srb: a Bacillus subtilis Gene Encoding a Homologue of the {alpha}-Subunit of the Mammalian Signal Recognition Particle Receptor

We cloned a Bacillus subtilis gene (srb) encoding a homologueof the mammalian signal recognition particle receptor -subunit(SR). The gene is 987 bp in length and encodes a 329-amino acidprotein. The deduced amino acid sequence of the protein shared26.6, 36.2 and 49.7% identity with those of mammalian SR, archaebacterialDP and Escherichia coli FtsY, respectively. The protein containsthree conserved GTP-binding elements like the other three SRPreceptor proteins, though the N-terminal portion of the putativeB. subtilis protein was shorter than the others. Secondary structureprediction showed that an amphipathic -helix is positioned inthe N-terminal region. A defect in srb inhibited cell growthand protein translocation.     

Sialylation of n-alkyllactosides, galactosides and glucosides by sialyltransferases from rat liver Golgi vesicles

nAlkyl - and -lactosides, galactosides and glucosides with differentalkyl chain lengths (C₂, C₈, C₁₄, and C₂₀) were synthesizedand used as acceptors for sialyltransferases from rat liverGolgi vesicles. The -galactosides, -glucosides, and both - and-lactosides, were sialylated. Keeping the acceptor concentrationconstant, sialylation rates reached a maximum for the n-octyl- and -lactosides, n-Octyl -galactoside and noctyl -glucoside,respectively. noctyl -glucoside, respectivwly. n-Octyl -galactosideand n-octyl -glucoside were not sialylated. The reaction productswere characterized by TLC. With n-octyl lactoside and galactosideas acceptors, two major sialylation products were formed. Thjeycould be separated by preparative TLC, and their structureswere identified as 2–3 and 2–6 sialylated acceptors,respectively, by a combination of periodated oxidation, NaBD₄reduction,permethylation and subsequent analysis by fast atombombardment mass spectrometry (FAB-MS). The structure of thesingle product obtained from n-ictyl -glucoside was determinedto be the 2–6 sialylated glucoside. Competition experimentswith n-octyl lactoside and lactosylceramide and gangliosideGal1-3GalNAc1-4(NeuAc2–3)Gal1–4Glcbeeta1–1Cer(GM1) as acceptors for sialyltransferases suggested that SAT-I[NeuAc2–3Gal1–4Glc1-1Cer (GM3) synthase] was atleast in least in part responsible for the 2–3 sialylationof n-octyl lactoside. alkylgalactosides alkylglucosides alkyllactosides neoglycolipids sialytransferases     

Enzymatic Degradation of Chlorophyll in Chenopodium album

The breakdown of chlorophyll (Chi) in crude extracts of Chenopodiumalbum (white goose foot) in the dark was examined. Derivativesof pheophorbide were formed when Chi or chlorophyllide wasincubated with depigmented crude extracts. The formation ofpheophorbide was completely prevented by heat treatment of extracts,indicating that the reaction was enzymatic, and the presenceof a Mg-releasing enzyme, the so called Mg-dechelatase, waspostulated. This hypothesis was strongly supported by the observationthat the formation of pheophorbide was inhibited by 51% by 10mM MgCl₂. Analysis by high-performance thin-layer chromatography(HPTLC) and liquid chromatography (HPLC) showed that the appearanceof chlorophyllide , pheophorbide 13²-hydroxychlorophyllide and pyropheophorbide was accompanied by a concomitant decreasein levels of Chi The formation of 13²-hydroxychloro-phyllide was not clearly an enzymatic reaction and requires furtherexamination. It appears that Chl is degraded in a crude extractof C. album via the following enzymatically catalyzed reactions (Received September 10, 1990; Accepted November 15, 1990)     

Further characterization of the binding properties of a GalNAc specific lectin from Codium fragile subspecies tomentosoides

