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determination of total sulfur in food samples by solid sampling high-resolution continuum source graphite furnace molecular absorption spectrometry.the determination of sulfur in food samples via the rotational molecular absorption of carbon monosulfide (cs) was performed using a solid sampling high-resolution continuum source electrothermal atomic absorption spectrophotometer (ss-hr-cs-etaas). in the presence of plenty of carbon in the graphite furnace as well as in food samples, cs was formed in the gas phase without the addition of any molecule forming element externally. the effects of the wavelength selected to detect cs, graphite furn ...201323635016
new experimental hosts of tobacco streak virus and absence of true seed transmission in leguminous hosts.of 70 plant species tested, 50 species were susceptible to tobacco streak virus (tsv) on sap inoculation. both localized (necrotic and chlorotic spots) and systemic (necrotic spots, axillary shoot proliferation, stunting, total necrosis and wilt) symptoms are observed by majority of plant species. eleven new experimental hosts were identified viz., amaranthus blitum var. oleracea (chaulai sag), celosia cristata (cocks comb), beta vulgaris var. bengalensis (palak/indian spinach), calendula offici ...201123637490
effect of inorganic and organic copper fertilizers on copper nutrition in spinacia oleracea and on labile copper in soil.to ensure an optimal concentration of cu in food crops, the effectiveness of eight liquid cu fertilizers was studied in a spinach ( spinacia oleracea l.) crop grown on cu-deficient soil under greenhouse conditions. plant dry matter yields, cu concentrations in spinach plants (total and morpholino acid (mes)- and ethylenediaminedisuccinic acid (edds)-extractable), and cu uptakes were studied. the behavior of cu in soil was evaluated by both single and sequential extraction procedures. the highest ...201323638953
major controlling factors and predictions for cadmium transfer from the soil into spinach plants.predicting the mobility, bioavailability and transfer of cadmium (cd) in the soil-plant system is of great importance with regards to food safety and environmental management. in this study, the transfer characteristics of cd (exogenous salts) from a wide range of chinese soils to spinach (spinacia oleracea l.) were investigated. the major controlling factors and prediction equations for cd transfer in the soil-plant system were also investigated. the results showed that plant cd concentration w ...201323642309
simple, rapid, and reliable detection of escherichia coli o26 using immunochromatography.shiga toxin-producing escherichia coli (stec) o26 has been increasingly associated with diarrheal disease all over the world. we developed an immunochromatographic (ic) strip for the rapid detection of e. coli o26 in food samples. to determine the specificity of the ic strip, pure cultures of 67 e. coli and 22 non-e. coli strains were tested with the ic strip. the ic strip could detect all (18 of 18) e. coli o26 strains tested and did not react with strains of any other e. coli serogroup or non- ...201323643115
protective role of a methanolic extract of spinach (spinacia oleracea l.) against pb toxicity in wheat (triticum aestivum l.) seedlings: beneficial effects for a plant of a nutraceutical used with animals.spinach extracts contain powerful natural antioxidants and have been used to improve the response of animal cells to various stress factors. the aim of the present study was to assess the effects of a methanolic extract of spinach (se) used at two concentrations (21.7 and 217 ppm) on the growth, certain enzymes and antioxidant systems in wheat seedlings under lead stress. when wheat seedlings were grown for 7 days in a solution containing pb(no3)2 (3 mm), germination and growth were impaired, wh ...201323645001
effect of metalloporphyrins on red autofluorescence from oral bacteria.the aim of this study was to assess the red autofluorescence from bacterial species related to dental caries and periodontitis in the presence of different nutrients in the growth medium. bacteria were grown anaerobically on tryptic soy agar (tsa) supplemented with nutrients, including magnesium-porphyrins from spinach and iron-porphyrins from heme. the autofluorescence was then assessed at 405 nm excitation. on the tsa without additives, no autofluorescence was observed from any of the species ...201323659237
nmr (¹h) analysis of crude extracts detects light stress in beta vulgaris and spinacia oleracea leaves.in highlight stress conditions, the mechanism of non-photochemical quenching (npq) of chlorophyll fluorescence is triggered at the chloroplast level. this process allows thermal quenching of the excessive excitation energy and it is strictly related to the efficiency of the xanthophyll cycle. nowadays, the utilization of the nuclear magnetic resonance (nmr) spectroscopy provides a powerful complementary way for the identification and quantitative analysis of plant metabolites either in vivo or i ...201323661197
generic escherichia coli contamination of spinach at the preharvest stage: effects of farm management and environmental factors.the objective of this study was to determine the effects of farm management and environmental factors on preharvest spinach contamination with generic escherichia coli as an indicator of fecal contamination. a repeated cross-sectional study was conducted by visiting spinach farms up to four times per growing season over a period of 2 years (2010 to 2011). spinach samples (n = 955) were collected from 12 spinach farms in colorado and texas as representative states of the western and southwestern ...201323666336
shiga toxin-producing escherichia coli in central greece: prevalence and virulence genes of o157:h7 and non-o157 in animal feces, vegetables, and humans.in greece, shiga toxin-producing escherichia coli (stec) have only been sporadically reported. the objective of this study was to estimate the prevalence of stec and escherichia coli o157:h7 in farm animals, vegetables, and humans in greece. a total number of 1,010 fecal samples were collected from farm animals (sheep, goats, cattle, chickens, pigs), 667 diarrheal samples from humans, and 60 from vegetables, which were cultured in specific media for stec isolates. enzyme-linked immunosorbent ass ...201323677425
differential sensitivity of spinach and amaranthus to enhanced uv-b at varying soil nutrient levels: association with gas exchange, uv-b-absorbing compounds and membrane damage.the metabolic reasons associated with differential sensitivity of c3 and c4 plant species to enhanced uv-b under varying soil nutrient levels are not well understood. in the present study, spinach (spinacia oleracea l. var all green), a c3 and amaranthus (amaranthus tricolor l. var pusa badi chaulai), a c4 plant were subjected to enhanced uv-b (280-315 nm; 7.2 kj m(-2) day(-1)) over ambient under varying soil nutrient levels. the nutrient amendments were recommended nitrogen (n), phosphorus (p), ...201323686471
mechanical and water barrier properties of agar/κ-carrageenan/konjac glucomannan ternary blend biohydrogel films.multicomponent hydrogel films composed of agar, κ-carrageenan, konjac glucomannan powder, and nanoclay (cloisite(®) 30b) were prepared and their mechanical and water barrier properties such as water vapor permeability (wvp), water contact angle (ca), water solubility (ws), water uptake ratio (wur), water vapor uptake ratio (wvur) were determined. mechanical, water vapor barrier, and water resistance properties of the ternary blend film exhibited middle range of individual component films, howeve ...201323688456
