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1.
MURRAY SHEILAH; WOODBINE MALCOLM; WALKER THOMAS KENNEDY 《Journal of experimental botany》1953,4(2):251-256
1. Forty-three strains of moulds, selected from ten species,were examined to ascertain their capabilities as producers offat, when grown in four different solutions of nutrient inorganicsalts together with sucrose. The three highest yields of feltwere given by Penicillium javanicum van Beyma, P. Soppi Zaleski,and Aspergillus nidulans Eidam, in that order. The fat contenton felt weight was maximal at 34·8 per cent, with P.Soppi, at 28·4 per cent. with Fusarium lini(1), and at25·8 per cent. with A. nidulans; on sugar utilized itwas maximal at 11·4 per cent. with P. Soppi, at 7·9per cent, with A. nidulans, and at 5·6 per cent. withF. lini(1). 2. Other moulds considered worthy of further trial were P. spinulosum,P. aurantiobrunneum, F. graminearum, A. flavus, F. oxysporum,A. clavatus, and P. oxalicum. 相似文献
2.
- As part of a general investigation into the exchange of gasesbetween the bogbean, Menyanthes trifoliata, and its environment,determinations have been made of the composition of the internalatmosphere of the plant at five different levels, viz. leafyshoot, three successive portions of stem, and roots.
- Procedureis described for the analysis of small gas samplesusing a modificationof the Bonnier and Mangin apparatus.
- In darkness with thelower part of the plant surrounded by anatmosphere of nitrogen,it has not been possible to show thepresence of a regular downwardsgradient of oxygen, such aswould be expected on a basis ofnormal gaseous diffusion.
- Under these Air Top/Nitrogen Bottomconditions the roots areshown to contain between 12?5 and 17?5percent, of oxygen intheir intercellular gas system. The portionof stem immediatelyadjacent to the roots showed an oxygen levelof from 14?0 to18?0 per cent.
- In plants kept under NitrogenTop/Air Bottom conditions in thedark for 48 hours, the concentrationof oxygen in the rootsfell to a level of 3?1 per cent, or belowin three plants andto 6?o per cent, in a fourth. The oxygenconcentration in theadjacent lowermost part of the stem wasas high as 18?0 percent., depending on the degree of aerationof the solution bathingthe stem. It is suggested that thisdistribution of oxygen canbe related to the relative impermeabilityof roots and of stemendodermis to gaseous diffusion from without,and it is thoughtthat the major part of the oxygen supply tothe roots is transportedto them through the stelar air passages.
- Some evidence is presented to show that oxygen passes fromthelower parts of the plant into the medium surrounding it.
3.
- Apprehension over the adequncy of current techniques stimulateda detailed study of the time factor in the arsenate inhibitionof growth and respiration in excised stem and root sectionsof Pisum sativum.
- Growth inhibition by arsenate sets in veryslowly, its rateof onset being related to the molar concentration(C) of arsenateate by the relation where T50 is the time taken in hours to reduce the growthrateto 50 per cent of the control and K is a constant. An explanationof the physiological basis of this relationship is attempted.
- Estimates were made of the final steady growth rate (relativeto control) in various arsenate concentrations. The inhibitionscalculated from this rate are held to approximate to the truearsenate effect and are shown to be very different from thosecalculated from total growth measures.
- Respirationof growing stem sections is not inhibited by thelow arsenateconcentrations that inhibit growth. Some inhibitionis indicatedat high concentrations (3 ? 104M. and over)but onlyafter 15-20 hours of exposure.
- Two per cent sucrose has noeffect on the arsenate inhibiitionof stem growth. Sucrose,however, markedly stimulates respirationin stem sections, butthis stimulation is prevented by arsenate.
- The misinterpretationswhich may arise as a result of ignoringthe time factor in inhibitionstudies in excised organ sectionsare discussed and the desirabilityof constructing completegrowth curves in all such studies isstressed.
4.
- The organic acids present are citric, isocitric, and l-malic,with a small residue of unidentified acids.
- The diurnal variationin acidity is due chiefly to changes,in malic acid, with aparallel fluctuation shown by citric acid.Under these conditionsisocitric acid shows little change.
- The importance of carbondioxide during acidification is confirmed,and it is shown thatat room temperatures or higher the CO2produced in respirationis sufficient to produce maximum acidification.At lower temperaturesthe supply of CO2 limits acid production.
- In the absence ofoxygen no acidification occurs, but even smallquantities (approx.1 per cent.) are sufficient to cause someacid production.
