Lipid-Linked Desaturation of Palmitic Acid in Monogalactosyl Diacylglycerol in the Blue-Green Alga (Cyanobacterium) Anabaena variabilis Studied in Vivo

The mechanism of desaturation of palmitic acid in monogalactosyldiacylglycerol in Anabaena variabilis was studied by labelingin vivo with ¹³C and mass spectrometry. When the cells werefed with [¹³C]Na₂CO₃ for 2.5 h, 19% of the palmitic, but virtuallynone of the palmitoleic, acid at the C-2 position of the lipidwas enriched with ¹³C. During subsequent incubation for 7.5h, the [¹³C]palmitic acid was desaturated to [¹³C]palmitoleicacid. Mass spectrometric analysis of the 2-acylglycerol moietyof the lipid indicated that [¹³C]palmitoyl-[¹³C]glycerol and[¹²C]palmitoyl-[¹²C]glycerol were converted to [¹³C]palmitoleoyl-[¹³C]glyceroland [¹²C]palmitoleoyl-[¹²C]glycerol, respectively. These resultssuggest that the palmitic acid was converted to palmitoleicacid in vivo by lipid-linked desaturation but not via a pathwayconsisting of deacylation, desaturation and reacylation. ⁴Present address: Department of Botany, Faculty of Science,University of Tokyo, Hongo, Tokyo 113, Japan ⁵Present address: Department of Physiological Chemistry andNutrition, Faculty of Medicine, University of Tokyo, Hongo,Tokyo 113, Japan (Received December 7, 1985; Accepted April 16, 1986)     

Phytochrome Control of Its Own Synthesis in Pisum sativum

An analysis of phytochrome synthesis in Pisum seedlings by measuringthe activity of polysomal polyadenylated RNA (poly-A⁺-RNA) codingfor phytochrome apoprotein showed phytochrome control of itsown synthesis; brief red-light irradiation of pea seedlingsinhibited the activity of the RNA, and the red-light effectwas red/far-red reversible. ⁴ Permanent address: Biology Department, Faculty of Science,University of Tokyo, Hongo, Tokyo 113, Japan. (Received August 13, 1984; Accepted September 17, 1984)     

CHOICE OF BIOASSAY IN ASSESSING ACTIVITY OF ENDOGENOUS GROWTH SUBSTANCES

A chloroform extract of peelings and buds of ‘Red Pontiac’potato tubers yielded chromatographic eluates that exhibitedqualitatively and quantitatively different stimulating and inhibitingresponses on four bioassays. The essentiality of selecting asatisfactory array of bioassays, coupled with a thorough extractionprocedure, is emphasized. ¹This research was supported by United States Public HealthService Grant EF-61 ²Present address: Department of Botany, Hebrew University, Jerusalem,Israel ³Present address: Department of Agronomy, University of Tokyo,Bunkyo-ku, Tokyo     

Induction of nitrate and nitrite reductases in Anabaena cylindrica

Induction of nitrate and nitrite reductases in Anabaena cylindrica(FOGG strain) was investigated. At various stages of algal growthin the presence of nitrate or nitrite, the levels of these enzymeswere determined using cell-free preparations. Nitrate and nitritereductases were induced by the respective substrates. Nitratedid not act either as an inducer or as a repressor of nitritereductase. ¹This work was supported by grant No. 8814 from the Ministryof Education ²Department of Biology, Faculty of Science, Tokyo MetropolitanUniversitySetagaya-ku, Tokyo, Japan (Received June 18, 1970; )     

Translocation of organic compounds in sunflower III. Effect of oligomycin, ouabain and phlorizin on translocation of sugars

The apical portions of intact sunflower leaves were infiltratedwith ¹⁴C-glucose, ¹⁴C-fructose or 3-O-methyl-¹⁴C-glucose andthe basal portions were treated with inhibitors. The effects of oligomycin, ouabain and phlorizin on translocationwere studied. Inhibition of translocation from the basal portionof the leaf to the stem was determined by experiments usingoligomycin. In other experiments, each leaf was divided intothree parts. The apical portion was fed with ¹⁴C-glucose andthe basal part treated with oligomycin. The effects of oligomycinon the distribution of ¹⁴C-glucose, ¹⁴C-sucrose, ¹⁴C-fructoseand ¹⁴C-sugar phosphate along the three parts of the leaf wereinvestigated. Inhibition of sucrose synthesis in the leavestreated with oligomycin was observed. Oligomycin inhibited ¹⁴Ctranslocation from the leaf. ¹Present address: Department of Biology, Faculty of Science,Science University of Tokyo, Kagurazaka, Shinjuku-ku, Tokyo,Japan. (Received August 17, 1978; )     

