Lipoxidase in early growth of wheat

Lipoxidase activity in etiolated wheat seedlings grown for 3.5days was localized primarily in the coleoptile and first leafof the seedling with moderate activity in the germinated seedand root. After 7 days growth, the distribution of lipoxidasewithin the plant did not change markedly while the total activitydecreased. The dormant wheat seed exhibited 2 major and 2 minor bands oflipoxidase activity on polyacrylamide gel zymograms. After germination,there was a marked change in the relative intensities of the4 lipoxidase bands depending on the part of the seedling assayed. ¹ Supported in part by funds from the Agricultural ResearchService, U. S. Department of Agriculture Grant No. 12-14-100-7654(74)administered by the Western Utilization Research and DevelopmentDivision, Albany, California. Published with the approval ofthe Director of the Wisconsin Agricultural Experiment Station. ² Present address: U. S. Department of Agriculture, NorthernGrain Insects Research Laboratory, Brookings, South Dakota 57006,U.S.A. ³ Present address: Institute of Experimental Phytopathologyand Entomology, Ivanka Pri Dunaji, Czechoslovakia.     

Biological Significance of Divalent Metal Ion Binding to 14-3-3 Proteins In Relationship to Nitrate Reductase Inactivation

In this report we address two questions regarding the regulationof phosphorylated nitrate reductase (pNR; EC 1.6.6.1 [EC] ) by 14-3-3proteins. The first concerns the requirement for millimolarconcentrations of a divalent cation in order to form the inactivepNR: 14-3-3 complex at pH 7.5. The second concerns the reducedrequirement for divalent cations at pH 6.5. In answering thesequestions we highlight a possible general mechanism involvedin the regulation of 14-3-3 binding to target proteins. We showthat divalent cations (e.g. Ca²⁺, Mg²⁺ and Mn²⁺) bind directlyto 14-3-3s, and as a result cause a conformational change, manifestedas an increase in surface hydrophobicity. A similar change isalso obtained by decreasing the pH from pH 7.5 to pH 6.5, inthe absence of divalent cations, and we propose that protonationof amino acid residues brings about a similar effect to metalion binding. A possible regulatory mechanism, where the 14-3-3protein has to be "primed" prior to binding a target protein,is discussed. ¹Co-operative investigations of the U.S. Department of Agriculture,Agricultural Research Service, and the North Carolina AgriculturalResearch Service, Raleigh, NC. This work was supported by agrant from the U.S. Department of Agriculture-National ResearchInitiative (Grant 93-37305-9231 to JLH and SCH). Mention ofa trademark or proprietary product does not constitute a guaranteeor warranty of the product by the USDA or the North CarolinaAgricultural Service. Nor does it imply its approval to theexclusion of other products that might also be suitable.     

Alfalfa saponins as inhibitors of cotton seed germination

The inhibitory effect of alfalfa saponins on the germinationof cotton seeds was primarily attributed to interference withthe seedcoat and with the membrane. This effect was not dueto impermeability to water. ¹This work was supported in part by grant No. FG-Is-246 fromthe U.S. Department of Agriculture, and a grant from the Committeefor the Encouragement of Research, General Federation of Labour,in Israel (Received December 8, 1969; )     

COMPARATIVE STUDIES OF PHOTOSYNTHETIC PROCESSES IN ORDINARY AND FULLY DEUTERATED ALGAE

The light-saturated growth rate of fully deuterated algae hasbeen found less than that of ordinary algae by a factor of threeto four. However, as compared to the net rate of photosynthesis,the Hill reaction rate indicates an unimpaired light reactionsystem. Analysis of cell extracts for amino acid content and¹⁴C-uptake studies indicate a decreased utilization of the productsof photosynthesis by deuterated algae, probably because of agenerally lowered protein metabolism. We conclude that in algaeD₂O does not have a pronounced effect on the light reactionin photosynthesis. ¹ Based on work performed under the auspices of the U. S. AtomicEnergy Commission. ² Resident Research Associate, 1962–64. ³Present address: University of Illinois, Department of Pharmacy,Chicago, Illinois.     

