转铁蛋白在低钾刺激Madin Darby狗肾细胞钠-钾ATP酶中的作用

体外低钾培养肾细胞能刺激细胞膜钠-钾ATP酶。本研究利用Madin Darby狗肾细胞能在无血清培养液中健康生存48h这一特征,研究体外低钾刺激细胞膜钠-钾ATP酶所依赖的血清中的活性因子,观察了表皮生长因子(EGF)、胰岛素样生长因子(IGF1)、前列腺素1(PGE1)和转铁蛋白(tranderrin)在这一过程中的作用。结果表明,在无血清培养液中低钾并不能刺激细胞膜钠—钾ATP酶,而添加转铁蛋白可模拟血清的作用。转铁蛋白能剂量依赖性地增加ouabain结合位点,对细胞膜钠-钾ATP酶作用呈良好的时间效应关系。在低钾无血清培养液中,细胞膜钠-钾ATP酶α1亚基启动子活性增强,α1与β1亚基蛋白质表达的增加依赖于转铁蛋白的存在。进一步研究结果表明,低钾在转铁蛋白的无血清培养液环境中能增加细胞对铁的摄取(^59Fe),该作用可被铁螯合剂(deferoxamine,DFO;35 μmol/L)所阻断。DFO也可阻断转铁蛋白依赖性低钾刺激细胞膜钠-钾ATP酶数目的增多,α1亚基启动子活性增强,α1与β1亚基蛋白质表达增加。以上结果表明,低钾对细胞膜钠-钾ATP酶活性的刺激作用依赖于转铁蛋白所调节的铁的摄取。     

Intraocular iron injection induces oxidative stress followed by elements of geographic atrophy and sympathetic ophthalmia

Iron has been implicated in the pathogenesis of age‐related retinal diseases, including age‐related macular degeneration (AMD). Previous work showed that intravitreal (IVT) injection of iron induces acute photoreceptor death, lipid peroxidation, and autofluorescence (AF). Herein, we extend this work, finding surprising chronic features of the model: geographic atrophy and sympathetic ophthalmia. We provide new mechanistic insights derived from focal AF in the photoreceptors, quantification of bisretinoids, and localization of carboxyethyl pyrrole, an oxidized adduct of docosahexaenoic acid associated with AMD. In mice given IVT ferric ammonium citrate (FAC), RPE died in patches that slowly expanded at their borders, like human geographic atrophy. There was green AF in the photoreceptor ellipsoid, a mitochondria‐rich region, 4 h after injection, followed later by gold AF in rod outer segments, RPE and subretinal myeloid cells. The green AF signature is consistent with flavin adenine dinucleotide, while measured increases in the bisretinoid all‐trans‐retinal dimer are consistent with the gold AF. FAC induced formation carboxyethyl pyrrole accumulation first in photoreceptors, then in RPE and myeloid cells. Quantitative PCR on neural retina and RPE indicated antioxidant upregulation and inflammation. Unexpectedly, reminiscent of sympathetic ophthalmia, autofluorescent myeloid cells containing abundant iron infiltrated the saline‐injected fellow eyes only if the contralateral eye had received IVT FAC. These findings provide mechanistic insights into the potential toxicity caused by AMD‐associated retinal iron accumulation. The mouse model will be useful for testing antioxidants, iron chelators, ferroptosis inhibitors, anti‐inflammatory medications, and choroidal neovascularization inhibitors.     

Effects of various iron supply on oxidative stress development and ferritin formation in the common ice plants

Mesembryanthemum crystallinum L. plants were grown from seeds in perlite. At the age of 4 weeks (juvenile plants) or 6 weeks (adult plants), they were transferred on nutrient media with different Fe³⁺ content brought in as Fe₂(SO₄)₃—EDTA complex (pH 6.0): control, iron deficit, and iron “excess”. Adult plants grown in media differing in iron content were subjected to salinity (300 mM NaCl) during the last 8 days of growth. Biochemical analyses were performed after plant fixation in liquid nitrogen; simultaneously, the samples for electron microscopy were taken. Different content of available Fe³⁺ in medium, especially under salinity conditions, changed sharply the content of chlorophyll and proline, the rate of lipid peroxidation, the level of H₂O₂, the activities of antioxidant enzymes in the leaves and roots, the number and sizes of plastoglobules, and ferritin formation in plastids. Joint action of salinity and iron deficit enhanced oxidative stress development, whereas iron excess hampered oxidative reaction development, reduced the rate of lipid peroxidation, and increased the chlorophyll content. At iron excess, plastoglobule lysis in plastids did not occur, their number and sizes increased, and ferritin deposits appeared, whereas the latter were absent at iron deficit.     

The effect of nitrate concentration in a flowing solution system on growth and nitrate uptake of twoPlantago species

Summary Juvenile plants ofPlantago lanceolata andP. major ssp.major were grown in a flowing solution system at 7.5 mM or 9.5 M NO₃. The parameters investigated were: RGR, shoot weight percentage, leaf length, length of main root axis, shoot concentrations of major ions and organic N, and the specific uptake rate for NO₃. At 9.5 M NO₃ growth ofP. major was not hampered, whereas shoot growth and leaf length ofP. lanceolata were reduced. The NO₃ concentration ofP. lanceolata decreased more than that ofP. major. The different performances of the species at 9.5 M NO₃ were associated with different specific uptake rates. In both treatments the root system ofP. major was shorter than that ofP. lanceolata. P. lanceolata accumulated more NO₃ in the leaves. The performance of thePlantago species is discussed in relation to the availability of nutrients in their habitats.Grassland Species Research Group. Publication no. 37.     

