M. MCCREADY AND W. HAS SIDKURSANOV (8) utilized this fact to study the synthetic and hydro-lytic actionsofinvertase inliving planttissues byhis "vacuuminfiltration" method. This method

TRANSFORMATION OF SUGARS IN EXCISED BARLEY SHOOTS

R. M. MCCREADY AND W. Z. HAS SID

(WITH TWO FIGURES)

Introduction

NELSON and AUCHINCLOSS (10) working with potato tissue showed thatsucrose is synthesized from glucose or fructose rather than from starch ashas been supposed by some investigators. That such a conversion occursin plant metabolism has also been shown by VIRTANEN and NORDLUND (14)in red clover and wheat plants, and more recently by HARTT (3) in detachedsugar cane leaves.

Since sucrose, consisting of a glucose and fructose molecule, can readilybe synthesized from either of these monosaccharides, it may be assumedthat such synthesis involves a preliminary conversion of each of these hexosesugars into the other. The fructose component of the sucrose moleculeexists in the furanose form (unstable y form with the five-membered ring)and is different from the six-membered fructose (pyranose configuration)from which it can be synthesized. The plant apparently also possesses amechanism to render this transformation possible. The fact that sucrose issynthesized when plants are artificially supplied with glucose or fructosecan serve indirectly in the study of transformation of other hexoses in theplant into these monosaccharides. If, for example, synthesis of sucrose isobserved after supplying the plant with mannose, it could be assumed thata preliminary conversion of the latter into glucose and fructose must takeplace before the synthesis of sucrose occurs. The hexoses that are knownto occur naturally in plants are: d-glucose, d-fructose, d-mannose, and d-galactose; of these the last two have not been detected in the free state andare found in plants only as units in polysaccharides. If, as it is generallyassumed, some form of glucose is the first product of photosynthesis, theplant should possess a mechanism whereby this molecule is transformed intomannose or galactose before the synthesis of the corresponding polysac-charide can be possible.

In this investigation, using the infiltration method (8), the followingcompounds were artificially supplied to barley plants: d-glucose, d-fructose,d-mannose, d-galactose, sucrose, lactose, maltose, I-arabinose, d-xylose, man-nitol, sorbitol, gluconic acid, pyruvic acid, and glyceric aldehyde. The in-crease of sucrose was observed after certain periods of time to determine theability of the plant to transform these compounds into glucose or fructoseand, if possible, to ascertain the mechanism of this transformation.

599

Copyright (c) 2020 American Society of Plant Biologists. All rights reserved.

PLANT PHYSIOLOGY

Experimental methods and resultsIt is well known that detached leaves or plants detached from their roots

are capable of carrying on metabolic activities for a considerable length oftime. KURSANOV (8) utilized this fact to study the synthetic and hydro-lytic actions of invertase in living plant tissues by his "vacuum infiltration"method. This method was effectively used in our investigation of sugartransformations in barley plants. Barley plants were grown in halfstrength HOAGLAND'S culture solution for about 3 weeks. The plants werecut above the roots (only the shoots were used) and 5-gm. samples of thefresh material were immersed into beakers containing 5 per cent. sugarsolution. The beakers with contents were placed into a desiccator andevacuated to about 20 mm. of mercury for 5 minutes. After evolution ofthe air bubbles from the leaves had ceased, air was slowly re-admitted intothe desiccator. The intercellular spaces were thereby replaced by the sugarsolution. The plant material was then taken out of the beakers, andallowed to remain in the dark at about 220 C. in an atmosphere saturatedwith water vapor for a certain period of time. The material was thenthoroughly washed with water, the soluble sugars extracted with boiling80 per cent. alcohol and analyzed for reducing sugars by oxidation withferricyanide and titration with ceric sulphate (6, 7) before and after hy-drolysis with invertase. Sucrose was determined by the difference. Blanksamples of 5 gm. fresh weight of the same plant material infiltrated withwater were run simultaneously. In all cases the samples were run in dupli-cate. The results are expressed on the basis of fresh weight.

