ERRATA

Page 806, Preparation of Mitochondrial Fraction, line 4: The following should be inserted between ‘centrifugedat’ and ‘20 000 g for’: 3000 for 10 mm. Thesupernatant was centrifuged at The following corrections are required: Page 104, line 20: ‘2-hydroxylation’ should read ‘2-ß3-hydroxylation’ Page 106, line 11: ‘of Ga₈’ should read ‘to GA₈’ Page 113, last line:‘length 50 µm’ shouldread ‘length 150 µm’ Formula 15 should read: Formula 17 should read: y(0)– y^* = ß₁V₁+ß₂V₂ page 118: Formula 18 should read: Formula 23 should read: Formula 24 should read:      

ERRATA

Page 685: For 2O% (•), 37% () and 47% (), read 2O% (),37% () and 47% (•) Page 695: For LDR and Relative growth data, move up columnsone line     

ERRATA

Errata is paper by Swanson and Whitfield, Vol. 32(126), 221–239. Equation (6), page 223. should read: Page 231; 7th line in first paragraph Fig. 7, vice Fig. 8 Page 237; Figure 12 caption, end of third line K = 0.46 vice K = 0.16     

Structure-activity relationships in sweeteners. I. Nitroanilines, sulphamates, oximes, isocoumarins and dipeptides

Besides the hydrophilic AH-B moiety in sweeteners, the morehydrophobic ‘third binding sites’ play an essentialrole in inducing sweetness. The distances between these molecularfunctions seem to be very critical, but exact data are lacking.To describe stereochemical requirements more precisely, newconceptual parameters were introduced, namely , and (minimum,optimum and maximum distances between these third binding sitesand the atoms A, H and B of the AH-B moieties respectively,especially appropriate for homologous series) and the S value(shortest distance between the position of an atom and the planeformed by the atoms A, H and B of the AH-B moiety). The dimensionsof the relevant side chains of five homologous series of sweeteners– sulphamates, oximes, nitroanilines, isocoumarins anddipeptides — were determined. We calculated that the positionsof the , and parameters with regard to the AH-B moieties arelocated around two main axes forming 95? angles with the H-Baxis in the AH-B moieties for sulphamates and isocoumarins and125? angles for oximes, nitroanilines and dipeptides. The positionsof are, for all potent sweeteners, situated at 70—85%of the maximum distance of viewed from the centre of the Aatom, while for , this value was found to be 15% for oximes,25% for nitroanilines, 40% for sulphamates, 50—70% fordipeptides and 65% for isocoumarins. The results indicate thereare at least three — but a maximum of four — differentreceptor sites. They have very narrow site clefts with maximumheights of -0.6 nm.     

Salinity and Salicornia bigelovii Torr. Seedling Establishment. Water Relations

Seedling establishment of Salicornia bigelovii was inhibitedwhen seeds were sown in vermiculite watered with 0 ppt NaCl(control treatment) while the presence of 10 or 30 ppt NaClhad no inhibitory effect. During most of the experimental periodthe rate of water absorption in both cotyledons and embryo-axisof the salt treatments was at least twice that of the control.The organic material decreased in the cotyledons at the sametime that it was increasing in the embryo-axis. Salinity didnot show any apparent effect on reserve mobilization from thecotyledons to the embryo-axis. Ions accumulated with the increasedsalinity of the root environment in both the cotyledons andthe embryo-axis. The former accumulated more than the latterexcept in the control treatment. After the 8th day from sowingthe cotyledon was —1•38, —1•95 and —2•74MPa for the 0, 10 and 30 ppt treatments, respectively. The gradients between external solution and the cotyledons were(0•80, 1•19 and 1•15 MPa for the 0, 10 and 30ppt, respectively. The _p of the control treatment was very low(0•02 MPa) when compared to the ones for the 10(0•53MPa) and the 30 ppt (0•99 MPa) treatments. Glycinebetaineand soluble amino nitrogen accounted for over 90% of the organiccomponent of the tissue osmolality with soluble sugars beingresponsible for the remainder. In the control the inorganicand organic components were of the same magnitude while in the10 and 30 ppt treatments the inorganic was 8•6 and 14•1fold greater than the organic component, respectively. Watermovement into the control plants was apparently inhibited bythe lack of inorganic solutes and as a consequence the cotyledonsfrom these plants did not expand and seedling growth was severelyreduced. Key words: Halophyte, seedling establishment, tissue osmolality components     

