Breakdown of phosphatidylinositol in soybean callus

We have investigated the breakdown of membrane-bound phosphatidylinositol (PI) in homogenates of soybean (Glycine max) callus. The breakdown of PI was stimulated by the detergent deoxycholate. At pH 7.0 and 1·gl^-1 of deoxycholate the loss of PI was rapid and extensive: more than 80% was broken down within 10 min. The breakdown of PI was also stimulated by millimolar concentrations of Ca²⁺. The products of breakdown of added PI (purified from soybean callus) in this system were identified from their chromatographic mobilities as 1,2-diacylglycerol, myo-inositol 1-phosphate and myo-inositol 1:2-cyclic monophosphate.Abbreviations DOC deoxycholate - EDTA ethylenedi-aminetetraacetic acid,-acetate - Pi Inorganic phosphate - PI phosphatidylinositol - PS phosphatidylserine - TLC thinlayer chromatography     

Isolation of a copper complex and its rate of appearance in roots of Mimulus guttatus

A Cu-complex was isolated from the roots of copper-tolerant Mimulus guttatus. The elution volume of the complex determined by gel permeation chromatography was similar to that of rat-liver cadmium thionein. The complex was heat stable, had a relatively high ratio of absorbance at 254 nm: 280 nm and incorporated ³⁵S. The complex, purified using a combination of gel permeation chromatography and anion-exchange chromatography, contained more glutamine/glutamic acid and glycine residues than mammalian metallothioneins. The amount of the complex in roots increased after 5 h growth in a solution containing 16 M Cu. Induction was preceded by an increase in the concentrations in root tissue of unknown compounds containing sulphur which may serve as precursors. The availability of these compounds appeared to regulate the rate of synthesis of this Cu-complex.Abbreviations CuBP copper-binding protein - HPLC highperformance liquid chromatography - MT metallothionein - Th thionein - Tris 2-amino-2-(hydroxymethyl)1-3-propanediol     

The cytoskeleton of Cobaea seed hairs:

The cell wall of Cobaea scandens seed hairs developed in a characteristic sequence, with the deposition of a cellulose thread onto a pectic swelling layer was the final event. The cellulose thread was intracellularly accompanied by a band of 10–18 microtubules. During the formation of the swelling layer the microtubules were homogeneously distributed; they ran circumferentially normal to the cell axis. When cellulose-thread formation started, the microtubules became arranged in a helical band. The density of the microtubules varied during the different phases of development. The highest density was observed before cellulosethread formation and ranged from 6–15 m·m^-2. The length of the microtubules, 20–30 m, was determined by direct measurements, as well as estimated from the total microtubular length in a given area and the counted free ends. With the indirect immunofluorescence technique the microtubules of the band stained inhomogeneously. Those which were located at the edges of the band fluoresced more intensely than those of the central part. Attempts to visualize actin filaments in the hair cells with rhodaminyl-conjugated phalloidin resulted in a homogeneous staining of the area of the microtubular band, indicating that actin filaments may be present in this region. Though, in thin sections and dry-cleaved cells, filamentous structures were observed between the microtubules, caution is expressed that the observed fluorescence was, indeed, due to actin filaments. The role of the filamentous structures is discussed with respect to formation and maintenance of the microtubular band. Microtubules apparently did not cross coated pits which were visualized in the plasma membrane through the dry-cleaving technique.Abbreviations IFT indirect immunofluorescence technique - RP rhodaminyl-conjugated phalloidin - SEM scanning electron microscopy     

Protein inhibitors of microbial proteinases from wheat,rye and triticale

Specific protein inhibitors of microbial serine proteinases were isolated from wheat (Triticum aestivum L.), rye (Secale cereale L.) and triticale using affinity chromatography on subtilisin-Sepharose 4B. The wheat inhibitor had an isoelectric point (pI) at pH 7.2, while the rye inhibitor consisted of two forms with pI values of 6.8 and 7.1. In triticale, two components were present with pIs 7.2 and 6.8. All the inhibitors had M _r values of approx. 20 000. The isolated proteins were effective inhibitors of subtilisins Carlsberg and BPN, and of fungal proteinases (EC 3.4.21.14) from the genus Aspergillus, but they were completely inactive against trypsin (EC 3.4.21.4) chymotrypsin (EC 3.4.21.1) and pancreatic elastase (EC 3.4.21.36). The inhibitors formed complexes with subtilisin in a molar ratio of 1:1. The results of chemical modifications seem to indicate that the isolated inhibitors have methionine residues in their reactive sites.Abbreviation pI isoelectric point     

Stimulation of photosynthesis by 2% oxygen at low temperatures is restored by phosphate

