外源褪黑素对苏打盐碱胁迫大豆幼苗的缓解效应

褪黑素是缓解逆境胁迫对大豆损伤的有效途径之一。研究苏打盐碱胁迫下喷施褪黑素对大豆幼苗生长的调控效应，为大豆幼苗缓解苏打盐碱胁迫提供理论基础和技术支撑。以合农71为试验材料，采用砂培试验方法，设置常规+喷施清水处理(CK)、常规+喷施褪黑素处理(CKM)、苏打盐碱胁迫+喷施清水处理(S)、苏打盐碱胁迫+喷施褪黑素处理(SM)4个处理，研究大豆苗期不同生理指标对苏打盐碱胁迫的响应。结果表明，与常规处理(CK和CKM)相比，苏打盐碱胁迫下(S和SM)大豆幼苗生长均受到抑制；与S处理相比，SM处理大豆叶片PSII反应初始荧光(F₀)与最大荧光产量(F_m)显著增加，非光化学淬灭系数(NPQ)升高，作物光合机构过剩光能的耗散增强，PSII反应中心光保护能力提升，净光合速率(P_n)显著增加，叶片抗氧化酶活性(SOD、POD、APX)和清除ROS能力显著增强，根系和茎秆可溶性糖和可溶性蛋白含量显著增加，叶片和根系中MDA产生速率显著下降，根系干物质积累量、总表面积、总体积和根平均直径显著增加，维持了叶片细胞内激素水平，叶片IAA、CTK...     

褪黑素对盐胁迫下香椿幼苗生长及离子吸收和光合作用的影响

以香椿幼苗为材料,采用水培法研究不同浓度褪黑素(0、50、100、200和400μmol/L)对盐(150 mmol/L NaCl)胁迫下香椿幼苗生长指标、矿质元素离子(Na~+、K~+、Ca~(2+)和Mg~(2+))含量、净光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)和胞间CO_2浓度(C_i)等光合作用指标的影响,以探究外源物质褪黑素对盐胁迫下香椿幼苗生长和生理的调控作用。结果表明:(1)在盐胁迫条件下,香椿幼苗的生长受到显著抑制,叶绿素含量和P_n显著降低,叶片和根系中Na~+含量比对照(CK)显著增加,而K~+、Mg~(2+)和Ca~(2+)含量以及离子含量的比值(K~+/Na~+、Mg~(2+)/Na~+和Ca~(2+)/Na~+)则明显下降,且丙二醛含量显著增加。(2)施加适宜浓度褪黑素能显著促进盐胁迫下香椿植株生长,降低其叶片和根系中Na~+含量,提高其K~+、Ca~(2+)、Mg~(2+)含量和离子含量比值以及叶片P_n、T_r、水分利用效率(WUE)和G_s和C_i,但却降低了气孔限制值(L_s)。(3)适宜浓度褪黑素使盐胁迫下香椿植株叶片的丙二醛积累明显下降,叶绿素含量显著上升。研究发现,外施适宜浓度的褪黑素能降低盐胁迫下香椿幼苗叶片和根系内Na~+浓度,增加K~+、Mg~(2+)和Ca~(2+)浓度,调控植物体内细胞的离子平衡状态,增强对营养元素的吸收,提高光合作用效率,从而提高香椿幼苗对盐胁迫的抗性,并以100μmol/L褪黑素处理的效果最佳。     

外源褪黑素对干旱胁迫下沙芦草幼苗生长和生理特性的影响

为明确外源褪黑素对沙芦草干旱胁迫的缓解效应,以‘盐池’沙芦草为试材,采用聚乙二醇6000(PEG-6000)模拟干旱胁迫,研究沙芦草幼苗对干旱胁迫的响应以及外源添加不同浓度(0、1、10、50、100、150和200 mg·L^-1)褪黑素对干旱胁迫下沙芦草幼苗生长和生理特性的影响。结果表明：干旱胁迫显著抑制沙芦草幼苗的生长,而外源添加不同浓度的褪黑素均能够缓解干旱胁迫引起的沙芦草幼苗生长抑制,并且当褪黑素浓度为100 mg·L^-1时缓解效果最显著。与单独干旱胁迫处理相比,在干旱胁迫下外源添加100 mg·L^-1褪黑素后沙芦草幼苗株高、地上干重和叶片相对含水量分别增加58.2%、121.2%和48.1%,叶绿素a、叶绿素b和类胡萝卜素含量分别增加48.7%、80.8%和38.3%,超氧化物歧化酶、过氧化物酶和根系活力分别增加12.6%、33.9%和39.1%,抗坏血酸和谷胱甘肽含量分别增加19.5%和18.3%,脯氨酸、可溶性糖和可溶性蛋白含量分别提高16.2%、32.6%和14.3%,而丙二醛、过氧化氢和超氧阴离子含量分...     

