Accumulation of Ascorbic Acid in the Cotyledons of Morning Glory (Pharbitis nil) Seedlings during the Induction of Flowering by Low-Temperature Treatment and the Effect of Prior Exposure to High-Intensity Light

Seedlings of Pharbitis nil strain ‘Violet’ werecultured at a low temperature, which induces their floweringeven in continuous light, with or without prior exposure tohigh-intensity light, which enhances the flower-inducing effectof the exposure to low temperature. Analysis by HPLC of extractsof cotyledons showed that the level of an unstable compoundincreased during these treatments, in addition to the increasein levels of phenylpropanoids reported previously. The compoundwas identified as ascorbic acid from the spectroscopic data.The change in the concentration of ascorbic acid at low temperaturewas correlated with the increase in the induction of floweringand the increase in levels of the phenylpropanoids. The rapidincrease in level of ascorbic acid after exposure to high-intensitylight reflected the promotive effect of high-intensity lighton the induction of flowering at low temperature. However, levelsof ascorbic acid also increased in seedlings of P. nil strain‘Kidachi’ that were cultured in high-intensity light,a treatment that does not induce flowering in this strain. Thus,ascorbic acid cannot be associated with the induction of floweringby high-intensity light alone. Ascorbic acid increased the rateof formation of caffeic acid from p-coumaric acid in vitro,a result that suggests that ascorbic acid might be involvedin the increases in levels of phenylpropanoids in the seedlings. (Received April 17, 1995; Accepted August 1, 1995)     

Flowering in Pisum: Kinetics of the Vernalization Response in Genotype If e Sn Hr

Previous work has shown that vernalization acts at two sites,one in the cotyledons and one in the shoot, in young plantsof genotype Ife Sn Hr. During the present study the size ofthe vernalization responses in both the cotyledons and shootincreased as the temperature was lowered from 17 to 3 °C.This occurred regardless of whether the treatment was givenfor the same chronological period of time or for the same physiologicalperiod of time. Vernalization treatment was effective from thetime the seeds were developing in the pods on the maternal plantuntil at least 20 leaves were expanded and became graduallymore effective as the length of the treatment was increasedfrom 2 to 5 weeks. High pre– or post–vernalizationtemperatures can reduce the cotyledon effect and to a lesserextent the shoot effect of vernalization. Devernalization occurredto a larger extent in low light intensities and darkness thanin high light intensities. No stabilization of the vernalizationeffects in the cotyledons or shoot appeared to occur at normalgrowing temperatures (15–25 °C). These results arediscussed in terms of the previously hypothesized mechanismsfor the cotyledon and shoot effects of vernalization. Pisum sativum, flowering, vernalization     

Effect of High-intensity Light Given Prior to Low-temperature Treatment on the Long-day Flowering of Pharbitis nil

Pharbitis nil, strain Violet which had been exposed to high-intensitylight (18,000 lux at 23?C) for 7 days followed by a low-temperaturetreatment (13–14?C) for 7 days initiated flower buds evenunder continuous light, but plants given these treatments inreverse order failed to bud. Three days of high-intensity lightat 23?C was most effective in promoting the flower-inducingeffect of the subsequent low-temperature period. Six days oflow temperature following the 3-day high-intensity light periodinduced near-maximum flowering response. DCMU (5?10^–6M) given during the high-intensity light period inhibited flowering,but when given during or after the low-temperature period itwas ineffective. DCMU at the same concentration given before,during or after an inductive 16-hr dark period at 26?C did notinhibit flowering. Sucrose, ATP, NADPH and some other reducingagents tested did not nullify the DCMU effect nor substitutefor the effect of high-intensity light. But, the high-intensitylight effect could be substituted, at least partly, by 5-chlorosalicylicacid, 3,4-dichlorobenzoic acid and some other benzoic acid derivatives,which are highly effective in inducing long-day flowering inthe short-day plant, Lemna paucicostata. (Received October 20, 1981; Accepted February 3, 1982)     