Previous study on the binding properties of a lectin isolatedfrom Codium fragile subspecies tomentosoides (CFT) indicatesthat this lectin recognizes the GalNAc1 sequence at both reducingand nonreducing ends. In this study, the carbohydrate specificityof CFT was further characterized by quantitative precipitin(QPA) and inhibition of lectin-enzyme binding assays. Of theglycoforms tested for QPA, all asialo-GalNAc1 containing glyco-proteinsreacted well with the lectin. Asialo hamster and ovine submandibularglycoproteins, which contain almost exclusively Tn (GalNAclSer/Thr)residues as carbohydrate side chains, and Streptococcus typeC polysaccharide completely precipitated the lectin added, whilethe GalNAcβcontaining Tamm-Horsfall Sd(a⁺) glycopro-teinand its asialo product were inactive. Among the oligo-saccharidestested for inhibiting lectin-glycoprotein interaction, GalNAc13GalNAcβ13Gal14Galβ14GIc(Fp)and Galβ13GalNAc1benzyl (T) were the best, and about 125-foldmore active than GalNAc They were about 3.3, 6.6, and 43 timesmore active than Tn containing glycopeptides, GalNAc13(LFuc12)Gal(A_h) and Galβ13GalNAc(T), respectively. From the presentand previous results, it is concluded that the combining siteof CFT is probably of a groove type that recognizes from GalNAclto pentasaccharide(Fp). The carbohydrate specificity of thislectin can be constructed and summarized in decreasing orderby lectin determinants as follows: Fp and T > Tn cluster> A_h >>I/II. carbohydrate specificities Codium fragile tomentosoides glycoprotein binding lectins     

Phosphorylation and subcellular location of {alpha}-L-fucosidase in Iymphoid cells from patients with I-cell disease and pseudo-Hurler polydystrophy

Mannose 6-phosphate is a recognition marker used by many newlymade acid hydrolases for their transport to lyso-somes. Previously,we investigated the incorporation of ³²Pi into -L-fucosidaseof lymphoid cell lines from a healthy individual (control) andan I-cell disease patient [DiCioccio and Miller, Glycobiology,1, 595–604 (1991)]. Phosphoserine was found in immunoprecipitable-L-fucosidase of both control and I-cell lymphoid cells, butmannose 6-phosphate was identified only in enzyme of controlcells. Extension of this investigation to lymphoid culturesof a pseudo-Hurler polydystrophy patient also identified onlyphosphoserine in -L-fucosidase. Using [³H] mannose instead of³²Pi, the precise identification of mannose 6-phosphate in -L-fucosidaseof control cells, and its absence in -L-fucosidase of I-celland pseudo-Hurler cells, was established. The stoichiometryof phosphorylation of -L-fucosidase in I-cell, pseudo-Hurlerand control lymphoid cells was 3, 4 and 10 mol Pi/mol enzyme,respectively. -L-Fucosidase was located in lysosomes isolatedfrom control, I-cell and pseudo-Hurler lymphoid cells by subcelluarfractionation on Percoll density gradients. Both I-cell andpseudo-Hurler lymphoid cells displayed normal intralysosomalactivity of -L-fucosidase despite lack of the mannose 6-phosphatemarker. Thus, I-cell and pseudo-Hurler lymphoid cells must possessa mannose 6-phosphate-independent mechanism for directing -L-fucosidaseto lysosomes. Phosphorylation of -L-fucosidase in pseudo-Hurlerand I-cell lymphoid cultures was found almost exclusively inintracellular and not in extracellular enzyme, suggesting thatphosphoserine may participate in the localization of -L-fucosidasein lysosomes of these cells. -L-fucosidase I-cell disease lysosome phosphorylation pseudo-Hurler polydystrophy     

A Transient Stimulation of Net Photosynthesis of Rye Leaves by {alpha}-Hydroxy-2-pyridinemethanesulphonic Acid ({alpha}-HPMS) due to Inhibition of Photorespiratory CO2 Release

The effects of -hydroxy-2-pyridinemethanesulphonic acid (-HPMS)upon net photosynthesis (P_n, the CO₂ compensation point (),post-lower illumination burst of CO₂ (PLIB) and post-lower temperatureburst of CO₂ (PLTB) in detached rye (Secale cereale L.) leaveswere investigated. At low concentrations ( 0.5 mol m^–3),-HPMS initially stimulated P_n and decreased the magnitude ofboth PLIB and PLTB. The decreased at all concentrations of-HPMS (0.05–5.0 mol m^–3. The effects of -HPMS onP_n and were time-dependent and, after a few minutes, the P_nwas inhibited while values increased considerably. At a higherconcentration (5.0 mol m ^–3), the transient effects of-HPMS were shorter () or not observed at all (P_n. Both PLIBand PLTB, when expressed in relation to P_n, increased at higherlevels of this compound. Similar data with respect to the effectsof -HPMS on PLIB and PLTB were found for leaves of dandelion(Taraxacum officinale L.). The results suggest that -HPMS may stimulate P_n by inhibitingphotorespiration, as originally suggested by Zelitch (1966),but only at low concentrations and over a short time span. Thedecrease of PLIB and PLTB values at low -HPMS levels is consistentwith these processes being a residual activity of the glycolatepathway. Key words: CO₂ compensation point, -hydroxy-2-pyridinemethanesulphonic acid, photorespiration, photosynthesis     

