A monoclonal antibody directed against high Mr salivary mucins recognizes the SO3-3Gal{beta}1-3GlcNAc moiety of sulfo-Lewisa: a histochemical survey of human and rat tissue

Using a panel of synthetic oligosaccharides attached to a polyacrylamidecarrier, the epitope of monoclonal antibody F2, evoked to highM_r salivary mucins, was mapped to the SO₃-3Galß1-3GlcNAc-moiety of the sulfo-Le^a antigen. Using immunochemical techniques,the expression of the F2-epitope was investigated in a numberof different isolated human mucin species, as well as in humanand rat tissue specimens. The mAb F2 bound to high M_r salivarymucins, cervical mucins, colon mucins and gallbladder mucins,but not to low M_r salivary mucins nor to gastric mucins. Immunohistochemicalscreening of human tissues with mAb F2 revealed a positive reactionwith a number of epithelia, including the (sero)mucous salivaryglands, the goblet cells of the colon, submucosal glands ofthe lung, the lining epithelium of cervical and esophageal glands,the suprabasal skin keratinocytes, and Hassall's corpusclesof the thymus. No staining was found in normal breast, pancreas,small intestine, spleen, and lymph nodes. Normal gastric glandswere negative, but gastric intestinal metaplastic glands stronglystained with the antibody. In rat tissues, mAb F2 labeled epithelialcells of salivary glands, colon and stomach. In addition toepithelial cells, extracellular matrix components in rat thymusand skin were labeled by mAb F2. No labeling of erythrocytes,granulocytes, lymphocytes or bone marrow cells was found byFACScan analysis. The present data shows a tissue specific distributionof the F2-epitope in cells from the epithelial lineage in humanand rat. epithelial tissue sulfo-Lewis^a mucins mAbs immunohistochemistry     

Active oxygen participation in chlorophyll destruction and lipid peroxidation in SO2-fumigated leaves of spinach

Chlorophyll a and carotenoids of spinach began to be destroyed2 to 3 hr after fumigation with 2 ppm SO₂ under light, whereaschlorophyll b was undamaged during 8 hr of exposure to SO₂.Pheophytin a was not affected by the fumigation. When disks excised from leaves fumigated with SO₂ at 2 ppm for2 hr were illuminated, chlorophyll a and carotenoids were brokendown, while they were not destroyed in darkness. The destructionof these pigments was suppressed under nitrogen. Chlorophylla destruction was inhibited by l,2-dihydroxybenzene-3,5-disulfonate(tiron), hydro-quinone and ascorbate, but not by l,4-diazabicyclo-[2,2,2]-octane(DABCO), methio-nine, histidine, benzoate and formate. Chlorophylla destruction was inhibited by phenazine methosulfate but stimulatedby methyl viologen. Addition of superoxide dismutase (SOD) tothe homogenate of SO₂-fumigated leaves inhibited the chlorophylla destruction. The activity of endogenous SOD was reduced to40% by 2-hr fumigation before the loss of chlorophyll was observed.These results suggest that chlorophyll a destruction by SO₂was due to superoxide radicals (O₂^–). Moreover, malondialdehyde (MDA), a product of lipid peroxidation,was formed in SO₂-fumigated leaves. MDA formation was inhibitedby tiron, hydroquinone and DABCO but not by benzoate and formate.MDA formation was increased by D₂O. These results suggest thatlipid peroxidation in SO₂-fumigated leaves was due to singletoxygen ¹O₂ produced from O_2^–. (Received May 15, 1980; )     

Active oxygen participation in chlorophyll destruction and lipid peroxidation in SO2-fumigated leaves of spinach

