Plantlet regeneration from a NaCl-selected salt-tolerant callus culture of Shamouti orange (Citrus sinensis L. Osbeck)

Plantlets were regenerated from a selected salt-tolerant cell line of Shamouti orange (Citrus sinensis L. Osbeck). Embryogenesis was carried out both in the presence and absence of NaCl, yielding green and white globular embryos, respectively. Greening could be induced subsequently and normal heart shape embryo development was obtained. Plantlet formation required exposure to kinetin prior to the introduction of the root-inducing hormone naphthalene acetic acid. This system differs from the designed protocol for plant regeneration from the salt-sensitive, i.e., unselected callus. It is concluded that NaCl interferes with the regeneration process, with embryogenesis and/or embryo development into plantlets. Its presence during callus growth probably changes the balance of the phytohormones which is later manifested in plant regeneration. Citrus salt-tolerant callus yields salt-tolerant embryos. Salt-tolerant calli derived from regenerated plantlets indicate acquisition of salt tolerance on the whole plant level.     

Proteins, non-structural carbohydrates and organic acids in the flowers of sweet orange (Citrus sinensis (L.) osbeck)

The concentration of soluble proteins in open flowers of sweet orange (Citrus sinensis (L.) Osbeck) was about 35% of the protein content found in green leaves, while ovary and stigma, with attached style, contained up to 85%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) indicates that flowers and leaves contained ribulose bisphosphate carboxylase-oxygenase (Rubisco). At least 12 polypeptides, ranging from 22 to 100 kDa, were more distinct in flowers than in leaves. The polypeptide band at about 100 kDa in the flower extract suggests the presence of phosphoenolpyruvate carboxylase (PEPCase) in citrus flowers. Activity of Rubisco and PEPCase, expressed in μmol g tissue fresh weight⁻¹ hr⁻¹, averaged 14.2 and 64.6 for intact open flowers, and 547.9 and 63.3 for the leaves, respectively. Starch and reducing sugars were 1.2- and 8.4-fold higher, respectively, and dark respiration rates were about five-fold greater for open flowers than fully expanded, sun leaves. Quinic and malic acids made up about 96% of the organic acids found in flowers and leaves. Ascorbic, citric, fumaric, and shikimic acids were in small or trace amounts. The large accumulation of starch and soluble sugars, in addition to the presence and activity of Rubisco and PEPCase, indicates that the flowers of sweet orange would have some capability to perform photosynthetic CO₂ assimilation, the metabolites of which might play some important role in flower development and fruit setting.     

Purification of cytochrome c peroxidase for monitoring H2O2 production

One of the most precise methods of determining hydrogen peroxide (H₂O₂) formation by biological systems is based on measuring the rate of enzyme-substrate complex formation between H₂O₂ and cytochrome c peroxidase (CCP). The main problem with this method is that CCP is not commercially available and has to be prepared in the laboratory. We have modified some currently available methods for purifying a highly active preparation of CCP in about 4 d. It includes a batch extraction of protein using DEAE-sepharose followed by concentration either by lyophilization or by passing the extract through a small DEAE-sepharose column instead of by ultrafiltration. The concentrated preparation is passed through a Sephadex G-75 column and the final CCP crystallized against water. The final preparations had a purity index (PI, ratio of absorbance at 408 nm/280 nm, equivalent to heme/protein ratio) above 1.2. These changes make the overall procedure very simple, preserving enzyme activity and spectral properties. In addition, we point out that special care has to be taken to eliminate cytochrome c from crude CCP extracts. Cytochrome c not only introduces an artifact when determining PI, but is also may act as a hydrogen donor for CCP when monitoring H₂O₂ formation, thus decreasing the sensitivity of this method.     

外源H_2O_2对低温胁迫下柑橘叶片抗寒性的影响

以柑橘品种‘日南1号’离体秋稍为试材,采用Hoagland营养液培养方法,研究添加不同浓度H_2O_2处理对4℃低温胁迫下柑橘生长状态和叶片细胞相对电导率(REC)、丙二醛(MDA)含量、脯氨酸含量以及过氧化氢酶(CAT)、超氧化物歧化酶(SOD)和过氧化物酶(POD)活性等生理指标的影响,筛选缓解柑橘低温伤害的最佳H_2O_2处理浓度,探讨外源H_2O_2处理对柑橘耐寒能力影响机制。结果显示:随低温胁迫时间的延长,各处理组柑橘叶片卷曲和叶片细胞膜伤害程度均逐渐加重;外源施加0.2和1.0mmol·L-1 H_2O_2处理均能缓解低温胁迫引起的叶片卷曲和萎蔫,降低叶片中REC和MDA的升高,减少叶片细胞中内源H_2O_2的积累,提高渗透调节物质脯氨酸的含量和抗氧化酶SOD、CAT和POD的活性,并以1.0mmol·L-1 H_2O_2缓解效果更为显著。研究表明,4℃低温能够引起柑橘离体秋梢叶片卷曲、枯萎、脱落和细胞膜伤害症状,外源1.0mmol·L-1 H_2O_2可以通过提高叶片的脯氨酸含量和SOD、CAT和POD抗氧化酶活性,有效缓解低温对柑橘叶片细胞膜的伤害,从而增强其抗寒性。     