Application of N-terminally Truncated DNA Polymerase from Thermus thermophilus ({Delta}Tth Polymerase) to DNA Sequencing and Polymerase Chain Reactions: Comparative Study of {Delta}Tth and Wild-Type Tth Polymerases

N-Terminally truncated DNA polymerase from Thermus thermophilus(Tth polymerase) lacking 5'-3' exonuclease activity was usedfor DNA sequencing and polymerase chain reaction (PCR). In contrastto the high background of the sequencing ladder observed withthe wild-type Tth polymerase, Tth polymerase gave readable sequencingpatterns which extend up to more than 500 bases from the primersite on cycle sequencing and automated sequencing. The Tth polymerasewas used for the standard and mutagenic PCR, and net amplificationof the DNA and the mutations accumulated during PCR were analyzed.Under mutagenic PCR, the mutation rates were 7.0 x 10^–4(Tth) and 8.3 x 10^–4 (Tth) per nucleotide per cycle ofamplification, which were 4–9 times higher than the ratesunder standard PCR.     

Integrated likelihood functions for non-Bayesian inference

Consider a model with parameter = (, ), where is the parameterof interest, and let L(, ) denote the likelihood function. Oneapproach to likelihood inference for is to use an integratedlikelihood function, in which is eliminated from L(, ) by integratingwith respect to a density function (|). The goal of this paperis to consider the problem of selecting (|) so that the resultingintegrated likelihood function is useful for non-Bayesian likelihoodinference. The desirable properties of an integrated likelihoodfunction are analyzed and these suggest that (|) should be chosenby finding a nuisance parameter that is unrelated to and thentaking the prior density for to be independent of . Such anunrelated parameter is constructed and the resulting integratedlikelihood is shown to be closely related to the modified profilelikelihood.     

Analysis of Pressure-Volume Curves of Leaves of Rosa hybrida cv. Sonia

By analysing the relationship between inverse water potential(^–1), and relative water content (RWC) measured on leavesof roses (Rosa hybrida cv. Sonia), grown soilless, it was foundthat a non-linear (NL) model was better suited than a linearmodel to reproduce values observed in the non-turgid region.To explain this apparent curvature, it is assumed that a reductionof the non-osmotic water fraction (A_p) takes place when decreases.Osmotic potentials () measured on fresh and frozen leaf discstend to support this hypothesis. A method for exploiting PVcurves, which takes into account the variation of A_p, is described.It delivers values for the turgor pressure (_p), the relativeosmotic water content, and the mean bulk volumetric elasticitycoefficient, lower than those given by the linear model. Onthe other hand, it gives higher estimates for A_p and for . Whenapplying the traditional model to obtain estimates for waterrelations characteristics of rose leaves, and comparing resultsfrom two distinct salinity treatments (electrical conductivitiesof 1·8 mS cm^–1 and 3·8 mS cm^–1, respectively),one deduces a significant reduction of at turgor-loss in thehigh salinity treatment. The NL method is, in addition, ablesimultaneously to reveal a reduction of and a significant increasein _p at RWC=100% this proves that soilless–grown roseplants are able to osmoregulate when subjected to a constantand relatively high degree of salinity. Key words: Apoplastic water, non-linear regression, pressure-volume curves, tissue-water relations     

A Comparative View of Alpha Crystallins: The contribution of comparative studies to understanding function