Chlorophyll a and carotenoids of spinach began to be destroyed2 to 3 hr after fumigation with 2 ppm SO₂ under light, whereaschlorophyll b was undamaged during 8 hr of exposure to SO₂.Pheophytin a was not affected by the fumigation. When disks excised from leaves fumigated with SO₂ at 2 ppm for2 hr were illuminated, chlorophyll a and carotenoids were brokendown, while they were not destroyed in darkness. The destructionof these pigments was suppressed under nitrogen. Chlorophylla destruction was inhibited by l,2-dihydroxybenzene-3,5-disulfonate(tiron), hydro-quinone and ascorbate, but not by l,4-diazabicyclo-[2,2,2]-octane(DABCO), methio-nine, histidine, benzoate and formate. Chlorophylla destruction was inhibited by phenazine methosulfate but stimulatedby methyl viologen. Addition of superoxide dismutase (SOD) tothe homogenate of SO₂-fumigated leaves inhibited the chlorophylla destruction. The activity of endogenous SOD was reduced to40% by 2-hr fumigation before the loss of chlorophyll was observed.These results suggest that chlorophyll a destruction by SO₂was due to superoxide radicals (O₂^–). Moreover, malondialdehyde (MDA), a product of lipid peroxidation,was formed in SO₂-fumigated leaves. MDA formation was inhibitedby tiron, hydroquinone and DABCO but not by benzoate and formate.MDA formation was increased by D₂O. These results suggest thatlipid peroxidation in SO₂-fumigated leaves was due to singletoxygen ¹O₂ produced from O_2^–. (Received May 15, 1980; )     

Comparison of NMR and molecular modeling results for a rigid and a flexible oligosaccharide

Three-bond heteronuclear coupling constants (³J_CH) are extremelyuseful in describing flexible models for oligosaccharides. Weshow that antiphase methods for measuring ³J_CH in oligosaccharideshave limited reliability but that the coupling constants canbe reliably measured in natural abundance by quantitative J-correlationmethods. Interpretation of ³J_CH data for a pentasaccharide (lacto-N-fuco-pentaose2) from human milk are consistent with a rigid model for theLewis^a trisaccharide epitope but for an antigenic tetrasaccharidefragment from the cell wall polysaccharide of viridans streptococci,³J_CH data imply a considerably more flexible model. NuclearOverhauser effect (NOE) data are reported for a heptasacchariderepeating unit isolated from the cell wall polysaccharide ofStreptococcus gordonii 38. The results for a tetrasaccharidefragment are similar to data reported for the same fragmentin the cell wall polysaccharide from S.mitis 322. This resultimplies a similar conformation for the tetrasaccharide fragmentin the polysaccharide and in the heptasaccharide and also impliesthat anisotropy of motion is not significant in the interpretationof the nuclear Overhauser effects in the polysaccharide. Interpretationof the NOE results for the tetrasaccharide fragment, like the³J_CH data, implies a flexible model with three conformationsin fast exchange. The results of the two experimental techniquesare combined with molecular modeling results including moleculardynamics simulation to provide a clear delineation between flexibleand rigid oligosaccharide epitopes. The blood group Lewis^a trisaccharideantigenic determinant is highly restricted in its motions bysteric interactions while the antigenic tetrasaccharide fragmentof the S.gordonii 38 heptasaccharide is considerably more mobile.We propose that some branched oligosaccharides are relativelyrigid and some are flexible depending on subtle details of thelinkages. oligosaccharide conformation molecular dynamics     

Sulphate release from keratan sulphate and heparan sulphate by bovine N-acetylglucosamine-6-sulphate sulphatase