endogenous levels of nitrites and nitrates in wide consumption foodstuffs: results of five years of official controls and monitoring.the massive introduction of nitrogen fertilisers, necessary to maximise the global food production, has brought about an increase of the residual amounts of nitrites and nitrates in the products. notoriously, these compounds may exercise toxic effects. in this work the results obtained from 5years of official controls and monitoring focused on tracing quantifiable amounts of nitrites and nitrates in 1785 samples of meat, dairy, fish products and leafy vegetables are reported. a widespread presen ...201223692764
intergeneric recombination between a new, spinach-infecting curtovirus and a new geminivirus belonging to the genus becurtovirus: first new world exemplar.a novel curtovirus, spinach severe curly top virus (ssctv), was associated with symptomatic spinach plants collected from a commercial field in south-central arizona during 2009. in addition, a second viral molecule of about 2.9 kb from the same spinach plants was amplified, cloned and sequenced. the latter isolate, herein named spinach curly top arizona virus (sctav), was found to share 77 % pairwise sequence identity with beet curly top iran virus (bctiv), a leafhopper-transmitted geminivirus ...201323708296
flagella mediate attachment of enterotoxigenic escherichia coli to fresh salad leaves.enterotoxigenic escherichia coli (etec) causes child and travelers' diarrhea and is presumed to be water- and food-borne. sporadic outbreaks were traced to consumption of contaminated fresh produce, particularly salad leaves as lettuce and parsley. importantly, the mechanism by which etec binds salad leaves is not known. in this study we investigated the ability of clinical etec isolates to adhere to eruca vesicaria (commonly known as rocket). towards this end we inoculated pieces of cut e. vesi ...201123761239
hurdle enhancement of slightly acidic electrolyzed water antimicrobial efficacy on chinese cabbage, lettuce, sesame leaf and spinach using ultrasonication and water wash.slightly acidic electrolyzed water (saew) is well known as a good sanitizer against foodborne pathogens on fresh vegetables. however, microbial reductions from saew treatment are not enough to ensure produce safety. therefore, it is necessary to improve its antimicrobial efficiency by combining it with other appropriate approaches. this study examined the microbicidal activity of saew (ph 5.2-5.5, oxidation reduction potential 500-600 mv, available chlorine concentration 21-22 mg/l) on chinese c ...201323764218
comparative evaluation of the vidas listeria monocytogenes xpress (lmx) for the detection of listeria monocytogenes in a variety of foods.the vidas listeria monocytogenes xpress (lmx) test is an enzyme-linked fluorescent immunoassay designed for use with the automated vidas or mini-vidas instruments for the specific detection of l. monocytogenes using a 26 h proprietary enrichment broth. the vidas lmx method was validated according to harmonized aoac research institute (ri) and official methods of analysis guidelines in both the aoac performance tested method (ptm) and govval programs. in the ptm comparison studies, the vidas lmx ...201323767344
evaluation of pathogenic escherichia coli occurrence in vegetable samples from district bazaars in istanbul using real-time pcr.in this study, a total of 180 vegetable samples collected from several district bazaars of istanbul were investigated for the occurrence of escherichia coli using a culture-based method. the isolates were subjected to real-time pcr detection of shiga-toxin-producing e. coli (stec) using primers specific for the shiga toxin (stx1 and stx2) and intimin (eae) virulence genes. the prevalences of e. coli in the samples were 93·3% in spinach, 93·3% in lettuce, 86·6% in parsley, 43·3% in carrot, 33·3% ...201323789811
in vitro digestion/caco-2 cell model to estimate cadmium and lead bioaccessibility/bioavailability in two vegetables: the influence of cooking and additives.the estimation of heavy metal bioaccessibility and bioavailability in vegetables is helpful for human health risk assessment. using an in vitro digestion/caco-2 cell model, the bioaccessibility and bioavailability of cadmium (cd) and lead (pb) in raw/cooked pakchoi (brassica rapa l., chinensis group) and malabar spinach (basella rubra l.) were studied. the effect of the addition of iron, calcium and acetic acid to the samples was also determined. the results indicated that cd bioaccessibility wa ...201323791752
mercury increases water permeability of a plant aquaporin through a non-cysteine-related mechanism.water transport across cellular membranes is mediated by a family of membrane proteins known as aqps (aquaporins). aqps were first discovered on the basis of their ability to be inhibited by mercurial compounds, an experiment which has followed the aqp field ever since. although mercury inhibition is most common, many aqps are mercury insensitive. in plants, regulation of aqps is important in order to cope with environmental changes. plant plasma membrane aqps are known to be gated by phosphoryl ...201323819815
summer (subarctic) versus winter (subtropic) production affects spinach (spinacia oleracea l.) leaf bionutrients: vitamins (c, e, folate, k1, provitamin a), lutein, phenolics, and antioxidants.comparison of spinach (spinacia oleracea l.) cultivars lazio and samish grown during the summer solstice in the subarctic versus the winter solstice in the subtropics provided insight into interactions between production environment (light intensity), cultivar, and leaf age/maturity/position affecting bionutrient concentrations of vitamins (c, e, folate, k1, provitamin a), lutein, phenolics, and antioxidants. growing spinach during the winter solstice in the subtropics resulted in increased leaf ...201323834651
evaluation of models describing the growth of nalidixic acid-resistant e. coli o157:h7 in blanched spinach and iceberg lettuce as a function of temperature.the aim of this study was to model the growth of nalidixic acid-resistant e. coli o157:h7 (e. coli o157:h7nr) in blanched spinach and to evaluate model performance with an independent set of data for interpolation (8.5, 13, 15 and 27 °c) and for extrapolation (broth and fresh-cut iceberg lettuce) using the ratio method and the acceptable prediction zone method. the lag time (lt), specific growth rate (sgr) and maximum population density (mpd) obtained from each primary model were modeled as a fu ...201323839062
diversity of the spinach (spinacia oleracea) spermosphere and phyllosphere bacterial communities.the bacterial diversity of seeds, transmission of bacteria from seed to phyllosphere, and fate of seed-transmitted bacteria on mature plants are poorly characterized. understanding the dynamics of microbial communities is important for finding bio-control or mitigation strategies for human and plant pathogens. bacterial populations colonizing spermosphere and phyllosphere of spinach (spinacia oleracea) seedlings and plants were characterized using pyrosequencing of 16s rrna gene amplicons. spina ...201323859062
imaging bacterial protein expression using genetically encoded rna sensors.the difficulties in imaging the dynamics of protein expression in live bacterial cells can be overcome by using fluorescent sensors based on spinach, an rna that activates the fluorescence of a small-molecule fluorophore. these rnas selectively bind target proteins and exhibit fluorescence increases that enable protein expression to be imaged in living escherichia coli. these sensors are key components of a generalizable strategy to image protein expression in a single bacterium in real time.201323872791
antibacterial and herbicidal activity of ring-substituted 3-hydroxynaphthalene-2-carboxanilides.in this study, a series of twenty-two ring-substituted 3-hydroxy-n-phenylnaphthalene-2-carboxanilides were prepared and characterized. the compounds were tested for their activity related to inhibition of photosynthetic electron transport (pet) in spinach (spinacia oleracea l.) chloroplasts. primary in vitro screening of the synthesized compounds was also performed against four staphylococcus strains and against two mycobacterial species. 3-hydroxy-n-(2-methoxyphenyl)naphthalene-2-carboxamide sh ...201323884130