H2O2预处理胜利褐煤镜质组的生物产气研究

【目的】研究H₂O₂处理对煤中镜质组生物产气的影响。【方法】选择内蒙古胜利褐煤作为研究对象,以实验室前期富集保存的产甲烷微生物作为出发菌群,首先通过浮选对煤炭进行显微组分分离(高镜质组GJ、中镜质组ZJ和低镜质组DJ),并对煤的物化性质进行表征,然后在固液比1:15、H₂O₂浓度10%、预处理时间30 d条件下用H₂O₂处理不同镜质组含量的样品,再以处理前后的原煤及残煤进行生物产气实验。采用气相色谱、X射线衍射和傅里叶变换红外光谱等方法分析H₂O₂处理前后产气及煤的物化性质变化。【结果】经过H₂O₂预处理后,煤中镜质组的含量有所下降,挥发成分增加,固定碳减少,H₂O₂与高镜质组煤样反应更剧烈,氧含量增加,碳含量减少。未经过处理的煤在100 d时产甲烷量为GJ＞ZJ＞DJ,分别为174.24、164.31、135.52 μmol/g煤,而经过H₂O₂预处理的煤在20 d后停止产气,最终产甲烷量分别为39.63、39.61、41.55μmol/g煤,比原煤产气减少了77.26%、75.89%和69.34%。随着镜质组含量的增加,经过H₂O₂处理后的煤样芳香环层片的层间距d₀₀₂、单层层片的延展度L_a和层片的堆叠度L_c减小,而芳香层数N增加,表明晶核结构变小。经过H₂O₂处理后煤芳烃碳、芳香族、C=O基团和C=C基团所占比例增加,芳环缩合度增大,含氧官能团变多。【结论】利用H₂O₂长时间处理使煤基质中较易被微生物利用的有机质结构减少,从而降低了产气能力。     

外源H2O2和·OH对大麦幼苗根系线粒体膜脂和流动性的伤害

以大麦(HordeumvulgareL.)为材料,研究了外源H2O2和*OH对大麦根系呼吸速率、线粒体膜流动性和膜脂脂肪酸组成的影响。结果表明,10mmol/LH2O2或·OH处理4d,大麦幼苗根系呼吸速率和线粒体膜脂不饱和脂肪酸含量及脂肪酸不饱和指数下降,线粒体膜脂荧光强度增加,膜流动性下降,且H2O2或·OH处理浓度(在0.1～10mmol/L范围内)越高,膜脂流动性下降越明显。H2O2和·OH处理的同时加入同浓度的抗坏血酸(AsA)和甘露醇,膜流动性明显增强或恢复。     

RNA-Seq揭示Foc4在外源氧化胁迫(H_2O_2)下的基因表达及细胞代谢变化

尖孢镰刀菌古巴专化型4号小种(Fusarium oxysporum f. sp. cubense race 4,Foc4)是香蕉枯萎病的强致病性病原菌。Foc4在侵染香蕉植株早期必须面对寄主的活性氧迸发。【目的】了解Foc4应对外源氧化胁迫的分子机制。【方法】利用Illumina 2500 RNA-Seq测序平台分析了经外源氧化胁迫(H_2O_2)处理的Foc4与对照在转录组水平的基因表达差异。【结果】在外源氧化胁迫条件下,Foc4的生长受到抑制。转录组测序获得了超过2千万条clean reads。进一步的差异基因表达分析以差异倍数FC (fold change)≥2且FDA值≤0.001为选择标准,发现496个基因表达上调,298个基因表达下调。GO功能富集分析显示,429个基因比对到GO功能分析数据库,在这些差异表达基因中,许多与代谢过程、生物调节、细胞过程和刺激应答有关。KEGG通路富集分析显示,有141个表达差异显著基因比对到KEGG中的50条代谢途径。其中,主要是各类氨基酸代谢途径、脂肪酸代谢途径。同时也包括与抗氧化胁迫直接相关的代谢途径,包括DNA的损伤修复、类胡萝卜素的生物合成、过氧化物酶体、谷胱甘肽代谢等。【结论】这些结果暗示,为了在强氧化胁迫环境下生存,Foc4细胞从包括直接应对氧化胁迫的信号调控途径在内的物质代谢和能量代谢均发生改变以应对环境变化的胁迫。     