Effects of Low Temperature, Light and O2 on Chilling-sensitive and -resistant Strains in Chlorella ellipsoidea

A low-temperature sensitive strain, Chlorella ellipsoidea Gerneck(IAM C-102), lost its chilling sensitivity during preservation.Cells of the original strain (low-temperature sensitive) andthe variant (low-temperature resistant) were both synchronouslygrown under a 14-hr light-10-hr dark regime. In the originalstrain, cells at the D-L stage (transient phase) were most sensitiveto a low temperature, whereas the variant cells were not damagedat any stage. During low-temperature treatment, the viability of D-L cellsin the sensitive strain decreased after a lag period of 1 hr.The O₂-uptake activity (respiration) showed the same behavioras the viability, whereas the O₂-evolution activity (photosynthesis)decreased from the start of chilling. In the resistant strain,only O₂ evolution decreased. The decreased activity was restoredwhen the chilled cells were incubated at 25°C. This restorationwas inhibited by oligomycin. Lowering the light intensity or eliminating O2 diminished thechilling injury of the sensitive strain. The results indicatethat the chilling injury of Chlorella results from the combinedeffects of low temperature, light and O₂. (Received September 26, 1980; Accepted March 23, 1981)     

The Effects of Temperature, Photoperiod and Light Integral on the Time to Flowering of Pansy cv. Universal Violet (ViolaxwittrockianaGams.)

The effects of temperature, photoperiod and light integral onthe time to first flowering of pansy (ViolaxwittrockianaGams)were investigated. Plants were grown at six temperatures (meansbetween 14.8 and 26.1 °C), combined with four photoperiods(8, 11, 14 and 17 h). The rate of progress to flowering increasedlinearly with temperature (up to an optimum of 21.7 °C)and with increase in photoperiod (r²=0.91, 19 d.f.), the latterindicating that pansies are quantitative long day plants (LDPs).In a second experiment, plants were sown on five dates betweenJuly and December 1992 and grown in glasshouse compartmentsunder natural day lengths at six temperatures (means between9.4 and 26.3 °C). The optimum temperature for time to floweringdecreased linearly (from 21.3 °C) with declining light integralfrom 3.4 MJ m^-2d^-1(total solar radiation). Data from both experimentswere used to construct a photo-thermal model of flowering inpansy. This assumed that the rate of progress to flowering increasedas an additive linear function of light integral, temperatureand photoperiod. Independent data from plants sown on threedates, and grown at five temperatures (means between 9.8 and23.6 °C) were used to validate this model which gave a goodfit to the data (r²=0.88, 15 d.f.). Possible confounding ofthe effects of photoperiod and light integral are discussed. Pansy;Violaxwittrockiana; flowering; photo-thermal model; temperature; photoperiod; light integral     

The Effects of Temperature and Light Integral on the Phases of Photoperiod Sensitivity inPetuniaxhybrida

Flowering in petunias is hastened by long days, but little isknown about when the plants are most sensitive to photoperiod,or how light integral or temperature affect such phases of sensitivity.The effects of these factors on time to flowering was investigatedusing reciprocal transfer experiments between long (16 h d^-1)and short days (8 h d^-1). The effect of light integral on thephases of photoperiod sensitivity was examined using two sowingdates and a shading treatment (53% transmission). The effectsof temperature were investigated by conducting reciprocal transferexperiments in glasshouse compartments at five temperature regimes(means of 13.7, 19.2, 22.3, 25.0 and 28.7 °C). The lengthof the photoperiod-insensitive juvenile phase of development,when flowering cannot be induced by any environmental stimulus,was sensitive to light integral; low light integrals prolongedthis phase, from 23 d at 2.6 MJ m^-2d^-1to 36 d at 1.6 MJ m^-2d^-1(totalsolar radiation). The length of this development phase was shortest(12.5 d) at 21 °C; it was longer under cooler (21 d at 13.5°C) and warmer temperatures (17.6 d at 28.3 °C). Afterthis phase, time to flowering was influenced greatly by photoperiod,with long days hastening flowering by between 28 and 137 d,compared with short days. Plants also showed some sensitivityto both temperature and light integral during this phase, butthe duration of the final phase of flower development, duringwhich plants were photoperiod-insensitive, was dependent primarilyon the temperature at which the plants were grown; at 14.5 °C,33.9 d were required to complete this phase compared with 11.4d at 25.5 °C. The experimental approach gave valuable informationon the phases of sensitivity to photothermal environment duringthe flowering process, and could provide the basis of a morephysiologically-based quantitative model of flowering than hashitherto been attempted. The information is also useful in thescheduling of lighting and temperature treatments to give optimalflowering times of high quality plants.Copyright 1999 Annalsof Botany Company Petunia,Petuniaxhybrida, juvenility, flowering, photoperiod, temperature, light integral, reciprocal transfer.     