Preliminary experiments showed that barley samples infiltrated with5 per cent. solutions of glucose, fructose, mannose, galactose, lactose, andmaltose, and allowed to remain for several hours showed a considerable gainin sucrose over the blank samples infiltrated with water. This indicatedsynthesis of sucrose by the plant from these sugars. Since the synthesiswas measured by difference in sucrose between the sugar and the waterinfiltrated samples, the production of sucrose in these experiments was sub-ject to doubt. It should be borne in mind that besides synthesis of sucrose,other metabolic processes go on simultaneously in the plant. While syn-thesis of sucrose is taking place, glucose or fructose is being used up inrespiration, and in order to maintain a proper state of equilibrium a certainamount of sucrose is hydrolyzed back into these monosaccharides. In thesamples infiltrated with solutions of monosaccharides, there is an excess ofhexose sugars available for respiration. The hydrolysis of sucrose intoglucose and fructose will therefore tend to decrease, and the equilibriumrepresented by the equation: glucose + fructose & sucrose will be shiftedto the right. In the water infiltrated samples the tendency of the sucroseto hydrolyze is greater, and the equilibrium will be shifted to the left. The

600


MCCREADY AND HASSID: SUGARS IN BARLEY ROOTS

difference in sucrose content between the sugar infiltrated sample and theblank would therefore not represenit the true value of the amount of sucrosesynthesized. To avoid this difficulty a procedure was adopted to depletethe sucrose to a low level, by respiring the barley plants for a certain lengthof time previous to infiltration with the sugar solutions.

The tendency of sucrose to be depleted first during respiration, while thereducing sugars are maintained more or less at a constant level, is shown bythe results in table I.

TABLE ICOMPARISON OF SUCROSE AND REDUCING SUGARS 1N EXCISED BARLEY SHOOTS AFTER

RESPIRATION FOR 24 AND 48 HOURS IN THE DARK AT 220 C.

SUCROSESAMIPLE DESCRIPTION OF SAMPLE REDUCING TOTAL SUCROSE OF FRESH

SUGARS SUGARS SUCRSE RERS5GMMATERIAL

I% % No 111g.1 Initial untreated 0.87 1.10 0.22 11.02 Depleted (24 hours)

in water 0.90 0.90 0.0 0.03 Depleted, then water

infiltrated 24 hours 0.77 0.77 0.0 0.04 Depleted, then infil-

trated 5% glucose24 hours 1.09 1.43 0.32 16.0

The untreated sample, no. 1, analvzed immediately after harvesting, con-tained 0.87 per cent. reducing sugars and 0.22 per cent. sucrose or 11.0 mg.per 5 gm. of fresh weight. After the plants respired in the dark for 24hours the reducing sugars remained at about the same order of magnitude,0.9 per cent. but the sucrose was all depleted (no. 2 sample). When therespired sample, no. 3, was infiltrated with water and allowed to remainfor another 24 hours, the reducing sugars came down to 0.77 per cent. Adecrease in the reducing sugars could be observed only after all the sucrosewas exhausted. Sample no. 4, which was infiltrated with 5 per cent. glu-cose after all the sucrose was depleted, synthesized 16.0 mg. of sucrose per5 gm. of fresh weight in 24 hours and contained 1.09 per cent. reducingsugars.

Table II represents results of experiments with barley shoots which re-spired in the dark for 24 hours to a low level of sucrose of 1.0 mg. per 5 gm.of fresh weight. Samples of these plants were then infiltrated with 5 percent. solutions of glucose, fructose, mannose, galactose, and arabinose andallowed to remain for 18 hours. As shown in the table, sucrose was formedfrom glucose, fructose, mannose, and galactose but niot from arabinose.The relative rate of sucrose synthesis in the plant from these sugars with

