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71.
Danilo Marques María Betiana Ângulo Jimi Naoki Nakajima Massimiliano Dematteis 《Nordic Journal of Botany》2018,36(9)
Lepidaploa belongs to tribe Vernonieae, one of the most complex tribes of Asteraceae, and the relationships within Lepidaploa and among related genera are poorly understood. Microcharacters may be of taxonomic value and may be used in the identification of taxa at different ranks. To evaluate the reliability of microcharacters as taxonomic markers in this group, we analysed the micromorphology of phyllaries, florets and cypselae in detail in 23 species of Lepidaploa .The species were studied using stereo, light, and scanning electron microscopy. Eight trichome types (eglandular and glandular) were observed on phyllaries, florets and cypselae, in addition to crystals, idioblasts and other microstructures. The results demonstrates that the ocurrence of different combinations of trichome types and crystals, presence of a stylar basal node, idioblasts and glandular apical anther appendages are highly useful to differentiate between related species of Lepidaploa and a diagnostic key using these characters is presented. However, these characters are not of much use to distinguish between closely related genera of Vernonieae since most characters appear homeoplasic and are found in representatives of different genera. 相似文献
72.
73.
Parasporal crystals of Bacillus thuringiensis var. entomocidus were separated from spores and other cell debris by the water-chloroform biphase procedure. The solubilization and fractionation were carried out under mild conditions at 4°C. Crystals were solubilized in 0.01 M dithiothreitol and 0.2 M glycine NaOH buffer at pH 10.0. The solution was treated overnight with 0.01 M Tris-HCl buffer, pH 5.5, containing 0.1% Triton N-101 and 0.1% sodium cholate, and then placed on a Sepharose 6B column, equilibrated, and later developed with the same buffer. Under these conditions, four fractions were obtained, one of which had a molecular weight ranging from 60,000 to 70,000, and demonstrated a high insecticidal activity on second instar larvae of Spodoptera litioralis. The LC50 value of this fraction was a half of that of the solubilized crystals. The other three fractions had a lower activity. The active fraction was further fractionated on an octyl-Sepharose 4B resin. Elution of this column with the same buffer separated the proteins into two fractions. The first eluted fraction was highly active, while the second demonstrated a very low activity. The active fraction was further purified by loading on a short column of octyl-Sepharose 4B and eluted with a linear gradient of the same detergents. Under these conditions, the highly active fraction gave a sharp and symmetrical peak that revealed five close bands at the pH range of 6.1–6.5 on isoelectric focusing gel electrophoresis. 相似文献
74.
Complexes of boric acid with sodium- and magnesium-salicylates were prepared and analyzed to examine the structural consequences resulting from the coordination of the salicylate ligand in mono- and bis-chelate modes. The complexes were isolated from aqueous solutions and characterized by FTIR (Fourier Transform Infrared), TGA (Thermogravimetric Analysis) and DTA (Differential Thermal Analysis) techniques. Interpretation of their spectral patterns and thermal stabilities established systematic differences and allowed a direct comparison between the mono- and bis-chelate structures. Magnesium bis-salicylatoborate, [Mg(H2O)6][B(Sal)2]·4H2O, was obtained in crystal form and presented as a new type of double-layered material, a unique feature among the salicylatoborate structures reported so far. 相似文献
75.
Hochkoeppler A Landau EM Venturoli G Zannoni D Feick R Luisi PL 《Biotechnology and bioengineering》1995,46(2):93-98
Photosynthetic reaction centers, isolated and purified from the facultative phototrophic bacterium Chloroflexus aurantiacus, were immobilized in optically transparent lipidic cubic phases composed of 42% (w/w) 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphocholine and 58% (w/w) water. The immobilized photosynthetic protein retains its native properties, as indicated by visible and circular dichroic spectra. The ground state visible spectrum of the immobilized reaction centers is very similar to the corresponding spectrum in aqueous solution, indicating that the protein pigments are not extracted into the lipidic regions of the cubic phase. The secondary structure of the protein is maintained in the immobilized state, as determined by far-UV circular dichroism spectroscopy in the 200- to 250-nm range. Moreover, immobilized reaction centers retain their photochemical activity: a reversible photo-oxidation of the primary electron donor (P) is seen upon continuous illumination. Furthermore, the entrappment of reaction centers does not affect the kinetics of charge recombination between the photo-oxidized primary donor (P(+)) and the photoreduced primary quinone acceptor, generated by a short flash of light. Reaction centers devoided of the secondary quinone acceptor can be easily reconstituted in cubic phases by means of their coimmobilization with 1,4-naphtoquinone. Indeed, the kinetics for charge recombination in reconstituted reaction centers is dramatically slower than the corresponding kinetics in the unreconstituted protein. Interestingly, immobilized reaction centers are significantly stabilized as compared with reaction centers in aqueous solution: the integrity of the protein in the cubic phase is maintained for at least 5 months, whereas in water solution 50% of the activity is lost within 2 months. (c) 1995 John Wiley & Sons, Inc. 相似文献
76.