molecular architecture of plant thylakoids under physiological and light stress conditions: a study of lipid-light-harvesting complex ii model membranes.in this study, we analyzed multibilayer lipid-protein membranes composed of the photosynthetic light-harvesting complex ii (lhcii; isolated from spinach [spinacia oleracea]) and the plant lipids monogalcatosyldiacylglycerol and digalactosyldiacylglycerol. two types of pigment-protein complexes were analyzed: those isolated from dark-adapted leaves (lhcii) and those from leaves preilluminated with high-intensity light (lhcii-hl). the lhcii-hl complexes were found to be partially phosphorylated an ...201323898030
the antimicrobial effects of cinnamon leaf oil against multi-drug resistant salmonella newport on organic leafy greens.there is generally no kill-step when preparing salad vegetables, so there is a greater risk for foodborne illness from contaminated vegetables. some essential oils have antimicrobial activities and could provide a natural way to reduce pathogens on fresh produce. the objective of this study was to investigate the antimicrobial activity of cinnamon oil wash against salmonella enterica serotype newport on organic leafy greens. organic romaine and iceberg lettuce, and organic baby and mature spinac ...201323911760
antibacterial and herbicidal activity of ring-substituted 2-hydroxynaphthalene-1-carboxanilides.in this study, a series of twenty-two ring-substituted 2-hydroxynaphthalene-1‑carboxanilides were prepared and characterized. primary in vitro screening of the synthesized compounds was performed against staphylococcus aureus, three methicillin-resistant s. aureus strains, mycobacterium marinum, m. kasasii, m. smegmatis. and m. avium paratuberculosis. the compounds were also tested for their activity related to inhibition of photosynthetic electron transport (pet) in spinach (spinacia oleracea l ...201323924993
changes and recovery of soil bacterial communities influenced by biological soil disinfestation as compared with chloropicrin-treatment.soil bacterial composition, as influenced by biological soil disinfestation (bsd) associated with biomass incorporation was investigated to observe the effects of the treatment on the changes and recovery of the microbial community in a commercial greenhouse setting. chloropicrin (cp) was also used for soil disinfestation to compare with the effects of bsd. the fusarium wilt disease incidence of spinach cultivated in the bsd- and cp-treated plots was reduced as compared with that in the untreate ...201323958081
effect of lead stress on mineral content and growth of wheat (triticum aestivum) and spinach (spinacia oleracea) seedlings.lead (pb) is the most common heavy metal contaminant in the environment. pb is not an essential element for plants, but they absorb it when it is present in their environment, especially in rural areas when the soil is polluted by automotive exhaust and in fields contaminated with fertilizers containing heavy metal impurities. to investigate lead effects on nutrient uptake and metabolism, two plant species, spinach (spinacia oleracea) and wheat (triticum aestivum), were grown under hydroponic co ...201323961216
multiplex taqman® detection of pathogenic and multi-drug resistant salmonella.overuse of antibiotics in the medical and animal industries is one of the major causes for the development of multi-drug-resistant (mdr) food pathogens that are often difficult to treat. in the past few years, higher incidences of outbreaks caused by mdr salmonella have been increasingly documented. the objective of this study was to develop a rapid multiplex real-time polymerase chain reaction (pcr) assay for simultaneous detection of pathogenic and mdr salmonella spp. a multiplex taqman®real-t ...201323973830
characterization of a potential listeria monocytogenes virulence factor associated with attachment to fresh produce.a study to determine the attachment of l. monocytogenes serotype 4b strain f2365 on vegetables and fruits was conducted. in an initial study, we screened 32 genes encoding surface proteins and lipases of the strain to find highly expressed genes on lettuce leaves. the results showed that transcription levels of lmof2365_0413, lmof2365_0498, lmof2365_0859, lmof2365_2052, and lmof2365_2812 were significantly upregulated on lettuce leaves. in silico analysis showed that lmof2365_0859 contains a put ...201323974144
photosynthetic electron transport system promotes synthesis of au-nanoparticles.in this communication, a novel, green, efficient and economically viable light mediated protocol for generation of au-nanoparticles using most vital organelle, chloroplasts, of the plant system is portrayed. thylakoids/chloroplasts isolated from potamogeton nodosus (an aquatic plant) and spinacia oleracea (a terrestrial plant) turned au³⁺ solutions purple in presence of light of 600 µmol m⁻² s⁻¹ photon flux density (pfd) and the purple coloration intensified with time. uv-vis spectra of these pu ...201323976990
understanding the cellular mechanism of recovery from freeze-thaw injury in spinach: possible role of aquaporins, heat shock proteins, dehydrin and antioxidant system.recovery from reversible freeze-thaw injury in plants is a critical component of ultimate frost survival. however, little is known about this aspect at the cellular level. to explore possible cellular mechanism(s) for post-thaw recovery (rec), we used spinacia oleracea l. cv. bloomsdale leaves to first determine the reversible freeze-thaw injury point. freeze (-4.5°c)-thaw-injured tissues (32% injury vs <3% in unfrozen control) fully recovered during post-thaw, as assessed by an ion leakage-base ...201423981077
cyanogenic glycosides in plant-based foods available in new zealand.cyanogenic glycosides occur in a wide range of plant species. the potential toxicity of cyanogenic glycosides arises from enzymatic degradation to produce hydrogen cyanide, which may result in acute cyanide poisoning and has also been implicated in the aetiology of several chronic diseases. one hundred retail foods were sampled and analysed for the presence of total hydrocyanic acid using an acid hydrolysis-isonicotinic/barbituric acid colourimetric method. food samples included cassava, bamboo ...201323984870
the spinach rna aptamer as a characterization tool for synthetic biology.characterization of genetic control elements is essential for the predictable engineering of synthetic biology systems. the current standard for in vivo characterization of control elements is through the use of fluorescent reporter proteins such as green fluorescent protein (gfp). gene expression, however, involves not only protein production but also the production of mrna. here, we present the use of the spinach aptamer sequence, an rna mimic of gfp, as a tool to characterize mrna expression ...201423991760
discovery and characterization of the first archaeal dihydromethanopterin reductase, an iron-sulfur flavoprotein from methanosarcina mazei.the microbial production of methane by methanogenic archaea is dependent on the synthesis of the pterin-containing cofactor tetrahydromethanopterin (h4mpt). the enzyme catalyzing the last step of h4mpt biosynthesis (dihydromethanopterin reductase) has not previously been identified in methane-producing microorganisms. previous complementation studies with the methylotrophic bacterium methylobacterium extorquens have indicated that an uncharacterized archaeal-flavoprotein-like flavoprotein (afpa) ...201423995635