Effects of chloramphenicol on RNA synthesis in Spirodela chlorplasts

RNA from chloroplasts isolated from Spirodela oligorrhiza includedrelatively rapidly-labeled fractions with apparent molecularweights of 2.7; 1.2; 0.7; and 0.5x10⁶. With longer labeling,radioactivity appeared in the mature rRNAs (1.1 and 0.56x10⁶MW). Chloramphenicol inhibited the appearance of labeled maturerRNA, but increased the net labeling and caused the accumulationof the pulse-labeled RNAs, effects similar to those reportedfor bacteria. ¹ 1 Permanent address: Dept. of Biological Sciences, S.U.N.Y.,Binghamton, N.Y. 13901, U.S.A. Supported by a SUNY/ResearchFoundation Faculty Research Fellowship. (Received November 12, 1974; )     

ON THE GUSTATORY EFFECTS OF MIRACULIN AND GYMNEMIC ACID IN THE MONKEY

The summated response from the chorda tympani proper nerve of9 monkeys was recorded during stimulation with solutions ofacetic and citric acids, sodium chloride, quinine sulfate, sucrose,glucose and fructose before and after application of extractsof Synsepalum dulcificum-miraculin- and Gymnema sylvestre-gymnemicacid-on the tongue. It was observed that (a) miraculin enhancedthe response to all acids used (b) miraculin had no significanteffect on the response of the other taste stimuli (c) its effectlasts for more than h and was not removed by rubbing of thetongue (d) gymnemic acid had no significant effect on the responseto any of the stimuli used if miraculin had not been appliedbeforehand (e) gymnemic acid applied after miraculin diminishedthe response to acid, then miraculin enhanced the response toacid again. It was concluded that these electrophysiologicalfindings in monkey parallel the psychophysical observationsin man with regard to the effect of miraculin and gymnemic acidon the response to acids, but that they differ with regard tothe effect of gymnemic acid on the response to sugars. ^* On leave from Dept. of Psychology, University of New Hampshire,U.S.A. ^** On leave from Dept. of Oral Physiology, Osaka University,Japan.     

In vivo citrate studies with developing soybean cotyledons

The in vivo data presented here are strong evidence for theinvolvement of citrate cleavage enzyme in lipid synthesis indeveloping soybean cotyledons. The incorporation of ¹⁴C fromcitrate into crude lipid fraction in vivo had a pH optimum of4.5; was linear with time; had a temperature optimum of 35?C;and was inhibited by (–)-hydroxycitrate. The point ofcitrate cleavage was between carbons 3 and 4 of the citratemolecule and therefore ¹⁴C was incorporated into crude lipidfraction from citrate-5-¹⁴C but not citrate-1-¹⁴C or citrate-6-¹⁴C. ¹ Cooperative investigations of the Agricultural Research Service,U.S. Department of Agriculture, and the Illinois AgriculturalExperiment Station. ² This research represents partial fulfillment of the Ph.D.requirements of Daniel R. Nelson. Presently at Monsanto AgriculturalProducts Co., St. Louis, MO 63141, U.S.A. (Received September 20, 1976; )     

Correlation of cytokinins and abscisic acid with monocarpic senescence in soybeans

The involvement of cytokinins and abscisic acid (ABA) in themonocarpic senescence (foliar yellowing following fruit development)of soybeans was examined. Foliar sprays of cytokinin (10^–4M zeatin or 10^–5 M benzyladenine), begun when the plantsfirst set fruit and repeated every other day, significantlydelayed, but did not prevent, monocarpic senescence. Foliarsprays of 10^–4 M ABA, applied in the same manner, significantlyhastened senescence of fruiting soybeans but apparently hadno effect on depodded plants. Leaf and stem material from pre-senescentand senescent plants was extracted, chromatographed, and bioassayedfor cytokinin-lilce activity (Amaranthus betacyanin productionassay) and ABA-like activity (oat coleoptile straight growthassay for inhibitors). ABA-like activity increased, and cytokinin-likeactivity decreased in shoot tissue before the plants began tosenesce. Cytokinin-like activity in the fruit also declinedduring this period. These results implicate a decrease in cytokininsand an increase in ABA-like inhibitors in the control of monocarpicsenescence of soybeans, but neither alone is causal. ¹ Supported in part by Research Grant 416-15-79 from the USDACooperative State Research Service under PL 89–106. ² Present address: Biology Dept., College of St. Benedict'sSt. Joseph, Minn. 56374, U.S.A. (Received February 4, 1978; )     

cytokinin-induced amylolytic activity in bean cotyledons: Identification of the regulated enzyme