Oligochitosan induced Brassica napus L. production of NO and H2O2 and their physiological function

NO (nitric oxide) and H₂O₂ (hydrogen peroxide) are important signaling molecule in plants. Brassica napus L. was used to understand oligochitosan inducing production of NO (nitric oxide) and H₂O₂ (hydrogen peroxide) and their physiological function. The result showed that the production of NO and H₂O₂ in epidermal cells of B. napus L. was induced with oligochitosan by fluorescence microscope. And it was proved that there was an interaction between NO and H₂O₂ with L-NAME (N^G-nitro-l-arg-methyl eater), which is an inhibitor of NOS (NO synthase) in mammalian cells that also inhibits plant NO synthesis, and CAT (catalase), which is an important H₂O₂ scavenger, respectively. It was found that NO and H₂O₂ induced by oligochitosan took part in inducing reduction in stomatal aperture and LEA protein gene expression of leaves of B. napus L. All these results showed that oligochitosan have potential activities of improving resistance to water stress.     

Synthesis and structure of a lead(II)-citrate: {Na(H2O)3}[Pb5(C6H5O7)3(C6H6O7)(H2O)3]·9.5H2O

The reaction of lead(II) nitrate with trisodium citrate Na₃(C₆H₅O₇) in a 1:22.5 ratio at pH 4.8 provides crystals of {Na(H₂O)₃}[Pb₅(H₂O)₃(C₆H₅O₇)₃(C₆H₆O₇)]·9.5H₂O (1). The structure of 1 is two-dimensional and exhibits five distinct Pb(II) sites and four different modes of citrate bonding. The five lead sites all display hemidirected coordination geometries, that is, irregular distribution of neighboring oxygen atoms resulting in obvious gaps in the coordination spheres. Consequently, the lead coordination geometries exhibit proximal bonding to a number of oxygen donors, as well as distal interactions with nearest neighbors. The coordination numbers vary from 8 to 10, with ‘5+3’, ‘5+4’, ‘6+4’ and ‘7+3’ coordination modes where the first number refers to the proximal ligands and the second to the distal set. The four crystallographically distinct citrate groups include three with deprotonated carboxylate groups (C₆H₅O₇)³⁻ and one with a single protonated carboxyl group (C₆H₆O₇)². The citrate ligands bridge 3, 5, 7 and 7 lead sites. Three of the citrate groups exhibit tridentate chelation coordination to a lead site through two carboxylate oxygen donors and the hydroxyl groups. One citrate group projects an uncoordinated -OH group and a pendant protonated carboxyl group into the interlamellar domain. This latter carboxyl group coordinates to a sodium cation, which exhibits five coordinate geometry defined by three aqua ligands and the carbonyl oxygen of the -CO₂H groups in the basal plane and a citrate -OH donor in the apical position.     

Selective synthesis of triangular cluster oxido-sulfidocomplexes of Mo and W: High yield preparations of [Mo3O2S2(H2O)9], [W3O2S2(H2O)9], [W2MoO2S2(H2O)9] and their derivatization

Reaction of [Mo₂O₂(μ-S)₂(H₂O)₆]²⁺ with Mo(CO)₆ or metallic Mo under hydrothermal conditions (140 °C, 4 M HCl) gives oxido-sulfido cluster aqua complex [Mo₃(μ₃-S)(μ-O)₂(μ-S)(H₂O)₉]⁴⁺ (1). Similarly, [W₃(μ₃-S)(μ-O)₂(μ-S)(H₂O)₉]⁴⁺ (2) is obtained from [W₂O₂(μ-S)₂(H₂O)₆]²⁺ and W(CO)₆. While reaction of [Mo₂O₂(μ-S)₂(H₂O)₆]²⁺ with W(CO)₆ mainly proceeds as simple reduction to give 1, [W₂O₂(μ-S)₂(H₂O)₆]²⁺ with Mo(CO)₆ produces new mixed-metal cluster [W₂Mo(μ₃-S)(μ-O)₂(μ-S)(H₂O)₉]⁴⁺ (3) as main product. From solutions of 1 in HCl supramolecular adduct with cucurbit[6]uril (CB[6]) {[Mo₃O₂S₂(H₂O)₆Cl₃]₂CB[6]}Cl₂⋅18H₂O (4) was isolated and structurally characterized. The aqua complexes were converted into acetylacetonates [M₃O₂S₂(acac)₃(py)₃]PF₆ (M₃ = Mo₃, W₃, W₂Mo; 5a-c), which were characterized by X-ray single crystal analysis, electrospray ionization mass spectrometry and ¹H NMR spectroscopy. Crystal structure of (H₅O₂)(Me₄N)₄[W₃(μ₃-S)(μ₂-S)(μ₂-O)₂(NCS)₉] (6), obtained from 2, is also reported.     