The functions of sulphated monosaccharides within glycosaminoglycans(GAGs) and glycoproteins are being studied intensely, but progressis hindered by an inability to selectively desulphate glycoconjugates.We recently identified an N-acetylglucosamine-6-sulphate sulphatase(NG6SS) from bovine kidney that can remove sulphate from N-acetylglucosamine-6-sulphate(GlcNAc-6-SO₄) within oligosaccharides and glycoproteins. However,the potential ‘endosulphatase’ activity of the NG6SStoward GAGs is not known. To test for this possibility, [³H]glucosamine-,[³H]galactose- and ³⁵SO_4- labelled keratan sulphate (KS) wereseparately prepared by metabolic radiolabelling of bovine cornea.NG6SS quantitatively removed sulphate from KS without releaseof sugar fragments. The enzyme had a K_m of 4.7 mM toward freeGlcNAc-6-SO₄, but its K_m for commercially available bovine cornealKS was found to be 9.1 µM. Analyses of both KS and heparansulphate after treatment with NG6SS demonstrated significantloss of sulphate from GlcNAc-6-SO₄ in both GAGs. These findingsmay be relevant for future studies aimed at defining the function(s)of GlcNAc-6-SO₄ residues in GAGs and understanding the catabolismof GAGs, especially in regard to sulphatidoses, such as SanfilippoD syndrome in humans, which involves a deficiency of NG6SS activity catabolism endosulphatase glycosaminoglycans sulphation     

Stomatal Responses to Sulphur Dioxide and Vapour Pressure Deficit

Stomatal conductances (g_s) of plants of Vicia faba, Raphanussativus, Phaseolus vulgaris, Heilanthus annuus, and Nicotianatabacum were measured in chambers containing either clean airor air containing between 18 and 1000 parts 10^–9 SO₂ atwater vapour pressure deficits (vpd) ranging from 1·0to 1·8 kPa. When vpd was low (<1·3 kPa at 22 °C) and stomatawere open, exposure to SO₂ induced rapid and irreversible increasesin g_s in V. faba. This response persisted throughout the exposure(3 d). The increase in g_s, 20–30% compared with cleanair, was independent of SO₂ concentration up to 350 parts 10^–9Stomatal conductances of polluted plants at night were greaterthan controls. When stomata were closed before exposure to SO₂,there was no effect on g_s. When vpd was varied, g_s of unpolluted plants of P. vulgarisshowed no response, but that of R. sativus increased slightlywith increasing vpd. In both species exposure to SO₂ causedan increase in g_s at all vpd values. g_s of unpolluted plantsof V. faba, H. annuus, and N. tabacum decreased with increasingvpd. At low vpd values exposure to SO₂ in these species causedan increase in g_s, but, above a certain value of vpd, dependingon species, g_s decreased with exposure to SO₂. It is postulated that SO₂, once in the substomatal cavity, entersthe stomatal complex via adjacent epidermal cells and at lowconcentrations leads to a reduction in turgor in these cellsand consequently to stomatal opening. In vpd-sensitive species,increased transpiration from guard cells or epidermal cellsadjacent to the stomata induced by SO₂ may lead to stomatalclosure at large vpd levels. Stomatal sensitivity to vpd insuch cases may be enhanced because adjacent epidermal cell turgoris lowered by SO₂. At high SO₂ concentrations direct disruptionof guard cell structure may lead to a loss of turgor and stomatalclosure.     

Modification of Stomatal Conductance by Sulphur Dioxide

The mechanism of SO₂-induced changes in stomatal conductance(g) of alder was examined to determine if SO₂ affects guardcell function directly or indirectly through the SO₂-inducedchanges in photosynthesis. During experimental fumigations at SO₂ concentrations of 3–3µmol m^–3 (0.08 µl l^–1), stomatal closurepreceded declines in net photosynthetic rate (A), indicatingthat SO₂ can directly affect guard cells. From these and otherstudies it appears that the sequence of A and g responses maybe influenced by SO₂ concentration as well as by species. Fumigation with SO₂ did not cause increases in g, even whenthe intercellular substomatal CO₂ concentration (c_i) was reducedby 50 µmol mol^–1. Increases in g are not attributableto SO₂ effects on the CO₂-based stomatal control system. Key words: Air pollution, Alnus serrulata, gas exchange, stomata, sulphur dioxide     

Absorption of SO2 by Pecan (Carya illinoensis (Wang) K. Koch) and Alfalfa (Medicago sativa L.) and its Effect on Net Photosynthesis

