Enhanced Superoxide Radical Production in Roots of Zinc-Deficient Plants

The production of superoxide radical () was studied in roots of cotton (Gossypium hirsutum L. cv. Deltapine15/21), bean (Phaseolus vulgaris L. var. Pr?lude) and tomato(Lycopersicon esculentum L. cv. Super marmande) plants grownin nutrient solution with different Zn concentrations. UsingTiron as a spin-probe, electron spin resonance (ESR) was employedfor the measurements of levels. In the 48 000 g and 140 000 g supernatants of cotton root extracts theamplitude of the Tiron ESR signals reflecting production steeply increased with the appearance of visual Zndeficiency symptoms in the shoots. The changes in the amplitudeof the Tiron ESR signals were closely correlated with an NADPH-dependent generating oxidase activity with a high pH optimum. Increases in NADPH-dependent generation were also found in root extracts of Zn-deficientbean and tomato plants. In all experiments re-supply of Zn todeficient plants for 12 h or 24 h markedly decreased generation. Further, with advancing Zn deficiencyrates of NADPH oxidation increased and the activities of superoxidedismutase (SOD) and catalase decreased. The results suggest that cotton, bean and tomato roots possessan NADPH-dependent generating activity which is affected by the Zn nutritional status of the plants. UnderZn deficiency, enhanced generation and impaired detoxification of Of and H₂O₂ could lead to elevated levelsof and -derived oxidizing O₂ species and thus to increased peroxidation of membrane lipids. Key words: NADPH oxidase, superoxide radical, zinc deficiency     

Effect of Zinc Nutritional Status on Growth, Protein Metabolism and Levels of Indole-3-acetic Acid and other Phytohormones in Bean (Phaseolus vulgaris L.)

Bean (Phaseolus vulgaris L. var. Prelude) plants were grownfor 17 d under controlled environmental conditions with variedZn supply in the nutrient solution. The concentrations of aminoacids; indole-3-acetic acid, IAA; abscisic acid, ABA; isopentenyladenine, I-Ade; isopentenyl adenosine, I-Ado; zeatin, Z; andzeatin riboside, ZR were determined in various shoot fractions. The growth of plants, especially shoot growth, was severelydepressed under conditions of Zn deficiency. Simultaneously,concentrations of soluble protein and chlorophyll decreased,whereas amino acid concentrations increased several-fold. Inthe Zn-deficient plants, the level of IAA in the shoot tipsand young leaves decreased to about 50% of that in Zn-sufficientplants. A similar decrease occurred in the ABA levels of shoottips. In contrast, Zn deficiency was without effect on cytokininlevels in the leaves. Re-supply of Zn to the deficient plantsfor up to 96 h significantly increased shoot growth, solubleprotein, and IAA levels up to the values of Zn-sufficient plants.Simultaneously, the concentration of amino acids dropped tolow levels. The effect of Zn nutritional status on the tryptophanlevel was parallel to that of most of the other amino acids.The results confirm the role of Zn in protein synthesis anddemonstrate that the decrease in IAA level in Zn-deficient plantsis not brought about by impaired synthesis of tryptophan. Itis also unlikely that in Zn-deficient plants the conversionof tryptophan to IAA is specifically inhibited. Key words: Indole-3-acetic acid, tryptophan, zinc deficiency     

Magnesium deficiency enhances resistance to paraquat toxicity in bean leaves

Effects of deficient (20mmol m^?3) and sufficient (1000 mmol m^?3) magnesium (Mg) supply and of varied light intensity (100 μmol m^?2 s^?1 to 580 μmol m^?2 s^?1) on paraquat-dependent chlorophyll destruction in bean (Phaseolus vulgaris) plants grown in nutrient solution were studied over a 12-d period using leaf discs or intact primary leaves. Treatment of leaf discs with 10mmol m ³ paraquat for 15h caused severe chlorophyll loss, especially with increasing light intensity. This chlorophyll destruction by paraquat was very much higher in Mg-sufficient than Mg-deficient leaves. The occurrence of paraquat resistance in Mg deficient leaves was already apparent after 6d growth in nutrient solution, i.e. before any decrease in chlorophyll or growth by Mg deficiency was evident. Also, following foliar application of paraquat (10–140 mmol m^?3) to intact plants, Mg-deficient plants were much more resistant to paraquat, even following longer exposure duration (72 h) and four to 14 times higher paraquat concentrations than those received by Mg sufficient plants. From experiments where exogenous scavengers of superoxide radical (O₂^.-), hydroxyl radical (OH^·) and singlet oxygen (¹O₂) were applied to leaf discs, it appears that O₂^.-, and partly, OH^· are the main O₂ species which contribute to chlorophyll destruction by paraquat. The results demonstrate that Mg-deficient bean plants become highly resistant to O₂^.--mediated and light-induced paraquat injury. The mode of this paraquat resistance is attributed to well-known stimulative effects of Mg deficiency on O₂^.- and H₂O₂ scavenging enzymes and antioxidants.     

