红曲糟抗热肽的制备及其对酿酒酵母热激氧化耐受性的影响

制备红曲糟抗热肽,研究其对酿酒酵母抵御热激氧化行为的影响。以酿酒酵母热激存活率为指标,筛选蛋白酶,通过抗热肽得率优化酶解条件,对抗热肽进行质谱和抗氧化能力分析,通过磷酸戊糖通路基因表达、胞内辅酶、谷胱甘肽(glutathione,GSH)以及活性氧自由基(reactive oxygen species,ROS)含量分析,从抗氧化角度探索抗热肽对酿酒酵母的热保护作用。结果表明,红曲糟抗热肽最佳酶解工艺为:红曲糟蛋白和水固液比1∶10(m/m)、复合蛋白酶酶解、温度50℃、时间3 h、加酶量3000 U/g、pH 8.5,该条件下抗热肽得率62.44%,酿酒酵母热激存活率73.97%,较纯水组提高了22.76%。序列鉴定表明,丰度前20的肽段中16条肽段的疏水氨基酸占比50%以上。抗热肽1,1-二苯基-2-三硝基苯肼自由基半数清除量为4.53 mg/mL,2,2′-联氮双(3-乙基苯并噻唑啉-6-磺酸)阳离子自由基半数清除量为1.82 mg/mL,具有抗氧化活性。同时,抗热肽通过上调磷酸戊糖途径的基因表达量,提升NADH激酶活性,促进还原型辅酶II的转化,使GSH含量提高4.74倍,胞内ROS水平与热激前酿酒酵母基本保持一致,从而有效提高了酿酒酵母抵御热激氧化胁迫的能力。

青菜热水浴处理保绿机理研究

通过对热处理后青菜组织内部叶绿素-蛋白质牢固性、叶 绿素降解产物和过氧化物酶活性变化的检测,初步考察 了青菜热水浴处理的保绿机理。结果表明,叶绿素的降解 速率与叶绿素-蛋白质结合牢固性之间无显著相关性:热 处理抑制了脱镁叶绿素氧化酶的活性,使叶绿素降解中 间产物造成积累,进而对叶绿素酶和脱镁叶绿素螯合酶 形成反馈抑制,从而延缓了青菜叶片的黄化;热处理抑制 了过氧化物酶的活性,从而阻止了由过氧化物酶引起的 过氧化反应对叶绿体的伤害,减缓了叶绿素的降解。热水 浴处理影响了青菜蛋白质的合成,产生了热激蛋白 (HSPs)。

Regulation of Heat Shock Factor AtHsfA1a on Ascorbate Peroxidase under Heat Stress in Arabidopsis thaliana

[Objective] This study was conducted to investigate the regulation of heat shock factor AtHsfA1a on ascorbate peroxidase under heat stress in Arabidopsis thaliana. [Method] After heat stress treatment on transgenetic A. thaliana with silenced endogenetic AtHsfA1a gene and wild A. thaliana plants as materials, the change in activity of APX enzyme was analyzed by spectrophotometry, the expression level of APX gene was investigated by real-time fluorescent quantitative PCR, and the binding condition of AtHsfAla with the promoter region of APX gene was analyzed by chromatin immunoprecipitation assay. [Result] The activity and mRNA level of APX in plants with silenced endogenetic AtHsfAla gene were higher than those in wild plants. Fragments of the promoter region of APX gene were not screened from the plants with silenced endogenetic AtHsfA1a gene, but found in wild plants. [Conclusion] This study provides a theoretical basis for the understanding of the important role of AtHsfAla in resistance to stress in plant, and is of great significance to the revealing of mechanism of resistance to stress in plant.

Regulatory Mechanism of Tea Polyphenols on Heat Stress in Animals

Teapolyphenols are the generic term of polyphenols in tea.Tea polyphenols are non-toxic and odorless with high oxidation resistance.Heat stress causes oxidative stress,which impairs the capacity of antioxidant defense system and immunity,thereby seriously affecting the production performance of animals.Teapolyphenols could reduce heatstress response in animals by scavenging harmful free radicals and increasing the activities of antioxidant enzymes.

Inducible heat shock protein 70 kD and inducible nitric oxide synthase in hemorrhage/resuscitation-induced injury

Inducible heat shock protein 70 kD (HSP-70i) has been shown to protect cells, tissues, and organs from harmful assaults in in vivo and in vitro experimental models. Hemorrhagic shock followed by resuscitation is the principal cause of death among trauma patients and soldiers in the battlefield. Although the underlying mechanisms are still not fully understood, it has been shown that nitric oxide (NO) overproduction and inducible nitric oxide synthase (iNOS) overexpression play important roles in producing injury caused by hemorrhagic shock including increases in polymorphonuclear neutrophils (PMN) infiltration to injured tissues and leukotriene B4 (LTB4) generation. Moreover, transcription factors responsible for iNOS expression are also altered by hemorrhage and resuscitation. It has been evident that either up-regulation of HSP-70i or down-regulation of iNOS can limit tissue injury caused by ischemia/reperfusion or hemorrhage/resuscitation. In our laboratory, geldanamycin, a member of ansamycin family, has been shown to induce HSP-70i overexpression and then subsequently to inhibit iNOS expression, to reduce cellular caspase-3 activity, and to preserve cellular ATP levels. HSP-70i is found to couple to iNOS and its transcription factor. Therefore, the complex formation between HSP-70i and iNOS may be a novel mechanism for protection from hemorrhage/resuscitation-in-duced injury.

Effects of (–)-5-hydroxy-equol on the lifespan and stress resistance of Caenorhabditis elegans

Caenorhabditis elegans （C. elegans） was used as an animal model to study the effect of （-）-5-hydroxy-equol, a microbialmetabolite of isoflavone genistein, on the lifespan, fecundity and resistance against thermal and oxidative stress. The resultsshowed that （-）-5-hydroxy-equol not only significantly increased the lifespan of C. elegans but also significantly enhancedthe resistance against thermal and oxidative stress at the concentrations of 0.1 mmol/L and 0.2 mmol/L. However, the fecundityof C. elegans was not obviously influenced after being exposed to the same concentrations of （-）-5-hydroxy-equol. Further studieson comparative transcriptome analyses and the lifespan ofdaf-16 （mu86） mutant and daf-2 （e1370） mutant indicated that（-）-5-hydroxy-equol prolonged the lifespan of C. elegans through DAF-2/DAF-16 Insulin/IGF-1 signaling pathway. This isthe first report that （-）-5-hydroxy-equol was able to increase the lifespan and improve the thermal and oxidative stress toleranceof C. elegans.