Isolation of F-actin from pea stems

Summary A procedure is introduced which allows the isolation of abundant amounts of F-actin from plants (etiolated pea seedlings) in an array of morphologies very similar to the array of morphologies found in situ. The major feature is a homogenizing medium containing very low ionic strength, low monovalent ion (K⁺) concentration, a 3-fold higher level of Mg^{+ +}, the presence of EGTA to chelate Ca⁺⁺, and PMSF to inhibit protease activity. Using this buffer, about 80–90% of the sedimentable actin is found in the low speed (4,000×g) pellet.Abbreviations CSB cytoskeleton-isolation buffer - DTE dithioery-thritol - EGTA ethylene-glycol-bis(B-aminoethyl ether) N,N,NN-tetraacetic acid - EPPS N-[2-hydroxyethyl]-piperazine-N-[3-propane-sulfonic acid] - HEPES N-[hydroxyethyl]-piperazine-N-[2-ethanesulfonic acid] - MFSB microfilament-stabilizing buffer - PIPES piperazine-N,N-bis[2-ethanesulfonic acid] - PMSF phenylmethyl-sulfonyl fluoride - PTE polyoxyethylene-10-tridecyl ether - TRIS tris-(hydroxymethyl) aminoethane     

Isolation of mutants of the cyanobacterium,Anabaena variabilis,impaired in photoautotrophy

Mutants ofAnabaena variabilis Kütz. that have a decreased ability to grow photoautotrophically have been isolated by a modification of the techniques used to isolate auxotrophic mutants of that filamentous cyanobacterium, and have been stably propagated. Three mutants have a reduced content of phycocyanin and, as determined by in situ assays of partial reaction sequences of photosynthesis, an impairment in photosystem II. Three other strains, all of which appear to have a normal complement of carotenoids when grown heterotrophically, are sensitive to light.Abbreviations Used TES N-tris(hydroxymethyl)-methyl-2-aminoethanesulfonic acid, sodium salt - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid, sodium salt - MV methylviologen - DBMIB 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone - DAB 3,3-diaminobenzidine - P-BQ p-benzoquinone - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - Fecy K-ferricyanide - NTG N-methyl-N-nitro-N-nitrosoguanidine     

Analysis of temperature dependence of cytoplasmic streaming using tonoplast-free cells of Characeae

Summary The temperature dependence of cytoplasmic streaming in intact and tonoplast-free cells ofNitellopsis obtusa was studied using a cryomicroscope. The streaming velocity decreases linearly with decrease in the temperature in well-buffered tonoplast-free cells but non-linearly in some intact cells. These results suggest that low temperature causes a disturbance in the homeostasis of calcium and protons, which inhibit cytoplasmic streaming in intact cells.Abbreviations ADP adenosine 5-diphosphate - APW artificial pond water - ATP adenosine 5-triphosphate - EGTA ethylene glycol-bis(-aminoethyl ether)N,N,N-tetraacetic acid - HEPES N-(2-hydroxyethyl)piperazine-N-(2-ethanesulfonic acid) - PIPES piperazine-N, N-bis(2-ethanesulfonic acid) - Tris tris(hydroxymethyl)aminoethane     

ATP and ADP contents in leaves of drying and rehydrating desiccation tolerant plants

Summary All species of desiccation tolerant angiosperms studied conserved some ATP in air-dry viable leaves. Otherwise there was no uniformity of response to drying: ATP content remained high in some species, but fell markedly in the others. ATP levels stayed high in Boea hygroscopica and Borya constricta until relative water content fell below 30%. ATP content recovered in the first 2 h of rehydration in Boea, but recovery was gradual in Borya, taking more than 16 h.Abbreviations ADP adenosine 5-diphosphate - ATP adenosine 5-triphosphate - BES N,N-bis[2-hydroxyethyl]-2-aminoethanesulfonic acid - HEPES N-2-hydroxyethylpiperazine-N¹-2-ethanesulfonic acid - RH relative humidity - RWC relative water content     