Cu污染土壤中溪荪和花菖蒲的生长状况及对Cu的积累及转运能力

采用土壤栽培方法,研究了在Cu添加量为0(CK)、200、400、600、800和1 000μg·g-1的土壤中溪荪(Iris sanguinea Donn es Horn.)和花菖蒲(I.ensata Thunb.var.hortensis Makino et Nemoto)叶和根的数量、长度及生物量(干质量)6个生长指标的变化趋势,并对叶和根中的Cu含量和积累量、全株的Cu积累量、Cu的富集系数及转运系数进行了比较分析.结果表明:随土壤中Cu添加量的提高,溪荪的根数逐渐降低且显著低于对照;而溪荪的其余5个生长指标和花菖蒲的6个生长指标均总体呈现出在Cu添加量较低的条件下逐渐增加并显著高于对照、在Cu添加量较高的条件下逐渐减小且显著小于对照的变化趋势;其中在Cu添加量1 000μg·g-1的土壤中2种植物的生长均受到显著抑制(P＜0.05);而添加400和600μg·g-1Cu则分别对2种植物的生长有一定的促进作用.随土壤中Cu添加量的增加,溪荪和花菖蒲叶及根中的Cu含量均逐渐提高;溪荪对Cu的富集系数和转运系数以及花菖蒲对Cu的富集系数均显著小于对照,而花菖蒲对Cu的转运系数则呈现在Cu添加量较低的条件下高于对照、Cu添加量较高的条件下低于对照并逐渐减小的趋势;在添加了Cu的土壤中,溪荪叶、根和全株对Cu的积累量均低于花菖蒲,但均显著高于对照,且2种植物根的Cu含量及积累量均大于叶片,表明溪荪和花菖蒲均具有一定的Cu积累能力,且主要积累在根中,花菖蒲对Cu的积累能力优于溪荪.综合分析结果显示:溪荪和花菖蒲不是Cu超积累植物,但对Cu胁迫均具有一定的耐性,且花菖蒲的耐性略强于溪荪;溪荪和花菖蒲分别适宜栽植于Cu含量400和600μg·g-1以下的土壤中,可用于轻度和中度Cu污染土壤的植物修复和环境美化.     

Cotton Leaf Curl Virus: lonic Status of Leaves and Symptom Development

In the present study, the relationship between the nutritional status of leaves and the development of symptoms of cotton leaf curl virus (CLCuV) in two cotton (Gossypium hirsutum L.) cultivars (i.e. CIM-240 and S-12) was investigated. The incidence of disease attack was found to be 100% in the S-12 cultivar and 16% in the CIM-240 cultivar. Geminivirus particles in infected leaves were confirmed by transmission electron microscope examination of highly specific geminivirus coat protein antisera-treated cell sap. The CLCuV impaired the accumulation of different nutrients in both cultivars. A marked decrease in the accumulation of Ca2+ and K+ was observed in infected leaves. However, the disease had no effect on leaf concentrations of Na+, N, and P. It was observed that the curling of leaf margins in CLCuV-infected plants was associated with the leaf Ca2+ content; leaf curling was severe in plants with a significant reduction in Ca2+ content.Moreover, leaf K+ content was found to be associated with resistance/susceptibility to CLCuV infection.     

烯效唑干拌种对小麦氮素积累和运转及籽粒蛋白质品质的影响

通过田间试验,研究了不同烯效唑干拌种剂量对3个不同筋力小麦品种植株氮素积累、运转和籽粒蛋白质品质的影响,结果表明,基因型、环境及烯效唑处理对小麦品质的影响效应依次减小,且均达到了极显著水平,但三者的互作效应较小。烯效唑处理后提高了不同生态点下不同小麦品种籽粒蛋白质含量和产量,处理后的面筋含量和沉淀值增加,面团形成时间和稳定时间延长;干拌种增加了开花期各营养器官中的氮素含量和单株氮素积累量,花后氮素总转移量、总转移率及其对籽粒氮的贡献率极显著提高,且处理后旗叶中可溶性蛋白质含量在花后15 d内均显著高于对照;对籽粒中氮含量而言,烯效唑处理后提高了灌浆初期籽粒中的非蛋白氮含量,花后5—20 d内均高于对照,灌浆期间籽粒蛋白氮含量均高于对照,因而处理后的粗蛋白质含量变化动态特点为谷底高、回升快。研究认为,烯效唑处理如同基因、环境一样独立影响小麦籽粒品质,而烯效唑处理后提高了开花初期旗叶中的可溶性蛋白质含量和花前营养器官中氮素含量及花后氮素转运量,可能是其提高籽粒非蛋白氮含量、促进籽粒蛋白质含量增加和蛋白质质量提高的重要原因之一,烯效唑干拌种对小麦籽粒蛋白质品质的改善具有广适性。