Comparison of the responses to NaCl stress of two pea cultivars using split-root system

Two pea (Pisum sativum L.) cultivars were compared: cv Lincoln and cv Douce de Provence. Seedlings grown for 14 d on standard medium were challenged for 21 d with salt using a split-root system. This protocol allowed salt-treated plants to absorb nutrients through a part of their root system maintained in control medium (C), the other part of the root system being placed in medium added with 75 mM NaCl (S). Full salt treatment (S/S) resulted in severe but non-lethal growth inhibition, high concentration of Na⁺ and Cl⁻ in leaves, and decrease in leaf K⁺ and chlorophyll contents. The two latter effects were more pronounced in Lincoln than in D. Provence. Growth inhibition was partially (Lincoln) or totally (D. Provence) alleviated in S/C configuration, and K⁺ content was less diminished than in full salt treatment. S/C treatment mitigated Na⁺ and Cl⁻ accumulation in Lincoln, but not in D. Provence. Thus, in the latter cultivar, growth inhibition by salt in S/S condition likely did not result from excessive Na⁺ and Cl⁻ accumulation in leaves. Increased electrolyte leakage from leaf tissues evidenced damages to leaf cell plasma membrane of both cultivars in S/S condition. However, damages to chloroplasts, as inferred from chlorophyll loss, were much pronounced in Lincoln than in D. Provence. Antioxidant enzymic activities in leaves were measured as proxies for oxidative stress. Catalase activity was stimulated by S/S treatment in both cultivars, but superoxide dismutase (Fe and Cu/Zn isoforms) and gaiacol peroxidase activities were augmented only in Lincoln. The absence of superoxide dismutase activity stimulation by salt in D. Provence could signify either that constitutive activity was sufficient to ensure protection against oxidative stress, or that intrinsic salt tolerance of this cultivar mitigated cellular oxidative stress. Thus, intraspecific variability for salt response exists between pea cultivars presenting similar growth sensitivity to salt.     

炭疽病对不同核桃品种抗性生理指标的影响

核桃是我国重要木本油料及经济树种,其生长发育、坚果产量及品质易受病害影响,其中炭疽病为核桃主要病害之一。因此,深入了解常见核桃品种响应炭疽病的能力,可为选育抗病性较强品种提供理论依据。对‘香玲’‘西洛3’‘西林3’‘契可’核桃分别进行炭疽病胁迫,分析胁迫下的活性氧（ROS）代谢以及抗氧化酶活性。结果表明,炭疽病菌胁迫前各植株生理指标差异均不明显,胁迫后各植株均表现为ROS（H₂O₂、O^·-₂）积累增多,膜脂过氧化（MDA）加剧,抗氧化酶（SOD、POD、CAT）活性增强。其中‘契可’MDA含量明显高于‘香玲’‘西洛3’‘西林3’;‘西林3’‘契可’的H₂O₂与O^·-₂含量明显高于‘香玲’‘西洛3’。而‘香玲’的SOD、POD、CAT活性明显高于‘西洛3’‘西林3’‘契可’,且活性增强幅度为‘香玲’>‘西洛3’>‘西林3’>‘契可’。由此可知‘香玲’‘西洛3’‘西林3’‘契可’核桃响应炭疽病的生理表现上为‘香玲’>‘西洛3’>‘西林3’>‘契可’。     

Physicochemical and Reactive Oxygen Species Scavenging Properties of Collagen and Collagen Hydrolysates from Farmed Globefish (Fugu rubripes) Bone