- Completebalance-sheets are presented for acids, carbohydrates,CO2 andoxygen for leaves maintained in the dark at high andlow temperatures.As acids are produced there is a correspondingloss of carbohydrate(chiefly starch). A scheme of reactionsis suggested to explainthe experimental results.
5.
- Data are presented which show the effect of the natural stimulatingsolution on the respiration of the seeds of Striga hermonthica.
- The stimulating solution has been shown to enhance the aerobicrespiration of seeds exposed to it, compared with that of seedsto distilled water at the same temperature. This effect on therespiration of the seeds is quite independent of any previousmoisture-treatment of the seeds, and thus of germination.
- Themaximum anaerobic rate of carbon-dioxide output of air-dryseedsafter treatment with the stimulating solution may be upto fifteentimes greater than that of seeds moistened with distilledwater.The anaerobic respiration of air-dry seeds after exposuretothe stimulating solution is greatly reduced by 0?025 M. sodiumfluoride and 0?001 M. sodium monoiodoacetate.
- The stimulatingsolution has been found to have little effecton the anaerobicoutput of carbon dioxide from seeds which hadbeen moisture-treatedfor 6 days at 22? C. before treatmentwith the stimulating solution.
- No correlation could be established between the effects ofthestimulating solution on germination and respiration.
6.
A list of the determinations in this work is given below:
- Under standard conditions with a photoperiod, the generationtime is five days. The generation time is shorter in continuouslight.
- There are temperature-dependent cleavage and mitoticgradientswithin a colony.
- A diurnal peak of mitosis occurstwo hours before the onsetof darkness.
- Under standard conditions(a) the mitotic index rises to a maximumof 10 per cent, twodays after inoculation; (b) the mitotictime is ten minutes;and (c) the mitotic rate is 71 cells per103cells per hour atthe mitotic peak.
7.
- Solubilization of chioroplasts with a mixture of 1 per centDuponol C and 1 per cent Span 80 (3: 1) caused a destructionof activity in the HILL reaction, but the treatment broughtabout an increase by about 60 per cent in the rate of ascorbatephotooxidation in the presence of DPIP. Heating the broken chloroplastscaused a marked decrease in the photooxidation activity. Byadding surface- active agents to the boiled preparation, theactivity was restored up to almost 80 per cent of the originallevel.
- With colloidal suspensions of isolated chiorophylls,ascorbatewas only slightly photooxidized in the presence ofDPIP. Byaddi tion of the surface-active agents, the activitywas greatlyenhanced.
- Dependency of the photooxidation bywhole and solubilized chloroplastsand isolated chlorophylla on the presence of DPIP was examined.DPIP can serve as anintermediate electron carrier in solubilizedchloroplasts aswell as in whole chloroplasts.
- Effect of o-phenanthrolineon ascorbate photooxidation by thesethree preparations wastested. With solubilized chloroplastsand isolated chlorophylls,the addition of the inhibitor hadno influence on their ascorbatephotooxidation either in thepresence or absence of DPIP.
- Treatmentof whole chloroplasts with the surface-active agentsinducedan activity of photooxidation of cytochrome c. The electron-flowpattern for the photooxidation of ascorbate by whole and solubilizedchloroplasts was briefly discussed.
8.
The Diageotropic Behaviour of Rhizomes 总被引:5,自引:0,他引:5
- The geotropic behaviour of rhizomes of Aegopodium podagrariahas been investigated by time-lapse photographic recording usinginfra-red radiation in complete absence of light.
- They havebeen shown to be very sensitive to light. Even a singleexposurefor 30 seconds to red light evokes a characteristicresponsein which the rhizome first turns downwards and thenturns upagain to the horizontal position. The exposure to lightduringthe process of digging up the rhizomes and setting upin theapparatus has similar effects which die away after about24hours.
- After recovery from this initial light effect theycontinueto grow roughly horizontal if maintained in darknessor subjectedto infra-red radiation only. If inverted (turnedthrough 180?)the side which was lowermost during the inversiongrows forabout 2 hours relatively the more quickly, thus becomingconvex;then a rapid straightening and bending in the oppositedirectionoccurs. This is followed by further up-and-down movementswhichgradually die out and the rhizome then continues growingstraight.
- Inversion for 10 minutes also evokes an essentiallysimilarresponse, which begins about 20 minutes after the invertedrhizomehas been returned to its original position. The importanttheoreticalsignificance of this is discussed in the text.
- Displacementof rhizomes through angles other than 180? resultsin to-and-frobendings in which the side of the rhizome whichwas uppermostbefore the stimulus of displacement first becomesconvex. Therhizomes then turn gradually towards the horizontalplane.
