Some Basic Psychophysics of Calcium Salt Solutions

Detection thresholds and the taste qualities of suprathresholdconcentrations of calcium salt solutions were assessed. Averagetaste detection thresholds for calcium chloride (CaCl₂), lactate(CaLa), hydroxide, phosphate and gluconate ranged between 8and 50 mM, with no reliable differences among the various salts.Between-subject variability ranged over four orders of magnitudeand reliability coefficients for repeated detection thresholdtests of CaCl₂ averaged r = 0.52. In an odor detection test,subjects could reliably discriminate 100 but not 1 mM CaCl₂and CaLa from water. The taste of suprathreshold concentrations(1–100 mM) of CaCl₂ and CaLa was considered unpleasant.At 1 mM, CaCl₂ solution was rated as 35% bitter, 32% sour, 29%sweet and 4% salty. At higher concentrations the sweet componentdiminished and the salty component increased, so that 100 mMCaCl₂ was rated as 44% bitter, 20% sour, 1% sweet and 35% salty.CaLa solutions were considered to be significantly less bitterand marginally more sour than equimolar CaCl₂ solutions. Thus,the taste of calcium varied with both the form and concentrationof salt tested, but included both sour and bitter components.Saltiness was identified only in high (     

MAGNITUDE ESTIMATES OF GUSTATORY QUALITY CHANGES AS A FUNCTION OF SOLUTION CONCENTRATION OF SIMPLE SALTS

Concentration-dependent quality changes in inorganic salt solutionswere investigated by obtaining quality reports, and magnitudeestimates, from four subjects, of the taste of LiCl, KCl, andNaCl solutions in the concentration range from 0.004 M to 0.050M; and Li₂SO₄ and K₂SO₄ solutions in the concentration rangefrom 0.002 F to 0.025 F. Plots of the geometric mean of themagnitude estimates for each quality as a function of concentrationconfirmed the general findings of earlier investigators (Höberand Kiesow, 1898; Renqvist, 1919; Dzendolet and Meiselman, 1967).In addition, differences found among the various studies werelinked to differences in procedure which established variablelevels of subject adaptation in the studies and permitted uncontrolledwater tastes to affect the data. It was concluded that a concentration-dependentphysicochemical change in the salt solutions, as proposed byDzendolet (1968), combines with a water taste to produce thequality of low concentration inorganic salt solutions. The relativecontribution of these two mechanisms to the overall qualityof the solution at any concentration will depend on the proceduresemployed. ^* Reprint requests should be sent to present address: John B.Pierce Foundation Laboratory, 290 Congress Ave., New Haven,CT 06519.     

An X-ray Microanalysis Study of the Salt Glands and Intracellular Calcium Crystals of Tamarix

X-ray microprobe analyses of the secreted salts from glandsof 20 Tamarix aphylla (L.) Karst trees growing in alluvial soilsin the north western district of Victoria, Australia, show thatthe glands secrete a variety of elements including calcium,magnesium and sulphur. However, sodium, potassium and chloride,common ions reported to be secreted predominantly in other studies,are present in relatively low amounts in the secreted salts.Calcium, the major cationic element in the secretory productof the gland, was not detected in the symplasm of the secretoryand collecting cells or in the vacuoles of the collecting cells.Some evidence indicates that silicon may be secreted by theglands but further corroboratory data are required. Our resultssupport previous suggestions that the glands of Tamarix havea low level of selectivity. Large, spherical aggregates of calcium crystals were observedin the vacuoles of the mesophyll cells and quantitative X-raymicroanalysis suggested that the chemical composition of thecrystalline aggregates was CaSO₄, 2H₂O. The predominant elementsin the vacuolar sap were magnesium and sulphur, probably presentas MgSO₄, whereas the major elements in the cytoplasm were potassium,sulphur and phosphorus. In Tamarix aphylla the calcium contentof the leaf appears to be regulated by both the secretion ofcalcium salts from the leaf and by intracellular calcificationin mesophyll cells.Copyright 1994, 1999 Academic Press X-ray microanalysis, Tamarix, salt gland, secretion, salts, ions, calcium crystals, compartmentation     