Globefish (Fugu rubripes) bone collagen (GBC) was isolated and characterized. Electrophoresis and Fourier transform infrared (FTIR) spectra indicated that GBC was high-purity type I collagen with an intact triple-helical structure. Amino acid analysis revealed that GBC contained higher glycine content (364 residues/1,000 residues) than that of other fishery bones, and the imino acid content was 189 residues/1,000 residues. The denaturation temperature (T_d) of GBC was 27.1°C. GBC displayed a rapid fibril-forming rate and well-defined fibril morphology in vitro. Globefish bone collagen hydrolysates (GBCH) were optimized by neutral protease through response surface methodology (RSM) with the highest hydroxyl radical (?OH) scavenging capacity. The optimal hydrolysis condition was a reaction temperature of 48.4°C, time of 120 min, and enzyme/substrate ratio of 2520 U/g. Three fractions were collected by ultrafiltration, and the fraction GBCH-III (Mw<1 kDa) possessed the strongest ?OH scavenging ability. Reactive oxygen species (ROS) scavenging capacities were evaluated with two model systems: ?OH and nitric oxide (NO?). The ROS scavenging capacities increased in a dose-dependent manner. GBCH-III proved to be a more effective ?OH scavenger than reduced glutathione (GSH). These findings demonstrated that GBC and GBCH have potential as an alternative source of collagen-derived materials for use in pharmaceutical, nutraceutical, and cosmetic industries.     

低温胁迫对不同抗寒性甘蔗品种幼苗叶绿体生理代谢的影响

土培桶栽抗寒品种GT28与不抗寒品种ROC22,测定正常(28℃)和低温(4℃)条件下甘蔗幼苗叶片的质膜透性、叶绿素荧光参数等相关生理指标。结果表明,低温与正常条件下相比,两品种幼苗叶片的膜透性显著增大,且ROC22增幅较大;初始荧光(F_o)、非光化学猝灭系数(NPQ)显著上升,最大光能转化效率(F_v/F_m)、反应中心激发能捕获效率(F_v'/F_m')、光化学猝灭系数(q_P)、PSII实际量子效率(Φ_PSII)均下降,以ROC22降幅较大;叶绿体希尔反应活力、Mg²⁺-ATPase、Ca²⁺-ATPase活性下降,叶绿体中丙二醛(MDA)含量增加,以ROC22变幅较大;超氧化物歧化酶(SOD)、过氧化物酶(POD)、谷胱甘肽还原酶(GR)活性均上升,GT28的增幅比ROC22显著。上述参数与品种抗寒性密切相关,GT28比ROC22抗寒性更强。     

腐殖质促进植物根和地上部生长的信号传导和串扰机制研究进展

天然高分子异构混合物腐殖质（HS）是陆地生态系统的重要组成部分,其促生作用近年来被广泛研究,其中多条信号通路在 HS 促进植物生长发育过程中起到重要作用。该文综述了 HS 促进植物根和地上部生长发育的信号通路传导及串扰机制。HS 在促进根系生长过程中吲哚乙酸（Indole-3-acetic acid,IAA）、一氧化氮（Nitric oxide,NO）、脱落酸（Abscisic acid,ABA）、活性氧（Reactive oxygen species,ROS）和 Ca2+ 等信号通路传导及相互串扰过程参与其中;HS 在促进地上部生长过程中细胞分裂素（Cytokinin,CTK）、ABA 和硝酸盐信号通路发生复杂的传导和相互串扰过程。HS 通过复杂的代谢网络调控植物生理代谢,调节机制涉及多条复杂信号通路的传导和串扰过程,其中质膜 H+-ATPase 是 HS 促进地下和地上部生长机制研究中的关键节点,多条信号通路通过质膜 H+-ATPase 介导相互级联放大的信号传导。在 HS 调控根系和地上部生长发育过程中,信使 NO 与多条信号通路间发生复杂的串扰过程,是参与 HS 促生作用的重要串扰信号分子。HS 在触发根和地上部生长发育过程中还存在其他信号通路,其中防御信号通路水杨酸（Salicylicacid,SA）和茉莉酸（Jasmonic acid,JA）受到信号通路 IAA、NO、ABA 和 CTK 等的调节。由于 HS 具有分散性、异质性和生物化学研究复杂性的特点,至今尚未明确 HS 对植物生长短期作用机制以及在整个植物生长周期内的整体作用机制,因此需要进一步深入分析揭示促生过程中所涉及到的信号传导、交叉、串扰和整合途径,以及复杂的营养和代谢通路,为 HS 生理活性作用机制和农业生产应用的研究提供理论依据。     