外源褪黑素对盐胁迫下紫花苜蓿幼苗抗氧化能力以及光合作用效率的影响

紫花苜蓿为多年生豆科优良牧草,土壤盐碱化是其产量的重要限制因素。该研究以‘中苜1号’紫花苜蓿为材料,在盐胁迫浓度和褪黑素浓度筛选试验基础上,设置盐(150 mmol/L NaCl)和褪黑素(30、50、80μmol/L)单独及复合处理,采用水培根灌褪黑素的方法,探究外源褪黑素对盐胁迫下紫花苜蓿幼苗生长特性、膜透性、渗透调节、抗氧化物酶以及光合作用指标的影响。结果表明:(1)紫花苜蓿幼苗生长受到盐胁迫的显著抑制,而在单独褪黑素处理下无显著变化;各浓度褪黑素处理均可有效缓解盐胁迫对紫花苜蓿生长造成的伤害,并以150 mmol/L NaCl+80μmol/L褪黑素处理(NaCl+MT2)效果最佳,其幼苗根长、根鲜重和根干重分别比盐胁迫处理显著增加了34.52%、41.93%和19.61%。(2)盐胁迫显著增加了紫花苜蓿幼苗细胞膜系统的透性和膜脂过氧化程度,NaCl+MT2处理幼苗叶片的相对电导率和MDA含量分别比盐胁迫处理显著降低了27.18%和30.24%,同时使幼苗叶片的相对含水量显著提高,脯氨酸含量却显著降低,表明外源褪黑素有效缓解了盐胁迫下细胞失水危害和细胞膜损伤的程度。(3)NaCl+MT2处理幼苗叶片的POD和SOD活性分别比盐胁迫处理显著提高31.45%和41.41%,其CAT活性却无显著变化,表明外源褪黑素可显著增强紫花苜蓿幼苗叶片POD、SOD活性,提高其活性氧的清除能力,减轻盐胁迫诱导的过氧化伤害。(4)盐胁迫显著抑制了紫花苜蓿幼苗光合作用效率,而NaCl+MT2处理幼苗叶片的净光合速率、气孔导度和蒸腾速率较盐胁迫处理分别显著增加了30.27%、45.1%、42.15%。研究发现,盐胁迫致使紫花苜蓿幼苗叶片的活性氧积累显著增加,抗氧化物酶活性显著降低,显著降低了其光合作用效率,外源褪黑素通过提高紫花苜蓿的抗氧化能力和光合作用效率来促进幼苗生长,从而增强了紫花苜蓿的耐盐性。     

干旱胁迫下叶面喷施褪黑素对滁菊幼苗生理生化特性的影响

以滁菊品种"金玉"幼苗为材料,通过日光温室内盆栽实验,在中度干旱胁迫条件下(土壤田间持水量的40%),研究叶面喷施外源褪黑素(MT,100μmol·L-1)对滁菊幼苗生长及生理生化特性的影响,探讨提高滁菊耐干旱性的新途径。结果表明:(1)与对照相比,干旱胁迫处理降低了滁菊叶片叶绿素含量、净光合速率和水分利用效率,提高了可溶性蛋白质、可溶性糖和脯氨酸含量,而叶片MDA含量和相对电导率显著增加,显著抑制了滁菊幼苗的生长。(2)在干旱胁迫条件下,外源MT可显著提高滁菊幼苗叶片脯氨酸、可溶性蛋白质和可溶性糖的含量,并显著降低了叶片相对电导率和MDA含量,使幼苗保持较高叶绿素含量和净光合速率。(3)与干旱胁迫处理相比,外源MT处理的滁菊地上部和根系干重、鲜重均显著增加。研究发现,外源褪黑素(MT)在一定程度上可通过促进滁菊幼苗渗透调节物质的积累,有效降低干旱胁迫对其细胞膜的伤害,维持其正常的细胞膜功能,保持其较高的光合速率和水分利用效率,从而增加其对干旱环境的适应性。     