Effects of Interactions Between Low and High Temperature Treatments on Flowering of Spring Rape (Brassica napusvar.annua)

Exposure to high temperature (30 °C) before or after exposureto low temperature (0, 4 or 8 weeks at 4 °C) consistentlyincreased the number of leaf nodes at flowering and delayedflowering in a range of genotypes of spring rape(Brassica napusvar.annuaL.).Four days of prior exposure to high temperature had more effectthan 2 d, and the effect of subsequent exposure to high temperaturewas maximized when exposure commenced 1 week after the end ofthe low-temperature treatment. In genotypes that showed a vernalizationresponse (i.e. in which the number of leaf nodes at floweringwas reduced or flowering was advanced by low temperature), thisresponse was reduced or eliminated by either prior high-temperaturetreatment (antivernalization) or subsequent high-temperaturetreatment (devernalization). A biochemical model to accountfor these effects is proposed.Copyright 1998 Annals of BotanyCompany Brassica napusvar.annua, spring rape, antivernalization, devernalization, vernalization     

Stimulation of the Flowering of Pharbitis nil Chois. by Gibberellin A3 : Time Dependent Action at the Apex

Gibberellin A₃ (GA₃) stimulated flowering when it was appliedto the shoot apex of seedlings of Pharbitis nil, dwarf strainKidachi; but, not when it was applied to the cotyledons. GA₃applied to the plumule before or shortly after the start ofan inductive dark period promoted both flowering and shoot elongation;but, the later the time of application during the dark periodless the promotion of flowering, although marked promotion ofshoot elongation always took place. The variation with time in the response of flowering to GA₃indicates that early floral processes at the apex are stimulatedby GA₃, but that subsequent processes are insensitive to it.The early processes of floral stimulus produced by a 16 hr inductivedark period probably are completed within 20 hr at 28°Cafter the end of the dark period. At low temperatures, suchas 15 and 20°C, early floral processes continued for morethan 40 hr. When cotyledons were removed at various times, the export ofthe floral stimulus to the shoot apex was apparent within hoursof the generation of the floral stimulus in the cotyledons,which started with the passage of the critical 9-hr dark period. (Received February 18, 1981; Accepted March 24, 1981)     

Dihydrokaempferol Glucoside from Cotyledons Promotes Flowering in Pharbitis nil

An extract of cotyledons of Pharbitis nil, which had been exposedto short-day conditions, was tested for flower-promoting activityin a shoot-tip assay system in vitro. The crude extract hadno flower-promoting activity, however, after partitioning ofthe crude extract with dichloromethane, the resulting aqueousfraction had flower-promoting activity. This activity was separatedinto two fractions by column chromatography on Toyopearl HW-40.One active fraction was identified as dihydrokaempferol-7-O-rß-D-glucoside(DHK-glc). This compound exhibited flower-promoting activityat the extremely low concentration of 4.4x10^-9. (Received April 25, 1995; Accepted August 11, 1995)     

