Estrogen Receptor β Signaling Induces Autophagy and Downregulates Glut9 Expression

Glut9 is highly expressed in the human kidney proximal convoluted tubular and plays a crucial role in the regulation of plasma urate levels. The gene effects were stronger among women. Our results show that 17-β-estradiol (E2) through ER (estrogen receptor) β downregulates Glut9 protein expression on human renal tubular epithelial cell line (HK2). Intriguingly, E2 does not affect the expression of Glut9 mRNA. ERβ is linked to PTEN, the PTEN gene negatively regulates the PI3K/AKT pathway, and the PI3K/AKT pathway inhibition may lead to autophagy. Further study indicates that ERβ may affect the expression of Glut9 though autophagy.     

Variation of δ<Superscript>13</Superscript>C of wood and foliage with canopy height differs between evergreen and deciduous species in a temperate forest

We investigated post-photosynthetic fractionation and carbon transfer mechanisms of different plant functional types growing under the same climatic conditions in North-eastern China. The variations in δ¹³C of trunk and branches were compared with leaf δ¹³C at different canopy heights of Pinus koraiensis (evergreen coniferous species), Larix gmelinii (deciduous coniferous species) and Quercus mongolica (deciduous broad-leaved species). Results showed that δ¹³C of leaves increased (became more enriched) with increasing canopy height for both coniferous species (P. koraiensis, L. gmelinii) but not for Q. mongolica (a deciduous broad-leaved species). δ¹³C of both trunk and branches also increased with sampling height for the evergreen conifer P. koraiensis but did not significantly vary for either of the deciduous species (L. gmelinii or Q. mongolica), except a significant increase in branch δ¹³C for L. gmelinii. Similarly, δ¹³C of trunk and branches were strongly correlated with leaf δ¹³C only in the evergreen conifer, P. koraiensis. ¹³C was consistently more enriched in trunk, branches, and roots compared to leaves in all three species. Our findings suggest that, even under the same climatic conditions, different plant functional types may exhibit different carbon transfer mechanisms. This is contrary to the previous hypothesis that different carbon transfer mechanisms operate in forests of different climatic zones, especially in tropical and temperate forests. Particularly, the differences occur predominantly between evergreen and deciduous trees rather than between coniferous and broad-leaved trees. The significant difference in δ¹³C between leaves and wood tissues confirms a previous post-photosynthetic isotope fractionation in temperate forests.     

精氨酸抗氧化作用机制

精氨酸是一种功能性氨基酸,在机体生理功能、新陈代谢和营养等方面发挥着重要作用。精氨酸具有抗氧化能力。目前的体外研究表明精氨酸具有较强的清除DPPH自由基、ABTS自由基、超氧自由基能力以及一定的还原力。作为一种带电子的碱性氨基酸,精氨酸可能通过胍基基团向自由基提供电子并与其作用,终止自由基链式反应,从而显示出还原能力与体外抗氧化能力。体内实验则表明精氨酸能有效地提高机体总抗氧化能力,降低体内自由基含量,抑制ROS生成与积累,促进谷胱甘肽(GSH)合成与积累,增强内源性抗氧化酶(CAT、SOD、GPx等)活性,抑制氧化应激的产生。精氨酸能够通过精氨酸——一氧化氮途径、GSH途径、Nrf2信号通路途径及其他途径发挥体内抗氧化作用。本文主要综述了目前精氨酸体外与体内抗氧化功能及其相关作用机制的研究进展,为精氨酸的实际应用提供理论指导意义。     

Physiological Evaluation of Drought Stress Tolerance and Recovery in Cauliflower (Brassica oleracea L.) Seedlings Treated with Methyl Jasmonate and Coronatine