Changes in glutamate dehydrogenase activity in cut-injured sweet potato root tissue

Changes in glutamate dehydrogenase activity in sweet potatoroot tissue in response to slicing were investigated with mitochondrialand supernatant fractions. Results indicated that activity inmitochondrial fraction had decreased, whereas activity in supernatantfraction had increased, 12 hr after slicing. The increase inactivity in the supernatant fraction may be related to the regenerationof phenylalanine, a precursor of polyphenols. ¹This paper constitutes Part 104 of the Phytopathological Chemistryof Sweet Potato with Black Rot and Injury. ²Present address: Laboratory of Biochemistry, Faculty of Agriculture,University of Tokyo, Bunkyoku, Tokyo 113, Japan. (Received August 15, 1972; )     

EUGLENA GRACILIS IN SYNCHRONOUS DIVISION I. DRY MASS AND VOLUME CHARACTERISTICS

Volume distributions and dry mass have been measured in synchronouspopulations of Euglena gracilis, grown in a salt medium at aconstant temperature. In keeping with the approximate doublingof cell number observed in each division burst, the averagedry mass and volume are doubled in each inter-division period. ¹ Present address: Department of Biology, Tokyo MetropolitanUniversity, Setagaya.ku, Tokyo. (Received February 17, 1961; )     

Inhibition of sweet potato glucose 6-phosphate dehydrogenase by NADPH2 and ATP

NADPH₂ and ATP competitively inhibit sweet potato glucose 6-phosphatedehydrogenase with NADP and glucose 6-phosphate (G6P), respectively.At pH 8.0, a Lineweaver-Burk plot of the reciprocal rate againstreciprocal G6P concentration was concave downwards in the presenceand absence of ATP, whereas a double reciprocal plot followedthe Michaelis-Menten relationship at pH 7.0, irrespective ofthe presence of ATP. Many of the other metabolic intermediatestested had no effects on the enzyme reaction. ¹ This paper constitutes Part 96 of the Phytopathological Chemistryof Sweet Potato with Black Rot and Injury. ² Present address: Institute of Applied Microbiology, Universityof Tokyo Bunkyo-ku, Tokyo 113. (Received October 20, 1971; )     

Lipid Biosynthesis in the Blue-Green Alga (Cyanobacterium), Anabaena variabilis III. UDPglucose:Diacylglycerol Glucosyltransferase Activity in vitro

The synthesis of glyceroglycolipids was studied in membraneand soluble fractions of Anabaena variabilis. The membrane fractionexhibited a high activity of UDPglucose: diacylglycerol glucosyltransferase,but practically no activity of UDPgalactose: diacylglycerolgalactosyltransferase. The glucosyltransferase activity wasmaximal at about pH 7.0 and dependent on Mg²⁺ The Michaelisconstant (K_m) for UDPglucose was 45?10^–6 M. The solublefraction catalyzed the incorporation of galactose from UDP galactoseinto digalactosyl diacylglycerol. These in vitro results werecompatible with the biosynthetic pathway of glyceroglycolipidsin this alga that we previously elucidated on the basis of tracerexperiments in vivo. ¹ Present address: Department of Biology, Faculty of Science,University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan. (Received June 1, 1982; Accepted July 1, 1982)     

