We provide an integrated strategy to help reduce interpretational ambiguities related to ARM in future studies. Plain Language Summary: The anhysteretic remanent magnetization (ARM) is an important parameter that is used to assess information about Earth's magnetic field variations and environmental changes. To interpret ARM signals robustly, we must understand the sedimentary magnetic minerals that control ARM changes. However, the origin of ARM changes in marine sediments is not well understood. Here, we analyze marine sediment records from the Eastern Pacific Ocean, the Antarctic margin, the Arctic Ocean, and the South China Sea to identify the carriers of ARM in the respective sediments. Our results indicate that all of the sediments contain abundant remains of magnetotactic bacteria (known as magnetofossils). Magnetofossil abundance variations dominate ARM on both 10,000 to million‐year timescales. Part of the bulk ARM is also contributed by other low‐coercivity magnetite particles. Furthermore, ARM is influenced significantly by magnetofossil chain structure variations. Our results have important implications for future studies involving use of ARM in magnetofossil‐rich sediments. Key Points: Integrated component analyses are presented for four sediment cores to identify magnetic particle sourcesMagnetofossils are the predominant anhysteretic remanent magnetization (ARM) carrier with detrital and extracellular magnetite also contributing to the ARMQuantitative analyses provide valuable insights into the nature of components to improve ARM data interpretation of marine sediments [ABSTRACT FROM AUTHOR]

• Serotonin depletion improved liver damage in LF mice. • Serotonin depletion inhibited collagen deposition in LF mice. • Serotonin depletion reduced serum and intrahepatic inflammatory cytokines in LF mice. • Serotonin depletion mitigated oxidative stress in liver tissues in LF mice. • Serotonin depletion inhabited TGF-β1/Smads signaling pathway in LF mice. Serotonin exerts important functions in several liver pathophysiological processes. In this study, we investigated the role of serotonin in concanavalin A (Con A)-induced liver fibrosis (LF) in mice and the underlying mechanisms. To establish the mouse model of LF, mice of wild-type (WT) and tryptophan hydroxylase 1 (Tph1) knockout (serotonin depletion) received Con A for 8 successive weeks. Degree of fibrosis was assessed by Sirius red staining, as well as the measurements of alpha smooth muscle actin (α- SMA), hydroxyproline (Hyp) and type I collagen in liver tissues. To elucidate the potential mechanisms, we assessed the effect of serotonin depletion on inflammatory, oxidative stress as well as TGF-β1/Smads signaling pathway. We found that serotonin depletion significantly inhibited collagen deposition as evaluated by less collagenous fiber in Sirus Red staining and reduced contents of Hyp and type I collagen. In addition, the absence of serotonin significantly inhibited the release of several inflammatory cytokines, including interleukin-6 (IL-6), interferon-gamma (IFN-γ), tumor necrosis-alpha (TNF-α), and transforming growth factor β1 (TGF-β1). Oxidative stress was also largely mitigated in LF mice with serotonin deficiency as manifested by the decreases of oxidative stress markers (malonaldehyde (MDA) and myeloperoxidase (MPO)), as well as the increases of antioxidant stress indicators (glutathione (GSH), and GSH-px, catalase (CAT), superoxide dismutase (SOD)) in liver tissues. Moreover, the lack of serotonin may provide an antifibrotic role by inhibiting the intrahepatic expressions of TGF-β1, phosphorylated-smad2 (p-smad2), and phosphorylated-smad3 (p-smad3). These results indicated that, serotonin depletion attenuates Con A-induced LF through the regulation of inflammatory response, oxidative stress injury, and TGF-β1/Smads signaling pathway. [ABSTRACT FROM AUTHOR]

Thermal demagnetization furnaces are widely used paleomagnetic facilities for progressive removal of naturally acquired magnetic remanence or the imparting of well-controlled laboratory magnetization. An ideal thermal demagnetizer should maintain "zero" magnetic field in the sample chamber during thermal treatments. However, magnetic field noises, including the residual magnetic fields of the construction material and the induced fields caused by the alternating current (AC) in the heating element are always present, which can contaminate the paleomagnetic results at the elevated temperatures or especially for the magnetically weak samples. Here, we designed a new structure of heating wire named "straight core solenoid" to develop a new demagnetization furnace with ultra-low magnetic field noise. Simulation and practical measurements show that the heating current magnetic field can be greatly reduced by using the new technology. Thermal demagnetization experiments demonstrate that the new demagnetizer can yield low noise results even for weakly magnetic samples. [ABSTRACT FROM AUTHOR]

The thick sequence of Cenozoic deposits in the Qaidam Basin of the NE Tibetan Plateau has great potential for understanding the tectonic and climatic evolution of the region. In this study, we performed detailed rock magnetic analyses of a well-dated (~20.7–11.2 Ma) Upper Cenozoic sedimentary sequence from the Huatugou (HTG) section in the NW Qaidam Basin. The magnetic susceptibility of the sequence is relatively low before 17.4 Ma, high during 17.4–14.5 Ma, and lower after 14.5 Ma again. This pattern is consistent with the occurrence of the Mid-Miocene Climatic Optimum (MMCO) during 17.4–14.5 Ma, with global climatic cooling thereafter. Measurements of multiple rock magnetic parameters indicate a peak in the concentration of fine-grained magnetic minerals during 17.4–14.5 Ma. This feature demonstrates that the enhancement of the magnetic susceptibility is due to the pedogenic production of superparamagnetic (SP) and single domain (SD) magnetite, suggesting the occurrence of relatively high effective precipitation and high temperature in the Qaidam Basin at this time. Comparing with regional and global climatic records, the warm and humid climatic conditions coincide with the MMCO, implying that global climate changes were responsible for the climatic evolution in the Qaidam Basin throughout the MMCO. However, after 14.5 Ma, the rapid uplift of the northern Tibetan Plateau caused it to reach a critical elevation which blocked the moisture supply to the Qaidam Basin and may also have contributed to the observed climatic changes. • Detailed rock magnetic analyses identify the MMCO during 17.4–14.5 Ma. • A pedogenic model accounts for the magnetic enhancement of during the MMCO. • Global climate change has caused the MMCO event in the Qaidam Basin. [ABSTRACT FROM AUTHOR]