- Rhizomeswhich have recovered from the initial light effectand are thusgrowing in darkness horizontally are caused toturn upwardswhen the air surrounding them is replaced by air+5per cent,carbon dioxide.
- The theoretical significance of these findingsis discussed.
9.
- Some recent works on the formation of oxalic acid by variousfungi are critically considered.
- The present work deals withthe role of oxalic acid in the metabolismof Aspergillus niger.
- When glucose solutions were supplied to preformed mats ofthefungus oxalic acid accumulated, attaining an equilibriumlevelwhich was not exceeded despite the presence of a considerableconcentration of glucose.
- When the glucose supplies were depletedthe oxalic acid concentrationfell steeply to a low level.
- Theconcentration of oxalic acid was dependent on the glucoseconcentration.In three separate series of experiments it wasshown that theoxalic acid concentration diminished with increasingglucoseconcentration.
- Similar results were obtained when the cultureswere rearedfrom spores on culture solutions with the normalamounts ofnutrient salts but different glucose concentrations.
- In all cases the CO2 output increased with the glucose concentration.
- When cultures were supplied with glucose+oxalic acid, theconcentrationof the latter fell steeply to the equilibriumlevel attainedon glucose only. In a culture receiving glucose+oxalicacid,with the oxalic acid concentration somewhat below thenormalequilibrium concentration, the formation of oxalic acidfromthe glucose ceased as soon as the equilibrium level hadbeenattained.
- When 1 per cent. oxalic acid only was suppliedto the fungusthe concentration gradually diminished to a lowlevel. When3 per cent. oxalic acid was supplied the rate ofacid utilizationsoon fell to low value.
- In several experimentsit was shown that the rate of CO2 outputwas higher from culturessupplied with glucose+excess oxalicacid than from culturessupplied with glucose only.
- The rate of oxalic acid carbonloss was always below that ofthe CO2 carbon output both incultures supplied with oxalicacid only and in cultures receivingglucose+oxalic acid.
- The cultures were incapable of utilizingneutral sodium oxalateand the presence of this substance hadno effecft on the ofCO2 output.
- The results indicate thatthe utilization of oxalic acid isassociated with the liberationof at least an equivalent amountof CO2.
- It is suggested thatthe utilization of oxalic acid is promotedby the presence ofglucose, thus accounting for the lower oxalicacid concentrationsand higher rates of CO2 output of cultureswith higher glucoseconcentrations.
10.
- The permeability of unplasmolysed cells of beetroot, v. CrimsonGlobe, was determined from the rate of water loss ofbeet slices on placing in sucrose solutions having O.P. greaterthan the suction pressure of the beet. The absolute values obtainedwere about 0?7µ3 water per µ2 cell-surface per hourper atmosphere osmotic pressure difference, i.e. 0?7 µ/hr./atm.
- The permeability of similar beet cells plasmolysed withintheircell walls was found to be about 13µ/hr./atm.
- Thepermeability of beet cells which had been plasmolysed andallowedto recover was shown to be approximately the same asthat ofunplasmolysed cells.
- The hypothesis is advanced that the increasein water permeabilityon plas-molysis is due to those partsof the plasma-membranewhich had formerly been pressed againstthe micelles of thecell wall becoming free and able to takepart in water transfer.
- The energy requirement for the maintenanceof an excess hydrostaticpressure of five atmospheres withina cell by its vital activitywas shown to be about one-tenthof the total respiratory energyreleased in freshly cut beetslices.
11.
- Two neutral plant hormones, one isolated recently from plants(3-indolylacetonitrile) and the other (3-indolylacetaldehyde)reported to be present in plants, are avaible as pure syntheticcompounds for investigation of their biological activities.This paper is mainly concerned with their effects on cellelongationin the Avena coleoptile
- 3-Indolylacetaldehyde is considerablyless active than 3-indolylaceticacid in the Avena straight-growthtest; for example, a 1.0 mg./l.solution of the aldehyde showsan activity equivalent to thatof a 0.1 mg./l. solution of theacid
- An acidic substance is produced in solutions of the aldehydeduring the period of assay. In some experiments it accountsfor all of the activity shown by the aldehyde solutions, onthe assumption that it is 3-indoylacetic acid, and in otherexperiments it shows a greater activity than that of the aldehydesolutions from which it was obtained. Therefore, it is concludedthat 3-indolylacetaldehyde, itself is either inactive or inhibitory.Acid production in aldehyde solutions in vitro is much lower,a fact which suggests that there is enzymatic oxidation of aldehydeto acid in the presence of coleoptiles.