The effect of phosphate feeding on the influence of low (2%) oxygen on photosynthetic carbon assimilation has been investigated in leaf discs of spinach (Spinacia oleracea L.) at 12°C. The following observations were made. First, after the transition from 20% O₂ to 2% O₂, the rate of CO₂ uptake was inhibited at CO₂ concentrations between about 250 and about 800 l CO₂·l^-1. Second, phosphate feeding stimulated the rate of CO₂ uptake in 20% O₂ at higher concentrations of CO₂ (500–900 l·l^-1). Third, phosphate feeding stimulated the rate of CO₂ uptake in 2% O₂ at all but the highest (900 l·l^-1) and lowest 74 (l·l^-1) concentrations of CO₂ employed. Phosphate thereby restored the stimulation of photosynthesis by 2% O₂ and it did so over a wide range of lower temperatures. Fourth, oscillatory behaviour, however generated, was dampened by phosphate feeding, even at very low concentrations of CO₂. Contents of leaf metabolites were measured during the transition to 2% O₂ in control and phosphate-fed leaf discs. During this period the ratio glycerate-3-phosphate/triose phosphate rose steeply, but fell again only in the phosphate-treated leaf discs. These data, taken together with measured ATP/ADP ratios, showed that assimilatory power, the ratio [ATP]·[NAD(P)H]/[ADP]·[Pi]·[NAD(P)], decreased when leaves were exposed to 2% O₂, but that this decrease was minimised by previous feeding of phosphate. The mechanism of phosphate limitation is discussed in the light of the results.Abbreviations C_i intercellular concentration of CO₂ - RuBP ribulose-1,5-bisphosphate     

Ethylene production and β-cyanoalanine synthase activity in carnation flowers

The relationship between ethylene production and the CN^--assimilating enzyme -cyanoalanine synthase (CAS; EC 4.4.1.9) was examined in the carnation (Dianthus caryophyllus L.) flower. In petals from cut flowers aged naturally or treated with ethylene to accelerate senescence the several hundred-fold increase in ethylene production which occurred during irreversible wilting was accompanied by a one- to twofold increase in CAS activity. The basal parts of the petal, which produced the most ethylene, had the highest CAS activity. Studies of flower parts (styles, ovaries, receptacles, petals) showed that the styles had a high level of CAS together with the ethylene-forming enzyme (EFE) system for converting 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene. The close association between CAS and EFE found in styles could also be observed in detached petals after induction by ACC or ethylene. Treatment of the cut flowers with cycloheximide reduced synthesis of CAS and EFE. The data indicate that CAS and ethylene production are associated, and are discussed in relation to the hypothesis that CN^- is formed during the conversion of ACC to ethylene.Abbreviations ACC 1-aminocyclopropane-1-carboxylic acid - AVG aminoethoxyvinylglyoine - CAS -cyanoalanine synthase - CHI cycloheximide - EFE ethylene-forming enzyme     

二十三种药用种子(或果实)中油的化学组成

本文报道了二十三种药用种子(或果实)的含油率和油的化学组成成分,它们分属于二十个科二十二个属中。本文所发表的大部分资料尚未见国内外文献的报道。     

The relationship between NADPH-dependent lipid peroxidation and degradation of cytochrome P-450 in adrenal cortex mitochondria

The relationship between NADPH-dependent lipid peroxidation and the degradation of cytochrome P-450 has been studied in bovine adrenal cortex mitochondria. Malondialdehyde formation is accompanied by a corresponding decrease in total cytochrome P-450 content. Inhibitors of lipid peroxidation also prevent the loss of cytochrome P-450, further demonstrating a direct relationship between NADPH-dependent lipid peroxidation and degradation of P-450. To differentiate between cytochrome P-450(11)beta and P-450scc, steroid-induced difference spectra were used to evaluate P-450 degradation. These measurements provide the first evidence that both P-450's are degraded during NADPH-dependent lipid peroxidation with P-450(11)beta being much more susceptible to this process.     

Isolation of an iC3b forming enzyme from peritoneal polymorphonuclear leukocytes of guinea pigs

We have investigated fluid phase cleavage of C3b by peritoneal polymorphonuclear leukocytes of guinea pigs and found that polymorphonuclear leukocytes expressed an iC3b forming enzyme as well as C3b receptor with maturation in peritoneal cavity. The iC3b forming enzyme was found to be distinct from C3bINA, a physiological iC3b forming enzyme in plasma, since the activity was inhibited by monoiodoacetic acid and did not require a cofactor plasma protein, beta 1H, for the cleavage of C3b into iC3b. The iC3b forming enzyme is gradually released upon incubation of PMN at 37 degrees C. The molecular weight of the iC3b forming enzyme was estimated to be 48,000 from gel filtration on Sephadex G-200.     

Cyclic nucleotide phosphodiesterases in larval brain of wild type and dunce mutant strains of Drosophila melanogaster: isoenzyme pattern and activation by Ca2+/calmodulin

Like adult heads and whole flies, larval brains of wild type Drosophila melanogaster contain two major soluble cyclic nucleotide phosphodiesterases, forms I and II. Larval brains of the learning-defective mutant strain, dunceM11, contain only the form I enzyme. In both wild type and dunce strains the form I enzyme is activated by Ca2+/calmodulin. A time-dependent loss of this Ca2+ activation was observed.