prevalences of shiga toxin subtypes and selected other virulence factors among shiga-toxigenic escherichia coli strains isolated from fresh produce.shiga-toxigenic escherichia coli (stec) strains were isolated from a variety of fresh produce, but mostly from spinach, with an estimated prevalence rate of 0.5%. a panel of 132 produce stec strains were characterized for the presence of virulence and putative virulence factor genes and for shiga toxin subtypes. about 9% of the isolates were found to have the eae gene, which encodes the intimin binding protein, and most of these belonged to known pathogenic stec serotypes, such as o157:h7 and o2 ...201323995936
antimycobacterial and photosynthetic electron transport inhibiting activity of ring-substituted 4-arylamino-7-chloroquinolinium chlorides.in this study, a series of twenty-five ring-substituted 4-arylamino-7-chloroquinolinium chlorides were prepared and characterized. the compounds were tested for their activity related to inhibition of photosynthetic electron transport (pet) in spinach (spinacia oleracea l.) chloroplasts and also primary in vitro screening of the synthesized compounds was performed against mycobacterial species. 4-[(2-bromophenyl)amino]-7-chloroquinolinium chloride showed high biological activity against m. marin ...201324002140
[vitamin c in fruits and vegetables].strong opinion about reducing vitamin c content in traditional cultivars of fruits and vegetables as a result of intensive farming practices, on the one hand, and depletion of soil, waste of fertilizers, on the other hand, takes place. the aim of the study was to assess changes in vitamin c content in fresh vegetables, fruits and berries from the 40s of last century to the present. available national and foreign data from official tables of the chemical composition tables published in different ...201324006751
unsaturated fatty acids from food and in the growth medium improve growth of bacillus cereus under cold and anaerobic conditions.in a chemically defined medium and in luria broth, cold strongly reduced maximal population density of bacillus cereus atcc 14579 in anaerobiosis and caused formation of filaments. in cooked spinach, maximal population density of b. cereus in anaerobiosis was the same at cold and optimal temperatures, with normal cell divisions. the lipid containing fraction of spinach, but not the hydrophilic fraction, restored growth of b. cereus under cold and anaerobiosis when added to the chemically defined ...201324010589
differences in biofilm formation of produce and poultry salmonella enterica isolates and their persistence on spinach plants.spinach plants were irrigated biweekly with water containing 2.1 log cfu salmonella/100 ml water (the maximum escherichia coli mpn recommended by the leafy greens marketing agreement; lgma), or 4.1 cfu salmonella/100 ml water to determine salmonella persistence on spinach leaves. green fluorescent protein expressing salmonella were undetectable by most-probable number (mpn) at 24 h and 7 days following each irrigation event. this study indicates that salmonella are unlikely to persist on spinach ...201324010621
photobleaching with phloxine b sensitizer to reduce food matrix interference for detection of escherichia coli serotype o157:h7 in fresh spinach by flow cytometry.a flow cytometric method (rapid-b™) with detection sensitivity of one viable cell of escherichia coli serotype o157:h7 in fresh spinach (spinacia oleracea) was developed and evaluated. the major impediment to achieving this performance was mistaking autofluorescing spinach particles for tagged target cells. following a 5 h non-selective enrichment, artificially inoculated samples were photobleached, using phloxine b as a photosensitizer. samples were centrifuged at high speed to concentrate targ ...201324010624
comparison of plant growth-promotion with pseudomonas aeruginosa and bacillus subtilis in three vegetables.our objective was to compare some plant growth promoting rhizobacteria (pgpr) properties of bacillus subtilis and pseudomonas aeruginosa as representatives of their two genera. solanum lycopersicum l. (tomato), abelmoschus esculentus (okra), and amaranthus sp. (african spinach) were inoculated with the bacterial cultures. at 60 days after planting, dry biomass for plants treated with b. subtilis and p. aeruginosa increased 31% for tomato, 36% and 29% for okra, and 83% and 40% for african spinach ...200824031240
short-term alteration of nitrogen supply prior to harvest affects quality in hydroponic-cultivated spinach (spinacia oleracea).quality-associated problems, such as excessive in planta accumulation of oxalate, often arise in soillessly cultivated spinach (spinacia oleracea). maintaining a higher level of ammonium (nh₄⁺) compared to nitrate (no₃⁻) during the growth period can effectively decrease the oxalate content in hydroponically cultivated vegetables. however, long-term exposure to high concentrations of nh₄⁺ induces toxicity in plants, and thus decreases the biomass production. short-term application of nh₄⁺ before ...201424038064
identification of three fungi newly intercepted from importing plants in korea.three fungi newly intercepted from importing plants were identified in 2004. they were ascochyta chrysanthemi on lactuca sativa from china, a. spinaciicola on spinacia oleracea from denmark, and leptosphaerulina australis on brassica oleracea var. capitata from china. the characters of these fungi were described and illustrated.200524049509
development of a sensitive monoclonal antibody-based indirect competitive enzyme-linked immunosorbent assay for analysing chlorantraniliprole residues.chlorantraniliprole (cap) is a new anthranilic diamide insecticide acting with high efficacy on ryanodine receptors of most of the species within the lepidoptera order and has been used worldwide. to monitor its residue in food and environmental samples, we developed an indirect competitive enzyme-linked immunosorbent assay (icelisa), based on monoclonal antibodies. the established icelisa possesses a concentration of producing 50% inhibition (ic50) of 1.60ng/ml. in addition, the assay had the a ...201424054242
spectrophotometric determination of fe3+ and pb2+ in real samples after micelle-mediated extraction.a cloud-point extraction process using micelle of the cationic surfactant ctab to extract fe3+and pb2+ from aqueous solutions was investigated. the method is based on the color reaction of fe3+and pb2+ with bromopyrogallol red at ph 5.0 and micelle-mediated extraction of the complex. the optimal extraction and reaction conditions (e.g., surfactant concentration, reagent concentration and effect of time) were studied and the analytical characteristics of the method (e.g., limit of detection, line ...201124062039
appraisal of hygiene indicators and farming practices in the production of leafy vegetables by organic small-scale farmers in umbumbulu (rural kwazulu-natal, south africa).during october, november and december 2011 (when highest sales of agri-hub fresh produce are observed), irrigation water, compost, lettuce and spinach sampled from four different farmer cooperatives supplying the local agri-hub in umbumbulu (kwazulu-natal, south africa) were analyzed monthly for the presence of total and fecal coliforms and escherichia coli using the most probable number (mpn) technique. the ph values for all irrigation water samples analyzed were within the acceptable range of ...201324065036
antimycobacterial and herbicidal activity of ring-substituted 1-hydroxynaphthalene-2-carboxanilides.in this study, a series of 22 ring-substituted 1-hydroxynaphthalene-2-carboxanilides were prepared and characterized. primary in vitro screening of the synthesized compounds was performed against mycobacterium marinum, mycobacterium kansasii and mycobacterium smegmatis. the compounds were also tested for their activity related to inhibition of photosynthetic electron transport (pet) in spinach (spinacia oleracea l.) chloroplasts. most of tested compounds showed the antimycobacterial activity aga ...201324075143