外源褪黑素对盐胁迫下银杏幼苗渗透调节和抗氧化能力的影响

以4年生银杏幼苗为材料,进行不同浓度盐胁迫(50、100、200 mmol·L^-1)处理,叶片喷施和土壤浇灌外源褪黑素溶液(0、0.02、0.1、0.5 mmol·L^-1),研究外源褪黑素对盐胁迫下银杏幼苗渗透调节和抗氧化能力的影响。结果表明：盐胁迫显著抑制银杏幼苗渗透调节和抗氧化能力,而在盐胁迫下施用适宜浓度(0.02、0.1 mmol·L^-1)的外源褪黑素能够促进植株生长,降低电解质外渗率,减少黄酮和丙二醛含量,促进叶片中过氧化物酶、超氧化物歧化酶(SOD)活性的提高,但高浓度(0.5 mmol·L^-1)外源褪黑素会进一步加剧氧化胁迫和渗透胁迫。0.02和0.1 mmol·L^-1外源褪黑素处理缓解了盐胁迫下银杏幼苗的渗透胁迫和氧化胁迫,且0.02 mmol·L^-1外源褪黑素处理对盐胁迫缓解效果最佳。地径、枝条宽度、枝条长度、电解质外渗率、SOD活性和黄酮含量可作为快速鉴定银杏受盐胁迫程度的关键指标。     

褪黑素预处理对高温下猕猴桃幼苗抗氧化能力的影响

为了探明外源褪黑素对高温胁迫下猕猴桃幼苗耐热性的影响,以盆栽‘秦美’猕猴桃幼苗为材料,进行根灌褪黑素溶液和45℃高温胁迫处理,并测定相关抗逆生理指标。结果表明：(1)与高温对照相比,褪黑素预处理显著降低了猕猴桃幼苗叶片相对电导率和丙二醛含量,提高了脯氨酸含量以及过氧化氢酶和过氧化物酶活性,且褪黑素溶液浓度在100~200 μmol·L^-1时效果较好。(2)褪黑素预处理显著增加了叶片中总酚、总黄酮和总黄烷醇含量,且幼苗的抗氧化能力(ABTS法、FRAP法和DPPH法)在胁迫过程中显著高于高温对照。研究认为,外源褪黑素可以通过提高植株体内抗氧化酶活性,非酶抗氧化物质如酚类物质和类黄酮物质含量以及渗透调节物质含量来增强植物的抗氧化能力,从而有效缓解高温对于猕猴桃幼苗的伤害,增强猕猴桃幼苗的耐热性。     

外源褪黑素对低温胁迫下茄子幼苗生长及其光合作用和抗氧化系统的影响

以‘沪茄08-1’茄子幼苗为试验材料,采用基质栽培方式,研究了叶面喷施50~200μmol·L-1外源褪黑素(melatonin,MT)对低温胁迫[(10±1)℃(昼)/(5±1)℃(夜)]下茄子幼苗生长、光合作用和抗氧化系统等生理指标的影响,以明确外源MT在茄子幼苗抵御低温逆境方面的生理机制。结果显示:(1)低温胁迫处理后,茄子幼苗株高、茎粗、地上部鲜重和根系鲜重、叶绿素含量、叶片净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)均显著降低,丙二醛(MDA)含量、超氧阴离子产生速率(O-·2)和过氧化氢(H2O2)含量均显著增加。(2)幼苗叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)、脱氢抗坏血酸还原酶(DHAR)活性及抗坏血酸(AsA)和谷胱甘肽(GSH)含量均显著升高,而其脯氨酸(Pro)和可溶性蛋白质含量均显著增加;外源MT处理可有效增强低温胁迫条件下茄子幼苗叶片中SOD、POD、CAT、APX、GR、DHAR活性,提高AsA和GSH含量,增加Pro和可溶性蛋白含量,显著抑制其叶片MDA、O-·2及H2O2的积累。研究表明,外源MT主要通过增强低温胁迫下茄子幼苗的光合作用以及清除活性氧的能力,减缓低温胁迫的危害,提高茄子幼苗对低温胁迫的耐性。     

褪黑素对高温胁迫下黄瓜幼苗抗坏血酸代谢系统的影响

以‘津春4号’黄瓜幼苗为试材,采用叶面喷施的方法,研究了外源褪黑素对高温胁迫下黄瓜幼苗叶片抗坏血酸代谢系统的影响.结果表明:高温胁迫后,黄瓜幼苗叶片过氧化氢(H2O2)和丙二醛(MDA)含量明显增加;还原型抗坏血酸(AsA)和还原型谷胱甘肽(GSH)含量持续下降,脱氢抗坏血酸(DHA)和氧化型谷胱甘肽(GSSG)含量逐渐升高,AsA/DHA和GSH/GSSG大幅下降;抗坏血酸过氧化物酶(APx)、单脱氢抗坏血酸还原酶(MDHAR)、脱氢抗坏血酸还原酶(DHAR)和谷胱甘肽还原酶(GR)活性明显升高,并在12 h达到最大.外施褪黑素能有效抑制高温胁迫下黄瓜幼苗叶片H2O2和MDA的积累,提高抗氧化物质AsA和GSH含量及抗坏血酸代谢相关酶APx、MDHAR、DHAR和GR活性,从而增强对H2O2的清除能力,抑制活性氧的产生,维持细胞膜的稳定性,减轻高温对植株造成的伤害,提高黄瓜幼苗抵御高温胁迫的能力.     