Inter-population Variations of Kochia indica During Germination Under Different Stresses

Germination of three populations of Kochia indica Wight fromcontrasting soil types were studied under various levels ofsalinity, alkalinity and osmotic stress with a view to evaluatetheir potential to establish through seeds in saline and alkalineenvironments of various magnitudes. The seeds were germinatedunder controlled conditions in Petri dishes using salinizedsolutions of NaCl, Na₂SO₄, MgCI₂ and CaSO₄ (electrical conductivity,EC, 4–16 ds m^–), sodium carbonate solutions (pH8.5–100), mannitol solutions ( – 2.5 to –100 bar) and de-ionised distilled water (control). Inter-populationdifferences were very marked, showing selective adaptation ofthe populations to a particular stress type. In general, allpopulations exhibited salt tolerance but were rather sensitiveto high osmotic stress. Kochia indica Wight (bui), germination, population, salinity, alkalinity, osmotic stress     

Feeding of the Cymatiid Gastropod, Argobuccinum argus, in Relation to the Structure of the Proboscis and Secretions of the Proboscis Gland

Several gastropod families belonging to the superfamily Tonnaceaare known to bore into the calcareous shells of echinoids andbivalves, but little work has been done on the family Cymatiidae.New observations show that the cymatiid, Argobuccinum argus,which feeds on the tubicolous polychaete, Gunnarea capensis,possesses large proboscis glands which secrete 0.4 to 0.5N H₂SO₄;further, the secretion dissolves greater amounts of pure CaCO₃than does O.47N H₂SO₄, alone. A toxin is also present, whichabolishes responses to light and touch in several invertebrates. The proboscis is atypically pleurembolic, having a permanentproboscis sheath. Retraction is due to the muscles ot the probosciswall, and the contracted proboscis is not inverted. Unlike othermesogastropods, the Tonnacea have three pairs ofglands associatedwith the foregut: proboscis glands, true salivary glands, anda small, partly paired gland of unknown function immediatelyposterior to the buccal mass. It is concluded that because of an abundance of readily availablefood in the form of Gunnarea, A. argus does not drillinto animalsprotected by a calcareous shell. The presence of a CaCO₃ dissolvingmechanism indicates that the Cymatiidae ingeneral may be ableto employ this method of feeding.     

Ion exchange reactions on the stem surface of Chamaecyparis obtusa Sieb. et Zucc.

In order to clarify the sources of soil acidification below stands of hinoki (Chamecyparis obtusa Sieb. et Zucc.), artificial stemflow experiments were performed to separate out the role rainfall acidity has from that of the acidity potentially occurring during stemflow. Various solutions, including distilled water, NaCl, NH₄Cl, KCl and CaCl₂+MgCl₂ solutions, were added in a controlled manner to the upper stem and the solutions systematically collected at breast height. Although the original pH values of the salt solutions were around 5.5, the pH values of stemflow ranged from 3.8 to 4.2. The ion balance [anion (including bicarbonate ions) to cation concentration] decreased with initial stemflow but recovered after ca. 5 l of flow. At this point, pH values continued to decrease and this decrease was accompanied by a decrease in the cation concentration of the stemflow. These results indicate that there are two ways by which stemflow can be acidified. In the initial stage of flow, organic and inorganic acids are dissolved in the stemflow. Following this, ion exchange occurs between cations contained in the stemflow and hydrogen ions adsorbed in the stem. The last step appears most critical in the acidification process.     