human health risk from heavy metal via food crops consumption with wastewater irrigation practices in pakistan.the current study was designed to investigate the potential human health risks associated with consumption of food crops contaminated with toxic heavy metals. cadmium (cd) concentration in surface soils; cd, lead (pb) and chromium (cr) in the irrigation water and food crops were above permissible limits. the accumulation factor (af) was >1 for manganese (mn) and pb in different food crops. the health risk index (hri) was >1 for pb in all food crops irrigated with wastewater and tube well water. ...201324075531
programmable folding of fusion rna in vivo and in vitro driven by prna 3wj motif of phi29 dna packaging motor.misfolding and associated loss of function are common problems in constructing fusion rna complexes due to changes in energy landscape and the nearest-neighbor principle. here we report the incorporation and application of the prna-3wj motif of the phi29 dna packaging motor into fusion rna with controllable and predictable folding. the motif included three discontinuous ∼18 nucleotide (nt) fragments, displayed a distinct low folding energy (shu d et al., nature nanotechnology, 2011, 6:658-667), ...201424084081
a new endornavirus species infecting malabar spinach (basella alba l.).a putative new endornavirus was isolated from malabar spinach (basella alba). the viral dsrna consisted of 14,027 nt with a single orf that coded for a polyprotein of 4,508 aa. the genome organization was similar to that of four other endornaviruses. conserved domains for helicase-1, capsular synthase, udp-glucose-glycosyltransferase (ugt), and rdrp were detected. infected plants were phenotypically undistinguishable from healthy ones. the name basella alba endornavirus is proposed for the virus ...201424122112
determination of pork spoilage by colorimetric gas sensor array based on natural pigments.a new colorimetric gas-sensor array based on four natural pigments, that were extracted from spinach (spinacia oleracea), red radish (raphanus sativus l.), winter jasmine (jasminum nudiflorum), and black rice (oryza sativa l. indica), was developed for pork freshness evaluation. a colour change profile for each sample was obtained by differentiating the images of the sensor array before and after exposure to the odour of sample. the total viable count (tvc) per gram of pork was obtained by class ...201424128513
combinatorial optimization of cystine-knot peptides towards high-affinity inhibitors of human matriptase-1.cystine-knot miniproteins define a class of bioactive molecules with several thousand natural members. their eponymous motif comprises a rigid structured core formed by six disulfide-connected cysteine residues, which accounts for its exceptional stability towards thermic or proteolytic degradation. since they display a remarkable sequence tolerance within their disulfide-connected loops, these molecules are considered promising frameworks for peptide-based pharmaceuticals. natural open-chain cy ...201324146945
biosynthesis of levan, a bacterial extracellular polysaccharide, in the yeast saccharomyces cerevisiae.levans are fructose polymers synthesized by a broad range of micro-organisms and a limited number of plant species as non-structural storage carbohydrates. in microbes, these polymers contribute to the formation of the extracellular polysaccharide (eps) matrix and play a role in microbial biofilm formation. levans belong to a larger group of commercially important polymers, referred to as fructans, which are used as a source of prebiotic fibre. for levan, specifically, this market remains untapp ...201324147008
flagella interact with ionic plant lipids to mediate adherence of pathogenic escherichia coli to fresh produce plants.bacterial attachment to plant and animal surfaces is generally thought to constitute the initial step in colonization, requiring adherence factors such as flagella and fimbriae. we describe the molecular mechanism underpinning flagella-mediated adherence to plant tissue for the foodborne pathogen, enterohaemorrhagic escherichia coli. escherichia coli h7 flagella interacted with a sulphated carbohydrate (carrageenan) on a glycan array, which occurred in a dose-dependent manner. adherence of e. co ...201424148193
graphite furnace atomic absorption spectrometric detection of vanadium in water and food samples after solid phase extraction on multiwalled carbon nanotubes.vanadium(v) ions as 8-hydroxyquinoline chelates were loaded on multiwalled carbon nanotubes (mwnts) in a mini chromatographic column. vanadium was determined by graphite furnace atomic absorption spectrometry (gfaas). various analytical parameters including ph of the working solutions, amounts of 8-hydroxyquinoline, eluent type, sample volume, and flow rates were investigated. the effects of matrix ions and some transition metals were also studied. the column can be reused 250 times without any ...201324148394
molecular evidence that the genes for dioecism and monoecism in spinacia oleracea l. are located at different loci in a chromosomal region.spinach (spinacia oleracea l.) is widely known to be dioecious. however, monoecious plants can also occur in this species. sex expression in dioecious spinach plants is controlled by a single gene pair termed x and y. our previous study showed that a single, incompletely dominant gene, which controls the monoecious condition in spinach line 03-336, should be allelic or linked to x/y. here, we developed 19 aflp markers closely linked to the monoecious gene. the aflp markers were mapped to a 38.2- ...201424169648
localization and nucleotide sequence of the gene for the atp synthase proteolipid subunit on the spinach plastid chromosome.a 1.6 kbp dna segment of spinach plastid dna has been shown to carry the gene for the proteolipid subunit of the atp synthase. each plastid chromosome contains one copy of this gene which is located in the large single-copy region of the chromosome near that of the atp synthase alpha subunit. these two genes are transcribed in the same direction and probably in distinct rna species. the proteolipid gene was located by hybrid-selection mapping, by transcription/translation of recombinant dnas and ...198324173155
physical mapping, nucleotide sequencing and expression in e. coli minicells of the gene for the large subunit of ribulose bisphosphate carboxylase from petunia hybrida.the petunia hybrida rbcl gene was identified and located on the physical map within the sall s9 fragment of the petunia hybrida cpdna by heterologous hybridization with the cloned rbcl gene of spinach (psoc3be148). in e. coli minicells harbouring the s9 fragment inserted into pbr322, the rbcl polypeptide is synthesized as was shown by molecular weight determination, immunoprecipitation and proteolytic digestion. however, the size of the rbcl polypeptide synthesized in minicells appeared to be de ...198424177744
light-mediated regulation of glutamine synthetase activity in the unicellular cyanobacterium synechococcus sp. pcc 6301.glutamine synthetase (gs; ec 6.3.1.2) activity from the unicellular cyanobacterium synechococcus sp. strain pcc 6301 shows a short-term regulation by light-dark transitions. the enzyme activity declines down to 30% of the original level after 2 h of dark incubation, and can be fully reactivated within 15 min of re-illumination. the loss of activity is not due to protein degradation, but rather to a reversible change of the enzyme, as deduced from the gs-protein levels determined in dark-incubate ...199224178052
hydration-state-responsive proteins link cold and drought stress in spinach.spinach (spinacia oleracea l.) seedlings exposed to low nonfreezing temperatures (0-10° c) that promote cold acclimation, synthesize a variety cold-acclimation proteins and at the same time acquire a greater ability to withstand cellular dehydration imposed by the freezing of tissue water. two of these proteins (160 and 85 kda) become more abundant over time at low temperature. in addition, a small decline in tissue water status from a maximally hydrated state also appears to be associated with ...199224178264
