脱水胁迫对连翘和冬青卫矛叶片细胞质外体和微环境的影响

用压力室、电导法和原子吸收分光光度分析法综合分析测定了连翘[Forsythiasuspensa (Thunb.) Vahl]和冬青卫矛(Euonymus japonicus Thunb.)在不同程度脱水胁迫时细胞外部微环境的变化.结果表明:(1)在脱水胁迫条件下,叶片细胞随着脱水胁迫强度的加大,细胞内离子外渗的累计量不断加大,但细胞内离子外渗的速度在不同的区间内并无明显的改变,即细胞膜的透性在所测范围内没有明显变化.(2)脱水胁迫同时造成了叶片质外体和共质体溶液中钠、钾离子浓度的增加,但质外体比共质体溶液中钠、钾离子浓度的增加幅度更高,导致细胞内、外离子浓度梯度的改变和离子平衡膜电位的改变,这些改变有可能引起细胞的次生生理变化,并有可能与植物的伤害反应和抗性有关.     

冬青卫矛叶片质外体适应冬季胁迫的蛋白质组学分析

植物的质外体在感知外界信号和胁迫应答中起重要作用。该研究采用生理生化和蛋白质组学方法,对秋季和冬季冬青卫矛叶片的理化指标、微观结构以及叶片质外体液体中的蛋白变化进行比较分析,探索冬青卫矛叶片质外体响应冻胁迫的分子机制,以期为植物抗冻分子机制研究提供依据。结果表明:(1)冬季冬青卫矛叶片中MDA、可溶性糖含量以及SOD、POD活性均显著升高,气孔张开度减小,叶片厚度变小。(2)冬季冬青卫矛质外体液体中的蛋白质种类和含量显著高于秋季。(3)冬青卫矛叶片质外体液体中共鉴定到838个肽段和194个蛋白质;与秋季相比,冬季冬青卫矛叶片质外体液体中共筛选到43种差异积累蛋白(DAPs),其中26个蛋白质显著上调,17个蛋白质显著下调;蛋白表达模式显示,胚胎发育晚期丰富蛋白质、铁超氧化物歧化酶、过氧化物酶、丝氨酸羧肽酶等在冬季表达量较高,推测它们可能是冬季胁迫响应敏感的蛋白质。(4)KEGG富集分析显示,差异蛋白主要与应激防御、细胞壁修饰、抗病、自由基清除、甘油脂类代谢、淀粉和蔗糖代谢、次生代谢物的生物合成等生物学过程相关。(5)验证实验结果表明,冬季冬青卫矛8个差异积累蛋白与其对应的基因的表达趋势一致。研究认为,冬季冬青卫矛质外体液体中积累的蛋白可通过清除活性氧、促进单糖、寡糖和游离氨基酸等渗透调节物的生成而增强对环境的适应;推测冬青卫矛质外体中积累的单糖和寡糖可能通过增加质外体液体的浓度从而降低冰点,进而提高冬青卫矛对冬季胁迫的耐受性。     

西藏冬青科和卫矛科新植物

(—6)厘米,先端突然长渐尖至尾尖,基部近圆形至阔楔形,两面无毛;中脉在上面下陷,下面凸起,侧脉8—10对,两面明显凸起,网脉显著。叶柄纤细,长1—1.5厘米,上面有深槽,无毛。花序未见。果序腋生,成簇,序轴长1毫米;苞片宿存,三角状卵形,膜质;果柄长1毫米。果卵球形,直径5—6毫米;花萼宿存,4裂,柱头头形或厚盘形,有核4粒,背部具沟。     

冬青卫矛斑蛾的生物学特性和防治

<正> 冬青卫矛斑蛾 Pryeria sinica Moore,又名大叶黄杨长毛斑蛾,属鳞翅目、斑蛾科。已知分布于江苏、浙江、安徽;日本、朝鲜等地。在南京地区,该虫是冬青卫矛 Euonymus japonicus L.及其变种银边冬青卫矛 E.japonicus var.     

