干旱胁迫下杏叶片膜脂脂肪酸组分和乙烯释放及LOX活性的变化

自然干旱条件下,杏叶片相对含水量和脂肪酸不饱和指数(IUFA)随干旱时间的延长而逐渐下降,细胞质膜透性增大,乙烯释放率和脂氧合酶(LOX)活性均表现出"先上升后下降"的趋势.恢复灌水后这些指标有不同程度的恢复.抗旱性强的品种"冰佳娜丽"在干旱条件下能维持较高的叶片相时含水量,较低的细胞质膜透性、乙烯释放率及LOX活性.     

表没食子儿茶素没食子酸酯和茶黄素对秀丽隐杆线虫耐温性的影响

为探究绿茶和红茶中的代表性组分对秀丽隐杆线虫在不同温度条件下的作用效果及机制,试验设置0.25、2.5、25 μmol/L 表没食子儿茶素没食子酸酯（epigallocatechin gallate,EGCG）和茶黄素（theaflavin,TF1）,测定线虫在4 ℃和35 ℃条件下的存活率,进而测定在4 ℃、20 ℃和30 ℃条件下经25 μmol/L EGCG和TF1孵育后线虫体内脂肪含量和线粒体膜电位的变化。结果显示,25 μmol/L EGCG将热应激线虫的最大寿命和中位寿命分别提高了8.15%、22.44%,将冷应激线虫的最大寿命和中位寿命分别降低了20.25%、17.94%。25 μmol/L TF1对热应激线虫的存活率无显著影响,将冷应激线虫的最大寿命和中位寿命分别提高了9.43%、19.01%。在4 ℃条件下,EGCG和TF1孵育均提高了线虫体内的脂肪含量,TF1孵育降低了线虫的线粒体膜电位水平。在20 ℃条件下,EGCG和TF1具有明显的降脂作用,长时间孵育可显著提高衰老线虫线粒体活性。在30 ℃条件下,EGCG和TF1提高了线虫体内的脂肪含量。以上结果表明,在低温条件下TF1通过促进线粒体产热而非脂肪动员提高了线虫的存活率,而EGCG孵育可诱导线虫死亡。     

Hesperetin attenuates hypoxia/reoxygenation-induced apoptosis in H9c2 cells via inhibition of calcium overload

AIM: To investigate the effect of hesperetin on hypoxia/reoxygenation (H/R)-induced apoptosis in the H9c2 cells and to clarify the underlying mechanism. METHODS: The H/R model was established and the H9c2 cells were pretreated with hesperetin for 4 h. The cell viability and cell damage were measured by CCK-8 assay and lactate dehydrogenase (LDH) detection. The apoptosis was analyzed by Hoechst 33258 staining and flow cytometry. The intracellular calcium fluorescence intensity was measured by fluorescence microscopy and flow cytometry. The calcium-ATPase activity and the level of adenosine triphosphate (ATP) were measured by ELISA. The mitochondrial membrane potential was measured by JC-1 staining. The protein expression levels of Bcl-2, Bax and cytochrome C (Cyt-C) were determined by Western blot. RESULTS: Hesperetin reduced the apoptosis of the H9c2 cells induced by H/R, decreased intracellular Ca²⁺ fluorescence intensity, elevated Ca²⁺-ATPase activity, inhibited the mitochondrial membrane potential depolarization and increased the level of ATP (P<0.05). In addition, hesperetin significantly reduced the release of Cyt-C protein from mitochondria to cytoplasma and increased the Bcl-2/Bax ratio (P<0.05). After using the calcium ion inhibitor nimodipine, the percentage of the cells with mitochondrial membrane depolarization was decreased, the ATP level was increased and the protein expression of mitochondrion-related apoptosis molecules were decreased (P<0.05). CONCLUSION: Hesperetin reduces the apoptosis of the H9c2 cells induced by H/R, which may be related to inhibition of calcium overload and improvement of mitochondrial function.     