601


PLANT PHYSIOLOGY

TABLE IISUCROSE SYNTHESIS IN SUCROSE DEPLETED BARLEY SHOOTS AFTER INFILTRATION WITH

5 PER CENT. SOLUTIONS OF VARIOUS MONOSACCHARIDES AND ALLOWED TOREMAIN FOR 18 HOURS AT 220 C.

SUCROSE RELATIVESAMPLE DESCRIPTION OF SAMPLE REDUCING TOTAL SUCROSE PER 5 GM. RATE OF

SUGARS SUGARS OF FRESH SUCROSEMATERIAL FORMATION

% % % mg.1 Initial untreated 0.86 1.14 0.27 13.5 ...........2 Depleted (24 hours)

in water 0.78 0.80 0.02 1.0 ...........3 Depleted, then water

infiltrated 24 hours 0.58 0.60 0.02 1.0 ....4 Glucose infiltrated 0.50 0.97 0.45 22.5 100.05 Fructose infiltrated 0.50 0.83 0.31 15.5 67.56 Mannose infiltrated 1.64 1.89 0.24 12.0 51.27 Galactose infiltrated 1.73 1.88 0.14 7.0 27.98 Arabinose infiltrated 1.52 1.52 0.0 0.0

respect to glucose was as follows: fructose, 67.5 per cent.; mannose, 51.3per cent.; galactose, 27.9 per cent.

Figure 1 gives the results from 8 samples of barley plants which wereinfiltrated with 10 per cent. glucose solution, analyzed for sucrose imme-diately, and then the synthesis of sucrose followed at different intervals for48 hours.

o60 ~~~~~A-GLUCOSE INniLTRATED5O0

34O30 .

20-cr~ ~cc.- |u 1 B-WATER INWILTRATED

10 20 30 40 50TIME IN HOURS

FIG. 1. Synthesis of sucrose from glucose.

As seen from curve A the maximum amount of sucrose was synthesizedafter about 18.5 hours (59 mg. per 5 gm.). From then on the amount ofsynthesis gradually diminished. Line B shows the depletion of sucrose.The entire content -of sucrose was depleted from an equivalent sample ofbarley within 24 hours. Curve A therefore represents the synthesis ofsucrose above the amount depleted during respiration.

The synthesis of sucrose from galactose is sbown in figure 2.

60(2



25

°I 20 ItS2I-

15 BK-K

5 10 15 20TME IN HOURS

FIG. 2. Synthesis of sucrose from galactose during 20 hours. A, not depleted ofsucrose before infiltration. B, depleted. C, recrystallized galactose and sample depletedbefore infiltration.

Galactose was infiltrated into one set of barley samples, originally con-taining 23.5 mg. per 5 gm. of fresh weight, analyzed immediately and thesynthesis of sucrose followed for 18 hours. Since the rate of sucrose forma-tion from galactose is not very great (shown in table II, 27.9 per cent. asfrom glucose) it did not exceed the hydrolysis which was apparently simul-taneously taking place during respiration. Therefore, not a gain butrather a slight loss in sucrose could be observed, as shown by slightly down-ward curve A. In a second set of barley plants, however, in which thesucrose had been previously exhausted to a low level, a distinct gain ofsucrose could be observed from galactose, as shown by curve B.

Since commercial galactose is usually made by hydrolysis of lactose,which consists of one molecule of galactose and one molecule of glucose, itwas tested for purity with respect to glucose contamination. A fermenta-tion test with a pure culture of yeast (Torula monosa) showed that thegalactose contained almost 1 per cent. glucose. The commercial galactosewas therefore purified by dissolving in water and fermenting the glucoseand then crystallizing from alcohol. A fermentation test on this purifiedgalactose showed no glucose contamination. Curve C shows sucrose forma-tion when purified galactose was used. This eliminates the possibility thatthe sucrose could have been formed from the small amount of glucose foundas an impurity and not from the galactose.