低温处理对北美冬青叶片抗氧化能力的影响

为了解低温对北美冬青(Ilex verticillata)生长的影响,对2年生扦插苗经低温处理(-6℃)后的生长和抗氧化能力进行了研究。结果表明,随着低温处理时间的延长,北美冬青叶片的叶绿素/类胡萝卜素比值和叶绿素b含量增加,而其他色素含量都呈下降趋势;相对电导率(REC)和H_2O_2含量(72 h除外)显著增加。低温处理对超氧化物歧化酶(SOD)活性影响不大,却显著降低CAT的活性。低温处理过氧化物酶(POD)活性显著提高,48 h活性达到最高;而抗坏血酸过氧化物酶(APX)活性在处理12 h达最高,然后下降。还原型抗坏血酸(As A)、还原型谷胱甘肽(GSH)含量均呈先升高再下降的趋势。因此,北美冬青在短时间内(≤24 h)能够忍受低温(-6℃),抗氧化防御系统在低温初期起关键的作用,但随时间延长(72 h)其抗氧化能力减弱。     

女贞和珊瑚树叶片表面特征的AFM观察

应用原子力显微镜观察了女贞(Ligustrum lucidum)、珊瑚树(Viburnum odoratissimum)幼叶和成熟叶的表面特征,并探讨了叶面微结构对滞尘能力的可能影响以及抵抗干旱、污染物等胁迫的能力。女贞幼叶和成熟叶正背面的粗糙度Ra分别为417.8、794.5,1069、957.4 nm;珊瑚树幼叶和成熟叶正背面的粗糙度Ra分别为471.3、469.6,291.1、865.9 nm。和幼叶相比,成熟叶表面的粗糙度发生变化,但2个物种的变化趋势不同,这种变化可能与气孔的发育以及外界环境条件对叶片表面形态结构、蜡质含量和成分的影响不同有关。叶片表面存在大量的沟状、孔状峰谷区域和直径约为10 μm的凹陷,有利于PM₁₀的滞留。女贞和珊瑚树成熟叶气孔只分布在叶下表皮且下陷。这些特征均说明女贞和珊瑚树具有较强的滞尘能力和抵抗干旱、污染物胁迫的能力,作为绿篱植物对消减城市大气颗粒物污染和提高空气质量具有重要的意义。     

胞外和胞内菌胞外囊泡的功能及应用

细胞外囊泡(Extracellular Vesicles,EVs)是从细胞膜上脱落或者分泌的双层膜结构的囊泡状小体.真核生物、细菌、古细菌和支原体等具有细胞结构的生物均能够释放EVs.细菌分泌的EVs含有DNA、RNA及蛋白质等多种成分,其在细菌毒力保持、免疫逃逸、细菌间物质运输、宿主细胞免疫调节、宿主转录基因调节、耐...     

番茄叶片胞外β－半乳糖苷酶的纯化和性质

健康或系统感染ＴＭＶ的番茄叶片胞外都存在高比活可溶性β－半乳糖苷酶。系统感染ＴＭＶ的番茄叶胞外提取液经冰冻干燥浓缩、－２０℃丙酮沉淀、ＣＭ－ＳｅｐｈａｄｅｘＣ－２５阳离子交换层析、ＤＥＡＥ－ＳｅｐｈａｄｅｘＡ－２５阴离子交换层析和ＳｅｐｈａｄｅｘＧ－１５０凝胶层析纯化．获得ＰＡＧＥ和ＳＤＳ－ＰＡＧＥ均一的β－半乳糖苷酶。该酶的分子量为７４ｋＤ．酶蛋白带能被过碘酸－Ｓｃｈｉｆｆ试剂染成桃红色,属糖蛋白。β－半乳精苷酶无论在健康或系统感染ＴＭＶ的番茄叶中,均为主要的胞外蛋白组分之一。     

番茄叶片胞外β—半乳糖苷酶的纯化和性质

健康或系统感染ＴＭＶ的番茄叶片胞外都存在高比活可溶性β－半乳糖苷酶。系统感染ＴＭＶ的番匣叶胞外提取液经冰冻干燥浓缩－２０℃丙酮沉淀、ＣＭ－ＳｅｐｈａｄｅｘＣ－２５阳离子交换层析、ＤＥＡＥ－ＳｅｐｈａｄｅｘＡ－２５阴离子交换层析和ＳｅｐｈａｄｅｘＧ－１５０凝胶层析纯化,获得ＰＡＧＥ和ＳＤＳ－ＰＡＧＥ均一的β－半乳糖苷酶。该酶的分子量为７４ｋＤ,酶蛋白带能被过碘酸－Ｓｃｈｉｆｆ试剂染成档红色,属糖蛋白     

