植物细胞壁伸展测定仪在蚕豆扩张蛋白特性研究中的应用

扩张蛋白(expansin)在细胞扩张和果实成熟中起着极为重要的作用.植物细胞壁伸展测定仪是研究扩张蛋白必不可少的仪器.为此以电涡流传感器为核心部件装配了一种具有结构简单、操作方便和测量准确等优点的新型测定仪,并利用该仪器研究了蚕豆(Vicia faba)扩张蛋白的特性.结果表明蚕豆根、茎、上胚轴和成熟叶片中均存在扩张蛋白,而且叶片和幼根的扩张蛋白活性最强;免疫印迹证实在蚕豆根、茎、上胚轴和成熟叶片中确实存在扩张蛋白.以上结果说明本仪器灵敏且可靠,用此仪器首次发现在成熟叶片中存在扩张蛋白.     

一种自动化的植物细胞壁伸展性能测定仪及其应用

应用实验室常用仪器和电子部件,包括直流稳压电源、等臂双盘天平、记录仪、恒流泵、程控仪、线性可变差动变压器（LVDT）、电磁间等,改装和配置成的植物细胞壁伸展性能测定仪,具有操作简便、测量准确和灵敏度高等优点;对大豆幼苗下胚轴生长区细胞壁的内源伸展活性和重组伸展活性的实测结果与文献报告相符,表明该仪器是一种较为理想的准确测定植物细胞壁伸展性能的自动化仪器。     

高等植物细胞壁中的伸展蛋白

高等植物的细胞壁中有一种富含羟脯氨酸的糖蛋白,称为伸展蛋白。其核心蛋白质具有高度重复序列的结构;次级结构为ppⅡ螺旋;它们在细胞质中合成,由高尔基体分泌到细胞壁内组装。作为细胞壁的结构成份,它们的主要功能是调控壁的伸展,并可能在防御反应和形态发生的调节方面起作用。     

植物细胞壁中的伸展蛋白

随着实验技术的发展尤其是分子生物学技术的应用 ,植物细胞壁的研究已取得丰硕的成果。植物细胞壁中最重要的结构蛋白———伸展蛋白 ,是高等植物细胞壁中一族富含羟脯氨酸的糖蛋白 ,起强固细胞壁的作用。本文综述了近几十年对伸展蛋白的分离纯化、结构、生物合成、功能作用及其基因和表达的控制方面的研究     

一种自动化的植物细胞壁伸展性能测定仪及其应用

应用实验室常用仪器和电子部件,包括直流稳压电源、等臂双盘天平、记录仪、恒流泵、程控信仪、线性可变差动变压器（ＬＶＤＴ）、是磁阀等,改装和配置成的植物细胞壁菜性能性能测定仪,具有操作简便、测量准确和灵敏度高等优点;对大豆幼苗下胚轴生长区细胞壁的内源伸展活性和重组伸展活性的实测结果与文献报告相符,表明该仪器是一种较为理想的测定植物细胞伸展性能的自动化仪器。     

大豆幼苗下胚轴扩张蛋白的存在及其特性

用离体细胞壁伸展活性重组法,对大豆（Ｇｌｙｃｉｎｅｍａｘ（Ｌ．）Ｍｅｒ．）幼苗下胚轴细胞壁特异性扩张蛋白的活性鉴定和特性研究结果表明,大豆幼苗下胚轴的延伸生长,既与扩张蛋白的活性升高有关,也与其细胞壁对扩张蛋白的敏感性增加有关;热钝化大豆下胚轴细胞壁的伸展活性,一旦被外源扩张蛋白所恢复,用酸性缓冲液（ｐＨ４．５）代替扩张蛋白提取液,伸展活性不受影响;但若换用中性缓冲液（ｐＨ６．８）,伸展活性丧失殆尽,且与活细胞壁一样,随缓冲液的交替更换而反复逆转;大豆和黄瓜幼苗扩张蛋白可以与其热钝化的细胞壁相互交叉重组。另外,重组的细胞壁伸展活性对扩张蛋白浓度和ｐＨ的依赖性,符合一般酶的催化特征,说明扩张蛋白不仅在植物细胞的延伸生长过程中起着极为重要的作用,而且还暗示植物细胞壁的内源伸展就是该蛋白介导的一种生物化学过程。     

