Biosynthesis of pentacyclic triterpenoids in leaves of Ilex aquifolium L.

Ilex leaves can utilize sucrose and mevalonate for the synthesis of triterpene esters. Mevalonate is also used for the synthesis of free triterpenoid alcohols, but sucrose is not. The selectivity of precursor utilization indicates separate sites for triterpenol and triterpenol-ester synthesis. The sites of synthesis are not found at the main locations of accumulation of triterpenols (the epicuticular wax) or triterpene esters (the cytoplasmatic lipid globules). Transport from the site of synthesis to the lipid globules, and especially towards the epicuticular wax, is slow.Abbreviations MVA mevalonic acid lactone - TLC thin layer chromatography     

Structural analysis of wheat wax (Triticum aestivum, c.v. ‘Naturastar’ L.): from the molecular level to three dimensional crystals

In order to elucidate the self assembly process of plant epicuticular waxes, and the molecular arrangement within the crystals, re-crystallisation of wax platelets was studied on biological and non-biological surfaces. Wax platelets were extracted from the leaf blades of wheat (Triticum aestivum L., c.v. ‘Naturastar’, Poaceae). Waxes were analysed by gas chromatography (GC) and mass spectrometry (MS). Octacosan-1-ol was found to be the most abundant chemical component of the wax mixture (66 m%) and also the determining compound for the shape of the wax platelets. The electron diffraction pattern showed that both the wax mixture and pure octacosan-1-ol are crystalline. The re-crystallisation of the natural wax mixture and the pure octacosan-1-ol were studied by scanning tunnelling microscopy (STM), atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Crystallisation of wheat waxes and pure octacosano-1-ol on the non polar highly ordered pyrolytic graphite (HOPG) led to the formation of platelet structures similar to those found on the plant surface. In contrast, irregular wax morphologies and flat lying plates were formed on glass, silicon, salt crystals (NaCl) and mica surfaces. Movement of wheat wax through isolated Convallaria majalis cuticles led to typical wax platelets of wheat, arranged in the complex patterns typical for C. majalis. STM of pure octacosan-1-ol monolayers on HOPG showed that the arrangement of the molecules strictly followed the hexagonal structure of the substrate crystal. Re-crystallisation of wheat waxes on non-polar crystalline HOPG substrate showed that technical surfaces could be used to generate microstructured, biomimetic surfaces. AFM and SEM studies proved that a template effect of the substrate determined the orientation of the re-grown crystals. These effects of the structure and polarity of the substrate on the morphology of the epicuticular waxes are relevant for understanding interactions between biological as well as technical surfaces and waxes.     

中药郁金挥发油成分及挥发油中蜡质成分研究

对中药郁金挥发油成分进行ＧＣ－ＭＳ－ＤＳ分析,共分离得到１３７个气相色谱峰,鉴定出７３种成分,其中３６种为首次鉴定出。首次,作者对其挥发油中蜡质成分进行分离,经ＧＣ－ＭＳ－ＤＳ分析得其主要成分为长直链烷烃和长直链脂肪酸。     

D2 Receptors May Modulate the Function of the Striatal Transporter for Dopamine: Kinetic Evidence from Studies In Vitro and In Vivo

Abstract: Recently it was hypothesized by others that the D₂dopamine receptor can regulate the uptake of dopamine. However, the evidence in support of this hypothesis, although compelling, was not based on observations related to direct measures of the kinetic activity of the transporter itself. Here kinetic evidence in support of this hypothesis is shown. The apparent time-resolved initial velocity of the transport of 1.0 μ M dopamine into striatal suspensions, measured using rotating disk electrode voltammetry, was found to increase in the presence of the D₂ receptor agonist, quinpirole, at 100 μ M . This effect was reversed by sulpiride. In separate studies it was shown that acute and chronic treatments with haloperidol at 0.5 mg/kg, i.p., reduced the reuptake transport of dopamine in vivo following intrastriatal stimulation of its release by K⁺. Thus, it appears that D₂ receptors may influence the functioning of the striatal transporter for dopamine. These results are consistent with a model in which presynaptically released dopamine may feed back onto the function of its transporter to increase the velocity of the clearance of synaptic dopamine following an action potential, suggesting the existence of a mechanism, in addition to release and synthesis modulation, for fine-tuning dopaminergic chemical signaling.     

The surface wax composition of the exuviae and adults of Aleyrodes singularis

Long-chain aldehydes, alcohols, hydrocarbons and wax esters were major components of the external lipids of adult Aleyrodes singularis. In exuviae, acetate esters replaced the hydrocarbons as a major component. The major long-chain alcohol and aldehyde from adults were C32 and were essentially the exclusive components of the wax particles. The major alcohol from exuviae was C26 and the aldehydes were C26, C28, C30 and C32. The major acetate esters were C28 and C30 in both adults and exuviae. There were wax esters of similar carbon number in adults and exuviae although the exuviae had a greater amount of wax esters with unsaturated fatty acids. The fatty acid and alcohol composition of the wax esters differed markedly between adults and exuviae. Wax esters of adults had similar amounts of C16, C18, C20, C22 and C24 fatty acids while those from exuviae contained largely C16 and C18. The major alcohol in the wax esters of adults was C22 and those of exuviae were C26 and C28. The distribution of fatty acids and alcohols among wax esters of varying chain length also differed between adults and exuviae: in adults C22 was the major fatty acid found in the dominant wax ester, C44 and the C22 alcohol was the major alcohol and found in wax esters C42 and C44. In exuviae C16 and C18 were the major fatty acids found in most wax esters and a C28 alcohol was the major alcohol found in wax esters C44 and C46, the two dominant wax esters in exuviae. It was clear that the difference in chemistry of the wax esters between the adults and exuviae is not evident unless the acid and alcohol moieties are characterized.     