大豆初生根凯氏带对铜离子的通透性

采用在根内生成有色铜沉淀的方法研究大豆(Glycine max)初生根凯氏带对铜离子的通透性。用真空泵抽取浓度为200 μmol·L^–1 的CuSO₄溶液进入根中, 然后在重力作用下从根基部灌注400 μmol·L^–1的K₄[Fe(CN)₆]溶液, 两种物质在根内相遇即可产生棕色的Cu₂[Fe(CN)₆]沉淀, 根据沉淀的位置来确定铜离子所经过的途径。结果表明: Cu²⁺可以穿过内皮层凯氏带, 在木质部导管壁以及凯氏带至木质部之间的细胞壁处产生棕色沉淀, 侧根发生的部位也产生了大量的沉淀; 当抽取K₄[Fe(CN)₆]溶液后再灌注CuSO₄溶液, 发现Cu²⁺仍然可以穿过凯氏带, 并在凯氏带外侧以及外皮层细胞的细胞壁处产生棕色沉淀。研究结果证明凯氏带并不是一个可以完全阻止离子进出的完美屏障。     

The Biological Activity of Organoboron Compounds in the Promotion of Root Growth

The growth of the bean (Vicia faba var. minor) radicle in nutrientsolution requires the presence of borate. Optimum extensiongrowth, over 41 h, was obtained in the presence of 0.5 µMboric acid. This requirement of borate for root growth couldalso be satisfied by PhB(OH)₂, 2-OCH₃PhB(OH)₂, and 4-OCH₃PhB(OH)₂.These three compounds also complex in vitro with catechol-3,5-disulphonic acid. NaPh₄B and 2, 6-OCH₃)₂PhB(OH)₂ did not formsuch complexes in vitro, but were biologically active as sourcesof boron for radicle growth. This activity of NaPh₄B was absentif roots were grown in solutions which were changed every 8h. The activity of both NaPh₄B and 2,6-(OCH₃)₂PhB(OH)₂ was increasedby using stock aqueous solutions which were not freshly prepared.Theresults are considered to provide support for the hypothesisthat the activity of borate, as an essential plant nutrient,depends upon its ability to form a biologically active complexwith an in vivo cis-diol compound.     

Effect of Ions on the Orientation of Cortical Microtubules in Spirogyra Cells

Effects of ions on the orientation of cortical micro-lubules(MTs) in Spirogyra cells were studied. After depo-lymerizalionwith amiprophos-methyl (APM), MTs were allowed to reorganizein NaCI solutions of various concentrations. As the concentrationof NaCI increased, the frequency of cells that had oblique MTsincreased. When cells in NaCI solution were transferred intoartificial pond water (APW) and incubated for 6 h, all the MTschanged to become transverse to the longitudinal axis of thecell. KC1 and MgCl₂ also had effects on the orientation of MTs.However, NH₄Cl, CaCl₂;, CoCl₂, and Co(NO₃)₂ did not show anyeffect. These results suggest that Na⁺, K⁺, and Mg²⁺have effectson MT orientation and that NH⁺₄, Ca²⁺, Co²⁺, Cl^–, andNO^–₃ have little effect. When MTs were reorganized ineither NaCl or KCl solutions, all the oblique MTs were organizedinto an S-helix. In contrast, some of the oblique MTs were foundas a Z-helix in the cells incubated in MgCl₂ or mannitol solutions.These results suggest that effects of Na⁺ and K⁺ on the orientationof MTs are not the same as those of Mg²⁺ and mannitol. Theseresults provide the first evidence that ions are involved inthe orientation of MTs in algae. (Received January 27, 1998; Accepted August 10, 1998)     

Metabolic Adaption in Mature Roots of Salt-stressed Zea mays

Respiratory gas exchange and incorporation of ¹⁴C-leucine intoprotein were studied in proximal root segments from 25-day-oldmaize plants grown for the last ten days in 50 mM Na₂SO₄. ¹⁴C-leucineincorporation, and oxygen uptake in the presence of glucose,were as large in Na₂SO₄-grown tissues tested under saline conditionsas in tissues exposed to non-saline solutions throughout Thisadaptation was attributed to an increased metabolic capacityof Na₂SO₄-treated tissues, because these tissues, when returnedto non-saline solutions, evolved oxygen and incorporated ¹⁴C-leucinefaster than tissues exposed continuously to non-saline solutions. These changes are interpreted as a ‘compensation’for the inhibitory effects found when non-adapted tissues wereexposed to 50 mM Na₂SO₄. Moreover, we have related them to ultrastructuralchanges observed previously in xylem parenchyma cells of thesetissues, and to the possible involvement of these xylem parenchymacells in the re-absorption of sodium from the ascending xylemfluid Zea mays L., maize, salt-stress, respiration, protein synthesis     