- The activities of3-indolylacetaldehyde in the pea test andin root-inhibitionand of 3-indolylacetone in the straight-growthtest are brieflyreported.
- 3-Indolylacetonitrile is considerably more activethan 3-indolylaceaticacid in the Avena straight-growth test;for erample, a 0.1 mg./l.solution of the nitrile shows an activityequivalent to a 1.0mg./l. solution of the acid. The inhibitoryeffect at concentrationsabove 1.010.0 mg./l. is lesswith the nitrile than withthe acid.
- There is negligible productionof acid in solutions of the nitrileboth in vitro and in thepresence of Avena coleoptiles at temperaturesranging from 18?to 25? C. for varying lengths of time.The possibility of enzymaticconvesion of nitrile to acid insidethe cells of the coleoptileis discussed
- The activities of 3-indolylacetamide and of 2:4-dichlorophenoxyaceticacid and the corresponding nitrile are considered in this connexion
- The nitrile is destroyed by treatment with alkali but notbyacid. In the light of these results, it is desirable to re-examineprevious work on identification of auxins in plants by theiracid and alkali sensitivity. Evidence for the existence of thenitrile in a number of other plants is presented.
12.
- At appropriate concentrations both gibberellic acid (GA) and1-naphthalene-acetic acid (NAA) enhance the main axis growthof excised tomato roots grown in culture media containing sucroseat concentrations below 1 per cent. Lateral root extension growthis enhanced by GA at all sucrose concentrations tested; onlyat the lower sucrose concentrations is this effect observedwith NAA. Both GA and NAA increase the number of emergent lateralroots and this effect is most marked in media of low sucrosecontent. Both GA and NAA at higher concentrations inhibit rootgrowth but NAA exhibits its full range of growth effects overa much narrower concentration range than GA.
- GA, like NAA,speeds up the loss of meristematic activity whichoccurs whenindividual meristems are repeatedly subculturedin media containing1 per cent, or higher concentrations ofsucrose.
- The promotionof main axis growth by both GA and NAA involvesenhanced cellelongation and cell division. At a moderatelyinhibitory concentrationGA reduces both cell elongation andcell division; this is notthe case with NAA.
- Gibberellins A1, A2, and A4 resemble GA(gibberellin A3) intheir growth effects. Allogibberic acidlike G A promotes lateralroot extension growth but causes markedinhibition of root growthat a much lower concentration thanGA.
13.
- The variety Phulwa was worked upon for respiratory studiesandgrowth response to dormancy-breaking hormones. The hormoneswere used in single and double doses.
- The respiratory studiesreveal that ethylene chlorhydrin affectsonly the bud areasand not the non-bud areas.
- The intensity of the effect ofthe hormone progressively decreasesin the deeper layers ofcells, till finally no effect is visiblein the cells of thepith areas.
- A distinct correlation exists between the respiratoryintensityand dormancy.
- Of the two hormones used the respiratoryrates recorded forN. ethylene chlorhydrin treated tubers, givenin single anddouble doses, were the highest. Similarly thegrowth responseto both the doses showed the maximum reductionof the dormancyperiod, 01 N. ethylene chlorhydrin treatmentswere not effectivein breaking the dormancy or in significantlyaltering the rateof respiration.
- Treatments with 05 percent, ammonium thiocyanate given insingle dose showed the lowestrespiratory rates and the germinationrecords showed no differenceover the control. With the doubledose a gradual rise in therespiratory rates was observed. Thegermination records alsoshowed an earliness of 20 and 22 daysover the control and single-dosetreatments respectively.
- Treatments with 2 per cent, ammoniumthiocyanate depressed germination.The respiratory rates recordedwere also low.
- In general the double-dose treatments showedbetter resultsthan the single-dose treatments. Also, treatmentson 3 weeksold tubers were more effective than on 6 weeks oldtubers.
14.
The rooting responses of isolated leaves of the dwarf Frenchbean and the ivy were studied by applying solutions of growthsubstances to the petiole: ß-indolyl-butyric acid(I.B.A.) for the former and -naphthyl-acetic acid (N.A.A.) forthe latter. The following factors were investigated:
- The variation in response of successive leaves from the apextowards the base of the plant.
- The optimal concentrationsof the growth substances and therelation between duration ofapplication and concentration.
- The relation of age of theleaf and optimal concentration(ivy).
- The nutritive factorsconcerned in the response were studied,(a) by varying periodsof contact between lamina and petiole,(b) by varying durationof light, (c) by varying the amountof light, and (d) by feedingwith sucrose and asparagine.
15.
- The metabolism of a citric-acid-forming strain of A. nigerwhengrown on a glucose-acetate medium has been investigated.