Separation of an extract of cotyledons of Phaseolus vulgarison a column of Sephadex G-200 revealed three amylolytic fractions.The slower migrating fraction hydrolyzed/ß-Limit dextrinazure and was inhibited by EDTA. The activity of this fractionwas enhanced by the embryo axis and this effect could be fullyreplaced by kinetin or benzyladenine. These results suggestthat the bean embryo axis exerts a promotive influence on theactivity of a-amylase in the cotyledons and that this effectis mediated by cytokinins. The other two amylolytic fractions did not show a-amylase activity.No effect of the embryo axis or of cytokinins on their activitycould be noted. ¹Present address: The Thimann Laboratories, University of California,Santa Cruz, California, U.S.A. (Received June 27, 1979; )     

The effect of barban on shoot formation in tobacco callus cultures

Shoot formation in tobacco callus was completely inhibited bythe presence of barban in the media during the first 2 daysof culture. Callus transferred to media containing barban from4th to the 12th day showed progressively less inhibition. Similarresults were obtained with GA₃. ¹Present address: Biology Department, Chung Chi College, TheChinese Univ. of Hong Kong, Shatin, N.T., Hong Kong ²Present address: Plant Hormone & Regulator Pioneering ResearchLab., U.S. Dept. Agric, Crops Res. Div., Beltsville, Md., U.S.A. (Received April 21, 1970; )     

Optical emission spectrographic studies on the distribution and accumulation of nanogram amounts of 15N in rice seedlings

An optical emission spectrographic method was used to studythe distribution and accumulation of nanogram quantities of¹⁵N in leaves and roots of individual rice plants. Gaseous nitrogenthat was prepared from plant samples, not weighing more than100 µg, was trapped in an electrodeless tube. The excess¹⁵N was determined by exciting the gas with a high frequencygenerator, then measuring the light intensities of the molecularbandheads at 2977, 2983 and 2989 ?. For leaves that contained4 atom % ¹⁵N the precision obtained was ?1.33%. A comparisonof emission and mass spectrographic ¹⁵N values were obtainedwith a number of second leaves of rice plants that were grownunder similar environmental conditions. The ¹⁵N contents obtainedat a 2 atom % level by the 2 methods were in reasonable agreement. ¹Permanent address: University of Tokyo, Dept. of Agr. Chem.,Japan. ²Permanent address: Argonne National Lab., Argonne, Illinois,U. S. A. (Received April 2, 1969; )     

Protein Synthesis Linked to Respiration and Phosphorylation in Intact Euglena Mitochondria

Highly purified condensed mitochondria obtained from bleachedmutant. W₁₀BSmL of Euglena gracilis Klebs var bacillaris Coriincorporate [³⁵S]methionine into protein when fortified withmalate, ADP, Mg²⁺, phosphate and a sucrose osmoticum. Twentyto twenty-five polypeptide bands were found to be labeled inorganello when the labeled protein was subjected to sodium dodecylsulfatepolyacrylamide gel electrophoresis. Methionine incorporation,but not respiration or oxidative phosphorylation, was blockedby chloramphenicol and other 70S ribosomal translation inhibitorsbut cycloheximide and ribonuclease were without effect. Inhibitorsof electron transport and uncouplers of oxidative phosphorylationwere excellent inhibitors of protein synthesis. Thus, thesemitochondrial preparations carry out protein synthesis in organellothat is linked to respiration and oxidative phosphorylation. ¹Present address: VA Hospital Outpatient Clinic, 17 Court St.,Boston, MA 02115, U.S.A. ²Present address: Laboratories de Microbiologia e Inmunologia,Universidad Catolica de Chile, Casilla 114-D, Santiago, Chile. ³Present address: Botany Department, University of Massachusetts,Amherst, MA 01003, U.S.A. (Received June 17, 1985; Accepted October 28, 1985)     

Gel electrophoresis studies of proteins from leaves of photoperiodically induced and vegetative cocklebur plants

Comparisons of proteins synthesized in photoperiodically-sensitiveleaves of induced and vegetative cocklebur plants were made.Fifteen or more protein bands could be separated by polyacrylamidegel electrophoresis when polyvinylpyrrolidone was used in theextracting buffer to remove phenolics. As contrasted to resultsof others with Pharbilis nil, no differences in stained bandingpatterns could be detected in vegetative and induced plants.Radioactive leucine, lysine and phenylalanine were incorporatedinto similar leaf proteins during the last half of an inductivedark period. These experiments and dual-labeling studies with³H- and ¹⁴C-phenylalanine indicated no consistent differencesin the types of extracted proteins synthesized by leaves ofvegetative and induced plants. ¹Present address: Plant Science Dept., Utah State University,Logan 84321, U.S.A. (Received October 26, 1970; )     