Crystal structure of nonaquasamarium(III)bromide-l,4-dioxan adduct (1:3:2), Sm(H2O)9·Br3(C4H8O2)2

The title compound has been found to consist of tricapped trigonal prismatic Sm(H₂O)₉³⁺ ions in C_2v symmetry, sandwiched between expanded ‘close packed’ layers of bromide ions, with 1,4-dioxan molecules in chair conformation hydrogen bonding between the equatorial water molecules of adjacent cations.Orthorhombic, Amm2, a = 8.010(3), b = 19.848(4), c = 7.388(3) Å, R = 0.022 for 992 unique reflexions.     

水分胁迫下苹果叶片的H2O2代谢

轻度水分胁迫下苹果叶片Pr迅速升高,CAT活性变化不大,NaHSO3处理能显著降低叶内H2O2含量,表明光呼吸的加强促进了H2O2产生可能是叶内H2O2大量积累的主要原因;中度水分胁迫下叶片AsA含量的下降和Mehler反应的增强都非常明显,DDTC和AsA处理都能有效降低叶内H2O2积累,但MV处理的作用不大,说明叶片H2O2主要来源于Mehler反应,AsA降解造成叶片对H2O2清除能力的下降是其积累的根本原因;严重水分胁迫时,NaHSO3和DDTC都不能有效地减轻叶内H2O2积累,光呼吸和Mehler反应都可能不是H2O2的主要来源。     

Rb2[B12(OH)12]·2H2O and Rb2[B12(OH)12]·2H2O2: Hydrate and perhydrolate of rubidium dodecahydroxo-closo-dodecaborate

The orthorhombically crystallizing salts Rb₂[B₁₂(OH)₁₂]·2H₂O (a = 1576.81(9), b = 813.08(5), c = 1245.32(7) pm) and Rb₂[B₁₂(OH)₁₂]·2H₂O₂ (a = 1616.54(9), b = 814.29(5), c = 1260.12(7) pm) could be prepared from Rb₂[B₁₂H₁₂] and hydrogen peroxide. Both crystal structures were determined by X-ray single crystal diffraction and refined in the space group Cmce. They are not isostructural to the other compounds containing icosahedral dodecahydroxo-closo-dodecaborate dianions [B₁₂(OH)₁₂]²⁻ and potassium, rubidium or cesium cations already known to literature, but both title compounds crystallize quasi-isotypically exhibiting Rb⁺ cations in 10-fold oxygen coordination. The hydrogen peroxide adduct (Rb₂[B₁₂(OH)₁₂]·2H₂O₂) is explosive on shock and heat, while the hydrate (Rb₂[B₁₂(OH)₁₂]·2H₂O) is not.     

肉桂醛调控不结球白菜多胺氧化酶-过氧化氢系统缓解硒胁迫的机理研究北大核心CSCD

硒(Se)胁迫通常引发植物细胞生理损伤,进而抑制植物生长。肉桂醛(CA)是一种具有抗氧化特性的天然化合物。该研究以不结球白菜(Brassica rapa)幼苗根为研究材料,采用多种生理生化以及原位荧光检测手段,研究了多胺氧化酶-过氧化氢(PAO-H_(2)O_(2))系统参与肉桂醛缓解硒胁迫的作用方式。结果表明:(1)硒胁迫显著抑制不结球白菜幼苗根的生长,并呈现浓度效应,而肉桂醛能显著缓解硒胁迫导致的生长抑制。(2)肉桂醛能够显著缓解硒胁迫诱导的根细胞氧化损伤和细胞死亡。(3)硒胁迫导致根内PAO活性和H_(2)O_(2)水平显著升高,而加入肉桂醛后可显著抑制PAO活性并降低H_(2)O_(2)水平。(4)在不结球白菜体内6个BrPAOs家族基因(BrPAO1-6)中,硒胁迫能够诱导BrPAO3、BrPAO5和BrPAO6表达量显著上调,而肉桂醛可显著抑制硒胁迫的这种诱导效应。研究发现,肉桂醛可通过抑制PAO-H_(2)O_(2)系统有效缓解不结球白菜的硒胁迫伤害,为外源调控作物耐受硒胁迫提供了新证据。