京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第13360号 / 論農博第2891号 / 新制||農||1080(附属図書館) / 学位論文||R2||N5299(農学部図書室) / (主査)教授 中﨑 鉄也, 教授 白岩 立彦, 教授 土井 元章 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

No description available.

Les plastes primaires proviennent d'une cyanobactérie qui a établi une relationendosymbiotique avec un hôte eucaryote. Cet événement a donné naissance au super-groupeArchaeplastida qui inclut les Viridiplantae (algues vertes et plantes terrestres), les Rhodophyta (alguesrouges) et les Glaucophyta. Suite à l'endosymbiose primaire, les algues rouges et vertes ont étendu lacapacité de photosynthèse à d'autres lignées eucaryotes via des endosymbioses secondaires. Bien quedes progrès considérables aient été réalisés dans la compréhension de l'évolution des eucaryotesphotosynthétiques, d'importantes questions sont restées ouvertes, telles que l’identité de la lignéecyanobactérienne la plus proche des plastes primaires ainsi que le nombre et l'identité des partenairesdans les endosymbioses secondaires.Ma thèse a consisté à étudier l'origine et l'évolution précoce des eucaryotes photosynthétiques enutilisant des approches phylogénétiques et phylogénomiques. Je montre par mon travail que les plastesprimaires ont évolué à partir d'un symbiote phylogénétiquement proche de Gloeomargarita lithophora,une cyanobactérie représentant un clade s’étant diversifié précocement et qui a été détectéeuniquement dans les milieux terrestres. Ce résultat fournit des pistes nouvelles sur le contexteécologique dans lequel l'endosymbiose primaire a probablement eu lieu. En ce qui concerne l'évolutiondes lignées eucaryotes avec des plastes secondaires, je montre que les génomes nucléaires deschlorarachniophytes et des euglénophytes, deux lignées photosynthétiques avec des plastes dérivésd'algues vertes, encodent un grand nombre de gènes acquis par transferts depuis des algues rouges.Enfin, je mets en évidence que SELMA, la machinerie de translocation des protéines à travers laseconde membrane externe des plastes rouges secondaires à quatre membranes, a une histoireétonnamment compliquée aux implications évolutives importantes : les cryptophytes ont recruté unensemble de composants de SELMA différent de ceux des haptophytes, straménopiles et alvéolés.Ainsi, ma thèse a permis d’identifier pour la première fois la lignée cyanobactérienne la plus proche desplastes primaires et apporte de nouvelles pistes pour éclaircir les événements complexes qui ontjalonné l’évolution des eucaryotes photosynthétiques secondaires. / Primary plastids derive from a cyanobacterium that entered into an endosymbioticrelationship with a eukaryotic host. This event gave rise to the supergroup Archaeplastida whichcomprises Viridiplantae (green algae and land plants), Rhodophyta (red algae) and Glaucophyta. Afterprimary endosymbiosis, red and green algae spread the ability to photosynthesize to other eukaryoticlineages via secondary endosymbioses. Although considerable progress has been made in theunderstanding of the evolution of photosynthetic eukaryotes, important questions remained debatedsuch as the present-day closest cyanobacterial lineage to primary plastids as well as the number andidentity of partners in secondary endosymbioses.The main objectives of my PhD were to study the origin and evolution of plastid-bearing eukaryotesusing phylogenetic and phylogenomic approaches to shed some light on how primary and secondaryendosymbioses occurred. In this work, I show that primary plastids evolved from a close relative ofGloeomargarita lithophora, a recently sequenced early-branching cyanobacterium that has been onlydetected in terrestrial environments. This result provide interesting hints on the ecological setting whereprimary endosymbiosis likely took place. Regarding the evolution of eukaryotic lineages with secondaryplastids, I show that the nuclear genomes of chlorarachniophytes and euglenids, two photosyntheticlineages with green alga-derived plastids, encode for a large number of genes acquired by transfersfrom red algae. Finally, I highlight that SELMA, the translocation machinery putatively used to importproteins across the second outermost membrane of secondary red plastids with four membranes, has asurprisingly complex history with strong evolutionary implications: cryptophytes have recruited a set ofSELMA components different from those present in haptophytes, stramenopiles and alveolates.In conclusion, during my PhD I identified for the first time the closest living cyanobacterium to primaryplastids and provided new insights on the complex evolution that have undergone secondary plastid-bearing eukaryotes