Polyamines and Somatic Embryogenesis in Carrot. III. Effects of Methylglyoxal bis(guanylhydrazone)

The effects of methylglyoxal bis(guanylhydrazone) (MGBG) onsomatic embryogenesis, titres of cellular polyamines and 1-aminocyclopropane-l-carboxylicacid, and the activity of arginine decarboxylase (ADC) werestudied using suspension cultures of carrot (Daucus carota L.).Whereas MGBG (0.1–0.5 mM) significantly inhibited thecellular levels of spermidine and spermine, putrescine levelswere higher in the treated tissue. MGBG also promoted ACC levelsin the cells. The activity of ADC was inhibited in the presenceof MGBG. Somatic embryogenesis in the auxin-free medium wascompletely inhibited by MGBG. The effects of MGBG on somaticembryogenesis were reversed by 0.1–0.2 mM spermidine butnot by spermine. These results are consistent with the suggestionthat an interaction between ethylene and polyamine bio-syntheticpathways through competition for the common precursor, S-adenosylmethionine,plays an important role in the development of somatic embryosin carrot cell cultures. ¹Scientific Contribution Number 1649 from the New HampshireAgricultural Experiment Station. This research was supportedby NSF Grant No. DCB-8615945, Central University Research Funds,UNH, and NHAES Project H-233 ²Present address: Nancy S. Papa, In Vitron Corporation, 4649LeBourget Drive, St. Louis, MO 63134, U.S.A. ³Present address: Dr. A. Jamal Khan, Department of Plant Science,College of Agriculture, Sultan Qaboos University, P.O. Box-32484,Al-Khod, Muscat, Sultanate of Oman (Received September 17, 1990; Accepted January 21, 1991)     

Localization and Binding Characteristics of a High-Affinity Binding Site for N--Acetylchitooligosaccharide Elicitor in the Plasma Membrane from Suspension-Cultured Rice Cells Suggest a Role as a Receptor for the Elicitor Signal at the Cell Surface

A high-affinity binding site for N-acetylchitooligosac-chlarideelicitor was found to localize in the plasma membrane from suspension-culturedrice cells. Binding kinetics as well as the specificity of thisbinding site corresponded well with the behavior of the ricecells to the editor. These characteristics suggest that thebinding site represents a functional receptor for N-acetylchitooligosaccharideelicitor in rice. ²Present address: Okinawa Prefectural Livestock ExperimentalStation, 2009-5 Shoshi, Nakijin-son, Okinawa, 905-04 Japan. ³Present address: School of Hygiene and Public Health, The JohnsHopkins University, 615 North Wolfe Street, Baltimore, Maryland,21205 U.S.A. ⁴Present address: University of Tenessee, Microbiology, knoxville,Tennessee, 37996 U.S.A.     

Effect of Calcium on Cell Wall Structure, Protein Phosphorylation and Protein Profile in Senescing Apples

The effect of Ca⁺⁺ on various parameters of apple fruit senescencewas investigated. Distinct and specific changes in polypeptideand phosphoprotein patterns were observed in Ca⁺⁺ treated ascompared to control fruits. A 70 kDa salt-extracted polypeptidebecame apparent in control fruits after 8 months of cold storagewhich was not apparent in Ca⁺⁺-treated fruits until 12 months.The soluble protein profile of Ca⁺⁺-treated fruits showed anaccumulation of a 30 kDa polypeptide while the control fruitsaccumulated a 60 kDa polypeptide. Autoradiographs of phosphorylatedpolypeptides revealed a 60 kDa membrane polypeptide becomingphosphorylated in the Ca⁺⁺-treated and not in the control fruitprotein fractions. Transmission electron micrographs of thecell showed Ca⁺⁺ to be effective in maintaining the cell wallstructure, particularly the middle lamella. Furthermore, increasein fruit Ca⁺⁺ reduced CO₂ and C₂H₂ evolution and altered chlorophyllcontent, ascorbic acid level and hydraulic permeability. ¹Scientific Paper No: 7930, College of Agriculture and HomeEconomics Research Center, Washington State University, Pullman,Washington, Project 0321. ²Supported by grants from the National Science Foundation CB-8502215and Washington State Tree Fruit Research Commission to BWP. (Received September 3, 1987; Accepted March 3, 1988)     