Perinuclear organization in the heterotrich ciliateStentor coeruleus

Summary Different fixation techniques were employed to obtain satisfactory fixation of the endoplasm ofStentor coeruleus for ultrastructural investigations. The nuclei ofS. coeruleus are surrounded by a flattened fenestrated cisterna. The space between the nuclear envelope and the cisterna (= perinuclear space) is continuous with the cytoplasm via channels. The envelopes of both, micronucleus and macronucleus, are connected to the fenestrated cisterna by filamentous material. This organization accounts for the close association between micronucleus and macronucleus inStentor coeruleus. The fenestrated cisterna is compared to similar structures occurring in other organisms, and its possible function is discussed.Abbreviations fC fenestrated cisterna - FV food vacuole - km km fibers - MaNu macronucleus - MiNu micronucleus - My myonome - NE nuclear envelope - PC perinuclear cisterna - PfC pore of fenestrated cisterna - PS perinuclear cytoplasmic space - EGTA ethyleneglycol-bis-(-aminoethylether)-N,N,N,N-tetraacetic acid) - GA glutaraldehyde - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - PEG polyethylene glycol - PIPES piperazine-N,N-bis[2-ethanesulfonic acid] - PTA phosphotungstic acid     

Immunolocalization of H+-ATPases in the plasma membrane of pollen grains and pollen tubes ofLilium longiflorum

Summary A heterogeneous distribution of H⁺-ATPase was visualized in germinated pollen ofLilium longiflorum using monoclonal antibodies raised against plasma membrane H⁺-ATPase. Immunolocalization studies of protoplasts and subprotoplasts derived from pollen tubes and sectioned pollen grains and pollen tubes show that H⁺-ATPases are abundant in the plasma membrane of pollen grains but are absent or sparsely distributed in the plasma membrane of pollen tubes. This polar distribution of H⁺-ATPases is probably the basis of the endogenous current pattern measured in growing lily pollen and involved in pollen tube tip growth.Abbreviations BSA bovine serum albumine - Hepes N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - Mes 2-(N-morpholino)-ethane sulphonic acid - PBS phosphate buffered saline - Pipes piperazine-N,N-bis(2-ethanesulfonic acid) - Tris 2-amino-2-hydroxymethyl-1,3-propandiol     

Photosensory transduction in the flagellated alga,Euglena gracilis

Euglena were cultured under 3 W m^-2 constant white light. In culture medium, cells show immediate and long lasting step-down photophobic responses and photoaccumulation behavior to blue light if dim red light-adapted for 30 min. However, if cells are suspended in buffered, saltcontaining solutions (adaptation buffers), strong step-down photobehavior and photoaccumulation responses are not observed for several hours. These behaviors gradually increase in strength to reach a maximum after 6–12 h; after which a stable response is maintained. The relative rates of appearance and the relative strengths of the responses are influenced by the concentrations of Ca²⁺ and K⁺, but not H⁺ or Na⁺ ions, in the adaptation buffers. Expression of the stepdown photobehavior thus requires that the cells adapt to the chemical environment in which they are suspended.Abbreviations Hepes N-2-hydroxypiperazine-N-2-ethanesulfonic acid - Mes 2(N-morpholino)-ethanesulfonic acid - Pipes piperazine-N,N-bis (2-ethanesulfonic acid) - Taps tris(hydroxymethyl) methylaminopropanesulfonic acid This work was supported, in part, by grant No. PCM-79-05320 from the U.S. National Science Foundation to B.D.     

Reductive activation of the methyl-tetrahydromethanopterin: coenzyme M methyltransferase from Methanobacterium thermoautotrophicum strain ΔH

The enzymatic conversion of formaldehyde to CH₃S-CoM in crude extracts of Methanobacterium thermoautotrophicum was used as a means to investigate the methyl-tetrahydromethanopterin: HS-CoM methyltransferase reaction. All components necessary for formaldehyde conversion were shown to be present in a soluble protein fraction. This soluble cell fraction still contained a major amount of corrinoids. Apart from tetrahydromethanopterin no other soluble cofactors were required for formaldehyde conversion. The dependence of the system on catalytic amounts of ATP was shown to be specific. Several nucleoside triphosphates or ADP were unable to substitute for ATP. Remarkably, various strong reducing systems, especially titanium(III)citrate could replace ATP to a large extent. The ATP-dependent formaldehyde conversion to CH₃S-CoM was inhibited in the presence of nitrous oxide, detergents or 2,3-dialdehyde-ATP. The results support a role for a corrinoid protein in the methyl-tetrahydromethanopterin: HS-CoM methyltransferase reaction at which ATP is involved in the activation of this protein, probably in the conversion of inactive B_12a or B_12r to active B_12s.Abbreviations HS-CoM Coenzyme M, 2-mercaptoethanesulfonate - CH₃S-CoM methylcoenzyme M, 2-(methylthio)ethanesulfonate - H₄MPT 5,6,7,8-tetrahydromethanopterin - BES 2-bromoethanesulfonate - BCE boiled cell-free extract - DTT dithiothreitol - TCS 3,3,4,5-tetrachlorosalicylanilide - DNTB 2,2-dinitro-5,5-dithiobenzoic acid - TES N-tris(hydroxymethyl)methyl-2-aminoethanesulfonate - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - PIPES piperazine-N,N-bis[2-ethanesulfonic acid] - AMP-PNP 5-adenylyl imidophosphate     