Alterations in Neurobehavioral Responses in Fishes Exposed to Lead and Lead-chelating Agents

Lead (Pb) is a neurotoxic element that causes behavioral dysfunctionin fishes within days of exposure to sublethal concentrations.To test the hypothesis that internal stores of Pb have long-termbehavioral effects, Pb-exposed (0.3 ppm) fish were either treatedwith the Pb-chelating drug meso-2,3 dimercaptosuccinic acid(DMSA) or returned to controlconditions (0.0 ppm Pb). Swimmingcapacity improved after a 7-day DMSA (1.5 ppm) exposure (ANOVAP < 0.05). Removing fish from conditions of waterborne Pbdid not achieve this result; DMSA alone without Pb pretreatmenthad no significant effect. Blood Pb (BPb) levels in controlor DMSA-only fish were not detectable. Treated groups had significantlyhigher BPb (ANOVA, P < 0.05): Pb-exposed fish—530.5± 156.7, 884.6 ± 130.0 ppm (1, 2 wks, respectively);Pb-exposed 0.0 ppm water—488.8 ± 67.3 ppm after2 wks; Pb-exposed 1.5 ppm DMSA—202.0 ± 116.0 ppmafter 2 wks. Norepinephrine and vanillylmandelic acid levelswere altered by Pb exposure (ANOVA, P < 0.05). Whereas removingPb did not facilitate a return to control values, adding DMSAdid (ANOVA, P < 0.05). Temporal-spatial response patternsto a stimulus in Pb-exposed (0.1 ppm) and Pb-exposed 0.0 ppmPb water groups differed from controls (0.0 ppm Pb; 0.0 ppmDMSA) for stimulus response angle, and rate and extent of movementaway from stimulus source. While the two control types weresimilar for stimulus response angle and reaction time, DMSA-onlycontrols, unlike 0.0 ppm Pb controls, did not respond as a tightly-associatedgroup after the stimulus.     

Receptor site analysis using neurosensory responses of the boll weevil to analogs of the cyclohexylideneethanol of its aggregation pheromone

The active sites of II neurons (Dickens, 1990c) in both sexesof the boll weevil, Anthonomus grandis Boh., were investigatedusing structure—activity relationship studies. Hectrophysiologicalresponses of antennal olfactory receptors in male and femaleboll weevils were recorded in response to components II andIII of its aggregation pheromone and various functional, geometric,and 2-fluoroalkenyl analogs. Dose—response curves forelectroantennogram responses of both sexes to both the 2-fluoroanalog of II (E-II-F) and II (Z-II) were essentially identical.Correspondingly, dose—response curves for the geometricisomer of II (E-II), and its 2-fluoro analog (Z-II-F), had similarshapes but responses to E-II were significantly greater at severaldoses. Responses of single neurons associated with type I sensillato 1 µg stimulus loads of various analogs of II showedsignificant differences in the numbers of impulses elicitedby each during a 500 ms stimulation period: Z-II > E-II-F> III--F, III > Z-II-F, E-II, IV. These results demonstratedthe importance of the cis geometry between the dimethyl groupat the 3-position on the six-carbon ring, and the functionalmoiety at the 1-position. The limited activity of E-II and Z-II-Fon II neurons indicates these compounds may be stimulating otherreceptor types, since EAGs to these compounds were large. Dose—responsecurves for an II neuron were similar for Z-D and E-II-F, aswere curves for III and III--F, indicating that the fluorineatom at the 2-position had little effect on receptor binding.Our data support a previous hypothesis that II neurons haveseparate receptors sites for pheromone components II and III.     