Absorption rates of SO₂ by pecan (Carya illinoensis (Wang) K.Koch) leaflets exposed to 2.6, 5.2, and 7.8 mg SO₂ m^–3were measured over a 2 h period. SO₂ was rapidly absorbed bythe leaflets in all treatments during the initial 30–50min; the rate of uptake decreased to a rather constant levelthereafter. Total SO₂ absorbed during the 2 h period was 15.6,25.6, and 38.9 nmol cm^–2 for the low, medium, and highSO₂ concentrations, respectively. Reductions in net photosyntheticrates were proportional to ambient SO₂ concentrations and totalSO₂ absorbed. Partial photosynthetic recovery occurred in alltreatments during a 2 h post-treatment period and full recoveryoccurred during a 12 h dark period. Exposure to SO₂ resultedin slight increases in stomatal and boundary layer resistancesto CO₂ and substantial increases in residual resistances. Absorptionrates of SO₂ by alfalfa (Medicago saliva L.) exposed to 5.2mg SO₂m^–3 for 1 h were approximately double those of pecanexposed to the same ambient SO₂ concentration. Alfalfa net photosyntheticrates were reduced 74% after 1 h exposure to 5.2 mg SO₂ m^–3while a depression of 42% occurred in pecan.     

Relative Importance of Ion Exclusion, Secretion and Accumulation in Spartina alterniflora Loisel.

The extent to which Spartina alterniflora Loisel. excluded,secreted or accumulated the major seawater ions (Cl^-, SO^2-₄,Na⁺, K⁺, Mg²⁺, and Ca²⁺) was investigated under varying salinitytreatments. From a quantitative viewpoint, ion exclusion wasmost prominent and accounted for 91–97% of the theoreticalmaximum ion uptake as a result of transpiration and growth.Of those ions taken up, approximately half was secreted fromthe shoots. Relative to K⁺, a disproportionate amount of Na⁺was excluded at the roots and secreted by the shoots. The concentrationwithin the tissues of S. alterniflora did not change with salinitytreatment for the majority of the ions examined, but Na⁺ wasmore than twice as concentrated at 40 g dm^-3 than at lOgdm^-3.Calculations of the flux of ions from salt marsh sediments tothe flood water via shoot secretion or stem/leaf turnover indicatethat these processes may be important to the ecology of S. alternifloraas mechanisms that limit the accumulation of salt within theroot zone.     

The Effect of Inorganic Nutrients on the Hormonal Requirements of Normal, Habituated, and Crown-gall Tissue 4

The addition of Braun and Wood's inorganic supplements (845mg l^–1 KCl, 1800 mgl^–1 NaNO₃, 300 mg l^–1 NaH₂PO₄.2H₂O,790 mg l^–1 (NH₄)₂SO₄) to White's medium caused markedincreases in the growth of normal tissues of Helianthus annuus,Nicotiana rustica, Daucus carota, and Vinca rosea and crown-galltumour tissues of H. annuus. However, no evidence was obtainedwhich suggested that the presence of these extra salts markedlyinfluenced the essential requirements of normal callus for auxinsand kinetin. In contrast their presence significantly influencedthe hormonal requirements of certain habituated cultures ofH. annuus and V. rosea. These habituated cultures had specificauxin requirements on White's medium while either an auxin orkinetin was sufficient on high-salts medium. These results arediscussed in relation to previous reports which suggested thatthe biosyntheses of auxins and other growth factors in normaland crown-gall cultures are specifically activated by certaininorganic ions.     