ERRATA

Please replace the paragraph Culture of material in Materialand method on page 574 (Fujii, Shimmen and Tazawa), Vol. 19,No. 4 with the following corrected paragraph. Materials and methods Culture of material Spirogyra sp. used for the experiments was collected in theriver Kamogawa in Kyoto. Cylindrical cells composing the filamentwere 55 µm in diameter and 100–200 µm in length.Each cell usually had one spiral ribbon-like chloroplast. Thealga was cultured in slightly modified Reichardt's medium (27),1000 ml of which contained: 200 mg KNO₃, 20 mg K₂HPO₄, 10mgH₃BO₃, 6.6 mg FeSO₄?7H₂O, 25 mg Na₂EDTA (ethylenediamine tetraaceticacid disodium salt), 200 mg NaHCO₃, 50 mg CaSO₄?2H₂O, 10mg MgSO₄?7H₂O,0.5 mg ZnSO₄?7H₂O, 5mg MnCl₂?4H₂O, 24 µg Na₂MoO₄, 2 µgCoCl₂?6H₂O, 500 mg Tris. The pH was adjusted to 7.4 with HCl.The alga was cultured in a Petri dish at 20?1?C under a 16 hr–8hr light-dark regime. The light intensity was about 2000 lux.Under such conditions, the cells divided once a day fairly synchronously. Experimental solutions Artificial pond water (APW) containing 0.1 mM each of KCl, NaCland CaCl₂     

Radial Turgor Pressure Profiles in Growing and Mature Zones of Wheat Roots--A Modification of the Pressure Probe

A modification of the pressure probe is described which allowsaccurate routine recording of the turgor pressure of singlecells at measured depth within a tissue. Measurements of radial profiles of turgor pressure in wheatroots grown in some simple salt solutions (0.5 mol m^–3CaCl₂, 0.5 mol m^–3 CaCI₂ plus 10 mol m^–3 NaCl, and0.5 mol m^–3 CaCl₂ plus 10 mol m^–3 KCI), are described.Turgor pressure was constant (approximately, 0.65 MPa) alonga radius within the elongation zone irrespective of the natureof the bathing solution. In mature root tissue turgor pressurein the cortex was lower than that of the growing zone in alltreatments and the pressure of the stele was on average 0.22MPa higher than that of the cortex. Potassium in the mediumbathing the root increased the turgor pressure in mature root(both cortex and stele) relative to low salt and sodium treatments. The results are discussed in relation to both root growth andion accumulation. Key words: Pressure probe, wheat roots, salt solution     

The neural activities of the greater superficial petrosal nerve of the rat in response to chemical stimulation of the palate