Effects of Ion Activity and Sugar Polyalcohol Osmotica on Ion Uptake

Evangelou, V. P. and Wagner, G. J. 1987. Effects of ion activityand sugar polyalcohol osmotica on ion uptake.—J. exp.Bot. 38: 1637–1651. Theoretical and experimental data are presented here which showthat ion activity—not just ion concentration—canbe an important consideration in interpreting measurements ofion uptake from solution by plant tissues. It is also shownthat sugar polyalcohols often used as osmotica in experimentsusing protoplasts, roots, vacuoles, etc. can greatly influenceion activity. The relationship between element concentrationand ion activity is shown here to be biphasic—the degreebeing dependent on the type of anions and cations involved andion concentration. Generally, the extent of biphasic behaviourincreases with increasing ion valence (i.e. K ⁺ versus Mg^{2 +}or Ca^{2 +} versus Al³⁺) and this character can be prominent inthe concentration range sometimes used to measure ion uptakeby plants (i.e. 1 to 70 mol m³). These observations can affectinterpretation of ion uptake kinetics involving ions with valencegreater than 1. High levels of sugar polyalcohols (i.e. 0·7kmol m ³ sorbitol or mannitol) significantly suppress ion activityand the nature and degree of suppression is dependent on iontype. The implications of this effect should be considered andquantified if ion uptake studies made in the presence of suchosmotica are to be extrapolated to the simpler case of a watersolution containing only inorganic salts. Key words: Kinetics, thermodynamics, solution cultures, ion pairs.     

Leaf Extension in Zea mays: III. FIELD MEASUREMENTS OF LEAF EXTENSION IN RESPONSE TO TEMPERATURE AND LEAF WATER POTENTIAL

Leaf extension rates of young maize plants were measured inthe field. Large diurnal fluctuations of air temperature fromabout 5—35°C caused extension rates to vary from 0·4mm h^–1– 3·6 mm h^–1. When the temperatureof the shoot apical meristem was kept at 30–34°C,extension rates remained constant, despite diurnal fluctuationsof air temperature. Leaf water potentials () above –8 or –9 bars hadlittle apparent effect on extension rate. It was concluded that gradients within leaves could account for this.     

Derivation of Plant Cell Wall Water Content by Examination of the Water-Holding Capacity of Membrane-Disrupted Tissues10

Plant cell lumina are several orders of magnitude larger thancell wall pores. If the membranes of the plant sample are disruptedand the tissue dried out, a value should be reached at whichthe cell lumina have drained but the cell walls remain relativelyhydrated. The water content of membrane-disrupted tissues atlow may, therefore, serve as a good approximation of plantcell wall water content (CW). The relationship between and water content of membrane-disruptedtissues was measured for four grass spaces over the range of0 to –40 MPa. It was found that most water loss occurredabove a of – 10 MPa. CW was estimated from the watercontent of membrane-disrupted tissues at lower and it was foundthat there was very little intra-or intraspecific variabilityin CW estimates when water content was expressed as a percentagedry weight of the tissue. This is in contrast to the high variabilityin CW estimated from the analysis of inverse water potential—watercontent (IP—WC) curves measured with the thermocouplepsychrometer. Applications of the membrane-disruption methodof estimating CW of plant tissue are discussed. Key words: Cell wall water, thermocouple psychrometer, membrane-disruption     

Plant Growth in Polyethylene Glycol Solutions in Relation to the Osmotic Potential of the Root Medium and the Leaf Water Balance