Regulation of the epithelial Na+ channel by intracellular Na+

The hypothesis that the intracellularNa⁺ concentration([Na⁺]_i)is a regulator of the epithelialNa⁺ channel (ENaC) was tested withthe Xenopus oocyte expression systemby utilizing a dual-electrode voltage clamp.[Na⁺]_iaveraged 48.1 ± 2.2 meq (n = 27)and was estimated from the amiloride-sensitive reversal potential.[Na⁺]_iwas increased by direct injection of 27.6 nl of 0.25 or 0.5 MNa₂SO₄.Within minutes of injection,[Na⁺]_istabilized and remained elevated at 97.8 ± 6.5 meq(n = 9) and 64.9 ± 4.4 (n = 5) meq 30 min after theinitial injection of 0.5 and 0.25 MNa₂SO₄,respectively. This increase of[Na⁺]_icaused a biphasic inhibition of ENaC currents. In oocytes injected with0.5 MNa₂SO₄(n = 9), a rapid decrease of inwardamiloride-sensitive slope conductance(g_Na) to 0.681 ± 0.030 of control within the first 3 min and a secondary, slowerdecrease to 0.304 ± 0.043 of control at 30 min were observed.Similar but smaller inhibitions were also observed with the injectionof 0.25 MNa₂SO₄.Injection of isotonicK₂SO₄(70 mM) or isotonicK₂SO₄made hypertonic with sucrose (70 mMK₂SO₄-1.2M sucrose) was without effect. Injection of a 0.5 M concentration ofeitherK₂SO₄,N-methyl-D-glucamine (NMDG) sulfate, or 0.75 M NMDG gluconate resulted in a much smaller initial inhibition (<14%) and little or no secondary decrease. Thusincreases of[Na⁺]_ihave multiple specific inhibitory effects on ENaC that can betemporally separated into a rapid phase that was complete within 2-3 min and a delayed slow phase that was observed between 5 and 30 min.

     

Effects of Low Concentrations of Sulphur Dioxide on Net Photosynthesis and Dark Respiration of Vicia faba

Rates of net photosynthesis, P_N, and dark respiration of Viciafaba plants were measured in the laboratory in clean air andin air containing up to 175 parts 10^–9 (500 µg m^–3)SO₂. At all SO₂ concentrations exceeding 35 parts 10^–9,P_N was inhibited compared with clean air. At light saturation,the magnitude of inhibition depended on SO₂ concentration butat low irradiances the inhibition was independent of concentration.Dark respiration rates increased substantially, independentof concentration. When exposures continued for up to 3 days,P_N returned to clean air values about 1 h after fumigation ceased:dark respiration recovered after one photoperiod. There wereno visible injuries. Reviewing possible mechanisms responsible for the inhibitionof P_N, it is suggested that SO₂ competes with CO₂ for bindingsites in RuBP carboxylase. Analysis of resistance analoguesdemonstrates that SO₂ altered both stomatal and internal (residual)resistances. A model of crop photosynthesis shows the implications of theobserved responses for the growth of field crops in which plantsare assumed to respond like laboratory plants. Photosynthesisof the crop would be less sensitive than that of individualplants to SO₂ concentration. Daily dry matter accumulation ofhypothetical ‘polluted crops’ would be substantiallyless than clean air values but would vary relatively littlewith SO₂ concentration. It is concluded that physiological basesexist to account for observed reductions in growth of plantsat very low SO₂ concentrations, and that thresholds for plantresponses to SO₂ require reassessment.     

Borate absorption in excised sugarcane leaves

Borate absorption in sugarcane consists of a rapid and reversibleinflux into the mesophyll cells of the leaf which is completedwithin 20 rains. (Phase I), followed by a slower and irreversibleaccumulatory phase (II). Phase II uptake represents the summationof 3 absorption mechanisms, each dependent upon the externalconcentration. Highly specific mechanisms 1 and 2 transportborate across the initial barrier into the cells, reaction 3carries the borate across the vacuolar membrane. Calcium isshown to be essential for maximum rates of borate absorption.All 3 reactions are inhibited by OH^– through a combinationof competitive inhibition and irreversible disruption of cellularfunction or structure. Temperature changes over the range of10–40 profoundly affect V_maz and K_m1, but have no effecton K_m2 and K_m3. Reactions 1 and 2 are unaffected by 50 mtl Cl^–,SO^–– or H2PO4^–, whereas each of these anionscompetes with H2BO3^– for site 3. Specific metabolic inhibitorswere used to delineate a linkage of mechanisms 1 and 2 to respiratoryelectron transport. Mechanism 3 is coupled to oxidative phosphorylation. ¹Published with the approval of the Director of the Hawaii AgriculturalExperiment Station as Technical Paper No. 954.     

