甲壳素对连作平邑甜茶生长、光合及抗氧化酶的影响

以苹果连作土盆栽的平邑甜茶幼苗为试材,探讨了0、0.5、1.0和2.5 g·kg-1不同施入量的甲壳素对其光合速率、活性氧含量及抗氧化酶活性的影响。结果表明,1.0 g·kg-1的甲壳素处理能显著促进幼苗株高、地径,干样质量和根冠比的增加,根冠比为对照的1.51倍;明显提高了幼苗叶片光合色素含量、净光合速率和蒸腾速率,其中光合速率为对照的1.30倍;同时提高了幼苗叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性,分别为对照的1.10倍、1.85倍、1.77倍和1.43倍;减少了叶片丙二醛(MDA)、过氧化氢(H2O2)和超氧阴离子的积累,分别为对照的73%、62%和34%,降低了脯氨酸(Pro)和可溶性糖含量。当甲壳素施用量为2.5 g·kg-1时则显著抑制平邑甜茶幼苗生长,降低幼苗叶片光合速率和抗氧化酶活性,并使超氧阴离子和脯氨酸含量明显上升。因此,适宜用量的甲壳素能减轻苹果的连作障碍。     

Oxygen isotope ratios of plant available phosphate in lowland tropical forest soils

Phosphorus (P) cycles rapidly in lowland tropical forest soils, but the process have been proven difficult to quantify. Recently it was demonstrated that valuable data on soil P transformations can be derived from the natural abundance of stable oxygen isotopes in phosphate (δ¹⁸O_P). Here, we measured the δ¹⁸O_P of soils that had received long-term nutrient additions (P, nitrogen, and potassium) or litter manipulations in lowland tropical forest in Panama and performed controlled incubations of fresh soils amended with a single pulse of P. To detect whether δ¹⁸O_P values measured in the incubations apply also for soils in the field, we examined the δ¹⁸O_P values after rewetting dry soils. In the incubations, resin-P δ¹⁸O_P values converged to ∼3.5‰ above the expected isotopic equilibrium with soil water. This contrasts with extra-tropical soils in which the δ¹⁸O_P of resin-P matches the expected equilibrium with soil water. Identical above-equilibrium resin-P δ¹⁸O_P values were also found in field soils that did not receive P additions or extra litter. We suggest that the 3.5‰ above-equilibrium δ¹⁸O_P values reflect a steady state between microbial uptake of phosphate (which enriches the remaining phosphate with the heavier isotopologues) and the release of isotopically equilibrated cell internal phosphate back to the soil. We also found that soil nutrient status affected the microbial turnover rate because in soils that had received chronic P addition, the original δ¹⁸O_P signature of the fertilizer was preserved for at least eight weeks, indicating that the off-equilibrium δ¹⁸O_P values produced during microbial phosphate turnover was not imprinted in these soils. Overall, our results demonstrate that ongoing microbial turnover of phosphate mediates its biological availability in lowland tropical soils.     

小麦灌浆后期青枯骤死原因分析及控制

小麦灌浆后期植株衰老与活性氧自由基毒害和膜脂质过氧化密切相关。灌浆后期株体内活必砼谢平衡失调是青枯发生的主要内因：造成青枯的外因除与“Ｖ”型变温有关外，雨后骤晴的强光与高温协同作用亦是青枯发生的重要外因一。灌浆后期“Ｖ”型变温使麦株各器均受到伤害，尤其穗下茎受到伤害。青枯能否发生取决于植体内酶活力的高低、非酶清除剂含量的多少以及“Ｖ”型变温的强度和持续时间。选择优良品种、适时播种、合理施肥和加强     

鸡血藤提取物的制备及药理毒理研究

目的：研究鸡血藤不同极性段提取物的制备方法、抗炎抗氧化活性,评价其安全性。方法：采用水、丙酮和乙醇等不同极性溶剂对鸡血藤有效成分进行提取,探讨鸡血藤不同极性段提取物体外清除自由基能力,并进行鸡血藤水提取物毒理学试验和体内抗炎作用研究。结果：鸡血藤各种提取物在体外均具有一定的清除羟自由基的能力;鸡血藤水提取物具有一定的抗炎活性;最大耐受量为120g／kg,为实际无毒。结论：鸡血藤水提取物具有抗炎、抗氧化活性,安全性好。     