photoinhibition of photosystem ii in vivo is preceded by down-regulation through light-induced acidification of the lumen: consequences for the mechanism of photoinhibition in vivo.the mechanism of photoinhibition of photosystem ii (psii) was studied in intact leaf discs of spinacia oleracea l. and detached leaves of vigna unguiculata l. the leaf material was exposed to different photon flux densities (pfds) for 100 min, while non-photochemical (qn) and photochemical quenching (qp) of chlorophyll fluorescence were monitored. the 'energy' and redox state of psii were manipulated quite independently of the pfd by application of different temperatures (5-20° c), [co2] and [o2 ...199324178492
response of a nitrite-reductase 3.1-kilobase upstream regulatory sequence from spinach to nitrate and light in transgenic tobacco.in the present study the question was addressed of whether the nitrite-reductase (nir-)promoter from spinach (spinacia oleracea l.), fused to a reporter gene (bacterial β-glucuronidase, gus) and introduced into tobacco (nicotiana tabacum l.) responds to nitrate and light in accordance with spinach (donor) or in accordance with tobacco (host). the data obtained at the gus enzyme level as well as at the transcript level allow an unambiguous answer to this question: gus gene expression under the co ...199324178503
efficient chimeric plant promoters derived from plant infecting viral promoter sequences.in the present study, we developed a set of three chimeric/hybrid promoters namely fsgt-pflt, pflt-uas-2x and msgt-pflt incorporating different important domains of figwort mosaic virus sub-genomic transcript promoter (fsgt, -270 to -60), mirabilis mosaic virus sub-genomic transcript promoter (msgt, -306 to -125) and peanut chlorotic streak caulimovirus full-length transcript promoter (pflt-, -353 to +24 and pflt-uas, -353 to -49). we demonstrated that these chimeric/hybrid promoters can drive t ...201424178585
binding sites of e. coli dna-dependent rna polymerase on spinach chloroplast dna.under stringent conditions e. coli dna-dependent rna polymerase holoenzyme binds selectively to some spinach chloroplast dna fragments generated by restriction endonucleases. the strongest of these binding sites, as judged by the initial rate of complex formation, are located in the large single-copy dna region (crouse et al. 1978) of this molecule and correspond in map location with known protein coding sequences. some of these binding sites have characteristics of complex formation comparable ...198124185866
lipid peroxidation and superoxide dismutase activity in relation to photoinhibition induced by chilling in moderate light.the effect of a chilling stress, at a moderate photon flux density for a few hours, on the peroxidation of membrane lipids and on superoxide dismutase (sod) activity was compared in leaf slices of chilling-sensitive and chilling-insensitive plants. the aim was to determine if susceptibility to chill-temperature photoinhibition could be related to either damage to membrane lipids by superoxide and-or a decrease in activity of chloroplast sod. plants used were nerium oleander l., grown at 45° c, a ...199124186344
multiplicity of soluble glucan-synthase activity in spinach leaves: enzyme pattern and intracellular location.buffer-extractable proteins from leaves of spinacia oleracea l. were separated by non-denaturing polyacrylamide gel electrophoresis. gels were stained for adenosine diphosphoglucose (adpglucose)-dependent glucan-synthase (gs) activity (ec 2.4.1.21). three major forms of activity were observed. no staining was detectable when adpglucose was replaced by an equimolar concentration of either uridine, guanosine or cytosine diphosphoglucose. two of the three gs forms exhibited both primed and citrate- ...199124186345
aspartic-acid synthesis in c3 plants.in a previous study (melzer and o'leary, 1987, plant physiol. 84, 58-60), we used isotopic methods to show that a substantial fraction of protein-bound aspartic acid in tobacco is derived from anaplerotic synthesis via phosphoenolpyruvate (pep) carboxylase. similar studies in soybean (glycine max l.) and spinach (spinacia oleracea l.) showed a similar pattern, and this pattern persists with age because of slow protein turnover. a more quantitative analysis indicates that about 40% of protein-bou ...199124186420
ribulose-1,5-bisphosphate carboxylase-oxygenase, other calvin-cycle enzymes, and chlorophyll decrease when glucose is supplied to mature spinach leaves via the transpiration stream.the inhibition of photosynthesis after supplying glucose to detached leaves of spinach (spinacia oleracea l.) was used as a model system to search for mechanisms which potentially contribute to the "sink" regulation of photosynthesis. detached leaves were supplied with 50 mm glucose or water for 7 d through the transpiration stream, holding the leaves in low irradiance (16 μmol photons · m(-2) · s(-1)) and a cycle of 9 h light/15 h darkness to prevent any endogenous accumulation of carbohydrate. ...199124186575
identification of an nadp/thioredoxin system in chlamydomonas reinhardtii.the protein components of the nadp/thioredoxin system, nadp-thioredoxin reductase (ntr) and thioredoxin h, have been purified and characterized from the green alga, chlamydomonas reinhardtii. the analysis of this system confirms that photoautotrophic chlamydomonas cells resemble leaves in having both an nadp- and ferrodoxin-linked thioredoxin redox system. chlamydomonas thioredoxin h, which is smaller on sodium dodecyl sulfate-polyacrylamide gel electrophoresis than thioredoxin m from the same s ...199124186583
adenine nucleotides are apparently involved in the light-dark modulation of spinach-leaf nitrate reductase.nitrate reductase (nr; ec 1.6.6.1) in spinach (spinacia oleracea l. cv. polka f1) leaves showed reversible modulation, being activated in the light and inactivated in the dark (t/2 = 20-30 min). the large changes in enzyme activity during light-dark transients were observed only when assayed in buffers containing free mg(2+). in the presence of edta (5 mm), the enzyme activity was high and the light modulation was barely evident.the inactivation of nr in the dark could be totally prevented by an ...199224186663
superoxide production by thylakoids during chilling and its implication in the susceptibility of plants to chilling-induced photoinhibition.factors influencing the rate of superoxide (o 2 (-) ) production by thylakoids were investigated to determine if increased production of the radical was related to injury induced by chilling at a moderate photon flux density (pfd). plants used were spinacia oleracea l., cucumis sativus l. and nerium oleander l. grown at either 200° c or 45° c. superoxide production was determined by electron-spin-resonance spectroscopy of the (o 2 (-) )-dependent rate of oxidation of 2-ethyl-1-hydroxy-2,5,5-trim ...199124193624
the action of phosphatidate phosphatase on the fatty-acid composition of safflower triacylglycerol and spinach glycerolipids.the microsomal phosphatidate phosphatase (ec 3.1.3.4) in maturing seeds of safflower (carthamus tinctorius l.) was specific and selective for unsaturated phosphatidates. the relative order of specificity for phosphatidate molecular species was 1,2-dilinoleoyl = 1,2-dioleoyl > 1-palmitoyl-2-oleoyl > 1,2-dilauroyl = 1,2-dimyristoyl > 1,2-dipalmitoyl. the order of selectivity was similar to that of the specificity. the broad selectivity for unsaturated phosphatidate species (1,2-di-unsaturated-acyl ...199124193745