The optical properties of a turbid reservoir and its phytoplankton in relation to photosynthesis and growth (Mount Bold Reservoir, South Australia)

In situ light measurements were used to obtain information oninherent and apparent optical properties. The average verticalattenuation coefficient K_d(ave) varied from 1.1 to 4.6 In unitsm^–1 During three periods the variation in K_d(ave) correlatedwith changes in chlorophyll a concentration and specific attenuationcoefficients K_s, of 0.013, 0.014 and 0.022 m² mg Chl a^–1were calculated. Chlorophyll-specific diffuse absorption coefficients(A,) for these periods were 0.012. 0.013 and 0.017 m² mg Chla^–1 and only varied significantly from estimates of K_sin the period when scattering was intense. Absorption coefficientsa(z^mid) and scattering coefficients b(z^mid) calculated for themid-point of the euphotic zone ranged between 0.45 and 2.9 mand 3.5–52.0 m respectively. Chlorophyll-specific absorptioncoefficients K_a, of 0.005, 0.006 and 0.007 m² mg Chl a^–1and scattering coefficients K_b of 0.05. 0.09 and 0.191 m² mgChl a^–1 were measured during the three periods. The highK_b value occurred when gas-vacuolate cyanobactena were dominant.Algal photosynthesis and light absorption were related throughthe maximum quantum yield _m which varied between 0.019 and 0.11mol C Einstein^–1 while average quantum yields _a, variedbetween 0.006 and 0.024 with a mean of 0.013 mol C Einstein^–1A comparison of changes in the mean irradiance of the mixedzone and chlorophyll concentration indicated that growth waslight limited below 0.04–0.05 Einsteins absorbed mg Chla^–1 day^–1.     

Nonreductive release of O-linked oligosaccharides from mucin glycoproteins for structure/function assignments as neoglycolipids: application in the detection of novel ligands for E-selectin

The neoglycolipid technology comprises several microproceduresinvolving the generation of lipid-linked oligosaccharide probesfor carbohydrate recognition studies in conjunction with oligosaccharidesequence determination by mass spectrometry. Although applicableto any desired oilgosaccharides, procedures are greatly facilitatedif the ohgosaccharides are nonreduced, as conjugation is byreductive amination of a reducing end aldehyde to a phosphatidylethanolamine.Using bovine submaxillary mucin as a model for release of O-glycansin the reducing state, and based on yields of neoglycolipidsand side-products from "peeling" reactions and degradation,aqueous ethylamine 70% w/v at 22°C for 48 h has been selectedin preference to other conditions, triethylainine, sodium hydroxide,and bydrazine. The integrity of the main acidic and neutraloligosaccharides released under these conditions, di- to octasaccharides,was established by analyses of free oligosaccharides by liquidsecondary ion mass spectrometry (LSIMS) and of the derived neoglycolipidsby TLCLSIMS; the repertoire compared favorably with that ofthe oligosaccharide alditols generated by conventional reductivealkaline borohydride treatment. More forcing conditions of ethylamine70% w/v at 65°C for 6 h were required to release oligosaccharidesfrom porcine gastric mucin; di- to nonasaccharides were obtainedof which about one-third had an intact core GalNAc. Relativeto yields after reductive alkaline hydrolysis, the overall yieldsfor these two glycoproteins were 20% and 40–50% for acidicand neutral oligosaccharides, respectively. Among O-glycansreleased from an ovarian cystadenoma glycoprotein using ethylamine,three variants of the sulfated Le^a/x sequences were identifiedas ligands for the endothelial adhesion molecule E-selectin,one of which is based on the unusual backbone Gal-3/4GlcNAc-3Gal-3Gal. mucins O-linked oligosaccharides TLC-LSIMS neoglycolipids E-selectin     