Integration between comparative biology and cellular/molecularbiology has helped advance understanding of the structure, functionand physiology of the vertebrate small heat shock proteins A-and B-crystallin. These proteins are expressed at high concentrationin the eye lens where they contribute to transparency and refractivepower. But they also function similarly to molecular chaperonesby preventing the aggregation of denatured proteins that cancause opacities, or cataracts. -crystallins also serve a numberof other roles in and out of the lens that are still not completelyunderstood. Comparative examination of -crystallins and closelyrelated small heat shock proteins from diverse taxa has helpedprovide insights into the proteins' three-dimensional shapeand structure/function relationships. Until recently, no studieshad examined the tissue specific expression or chaperone-likeactivity of -crystallins from a non-mammalian vertebrate. Ihave been investigating the -crystallins of the zebrafish, Daniorerio, as a first step towards utilizing the bony fishes asa model group for understanding the evolution of -crystallinfunction. Zebrafish A-crystallin displays similar structureand expression and increased chaperone-like activity comparedto its human orthologue. Zebrafish B-crystallin, however, hasa truncated C-terminal extension, more limited expression andlower chaperone-like activity than its human orthologue. Thesedata suggest that A-crystallin physiological function may beconserved between zebrafish and mammals, while B-crystallinphysiological function has diverged. Understanding zebrafish-crystallin physiology is necessary before this species canbe used for developmental and genetic studies, and providesa foundation for further comparative studies.     

Seasonal Distribution of Carbohydrates in Nodules and Stem Exudate from Field-grown Soya Bean Plants

The concentration of carbohydrates in tap root nodules fromfield-grown soya bean [Glycine max (L.) Merr.] plants was verysimilar to the concentration of compounds previously reportedin greenhouse-grown nodules during vegetative growth of seedlings.The concentration of D-pinitol, sucrose and starch in nodulesdeclined during rapid fruit growth, but the concentration ofother compounds did not decline. The availability of carbohydratein nodules during fruit growth did not seem likely to be thecause of the decline in nitrogen-fixing activity of noduleswhich has been reported by others. All compounds except glucoseand , -trehalose declined to concentrations near zero duringa 10-day period of nodule decay. However, the decline in carbohydratedid not appear to cause nodule senescence because it did notprecede the period of decay and because decayed nodules containedsubstantial quantities of glucose and , -trehalose. Seasonalmean concentrations (72 samples from 24 dates) of compounds,in mg carbohydrate per g f. wt of nodule, were: sucrose, 2.84;D-pinitol, 1.14; D-chiro-inositol, 1.27; glucose, 1.40; , -trehalose,1.34; myo-inositol, 0.65; maltose, 0.31; and fructose, 0.21. Quantities of sugars and cyclitols in stem exudate collectedin the field on 13 dates were small (< 10 percent) relativeto the quantity of nitrogenous compounds transported from rootsto shoots. The seasonal pattern of pinitol transport in thexylem was very similar to the seasonal pinitol concentrationin nodules. A large increase in sugar concentration in stemexudate subsequent to 80 days after planting supports the viewthat lack of carbohydrate was not a cause of nodule senescence. Glycine max (L.) Merr, soya bean, cyclitols, , -trehalose, starch, D-pinitol, carbohydrates, root nodules, senescence     

Transmembrane-Domain Trapping: A Novel Method for Isolation of cDNAs Encoding Putative Membrane Proteins

We have developed a method that enables us to isolate cDNAsof putative membrane proteins. The system is designed to isolatea cDNA which can provide the transmembrane domain to the extracellularpart of the IL-2 receptor chain. We constructed a p18Mac vectorby putting part of the IL-2 receptor chain cDNA that encodedits signal sequence and extracellular domain, a cDNA cloningsite and a poly(A) additional signal after a strong promoterSR. If a cloned cDNA provides a transmembrane domain in-frame,the extracellular domain of the IL-2 receptor chain will beexpressed on the surface of the transfected cells. Otherwise,the chimeric protein will be either secreted or retained insidethe transfected cells. We made a cDNA library using p18Mac andscreened for cDNA clones which allowed the expression of theextracellular domain of the IL-2 receptor chain on the cellsurface. Of the 2000 clones screened, 5 clones were scored aspositive. Partial sequence analysis revealed that one cloneencoded the amyloid precursor protein, two others encoded mitochondrialproteins and the rest were new. These results suggest the systemis effective in isolating cDNAs encoding putative membrane proteins.     