- Acetate greatly accelerated the rate of utilization of glucose.
- Citric acid production from glucose was much increased bythepresence of acetate.
- The formation of oxalate from glucose-acetatecultures was muchless than from acetate alone.
- In some cultureslarge amounts of glucose and acetate were consumedbut no acidicproducts were formed.
16.
- Chlorella ellipsoidea was grown synchronously and the changesin content of various vitamins during the algal life cycle werefollowed either by chemical or microbiological assay methods.
- In terms of µg per gram of cell dry weight, the contentof some vitamins (niacin, biotin, inositol and choline) remainedalmost constant throughout the algal life cycle, while thatof others (vitamin B6-complex, pantothenic acid, folic acid,thiamine and riboflavin) was found to decrease more or lessmarkedly during the "growing phase" and increase at later phasesof "ripening". The content of p-aminobenzoic acid increasedonly at an early stage of "ripening", and that of ascorbic acidincreased only at the stages in which photosynthesis occurredmost actively.
- These results were discussed in an attemptto interprete theirrelationship with the previously reportedobservations pertainingto the physiological and biochemicalevents occurring in thelife cycle of the alga.
17.
- 3-Indolylacetonitrile is more active than 3-indolylacetic acidin the Avena straight-growth test, but less active in the Avenacurvature test at comparable concentrations. Reasons for thisare discussed, and results of previous work on plant extractsusing the curvature test as a means of assay are considered.
- Transport of both the acid and the nitrile is polar, fromapexto base of the coleoptile. The nitrile can reach the growingcells as easily, and possibly more easily, than the acid. Thesignificance of these findings for a theory on the mechanismof action of the nitrile is discussed.
- The nitrile is inactivein the pea curvature test and straight-growthof pea stem sectionsexcept at high concentrations. It is alsoinactive or only slightlyactive in lateral bud inhibition,root initiation, and petioleabscission at the concentrationstested.
- It is less activethan the acid in root inhibition in cress,but approximatelyas active in Avena. It is approximately asactive as the acidin parthenocarpic fruit development, andinitiation of cambialactivity.
- The significance of these results is discussed.
18.
- Pharbitis plants were cultured on a nutrient medium containing5% sucrose or no sucrose. They were subjected to various lightconditions at temperatures of 10? or 20?.
- All the plants culturedon the sucrose-medium at 10? initiatedflower buds independentlyof the light to which the plants wereexposed.
- Plants culturedon the sucrose-free medium at 10? initiatedflower buds undershort photoperiods, but did not under continuousillumination.
- Plants cultured on the sucrose-medium at 20? initiated flowerbuds in total darkness or under short photoperiods regardlessof the intensity and quality of the light, but those subjectedto continuous illumination did not.
- Plants cultured on thesucrose-free medium at 20? initiatedflower buds under shortphotoperiods but did not initiate themunder continuous illumination.
19.
- In the dark, HNG (habituated Nicotiana glutinosa) and NG cellsscarcely grew at 15?C, and the difference between the growthrates of HNG and NG was small at both 15?C and 25?C.
- The stimulatoryeffect of light (4000 lux) on the cell growthrate was higherat 25?C than at 15?C for both HNG and NG.
- Light exerted muchmore effect on the growth rate of HNG thanof NG.
- The thermaleffect was higher in the light than in the darkfor both HNGand NG, and was somewhat greater on NG than onHNG.
- The synergisticeffect of light and temperature on cell growthwas greater onHNG than on NG.
- HNG contained more chlorophyll than NG.
- Inaddition, there was little difference between the friabilitiesof cell groups of HNG and NG.
20.
- The haploid chromosome number in Tamarix ericoides Rottl., reportedfor the first time, is twelve.
- The archesporial cell is single,rarely double.
- There is no tetrad formation, division of themegaspore mother-cell;instead, a four nucleate embryo-sac results.
- The nuclei are originally arranged in a cruciform type, butlater form a I+3 arrangement.
- As a result of the third division,the embryo-sac is again four-nucleate,with two haploid nucleiat the micropylar end and two triploidnuclei at the chalazalend.
- The cells of the embryo-sac are formed at the end ofthe fourthdivision, the embryo-sac thus representing the sixteennucleatecondition.
- The development of the embryo-sac of Tamarixericoides conformsto the Fritillaria-type.
- The endospermis free nuclear, and the embryo is characteristicin developinga massive suspensor and a large pad of cellulartissue fromthe proximal cell.
- Double embryo-sacs and the occurrence ofpolyembryony are reportedfor the first time in the family.