603


PLANT PHYSIOLOGY

Table III shows the results of experiments in which barley plants wereinfiltrated with solutions of xylose, maltose, lactose, mannitol, sorbitol,glyceric aldehyde, and the sodium salts of gluconic and pyruvic acids. Inthese experiments the plants were depleted of sucrose in the usual mannerbefore infiltration with the solutions. A sample of plants was also infil-trated with glucose in order to determine the rate of sucrose formation fromthe particular sugar with respect to glucose.

TABLE IIISUCROSE SYNTHESIS IN SUCROSE DEPLETED BARLEY SHOOTS AFTER INFILTRATION WITH 5 PER

CENT. SOLUTIONS OF VARIOUS SUGARS OR RELATED SUGAR COMPOUNDS ANDALLOWED TO REMAIN FOR 20 HOURS AT 220 C.

SUCROSE REATIEOREDUCING ToTALSURE PER 5 GM.RAEOSAMPLE DESCRIPTION OF SAMPLE SUGARS SUGARS FRESH SUCROSE

WEGHPORMA-

WEGT TION

No No No mng.1 Initial-after depletion 1.23 1.43 0.19 9.5 ............2 Depleted, then water in-

filtrated (20 hours) 0.79 0.90 0.10 5.0 ...........3 Glucose infiltrated 1.80 2.58 0.74 37.0 100.04 Xylose infiltrated 2.34 2.47 0.12 6.0 .........5 Maltose infiltrated 2.09 2.90 0.77 38.5 105.06 Lactose infiltrated 2.03 2.60 0.54 27.0 68.87 Mannitol infiltrated 0.79 0.92 0.12 6.0 ............8 Sorbitol infiltrated 0.60 0.67 0.07 3.5 ............9 Glyceric aldehyde 1.00 1.40 0.38 19.0 43.8

10 Gluconic acid (Na salt) 1.20 1.37 0.16 8.0 ............11 Pyruvic acid (Na salt) 0.70 0.88 0.17 8.5 ............

Sucrose was formed in the barley plants from maltose, lactose, andglyceric aldehyde. The rate of sucrose synthesis from these sugars withrespect to glucose is 105 per cent., 68.8 per cent. and 43.8 per cent. respec-tively. It is of interest to note that the disaccharides, maltose and lactose,are used by the plants for the synthesis of sucrose and that maltose is util-ized to about the same extent as glucose. Apparently the barley plant pos-sesses enzymes which readily hydrolyze these disaccharides to their respec-tive monosaccharides, which are then used for sucrose synthesis. Xylose,mannitol, sorbitol, and the salts of gluconic and pyruvic acids were notutilized. The utilization of a pentose sugar for sucrose synthesis wouldrequire an additional carbon atom for the preliminary formation of a hex-ose. Evidently the barley plant does not possess a mechanism for such atransformation. There are apparently also no enzymes which could reducesugar acids or oxidize sugar alcohols to their corresponding aldohexoses.The formation of a considerable amount of sucrose from glyceric aldehydeshows that the plant is able to condense this tricarbon compound to glucoseor fructose.

604



In table IV the results with etiolated plants are presented. The plantswere germinated and grown in a culture solution in the dark for about 2weeks; they were light yellow and absolutely devoid of chlorophyll.

TABLE IVSUCROSE SYNTHESIS IN ETIOLATED BARLEY SHOOTS INFILTRATED WITH 5 PER CENT. SOLU-

TIONS OF VARIOUS SUGARS, AFTER RESPIRATION IN THE DARK FOR 24 HOURS,AND THEN ALLOWED TO REMAIN FOR 18 HOURS AT 220 C.