The changes in leaf extension, plant dryweight, leaf area, netassimilation rate (E), relative growth-rate (R_W), and relativeleaf growth-rate (R_L), have been studied for four species grownfor 2 weeks in solutions of polyethylene glycol 4000 of controlledosmotic potentials. All aspects of growth were decreased bydecreasing the osmotic potential (_sol) of the root medium andthe leaf water potential (), and ceased when _/ was greater than— 10 bars in bean, cotton, maize. These plants were moresusceptible than ryegrass to water stress. Growth of bean stoppedat equal to about —6 bars, but even at —10 barsryegrass was capable of some growth. Slight decrease in fromthe values in the control plants decreased growth during thefirst week but partial recovery was apparent during the secondweek's growth in solution culture, when leaf extension, E, R_Land R_W increased in plants subjected to stress. Examinationof the water balance, water potential, osmotic potential andturgor of the leaf in relation to relative water content suggeststhat recovery was related to increased turgor and that the abilityof the plants to grow at reduced values of the osmotic potentialof the root medium and of the leaf water potential depend onthe maintenance of turgor.     

A constant flow rate olfactometer with seven calibrated concentrations

Page 4, equation (1) should read Page 5, equation (2) should read      

Axial Distribution of Glycosidases in Relation to Cellular Growth and Ageing in Pisum sativum Root

Tanimoto, E. 1985. Axial distribution of glycosidases in relationto cellular growth and ageing in Pisum sativum root.—J.exp. Bot. 36: 1267–1274. Eight glycosidase activities were measured in relation to cellulargrowth and ageing along the axis of pea roots. The highest activities of ß-D-fucosidase and ß-D-glucosidasewere in the apical 1.0 mm segment containing the root cap andmeristem. Activities of -L-arabinosidase, -D-mannosidase, ß-D-galactosidase, -D-glucosidase and ß-D-xylosidase werehighest in the segment between 1 and 2 mm from the tip and containingyoung elongating cells with high growth potential. The activityof -D-galactosidase was high between 1 and 2 mm from the roottip, decreasing to a minimum 4-5 mm from the tip and increasingagain up to the base of root. This distribution of enzyme activitiesrelative to the root tip remained unchanged during 28 h whilethe root length doubled. No -L--fucosidase, ß-L-fucosidaseand -D-xylosidase activities were detected. Key words: Pisum sativum, root growth, glycosidase, galactosidase, mannosidase     

Production and secretion of {alpha}-galactosidase and endo-{beta}-mannanase by carob (Ceratonia siliqua L.) endosperm protoplasts

Viable protoplasts were isolated for the first time from maturecarob (Ceratonia siliqua L.) endosperm tissue. After 5 d ofincubation 75% of the protoplasts were viable. During incubationthey underwent vacuolation and produced the carob endospermhydrolases, agalactosidase and endo-ß-mannanase, whichwere secreted in the incubation medium. The secretion of bothenzymes were under Ca²⁺ control. Many characteristics of -galactosidaseand endo-ß-mannanase production by protoplasts werethe same as those of whole endosperms: their production didnot require any hormonal signal and was inhibited in the presenceof ABA or the leachate from the carob endosperm/seed coat. Moderatewater stress (—2.0 MPa) neither affected the activityof these hydrolases nor their secretion by endosperm protoplast.However, when the osmoticum of protoplast incubation mediumwas higher, the production and secretion of both hydrolaseswere reduced. Comparison of the hydrolases activities in theincubation media of leached carob endosperms, which were incubatedunder normal and water stress (—1.5 MPa) conditions, withthe activities of the protoplast-secreted hydrolases indicatedthat (i) carob endosperm cell wall acts as a barrier for thesecreted enzymes and (ii) that water stress reduces the cellwall porosity of the carob endosperm cells, and thus the releaseof the secreted -galactosidase and endo-ß-mannanaseis inhibited. The isolation of carob endosperm protoplasts offersa potent experimental system for the study of aspects of endospermcell physiology, such as enzyme secretion Key words: Abscisic acid, carob endosperm, Ceratonia siliqua L, endo-ß-mannanase, -galactosidase, leachate, protoplasts, water stress     

Stomatal Control of Photosynthesis of Eucalyptus globulus Labill. Trees under Field Conditions in Portugal