Subcellular localization, of glucosyl transferases involved in lectin glucosylation in Pisum sativum seedlings

Cellular membranes from 4 to 5-days old etiolated pea seedlingswere isolated by isopyenic centrifugation. Marker enzymes wereused to measure the purity of the subcellular fractions. Theformation of dolichy!-P-glucose and of glucosylated lectin wastested in all the fractions. Both activities were associatedwith the endoplasmic reticulum fractions. When the membraneswere prepared in the presence of EDTA, a shift in both activitiesto a lower density in the gradient was observed. These results are in agreement with the current assumption thatglycosylation of proteins via lipid-linked sugars is a cotranslationalprocess. ¹ Present address: Centra de Investigaciones Agron?micas, INTA,C.C. 25, Castelar, Argentina. ² Present address: Department of Biochemistry, University ofMiami, P. O. Box 016129, Miami, FL 33101, U.S.A. ³ To whom correspondence should be addressed. Present address:Instituto de Investigaciones Biologicas, Universidad Nac. deMar del Plata, C. C. 1348, 7600 Mar del Plata, Argentina. (Received April 24, 1979; )     

ORNITHINE CYCLE ENZYMES IN THE BLUE-GREEN ALGA NOSTOC MUSCORUM

Cell-free extracts of a bacteria-free culture of Nostoc muscorumwere used to demonstrate the occurrence of part of the KREBS-HENSELEITornithine cycle in blue-green algae. Evidence is presented forthe conversion of ammonia and bicarbonate to carbamyl phosphateand the coupling of carbamyl phosphate to ornithtne to yieldcitrulline. Attempts to demonstrate the conversion of citrullineto arginine were not successful. ¹Present address: Scripts Institute of Oceanography, Universityof California, La Jolla, California, U.S.A. ²Present address: Department of Biochemistry and Nutrition,The University of Texas Medical Branch, Galveston, Texas, U.S.A.     

Characterization of Senescence in Lemna gibba G3: A Determinate Growth System

Frond senescence in Lemna gibba G3 was characterized, and itscontrol by light, ABA and kinetin investigated. The plant exhibitsa determinate growth pattern with a frond producing a set numberof daughter fronds before undergoing senescence and death regardlessof whether or not it flowers. When a frond was cut in half,the distal half (half frond) which lacks any meristem underwentrapid senescence as compared with intact fronds. In both intactand half fronds, the onset of senescence was accelerated byABA and retarded by kinetin. Continuous white light acceleratedsenescence in both intact and half fronds over the dark controls.Under different photoperiodic light regime, the pace of daughterfrond production is accelerated in proportion to the lengthof light period. In half fronds, however, very short photoperiodiclight treatments (e.g. 1L: 23D or 3L: 21D) rather delayed senescenceover the dark controls. Two separate light control systems operatingin opposite directions in Lemana senescence appear to exist. ¹Present address: Department of Biology, Yonsei University,Seoul 120-749, Korea ²Present address: U.S. Department of Agriculture, Aero SpaceBuilding, Rm. 323, 901 D Street, S.W., Washington, D.C. 20251-2200, U.S.A. (Received July 13, 1989; Accepted May 8, 1990)     

Dark Reduction of P700+ in Photosystem I Particles by Illuminated Chlorophyllide

Illumination of chlorophyllide dissolved in a wet organic solventgenerates an unknown species of chlorophyllide which is capableof reducing P700⁺ in darkness ata considerably high rate inthe absence of ascorbate and redox mediators. The formationof this derivative species is accompanied by bleaching of boththe red and blue absorption bands of chlorophyllide concomitantwith the appearance of a new peak at around 500 nm. The generationof reducing capability is stimulated by the presence of basesbut does not require reducing agents. Some of the propertiesof this reaction are discussed in comparison with the Krasnovskiireaction. ¹Present address: Department of Environmental Biology, ResearchSchool of Biological Science, The Australian National University,Canberra City, ACT 2601, Australia. ³Present address: Department of Biology, Indiana University,Bloomington, IN 47405, U.S.A. (Received June 6, 1985; Accepted November 20, 1985)