摘要:

A membrane fraction enriched in plasma membrane and tonoplast vesicles was isolated from green leaves ofSpinacia oleraceaL. and subjected to subfractionation by free‐flow electrophoresis. The most electronegative membrane vesicle fraction collected after the free‐flow electrophoretic separation was identified as derived from tonoplast, while the least electronegative fraction was identified as derived from plasma membrane. The identification of the fractions was based on membrane morphology, and on the presence or absence of biochemical markers. The plasma membrane fraction was enriched in thick (9–11 nm) membranes which bound N‐1‐naphthylphthalamic acid (NPA), and reacted with phosphotungstic acid at low pH on thin sections for electron microscopy. The tonoplast fraction was enriched in vesicles with 7–9 nm thick membranes that neither bound NPA nor reacted with phosphotungstic acid at low pH. Both the plasma membrane and the tonoplast fraction were about 90% pure, with a cross‐contamination of not more than 2%. Membrane vesicles originating from dictyosomes, endoplasmic reticulum, mitochondria, plastids, or peroxisomes contaminated the plasma membrane and the tonoplast fractions by a few % only. In leaves of photoinduced plants (24 h light period), the plasma membranes were thicker than in control leaves (8 h light, 16 h dark). The plasma membrane fraction obtained from photo‐induced leaves by free‐flow electrophoresis retained this increase in thickness, showing not only that photoinduction alters plasma membrane structure, but also that this change is st

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb06588.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Twenty cultivars of barley and 15eceriferummutants from one of the cultivars have been analysed for cuticular transpiration and epicuticular lipids of their primary leaves. The relative cuticular transpiration rates of the cultivars ranged from 0.61 to 1.98. In spite of this variation in transpiration most of the cultivars had almost the same amount of epicuticular lipids per leaf area, about 16 μg cm−2. Theeceriferummutants showed a wider range in amount of epicuticular lipids, from 5.0 to 15.5 μg cm−2. Nevertheless, most of the mutants transpired almost at the same rate. Only a weak correlation was found between cuticular transpiration and total amount of epicuticular lipids. None of the analysed lipid components (alkanes, aldehydes, primary alcohols, esters or fatty acids) was better correlated to the cuticular transpiration than the total amount of lipids. When the cultivars were exposed to a mild water stress their cuticular transpiration rates decreased by about 11%. This reduction was not accompanied by any corresponding increase in total amount of epicuticular lipids. The most pronounced effect of the water stress treatment was a stimulation in the ester formation and a reduced formation of primary alcohols. This shift in lipid composition could not be correlated to the decreased cuticular transpiration rates of the individual cultivars. From this investigation it is concluded that the cuticular transpiration is poorly correlated to the amount or composition of the epicuticular lipids in this barley material. As a consequence it was not possible to use any characteristic of the epicuticular lipids as a selection criterion in breeding for drought resis

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb06589.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Ca2+‐ and Mg2+‐dependent ATPase activity (EC 3.6.1.3) in a plasma membrane‐enriched fraction increased rapidly after in vivo application of physiologically active concentrations of triacontanol (TRIA) to the roots of barley (Hordeum vulgareL. cv. Conquest) seedlings. Ca2+‐ and Mg2+‐dependent ATPase activity was 64 and 85% higher, respectively, in the roots of seedlings germinated in the presence of growth‐promoting concentrations of TRIA compared to controls. The increase in vivo was concentration dependent, with the greatest increase obtained at 2.3 nMTRIA. Maximal stimulation of ATPase activity of excised tissue treated with TRIA coincided with the temperature at which the barley was grown. At this temperature the plasma membrane is primarily in a mixed gel/liquid crystalline state. Pretreatment of barley roots with cyclohexamide did not alter ATPase stimulation by TRIA. Two to three times more [14C]‐TRIA (mg membrane protein)−1was found associated with plasma membrane‐enriched vesicles treated with TRIA than with vesicles enriched for mitochondrial membranes or for vesicles enriched for tonoplast, Golgi and rough endoplasmic reticulum. Both Ca2+‐ and Mg2+‐dependent ATPase activity increased by 40–60% within 30 min of the addition of 2.3 nMTRIA to cell‐free extracts of barley roots. The addition of octacosanol, the C28analogue of TRIA, to cell‐free extracts did not affect metal‐dependent ATPase activity. Consistent with many studies in the green‐house, simultaneous additions of equimolar amounts of TRIA and octacosanol to cell‐free extracts resulted in inhibition of ATPase stimulation by TRIA. TRIA may directly affect plasma