{alpha}-Amylase synthesis by a cell free system and plant growth substances

A microsomal preparation from the aleurone layer pre-treatedwith GA or H-ol had the ability to synthesize -amylase whenit was incubated with an appropriate medium. -Amylase synthesiswas inhibited by the addition of p-fluorophenylalanine or bypre-treatment with RNase. The synthesized -amylase was separatedinto three isozymes by disc-electrophoresis (Received July 25, 1970; )     

Molecular dynamics simulations of oligosaccharides and their conformation in the crystal structure of lectin-carbohydrate complex: importance of the torsion angle {psi} for the orientation of {alpha}1,6-arm

The conformation of the heptasaccharide Man-1,6-(Man-1,3)(Xyl-ß1,2)-Man-ß,4-GlcNAc₂-ß1,4-(L-Fuc-1,3)-GlcNAc₁,the carbohydrate moiety of Erythrina corallodendron lectin (EcorL),the hexasaccharide Man-1,6-(Man-1,3) (GlcNAc-ß1,4)-Man-ß1,4-GlcNAc-ß1,4-GlcNAcand their disaccharide fragments have been studied by moleculardynamics (MD) simulations for 1000 ps with different initialconformations. In the isolated heptasaccharide, the most frequentlyaccessed conformation during MD has a value of 180° aroundMan-1,6-Man linkage. This conformation is stabilized by theformation of a hydrogen bond between the carbonyl oxygen ofGlcNAc₂ with the O3/O4 hydroxyls of the 1,6-linked mannose residue.The conformation of the heptasaccharide found in the crystalstructure of the EcorL-lactose complex (Shaanan et al., Science,254, 862, 1991), that has a value of 76° around Man-1,6-Manlinkage, is accessed, although less frequently, during MD ofthe isolated oligosaccharide. The ,, = 58°,–134°,–60°conformation around Man-₁,6-Man fragment observed in the crystalstructure of the Lathyrus ochnrs lectin complexed with a biantennaryoctasaccharide (Table I in Homans,S.W., Glycobiology, 3, 551,1993) has also been accessed in the present MD simulations.These values for the 1,6-linkage, which are observed in theprotein-carbohydrate crystal structures and are accessed inthe MD simulations, though occasionally, have not been predictedfrom NMR studies. Furthermore, these different values of leadto significantly different orientations of the 1,6-arm for thesame value of . This contrasts with the earlier predictionsthat only different values of can bring about significant changesin the orientation of the ₁,6-arm. The MD simulations also showthat the effects of bisecting GlcNAc or ß1,2-xyloseare very similar on the ₁,3-arm and slightly different on the₁,6-arm. bisecting GlcNAc carbohydrates glycoprotein lectinsaccharide complex     

Hydrophobic mannosides act as acceptors for trypanosome {alpha}-mannosyltransferases

A series of hydrophobic mannosides were synthesized and testedfor their ability to act as acceptor substrates for mannosyltransferasesin a Trypanosoma brucei cell-free system. The thiooctyl -mannosidesand octyl -mannosides all accepted single mannose residues in-linkage, as judged by thin layer chromatography of the productsbefore and after jack bean -mannosidase digestion. The mannosylationreactions were inhibited by amphomycin, suggesting that theimmediate donor was dolicholphosphate-mannose (Dol-P-Man) inall cases. The transferred -mannose residues were shown to beboth 1-2 and 1-6 linked by Aspergillus phoenicis -mannosidaseand acetolysis treatments, respectively. These data suggestthat the compounds can act as acceptor substrates for the Dol-P-Mandependent 1-2 and 1-6 mannosyltransferases of the GPI biosyntheticpathway and/or the dolichol-cycle of protein N-glycosylation.One of the compounds, Man1-6Man1-O-(CH₂)₇CH₃, inhibited endogenousGPI biosynthesis in the cell-free system, suggesting that itcould be a substrate for the trypanosome Dol-P-Man:Man₂GlcN-Pl1-2 mannosyltransferase. dolichol glycosylphosphatidylinositol mannosyltransferase trypanosome     

Adaptation of the Euryhaline Charophyte Lamprothamnium papulosum to Brackish and Freshwater: Turgor Pressure and Vacuolar Solute Concentrations During Steady-State Culture and After Hypo-osmotic Treatment