molecular cloning and structural analysis of the phosphate translocator from pea chloroplasts and its comparison to the spinach phosphate translocator.using an 5'-avaii fragment of the spinach (spinacia oleracea l.) phosphate translocator cdna as a probe for a hybridization screening of a pea (pisum sativum l.) cdna library we have cloned and sequenced a cdna clone coding for the phosphate translocator precursor protein from pea chloroplasts. the full-length cdna clone comprises 42 base pairs (bp) at the 5'-non-coding region, a 1206-bp coding region corresponding to a polypeptide of 402 amino-acid residues (relative molecular mass 43 671) and ...199124193755
inhibition of the transthylakoid gradient of electrochemical proton potential by the local anesthetic dibucaine.the effects of the local anesthetic dibucaine on coupling between electron transport and atp synthesis-hydrolysis by the coupling-factor complex (cf0cf1 atpase) were investigated in thylakoid membranes from spinacia oleracea l. cv. monatol. evidence is presented that inhibition of atp synthesis was produced by a specific uncoupling mechanism which was based on dibucaine-membrane surface interactions rather than on the interaction of dibucaine with the atpase complex. dibucaine reduced the osmoti ...199124193850
the relationship between the activation state of sucrose-phosphate synthase and the rate of co2 assimilation in spinach leaves.the relationship between the gas-exchange characteristics of spinach (spinacia oleracea l.) leaves and the activation state of sucrose-phosphate synthase was examined at different intercellular partial pressures of co2 at two different photon flux densities. there was a strong positive correlation between the activation state of sucrose-phosphate synthase and the assimilation rate. the relationship was the same at both photon flux densities, indicating that the activation state of the enzyme is ...199124193857
coaction of light, nitrate and a plastidic factor in controlling nitrite-reductase gene expression in spinach.it is well established that nitrite reductase (nir; ec 1.7.7.1) a key enzyme of nitrate reduction - is "induced" by nitrate and light. in the present study with the spinach (spinacia oleracea l.) seedling the dependency of nir appearance on nitrate, light and a 'plastidic factor' was investigated to establish the nature of the coaction between these controlling factors. a cdna clone coding for spinach nir was available as a probe. the major results we have obtained are the following: (i) the lig ...199124193932
photosynthetic oxygen evolution and chlorophyll fluorescence in intact isolated chloroplasts on a solid support: the influence of orthophosphate.we devised recently a method to trap intact isolated chloroplasts on a solid support consisting of membrane filters made of cellulose nitrate (cerović et al., 1987, plant physiol. 84, 1249-1251). the addition of alkaline phosphatase to the reaction medium enabled continuous photosynthesis by spinach (spinacia oleracea l.) chloroplasts to be sustained by hydrolysis of newly produced and exported triose phosphates and recycling of orthophosphate. in this system, simultaneous measurements of chloro ...199124194077
purification of udp-galactose: diacylglycerol galactosyltransferase from chloroplast envelopes of spinach (spinacia oleracea l.).uridine 5'-diphosphate(udp)-galactose: 1,2-diacylglycerol 3-o-β-d-galactopyranosyltransferase (ec 2.4.1.46) is an integral protein of chloroplast envelope membranes from which it has been partially purified (covès et al., 1986, febs lett. 208, 401-406). we have worked out a purification procedure which after removal of peripheral membrane proteins, solubilization and two chromotographic steps allowed us to identify a 22-kda protein as the galactosyltransferase. enrichment of enzymatic activity w ...199124194148
embryogenesis and plant regeneration of spinach (spinacia oleracea l.) from hypocotyl segments.a system for somatic embryogenesis and plant regeneration of spinach from hypocotyl segments has been established. callus was induced on solid media supplemented with 8.5-15.0 mg.l(-1) of indole-3-acetic acid and 3.46-34.64 mg.l(-1) gibberellic acid. callus was then subcultured on different media (solid or liquid) with or without iaa, or continuously maintained on the initiating media. somatic embryos were obtained in subcultures on iaa-containing media as well as in long-term cultures on initia ...199324196289
regulation of sedoheptulose-1,7-bisphosphatase by sedoheptulose-7-phosphate and glycerate, and of fructose-1,6-bisphosphatase by glycerate in spinach chloroplasts.using partially purified sedoheptulose-1,7-bisphosphatase from spinach (spinacia oleracea l.) chloroplasts the effects of metabolites on the dithiothreitoland mg(2+)-activated enzyme were investigated. a screening of most of the intermediates of the calvin cycle and the photorespiratory pathway showed that physiological concentrations of sedoheptulose-7-phosphate and glycerate specifically inhibited the enzyme by decreasing its maximal velocity. an inhibition by ribulose-1,5-bisphosphate was als ...199024196680
characterization and compartmentation, in green leaves, of hexokinases with different specificities for glucose, fructose, and mannose and for nucleoside triphosphates.when green leaves of spinach (spinacia oleracea l.) were surveyed for the presence of hexokinases which utilize glucose, fructose and-or mannose as a substrate, four kinases could be distinguished by their order of elution during chromatography on diethylaminoethyl (deae)-cellulose: (i) a hexokinase i with a specificity for fructose, glucose, and mannose, (ii) a fructokinase i with a specificity for fructose, (iii) a hexokinase ii with a specificity for glucose, fructose and mannose, and (iv) a ...199024196745
the aggregation states of spinach phosphoribulokinase.phosphoribulokinase (prk; ec 2.1.7.19) is active in illuminated chloroplasts and inactive in darkened chloroplasts. this regulatory mechanism is mediated by thioredoxin-dependent reduction of a kinase disulfide in vivo. extracts of spinach (spinacia oleracea l.) leaves in the presence of 10 mm dithiothreitol contain a single 80-kda form of prk as judged by gel filtration. gel filtration of thiol-free extracts of light-harvested tissue shows the presence of two inactive forms of prk, the 80-kda f ...199024196813
control of photosynthate partitioning in spinach leaves : analysis of the interaction between feedforward and feedback regulation of sucrose synthesis.experiments were carried out to estimate the elasticity coefficients and thence the distribution of control of sucrose synthesis and photosynthate partitioning between cytosolic fructose-1,6-bisphosphatase and sucrose-phosphate synthase (sps), by applying the dualmodulation method of kacser and burns (1979, biochem. soc. trans. 7, 1149-1161). leaf discs of spinach (spinacia oleracea l.) were harvested at the beginning and end of the photoperiod and illuminated at five different irradiances to al ...199024196941
regulation of photosynthetic sucrose synthesis: a role for calcium?we have investigated whether changes of the cytosolic free-calcium concentration could regulate photosynthetic sucrose synthesis. partially purified enzymes from spinach (spinacea oleracea l.) leaves were assayed using calcium-egta buffers to obtain defined free-calcium concentrations in the low micromolar and submicromolar ranges. these concentrations of calcium did not directly affect sucrose-phosphate synthase activity. they inhibited the cytosolic fructose-1,6-bisphosphatase, acting competit ...199024197102
fluorescence microscopy and radiolabeling of c3 and c 4 chloroplasts using diisothiocyanatostilbene disulfonic acid as a marker for the phosphate translocator.the usefulness of 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (dids) for in-situ studies of the chloroplast phosphate translocator was evaluated by fluorescence microscopy and radiolabeling of spinach (spinacia oleracea l.) (c3 plant) and maize (zea mays l.) (c4 plant) chloroplasts. in maize mesophyll and bundle-sheath chloroplasts and in spinach chloroplasts that were either intact, broken or swollen, dids fluorescence was only associated with the chloroplast envelope. intact chloroplast ...198924201512