The Effect of Temperature on Reproduction in FivePrimulaSpecies

Primula vulgarisHuds.,P. verisL.,P. frondosaJanka, and threepopulations ofP. farinosaL. were legitimately and illegitimatelypollinated, and the self-fertileP. scoticaselfed and cross-pollinatedand then subjected to uniform temperature conditions of 6, 15or 26 °C for 4 d before gynoecia were examined for pollengermination and pollen tube growth, or plants progressed toseed set at 15 °C, after which seeds were weighed, germinated,and seedlings grown on. The temperature responses of pollengermination and pollen tube growth were not always congruent,and varied between species, populations, and often between morphs(pin and thrum) in the distylous species. Nevertheless, optimaltemperature responses tended to be lower for vernal species(P. vulgarisandP. veris) and for subarcticP. scoticathan forlater flowering montane species. However, no relationship wasfound between pollen temperature response, and fertility. Thegreatest seed set occurred after legitimate pollination at 15°C in most cases; a flowering temperature of 26 °C tendedto impede seed set, except forP. scoticaand the low altitudepopulation ofP. farinosa. InP. veris, P. frondosaand the highaltitude population ofP. farinosa,some illegitimate pollen germinationand pollen tube growth occurred at 26 °C, but this did notlead to increased within-morph seed set in these self-incompatiblespecies at this relatively high temperature. Temperature atflowering frequently affected average seed weight, and inP.verisand two populations ofP. farinosathis attribute may havebeen influenced by seed number, the average seed weight of few-seededcapsules tending to be greater than for many-seeded capsules.A high seed weight might mitigate the disadvantageous effectsof low fecundity resulting from interactions with floweringtemperature. However, inP. vulgarisandP. scoticainteractionsbetween flowering temperature and seed weight may have other,undetermined, causes. The seed of four species germinated leastwell in standard conditions when set following a flowering temperatureof 6 °C, which tends to support the hypothesis that temperatureat flowering can affect seed physiology; in contrast the seedof the two upland populations ofP. farinosagerminated leastwell after flowering at 26 °C. We conclude that much morework is needed on interactions between temperature and reproductiveefficiency, but that preliminary indications suggest that aglobal increase in temperature at flowering might adverselyaffect the quantity and quality of seed set in some species.Copyright1998 Annals of Botany Company Distyly, pollen tube,Primula farinosa, Primula frondosa, Primula scotica, Primula veris, Primula vulgaris,reproduction, seed set, temperature.     

Modulation of Sucrose Content by Fructose 2,6-bisphosphate during Photosynthesis in Rice Leaves Growing at Different Light Intensities

Reddy, A. R. and Das, V. S. R. 1987. Modulation of sucrose contentby fructose 2,6-bisphosphate during photosynthesis in rice leavesgrowing at different light intensities.—J. exp. Bot. 38:828–833. The relationship between the rate of CO₂ fixation and sucroseconcentration in the leaves of rice (Oryza sativa L.) grownat different light intensities was investigated. Maximum sucrosecontent coincided with maximum rates of CO₂ fixation, achievedat a photon flux density of 1600 µmol m^–2 s^–1.The levels of sucrose and fructose 2,6-bisphosphate were alsocompared in the leaves under different light intensities. Fructose2,6-Msphosphate accumulated during growth at low light. Theactivity of fructose-6-phosphate 2-kinase was high in the leavesgrown at low light while that of fructose-2,6-bisphosphatasewas low. The activities of phosphoglucose isomerase and phospho-glucomutasewere slightly increased by growth at low light The activitiesof UDP glucose pyrophosphorylase were adversely affected invitro with increased concentrations of fructose 2,6-bisphosphatewhile those of sucrose phosphate synthase were moderately affected.Phosphoglucose isomerase and phosphoglucomutase were activatedby fructose 2,6-bisphosphate (8-0 mmol m^–3) by 12-15%.The results suggested that low light intensities during growthresult in an accumulation of fructose 2,6-bisphosphate whichmodulates the key enzymes of sucrose biosynthesis thus regulatingcarbon flow under conditions of limited photosynthesis. Key words: Oryza sativa, photosynthesis, sucrose synthesis, fructose 2,6-bisphosphate, light     