The Effect of Salinity Changes Upon the Physiology of Eulittoral Green Macroalgae from Antarctica and Southern Chile: II INTRACELLULAR INORGANIC IONS AND ORGANIC COMPOUNDS

The effects of hypo- and hypersaline treatments ranging from7–68% on the intracellular inorganic ion and organic soluteconcentrations were determined in the eulittoral green macroalgaeUlothrix implexa, Ulothrix subflaccida, Enteromorpha bulbosa,Acrosiphonia arcta, and Ulva rigida from Antarctica and SouthernChile. The main inorganic cations were K⁺, Na⁺, and Mg²⁺ inall species. The major osmolyte in E. bulbosa, A. arcta, andU. rigida was K⁺ at increasing salinities. In both Ulothrixspecies, however, K⁺ levels declined during hypersaline stressand Na⁺ concentrations rose significantly. The main inorganicanions were Cl^-, SO²_4-, and PO³_4- in all algae, while E. bulbosaand U. rigida also contained NO⁺₃. A. arcta showed an extremelyhigh SO^2-₄ content. The organic solutes proline, sucrose, andß-dimethylsulphoniopropionate (DMSP) played an importantrole in osmotic acclimation. The occurrence of three organicosmolytes suggests an additional function of these solutes ascryoprotectants in the cold-water macroalgae investigated.     

Partitioning and redistribution of sulphur during S-stress in Macroptilium atropurpureum cv. Siratro

During the first 7 d of sulphate-deprivation stored SO₄^2- wasredistributed and assimilated into organic forms in the tropicallegume Macroptilium atropurpu-reum cv. Siratro. However, whilstthe sulphate content of all tissues declined after removingthe external SO₄^2- supply this was slowest in mature leaves.By contrast, the total S content of mature leaves declined markedlyin the absence of external sulphate whilst that of both youngleaves and roots increased. Furthermore, when radiolabelledSO₄^2- was applied to abraded surfaces of mature leaves, mostof the translocated label was recovered in the root following2 d SO₄^2- deprivation. By contrast, radiolabelled SO₄^2-appliedto young leaves was mostly retained in these tissues and nottranslocated. Within 3 d of removing the SO₄^2- supply there was a large increasein extractable APS-sulphotransferase activity in roots accompaniedby a decline in nitrate reductase activity, but these effectswere not seen in leaves. Five days after the removal of SO₄^2-there was a large increase in the content of asparagine in roots. The results are discussed in relation to the co-ordination ofNO₃^- and SO₄^2- uptake and assimilation and the partitioningof sulphur during S-stress. Key words: Sulphate supply, stomatal conductance, ATP-sulphurylase, APS-sulphotransferase, nitrate reductase     

Monoclonal antibody 91.9H raised against sulfated mucins is specific for the 3'-sulfated Lewisa tetrasaccharide sequence