干旱胁迫对蒲公英渗透调节物质、酶保护系统及质膜水孔蛋白PIP2-3基因表达的影响

为了揭示蒲公英在干旱胁迫下渗透调节和酶保护系统的作用机理以及质膜水孔蛋白PIP2-3基因的表达特征,采用盆栽控水试验,研究了不同干旱胁迫RWC=(90±5)%、RWC=(75±5)%、RWC=(50±5)%下蒲公英渗透调节物质、酶保护系统以及质膜水孔蛋白基因的相关表达。结果表明:随着干旱胁迫的加重,蒲公英叶片中的可溶性糖、可溶性蛋白、游离脯氨酸的含量显著增加,超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)的活性显著提高,在轻度胁迫(MS)中呈持续上升的趋势,重度胁迫(SS)中则呈现先升高后下降的趋势(可溶性糖除外);质膜水孔蛋白PIP2-3基因的相对表达量上调,轻度胁迫(MS)显著高于重度胁迫(SS)。复水7 d后,渗透调节物质的积累以及SOD的含量下降,但仍显著高于CK,POD、CAT的含量以及质膜水孔蛋白PIP2-3基因的相对表达量恢复正常,说明在干旱胁迫条件下蒲公英通过增加渗透调节物质的积累,提高酶保护系统的活性来增强植株的抗逆性,上调质膜水孔蛋白基因的相对表达量来加强水分运输能力。     

可食性液态膜复合保鲜剂对番茄保鲜效果的研究

以番茄为试材,通过壳聚糖、可溶性淀粉、羧甲基纤维素钠配制成不同浓度的复合保鲜液浸泡涂膜处理,研究其对番茄保鲜效果的影响。结果表明,复合保鲜液涂膜可有效地降低番茄果实的失重率、腐烂率、可溶性固形物含量,抑制多酚氧化酶活性,维持番茄VC含量,保持番茄果实较好的感官品质,且以0.5%壳聚糖+0.8%可溶性淀粉+0.3%羧甲基纤维素钠复配的复合保鲜液涂膜对番茄有较好的保鲜效果,15℃环境下其货架期延长到15 d以上。     

热处理对低温胁迫下黄瓜活性氧代谢和膜脂组分的影响

为探讨热处理减轻黄瓜果实低温冷害的作用机理,本试验研究了47℃热水浸泡5 min处理对黄瓜果实在4℃贮藏期间活性氧代谢和膜脂组分的影响。结果表明,47℃热水5 min处理可显著抑制黄瓜果实冷害的发生,贮藏15 d后果实冷害指数较对照(CK)低20.87%。此外,热处理还可抑制黄瓜相对电导率及丙二醛(MDA)含量的上升,提高黄瓜果实超氧化物歧化酶(SOD)、过氧化物酶(DOD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)的活性,抑制超氧阴离子($\mathop{{O}}_{2}^{{\mathop{}_{\ ·}^{-}}}$)及过氧化氢(H₂O₂)的产生,同时降低脂氧合酶的活性,保持较低的饱和脂肪酸含量、较高的不饱和脂肪酸含量和膜脂不饱和度。综上,热处理可维持黄瓜果实活性氧代谢的平衡,抑制膜脂的过氧化作用,从而提高黄瓜果实的抗冷性,减轻果实冷害损伤。     

Effect of Fucoidan on the Mitochondrial Membrane Potential (ΔΨm) of Leukocytes from Patients with Active COVID-19 and Subjects That Recovered from SARS-CoV-2 Infection

Fucoidan is a polysaccharide obtained from marine brown algae, with anti-inflammatory, anti-viral, and immune-enhancing properties, thus, fucoidan may be used as an alternative treatment (complementary to prescribed medical therapy) for COVID-19 recovery. This work aimed to determine the ex-vivo effects of treatment with fucoidan (20 µg/mL) on mitochondrial membrane potential (ΔΨm, using a cationic cyanine dye, 3,3′-dihexyloxacarbocyanine iodide (DiOC₆(3)) on human peripheral blood mononuclear cells (HPBMC) isolated from healthy control (HC) subjects, COVID-19 patients (C-19), and subjects that recently recovered from COVID-19 (R1, 40 ± 13 days after infection). In addition, ex-vivo treatment with fucoidan (20 and 50 µg/mL) was evaluated on ΔΨm loss induced by carbonyl cyanide 3-chlorophenylhydrazone (CCCP, 150 µM) in HPBMC isolated from healthy subjects (H) and recovered subjects at 11 months post-COVID-19 (R2, 335 ± 20 days after infection). Data indicate that SARS-CoV-2 infection induces HPBMC loss of ΔΨm, even 11 months after infection, however, fucoidan promotes recovery of ΔΨm in PBMCs from COVID-19 recovered subjects. Therefore, fucoidan may be a potential treatment to diminish long-term sequelae from COVID-19, using mitochondria as a therapeutic target for the recovery of cellular homeostasis.     