Pereira, J. S., Tenhunen, J. D. and Lange, O. L. 1987. Stomatalcontrol of photosynthesis of Eucalyptus globulus Labill. treesunder field conditions in Portugal.—J. exp. Bot. 38: 1678–1688. Stomatal behaviour of adult leaves of Eucalyptus globulus treeswas studied under field conditions in Portugal. In the absenceof severe plant water stress stomata were open when the summedtotal of photosynthetically active photon flux density incidenton both leaf surfaces was above 100 µmol m²s¹ and leafconductance to water vapour reached 245 mmol m ² s¹ on a total(both epidermes) leaf area basis. The stomata of both leaf epidermesresponded similarly to changes in solar radiation and waterstress. Water stress resulted in decreasing daily maxima inleaf conductance as predawn leaf water potential decreased.Maximal leaf conductance decreased to less than 50 mmol m ²s ¹ when predawn leaf water potential decreased below —1·0MPa. At similar values of predawn leaf water potential stomatawere more closed as the leaf to air water vapour partial pressuredifference increased. The effect of increasing air dryness onstomata was greatest at high predawn leaf water potential. Dailymaxima in photosynthetic rates and in leaf conductance werelinearly related to one another in spring and summer. Both decreasedwith increase in leaf water stress. In autumn and winter, increasesin leaf conductance occurring under natural conditions duringthe course of the day were not necessarily accompanied by increasesin net photosynthesis. Stomata were more closed in the afternoonthan in the morning at the same rates of net photosynthesis,temperature or leaf to air water vapour partial pressure difference. Key words: Eucalyptus globulus,, photosynthesis, stomata, water stress.     

Intracellular pH Regulation in Ricinus communis Grown with Ammonium or Nitrate as N Source: The Role of Long Distance Transport

Allen, S. and Raven, J. A. 1987. Intracellular pH regulationin Ricinus communis grown with ammonium or nitrate as N source:the role of long distance transport.—J. exp. Bot. 38:580–596. Charge balance and intracellular pH regulation were studiedin Ricinus communis grown in water culture with 1–0 molm^–3 or l-0 mol m ^–3 as sole N source. Seedling and 70-d-old plant parts were analysed for total P, C, organic N and S, and ash alkalinity;xylem and phloem saps were analysed for mineral ion content,and amino acids, amides, and dicarboxylates. Excreted H⁺ andbase were also measured. It was shown that in -N plants, H ⁺ produced and excreted directly bythe roots accounted for all net —COOH produced in theplant, but not for cation uptake by net H⁺ exchange. IntracellularpH perturbation in the shoot was regulated partly by reduction and partly by the transportof OH^- -generating dicarboxylates in the xylem. Phloem sap hadthe capacity to transport organic N and carboxylates excessto shoot requirements back to the root. In -N plants, 60% of total reduction occurred in the root, and 70% of all OH^- produced by root and reduction was excreted directly as base. Very little —COO^–from root reduction was stored in the root: most was transported to the shoot as xylem dicarboxylateand stored in the shoot. Of the OH^- produced from shoot and reduction, 40% was stored as shoot carboxylate: the phloem saphad the capacity to transport the rest back to the roots whereit was excreted as base. Key words: Intracellular pH, ammonium nutrition, nitrate nutrition, xylem dicarboxylates, phloem dicarboxylates, charge balance     

The Effect of Temperature and Moisture Content on the Longevity of Seed of Ulmus carpinifolia and Terminalia brassii