植物伸展蛋白的研究进展

伸展蛋白是高等植物细胞壁中一族富含羟脯氨酸的糖蛋白,在植物细胞壁中发挥着重要的生理功能。综述了近几十年对伸展蛋白结构、功能、基因家族以及生物合成与基因表达调节的研究进展。     

利用湿强度测定仪测定植物细胞壁的机械性能

UsingWetStrengthTestertoMeasuretheMechanicalParametersofPlantCellWallHUANGXu－Ming（CollegeofBiotechnology,SouthChinaAgriculturalUniversity,Guangzhou510642）HUANGHui－Bai（DepartmentofHorticulture,SouthChinaAgriculturalUniversity,Guangzhou510642）细胞壁的机械状态与细胞的膨大生长有密切的关系。～些生理现象,如生理裂果现象,与细胞壁的机械性能密切相关。研究细胞壁机械性能的方法有多种。如利用压力室P－V曲线法,可以推算出细胞壁的弹性模量则asticrllfxlules）［'j;一些特大的细胞,如丽…     

新发现的植物细胞壁蛋白

分别从矮牵牛和菜豆基因文库中分离到的一种基因都编码富含甘氨酸的蛋白质(GRP),经免疫学方法证实,GRP为细胞壁蛋白。从玉米悬浮培养细胞中分离到富含苏氨酸与羟脯氨酸的糖蛋白(THRGP)和富含组氨酸与羟脯氨酸的糖蛋白(HHRGP)。氨基酸及中性糖的组成、分子形状、免疫特性等生化特点都表明THRGP和HHRGP是单子叶植物类型的细胞壁蛋白。     

Expansin(细胞壁松弛蛋白)的发展

Expansin是一种体外诱导分离的植物细胞壁伸展的蛋白,在修饰细胞壁基础上使细胞膨胀。Expansin的功能众多,除了促进细胞生长,还包括影响营养生长、形态发生、授粉受精、果实软化等,并表现出高度的组织、器官和细胞特异性。目前已经在多种植物及其他一些生物范围内对expansin及类expansin序列和蛋白质进行了研究,并对它们的作用机制进行了探索。     

Circadian Stomatal Rhythms in Epidermal Peels from Vicia faba

Circadian rhythms in stomatal aperture and in stomatal conductance have been observed previously. Here we investigate circadian rhythms in apertures that persist in functionally isolated guard cells in epidermal peels of Vicia faba, and we compare these rhythms with rhythms in stomatal conductance in attached leaves. Functionally isolated guard cells kept in constant light display a rhythmic change in aperture superimposed on a continuous opening trend. The rhythm free-runs with a period of about 22 hours and is temperature compensated between 20 and 30°C. Functionally isolated guard cell pairs are therefore capable of sustaining a true circadian rhythm without interaction with mesophyll cells. Stomatal conductance in whole leaves displays a more robust rhythm, also temperature-compensated, and with a period similar to that observed for the rhythm in stomatal aperture in epidermal peels. When analyzed individually, some stomata in epidermal peels showed a robust rhythm for several days while others showed little rhythmicity or damped out rapidly. Rhythmic periods may vary between individual stomata, and this may lead to desynchronization within the population.     

Favin, a crystalline lectin from Vicia faba

A lectin from the fava bean (Vicia faba) has been purified and crystallized in a form suitable for high-resolution crystallographic structure analysis. This protein binds glucose- and mannose-like saccharides, and it is mitogenic for lymphocytes. The fava lectin crystallizes in the orthorhombic space group. P2₁2₁2₁ with unit cell dimensions $\text{a = 90.0, b = 89.3,}\text{and}\text{c = 67.4}\text{A}\text{?}$. The mass of protein in the asymmetric unit is 53,000 daltons, corresponding to the molecular weight of the protein in solution.     