调控细胞衰老的胞外环境和胞内因子

衰老是一个多因素调控的不可逆的复杂生命过程,受多种胞外环境和胞内因子影响,表现为胞内组分损伤的积累和生物学功能的逐步退化。随着近年来对衰老研究的不断深入,一些衰老调控分子机制逐渐被揭开。研究显示,许多衰老调控相关的信号通路从单细胞真核生物酵母到哺乳动物是高度保守的。事实上,从简单真核生物酵母中获得的衰老调控机制,可为包括人类在内的高等生物的衰老研究提供极具价值的参考。本综述主要以单细胞真核生物酵母为对象,从胞外环境和胞内因子两方面,阐述调控衰老的相关因素及其调控机制,最后结合衰老研究现状展望了衰老研究的前景,为延缓高等生物衰老和衰老相关疾病的发生发展提供参考。     

Enzymatic Activities for the Synthesis of Chlorophyll in Pigment-Deficient Variegated Leaves of Euonymus japonicus

The enzymes involved in the biosynthesis of chlorophyll (Chl)in pigment-deficient variegated leaves of Euonymus japonicuswere investigated. Each variegated leaf was composed of clearlydelineated green and white sectors. The white sectors containedalmost no Chls. The rate of synthesis of 5-aminolevulinic acid(ALA) in the white sectors in vivo was twice that in the greensectors. The level of glutamate 1-semialdehyde aminotransferasein the white sectors was much higher than that in the greensectors. Plastidic tRNA^Glu was also present at substantial levelsin the white sectors, indicating that the system for synthesisof ALA was very active in the white sectors. The activity of porphobilinogen (PBG) synthase in the whitesectors in vitro was twice that in the green sectors. In thewhite sectors the rate of porphyrin synthesis from PBG was 4-to 6-fold higher than in the green sectors. We measured Mg-chelataseactivity indirectly in both sectors by monitoring the accumulationof Mg-protoporphyrin IX in the presence of 2,2'-dipyridyl, whichinhibits isocyclic ring formation with the resultant accumulationof Mg-protoporphyrin IX. When sectors were incubated in darknesswith 2,2'-dipyridyl, large amounts of protoporphyrin IX accumulatedin the white sectors, whereas Mg-protoporphyrin IX mainly accumulatedin the green sectors. These results suggest that the enzymesfor the synthesis of porphyrin that catalyze conversion of ALAto protoporphyrin IX were very active and that the Mg-insertionstep might be blocked in the white sectors, with the resultantfailure to synthesize Chl. The deficiency is discussed in acomparison with that in other Chl-deficient plants. (Received November 15, 1995; Accepted March 21, 1996)     

一种女贞叶抗冻蛋白的分离纯化

根据抗冻蛋白与冰结合的特性, 利用碎冰从女贞(Ligustrum lucidum)叶提取液中分离出抗冻蛋白。结果表明, 通过碎冰吸附、凝胶过滤和离子交换层析可以获得4个组分的蛋白质, 其中的1个经鉴定具有热滞活性。在蛋白质浓度为5 mg. mL-1时, 它的热滞活性(thermal hysteresis activity, THA)值为0.678°C, 对其进行全波长扫描(200-1 000 nm)发现在975nm处有吸收峰; 该蛋白亲水性氨基酸含量较高。     

一种女贞叶抗冻蛋白的分离纯化

根据抗冻蛋白与冰结合的特性,利用碎冰从女贞(Ligustrum lucidum)叶提取液中分离出抗冻蛋白。结果表明,通过碎冰吸附、凝胶过滤和离子交换层析可以获得4个组分的蛋白质,其中的1个经鉴定具有热滞活性。在蛋白质浓度为5mg.mL-1时,它的热滞活性(thermal hysteresis activity,THA)值为0.678°C,对其进行全波长扫描(200-1000nm)发现在975nm处有吸收峰;该蛋白亲水性氨基酸含量较高。     

A Freeze-Fracture Study of the Cell Membranes of Wheat Adapted to Extracellular Freezing and to Growth at Low Temperatures