茉莉酸类化合物与单线态氧相互作用的研究进展

茉莉酸类化合物包括茉莉酸及其衍生物,是一类基本的植物激素,作为信号分子在植物的生长发育和胁迫信号响应过程中具有重要的作用.在茉莉酸类化合物对外界环境防御和调控细胞凋亡过程中,与单线态氧相互作用.现主要介绍了茉莉酸类化合物信号转导过程与单线态氧的相互作用.     

Differential response of zucchini varieties to low storage temperature

Several parameters related to cold damage in zucchini have been measured in fruits from different varieties cultivated in the province of Almería (south-eastern Spain). The purpose of this work is to correlate physiological parameters with commercial quality and chilling damage, in order to establish reliable criteria for selecting varieties having better genetic adaptation to low-temperature storage. The results show that, for varieties harvested during February, the variety Natura was the best adapted to storage at 4 °C, as its fruits suffered less from chilling injuries, had a lower weight loss, and the levels of metabolites malonyldialdehyde and H₂O₂ were not as high as in the other varieties. Genetic variation was detected for some of the parameters analysed. The positive correlation among the levels of MDA, H₂O_2, and chilling injury, as well as the negative correlation among catalase and chilling injury, makes these parameters good indicators of chilling damage in our system.     

Homocysteine thiolactone damages cultured endothelial cells

AIM: To approach the mechanisms of homocysteine thiolactone (HTL)-induced damage in endothelial cells. METHODS: Human umbilical vein endothelial cells (HUVECs) were incubated with HTL. The concentrations of soluble intercellular adhesion molecule (sICAM)-1 and TNF-α in the conditioned medium were measured by ELISA. The activity of NF-κB and the level of ROS were determined by fluorescence microscopy. Cell viability,activity of lactate dehydrogenase (LDH) and content of nitric oxide (NO) in the medium were also detected. RESULTS: Exposure of HUVECs to HTL at concentration of 1 mmol/L for 3 h potentiated the activity of NF-κB and increased the level of ROS. Incubation of HUVECs with HTL (1 mmol/ L for 24 h) markedly decreased the cell viability and NO content, and increased the level of LDH, sICAM-1 and TNF-α in the culture medium. Pretreatment with NAC, apocynin or PDTC markedly inhibited the increased activity of NF-κB and decreased the levels of ROS, TNF-α, sICAM-1, NO and LDH in a dose-dependent manner. CONCLUSION: The dysfunction of endothelial cells induced by homocysteine thiolactone in vitro may be related to the oxidative stress and the activation of NF-κB.     

Cardioprotective effect of sevoflurane preconditioning on ROS production in rat heart with ischemia-reperfusion