SUCROSE

SAMPLE DESCRIPTION OF SAMPLE REDUCING TOTAL SUCROSE PR HSUGARS SUGARS OF FRESH

WEIGHT

No No % mg.1 Initial untreated 0.50 0.50 0.0 0.02 Depleted for 24 hours 0.42 0.42 0.0 0.03 Glucose infiltrated 1.30 1.83 0.50 25.04 Sucrose infiltrated 1.14 1.66 0.49 24.55 Maltose infiltrated 0.87 1.41 0.51 25.56 Galactose infiltrated 1.30 1.58 0.27 13.5

Sucrose formation takes place in barley plants which are devoid ofchlorophyll. The etiolated plants did not contain any sucrose (sampleno. 1). Sample no. 4, infiltrated with sucrose, did not raise the sucrosecontent above the one infiltrated with glucose; instead, it raised the valueof reducing sugars. As shown in the table IV, the value of the reducingsugars in the blank sample after respiration for 24 hours was 0.42 per cent.After being infiltrated with glucose and allowed to remain for 18 hours, therespired barley plants contained 0.50 per cent sucrose and 1.30 per cent.glucose. The plants infiltrated with sucrose and allowed to remain for thesame period of time, contained about the same amount of sucrose, 0.49 percent., and 1.14 per cent. reduciing sugars. It appears that an excess ofreducing sugars induces synthesis of sucrose, while an excess of sucrosefavors the reverse process, hydrolysis.

In order to show whether the synthesis of sucrose from a monosacchariderequires oxygen, the following experiment was carried out: barley samplesinfiltrated with 5 per cent. glucose were placed in 3 desiccators. The firstcontained air saturated with water vapor, in the second the air was replacedby oxygeni, anid in the third by nitrogen. The plants were allowed toremaini in the dark for 24 hours. Originially they contained 47.5 mg. ofsucrose per 5 gim. of fresh weight, and respired for 36 hours to a level of19.5 mg. The results are shown in table V.

Sample no. 4, in the air, synthesized 58.5 mg. per 5 gm. of tissue. Whenthe air was replaced by nitrogen only 22.5 mg. of sucrose per 5 gm. of tissuewere sy-nthesized, a value slightly higher than the blank, 19.5 mg. Sampleno. 3, in pure oxygen synthesized 63.0 mg. of sucrose per 5 gm. of tissue, a

605


PLANT PHYSIOLOGY

TABLE VSUCROSE SYNTHESIS IN BARLEY SHOOTS INFILTRATED WITH 5 PER CENT. SOLUTIONS OF

GLUCOSE AND EXPOSED TO AN ATMOSPHERE OF AIR, NITROGEN,AND OXYGEN FOR 24 HOURS AT 220 C.

SUCROSESAMPLE DESCRIPTION OF SAMPLES REDUCING TOTAL SUCROSE PER 5 GM.

SUGARS SUGARS OF FRESHWEIGHT

% No % mg.1 Initial after deple-

tion (in air) 1.37 1.78 0.39 19.52 Nitrogen 2.00 2.47 0.45 22.53 Oxygen 2.03 3.36 1.26 63.04 Air 2.10 3.33 1.17 58.5

value slightly higher than in air. This indicates that the synthesis ofsucrose is an aerobic, or at least partly aerobic, process.

Invertase is generally considered to be specific for sucrose. The ques-tion of strict specificity of this enzyme is of prime importance in this inves-tigation, since the conclusion that sucrose is synthesized from suppliedmonosaccharides rests entirely upon this assumption. There is a possibil-ity that a compound other than sucrose might be formed which could behydrolyzed by invertase. For example, when the plant is supplied withmannose or galactose, some non-reducing disaccharide might be formedwhich would also be subject to the attack of invertase. The release of freemonosaccharides would produce a high reducing value similar to thehydrolysis of sucrose. If the reducing value, after invertase hydrolysis, isin reality due to sucrose (since sucrose contains a molecule of fructose) halfof the increase of that value should be approximately equal to a correspond-ing increase in fructose. To verify this point, barley plants were infiltratedwith 5 per cent. solutions of glucose, mannose, and galactose, and the in-crease in sucrose obtained by the invertase method was compared with theincrease in fructose determined by ROE'S method (11).

The results in table VI show that, after supplying galactose or mannose,the increase in the reducing value, by hydrolysis with invertase, correspondsapproximately with the increase in fructose. This indicates that the carbo-hydrate synthesized is sucrose.