Transglutaminase catalyzed incorporation of putrescine into surface proteins of mouse neuroblastoma cells

Summary Transglutaminase, purified from guinea pig liver, was used to catalyze the incorporation of [¹⁴C]putrescine into exposed surface proteins of intact mouse neuroblastoma cells. This method specifically labeled two surface proteins (Mr = 92 000 and 76 000) in the N-18 mouse neuroblastoma cells and three surface proteins (Mr = 92 000, 76 000, and 72 000) in the NB-15 mouse neuroblastoma cells. In addition, transglutaminase also catalyzed cross-linking reactions of exposed surface proteins. In both the N-18 and NB-15 cells, differentiation was accompanied by a 2-fold increase of specific radioactivity incorporated into trichloroacetic acid insoluble cellular material, suggesting that the differentiated mouse neuroblastoma cells may possess greater amount of accessible peptide-bound glutaminyl residues on their surface than their malignant counterparts. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorographic method revealed that while the [¹⁴C]putrescine-labeled protein patterns of undifferentiated and differentiated mouse neuroblastoma cells were similar, the intensity of labeling of individual bands was specifically modulated by cell differentiation.Abbreviations PMSF phenylmethylsulfonylfluoride - Bt₂cAMP,N⁶,O² Dibutyryl adenosine 3:5-cyclic monophosphate - IBMX 3-isobutyl-l-methyl xanthine - SDSPAGE sodiumdodecylsulfate-polyacrylamide gel electrophoresis - HEPES N-2-hydroxylethylpiperazine-N-2-ethanesulfonic acid     

Nitro-blue tetrazolium: A specific stain for photosynthetic activity in protoplasts

A qualitative assay for the detection of photosynthetic activity in protoplasts is described. Leaf protoplasts from atrazine resistant and susceptible biotypes of Brassica napus suspended in medium with 0.01% nitro-blue tetrazolium and 10 to 100 µM atrazine showed clear differences in staining. Staining was detectable with 0.001% fluorescein-labelled tetrazolium which, unlike nitro-blue tetrazolium, did not cause collapse of the protoplasts.Abbreviations atrazine 2-chloro-4-(ethylamino)-6(isopropyl-amino)-s-triazine - DCPIP dichlorophenolindophenol - fluorescein-labelled tetrazolium 2,5-bis-(4-nitrophenyl)-3-(5-fluoresceinyl)-2H-tetrazolium chloride - Hepes N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - Mes 2-(N-morpholino)ethanesulfonic acid - nitro-blue tetrazolium 2,2,5,5-tetraphenyl-(3,3-dimethoxy-4,4-biphenylene)-ditetrazolium chloride - PS 0.6M sorbitol + 10mM NaHCO3 + 50mM Hepes, pH 7.6 - SM 0.5M sorbitol + 10mM Mes, pH 5.8 This work has been submitted by D. R. in partial fulfillment of the requirement for the Ph.D. degree     

Reactivity of cysteinyl, arginyl, and lysyl residues ofEscherichia coli phosphoenolpyruvate carboxykinase against group-specific chemical reagents