A comparison of the integrated responses of the rat's greatersuperficial petrosal (GSP) and chorda tympani (CT) nerves toa number of taste stimuli was studied. The GSP nerve of therat was very responsive to the chemical stimulation of the oralcavity. Among the selected stimuli related to the four basictaste qualities, 0.5 M sucrose produced the greatest neuralresponse in the GSP nerve, whereas, 0.1 M NaCl produced thegreatest in the CT nerve. The GSP nerve integrated responseto 0.5 M sucrose solution was approximately three times as greatin magnitude as that to a 0.1 M NaCl solution. The neural responsemagnitude of the GSP and CT nerves were as follows: GSP nerve;0.5 M sucrose >0.02 M Na-saccharin >0.05 M citric acid>0.1 M NaCl > 0.01 M quinine-HCl. CT nerve; 0.1 M NaCl> 0.05 M citric acid > 0.02 M Na-saccharin > 0.01 Mquinine-HCl >0.5 M sucrose. The response magnitudes of theGSP nerve to 0.3 M chloride salt solutions were: LiCl > CaCl₂> NaCl > NH₄Cl > KCl, whereas the response magnitudesof the CT nerve to the above salts were: LiCl > NaCl >NH₄Cl > CaCl₂ > KCl. All 0.5 M solutions of the selectedsugars (sucrose, rhamnose, galactose, lactose, fructose, -methyl-D-glucoside,xylose, mannose, arabinose, maltose, sorbose and glucose) evokedneural responses in both GSP and CT nerves. The order of theresponse magnitudes of the GSP nerve to the selected sugarswas similar to that of the CT nerve but the absolute magnitudesof the GSP nerve were greater.     

Effects of Na2SO4, K2SO4 and KCl on Growth and Ion Uptake of Callus Cultures of Vaccinium corymbosum L. cv. Blue Crop

Non-selected and Na₂SO-, K₂SO₄- or KCl-selected callus culturesof Vaccinium corymbosum L. cv. Blue Crop were grown on mediasupplemented with 0, 25 and 50 mM Na₂SO₄ (non-selected and Na₂SO(-selectedonly), 0, 25 and 50mMK₂SO₄ (non-selected and K₂SO₄-selectedonly) or 0, 50 and 100 mM KCl (non-selected and KCl-selectedonly). On all media, growth of selected callus (on a fresh-weightor dry-weight basis) was greater than that of non-selected callus,and selected callus grew optimally on the level and type ofsalt on which it was selected. Selected callus was friable andmaintained a higher f. wt:d. wt ratio. Tissue water potentialin selected callus was more negative than in non-selected callus. Flame photometry and chloridometry showed Na⁺, K⁺ and Cl^–accumulated in callus to concentrations equal to or greaterthan the initial concentration in the medium. Turbidometry showedthat tissue SO₄^2- concentration was lower than the concentrationin the medium. In most cases selected callus accumulated moreNa⁺, K^sup, SO₄^2– or Cl^– than non-selected callus.Vacuolar ion concentration was measured by electronprobe X-raymicroanalysis, and on most media selected callus had highervacuolar ion concentrations than non-selected callus. SO₄^2–and Cl^– were accumulated in the vacuoles at concentrationshigher than the external medium, but vacuolar Na⁺ concentrationdid not reach external concentration on Na₂SO₄ and on potassiumsalts was maintained between 12 and 17 mM. Vacuolar K⁺ concentration(approx. 142–191 mM on no salt) decreased on Na₂SO₄ andincreased on K₂SO₄ and KCl. There was no precise correlation between total or specific ionaccumulation (Na⁺, K⁺, SO₄^2– and Cl^– and fresh-weightyield. Results suggest that selection results in adaptationin response to decreased water potential of the medium. Vaccinium corymbosum, blueberry, electronprobe X-ray microanalysis, callus, in vitro selection, salt tolerance, KCl, K₂SO₄, Na₂SO₄     

Salt Stress Induced Nuclear and DNA Degradation in Meristematic Cells of Barley Roots

Root growth of barley (Hordeum vulgare L., cv. Akashinriki)was inhibited by 200 raM NaCl, when 1 mM CaCl₂ was present inthe hydroponic culture solution. Increasing the CaCl₂ up to10 mM partially prevented this inhibition. However, inhibitionalso occurred with 100 mM NaCl in the presence of 0.1 mM CaCl₂.The nuclei of meristematic cells in roots in which growth hadbeen inhibited by salt stress were studied after staining withDAPI (4',6-diamino-2-phenylindol). Nuclear deformation of thecells occurred with 12 h of salt stress with 500 mM NaCl, andwas followed by degradation. The nuclear degradation was alsoobserved when the roots were exposed to more than 300 mM NaClfor 24 h. Biochemical analysis revealed that nuclear degradationwas accompanied by apoptosis-like DNA fragmentation. The intracellularmechanisms of nuclear degradation in cells after salt stressare discussed. ¹Emertius professor, Okayama University.     