COMPARATIVE STUDIES ON GROWTH, RESPIRATION, PHOTOSYNTHESIS AND PIGMENT CONTENT IN RHODOPSEUDOMONAS PALUSTRIS

1. Comparative studies were performed on growth, photosyntheticand respiratory activities, and pigment content in Rhodopseudomonaspalustris.
2. The growth of the organism, as influenced by variousculturalconditions such as light, aerobiosis, anaerobiosisand nutritionalfactors was investigated.
3. The respiratoryactivity of the bacterium was found to be higherin dark-growncells than in cells grown in the light. The photosyntheticactivitydid not significantly depend on the growth conditionsof theculture. Cells of younger cultures were found to be moreactivethan those of older cultures, with respect both to respirationand photosynthesis.
4. The pigment content was found to be higherin the light-growncells than in the dark-grown ones. The ratiophotosyntheticactivity/bacteriochlorophyll was significantlyhigher in thelatter than in the former.
5. Light, as well asvarious nutritional factors, was found toexert a marked accelerationon pigment formation, although ithas not yet been possibleto culture cells completely lackingin photosynthetic pigmentsand accordingly in photosyntheticactivity.

¹ Present address: Division of Dermatology and Urology, TokyoMetropolitan Hiroo Hospital, Tokyo. ² Present address: Department of Biology, Saitama University,Urawa. ³ Present address: Department of Biochemistry, School of Medicine,Yokohama University, Yokohama. ⁴ Present address: Department of Biophysics and Biochemistry,Faculty of Science, University of Tokyo, Tokyo. (Received July 23, 1961; )     

Electrical Characteristics of the Tonoplast of Cham corallincr. A Study Using Permeabilised Cells

Use of permeabilised cells of Chara corallina provides a uniqueopportunity to study the electrical characteristics of the tonoplastwhilst being able to control ionic conditions on the outsideof the membrane. Current-voltage (I/V) analysis over wide voltagespans, and admittance measurements at 5 Hz showed that manypermeabilised cells had a similar conductance and capacitanceto the tonoplast of intact cells. Cells developed two regionsof negative-slope conductance upon addition of external Cl^–,which suggests the existence of potential-dependent Cl^–channels in the Chara tonoplast. With Cl^– concentrationssimilar to those expected in vivo, the resting potential wasmore sensitive to changes in external K⁺ than Cl^–; however,a decrease in external K⁺ did not significantly alter the shapeof the I/V relation. ¹Present address: Biopysics Laboratory, School of BiologicalSciences, A12, University of Sydney, Sydney, N.S.W., 2006, Australia ²Permanent address: Department of botany, Faculty of Science,University of Tokyo, Hongo, Tokyo 113, Japan (Received May 6, 1987; Accepted September 21, 1987)     

Biosynthetic mechanism of glycolate in Chromatium II. Enzymic mechanism of glycolate formation by a transketolase system

The mechanism for the biosynthesis of glycolate in the photosyntheticbacterium Chromatium was studied. The enzymic nature of glycolatesynthesis from fructose-6-P and ribose-5-P by a cell-free bacterialextract, strictly dependent on the presence of ferricyanidein the assay mixture, was established. Removal of thiamine pyrophosphatefrom the assay mixture did not alter the magnitude of glycolateformation. By examining the reaction products from ¹⁴C-fructose-6-Pand ¹⁴C-ribose-5-P, the operating mechanism involved in glycolateformation was judged to be the oxidative breakdown of the glycolaldehyde-transketolaseaddition product by ferricyanide. The role of transketolasein the oxidative formation of glycolate in the photosynthesizingcells of Chromatium is discussed. ¹ This is paper XXXI in the series "Structure and Function ofChloroplast Proteins". Paper XXX is reference (5). The researchwas supported in part by grants from the Ministry of Educationof Japan (986009), the Toray Science Foundation (Tokyo), andthe Naito Science Foundation(Tokyo). (Received May 22, 1975; )     

Studies on chlorophyll formation in Chlorella protothecoides III. Effects of chloramphenicol, cycloheximide, and ethionine on chlorophyll formation

Effects of chloramphenicol, cycloheximide, puromycin and ethionineon the light-independent and subsequent light-dependent processesof chlorophyll formation in "glucose-bleached" cells of Chlorellaprotothecoides were studied. These substances, except puromycin,strongly suppressed different phases of chlorophyll formation.Ethionine most strongly suppressed the light-independent phaseand chloramphenicol an early, relatively short process in thelight-dependent phase of chlorophyll formation. Cycloheximideseverely suppressed all phases of chlorophyll formation. Possibleimplications of these results for the biosynthesis of chlorophyllin algal cells are discussed. ¹ Present address: National Food Research Institute, Ministryof Agriculture and Forestry, Koto-ku, Tokyo 135, Japan. ² Laboratory of Entomology, Faculty of Agriculture, TamagawaUniversity, Machida-shi, Tokyo, Japan (Received October 5, 1972; )     