A Novel Isourazole Herbicide, Fluthiacet-Methyl, is a Potent Inhibitor of Protoporphyrinogen Oxidase after Isomerization by Glutathione S-Transferase

A novel isourazole herbicide, fluthiacet-methyl (methyl [[2-chloro-4-fluoro-5-[(5,6,7,8-tetrahydro-3-oxo-lH,3H-[l,3,4]thiadiazolo[3,4-a]pyridazin-l-ylidene)amino]phenyrjthio]acetate;experimental code name, KIH-9201) promoted the leakage of electrolytesfrom cotyledons of velvetleaf (Abtilon theophtasti Medic) andcotton (Gossypium hirsutum L.) plants that are sensitive tothis compound. It induced the accumulation of protoporphyrinIX in cotyledons of cotton and inhibited Chl biosynthesis incotyledons of velvetleaf and cotton at low concentrations (I₅₀values, 10–12 nM). Fluthiacet-methyl was converted toits urazole by glutathione S-transferase that had been partiallypurified from velvetleaf. The urazole inhibited protoporphyrinogenoxidase (Protox, EC 1.3.3.4 [EC] ) from some plants, including velvetleaf,at low concentrations (I₅₀ values, 5.1–11 nM), whereasfluthiacet-methyl was not as potent. The effects in vivo (electrolyteleakage and inhibition of Chi biosynthesis) of fluthiacet-methylwere correlated with the inhibition of Protox activity by theurazole and not with the action of fluthiacet-methyl itself.From these results, it is concluded that fluthiacet-methyl inhibitsProtox activity after conversion to the corresponding urazoleby glutathione S-transferase. It is in this way that fluthiacet-methylexerts its effect as a light-dependent peroxidizing herbicide. (Received November 1, 1994; Accepted March 6, 1995)     

The identification of flavonoids and the expression of genes of anthocyanin biosynthesis in the chrysanthemum flowers

In order to provide additional information on the coloration of chrysanthemum flowers, the flavonoid composition and the expression of six structural genes involved in anthocyanin pathway in the ray florets of a pink flowering (cv. H5) and two white flowering (cvs. Keikai and Jinba) Chrysanthemum grandiflorum cultivars were examined. HPLCDAD/ESI-MSⁿ analysis showed that cyanidin 3-O-(6″-O-malonylglucoside) and cyanidin 3-O-(3″,6″-O-dimalonylglucoside) were the two major flavonoids presented in H5, while white flowering cultivars contained flavones instead of anthocyanins. Nine flavone derivatives were detected in the three cultivars, the amount of each flavone varied upon cultivars, and seven of these were identified as luteolin 7-O-arabinosylglucuronide, apigenin 7-O-glucoside, luteolin 7-O-malonylglucoside, apigenin 7-O-malonylglucoside, chrysoeriol 7-O-malonylglucoside, acacetin 7-O-rutinoside and acacetin 7-O-malonylglucoside. The two white flowering cultivars showed similar total flavonoid content, which was about two fold higher than that in H5. A high expression of the genes encoding dihydroflavonol 4-reductase and 3-O-glucosyltransferase was detected only in H5 but not in Keikai or Jinba. Chalcone synthase, chalcone isomerase, flavanone 3-hydroxylase, and flavonoid 3′-hydroxylase were expressed in all flowers, suggesting that the lack of anthocyanin in white flowering cultivars cannot be due to any blockage of their expression.     

Flower-Inducing Activity of Water Extracts of Various Plant Species, in Particular Pharbitis nil