The ability of freshly prepared spinach or poke weed (Phytolacca americana) chloroplasts to photoreduce triphosphopyridine nucleotide (TPN) under anaerobic conditions decreased in the presence of ascorbate and 2,6-dichlorophenolindophenol (DPIP). On .aging the chloroplasts, however, addition of DPIP and ascorbate was required for a high rate of TPN photoreduction. Qualitatively similar results were obtained for photoreduction of DPN, indigo carmine, riboflavin-5'-phosphate and vitamin K3 . Addition of 3-(3,4-dichlorophenyl)-1,l-dimethylurea (DCMU) at 10-5 M to freshly prepared chloroplasts inhibited the photoreduction of TPN by more than 98 %, and activity was restored to 94 %o f the original value by addition of ascorbate and.DPIF. Hydroxylamine at 10-3 Mand ammonium ion at 0.17 M produced similar effects. Qualitatively similar results were obtained with .these three inhibitors for photoreduction of DPN, indigo , carmine, .riboflavin-5 1 -phosphate, vitamin K3, methyl red and tetrazolium blue. Cesium ion and orthophenanthroline produced inhibitory effects similar to those of DCMU, hydroxylamine and ammonium ion which responded analogously to the DPIP-ascorbate couple. The data substantiate the previously proposed idea that ascorbate is photooxidized in the absence of oxygen by the photochemical oxidizing equivalents produced by illuminated chloroplasts, with the dye DPIP· acting as intermediate electron carrier. With intact .chloroplasts 2 the oxidizing equivalents are utilized preferentially for oxidation of water to produce oxygen. Only after the oxygen-evolution .system becomes .inoperativec1;1.n the ascorbate-DPIP couple compete successfully for the oxidizing equivalents. ExPosure of chloroplasts . to . light for 20 minutes _prior to ,adding .a Hill oxidant resulted in a reduced photoreducin,g capacity in the Hill reaction with TPN, indigo .carmine .and tetrazoli:um blue. However, such a treatment .actually increased the photoreducing _ability of the chloroplasts in the presence of DPIP and .ascorbate. Chloroplasts were inactivated toward the Hill reaction .by a pH of 7.7 at 30°. This inactivation was .readily overcome by addition of ascorbate and DPIP, indicating that .the principal effect of this treatment was to inactivate the oxygen-evolution system. Since indigo carmine photoreduction is stabili.z-ed· much more by the presence of sucrose in the reaction mixture than the photoreduction of DPIP it is indicated that there are components in the electron transport system leading from the site of DPIP photoreduction to that of indigo carmine photoreduction which .are sensitiye to distilled water dilution. The photoreduction of TPN, PPN .and indigo carmine was stimulated by addition of cysteine, whereas reduced glutathione was without effect. Cysteine was unable to overcome the inhibitions of DCMU, hydroxylamine and ammonium ion and no stimulation was observed when cysteine was .added to the inhibited systems containing DPIP and ascorbate even though cysteine was capable of stimulating the uninhibited reaction containing the DI"IP-ascorbate couple. It was there3 fore concluded that cysteine acts by stabilizing or reacting with the oxygen-evolving system. Chloride-deficient chloroplasts .were stimulated by added chloride and cyanide in Hill reaction activities. Reaction .mixtures containing sufficient chloride to provide maximal stimulation were further stimulated by added cyanide, versene and Tris.