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb06590.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The induction of secondary dormancy in caryopses of genetically pure dormant lines ofAvena fatuaL. is described. Seeds harvested from mature plants were after‐ripened under controlled conditions (26°C, 25% relative humidity) until fully non‐dormant. Secondary dormancy was then induced into these caryopses by incubation on moist filter papers in an aspirated nitrogen atmosphere at 20°C over periods from 3 h to 14 days. These caryopses failed to germinate when returned to an aerobic environment. The dose‐response curves for gibberellic acid, sodium azide, sodium nitrite, sodium nitrate and ethanol show that all of these treatments can overcome the induced secondary dormancy. Drying increased the sensitivity of secondary dormant caryopses to these treatments. These treatments overcame secondary dormancy at all times, indicating the presence of only one of the two known blocks to germination that exist during primary dormancy. Similarities between primary and secondary dormancy inA. fatuaare di

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb06591.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Cyanidium caldarium(Tilden) Geitler, a non‐vacuolate unicellular alga, resuspended in medium flushed with air enriched with 5% CO2, assimilated NH4+at high rates both in the light and in the dark. The assimilation of NO3−, by contrast, was inhibited by 63% in the dark. In cell suspensions flushed with CO2‐free air, NH4+assimilation decreased with time both in the light and in the dark and ceased almost completely after 90 min. The addition of CO2completely restored the capacity of the alga to assimilate NH4+. NO3−assimilation, by contrast, was 33% higher in the absence of CO2and was linear with time. It is suggested that NO3−and NH4+metabolism inC. caldariumare differently controlled in response to the light and carbon conditions of

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb06592.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Grains of wheat (Triticum aestivumL. cv. Starke II) were treated with SAN‐9789 (Norflurazon), and grown in darkness for 6 days. The SAN treatment resulted in an inhibition of the carotenoid synthesis at the level of phytoene. The plastids of SAN‐treated plants contained enlarged and non‐osmiophilic plastoglobuli, compared to the plastoglobuli of the control. The plastoglobuli were isolated and purified by means of a flotation technique, and their lipid composition was determined. Efforts were made to avoid contamination of epicuticular soluble lipids in the plastoglobuli suspension during isolation. The most suitable method was found to be a mechanical removal of the lipids from the surface of the intact leaves prior to homogenization. Membrane lipids, i.e. galacto‐, phospho‐ and sulpholipids could not be detected in plastoglobuli from either SAN‐treated or control plants, indicating that contamination with membranes was negligible. In plastoglobuli of SAN‐treated plants, large amounts of phytoene and, to a lesser extent, phytofluene accumulated. The proportion of triacylglycerols to quinones was lower than in the control. The main lipids in control plastoglobuli were triacylglycerols, plastoquinones and α‐tocopherol. The possible function of plastoglobuli in etiopla

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb06593.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Five glycosidase activities from cell homogenate of carrot (Daucus carotaL. cv. Kintoki) cell cultures were assayed after extraction successively by phosphate buffer (pH 7.0) and the buffer plus 2MNaCl. A β‐galactosidase (EC 3.2.1.23) was isolated in a highly purified state from the buffer‐soluble protein fraction by ammonium sulfate fractionation and chromatography on CM‐Sephadex C‐50, DEAE‐Sephadex A‐50 and Sephadex G‐200. The molecular weight of this enzyme was ca 104 000 and the isoelectric point was pH 7.8. The optimal activity occurred at pH 4.4 with McIlvaine buffer. The Kmand Vmaxvalues were 1.67 mMand 201 units (mg protein)−1, respectively, forp‐nitrophenyl β‐d‐galactopyranoside. The enzyme activity was strongly inhibited by Zn2+, Cu2+, Hg2+andd‐galactono‐1,4‐lactone. The enzyme acted on the β‐1,4‐linked galactan prepared from citrus pectin in an exo‐fashion. Furthermore, the enzyme was slightly involved in the hydrolysis of the pectic polymer and cell wall