嗜水气单胞菌外膜蛋白(OMP)在乳酸乳球菌中的表达及其对BALB/c小鼠的免疫保护效果

乳酸球菌(Lactococcus lactis)是一种安全级微生物,为活载体疫苗传递抗原的理想选择.嗜水气单胞菌(A eromonas hydrophila,Ah)能引起鱼类等多种动物的败血病,因其血清型众多,寻找共同保护性抗原是进行疫苗研究的重点.为探究嗜水气单胞菌AS1.927株外膜蛋白(OMP)在乳酸乳球菌中的表达和检测其表达产物对小鼠的免疫保护效果,本研究将己克隆的ompA基因经BamH Ⅰ和Xba Ⅰ双酶切后连接载体pNZ8048,转化乳酸乳球菌NZ9000,nisin诱导表达,并进行SDS-PAGE分析鉴定.结果显示,重组基因工程菌L.lactis[pNZ-ompA]表达的融合蛋白分子量约为36.2 kD,成熟蛋白分子量约为33.7 kD.将重组基因工程菌L.lac tis [pNZ-ompA]口服免疫BALB/c小鼠(Mus musculus),用放射免疫法检测末次免疫一周后的各组小鼠肠粘膜分泌型免疫球蛋白A(sIgA)的水平以及用间接ELISA法检测小鼠血清特异性抗体IgG,结果发现,该重组基因工程菌能显著提高sIgA的分泌(P＜0.05);同时在小鼠血清中的特异性抗体含量也显著高于对照组(P＜0.05).末次免疫两周后用100 LD50的Ah AS 1.927(3.3×105 cfu/mL)腹腔注射攻击小鼠,口服重组菌对小鼠的相对免疫保护力(relative percent survival,RPS)为87.5％,表明重组基因工程菌可诱导小鼠对AhAS1.927产生一定的免疫保护作用.该结果将为开发安全有效的口服基因工程鱼用疫苗提供一定的实验基础.     

嗜水气单胞菌外膜蛋白（OMP）的原核表达及其对BALB/c小鼠的免疫保护研究

为确定嗜水气单胞菌(Aeromonas hydrophila,Ah)AS1.927株外膜蛋白(OMP)的原核表达产物是否具有抗原性及其对小鼠的免疫保护力.本研究根据GenBank上嗜水气单胞菌外膜蛋白ompA基因序列(GenBank登录号:AF146597)设计1对引物,克隆出ompA全长基因1020 bp(GenBank登录号:EU309491),经Sal Ⅰ和Xhol Ⅰ双酶切后连接pET-30a(+),转化大肠杆菌(Escherichia cDli)BL21,IPTG诱导表达,并进行SDS-PAGE及Westernblot分析鉴定.结果显示重组基因工程菌E.coli[pET-30a-ompA]表达的融合蛋白分子量约为40.7kD,可以被鼠抗嗜水气单胞菌外膜蛋白抗血清识别.将重组基因工程菌Ecoli[pET-30a-om-pA]口服免疫BALB/c小鼠(Mus mussulus);末次免疫1周后用放射免疫分析小鼠肠粘膜分泌型免疫球蛋白A(sIgA)水平,检测结果揭示,该重组基因工程菌能提高sIgA的分泌(P<0.05);同时在小鼠血清中测出特异性抗体IgG(P<0.05).末次免疫2周后用100 LD50的Ah AS1.927(3.3×105> cfu/mL)腹腔注射攻击小鼠,口服重组菌对小鼠的相对免疫保护力(relative percent survival,RPS)为75%,表明重组基因工程菌可诱导小鼠对AhAS1.927产生一定的免疫保护作用.