褪黑素种子引发处理提高朝天椒耐盐性的作用机制

褪黑素具有增强植株耐盐性的作用,但其通过种子引发处理提高朝天椒植株耐盐性的效果和作用机制还鲜见报道。为探讨种子引发剂褪黑素（melatonin, MT）对盐胁迫下辣椒幼苗生长及生理特性的影响机制,以‘茂蔬360’为材料,研究褪黑素引发种子对盐胁迫下辣椒幼苗生长、光合特性、抗氧化代谢及渗透调节等的影响。结果表明,褪黑素种子引发处理显著缓解了盐胁迫对朝天椒植株生长的不利影响,与未引发处理相比,经不同浓度褪黑素引发种子后,显著提高了盐胁迫下辣椒幼苗生长,具体表现为植株根长、地上高度、茎鲜重、叶片鲜重、根鲜重、Fv’/Fm’、Qp、NPQ、Fo、Fv/Fm值和叶绿素含量提高。生理分析表明,经不同浓度褪黑素引发处理后,显著降低了盐胁迫下朝天椒植株叶片的丙二醛、过氧化氢和超氧阴离子含量;叶片可溶性糖、可溶性蛋白、脯氨酸、AsA和DHA含量显著提高;叶片POD、SOD、APX和GR活性显著增强。此外,经褪黑素引发处理后,显著提高了盐胁迫下叶、茎、根中K+含量,降低了Na+含量和Na+/K+值。以上结果表明,100μmol/L褪黑素种子引发处理效果最好,明显提高了朝天椒对土壤盐分的耐性,减少了植株对N...     

Arbutin derivatives from the buds of Vaccinium dunalianum and their MS/MS spectrometric fragmentations

Four arbutin derivatives were isolated from the buds of Vaccinium dunalianum in which 4-hydroxyphenyl-6′-(3''-O-β-D-glucopyranosyl-4''-hydroxycinnamoyl)-O-β-D-glucopyranoside (1) was a new compound. The structure of the new compound was determined on the basis of NMR and HR-ESI-MS data. All the arbutin derivatives were subjected to the MS/MS analyses from which the MS/MS spectrometric fragmentations were summarized.     

Method for therapeutic drug monitoring of azole antifungal drugs in human serum using LC/MS/MS

Fungal infections occur in immunocompromised patients. Azole antifungal agents are used for the prophylaxis and treatment of these infections. The interest in therapeutic drug monitoring azole agents has increased over the last few years. Inter- and intra-patient variability of pharmacokinetics, drug–drug interactions, serum concentration related toxicity and success of therapy has stressed the need of frequently therapeutic drug monitoring of the drugs, belonging to the group of azoles. Therefore a simple, rapid and flexible method of analysis is required. This method is based on the precipitation of proteins in human serum with LC/MS/MS detection. Validation was performed according to the guidelines for bioanalytical method validation of the food and drug administration agency. The four most used azole drugs can be detected in human serum within the clinical relevant serum levels with good accuracy and reproducibility at the limit of quantification. Intra- and inter-day validation demonstrated good accuracy and reproducibility. A rapid, sensitive and flexible LC/MS/MS method has been developed and validated to measure voriconazole (VRZ), fluconazole (FLZ), itraconazole (ITZ) and posaconazole (PSZ) in human serum. This new method is suitable for clinical pharmacokinetic studies and routine monitoring in daily practice.     

MS/MS profiling of taxoids from the needles of Taxus wallichiana

Ammonium cationisation has been used for taxoid profiling of partially purified methanolic extracts of needles of Taxus wallichiana growing in different regions of the Himalayas (Kashmir, Himachal Pradesh, UP Hills, Darjeeling, Sikkim and Arunachal Pradesh) by electrospray ionisation tandem mass spectrometry (MS/MS). The MS/MS spectra of the [M + NH4]+ or [M + H]+ ions gave structurally diagnostic fragment ions which revealed information about the taxane skeleton as well as the number and nature of the substituents. The rearranged 11(15-->1)-abeo-taxanes showed a characteristic elimination of the hydroxyisopropyl group with an acetoxy/benzoyloxy group from C-9. The identification of the taxoids was achieved by comparison of the MS/MS spectra with those of authentic taxoids or was based on biogenetic grounds. The results were corroborated by liquid chromatography-MS analysis. Out of the 50 taxoids identified, 21 belonged to the rearranged class. The presence of paclitaxel in the samples from four regions was confirmed: the study also revealed the occurrence of several basic taxoids in these samples. MS/MS profiling by electrospray ionisation was shown to be a fast and reliable technique for the analysis of taxoid samples.     

Intact glucosinolate analysis in plant extracts by programmed cone voltage electrospray LC/MS: performance and comparison with LC/MS/MS methods

We present a comprehensive, sensitive, and highly specific negative ion electrospray LC/MS method for identifying all structural classes of glucosinolates in crude plant extracts. The technique is based on the observation of simultaneous maxima in the abundances of the m/z 96 and 97 ions, generated by programmed cone voltage fragmentation, in the mass chromatogram. The abundance ratios lie in the range 1:2-1:4 ([m/z 96]/[m/z 97]). Examination of the corresponding full-scan mass spectra allows individual glucosinolates of all structural classes to be identified rapidly and with confidence. The use of linearly programmed cone voltage fragmentation enhances characteristic fragment ions without compromising the abundance of the analytically important [M - H]- ion and its associated (and analytically useful) sulfur isotope peaks. Detection limits are in the low nanogram range for full-scan, programmed cone voltage spectra. Comparison of the technique with LC/MS/MS methods (product ion, precursor ion, and constant neutral loss scans) has shown that the sensitivity and selectivity of the programmed cone voltage method is superior. Data obtained on a variety of plant extracts confirmed that the methodology was robust and reliable.     

Detection and identification of plasma proteins that bind GlialCAM using ProteinChip arrays, SELDI-TOF MS, and nano-LC MS/MS

In order to fully understand biological processes it is essential to identify interactions in protein complexes. There are several techniques available to study this type of interactions, such as yeast two-hybrid screens, affinity chromatography, and coimmunoprecipitation. We propose a novel strategy to identify protein-protein interactions, comprised of first detecting the interactions using ProteinChips and SELDI-TOF MS, followed by the isolation of the interacting proteins through affinity beads and RP-HPLC and finally identifying the proteins using nano-LC MS/MS. The advantages of this new strategy are that the primary high-throughput screening of samples can be performed with small amounts of sample, no specific antibody is needed and the proteins represented on the SELDI-TOF MS spectra can be identified with high confidence. Furthermore, the method is faster and less labor-intensive than other current approaches. Using this novel method, we isolated and identified the interactions of two mouse plasma proteins, mannose binding lectin C and properdin, with GlialCAM, a type 1 transmembrane glycoprotein that belongs to the Ig superfamily.     

Development of an LC/MS/MS Method for Simultaneous Detection of 11 Polyphenols in Rat Plasma and Its Pharmacokinetic Application after Oral Administration of Coreopsis tinctoria Extract

Eleven polyphenols, classified as flavonoid glycosides, flavonoid aglycones, and phenolic acids, are important bioactive components in the capitula of Coreopsis tinctoria (CCT). Nevertheless, their full pharmacokinetic profiles have not been demonstrated simultaneously. Therefore, a liquid chromatography – tandem mass spectrometry (LC/MS/MS) method was developed in the present work and used it to study the pharmacokinetics of these 11 compounds. We performed LC/MS/MS with a gradient mobile phase composed of water containing 0.1 % formic acid and acetonitrile containing 0.1 % formic acid on a Proshell 120 SB C18 column (2.1 mm×100 mm, 2.7 μm). We achieved a good chromatographic peak shape, resolution, and mass signal response, and multiple reaction monitoring facilitated the simultaneous detection of 11 analytes. In addition, we validated the selectivity, correlation coefficient, precision, extraction recovery, matrix effects, and stability of the LC/MS/MS method to be acceptable for 11 analytes in rat plasma. Subsequently, rats were orally administered with 50 % ethanol eluent of CCT (ECCT). Nine of 11 polyphenols were absorbed quickly (except for QCD and TCA), and their plasma levels peaked within 40 min. The exposure and C_max values of flavonoid glycosides and phenolic acids were lower than those of flavonoid aglycones. This is the first report to demonstrate the pharmacokinetics of 11 polyphenols in ECCT, which may play an important role in future studies of the bioactive components of ECCT and their bioactive mechanisms.