The IgG1hybridoma antibody, 91.9H, was originally raised against sulfated mucins isolated from normal human colonic mucosa. Previous studies have shown that the 91.9H antigen is expressed on normal colonic epithelial cells and the sulfomucins that they produce, but not in the normal small intestine and stomach. Tissue-specific changes occur in 91.9H antigen expression in disease: the antigen diminishes in colonic carcinomas, whereas in regions of gastric mucosa showing intestinal metaplasia and in gastric carcinomas, the antigen is expressed as a "neo-antigen." This report is concerned with elucidation, by the neoglycolipid technology, of the determinant recognized by antibody 91.9H using sulfated and sialyl oligosaccharides of Lewisa(Lea) and Lextypes, and analogs that lack sulfate, sialic acid, or fucose. Binding experiments with the lipid-linked oligosaccharides immobilized on chromatograms or on microwells, and inhibition of binding experiments with free oligosaccharides based on di-, tri- and tetrasaccharide backbones, show that the 91.9H antigenic determinant is based on a trisaccharide backbone, and consists of the 3'-sulfated Leatetrasaccharide sequence, which is a potent ligand for the E- and L-selectins. The antibody gives a relatively low signal with the 3'-sulfated non-fucosylated backbone, and has no detectable cross- reaction with the 3'-sulfated Lexisomer, nor with sialyl-Leaand - Lexanalogues. Antibody 91.9H is a valuable addition, therefore, to the repertoire of reagents for mapping details of the distribution, and determining the relative importance of sulfated and sialyl oligosaccharides as ligands for the selectins, in normal and pathological epithelia and endothelia.      

Effects of sulfite and pH on abscisic acid-dependent transpiration and on stomatal opening

In rice, alday, wheat and tobacco (Nicotiana tabacum L. Samsunand Samsun NN) plants which contained large amounts of ABA,the transpiration rate decreased rapidly with 2 ppm SO₂ fumigationand reached 20 to 65% of the initial level after 5- to 30-minexposure depending on their ABA contents. In the cases of broadbean and tobacco (N. glutinosa L.) with low ABA contents, therate slightly increased for 20 and 40 min, respectively, afterthe start of the fumigation and then decreased gradually. Thetranspiration rates of corn and sorghum, in spite of their extremelylow ABA contents, pronouncedly decreased with SO₂ fumigationand reached 65 and 50%, respectively, of the initial levelsafter 40-min exposure. Foliar application of 0.04 N HC1 to N.tabacum L. Samsun NN leaves remarkably depressed the transpirationrate, while the application of 0.04 M Na₂SO₃ decreased the rateonly to the same level as water treatment. Foliar applicationof either HCl or Na₂SO₃ to N. glutinosa L. leaves exerted littlechange in the transpiration rate. When 10^–4M ABA was appliedto broad bean leaves prior to HCl and Na₂SO₃ treatment, theirtranspiration rate was decreased by HCl, but not by Na₂SO₃ application.In sonicated epidermal strips peeled from broad bean leaves,Na₂SO₃ produced a slight increase in the stomatal aperture sizein the absence of ABA, but showed no effect in the presenceof ABA. The aperture size was identical in the pH range of 3.0to 7.0 in the incubation medium. In the presence of ABA in themedium, the aperture size was small in the acidic region ofpH with a minimal value at pH 4.0. ABA decreased the aperturesize at concentrations above 10^–9 M at pH 4.0 and 10^–6M at pH 7.0 in the medium. [2_–14C] ABA uptake by epidermalstrips was large in the acidic region, especially at pH 4.0. (Received February 28, 1980; )     

A sulfite-dependent adenosine triphosphatase of Thiobacillus thiooxidans. Its partial purification and some properties

A sulfite-dependent ATPase [EC 3.6.1.3 [EC] ] of Thiobacillus thiooxidanswas activated and solubilized by treatment with trypsin [EC3.4.4.4 [EC] ], and purified 84-fold with a 32% recovery. It requiredboth Mg²⁺ and SO₃^2– for full activity, and its optimumpH was found at 7.5–8.0. Mn²⁺, Co²⁺, and Ca²⁺ could partiallysubstitute for Mg²⁺, while SeO₃^2– and CrO₄^2– couldpartially substitute for SO₃^2–. The enzyme hydrolyzed ATP and deoxy-ATP most rapidly and otherphosphate esters were poorer substrates. The apparent Km valuefor ATP was 0.33 mM. The enzyme activity was strongly inhibitedby 0.2 mM NaN₃ and 10 mM NaF. (Received July 27, 1977; )