The euryhaline charophyte Lamprothamnium papulosum (Wallr.)J. Gr. was adapted to media with decreasing salinities rangingfrom 550 to 0 mosmol kg^–1. Vegetative plants grown inmedia with osmotic pressures (⁰) in the range of 550 to 130mosmol kg^–1 maintained a constant turgor pressure () at309 + 7 mosmol kg^–1. The ions K+, Na+ and Cl–, werethe predominant solutes in the vacuole. Changes in their concentrationsaccount for the variation in internal osmotic pressure (¹) with,⁰. The divalent ions Mg²⁺, Ca²⁺ and were also present in significant amounts, but their concentrationsdid not alter with changes in, ⁰. In cells subjected to hypo-osmotic shock the regulation of was incomplete. The turgor pressure increased from 302 to 383mosmol kg^–1. The first rapid response to the sudden decreasein ⁰ was a loss of K⁺ and Cl^–. In contrast to the decreasein ionic concentrations an accumulation of sucrose occurredwhich could account for the increase of . The increase in sucroseconcentration started 24 to 48 h after the downshock and reachedits highest value after 3 to 4 weeks. The sucrose concentrationin the vacuole was up to 320 mol m^–3. During this timethe ionic content continued to decrease but did not counterbalancethe sucrose concentration sufficiently to regain the original. High sucrose levels accompanied by an enhanced were also observedduring the period of fructification (sexual reproduction: formationof antheridia and oogonia) in Lamprothamnium kept under conditionsof constant salinity. It is concluded that high sucrose content and elevated arecharacteristic of sexual reproduction in this charophyte. Lamprothamniumis able to tolerate different during various developmentalstages (e.g. vegetative and reproductive phases). Key words: Lamprothamnium papulosum, sucrose, turgor pressure     

Isolation of Subunits of Coupling Factor 1 from Maize and Spinach Chloroplasts and Properties of Combinations of Subunits with ATPase Activity

Subunits (, ß, ) and mixtures of subunits ( ß, , ß , ß ) were isolated without denaturationfrom a chloroform extract of chloroplast coupling factor 1 (CF₁)from maize (Zea mays var. Ushiku 5-4) and from spinach by fastprotein liquid chromatography (FPLC), on an anion-exchange columnof Mono-Q in the presence of n-octylglucoside (OG) and on achromatofocusing column of Mono-P. The ß -subunitcomplex (CF¹ ß ) was the minimum unit required forATPase activity, as was confirmed by the reconstituted complexof ß and subunits. An subunit isolated from maizeinhibited the ATPase activity of CF₁ ß from bothmaize and spinach. CF₁ ß was found to contain anOG-dependent Mg²⁺-ATPase. The ATPase activity of CF₁ ß required divalent cations, such as Mg²⁺ or Mn²⁺, for its expressionin the presence of OG; its optimum pH was 8.0 and it was markedlyinhibited by NaN₃. The enzyme hydrolyzed ATP in prefernece toGTP but not CTP, UTP, ADP, AMP or pNPP. Lineweaver-Burk plotsof its activity were curvilinear in the range of 0.6–0.7mM ATP.Mg²⁺. ¹Present address: Department of Biology, School of Education,Waseda University, Shinjuku-ku, Tokyo, 160 Japan. (Received February 15, 1989; Accepted April 20, 1989)     

Stomatal Behaviour and Water Relations of Chilled Phaseolus vulgaris L. and Pisum sativum L.

Leaf diffusion resistance interpreted as stomatal resistance,leaf water potential (_w), solute potential (_s) and leaf turgorpotential (_p) of the chilling sensitive species Phaseolus vulgariswere determined during chilling at 4 °C in the light. Bothchill-hardened and non-hardened plants were used. For comparison,the chilling resistant species Pisum sativum was also used. The results for chilled P. sativum were similar to those obtainedfor chill-hardened P. vulgaris plants receiving a chilling treatment.In both cases a reduction in stomatal aperture and the maintenanceof a positive leaf turgor were the responses to chilling. Leavesof chilled but non-hardened P. vulgaris plants were found tomaintain open stomata throughout the chilling treatment despitea severe wilt developing after 7 h at 4 °C. This was incontrast to the chill-resistant P. sativum. which showed a rapidclosing and subsequent re-opening of the stomata to a new reducedaperture. During the first 12 h of chilling _wof P. vulgaris leaves changedfrom –0.47 MPa to –1.24 MPa. On more prolonged chilling_w tended to return to pre-chilling values. In addition. _p decreasedfrom 0.42 MPa to zero after only 9 h of chilling, and remainedat this value for the remainder of the chilling period, _s, changedrapidly from –0.89 MPa to –1.35 MPa in the first7.5 h, and after 9 h. _w and _s, were equal, i.e. zero _p. In contrast,the chilling resistant plant P. sativum maintained a positive_p throughout the chilling period, and there was little differencebetween values of _w, and _s in control and chilled leaves. Key words: Chilling, Stomata, ater relations, Phaseolus vulgaris, Pisum sativum