Agrobacterium-mediated transformation of Vicia faba

Among the major grain legume crops, Vicia faba belongs to those where the production of transgenic plants has not yet convincingly been reported. We have produced stably transformed lines of faba bean with an Agrobacterium tumefaciens-mediated gene transfer system. Stem segments from aseptically germinated seedlings were inoculated with A. tumefaciens strains EHA101 or EHA105, carrying binary vectors conferring (1) uidA, (2) a mutant lysC gene, coding for a bacterial aspartate kinase insensitive to feedback control by threonine, and (3) the coding sequence for a methionine-rich sunflower 2S-albumin, each in combination with nptII as selectable marker. Kanamycin-resistant calluses were obtained on callus initiation medium at a frequency of 10–30%. Shoot regeneration was achieved on thidiazuron containing medium in a second culture step. A subsequent transfer of shoots to BA-containing medium was necessary for stem elongation and leaf development. Shoots were rooted or grafted onto young seedlings in vitro and mature plants were recovered. Molecular analysis confirmed the integration of the transgenes into the plant genome. Inheritance and expression of the foreign genes was demonstrated by Southern blot, PCR, western analysis and enzyme activity assays. Although at present the system is time-consuming and of relatively low efficiency, it represents a feasible approach for the production of genetically engineered faba beans.     

Nitrogen Metabolism of Vicia faba

Vicia faba plants were grown for four and six weeks without externally supplied nitrogen. Some nitrogen was transported to the plant axis from the cotyledons throughout this period, but the amount available was insufficient to support maximum shoot growth. During this period the protein content of the shoot declined whilst the free amino acids, especially aspartic acid, glutamic acid, histamine and the combined pool for threonine, serine, asparagine and glutamine and ammonia, increased in amount. In contrast to the shoot the protein content of the root increased as did their free amino acid content, but the increase in the latter was less than in the shoot and only the combined value for threonine, serine, asparagines and glutamine increased significantly. During tbe last two weeks growth, some soluble non-amino acid compound appeared to donate nitrogen to the pool of free amino acids in the root and shoot.     

Sister chromatid exchanges in Vicia faba

Evolutionary loss of the Y chromosome has occurred in Climacia areolaris (Hagen) of the neuropteran family Sisyridae. The diploid set comprises 6 pairs of autosomes, plus 2 X chromosomes in the female and 1 X in the male. The Y is retained in Sisyra vicaria (Walker) of the same family: its chromosome number is 14 in both sexes including 2X chromosomes in the female and 1X plus Y in the male. Two alternative pathways for the segregation of the sex chromosomes-distance segregation and sex bivalent formation-co-exist in the latter species in a ratio of approximately 1 to 6; the possible phylogenetic significance of this feature is discussed.     

RNA synthesis in roots of Vicia faba

Roots of V. faba were grown in solutions of ³H-cytidine and ³H-uridine, RNA precursors, for 30 min, 1 hr or 2 hr. Grain counts were made over nuclei and cytoplasm in squash preparations. By means of these counts, synthesis of RNA was followed in interphase and dividing cells. Results indicate that:

• 1.1. RNA is synthesized in the nuclei of cells in interphase and early and middle prophase. There appears to be no synthesis in cells in mitosis.
• 2.2. Labeled RNA moves from the nuclei to the cytoplasm.
• 3.3. In late prophase, nuclear RNA is shed into the cytoplasm with the breakdown of the nuclear membrane and nucleolus.
• 4.4. Some grains were seen over the chromosomes. Of the RNA in the nucleus in prophase, very little of it appears to become a chromosome constituent.

     

Variability among Rhizobium Strains Originating from Nodules of Vicia faba

Rhizobium strains from nodules of Vicia faba were diverse in plasmid content and serology. Results of multilocus gel electrophoresis and restriction fragment length polymorphism indicated several deep chromosomal lineages among the strains. Linkage disequilibrium among the chromosomal types was detected and may have reflected variation of Rhizobium strains in the different geographical locations from which the strains originated. An investigation of pea strains with antibodies prepared against fava bean strains and restriction fragment length polymorphism analyses, targeting DNA regions coding for rRNA and nodulation, indicated that Rhizobium strains from V. faba nodules were distinguishable from those from Pisum sativum, V. villosa, and Trifolium spp.