Influence of Chloride and Transpiration on Net15NO3-Uptake Rate byCitrus Roots

Three-month-old Carrizo citrange (hybrid of Citrus sinensisL. OsbeckxPoncirus trifoliata Blanco) seedlings were grown incontrolled environment chambers in pots of fine sand. Plantswere irrigated with either non-saline or saline solutions overa 3-week period. After these treatments, plants were transferredto vessels containing a 5 m M¹⁵NO₃K (96% atom excess¹⁵N) solution,and transpiration as well as concentration of¹⁵N and Cl^-in roots,stem and leaves were measured after 24 h. Transpiration and¹⁵NO₃^-uptakerates were inhibited after exposure to NaCl and the concentrationof salt pre-treatment determined the intensity of this inhibitoryeffect. To determine the effect of transpiration on NO₃^-absorption,net¹⁵NO₃^-uptake rate was measured in salt stressed and non-stressedplants exposed to different light intensities or relative humiditiesand also in detached roots. Reduction in NO₃^-uptake was moreclosely related to Cl^-antagonism from salt stress than to reducedtranspiration rate. Copyright 1999 Annals of Botany Company Nitrate, absorption, inhibition transport system, salt, light and humidity.     

NKCC1 and NHE1 are abundantly expressed in the basolateral plasma membrane of secretory coil cells in rat, mouse, and human sweat glands

In isolated sweat glands, bumetanide inhibits sweat secretion. The mRNA encoding bumetanide-sensitive Na⁺-K⁺-Cl^– cotransporter (NKCC) isoform 1 (NKCC1) has been detected in sweat glands; however, the cellular and subcellular protein localization is unknown. Na⁺/H⁺ exchanger (NHE) isoform 1 (NHE1) protein has been localized to both the duct and secretory coil of human sweat duct; however, the NHE1 abundance in the duct was not compared with that in the secretory coil. The aim of this study was to test whether mRNA encoding NKCC1, NKCC2, and Na⁺-coupled acid-base transporters and the corresponding proteins are expressed in rodent sweat glands and, if expressed, to determine the cellular and subcellular localization in rat, mouse, and human eccrine sweat glands. NKCC1 mRNA was demonstrated in rat palmar tissue, including sweat glands, using RT-PCR, whereas NKCC2 mRNA was absent. Also, NHE1 mRNA was demonstrated in rat palmar tissue, whereas NHE2, NHE3, NHE4, electrogenic Na⁺-HCO₃^– cotransporter 1 NBCe1, NBCe2, electroneutral Na⁺-HCO₃^– cotransporter NBCn1, and Na⁺-dependent Cl^–/HCO₃^– exchanger NCBE mRNA were not detected. The expression of NKCC1 and NHE1 proteins was confirmed in rat palmar skin by immunoblotting, whereas NKCC2, NHE2, and NHE3 proteins were not detected. Immunohistochemistry was performed using sections from rat, mouse, and human palmar tissue. Immunoperoxidase labeling revealed abundant expression of NKCC1 and NHE1 in the basolateral domain of secretory coils of rat, mouse, and human sweat glands and low expression was found in the coiled part of the ducts. In contrast, NKCC1 and NHE1 labeling was absent from rat, mouse, and human epidermis. Immunoelectron microscopy demonstrated abundant NKCC1 and NHE1 labeling of the basolateral plasma membrane of mouse sweat glands, with no labeling of the apical plasma membranes or intracellular structures. The basolateral NKCC1 of the secretory coils of sweat glands would most likely account for the observed bumetanide-sensitive NaCl secretion in the secretory coils, and the basolateral NHE1 is likely to be involved in Na⁺-coupled acid-base transport. bumetanide; eccrine glands; immunohistochemistry; immunoblotting     