DiscussionThe synthesis of sucrose in barley when either glucose, fructose, man-

nose, or galactose is supplied, indicates that there is a mechanism in theplant, which renders the conversion of these monosaccharides possible.HARTT (4) working with blades of sugar cane found that mannose was notutilized to form sucrose. The power of interconversion of the differentmonosaccharides apparently is dependent on the enzymic system and varies

606



M E-2(E- )

W~Dr12 04 qrl ,

E0 Oo 5 $ : t 6 -.1;V CCKI Coo

A3~~~~~~~~tf> t- r- L-.':ot 't

X w0 n O O C6 C;O

C; C; C*

o °

El Z t-r- 00 r-i cto 00 t-q 00O

O O C 1" 0i cli HicliEr-IH .4&'z zI

4.1 4C1 Ce C 4D-.

Z¢Z< cs cs ca~~~~.c'J CQ CQ

z, 4.1 z4. C d C

cd ce q eoo o )C

X :;, ~~~~e we 3=0 H n C: t > > > t E!i

r--C'm '14L-.1c m .-r-

607

z

E-l

0

z

0

a

;4

0

E-4

E-4

z

0 E

0Z

0

E-l

r-I:

El4

z

0

00zW


PLANT PHYSIOLOGY

with different plants. The mutual interconversion of glucose, fructose,and mannose can be accomplished in vitro in very dilute alkaline solutionthrough the LOBRY-BRUYN enolic transformation. Because of the ease withlwhich glucose and fructose are initerconverted in plants, it is considered pos-sible that the transformation takes place through this mechanism. The factthat mannose was also found to be converted to glucose and fructose in thebarley plant strengthens the view that the interconversion of these threemonosaccharides in the plant takes place by the mechanism of enolization,but there is still no experimental evidence to support this assumption. Itis eveni more difficult to account for the transformation of galactose intoglucose, since this sugar has no common enolic form with glucose or frue-tose. The theoretically possible chang,e of position of the fourth hydroxylgroup in the glucose molecule by the mechanism of the WALDEN il1version1,whereby it could be coniverted inito galactose, also has no experimentalproof.

The existence of hexosephosphates in plants shown by several investi-gators (1, 7, 13) in recent years strongly indicates that phosphorus playsan important role in the mechanism of sucrose formation. The isolation ofa mixture of glueose and fructose-phosphoric acid esters from pea leaves byone of the writers (7) suggests that phosphorylation of the glucose andfructose components is probably a necessary step in the sYnthesis of sucrosein the plant. Support of this view can be found in the work of KURSANOVand KRYUKOVA ('9). These authors showed that synthesis of sucrose inchicory and sugar beet leaves was always accompanied by an accumulationof phosphoric esters, also the synthesis of esters by sucrose synthesis.Under conditions of phosphate deficiency the capacity of the plant to syln-thesize sucrose decreased conisiderably. The introduction of phosphate insuch plants restored their normal synthetic capacity. SYSSAKYAN (12) hasalso found that in the case of phosphorus-starved sugar beet leaves, thesynthesis of sucrose was inihibited to a considerable extent as compared withniormal planits. HANES'S (2) recent important contribution, that of syn-thesizinog starch from glucose-l-phosphate in the presence of phosphorylasefrom potato tubers, demonstrates the important role of phosphorus in themechanism of carbohydrate synthesis. It is suggested that in the interconi-version of monosaccharides some intermediate phosphorylated compoundmight also be involved.

Mannitol, sorbitol, and gluconiic acid were not utilized by barley to formsucrose. Apparently the plant did not contain any enzymes which couldoxidize the sugar alcohols or reduce the sugar acid. The formation ofglucose from glyceric aldehyde indicates that sugars may be formed fromtricarbon atom compounds containing a reducing group.