In Vivo and In Vitro Effects of Some Plant Hormones on Rat Erythrocyte Carbonic Anhydrase and Glucose-6-Phosphate Dehydrogenase Activities

The present study was undertaken to determine in vivo and in vitro effects of some plant growth regulators on rat erythrocyte carbonic anhydrase (CA) and glucose-6-phosphate dehydrogenase (G6PD) activities. Both in vivo and in vitro, spermidine and kinetin did not affect enzymatic activities of CA and G6PD, whereas putrescine decreased these activities, and abscisic acid increased them. Since plants use such growth regulators, their effects should be considered on mammals consuming them since they may possess important biological effects.     

The fatty acid compositions of predator Piocoris luridus （Heteroptera： Lygaeidae） and its host Monosteria unicostata （Heteroptera： Tingidae） reared on almond

The changes in fatty acid compositions during nutritional interaction among almond Amygdalus communis Linnaeus （Rosales： Rosaceae） （host plant）, lacebug Monosteria unicostata （Mulsant and Rey） （Heteroptera： Tingidae） and its predator Piocoris luridus Fieber （Heteroptera： Lygaeidae） were determined by gas chromatography and gas chromatography-mass spectrometry analyses. The fatty acid profiles of phospholipids and triacylglycerols were substantially different. Unlike the general observations for virtually most terrestrial insects, arachidonic and eicosapentaenoic acids were detected in high proportions of phospholipid fractions in both insects, especially in P. luridus. Also the almond tissues provide very little oleic acid to the herbivore diet, yet both insect species developed high proportions of this component. Our data reveals instances of specific accumulation of fatty acid biosynthesis, elongation/desaturation, and not incorporating selected fatty acids into cellular lipids.     

沙棘PEPCK基因的克隆及表达研究

以沙棘为研究对象,通过RACE、基因克隆和定量PCR技术,克隆并分析沙棘磷酸烯醇式丙酮酸羧激酶基因(PEPCK)的序列信息,以及进化树构建和氨基酸的二级结构分析,比较NaCl胁迫后PEPCK基因的表达变化,为揭示PEPCK基因在沙棘抗性方面的功能研究奠定基础。结果显示:(1)成功克隆了沙棘PEPCK基因,该基因开放阅读框(ORF)为2 001bp,编码666个氨基酸。(2)序列分析表明,沙棘PEPCK与蓖麻、黄顶菊、核桃等序列一致性高达85%以上;进化上沙棘PEPCK基因与蓖麻和狭叶羽扇豆较近,与烟草、拟南芥进化关系较远。(3)在300mmol·L~(-1) NaCl盐胁迫下,沙棘PEPCK基因表达在胁迫组中显著上升,胁迫后7d时为未处理的2.5倍,15d时达到未处理的3.2倍。研究表明,沙棘PEPCK基因在沙棘适应外源盐胁迫的过程中可能发挥了重要作用。     

The Effects of Dietary Selenium and Vitamin E and their Combination on the Fatty Acids of Erythrocytes,Bone Marrow and Spleen Tissue Lipids of Lambs

The object was to determine the influence of dietary vitamin E, selenium and their combination on the fatty acid con-tent of erythrocytes, bone marrow and spleen lipids of Akkaraman lambs. After supplementation for 15 days, the amount of all fatty acids was slightly higher (p < 0·05) in the vitamin E as compared to the control group, whereas the amount of longer fatty acids was significantly higher (p < 0·01, p < 0·001) in the selenium and combination groups. On the thirtieth day, the amount of all fatty acids was slightly high (p < 0·5) in all the supplemented groups in comparison with the control group. In the bone marrow lipids, the amount of longer fatty acids was decreased (p < 0·05, p < 0·01, p < 0·001) in the vitamin E and combination groups as compared to the control. Although the amount of some fatty acids was high (p < 0·05, p < 0·01) in the selenium group compared to the control, linoleic (18:2), linolenic (18:3) and the polyunsaturated fatty acids (PUFA) were lower (p < 0·05, p < 0·001). In the spleen lipids, the amount of longer fatty acids was slightly decreased (p < 0·05) in the vitamin E group as compared with the control; however the amount of longer fatty acids was significantly higher (p < 0·05, p < 0·01) in the selenium and combination groups in comparison to the control group. Thus dietary supplementation with selenium was more effective than dietary vitamin E supplementation in altering the fatty acid content of the erythrocyte, bone marrow and spleen lipids. © 1997 John Wiley & Sons, Ltd.     

A simple and efficient method for cultivation of limbal explant stem cells with clinically safe potential

Background

Several methods to cultivate limbal epithelial stem cells (LESCs) in vitro with the support of feeder layers and different growth medium formulations have been established for several years. The initial green medium consists of various ingredients that exhibit a non-optimal level of biosafety, therefore, different modifications have been made to suit it to safe clinical applications. However, the question of which formulation is the most appropriate remains to be answered.

Astragalus bahcesarayensis (Leguminosae-Papilionoideae), a new species of section Alopecuroidei DC. from Turkey

Astragalus bahcesarayensis H. Akan, M. Fırat & M. Ekici (Leguminosae-Papilionoideae) from Turkey is described and illustrated. It is compared with A. dipsaceus Bunge and A. panduratus Bunge. The geographical distributions of the new species and related species are mapped.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 439–444.