不利环境对昆虫抗氧化酶影响的研究进展

昆虫体内的抗氧化酶主要包括超氧化物歧化酶、过氧化氢酶、过氧化物酶等,当机体受到不利环境的刺激或胁迫时,体内活性氧急剧增加,此时相应的抗氧化酶活性升高,多种抗氧化酶协同作用降低活性氧含量并使之处于一个低浓度的动态平衡状态。为系统地认识昆虫抗氧化酶在应对不利环境胁迫时的反应及保护机制,对昆虫的保护酶系统在重金属胁迫、农药污染、环境因子变化等不利条件下的酶活性变化趋势和协同作用进行综述。     

氧含量急剧变化对冷血脊椎动物氧化压力的影响

氧气对大多生物体至关重要,但是氧气能转变为活性氧从而对机体产生毒性。多种冷血脊椎动物可耐受自然条件下产生的氧化压力,如某些鱼、蛙、龟和蛇等。综述了缺氧/低氧耐受性动物在环境、代谢产生供氧不足时的应对方式。对比这些动物的应对方式后发现了某些抗氧化能力提高的规律。机体一般采用关键抗氧化酶的酶活增强、谷胱甘肽含量增多来抵御氧化压力。     

伏马菌素B1诱导Marc-145细胞caspase非依赖型程序性细胞死亡

[目的]以Marc-145细胞为模型,研究了伏马菌素B1能否导致细胞产生其他类型程序性细胞死亡。[方法]利用caspase抑制剂、蛋白合成抑制剂、非凋亡程序性细胞死亡necroptosis抑制剂及ROS抑制剂,分别抑制caspase活性、蛋白质合成、necroptosis和ROS,采用结晶紫染色和AnnexinV-FITC/PI双染分析这些抑制剂对伏马菌素B1诱导Marc-145细胞死亡的影响。[结果]caspase、necroptosis抑制剂和2种自由基抑制剂不能抑制伏马菌素B1诱导的Marc-145细胞死亡,但蛋白合成抑制剂则可以显著抑制伏马菌素B1诱导的Marc-145细胞死亡。[结论]伏马菌素B1所诱导的Marc-145细胞的死亡是一种受基因表达调控的程序性细胞死亡,但与caspase、ROS和nec-roptosis无关。     

含海藻糖稀释剂增补EDTA对猪精子冷冻能力的影响

探讨了猪精子冷冻保存液中添加不同浓度的海藻糖(trehalose)和EDTA(0.05mol/L trehalose、0.05mol/L trehalose 2.0mmol/LEDTA、0.05mol/L trehalose 5.0mmol/L EDTA、0.1mol/L trehalose、0.1mol/L tre-halose 2.0mmol/LEDTA、0.1mol/L trehalose 5.0mmol/LEDTA)对猪精子冷冻效果的影响。结果表明,精子冷冻解冻后,0.1mol/Ltrehalose 2mmol/LEDTA混合处理组精子活力显著高于0.1mol/Ltrehalose处理组(P<0.05),0.1mol/Ltrehalose和5.0mmol/LEDTA混合处理组的精子生存率最高。0.1mol/Ltrehalose和2~5mmol/LEDTA混合处理组精子顶体完整率显著高于trehalose处理组(P<0.05),0.05~0.1mol/Ltrehalose和5.0mmol/LEDTA混合处理组低渗膨胀精子率显著高于trehalose处理组(P<0.05)。trehalose和EDTA混合处理组精子内活性氧(ROS)含量总体上高于trehalose处理组(P<0.05)。这些结果显示稀释剂中trehalose和EDTA增补能改善精液特性,但不能抑制精子内ROS的发生。     

植物细胞质APX1的研究进展

活性氧(ROS)在植物生长发育和对各种逆境适应过程中扮演双面角色：高浓度下引起氧化损伤、低浓度下发挥第二信使作用,其角色转换取决于其产生和清除之间的平衡状态,并严格受控于体内一套由酶和非酶组分构成的双元抗氧化系统。在抗氧化酶类中,位居细胞质的抗坏血酸过氧化物酶1(APX1)在胞内氧化还原态水平调控中起到关键作用,在ROS清除网络中居于核心地位,已被视作ROS功能的重要杠杆,并因而获得相对最广泛的研究关注。着重介绍了其酶学特性、基因表达和调控、生物学作用及目前主要在植物抗逆基因工程中的应用研究进展,以期为日后植物ROS和抗逆性研究提供有用信息和思路。