The crude water extracts of leaves of many plant species belongingto Spermatophyta and some belonging to Bryophyta induced floweringof Lemna paucicostata 151 (PI51) under continuous light, atthe concentrations equivalent to 0.1 to 10 mg fr wt leaf per10 ml culture medium (mg fr wt/10 ml). The extract of Salvinia(Pterydophyta) added together with the extract of Lemna at aconcentration lower than that necessary to cause flowering alsoinduced flowering. The activity of the water extracts of someplants varied considerably from experiment to experiment dueto unknown factors, but the extracts of Pharbitis nil strainViolet, a sensitive short-day plant, always showed a high activity,as did the extracts of Lemna paucicostata reported previously. The extract of Pharbitis cotyledons induced flowering of P151even at 0.3 mg fr wt/10 ml, and significantly promoted floweringof L. paucicostata 441 and 6746 at 1–3 mg fr wt/10 ml.Ex-udate from the cuttings of the seedlings was also active.However, neither the activity of the water extract nor thatof the exudate could be correlated with photoperiodic floralinduction. On the other hand, the extract of leaves or cotyledonshad higher activity (on a fr wt basis) than that of other organs,and the activity of the extract of cotyledons changed with theirage roughly in parallel with their photoperiodic sensitivity. (Received April 17, 1989; Accepted August 10, 1989)     

Synthesis and Turnover of {alpha}-Amylase in Cotyledons of Germinating Vigna mungo Seeds: Effects of Exogenously Applied End-Products and Plant Hormones

Pulse-chase experiments indicated that the higher levels ofa-amylase in detached and incubated cotyledons of Vigna mungothan those in cotyledons attached to the embryonic axis weredue to both faster synthesis and slower degradation of the enzymein the detached cotyledons than in the attached cotyledons.Levels of a-amylase in the cotyledons were examined in termsof possible effects of end-products and the effects of exogenouslyapplied plant hormones and growth regulators. Levels of a-amylaseactivity and content were reduced by high concentrations ofglucose and sucrose, and it is suggested that this effect wascaused mostly by osmotic stress and partly by end-product repression.The level of a-amylase was nearly twice that in controls after1 to 10µM GA₃ had been applied to the cotyledons. In addition,0.1 mM kinetin, 0.1 mM 2,4-D and 0.1 to 0.S mM naphthaleneaceticacid also increased the level by 34% to 66% as compared to thecontrol. ABA and uniconazole both prevented the synthesis ofa-amylase. (Received July 4, 1994; Accepted November 14, 1994)     

Effects of Temperature and Photoperiod on Phenological Development in Three Genotypes of Bambara Groundnut (Vigna subterranea)

Factorial combinations of four photoperiods (10, 11·33,12·66 and 16 h d^-1) and three mean diurnal temperatures(20·2, 24·1 and 28·1°C) were imposedon nodulated plants of three Nigerian bambara groundnut genotypes[Vigna subterranea (L.) Verdc., syn. Voandzeia subterranea (L.)Thouars] grown in glasshouses in The Netherlands. The photothermalresponse of the onset of flowering and the onset of poddingwere determined. The time from sowing to first flower (f) wasdetermined by noting the day on which the first open flowerappeared. The time from sowing to the onset of podding (p) wasestimated from linear regressions of pod dry weight againsttime from sowing. Developmental rates were derived from thereciprocals of f and p. In two genotypes, 'Ankpa 2' and 'Yola',flowering occurred irrespective of photoperiod and 1/f was controlledby temperature only, occurring sooner at 28·1 than at20·2°C. The third genotype, 'Ankpa 4', was sensitiveto temperature and photoperiod and f was increased by coolertemperatures and photoperiods > 12·66 h d^-1 at 20·2°Cand > 11·33 h d^-1 at 24·1 and 28·1°C.In contrast, p was affected by temperature and photoperiod inall three genotypes. In bambara groundnut photoperiod-sensitivitytherefore increases between the onset of flowering and the onsetof podding. The most photoperiod-sensitive genotype with respectto p was 'Ankpa 4', followed by 'Yola' and 'Ankpa 2'. Therewas also variation in temperature-sensitivity between the genotypesinvestigated. Evaluation of bambara groundnut genotypes foradaptation to different photothermal environments will thereforerequire screening for flowering and podding responses.Copyright1994, 1999 Academic Press Vigna subterranea (L.) Verdc., Voandzeia subterranea (L.) Thouars, bambara groundnut, phenology, photoperiod, daylength, temperature, flowering, podding     