Calcium-activated phosphoenolpyruvate carboxykinase fromEscheria coli is not inactivated by a number of sulfhydryl-directed reagents [5,5-dithiobis(2-nitrobenzoate), iodoacetate, N-ethylmaleimide, N-(1-pyrenyl)maleimide or N-(iodoacetyl)-N-(5-sulfo-l-naphthylethylenediamine)], unlike phosphoenolpyruvate carboxykinase from other organisms. On the other hand, the enzyme is rapidly inactivated by the arginyl-directed reagents 2,3-butanedione and 1-pyrenylglyoxal. The substrates, ADP plus PEP in the presence of Mn²⁺, protect the enzyme against inactivation by the diones. Quantitation of pyrenylglyoxal incorporation indicates that complete inactivation correlates with the binding of one inactivator molecule per mole of enzyme. Chemical modification by pyridoxal 5-phosphate also produces inactivation of the enzyme, and the labeled protein shows a difference spectrum with a peak at 325 nm, characteristic of a pyridoxyl derivative of lysine. The inactivation by this reagent is also prevented by the substrates. Binding stoichiometries of 1.25 and 0.30mol of reagent incorporated per mole of enzyme were found in the absence and presence of substrates, respectively. The results suggest the presence of functional arginyl and lysyl residues in or near the active site of the enzyme, and indicate lack of reactive functional sulfhydryl groups.Abbreviations used: DTNB, 5,5-dithiobis(2-nitrobenzoate); Hepes, N-(2-hydroxyethyl)piperazine-N-2-ethanesulfonic acid; 1,5-IAEDANS, N-(iodoacetyl)-N-(5-sulfo-1-naphthyl) ethylenediamine; EPE, phosphoenolpyruvate; PEPCK, phosphoenolpyruvate carboxykinase; PG, 1-pyrenylglyoxal; PLP, pyridoxal 5-phosphate.     

Direct embryogenesis and green plant regeneration from isolated microspores of hexaploid triticale (× <Emphasis Type="Italic">Triticosecale</Emphasis> Wittmack) cv. Bogo

The use of doubled haploids improves the efficiency of cultivar development in many crops and can be helpful in genetic and molecular studies. The major problem with this approach is the low efficiency of green plant regeneration. We describe here an efficient method for inducing embryos and regenerating green plants directly from isolated microspores of hexaploid triticale (× Triticosecale Wittmack) cv. Bogo. The absence of growth regulators in the induction medium was the most effective condition for the formation of embryo-like structures. The highest induction rates were observed at microspore densities of 1.5×10⁵ microspores and 2×10⁵ microspores per milliliter. Such cultures produced an average of 54.9 green plants per single donor spike. The frequency of albino plants ranged from 9.3% to 22.9%. Among the green progeny tested, 30.8% were spontaneously doubled haploids.Abbreviations BAP Benzylaminopurine - DAPI 4-6 Diamidino-2-phenylindole - 2,4-D 2,4-Dichlorophenoxyacetic acid - NAA -Naphthaleneacetic acid     

Ca2+-induced fragmentation of actin filaments in pollen tubes

Summary To control the intracellular free Ca²⁺ concentration from the cell exterior, pollen tubes ofLilium longiflorum were treated with a Ca²⁺ ionophore, A23187. Cytoplasmic streaming was inhibited when the free Ca²⁺ concentration of the external medium ([Ca²⁺]) was raised to 5×10^–6 M or higher. At [Ca²⁺] below 1×10^–6 M, the rhodamine-phalloidin stained actin filaments appeared straight and thin. However, at [Ca²⁺] which inhibited cytoplasmic streaming, the actin filaments appeared fragmented. In pollen tubes, Ca²⁺ regulation of cytoplasmic streaming may be linked not only to myosin (Shimmen 1987) but also to actin.Abbreviations ATP adenosine-5-triphosphoric acid - [Ca²⁺] concentration of free Ca²⁺ - EGTA ethyleneglycol-bis-(-aminoethylether)N,N,N,N-tetraacetic acid - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - PIPES piperazine-N,N-bis(2-ethanesulfonic acid) - Rh-ph rhodamine-conjugated phalloidin     