Överlag är det vanligt att elever i de yngre åldrarna har svårigheter att lära sig och förståde abstrakta processerna i fröets groningsprocess och fotosyntesen. Syftet med mittexamensarbete är att undersöka hur praktiska laborationer kan hjälpa elever attkonkretisera dessa abstrakta processer. Min frågeställning som jag har utgått ifrån är”Hur förändrar ett laborativt arbetssätt elevernas kunskaper och förståelse förfrögroningsprocessen och fotosyntesen?” För att kunna besvara denna har jag gjort enkartläggning av elevernas kunskaper om fröets groningsprocess och fotosyntes såvälföre som efter en laboration för att bilda mig en uppfattning om elevernas kunskapsnivåoch hur den förändrats genom de experiment som jag låtit eleverna genomföra. Minteoretiska grund för detta examensarbete har tagit avstamp i variationsteorin och jag harpraktiserat learning study i min egen undervisning. Den grupp jag studerat är mina egnaelever som jag har undervisat under en tidsperiod, då jag såg examensarbetet som ettypperligt tillfälle att få möjlighet att utveckla min egen undervisning utifrån forskningsamt att praktiskt pröva några vetenskapliga teorier. Möjligheten att studera mina elevernärmare för att kunna undersöka om undervisningsstrategin som används i klassrummetär optimal för eleverna, har gett mig teoretiska perspektiv och praktiska redskap för attdokumentera, analysera och utvärdera min undervisning med ett vetenskapligtförhållningssätt. Denna utvärdering kommer att ligga till grund för att jag ska kunnaompröva och utveckla mina undervisningsmetoder vidare i framtiden. I studien som genomförts har jag har utgått ifrån en konstruktivistisk syn på kunskapoch använt Piagets stadieteori samt Vygotskijs sociokulturella perspektiv somhjälpmedel vid kartläggningen av elevernas kunskaper och vid analys av resultaten. Föratt kunna synliggöra elevernas utveckling genomförde jag två enkäter före och efter atteleverna hade genomfört en laboration. Enkäterna handlade om vad eleverna förknipparmed fotosyntes, beskrivning av fotosyntes och om fröets groningsprocess. Underexperimentets arbetsgång var jag med i klassen och observerade eleverna samt derasplanteringar.Flertalet elever gav i enkäterna likartade svar, medan ett fåtal avvek markantantingen genom en mycket god processförståelse eller en bristfällig. Dessa avvikelservalde jag att studera närmare genom att låta eleverna delta i ett kompletterande samtalkring vad de lärt sig, då jag uppfattar att det är avvikelserna som ger ledtrådar till att identifiera styrkorna och svagheterna i undervisningen; Varför lyckades jag nå framsärskilt väl till en del elever och vad brast i min undervisning gentemot de elever somjag inte nått fram till?Resultatet som jag har kommit fram till i min studie är att det ger ett visst stöd förkunskapsutvecklingen hos flertalet elever att använda praktiska laborationer för attkonkretisera fröets groningsprocess och fotosyntesen. Dessvärre har inte praktisktlaborationsarbete varit en tillräcklig eller optimal undervisningsstrategi för en del aveleverna då dessa inte uppvisade någon kunskapsutveckling efter laborationen.

Bibliography: pages 162-177. / The seasonal and diurnal patterns of photosynthetic gas exchange and the water relations of seven species of the mediterranean-climate region of South Africa (fynbos) were investigated. The following species, representing the major fynbos elements, were chosen for intensive investigation: Erica plukenetii and Erica hispidula (ericoid element), Thamnochortus lucens and Askidiosperma paniculatum (restioid element), Protea laurifolia and Leucadendron salignum (proteoid element). Metrosideros angustifolia, a shrub of riparian habitats, was also studied.

Eastern hemlock (Tsuga canadensis [L.] Carr.) is a foundation species that occupies a unique niche in forest ecosystems and which often forms pure stands throughout the eastern United States. Throughout the last half of a century, widespread mortality of T. canadensis had been occurring with the introduction of the invasive pest, hemlock woolly adelgid (Adelges tsugae Annand) (HWA). HWA now threatens to destroy millions of hectares of hemlock dominated forests and to disrupt its associated ecosystems. In order to determine how HWA impacts hemlock physiology, three sites with various degrees of infestation were chosen and half of the trees at each site were treated with imidacloprid (Merit® 2 F, Bayer, Kansas City, MO) while the rest were left untreated. Needle gas exchange was assessed monthly using a LI-COR 6400 portable open path gas exchange system (LI-COR Inc, Lincoln NE). Chlorophyll fluorescence and bud break were also characterized for all trees at two of the three sites. After one complete growing season, we found a slight increase in photosynthetic rates (4.98 %), increased bud break at Fishburn (562 %) and Mountain Lake (25.6 %) sites, and no change in chlorophyll fluorescence for imidacloprid treated trees. These results suggest that HWA is causing tree mortality largely through a reduction of leaf area and not a reduction in leaf level photosynthetic capacity. By quantifying the physiological response of T. canadensis to HWA, better insights can be made into understanding tree decline as it relates to HWA. / Master of Science