AIM: To investigate the effects of sevoflurane preconditioning on the production of reactive oxygen species (ROS) and nitric oxide (NO), the activity of superoxide dismutase(SOD), glutathione peroxide(GPx) and catalase(CAT) in myocardial ischemia-reperfusion injury(IRI). METHODS: Sixty rats were randomly allocated to 8 groups. Following 2% sevoflurane preconditioning for 30 min, the left anterior descending artery was ligated for 30 min and then reperfused for 120 min in vivo. The infarction size of the hearts was measured with the staining of 2,3,5-triphenyltetrazoliumchloride. The myocardial apoptotic index was measured by the method of TUNEL. The ROS fluorescent probe dihydroethidium was used for the measurement of ROS. The myocardium was homogenized for the measurement of NO, SOD, GPx and CAT. To evaluate the effects of ROS and NO on the cardioprotection of sevoflurane preconditioning, ROS scavenger N-(2-mercaptopropionyl) glycine (2-MPG) or NOS inhibitor N^ω-nitro-L-arginine methyl ester (L-NAME) were employed to block their actions. RESULTS: Compared with control group, the production of ROS was induced by sevoflurane preconditioning before ischemia-reperfusion injury (12.0±0.8 vs 2.6±0.5, P<0.05) and decreased after ischemia-reperfusion injury (16.2 ±0.9 vs 24.9±1.3, P<0.05). 2-MPG decreased the elevation of ROS caused by sevoflurane preconditioning before ischemia-reperfusion injury (5.1±0.7 vs 12.0±0.8, P<0.05). No difference of ROS production between treating with 2-MPG+Sevo+IRI and with IRI (24.9±1.4 vs 24.9±1.3, P>0.05) was observed. Compared with control group, sevoflurane preconditioning also induced the generation of NO (34.5±3.2 vs 15.9±1.4, P<0.05) and the activity of SOD(1.5±0.5 vs 0.6±0.2, P<0.05), GPx(22.8±2.5 vs 12.7±2.2, P<0.05) and CAT(15.5±1.8 vs 11.2±1.4, P<0.05). 2-MPG blocked the increase in NO production and inhibited the activity of SOD,GPx,CAT. L-NAME also attenuated the activity of SOD,GPx,CAT. CONCLUSION: Sevoflurane preconditioning protects the rat heart against ischemia-reperfusion injury by reducing the infarction size and apoptosis. Production of ROS at sub-injury dose induced by sevoflurane preconditioning stimulates the myocardium to create SOD,GPx,CAT and NO, thus inhibiting the further formation of ROS and protecting the heart under the condition of ischemia-reperfusion.     

Infrared spectroscopic study of alkaline oxygen treatment of lignin with ATR technique in aqueous state 1: method for determining quantitative spectra of oxygen-degraded lignin

For the fundamental study of oxygen delignification of kraft pulp, structural changes of kraft lignin during alkaline oxygen treatment were investigated with the use of infrared measurement with attenuated total reflectance (ATR) technique. In the neutralized reaction mixture of alkaline oxygen-treated kraft lignin, there is a significant amount of NaCl, so that the spectral changes of water due to the coexistence of NaCl was investigated, and how to remove the huge absorption of NaCl solution is discussed. Sodium vanillate–NaCl solutions were employed as model solutions for the reaction mixture. Partial least square (PLS) regression was applied for the prediction of NaCl concentration, and the spectrum of NaCl solution was subtracted from the spectrum of sodium vanillate–NaCl solution as background measurement. This allowed us to obtain the vanillate spectra free from the absorption of NaCl solution. In addition, the mathematical method for reconstructing the spectrum of NaCl solution is discussed. The spectrum of NaCl solution is reconstructed as the linear combination of basic spectra calculated by singular value decomposition (SVD), and it was subtracted from that of the sodium vanillate–NaCl solution. By this procedure, the vanillate spectra were also obtained quantitatively, as has been demonstrated in PLS regression study. It was also confirmed that the quantitative spectra of high molecular weight fraction of alkaline oxygen-treated kraft lignin were obtained by the use of this reconstruction technique.Parts of this report were presented at the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, Japan, April 2002 and the 12th International Symposium on Wood and Pulping Chemistry, Madison, USA, June 2003     

Anti-inflammatory activities of cucurbitacin E isolated from Citrullus lanatus var. citroides: role of reactive nitrogen species and cyclooxygenase enzyme inhibition

The in vivo and in vitro mechanistic anti-inflammatory actions of cucurbitacin E (CE) (Citrullus lanatus var. citroides) were examined. The results showed that LPS/INF-γ increased NO production in RAW264.7 macrophages, whereas L-NAME and CE curtailed it. CE did not reveal any cytotoxicity on RAW264.7 and WRL-68 cells. CE inhibited both COX enzymes with more selectivity toward COX-2. Intraperitoneal injection of CE significantly suppressed carrageenan-induced rat's paw edema. ORAC and FRAP assays showed that CE is not a potent ROS scavenger. It could be concluded that CE is potentially useful in treating inflammation through the inhibition of COX and RNS but not ROS.