Seedlings of Triticum aestivum L. cv. Lennox were grown in natural(late autumn) or controlled environments differing in temperature,to give plants differing either only in growth adaptation oralso in hardiness. The frost hardiness of laminae and leaf baseswas measured using an ion leakage method. Pieces of laminaeand leaf bases were freeze-fixed without chemical cryo-protectantor chemical fixative. The number of particles per unit area of the E fracture faceof the plasma membrane was substantially reduced in laminaefrom the environment inducing most hardening, compared to unhardenedcontrols. This difference in frequency of particles on the Eface was not related to adaptation of growth to low temperature(in the leaf bases) and was not an artificial consequence ofchemical treatment prior to freeze-fixation. The density ofparticles on the P face of the plasma membrane was unaffectedby growth environment. More limited data suggested the densityof particles on either fracture face of the thylakoids was alsounaffected. Unlike an earlier report, particle-free areas ofplasma membrane were not found in hardened tissue. Environment did not affect (a) the width of the ‘mouth’at the plasma membrane-plasmodesma junction in the leaf basesor (b) the size of the nuclear pores. Membrane accumulated belowthe plasma membrane only in some cells from the hardiest material. Key words: Hardiness, Membranes, Triticum     

金边黄杨与大叶黄杨光合特性的比较

在田间条件下,比较金边黄杨与大叶黄杨光合生理特性的结果表明：（1）金边黄杨的叶绿素含量极显著低于大叶黄杨,类胡萝卜素和花色素苷含量无显著差异;（2）金边黄杨的光合能力显著低于大叶黄杨,表现量子效率、羧化效率分别为大叶黄杨的54％和50％;（3）二者的净光合速率日变化均为单峰曲线,金边黄杨净光合速率和蒸腾速率日积分值分别为大叶黄杨的60％和75％。     

Water Relations of Pachysandra Leaves during Freezing and Thawing : Evidence for a Negative Pressure Potential Alleviating Freeze-Dehydration Stress

The evergreen herb Pachysandra terminalis becomes moderately frost-hardy in winter. The water relations of its frost-hardy leaves were studied during a freeze-thaw cycle. Leaf water potentials, measured by psychrometry at subfreezing temperatures, were identical with those of ice, indicating equilibrium freezing. Microscopic observations showed extracellular freezing of tissue water. As evidenced by thermal analysis, the freezing process starts with the crystallization of a minor volume which was identified as apoplasmic water. The following long-lasting exotherm indicated slow export of water from the protoplasts driven by extracellular crystallization. In partially frozen leaves, the fractions of liquid water were measured at several subfreezing temperatures by nuclear magnetic resonance spectroscopy. They were consistently greater than those calculated from the osmotic potentials of cellular fluid, and the differences increased with decreasing temperature. About 50% of the differences could be abolished by freeze-killing of the leaf and was thus ascribed to the effect of a (negative) pressure reinforcing the osmotic potential. The persistent part of the differences may have reflected a matric component. At −7°C, the absolute values of both potentials were −1.7 megapascals each. The water relations of Pachysandra leaves clearly indicate nonideal equilibrium freezing where negative pressures and matric potentials contribute to the leaf water potential and thus alleviate freeze-dehydration of the tissue.     

The Effect of High Temperatures on the Photosynthetic Activity of Intact Barley Leaves at Low and High Irradiance

Light curves of CO₂ fixation by barley seedling leaves preliminarily heated at 30–43°C for 5 min were measured. The slope of the linear part of the light curve decreased after leaf heating at temperatures above 35°C; whereas, at a high light level, the photosynthesis rate decreased only at temperatures of 40°C and higher. The linear relationships between the photosynthetic CO₂-fixation rate and a photon flux density up to 1400 mol/(m² s) were found in leaves preheated at 42°C; this indicates the strong nonphotochemical dissipation of absorbed light quanta. The lowering of the oxygen concentration from 21 to 1% led to a CO₂ fixation maximum quantum yield and a photosynthesis-rate increase at the highest light intensity in leaves preheated at temperatures above 40°C as compared to the control leaves. Nevertheless, the linear relationship between the photosynthetic CO₂ fixation and the light intensity was found in leaves heated at 42°C at O₂ concentrations of both 21 and 1%. The latter fact suggests that the proton gradient of the thylakoid membrane, which causes an increase in the nonphotochemical dissipation of the quanta absorbed, could also be formed due to the cyclic electron transport over photosystem I.