Heterogeneous photosystem 2 activity in isolated spinach chloroplasts

A study was made of the fluorescence induction curves from gently-broken spinach chloroplasts inhibited with DCMU. It was found that there were four kinetically different phases associated with such curves of which only the fastest did not appear to follow exponential kinetics. A comparison of the effects of various concentrations of DCMU on the rate of oxygen evolution and on the fluorescence induction curve did not support the hypothesis that any of the kinetic phases was simply an artefact caused by incomplete inhibition of electron transport. It was also found that 5 min of dark incubation did not maximally oxidize the electron acceptors to photosystem 2 since some acceptors were only oxidized following far-red illumination, suggesting a heterogeneity among these acceptors with respect to their re-oxidation properties. Investigation of the effect of the Q₄₀₀ oxidation state on the fluorescence induction curve revealed that it only influenced the slowest kinetic phase and that Q₄₀₀ did not seem to be associated with the other phases.Abbreviations DCMU 3-(3,4-dichlorophenyl)-1 - 1 dimethylurea - PS 1 photosystem 1 - PS2 photosystem 2 - HEPES N-2-Hydroxyethylpiperazine-N-2-ethanesulfonic acid - EDTA ethylene-diaminetetraacetic acid - F_max maximum yield of fluorescence emission - F₀ initial yield of fluorescence emission - F_v variable yield of fluorescence emission - N.E. non-exponential kinetics     

An extrinsic marker for higher plant cell walls

Summary Cytochromec was ionically bound to cell walls as a useful extrinsic marker. The marker binds rapidly, can readily be removed by salt treatment, and can be quantitated by conventional spectrophotometric procedures. The use of the marker allows each step of a cell wall purification to be monitored qualitatively and, furthermore, it provides a rapid, simple quantitative method to determine the yield of purified cell walls once isolated from the cell.Abbreviations pI Isoelectric pH - EDTA Ethylenediaminetetra-acetic acid - kD kiloDaltons - Cytc Cytochrome c - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - MES 2(N-Morpholino)ethanesulfonic acid     

Parameters affecting attachment ofBacillus thuringiensis var.israelensis toxin to latex beads

Summary Bacillus thuringiensis var.israelensis protein toxin radiolabeled with¹⁴C-iodoacetamide was bound to latex beads. The efficiency of attachment was not affected by the temperature or length of incubation or by the presence of several different buffers, salts, or organic solvents. However, attachment decreased dramatically at pH values >8.5 or in the presence of detergents (anionic, neutral, or cationic). Protein concentrations 2–3 mg/m² of bead surface led to a progressively decreasing efficiency of protein adsorption. With minor variations, these findings should also be applicable to the attachment of numerous other proteins of diagnostic significance.Abbreviations BSA bovine serum albumin - Bti Bacillus thuringiensis var.israelensis - EDTA ethylenediaminetetraacetic acid - HEPES N-2-hydroxyethyl-piperazine-N-2-ethanesulfonic acid - LAT latex agglutination test - PAGE polyacrylamide gel electrophoresis - SDS sodium dodecylsulfate - TCA trichloroacetic acid - Tris Tris(hydroxymethyl)aminomethane - TTAB tetradecyltrimethylammonium bromide     

The role of Ca2+ in elicitation of phytoalexin synthesis in cell culture of onion (Allium cepa L.)

Summary Treatment of Allium cepa L. cellsuspension cultures with a biotic elicitor derived from the fungus Botrytis cinerea, resulted in phytoalexin synthesis. Two phytoalexins, 5-octylcyclopenta-1,3-dione and 5-hexyl-cyclopenta-1,3-dione, were accumulated in cultured onion cells. Removal of extracellular Ca²⁺ by the calcium chelator ethylene glycol bis(b-aminoethyl ether) N,N-tetraacetic acid abolished the elicitor-mediated phytoalexin synthesis. The calcium channel blockers, verapamil and 8-N,N-(dimethylamino)octyl-3,4,5-trimethoxybenzoate caused similar effects, whereas the addition of the Ca²⁺ ionophore A23187 enhanced the accumulation of phytoalexins in the absence of the elicitor. Increase in the cytoplasmic Ca²⁺ concentration in elicitor-treated onion cells was observed as monitored by the fluorescent calcium indicator indo-1. These observations suggest that Ca²⁺ acts as a second messenger in the regulation of phytoalexin synthesis in cultured onion cells.Abbreviations A23187 4-bromo-calcium ionophore - cAMP adenosine 3,5-cyclic monophosphate - [Ca²⁺]_cyt cytoplasmic Ca²⁺ concentration - EGTA ethylene glycol bis(b-aminoethyl ether) N,N-tetraacetic acid - EtOH ethanol - Et₂O diethyl ether - fr.wt fresh weight - HR hypersensitive response - PIPES piperazine N,N-bis-(2-ethanesulfonic acid) - TMB-8 [8-N,N-(dimethylamino)] octyl-3,4,5-trimethoxy-benzoate - Tsl tsibulin     