Coronatine (COR) is a chlorosis-inducing phytotoxin that mimics some biological activities of methyl jasmonate (MeJA). Although MeJA has been reported to alleviate drought stress, it is unclear if COR has the same ability. Our objective was to determine the influence of exogenously applied MeJA and COR on the growth and metabolism of cauliflower seedlings under drought stress and recovery. Both MeJA and COR enhanced the growth and accumulation of dry matter in cauliflower seedlings during drought-stressed and rewatering conditions. Treatment with MeJA or COR enhanced tolerance of drought stress through increased accumulation of chlorophyll and net photosynthetic rate. Enzymatic (superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, and glutathione reductase) and nonenzymatic antioxidant (proline and soluble sugar) systems were activated, and lipid peroxidant (malondialdehyde and hydrogen peroxide) was suppressed by MeJA and COR under drought stress. MeJA and COR also increased leaf relative water content and endogenous abscisic acid level under drought-stressed conditions. After rewatering, the contents of leaf water, chlorophyll, abscisic acid, and photosynthetic characteristics as well as enzymatic and nonenzymatic antioxidant systems showed nearly complete recovery. Both MeJA and COR can alleviate the adverse effects of drought stress and enhance the ability for water stress resistance through promotion of defense-related metabolism in cauliflower seedlings.     

Purification and characterization of prokaryotically expressed human interferon-λ2

A system for the production of soluble interferon (IFN)-λ2 was developed by fusing the IFN-λ2, NusA protein, polyhistidine and S peptide genes and then expressing the fused product (Nus-His-S-tagged IFN-λ2) in Escherichia coli. The expressed fusion protein was purified by Ni-NTA affinity chromatography. The fusion tag was removed from recombinant IFN-λ2 by cleavage with enterokinase. N-Terminal sequencing confirmed the identity of the purified protein. When compared with commercial IFN-α2b, IFN-λ2 had similar antiviral activity. The production and characterization of biologically active IFN-λ2 will be beneficial for its potential role in clinical applications.     

Uniconazole-induced tolerance of soybean to water deficit stress in relation to changes in photosynthesis, hormones and antioxidant system

This study investigated whether uniconazole confers drought tolerance to soybean and if such tolerance is correlated with changes in photosynthesis, hormones and antioxidant system of leaves. Soybean plants were foliar treated with uniconazole at 50 mg L-1 at the beginning of bloom and then exposed to water deficit stress at pod initiation for 7 d. Uniconazole promoted biomass accumulation and seed yield under both water conditions. Plants treated with uniconazole showed higher leaf water potential only in water-stressed condition. Water stress decreased the chlorophyll content and photosynthetic rate, but those of uniconazole-treated plants were higher than the stressed control. Uniconazole increased the maximum quantum yield of photosystemand ribulose-1,5-bisphosphate carboxylase/oxygenase activity of water-stressed plants. Water stress decreased partitioning of assimilated 14C from labeled leaf to the other parts of the plant. In contrast, uniconazole enhanced translocation of assimilated 14C from labeled leaves to the other parts, except stems, regardless of water treatment. Uniconazole-treated plants contained less GA3, GA4 and ABA under well-watered condition than untreated plants, while the IAA and zeatin levels were increased substantially under both water conditions, and ABA concentration was also increased under water stressed condition. Under water-stressed conditions, uniconazole increased the content of proline and soluble sugars, and the activities of superoxide dismutase and peroxidase in soybean leaves but not the malondialdehyde content or electrical conductivity. These results suggest that uniconazole-induced tolerance to water deficit stress in soybean was related to the changes of photosynthesis, hormones and antioxidant system of leaves.     

Exogenous Gamma-aminobutyric Acid Coordinates Active Oxygen and Amino Acid Homeostasis to Enhance Heat Tolerance in Wheat Seedlings

Heat stress has detrimental impacts on wheat growth and yield formation. Conferring heat tolerance through applying plant growth regulators is a feasible strategy to reduce loss. Gamma aminobutyric acid (GABA) is a four-carbon non-proteinogenic amino acid existing in organisms and accumulates in response to stress. In this study, spring wheat Liaochun17 and winter wheat Jingdu 40 were used to investigate the function of exogenous GABA on the heat tolerance of wheat seedlings. Data displayed that GABA treatment not only reduced the production of reactive active oxygen (ROS), but also improved the scavenging capacity of diphenyl picryl phenyl hydrazine active oxygen under heat stress, thus alleviating the accumulation of malondialdehyde and the damage of cell membrane. In addition, analysis of protein and amino acids revealed that GABA effectively promoted the accumulation of soluble protein and coordinated amino acid homeostasis. Summarily, our current findings revealed that GABA strengthened the resistance of wheat seedling to heat stress by maintaining the metabolism balance of ROS and amino acids.