The dinoflagellate genus Symbiodinium is a popular research topic in the coral reef molecular biology field. Primarily because these organisms serve as the coral holobiont’s primary source of energy, carrying out photosynthesis, and providing hydrocarbons to the coral host. Previous studies have shown the difficulty of isolating Symbiodinium as well as the inherent problems in trying to quantify the diversity of this genus and to qualify the distinct reactions of different Symbiodinium sp. to changing environmental conditions. The main goals of this study are: (1) to detail the relationship between the genetic classification of the organism and its physiology in regard to photosynthesis with a number of established Symbiodinium cultures; and (2) to isolate Symbiodinium from coral of the central Red Sea. To evaluate the photosynthetic physiology of Symbiodinium, a microsensor was used to measure oxygen concentrations along with a phytoplankton analyzer system that used pulse-amplitude-modulation (Phyto-PAM) to measure fluorescence. In order to identify the particular clade that the isolates belonged to, denaturing gradient gel electrophoresis (PCR-DGGE) was used to identify Symbiodinium based on their internal transcribed spacer 2 (ITS2) region. These techniques helped us to achieve our goals in the following ways: Symbiodinium sp. from a culture collection were classified to the subclade level; species-specific and clade-specific photosynthetic profiles were generated; and a Symbiodinium sp. was isolated from the central Red Sea. This study provided preliminary correlation between the photosynthetic difference and Symbiodinium genetic classification; showed the probable existence of a self-protection system inside the Symbiodinium cells by comparing the difference between the initial oxygen production at the beginning of each light step and the oxygen production after light adaptation; and confirmed the possibility of the isolation of Symbiodinium.

The work presented here investigated two methods of improving productivity in microalgal photobioreactors: applying temperature cycles intended to maximize photosynthesis and minimize respiration, and development of a mathematical model that predicts improvements in photon utilization using temporal light dilution (flashing). The experiments conducted on diurnal temperature cycles with Dunaliella tertiolecta in 30-L outdoor photobioreactors showed that a properly chosen temperature cycle can improve mass and energy productivity by 18% over an identical photobioreactor with a constant temperature. However, excessively large temperature cycle amplitudes reduced productivity. A 4-7% increase in energy content was observed in microalgae exposed to temperature cycles. The physiological reason for this could not be established. A relationship similar to the Bush Equation was obtained that related photon utilization efficiency to flashing frequency, load factor, Photosystem II (PSII) concentration and reaction frequency, and chlorophyll content. The model was validated by the experimental data of a number of researchers.

Germination, respiration, and photosynthesis in seeds of dwarf mistletoe (Arcenthobium) were studied. The effects of 1 hour soakings of seeds in aqueous solutions of 1, 2, or 3% H2O2 or 1, 2, 3, 4, or 5% Chlorox on germination of seeds were tested. Germination rates for seeds from three consecutive years (1975-1977) were obtained. Germination rates varied widely. This variance transcended subtle changes in treatment. Pretreatment of seeds with Chlorox resulted in significantly lower germination rates than those of the control. Chlorophyll concentrations were determined for seeds and aerial shoot tissue of four species. Seeds of A. douglasii had the highest chlorophyll concentration (0.39 mg/g fresh weight) while seeds of A. tsugense had the lowest concentration (0.25 mg/g fresh weight). Net O2 uptake by seeds of A. campylopodum in dark and in light was measured by manometric and polarographic methods. The mean values were 353 μl O2 g-1 h-1 in the dark and 201 O2 g-1 h-1 in the light. The difference between these rates is apparently due to O2 evolution during photosynthesis. In light the seeds can fix 43% of the CO2 produced by respiration. Experiments in which seeds were exposed to 14CO2 in light confirmed that the seeds are able to fix CO2. Extraction of seeds with ethanol showed that 97-99% of the incorporated 14C was ethanol soluble. Ten to sixteen percent of the ethanol fraction was chloroform soluble while the rest was H2o soluble. Ion exchange separation of the H2o phase showed that 11-25% of 14C activity was cationic, 15-29% anionic, and 53-67% neutral.