Morphological and physiological characterization of IAA-less-sensitive and IAA-sensitive phases in rooting of Azukia cuttings

In disbudded epicotyl cuttings taken from light grown 5-dayold Azukia angularis Phaseolus angularis) seedlings, all adventitiousrootlets appeared on the second day of incubation. No root primordiawere observed within the first 24 hr and no increase in thenumber of roots occurred after 48 hr. Puromycin (5.5?10^–5M), p-fluorophenylalanine (1?10^–3M),2-thiouracil (2.3?10^–4M) and 2,6-diaminopurine (2?10^–5M)inhibited rooting when applied to cuttings on the second day,but showed no inhibition when applied on the first day. Unlike these inhibitors, pyrithiamine (7.2?10^–5M) inhibitedrooting when it was applied to cuttings on the first day. A rooting promoting effect was observed with actinomycin D (2.4?10^–6M),2,4-dinitrophenol (3?10^–5M) and p-fluorophenylalanine(1?10^–4M) applied to the cuttings on the first day, whereasindoleacetic acid (1.7?10^–4M) showed its promoting effectmost effectively on the second day. ¹Contribution No. 17 from the Botanical Gardens, Faculty ofScience, University of Tokyo, Tokyo, Japan. (Received June 4, 1969; )     

Operation of the reductive pentose phosphate cycle daring the induction period of photosynthesis in Chlorella

When Chlorella oulgaris ll h cells grown in air containing 4%CO₂ (high-CO₂ cells) were given low concentrations of¹⁴CO₂ (<150ppm), the initial rate of photosynthetic ¹⁴CO₂ fixation wasvery low and linear ¹⁴CO₂ fixation was observed after an inductionperiod which lasted for ca. 45 min. No such induction period was observed when high-CO₂ cells weregiven high concentrations of ¹⁴CO₂ (10,000 ppm) or when IOW-CO₂cells were given either low or high concentrations of ¹⁴CO₂,supporting the observations by Briggs and Whittingham (l). However,irrespective of CO₂ concentrations during growth and of ¹⁴CO₂concentrations during the experiments, most of the ¹⁴C was incorporatedinto phosphate esters during the initial periods of photosynthetic¹⁴CO₂ fixation. These results are in sharp contrast to the reportby Graham and Whittingham (4). ¹ Requests for reprints should be addressed to S. Miyachi, RadioisotopeCentre, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan. (Received June 30, 1979; )     

Effect of NADP$ and glucose 6-phosphate on the sedimentation behavior of glucose 6-phosphate dehydrogenase from sweet potato

Sedimentation behavior of sweet potato glucose 6-phosphate dehydrogenasewas studied using the sucrose density gradient centrifugation.The relative s value to s_20, value of alcohol dehydrogenasewas determined to be about 6 in the absence of both NADP^$ andglucose 6-phosphate. In the presence of NADP^$, the enzyme wassedimented with a relative s value of about 9. The additionof glucose 6-phosphate did not affect the sedimentation behavior.When glucose 6-phosphate was added to the gradient medium containingNDAP^$, the enzyme was sedimented with a relative s value ofabout 6 or 7, depending on the concentration of glucose 6-phosphate. ¹ Present address: Institute of Applied Microbiology, Universityof Tokyo, Bunkyo-ku. Tokyo, Japan. (Received February 13, 1971; )     

Glucose 6-phosphate dehydrogenase from sweet potato: Effect of various ions and their ionic strength on enzyme activity