A co-culture system leads to the formation of microcalli derived from microspore protoplasts ofBrassica napus L. cv. Topas

Summary This paper describes a procedure in which protoplasts are obtained from microspores and pollen of rapeseed to induce callus formation aided by a feeder cell system with embryogenic microspores. Microspores at late unicellular stage and pollen at early bicellular stage were isolated and precultured for 24 h at 32 °C before enzymatic treatment. Eleven enzymes were tested in various combinations and concentrations. The optimal enzyme combination was 1.0% cellulase, 0.8% pectinase, 0.3% macerozyme, and 0.02% pectolyase, in which 26.3% of the microspores released protoplasts. A successful co-culture system was set up by employing embryogenic microspores as feeder cells. To this end, microspores were cultured in a medium with high osmotic pressure at 32 °C. Up to 37% of the microspores exhibited cell division and embryos developed to the heart-shape stage without changing medium. Microspore protoplasts were cultured in Millicells surrounded by the embryogenic microspores as feeder. In growth-regulator-free medium 14.5% of the protoplasts divided but only formed budding-like multicellular structures. Only after pretreatment with 4 mg of 2,4-dichlorophenoxyacetic acid and 1 mg of naphthaleneacetic acid per liter protoplasts divided and formed microcalli. Pollen tubes or tubelike structures were not observed. The experiments reveal that selection of the specific developmental stage of microspores, which is a prerequisite for microspore embryogenesis, is also important in microspore protoplast culture. Compared to other methods used before, microculture fed with embryogenic microspores has obvious superiority.Abbreviations CPW basic protoplast washing medium according to Power and Chapman - CPW972 CPW basic medium supplemented with 9% mannitol and 7.2% sorbitol - DAPI 4,6-diamidino-2-phenylindole - NLN nutrient medium according to Lichter modified by Pechan and Keller - NLN13 NLN medium supplemented with 13% sucrose - NLNP NLN13 supplemented with 7.2% sorbitol     

The polysaccharide structure of potato cell walls: Chemical fractionation

Cell walls of potato tubers were fractionated by successive extraction with various reagents. A slightly degraded pectic fraction with 77% galacturonic acid was extracted in hot, oxalate-citrate buffer at pH 4. A further, major pectic fraction with 38% galacturonic acid was extracted in cold 0.1 M Na₂CO₃ with little apparent degradation. These two pectic fractions together made up 52% of the cell wall. Most of the oxalate-citrate fraction could alternatively be extracted with cold acetate-N,N,N-tetracetic acid (CDTA) buffer, a non-degradative extractant which nevertheless removed essentially all the calcium ions. This fraction was therefore probably held only by calcium binding, and the remainder of the pectins by covalent bonds. Electrophoresis showed that both pectic fractions contained a range of molecular types differing in composition, with a high arabinose: galactose ratio as well as much galacturonic acid in the most extractable fractions. From methylation data, the main side-chains were 1,4-linked galactans and 1,5-linked arabinans, with smaller quantities of covalently attached xyloglucan. Extraction with NaOH-borate removed a small hemicellulose fraction and some cellulose. The main hemicelluloses were apparently a galactoxyloglucan, a mannan or glucomannan and an arabinogalactan.Abbreviations GLC gas-liquid chromatography - MS mass spectrometry - V₀ void volume - MW weight-average molecular weight - DMSO dimethylsulphoxide - EDTA ethylenediamine tetraacetic acid - TFA trifluoroacetic acid - CDTA N,N,N-tetraacetic acid     

The development of photosynthetic light reactions in cultured apple embryos in relation to their embryonal dormancy

The development of photosynthetic light reactions (photoreduction and photophosphorylation) was studied in cotyledons of cultured embryos isolated from stratified and non-stratified apple seeds (Malus domestica Borb. cv. Antonówka). The results obtained show the presence of an energy transfer inhibitor in the cotyledons of the stratified embryos.Abbreviations PSII photosystem II - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - ATP adenosine triphosphate - ADP adenosine diphosphate - CCCP carbonyl cyanide m-chlorophenyl-hydrazone - EDTA ethylenediamine tetraacetic acid; P, inorganic orthophosphate - TES (N-tris [hydroxymethyl] methyl-2-aminoethane sulfonic acid) This work was partly supported by the Polish Academy of Sciences, Contract No 10.2.10