不同含水量大葱种子贮藏后的脂肪代谢研究

将大葱种子干燥成1．8％-10．5％的不同含水量后。在50℃、35℃、20℃和-18℃条件下密闭贮存16个月。通过对棕榈酸、硬脂酸、油酸、亚油酸、亚麻酸含量的研究,结果表明,随着贮存温度的升高,种子中棕榈酸、硬脂酸、油酸、亚油酸、亚麻酸含量不断升高,但在20℃和-18℃的差异不明显。在50℃下含水量为1．8％～6．6％的种子。5种脂肪酸含量明显大于含水量为7．4％-10.5％的种子。     

玉米种子中4种可溶性糖含量UPLC-ELSD测定方法的优化及其应用

对比了HPLC-RID法和UPLC-ELSD法对果糖、葡萄糖、蔗糖和麦芽糖4种可溶性糖的检测。结果表明:UPLC-ELSD法的分离效果、重复性、灵敏度等比HPLC-RID法好,确定了UPLC-ELSD法测定4种糖含量的技术参数,即流动相为0.2%(w/v)三乙胺溶于75%(v/v)乙腈,流速为0.2 m L/min,柱温为35℃,上样量为2μL,在6 min内可以灵敏、快速地检测出果糖等4种可溶性糖。利用UPLC-ELSD法测定玉米种子吸胀过程中蔗糖、麦芽糖、葡萄糖和果糖4种可溶性糖的含量,结果表明:胚乳在吸胀之前,仅检出蔗糖、葡萄糖和果糖,其中蔗糖含量最高,随着种子吸胀,蔗糖含量先下降后上升,而葡萄糖和果糖逐渐增加,吸胀48 h时检出麦芽糖。胚在吸胀之前,4种可溶性糖均可以检测到,且含量均显著高于胚乳,在吸胀过程中4种糖的变化规律与胚乳相似。因此,在玉米种子吸胀过程中,可能先动员蔗糖分解成葡萄糖和果糖,再动员贮藏物质合成蔗糖、麦芽糖、葡萄糖和果糖,为种子萌发生长提供能量和中间物质。     

温州蜜柑果实发育期间果糖激酶与糖积累的关系

研究了温州蜜柑果实发育进程中糖含量变化与果糖激酶活性变化的关系及增施氮肥对果实果糖激酶活性和基因表达的影响.结果表明,随着果实的发育,可食组织果糖激酶活性逐渐降低,糖含量不断增加,果皮中蔗糖和葡萄糖含量在成熟期略有下降,果糖激酶活性略有升高.果实膨大期后增施氮肥的果实在成熟期可食组织及果皮中蔗糖和果糖所占比例均有所下降,葡萄糖比例升高,以单位蛋白质表示的果糖激酶活性也明显高于对照果实.Northern分析表明,增施氮肥能促进发育后期果实可食组织中Cufrkl基因的表达,但对Cufrk2的表达无明显作用.     

八棱海棠种子超低温保存中含水量对糖代谢的影响

含水量是影响种子超低温保存效果的关键因素，而其作用机制尚不完全清楚。为探讨含水量对种子超低温保存生活力的影响途径，该研究以八棱海棠种子为材料，通过硅胶干燥法获得不同含水量的种子，测定超低温保存后种子生活力、糖含量及相关酶指标的变化并分析相关性。结果表明：(1)超低温保存15 d后，不同含水量种子生活力不同，随着种子含水量的降低，种子生活力呈现先升高后降低的趋势，含水量为9.02%的八棱海棠种子生活力最高，为53.33%;超低温保存120 d后，种子生活力随着含水量下降一直升高，含水量为6.40%生活力最高，为27.78%。这表明八棱海棠种子含水量对超低温保存后的生活力有明显影响，但受液氮保存时间影响，随着液氮保存时间的延长，最适含水量降低。(2)相关分析显示，超低温保存后种子含水量与生活力呈极显著负相关(r=-0.82);与果糖和蔗糖含量、酸性转化酶、果糖激酶呈显著负相关，而种子萌发率与这些指标呈显著正相关。这表明种子含水量通过影响酸性转化酶活性而影响蔗糖和果糖含量，进而影响蔗糖代谢，响应低温和脱水胁迫，最终导致生活力差异。种子生活力还受到介导果糖激酶的果糖代谢影响。此外，海藻糖也是种...     

低夜温下黄瓜生理生化指标的变化及对雌花形成的影响

选用温敏型黄瓜‘C09-123’为试材,设置3个不同的夜温处理,调查其20节内雌花分化情况,同时测定二叶一心茎尖内各激素(乙烯、赤霉素、生长素、脱落酸和玉米素)、糖(蔗糖、葡萄糖)、18种氨基酸含量以及相关基因的表达量。结果表明:不同夜温处理下,内源乙烯、葡萄糖和蔗糖的含量随处理温度的升高而降低,生长素、赤霉素、脱落酸和玉米素未表现出相同的变化趋势;黄瓜雌花分化率与内源激素和糖的相关性分析表明,雌花分化率与葡萄糖含量极显著正相关(P<0.01)、与内源乙烯含量呈显著正相关(P<0.05),同时乙烯和葡萄糖含量均与蔗糖含量显著正相关;乙烯合成所需的甲硫氨酸和天冬氨酸的含量也在低夜温下显著升高;糖代谢中的关键酶己糖激酶和谷草转氨酶在生理和分子水平均表现出随处理夜温的升高而降低,特别谷草转氨酶基因表达量在低夜温12°C时较18和24°C时提高了4倍,并与乙烯合成关键基因(Cs ACS2和Cs ACO2)的表达量随温度升高的变化趋势一致。     

蓖麻种子油脂累积与可溶性糖变化的关系

通过高效液相色谱、RNA-seq测序和放射性碳同位素示踪等技术研究了蓖麻种子发育过程中可溶性糖代谢与油脂累积过程的关系。结果表明,蓖麻种子可溶性糖主要由葡萄糖、果糖和蔗糖构成。随着种子发育和油脂累积,可溶性糖含量呈现明显的下降趋势。其中蔗糖含量变化与油脂累积存在极显著的负相关性(r=0.980)。在种子发育早期,己糖/蔗糖比值较高,糖代谢相关基因大量表达,其中蔗糖合成酶在蔗糖代谢过程中起关键性作用;而在发育中后期,随着种子油脂快速累积,己糖/蔗糖比值和糖代谢水平下降,参与糖代谢的相关基因表达量下调,而脂肪酸合成与油脂累积相关基因表达量明显升高。通过14C蔗糖同位素示踪实验证实:降低种子蔗糖摄入量可以显著抑制糖类向油脂转化,限制蓖麻种子油脂累积。因此,可溶性糖代谢(主要是蔗糖)在蓖麻种子油脂累积过程中具有重要作用。     

沙芥种子发育过程中的脱水耐性

以发育过程中经脱水和未脱水处理的沙芥种子为试验材料,测定了其含水量、萌发率和抗氧化酶系统,探讨了沙芥种子脱水耐性与抗氧化系统之间的关系。结果表明：在20～60DAF,沙芥种子含水量逐渐下降,干重逐渐增加;60DAF种子具有萌发能力,萌发率为24％;且脱水可促进沙芥种子的萌发,人工脱水至含水量为12％和5％时,萌发率分别为56％和44％,自然脱水至含水量为12％和5％时,萌发率分别为52％和60％;发育过程中沙芥种子SOD活性逐渐降低,而CAT、POD、LOX活性以及MDA含量均呈上升趋势;在脱水过程中,随着种子含水量的下降SOD活性逐渐降低,CAT和LOX活性逐渐升高,而POD活性呈先降低后升高的变化趋势。脱水后,种子中MDA含量均高于CK。60DAF的沙芥种子已获得脱水耐性。     

人工老化处理对结球甘蓝种子生理生化特性的影响

以结球甘蓝品种‘冬升’种子为材料,研究高温(40℃)高湿(相对湿度100%)人工老化处理过程中种子的萌发特性、种子浸出液相对电导率和丙二醛、可溶性蛋白、可溶性糖含量以及抗氧化酶活性的变化,以揭示种子劣变的机理。结果表明:(1)人工老化处理甘蓝种子的含水量和不正常苗率均随着老化时间的延长逐渐增加,而种子发芽势、发芽率、发芽指数和活力指数的增加均逐渐降低。(2)随着处理天数的延长,老化处理甘蓝种子的浸出液电导率显著增大,浸出液可溶性糖含量逐渐升高,可溶性蛋白含量表现出显著下降趋势,而种子MDA含量呈先升高后逐渐下降的趋势。(3)在结球甘蓝种子老化进程中,其种子中SOD、POD、CAT活性变化的趋势相似,均随老化程度的加深而逐渐降低;而APX活性在老化处理的最初2d显著增加,第6天显著降低。研究发现,在结球甘蓝种子老化进程中,种子活力和萌发率显著降低,其种子浸出液电导率、可溶性蛋白含量、可溶性糖含量、保护酶活性变化与种子老化及劣变程度密切相关,膜脂过氧化作用可能是引起或加剧种子老化劣变的重要原因之一。     

蔗糖调节拟南芥花青素的生物合成

为了探讨糖在花青素合成过程中的调节作用,采用蔗糖和其代谢糖（葡萄糖 和果糖）组合处理拟南芥幼苗.实验结果表明,60 mmol/L蔗糖处理显著提高拟南芥 幼苗的花青素、还原糖含量,并上调花青素合成相关基因（CHS, FLS-1, DFR, LDOX, BANYULS）的转录,对叶绿素含量和UGT78D2基因的转录无影响;20 mmol/L 葡萄糖+20 mmol/L果糖处理,对花青素、叶绿素和还原糖的含量无影响,对花青素 合成相关基因转录影响不一;20 mmol/L蔗糖+20 mmol/L葡萄糖+20 mmol/L果糖处 理后,花青素和还原糖含量介于前两个处理之间,也上调花青素合成相关基因的转 录;但和蔗糖处理组相比,上调UGT78D2基因转录,下调FLS-1基因转录.在不同处 理组之间,花青素含量变化和还原糖含量变化趋势相同,有可能糖在调节花青素 合成的同时也调节还原糖含量.因此,蔗糖既可以通过蔗糖特异信号途径,也可以 和其代谢糖通过其他途径共同调节拟南芥花青素的生物合成.     

外源一氧化氮对盐胁迫下菊苣生长及渗透调节物质的影响

利用室内砂培实验,研究了外源性一氧化氮(NO)供体硝普钠(SNP,0.2 mmol·L-1)对不同浓度NaC1(140和280 mmol·L-1)胁迫下菊苣(Cichorium intybus L.cv.Commander)幼苗生长及渗透调节物质的影响.结果表明:与空白对照相比,随着盐胁迫时间的延长(6 ～ 15 d),菊苣叶面积、叶长、叶宽以及叶相对含水量(RWC)明显降低,而脯氨酸含量则显著升高(P＜0.05).HPLC分析表明,根中果糖、葡萄糖和蔗糖含量表现为先升高后下降;1-蔗果三糖和蔗果四糖的含量在低盐胁迫下明显下降,而在高浓度盐胁迫下则有所升高.SNP预处理不仅缓解了盐胁迫对菊苣叶的生长和RWC的抑制,而且使脯氨酸含量和蔗果四糖含量急剧增加(P＜0.05),同时降低了果糖、葡萄糖和蔗糖的含量.这说明外源NO能通过增强菊苣幼苗的保水能力,促进渗透调节物质脯氨酸和果聚糖特别是蔗果四糖的生成而增强抵御盐胁迫的能力.     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

Identification and Characterization of the First Equine Parainfluenza Virus 5

正Dear Editor,Parainfluenza virus 5 (PIV5), known as canine parainfluenza virus in the veterinary field, is a negative-sense,nonsegmented, single-stranded RNA virus belonging to the Paramyxoviridae family (Chen 2018). The virus was first reported in primary monkey kidney cells in 1954 (Hsiung1972), then it has been frequently discovered in various