Ion Distribution in Salt-stressed Mature Zea mays Roots in Relation to Ultrastructure and Retention of Sodium

Ultrastructural features and the distribution of soluble ionshave been examined in mature roots of Zea mays plants grownin both NaCl and Na₂SO₄ salinities. When the plants were grown in either salt, the Na concentrationincreased proximally along the root with a concomitant declinein the K concentration. Both trends were reversed in the shoot. X-ray microanalysis of deep-frozen, fully hydrated specimensshowed that in salt-treated roots Na, and Cl, or S were distributedabout stoichiometrically in the cortex and endodermis. Na wasusually less concentrated than the anion in the lumens of thevessels, but was concentrated markedly relative to either Clor S in the adjoining xylem parenchyma cells. In the older, proximal parts of seminal roots of plants grownboth without salt (controls) and in the presence of either NaClor Na₂SO₄, wall developments occurred in xylem parenchyma cellsat the half-bordered pits in which the cell wall became markedlythicker and possessed a loosely packed fibrillar structure.These structures were not comparable with the transfer-celltype of protuberances reported in the roots of other species. In the xylem parenchyma of plants grown in the presence of Na₂SO₄there were dramatic increases in the quantities of rough endoplasmicreticulum, ribosomes, and mitochondria relative both to controlsand NaCl treatments. The results are discussed in relation to the possible functionof the xylem parenchyma of the mature root in the reabsorptionof Na from the xylem sap, which may mitigate adverse effectsof salinity in salt-sensitive glycophytes.     

ORGANIC ACID SYNTHESIS IN RESPONSE TO EXCESS CATION ABSORPTION IN VACUOLATE AND NON-VACUOLATE SECTIONS OF CORN AND BARLEY ROOTS

1. ¹⁴CO₂ fixation into organic acids in tips and proximal sectionsof both corn and barley roots was studied as a function of thenature and concentration of the salt in the external solution.
2. In comparison with the level of ¹⁴CO₂ fixation by vacuolateproximal sections in KCI, incorporation was markedly enhancedin K₂SO₄ and diminished in CaCk. By contrast, non-vacuolateroot tips were indifferent to the type of external salt withrespect to UCO₂ incorporation into organic acids.
3. The effectof salt type on organic acid formation from ¹⁴CO₂was most pronouncedat relatively high concentrations.
4. The conclusion was reachedthat organic acid synthesis in responsetoexcess cation uptakeis the result of cation movement into thevacuole, and thattransport into the vacuole is mediated bythe low-affinity componentof the dual mechanisms involved inion absorption.

¹Present address: Government Forst Experiment Station, Meguro,Tokyo.     

Accumulation of tartaric acid in the ripening process of grapes

1. 1. Tartaric acid content in grapes gradually increased withripening and reached a plateau about 50 days after flowering.
2. 2. Tartaric acid synthesis from ^14C0₂ was predominant in anearly ripening stage. When the berries were exposed to ^14CO₂8 days after flowering and examined two days later, 30% of thetotal ¹⁴C fixed was found in tartaric acid. Subsequently, apart of the tartaric acid decomposed, but the greater part remainedin the berries in a salt form. At the last stage of the ripeningprocess (82-100 days after flowering), some of the tartaratewas again converted to free acid. No ^14CO₂ was incorporatedinto tartaric acid when berries were exposed 61 days after flowering.
3. 3. L(+)-Tartaric acid-l,4-¹⁴C fed to the berries was catabolizedto ¹⁴CO₂. The ratio of radio activity recovered as ^{14 CO₂} tothat fed was nearly constant throughout the ripening process.
4. The cause of tartaric acid accumulation in grape berries isnot thought to be due to a lack of catabolizable enzymes, butto formation of an insoluble salt which is scarcely effectedby such enzymes.

(Received May 2, 1968; )