608



Summary

1. Sucrose can be synthesized in barley plants when either of the follow-ing monosaccharides are supplied: glucose, fructose, mnannose, and* galac-tose. It is therefore evident that the plant possesses a mechanism to con-vert these monosaccharides into glucose or fructose.

2. Maltose and lactose can also be utilized by barley for sucrose forma-tion. The plants, apparently, possess enzymes which are able to hydrolyzethese disaccharides to their respective monosaccharides, which are thenused for the synthesis of sucrose.

3. Synthesis of sucrose from monosaccharides can take place in etiolatedplants in the dark. The process is therefore independent of light and doesnot require chlorophyll.

4. Arabinose, xylose, mannitol, sorbitol, anid gluconic and pyruvic acidswere not utilized by the plant for sucrose formation.

5. When excised barley shoots respired for 24 hours the sucrosegradually diminished, apparently due to hydrolysis, but the reducing sugarsremained approximately at a constant level throughout that period. Itwas only after the sucrose was entirely depleted, that a diminlution in thereducing sugars could be observed. It was also shown that an excess ofreducing sugars induces synthesis of sucrose, while an excess of sucrosefavors the reverse process, hydrolysis.

6. Synthesis of sucrose did not occur without the presence of oxygen,which indicates that this process is aerobic.

The authors are indebted to PROFESSOR D. R. HOAGLAND for his interestand valuable suggestions during the course of this investigation.

DIVISION OF PLANT NUTRITIONUNIVERSITY OF CALIFORNIA

BERKELEY, CALIFORNIA

LITERATURE CITED

1. BURKARD, J., and NEUBERG, C. Zur Fracre niach der Entstehung desRohrzuckers. Biochem. Zeitschr. 270: 229-234. 1934.

2. HANES, C. S. Enzymic synthesis of starch from glucose-l-phosphate.Nature 145: 348-349. 1940.

3. HARTT, C. E. The synthesis of sucrose by excised blades of sugar cane.The Hawaiian Planters' Record. 41: 33-46. 1937.

4. . Report of enzyme laboratory. Proc. Hawaiian SugarPlanters' Association. Rept. committee in charge Exp. Sta. 58:111-116. 1938. (Pub. 1939).

5. HASSID, W. Z. Determination of reducing sugars and sucrose in plantmaterials. Iiid. Eng. Chem. Anial. Ed. 8: 138-140. 1936.

609


PLANT PHYSIOLOGY

6. . Determination of sugars in plants by oxidation withferricyanide and eeric sulfate titration. Ind. Eng. Chem. Anal.Ed. 9: 228-229. 1937.

7. . Isolation of a hexosemonophosphate from pea leaves.Plant Physiol. 13: 641-647. 1938.

8. KURSANOV, A. The use of the vacuum infiltration method for thedetermination of the synthetic and hydrolytic actions of invertasein living plant tissues. Biokhimiya 1: 269-294. 1936.

9. , AND KRYUKOVA, N. Participation of phosphatase in thesynthesis of sucrose. Biokhimiya 4: 229-239. 1939.

10. NELSON, J. M., and AUCHINCLOSS, R. The effects of glucose and fruc-tose on the sucrose content in potato slices. Jour. Amer. Chem.Soc. 55: 3769-3772. 1933.

11. ROE, J. H. A colorimetic method for the determination of fructose inblood and urine. Jour. Biol. Chem. 107: 15-22. 1934.

12. SYSSAKYAN, N. M. The role of phosphates in the process of sugaraccumulation in the sugar beet. Biokhimiya. 1: 301-320. 1936.

13. TkNK6, B. Hexosephosphates produced by higher plants. Biochem.Jour. 30: 692-700. 1936.

14. VIRTANEN, A. I., and NORDLUND, M. Synthesis of sucrose in planttissue. Biochem. Jour. 28: 1729-1732. 1934.

610


Documents

M. MCCREADY AND W. HAS SIDKURSANOV (8) utilized this fact to study the synthetic and hydro-lytic actionsofinvertase inliving planttissues byhis "vacuuminfiltration" method. This method