Activity of glucose 6-phosphate dehydrogenase (D-glucose 6-phosphate:NADP oxidoreductase, EC 1.1.1.49 [EC] ) preparation from sweet potatoroot tissue was markedly altered in the presence of variousions. Cations or anions were effective in the following order:Na^$, K^$>Tris^$>NH₄^$>Mg^2$>Ca^2$, or Cl^–>NO₃^–,HPO₄^2–>SO₄^2–>HCO₃^–. Activity was inhibitedat high concentrations of Ca^2$, and HCO₃^–,. In an investigationon the dependence of the activity on pH, two activity peakswere clearly observed at low ionic strength. Ionic strength altered both the Km and Vmax for glucose 6-phosphate(G6P). A Lineweaver-Burk plot for the enzyme, with respect toG6P, showed a bimodal nature at low ionic strength; suggestingnegative cooperativity. Deviation from linearity of the plotwas less with an increase in the ionic strength. ¹ Present address: Institute of Applied Microbiology, Universityof Tokyo, Bunkyo-ku, Tokyo 113. (Received September 18, 1971; )     

Fatty acid synthesis by spinach chloroplasts I. Property of fatty acid synthesis from acetate

Intact chloroplasts (about 70% Class I chloroplasts) isolatedfrom spinach leaves incorporated 150 nmoles of [1-¹⁴C] acetateinto fatty acids per mg chlorophyll in 1 hr at pH 8.3, 25°Cand 25,000 lux. On electron and phase-contrast microscopiescombined with hypotonic treatment of chloroplasts, this syntheticactivity was shown to be proportional to the percentage of ClassI chloroplasts in the preparation. Light was necessary for thesynthesis, the activity in the complete reaction mixture inthe dark being only 2% of that in the light. The synthetic activityincreased with increasing intensities of light to reach saturationat 6,000 lux. CoA and ATP were most effective as cofactors,HCO₃^–, HPO₄^2–, Mg^2$ and Mn^2$ were less effective.ATP could be replaced by ADP in the presence of Pi, suggestingpossible supply of ATP by photophosphorylation. Omission ofthe NADPH-generation system and NADH did not affect the synthesis,indicating sufficient provision of endogenous NADPH and NADHin intact chloroplasts under light. Addition of DTE did notcause recovery of the synthetic activity of intact chloroplastsin the dark. ¹ Present address: Radioisotope Centre, University of Tokyo,Yayoi, Bunkyo, Tokyo 113, Japan. (Received August 26, 1974; )     

Spectral effectiveness in chlorophyll and 5-aminolevulinic acid formation during regreening of glucose-bleached cells of Chlorella protothecoides

Regreening of glucose-bleached cells of Chlorella protothecoidesis stimulated by light. Spectral effectiveness in the processshowed maxima around 370, 440 and 480 nm, suggesting a flavoproteinas primary photoreceptor. Action spectra of ALA synthesis provedto be similar to those of chlorophyll formation, indicatingthat light stimulation of greening in this alga is regulatedat the first step of chlorophyll biosynthesis. ¹ Present address: Institute of Applied Microbiology, Universityof Tokyo, Tokyo 113, Japan. (Received March 27, 1978; )     

Comparison of carbon dioxide fixation and the fine structure in various assimilatory tissues of Amaranthus retroflexus L

The pattern for primary products of CO₂-fixation and the chloroplaststructure of Amaranthus retrqflexus L., a species which incorporatescarbon dioxide into C₄ dicarboxylic acids as the primary productof photosynthesis, were compared in various chlorophyll containingtissues,i.e., foliage leaves, stems, cotyledons and pale-greencallus induced from stem pith. Despite some morphological differencesin these assimilatory tissues, malate and aspartate were identifiedas the major compounds labelled during a 10 sec fixation of¹⁴CO₂ in all tissues. Whereas, aspartate was the major componentin C₄-dicarboxylic acids formed in foliage leaves, malate predominatedas the primary product in stems, cotyledons and the pale-greencallus. The percentage of ¹⁴C-radioactivity incorporated intoPGA and sugar-P esters increased and ¹⁴C-sucrose was detectedin the prolonged fixation of ¹⁴CO₂ in the light, not only infoliage leaves, but also in stems and cotyledons. ¹ This work was supported by a Grant for Scientific ResearchNo. 58813, from the Ministry of Education, Japan. ² Present address: Institute of Applied Microbiology, Universityof Tokyo, Tokyo, Japan. ³ Present address: Department of Biochemistry, University ofGeorgia, Athens 30601. Georgia, U. S. A. (Received July 10, 1971; )