localization of a protein, immunologically similar to a sucrose-binding protein from developing soybean cotyledons, on the plasma membrane of sieve-tube members of spinach leaves.immunocytochemical studies using antibodies raised against a 62-kda membrane protein isolated from developing soybean (glycine max (l.) merr.) cotyledons were performed on leaf tissue of spinach (spinacia oleracea l.). this 62-kda protein was labeled by 6'-deoxy-6'-(4-azido-2-hydroxy)-benzamidosucrose (habs), a photoaffinity sucrose analogue (k. g. ripp et al., 1988, plant physiol.88, 1435-1445). western-blot analysis of spinach plasma-membrane proteins indicated a cross-reactive polypeptide ide ...198924201850
reversible photoinhibition of unhardened and cold-acclimated spinach leaves at chilling temperatures.the photoinhibition of photosynthesis at chilling temperatures was investigated in cold-acclimated and unhardened (acclimated to +18° c) spinach (spinacia oleracea l.) leaves. in unhardened leaves, reversible photoinhibition caused by exposure to moderate light at +4° c was based on reduced activity of photosystem (ps) ii. this is shown by determination of quantum yield and capacity of electron transport in thylakoids isolated subsequent to photoinhibition and recovery treatments. the activity o ...199024201942
the ferredoxin-thioredoxin system of a green alga, chlamydomonas reinhardtii : identification and characterization of thioredoxins and ferredoxin-thioredoxin reductase components.the components of the ferredoxin-thioredoxin (ft) system of chlamydomonas reinhardtii have been purified and characterized. the system resembled that of higher plants in consisting of a ferredoxin-thioredoxin reductase (ftr) and two types of thioredoxin, a single f and two m species, m1 and m2. the chlamydomonas m and f thioredoxins were antigenically similar to their higher-plant counterparts, but not to one another. the m thioredoxins were recognized by antibodies to both higher-plant m and ba ...199024202012
protective systems against active oxygen species in spinach: response to cold acclimation in excess light.spinach (spinacia oleracea l.) plants were acclimated to 1° c or maintained at 18° c under the same light regime (260-300 μmol photons·m(-2)·s(-1)). the cold acclimation led to several metabolic and biochemical changes that apparently include improved protection of the photosynthetic apparatus against active oxygen species. in particular, cold-acclimated leaves exhibited a considerably higher ascorbate content and significantly increased activities of superoxide dismutase, ascorbate peroxidase, ...199024202017
proteins from frost-hardy leaves protect thylakoids against mechanical freeze-thaw damage in vitro.we have isolated protein fractions from cold-acclimated, frost-hardy cabbage (brassica oleracea l.) and spinach (spinacia oleracea l.) leaves which protect isolated thylakoids from non-hardy spinach against mechanical membrane rupture during an in-vitro freeze-thaw cycle. no protective activity was found in similar preparations from non-hardy leaves. the proteins protected the membranes from damage by reducing their solute permeability during freezing and by increasing their expandability during ...199024202022
regulation of sucrose-phosphate-synthase activity in spinach leaves by protein level and covalent modification.a dot-blot technique was developed using monoclonal antibodies to measure, rapidly and accurately, the amount of sucrose-phosphate synthase (sps; ec 2.4.1.14) protein present in a crude extract from spinach (spinacia oleracea l. cv. dark green bloomsdale) leaves; this was compared with sps activity in this material. during leaf development, increased sps activity followed closely the increase in enzyme-protein level, indicating denovo synthesis or altered turn-over rates for sps. in contrast, ac ...198924212279
response of photosynthesis and respiration of resurrection plants to desiccation and rehydration.using non-invasive techniques (co2 gas exchange, light scattering, light absorption, chlorophyll fluorescence, chlorophyll luminescence), we have analysed the response of respiration and photosynthesis to dehydration and rehydration of leaves of the resurrection plants craterostigma plantagineum hochst., ramonda mykoni reichb. and ceterach officinarum lam. et dc. and of the drought-sensitive mesophyte spinach (spinacia oleracea l.). the following observations were made: (i) the rate of water los ...198924212344
photoinhibition at chilling temperature : fluorescence characteristics of unhardened and cold-acclimated spinach leaves.the effects of moderate light at chilling temperature on the photosynthesis of unhardened (acclimated to +18° c) and hardened (cold-acclimated) spinach (spinacea oleracea l.) leaves were studied by means of fluorescence-induction measurements at 20° c and 77k and by determination of quantum yield of o2 evolution. exposure to 550 μmol photons·m(-2)·s(-1) at +4° c induced a strong photoinhibition in the unhardened leaves within a few hours. photoinhibition manifested by a decline in quantum yield ...198924212435
comparison of acetate- and pyruvate-dependent fatty-acid synthesis by spinach chloroplasts.in recent studies using intact chloroplasts of spinach (spinacia oleracea l.) to investigate the accumulation of acetyl-coa produced by the activity of either acetyl-coa synthetase (ec 6.2.1.1) or the pyruvate-dehydrogenase complex, this product was not detectable. these results in combination with new information on the physiological levels of acetate and pyruvate in spinach chloroplasts (h.-j. treede et al. 1986, z. naturforsch. 41 c, 733-740) prompted a reinvestigation of the incorporation of ...198924212436
short-term water stress leads to a stimulation of sucrose synthesis by activating sucrose-phosphate synthase.the aim of this work was to identify which aspects of photosynthetic metabolism respond most sensitively to leaf water deficit. spinach (spinacia oleracea l.) leaf discs were floated on sorbitol concentrations of increasing molarity and changes of the protoplast volume were estimated using [(14)c]sorbitol and (3)h2o penetration. detached leaves were also wilted until 10% of their fresh weight was lost. photosynthesis was studied at very high external co2 concentrations, to eliminate the effect o ...198924212496
comparative biochemical and immunological studies of the glycine betaine synthesis pathway in diverse families of dicotyledons.members of the chenopodiaceae can accumulate high levels (>100 μmol·(g dw)(-1)) of glycine betaine (betaine) in leaves when salinized. chenopodiaceae synthesize betaine by a two-step oxidation of choline (choline→betaine aldehyde→ betaine), with the second step catalyzed by betaine aldehyde dehydrogenase (badh, ec 1.2.1.8). high betaine levels have also been reported in leaves of species from several distantly-related families of dicotyledons, raising the question of whether the same betaine-syn ...198924212901
shoot regeneration from spinach hypocotyl segments by short term treatment with 5,6-dichloro-indole-3-acetic acid.factors affecting shoot regeneration from hypocotyl segments of spinach (spinacia oleracea l.) were investigated. when expiants were cultured on medium containing 10 mg/l iaa for 7 weeks, 3 out of 9 cultivars showed relatively high shoot regeneration response (15 - 35%). the other pgrs tested had no effect on shoot regeneration. however, the transfer of explants from auxin-containing medium to auxin-free medium 20 d after culture induced shoot formation from expiants cultured on media containing ...199224213485
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