从青岛采集的多管藻(Polysiphoniaurceolata)中分离得到的R-藻蓝蛋白,在pH=7.0的0.05mol/L磷酸盐-硫酸铵缓冲液中,使用悬滴气相扩散法获得适合X光衍射分析用单晶。经Buerger徘循照相和XRD—100面探测仪分析,R-藻蓝蛋白晶体属于四方晶系,空间群为P41(3)212,晶胞参数:a=b=137.5c=218.5α=β=γ=90°。用等比重梯度柱法测定了晶体和母液的比重分别为1.19和1.09。根据分子量与晶胞体积估算,一个不对称单位含有一个分子,推测它的分子聚集态形式为(αβ)3。 相似文献
77.
Andreas Hirsch Thomas Wacker Jürgen Weckesser Kay Diederichs Wolfram Welte 《Proteins》1995,23(2):282-284
The porin from Paracoccus denitrificans ATCC 13543 was purified and crystallized. Two crystal forms were obtained from porin solutions with β-d-octylglucopyra-noside as detergent. Crystals of form I belong to the monoclinic spacegroup C2 with unit cell dimensions a = 112.2 Å, b = 193.8 Å, c = 100.5 Å and β = 129.2°. There is 1 trimer per asymmetric unit. Crystals of form II are triclinic with α = 89.7 Å, b = 98.8 Å, c = 112.5 Å, b = 112.5Å, β = 101.8°, γ = 106.7° (2 trimers per asymmetric unit). Both crystal forms diffract to 3 Å. © 1995 Wiley-Liss, Inc. 相似文献
78.
E. CROW C. H. STIRTON D F. CUTLER 《Botanical journal of the Linnean Society. Linnean Society of London》1997,124(2):155-182
Leaf anatomy is described from 17 species of Psoralea sensu stricto which includes four species of the genus Hallia Thunberg. Species of the two genera share many characters including the presence of rod-shaped crystals, similar stipule structure and a possible continuum in secretory cavity anatomy ranging from a small and non-trabeculate to a large and trabci ulate form. Hallia species are distinguished b the presence of large tannin cells in the bundle sheaths and a narrow lcngllv.width ratio of palisade cells. In the light of other floral evidence this is considered insufficient to separate the two genera, a view confirmed by cluster analysis. Thus, Salter's proposal of 1939 for their amalgamation is supported. Leaf anatomy of herbaceous species is compared with that of seedlings of Psoralea sp. to assess the possibility that the herbaceous species may have arisen through neoteny from species that are trees or shrubs. Comparative venation studies between stipules and scale leaves suggest that the scale leaf form arose from pinnate-leaved ancestors by leaf reduction. 相似文献
79.
Accumulation of cadmium, lead and strontium, and a role of calcium oxalate in water hyacinth tolerance 总被引:2,自引:0,他引:2
Eichhornia crassipes plants brought from the River Nile were cultured in jars containing river water supplemented with various
concentrations of Cd, Pb, and Sr (0 to 100 μg cm-3), added simultaneously. Treatment continued for 20 d during which each
cultivation solution was being replaced with fresh one every 3 d. The growth of Eichhornia was drastically retarded at heavy
metal concentrations higher than 15 μg cm-3. At concentrations 15 or 25 μg cm-3, the accumulation of Cd and Pb to levels several
times higher than those in control plants was found. More than 50 % of the uptaken metals were retained by roots alone. Leaves
and leaf petiols received around 30 and 20 % of the accumulated metals, respectively. X-ray microanalysis indicated the presence
of the three heavy metals in Ca oxalate crystals. Content of metals in the crystals increased progressively over time of exposure
in a way similar to those in whole plant tissues. These results suggest a possible role for Ca oxalate crystalization in toxic
heavy metal deposition and thus tolerance by Eichhornia.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
80.
Single crystals of bacteriophage T7 RNA polymerase 总被引:1,自引:0,他引:1
Single crystals of T7 RNA polymerase have been grown to a maximum size of 1.8 x 0.3 x 0.3 mm. The crystals are composed of fully intact T7 RNA polymerase which is enzymatically active upon dissolution. These crystals belong to the monoclinic space group P2(1) and have unit cell parameters a = 114.5 A, b = 139.6 A, c = 125.7 A, and beta = 98.1 degrees. Self-rotation function studies indicate that there are three molecules per asymmetric unit. The crystals diffract to at least 3.0 A resolution. These are the first crystals of a DNA-dependent RNA polymerase suitable for high-resolution X-ray structure determination. 相似文献