Interactions Between the Argininyl Moieties of Neurotensin and the Catechol Protons of Dopamine

The interaction between dopamine and neurotensin as well as other Arg-containing peptides was studied to provide more chemical details of how dopamine binds to the neuropeptide neurotensin. The stoichiometry of 1:1, dopamine to neurotensin, was confirmed by additional electroanalytical and ultraviolet-visible spectroscopic studies. By analyses of the 205- to 340-nm difference spectra of fixed concentrations of dopamine in the presence of increasing amounts of neurotensin, the dissociation constant of the interaction was found to be 5.9 x 10(-8) mol/L. This finding confirmed (by a second physical method) the previously reported KD value obtained by electroanalytical techniques. The associations between dopamine and neurotensin as well as the neurotensin fragment Pro7-Arg8-Arg9-Pro10 were found to be pH dependent when the dissociation constant was measured as a function of pH (in 150 mmol/L NaCl). The results of studies of the formal potential of dopamine in the presence of Arg and Arg-containing peptides confirmed that catechol protons are directly involved in the association and that the chemical species of dopamine associated with neurotensin is a catecholate form. The (pseudo)-first-order rate constant of dissociation of the complex at pH 7.6, measured by the chronoamperometric and rotating disk electroanalytical techniques, was found to be approximately 10(5) s-1, indicating that the rate of formation of the complex is under diffusion control. A hypothetical chemical structure of the neurotensin-dopamine complex is suggested.     

竹红菌光敏作用的初步探讨*

用纸片法作为筛选光敏物质及光敏作用的研究方法。结果证实了(1)竹红菌Hypo crella bambusae中含有对革兰氏阳性细菌具光敏活性的成分;(2)从中筛选到一种红色的光敏色素,属苝醌的一个新的衍生物,取名竹红菌甲素(Hypocrellin A简称“甲素”);(3)揭示了“甲素”是对可见光敏感、作用光谱较宽的光动力学(photodynamic)物质。从化合物的类型、光敏特性、治疗方法、治疗对象及其效果看,可以认为甲素是一新型的光化学疗法药物。     

竹红菌光敏作用的初步探讨

用纸片法作为筛选光敏物质及光敏作用的研究方法。结果证实了(1)竹红菌Hypo crella bambusae中含有对革兰氏阳性细菌具光敏活性的成分;(2)从中筛选到一种红色的光敏色素,属苝醌的一个新的衍生物,取名竹红菌甲素(Hypocrellin A简称“甲素”);(3)揭示了“甲素”是对可见光敏感、作用光谱较宽的光动力学(photodynamic)物质。从化合物的类型、光敏特性、治疗方法、治疗对象及其效果看,可以认为甲素是一新型的光化学疗法药物。     

Composition,ultrastructure and function of the cutin- and suberin-containing layers in the leaf,fruit peel,juice-sac and inner seed coat of grapefruit (Citrus paradisi Macfed.)

Cutin and suberin polymers from various anatomical regions of grapefruit were analyzed chemically and ultrastructurally. The leaf, fruit peel and juice-sac showed an amorphous cuticular layer. The cutin in the leaf was composed of 10,16-dihydroxy C₁₆ acid and its positional isomers as the major monomers whereas 16-hydroxy-10-oxo C₁₆ acid was a major component in the fruit peel. Juice-sac cutin, on the other hand, contained the dihydroxy C₁₆ acids, hydroxyoxo C₁₆ acids, hydroxyepoxy C₁₈ acids and trihydroxy C₁₈ acids. Ultrastructural examination of the inner seed coat showed that an amorphous cuticular layer encircled the entire seed except in the chalazal region which showed several layers of cells with lamellar suberin structure throughout the cell walls. Consistent with the ultrastructural assignment, the compositions of the aliphatic components of the polymers from the chalazal region and the non-chalazal region indicated the presence of suberin and cutin, respectively. The aliphatic portion of the polymer from the chalazal region of the inner seed coat contained C₁₆, C_18:1, C₂₂ and C₂₄ -hydroxy acids (46% combined total) and the corresponding dicarboxylic acids (43%) as the major components. -Hydroxy-9,10-epoxy C₁₈ acids and 9,10,18-trihydroxy C₁₈ acids were the major components (77%) of the polymer from the non-chalazal portion of the inner seed coat. The main portion and the chalazal region of the inner seed coat yielded 17 and 342 g/cm² of aliphatic monomers, respectively, and the diffusion resistance of these two portions of the inner seed coat were 62 and 192 sec/cm, respectively. The inner seed coat was shown to be the major moisture diffusion barrier influencing imbibition and germination.Scientific Paper No. 5649, Project 2001, College of Agriculture Research Center, Washington State University, Pullman, Washington 99164     

Histological and ultrastructural studies of the basal disk of Hydra

Summary The gastrodermis and mesoglea of the basal disk of Hydra were investigated to conclude a three-part series of papers. The gastrodermis is composed of digestive cells (most predominant cell type), mucous and nerve cells (both immature and fully differentiated). The principal function of the digestive cells appears to be storage of protein, lipid and glycogen reserves which are utilized by neighboring cells. Mucous cells apparently use some of the reserves to synthesize their secretions which lubricate cells and prevent cell damage during egestion of waste through the aboral pore. The function of the gastrodermal nerve cells is uncertain.The mesoglea of the basal disk, contains the same structural components as seen in other regions of the polyp. It is reasonable to assume that it maintains the same function of cell adhesion and migration. As the mesoglea converges on the aboral pore, it loses its structural integrity and cells are sloughed off the column.This investigation was supported by The National Science Foundation, Grant Number GB-27395.