No abstract

Betaine (BET) is a native compound widely studied as an antioxidant in agriculture and human health. However, the antioxidant mechanism of BET remains unclear. In this research, radical scavenging assays showed that BET had little free radical scavenging activity. However, the antioxidant activity of BET was confirmed by cellular antioxidant activity (CAA) and erythrocyte hemolysis assays. The results of quantitative PCR (qPCR) and enzyme activity determination kits showed that the antioxidant activity of BET was not due to the gene expression and activity of antioxidases. High-pressure liquid chromatography (HPLC) assessment of the effect of BET on sulfur-containing amino acid metabolism showed that BET increased the levels of nonenzymatic antioxidants,S-adenosylmethionine (SAM) and methionine (p < 0.05), via the regulation of the methionine-omocysteine cycle. Additionally, the three methyl groups of BET were found to play a key role in its antioxidant activity. The possible reason was that because of the hydrophobicity of the three methyl groups and hydrophilicity of the carboxyl of BET, a tight protective membrane was formed around cells to prevent oxidative stress inducer from inducing ROS generation and cell damage. In conclusion, the antioxidant mechanism of BET was found to enhance nonenzymatic antioxidant defenses via the methionine-homocysteine cycle and form a protective membrane around cells.

Eukaryotic elongation factor-2 kinase (eEF-2K), a negative regulator of protein synthesis, has been shown to play an important role in modulating autophagy and apoptosis in tumor cells under various stresses. In this study, we investigated the regulatory role of eEF-2K in pyroptosis (a new form of programmed necrosis) in doxorubicin-treated human melanoma cells. We found that doxorubicin (0.5-5 μmol/L) induced pyroptosis in melanoma cell lines SK-MEL-5, SK-MEL-28, and A-375 with high expression of DFNA5, but not in human breast cancer cell line MCF-7 with little expression of DFNA5. On the other hand, doxorubicin treatment activated autophagy in the melanoma cells; inhibition of autophagy by transfecting the cells with siRNA targeting Beclin1 or by pretreatment with chloroquine (20 μmol/L) significantly augmented pyroptosis, thus sensitizing the melanoma cells to doxorubicin. We further demonstrated that doxorubicin treatment activated eEF-2K in the melanoma cells, and silencing of eEF-2K blunted autophagic responses, but promoted doxorubicin-induced pyroptotic cell death. Taken together, the above results demonstrate that eEF-2K dictates the cross-talk between pyroptosis and autophagy in doxorubicin-treated human melanoma cells; suppression of eEF-2K results in inhibiting autophagy and augmenting pyroptosis, thus modulating the sensitivity of melanoma cells to doxorubicin, suggesting that targeting eEF-2K may reinforce the antitumor efficacy of doxorubicin, offering a new insight into tumor chemotherapy.

In our previous study, three novel polysaccharides, named MC-1, MC-2, and MC-3, were separated from the roots of maca (Lepidium meyenii), which is a food source from the Andes region. The structural information and immunomodulatory activity of MC-1 were then investigated. The structure and activity of MC-2 are still unknown. In this study, structural characterization revealed that MC-2 has an average molecular weight of 9.83 kDa and is composed of arabinose (20.9%), mannose (4.5%), glucose (71.9%), and galactose (2.7%). The main linkage types of MC-2 were proven to be (1→5)-α-l-Ara, (1→3)-α-l-Man, (1→)-α-d-Glc, (1→4)-α-d-Glc, (1→6)-α-d-Glc, and (1→6)-β-d-Gal by methylation and NMR analyses. Congo red assay showed that MC-2 possesses a triple-helix conformation. Immunostimulating assays indicated that MC-2 could induce M1 polarization of original macrophages and convert M2 macrophages into M1 phenotype. Although MC-2 could not shift M1 macrophages into M2, it could still inhibit inflammatory reactions induced by lipopolysaccharide. Furthermore, Toll-like receptor 2, tTll-like receptor 4, complement receptor 3, and mannose receptor were confirmed as the membrane receptors for MC-2 on macrophages. These results indicate that MC-2 could potentially be used toward hypoimmunity and tumor therapies.

No abstract

Feeding experiments using three strains of entomopathogenic fungi, Beauveria bassiana, Metarhizium anisopliae and Isaria fumosorosea were conducted with newly moulted 3rd-5th instar Ocinara varians Walker larvae in the laboratory. The mortality of larvae immersed individually in spore suspension (1 × 10 7 spores/mL) of all the strains was ≥ 80% except 5th instar larvae treated with M. anisopliae which transformed into pupae, but did not result in adult emergence. The growth (total body mass), consumption, relative consumption rate and relative growth rate, were reduced at all three larval stages, while developmental time was extended in infected larvae with concurrent significant increase in approximate digestibility in infected larvae. Conversion of digested food (ECD) and ingested food (ECI) values declined in infected larvae as compared to the healthy larvae (control). The 5th instar larvae treated with M. anisopliae showed higher ECD and ECI values than control. Based on mortality and growth inhibition it can be suggested that all the studied fungal strains have a high potential for biocontrol and could be developed into biocontrol agents against O. varians.

No abstract

DNA methylation plays important roles in responses to environmental stimuli. However, in perennial plants, the roles of DNA methylation in stress-specific adaptions to different abiotic stresses remain unclear. Here, we present a systematic, comparative analysis of the methylome and gene expression in poplar under cold, osmotic, heat, and salt stress conditions from 3h to 24h. Comparison of the stress responses revealed different patterns of cytosine methylation in response to the four abiotic stresses. We isolated and sequenced 1376 stress-specific differentially methylated regions (SDMRs); annotation revealed that these SDMRs represent 1123 genes encoding proteins, 16 miRNA genes, and 17 long non-coding RNA (lncRNA) genes. The SDMR162 region, consisting of Psi-MIR396e and PsiLNCRNA00268512, is regulated by epigenetic pathways and we speculate that PsiLNCRNA00268512 regulates miR396e levels by acting as a target mimic. The ratios of methylated cytosine declined to ~35.1% after 1 month of recovery from abiotic stress and to ~15.3% after 6 months. Among methylated miRNA genes, only expression of the methylation-regulated gene MIRNA6445a showed long-term stability. Our data provide a strong basis for future work and improve our understanding of the effect of epigenetic regulation of non-coding RNA expression, which will enable in-depth functional analysis.