Protein Bodies of Developing Seeds of Vicia faba

Changes in fine structure and starch, nitrogen, and solublesugar content were followed through to maturation in developingcotyledons of Vicia faba. Various ultrastructural changes wereobserved in the developing cotyledons, notably an increase inthe number of membrane-bound ribosomes which corresponded withthe onset of storage protein deposition. The build-up of storageprotein was shown to occur in the cytoplasm within membrane-boundvacuoles which subsequently became the protein bodies of themature seed, retaining the original tonoplast as the boundingmembrane of the protein body. Nuclei became lobed during thelater phases of maturation; phytoferritin was observed in plastidsof mature seeds. The deposition of reserves in the cotyledonswas complete by 85–90 days after flowering, followingwhich water was lost until the seed became hard and ‘ripe’by no days after flowering.     

Photosynthetic CO2-fixing activity in dark-grown spruce seedlings

Bicarbonate-dependent O₂-evolving activity in dark-grown cotyledonsof Picea abies was measured with an oxygen electrode with differentpreillumination times. The activity showed a slight linear increasewith increasing preillumination time. On the other hand, O₂-evolvingactivity (Hill activity) of chloroplasts prepared from preilluminateddark-grown cotyledons exhibited a characteristic change of asteep rise followed by a gradual increase with increasing preilluminationtime. The results obtained were discussed in connection withthe light activation of the latent, inactive O₂-evolving centerin dark-grown cotyledons. (Received December 8, 1978; )     

Structural requirements in heparin for binding and activation of FGF-1 and FGF-4 are different from that for FGF-2

Size- and structure-defined oligosaccharides from heparin, 2-O-desulphated(2-O-DS-) heparin, 6-O-desulphated (6-O-DS-) heparin, carboxy-reduced(CR-) heparin, and carboxyamidomethylsulphonated (AMS-) heparinwere utilized in characterizing the structural properties ofheparin to specifically bind to basic fibroblast growth factor(FGF-2) and to modulate the mitogenic activity of FGF-2 (Ishihara,M.et al., Glycobiology, 4, 451–458, 1994). The previousresults showed that both 2-O-sulphate groups and the negativecharge of the carboxy group in iduronate residues are requiredfor specific interaction with FGF-2, but the 6-O-sulphate groupsin N-sulphated glucosamine (GlcNS) residues do not influencethe interaction with FGF-2. In the present study, the same oligosaccharideswere fractionated on a FGF-1- or FGF-4-affinity column, andwere assessed as promotors of FGF-1- or FGF-4-induced proliferationof adrenocortical endothelial (ACE) cells and chlorate-treatedACE cells. The present results suggest that the smallest heparin-derivedoligosaccharide binding to these growth factors with the highestaffinity and promoting their mitogenic activities is a fullyN-sulphated decasaccharide enriched in 2-O- and 6-O- sulphateddisaccharide units. In contrast to our results with FGF-2, ahigh content of 6-O-sulphate groups in GlcNS residues is requiredfor specific interaction with FGF-1 and FGF-4. FGF-1 FGF-4 heparin heparan sulphate oligosaccharides     

Blue Light Mediated Regulation of {beta}-Amylase Activity in Mustard (Sinapis alba L.) Cotyledons

In the cotyledons of mustard (Sinapis alba L.) seedlings grownunder continuous blue light, ß-amylase activity increasedbetween 42–96 h from sowing and thereafter the ß-amylaseactivity abruptly declined. Preirradiation with blue light didnot increase the responsivity of the subsequent phytochrome-mediatedß-amylase increase in the cotyledons. The run-offkinetics of ß-amylase increase in seedlings transferredfrom blue light to darkness indicated that the components ofthe blue light-triggered signal chain are kinetically identicalto those of the phytochrome-mediated signal chain. Far-red reversibilityexperiments showed that the above blue light response is eithermediated by phytochrome directly or the blue light photoreceptorrequires the coaction of phytochrome. (Received November 11, 1987; Accepted March 23, 1988)