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The role of ferroptosis in steatohepatitis development is largely unknown. We investigated (1) whether hepatocyte ferroptosis occurs in a gene-modified steatohepatitis model without modifying dietary components, (2) whether ferroptosis occurs at an early stage of steatohepatitis, and (3) whether apomorphine, recently reported as a ferroptosis inhibitor, can ameliorate steatohepatitis. Hepatocyte-specific PTEN KO mice were used. Huh 7 and primary cultured hepatocytes isolated from the mice were used in this study. The number of dead cells increased in 10-week-old PTEN KO mice. This cell death was suppressed by the administration of ferroptosis inhibitor ferrostatin-1 for 2 weeks. Apomorphine also ameliorated the severity of steatohepatitis. Treatment with ferroptosis inhibitors, including apomorphine, decreases the level of lipid peroxidase. Apomorphine suppressed cell death induced by RSL-3 (a ferroptosis inducer), which was not suppressed by apoptosis or necroptosis inhibitors. Apomorphine showed a radical trapping capacity with much more potent activity than ferrostatin-1 and Trolox, a soluble form of vitamin E. In addition, apomorphine activated nrf2 and its downstream genes, including HO-1 and xCT. In conclusion, ferroptosis occurs in steatohepatitis from an early stage in PTEN KO mice. In addition, apomorphine ameliorates the severity of steatohepatitis by inhibiting ferroptosis.

Silicon (Si) is a ubiquitous element in soil with well-known beneficial effects under certain conditions, in several plant species, if supplied in available form for uptake. It may alleviate damage in various stress situations and may also promote growth when no obvious stressors are applied. Effects of Si are often linked to mitigation of oxidative stress, in particular to the induction of antioxidant defense mechanisms. In the work presented, the impact of silicon provision on pro-oxidant systems was investigated in cucumber. Plants of the F1 cultivar hybrid 'Joker' were grown under in vitro conditions in the absence of any applied external stressor. Silicon provision decreased H 2 O 2 content and lowered lipid peroxidation in the leaves of the treated plants. This was paralleled by declining polyamine oxidase (PAO) and diamine oxidase (DAO) activities. Several PAO as well as lipoxygenase (LOX) genes were coordinately downregulated in Si-treated plants. Unlike in similar systems studied earlier, the Si effect was not associated with an increased transcript level of gene coding for antioxidant enzymes. These results suggest an inhibitory effect of Si provision on pro-oxidant amine oxidases, which may decrease the level of reactive oxygen species by retarding their production. This extends the molecular mechanisms linked to silicon effects onto redox balance in plants.

Two cucumber F1 cultivar hybrids were investigated for stress tolerance markers upon application of different strength of Hoagland fertigation solutions (HG). 'Joker' and 'Oitol' cultivar hybrids were studied, representing typically field grown and greenhouse cultivated genotypes, respectively. At standard fertigation level (0.5 × HG) in controlled environment young 'Joker' plants displayed slower growth than 'Oitol' based on total leaf area. At this basal nutrient concentration leaves of 'Joker' plants had significantly lower antioxidant capacity and higher malondialdehyde (MDA, an indicator of lipid peroxidation) level than 'Oitol'. According to RT-qPCR transcript levels of several antioxidant enzymes' genes (ascorbate peroxidase, glutathione reductase and glutathione peroxidase) were significantly higher in 'Joker' compared to 'Oitol'. At increased HG concentrations (1.0, 1.5, 2.0, and 2.5 × HG) growth didn't change significantly in either hybrid. Osmotic potential declined at higher fertigation levels. Antioxidant capacity increased in both hybrids with strong characteristic differences favouring 'Oitol' plants. Higher MDA content of leaves testified more oxidative burden in 'Joker' plants at all and especially at the more concentrated HG treatments. This trend was also approved by results of bio photon emission imaging, which is a powerful method to quantify stress level in living tissues with autoluminescence detection technology. Gene expression for antioxidant enzymes followed HG concentration-dependent increase in both hybrids, at a substantially higher level in 'Joker'. Expression of the dehydrin gene DHN3 was preferentially induced at elevated fertigation levels in 'Oitol' plants, which could contribute to the lower oxidative stress detected in this hybrid. Results presented in this report demonstrate differences in shoot growth, antioxidant capacity, level of oxidative stress and antioxidant gene expression in two contrasting cucumber hybrids at basal fertigation. Furthermore, excessive HG fertigation was found to increase oxidative stress in a genotype-specific way. This effect may be due to different antioxidant capacity and differential expression of stress protective genes, such as the DHN3 dehydrin., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)