Seeds of the Smooth-leafed Elm (Uimus carpinifolia) and of thetropical forest tree Terb (Terminalia brassii) were stored hermeticallyand sampled at intervals for periods of up to two years. Bothspecies possess ‘orthodox’ seed (increasing longevityis observed as either moisture content or temperature are reduced)within the temperature ranges from — 13 to 52°C (Elm)and from —4 to 42°C (Terb) and within the moisturecontent ranges from 3 to 19 per cent (Elm) and from 5 to 14per cent (Terb) on a fresh weight basis. Elm seed stored at—75°C showed the expected relationship between longevityand moisture content, but did not differ significantly in longevityfrom seed kept at — 13°C when moisture contents wereheld constant. Probit analysis of the relationship between germinationpercentage and time was performed for each storage environment,yielding a slope from which the standard deviation of the distributionof seed deaths over time () was calculated. Standard deviationvalues were used in turn to determine the values of constantsin a viability equation which had previously been applied toseed of barley, chickpea, cowpea and soybean. The equation,which gave a good fit to the results obtained, can be used topredict viability for seed in storage over a wide range of environmentalconditions. Some limitations to the applicability of the viability equationwere defined. At 22 per cent and higher moisture contents Elmseed survived longer than predicted. Furthermore, all Elm andTerb seed was killed quickly on placing in —75°C at22 and 20 per cent moisture content respectively, but high viabilitywas retained for several days at 19 and 17 per cent respectively.Practical implications of the results are discussed. Uimus carpinifolia Gleditsch, Smooth-leafed Elm, Terminalia brassii Exell, Terb, seed longevity, seed storage, moisture content, temperature     

A Pressure-Jump Method as a New Tool in Growth Physiology for Monitoring Physiological Wall Extensibility and Effective Turgor

A new method has been devised in order to allow the rapid determinationof the physiological extensibility () of the cell wall togetherwith the apparent effective turgor (P — Y'). The methodconsists of determining the elongation growth rate of a segmentof pea hypocotyl with an auxanometer and applying a very smallincrease (around 10 kPa) in xylem pressure (jumps) by the xylemperfusion method. The cell turgor pressure is increased by thewater surge from the xylem that is due to the pressure jumpand reaches a new level within a short time. The elongationrate is also increased asymptotically to a new steady-statelevel within a short time. is estimated by simply dividingthe increase in the steady-state growth rate by the increasein perfusion pressure, which is monitored by a pressure transduceror by the increase in turgor pressure measured by a pressureprobe. Minimal length of the time period required to get a newsteady elongation rate is 1.5 min. Therefore, it is possibleto scan continuously the change in by the intermittent applicationof the brief, small pulses of xylem pressure during any experimentaltreatment. The apparent effective turgor P — Y' can becalculated by dividing the initial elongation growth rate by Using this method, we have demonstrated experimentally thenon-linearity of the relationship between elongation rate andturgor (Lockhart mechanical equation). (Received April 26, 1989; Accepted July 17, 1989)     

Somaclonal Variation in the Gliadin Patterns of Grains of Regenerated Wheat Plants

Maddock, S. E., Risiott, R., Parmar, S., Jones, M. G. K. andShewry, P. R. 1985. Somaclonal variation in the gliadin patternsof grains of regenerated wheat plants.—J. exp. Bot. 36:1976–1984. The banding patterns of the gliadin storageproteins of the grains of 590 regenerated plants from six wheatcultivars were examined by polyacrylamide gel electrophoresisusing lactate buffer. Variation additional to that present incontrol material was observed at a low frequency (1%). Two variantlines showed extensive changes in banding patterns which wereaccompanied by morphological variation of the plants. More limitedvariation in the form of an extra –gliadin band was observedin a third line. Differences in the seed gliadins were not foundin four lines which had shown stable phenotypic changes in heightin field trials. Key words: Wheat, somaclonal variation, gliadins, tissue culture, seed proteins     

ERRATA

WARBURG, M. R., 1965. On the water economy of some Australianland snails. Proc. malac. Soc. Lond. 36, 297–305. Page 298: second line from bottom, should read ‘within± 1 µg for Themapupa’. Page 300: Fig. 2 legend, should read ‘Evaporative waterloss from Sinumelon remissum (a), Pleuroxia sp. (b) and Themapupaadelaidae (c)’. Page 300: section 4 heading, should read ‘Continuous curvesfor water loss’. Page 301: second line, for ‘Fig. 9’ read ‘Fig.3’. Page 301: Table 1, last line, for ‘0.120024’ read‘0.12024’. Present address: Israel Institute for Biological Research, Ness-Ziona,Israel.