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb06594.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Rape seedlings (Brassica napusL. cv. Brink) were exposed to repeated water‐deficit stress. The water‐stress program started after 19 days of growth and consisted of three 24 h stress periods interspersed with 24 h rewatering periods. After the third stress period the seedlings were harvested and the membrane lipids of the roots were extracted, isolated and quantified. The stress caused an increased ratio of dry weight roots/shoot. Furthermore, the total amount of acyl lipids as well as phospholipids decreased drastically. However, the relative distribution of individual phospholipids was constant and independent of stress. Free and esterified sterols showed only a small decrease in response to water stress. As a consequence the ratio free sterols/phospholipids increased from 0.07 in the control root cells to 0.15 in the stressed cells. The lipid changes are discussed in relation to membrane activ

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb06595.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Plasmalemma vesicles were purified from 7‐day‐old wheat (Triticum aestivumL. cv. Drabant) roots by a) discontinuous sucrose gradient (SG), b) aqueous polymer two‐phase partitioning (PP) and c) SG followed by PP (SG + PP). SG‐purified plasmalemma preparations were 2‐3 fold more contaminated with mitochondria (cytochrome c oxidase, EC 1.9.3.1) when compared to PP and (SG + PP)‐purified plasmalemma. The electrostatic surface properties, as measured by 9‐aminoacridine fluorescence, were similar in PP and (SG + PP)‐purified plasmalemma and different from SG‐purified. The latency of the MG‐ATPase measured with Triton X‐100 was 51, 81 and 82% for SG‐, PP‐ and (SG + PP)‐purified plasmalemma vesicles, respectively. The higher latency of the ATPase (and lower specific activity in the absence of Triton X‐100) in PP‐purified and (SG + PP)‐purified preparations was not due to an effect of PEG, since exposure of SG‐purified preparations to PEG either in the wash medium or in the ATPase assay medium did not change ATPase activity. It is concluded that SG‐purified plasmalemma vesicles are more contaminated than PP‐purified preparations and that the former are likely to be leaky. They are, therefore, less suitable for use in stud

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb06596.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Purified, right side‐out plasmalemma vesicles were isolated from 7‐day‐old roots of dark‐grown wheat (Triticum aestivumL. cv. Drabant) by aqueous polymer two‐phase partitioning. The oxygen consumption by these vesicles at pH 6.5 in the presence of 1 mMNADH [12–29 nmol (mg protein)−1min−1] was 66% inhibited by 1 mMKCN and ca 40% by 1 mMEDTA. It was unaffected by rotenone, antimycin A, carbonyl cyanide trifluoromethoxyphenylhydrazone (FCCP), mersalyl, chlorotetracycline + Ca2+, and EGTA. Salicylhydroxamic acid (SHAM) and its analogue,m‐chlorobenzhydroxamic acid, stimulated the rate of oxygen consumption 10–20 fold in the presence of 1 mMNAD(P)H with an apparent Km(SHAM) of ca 40 μM(with NADH). The dependence of O2consumption on NADH concentration in the presence of SHAM (2 mM) was sigmoidal, possibly due to endogenous catalase activity, and half‐maximal rate was obtained at 1.5 mM. In the absence of SHAM the rate increased with increasing acidity and no pH optimum was detectable between pH 4.5 and 8.5. In the presence of SHAM an optimum was observed at pH 6.5 and 0.8 mol of H2O2was produced for every 1 mol O2consumed. Endogenous catalase converted this H2O2to O2and after complete conversion the stoichiometry was 2 mol NADH consumed for every mol O3. SHAM was not consumed in the reaction. The possible involvement of a cytochrome P‐450

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb06597.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY