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Sample records for chloroplasts optimizes electron

  1. Transport Across Chloroplast Membranes: Optimizing Photosynthesis for Adverse Environmental Conditions.

    Science.gov (United States)

    Pottosin, Igor; Shabala, Sergey

    2016-03-01

    Chloroplasts are central to solar light harvesting and photosynthesis. Optimal chloroplast functioning is vitally dependent on a very intensive traffic of metabolites and ions between the cytosol and stroma, and should be attuned for adverse environmental conditions. This is achieved by an orchestrated regulation of a variety of transport systems located at chloroplast membranes such as porines, solute channels, ion-specific cation and anion channels, and various primary and secondary active transport systems. In this review we describe the molecular nature and functional properties of the inner and outer envelope and thylakoid membrane channels and transporters. We then discuss how their orchestrated regulation affects thylakoid structure, electron transport and excitation energy transfer, proton-motive force partition, ion homeostasis, stromal pH regulation, and volume regulation. We link the activity of key cation and anion transport systems with stress-specific signaling processes in chloroplasts, and discuss how these signals interact with the signals generated in other organelles to optimize the cell performance, with a special emphasis on Ca(2+) and reactive oxygen species signaling. PMID:26597501

  2. Induction events and short-term regulation of electron transport in chloroplasts: an overview.

    Science.gov (United States)

    Tikhonov, Alexander N

    2015-08-01

    Regulation of photosynthetic electron transport at different levels of structural and functional organization of photosynthetic apparatus provides efficient performance of oxygenic photosynthesis in plants. This review begins with a brief overview of the chloroplast electron transport chain. Then two noninvasive biophysical methods (measurements of slow induction of chlorophyll a fluorescence and EPR signals of oxidized P700 centers) are exemplified to illustrate the possibility of monitoring induction events in chloroplasts in vivo and in situ. Induction events in chloroplasts are considered and briefly discussed in the context of short-term mechanisms of the following regulatory processes: (i) pH-dependent control of the intersystem electron transport; (ii) the light-induced activation of the Calvin-Benson cycle; (iii) optimization of electron transport due to fitting alternative pathways of electron flow and partitioning light energy between photosystems I and II; and (iv) the light-induced remodeling of photosynthetic apparatus and thylakoid membranes. PMID:25680580

  3. Artemisinin inhibits chloroplast electron transport activity: mode of action.

    Directory of Open Access Journals (Sweden)

    Adyasha Bharati

    Full Text Available Artemisinin, a secondary metabolite produced in Artemisia plant species, besides having antimalarial properties is also phytotoxic. Although, the phytotoxic activity of the compound has been long recognized, no information is available on the mechanism of action of the compound on photosynthetic activity of the plant. In this report, we have evaluated the effect of artemisinin on photoelectron transport activity of chloroplast thylakoid membrane. The inhibitory effect of the compound, under in vitro condition, was pronounced in loosely and fully coupled thylakoids; being strong in the former. The extent of inhibition was drastically reduced in the presence of uncouplers like ammonium chloride or gramicidin; a characteristic feature described for energy transfer inhibitors. The compound, on the other hand, when applied to plants (in vivo, behaved as a potent inhibitor of photosynthetic electron transport. The major site of its action was identified to be the Q(B; the secondary quinone moiety of photosystemII complex. Analysis of photoreduction kinetics of para-benzoquinone and duroquinone suggest that the inhibition leads to formation of low pool of plastoquinol, which becomes limiting for electron flow through photosystemI. Further it was ascertained that the in vivo inhibitory effect appeared as a consequence of the formation of an unidentified artemisinin-metabolite rather than by the interaction of the compound per se. The putative metabolite of artemisinin is highly reactive in instituting the inhibition of photosynthetic electron flow eventually reducing the plant growth.

  4. Optimization of ATP synthase function in mitochondria and chloroplasts via the adenylate kinase equilibrium

    OpenAIRE

    Igamberdiev, Abir U.; Kleczkowski, Leszek A.

    2015-01-01

    The bulk of ATP synthesis in plants is performed by ATP synthase, the main bioenergetics engine of cells, operating both in mitochondria and in chloroplasts. The reaction mechanism of ATP synthase has been studied in detail for over half a century; however, its optimal performance depends also on the steady delivery of ATP synthase substrates and the removal of its products. For mitochondrial ATP synthase, we analyze here the provision of stable conditions for (i) the supply of ADP and Mg2+, ...

  5. Structure of the ATP synthase from chloroplasts studied by electron microscopy and image processing

    NARCIS (Netherlands)

    Boekema, Egbert J.; Heel, Marin van; Gräber, Peter

    1988-01-01

    The structure of the hydrophilic part of the ATP synthase from chloroplasts (CF1) has been investigated by electron microscopy of negatively stained samples. The staining conditions, which are generally critical for such small objects as CF1, could be improved by mixing CF1 samples with a much large

  6. Structure of the ATP synthase from chloroplasts studied by electron microscopy. Localization of the small subunits

    NARCIS (Netherlands)

    Boekema, Egbert J.; Xiao, Jianping; McCarty, Richard E.

    1990-01-01

    The structure of the hydrophilic part of the ATP synthase from chloroplasts (CF1) has been further investigated by electron microscopy and image analysis of negatively stained samples. The projections of three different types of CF1 were analyzed: the holoenzyme with five different subunits and two

  7. Optimization of ATP synthase function in mitochondria and chloroplasts via the adenylate kinase equilibrium

    Directory of Open Access Journals (Sweden)

    Abir U Igamberdiev

    2015-01-01

    Full Text Available The bulk of ATP synthesis in plants is performed by ATP synthase, the main bioenergetics engine of cells, operating both in mitochondria and in chloroplasts. The reaction mechanism of ATP synthase has been studied in detail for over half a century; however, its optimal performance depends also on the steady delivery of ATP synthase substrates and the removal of its products. For mitochondrial ATP synthase, we analyze here the provision of stable conditions for (i the supply of ADP and Mg2+, supported by adenylate kinase (AK equilibrium in the intermembrane space, (ii the supply of phosphate via membrane transporter in symport with H+, and (iii the conditions of outflow of ATP by adenylate transporter carrying out the exchange of free adenylates. We also show that, in chloroplasts, AK equilibrates adenylates and governs Mg2+ contents in the stroma, optimizing ATP synthase and Calvin cycle operation, and affecting the import of inorganic phosphate in exchange with triose phosphates. It is argued that chemiosmosis is not the sole component of ATP synthase performance, which also depends on AK-mediated equilibrium of adenylates and Mg2+, adenylate transport and phosphate release and supply.

  8. Digestive system of the sacoglossan Plakobranchus ocellatus (Gastropoda: Opisthobranchia): light- and electron-microscopic observations with remarks on chloroplast retention.

    Science.gov (United States)

    Hirose, Euichi

    2005-08-01

    The sacoglossan Plakobranchus ocellatus feeds by sucking the cytoplasmic contents from algae and retains intact algal chloroplasts within the cells of the digestive gland. Morphology of the entire digestive system of this species was firstly described by means of a combination of histology and electron microscopy (both SEM and TEM). The short alimentary canal is confined to the head, and the anus opens at the anterior right corner of the pericardial swelling, as is the case in many non-shelled sacoglossans. The alimentary canal of the specimens examined rarely contained ingesta, suggesting that the retained chloroplasts provide sufficient nourishment to the sacoglossan hosts and that sea slugs with empty stomachs survive well in the field. The digestive gland, with the retained chloroplasts, branches from the stomach and is sparsely distributed throughout the body, including the head region, but is aggregated mainly in the dorsal lamellae. Chloroplasts were occasionally found in the epithelial cells in the transitional region from the stomach wall to the digestive gland, which may be a site at which chloroplasts are incorporated into the animal cells by endocytosis. Numerous microvilli filling the lumen of the digestive gland suggest that molecules are actively transferred within the gland. The sea slug thus apparently provides a favorable environment to support the long-term retention and function of chloroplasts. PMID:16141704

  9. Role of electron transport chain of chloroplasts in oxidative burst of interaction between Erwinia amylovora and host cells.

    Science.gov (United States)

    Abdollahi, Hamid; Ghahremani, Zahra; Erfaninia, Kobra; Mehrabi, Rahim

    2015-05-01

    Erwinia amylovora is a necrogenic bacterium, causing the fire blight disease on many rosaceous plants. Triggering oxidative burst by E. amylovora is a key response by which host plants try to restrain pathogen spread. Electron transport chain (ETC) of chloroplasts is known as an inducible source of reactive oxygen species generation in various stresses. This research was performed to assess the role of this ETC in E. amylovora-host interaction using several inhibitors of this chain in susceptible and resistant apple and pear genotypes. All ETC inhibitors delayed appearance of disease necrosis, but the effects of methyl viologen, glutaraldehyde, and DCMU were more significant. In the absence of inhibitors, resistant genotypes showed an earlier and severe H2O2 generation and early suppression of redox dependent, psbA gene. The effects of inhibitors were corresponding to the redox potential of ETC inhibitory sites. In addition, delayed necrosis appearance was associated with the decreased disease severity and delayed H2O2 generation. These results provide evidences for the involvement of this ETC in host oxidative burst and suggest that chloroplast ETC has significant role in E. amylovora-host interaction. PMID:25820489

  10. A Novel Nucleus-encoded Chloroplast Protein, PIFI, Is Involved in NAD(P)H Dehydrogenase Complex Mediated Chlororespiratory and Possibly Cyclic Electron Transport in Arabidopsis

    Science.gov (United States)

    A transient rise in chlorophyll fluorescence after a light-to-dark transition reflects non-photochemical reduction of the plastoquinone pool. This process is dependent on the activity of the chloroplast NAD(P)H-dehydrogease complex (NDH) which mediates electron flow from stromal reductants to the pl...

  11. The reduction of artificial electron acceptors at sub-zero temperatures by chloroplasts suspended in fluid media.

    Science.gov (United States)

    Cox, R P

    1975-06-17

    1. Chloroplasts can be suspended in aqueous/organic mixtures which are liquid at sub-zero temperatures with a good retention of the ability to reduce artificial electron acceptors. The reduction of ferricyanide and 2,6-dichlorophenolindophenol at temperatures above 0 degrees C is about 50% inhibited by 50% (v/v) ethylene glycol. Higher concentrations cause more extensive inhibition. 2. Different solvents were compared on the basis of their ability to cause a given depression of the freezing point of an aqueous solution. Ethylene glycol caused less inhibition of electron transport than glycerol, which in turn was found to be superior to methanol. 3. The reduction of oxidised 2,3,5,6-tetramethyl-p-phenylenediamine could be measured at -25 degrees C in 40% (v/v) ethylene glycol. Using an acceptor with a high extinction coefficient, methyl purple (a derivative of 2,6-dichlorophenolindophenol) it was possible to observe electron flow at temperatures as low as -40 degrees C in 50% (v/v) ethylene glycol. 4. From studies of the effects of the inhibitors 3(3,4-dichlorophenyl)-1,1-dimethylurea and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone it is suggested that electron flow from the donor side of Photosystem II to the acceptor side of Photosystem I can occur at temperatures at least as low as -25 degrees C. The ultimate electron donor is presumably water but it was not possible to demonstrate this directly. PMID:1138892

  12. On the structure of the spinach chloroplast

    NARCIS (Netherlands)

    Thomas, J.B.; Bustraan, M.; Paris, C.H.

    1952-01-01

    The structure of spinach chloroplasts was investigated with the aid of the electron microscope. It has been established that: 1. 1. the outer membrane of the chloroplasts is composed of both proteins and lipoids. 2. 2. the stroma is also built up by these components. 3. 3. within the stroma memb

  13. Small chloroplast-targeted DnaJ proteins are involved in optimization of photosynthetic reactions in Arabidopsis thaliana

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    Piippo Mirva

    2010-03-01

    Full Text Available Abstract Background DnaJ proteins participate in many metabolic pathways through dynamic interactions with various components of these processes. The role of three small chloroplast-targeted DnaJ proteins, AtJ8 (At1 g80920, AtJ11 (At4 g36040 and AtJ20 (At4 g13830, was investigated here using knock-out mutants of Arabidopsis thaliana. Photochemical efficiency, capacity of CO2 assimilation, stabilization of Photosystem (PS II dimers and supercomplexes under high light illumination, energy distribution between PSI and PSII and phosphorylation of PSII-LHCII proteins, global gene expression profiles and oxidative stress responses of these DnaJ mutants were analyzed. Results Knockout of one of these proteins caused a series of events including a decrease in photosynthetic efficiency, destabilization of PSII complexes and loss of control for balancing the redox reactions in chloroplasts. Data obtained with DNA microarray analysis demonstrated that the lack of one of these DnaJ proteins triggers a global stress response and therefore confers the plants greater tolerance to oxidative stress induced by high light or methyl viologen treatments. Expression of a set of genes encoding enzymes that detoxify reactive oxygen species (ROS as well as a number of stress-related transcription factors behaved in the mutants at growth light similarly to that when wild-type (WT plants were transferred to high light. Also a set of genes related to redox regulation were upregulated in the mutants. On the other hand, although the three DnaJ proteins reside in chloroplasts, the expression of most genes encoding thylakoid membrane proteins was not changed in the mutants. Conclusion It is proposed that the tolerance of the DnaJ protein knockout plants to oxidative stress occurs at the expense of the flexibility of photosynthetic reactions. Despite the fact that the effects of the individual protein knockout on the response of plants to high light treatment are quite similar

  14. Extending the biosynthetic repertoires of cyanobacteria and chloroplasts.

    Science.gov (United States)

    Nielsen, Agnieszka Zygadlo; Mellor, Silas Busck; Vavitsas, Konstantinos; Wlodarczyk, Artur Jacek; Gnanasekaran, Thiyagarajan; Perestrello Ramos H de Jesus, Maria; King, Brian Christopher; Bakowski, Kamil; Jensen, Poul Erik

    2016-07-01

    Chloroplasts in plants and algae and photosynthetic microorganisms such as cyanobacteria are emerging hosts for sustainable production of valuable biochemicals, using only inorganic nutrients, water, CO2 and light as inputs. In the past decade, many bioengineering efforts have focused on metabolic engineering and synthetic biology in the chloroplast or in cyanobacteria for the production of fuels, chemicals and complex, high-value bioactive molecules. Biosynthesis of all these compounds can be performed in photosynthetic organelles/organisms by heterologous expression of the appropriate pathways, but this requires optimization of carbon flux and reducing power, and a thorough understanding of regulatory pathways. Secretion or storage of the compounds produced can be exploited for the isolation or confinement of the desired compounds. In this review, we explore the use of chloroplasts and cyanobacteria as biosynthetic compartments and hosts, and we estimate the levels of production to be expected from photosynthetic hosts in light of the fraction of electrons and carbon that can potentially be diverted from photosynthesis. The supply of reducing power, in the form of electrons derived from the photosynthetic light reactions, appears to be non-limiting, but redirection of the fixed carbon via precursor molecules presents a challenge. We also discuss the available synthetic biology tools and the need to expand the molecular toolbox to facilitate cellular reprogramming for increased production yields in both cyanobacteria and chloroplasts. PMID:27005523

  15. Proteomic Insight into the Response of Arabidopsis Chloroplasts to Darkness

    Science.gov (United States)

    Wang, Jing; Yu, Qingbo; Xiong, Haibo; Wang, Jun; Chen, Sixue; Yang, Zhongnan; Dai, Shaojun

    2016-01-01

    Chloroplast function in photosynthesis is essential for plant growth and development. It is well-known that chloroplasts respond to various light conditions. However, it remains poorly understood about how chloroplasts respond to darkness. In this study, we found 81 darkness-responsive proteins in Arabidopsis chloroplasts under 8 h darkness treatment. Most of the proteins are nucleus-encoded, indicating that chloroplast darkness response is closely regulated by the nucleus. Among them, 17 ribosome proteins were obviously reduced after darkness treatment. The protein expressional patterns and physiological changes revealed the mechanisms in chloroplasts in response to darkness, e.g., (1) inhibition of photosystem II resulted in preferential cyclic electron flow around PSI; (2) promotion of starch degradation; (3) inhibition of chloroplastic translation; and (4) regulation by redox and jasmonate signaling. The results have improved our understanding of molecular regulatory mechanisms in chloroplasts under darkness. PMID:27137770

  16. Penumbra modifier for optimal electron field combination

    International Nuclear Information System (INIS)

    Treatment with megavoltage electron beam is ideal for irradiating shallow seated tumors because of their limited range in tissues. However, the treatment of extended areas with electrons requires the use of two or more adjacent fields. Variations may arise at the junction of the fields. These dose variations come from the presence of large bulges in the low value isodose curves created by electron beam divergence and lateral scattering in tissues. Overlapping of these bulges, creates a high dose region at depths. While constriction of the isodose curves near the surface may produce a Long-term follow-up study critically on the fields separation. To overcome this problem, several authors have proposed techniques for matching electron beam edge in such a way as to make the overlap region as uniform as possible. The simplest approach to the problem is to optimize the skin gap between the two adjacent electron field edges. The increased lateral scatter of low-energy electrons and the machine specific characteristics of an electron beam penumbra make the determination of an optimized skin gap somewhat complicated. Optimization is achieved by a complete set of trial and error measurements. The main limitation to the usefulness of the optimized skin gap technique is the strong sensitivity of the dose distribution in the field junction region to small deviation in field separation or in the angulation of the incident electron beams, making it strongly dependent on positioning. The present study is done at electron beam energies of 6, 8, and 15 MeV. The method depends on the abutment of different field areas using beam edge modifier (Penumbra Generator) made of cerrobend. The objectives of this study are to present a systematic study of the modified electron field for better under standing of the behavior and physical characteristics of the penumbra generator, and to investigate the feasibility of using this technique for large electron fields. Also to obtain a quantitative

  17. Nitrogen control of chloroplast differentiation

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, G.W.

    1992-07-01

    This project is directed toward understanding how the availability of nitrogen affects the accumulation of chloroplast pigments and proteins functioning in energy transduction and carbon metabolism. Molecular analyses performed with Chlamydomonas reinhardtii grown in a continuous culture system such that ammonium concentration is maintained at a low steady-state concentration so as to limit cell division. As compared to chloroplasts from cells of non-limiting nitrogen provisions, chloroplasts of N-limited cells are profoundly chlorophyll-deficient but still assimilate carbon for deposition of as starch and as storage lipids. Chlorophyll deficiency arises by limiting accumulation of appropriate nuclear-encoded mRNAs of and by depressed rates of translation of chloroplast mRNAs for apoproteins of reaction centers. Chloroplast translational effects can be partially ascribed to diminished rates of chlorophyll biosynthesis in N-limited cells, but pigment levels are not determinants for expression of the nuclear light-harvesting protein genes. Consequently, other signals that are responsive to nitrogen availability mediate transcriptional or post-transcriptional processes for accumulation of the mRNAs for LHC apoproteins and other mRNAs whose abundance is dependent upon high nitrogen levels. Conversely, limited nitrogen availability promotes accumulation of other proteins involved in carbon metabolism and oxidative electron transport in chloroplasts. Hence, thylakoids of N-limited cells exhibit enhanced chlororespiratory activities wherein oxygen serves as the electron acceptor in a pathway that involves plastoquinone and other electron carrier proteins that remain to be thoroughly characterized. Ongoing and future studies are also outlined.

  18. Update on chloroplast research

    OpenAIRE

    Armbruster, Ute; Pesaresi, Paolo; Pribil, Mathias; Hertle, Alexander; Leister, Dario

    2010-01-01

    Chloroplasts, the green differentiation form of plastids, are the sites of photosynthesis and other important plant functions. Genetic and genomic technologies have greatly boosted the rate of discovery and functional characterization of chloroplast proteins during the past decade. Indeed, data obtained using high-throughput methodologies, in particular proteomics and transcriptomics, are now routinely used to assign functions to chloroplast proteins. Our knowledge of many chloroplast process...

  19. Solar energy conversion by chloroplast photoelectrochemical cells

    Science.gov (United States)

    Bhardwaj, R.; Pan, R. L.; Gross, E. L.

    1981-01-01

    A photoelectrochemical cell based on chloroplasts which generates large photovoltages and photocurrents from solar energy is presented. The cell contains broken Type C chloroplasts placed on a filter separating compartments containing an electron acceptor and electron donor with platinum electrodes in each. Photovoltages were observed across a load resistance of 3000 ohms with either flavin mononucleotide or anthroquinone 2-sulphonate as the electron acceptor and dichlorophenol indophenol as the donor, and persisted for 1-2 hr after the light was turned off. The powers and short circuit currents obtained in the chloroplast cells are nearly equal to those obtained in cells based on isolated photosystem I particles. Finally, an efficiency of 2.3% has been measured for the chloroplast contribution to the total power in flavin mononucleotide cells.

  20. Evidence for a respiratory chain in the chloroplast

    OpenAIRE

    Bennoun, Pierre

    1982-01-01

    Evidence is given for the existence of an electron transport pathway to oxygen in the thylakoid membranes of chloroplasts (chlororespiration). Plastoquinone is shown to be a redox carrier common to both photosynthetic and chlororespiratory pathways. It is shown that, in dark-adapted chloroplasts, an electrochemical gradient is built up across the thylakoid membrane by transfer of electrons through the chlororespiratory chain as well as by reverse functioning of the chloroplast ATPases. It is ...

  1. Chloroplasts in tissues of some herbaceous stems

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    Roman Maksymowych

    2014-02-01

    Full Text Available Serial sections of mature stems of ten species of herbaceous dicotyledonous plants were examined by light microscopy and the number of chloroplasts per cell was estimated in epidermis, collenchyma and cortex. Chloroplast identification was made by both light and transmission electron microscopy. Chloroplasts were present in epidermis, collenchyma and cortex tissues of all stems examined. The smallest number of chloroplasts was observed in the epidermis. Collenchyma cells had the largest number of plastids in four of the genera and cortex cells had the largest number in the remaining six genera. The stem epidermis of all genera contained stomates as demonstrated by scanning electron microscopy and aceto-orcein stained epidermal peels.

  2. Penumbra modifier for optimal electron fields combination

    International Nuclear Information System (INIS)

    Abutment of two or more electron fields to irradiate extended areas may lead to significant dose inhomogeneities in the junction region. This study describes the geometric and dosimetric characteristics of a device developed to modify the penumbra of an electron beam and therapy improve of dose uniformity in the over lap region when fields are abutted. The device is lipowitz metal block placed on top of the insertion plate of the electron applicator and positioned to stop part of he electron beam on side of field abutment. The air-scattered electrons beyond the block increase the penumbra width from about 1,4 to 2-7-43.4 cm at SSD 100 cm, the modified penumbra is broad and almost linear at all depths for the 6.8, and 15 MeV electron beams used. Film dosimetry was used to obtain profiles, iso-dose distributions, single modified beams and matched fields of 6, 10, and 15 MeV. Wellhofer dosimetry system was used to obtain beam profiles and iso-dose distributions of single modified beams needed for CADPLAN treatment planning system, which used to optimize and compare the skin gap to be used and to quantify the dose uniformity in a junction of the field separation for both modified and non-modified beams. Results are presented for various field configurations without the penumbra modifier; lateral setup error of 2-3 mm may introduce dose variations of 20% or more in the junction region. Similar setup error cause less than 5% dose variations when the penumbra modifier is used to match the field

  3. Optimization of codon composition and regulatory elements for expression of human insulin like growth factor-1 in transgenic chloroplasts and evaluation of structural identity and function

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    Sandberg Laurence

    2009-04-01

    Full Text Available Abstract Background Transgenic chloroplasts are potential bioreactors for recombinant protein production, especially for achievement of high levels of protein expression and proper folding. Production of therapeutic proteins in leaves provides transgene containment by elimination of reproductive structures. Therefore, in this study, human Insulin like Growth Factor-1 is expressed in transgenic chloroplasts for evaluation of structural identity and function. Results Expression of the synthetic Insulin like Growth Factor 1 gene (IGF-1s, 60% AT was observed in transformed E. coli. However, no native IGF-1 gene (IGF-1n, 41% AT product was detected in the western blots in E. coli. Site-specific integration of the transgenes into the tobacco chloroplast genome was confirmed after transformation using PCR. Southern blot analysis confirmed that the transgenic lines were homoplasmic. The transgenic plant lines had IGF-1s expression levels of 11.3% of total soluble protein (TSP. The IGF-1n plants contained 9.5% TSP as IGF-1n, suggesting that the chloroplast translation machinery is more flexible than E. coli in codon preference and usage. The expression of IGF-1 was increased up to 32% TSP under continuous illumination by the chloroplast light regulatory elements. IgG-Sepharose affinity column chromatographic separation of Z domain containing chloroplast derived IGF-1 protein, single and two dimensional electrophoresis methods and mass spectrometer analysis confirmed the identity of human IGF-1 in transgenic chloroplasts. Two spots analyzed from 2-D focusing/phoresis acrylamide gel showed the correct amino acid sequence of human IGF-1 and the S. aureus Z-tag. Cell proliferation assays in human HU-3 cells demonstrated the biological activity of chloroplast derived IGF-1 even in the presence of the S. aureus Z tag. Conclusion This study demonstrates that the human Insulin like Growth Factor-1 expressed in transgenic chloroplasts is identical to the native

  4. Optimization of codon composition and regulatory elements for expression of human insulin like growth factor-1 in transgenic chloroplasts and evaluation of structural identity and function

    Science.gov (United States)

    Daniell, Henry; Ruiz, Gricel; Denes, Bela; Sandberg, Laurence; Langridge, William

    2009-01-01

    Background Transgenic chloroplasts are potential bioreactors for recombinant protein production, especially for achievement of high levels of protein expression and proper folding. Production of therapeutic proteins in leaves provides transgene containment by elimination of reproductive structures. Therefore, in this study, human Insulin like Growth Factor-1 is expressed in transgenic chloroplasts for evaluation of structural identity and function. Results Expression of the synthetic Insulin like Growth Factor 1 gene (IGF-1s, 60% AT) was observed in transformed E. coli. However, no native IGF-1 gene (IGF-1n, 41% AT) product was detected in the western blots in E. coli. Site-specific integration of the transgenes into the tobacco chloroplast genome was confirmed after transformation using PCR. Southern blot analysis confirmed that the transgenic lines were homoplasmic. The transgenic plant lines had IGF-1s expression levels of 11.3% of total soluble protein (TSP). The IGF-1n plants contained 9.5% TSP as IGF-1n, suggesting that the chloroplast translation machinery is more flexible than E. coli in codon preference and usage. The expression of IGF-1 was increased up to 32% TSP under continuous illumination by the chloroplast light regulatory elements. IgG-Sepharose affinity column chromatographic separation of Z domain containing chloroplast derived IGF-1 protein, single and two dimensional electrophoresis methods and mass spectrometer analysis confirmed the identity of human IGF-1 in transgenic chloroplasts. Two spots analyzed from 2-D focusing/phoresis acrylamide gel showed the correct amino acid sequence of human IGF-1 and the S. aureus Z-tag. Cell proliferation assays in human HU-3 cells demonstrated the biological activity of chloroplast derived IGF-1 even in the presence of the S. aureus Z tag. Conclusion This study demonstrates that the human Insulin like Growth Factor-1 expressed in transgenic chloroplasts is identical to the native protein and is fully

  5. Techniques for optimizing inerting in electron processors

    International Nuclear Information System (INIS)

    The design of an ''inert gas'' distribution system in an electron processor must satisfy a number of requirements. The first of these is the elimination or control of beam produced ozone and NOx which can be transported from the process zone by the product into the work area. Since the tolerable levels for O3 in occupied areas around the processor are 3 in the beam heated process zone, or exhausting and dilution of the gas at the processor exit. The second requirement of the inerting system is to provide a suitable environment for completing efficient, free radical initiated addition polymerization. The competition between radical loss through de-excitation and that from O2 quenching must be understood. This group has used gas chromatographic analysis of electron cured coatings to study the trade-offs of delivered dose, dose rate and O2 concentrations in the process zone to determine the tolerable ranges of parameter excursions for production quality control purposes. These techniques are described for an ink coating system on paperboard, where a broad range of process parameters have been studied (D, D radical, O2). It is then shown how the technique is used to optimize the use of higher purity (10-100 ppm O2) nitrogen gas for inerting, in combination with lower purity (2-20,000 ppm O2) non-cryogenically produced gas, as from a membrane or pressure swing adsorption generators. (author)

  6. Nitrogen control of chloroplast development: Progress report

    International Nuclear Information System (INIS)

    A manifestation of nitrogen deficiency in vascular plants and algae is chlorosis, indicating that chloroplast biogenesis can be strongly restricted by direct or indirect effects of nitrogen assimilation products. To define the molecular basis of nitrogen responses we are using Chlamydomonas reinhardtii. Depending on the levels of ammonium, steady-state deficiency conditions are established such that the cellular levels of chlorophylls and xanthophylls are depressed. Chloroplasts in nitrogen-deficient cells contain appreciable levels of carbon assimilation enzyme and thylakoids with high electron transport activities. However, the light harvesting complexes are nearly absent and Photosystem I exhibits unusual characteristics. Studies of rates of protein synthesis by in vivo pulse-chase labeling and levels of RNAs encoded by the chloroplast and nuclear genomes have been initiated: the accumulation of transcripts for the nuclear light-harvesting apoproteins is dramatically altered qualitatively and quantitatively; there is no major effect on chloroplast RNAs but, in general, these are inefficiently utilized for protein synthesis until nitrogen is provided to the cultures. Supplying nitrogen results in an almost immediate release of chloroplast mRNAs from a translational arrest but the stimulation of the accumulation of nuclear transcripts for light-harvesting apoproteins does not occur until after a 1-2 hour lag

  7. Electronic Commerce Logistics Network Optimization Based on Swarm Intelligent Algorithm

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    Yabing Jiao

    2013-09-01

    Full Text Available This article establish an efficient electronic commerce logistics operation system to reduce distribution costs and build a logistics network operation model based on around the B2C electronic commerce enterprise logistics network operation system. B2C electronic commerce transactions features in the enterprise network platform. To solve the NP-hard problem this article use hybrid ant colony algorithm, particle swarm algorithm and group swarm intelligence algorithm to get a best solution. According to the intelligent algorithm, design of electronic commerce logistics network optimization system, enter the national 22 electronic commerce logistics network for validation. Through the experiment to verify the optimized logistics cost greatly decreased. This research can help B2C electronic commerce enterprise logistics network to optimize decision-making under the premise of ensuring the interests of consumers and service levels also can be an effective way for enterprises to improve the efficiency of logistics services and reduce operation costs

  8. Optimization Model for Environmental Stress Screening of Electronic Components

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Environmental stress screening (ESS) is a technological process to reduce the costly early field failure ofelectronic components. This paper builds an optimization model for ESS of electronic components to obtain the optimalESS duration. The failure phenomena of ESS are modeled by mix ed distribution, and optimal ESS duration is definedby maximizing life-cycle cost savings under the condition of meeting reliability requirement.

  9. Evolution of the Cp-Actin-based Motility System of Chloroplasts in Green Plants.

    Science.gov (United States)

    Suetsugu, Noriyuki; Wada, Masamitsu

    2016-01-01

    During the course of green plant evolution, numerous light responses have arisen that optimize their growth under fluctuating light conditions. The blue light receptor phototropin mediates several photomovement responses at the tissue, cellular and organelle levels. Chloroplast photorelocation movement is one such photomovement response, and is found not only in most green plants, but also in some red algae and photosynthetic stramenopiles. In general, chloroplasts move toward weak light to maximally capture photosynthetically active radiation (the chloroplast accumulation response), and they move away from strong light to avoid photodamage (the avoidance response). In land plants, chloroplast movement is dependent on specialized actin filaments, chloroplast-actin filaments (cp-actin filaments). Through molecular genetic analysis using Arabidopsis thaliana, many molecular factors that regulate chloroplast photorelocation were identified. In this Perspective, we discuss the evolutionary history of the molecular mechanism for chloroplast photorelocation movement in green plants in view of cp-actin filaments. PMID:27200035

  10. Reactive Nitrogen Species-Dependent Effects on Soybean Chloroplasts

    OpenAIRE

    Puntarulo, Susana; Jasid, Sebastián; Simontacchi, Marcela

    2007-01-01

    Nitric oxide (NO) generation by soybean (Glycine max, var ADM 4800) chloroplasts was studied by electron paramagnetic resonance (EPR) spin-trapping technique.1 Both nitrite and L-arginine (arg) are the required substrates for enzymatic activities considered as possible sources of NO in plants. Soybean chloroplasts showed a NO production of 3.2 ± 0.2 nmol min−1 mg−1 protein in the presence of 1 mM NaNO2. Chloroplasts incubated with 1 mM arg showed a NO production of 0.76 ± 0.04 nmol min−1 mg−1...

  11. Optimization of combined electron and photon beams for breast cancer

    International Nuclear Information System (INIS)

    Recently, intensity-modulated radiation therapy and modulated electron radiotherapy have gathered a growing interest for the treatment of breast and head and neck tumours. In this work, we carried out a study to combine electron and photon beams to achieve differential dose distributions for multiple target volumes simultaneously. A Monte Carlo based treatment planning system was investigated, which consists of a set of software tools to perform accurate dose calculation, treatment optimization, leaf sequencing and plan analysis. We compared breast treatment plans generated using this home-grown optimization and dose calculation software for different treatment techniques. Five different planning techniques have been developed for this study based on a standard photon beam whole breast treatment and an electron beam tumour bed cone down. Technique 1 includes two 6 MV tangential wedged photon beams followed by an anterior boost electron field. Technique 2 includes two 6 MV tangential intensity-modulated photon beams and the same boost electron field. Technique 3 optimizes two intensity-modulated photon beams based on a boost electron field. Technique 4 optimizes two intensity-modulated photon beams and the weight of the boost electron field. Technique 5 combines two intensity-modulated photon beams with an intensity-modulated electron field. Our results show that technique 2 can reduce hot spots both in the breast and the tumour bed compared to technique 1 (dose inhomogeneity is reduced from 34% to 28% for the target). Techniques 3, 4 and 5 can deliver a more homogeneous dose distribution to the target (with dose inhomogeneities for the target of 22%, 20% and 9%, respectively). In many cases techniques 3, 4 and 5 can reduce the dose to the lung and heart. It is concluded that combined photon and electron beam therapy may be advantageous for treating breast cancer compared to conventional treatment techniques using tangential wedged photon beams followed by a boost

  12. Copper Delivery to Chloroplast Proteins and its Regulation

    OpenAIRE

    Aguirre, Guadalupe; Pilon, Marinus

    2016-01-01

    Copper is required for photosynthesis in chloroplasts of plants because it is a cofactor of plastocyanin, an essential electron carrier in the thylakoid lumen. Other chloroplast copper proteins are copper/zinc superoxide dismutase and polyphenol oxidase, but these proteins seem to be dispensable under conditions of low copper supply when transcripts for these proteins undergo microRNA-mediated down regulation. Two ATP-driven copper transporters function in tandem to deliver copper to chloropl...

  13. Optimization of electron beam crosslinking of wire and cable insulation

    International Nuclear Information System (INIS)

    The computer simulations based on Monte Carlo (MC) method and the ModeCEB software were carried out in connection with electron beam (EB) radiation set-up for crosslinking of electric wire and cable insulation. The theoretical predictions for absorbed dose distribution in irradiated electric insulation induced by scanned EB were compared to the experimental results of irradiation that was carried out in the experimental set-up based on ILU 6 electron accelerator with electron energy 0.5–2.0 MeV. The computer simulation of the dose distributions in two-sided irradiation system by a scanned electron beam in multilayer circular objects was performed for various process parameters, namely electric wire and cable geometry (thickness of insulation layers and copper wire diameter), type of polymer insulation, electron energy, energy spread and geometry of electron beam, electric wire and cable layout in irradiation zone. The geometry of electron beam distribution in the irradiation zone was measured using CTA and PVC foil dosimeters for available electron energy range. The temperature rise of the irradiated electric wire and irradiation homogeneity were evaluated for different experimental conditions to optimize technological process parameters. The results of computer simulation are consistent with the experimental data of dose distribution evaluated by gel-fraction measurements. Such conformity indicates that ModeCEB computer simulation is reliable and sufficient for optimization absorbed dose distribution in the multi-layer circular objects irradiated with scanned electron beams. - Highlights: ► We model wire and cables irradiation process by Monte Carlo simulations. ► We optimize irradiation configuration for various process parameters. ► Temperature rise and irradiation homogeneity were evaluated. ► Calculation (dose) and experimental (gel-fraction) results were compared. ► Computer simulation was found reliable and sufficient for process optimization.

  14. Efficient Hybrid Optimal Design Method for Power Electronics Converters

    CERN Document Server

    AUTHOR|(SzGeCERN)697719; Aguglia, Davide; Viarouge, Philippe; Cros, Jérôme

    2015-01-01

    This paper presents a novel design methodology for dimensioning optimal power-electronic converters, which is able to achieve the precision of numerical simulation-based optimization procedures, however minimizing the overall computation time. The approach is based on the utilization of analytical and frequency-domain design models for a numerical optimization process, a validation with numerical simulations of the intermediate optimal solutions, and the correction of the analytical design models precision from the numerical simulation results. This method allows using the numerical simulation in an efficient way, where typically less than ten correction iterations are required. In order to demonstrate the performances of the proposed methodology, the calculation of the control parameters for an H-bridge DC-DC converter and the optimal dimensioning of a damped output filter for a buck converter using the proposed approach is presented.

  15. Optimizing chirped laser pulse parameters for electron acceleration in vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Akhyani, Mina; Jahangiri, Fazel; Niknam, Ali Reza; Massudi, Reza, E-mail: r-massudi@sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, Tehran 1983969411 (Iran, Islamic Republic of)

    2015-11-14

    Electron dynamics in the field of a chirped linearly polarized laser pulse is investigated. Variations of electron energy gain versus chirp parameter, time duration, and initial phase of laser pulse are studied. Based on maximizing laser pulse asymmetry, a numerical optimization procedure is presented, which leads to the elimination of rapid fluctuations of gain versus the chirp parameter. Instead, a smooth variation is observed that considerably reduces the accuracy required for experimentally adjusting the chirp parameter.

  16. Longevity of guard cell chloroplasts in falling leaves: implication for stomatal function and cellular aging

    Energy Technology Data Exchange (ETDEWEB)

    Zeiger, E.; Schwartz, A.

    1982-11-12

    Guard cell chloroplasts in senescing leaves from 12 species of perennial trees and three species of annual plants survived considerably longer than their mesophyll counterparts. In Ginkgo biloba, stomata from yellow leaves opened during the day and closed at night; guard cell chloroplasts from these leaves showed fluorescence transients associated with electron transport and photophosphorylation. These findings indicate that guard cell chloroplasts are highly conserved throughout the life-span of the leaf and that leaves retain stomatal control during senescence.

  17. Optimization and application of electron acceleration in relativistic laser plasmas

    International Nuclear Information System (INIS)

    This thesis describes experiments and simulations of the acceleration of electrons to relativistic energies (toward γe ∼ 103) by structures in plasmas which are generated by ultrashort (pulse length < 10-14 s) laser pulses. The first part of this work discusses experiments in a parameter space where quasimonoenergetic electron bunches are generated in subcritical (gaseous) plasmas and compares them to analytical scalings. A primary concern in this work is to optimize the stability of the energy and the pointing of the electrons. The second part deals with acceleration of electrons along the surface of solid substrates by laser-plasma interaction. The measurements show good agreement with existing analytical scalings and dedicated numerical simulations. In the third part, two new concepts for multi-stage acceleration will be presented and parameterised by analytical considerations and numerical simulations. The first method uses electron pairs, as produced in the first part, to transfer energy from the first bunch to the second by means of a plasma wave. The second method utilizes a low intensity laser pulse in order to inject electrons from a neutral gas into the accelerating phase of a plasma wave. The final chapter proposes and demonstrates a first application that has been developed in collaboration with ESA. The use of electron beams with exponential energy distribution, as in the second part of this work, offers the potential to investigate the resistance of electronic components against space radiation exposure.

  18. Photocathode Optimization for a Dynamic Transmission Electron Microscope: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, P; Flom, Z; Heinselman, K; Nguyen, T; Tung, S; Haskell, R; Reed, B W; LaGrange, T

    2011-08-04

    The Dynamic Transmission Electron Microscope (DTEM) team at Harvey Mudd College has been sponsored by LLNL to design and build a test setup for optimizing the performance of the DTEM's electron source. Unlike a traditional TEM, the DTEM achieves much faster exposure times by using photoemission from a photocathode to produce electrons for imaging. The DTEM team's work is motivated by the need to improve the coherence and current density of the electron cloud produced by the electron gun in order to increase the image resolution and contrast achievable by DTEM. The photoemission test setup is nearly complete and the team will soon complete baseline tests of electron gun performance. The photoemission laser and high voltage power supply have been repaired; the optics path for relaying the laser to the photocathode has been finalized, assembled, and aligned; the internal setup of the vacuum chamber has been finalized and mostly implemented; and system control, synchronization, and data acquisition has been implemented in LabVIEW. Immediate future work includes determining a consistent alignment procedure to place the laser waist on the photocathode, and taking baseline performance measurements of the tantalum photocathode. Future research will examine the performance of the electron gun as a function of the photoemission laser profile, the photocathode material, and the geometry and voltages of the accelerating and focusing components in the electron gun. This report presents the team's progress and outlines the work that remains.

  19. Phase II Final Report Computer Optimization of Electron Guns

    Energy Technology Data Exchange (ETDEWEB)

    R. Lawrence Ives; Thuc Bui; Hien Tran; Michael Read; Adam Attarian; William Tallis

    2011-04-15

    This program implemented advanced computer optimization into an adaptive mesh, finite element, 3D, charged particle code. The routines can optimize electron gun performance to achieve a specified current, beam size, and perveance. It can also minimize beam ripple and electric field gradients. The magnetics optimization capability allows design of coil geometries and magnetic material configurations to achieve a specified axial magnetic field profile. The optimization control program, built into the charged particle code Beam Optics Analyzer (BOA) utilizes a 3D solid modeling package to modify geometry using design tables. Parameters within the graphical user interface (currents, voltages, etc.) can be directly modified within BOA. The program implemented advanced post processing capability for the optimization routines as well as the user. A Graphical User Interface allows the user to set up goal functions, select variables, establish ranges of variation, and define performance criteria. The optimization capability allowed development of a doubly convergent multiple beam gun that could not be designed using previous techniques.

  20. Discrete Optimization of Electronic Hyperpolarizabilities in a Chemical Subspace.

    Science.gov (United States)

    Rinderspacher, B Christopher; Andzelm, Jan; Rawlett, Adam; Dougherty, Joseph; Beratan, David N; Yang, Weitao

    2009-12-01

    We introduce a general optimization algorithm based on an interpolation of property values on a hypercube. Each vertex of the hypercube represents a molecule, while the interior of the interpolation represents a virtual superposition ("alchemical" mutation) of molecules. The resultant algorithm is similar to branch-and-bound/tree-search methods. We apply the algorithm to the optimization of the first electronic hyperpolarizability for several tolane libraries. The search includes structural and conformational information. Geometries were optimized using the AM1 Hamiltonian, and first hyperpolarizabilities were computed using the INDO/S method. Even for small libraries, a significant improvement of the hyperpolarizability, up to a factor of ca. 4, was achieved. The algorithm was validated for efficiency and reproduced known experimental results. The algorithm converges to a local optimum at a computational cost on the order of the logarithm of the library size, making large libraries accessible. For larger libraries, the improvement was accomplished by performing electronic structure calculations on less than 0.01% of the compounds in the larger libraries. Alternation of electron donating and accepting groups in the tolane scaffold was found to produce candidates with large hyperpolarizabilities consistently. PMID:26602512

  1. Effect of alkyl-N-phenylcarbamates on photochemical activity of spinach chloroplasts

    International Nuclear Information System (INIS)

    This study is aimed to investigate the effect of alkyl-N-phenylcarbamates on photosynthetic electron transport in spinach chloroplasts, to determine site of action in the photosynthetic apparatus of spinach chloroplasts and to find correlations between their structure and biological activity. (authors)

  2. Sonication-based isolation and enrichment of Chlorella protothecoides chloroplasts for illumina genome sequencing

    Energy Technology Data Exchange (ETDEWEB)

    Angelova, Angelina [University of Arizona; Park, Sang-Hycuk [University of Arizona; Kyndt, John [Bellevue University; Fitzsimmons, Kevin [University of Arizona; Brown, Judith K [University of Arizona

    2013-09-01

    With the increasing world demand for biofuel, a number of oleaginous algal species are being considered as renewable sources of oil. Chlorella protothecoides Krüger synthesizes triacylglycerols (TAGs) as storage compounds that can be converted into renewable fuel utilizing an anabolic pathway that is poorly understood. The paucity of algal chloroplast genome sequences has been an important constraint to chloroplast transformation and for studying gene expression in TAGs pathways. In this study, the intact chloroplasts were released from algal cells using sonication followed by sucrose gradient centrifugation, resulting in a 2.36-fold enrichment of chloroplasts from C. protothecoides, based on qPCR analysis. The C. protothecoides chloroplast genome (cpDNA) was determined using the Illumina HiSeq 2000 sequencing platform and found to be 84,576 Kb in size (8.57 Kb) in size, with a GC content of 30.8 %. This is the first report of an optimized protocol that uses a sonication step, followed by sucrose gradient centrifugation, to release and enrich intact chloroplasts from a microalga (C. prototheocoides) of sufficient quality to permit chloroplast genome sequencing with high coverage, while minimizing nuclear genome contamination. The approach is expected to guide chloroplast isolation from other oleaginous algal species for a variety of uses that benefit from enrichment of chloroplasts, ranging from biochemical analysis to genomics studies.

  3. Genetic Analysis of Chloroplast Translation

    Energy Technology Data Exchange (ETDEWEB)

    Barkan, Alice

    2005-08-15

    The assembly of the photosynthetic apparatus requires the concerted action of hundreds of genes distributed between the two physically separate genomes in the nucleus and chloroplast. Nuclear genes coordinate this process by controlling the expression of chloroplast genes in response to developmental and environmental cues. However, few regulatory factors have been identified. We used mutant phenotypes to identify nuclear genes in maize that modulate chloroplast translation, a key control point in chloroplast gene expression. This project focused on the nuclear gene crp1, required for the translation of two chloroplast mRNAs. CRP1 is related to fungal proteins involved in the translation of mitochondrial mRNAs, and is the founding member of a large gene family in plants, with {approx}450 members. Members of the CRP1 family are defined by a repeated 35 amino acid motif called a ''PPR'' motif. The PPR motif is closely related to the TPR motif, which mediates protein-protein interactions. We and others have speculated that PPR tracts adopt a structure similar to that of TPR tracts, but with a substrate binding surface adapted to bind RNA instead of protein. To understand how CRP1 influences the translation of specific chloroplast mRNAs, we sought proteins that interact with CRP1, and identified the RNAs associated with CRP1 in vivo. We showed that CRP1 is associated in vivo with the mRNAs whose translation it activates. To explore the functions of PPR proteins more generally, we sought mutations in other PPR-encoding genes: mutations in the maize PPR2 and PPR4 were shown to disrupt chloroplast ribosome biogenesis and chloroplast trans-splicing, respectively. These and other results suggest that the nuclear-encoded PPR family plays a major role in modulating the expression of the chloroplast genome in higher plants.

  4. Design optimization of a spreader heat sink for power electronics

    Energy Technology Data Exchange (ETDEWEB)

    Maranzana, Gael; Perry, Isabelle; Maillet, Denis [Laboratoire d' Energetique et de Mecanique Theorique et Appliquee UMR 7563 CNRS-INPL-UHP, 2, avenue de la foret de Haye, BP 160, 54504 cedex, Vandoeuvre-les-Nancy (France); Rael, Stephane [Groupe de Recherche en Electrotechnique et Electronique de Nancy, 2, avenue de la foret de Haye, 54516 cedex, Vandoeuvre-les-Nancy (France)

    2004-01-01

    This article deals with a design method for optimizing heat spreaders dedicated to electronic board cooling. The modeling is based on the thermal quadrupole method which is an analytical exact and rapid method that can be implemented for suitable geometries. Under some conditions, an optimal thickness can be found for the spreader (or the heat sink base). It correspond to a minimization of the average or the maximal temperature of the heat sources. This optimal thickness is given in an non-dimensional form by an abacus which can be used in a quantitative way to design heat spreaders or, in a more qualitative way, to assess the function and the performance of the spreader. Locations of the sources on the heat spreader as well as the shape of the spreader are also optimized. Finally, the case of a pyramidal multi-layer heat spreader is considered in order to test the efficiency of the quadrupole method as a tool for modeling conductive heat transfer for optimization applications. (authors)

  5. Electron-Cloud Maps for LHC Scrubbing Optimization

    CERN Document Server

    Dominguez, O

    2013-01-01

    Electron-cloud maps as alternative to detailed build-up simulations have already been applied in the past for a few accelerators, e.g. RHIC and the LHC at 7 TeV. We here report on a first application of maps to optimize the “beam scrubbing” of the LHC arcs at injection energy: Maps are used to efficiently determine the optimum bunch filling pattern which maximizes the electron flux on the chamber wall, while respecting constraints on the central cloud density to ensure beam stability. In addition, new features have been explored, e.g. by introducing thresholds which divide regions where either linear maps or cubic maps best describe the build-up and the decay of an electron cloud. In the near future we plan to extend the map formalism to individual slices in a dipole field in order to represent the vertical “stripes”.

  6. Electron-Cloud Maps for the LHC Scrubbing Optimization

    CERN Document Server

    Dominguez, O

    2013-01-01

    Electron-cloud maps as alternative to detailed build-up simulations have already been applied in the past for a few accelerators, e.g. RHIC and the LHC at 7 TeV. We here report on a first application of maps to optimize the “beam scrubbing” of the LHC arcs at injection energy: Maps are used to efficiently determine the optimum bunch filling pattern which maximizes the electron flux on the chamber wall, while respecting constraints on the central cloud density to ensure beam stability. In addition, new features have been explored, e.g. by introducing thresholds which divide regions where either linear maps or cubic maps best describe the build-up and the decay of an electron cloud. In the near future we plan to extend the map formalism to individual slices in a dipole field in order to represent the vertical “stripes”. Presented at IPAC'13 Shanghai, 12-17 May 2013

  7. Chloroplast phosphoproteins: distribution of phosphoproteins within spinach chloroplasts

    International Nuclear Information System (INIS)

    The distribution of phosphoproteins within spinach chloroplasts was studied. Intact chloroplasts with good rates of CO2-dependent oxygen evolution were fed (γ-32P)ATP and then separated into stroma and membrane fractions. Only one major labelled stroma protein was identified by gel electrophoresis/autoradiography, with a mol. wt. of 66000. The membranes were separated into envelopes and thylakoid fractions. Three labelled proteins were separated by gel electrophoresis in the envelope with mol. wt. of 50500, 29000 and 13000. (author)

  8. Extending the biosynthetic repertoires of cyanobacteria and chloroplasts

    DEFF Research Database (Denmark)

    Nielsen, Agnieszka Janina Zygadlo; Mellor, Silas Busck; Vavitsas, Konstantinos;

    2016-01-01

    The chloroplasts found in plants and algae, and photosynthetic microorganisms such as cyanobacteria, are emerging hosts for sustainable production of valuable biochemicals, using only inorganic nutrients, water, CO2 and light as inputs. In the past decade, many bioengineering efforts have focused...... on metabolic engineering and synthetic biology in the chloroplast or in cyanobacteria for the production of fuels, chemicals, as well as complex, high-value bioactive molecules. Biosynthesis of all these compounds can be performed in photosynthetic organelles/organisms by heterologous expression...... of chloroplasts and cyanobacteria as biosynthetic compartments and hosts, and we estimate the production levels to be expected from photosynthetic hosts in light of the fraction of electrons and carbon that can potentially be diverted from photosynthesis. The supply of reducing power, in the form of electrons...

  9. Optimization of harmonic sextupoles in Indus-2 electron storage ring

    International Nuclear Information System (INIS)

    Dynamic aperture is one of the deciding parameters of the low emittance electron storage ring performance. Sufficient dynamic aperture is required to reach higher injection efficiency as well as good beam lifetime. In low emittance storage rings, dynamic aperture is limited mainly by the chromaticity correcting sextupoles, which is enhanced by introducing more sextupole magnets in the dispersion free straight section of the ring lattice, known as “harmonic sextupoles”. In Indus-2 storage ring lattice also, there is a plan to accommodate harmonic sextupoles. In this paper we present, how the strength of harmonic sextupoles is optimized for suppressing resonance driving terms up to third order, those are responsible for reducing the dynamic aperture. In such optimization, one of the main difficulties is to choose the optimal weight factor for the different resonance driving terms. We evolved an approach for assigning the relative weight to the various resonances driving terms which is found to be working very well for Indus-2 storage ring. Following this approach, the strength of the harmonic sextupoles is optimized and there is a reasonable enhancement of dynamic aperture with harmonic sextupoles for two different working points of Indus-2

  10. Chloroplast ribosomes and protein synthesis.

    OpenAIRE

    Harris, E. H.; Boynton, J E; Gillham, N W

    1994-01-01

    Consistent with their postulated origin from endosymbiotic cyanobacteria, chloroplasts of plants and algae have ribosomes whose component RNAs and proteins are strikingly similar to those of eubacteria. Comparison of the secondary structures of 16S rRNAs of chloroplasts and bacteria has been particularly useful in identifying highly conserved regions likely to have essential functions. Comparative analysis of ribosomal protein sequences may likewise prove valuable in determining their roles i...

  11. Optimal Truncation in Ionization of hydrogen by Electron Impact

    Institute of Scientific and Technical Information of China (English)

    张程华; 牛英煜; 吴炜; 邱卫; 辛君丽; 王晓伟; 王京阳

    2003-01-01

    An analytic expression for the ionization amplitude of hydrogen by electron impact is found to contain a polynomial by an optimal truncation in an asymptotic series and a convergent series. The ionization amplitude, i.e., the transition matrix element on the energy shell, is decomposed into two parts: the structure-scattering factor and correlation factor, based on an approximation of the projectile plane wave in coplanar asymmetric geometries.The contribution of these factors to the triple differential cross section is evaluated using the method of optional truncation of asymptotic and convergent series.

  12. Optimal VLF Parameters for Pitch Angle Scattering of Trapped Electrons

    Science.gov (United States)

    Albert, J. M.; Inan, U. S.

    2001-12-01

    VLF waves are known to determine the lifetimes of energetic radiation belt electrons in the inner radiation belt and slot regions. Artificial injection of such waves from ground- or space-based transmitters may thus be used to affect the trapped electron population. In this paper, we seek to determine the optimal parameters (frequency and wave normal angle) of a quasi-monochromatic VLF wave using bounce-averaged quasi-linear theory. We consider the cumulative effects of all harmonic resonances and determine the diffusion rates of particles with selected energies on particular L-shells. We also compare the effects of the VLF wave to diffusion driven by other whistler-mode waves (plasmaspheric hiss, lightning, and VLF transmitters). With appropriate choice of the wave parameters, it may be possible to substantially reduce the lifetime of selected classes of particles.

  13. Nitrogen control of chloroplast differentiation. Annual progress report

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, G.W.

    1992-07-01

    This project is directed toward understanding how the availability of nitrogen affects the accumulation of chloroplast pigments and proteins functioning in energy transduction and carbon metabolism. Molecular analyses performed with Chlamydomonas reinhardtii grown in a continuous culture system such that ammonium concentration is maintained at a low steady-state concentration so as to limit cell division. As compared to chloroplasts from cells of non-limiting nitrogen provisions, chloroplasts of N-limited cells are profoundly chlorophyll-deficient but still assimilate carbon for deposition of as starch and as storage lipids. Chlorophyll deficiency arises by limiting accumulation of appropriate nuclear-encoded mRNAs of and by depressed rates of translation of chloroplast mRNAs for apoproteins of reaction centers. Chloroplast translational effects can be partially ascribed to diminished rates of chlorophyll biosynthesis in N-limited cells, but pigment levels are not determinants for expression of the nuclear light-harvesting protein genes. Consequently, other signals that are responsive to nitrogen availability mediate transcriptional or post-transcriptional processes for accumulation of the mRNAs for LHC apoproteins and other mRNAs whose abundance is dependent upon high nitrogen levels. Conversely, limited nitrogen availability promotes accumulation of other proteins involved in carbon metabolism and oxidative electron transport in chloroplasts. Hence, thylakoids of N-limited cells exhibit enhanced chlororespiratory activities wherein oxygen serves as the electron acceptor in a pathway that involves plastoquinone and other electron carrier proteins that remain to be thoroughly characterized. Ongoing and future studies are also outlined.

  14. Standardless quantification by parameter optimization in electron probe microanalysis

    Energy Technology Data Exchange (ETDEWEB)

    Limandri, Silvina P. [Instituto de Fisica Enrique Gaviola (IFEG), CONICET (Argentina); Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Medina Allende s/n, (5016) Cordoba (Argentina); Bonetto, Rita D. [Centro de Investigacion y Desarrollo en Ciencias Aplicadas Dr. Jorge Ronco (CINDECA), CONICET, 47 Street 257, (1900) La Plata (Argentina); Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 1 and 47 Streets (1900) La Plata (Argentina); Josa, Victor Galvan; Carreras, Alejo C. [Instituto de Fisica Enrique Gaviola (IFEG), CONICET (Argentina); Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Medina Allende s/n, (5016) Cordoba (Argentina); Trincavelli, Jorge C., E-mail: trincavelli@famaf.unc.edu.ar [Instituto de Fisica Enrique Gaviola (IFEG), CONICET (Argentina); Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Medina Allende s/n, (5016) Cordoba (Argentina)

    2012-11-15

    A method for standardless quantification by parameter optimization in electron probe microanalysis is presented. The method consists in minimizing the quadratic differences between an experimental spectrum and an analytical function proposed to describe it, by optimizing the parameters involved in the analytical prediction. This algorithm, implemented in the software POEMA (Parameter Optimization in Electron Probe Microanalysis), allows the determination of the elemental concentrations, along with their uncertainties. The method was tested in a set of 159 elemental constituents corresponding to 36 spectra of standards (mostly minerals) that include trace elements. The results were compared with those obtained with the commercial software GENESIS Spectrum Registered-Sign for standardless quantification. The quantifications performed with the method proposed here are better in the 74% of the cases studied. In addition, the performance of the method proposed is compared with the first principles standardless analysis procedure DTSA for a different data set, which excludes trace elements. The relative deviations with respect to the nominal concentrations are lower than 0.04, 0.08 and 0.35 for the 66% of the cases for POEMA, GENESIS and DTSA, respectively. - Highlights: Black-Right-Pointing-Pointer A method for standardless quantification in EPMA is presented. Black-Right-Pointing-Pointer It gives better results than the commercial software GENESIS Spectrum. Black-Right-Pointing-Pointer It gives better results than the software DTSA. Black-Right-Pointing-Pointer It allows the determination of the conductive coating thickness. Black-Right-Pointing-Pointer It gives an estimation for the concentration uncertainties.

  15. Factors affecting the stability of chloroplast membranes in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Takaoki, T.; Torres-Pereira, J.; Packer, L.

    1974-01-01

    Factors which affect the stability of light-induced atebrin fluorescence quenching activity in chloroplast membranes, a measure of the electron transport dependent formation of energy-linked H/sup +/ gradients, were investigated in vitro. Class II spinach chloroplast membranes were isolated and stored at 0 to 4/sup 0/C and aliquots were subsequently tested for their retention of energizing capacity. The main factors which increase the stability of this activity were found to be (a) isolation in a potassium-containing medium but storage in a sucrose medium containing a low concentration of electrolytes; (b) the presence of butylated hydroxytoluene (an antioxidant), and a protein such as bovine serum albumin to remove free fatty acids in the medium during storage. Under these conditions, the energization capacity of chloroplasts is retained for more than 40 days.

  16. IM30 triggers membrane fusion in cyanobacteria and chloroplasts.

    Science.gov (United States)

    Hennig, Raoul; Heidrich, Jennifer; Saur, Michael; Schmüser, Lars; Roeters, Steven J; Hellmann, Nadja; Woutersen, Sander; Bonn, Mischa; Weidner, Tobias; Markl, Jürgen; Schneider, Dirk

    2015-01-01

    The thylakoid membrane of chloroplasts and cyanobacteria is a unique internal membrane system harbouring the complexes of the photosynthetic electron transfer chain. Despite their apparent importance, little is known about the biogenesis and maintenance of thylakoid membranes. Although membrane fusion events are essential for the formation of thylakoid membranes, proteins involved in membrane fusion have yet to be identified in photosynthetic cells or organelles. Here we show that IM30, a conserved chloroplast and cyanobacterial protein of approximately 30 kDa binds as an oligomeric ring in a well-defined geometry specifically to membranes containing anionic lipids. Triggered by Mg(2+), membrane binding causes destabilization and eventually results in membrane fusion. We propose that IM30 establishes contacts between internal membrane sites and promotes fusion to enable regulated exchange of proteins and/or lipids in cyanobacteria and chloroplasts. PMID:25952141

  17. An Optimized Thermal Analysis of Electronic Unit Used in Aircraft

    International Nuclear Information System (INIS)

    In a field where change and growth is inevitable, new electronic packaging problems continuously arise. Smaller, but more powerful devices are prone to overheating causing intermittent system failures, corrupted signals and outright system failure. Current study is focused on the analysis of the optimized working of electronic equipment from thermal point of view. In order to achieve the objective, an approach was developed for the thermal analysis of Printed Circuit Board (PCB) including the heat dissipation of its electronic components and then removal of the heat in a sophisticated manner by considering the conduction and convection modes of heat transfer. Mathematical modeling was carried out for a certain problem to address the thermal design, and then a program was developed in MATLAB for the solution of model by using Newton-Raphson method. The proposed unit is to be mounted on an aircraft having suspected thermal characteristics owing to abrupt changes in pressure and temperature as aircraft moves quickly from a lower altitude to higher altitude. In current study, dominant mode of heat transfer was conduction revealing that the major portion of heat transfer takes place by copper cladding and that heat conduction along the length of PCB can be improved enormously by using even thin layer of copper. The results confirmed that temperatures of all the electronic components were within derated values. Meanwhile, it was known that convection also plays a significant role in the reduction of temperatures of the components. The reduction in nodal temperature was in the range of 13 to 42 %. Furthermore, altitude variation from sea level to 15240 m (above sea level) caused the reduction in pressure from 1atm to 0.1095 atm. Consequently, the temperature of the electronic components increased from 73.25 degree C to 83.83 degree C for first node 'a', and from 66.04 degree C to 68.47 degree C for last node 'n' because of the decrease in the convective heat transfer

  18. Chloroplast Iron Transport Proteins - Function and Impact on Plant Physiology.

    Science.gov (United States)

    López-Millán, Ana F; Duy, Daniela; Philippar, Katrin

    2016-01-01

    Chloroplasts originated about three billion years ago by endosymbiosis of an ancestor of today's cyanobacteria with a mitochondria-containing host cell. During evolution chloroplasts of higher plants established as the site for photosynthesis and thus became the basis for all life dependent on oxygen and carbohydrate supply. To fulfill this task, plastid organelles are loaded with the transition metals iron, copper, and manganese, which due to their redox properties are essential for photosynthetic electron transport. In consequence, chloroplasts for example represent the iron-richest system in plant cells. However, improvement of oxygenic photosynthesis in turn required adaptation of metal transport and homeostasis since metal-catalyzed generation of reactive oxygen species (ROS) causes oxidative damage. This is most acute in chloroplasts, where radicals and transition metals are side by side and ROS-production is a usual feature of photosynthetic electron transport. Thus, on the one hand when bound by proteins, chloroplast-intrinsic metals are a prerequisite for photoautotrophic life, but on the other hand become toxic when present in their highly reactive, radical generating, free ionic forms. In consequence, transport, storage and cofactor-assembly of metal ions in plastids have to be tightly controlled and are crucial throughout plant growth and development. In the recent years, proteins for iron transport have been isolated from chloroplast envelope membranes. Here, we discuss their putative functions and impact on cellular metal homeostasis as well as photosynthetic performance and plant metabolism. We further consider the potential of proteomic analyses to identify new players in the field. PMID:27014281

  19. Treatment with antibiotics that interfere with peptidoglycan biosynthesis inhibits chloroplast division in the desmid Closterium.

    Directory of Open Access Journals (Sweden)

    Hiroko Matsumoto

    Full Text Available Charophytes is a green algal group closely related to land plants. We investigated the effects of antibiotics that interfere with peptidoglycan biosynthesis on chloroplast division in the desmid Closterium peracerosum-strigosum-littorale complex. To detect cells just after division, we used colchicine, which inhibits Closterium cell elongation after division. Although normal Closterium cells had two chloroplasts before and after cell division, cells treated with ampicillin, D-cycloserine, or fosfomycin had only one chloroplast after cell division, suggesting that the cells divided without chloroplast division. The antibiotics bacitracin and vancomycin showed no obvious effect. Electron microscopic observation showed that irregular-shaped chloroplasts existed in ampicillin-treated Closterium cells. Because antibiotic treatments resulted in the appearance of long cells with irregular chloroplasts and cell death, we counted cell types in the culture. The results suggested that cells with one chloroplast appeared first and then a huge chloroplast was generated that inhibited cell division, causing elongation followed by cell death.

  20. Gradient type optimization methods for electronic structure calculations

    CERN Document Server

    Zhang, Xin; Wen, Zaiwen; Zhou, Aihui

    2013-01-01

    The density functional theory (DFT) in electronic structure calculations can be formulated as either a nonlinear eigenvalue or direct minimization problem. The most widely used approach for solving the former is the so-called self-consistent field (SCF) iteration. A common observation is that the convergence of SCF is not clear theoretically while approaches with convergence guarantee for solving the latter are often not competitive to SCF numerically. In this paper, we study gradient type methods for solving the direct minimization problem by constructing new iterations along the gradient on the Stiefel manifold. Global convergence (i.e., convergence to a stationary point from any initial solution) as well as local convergence rate follows from the standard theory for optimization on manifold directly. A major computational advantage is that the computation of linear eigenvalue problems is no longer needed. The main costs of our approaches arise from the assembling of the total energy functional and its grad...

  1. Isolation of chloroplastic phosphoglycerate kinase

    Energy Technology Data Exchange (ETDEWEB)

    Macioszek, J.; Anderson, L.E. (Univ. of Illinois, Chicago (USA)); Anderson, J.B. (Pennsylvania State Univ., University Park (USA))

    1990-09-01

    We report here a method for the isolation of high specific activity phosphoglycerate kinase (EC 2.7.2.3) from chloroplasts. The enzyme has been purified over 200-fold from pea (Pisum sativum L.) stromal extracts to apparent homogeneity with 23% recovery. Negative cooperativity is observed with the two enzyme phosphoglycerate kinase/glyceraldehyde-3-P dehydrogenase (EC 1.2.1.13) couple restored from the purified enzymes when NADPH is the reducing pyridine nucleotide, consistent with earlier results obtained with crude chloroplastic extracts. Michaelis Menten kinetics are observed when 3-phosphoglycerate is held constant and phosphoglycerate kinase is varied, which suggests that phosphoglycerate kinase-bound 1,3-bisphosphoglycerate may be the preferred substrate for glyceraldehyde-3-P dehydrogenase in the chloroplast.

  2. Biosynthesis of starch in chloroplasts.

    Science.gov (United States)

    Nomura, T; Nakayama, N; Murata, T; Akazawa, T

    1967-03-01

    The enzymic synthesis of ADP-glucose and UDP-glucose by chloroplastic pyrophosphorylase of bean and rice leaves has been demonstrated by paper chromatographic techniques. In both tissues, the activity of UDP-glucose-pyrophosphorylase was much higher than ADP-glucose-pyrophosphorylase. Glycerate-3-phosphate, phosphoenolpyruvate and fructose-1,6-diphosphate did not stimulate ADP-glucose formation by a pyrophosphorylation reaction. The major metabolic pathway for UDP-glucose utilization appears to be the synthesis of either sucrose or sucrose-P. On the other hand, a specific precursor role of ADP-glucose for synthesizing chloroplast starch by the ADP-glucose-starch transglucosylase reaction is supported by the coupled enzyme system of ADP-glucose-pyrophosphorylase and transglucosylase, isolated from chloroplasts. None of the glycolytic intermediates stimulated the glucose transfer in the enzyme sequence of reaction system employed. PMID:4292567

  3. Regulation of electron transport in C(3) plant chloroplasts in situ and in silico: short-term effects of atmospheric CO(2) and O(2).

    Science.gov (United States)

    Kuvykin, Ilya V; Ptushenko, Vasily V; Vershubskii, Alexey V; Tikhonov, Alexander N

    2011-03-01

    In this work, we have investigated the effects of atmospheric CO(2) and O(2) on induction events in Hibiscus rosa-sinensis leaves. These effects manifest themselves as multiphase kinetics of P(700) redox transitions and non-monotonous changes in chlorophyll fluorescence. Depletion of CO(2) and O(2) in air causes a decrease in linear electron flux (LEF) and dramatic lowering of P(700)(+) level. This is explained by the impediment to electron efflux from photosystem 1 (PS1) at low acceptor capacity. With the release of the acceptor deficit, the rate of LEF significantly increases. We have found that oxygen promotes the outflow of electrons from PS1, providing the rise of P(700)(+) level. The effect of oxygen as an alternative electron acceptor becomes apparent at low and ambient concentrations of atmospheric CO(2) frames of our mathematical model. The model describes the reciprocal changes in LEF and NPQ and predicts the redistribution of electron fluxes on the acceptor side of PS1. In particular, the contribution of cyclic electron flow around PS1 (CEF1) and water-water cycle gradually decays during the induction phase. This result is consistent with experimental data indicating that under the steady-state conditions the contribution of CEF1 to photosynthetic electron transport in Hibiscus rosa-sinensis is insignificant (< or = 10%). PMID:21195049

  4. Increased sensitivity of photosynthesis to antimycin A induced by inactivation of the chloroplast ndhB gene. Evidence for a participation of the NADH-dehydrogenase complex to cyclic electron flow around photosystem I.

    Science.gov (United States)

    Joët, T; Cournac, L; Horvath, E M; Medgyesy, P; Peltier, G

    2001-04-01

    Tobacco (Nicotiana tabacum var Petit Havana) ndhB-inactivated mutants (ndhB-) obtained by plastid transformation (E.M. Horvath, S.O. Peter, T. Joët, D. Rumeau, L. Cournac, G.V. Horvath, T.A. Kavanagh, C. Schäfer, G. Peltier, P. MedgyesyHorvath [2000] Plant Physiol 123: 1337-1350) were used to study the role of the NADH-dehydrogenase complex (NDH) during photosynthesis and particularly the involvement of this complex in cyclic electron flow around photosystem I (PSI). Photosynthetic activity was determined on leaf discs by measuring CO2 exchange and chlorophyll fluorescence quenchings during a dark-to-light transition. In the absence of treatment, both non-photochemical and photochemical fluorescence quenchings were similar in ndhB- and wild type (WT). When leaf discs were treated with 5 microM antimycin A, an inhibitor of cyclic electron flow around PSI, both quenchings were strongly affected. At steady state, maximum photosynthetic electron transport activity was inhibited by 20% in WT and by 50% in ndhB-. Under non-photorespiratory conditions (2% O2, 2,500 microL x L(-1) CO2), antimycin A had no effect on photosynthetic activity of WT, whereas a 30% inhibition was observed both on quantum yield of photosynthesis assayed by chlorophyll fluorescence and on CO2 assimilation in ndhB-. The effect of antimycin A on ndhB- could not be mimicked by myxothiazol, an inhibitor of the mitochondrial cytochrome bc1 complex, therefore showing that it is not related to an inhibition of the mitochondrial electron transport chain but rather to an inhibition of cyclic electron flow around PSI. We conclude to the existence of two different pathways of cyclic electron flow operating around PSI in higher plant chloroplasts. One of these pathways, sensitive to antimycin A, probably involves ferredoxin plastoquinone reductase, whereas the other involves the NDH complex. The absence of visible phenotype in ndhB- plants under normal conditions is explained by the complement of these two

  5. Topology Optimization of an Actively Cooled Electronics Section for Downhole Tools

    DEFF Research Database (Denmark)

    Soprani, Stefano; Klaas Haertel, Jan Hendrik; Lazarov, Boyan Stefanov;

    2015-01-01

    downhole electronics unit proved to be challenging, because of the space constraints and the proximity of the cooling zone (electronics) to the heat sink (well fluid). The topology optimization approach was therefore chosen to optimize the thermal design of the actively cooled electronics section and the...

  6. An optimized nanoparticle separator enabled by electron beam induced deposition

    International Nuclear Information System (INIS)

    Size-based separations technologies will inevitably benefit from advances in nanotechnology. Direct-write nanofabrication provides a useful mechanism for depositing/etching nanoscale elements in environments otherwise inaccessible to conventional nanofabrication techniques. Here, electron beam induced deposition was used to deposit an array of nanoscale features in a 3D environment with minimal material proximity effects outside the beam-interaction region. Specifically, the membrane component of a nanoparticle separator was fabricated by depositing a linear array of sharply tipped nanopillars, with a singular pitch, designed for sub-50 nm nanoparticle permeability. The nanopillar membrane was used in a dual capacity to control the flow of nanoparticles in the transaxial direction of the array while facilitating the sealing of the cellular-sized compartment in the paraxial direction. An optimized growth recipe resulted which (1) maximized the growth efficiency of the membrane (which minimizes proximity effects) and (2) preserved the fidelity of the spacing between nanopillars (which maximizes the size-based gating quality of the membrane) while (3) maintaining sharp nanopillar apexes for impaling an optically transparent polymeric lid critical for device sealing.

  7. The novel protein DELAYED PALE-GREENING1 is required for early chloroplast biogenesis in Arabidopsis thaliana.

    Science.gov (United States)

    Liu, Dong; Li, Weichun; Cheng, Jianfeng

    2016-01-01

    Chloroplast biogenesis is one of the most important subjects in plant biology. In this study, an Arabidopsis early chloroplast biogenesis mutant with a delayed pale-greening phenotype (dpg1) was isolated from a T-DNA insertion mutant collection. Both cotyledons and true leaves of dpg1 mutants were initially albino but gradually became pale green as the plant matured. Transmission electron microscopic observations revealed that the mutant displayed a delayed proplastid-to-chloroplast transition. Sequence and transcription analyses showed that AtDPG1 encodes a putatively chloroplast-localized protein containing three predicted transmembrane helices and that its expression depends on both light and developmental status. GUS staining for AtDPG1::GUS transgenic lines showed that this gene was widely expressed throughout the plant and that higher expression levels were predominantly found in green tissues during the early stages of Arabidopsis seedling development. Furthermore, quantitative real-time RT-PCR analyses revealed that a number of chloroplast- and nuclear-encoded genes involved in chlorophyll biosynthesis, photosynthesis and chloroplast development were substantially down-regulated in the dpg1 mutant. These data indicate that AtDPG1 plays an essential role in early chloroplast biogenesis, and its absence triggers chloroplast-to-nucleus retrograde signalling, which ultimately down-regulates the expression of nuclear genes encoding chloroplast-localized proteins. PMID:27160321

  8. Comparative studies on codon usage pattern of chloroplasts and their host nuclear genes in four plant species

    Indian Academy of Sciences (India)

    Qingpo Liu; Qingzhong Xue

    2005-04-01

    A detailed comparison was made of codon usage of chloroplast genes with their host (nuclear) genes in the four angiosperm species Oryza sativa, Zea mays, Triticum aestivum and Arabidopsis thaliana. The average GC content of the entire genes, and at the three codon positions individually, was higher in nuclear than in chloroplast genes, suggesting different genomic organization and mutation pressures in nuclear and chloroplast genes. The results of Nc-plots and neutrality plots suggested that nucleotide compositional constraint had a large contribution to codon usage bias of nuclear genes in O. sativa, Z. mays, and T. aestivum, whereas natural selection was likely to be playing a large role in codon usage bias in chloroplast genomes. Correspondence analysis and chi-test showed that regardless of the genomic environment (species) of the host, the codon usage pattern of chloroplast genes differed from nuclear genes of their host species by their AU-richness. All the chloroplast genomes have predominantly A- and/or U-ending codons, whereas nuclear genomes have G-, C- or U-ending codons as their optimal codons. These findings suggest that the chloroplast genome might display particular characteristics of codon usage that are different from its host nuclear genome. However, one feature common to both chloroplast and nuclear genomes in this study was that pyrimidines were found more frequently than purines at the synonymous codon position of optimal codons.

  9. Response of Chloroplast NAD(P)H Dehydrogenase-Mediated Cyclic Electron Flow to a Shortage or Lack in Ferredoxin-Quinone Oxidoreductase-Dependent Pathway in Rice Following Short-Term Heat Stress.

    Science.gov (United States)

    Essemine, Jemaa; Qu, Mingnan; Mi, Hualing; Zhu, Xin-Guang

    2016-01-01

    Cyclic electron flow (CEF) around photosystem I (PSI) can protect photosynthetic electron carriers under conditions of stromal over-reduction. The goal of the research reported in this paper was to investigate the responses of both PSI and photosystem II (PSII) to a short-term heat stress in two rice lines with different capacities of cyclic electron transfer, i.e., Q4149 with a high capacity (hcef) and C4023 with a low capacity (lcef). The absorbance change at 820 nm (ΔA820) was used here to assess the charge separation in the PSI reaction center (P700). The results obtained show that short-term heat stress abolishes the ferredoxin-quinone oxidoreductase (FQR)-dependent CEF in rice and accelerates the initial rate of P700 (+) re-reduction. The P700 (+) amplitude was slightly increased at a moderate heat-stress (35°C) because of a partial restriction of FQR but it was decreased following high heat-stress (42°C). Assessment of PSI and PSII activities shows that PSI is more susceptible to heat stress than PSII. Under high temperature, FQR-dependent CEF was completely removed and NDH-dependent CEF was up-regulated and strengthened to a higher extent in C4023 than in Q4149. Specifically, under normal growth temperature, hcef (Q4149) was characterized by higher FQR- and chloroplast NAD(P)H dehydrogenase (NDH)-dependent CEF rates than lcef (C4023). Following thermal stress, the activation of NDH-pathway was 130 and 10% for C4023 and Q4149, respectively. Thus, the NDH-dependent CEF may constitute the second layer of plant protection and defense against heat stress after the main route, i.e., FQR-dependent CEF, reaches its capacity. We discuss the possibility that under high heat stress, the NDH pathway serves as a safety valve to dissipate excess energy by cyclic photophosphorylation and overcome the stroma over-reduction following inhibition of CO2 assimilation and any shortage or lack in the FQR pathway. The potential role of the NDH-dependent pathway during the

  10. Formation of putative chloroplast cytochromes in isolated developing pea chloroplasts

    International Nuclear Information System (INIS)

    In addition to chlorophyll-protein complexes, other proteins were labeled when isolated developing pea chloroplasts were incubated with [14C]-5-aminolevulinic acid [14C]-ALA. The major labeled band (M/sub r/ = 43 kDa by LDS-PAGE) was labeled even in the presence of chloramphenicol. Heme-dependent peroxidase activity (as detected by the tetramethyl benzidine-H2O2 stain) was not visibly associated with this band. The radioactive band was stable to heat, 5% HCl in acetone, and was absent if the incubation with [14C]-5-aminolevulinic acid was carried out in the presence of N-methyl protoporphyrin IX dimethyl ester (a specific inhibitor of ferrochelatase). Organic solvent extraction procedures for the enrichment of cytochrome f from chloroplast membranes also extracted this unknown labeled product. It was concluded that this labeled product was probably a c-type cytochrome. The effect of exogenous iron, iron chelators, gabaculine (an inhibitor of ALA synthesis) and other incubation conditions upon the in vitro formation of putative chloroplast cytochromes will be discussed

  11. Protein methylation in pea chloroplasts

    International Nuclear Information System (INIS)

    The methylation of chloroplast proteins has been investigated by incubating intact pea (Pisum sativum) chloroplasts with [3H-methyl]-S-adenosylmethionine. Incubation in the light increases the amount of methylation in both the thylakoid and stromal fractions. Numerous thylakoid proteins serve as substrates for the methyltransfer reactions. Three of these thylakoid proteins are methylated to a significantly greater extent in the light than in the dark. The primary stromal polypeptide methylated is the large subunit of ribulose bisphosphate carboxylase/oxygenase. One other stromal polypeptide is also methylated much more in the light than in the dark. Two distinct types of protein methylation occur. One methylinkage is stable to basic conditions whereas a second type is base labile. The base-stable linkage is indicative of N-methylation of amino acid residues while base-lability is suggestive of carboxymethylation of amino acid residues. Labeling in the light increases the percentage of methylation that is base labile in the thylakoid fraction while no difference is observed in the amount of base-labile methylations in light-labeled and dark-labeled stromal proteins. Also suggestive of carboxymethylation is the detection of volatile [3H]methyl radioactivity which increases during the labeling period and is greater in chloroplasts labeled in the light as opposed to being labeled in the dark; this implies in vivo turnover of the [3H]methyl group

  12. Endosymbiotic origin and codon bias of the nuclear gene for chloroplast glyceraldehyde-3-phosphate dehydrogenase from maize.

    Science.gov (United States)

    Brinkmann, H; Martinez, P; Quigley, F; Martin, W; Cerff, R

    1987-01-01

    The nuclei of plant cells harbor genes for two types of glyceraldehyde-3-phosphate dehydrogenases (GAPDH) displaying a sequence divergence corresponding to the prokaryote/eukaryote separation. This strongly supports the endosymbiotic theory of chloroplast evolution and in particular the gene transfer hypothesis suggesting that the gene for the chloroplast enzyme, initially located in the genome of the endosymbiotic chloroplast progenitor, was transferred during the course of evolution into the nuclear genome of the endosymbiotic host. Codon usage in the gene for chloroplast GAPDH of maize is radically different from that employed by present-day chloroplasts and from that of the cytosolic (glycolytic) enzyme from the same cell. This reveals the presence of subcellular selective pressures which appear to be involved in the optimization of gene expression in the economically important graminaceous monocots. PMID:3131533

  13. The global optimization design for electron emission system using genetic algorithms

    International Nuclear Information System (INIS)

    The general optimization design method, such as Simplex method and Powell method, etc., can determine the final optimum structure and electric parameters of an electron optical system from given electron optical properties, but it may land in a local minimum of the optimum search process. The Genetic Algorithms (GAs) is a novel direct search optimization method based on principles of natural selection and 'survival of the fittest' from natural evolution. Through the 'reproduction', 'crossover' and 'mutation' iterative process, GAs can search the global optimum result. In this paper, we applied the GAs to optimize an electron emission system, a 'triode' structure used in a projection display with high resolution and brightness. The optimal structure and corresponding electrical parameters with a criterion of minimum objective function value, crossover radius, have been searched and presented in this paper. The GAs, as a direct search method and an adaptive search technique, has significant advantage in the optimization design of electron optical systems

  14. Optimal Electron Energies for Driving Chromospheric Evaporation in Solar Flares

    CERN Document Server

    Reep, Jeffrey; Alexander, David

    2015-01-01

    In the standard model of solar flares, energy deposition by a beam of electrons drives strong chromospheric evaporation leading to a significantly denser corona and much brighter emission across the spectrum. Chromospheric evaporation was examined in great detail by Fisher, Canfield, & McClymont (1985a,b,c), who described a distinction between two different regimes, termed explosive and gentle evaporation. In this work, we examine the importance of electron energy and stopping depths on the two regimes and on the atmospheric response. We find that with explosive evaporation, the atmospheric response does not depend strongly on electron energy. In the case of gentle evaporation, lower energy electrons are significantly more efficient at heating the atmosphere and driving up-flows sooner than higher energy electrons. We also find that the threshold between explosive and gentle evaporation is not fixed at a given beam energy flux, but also depends strongly on the electron energy and duration of heating. Furt...

  15. Optimization of Plasmon Decay Through Scattering and Hot Electron Transfer

    Science.gov (United States)

    DeJarnette, Drew

    Light incident on metal nanoparticles induce localized surface oscillations of conductive electrons, called plasmons, which is a means to control and manipulate light. Excited plasmons decay as either thermal energy as absorbed phonons or electromagnetic energy as scattered photons. An additional decay pathway for plasmons can exist for gold nanoparticles situated on graphene. Excited plasmons can decay directly to the graphene as through hot electron transfer. This dissertation begins by computational analysis of plasmon resonance energy and bandwidth as a function of particle size, shape, and dielectric environment in addition to diffractive coupled in lattices creating a Fano resonance. With this knowledge, plasmon resonance was probed with incident electrons using electron energy loss spectroscopy in a transmission electron microscope. Nanoparticles were fabricated using electron beam lithography on 50 nanometer thick silicon nitride with some particles fabricated with a graphene layer between the silicon nitride and metal structure. Plasmon resonance was compared between ellipses on and off graphene to characterize hot electron transfer as a means of plasmon decay. It was observed that the presence of graphene caused plasmon energy to decrease by as much as 9.8% and bandwidth to increase by 25%. Assuming the increased bandwidth was solely from electron transfer as an additional plasmon decay route, a 20% efficiency of plasmon decay to graphene was calculated for the particular ellipses analyzed.

  16. Simulation and Optimization of a Carbon Nanotube Electron Source

    Czech Academy of Sciences Publication Activity Database

    Knápek, Alexandr; Radlička, Tomáš; Krátký, Stanislav

    2015-01-01

    Roč. 21, S4 (2015), s. 60-65. ISSN 1431-9276 R&D Projects: GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : carbon nanotube * electron beam lithography Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.877, year: 2014

  17. Chloroplasts as functional organelles in animal tissues.

    Science.gov (United States)

    Trench, R K; Greene, R W; Bystrom, B G

    1969-08-01

    The marine gastropod molluscs Tridachia crispata, Tridachiella diomedea, and Placobranchus ianthobapsus (Sacoglossa, Opisthobranchia) possess free functional chloroplasts within the cells of the digestive diverticula, as determined by observations on ultrastructure, pigment analyses, and experiments on photosynthetic capacity. In the light, the chloroplasts incorporate H(14)CO(3) (-)in situ. Reduced radiocarbon is translocated to various chloroplast-free tissues in the animals. The slugs feed on siphonaceous algae from which the chloroplasts are derived. Pigments from the slugs and from known siphonaceous algae, when separated chromatographically and compared, showed similar components. Absorption spectra of extracts of slugs and algae were very similar. The larvae of the slugs are pigment-free up to the post-veliger stage, suggesting that chloroplasts are acquired de novo. with each new generation. PMID:5792329

  18. The development of optimal magnet systems for electronic and laser applications

    International Nuclear Information System (INIS)

    A general method of synthesis of optimal magnet systems (MS) from hard magnets is developed. The method permits to determine the optimal distribution of magnetization in MS, the optimal form and minimum volume of MS. The mathematical problem is reduced to the extremum search under constant volume. A method of optimization of MS contained permanent magnets and soft magnetic elements is also suggested. Using the developed method MS with optimal mass and size characteristics for laser applications and microwave electronics have been produced. (author)

  19. Exploring the optimal performances of irreversible single resonance energy selective electron refrigerators

    Science.gov (United States)

    Zhou, Junle; Chen, Lingen; Ding, Zemin; Sun, Fengrui

    2016-05-01

    Applying finite-time thermodynamics (FTT) and electronic transport theory, the optimal performances of irreversible single resonance energy selective electron (ESE) refrigerator are analyzed. The effects of heat leakage between two electron reservoirs on optimal performances are discussed. The influences of system operating parameters on cooling load, coefficient of performance (COP), figure of merit and ecological function are demonstrated using numerical examples. Comparative performance analyses among different objective functions show that performance characteristics at maximum ecological function and maximum figure of merit are of great practical significance. Combining the two optimization objectives of maximum ecological function and maximum figure of merit together, more specific optimal ranges of cooling load and COP are obtained. The results can provide some advices to the design of practical electronic machine systems.

  20. Optimal Allocation of Power-Electronic Interfaced Wind Turbines Using a Genetic Algorithm - Monte Carlo Hybrid Optimization Method

    DEFF Research Database (Denmark)

    Chen, Peiyuan; Siano, Pierluigi; Chen, Zhe; Bak-Jensen, Birgitte

    The increasing amount of wind power integrated to power systems presents a number of challenges to the system operation. One issue related to wind power integration concerns the location and capacities of the wind turbines (WTs) in the network. Although the location of wind turbines is mainly...... determined by the wind resource and geographic conditions, the location of wind turbines in a power system network may significantly affect the distribution of power flow, power losses, etc. Furthermore, modern WTs with power-electronic interface have the capability of controlling reactive power output...... limit requirements. The method combines the Genetic Algorithm (GA), gradient-based constrained nonlinear optimization algorithm and sequential Monte Carlo simulation (MCS). The GA searches for the optimal locations and capacities of WTs. The gradient-based optimization finds the optimal power factor...

  1. Chloroplast Retrograde Regulation of Heat Stress Responses in Plants.

    Science.gov (United States)

    Sun, Ai-Zhen; Guo, Fang-Qing

    2016-01-01

    It is well known that intracellular signaling from chloroplast to nucleus plays a vital role in stress responses to survive environmental perturbations. The chloroplasts were proposed as sensors to heat stress since components of the photosynthetic apparatus housed in the chloroplast are the major targets of thermal damage in plants. Thus, communicating subcellular perturbations to the nucleus is critical during exposure to extreme environmental conditions such as heat stress. By coordinating expression of stress specific nuclear genes essential for adaptive responses to hostile environment, plants optimize different cell functions and activate acclimation responses through retrograde signaling pathways. The efficient communication between plastids and the nucleus is highly required for such diverse metabolic and biosynthetic functions during adaptation processes to environmental stresses. In recent years, several putative retrograde signals released from plastids that regulate nuclear genes have been identified and signaling pathways have been proposed. In this review, we provide an update on retrograde signals derived from tetrapyrroles, carotenoids, reactive oxygen species (ROS) and organellar gene expression (OGE) in the context of heat stress responses and address their roles in retrograde regulation of heat-responsive gene expression, systemic acquired acclimation, and cellular coordination in plants. PMID:27066042

  2. Nitrogen control of chloroplast differentiation. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, G.W.

    1998-05-01

    This project was directed toward understanding at the physiological, biochemical and molecular levels of how photosynthetic organisms adapt to long-term nitrogen-deficiency conditions is quite incomplete even though limitation of this nutrient is the most commonly restricts plant growth and development. For our work on this problem, the unicellular green alga, Chlamydomonas reinhardtii, was grown in continuous cultures in which steady-state levels of nitrogen can be precisely controlled. N-limited cells exhibit the classical symptoms of deficiency of this nutrient, chlorosis and slow growth rates, and respond to nitrogen provision by rapid greening and chloroplast differentiation. We have addressed three aspects of this problem: (1) the regulation of pigment synthesis; (2) control of expression of nuclear genes encoding photosynthetic proteins; (3) changes in metabolic and electron transport pathways that enable sustained CO{sub 2} fixation even though they cannot be readily converted into amino and nucleic acids. For the last, principle components are: (a) enhanced mitochondrial respiratory activity intimately associated with photosynthates, and (b) the occurrence in thylakoids of a supplemental electron transport pathway that facilitates reduction of the plastoquinone pool. Together, these distinguishing features of N-limited cells are likely to enable cell survival, especially under conditions of high irradiance stress.

  3. Evaluation and optimization of electron capture dissociation efficiency in fourier transform ion cyclotron resonance mass spectrometry.

    Science.gov (United States)

    McFarland, Melinda A; Chalmers, Michael J; Quinn, John P; Hendrickson, Christopher L; Marshall, Alan G

    2005-07-01

    Electron capture dissociation (ECD) efficiency has typically been lower than for other dissociation techniques. Here we characterize experimental factors that limit ECD and seek to improve its efficiency. Efficiency of precursor to product ion conversion was measured for a range of peptide (approximately 15% efficiency) and protein (approximately 33% efficiency) ions of differing sizes and charge states. Conversion of precursor ions to products depends on electron irradiation period and maximizes at approximately 5-30 ms. The optimal irradiation period scales inversely with charge state. We demonstrate that reflection of electrons through the ICR cell is more efficient and robust than a single pass, because electrons can cool to the optimal energy for capture, which allows for a wide range of initial electron energy. Further, efficient ECD with reflected electrons requires only a short (approximately 500 micros) irradiation period followed by an appropriate delay for cooling and interaction. Reflection of the electron beam results in electrons trapped in or near the ICR cell and thus requires a brief (approximately 50 micros) purge for successful mass spectral acquisition. Further electron irradiation of refractory precursor ions did not result in further dissociation. Possibly the ion cloud and electron beam are misaligned radially, or the electron beam diameter may be smaller than that of the ion cloud such that remaining precursor ions do not overlap with the electron beam. Several ion manipulation techniques and use of a large, movable dispenser cathode reduce the possibility that misalignment of the ion and electron beams limits ECD efficiency. PMID:15914017

  4. Chloroplast ultrastructure in leaves of Cucumis sativus chlorophyll mutant

    Directory of Open Access Journals (Sweden)

    Irena Palczewska

    2014-02-01

    Full Text Available The developing and young leaves of Cucumis sativus chlorophyll mutants are yellow, when mature they become green and do not differ in their colour from those of control plants. The mesophyll of yellow leaves contains a diversiform plastid population with a varying degree of defectiveness, which is mainly manifested in the reduction or disorganization of the typical thylakoid system. DNA areas, ribosome-like particles and aggregates of electron-dense material are preserved in the stroma of mutated plastids. Starch grains are deficient. Apart from mutated plastids, chloroplasts with a normal structure, as in control plants, were also observed.The leaf greening process is accompanied by a reconstruction and rearrangement of the inner chloroplast lamellar system and an ability to accumulate starch. However, in the mutant chloroplasts as compared with control-plant ones, an irregular arrangement of grana and reduced number of inter-grana thylakoids can be seen. An osmiophilic substance stored in the stroma of mutated plastids and the vesicles formed from an internal plastid membrane take part in restoration of the membrane system.

  5. Biosynthesis of gold nanoparticles using chloroplasts

    Directory of Open Access Journals (Sweden)

    Zhang YX

    2011-11-01

    Full Text Available Yi Xia Zhang1, Jun Zheng2, Guo Gao1, Yi Fei Kong1, Xiao Zhi1, Kan Wang1, Xue Qing Zhang1, Da Xiang Cui11Department of Bio-Nano-Science and Engineering, National Key Laboratory of Nano/Micro Fabrication Technology, Key Laboratory for Thin Film and Microfabrication of Ministry of Education, Institute of Micro-Nano Science and Technology, Shanghai Jiao Tong University, Shanghai, 2Wheat Research Institute, Academy of Agricultural Sciences, Linfen, Shan Xi, People's Republic of ChinaAbstract: In this paper, a new method of one-pot biosynthesizing of gold nanoparticles (GNPs, using chloroplasts as reductants and stabilizers is reported. The as-prepared GNPs were characterized by ultraviolet visible spectroscopy, transmission electron microscopy, X-ray powder diffraction, and Fourier transform infrared spectroscopy (FTIR. The cytotoxicity of the GNPs was evaluated using the 3-(4,5-Dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT method against gastric mucous cell line GES-1 and gastric cancer cell line MGC-803. Rhodamine 6G as a Raman probe was used for investigating surface-enhanced Raman spectroscopy (SERS enhancement of GNPs. The transmission electron microscopy results indicated that the GNPs were spherical in structure and almost 20 nm in diameter. Ultraviolet visible spectroscopy exhibited an absorption peak at 545 nm. The GNPs exhibited high crystallinity, with the (111 plane as the predominant orientation, clarified by X-ray powder diffraction. In addition, a potential mechanism was proposed to interpret the formation process of GNPs, mainly based on the analysis of FTIR results. The FTIR spectrum confirmed that the GNPs were carried with N–H groups. Toxicological assays of as-prepared GNPs revealed that the green GNPs were nontoxic. SERS analysis revealed that the GNPs without any treatment could substantially enhance the Raman signals of rhodamine 6G. The Raman enhancement factor was calculated to be nearly 1010 orders of magnitude

  6. Chloroplast protein targeting involves localized translation in Chlamydomonas

    OpenAIRE

    Uniacke, James; Zerges, William

    2009-01-01

    The compartmentalization of eukaryotic cells requires that newly synthesized proteins be targeted to the compartments in which they function. In chloroplasts, a few thousand proteins function in photosynthesis, expression of the chloroplast genome, and other processes. Most chloroplast proteins are synthesized in the cytoplasm, imported, and then targeted to a specific chloroplast compartment. The remainder are encoded by the chloroplast genome, synthesized within the organelle, and targeted ...

  7. The structure of cell chloroplasts of spring cereals

    OpenAIRE

    Vladislav V. Zhuk; Mykola M. Musyenko

    2012-01-01

    It is shown that in wheat chloroplasts thylakoids are localized on the periphery and in the central part are strong starch grains. In the chloroplasts of barley found small stack of thylakoids. Unlike wheat, the number of starch grains in chloroplasts of barley is more, but they are smaller. Oat chloroplasts were significantly smaller than the other studied cereals. Thus, cell chloroplasts of leaves of wheat, barley and oats differed significantly in size and structure, but had have clearly o...

  8. The complexity of chloroplast chaperonins.

    Science.gov (United States)

    Vitlin Gruber, Anna; Nisemblat, Shahar; Azem, Abdussalam; Weiss, Celeste

    2013-12-01

    Type I chaperonins are large oligomeric protein ensembles that are involved in the folding and assembly of other proteins. Chloroplast chaperonins and co-chaperonins exist in multiple copies of two distinct isoforms that can combine to form a range of labile oligomeric structures. This complex system increases the potential number of chaperonin substrates and possibilities for regulation. The incorporation of unique subunits into the oligomer can modify substrate specificity. Some subunits are upregulated in response to heat shock and some show organ-specific expression, whereas others possess additional functions that are unrelated to their role in protein folding. Accumulating evidence suggests that specific subunits have distinct roles in biogenesis of ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco). PMID:24035661

  9. CURE-Chloroplast: A chloroplast C-to-U RNA editing predictor for seed plants

    Directory of Open Access Journals (Sweden)

    Li Yanda

    2009-05-01

    Full Text Available Abstract Background RNA editing is a type of post-transcriptional modification of RNA and belongs to the class of mechanisms that contribute to the complexity of transcriptomes. C-to-U RNA editing is commonly observed in plant mitochondria and chloroplasts. The in vivo mechanism of recognizing C-to-U RNA editing sites is still unknown. In recent years, many efforts have been made to computationally predict C-to-U RNA editing sites in the mitochondria of seed plants, but there is still no algorithm available for C-to-U RNA editing site prediction in the chloroplasts of seed plants. Results In this paper, we extend our algorithm CURE, which can accurately predict the C-to-U RNA editing sites in mitochondria, to predict C-to-U RNA editing sites in the chloroplasts of seed plants. The algorithm achieves over 80% sensitivity and over 99% specificity. We implement the algorithm as an online service called CURE-Chloroplast http://bioinfo.au.tsinghua.edu.cn/pure. Conclusion CURE-Chloroplast is an online service for predicting the C-to-U RNA editing sites in the chloroplasts of seed plants. The online service allows the processing of entire chloroplast genome sequences. Since CURE-Chloroplast performs very well, it could be a helpful tool in the study of C-to-U RNA editing in the chloroplasts of seed plants.

  10. A Model for Optimizing Electronic Toll Collection Systems

    OpenAIRE

    David Levinson; Elva Chang

    2003-01-01

    This paper examines the deployment of electronic toll collection (ETC) and develops a model to maximize social welfare associated with a toll plaza. A payment choice model estimates the share of traffic using ETC as a function of delay, price, and a fixed cost of acquiring the in-vehicle transponder. Delay in turn depends on the relative number of ETC and Manual Collection Lanes. Price depends on the discount given to users of the ETC Lanes. The fixed cost of acquiring the transponder (not si...

  11. A comparison of rice chloroplast genomes

    DEFF Research Database (Denmark)

    Tang, Jiabin; Xia, Hong'ai; Cao, Mengliang; Zhang, Xiuqing; Zeng, Wanyong; Hu, Songnian; Tong, Wei; Wang, Jun; Wang, Jian; Yu, Jun; Yang, Huanming; Zhu, Lihuang

    2004-01-01

    ), which are both parental varieties of the super-hybrid rice, LYP9. Based on the patterns of high sequence coverage, we partitioned chloroplast sequence variations into two classes, intravarietal and intersubspecific polymorphisms. Intravarietal polymorphisms refer to variations within 93-11 or PA64S...... intersubspecific polymorphisms. In our study, we found that the intersubspecific variations of 93-11 (indica) and PA64S (japonica) chloroplast genomes consisted of 72 single nucleotide polymorphisms and 27 insertions or deletions. The intersubspecific polymorphism rates between 93-11 and PA64S were 0.05% for...... single nucleotide polymorphisms and 0.02% for insertions or deletions, nearly 8 and 10 times lower than their respective nuclear genomes. Based on the total number of nucleotide substitutions between the two chloroplast genomes, we dated the divergence of indica and japonica chloroplast genomes as...

  12. Chloroplast genes are expressed during intracellular symbiotic association of Vaucheria litorea plastids with the sea slug Elysia chlorotica.

    OpenAIRE

    Mujer, C V; Andrews, D L; Manhart, J R; Pierce, S K; Rumpho, M E

    1996-01-01

    The marine slug Elysia chlorotica (Gould) forms an intracellular symbiosis with photosynthetically active chloroplasts from the chromophytic alga Vaucheria litorea (C. Agardh). This symbiotic association was characterized over a period of 8 months during which E. chlorotica was deprived of V. litorea but provided with light and CO2. The fine structure of the symbiotic chloroplasts remained intact in E. chlorotica even after 8 months of starvation as revealed by electron microscopy. Southern b...

  13. Inheritance of chloroplast DNA in Chlamydomonas reinhardtii

    OpenAIRE

    Grant, David M; Nicholas W. Gillham; Boynton, John E.

    1980-01-01

    Two symmetrically located deletions of approximately 100 base pairs each have been identified in chloroplast DNA of Chlamydomonas reinhardtii. Although present in a mutant strain that requires acetate for growth, both deletions have been shown to be distinct from the nonphotosynthetic phenotype of this strain. These physical markers in the chloroplast genome and maternally inherited genetic markers showed strict cotransmission in reciprocal crosses. Thus, our results are consistent with the l...

  14. Fatty acid synthesis by spinach chloroplasts, 3

    International Nuclear Information System (INIS)

    The modes of actions of photosynthetic inhibitors on photosynthesis and fatty acid synthesis were examined. DCMU, an electron transport inhibitor, inhibited fatty acid synthesis and photophosphorylation to the same extent, suggesting dependence of fatty acid synthesis on photosynthesis. The same was also the case with FCCP, a photophosphorylation uncoupler. In contrast, NH4Cl and phlorizin at concentrations completely suppressing ATP formation, only partially inhibited the fatty acid synthesis. These facts suggest that a certain level of high-energy intermediate (state) is responsible for the light enhancement of fatty acid synthesis. This idea is further supported by the fact that the partial inhibition of fatty acid synthesis by NH4Cl was relieved by addition of DCCD at low concentrations suppressing the ATP formation but not completely destroying the high energy intermediate. The lag period in the initial period of fatty acid synthesis was shortened by preillumination of chloroplasts, even in the absence of ADP. This indicates that the light dependent fatty acid synthesis is closely associated with the high-energy intermediate (state), but not directly with ATP formation by photophosphorylation. (author)

  15. Export of carbon from chloroplasts at night

    Energy Technology Data Exchange (ETDEWEB)

    Schleucher, J.; Vanderveer, P.J.; Sharkey, T.D. [Univ. of Wisconsin, Madison, WI (United States)

    1998-12-01

    Hexose export from chloroplasts at night has been inferred in previous studies of mutant and transgenic plants. The authors have tested whether hexose export is the normal route of carbon export from chloroplasts at night. The authors used nuclear magnetic resonance to distinguish glucose (Glc) made from hexose export and Glc made from triose export. Glc synthesized in vitro from fructose-6-phosphate in the presence of deuterium-labeled water had deuterium incorporated at C-2, whereas synthesis from triose phosphates caused C-2 through C-5 to become deuterated. In both tomato (Lycopersicon esculentum L.) and bean (phaseolus vulgaris L.), Glc from sucrose made at night in the presence of deuterium-enriched water was deuterated only in the C-2 position, indicating that >75% of carbon is exported as hexoses at night. In darkness the phosphate in the cytosol was 28 mM, whereas that in the chloroplasts was 5 mW, but hexose phosphates were 10-fold higher in the cytosol than in the chloroplasts. Therefore, hexose phosphates would not move out of chloroplasts without the input of energy. The authors conclude that most carbon leaves chloroplasts at night as Glc, maltose, or higher maltodextrins under normal conditions.

  16. Evolution of the chloroplast division machinery

    Institute of Scientific and Technical Information of China (English)

    Hongbo GAO; Fuli GAO

    2011-01-01

    Chloroplasts are photosynthetic organelles derived from endosymbiotic cyanobacteria during evolution.Dramatic changes occurred during the process of the formation and evolution of chloroplasts,including the large-scale gene transfer from chloroplast to nucleus.However,there are still many essential characters remaining.For the chloroplast division machinery,FtsZ proteins,Ftn2,SulA and part of the division site positioning system- MinD and MinE are still conserved.New or at least partially new proteins,such as FtsZ family proteins FtsZl and ARC3,ARC6H,ARC5,PDV1,PDV2 and MCD1,were introduced for the division of chloroplasts during evolution.Some bacterial cell division proteins,such as FtsA,MreB,Ftn6,FtsW and Ftsl,probably lost their function or were gradually lost.Thus,the chloroplast division machinery is a dynamically evolving structure with both conservation and innovation.

  17. The molecular architecture of the chloroplast thylakoid membrane

    Energy Technology Data Exchange (ETDEWEB)

    Stefansson, H.

    1996-08-01

    Non-detergent procedure for isolation of sub-thylakoid vesicle populations derived from different structural domains of the chloroplast thylakoid membrane has been developed. Sub-thylakoid vesicles representing the grana, grana core, stroma lamellae, and the grana margins have been isolated and their protein composition has been investigated. Furthermore a novel non-detergent procedure for investigating the pigment composition of photosynthetic complexes located in the different structural domains has been developed. This procedure circumvents selective extractions, an perturbing effect often combined with detergent isolations of membrane bound protein complexes. The fractionation experiments show that the NADPH dehydrogenase, suggested to operate as NADPH or ferredoxin-plastoquinone oxidoreductase in cyclic electron transport around photosystem I, is stoichiometrically depleted on photosystem I basis in the grana domain. The fractionation studies are consistent with the model of the thylakoid membrane where the photosystems in the grana are operating in a linear electron transport whereas the site of cyclic electron transport is in the stroma lamellae. It is suggested that partial destacking of grana, as a result of light-induced protein phosphorylation, may promote the exposure of the granal photosystem I centers to the chloroplast stroma and thereby enhance their participation in cyclic electron transport activity. 146 refs, 18 figs

  18. 38: Optimization of electron arc therapy doses by dynamic collimator control

    International Nuclear Information System (INIS)

    The problem of delivering a uniform dose to a large curved surface such as a patient's chest wall has been addressed by the technique of electron arc therapy. Prospective computer simulations show that a dramatic improvement in dose uniformity can, in many clinical situations, be achieved by dynamic shaping of the electron arc collimator, under computer control, as a function of gantry angle and distance superior or inferior to the central plane. Computer optimization techniques applied to the design of a multivane dynamic electron arc collimator is presented, along with representative treatment plans resulting from inclusion of this dynamic technique in electron arc therapy. 17 refs.; 5 figs

  19. A Cyan Fluorescent Reporter Expressed from the Chloroplast Genome of Marchantia polymorpha

    Science.gov (United States)

    Boehm, Christian R.; Ueda, Minoru; Nishimura, Yoshiki; Shikanai, Toshiharu; Haseloff, Jim

    2016-01-01

    Recently, the liverwort Marchantia polymorpha has received increasing attention as a basal plant model for multicellular studies. Its ease of handling, well-characterized plastome and proven protocols for biolistic plastid transformation qualify M. polymorpha as an attractive platform to study the evolution of chloroplasts during the transition from water to land. In addition, chloroplasts of M. polymorpha provide a convenient test-bed for the characterization of genetic elements involved in plastid gene expression due to the absence of mechanisms for RNA editing. While reporter genes have proven valuable to the qualitative and quantitative study of gene expression in chloroplasts, expression of green fluorescent protein (GFP) in chloroplasts of M. polymorpha has proven problematic. We report the design of a codon-optimized gfp varian, mturq2cp, which allowed successful expression of a cyan fluorescent protein under control of the tobacco psbA promoter from the chloroplast genome of M. polymorpha. We demonstrate the utility of mturq2cp in (i) early screening for transplastomic events following biolistic transformation of M. polymorpha spores; (ii) visualization of stromules as elements of plastid structure in Marchantia; and (iii) quantitative microscopy for the analysis of promoter activity. PMID:26634291

  20. A Cyan Fluorescent Reporter Expressed from the Chloroplast Genome of Marchantia polymorpha.

    Science.gov (United States)

    Boehm, Christian R; Ueda, Minoru; Nishimura, Yoshiki; Shikanai, Toshiharu; Haseloff, Jim

    2016-02-01

    Recently, the liverwort Marchantia polymorpha has received increasing attention as a basal plant model for multicellular studies. Its ease of handling, well-characterized plastome and proven protocols for biolistic plastid transformation qualify M. polymorpha as an attractive platform to study the evolution of chloroplasts during the transition from water to land. In addition, chloroplasts of M. polymorpha provide a convenient test-bed for the characterization of genetic elements involved in plastid gene expression due to the absence of mechanisms for RNA editing. While reporter genes have proven valuable to the qualitative and quantitative study of gene expression in chloroplasts, expression of green fluorescent protein (GFP) in chloroplasts of M. polymorpha has proven problematic. We report the design of a codon-optimized gfp varian, mturq2cp, which allowed successful expression of a cyan fluorescent protein under control of the tobacco psbA promoter from the chloroplast genome of M. polymorpha. We demonstrate the utility of mturq2cp in (i) early screening for transplastomic events following biolistic transformation of M. polymorpha spores; (ii) visualization of stromules as elements of plastid structure in Marchantia; and (iii) quantitative microscopy for the analysis of promoter activity. PMID:26634291

  1. Completeness-optimized basis sets: application to ground-state electron momentum densities.

    Science.gov (United States)

    Lehtola, Jussi; Manninen, Pekka; Hakala, Mikko; Hämäläinen, Keijo

    2012-09-14

    In the current work we apply the completeness-optimization paradigm [P. Manninen and J. Vaara, J. Comput. Chem. 27, 434 (2006)] to investigate the basis set convergence of the moments of the ground-state electron momentum density at the self-consistent field level of theory. We present a black-box completeness-optimization algorithm that can be used to generate computationally efficient basis sets for computing any property at any level of theory. We show that the complete basis set (CBS) limit of the moments of the electron momentum density can be reached more cost effectively using completeness-optimized basis sets than using conventional, energy-optimized Gaussian basis sets. By using the established CBS limits, we generate a series of smaller basis sets which can be used to systematically approach the CBS and to perform calculations on larger, experimentally interesting systems. PMID:22979848

  2. Design optimization and fatigue testing of an electronically-driven mechanically-resonant cantilever spring mechanism

    International Nuclear Information System (INIS)

    A light scanning device consisting of an electronically-driven mechanically-resonant cantilever spring-mirror system has been developed for innovative lighting applications. The repeated flexing of the cantilever spring during operation can lead to premature fatigue failure. A model was created to optimize the spring design. The optimized spring design can reduce stress by approximately one-third from the initial design. Fatigue testing showed that the optimized spring design can operate continuously for over 1 month without failure. Analysis of failures indicates surface cracks near the root of the spring are responsible for the failures.

  3. Simulation and optimization of a 10 A electron gun with electrostatic compression for the electron beam ion source

    International Nuclear Information System (INIS)

    Increasing the current density of the electron beam in the ion trap of the Electron Beam Ion Source (EBIS) in BNL's Relativistic Heavy Ion Collider facility would confer several essential benefits. They include increasing the ions’ charge states, and therefore, the ions’ energy out of the Booster for NASA applications, reducing the influx of residual ions in the ion trap, lowering the average power load on the electron collector, and possibly also reducing the emittance of the extracted ion beam. Here, we discuss our findings from a computer simulation of an electron gun with electrostatic compression for electron current up to 10 A that can deliver a high-current-density electron beam for EBIS. The magnetic field in the cathode-anode gap is formed with a magnetic shield surrounding the gun electrodes and the residual magnetic field on the cathode is (5 ÷ 6) Gs. It was demonstrated that for optimized gun geometry within the electron beam current range of (0.5 ÷ 10) A the amplitude of radial beam oscillations can be maintained close to 4% of the beam radius by adjusting the injection magnetic field generated by a separate magnetic coil. Simulating the performance of the gun by varying geometrical parameters indicated that the original gun model is close to optimum and the requirements to the precision of positioning the gun elements can be easily met with conventional technology.

  4. Simulation and optimization of a 10 A electron gun with electrostatic compression for the electron beam ion source

    Science.gov (United States)

    Pikin, A.; Beebe, E. N.; Raparia, D.

    2013-03-01

    Increasing the current density of the electron beam in the ion trap of the Electron Beam Ion Source (EBIS) in BNL's Relativistic Heavy Ion Collider facility would confer several essential benefits. They include increasing the ions' charge states, and therefore, the ions' energy out of the Booster for NASA applications, reducing the influx of residual ions in the ion trap, lowering the average power load on the electron collector, and possibly also reducing the emittance of the extracted ion beam. Here, we discuss our findings from a computer simulation of an electron gun with electrostatic compression for electron current up to 10 A that can deliver a high-current-density electron beam for EBIS. The magnetic field in the cathode-anode gap is formed with a magnetic shield surrounding the gun electrodes and the residual magnetic field on the cathode is (5 ÷ 6) Gs. It was demonstrated that for optimized gun geometry within the electron beam current range of (0.5 ÷ 10) A the amplitude of radial beam oscillations can be maintained close to 4% of the beam radius by adjusting the injection magnetic field generated by a separate magnetic coil. Simulating the performance of the gun by varying geometrical parameters indicated that the original gun model is close to optimum and the requirements to the precision of positioning the gun elements can be easily met with conventional technology.

  5. Multiple regulatory mechanisms in the chloroplast of green algae: relation to hydrogen production.

    Science.gov (United States)

    Antal, Taras K; Krendeleva, Tatyana E; Tyystjärvi, Esa

    2015-09-01

    A complex regulatory network in the chloroplast of green algae provides an efficient tool for maintenance of energy and redox balance in the cell under aerobic and anaerobic conditions. In this review, we discuss the structural and functional organizations of electron transport pathways in the chloroplast, and regulation of photosynthesis in the green microalga Chlamydomonas reinhardtii. The focus is on the regulatory mechanisms induced in response to nutrient deficiency stress and anoxia and especially on the role of a hydrogenase-mediated reaction in adaptation to highly reducing conditions and ATP deficiency in the cell. PMID:25986411

  6. Optimal Allocation of Social Cost for Electronic Payment System: A Ramsey Approach

    OpenAIRE

    Pidong Huang; Young Sik Kim; Manjong Lee

    2014-01-01

    Using a standard Ramsey approach, we examine an optimal allocation of the social cost for electronic payment system in the context of a dynamic general equilibrium model where money is essential. The benevolent government provides electronic payment services and allocates the relevant social cost through taxation on the beneficiaries¡¯ labor and consumption. A higher tax rate on labor yields the following desirable allocations. First, it implies a lower welfare loss due to the distortionary c...

  7. Optimizing Effectiveness in Electronic Prescriptions for Pediatric Outpatients: A Call for Responsive Action

    OpenAIRE

    Parrish II, Richard H.; Sandra Benavides; Joseph T. Malak; Amy L Potts; Micheal Guirguis; Tracy Hagemann

    2014-01-01

    A pediatric compounded non-sterile products repository (pCNP) to optimize the effectiveness and safety of “off-label” use of compounded pharmacotherapy through complete transmission of electronic prescriptions across the continuum of care is described. The advent of electronic prescribing has the potential to refocus and resolve long-standing issues of prescription therapy for pediatric patients related to formulation, indication, dosing, and outcomes follow-up, among others. This white paper...

  8. Discrete redox signaling pathways regulate photosynthetic light-harvesting and chloroplast gene transcription.

    Directory of Open Access Journals (Sweden)

    John F Allen

    Full Text Available In photosynthesis in chloroplasts, two related regulatory processes balance the actions of photosystems I and II. These processes are short-term, post-translational redistribution of light-harvesting capacity, and long-term adjustment of photosystem stoichiometry initiated by control of chloroplast DNA transcription. Both responses are initiated by changes in the redox state of the electron carrier, plastoquinone, which connects the two photosystems. Chloroplast Sensor Kinase (CSK is a regulator of transcription of chloroplast genes for reaction centres of the two photosystems, and a sensor of plastoquinone redox state. We asked whether CSK is also involved in regulation of absorbed light energy distribution by phosphorylation of light-harvesting complex II (LHC II. Chloroplast thylakoid membranes isolated from a CSK T-DNA insertion mutant and from wild-type Arabidopsis thaliana exhibit similar light- and redox-induced (32P-labelling of LHC II and changes in 77 K chlorophyll fluorescence emission spectra, while room-temperature chlorophyll fluorescence emission transients from Arabidopsis leaves are perturbed by inactivation of CSK. The results indicate indirect, pleiotropic effects of reaction centre gene transcription on regulation of photosynthetic light-harvesting in vivo. A single, direct redox signal is transmitted separately to discrete transcriptional and post-translational branches of an integrated cytoplasmic regulatory system.

  9. Ozone-induced changes in the chloroplast structure of conifer needles, and their use in ozone diagnostics

    International Nuclear Information System (INIS)

    Ozone induces characteristic symptoms in the chloroplasts of the needles of several coniferous species. Chloroplasts are (1) reduced in size and (2) the stroma is electron dense. Moreover (3) these chloroplast alterations are more pronounced in the outer mesophyll cell layers and in the upper side of the needle compared to the inner layers and lower side. The syndrome, including the three symptoms (1)-(3), is found in the green needles of Scots pine and Norway spruce not only in the experimental fumigations, but also in mature trees in the field, and has potential for diagnosis of ozone stress. For sound ozone diagnostics all three symptoms must be present in the samples studied. The symptoms in relation to needle anatomy and physiology is discussed, and recommendations for sampling and analysis are given. - Ozone-induced alterations in chloroplast structure of conifer needles are reviewed, and recommendations for field monitoring given

  10. Contraction of completeness-optimized basis sets: application to ground-state electron momentum densities.

    Science.gov (United States)

    Lehtola, Susi; Manninen, Pekka; Hakala, Mikko; Hämäläinen, Keijo

    2013-01-28

    Completeness-optimization is a novel method for the formation of one-electron basis sets. Contrary to conventional methods of basis set generation that optimize the basis set with respect to ground-state energy, completeness-optimization is a completely general, black-box method that can be used to form cost-effective basis sets for any wanted property at any level of theory. In our recent work [J. Lehtola, P. Manninen, M. Hakala, and K. Hämäläinen, J. Chem. Phys. 137, 104105 (2012)] we applied the completeness-optimization approach to forming primitive basis sets tuned for calculations of the electron momentum density at the Hartree-Fock (HF) level of theory. The current work extends the discussion to contracted basis sets and to the post-HF level of theory. Contractions are found to yield significant reductions in the amount of functions without compromising the accuracy. We suggest polarization-consistent and correlation-consistent basis sets for the first three rows of the periodic table, which are completeness-optimized for electron momentum density calculations. PMID:23387570

  11. Optimization of power output and study of electron beam energy spread in a Free Electron Laser oscillator

    CERN Document Server

    Abramovich, A; Efimov, S; Gover, A; Pinhasi, Y; Yahalom, A

    2001-01-01

    Design of a multi-stage depressed collector for efficient operation of a Free Electron Laser (FEL) oscillator requires knowledge of the electron beam energy distribution. This knowledge is necessary to determine the voltages of the depressed collector electrodes that optimize the collection efficiency and overall energy conversion efficiency of the FEL. The energy spread in the electron beam is due to interaction in the wiggler region, as electrons enter the interaction region at different phases relative to the EM wave. This interaction can be simulated well by a three-dimensional simulation code such as FEL3D. The main adjustable parameters that determine the electron beam energy spread after interaction are the e-beam current, the initial beam energy, and the quality factor of the resonator out-coupling coefficient. Using FEL3D, we study the influence of these parameters on the available radiation power and on the electron beam energy distribution at the undulator exit. Simulations performed for I=1.5 A, E...

  12. Molecule-optimized Basis Sets and Hamiltonians for Accelerated Electronic Structure Calculations of Atoms and Molecules

    CERN Document Server

    Gidofalvi, Gergely

    2014-01-01

    Molecule-optimized basis sets, based on approximate natural orbitals, are developed for accelerating the convergence of quantum calculations with strongly correlated (multi-referenced) electrons. We use a low-cost approximate solution of the anti-Hermitian contracted Schr{\\"o}dinger equation (ACSE) for the one- and two-electron reduced density matrices (RDMs) to generate an approximate set of natural orbitals for strongly correlated quantum systems. The natural-orbital basis set is truncated to generate a molecule-optimized basis set whose rank matches that of a standard correlation-consistent basis set optimized for the atoms. We show that basis-set truncation by approximate natural orbitals can be viewed as a one-electron unitary transformation of the Hamiltonian operator and suggest an extension of approximate natural-orbital truncations through two-electron unitary transformations of the Hamiltonian operator, such as those employed in the solution of the ACSE. The molecule-optimized basis set from the ACS...

  13. Glycolate transporter of the pea chloroplast envelope

    International Nuclear Information System (INIS)

    The discovery of a glycolate transporter in the pea (Pisum sativum) chloroplast envelope is described. Several novel silicone oil centrifugation methods were developed to resolve the initial rate kinetics of [14C]glycolate transport by isolated, intact pea chloroplasts. Chloroplast glycolate transport was found to be carrier mediated. Transport rates saturated with increasing glycolate concentration. N-Ethylmaleimide (NEM) pretreatment of chloroplasts inhibited transport, an inhibition prevented by glycolate. Glycolate distributed across the envelope in a way which equalized stromal and medium glycolic acid concentrations, limiting possible transport mechanisms to facilitated glycolic acid diffusion, proton symport or hydroxyl antiport. The effects of stomal and medium pH's on the K/sub m/ and V/sub max/ fit the predictions of mobile carrier kinetic models of hydroxyl antiport or proton symport (H+ binds first). The carrier mediated transport was fast enough to be consistent with in vivo rates of photorespiration. The 2-hydroxymonocarboxylates, glycerate, lactate and glyoxylate are competitive inhibitors of chloroplast glycolate uptake. Glyoxylate, D-lactate and D-glycerate cause glycolate counterflow, indicating that they are also substrates of the glycolate carrier. This finding was confirmed for D-glycerate by studies on glycolate effects on [1-14C]D-glycerate transport

  14. Interface for electronic data capture systems for clinical trials by optimal utilization of available hospital resources.

    Science.gov (United States)

    Kaushik, Sashank; Khan, Anzalee; Kaushik, Saurabh; Lindenmayer, Jean-Pierre

    2008-01-01

    We describe Clinical Trials System (CTS), an innovative EDC system utilizing data from existing hospital-based electronic databases that supports information gathering and storing for various clinical trials. The complexities of designing electronic clinical trials systems and their ideal features are outlined. CTS optimally utilizes existing electronic databases in a well-organized and easy-to-reference format. CTS is currently incorporated within a large psychiatric center, allowing easy sharing of information and data among multidisciplinary clinical and research teams. PMID:18999083

  15. Three-Dimensional Visualization of the Tubular-Lamellar Transformation of the Internal Plastid Membrane Network during Runner Bean Chloroplast Biogenesis.

    Science.gov (United States)

    Kowalewska, Łucja; Mazur, Radosław; Suski, Szymon; Garstka, Maciej; Mostowska, Agnieszka

    2016-04-01

    Chloroplast biogenesis is a complex process that is integrated with plant development, leading to fully differentiated and functionally mature plastids. In this work, we used electron tomography and confocal microscopy to reconstruct the process of structural membrane transformation during the etioplast-to-chloroplast transition in runner bean (Phaseolus coccineus). During chloroplast development, the regular tubular network of paracrystalline prolamellar bodies (PLBs) and the flattened porous membranes of prothylakoids develop into the chloroplast thylakoids. Three-dimensional reconstruction is required to provide us with a more complete understanding of this transformation. We provide spatial models of the bean chloroplast biogenesis that allow such reconstruction of the internal membranes of the developing chloroplast and visualize the transformation from the tubular arrangement to the linear system of parallel lamellae. We prove that the tubular structure of the PLB transforms directly to flat slats, without dispersion to vesicles. We demonstrate that the grana/stroma thylakoid connections have a helical character starting from the early stages of appressed membrane formation. Moreover, we point out the importance of particular chlorophyll-protein complex components in the membrane stacking during the biogenesis. The main stages of chloroplast internal membrane biogenesis are presented in a movie that shows the time development of the chloroplast biogenesis as a dynamic model of this process. PMID:27002023

  16. Beam trial and operation optimization of 10 MeV industrial electron Linac

    International Nuclear Information System (INIS)

    A 10 MeV travelling wave industrial (TWINDUS) electron linac suitable for radiation processing applications is under development at RRCAT. The linac is designed and developed indigenously to deliver beam power of 6 kW at energy level of 10 MeV. It consists of various subsystems such as accelerating structure, electron gun, microwave system, control system, beam injection and focusing system, vacuum system, beam diagnostic and measurement system and safety system. After independent subsystem level testing, all the systems were integrated and beam trial experiments were taken up in a shielded vault after obtaining due approval from Atomic Energy Regulatory Board (AERB). Optimization and harmonization of the operating parameters of all these sub-systems is carried-out in order to achieve the desired electron beam current and power. This paper describes the results of series of beam trial experiments carried out to optimize operation parameters for demonstrating operation at 4.2 kW beam power

  17. Protein methylation reactions in intact pea chloroplasts

    International Nuclear Information System (INIS)

    Post-translational protein methylation was investigated in Pisum sativum chloroplasts. Intact pea chloroplasts were incubated with (3H-methyl)-S-adenosylmethionine under various conditions. The chloroplasts were then separated into stromal and thylakoid fractions and analyzed for radioactivity transferred to protein. Light enhanced the magnitude of labeling in both fractions. One thylakoid polypeptide with an apparent molecular mass of 43 kDa was labeled only in the light. Several other thylakoid and stromal proteins were labeled in both light and dark-labeling conditions. Both base-labile methylation, carboxy-methylesters and base-stable groups, N-methylations were found. Further characterization of the methyl-transfer reactions will be presented

  18. Genomics and chloroplast evolution: what did cyanobacteria do for plants?

    OpenAIRE

    Raven, J.A.; Allen, John

    2003-01-01

    The complete genome sequences of cyanobacteria and of the higher plant Arabidopsis thaliana leave no doubt that the plant chloroplast originated, through endosymbiosis, from a cyanobacterium. But the genomic legacy of cyanobacterial ancestry extends far beyond the chloroplast itself, and persists in organisms that have lost chloroplasts completely.

  19. Optimal control of the electronic current density: Application to one- and two-dimensional one-electron systems

    International Nuclear Information System (INIS)

    Quantum optimal control theory is a powerful tool for engineering quantum systems subject to external fields such as the ones created by intense lasers. The formulation relies on a suitable definition for a target functional, that translates the intended physical objective to a mathematical form. We propose the use of target functionals defined in terms of the one-particle density and its current. A strong motivation for this is the possibility of using time-dependent density-functional theory for the description of the system dynamics. We exemplify this idea by defining an objective functional that on one hand attempts a large overlap with a target density and on the other hand minimizes the current. The latter requirement leads to optimized states with increased stability, which we prove with a few examples of one- and two-dimensional one-electron systems.

  20. The reduced state of the plastoquinone pool is required for chloroplast-mediated stomatal closure in response to calcium stimulation.

    Science.gov (United States)

    Wang, Wen-Hua; He, En-Ming; Chen, Juan; Guo, Ying; Chen, Juan; Liu, Xiang; Zheng, Hai-Lei

    2016-04-01

    Besides their participation in photosynthesis, leaf chloroplasts function in plant responses to stimuli, yet how they direct stimulus-induced stomatal movement remains elusive. Here, we showed that over-reduction of the plastoquinone (PQ) pool by dibromothymoquinone (DBMIB) was closely associated with stomatal closure in plants which required chloroplastic H2 O2 generation in the mesophyll. External application of H2 O2 reduced the PQ pool, whereas the cell-permeable reactive oxygen species (ROS) scavenger N-acetylcysteine (NAC) reversed the DBMIB-induced over-reduction of the PQ pool and stomatal closure. Mesophyll chloroplasts are key players of extracellular Ca(2+) (Ca(2+) o )-induced stomatal closure, but when treated with either 3-(3',4'-dichlorophenyl)-1,1-dimethylurea (DCMU) or NAC they failed to facilitate Ca(2+) o -induced stomatal closure due to the inhibition of chloroplastic H2 O2 synthesis in mesophyll. Similarly, the Arabidopsis electron transfer chain-related mutants npq4-1, stn7 and cas-1 exhibited diverse responses to Ca(2+) o or DBMIB. Transcriptome analysis also demonstrated that the PQ pool signaling pathway shared common responsive genes with the H2 O2 signaling pathway. These results implicated a mechanism for chloroplast-mediated stomatal closure involving the generation of mesophyll chloroplastic H2 O2 based on the reduced state of the PQ pool, which is calcium-sensing receptor (CAS) and LHCII phosphorylation dependent. PMID:26945669

  1. Analysis on the Metrics used in Optimizing Electronic Business based on Learning Techniques

    Directory of Open Access Journals (Sweden)

    Irina-Steliana STAN

    2014-09-01

    Full Text Available The present paper proposes a methodology of analyzing the metrics related to electronic business. The drafts of the optimizing models include KPIs that can highlight the business specific, if only they are integrated by using learning-based techniques. Having set the most important and high-impact elements of the business, the models should get in the end the link between them, by automating business flows. The human resource will be found in the situation of collaborating more and more with the optimizing models which will translate into high quality decisions followed by profitability increase.

  2. Optimization of operation parameters of 80-keV electron gun

    International Nuclear Information System (INIS)

    A Slowing Down Time Spectrometer (SDTS) system is a highly efficient technique for isotopic nuclear material content analysis. SDTS technology has been used to analyze spent nuclear fuel and the pyro-processing of spent fuel. SDTS requires an external neutron source to induce the isotopic fissile fission. A high intensity neutron source is required to ensure a high for a good fissile fission. The electron linear accelerator system was selected to generate proper source neutrons efficiently. As a first step, the electron generator of an 80-keV electron gun was manufactured. In order to produce the high beam power from electron linear accelerator, a proper beam current is required form the electron generator. In this study, the beam current was measured by evaluating the performance of the electron generator. The beam current was determined by five parameters: high voltage at the electron gun, cathode voltage, pulse width, pulse amplitude, and bias voltage at the grid. From the experimental results under optimal conditions, the high voltage was determined to be 80 kV, the pulse width was 500 ns, and the cathode voltage was from 4.2 V to 4.6 V. The beam current was measured as 1.9 A at maximum. These results satisfy the beam current required for the operation of an electron linear accelerator.

  3. Direct Chloroplast Sequencing: Comparison of Sequencing Platforms and Analysis Tools for Whole Chloroplast Barcoding

    OpenAIRE

    Marta Brozynska; Agnelo Furtado; Robert James Henry

    2014-01-01

    Direct sequencing of total plant DNA using next generation sequencing technologies generates a whole chloroplast genome sequence that has the potential to provide a barcode for use in plant and food identification. Advances in DNA sequencing platforms may make this an attractive approach for routine plant identification. The HiSeq (Illumina) and Ion Torrent (Life Technology) sequencing platforms were used to sequence total DNA from rice to identify polymorphisms in the whole chloroplast genom...

  4. Optimal control of the initiation of a pericyclic reaction in the electronic ground state

    Indian Academy of Sciences (India)

    Timm Bredtmann; Jörn Manz

    2012-01-01

    Pericyclic reactions in the electronic ground state may be initiated by down-chirped pump-dump sub-pulses of an optimal laser pulse, in the ultraviolet (UV) frequency and sub-10 femtosecond (fs) time domain. This is demonstrated by means of a quantum dynamics model simulation of the Cope rearrangement of Semibullvalene. The laser pulse is designed by means of optimal control theory, with detailed analysis of the mechanism. The theoretical results support the recent experimental initiation of a pericyclic reaction. The present approach provides an important step towards monitoring asynchronous electronic fluxes during synchronous nuclear pericyclic reaction dynamics, with femto-to-attosecond time resolution, as motivated by the recent prediction of our group.

  5. From extracellular to intracellular: the establishment of mitochondria and chloroplasts.

    Science.gov (United States)

    Whatley, J M; John, P; Whatley, F R

    1979-04-11

    Paracoccus and Rhodopseudomonas are unusual among bacteria in having a majority of the biochemical features of mitochondria; blue-green algae have many of the features of chloroplasts. The theory of serial endosymbiosis proposes that a primitive eukaryote successively took up bacteria and blue-green algae to yield mitochondria and chloroplasts respectively. Possible characteristics of transitional forms are indicated both by the primitive amoeba, Pelomyxa, which lacks mitochondria but contains a permanent population of endosymbiotic bacteria, and by several anomalous eukaryotic algae, e.g. Cyanophora, which contain cyanelles instead of chloroplasts. Blue-green algae appear to be obvious precursors of red algal chloroplasts but the ancestry of other chloroplasts is less certain, though the epizoic symbiont, Prochloron, may resemble the ancestral green algal chloroplast. We speculate that the chloroplasts of the remaining algae may have been a eukaryotic origin. The evolution or organelles from endosymbiotic precursors would involve their integration with the host cell biochemically, structurally and numerically. PMID:36620

  6. Simulated annealing method for electronic circuits design: adaptation and comparison with other optimization methods

    International Nuclear Information System (INIS)

    The circuit design problem consists in determining acceptable parameter values (resistors, capacitors, transistors geometries ...) which allow the circuit to meet various user given operational criteria (DC consumption, AC bandwidth, transient times ...). This task is equivalent to a multidimensional and/or multi objective optimization problem: n-variables functions have to be minimized in an hyper-rectangular domain ; equality constraints can be eventually specified. A similar problem consists in fitting component models. In this way, the optimization variables are the model parameters and one aims at minimizing a cost function built on the error between the model response and the data measured on the component. The chosen optimization method for this kind of problem is the simulated annealing method. This method, provided by the combinatorial optimization domain, has been adapted and compared with other global optimization methods for the continuous variables problems. An efficient strategy of variables discretization and a set of complementary stopping criteria have been proposed. The different parameters of the method have been adjusted with analytical functions of which minima are known, classically used in the literature. Our simulated annealing algorithm has been coupled with an open electrical simulator SPICE-PAC of which the modular structure allows the chaining of simulations required by the circuit optimization process. We proposed, for high-dimensional problems, a partitioning technique which ensures proportionality between CPU-time and variables number. To compare our method with others, we have adapted three other methods coming from combinatorial optimization domain - the threshold method, a genetic algorithm and the Tabu search method - The tests have been performed on the same set of test functions and the results allow a first comparison between these methods applied to continuous optimization variables. Finally, our simulated annealing program

  7. Optimizing read-out of the NECTAr front-end electronics

    International Nuclear Information System (INIS)

    We describe the optimization of the read-out specifications of the NECTAr front-end electronics for the Cherenkov Telescope Array (CTA). The NECTAr project aims at building and testing a demonstrator module of a new front-end electronics design, which takes an advantage of the know-how acquired while building the cameras of the CAT, H.E.S.S.-I and H.E.S.S.-II experiments. The goal of the optimization work is to define the specifications of the digitizing electronics of a CTA camera, in particular integration time window, sampling rate, analog bandwidth using physics simulations. We employed for this work real photomultiplier pulses, sampled at 100 ps with a 600 MHz bandwidth oscilloscope. The individual pulses are drawn randomly at the times at which the photo-electrons, originating from atmospheric showers, arrive at the focal planes of imaging atmospheric Cherenkov telescopes. The timing information is extracted from the existing CTA simulations on the GRID and organized in a local database, together with all the relevant physical parameters (energy, primary particle type, zenith angle, distance from the shower axis, pixel offset from the optical axis, night-sky background level, etc.), and detector configurations (telescope types, camera/mirror configurations, etc.). While investigating the parameter space, an optimal pixel charge integration time window, which minimizes relative error in the measured charge, has been determined. This will allow to gain in sensitivity and to lower the energy threshold of CTA telescopes. We present results of our optimizations and first measurements obtained using the NECTAr demonstrator module.

  8. Structure Optimization Design of the Electronically Controlled Fuel Control Rod System in a Diesel Engine

    OpenAIRE

    Hui Jin; Haosen Wang

    2015-01-01

    Poor ride comfort and shorter clutch life span are the key factors restricting the commercialization of automated manual transmission (AMT). For nonelectrically controlled engines or AMT where cooperative control between the engine and the transmission is not realizable, applying electronically controlled fuel control rod systems (ECFCRS) is an effective way to solve these problems. By applying design software such as CATIA, Matlab and Simulink, and MSC Adams, a suite of optimization design m...

  9. Multiobjective Genetic Algorithms Program for the Optimization of an OTA for Front-End Electronics

    OpenAIRE

    Abdelghani Dendouga; Slimane Oussalah; Damien Thienpont; Abdenour Lounis

    2014-01-01

    The design of an interface to a specific sensor induces costs and design time mainly related to the analog part. So to reduce these costs, it should have been standardized like digital electronics. The aim of the present work is the elaboration of a method based on multiobjectives genetic algorithms (MOGAs) to allow automated synthesis of analog and mixed systems. This proposed methodology is used to find the optimal dimensional transistor parameters (length and width) in order to obtain oper...

  10. A Thesis on Design Optimization of Heat Sink in Power Electronics

    Directory of Open Access Journals (Sweden)

    P.Chennakesavarao

    2014-10-01

    Full Text Available The heat sinks are used in electronic systems to remove heat from the chip and effectively transfer it to the ambient. The heat sink geometry is designed by the mechanical engineers with the primary aim of reducing the thermal resistance of the heat sink for better cooling in the electronic systems. Due to the proximity of the heat sink with the ICs, the RF fields created by RF currents in the ICs/PCBs gets coupled to heat sinks. Hence, the coupled RF current can cause radiated emission. This radiated noise from the device can couple and disturb the functioning of the nearby electronic systems. Also this radiated emission from the device poses a problem to the system compliance with respect to EMI/EMC regulations. The international EMI/EMC standards require the radiated emission from the electronic devices to be kept below the specified limits. As a result the design of Heat Sink is very important factor for the efficient operation of the electronic equipment. In this project design optimization of a Heat sink in a Power amplifier is performed to reduce the weight and size .Power amplifier is electronic equipment mounted in an army vehicle. The power modules inside the amplifier generates a heat of 1440 Watts and a temperature of 140 0c.Two Heat sinks are used to dissipate the heat generated inside the equipment and maintain a temperature of less than 850c. The existing heat sink which is being used is weighing around 10.3kgs and height of 51mm; as a result the unit is very robust. The objective of my project is To design & optimize the heat sink to reduce the weight and size. The optimized heat sink should also dissipate heat generated by power modules and maintain a temperature of less than 850c inside. To achieve the design a steady state thermal analysis will be performed on the heat sink and plot the Temperature distribution on the fins. Based on the above analysis results we will increase/decrease the number of fins, thickness of fins, and

  11. Selection and optimization of pin cross-sections for electronics cooling

    International Nuclear Information System (INIS)

    Pin fins are widely used as elements that provide increased cooling for electronic devices. Increasing demands regarding the performance of such devices can be observed due to the increasing heat production density of electronic components. For this reason, extensive work is being carried out to select and optimize pin fin elements for increased heat transfer. In the present paper, a procedure is described to select heat exchanger surfaces with pin fins in accordance with their location in a performance diagram. Such a diagram provides performance comparisons of pin fins with respect to two operating parameters: the heat transfer rate per unit base surface area and the power input for the same area. It is shown that elliptical cross-sections offer the best performance compared with all other investigated cross-sections for pin fins. The present work demonstrates that the heat exchanger performance plot allows also the selection of the best elliptical cross-section design within the initial design set (design set obtained numerically) in analogy with the Pareto-optimality approach. However, the real optimal geometry of the elliptical cross-section is deduced from commercial optimization software, modeFRONTIER. It is shown that by subsequent use of the virtual solutions from the response surface modelling (RSM) of that software and their validation with Star-CD, a complete 'Pareto-frontier solution' can be obtained

  12. Selection and optimization of pin cross-sections for electronics cooling

    Energy Technology Data Exchange (ETDEWEB)

    Sahiti, N. [Institute of Fluid Mechanics, Friedrich-Alexander-University Erlangen-Nuremberg, Cauerstr. 4, D-91058 Erlangen (Germany)]. E-mail: sahiti@lstm.uni-erlangen.de; Durst, F. [Institute of Fluid Mechanics, Friedrich-Alexander-University Erlangen-Nuremberg, Cauerstr. 4, D-91058 Erlangen (Germany); Geremia, P. [ES.TEC.O. s.r.l., Area Science Park, Padriciano 99, 34012 Trieste (Italy)

    2007-01-15

    Pin fins are widely used as elements that provide increased cooling for electronic devices. Increasing demands regarding the performance of such devices can be observed due to the increasing heat production density of electronic components. For this reason, extensive work is being carried out to select and optimize pin fin elements for increased heat transfer. In the present paper, a procedure is described to select heat exchanger surfaces with pin fins in accordance with their location in a performance diagram. Such a diagram provides performance comparisons of pin fins with respect to two operating parameters: the heat transfer rate per unit base surface area and the power input for the same area. It is shown that elliptical cross-sections offer the best performance compared with all other investigated cross-sections for pin fins. The present work demonstrates that the heat exchanger performance plot allows also the selection of the best elliptical cross-section design within the initial design set (design set obtained numerically) in analogy with the Pareto-optimality approach. However, the real optimal geometry of the elliptical cross-section is deduced from commercial optimization software, modeFRONTIER. It is shown that by subsequent use of the virtual solutions from the response surface modelling (RSM) of that software and their validation with Star-CD, a complete 'Pareto-frontier solution' can be obtained.

  13. Multi-objective Optimizations of a Normal Conducting RF Gun Based Ultra Fast Electron Diffraction Beamline

    CERN Document Server

    Gulliford, C; Maxson, J; Bazarov, I

    2016-01-01

    We present the results of multi-objective genetic algorithm optimizations of a potential single shot ultra fast electron diffraction beamline utilizing a 100 MV/m 1.6 cell normal conducting rf (NCRF) gun, as well as a 9 cell 2pi/3 bunching cavity placed between two solenoids. Optimizations of the transverse projected emittance as a function of bunch charge are presented and discussed in terms of the scaling laws derived in the charge saturation limit. Additionally, optimization of the transverse coherence length as a function of final rms bunch length at the sample location have been performed for a charge of 1e6 electrons. Analysis of the solutions is discussed, as are the effects of disorder induced heating. In particular, for a charge of $10^6$ electrons and final beam size greater than or equal to 25 microns, we found a relative coherence length of 0.07, 0.1, and 0.2 nm/micron for a final bunch length of approximately 5, 30, and 100 fs, respectively. These results demonstrate the viability of using geneti...

  14. Preparation of intact chloroplasts by chemically induced lysis of the green alga Dunaliella marina.

    Science.gov (United States)

    Kombrink, E; Wöber, G

    1980-07-01

    A method for the isolation in high yield of intact chloroplasts from the unicellular green alga Dunaliella marina (Volvocales) is described. This procedure uses chemically induced lysis of cells with the polycationic macromolecules, DEAE-dextran (M=500,000) or poly-D,L-lysine (M=30,000-70,000). Reaction conditions were optimized with respect to obtaining a high yield of intact chloroplasts, after isopycnic centrifugation in a linear sucrose density gradient, by varying the concentration of polycation and the temperature and pH of incubation. Broken chloroplasts devoid of the stromal marker enzymes fructosebisphosphate phosphatase and ribulosebisphosphate carboxylase, but containing mitochondrial (fumarase) and microbody (catalase) contamination, were banded at a bouyant density of 1.18 g cm(-3). Intact chloroplasts, as indicated by their retention of alkaline fructosebisphosphate phosphatase and ribulosebisphosphate carboxylase, were found in 30% yield (chlorophyll in intact cells, 100%) at an equilibrium density of 1.24 g cm(-3). Contamination by cytoplasmic material (pyruvate kinase), mitochondria, and microbodies was less than 8% each. PMID:24306242

  15. Multiobjective Optimization for Electronic Circuit Design in Time and Frequency Domains

    Directory of Open Access Journals (Sweden)

    J. Dobes

    2013-04-01

    Full Text Available The multiobjective optimization provides an extraordinary opportunity for the finest design of electronic circuits because it allows to mathematically balance contradictory requirements together with possible constraints. In this paper, an original and substantial improvement of an existing method for the multiobjective optimization known as GAM (Goal Attainment Method is suggested. In our proposal, the GAM algorithm itself is combined with a procedure that automatically provides a set of parameters -- weights, coordinates of the reference point -- for which the method generates noninferior solutions uniformly spread over an appropriately selected part of the Pareto front. Moreover, the resulting set of obtained solutions is then presented in a suitable graphic form so that the solution representing the most satisfactory tradeoff can be easily chosen by the designer. Our system generates various types of plots that conveniently characterize results of up to four-dimensional problems. Technically, the procedures of the multiobjective optimization were created as a software add-on to the CIA (Circuit Interactive Analyzer program. This way enabled us to utilize many powerful features of this program, including the sensitivity analyses in time and frequency domains. As a result, the system is also able to perform the multiobjective optimization in the time domain and even highly nonlinear circuits can be significantly improved by our program. As a demonstration of this feature, a multiobjective optimization of a C-class power amplifier in the time domain is thoroughly described in the paper. Further, a four-dimensional optimization of a video amplifier is demonstrated with an original graphic representation of the Pareto front, and also some comparison with the weighting method is done. As an example of improving noise properties, a multiobjective optimization of a low-noise amplifier is performed, and the results in the frequency domain are shown

  16. Protein phosphorylation in chloroplasts - a survey of phosphorylation targets.

    Science.gov (United States)

    Baginsky, Sacha

    2016-06-01

    The development of new software tools, improved mass spectrometry equipment, a suite of optimized scan types, and better-quality phosphopeptide affinity capture have paved the way for an explosion of mass spectrometry data on phosphopeptides. Because phosphoproteomics achieves good sensitivity, most studies use complete cell extracts for phosphopeptide enrichment and identification without prior enrichment of proteins or subcellular compartments. As a consequence, the phosphoproteome of cell organelles often comes as a by-product from large-scale studies and is commonly assembled from these in meta-analyses. This review aims at providing some guidance on the limitations of meta-analyses that combine data from analyses with different scopes, reports on the current status of knowledge on chloroplast phosphorylation targets, provides initial insights into phosphorylation site conservation in different plant species, and highlights emerging information on the integration of gene expression with metabolism and photosynthesis by means of protein phosphorylation. PMID:26969742

  17. Characterizing and Optimizing Photocathode Laser Distributions for Ultra-low Emittance Electron Beam Operations

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, F. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Bohler, D. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Ding, Y. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Gilevich, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Huang, Z. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Loos, H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Ratner, D. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Vetter, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-12-07

    Photocathode RF gun has been widely used for generation of high-brightness electron beams for many different applications. We found that the drive laser distributions in such RF guns play important roles in minimizing the electron beam emittance. Characterizing the laser distributions with measurable parameters and optimizing beam emittance versus the laser distribution parameters in both spatial and temporal directions are highly desired for high-brightness electron beam operation. In this paper, we report systematic measurements and simulations of emittance dependence on the measurable parameters represented for spatial and temporal laser distributions at the photocathode RF gun systems of Linac Coherent Light Source. The tolerable parameter ranges for photocathode drive laser distributions in both directions are presented for ultra-low emittance beam operations.

  18. Measurements and tests on FBK silicon sensors with an optimized electronic design for a CTA camera

    CERN Document Server

    Ambrosi, G; Aramo, C; Bissaldi, E; Capasso, M; Corti, D; de Angelis, A; de Palma, F; Ferrarotto, F; Ferri, A; Garrappa, S; Giglietto, N; Giordano, F; Gola, A; Ionica, M; Iori, M; Licciulli, F; Mariotti, M; Marzocca, C; Paoletti, R; Piemonte, C; Postolache, V; Rando, R; Stella, C; Vallania, P; Vigorito, C

    2014-01-01

    In October 2013, the Italian Ministry approved the funding of a Research & Development (R&D) study, within the "Progetto Premiale TElescopi CHErenkov made in Italy (TECHE)", devoted to the development of a demonstrator for a camera for the Cherenkov Telescope Array (CTA) consortium. The demonstrator consists of a sensor plane based on the Silicon Photomultiplier (SiPM) technology and on an electronics designed for signal sampling. Preliminary tests on a matrix of sensors produced by the Fondazione Bruno Kessler (FBK-Trento, Italy) and on electronic prototypes produced by SITAEL S.p.A. will be presented. In particular, we used different designs of the electronics in order to optimize the output signals in terms of tail cancellation. This is crucial for applications where a high background is expected, as for the CTA experiment.

  19. Optimization of a seeding option for the VUV free electron laser at DESY

    CERN Document Server

    Saldin, E L; Yurkov, M V

    2000-01-01

    In order to get fully coherent radiation from the Free Electron Laser (FEL) amplifier starting from the shot noise, it is foreseen to implement a seeding option into the VUV FEL being under construction at DESY (DESY print TESLA-FEL 95-03, Hamburg, DESY, 1995, Seeding option for the VUV free electron laser at DESY: joint DESY and GKSS proposal; Available at DESY upon request only). It consists of an additional undulator, a bypass for electrons and an X-ray monochromator. This paper presents the results of optimization of the seeding option for the VUV FEL providing maximal spectral brightness at minimal shot-to-shot intensity fluctuations. Calculations are performed with three-dimensional, time-dependent simulation code FAST (Nucl. Instr. and Meth. A 429 (1999) 233).

  20. A Set of 100 Chloroplast DNA Primer Pairs to Study Population Genetics and Phylogeny in Monocotyledons

    OpenAIRE

    Scarcelli, Nora; Barnaud, Adeline; Eiserhardt, Wolf; Treier, Urs A.; Seveno, Marie; d'Anfray, Amélie; Vigouroux, Yves; Pintaud, Jean-Christophe

    2011-01-01

    Chloroplast DNA sequences are of great interest for population genetics and phylogenetic studies. However, only a small set of markers are commonly used. Most of them have been designed for amplification in a large range of Angiosperms and are located in the Large Single Copy (LSC). Here we developed a new set of 100 primer pairs optimized for amplification in Monocotyledons. Primer pairs amplify coding (exon) and non-coding regions (intron and intergenic spacer). They span the different chlo...

  1. Optimization and stability of the contrast transfer function in aberration-corrected electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tromp, R.M., E-mail: rtromp@us.ibm.com [IBM T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States); Leiden Institute of Physics, Kamerlingh Onnes Laboratory, Niels Bohrweg 2, 2333 CA Leiden (Netherlands); Schramm, S.M. [Leiden Institute of Physics, Kamerlingh Onnes Laboratory, Niels Bohrweg 2, 2333 CA Leiden (Netherlands)

    2013-02-15

    The Contrast Transfer Function (CTF) describes the manner in which the electron microscope modifies the object exit wave function as a result of objective lens aberrations. For optimum resolution in C{sub 3}-corrected microscopes it is well established that a small negative value of C{sub 3}, offset by positive values of C{sub 5} and defocus C{sub 1} results in the most optimal instrument resolution, and optimization of the CTF has been the subject of several studies. Here we describe a simple design procedure for the CTF that results in a most even transfer of information below the resolution limit. We address not only the resolution of the instrument, but also the stability of the CTF in the presence of small disturbances in C{sub 1} and C{sub 3}. We show that resolution can be traded for stability in a rational and transparent fashion. These topics are discussed quantitatively for both weak-phase and strong-phase (or amplitude) objects. The results apply equally to instruments at high electron energy (TEM) and at very low electron energy (LEEM), as the basic optical properties of the imaging lenses are essentially identical. - Highlights: ► An optimized Contrast Transfer Function for aberration corrected electron microscopes is proposed. ► Based on the properties of the CTF near optimum settings, we address its stability. ► Over some range of parameters resolution can be traded for stability. ► These issues are addressed for weak-phase objects, as well as strong-phase and amplitude object. ► We compare our results with CTF settings previously proposed.

  2. Optimization and stability of the contrast transfer function in aberration-corrected electron microscopy

    International Nuclear Information System (INIS)

    The Contrast Transfer Function (CTF) describes the manner in which the electron microscope modifies the object exit wave function as a result of objective lens aberrations. For optimum resolution in C3-corrected microscopes it is well established that a small negative value of C3, offset by positive values of C5 and defocus C1 results in the most optimal instrument resolution, and optimization of the CTF has been the subject of several studies. Here we describe a simple design procedure for the CTF that results in a most even transfer of information below the resolution limit. We address not only the resolution of the instrument, but also the stability of the CTF in the presence of small disturbances in C1 and C3. We show that resolution can be traded for stability in a rational and transparent fashion. These topics are discussed quantitatively for both weak-phase and strong-phase (or amplitude) objects. The results apply equally to instruments at high electron energy (TEM) and at very low electron energy (LEEM), as the basic optical properties of the imaging lenses are essentially identical. - Highlights: ► An optimized Contrast Transfer Function for aberration corrected electron microscopes is proposed. ► Based on the properties of the CTF near optimum settings, we address its stability. ► Over some range of parameters resolution can be traded for stability. ► These issues are addressed for weak-phase objects, as well as strong-phase and amplitude object. ► We compare our results with CTF settings previously proposed

  3. Guard Cell Chloroplasts Are Essential for Blue Light-Dependent Stomatal Opening in Arabidopsis

    Science.gov (United States)

    Suetsugu, Noriyuki; Takami, Tsuneaki; Ebisu, Yuuta; Watanabe, Harutaka; Iiboshi, Chihoko; Doi, Michio; Shimazaki, Ken-ichiro

    2014-01-01

    Blue light (BL) induces stomatal opening through the activation of H+-ATPases with subsequent ion accumulation in guard cells. In most plant species, red light (RL) enhances BL-dependent stomatal opening. This RL effect is attributable to the chloroplasts of guard cell, the only cells in the epidermis possessing this organelle. To clarify the role of chloroplasts in stomatal regulation, we investigated the effects of RL on BL-dependent stomatal opening in isolated epidermis, guard cell protoplasts, and intact leaves of Arabidopsis thaliana. In isolated epidermal tissues and intact leaves, weak BL superimposed on RL enhanced stomatal opening while BL alone was less effective. In guard cell protoplasts, RL enhanced BL-dependent H+-pumping and DCMU, a photosynthetic electron transport inhibitor, eliminated this effect. RL enhanced phosphorylation levels of the H+-ATPase in response to BL, but this RL effect was not suppressed by DCMU. Furthermore, DCMU inhibited both RL-induced and BL-dependent stomatal opening in intact leaves. The photosynthetic rate in leaves correlated positively with BL-dependent stomatal opening in the presence of DCMU. We conclude that guard cell chloroplasts provide ATP and/or reducing equivalents that fuel BL-dependent stomatal opening, and that they indirectly monitor photosynthetic CO2 fixation in mesophyll chloroplasts by absorbing PAR in the epidermis. PMID:25250952

  4. Thermal analysis and structural Optimization of electron gun for traveling wave tube

    International Nuclear Information System (INIS)

    Steady-state and transient thermal analysis of electron gun for a Ka-band traveling wave tube are theoretically performed with a newly-developed 2 mm cathode model by ANSYS software. The heat flux vector chart and temperature distribution chart as well as warm-up time are also derived. The discrepancy of 2% between simulation results and test results, proves that the finite element method is feasible. The ultimate temperature reached by cathode, at given heater power, remarkably depends on the thermal conduction mechanism through cathode module. Based on the heat flux vector chart, the structure of cathode support sleeve with the highest flux is optimized. After optimization, the temperature of cathode increases 28 ℃ the highest temperature of electron gun increases 27 ℃ and the warm-up time of cathode reduces 40 s under the same given heater power. The optimized structure can effectively shorten the warm-up time of cathode by 33% and thus improve fast warm-up the performance of cathode, enhancing the rapid response capability of traveling wave tube. (authors)

  5. A novel chloroplast-localized protein EMB1303 is required for chloroplast development in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Xiaozhen Huang; Xiaoyan Zhang; Shuhua Yang

    2009-01-01

    To understand the molecular mechanisms underlying chloroplast development, we isolated and characterized the albino mutant emb1303-1 in Arabidopsis. The mutant displayed a severe dwarf phenotype with small albino rosette leaves and short roots on a synthetic medium containing sucrose. It is pigment-deficient and seedling lethal when grown in soil. Embryo development was delayed in the mutant, although seed germination was not significantly im-paired. The plastids of emb1303-1 were arrested in early developmental stages without the classical stack of thylakoid membrane. Genetic and molecular analyses uncovered that the EMB1303 gene encodes a novel chloroplast-localized protein. Mieroarray and RT-PCR analyses revealed that a number of nuclear-and plastid-encoded genes involved in photosynthesis and chloroplast biogenesis were substantially downregulated in the mutant. Moreover, the accu-mulation of several major chloroplast proteins was severely compromised in emb1303-1. These results suggest that EMBI303 is essential for chloroplast development.

  6. Direct chloroplast sequencing: comparison of sequencing platforms and analysis tools for whole chloroplast barcoding.

    Directory of Open Access Journals (Sweden)

    Marta Brozynska

    Full Text Available Direct sequencing of total plant DNA using next generation sequencing technologies generates a whole chloroplast genome sequence that has the potential to provide a barcode for use in plant and food identification. Advances in DNA sequencing platforms may make this an attractive approach for routine plant identification. The HiSeq (Illumina and Ion Torrent (Life Technology sequencing platforms were used to sequence total DNA from rice to identify polymorphisms in the whole chloroplast genome sequence of a wild rice plant relative to cultivated rice (cv. Nipponbare. Consensus chloroplast sequences were produced by mapping sequence reads to the reference rice chloroplast genome or by de novo assembly and mapping of the resulting contigs to the reference sequence. A total of 122 polymorphisms (SNPs and indels between the wild and cultivated rice chloroplasts were predicted by these different sequencing and analysis methods. Of these, a total of 102 polymorphisms including 90 SNPs were predicted by both platforms. Indels were more variable with different sequencing methods, with almost all discrepancies found in homopolymers. The Ion Torrent platform gave no apparent false SNP but was less reliable for indels. The methods should be suitable for routine barcoding using appropriate combinations of sequencing platform and data analysis.

  7. Performance optimization of total momentum filtering double-resonance energy selective electron heat pump

    Science.gov (United States)

    Ding, Ze-Min; Chen, Lin-Gen; Ge, Yan-Lin; Sun, Feng-Rui

    2016-04-01

    A theoretical model for energy selective electron (ESE) heat pumps operating with two-dimensional electron reservoirs is established in this study. In this model, a double-resonance energy filter operating with a total momentum filtering mechanism is considered for the transmission of electrons. The optimal thermodynamic performance of the ESE heat pump devices is also investigated. Numerical calculations show that the heating load of the device with two resonances is larger, whereas the coefficient of performance (COP) is lower than the ESE heat pump when considering a single-resonance filter. The performance characteristics of the ESE heat pumps in the total momentum filtering condition are generally superior to those with a conventional filtering mechanism. In particular, the performance characteristics of the ESE heat pumps considering a conventional filtering mechanism are vastly different from those of a device with total momentum filtering, which is induced by extra electron momentum in addition to the horizontal direction. Parameters such as resonance width and energy spacing are found to be associated with the performance of the electron system.

  8. Optimization of Cone Wall Thickness to Reduce High Energy Electron Generation for Fast-Ignition Scheme

    Science.gov (United States)

    Kojima, Sadaoki; Zhe, Zhang; Sawada, Hiroshi; Firex Team

    2015-11-01

    In Fast Ignition Inertial Confinement Fusion, optimization of relativistic electron beam (REB) accelerated by a high-intensity laser pulse is critical for the efficient core heating. The high-energy tail of the electron spectrum is generated by the laser interaction with a long-scale-length plasma and does not efficiently couple to a fuel core. In the cone-in-shell scheme, long-scale-length plasmas can be produced inside the cone by the pedestal of a high-intensity laser, radiation heating of the inner cone wall and shock wave from an implosion core. We have investigated a relation between the presence of pre-plasma inside the cone and the REB energy distribution using the Gekko XII and 2kJ-PW LFEX laser at the Institute of Laser Engineering. The condition of an inner cone wall was monitored using VISAR and SOP systems on a cone-in-shell implosion. The generation of the REB was measured with an electron energy analyzer and a hard x-ray spectrometer on a separate shot by injecting the LFEX laser in an imploded target. The result shows the strong correlation between the preheat and high-energy tail generation. Optimization of cone-wall thickness for the fast-ignition will be discussed. This work is supported by NIFS, MEXT/JSPS KAKENHI Grant and JSPS Fellows (Grant Number 14J06592).

  9. Functional analysis of chloroplast early light inducible proteins (ELIPs)

    Energy Technology Data Exchange (ETDEWEB)

    Wetzel, Carolyn M

    2005-02-22

    The objectives of this project were to characterize gene expression patterns of early light inducible protein (ELIP) genes in Arabidopsis thaliana and in Lycopersicon esculentum, to identify knock mutants of the 2 ELIP genes in Arabidopsis, and to characterize the effects of the knockouts. Expression in Arabidopsis was studied in response to thylakoid electron transport chain (PETC) capacity, where it was found that there is a signal for expression associated with reduction of the PETC. Expression in response to salt was also studied, with different responses of the two gene copies. Knockout lines for ELIP1 and ELIP2 have been identified and are being characterized. In tomato, it was found that the single-copy ELIP gene is highly expressed in ripening fruit during the chloroplast-to-chromoplast transition. Studies of expression in tomato ripening mutants are ongoing.

  10. Practical Framework for an Electron Beam Induced Current Technique Based on a Numerical Optimization Approach

    Science.gov (United States)

    Yamaguchi, Hideshi; Soeda, Takeshi

    2015-03-01

    A practical framework for an electron beam induced current (EBIC) technique has been established for conductive materials based on a numerical optimization approach. Although the conventional EBIC technique is useful for evaluating the distributions of dopants or crystal defects in semiconductor transistors, issues related to the reproducibility and quantitative capability of measurements using this technique persist. For instance, it is difficult to acquire high-quality EBIC images throughout continuous tests due to variation in operator skill or test environment. Recently, due to the evaluation of EBIC equipment performance and the numerical optimization of equipment items, the constant acquisition of high contrast images has become possible, improving the reproducibility as well as yield regardless of operator skill or test environment. The technique proposed herein is even more sensitive and quantitative than scanning probe microscopy, an imaging technique that can possibly damage the sample. The new technique is expected to benefit the electrical evaluation of fragile or soft materials along with LSI materials.

  11. Specialty Task Force: A Strategic Component to Electronic Health Record (EHR) Optimization.

    Science.gov (United States)

    Romero, Mary Rachel; Staub, Allison

    2016-01-01

    Post-implementation stage comes after an electronic health record (EHR) deployment. Analyst and end users deal with the reality that some of the concepts and designs initially planned and created may not be complementary to the workflow; creating anxiety, dissatisfaction, and failure with early adoption of system. Problems encountered during deployment are numerous and can vary from simple to complex. Redundant ticket submission creates backlog for Information Technology personnel resulting in delays in resolving concerns with EHR system. The process of optimization allows for evaluation of system and reassessment of users' needs. A solid and well executed optimization infrastructure can help minimize unexpected end-user disruptions and help tailor the system to meet regulatory agency goals and practice standards. A well device plan to resolve problems during post implementation is necessary for cost containment and to streamline communication efforts. Creating a specialty specific collaborative task force is efficacious and expedites resolution of users' concerns through a more structured process. PMID:27332478

  12. Posttranslational Modifications of Chloroplast Proteins: An Emerging Field.

    Science.gov (United States)

    Lehtimäki, Nina; Koskela, Minna M; Mulo, Paula

    2015-07-01

    Posttranslational modifications of proteins are key effectors of enzyme activity, protein interactions, targeting, and turnover rate, but despite their importance, they are still poorly understood in plants. Although numerous reports have revealed the regulatory role of protein phosphorylation in photosynthesis, various other protein modifications have been identified in chloroplasts only recently. It is known that posttranslational N(α)-acetylation occurs in both nuclear- and plastid-encoded chloroplast proteins, but the physiological significance of this acetylation is not yet understood. Lysine acetylation affects the localization and activity of key metabolic enzymes, and it may work antagonistically or cooperatively with lysine methylation, which also occurs in chloroplasts. In addition, tyrosine nitration may help regulate the repair cycle of photosystem II, while N-glycosylation determines enzyme activity of chloroplastic carbonic anhydrase. This review summarizes the progress in the research field of posttranslational modifications of chloroplast proteins and points out the importance of these modifications in the regulation of chloroplast metabolism. PMID:25911530

  13. Origin of a chloroplast protein importer

    OpenAIRE

    Bölter, Bettina; Soll, Jürgen; Schulz, Alexander; Hinnah, Silke; Wagner, Richard

    1998-01-01

    During evolution, chloroplasts have relinquished the majority of their genes to the nucleus. The products of transferred genes are imported into the organelle with the help of an import machinery that is distributed across the inner and outer plastid membranes. The evolutionary origin of this machinery is puzzling because, in the putative predecessors, the cyanobacteria, the outer two membranes, the plasma membrane, and the lipopolysaccharide layer lack a functionally similar protein import s...

  14. Process for Managing and Optimizing Radiology Work Flow in the Electronic Heath Record Environment.

    Science.gov (United States)

    Sachs, Peter B; Long, Graham

    2016-02-01

    Electronic health record (EHR) implementation has dramatically impacted all facets of radiology workflow. Many departments find themselves unprepared for the multiple issues that surface following EHR deployment and the ongoing need for workflow optimization. This paper reviews the structure and processes utilized by the team, developed at the University of Colorado Hospital to evaluate, prioritize, and implement requests for workflow repairs and improvements within the EHR. The evolution of this team as the academic hospital formed a health system with two community hospital sites is also described. This structure may serve as a useful template for others considering EHR deployment or struggling to manage radiology workflow within an existing EHR environment. PMID:26296949

  15. Expressing PHB synthetic genes through chloroplast genetic engineering

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Chloroplast integration and expression vector containing expression cassettes for phbB, phbA, phbC and aadA genes was constructed and bombarded into the tobacco chloroplast genome. Transplastomic plants were analyzed with PCR and Southern blot. Their homoplastomy was also judged. Northern dot and RT-PCR analysis were employed to investigate transgene expression at transcriptional level. The results indicate that the chloroplast transformation system is compatible for poly-3-hydroxybutyrate (PHB) production.

  16. Optimization Of Cms Endcap Muon Electronics For Major Physics Goals At Lhc

    CERN Document Server

    Vasilev, A

    2000-01-01

    A Large Hadron Collider (LHC) is expected to discover the Higgs particle(s) and will search for new physics beyond Standard Model (SM). However, the LHC environment is the most challenging one in High Energy Physics (HEP) with respect to the range of physics events and their expected rates. An optimized per major LHC physics goals approach to Compact Muon Solenoid (CMS) endcap front-end and readout electronics is investigated. This electronics is based on a low-noise Logarithmic Charge-to-Time and Time- to-Digital Converters that have very low readout latency. Extensive measurements and simulations were conducted not only to prove fulfillment of the design objectives but also to justify a radical change from the baseline approach. Far more superior performance of these circuits allows for digital readout architecture that will solve readout of Cathode Strip Chambers (CSC) problems such as event rate capability, resolution, integration density, radiation hardness and can potentially greatly simplify search for...

  17. Complex chloroplast RNA metabolism: just debugging the genetic programme?

    Directory of Open Access Journals (Sweden)

    Schmitz-Linneweber Christian

    2008-08-01

    Full Text Available Abstract Background The gene expression system of chloroplasts is far more complex than that of their cyanobacterial progenitor. This gain in complexity affects in particular RNA metabolism, specifically the transcription and maturation of RNA. Mature chloroplast RNA is generated by a plethora of nuclear-encoded proteins acquired or recruited during plant evolution, comprising additional RNA polymerases and sigma factors, and sequence-specific RNA maturation factors promoting RNA splicing, editing, end formation and translatability. Despite years of intensive research, we still lack a comprehensive explanation for this complexity. Results We inspected the available literature and genome databases for information on components of RNA metabolism in land plant chloroplasts. In particular, new inventions of chloroplast-specific mechanisms and the expansion of some gene/protein families detected in land plants lead us to suggest that the primary function of the additional nuclear-encoded components found in chloroplasts is the transgenomic suppression of point mutations, fixation of which occurred due to an enhanced genetic drift exhibited by chloroplast genomes. We further speculate that a fast evolution of transgenomic suppressors occurred after the water-to-land transition of plants. Conclusion Our inspections indicate that several chloroplast-specific mechanisms evolved in land plants to remedy point mutations that occurred after the water-to-land transition. Thus, the complexity of chloroplast gene expression evolved to guarantee the functionality of chloroplast genetic information and may not, with some exceptions, be involved in regulatory functions.

  18. Nanophotonics of Chloroplasts for Bio-Inspired Solar Energy Materials

    Science.gov (United States)

    Gourley, Paul L.; Gourley, Cheryl R.

    2011-03-01

    In the search for new energy sources, lessons can be learned from chloroplast photonics. The nano-architecture of chloroplasts is remarkably well-adapted to mediate sunlight interactions for efficient energy conversion. We carried out experiments with chloroplasts isolated from spinach and leaf lettuce to elucidate the relationship between nano-architecture, biomolecular composition and photonic properties. We obtained high-resolution microscopic images of single chloroplasts to identify geometries of chloroplasts and interior grana. We performed micro-spectroscopy to identify strengths of absorption and fluorescence transitions and related them to broadband reflectance and transmittance spectra of whole leaf structures. Finally, the nonlinear optical properties were investigated with nanolaser spectroscopy by placing chloroplasts into micro-resonators and optically pumping. These spectra reveal chloroplast photonic modes and allow measurement of single chloroplast light scattering cross section, polarizability, and refractive index. The nanolaser spectra recorded at increasing pump powers enabled us to observe non-linear optics, photon dynamics, and stimulated emission from single chloroplasts. All of these experiments provide insight into plant photonics and inspiration of paradigms for synthetic biomaterials to harness sunlight in new ways.

  19. Transverse pulse shaping and optimization of a tapered hard X-ray free electron laser

    CERN Document Server

    Emma, Claudio; Wu, Juhao

    2014-01-01

    Multidimensional optimization schemes for TW hard X-Ray free electron lasers are applied to the cases of transversely uniform and parabolic electron beam distributions and compared to examples of transversely Gaussian beams. The optimizations are performed for a $200$m undulator and a resonant wavelength of $\\lambda_r=1.5\\AA $ using the fully 3-dimensional FEL particle code GENESIS. Time dependent simulations showed that the maximum radiation power is larger for flatter transverse distributions due to enhanced optical guiding in the tapered section of the undulator. For a transversely Gaussian beam the maximum output power was found to be $\\text{P}_{max}$=$1.56$ TW compared to $2.26$ TW for the parabolic case and $2.63$ TW for the uniform case. Spectral data also showed a 30-70$\\%$ reduction in energy deposited in the sidebands for the uniform and parabolic beams compared with a Gaussian. An analysis of the maximum power as a function of detuning from resonance shows that redshifting the central wavelength by...

  20. Digital pulse processing and optimization of the front-end electronics for nuclear instrumentation

    International Nuclear Information System (INIS)

    This article describes an algorithm developed for the digital processing of signals provided by a high-efficiency well-type NaI(Tl) detector used to apply the 4πγ technique. In order to achieve a low-energy threshold, a new front-end electronics has been specifically designed to optimize the coupling to an analog-to-digital converter (14 bit, 125 MHz) connected to a digital development kit produced by Altera®. The digital pulse processing is based on an IIR (Infinite Impulse Response) approximation of the Gaussian filter (and its derivatives) that can be applied to the real-time processing of digitized signals. Based on measurements obtained with the photon emissions generated by an 241Am source, the energy threshold is estimated to be equal to ∼2 keV corresponding to the physical threshold of the NaI(Tl) detector. An algorithm developed for a Silicon Drift Detector used for low-energy x-ray spectrometry is also described. In that case, the digital pulse processing is specifically designed for signals provided by a reset-type preamplifier (55Fe source). - Highlights: • Digital pulse processing based on a recursive implementation of a Gaussian filter. • Optimization of the front-end electronics for the coupling to the ADC. • Improvement of detection threshold of a high-efficiency well-type NaI(Tl) detector. • Digital processing applied to a Si drift detector with reset-type preamplifier

  1. Multiobjective Genetic Algorithms Program for the Optimization of an OTA for Front-End Electronics

    Directory of Open Access Journals (Sweden)

    Abdelghani Dendouga

    2014-01-01

    Full Text Available The design of an interface to a specific sensor induces costs and design time mainly related to the analog part. So to reduce these costs, it should have been standardized like digital electronics. The aim of the present work is the elaboration of a method based on multiobjectives genetic algorithms (MOGAs to allow automated synthesis of analog and mixed systems. This proposed methodology is used to find the optimal dimensional transistor parameters (length and width in order to obtain operational amplifier performances for analog and mixed CMOS-(complementary metal oxide semiconductor- based circuit applications. Six performances are considered in this study, direct current (DC gain, unity-gain bandwidth (GBW, phase margin (PM, power consumption (P, area (A, and slew rate (SR. We used the Matlab optimization toolbox to implement the program. Also, by using variables obtained from genetic algorithms, the operational transconductance amplifier (OTA is simulated by using Cadence Virtuoso Spectre circuit simulator in standard TSMC (Taiwan Semiconductor Manufacturing Company RF 0.18 μm CMOS technology. A good agreement is observed between the program optimization and electric simulation.

  2. Optimized quantum sensing with a single electron spin using real-time adaptive measurements

    Science.gov (United States)

    Bonato, C.; Blok, M. S.; Dinani, H. T.; Berry, D. W.; Markham, M. L.; Twitchen, D. J.; Hanson, R.

    2016-03-01

    Quantum sensors based on single solid-state spins promise a unique combination of sensitivity and spatial resolution. The key challenge in sensing is to achieve minimum estimation uncertainty within a given time and with high dynamic range. Adaptive strategies have been proposed to achieve optimal performance, but their implementation in solid-state systems has been hindered by the demanding experimental requirements. Here, we realize adaptive d.c. sensing by combining single-shot readout of an electron spin in diamond with fast feedback. By adapting the spin readout basis in real time based on previous outcomes, we demonstrate a sensitivity in Ramsey interferometry surpassing the standard measurement limit. Furthermore, we find by simulations and experiments that adaptive protocols offer a distinctive advantage over the best known non-adaptive protocols when overhead and limited estimation time are taken into account. Using an optimized adaptive protocol we achieve a magnetic field sensitivity of 6.1 ± 1.7 nT Hz-1/2 over a wide range of 1.78 mT. These results open up a new class of experiments for solid-state sensors in which real-time knowledge of the measurement history is exploited to obtain optimal performance.

  3. An optimized methodology to analyze biopolymer capsules by environmental scanning electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Conforto, Egle, E-mail: egle.conforto@univ-lr.fr [LaSIE UMR 7356 CNRS-ULR, Université de La Rochelle, UFR Sciences, Avenue Michel Crepeau, 17042 La Rochelle (France); Joguet, Nicolas [Equipe Approches Moléculaires Environnement-Santé, LIENSs, UMR 7266 CNRS-ULR, Université de La Rochelle, UFR Sciences, Avenue Michel Crepeau, 17042 La Rochelle (France); Buisson, Pierre [INNOV' IA, 4 rue Samuel Champlain, Z.I. Chef de Baie, 17000 La Rochelle (France); Vendeville, Jean-Eudes; Chaigneau, Carine [IDCAPS, filiale R and D INNOV' IA, 4 rue Samuel Champlain, Z.I. Chef de Baie, 17000 La Rochelle (France); Maugard, Thierry [Equipe Approches Moléculaires Environnement-Santé, LIENSs, UMR 7266 CNRS-ULR, Université de La Rochelle, UFR Sciences, Avenue Michel Crepeau, 17042 La Rochelle (France)

    2015-02-01

    The aim of this paper is to describe an optimized methodology to study the surface characteristics and internal structure of biopolymer capsules using scanning electron microscopy (SEM) in environmental mode. The main advantage of this methodology is that no preparation is required and, significantly, no metallic coverage is deposited on the surface of the specimen, thus preserving the original capsule shape and its surface morphology. This avoids introducing preparation artefacts which could modify the capsule surface and mask information concerning important feature like porosities or roughness. Using this method gelatin and mainly fatty coatings, difficult to be analyzed by standard SEM technique, unambiguously show fine details of their surface morphology without damage. Furthermore, chemical contrast is preserved in backscattered electron images of unprepared samples, allowing visualizing the internal organization of the capsule, the quality of the envelope, etc.… This study provides pointers on how to obtain optimal conditions for the analysis of biological or sensitive material, as this is not always studied using appropriate techniques. A reliable evaluation of the parameters used in capsule elaboration for research and industrial applications, as well as that of capsule functionality is provided by this methodology, which is essential for the technological progress in this domain. - Highlights: • We optimized a methodology using ESEM to analyze biopolymer capsules. • This methodology allows analyzing original surface samples without any preparation. • No preparation artefact are introduced which would mask important surface details. • Morphological details and chemical contrast from the original surface are preserved. • Capsule shape, volume, surface roughness and coating quality were reliably evaluated.

  4. An optimized methodology to analyze biopolymer capsules by environmental scanning electron microscopy

    International Nuclear Information System (INIS)

    The aim of this paper is to describe an optimized methodology to study the surface characteristics and internal structure of biopolymer capsules using scanning electron microscopy (SEM) in environmental mode. The main advantage of this methodology is that no preparation is required and, significantly, no metallic coverage is deposited on the surface of the specimen, thus preserving the original capsule shape and its surface morphology. This avoids introducing preparation artefacts which could modify the capsule surface and mask information concerning important feature like porosities or roughness. Using this method gelatin and mainly fatty coatings, difficult to be analyzed by standard SEM technique, unambiguously show fine details of their surface morphology without damage. Furthermore, chemical contrast is preserved in backscattered electron images of unprepared samples, allowing visualizing the internal organization of the capsule, the quality of the envelope, etc.… This study provides pointers on how to obtain optimal conditions for the analysis of biological or sensitive material, as this is not always studied using appropriate techniques. A reliable evaluation of the parameters used in capsule elaboration for research and industrial applications, as well as that of capsule functionality is provided by this methodology, which is essential for the technological progress in this domain. - Highlights: • We optimized a methodology using ESEM to analyze biopolymer capsules. • This methodology allows analyzing original surface samples without any preparation. • No preparation artefact are introduced which would mask important surface details. • Morphological details and chemical contrast from the original surface are preserved. • Capsule shape, volume, surface roughness and coating quality were reliably evaluated

  5. Simulation study on equivalent dose field of electron beam irradiation flue gas desulfurization and denitrification model and its parameters optimization

    International Nuclear Information System (INIS)

    In an electron beam irradiation flue gas desulfurization and denitrification technical model, the track and the equivalent dose field of electron beams with different inject energy were simulated with Geant4 toolkit. Simulation results show that electron beam with 1.75 MeV matches with 1000 MW(e) level power plant flue gas desulfurization and denitrification technical design. The simulation results will be beneficial to the engineering design and the accelerator parameter optimization. (authors)

  6. Matrix-product-state method with local basis optimization for nonequilibrium electron-phonon systems

    Science.gov (United States)

    Heidrich-Meisner, Fabian; Brockt, Christoph; Dorfner, Florian; Vidmar, Lev; Jeckelmann, Eric

    We present a method for simulating the time evolution of quasi-one-dimensional correlated systems with strongly fluctuating bosonic degrees of freedom (e.g., phonons) using matrix product states. For this purpose we combine the time-evolving block decimation (TEBD) algorithm with a local basis optimization (LBO) approach. We discuss the performance of our approach in comparison to TEBD with a bare boson basis, exact diagonalization, and diagonalization in a limited functional space. TEBD with LBO can reduce the computational cost by orders of magnitude when boson fluctuations are large and thus it allows one to investigate problems that are out of reach of other approaches. First, we test our method on the non-equilibrium dynamics of a Holstein polaron and show that it allows us to study the regime of strong electron-phonon coupling. Second, the method is applied to the scattering of an electronic wave packet off a region with electron-phonon coupling. Our study reveals a rich physics including transient self-trapping and dissipation. Supported by Deutsche Forschungsgemeinschaft (DFG) via FOR 1807.

  7. Tools for regulated gene expression in the chloroplast of Chlamydomonas.

    Science.gov (United States)

    Rochaix, Jean-David; Surzycki, Raymond; Ramundo, Silvia

    2014-01-01

    The green unicellular alga Chlamydomonas reinhardtii has emerged as a very attractive model system for chloroplast genetic engineering. Algae can be transformed readily at the chloroplast level through bombardment of cells with a gene gun, and transformants can be selected using antibiotic resistance or phototrophic growth. An inducible chloroplast gene expression system could be very useful for several reasons. First, it could be used to elucidate the function of essential chloroplast genes required for cell growth and survival. Second, it could be very helpful for expressing proteins which are toxic to the algal cells. Third, it would allow for the reversible depletion of photosynthetic complexes thus making it possible to study their biogenesis in a controlled fashion. Fourth, it opens promising possibilities for hydrogen production in Chlamydomonas. Here we describe an inducible/repressible chloroplast gene expression system in Chlamydomonas in which the copper-regulated Cyc6 promoter drives the expression of the nuclear Nac2 gene encoding a protein which is targeted to the chloroplast where it acts specifically on the chloroplast psbD 5'-untranslated region and is required for the stable accumulation of the psbD mRNA and photosystem II. The system can be used for any chloroplast gene or transgene by placing it under the control of the psbD 5'-untranslated region. PMID:24599871

  8. Coassembly of Photosystem II and ATPase as Artificial Chloroplast for Light-Driven ATP Synthesis.

    Science.gov (United States)

    Feng, Xiyun; Jia, Yi; Cai, Peng; Fei, Jinbo; Li, Junbai

    2016-01-26

    Adenosine triphosphate (ATP) is one of the most important energy sources in living cells, which can drive serial key biochemical processes. However, generation of a proton gradient for ATP production in an artificial way poses a great challenge. In nature, photophosphorylation occurring in chloroplasts is an ideal prototype of ATP production. In this paper we imitate the light-to-ATP conversion process occurring in the thylakoid membrane by construction of FoF1-ATPase proteoliposome-coated PSII-based microspheres with well-defined core@shell structures using molecular assembly. Under light illumination, PSII can split water into protons, oxygen, and electrons and can generate a proton gradient for ATPase to produce ATP. Thus, an artificially designed chloroplast for PSII-driven ATP synthesis is realized. This biomimetic system will help to understand the photophosphorylation process and may facilitate the development of ATP-driven devices by remote light control. PMID:26615669

  9. In vitro induction, isolation and transfer of chloroplast mutations in Nicotiana

    International Nuclear Information System (INIS)

    Protoplast cultures of Nicotiana plumbaginifolia have been used for the isolation of mutants resistant to antibiotics and to photosynthesis-inhibiting herbicides. The effectiveness of N-ethyl-N-nitrosourea in inducing different chloroplast mutations, establishing proper selective conditions in cell cultures, plant regeneration from resistant cell lines and inheritance of these markers are presented. Bacterial protein-synthesis inhibitors (streptomycin and lincomycin) were used in the selection of a large number of chloroplast mutants under standard culture conditions, while special 'photomixotrophic' culture conditions, for selecting mutants resistant to photosynthesis-inhibiting herbicides, had to be established. Under these culture conditions, the primary symptom of photosynthetic electron-transport inhibition by herbicides (bleaching) can be observed and selection for resistance can be carried out. Protoplast fusion has been shown to be suitable for the 'rescue' of mutant plastids from an undesirable nuclear background, from transfer into a different background, or even transfer into a completely different species. (author)

  10. Chloroplast division during leaf development of Xanthium pensylvanicum Wallr. (Compositae

    Directory of Open Access Journals (Sweden)

    Roman Maksymowych

    2014-02-01

    Full Text Available Division and growth of chloroplasts was studied during leaf development of Xanthium pensylvanicum at various stages of development represented by the leaf plastochron index.Between leaf plastochron indices -1.00 and 2.56 chloroplast division was observed with little enlargement. Between 2.50 and 5.00 chloroplasts enlarged in diameter with an average rate of 0.21 µm per day. At leaf plastochron index 5.00 chloroplasts attained their mature size of 6.12 µm. No chloroplast division was found after leaf plastochron index 2.50. A change in shape of plastids from spherical proplastids to discoidal accompanied their growth during stages 2.50 and 5.00.

  11. The complete chloroplast genome of the Dendrobium strongylanthum (Orchidaceae: Epidendroideae).

    Science.gov (United States)

    Li, Jing; Chen, Chen; Wang, Zhe-Zhi

    2016-07-01

    Complete chloroplast genome sequence is very useful for studying the phylogenetic and evolution of species. In this study, the complete chloroplast genome of Dendrobium strongylanthum was constructed from whole-genome Illumina sequencing data. The chloroplast genome is 153 058 bp in length with 37.6% GC content and consists of two inverted repeats (IRs) of 26 316 bp. The IR regions are separated by large single-copy region (LSC, 85 836 bp) and small single-copy (SSC, 14 590 bp) region. A total of 130 chloroplast genes were successfully annotated, including 84 protein coding genes, 38 tRNA genes, and eight rRNA genes. Phylogenetic analyses showed that the chloroplast genome of Dendrobium strongylanthum is related to that of the Dendrobium officinal. PMID:26153739

  12. Two methods for solving optimization problems arising in electronic measurements and electrical engineering

    CERN Document Server

    Sergeyev, Yaroslav D; Grimaldi, Domenico; Molinaro, Anna

    2011-01-01

    In this paper we introduce a common problem in electronic measurements and electrical engineering: finding the first root from the left of an equation in the presence of some initial conditions. We present examples of electrotechnical devices (analog signal filtering), where it is necessary to solve it. Two new methods for solving this problem, based on global optimization ideas, are introduced. The first uses the exact a priori given global Lipschitz constant for the first derivative. The second method adaptively estimates local Lipschitz constants during the search. Both algorithms either find the first root from the left or determine the global minimizers (in the case when the objective function has no roots). Sufficient conditions for convergence of the new methods to the desired solution are established in both cases. The results of numerical experiments for real problems and a set of test functions are also presented.

  13. 2-Dimensional CFD Simulation and Correlation Development for Optimization of Fin Heatsinks in Electronic Cooling

    Institute of Scientific and Technical Information of China (English)

    Jing YANG; Li WANG; Huazhi LI

    2001-01-01

    CFD has penetrated into the field of electronic cooling for some time. Both parallel and staggered plate fin heatsinks are widely used in modern computers. This paper presents the ways to make most use of CFD in optimization design of those heatsinks: the flow and heat transfer of staggered and parallel plate fm heatsinks of various geometry were simulated by using Fluent 5.0 commercial CFD code. Based on 60 different simulation solutions, two correlations, concerning Nusselt number and friction factor as the functions of geometrical and operational parameters of the heatsinks were developed. The presentation parameter examination was also performed by comparing the numerical solutions with the analytical solutions of parallel plate arrays, showing that the correct parameters are used in the correlations.

  14. Optimizing the CEBAF Injector for Beam Operation with a Higher Voltage Electron Gun

    CERN Document Server

    Hannon, F E; Kazimi, R

    2011-01-01

    Recent developments in the DC gun technology used at CEBAF have allowed an increase in operational voltage from 100kV to 130kV. In the near future this will be extended further to 200kV with the purchase of a new power supply. The injector components and layout at this time have been designed specifically for 100kV operation. It is anticipated that with an increase in gun voltage and optimization of the layout and components for 200kV operation, that the electron bunch length and beam brightness can be improved upon. This paper explores some upgrade possibilities for a 200kV gun CEBAF injector through beam dynamic simulations.

  15. On-line optimization of intraoperative electron beam radiotherapy of the breast

    International Nuclear Information System (INIS)

    Purpose: To optimize the dose delivery to the breast lumpectomy target treated with intraoperative electron beam radiotherapy (IOERT). Materials and methods: Two tools have been developed in our MU calculation software NEMO X to improve the dose homogeneity and the in-vivo dosimetry effectiveness for IOERT treatments. Given the target (tumor bed) thickness measured by the surgeon, NEMO X can provide auto dose normalization to cover 95% of the target volume with 95% of the prescription dose (PD) and a “best guess” of the expected dosimeter dose (EDD) for a deep seated in-vivo dosimeter. The tools have been validated with the data of 91 patients treated with IOERT on a LIAC mobile accelerator. In-vivo dosimetry has been performed with microMOSFETs positioned on the shielding disk inserted between the tumor bed and the chest wall. Results: On average the auto normalization showed to provide better results if compared to conventional normalization rules in terms of mean target dose (|MTD–PD|/PD ⩽ 5% in 95% vs. 53% of pts) and V107 percentage (〈V107〉 = 19% vs. 32%). In-vivo dosimetry MOSFET dose (MD) showed a better correlation with the EDD guessed by our tool than just by assuming that EDD = PD (|MD–EDD|/EDD ⩽ 5% in 57 vs. 26% of pts). Conclusions: NEMO X provides two useful tools for the on-line optimization of the dose delivery in IOERT. This optimization can help to reduce unnecessary large over-dosage regions and allows introducing reliable action levels for in-vivo dosimetry.

  16. Optimization

    CERN Document Server

    Pearce, Charles

    2009-01-01

    Focuses on mathematical structure, and on real-world applications. This book includes developments in several optimization-related topics such as decision theory, linear programming, turnpike theory, duality theory, convex analysis, and queuing theory.

  17. An optimized electronic device for solar power harvesting dedicated to wireless sensor networks

    Energy Technology Data Exchange (ETDEWEB)

    Le Cam, Vincent; Le Maulf, Regis; Lemarchand, Laurent; Martin, William; Le Pen, Mathieu [LUNAM Univ., Bouguenais (France). IFSTTAR, MACS Dept.

    2012-07-01

    For economics as for practical reasons, this last decade, the use and dissemination of wireless sensor networks (WSN) became obvious; particularly in structural heath monitoring (SHM) use-cases where distances between sensors could be long and access to the structure quite difficult. Even if efforts are leaded to design small components and RF modules that ask for low-power, the need of an external source is often necessary. After have acquired knowledge in solar cells as in batteries technologies and methods to control charge/discharge phases as in optimizing algorithms, IFSTTAR laboratory has designed an electronic device that integrates those progress. This electronic device has a quite generic mission: for a panel of batteries chemistry (Lithium, NiMh) and a panel of solar cells sources (frome mW to some W), the system acts as an improved battery charger whatever the load ask for power. The system applies control algorithms based on battery capacity and chemistry profile. It also applies the MPPT (Maximum Power Point Tracking) algorithm. At any time, battery State Of Charge (SOC) can be requested via I2C bus as well as a warning signal is output when SOC becomes critical. Through standard pin connectors and a simple I2C interface, the system can be used by many wireless devices (sensors) that have to run autonomously. After the presentation of this system, a focus on its application on a real use-case will be given. (orig.)

  18. Optimizing design for the maze exit of a 10-MeV electron irradiation accelerator

    International Nuclear Information System (INIS)

    Background: Irradiation accelerator is being used more and more widely, but the optimizing of radiation shielding is always a problem to be solved. Purpose: To make the dose rates of the maze exit lower and the cost to achieve it less, it is of great significance to design a shielding which is cheap and effective. Methods: The radiation dose rates at different maze exits of a 10-MeV industrial electron linear accelerator were compared by formula and Monte Carlo (Fluka) method. A real-time measurement system composed of Mini Digital Data Logging (Mini-DDL) and Gamma detectors was also used. Results: With one comer added to the exit, another scattering would be generated. The dose rate of exit before changing was 3-4 μGy·h-1 while it was 200 nGy·h-1 after that. Conclusion: The radiation dose rate at the exit will be reduced by one order of magnitude because of another scattering generated by the added turn to the maze exit. All of these do not increase any additional cost and conform to the ALARA (as low as reasonably achievable) principle. It provides a good reference for the future design of shielding for industrial electron linear accelerator. (authors)

  19. The electron-photon decay of Higgs boson. Optimization and calibration of electromagnetic calorimeter of ATLAS experiment

    International Nuclear Information System (INIS)

    ATLAS is one of the two large experiments which will be placed along the LHC, the CERN's future proton-proton collider. The search for Higgs boson is one of its objectives. The Higgs boson is introduced in the Standard Model to explain the electroweak symmetry breaking and the fermions masses. The hadronic background naturally generated by the collider, constraints to look for the photonic and leptonic Higgs boson decay modes, especially in its electronic mode. In this perspective, the ATLAS electromagnetic calorimeter should be specifically optimized and calibrated. The optimization bears on the readout electronics to minimize the measurement smearing introduced by radiations, pile-up noise, electronics noise, as well as, quantization noise. We will see in this thesis that the simultaneous use of warm preamplifiers, of optimal filtering techniques and of multi-gains system can fulfill such an optimization. Calibrating the electromagnetic calorimeter consists in determining the correspondence between signals coming from the calorimeter and energies of electrons and photons at their creation. If a first calibration can be obtained in test-beam area and transported in situ by using an electronic calibration system, final correction should be done. We will see in this thesis that the use of a physics signal, Z0 -> e+e-, as an absolute calibrating signal can perform such a final adjustment. (author)

  20. Expression of dengue-3 premembrane and envelope polyprotein in lettuce chloroplasts.

    Science.gov (United States)

    Kanagaraj, Anderson Paul; Verma, Dheeraj; Daniell, Henry

    2011-07-01

    Dengue is an acute febrile viral disease with >100 million infections occurring each year and more than half of the world population is at risk. Global resurgence of dengue in many urban centers of the tropics is a major concern. Therefore, development of a successful vaccine is urgently needed that is economical and provide long-lasting protection from dengue virus infections. In this manuscript, we report expression of dengue-3 serotype polyprotein (prM/E) consisting of part of capsid, complete premembrane (prM) and truncated envelope (E) protein in an edible crop lettuce. The dengue sequence was controlled by endogenous Lactuca sativa psbA regulatory elements. PCR and Southern blot analysis confirmed transgene integration into the lettuce chloroplast genome via homologous recombination at the trnI/trnA intergenic spacer region. Western blot analysis showed expression of polyprotein prM/E in different forms as monomers (~65 kDa) or possibly heterodimers (~130 kDa) or multimers. Multimers were solubilized into monomers using guanidine hydrochloride. Transplastomic lettuce plants expressing dengue prM/E vaccine antigens grew normally and transgenes were inherited in the T1 progeny without any segregation. Transmission electron microscopy showed the presence of virus-like particles of ~20 nm diameter in chloroplast extracts of transplastomic lettuce expressing prM/E proteins, but not in untransformed plants. The prM/E antigens expressed in lettuce chloroplasts should offer a potential source for investigating an oral Dengue vaccine. PMID:21431782

  1. Photosynthetic Characteristics and Ultrastructure of Chloroplast of Cucumber Under Low Light Density in Solar-Greenhouse

    Institute of Scientific and Technical Information of China (English)

    AI Xi-zhen; GUO Yan-kui; CHEN Li-ping; XING Yu-xian

    2004-01-01

    The photosynthetic characteristics and ultrastructure of chloroplast of cucumber in solargreenhouse were studied. The result showed that the photosynthetic rate (Pn), photosynthetic ability (A350), carboxylation efficiency, light saturation point and light compensation point all declined remarkably under lowlight density, indicating that the photosynthetic characteristics of cucumber were closely related to light environment. Under iow light density, the minimal fluorescence (Fo), alterable fluorescence (Fv), photochemical efficiency of PS Ⅱ (Fv/Fm), steady fluorescence in light (Fs), maximal fluorescence (Fm′) and actual efficiency of PS Ⅱ (φPSⅡ)etc increased, indicating that the photochemical activity and efficiency for solar energy transformation enhanced, thus the light proportion used to electron transport also increased. The chlorophyll a, b, a/b and carotenoid of shading leaves decreased. However, the depressed extent of Chl a and Chl a/b were obviously larger than that of Chl b. The number of chloroplast and starch grain in cucumber leaves descended, but that of grana and lamella increased as a shaded result. The size of chloroplast and starch grain of shading leaves minished.

  2. Dual Protein Localization to the Envelope and Thylakoid Membranes Within the Chloroplast.

    Science.gov (United States)

    Klasek, Laura; Inoue, Kentaro

    2016-01-01

    The chloroplast houses various metabolic processes essential for plant viability. This organelle originated from an ancestral cyanobacterium via endosymbiosis and maintains the three membranes of its progenitor. Among them, the outer envelope membrane functions mainly in communication with cytoplasmic components while the inner envelope membrane houses selective transport of various metabolites and the biosynthesis of several compounds, including membrane lipids. These two envelope membranes also play essential roles in import of nuclear-encoded proteins and in organelle division. The third membrane, the internal membrane system known as the thylakoid, houses photosynthetic electron transport and chemiosmotic phosphorylation. The inner envelope and thylakoid membranes share similar lipid composition. Specific targeting pathways determine their defined proteomes and, thus, their distinct functions. Nonetheless, several proteins have been shown to exist in both the envelope and thylakoid membranes. These proteins include those that play roles in protein transport, tetrapyrrole biosynthesis, membrane dynamics, or transport of nucleotides or inorganic phosphate. In this review, we summarize the current knowledge about proteins localized to both the envelope and thylakoid membranes in the chloroplast, discussing their roles in each membrane and potential mechanisms of their dual localization. Addressing the unanswered questions about these dual-localized proteins should help advance our understanding of chloroplast development, protein transport, and metabolic regulation. PMID:26944623

  3. Comparative proteomic analysis of amaranth mesophyll and bundle sheath chloroplasts and their adaptation to salt stress.

    Science.gov (United States)

    Joaquín-Ramos, Ahuitzolt; Huerta-Ocampo, José Á; Barrera-Pacheco, Alberto; De León-Rodríguez, Antonio; Baginsky, Sacha; Barba de la Rosa, Ana P

    2014-09-15

    The effect of salt stress was analyzed in chloroplasts of Amaranthus cruentus var. Amaranteca, a plant NAD-malic enzyme (NAD-ME) type. Morphology of chloroplasts from bundle sheath (BSC) and mesophyll (MC) was observed by transmission electron microscopy (TEM). BSC and MC from control plants showed similar morphology, however under stress, changes in BSC were observed. The presence of ribulose bisphosphate carboxylase/oxygenase (RuBisCO) was confirmed by immunohistochemical staining in both types of chloroplasts. Proteomic profiles of thylakoid protein complexes from BSC and MC, and their changes induced by salt stress were analyzed by blue-native polyacrylamide gel electrophoresis followed by SDS-PAGE (2-D BN/SDS-PAGE). Differentially accumulated protein spots were analyzed by LC-MS/MS. Although A. cruentus photosynthetic tissue showed the Kranz anatomy, the thylakoid proteins showed some differences at photosystem structure level. Our results suggest that A. cruentus var. Amaranteca could be better classified as a C3-C4 photosynthetic plant. PMID:25046763

  4. Gibberellin metabolism in chloroplasts of Pisum sativum L. var. Alaska

    International Nuclear Information System (INIS)

    Little is known about the metabolic control of gibberellin (GA) biosynthesis in higher plants. Recent studies have implicated chloroplasts in the metabolic control of GA metabolism in leaves. Thus chloroplasts from several higher plants have been shown to possess high levels of GA-like activity and appear to be able to localize certain GAs selectivity whilst allowing others to migrate into the cytoplasm. This paper evaluates the ability of chloroplasts to synthesize and interconvert GAs, in an in vitro system developed from plastids of Pisum sativum. The results of detailed analysis of the products are reported

  5. The complete chloroplast genome of Capsicum frutescens (Solanaceae) 1

    OpenAIRE

    Shim, Donghwan; Raveendar, Sebastin; Lee, Jung-Ro; Lee, Gi-An; Ro, Na-Young; Jeon, Young-Ah; Cho, Gyu-Taek; Lee, Ho-Sun; Ma, Kyung-Ho; Chung, Jong-Wook

    2016-01-01

    Premise of the study: We report the complete sequence of the chloroplast genome of Capsicum frutescens (Solanaceae), a species of chili pepper. Methods and Results: Using an Illumina platform, we sequenced the chloroplast genome of C. frutescens. The total length of the genome is 156,817 bp, and the overall GC content is 37.7%. A pair of 25,792-bp inverted repeats is separated by small (17,853 bp) and large (87,380 bp) single-copy regions. The C. frutescens chloroplast genome encodes 132 uniq...

  6. Origins of prokaryotes, eukaryotes, mitochondria, and chloroplasts

    Science.gov (United States)

    Schwartz, R. M.; Dayhoff, M. O.

    1978-01-01

    A computer branching model is used to analyze cellular evolution. Attention is given to certain key amino acids and nucleotide residues (ferredoxin, 5s ribosomal RNA, and c-type cytochromes) because of their commonality over a wide variety of cell types. Each amino acid or nucleotide residue is a sequence in an inherited biological trait; and the branching method is employed to align sequences so that changes reflect substitution of one residue for another. Based on the computer analysis, the symbiotic theory of cellular evolution is considered the most probable. This theory holds that organelles, e.g., mitochondria and chloroplasts invaded larger bodies, e.g., bacteria, and combined functions to form eucaryotic cells.

  7. Dynamics of chloroplast genomes in green plants.

    Science.gov (United States)

    Xu, Jian-Hong; Liu, Qiuxiang; Hu, Wangxiong; Wang, Tingzhang; Xue, Qingzhong; Messing, Joachim

    2015-10-01

    Chloroplasts are essential organelles, in which genes have widely been used in the phylogenetic analysis of green plants. Here, we took advantage of the breadth of plastid genomes (cpDNAs) sequenced species to investigate their dynamic changes. Our study showed that gene rearrangements occurred more frequently in the cpDNAs of green algae than in land plants. Phylogenetic trees were generated using 55 conserved protein-coding genes including 33 genes for photosynthesis, 16 ribosomal protein genes and 6 other genes, which supported the monophyletic evolution of vascular plants, land plants, seed plants, and angiosperms. Moreover, we could show that seed plants were more closely related to bryophytes rather than pteridophytes. Furthermore, the substitution rate for cpDNA genes was calculated to be 3.3×10(-10), which was almost 10 times lower than genes of nuclear genomes, probably because of the plastid homologous recombination machinery. PMID:26206079

  8. Practical lesson of Photosynthesis: A demonstration of Hill reaction in chloroplasts with energy dissipation by fluorescence upon photosystems uncoupling or inhibition by Diuron herbicide

    Directory of Open Access Journals (Sweden)

    Vadim Ravara Viviani

    2016-05-01

    Full Text Available During photosynthesis, the photochemical electron transfer process is easily demonstrated by the Hill reaction, where artificial electron acceptors are reduced by active chloroplasts suspensions in the presence of light.  However, the destiny of luminous energy absorbed by chlorophyll molecules in uncoupled or damaged photosystems is not usually demonstrated. Here we provide an adaptation of the classical Hill reaction using intact spinach chloroplasts, which includes the visualization of energy dissipation by fluorescence in lysed chloroplasts, and a dose/effect response in photosystems inhibited by the herbicide DCMU. This laboratory lesson, which is aimed to biochemistry and biophysics for undergraduate courses of Chemistry, Biological, Environmental and Agricultural Sciences, provides the basic photochemical principles using the classical Hill reaction, and photophysical principles through the visualization of energy dissipation by chlorophyll fluorescence,  improving the understanding of the photosynthetic process, and introducing the concept of fluorescence and its applications as bioanalytical tool to monitor photosynthesis in plants and vegetal ecosystems.

  9. Development of a novel optimization tool for electron linacs inspired by artificial intelligence techniques in video games

    Energy Technology Data Exchange (ETDEWEB)

    Meier, E., E-mail: evelyne.meier@synchrotron.org.a [School of Physics, Monash University, Wellington Rd, Clayton VIC 3800 (Australia) and Australian Synchrotron, 800 Blackburn Rd, Clayton VIC 3168 (Australia) and FERMI-Elettra, Sincrotrone Trieste, S.S. 14 km 163.5 in AREA Science Park, 34012 Basovizza, Trieste (Italy); Biedron, S.G., E-mail: biedron@anl.go [Department of Defense Project Office, Argonne National Laboratory, IL 60439 (United States); FERMI-Elettra, Sincrotrone Trieste, S.S. 14 km 163.5 in AREA Science Park, 34012 Basovizza, Trieste (Italy); LeBlanc, G., E-mail: greg.leblanc@synchrotron.org.a [Australian Synchrotron, 800 Blackburn Rd, Clayton VIC 3168 (Australia); Morgan, M.J., E-mail: Michael.J.Morgan@monash.ed [School of Physics, Monash University, Wellington Rd, Clayton VIC 3800 (Australia)

    2011-03-11

    This paper reports the results of an advanced algorithm for the optimization of electron beam parameters in Free Electron Laser (FEL) Linacs. In the novel approach presented in this paper, the system uses state of the art developments in video games to mimic an operator's decisions to perform an optimization task when no prior knowledge, other than constraints on the actuators is available. The system was tested for the simultaneous optimization of the energy spread and the transmission of the Australian Synchrotron Linac. The proposed system successfully increased the transmission of the machine from 90% to 97% and decreased the energy spread of the beam from 1.04% to 0.91%. Results of a control experiment performed at the new FERMI-Elettra FEL is also reported, suggesting the adaptability of the scheme for beam-based control.

  10. Development of a novel optimization tool for electron linacs inspired by artificial intelligence techniques in video games

    Science.gov (United States)

    Meier, E.; Biedron, S. G.; LeBlanc, G.; Morgan, M. J.

    2011-03-01

    This paper reports the results of an advanced algorithm for the optimization of electron beam parameters in Free Electron Laser (FEL) Linacs. In the novel approach presented in this paper, the system uses state of the art developments in video games to mimic an operator's decisions to perform an optimization task when no prior knowledge, other than constraints on the actuators is available. The system was tested for the simultaneous optimization of the energy spread and the transmission of the Australian Synchrotron Linac. The proposed system successfully increased the transmission of the machine from 90% to 97% and decreased the energy spread of the beam from 1.04% to 0.91%. Results of a control experiment performed at the new FERMI@Elettra FEL is also reported, suggesting the adaptability of the scheme for beam-based control.

  11. Development of a novel optimization tool for electron linacs inspired by artificial intelligence techniques in video games

    International Nuclear Information System (INIS)

    This paper reports the results of an advanced algorithm for the optimization of electron beam parameters in Free Electron Laser (FEL) Linacs. In the novel approach presented in this paper, the system uses state of the art developments in video games to mimic an operator's decisions to perform an optimization task when no prior knowledge, other than constraints on the actuators is available. The system was tested for the simultaneous optimization of the energy spread and the transmission of the Australian Synchrotron Linac. The proposed system successfully increased the transmission of the machine from 90% to 97% and decreased the energy spread of the beam from 1.04% to 0.91%. Results of a control experiment performed at the new FERMI-Elettra FEL is also reported, suggesting the adaptability of the scheme for beam-based control.

  12. Exploring sub-optimal use of an electronic risk assessment tool for venous thromboembolism.

    Science.gov (United States)

    Baysari, Melissa T; Jackson, Nicola; Ramasamy, Sheena; Santiago, Priscila; Xiong, Juan; Westbrook, Johanna; Omari, Abdullah; Day, Richard O

    2016-07-01

    International guidelines and consensus groups recommend using a risk assessment tool (RAT) to assess Venous Thromboembolism (VTE) risk prior to the prescription of prophylaxis. We set out to examine how an electronic RAT was being used (i.e. if by the right clinician, at the right time, for the right purpose) and to identify factors influencing utilization of the RAT. A sample of 112 risk assessments was audited and 12 prescribers were interviewed. The RAT was used as intended in only 40 (35.7%) cases (i.e. completed by a doctor within 24 h of admission, prior to the prescription of prophylaxis). We identified several reasons for sub-optimal use of the RAT, including beliefs about the need for a RAT, poor awareness of the tool, and poor RAT design. If a user-centred approach had been adopted, it is likely that a RAT would not have been implemented or that problematic design issues would have been identified. PMID:26995037

  13. OPTIMIZATION AND CHARACTERIZATION OF ELECTRON BEAM RESIST USING ATOMIC FORCE MICROSCOPY

    Directory of Open Access Journals (Sweden)

    - Sutikno

    2012-01-01

    Full Text Available Resis negatif ma-N 2403 dan 495 K PMMA memiliki resolusi yang baik untuk aplikasi litografi berkas elektron (EBL. Ketebalanresist optimal memainkan peran penting dalam paparan berkas elektron. Oleh karena itu, dalam penelitian ini, ketebalan darikedua resist yang dioptimalkan menggunakan spincoater dalam jangkauan laju spin 1000-6000 rpm. Semakin laju spin meningkat,ketebalan resist menurun juga. Morfologi permukaan resist dikarakterisasi dengan mikroskop gaya atom. Butir butir resist nampakpanjang. Dalam analisis AFM, permukaan profil resist negatif ma-N 2403 dan 495 K PMMA nampak seperti kerucut. Negative resist ma-N 2403 and 495 K PMMA have good resolution for electron beam lithography (EBL application. The optimumresist thickness plays significant role in e-beam exposure. Therefore, in this research, thicknesses of both resists were optimizedusing spincoater within spin speeds of 1000-6000 rpm. As spin speed increased, resist thickness decreased as well. Morphology ofresist surfaces were characterized using atomic force microscopy (AFM. Grains of resist show long grains. In AFM analyses,surface profiles of negative resist ma-N 2403 and 495 K PMMA show cone peaks.Keywords: e-beam resist; spincoater; e-beam lithography

  14. Development of an optimal protocol for the ultrastructural examination of skin by transmission electron microscopy.

    Science.gov (United States)

    Van den Bergh, B A; Swartzendruber, D C; Bos-Van der Geest, A; Hoogstraate, J J; Schrijvers, A H; Boddé, H E; Junginger, H E; Bouwstra, J A

    1997-08-01

    The intercellular lipid bilayers of the stratum corneum provide the permeability barrier of the skin. To perform an electron microscopical examination of the ultrastructure of these bilayers, ruthenium tetroxide fixation is required. In this study an optimal fixation protocol was developed and selected upon comparing seven different fixation procedures, using glutaraldehyde (GA) and the postfixatives ruthenium red, osmium tetroxide (OsO4) and ruthenium tetroxide (RuO4) in combination with potassium ferrocyanide (K4Fe(CN)6) and potassium ferricyanide (K3Fe(CN)6). Instead of fixing skin with either OsO4 or RuO4, these two fixatives were combined in one protocol. In addition, the use of RuRed was introduced and the influence of both K4Fe(CN)6 and K3Fe(CN)6 in combination with RuO4 were examined. Furthermore, we compared two dehydration solvents, methanol and acetone. The most satisfying results were obtained when the skin was prefixed in GA and postfixed in OsO4 and RuO4 with K3Fe(CN)6, i.e. with Fe in its highest oxidation state (Fe3+). No differences were observed between dehydration in methanol and acetone. PMID:9316270

  15. Thermoelectric properties optimization of Fe2VGa by tuning electronic density of states via titanium doping

    International Nuclear Information System (INIS)

    We report the correlation between thermoelectric properties and electronic band structure of thermoelectric Heusler alloy Fe2V1-xTixGa by comparing experimental measurements with theoretical calculations. The electrical resistivity data show that the semiconducting-like behavior of pure Fe2VGa is transformed to a more metallic-like behavior at x = 0.1. Meanwhile, an enhancement of the Seebeck coefficient was observed for all Ti doped specimens at elevated temperatures with a peak value of 57 μV/K for x = 0.05 at 300 K. The experimental results can be elucidated by the calculated band structure, i.e., a gradual shifting of the Fermi level from the middle of the pseudogap to the region of valence bands. With optimized doping, the thermoelectric power factor can be significantly enhanced to 3.95 mW m−1 K−2 at room temperature, which is comparable to the power factors of Bi2Te3-based compounds. The synergy of thermal conductivity reduction due to the alloying effect and the significant increase of the thermoelectric power factor leads to higher order zT values than that of prime Fe2VGa

  16. Optimization of deformations and hoop stresses in TSV liners to boost interconnect reliability in electronic appliances

    Science.gov (United States)

    Juma, Mary Atieno; Zhang, Xuliang; He, Song Bai; Abusabah, Ahmed I. A.

    2015-12-01

    Recently, there has been a lot of research with electronic products because more and different functions are integrated into devices and the final product sizes have to be small to meet the market demand. A lot of research has been done on the (TSVs) Through Silicon Vias. In this paper, through silicon via liners are investigated. The liners: silicon dioxide, polystyrene and polypropylene carbonate are exposed to pressure on their inner surfaces and this yielded hoop stresses within their thickness. Deflections too occurred and this is a proof that deformation really took place. In one of our papers, hoop stresses for the same materials were investigated. The values were a little higher but different for each material used. In this paper, we use global cylindrical, partial cylinder model with different theta in Analysis system 14 to model the through silicon via liners. The values are lower meaning the reliability of the liners have been optimized and boosted. However, silicon dioxide liner had the lowest hoop stress around its circumference and lowest deflection value meaning that it's still one of the most reliable materials in the manufacture of through silicon via liners in the industry; but overdependence can be avoided if the other liners are used too.

  17. Digital pulse processing and optimization of the front-end electronics for nuclear instrumentation.

    Science.gov (United States)

    Bobin, C; Bouchard, J; Thiam, C; Ménesguen, Y

    2014-05-01

    This article describes an algorithm developed for the digital processing of signals provided by a high-efficiency well-type NaI(Tl) detector used to apply the 4πγ technique. In order to achieve a low-energy threshold, a new front-end electronics has been specifically designed to optimize the coupling to an analog-to-digital converter (14 bit, 125 MHz) connected to a digital development kit produced by Altera(®). The digital pulse processing is based on an IIR (Infinite Impulse Response) approximation of the Gaussian filter (and its derivatives) that can be applied to the real-time processing of digitized signals. Based on measurements obtained with the photon emissions generated by an (241)Am source, the energy threshold is estimated to be equal to ~2 keV corresponding to the physical threshold of the NaI(Tl) detector. An algorithm developed for a Silicon Drift Detector used for low-energy x-ray spectrometry is also described. In that case, the digital pulse processing is specifically designed for signals provided by a reset-type preamplifier ((55)Fe source). PMID:24326314

  18. Effect of supplementary VB radiation on chlorophyll synthesis and accumulation of photosystems during chloroplast development in Spirodela oligorrhiza

    International Nuclear Information System (INIS)

    Although the effects of ultraviolet B (UVB, 290-320 nm) radiation have been studied in plants extensively, little is known about the potential impacts on maturation of chloroplasts. To address this problem, the effects of supplementary UVB on chloroplast development were examined in the aquatic higher plant Spirodela oligorrhiza. Dark-grown Spirodela-containing proplastids were exposed to photosynthetically active radiation (PAR) and ultraviolet A (UVA, 320-400 nm), plus supplementary UVB equivalent to 1% of PAR on a photon basis. The biosynthesis and assembly of chlorophyll (Chl) into reaction centers was followed for 4 days in situ by low temperature (77 K) Chl fluorescence. Impacts on chloroplast development were detected after only 1 h incubation in light with supplementary UVB. Fluorescence emission signals from Chl associated with the photosystem (PS) II antenna, PSII reaction centers and PSI reaction centers were detected at the same time with or without UVB, but the magnitude of PS fluorescence was diminished up to 60% in plants incubated in UVB. The Chl content was also lower in UVB-treated plants, but to a lesser degree than anticipated by low temperature fluorescence, suggesting lack of organization and/or association of Chl with PS. Electron transport, measured with room temperature fluorescence induction, was not consistently different in plants exposed to UVB. These results suggest that with UVB, fewer and/or smaller PS form during chloroplast development, but there is not a large inhibition of Chl synthesis or PSII activity. (Author)

  19. Transport of Ions Across the Inner Envelope Membrane of Chloroplasts

    International Nuclear Information System (INIS)

    The technical report outlines the results of nine years of research on how ions cross the inner envelope membrane of chloroplasts. The ions include protons, nitrite, calcium and ferrous iron. Bicarbonate transport was also studied

  20. Chloroplast genome variation in upland and lowland switchgrass

    Science.gov (United States)

    Switchgrass (Panicum virgatum L.) exists at multiple ploidies and two phenotypically distinct ecotypes. To facilitate interploidal comparisons and to understand the extent of sequence variation within existing breeding pools, two complete switchgrass chloroplast genomes were sequenced from individu...

  1. Transport of Ions Across the Inner Envelope Membrane of Chloroplasts

    Energy Technology Data Exchange (ETDEWEB)

    McCarty, R. E.

    2004-06-02

    The technical report outlines the results of nine years of research on how ions cross the inner envelope membrane of chloroplasts. The ions include protons, nitrite, calcium and ferrous iron. Bicarbonate transport was also studied.

  2. Separation of Chloroplast Pigments Using Reverse Phase Chromatography.

    Science.gov (United States)

    Reese, R. Neil

    1997-01-01

    Presents a protocol that uses reverse phase chromatography for the separation of chloroplast pigments. Provides a simple and relatively safe procedure for use in teaching laboratories. Discusses pigment extraction, chromatography, results, and advantages of the process. (JRH)

  3. The complete chloroplast genome sequence of Zanthoxylum piperitum.

    Science.gov (United States)

    Lee, Jonghoon; Lee, Hyeon Ju; Kim, Kyunghee; Lee, Sang-Choon; Sung, Sang Hyun; Yang, Tae-Jin

    2016-09-01

    The complete chloroplast genome sequence of Zanthoxylum piperitum, a plant species with useful aromatic oils in family Rutaceae, was generated in this study by de novo assembly with whole-genome sequence data. The chloroplast genome was 158 154 bp in length with a typical quadripartite structure containing a pair of inverted repeats of 27 644 bp, separated by large single copy and small single copy of 85 340 bp and 17 526 bp, respectively. The chloroplast genome harbored 112 genes consisting of 78 protein-coding genes 30 tRNA genes and 4 rRNA genes. Phylogenetic analysis of the complete chloroplast genome sequences with those of known relatives revealed that Z. piperitum is most closely related to the Citrus species. PMID:26260183

  4. Transfer of the cytochrome P450-dependent dhurrin pathway from Sorghum bicolor into Nicotiana tabacum chloroplasts for light-driven synthesis.

    Science.gov (United States)

    Gnanasekaran, Thiyagarajan; Karcher, Daniel; Nielsen, Agnieszka Zygadlo; Martens, Helle Juel; Ruf, Stephanie; Kroop, Xenia; Olsen, Carl Erik; Motawie, Mohammed Saddik; Pribil, Mathias; Møller, Birger Lindberg; Bock, Ralph; Jensen, Poul Erik

    2016-04-01

    Plant chloroplasts are light-driven cell factories that have great potential to act as a chassis for metabolic engineering applications. Using plant chloroplasts, we demonstrate how photosynthetic reducing power can drive a metabolic pathway to synthesise a bio-active natural product. For this purpose, we stably engineered the dhurrin pathway fromSorghum bicolorinto the chloroplasts ofNicotiana tabacum(tobacco). Dhurrin is a cyanogenic glucoside and its synthesis from the amino acid tyrosine is catalysed by two membrane-bound cytochrome P450 enzymes (CYP79A1 and CYP71E1) and a soluble glucosyltransferase (UGT85B1), and is dependent on electron transfer from a P450 oxidoreductase. The entire pathway was introduced into the chloroplast by integratingCYP79A1,CYP71E1, andUGT85B1into a neutral site of theN. tabacumchloroplast genome. The two P450s and the UGT85B1 were functional when expressed in the chloroplasts and converted endogenous tyrosine into dhurrin using electrons derived directly from the photosynthetic electron transport chain, without the need for the presence of an NADPH-dependent P450 oxidoreductase. The dhurrin produced in the engineered plants amounted to 0.1-0.2% of leaf dry weight compared to 6% in sorghum. The results obtained pave the way for plant P450s involved in the synthesis of economically important compounds to be engineered into the thylakoid membrane of chloroplasts, and demonstrate that their full catalytic cycle can be driven directly by photosynthesis-derived electrons. PMID:26969746

  5. Sequence evidence for the symbiotic origins of chloroplasts and mitochondria

    Science.gov (United States)

    George, D. G.; Hunt, L. T.; Dayhoff, M. O.

    1983-01-01

    The origin of mitochondria and chloroplasts is investigated on the basis of prokaryotic and early-eukaryotic evolutionary trees derived from protein and nucleic-acid sequences by the method of Dayhoff (1979). Trees for bacterial ferrodoxins, 5S ribosomal RNA, c-type cytochromes, the lipid-binding subunit of ATPase, and dihydrofolate reductase are presented and discussed. Good agreement among the trees is found, and it is argued that the mitochondria and chloroplasts evolved by multiple symbiotic events.

  6. Inhibition of chloroplast protein synthesis following light chilling of tomato

    International Nuclear Information System (INIS)

    In the present study we looked at the effects of a high light chill on the pulsed incorporation of 35S methionine into total, stromal, and thylakoid proteins of lightly abraded leaflets of 18-21 day old tomato (Lycopersicon esculentum Mill ca. Floramerica) seedlings. Based on gel fluorographic patterns of marker proteins that are indicative of the net rates of chloroplast and cytoplasmic protein synthesis, there appears to be a nearly complete cessation of chloroplastic protein synthesis. No labeling is observed for either the stromal large subunit of Rubisco or the thylakoid-bound alpha and beta subunits of the coupling factor. One notable exception, however, appears to be the 32 kd, D1 protein. Its net synthetic rate remains high despite the inhibition of other chloroplastically synthesized proteins. The small subunit of Rubicso, LHCP-II, as well as several other proteins of known cytoplasmic origin, were still synthesized, albeit, at lower than control rates. Light chilling of chill-insensitive spinach produced a similar, but less dramatic differential behavior between chloroplastic and cytoplasmic protein synthesis. It appears, in chilling-sensitive plants, that chloroplast protein synthesis exhibits a greater sensitivity to low temperature inhibition than does cytoplasmic protein synthesis and that recovery of chloroplast protein synthesis may play an important role in recovery of photosynthetic activity following chilling

  7. Role of mitochondria in sulfolipid biosynthesis by Euglena chloroplasts

    International Nuclear Information System (INIS)

    Sulfate activation occurs in Euglena mitochondria the authors now find that the sulfate activating enzymes are absent from Euglena chloroplasts. Cells of mutant W10BSmL lacking plastids also lack detectable sulfolipid (SL) when grown on 35SO42- indicating that SL is absent from the mitochondria and is exclusively in the plastids. Plastids alone will convert 35S-cysteine to 35SL in the presence of ATP and Mg2+; light is stimulatory. Under similar conditions, chloroplasts and mitochondria incubated together convert 35SO42- to plastid-localized 35SL but either organelle incubated alone fails to effect this conversion. Unlabeled cysteine blocks SL labeling from sulfate in the mixed incubation; since cysteine is formed from sulfate by Euglena mitochrondria, cysteine (and other compounds) may move from the mitochondrion to the chloroplast to provide the sulfo group for SL formation. Although mitochondria form labeled protein from 35SO42- via cysteine, chloroplasts alone do not form labeled protein from 35SO42-, ATP and Mg2+ in light or darkness; incubation of chloroplasts plus mitochondria under these conditions labels chloroplast protein

  8. Expression of human soluble TRAIL in Chlamydomonas reinhardtii chloroplast

    Institute of Scientific and Technical Information of China (English)

    YANG Zongqi; LI yinü; CHEN Feng; LI Dong; ZHANG Zhifang; LIU Yanxin; ZHENG Dexian; WANG Yong; SHEN Guifang

    2006-01-01

    Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces selectively apoptosis in various tumor cells and virus-infected cells, but rarely in normal cells. A chloroplast expression vector, p64TRAIL, containing the cDNA coding for the soluble TRAIL (sTRAIL), was constructed with clpP-trnL-petB-chlL-rpl23-rpl2 as Chlamydomonas reinhardtii plastid homologous recombinant fragments and spectinomycin-resistant aadA gene as a select marker. The plasmid p64TRAIL was transferred into the chloroplast genome of C. reinhardtii by the biolistic method. Three independently transformed lines were obtained by 100 mg/L spectinomycin selection. PCR amplification, Southern blot analysis of the sTRAIL coding region DNA and cultivation cells in the dark all showed that the exogenous DNA had been integrated into chloroplast genome of C. reinhardtii. Western blot analysis showed that human soluble TRAIL was expressed in C. reinhardtii chloroplast. The densitometric analysis of Western blot indicated that the expressed human sTRAIL protein in the chloroplasts of C. reinhardtii accounted for about 0.43%-0.67% of the total soluble proteins.These experimental results demonstrated the possibility of using transgenic chloroplasts of green alga as bioreactors for production of biopharmaceuticals.

  9. Optimization studies of photo-neutron production in high- metallic targets using high energy electron beam for ADS and transmutation

    Indian Academy of Sciences (India)

    V C Petwal; V K Senecha; K V Subbaiah; H C Soni; S Kotaiah

    2007-02-01

    Monte Carlo calculations have been performed using MCNP code to study the optimization of photo-neutron yield for different electron beam energies impinging on Pb, W and Ta cylindrical targets of varying thickness. It is noticed that photo-neutron yield can be increased for electron beam energies ≥ 100 MeV for appropriate thickness of the target. It is also noticed that it can be maximized by further increasing the thickness of the target. Further, at higher electron beam energy heat gradient in the target decreases, which facilitates easier heat removal from the target. This can help in developing a photo-neutron source based on electron LINAC by choosing appropriate electron beam energy and target thickness to optimize the neutron flux for ADS, transmutation studies and as high energy neutron source etc. Photo-neutron yield for different targets, optimum target thickness and photo-neutron energy spectrum and heat deposition by electron beam for different incident energy is presented.

  10. Can electronic search engines optimize screening of search results in systematic reviews: an empirical study

    Directory of Open Access Journals (Sweden)

    Clifford Tammy J

    2006-02-01

    Full Text Available Abstract Background Most electronic search efforts directed at identifying primary studies for inclusion in systematic reviews rely on the optimal Boolean search features of search interfaces such as DIALOG® and Ovid™. Our objective is to test the ability of an Ultraseek® search engine to rank MEDLINE® records of the included studies of Cochrane reviews within the top half of all the records retrieved by the Boolean MEDLINE search used by the reviewers. Methods Collections were created using the MEDLINE bibliographic records of included and excluded studies listed in the review and all records retrieved by the MEDLINE search. Records were converted to individual HTML files. Collections of records were indexed and searched through a statistical search engine, Ultraseek, using review-specific search terms. Our data sources, systematic reviews published in the Cochrane library, were included if they reported using at least one phase of the Cochrane Highly Sensitive Search Strategy (HSSS, provided citations for both included and excluded studies and conducted a meta-analysis using a binary outcome measure. Reviews were selected if they yielded between 1000–6000 records when the MEDLINE search strategy was replicated. Results Nine Cochrane reviews were included. Included studies within the Cochrane reviews were found within the first 500 retrieved studies more often than would be expected by chance. Across all reviews, recall of included studies into the top 500 was 0.70. There was no statistically significant difference in ranking when comparing included studies with just the subset of excluded studies listed as excluded in the published review. Conclusion The relevance ranking provided by the search engine was better than expected by chance and shows promise for the preliminary evaluation of large results from Boolean searches. A statistical search engine does not appear to be able to make fine discriminations concerning the relevance of

  11. Multi-objective Optimizations of a Novel Cryo-cooled DC Gun Based Ultra Fast Electron Diffraction Beamline

    CERN Document Server

    Gulliford, C; Bazarov, I

    2015-01-01

    We present the results of multi-objective genetic algorithm optimizations of a potential single shot ultra fast electron diffraction beamline utilizing a 225 kV dc gun with a novel cryocooled photocathode system and buncher cavity. Optimizations of the transverse projected emittance as a function of bunch charge are presented and discussed in terms of the scaling laws derived in the charge saturation limit. Additionally, optimization of the transverse coherence length as a function of final rms bunch length at sample location have been performed for three different sample radii: 50, 100, 200 microns, for two final bunch charges: 100k and 1000k electrons. Analysis of the solutions is discussed, as are the effects of disorder induced heating. In particular, a coherence length per rms spot size of 0.27 nm/micron was obtained for a final bunch charge of 100k electrons and final rms bunch length of approximately 100 fs. For a final charge of 1000k electrons the cryogun produces a coherence length per rms spot size...

  12. Hydrogen peroxide generated by NADPH oxidase is involved in high blue-light-induced chloroplast avoidance movements in Arabidopsis

    Science.gov (United States)

    Wen, Feng; Xing, Da; Zhang, Lingrui

    2009-08-01

    One of the most important functions of blue light is to induce chloroplast movements by reducing the damage to photosynthetic machinery under excess light. Hydrogen peroxide (H2O2), generated by various environmental stimuli, can act as a signaling molecule that regulates a number of developmental processes and environmental responses. To investigate whether H2O2 is involved in high blue light-induced chloroplast avoidance movements, we use luminescence spectrometer to observe H2O2 generation with the assistance of the fluorescence probe dichlorofluorescin diacetate (H2DCF-DA). After treatment with high blue light, a large quantity of H2O2 indicated by the fluorescence intensity of DCF is produced in a dose-dependent manner in leaf strip of Arabidopsis. Enzymatic assay shows that the activity of NADPH oxidase, which is a major site for H2O2 generation, also rapidly increases in treated strips. Exogenously applied H2O2 can promote the high blue light-induced chloroplast movements. Moreover, high blue light-induced H2O2 generation can be abolished completely by addition of exogenous catalase (CAT), and partly by diphenylene iodonium (DPI) and dichlorophenyl dimethylurea (DCMU), which are an NADPH oxidase inhibitor and a blocker of electron transport chain. And subsequent chloroplast movements can be abolished by CAT and DPI, but not by DCMU. These results presented here suggested that high blue light can induce oxidative burst, and NADPH oxidase as a major producer for H2O2 is involved in blue light-induced chloroplast avoidance movements.

  13. Untangling the contributions of image charge and laser profile for optimal photoemission of high-brightness electron beams

    Science.gov (United States)

    Portman, J.; Zhang, H.; Makino, K.; Ruan, C. Y.; Berz, M.; Duxbury, P. M.

    2014-11-01

    Using our model for the simulation of photoemission of high brightness electron beams, we investigate the virtual cathode physics and the limits to spatio-temporal and spectroscopic resolution originating from the image charge on the surface and from the profile of the exciting laser pulse. By contrasting the effect of varying surface properties (leading to expanding or pinned image charge), laser profiles (Gaussian, uniform, and elliptical), and aspect ratios (pancake- and cigar-like) under different extraction field strengths and numbers of generated electrons, we quantify the effect of these experimental parameters on macroscopic pulse properties such as emittance, brightness (4D and 6D), coherence length, and energy spread. Based on our results, we outline optimal conditions of pulse generation for ultrafast electron microscope systems that take into account constraints on the number of generated electrons and on the required time resolution.

  14. Tethering of ferredoxin:NADP+ oxidoreductase to thylakoid membranes is mediated by novel chloroplast protein TROL.

    Science.gov (United States)

    Jurić, Snjezana; Hazler-Pilepić, Kroata; Tomasić, Ana; Lepedus, Hrvoje; Jelicić, Branka; Puthiyaveetil, Sujith; Bionda, Tihana; Vojta, Lea; Allen, John F; Schleiff, Enrico; Fulgosi, Hrvoje

    2009-12-01

    Working in tandem, two photosystems in the chloroplast thylakoid membranes produce a linear electron flow from H(2)O to NADP(+). Final electron transfer from ferredoxin to NADP(+) is accomplished by a flavoenzyme ferredoxin:NADP(+) oxidoreductase (FNR). Here we describe TROL (thylakoid rhodanese-like protein), a nuclear-encoded component of thylakoid membranes that is required for tethering of FNR and sustaining efficient linear electron flow (LEF) in vascular plants. TROL consists of two distinct modules; a centrally positioned rhodanese-like domain and a C-terminal hydrophobic FNR binding region. Analysis of Arabidopsis mutant lines indicates that, in the absence of TROL, relative electron transport rates at high-light intensities are severely lowered accompanied with significant increase in non-photochemical quenching (NPQ). Thus, TROL might represent a missing thylakoid membrane docking site for a complex between FNR, ferredoxin and NADP(+). Such association might be necessary for maintaining photosynthetic redox poise and enhancement of the NPQ. PMID:19682289

  15. The stay-green phenotype of TaNAM-RNAi wheat plants is associated with maintenance of chloroplast structure and high enzymatic antioxidant activity.

    Science.gov (United States)

    Checovich, Mariana L; Galatro, Andrea; Moriconi, Jorge I; Simontacchi, Marcela; Dubcovsky, Jorge; Santa-María, Guillermo E

    2016-07-01

    TaNAM transcription factors play an important role in controlling senescence, which in turn, influences the delivery of nitrogen, iron and other elements to the grain of wheat (Triticum aestivum) plants, thus contributing to grain nutritional value. While lack or diminished expression of TaNAMs determines a stay-green phenotype, the precise effect of these factors on chloroplast structure has not been studied. In this work we focused on the events undergone by chloroplasts in two wheat lines having either control or diminished TaNAM expression due to RNA interference (RNAi). It was found that in RNAi plants maintenance of chlorophyll levels and maximal photochemical efficiency of photosystem II were associated with lack of chloroplast dismantling. Flow cytometer studies and electron microscope analysis showed that RNAi plants conserved organelle ultrastructure and complexity. It was also found that senescence in control plants was accompanied by a low leaf enzymatic antioxidant activity. Lack of chloroplast dismantling in RNAi plants was associated with maintenance of protein and iron concentration in the flag leaf, the opposite being observed in control plants. These data provide a structural basis for the observation that down regulation of TaNAMs confers a functional stay-green phenotype and indicate that the low export of iron and nitrogen from the flag leaf of these plants is concomitant, within the developmental window studied, with lack of chloroplast degradation and high enzymatic antioxidant activity. PMID:27061370

  16. Test of a numerical optimization algorithm for obtaining cross sections for multiple collision processes from electron swarm data

    International Nuclear Information System (INIS)

    A numerical optimization technique is used to obtain low-energy momentum transfer, j = 0 → 2 rotational and v = 0 → vibrational sections from measured electron swarm data for parahydrogen. The downhill simplex algorithm is used to find cross sections that represent the best numerical fit to the measured electron drift velocity and characteristic energy over a range of E/N. These results, which are in excellent agreement with published cross sections derived using traditional swarm analysis techniques, demonstrates the feasibility of using automated computational algorithms for swarm analysis involving the estimation of multiple cross sections. (Author)

  17. Preliminary design and optimization of a G-band extended interaction oscillator based on a pseudospark-sourced electron beam

    International Nuclear Information System (INIS)

    The design and simulation of a G-band extended interaction oscillator (EIO) driven by a pseudospark-sourced electron beam is presented. The characteristic of the EIO and the pseudospark-based electron beam were studied to enhance the performance of the newly proposed device. The beam-wave interaction of the EIO can be optimized by choosing a suitable pseudospark discharging voltage and by widening the operating voltage region of the EIO circuit. Simulation results show that a peak power of over 240 W can be achieved at G-band using a pseudospark discharge voltage of 41 kV

  18. The heterogeneity of structural and functional photosynthetic characteristics of mesophyll chloroplasts in various parts of mature or senescing leaf blade of two maize (Zea mays L.) genotypes

    Czech Academy of Sciences Publication Activity Database

    Kutík, J.; Holá, D.; Vičánková, A.; Šmídová, M.; Kočová, M.; Körnerová, M.; Kubínová, Lucie

    2001-01-01

    Roč. 39, č. 4 (2001), s. 497-506. ISSN 0300-3604 Grant ostatní: GA UK(CZ) 103/1998 Institutional research plan: CEZ:AV0Z5011922 Keywords : chloroplast development * electron microscopy Subject RIV: EF - Botanics Impact factor: 0.807, year: 2001

  19. Topology optimization of an electronics cover plate with respect to eigenfrequencies

    DEFF Research Database (Denmark)

    A. Kristensen, Anders Schmidt

    In the present paper it is illustrated how topology optimization with respect to eigenfrequency can be applied effectively in the product development process. The topology optimization code is implemented in ANSYS by a so called UPF. The maximization of eigenfrequency as objective is invoked into...

  20. Optimization of the electron collection efficiency of a large area MCP-PMT for the JUNO experiment

    Science.gov (United States)

    Chen, Lin; Tian, Jinshou; Liu, Chunliang; Wang, Yifang; Zhao, Tianchi; Liu, Hulin; Wei, Yonglin; Sai, Xiaofeng; Chen, Ping; Wang, Xing; Lu, Yu; Hui, Dandan; Guo, Lehui; Liu, Shulin; Qian, Sen; Xia, Jingkai; Yan, Baojun; Zhu, Na; Sun, Jianning; Si, Shuguang; Li, Dong; Wang, Xingchao; Huang, Guorui; Qi, Ming

    2016-08-01

    A novel large-area (20-inch) photomultiplier tube based on microchannel plate (MCP-PMTs) is proposed for the Jiangmen Underground Neutrino Observatory (JUNO) experiment. Its photoelectron collection efficiency Ce is limited by the MCP open area fraction (Aopen). This efficiency is studied as a function of the angular (θ), energy (E) distributions of electrons in the input charge cloud and the potential difference (U) between the PMT photocathode and the MCP input surface, considering secondary electron emission from the MCP input electrode. In CST Studio Suite, Finite Integral Technique and Monte Carlo method are combined to investigate the dependence of Ce on θ, E and U. Results predict that Ce can exceed Aopen, and are applied to optimize the structure and operational parameters of the 20-inch MCP-PMT prototype. Ce of the optimized MCP-PMT is expected to reach 81.2%. Finally, the reduction of the penetration depth of the MCP input electrode layer and the deposition of a high secondary electron yield material on the MCP are proposed to further optimize Ce.

  1. Glucose respiration in the intact chloroplast of Chlamydomonas reinhardtii

    International Nuclear Information System (INIS)

    Chloroplastic respiration was monitored by measuring 14CO2 from 14C glucose in the darkened Chlamydomonas reinhardtii F-60 chloroplast, The patterns of 14CO2 evolution from labeled glucose in the absence and presence of the inhibitors iodoacetamide, glycolate-2-phosphate, and phosphoenolypyruvate were those expected from the oxidative pentose phosphate cycle and glycolysis. The Km for glucose was 56 micromolar and for MgATP was 200 micromolar. Release of 14CO2 was inhibited by phloretin and inorganic phosphate. Comparing the inhibition of CO2 evolution generated by pH 7.5 with respect to pH 8.2 (optimum) in chloroplasts given C-1, C-2, and C-6 labeled glucose indicated that a suboptimum pH affects the recycling of the pentose phosphate intermediates to a greater extent than CO2 evolution from C-1 of glucose. Respiratory inhibition by pH 7.5 in the darkened chloroplast was alleviated by NH4Cl and KCl (stromal alkalating agents), iodoacetamide (an inhibitor of glyceraldehyde 3-phosphate dehydrogenase), or phosphoenolypyruvate (an inhibitor of phosphofructokinase). It is concluded that the site which primarily mediates respiration in the darkened Chlamydomonas chloroplast is the fructose-1,6-bisphosphatase/phosphofructokinase junction. The respiratory pathways described here can account for the total oxidation of a hexose to Co2 and for interactions between carbohydrate metabolism and the oxyhydrogen reaction in algal cells adapted to a hydrogen metabolism

  2. Arabidopsis chloroplast chaperonin 10 is a calmodulin-binding protein

    Science.gov (United States)

    Yang, T.; Poovaiah, B. W.

    2000-01-01

    Calcium regulates diverse cellular activities in plants through the action of calmodulin (CaM). By using (35)S-labeled CaM to screen an Arabidopsis seedling cDNA expression library, a cDNA designated as AtCh-CPN10 (Arabidopsis thaliana chloroplast chaperonin 10) was cloned. Chloroplast CPN10, a nuclear-encoded protein, is a functional homolog of E. coli GroES. It is believed that CPN60 and CPN10 are involved in the assembly of Rubisco, a key enzyme involved in the photosynthetic pathway. Northern analysis revealed that AtCh-CPN10 is highly expressed in green tissues. The recombinant AtCh-CPN10 binds to CaM in a calcium-dependent manner. Deletion mutants revealed that there is only one CaM-binding site in the last 31 amino acids of the AtCh-CPN10 at the C-terminal end. The CaM-binding region in AtCh-CPN10 has higher homology to other chloroplast CPN10s in comparison to GroES and mitochondrial CPN10s, suggesting that CaM may only bind to chloroplast CPN10s. Furthermore, the results also suggest that the calcium/CaM messenger system is involved in regulating Rubisco assembly in the chloroplast, thereby influencing photosynthesis. Copyright 2000 Academic Press.

  3. Comparison of intraspecific, interspecific and intergeneric chloroplast diversity in Cycads.

    Science.gov (United States)

    Jiang, Guo-Feng; Hinsinger, Damien Daniel; Strijk, Joeri Sergej

    2016-01-01

    Cycads are among the most threatened plant species. Increasing the availability of genomic information by adding whole chloroplast data is a fundamental step in supporting phylogenetic studies and conservation efforts. Here, we assemble a dataset encompassing three taxonomic levels in cycads, including ten genera, three species in the genus Cycas and two individuals of C. debaoensis. Repeated sequences, SSRs and variations of the chloroplast were analyzed at the intraspecific, interspecific and intergeneric scale, and using our sequence data, we reconstruct a phylogenomic tree for cycads. The chloroplast was 162,094 bp in length, with 133 genes annotated, including 87 protein-coding, 37 tRNA and 8 rRNA genes. We found 7 repeated sequences and 39 SSRs. Seven loci showed promising levels of variations for application in DNA-barcoding. The chloroplast phylogeny confirmed the division of Cycadales in two suborders, each of them being monophyletic, revealing a contradiction with the current family circumscription and its evolution. Finally, 10 intraspecific SNPs were found. Our results showed that despite the extremely restricted distribution range of C. debaoensis, using complete chloroplast data is useful not only in intraspecific studies, but also to improve our understanding of cycad evolution and in defining conservation strategies for this emblematic group. PMID:27558458

  4. The complete chloroplast genome of Capsicum frutescens (Solanaceae)1

    Science.gov (United States)

    Shim, Donghwan; Raveendar, Sebastin; Lee, Jung-Ro; Lee, Gi-An; Ro, Na-Young; Jeon, Young-Ah; Cho, Gyu-Taek; Lee, Ho-Sun; Ma, Kyung-Ho; Chung, Jong-Wook

    2016-01-01

    Premise of the study: We report the complete sequence of the chloroplast genome of Capsicum frutescens (Solanaceae), a species of chili pepper. Methods and Results: Using an Illumina platform, we sequenced the chloroplast genome of C. frutescens. The total length of the genome is 156,817 bp, and the overall GC content is 37.7%. A pair of 25,792-bp inverted repeats is separated by small (17,853 bp) and large (87,380 bp) single-copy regions. The C. frutescens chloroplast genome encodes 132 unique genes, including 87 protein-coding genes, 37 transfer RNA (tRNA) genes, and eight ribosomal RNA (rRNA) genes. Of these, seven genes are duplicated in the inverted repeats and 12 genes contain one or two introns. Comparative analysis with the reference chloroplast genome revealed 125 simple sequence repeat motifs and 34 variants, mostly located in the noncoding regions. Conclusions: The complete chloroplast genome sequence of C. frutescens reported here is a valuable genetic resource for Capsicum species. PMID:27213127

  5. A rapid, modular and marker-free chloroplast expression system for the green alga Chlamydomonas reinhardtii.

    Science.gov (United States)

    Bertalan, Ivo; Munder, Matthias C; Weiß, Caroline; Kopf, Judith; Fischer, Dirk; Johanningmeier, Udo

    2015-02-10

    In search of alternative expression platforms heterologous protein production in microalgae has gained increasing importance in the last years. Particularly, the chloroplast of the green alga Chlamydomonas reinhardtii has been adopted to successfully express foreign proteins like vaccines and antibodies. However, when compared with other expression systems, the development of the algal chloroplast to a powerful production platform for recombinant proteins is still in its early stages. In an effort to further improve methods for a reliable and rapid generation of transplastomic Chlamydomonas strains we constructed the key plasmid pMM2 containing the psbA gene and a multiple cloning site for foreign gene insertion. The psbA gene allows a marker-free selection procedure using as a recipient the Fud7 strain of Chlamydomonas, which grows on media containing acetate as a carbon source, but is unable to grow photoautotrophically due to the lack of an intact psbA gene. Biolistic transformation of Fud7 with vectors containing this gene restores photoautotrophic growth and thus permits selection in the light on media without carbon sources and antibiotics. The multiple cloning site with a BsaI recognition sequence allows type IIs restriction enzyme-based modular cloning which rapidly generates new gene constructs without sequences, which could influence the expression and characteristics of the foreign protein. In order to demonstrate the feasibility of this approach, a codon optimized version of the gene for the bacterial protein MPT64 has been integrated into the plastome. Several strains with different promoter/UTR combinations show a stable expression of the HA tagged MPT64 protein in Chlamydomonas chloroplasts. PMID:25554634

  6. Molecular biology and physiology of isolated chloroplasts from the algae Vaucheria

    OpenAIRE

    Didriksen, Alena

    2010-01-01

    Sea slugs of the genus Elysia (e.g. E. chlorotica) are known for their ability to incorporate chloroplasts from the yellow-green alga Vaucheria litorea. These “kleptoplasts” stay active in the digestive tract of the sea slug for several months. Chloroplasts from Vaucheria litorea are also reported to be significantly more stable after in vitro isolation than chloroplasts of other algae or of higher plants. In organello assays with isolated chloroplasts are used in studies on photosynthetical ...

  7. Chloroplast degeneration and its inhibition by kinetin in detached leaves of Cichorium intybus L.

    OpenAIRE

    F. Młodzianowski; L. Młodzanowska

    2015-01-01

    In the chicory (Cichorium intybus L. var. sativum cv. Polanowicka) leaves two types of chloroplasts are present differing by their degree of osmiophility of the thylakoid inside. This type of differentiation of chloroplasts has so far been found only in several plant species. The process of chloroplast degeneration in darkness is described. In osmiophilic chloroplasts at certain stage of degeneration minutely layered giant grana were found. Kinetin markedly inhibited the process of chloroplas...

  8. Development of chloroplast genomic resources for Cynara.

    Science.gov (United States)

    Curci, Pasquale L; De Paola, Domenico; Sonnante, Gabriella

    2016-03-01

    In this study, new chloroplast (cp) resources were developed for the genus Cynara, using whole cp genomes from 20 genotypes, by means of high-throughput sequencing technologies. Our target species included seven globe artichokes, two cultivated cardoons, eight wild artichokes, and three other wild Cynara species (C. baetica, C. cornigera and C. syriaca). One complete cp genome was isolated using short reads from a whole-genome sequencing project, while the others were obtained by means of long-range PCR, for which primer pairs are provided here. A de novo assembly strategy combined with a reference-based assembly allowed us to reconstruct each cp genome. Comparative analyses among the newly sequenced genotypes and two additional Cynara cp genomes ('Brindisino' artichoke and C. humilis) retrieved from public databases revealed 126 parsimony informative characters and 258 singletons in Cynara, for a total of 384 variable characters. Thirty-nine SSR loci and 34 other INDEL events were detected. After data analysis, 37 primer pairs for SSR amplification were designed, and these molecular markers were subsequently validated in our Cynara genotypes. Phylogenetic analysis based on all cp variable characters provided the best resolution when compared to what was observed using only parsimony informative characters, or only short 'variable' cp regions. The evaluation of the molecular resources obtained from this study led us to support the 'super-barcode' theory and consider the total cp sequence of Cynara as a reliable and valuable molecular marker for exploring species diversity and examining variation below the species level. PMID:26354522

  9. Evolutionary divergence of chloroplast FAD synthetase proteins

    Directory of Open Access Journals (Sweden)

    Arilla-Luna Sonia

    2010-10-01

    Full Text Available Abstract Background Flavin adenine dinucleotide synthetases (FADSs - a group of bifunctional enzymes that carry out the dual functions of riboflavin phosphorylation to produce flavin mononucleotide (FMN and its subsequent adenylation to generate FAD in most prokaryotes - were studied in plants in terms of sequence, structure and evolutionary history. Results Using a variety of bioinformatics methods we have found that FADS enzymes localized to the chloroplasts, which we term as plant-like FADS proteins, are distributed across a variety of green plant lineages and constitute a divergent protein family clearly of cyanobacterial origin. The C-terminal module of these enzymes does not contain the typical riboflavin kinase active site sequence, while the N-terminal module is broadly conserved. These results agree with a previous work reported by Sandoval et al. in 2008. Furthermore, our observations and preliminary experimental results indicate that the C-terminus of plant-like FADS proteins may contain a catalytic activity, but different to that of their prokaryotic counterparts. In fact, homology models predict that plant-specific conserved residues constitute a distinct active site in the C-terminus. Conclusions A structure-based sequence alignment and an in-depth evolutionary survey of FADS proteins, thought to be crucial in plant metabolism, are reported, which will be essential for the correct annotation of plant genomes and further structural and functional studies. This work is a contribution to our understanding of the evolutionary history of plant-like FADS enzymes, which constitute a new family of FADS proteins whose C-terminal module might be involved in a distinct catalytic activity.

  10. Optimized design for the scattering with angular limitation in projection electron-beam lithography based electron projection system

    International Nuclear Information System (INIS)

    We investigate the design for a scattering with angular limitation in projection electron-beam lithography (SCALPEL) based electron projection system with a demagnification of -4. By a ''field-flip'' process we can construct a doublet in which the magnetic field has a flat feature in most of the optic column but opposite sign at two sides connected by a sharp transition region. Such a theoretical model can give a near zero chromatic aberration of rotation and much smaller field curvature and astigmatism. Compared with the conventional doublet, the total image blur caused by aberrations at 1/√(2) mm off-axis distance and 1.5 mrad semiangle aperture at the mask side is about only 24 nm for a column length of 400 mm. A shorter column, less than the current 400 mm, is also favored for further reducing the total aberration. These guarantee that we can choose a much larger aperture angle (compared with present 0.5 mrad) and beam current density in such a SCALPEL projection system to achieve higher throughput while still maintaining current resolution. A practical issue for possible magnetic lens design is also discussed. (c) 2000 American Vacuum Society

  11. Expression and function analysis of the metallo-thionein-like (MT-like) gene from Festuca rubra in Chlamydomonas reinhardtii chloroplast

    Institute of Scientific and Technical Information of China (English)

    HAN SiHai; HU ZhangLi; LEI AnPing

    2008-01-01

    The cDNA of the metallothionein-like (MT-like) gene from Festuca rubra cv. Merlin was optimized with bias codon of Chlamydomonous reinhardtii chloroplast genome. The optimized MT-like gene was delivered into C. reinhardtii chloroplast and the transgenic strains expressing MT-like gene was obtained. PCR-Southern blot and RT-PCR-Southern blot analysis demonstrated that the MT-like gene was integrated into chloroplast genome of C. reinhardtii and expressed at the transcriptional level. The cadmium binding capacity of the transgenic C. reinhardtii was determined by hydride generation-atomic fluorescence spectrometry (HG-AFS) and the binding properties were analyzed. Results showed that the transgenic C. reinhardtii expressing the MT-like gene exhibited remarkably higher Cd2+ binding capacity and grew to higher densities at toxic Cd2+ concentrations (40-100 μmol/L) than the wild type strain, and that the IC50 of Cd2+ (3-d treating) to algal cell growth of transgenic strain was 55.43% higher than that of the wild type strain, indicating that the Cd2+ binding capacity and Cd2+ tolerance of C. reinhardtii was enhanced through the expression of the foreign MT-like gene in chloroplast.

  12. Expression and function analysis of the metallo-thionein-like (MT-like) gene from Festuca rubra in Chlamydomonas reinhardtii chloroplast

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The cDNA of the metallothionein-like (MT-like) gene from Festuca rubra cv. Merlin was optimized with bias codon of Chlamydomonous reinhardtii chloroplast genome. The optimized MT-like gene was de-livered into C. reinhardtii chloroplast and the transgenic strains expressing MT-like gene was obtained. PCR-Southern blot and RT-PCR-Southern blot analysis demonstrated that the MT-like gene was inte-grated into chloroplast genome of C. reinhardtii and expressed at the transcriptional level. The cad-mium binding capacity of the transgenic C. reinhardtii was determined by hydride generation-atomic fluorescence spectrometry (HG-AFS) and the binding properties were analyzed. Results showed that the transgenic C. reinhardtii expressing the MT-like gene exhibited remarkably higher Cd2+ binding capacity and grew to higher densities at toxic Cd2+ concentrations (40-100 μmol/L) than the wild type strain, and that the IC50 of Cd2+ (3-d treating ) to algal cell growth of transgenic strain was 55.43% higher than that of the wild type strain, indicating that the Cd2+ binding capacity and Cd2+ tolerance of C. reinhardtii was enhanced through the expression of the foreign MT-like gene in chloroplast.

  13. Identification of the 64 kilodalton chloroplast stromal phosphoprotein as phosphoglucomutase

    International Nuclear Information System (INIS)

    Phosphorylation of the 64 kilodalton stromal phosphoprotein by incubation of pea (Pisum sativum) chloroplast extracts with [γ-32P]ATP decreased in the presence of Glc-6-P and Glc-1,6-P2, but was stimulated by glucose. Two-dimensional gel electrophoresis following incubation of intact chloroplasts and stromal extracts with [γ-32P]ATP, or incubation of stromal extracts and partially purified phosphoglucomutase (EC 2.7.5.1) with [32P]Glc-1-P showed that the identical 64 kilodalton polypeptide was labeled. A 62 kilodalton polypeptide was phosphorylated by incubation of tobacco (Nicotiana sylvestris) stromal extracts with either [γ-32P]ATP or [32P]Glc-1-P. In contrast, an analogous polypeptide was not phosphorylated in extracts from a tobacco mutant deficient in plastid phosphoglucomutase activity. The results indicate that the 64 (or 62) kilodalton chloroplast stromal phosphoprotein is phosphoglucomutase

  14. The complete chloroplast genome sequence of Alocasia macrorrhizos.

    Science.gov (United States)

    Wang, Bin; Han, Limin

    2016-09-01

    The complete chloroplast sequence of Alocasia macrorrhizos is 154 995 bp in length, containing a pair of inverted repeats of 25 944 bp separated by a large single-copy (LSC) region and a small single-copy (SSC) region of 87 366 bp and 15 741 bp, respectively. The chloroplast genome encodes 132 predicted functional genes, including 87 protein-coding genes, four ribosomal RNA genes, and 37 transfer RNA genes, 18 of which are duplicated in the inverted repeat regions. In these genes, 16 genes contained single intron and two genes comprising double introns. A maximum-likelihood phylogenetic analysis using complete chloroplast genome revealed that A. macrorrhizos does not belong to Araceae family, which infers that the A. macrorrhizos is distant from the species in Araceae family. PMID:26258514

  15. Transcriptome analysis of ectopic chloroplast development in green curd cauliflower (Brassica oleracea L. var. botrytis)

    Science.gov (United States)

    Chloroplasts are the green plastids where photosynthesis takes place. The biogenesis of chloroplasts requires the coordinate expression of both nuclear and chloroplast genes and is regulated by developmental and environmental signals. Despite extensive studies of this process, the genetic basis and ...

  16. Manipulating the chloroplast genome of Chlamydomonas: Present realities and future prospects

    Energy Technology Data Exchange (ETDEWEB)

    Boynton, J.; Gillham, N.; Hauser, C.; Heifetz, P.; Lers, A.; Newman, S.; Osmond, B.

    1992-12-31

    Biotechnology is being applied in vitro modification and stable reintroduction of chloroplast genes in Chlamydomonas reinhardtii and Nicotiana tabacum by homologous recombination. We are attempting the function analyses of plastid encoded proteins involved in photosynthesis, characterization of sequences which regulate expression of plastid genes at the transcriptional and translational levels, targeted disruption of chloroplast genes and molecular analysis of processes involved in chloroplast recombination.

  17. Salinity induces membrane structure and lipid changes in maize mesophyll and bundle sheath chloroplasts.

    Science.gov (United States)

    Omoto, Eiji; Iwasaki, Yugo; Miyake, Hiroshi; Taniguchi, Mitsutaka

    2016-05-01

    The membranes of Zea mays (maize) mesophyll cell (MC) chloroplasts are more vulnerable to salinity stress than are those of bundle sheath cell (BSC) chloroplasts. To clarify the mechanism underlying this difference in salt sensitivity, we monitored changes in the glycerolipid and fatty acid compositions of both types of chloroplast upon exposure to salinity stress. The monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) contents were higher in MC chloroplasts than in BSC chloroplasts, in both the presence and absence of salt treatment. Under salt conditions, the MGDG level in MC chloroplasts was significantly lower than under normal conditions, while it was unchanged in BSC chloroplasts. In both types of chloroplast, the contents of DGDG, phosphatidylglycerol and phosphatidylinositol remained at the same levels in control and salt-treated plants, whereas sulfoquinovosyldiacylglycerol and phosphatidylcholine were significantly lower and higher, respectively, upon salt treatment. In addition, the fatty acid composition and double bond index of individual lipid classes were changed by salt treatment in both BSC and MC chloroplasts, although these factors had no effect on glycerolipid content. These findings suggest that the difference in salt sensitivity of MC and BSC chloroplast membranes is related to differences in MGDG responses to salinity. Thus, we propose that the low MGDG content and the low sensitivity of MGDG to salinity in BSC chloroplasts render them more tolerant than MC chloroplasts to salinity stress. PMID:26555406

  18. The optimization of production and control of hot-electron plasmas

    International Nuclear Information System (INIS)

    The research discussed in this paper consist of the following: Hot-Electron Plasma Formation in AMPHED; Kinectic Models of Hot-Electron Plasma Formation; Resonator Design and Tests; Results of 1-D Fokker-Planck ECH Study of TEXT; and AMPC/TEXT Collaboration

  19. The action spectrum in chloroplast translocation in multilayer leaf cells

    Directory of Open Access Journals (Sweden)

    Zbigniew Lechowski

    2015-05-01

    Full Text Available By measurement of light transmittance through a leaf as criterion of chloroplast translocation, the action spectrum of Ajuga reptans was established. In the spectrum obtained, a correction was introduced for leaf autoabsorption calculated on the basis of the Beer-Lambert law. The action spectrum has two maxima: at λ= 375 nm and λ= 481 nm. The range above 502 nm has no significant effect on chloroplast translocation. Comparison with other objects examined demonstrated that in multilayer leaf cells riboflavin seems also to be a photoreceptor active in this process.

  20. Robust expression of a bioactive mammalian protein in chlamydomonas chloroplast

    Science.gov (United States)

    Mayfield, Stephen P.

    2010-03-16

    Methods and compositions are disclosed to engineer chloroplast comprising heterologous mammalian genes via a direct replacement of chloroplast Photosystem II (PSII) reaction center protein coding regions to achieve expression of recombinant protein above 5% of total protein. When algae is used, algal expressed protein is produced predominantly as a soluble protein where the functional activity of the peptide is intact. As the host algae is edible, production of biologics in this organism for oral delivery or proteins/peptides, especially gut active proteins, without purification is disclosed.

  1. Robust expression of a bioactive mammalian protein in Chlamydomonas chloroplast

    Energy Technology Data Exchange (ETDEWEB)

    Mayfield, Stephen P

    2015-01-13

    Methods and compositions are disclosed to engineer chloroplast comprising heterologous mammalian genes via a direct replacement of chloroplast Photosystem II (PSII) reaction center protein coding regions to achieve expression of recombinant protein above 5% of total protein. When algae is used, algal expressed protein is produced predominantly as a soluble protein where the functional activity of the peptide is intact. As the host algae is edible, production of biologics in this organism for oral delivery of proteins/peptides, especially gut active proteins, without purification is disclosed.

  2. The complete chloroplast genome of Schrenkiella parvula (Brassicaceae).

    Science.gov (United States)

    He, Qi; Hao, Guoqian; Wang, Xiaojuan; Bi, Hao; Li, Yuanshuo; Guo, Xinyi; Ma, Tao

    2016-09-01

    Schrenkiella parvula is an Arabidopsis-related model species used here for studying plant stress tolerance. In this study, the complete chloroplast genome sequence of S. parvula has been reported for the first time. The total length of the chloroplast genome was 153 979 bp, which had a typical quadripartite structure. The annotated plastid genome includes 87 protein-coding genes, 39 tRNA genes and 8 ribosomal RNA genes. The evolutionary relationships revealed by our phylogenetic analysis indicated that S. parvula is closer to the Brassiceae species when compared with Eutrema salsugineum. PMID:26260181

  3. Nucleotide sequence of a spinach chloroplast valine tRNA.

    OpenAIRE

    Sprouse, H M; Kashdan, M; Otis, L; Dudock, B

    1981-01-01

    The nucleotide sequence of a spinach chloroplast valine tRNA (sp. chl. tRNA Val) has been determined. This tRNA shows essentially equal homology to prokaryotic valine tRNAs (58-65% homology) and to the mitochondrial valine tRNAs of lower eukaryotes (yeast and N. crassa, 61-62% homology). Sp. chl. tRNA Val shows distinctly lower homology to mouse mitochondrial valine tRNA (53% homology) and to eukaryotic cytoplasmic valine tRNAs (47-53% homology). Sp. chl. tRNA Val, like all other chloroplast ...

  4. Characterization of elemental sulfur in isolated intact spinach chloroplasts

    International Nuclear Information System (INIS)

    Incubation of intact spinach (Spinacia oleracea L.) chloroplasts in the presence of 35SO42- resulted in the light-dependent formation of a chloroform-soluble sulfur-containing compound distinct from sulfolipid. The authors have identified this compound as the most stable form (S8) of elemental sulfur (S0, valence state for S = O) by mass spectrometry. It is possible that elemental sulfur (S0) was formed by oxidation of bound sulfide, i.e. after the photoreduction of sulfate to sulfide by intact chloroplasts, and released as S8 under the experimental conditions used for analysis

  5. A Novel Optimization Technique to Improve Gas Recognition by Electronic Noses Based on the Enhanced Krill Herd Algorithm.

    Science.gov (United States)

    Wang, Li; Jia, Pengfei; Huang, Tailai; Duan, Shukai; Yan, Jia; Wang, Lidan

    2016-01-01

    An electronic nose (E-nose) is an intelligent system that we will use in this paper to distinguish three indoor pollutant gases (benzene (C₆H₆), toluene (C₇H₈), formaldehyde (CH₂O)) and carbon monoxide (CO). The algorithm is a key part of an E-nose system mainly composed of data processing and pattern recognition. In this paper, we employ support vector machine (SVM) to distinguish indoor pollutant gases and two of its parameters need to be optimized, so in order to improve the performance of SVM, in other words, to get a higher gas recognition rate, an effective enhanced krill herd algorithm (EKH) based on a novel decision weighting factor computing method is proposed to optimize the two SVM parameters. Krill herd (KH) is an effective method in practice, however, on occasion, it cannot avoid the influence of some local best solutions so it cannot always find the global optimization value. In addition its search ability relies fully on randomness, so it cannot always converge rapidly. To address these issues we propose an enhanced KH (EKH) to improve the global searching and convergence speed performance of KH. To obtain a more accurate model of the krill behavior, an updated crossover operator is added to the approach. We can guarantee the krill group are diversiform at the early stage of iterations, and have a good performance in local searching ability at the later stage of iterations. The recognition results of EKH are compared with those of other optimization algorithms (including KH, chaotic KH (CKH), quantum-behaved particle swarm optimization (QPSO), particle swarm optimization (PSO) and genetic algorithm (GA)), and we can find that EKH is better than the other considered methods. The research results verify that EKH not only significantly improves the performance of our E-nose system, but also provides a good beginning and theoretical basis for further study about other improved krill algorithms' applications in all E-nose application areas. PMID

  6. Importance of the tuning of band position in optimizing the electronic coupling and photocatalytic activity of nanocomposite

    International Nuclear Information System (INIS)

    The electronic coupling and photocatalytic activity of Ag2CO3–TiO2 nanocomposite can be optimized by the fine-tuning of the band position of titanium oxide with nitrogen doping. The increase of the valence band energy of TiO2 by N-doping leads not only to the enhanced absorption of visible light but also to the promoted hole transfer from Ag2CO3 to TiO2, resulting in the efficient spatial separation of photogenerated electrons and holes. While the undoped Ag2CO3–TiO2 nanocomposite shows an inferior photocatalytic activity to the pure Ag2CO3, the photocatalyst performance of N-doped nanocomposite is better than those of Ag2CO3 and undoped Ag2CO3–TiO2 nanocomposite. This observation underscores a significant enhancement of the photocatalytic activity of nanocomposite upon N-doping, a result of enhanced electronic coupling between the hybridized species. The present results clearly demonstrate the importance of the fine-tuning of band position in optimizing the photocatalytic activity of hybrid-type photocatalysts. - Highlights: • The band position of Ag2CO3–TiO2 can be effectively tailored by nitrogen doping. • The N-doping leads to the improvement of charge separation. • The N-doped Ag2CO3–TiO2 shows high photocatalytic activity

  7. A set of 100 chloroplast DNA primer pairs to study population genetics and phylogeny in monocotyledons.

    Science.gov (United States)

    Scarcelli, Nora; Barnaud, Adeline; Eiserhardt, Wolf; Treier, Urs A; Seveno, Marie; d'Anfray, Amélie; Vigouroux, Yves; Pintaud, Jean-Christophe

    2011-01-01

    Chloroplast DNA sequences are of great interest for population genetics and phylogenetic studies. However, only a small set of markers are commonly used. Most of them have been designed for amplification in a large range of Angiosperms and are located in the Large Single Copy (LSC). Here we developed a new set of 100 primer pairs optimized for amplification in Monocotyledons. Primer pairs amplify coding (exon) and non-coding regions (intron and intergenic spacer). They span the different chloroplast regions: 72 are located in the LSC, 13 in the Small Single Copy (SSC) and 15 in the Inverted Repeat region (IR). Amplification and sequencing were tested in 13 species of Monocotyledons: Dioscorea abyssinica, D. praehensilis, D. rotundata, D. dumetorum, D. bulbifera, Trichopus sempervirens (Dioscoreaceae), Phoenix canariensis, P. dactylifera, Astrocaryum scopatum, A. murumuru, Ceroxylon echinulatum (Arecaceae), Digitaria excilis and Pennisetum glaucum (Poaceae). The diversity found in Dioscorea, Digitaria and Pennisetum mainly corresponded to Single Nucleotide Polymorphism (SNP) while the diversity found in Arecaceae also comprises Variable Number Tandem Repeat (VNTR). We observed that the most variable loci (rps15-ycf1, rpl32-ccsA, ndhF-rpl32, ndhG-ndhI and ccsA) are located in the SSC. Through the analysis of the genetic structure of a wild-cultivated species complex in Dioscorea, we demonstrated that this new set of primers is of great interest for population genetics and we anticipate that it will also be useful for phylogeny and bar-coding studies. PMID:21637837

  8. Integration of complete chloroplast genome sequences with small amplicon datasets improves phylogenetic resolution in Acacia.

    Science.gov (United States)

    Williams, Anna V; Miller, Joseph T; Small, Ian; Nevill, Paul G; Boykin, Laura M

    2016-03-01

    Combining whole genome data with previously obtained amplicon sequences has the potential to increase the resolution of phylogenetic analyses, particularly at low taxonomic levels or where recent divergence, rapid speciation or slow genome evolution has resulted in limited sequence variation. However, the integration of these types of data for large scale phylogenetic studies has rarely been investigated. Here we conduct a phylogenetic analysis of the whole chloroplast genome and two nuclear ribosomal loci for 65 Acacia species from across the most recent Acacia phylogeny. We then combine this data with previously generated amplicon sequences (four chloroplast loci and two nuclear ribosomal loci) for 508 Acacia species. We use several phylogenetic methods, including maximum likelihood bootstrapping (with and without constraint) and ExaBayes, in order to determine the success of combining a dataset of 4000bp with one of 189,000bp. The results of our study indicate that the inclusion of whole genome data gave a far better resolved and well supported representation of the phylogenetic relationships within Acacia than using only amplicon sequences, with the greatest support observed when using a whole genome phylogeny as a constraint on the amplicon sequences. Our study therefore provides methods for optimal integration of genomic and amplicon sequences. PMID:26702955

  9. Decay Time Optimization of YAG:Ce Scintillator for S(T)EM Electron Detector

    Czech Academy of Sciences Publication Activity Database

    Schauer, Petr

    Sapporo : Japanese Society of Microscopy , 2006, s. 655. [IMC16 - International Microscopy Congress /16./. Sapporo (JP), 03.09.2006-08.09.2006] R&D Projects: GA ČR GA102/04/2144 Institutional research plan: CEZ:AV0Z20650511 Keywords : scintillation detector * electron microscope * cathodoluminescence * YAG:Ce * single crystal scintillator * decay time * afterglow * kinetic model * SEM * STEM Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  10. Optimization of Electron Beam Melting for Production of Small Components in Biocompatible Titanium Grades

    OpenAIRE

    Karlsson, Joakim

    2015-01-01

    Additive manufacturing (AM), also called 3D-printing, are technologies where parts are formed from the bottom up by adding material layer-by-layer on top of each other. Electron Beam Melting (EBM) is an AM technique capable of manufacturing fully solid metallic parts, using a high-intensity electron beam to melt powder particles in layers to form finished components. Compared to conventional machining, EBM offers enhanced efficiency for production of customized and patient specific parts such...

  11. Optimization of Secondary Electron Detection by Segmental lonization Detector in Environmental SEM

    Czech Academy of Sciences Publication Activity Database

    Černoch, P.; Jirák, Josef

    Prague : Czechoslovak Microscopy Society, 2007 - (Nebesářová, J.; Hozák, P.), s. 79-80 ISBN 978-80-239-9397-4. [Multinational Congress on Microscopy /8./. Prague (CZ), 17.06.2007-21.06.2007] R&D Projects: GA ČR(CZ) GA102/05/0886 Institutional research plan: CEZ:AV0Z20650511 Keywords : secondary electron detection * segmental ionization detector * environmental SEM Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  12. Optimal Operation of Distribution Electronic Power Transformer Using Linear Quadratic Regulator Method

    OpenAIRE

    Mohammad Hosein Rezaei; Rahmatolah Hooshmand; Mohammad Ataei

    2011-01-01

    Transformers perform many functions such as voltage transformation, isolation and noise decoupling. They are indispensable components in electric power distribution system. However, at low frequencies (50 Hz), they are one of the heaviest and the most expensive equipment in an electrical distribution system. Nowadays, electronic power transformers are used instead of conventional power transformers that do voltage transformation and power delivery in power system by power electronic converter...

  13. Optimal Operation of a Distributed System with High Share of Power Electronic Loads

    OpenAIRE

    Jelani, Nadeem

    2010-01-01

    The tendency of connecting the loads to the three phase AC system through power electronic interfaces is increasing with time. These interfaces greatly affect the performance of the power system when properly operated. The injection of reactive power by these interfaces provides the possibility to support the voltage, increase the stability margins and decrease the power losses in the power system. The power electronic loads when tightly regulated consume constant power from the grid and the...

  14. Optimal control of ultrafast laser driven many-electron dynamics in a polyatomic molecule: N-methyl-6-quinolone

    Science.gov (United States)

    Klamroth, Tillmann

    2006-04-01

    We report time-dependent configuration interaction singles calculations for the ultrafast laser driven many-electron dynamics in a polyatomic molecule, N-methyl-6-quinolone. We employ optimal control theory to achieve a nearly state-selective excitation from the S0 to the S1 state, on a time scale of a few (≈6) femtoseconds. The optimal control scheme is shown to correct for effects opposing a state-selective transition, such as multiphoton transitions and other, nonlinear phenomena, which are induced by the ultrashort and intense laser fields. In contrast, simple two-level π pulses are not effective in state-selective excitations when very short pulses are used. Also, the dependence of multiphoton and nonlinear effects on the number of states included in the dynamical simulations is investigated.

  15. Optimized random phase approximation for the structure of liquid alkali metals as electron-ion plasmas

    International Nuclear Information System (INIS)

    The purpose of this letter is to stress that the way towards an unconventional optimized-random-phase-approximation (ORPA) approach to the structure of liquid metals is indicated, and in fact already a good first-order solution for such an approach is provided

  16. Chloroplast degeneration and its inhibition by kinetin in detached leaves of Cichorium intybus L.

    Directory of Open Access Journals (Sweden)

    F. Młodzianowski

    2015-05-01

    Full Text Available In the chicory (Cichorium intybus L. var. sativum cv. Polanowicka leaves two types of chloroplasts are present differing by their degree of osmiophility of the thylakoid inside. This type of differentiation of chloroplasts has so far been found only in several plant species. The process of chloroplast degeneration in darkness is described. In osmiophilic chloroplasts at certain stage of degeneration minutely layered giant grana were found. Kinetin markedly inhibited the process of chloroplast degeneration, and after prolonged treatment even stimulated the stacking. process of grana thylakoids.

  17. Isolation of dimorphic chloroplasts from the single-cell C4 species Bienertia sinuspersici

    Directory of Open Access Journals (Sweden)

    Lung Shiu-Cheung

    2012-03-01

    Full Text Available Abstract Three terrestrial plants are known to perform C4 photosynthesis without the dual-cell system by partitioning two distinct types of chloroplasts in separate cytoplasmic compartments. We report herein a protocol for isolating the dimorphic chloroplasts from Bienertia sinuspersici. Hypo-osmotically lysed protoplasts under our defined conditions released intact compartments containing the central chloroplasts and intact vacuoles with adhering peripheral chloroplasts. Following Percoll step gradient purification both chloroplast preparations demonstrated high homogeneities as evaluated from the relative abundance of respective protein markers. This protocol will open novel research directions toward understanding the mechanism of single-cell C4 photosynthesis.

  18. High-quality imaging in environmental scanning electron microscopy - optimizing the pressure limiting system and the secondary electron detection of a commercially available ESEM.

    Science.gov (United States)

    Fitzek, H; Schroettner, H; Wagner, J; Hofer, F; Rattenberger, J

    2016-04-01

    In environmental scanning electron microscopy applications in the kPa regime are of increasing interest for the investigation of wet and biological samples, because neither sample preparation nor extensive cooling are necessary. Unfortunately, the applications are limited by poor image quality. In this work the image quality at high pressures of a FEI Quanta 600 (field emission gun) and a FEI Quanta 200 (thermionic gun) is greatly improved by optimizing the pressure limiting system and the secondary electron (SE) detection system. The scattering of the primary electron beam strongly increases with pressure and thus the image quality vanishes. The key to high-image quality at high pressures is to reduce scattering as far as possible while maintaining ideal operation conditions for the SE-detector. The amount of scattering is reduced by reducing both the additional stagnation gas thickness (aSGT) and the environmental distance (ED). A new aperture holder is presented that significantly reduces the aSGT while maintaining the same field-of-view (FOV) as the original design. With this aperture holder it is also possible to make the aSGT even smaller at the expense of a smaller FOV. A new blade-shaped SE-detector is presented yielding better image quality than usual flat SE-detectors. The electrode of the new SE detector is positioned on the sample table, which allows the SE-detector to operate at ideal conditions regardless of pressure and ED. PMID:26540292

  19. Shaped electric fields for fast optimal manipulation of electron spin and position in a double quantum dot

    Science.gov (United States)

    Budagosky, J. A.; Khomitsky, D. V.; Sherman, E. Ya.; Castro, Alberto

    2016-01-01

    We use quantum optimal control theory algorithms to design external electric fields that drive the coupled spin and orbital dynamics of an electron in a double quantum dot, subject to the spin-orbit coupling and Zeeman magnetic fields. We obtain time profiles of multifrequency electric field pulses which increase the rate of spin-flip transitions by several orders of magnitude in comparison with monochromatic fields, where the spin Rabi oscillations were predicted to be very slow. This precise (with fidelity higher than 1 ×10-4 ) and fast (at the time scale of the order of 0.1 ns, comparable with the Zeeman spin rotation and the interdot tunneling time) simultaneous control of the spin and position is achieved while keeping the electron in the four lowest tunneling- and Zeeman-split levels through the duration of the pulse. The proposed algorithms suggest effective applications in spintronics and quantum information devices.

  20. Structure-function correlation during the etioplast-chloroplast transition in cucumber cotyledonary leaves

    International Nuclear Information System (INIS)

    We studied the development of chloroplasts from etioplasts in the cotyledonary leaves of 4-d-old dark-grown cucumber (Cucumis sativus) seedlings after irradiation (20 micromol mE(-2) sE(-1). Upon irradiation, the triggering of chlorophyll (Chl) synthesis and accumulation showed a relatively short lag phase. The irradiation of etiolated seed-lings initiated the synthesis of apoproteins of pigment-protein complexes. While Chl-protein 2 (CP2) was detected at 6 h after irradiation, CP 1 only after 29 h. Further, the thylakoid membrane function during this time period in terms of PS1- and PS2-mediated electron transfer activity and intersystem electron pool size were analyzed

  1. Chloroplast genetics of chlamydomonas. I. Allelic segregation ratios

    International Nuclear Information System (INIS)

    This paper presents allelic segregation data from a series of 16 crosses segregated for nuclear and chloroplast genes. By means of pedigree analysis, segregants of chloroplast genes. By means of pedigree analysis, segregants of chloroplast markers occurring in the zygote have been distinguished from those occurring in zoospore clones. The genes ac1, ac2, and tm1 showed little if any deviation from 1:1 either in zygotic segregation or in zoospore clones. The genes sm2, ery, and spc showed a significant excess of the allele from the mt+ parent in zygotes. However, in zoospores, mt+ excess was seen only when the allele was the mutant (resistant) form but not when it was wild type (sensitive). These results show that the extent of preferential segregation differs in zygotes and in zoospores, and that preferential segregation is influenced by map location and by allele specificity. A comparison of progeny from zygotes mated after 0, 15'', 30'', and 50'' uv irradiation of the mt+ gametes demonstrated the lack of an effect of uv upon allelic segregation ratios. In total, these results exclude the multi-copy model of chloroplast genome segregation suggested by Gillham. Boynton and Lee (1974) and support the diploid model we have previously proposed

  2. Chloroplast genetics of chlamydomonas. I. Allelic segregation ratios. [UV radiation

    Energy Technology Data Exchange (ETDEWEB)

    Sager, R.; Ramanis, Z.

    1976-06-01

    This paper presents allelic segregation data from a series of 16 crosses segregated for nuclear and chloroplast genes. By means of pedigree analysis, segregants of chloroplast genes. By means of pedigree analysis, segregants of chloroplast markers occurring in the zygote have been distinguished from those occurring in zoospore clones. The genes ac1, ac2, and tm1 showed little if any deviation from 1:1 either in zygotic segregation or in zoospore clones. The genes sm2, ery, and spc showed a significant excess of the allele from the mt+ parent in zygotes. However, in zoospores, mt+ excess was seen only when the allele was the mutant (resistant) form but not when it was wild type (sensitive). These results show that the extent of preferential segregation differs in zygotes and in zoospores, and that preferential segregation is influenced by map location and by allele specificity. A comparison of progeny from zygotes mated after 0, 15'', 30'', and 50'' uv irradiation of the mt+ gametes demonstrated the lack of an effect of uv upon allelic segregation ratios. In total, these results exclude the multi-copy model of chloroplast genome segregation suggested by Gillham. Boynton and Lee (1974) and support the diploid model we have previously proposed.

  3. Chloroplast heterogeneity and historical admixture within the genus Malus

    Science.gov (United States)

    Premise of the study: We examined chloroplast DNA sequence variation in 412 samples representing 30 Malus species (including Malus x domestica Borkh.). Malus wild species are of particular interest for providing novel alleles and traits in apple breeding programs, yet the taxonomic status of these s...

  4. Complete Chloroplast Genome Sequence of Phagomixotrophic Green Alga Cymbomonas tetramitiformis

    Science.gov (United States)

    Paasch, Amber E.; Graham, Linda E.; Kim, Eunsoo

    2016-01-01

    We report here the complete chloroplast genome sequence of Cymbomonas tetramitiformis strain PLY262, which is a prasinophycean green alga that retains a phagomixotrophic mode of nutrition. The genome is 84,524 bp in length, with a G+C content of 37%, and contains 3 rRNAs, 26 tRNAs, and 76 protein-coding genes. PMID:27313295

  5. Selenocystamine improves protein accumulation in chloroplasts of eukaryotic green algae

    OpenAIRE

    Ferreira-Camargo, Livia S; Tran, Miller; Beld, Joris; Burkart, Michael D.; Mayfield, Stephen P

    2015-01-01

    Eukaryotic green algae have become an increasingly popular platform for recombinant proteins production. In particular, Chlamydomonas reinhardtii, has garnered increased attention for having the necessary biochemical machinery to produce vaccines, human antibodies and next generation cancer targeting immunotoxins. While it has been shown that chloroplasts contain chaperones, peptidyl prolylisomerases and protein disulfide isomerases that facilitate these complex proteins folding and assembly,...

  6. Global Chloroplast Phylogeny and Biogeography of Bracken (Pteridium: Dennstaedtiaceae)

    OpenAIRE

    J.P.;; Thomson, J. A.; Stratford, J. K.; Paul G Wolf

    2009-01-01

    Bracken ferns (genus Pteridium) represent an ancient species complex with a natural worldwide distribution. Pteridium has historically been treated as comprising a single species, but recent treatments have recognized several related species. Phenotypic plasticity, geographically structured morphological variation, and geographically biased sampling have all contributed to taxonomic confusion in the genus. We sampled bracken specimens worldwide and used variable regions of the chloroplast gen...

  7. Structure of "Arabidopsis" chloroplastic monothiol glutaredoxin AtGRXcp

    Science.gov (United States)

    Monothiol glutaredoxins (Grxs) play important roles in maintaining redox homeostasis in living cells and are conserved across species. "Arabidopsis thaliana" monothiol glutaredoxin AtGRXcp, is critical for protection from oxidative stress in chloroplasts. The crystal structure of AtGRXcp has been de...

  8. Senescence-Associated Vacuoles, a Specific Lytic Compartment for Degradation of Chloroplast Proteins?

    Directory of Open Access Journals (Sweden)

    Cristian A. Carrión

    2014-11-01

    Full Text Available Degradation of chloroplasts and chloroplast components is a distinctive feature of leaf senescence. In spite of its importance in the nutrient economy of plants, knowledge about the mechanism(s involved in the breakdown of chloroplast proteins is incomplete. A novel class of vacuoles, “senescence-associated vacuoles” (SAVs, characterized by intense proteolytic activity appear during senescence in chloroplast-containing cells of leaves. Since SAVs contain some chloroplast proteins, they are candidate organelles to participate in chloroplast breakdown. In this review we discuss the characteristics of SAVs, and their possible involvement in the degradation of Rubisco, the most abundant chloroplast protein. Finally, SAVs are compared with other extra-plastidial protein degradation pathways operating in senescing leaves.

  9. Optimal electron, phonon, and magnetic characteristics for low energy thermally induced magnetization switching

    Energy Technology Data Exchange (ETDEWEB)

    Atxitia, U., E-mail: Unai.Atxitia@uni-konstanz.de [Fachbereich Physik, Universität Konstanz, D-78457 Konstanz (Germany); Zukunftskolleg, Universität Konstanz, D-78457 Konstanz (Germany); Ostler, T. A., E-mail: t.ostler@exeter.ac.uk [Department of Physics, University of York, York YO105DD (United Kingdom); College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, Devon EX4 4SB (United Kingdom); Chantrell, R. W. [Department of Physics, University of York, York YO105DD (United Kingdom); Chubykalo-Fesenko, O. [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid (Spain)

    2015-11-09

    Using large-scale computer simulations, we thoroughly study the minimum energy required to thermally induced magnetization switching (TIMS) after the application of a femtosecond heat pulse in transition metal-rare earth ferrimagnetic alloys. We find that for an energy efficient TIMS, a low ferrimagnetic net magnetization with a strong temperature dependence is the relevant factor for the magnetic system. For the lattice and electron systems, the key physics for efficient TIMS is a large electron-phonon relaxation time. Importantly, we show that as the cooling time of the heated electrons is increased, the minimum power required to produce TIMS can be reduced by an order of magnitude. Our results show the way to low power TIMS by appropriate engineering of magnetic heterostructures.

  10. A Thesis on Design Optimization of Heat Sink in Power Electronics

    OpenAIRE

    P.Chennakesavarao; P.Srihari

    2014-01-01

    The heat sinks are used in electronic systems to remove heat from the chip and effectively transfer it to the ambient. The heat sink geometry is designed by the mechanical engineers with the primary aim of reducing the thermal resistance of the heat sink for better cooling in the electronic systems. Due to the proximity of the heat sink with the ICs, the RF fields created by RF currents in the ICs/PCBs gets coupled to heat sinks. Hence, the coupled RF current can cause radiate...

  11. Observation of lens aberrations for high resolution electron microscopy II: Simple expressions for optimal estimates

    International Nuclear Information System (INIS)

    This paper lists simple closed-form expressions estimating aberration coefficients (defocus, astigmatism, three-fold astigmatism, coma / misalignment, spherical aberration) on the basis of image shift or diffractogram shape measurements as a function of injected beam tilt. Simple estimators are given for a large number of injected tilt configurations, optimal in the sense of least-squares fitting of all the measurements, and so better than most reported previously. Standard errors are given for most, allowing different approaches to be compared. Special attention is given to the measurement of the spherical aberration, for which several simple procedures are given, and the effect of foreknowledge of this on other aberration estimates is noted. Details and optimal expressions are also given for a new and simple method of analysis, requiring measurements of the diffractogram mirror axis direction only, which are simpler to make than the focus and astigmatism measurements otherwise required. - Highlights: • Optimal estimators for CTEM lens aberrations are more accurate and/or use fewer observations. • Estimators have been found for defocus, astigmatism, three-fold astigmatism, coma and spherical aberration. • Estimators have been found relying on diffractogram shape, image shift and diffractogram orientation only, for a variety of beam tilts. • The standard error for each estimator has been found

  12. Observation of lens aberrations for high resolution electron microscopy II: Simple expressions for optimal estimates

    Energy Technology Data Exchange (ETDEWEB)

    Saxton, W. Owen, E-mail: wos1@cam.ac.uk

    2015-04-15

    This paper lists simple closed-form expressions estimating aberration coefficients (defocus, astigmatism, three-fold astigmatism, coma / misalignment, spherical aberration) on the basis of image shift or diffractogram shape measurements as a function of injected beam tilt. Simple estimators are given for a large number of injected tilt configurations, optimal in the sense of least-squares fitting of all the measurements, and so better than most reported previously. Standard errors are given for most, allowing different approaches to be compared. Special attention is given to the measurement of the spherical aberration, for which several simple procedures are given, and the effect of foreknowledge of this on other aberration estimates is noted. Details and optimal expressions are also given for a new and simple method of analysis, requiring measurements of the diffractogram mirror axis direction only, which are simpler to make than the focus and astigmatism measurements otherwise required. - Highlights: • Optimal estimators for CTEM lens aberrations are more accurate and/or use fewer observations. • Estimators have been found for defocus, astigmatism, three-fold astigmatism, coma and spherical aberration. • Estimators have been found relying on diffractogram shape, image shift and diffractogram orientation only, for a variety of beam tilts. • The standard error for each estimator has been found.

  13. Phytotoxic Mechanism of Nanoparticles: Destruction of Chloroplasts and Vascular Bundles and Alteration of Nutrient Absorption.

    Science.gov (United States)

    Nhan, Le Van; Ma, Chuanxin; Rui, Yukui; Liu, Shutong; Li, Xuguang; Xing, Baoshan; Liu, Liming

    2015-01-01

    This study focused on determining the phytotoxic mechanism of CeO2 nanoparticles (NPs): destroying chloroplasts and vascular bundles and altering absorption of nutrients on conventional and Bt-transgenic cottons. Experiments were designed with three concentrations of CeO2 NPs including: 0, 100 and 500 mg·L(-1), and each treatment was three replications. Results indicate that absorbed CeO2 nanoparticles significantly reduced the Zn, Mg, Fe, and P levels in xylem sap compared with the control group and decreased indole-3-acetic acid (IAA) and abscisic acid (ABA) concentrations in the roots of conventional cotton. Transmission electron microscopy (TEM) images revealed that CeO2 NPs were absorbed into the roots and subsequently transported to the stems and leaves of both conventional and Bt-transgenic cotton plants via xylem sap. In addition, the majority of aggregated CeO2 NPs were attached to the external surface of chloroplasts, which were swollen and ruptured, especially in Bt-transgenic cotton. The vascular bundles were destroyed by CeO2 nanoparticles, and more damage was observed in transgenic cotton than conventional cotton. PMID:26108166

  14. A study of an optimal technological solution for the electronics of particle position sensitive gas detectors (multiwire proportional chambers)

    International Nuclear Information System (INIS)

    This work aims at optimizing the electronics for position sensitive gas detectors. The first part is a review of proportional chamber operation principles and presents the different possibilities for the architecture of the electronics. The second part involves electronic signal processing for best signal-to-noise ratio. We present a time-variant filter based on a second order base line restorer.It allows a simple pole-zero and tail cancellation at high counting rates. Also, various interpolating algorithms for cathode strip chambers have been studied. The last part reports the development of a complete electronic system, from the preamplifiers up to the readout and control interface, for the cathode strip chambers in the focal plane of the BBS Spectrometer at KVI, Holland. The system is based on application specific D-size VXI modules. In all modules, the 16-bit ADCs and FIFO memory are followed by a Digital Signal Processor, which performs data filtering and cathode induced charge interpolation. Very good analog noise performance is obtained in a multi-processor environment. (author)

  15. Effects of high proline accumulation on chloroplast and mitochondrial ultrastructure and on osmotic adjustment in tobacco plants

    Directory of Open Access Journals (Sweden)

    Lucélia Borgo

    2015-05-01

    Full Text Available Proline accumulates in many organisms in response to abiotic stresses, such as drought and salinity. Reports have discussed the role of proline in relation to osmotic adjustment, even though no clear-cut evidence has yet been provided demonstrating this association as a defense mechanism against drought stress in plants. However, it has been indicated that the application of exogenous proline can damage the ultrastructure of chloroplasts and mitochondria. In this study, using transgenic tobacco plants carrying a mutant p5cs gene from Vigna aconitifolia under control of the CaMV 35S promoter, we show that the high levels of endogenous proline accumulated in leaves does not contribute to the osmotic adjustment in plants under water deficit conditions. Additionally, electron microscopic observations of mitochondria and chloroplasts show that the ultrastructure of these organelles was not damaged even in the transgenic plants, with the leaves presenting the highest endogenous proline content in (100 µmol g-1 dry mass. This investigation demonstrates that in tobacco, high levels of endogenous free proline are not associated with osmotic adjustment and that elevated proline content in leaves, even at levels 10 times higher than normal, do not disturb the chloroplast and mitochondria ultrastructure under both irrigated and water deficit conditions.

  16. Chloroplast Genome Sequence of the Moss Tortula ruralis: Gene Content and Structural Arrangement Relative to Other Green Plant Chloroplast Genomes

    Science.gov (United States)

    Tortula ruralis, a widely distributed moss species in the family Pottiaceae, is increasingly being used as a model organism for the study of desiccation tolerance and mechanisms of cellular repair. In this paper, we present the chloroplast genome sequence of Tortula ruralis, only the second publishe...

  17. Electronic neural network for solving traveling salesman and similar global optimization problems

    Science.gov (United States)

    Thakoor, Anilkumar P. (Inventor); Moopenn, Alexander W. (Inventor); Duong, Tuan A. (Inventor); Eberhardt, Silvio P. (Inventor)

    1993-01-01

    This invention is a novel high-speed neural network based processor for solving the 'traveling salesman' and other global optimization problems. It comprises a novel hybrid architecture employing a binary synaptic array whose embodiment incorporates the fixed rules of the problem, such as the number of cities to be visited. The array is prompted by analog voltages representing variables such as distances. The processor incorporates two interconnected feedback networks, each of which solves part of the problem independently and simultaneously, yet which exchange information dynamically.

  18. Optimizing the electronic control loop of a solid-state ring laser gyroscope

    OpenAIRE

    Schwartz, Sylvain; Rebut, Maxence; Feugnet, Gilles; Colineau, Joseph; Pocholle, Jean-Paul

    2007-01-01

    We study in this Letter the dynamical effects of the limited bandwidth of the control electronics in a solid-state (Nd-YAG) ring laser gyroscope. We derive a stability condition for the rotation-sensing regime in the case of a first-order control loop, showing that the smallest measurable rotation speed depends directly on the cutoff frequency value. Our experimental measurements are in good agreement with this prediction.

  19. Electronic Medical Records Optimize Clinical Data Management in the Outpatient Cardiological Clinic

    OpenAIRE

    Dalmiani, Stefano; Morales, Maria Aurora; Carpeggiani, Clara; Macerata, Alberto; Marcheschi, Paolo

    2003-01-01

    A system based on a relational database with administrative and clinical information and integrated with an Information System, where the system covers the role of a Functional Island, is routinely used in our Institution. To analyze how Electronic Medical Records (EMR) may help physicians in organizing and reducing time waste in a busy outpatient clinic, a sample of 1000 reports were evaluated for system performance. The time needed for building new clinical histories or modifying the alread...

  20. Bunch evolution study in optimization of MeV ultrafast electron diffraction

    OpenAIRE

    Lu, Xianhai; Du, Yingchao; Huang, Wenhui; Tang, Chuanxiang

    2014-01-01

    Megaelectronvolt ultrafast electron diffraction (UED) is a promising detection tool for ultrafast processes. The quality of diffraction image is determined by the transverse evolution of the probe bunch. In this paper, we study the contributing terms of the emittance and space charge effects to the bunch evolution in MeV UED scheme, employing a mean-field model with an ellipsoidal distribution as well as particle tracking simulation. Small transverse dimension of the drive laser is found crit...

  1. Transmission electron microscopy for the evaluation and optimization of crystal growth

    Energy Technology Data Exchange (ETDEWEB)

    Stevenson, Hilary P.; Lin, Guowu; Barnes, Christopher O.; Sutkeviciute, Ieva; Krzysiak, Troy; Weiss, Simon C.; Reynolds, Shelley; Wu, Ying; Nagarajan, Veeranagu; Makhov, Alexander M.; Lawrence, Robert; Lamm, Emily; Clark, Lisa; Gardella, Timothy J.; Hogue, Brenda G.; Ogata, Craig M.; Ahn, Jinwoo; Gronenborn, Angela M.; Conway, James F.; Vilardaga, Jean-Pierre; Cohen, Aina E.; Calero, Guillermo

    2016-04-26

    The crystallization of protein samples remains the most significant challenge in structure determination by X-ray crystallography. Here, the effectiveness of transmission electron microscopy (TEM) analysis to aid in the crystallization of biological macromolecules is demonstrated. It was found that the presence of well ordered lattices with higher order Bragg spots, revealed by Fourier analysis of TEM images, is a good predictor of diffraction-quality crystals. Moreover, the use of TEM allowed (i) comparison of lattice quality among crystals from different conditions in crystallization screens; (ii) the detection of crystal pathologies that could contribute to poor X-ray diffraction, including crystal lattice defects, anisotropic diffraction and crystal contamination by heavy protein aggregates and nanocrystal nuclei; (iii) the qualitative estimation of crystal solvent content to explore the effect of lattice dehydration on diffraction and (iv) the selection of high-quality crystal fragments for microseeding experiments to generate reproducibly larger sized crystals. Applications to X-ray free-electron laser (XFEL) and micro-electron diffraction (microED) experiments are also discussed.

  2. Transmission electron microscopy for the evaluation and optimization of crystal growth.

    Science.gov (United States)

    Stevenson, Hilary P; Lin, Guowu; Barnes, Christopher O; Sutkeviciute, Ieva; Krzysiak, Troy; Weiss, Simon C; Reynolds, Shelley; Wu, Ying; Nagarajan, Veeranagu; Makhov, Alexander M; Lawrence, Robert; Lamm, Emily; Clark, Lisa; Gardella, Timothy J; Hogue, Brenda G; Ogata, Craig M; Ahn, Jinwoo; Gronenborn, Angela M; Conway, James F; Vilardaga, Jean Pierre; Cohen, Aina E; Calero, Guillermo

    2016-05-01

    The crystallization of protein samples remains the most significant challenge in structure determination by X-ray crystallography. Here, the effectiveness of transmission electron microscopy (TEM) analysis to aid in the crystallization of biological macromolecules is demonstrated. It was found that the presence of well ordered lattices with higher order Bragg spots, revealed by Fourier analysis of TEM images, is a good predictor of diffraction-quality crystals. Moreover, the use of TEM allowed (i) comparison of lattice quality among crystals from different conditions in crystallization screens; (ii) the detection of crystal pathologies that could contribute to poor X-ray diffraction, including crystal lattice defects, anisotropic diffraction and crystal contamination by heavy protein aggregates and nanocrystal nuclei; (iii) the qualitative estimation of crystal solvent content to explore the effect of lattice dehydration on diffraction and (iv) the selection of high-quality crystal fragments for microseeding experiments to generate reproducibly larger sized crystals. Applications to X-ray free-electron laser (XFEL) and micro-electron diffraction (microED) experiments are also discussed. PMID:27139624

  3. Optimal Operation of Distribution Electronic Power Transformer Using Linear Quadratic Regulator Method

    Directory of Open Access Journals (Sweden)

    Mohammad Hosein Rezaei

    2011-10-01

    Full Text Available Transformers perform many functions such as voltage transformation, isolation and noise decoupling. They are indispensable components in electric power distribution system. However, at low frequencies (50 Hz, they are one of the heaviest and the most expensive equipment in an electrical distribution system. Nowadays, electronic power transformers are used instead of conventional power transformers that do voltage transformation and power delivery in power system by power electronic converter. In this paper, the structure of distribution electronic power transformer (DEPT are analized and then paid attention on the design of a linear-quadratic-regulator (LQR with integral action to improve dynamic performance of DEPT with voltage unbalance, voltage sags, voltage harmonics and voltage flicker. The presentation control strategy is simulated by MATLAB/SIMULINK. In addition, the results that are in terms of dc-link reference voltage, input and output voltages clearly show that a better dynamic performance can be achieved by using the LQR method when compared to other techniques.

  4. Functional proteomics of barley and barley chloroplasts – strategies, methods and perspectives

    DEFF Research Database (Denmark)

    Petersen, Jørgen; Rogowska-Wrzesinska, Adelina; Jensen, Ole Nørregaard

    2013-01-01

    whole-genome sequencing of barley revealed approximately 26,100 open reading frames, which provides a foundation for detailed molecular studies of barley by functional genomics and proteomics approaches. Such studies will provide further insights into the mechanisms of, for example, drought and stress......Barley (Hordeum vulgare) is an important cereal grain that is used in a range of products for animal and human consumption. Crop yield and seed quality has been optimized during decades by plant breeding programs supported by biotechnology and molecular biology techniques. The recently completed...... tolerance, micronutrient utilization, and photosynthesis in barley. In the present review we present the current state of proteomics research for investigations of barley chloroplasts, i.e., the organelle that contain the photosynthetic apparatus in the plant. We describe several different proteomics...

  5. A set of 100 chloroplast DNA primer pairs to study population genetics and phylogeny in monocotylenons

    DEFF Research Database (Denmark)

    Scarcelli, Nora; Bernaud, Adeline; Eiserhardt, Wolf L.;

    2011-01-01

    developed a new set of 100 primer pairs optimized for amplification in Monocotyledons. Primer pairs amplify coding (exon) and non-coding regions (intron and intergenic spacer). They span the different chloroplast regions: 72 are located in the LSC, 13 in the Small Single Copy (SSC) and 15 in the Inverted...... most variable loci (rps15-ycf1, rpl32-ccsA, ndhF-rpl32, ndhG-ndhI and ccsA) are located in the SSC. Through the analysis of the genetic structure of a wild-cultivated species complex in Dioscorea, we demonstrated that this new set of primers is of great interest for population genetics and we...

  6. Chlamydomonas reinhardtii chloroplasts contain a homodimeric pyruvate:ferredoxin oxidoreductase that functions with FDX1.

    Science.gov (United States)

    van Lis, Robert; Baffert, Carole; Couté, Yohann; Nitschke, Wolfgang; Atteia, Ariane

    2013-01-01

    Eukaryotic algae have long been known to live in anoxic environments, but interest in their anaerobic energy metabolism has only recently gained momentum, largely due to their utility in biofuel production. Chlamydomonas reinhardtii figures remarkably in this respect, because it efficiently produces hydrogen and its genome harbors many genes for anaerobic metabolic routes. Central to anaerobic energy metabolism in many unicellular eukaryotes (protists) is pyruvate:ferredoxin oxidoreductase (PFO), which decarboxylates pyruvate and forms acetyl-coenzyme A with concomitant reduction of low-potential ferredoxins or flavodoxins. Here, we report the biochemical properties of the homodimeric PFO of C. reinhardtii expressed in Escherichia coli. Electron paramagnetic resonance spectroscopy of the recombinant enzyme (Cr-rPFO) showed three distinct [4Fe-4S] iron-sulfur clusters and a thiamine pyrophosphate radical upon reduction by pyruvate. Purified Cr-rPFO exhibits a specific decarboxylase activity of 12 µmol pyruvate min⁻¹ mg⁻¹ protein using benzyl viologen as electron acceptor. Despite the fact that the enzyme is very oxygen sensitive, it localizes to the chloroplast. Among the six known chloroplast ferredoxins (FDX1-FDX6) in C. reinhardtii, FDX1 and FDX2 were the most efficient electron acceptors from Cr-rPFO, with comparable apparent K(m) values of approximately 4 µm. As revealed by immunoblotting, anaerobic conditions that lead to the induction of CrPFO did not increase levels of either FDX1 or FDX2. FDX1, being by far the most abundant ferredoxin, is thus likely the partner of PFO in C. reinhardtii. This finding postulates a direct link between CrPFO and hydrogenase and provides new opportunities to better study and engineer hydrogen production in this protist. PMID:23154536

  7. Simulation and optimization for a 30-MeV electron accelerator driven neutron source

    International Nuclear Information System (INIS)

    A neutron source driven by electron accelerator is proposed in Shanghai Institute of Applied Physics (SINAP). The facility is planned for the study of nuclear data in Thorium-Uranium cycling system, and for material research. A detailed simulation of the neutron source is performed for the program to get the neutron generation maximum economically. Several parameters of the facility, which affect the neutron yield and the neutron escape from outer surface of the target, are analyzed respectively. Besides, the yielding neutron spectrum and the escaping neutron angular distribution are calculated and discussed. (authors)

  8. Bunch evolution study in optimization of MeV ultrafast electron diffraction

    CERN Document Server

    Lu, Xianhai; Huang, Wenhui; Tang, Chuanxiang

    2014-01-01

    Megaelectronvolt ultrafast electron diffraction (UED) is a promising detection tool for ultrafast processes. The quality of diffraction image is determined by the transverse evolution of the probe bunch. In this paper, we study the contributing terms of the emittance and space charge effects to the bunch evolution in MeV UED scheme, employing a mean-field model with an ellipsoidal distribution as well as particle tracking simulation. Small transverse dimension of the drive laser is found critical to improve the reciprocal resolution, exploiting both smaller emittance and larger transverse bunch size before the solenoid. The degradation of reciprocal spatial resolution caused by the space charge effects should be carefully controlled.

  9. Optimization of ohmic contact for InP-based transferred electronic devices

    International Nuclear Information System (INIS)

    The effect of the annealing time and annealing temperature on Ni/Ge/Au electrode contacts deposited on the n-type InP contact layer has been studied using a circular transmission line model. The minimum specific contact resistance of 3.2 × 10−7 Ω·cm2 was achieved on the low-doped n-type InP contact layer with a 40 s anneal at 425 °C. In order to improve the ohmic contact and reduce the difficulty in the fabrication of the high doped InP epi-layer, the doping concentration in the InP contact layer was chosen to be 5 × 1018 cm−3 in the fabrication of transferred electronic devices. Excellent differential negative resistance properties were obtained by an electron beam evaporating the Ni/Ge/Au/Ge/Ni/Au composite electrode on an InP epi-layer with a 60 s anneal at 380 °C. (semiconductor technology)

  10. Modeling an optical magnetometer with electronic circuits — analysis and optimization

    International Nuclear Information System (INIS)

    Optical magnetometers are currently able to achieve magnetometric sensitivities below 1 fT/Hz1/2. Although such sensitivities are typically obtained for ultra-low-field measurements, a group of optical magnetometers allows the detection of the fields in a much broader dynamic range without a significant compromise in the sensitivity. A particular example of such a device is the magnetometer exploiting amplitude-modulated nonlinear magneto-optical rotation. It enables measurement of a magnetic field via detection of a polarization state of light traversing a medium subjected to the field. In this paper, an electronic-circuit analogue of such the magnetometer is elaborated. Its operation is investigated with an electronic-circuit design software, which allows to study the ''magnetometer'' performance as a function of various parameters. The ability to automate operation of the magnetometer and automatically track ''magnetic field'' is demonstrated. The simulations are verified with experimental results obtained with the true magnetometer operating in one of the investigated arrangements.

  11. Combined modulated electron and photon beams planned by a Monte-Carlo-based optimization procedure for accelerated partial breast irradiation

    Science.gov (United States)

    Atriana Palma, Bianey; Ureba Sánchez, Ana; Salguero, Francisco Javier; Arráns, Rafael; Míguez Sánchez, Carlos; Walls Zurita, Amadeo; Romero Hermida, María Isabel; Leal, Antonio

    2012-03-01

    The purpose of this study was to present a Monte-Carlo (MC)-based optimization procedure to improve conventional treatment plans for accelerated partial breast irradiation (APBI) using modulated electron beams alone or combined with modulated photon beams, to be delivered by a single collimation device, i.e. a photon multi-leaf collimator (xMLC) already installed in a standard hospital. Five left-sided breast cases were retrospectively planned using modulated photon and/or electron beams with an in-house treatment planning system (TPS), called CARMEN, and based on MC simulations. For comparison, the same cases were also planned by a PINNACLE TPS using conventional inverse intensity modulated radiation therapy (IMRT). Normal tissue complication probability for pericarditis, pneumonitis and breast fibrosis was calculated. CARMEN plans showed similar acceptable planning target volume (PTV) coverage as conventional IMRT plans with 90% of PTV volume covered by the prescribed dose (Dp). Heart and ipsilateral lung receiving 5% Dp and 15% Dp, respectively, was 3.2-3.6 times lower for CARMEN plans. Ipsilateral breast receiving 50% Dp and 100% Dp was an average of 1.4-1.7 times lower for CARMEN plans. Skin and whole body low-dose volume was also reduced. Modulated photon and/or electron beams planned by the CARMEN TPS improve APBI treatments by increasing normal tissue sparing maintaining the same PTV coverage achieved by other techniques. The use of the xMLC, already installed in the linac, to collimate photon and electron beams favors the clinical implementation of APBI with the highest efficiency.

  12. The study of optimal conditions of electrochemical etching of tunnel electron microscopy tungsten tips

    International Nuclear Information System (INIS)

    We present the experimental results obtained during the study made in the electrochemical etching of tunneling electron microscopy tungsten tips. The experiments was made using DC and two usual electrolytes: KOH and NaOH. For the tip preparation we used a electrochemical cell with stainless steel cathode and the tungsten wire as anode. the electrodes was introduced in a glass recipient containing the electrolytic solution. We study the effects of applied voltage, polish time, tip length and electrolyte concentration as process relevant parameters. The best condition for tip preparation was obtained with a metallurgical microscope and with a SEM.EDX and Auger analysis was made. The results shown the better tips was made with KOH as electrolyte with a limited concentration range (2-4 normal) and applied voltage (2-6 volts) (Author) 20 refs

  13. Optimization of a coaxial electron cyclotron resonance plasma thruster with an analytical model

    Energy Technology Data Exchange (ETDEWEB)

    Cannat, F., E-mail: felix.cannat@onera.fr, E-mail: felix.cannat@gmail.com; Lafleur, T. [Physics and Instrumentation Department, Onera -The French Aerospace Lab, Palaiseau, Cedex 91123 (France); Laboratoire de Physique des Plasmas, CNRS, Sorbonne Universites, UPMC Univ Paris 06, Univ Paris-Sud, Ecole Polytechnique, 91128 Palaiseau (France); Jarrige, J.; Elias, P.-Q.; Packan, D. [Physics and Instrumentation Department, Onera -The French Aerospace Lab, Palaiseau, Cedex 91123 (France); Chabert, P. [Laboratoire de Physique des Plasmas, CNRS, Sorbonne Universites, UPMC Univ Paris 06, Univ Paris-Sud, Ecole Polytechnique, 91128 Palaiseau (France)

    2015-05-15

    A new cathodeless plasma thruster currently under development at Onera is presented and characterized experimentally and analytically. The coaxial thruster consists of a microwave antenna immersed in a magnetic field, which allows electron heating via cyclotron resonance. The magnetic field diverges at the thruster exit and forms a nozzle that accelerates the quasi-neutral plasma to generate a thrust. Different thruster configurations are tested, and in particular, the influence of the source diameter on the thruster performance is investigated. At microwave powers of about 30 W and a xenon flow rate of 0.1 mg/s (1 SCCM), a mass utilization of 60% and a thrust of 1 mN are estimated based on angular electrostatic probe measurements performed downstream of the thruster in the exhaust plume. Results are found to be in fair agreement with a recent analytical helicon thruster model that has been adapted for the coaxial geometry used here.

  14. Data Mining and Electronic Health Records: Selecting Optimal Clinical Treatments in Practice

    CERN Document Server

    Bennett, Casey

    2011-01-01

    Electronic health records (EHR's) are only a first step in capturing and utilizing health-related data - the problem is turning that data into useful information. Models produced via data mining and predictive analysis profile inherited risks and environmental/behavioral factors associated with patient disorders, which can be utilized to generate predictions about treatment outcomes. This can form the backbone of clinical decision support systems driven by live data based on the actual population. The advantage of such an approach based on the actual population is that it is "adaptive". Here, we evaluate the predictive capacity of a clinical EHR of a large mental healthcare provider (~75,000 distinct clients a year) to provide decision support information in a real-world clinical setting. Initial research has achieved a 70% success rate in predicting treatment outcomes using these methods.

  15. Analysis and optimization of a mode of industrial product processing at an electron accelerator

    International Nuclear Information System (INIS)

    By means of computer simulation, the factors determinating non-uniformity of the volume distribution of the absorbed dose at product processing by scanned electron beam, namely, the energy spectrum and scanning mode, product density and homogeneity of its distribution, as well as the distance between the objects moving through the irradiation zone, are studied. On the basis of the PENELOPE-2008 package, a code for calculating the dose distribution and its non-uniformity coefficient with due regard to the beam characteristics, surface density and velocity of the object, has been developed. Verification of the code was carried out by comparison of simulation results with the experimental data obtained using a reference polystyrene calorimeter RISO as well as by dose mapping in a standard phantom

  16. Bunch evolution study in optimization of MeV ultrafast electron diffraction

    Science.gov (United States)

    Lu, Xian-Hai; Du, Ying-Chao; Huang, Wen-Hui; Tang, Chuan-Xiang

    2014-12-01

    Megaelectronvolt ultrafast electron diffraction (UED) is a promising detection tool for ultrafast processes. The quality of diffraction image is determined by the transverse evolution of the probe bunch. In this paper, we study the contributing terms of the emittance and space charge effects to the bunch evolution in the MeV UED scheme, employing a mean-field model with an ellipsoidal distribution as well as particle tracking simulation. The small transverse dimension of the drive laser is found to be critical to improve the reciprocal resolution, exploiting both smaller emittance and larger transverse bunch size before the solenoid. The degradation of the reciprocal spatial resolution caused by the space charge effects should be carefully controlled.

  17. Superconductivity-Induced Self-Energy Evolution of the Nodal Electron in Optimally-Doped Bi2212

    Energy Technology Data Exchange (ETDEWEB)

    Lee, W.S.

    2010-05-03

    The temperature dependent evolution of the renormalization effect in optimally-doped Bi2212 along the nodal direction has been studied via angle-resolved photoemission spectroscopy. Fine structure is observed in the real part of the self-energy (Re{Sigma}), including a subkink and maximum, suggesting that electrons couple to a spectrum of bosonic modes, instead of just one mode. Upon cooling through the superconducting phase transition, the fine structures of the extracted Re{Sigma} exhibit a two-processes evolution demonstrating an interplay between kink renormalization and superconductivity. We show that this two-process evolution can be qualitatively explained by a simple Holstein model in which a spectrum of bosonic modes is considered.

  18. Tools for Model Building and Optimization into Near-Atomic Resolution Electron Cryo-Microscopy Density Maps.

    Science.gov (United States)

    DiMaio, F; Chiu, W

    2016-01-01

    Electron cryo-microscopy (cryoEM) has advanced dramatically to become a viable tool for high-resolution structural biology research. The ultimate outcome of a cryoEM study is an atomic model of a macromolecule or its complex with interacting partners. This chapter describes a variety of algorithms and software to build a de novo model based on the cryoEM 3D density map, to optimize the model with the best stereochemistry restraints and finally to validate the model with proper protocols. The full process of atomic structure determination from a cryoEM map is described. The tools outlined in this chapter should prove extremely valuable in revealing atomic interactions guided by cryoEM data. PMID:27572730

  19. Localisation of chlorophyll within the chloroplast

    NARCIS (Netherlands)

    Thomas, J.B.; Post, L.C.; Vertregt, N.

    1954-01-01

    Silver nitrate reduction was shown to occur in illuminated suspensions of Hibiscus grana. The action spectrum of this reduction, the reaction, proved to coincide satisfactorily with the chlorophyll absorption spectrum. Electron micrographs reveal that this reaction occurs in single lamellae. From

  20. Learning the Languages of the Chloroplast: Retrograde Signaling and Beyond.

    Science.gov (United States)

    Chan, Kai Xun; Phua, Su Yin; Crisp, Peter; McQuinn, Ryan; Pogson, Barry J

    2016-04-29

    The chloroplast can act as an environmental sensor, communicating with the cell during biogenesis and operation to change the expression of thousands of proteins. This process, termed retrograde signaling, regulates expression in response to developmental cues and stresses that affect photosynthesis and yield. Recent advances have identified many signals and pathways-including carotenoid derivatives, isoprenes, phosphoadenosines, tetrapyrroles, and heme, together with reactive oxygen species and proteins-that build a communication network to regulate gene expression, RNA turnover, and splicing. However, retrograde signaling pathways have been viewed largely as a means of bilateral communication between organelles and nuclei, ignoring their potential to interact with hormone signaling and the cell as a whole to regulate plant form and function. Here, we discuss new findings on the processes by which organelle communication is initiated, transmitted, and perceived, not only to regulate chloroplastic processes but also to intersect with cellular signaling and alter physiological responses. PMID:26735063

  1. The complete chloroplast genome sequence of Fagopyrum cymosum.

    Science.gov (United States)

    Yang, Jun; Lu, Chaolong; Shen, Qi; Yan, Yuying; Xu, Changjiang; Song, Chi

    2016-07-01

    Fagopyrum cymosum is a traditional medicinal plant. In this study, the complete chloroplast genome of Fagopyrum cymosum is presented. The total genome size is 160,546 bp in length, containing a pair of inverted repeats (IRs) of 32,598 bp, separated by large single copy (LSC) and small single copy (SSC) of 84,237 bp and 11,014 bp, respectively. Overall GC contents of the genome were 36.9%. The chloroplast genome harbors 126 annotated genes, including 91 protein coding genes, 29 tRNA genes, and six rRNA genes. Eighteen genes contain one or two introns. Phylogenetic analyses indicated a clear evolutionary relationship among species of Caryophyllales. PMID:26119127

  2. The complete chloroplast genome of Torreya fargesii (Taxaceae).

    Science.gov (United States)

    Tao, Ke; Gao, Lei; Li, Jia; Chen, Shanshan; Su, Yingjuan; Wang, Ting

    2016-09-01

    The complete chloroplast genome sequence of Torreya fargesii (Taxaceae), a relic plant endemic to China, is presented in this study. The genome is 137 075 bp in length, with 35.47% average GC content. One copy of the large inverted repeats is lost from this genome. The T. fargesii chloroplast genome encodes 118 unique genes, in which trnI-CAU, trnQ-UUG, trnN-GUU are duplicated. Protein-coding, tRNA and rRNA genes represent 54.7%, 1.9% and 3.4% of the genome, respectively. There are 17 intron-containing genes, of which 6 are tRNA genes. A maximum likelihood phylogenetic analysis revealed a strong sister relationship between Torreya and Amentotaxus. PMID:27158868

  3. The complete chloroplast genome of North American ginseng, Panax quinquefolius.

    Science.gov (United States)

    Han, Zeng-Jie; Li, Wei; Liu, Yuan; Gao, Li-Zhi

    2016-09-01

    We report complete nucleotide sequence of the Panax quinquefolius chloroplast genome using next-generation sequencing technology. The genome size is 156 359 bp, including two inverted repeats (IRs) of 52 153 bp, separated by the large single-copy (LSC 86 184 bp) and small single-copy (SSC 18 081 bp) regions. This cp genome encodes 114 unigenes (80 protein-coding genes, four rRNA genes, and 30 tRNA genes), in which 18 are duplicated in the IR regions. Overall GC content of the genome is 38.08%. A phylogenomic analysis of the 10 complete chloroplast genomes from Araliaceae using Daucus carota from Apiaceae as outgroup showed that P. quinquefolius is closely related to the other two members of the genus Panax, P. ginseng and P. notoginseng. PMID:27158867

  4. Chloroplast engineering: boon for third - world countries as therapeutic proteins

    Directory of Open Access Journals (Sweden)

    M. Kumari

    2014-12-01

    Full Text Available Chloroplasts are the site of photosynthesis in plants mostly seen in leaves and some eukaryotic algae that provides the primary sources of the world’s food productivity. Plastids of higher plants are generally semiautonomous with 120–150 kb genome. Chloroplast transformation has become an attractive alternative to nuclear gene transformation due to its advantages, high protein levels, the feasibility of expressing multiple proteins from polycistronic mRNAs, and gene containment through the lack of pollen transmission. The review presents the recent trends and methods for plastid genome engineering and transgene expression and summarizes the potential of plastid transformation in various fields of biotechnology and also as a source of therapeutic proteins.

  5. Electron Irradiation of Conjunctival Lymphoma-Monte Carlo Simulation of the Minute Dose Distribution and Technique Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Brualla, Lorenzo, E-mail: lorenzo.brualla@uni-due.de [NCTeam, Strahlenklinik, Universitaetsklinikum Essen, Essen (Germany); Zaragoza, Francisco J.; Sempau, Josep [Institut de Tecniques Energetiques, Universitat Politecnica de Catalunya, Barcelona (Spain); Wittig, Andrea [Department of Radiation Oncology, University Hospital Giessen and Marburg, Philipps-University Marburg, Marburg (Germany); Sauerwein, Wolfgang [NCTeam, Strahlenklinik, Universitaetsklinikum Essen, Essen (Germany)

    2012-07-15

    Purpose: External beam radiotherapy is the only conservative curative approach for Stage I non-Hodgkin lymphomas of the conjunctiva. The target volume is geometrically complex because it includes the eyeball and lid conjunctiva. Furthermore, the target volume is adjacent to radiosensitive structures, including the lens, lacrimal glands, cornea, retina, and papilla. The radiotherapy planning and optimization requires accurate calculation of the dose in these anatomical structures that are much smaller than the structures traditionally considered in radiotherapy. Neither conventional treatment planning systems nor dosimetric measurements can reliably determine the dose distribution in these small irradiated volumes. Methods and Materials: The Monte Carlo simulations of a Varian Clinac 2100 C/D and human eye were performed using the PENELOPE and PENEASYLINAC codes. Dose distributions and dose volume histograms were calculated for the bulbar conjunctiva, cornea, lens, retina, papilla, lacrimal gland, and anterior and posterior hemispheres. Results: The simulated results allow choosing the most adequate treatment setup configuration, which is an electron beam energy of 6 MeV with additional bolus and collimation by a cerrobend block with a central cylindrical hole of 3.0 cm diameter and central cylindrical rod of 1.0 cm diameter. Conclusions: Monte Carlo simulation is a useful method to calculate the minute dose distribution in ocular tissue and to optimize the electron irradiation technique in highly critical structures. Using a voxelized eye phantom based on patient computed tomography images, the dose distribution can be estimated with a standard statistical uncertainty of less than 2.4% in 3 min using a computing cluster with 30 cores, which makes this planning technique clinically relevant.

  6. Optimization of a low-pressure hollow-anode electrical discharge for generation of high-current electron beams

    International Nuclear Information System (INIS)

    We report results on the optimization of the design of a high-current hollow-anode (HA) electrical discharge electron beam source that is triggered by a ferroelectric surface discharge. For the ferroelectric sample, we used a BaTi solid solution with a large dielectric constant (ε ∼ 1600). Three different electric schemes for ignition and sustainment of the HA discharge were investigated. The studied HA designs allow reliable ignition and sustainment of the discharge with current amplitude of up to 1.2 kA and pulse duration of up to 2x10-5 s, with and without gas flooding. It was found that the rise time of the discharge current monotonically decreases from ∼10-7.5 μs with the increase of the background pressure from 4x10-5 to 7x10-5 Torr. Generation of high-current electron beams was demonstrated under an accelerating voltage of up to 300 kV and ∼400 ns pulse duration. It was shown that the use of an optimal resistor which supplies an auto-bias potential to the HA output grid eliminates almost entirely the plasma pre-filling of the accelerating gap prior to the application of the accelerating pulse. In addition, it was found that within a certain range of time delays (12.5-15.5 μs) of the application of the accelerating pulse with respect to the beginning of the HA discharge, the amplitude of the diode current remains practically unchanged in spite of a considerable decrease in the amplitude of the discharge current

  7. Optimization of a low-pressure hollow anode electrical discharge for generation of high-current electron beams

    International Nuclear Information System (INIS)

    Full Text:We report results on the optimization of the design of a high-current hollow anode electrical discharge electron beam source triggered by a ferroelectric surface discharge. For the ferroelectric sample we used a BaTi solid solution with a large dielectric constant epsilon =: 1600. Three different electric schemes for ignition and sustaining of the hollow anode discharge were investigated. The studied hollow anode designs allow reliable ignition and sustaining of the discharge with current amplitude of up to 1.2 kA and pulse duration of up to 20 Vs, with and without gas flooding. It was found that the rise time of the discharge current monotonically decreases from N 10 vs to N 7.5 vs with the increase of the background pressure from 4 Pa to 7 Pa. Generation of high-current electron beams was demonstrated under an accelerating voltage of up to 300 kV and N 400 ns pulse duration. It was shown that the use of an optimal resistor which supplies an auto-bias potential to the hollow-anode output grid eliminates almost entirely the plasma pre-filling of the accelerating gap prior to the application of the accelerating pulse. In addition, it was found that within a certain range of time delays (12.5 vμs - 15.5 vμs) of the application of the accelerating pulse with respect to the beginning of the hollow anode discharge, the amplitude of the diode current remains practically unchanged in spite of a considerable decrease in the amplitude of the discharge current

  8. Electron Irradiation of Conjunctival Lymphoma—Monte Carlo Simulation of the Minute Dose Distribution and Technique Optimization

    International Nuclear Information System (INIS)

    Purpose: External beam radiotherapy is the only conservative curative approach for Stage I non-Hodgkin lymphomas of the conjunctiva. The target volume is geometrically complex because it includes the eyeball and lid conjunctiva. Furthermore, the target volume is adjacent to radiosensitive structures, including the lens, lacrimal glands, cornea, retina, and papilla. The radiotherapy planning and optimization requires accurate calculation of the dose in these anatomical structures that are much smaller than the structures traditionally considered in radiotherapy. Neither conventional treatment planning systems nor dosimetric measurements can reliably determine the dose distribution in these small irradiated volumes. Methods and Materials: The Monte Carlo simulations of a Varian Clinac 2100 C/D and human eye were performed using the PENELOPE and PENEASYLINAC codes. Dose distributions and dose volume histograms were calculated for the bulbar conjunctiva, cornea, lens, retina, papilla, lacrimal gland, and anterior and posterior hemispheres. Results: The simulated results allow choosing the most adequate treatment setup configuration, which is an electron beam energy of 6 MeV with additional bolus and collimation by a cerrobend block with a central cylindrical hole of 3.0 cm diameter and central cylindrical rod of 1.0 cm diameter. Conclusions: Monte Carlo simulation is a useful method to calculate the minute dose distribution in ocular tissue and to optimize the electron irradiation technique in highly critical structures. Using a voxelized eye phantom based on patient computed tomography images, the dose distribution can be estimated with a standard statistical uncertainty of less than 2.4% in 3 min using a computing cluster with 30 cores, which makes this planning technique clinically relevant.

  9. Localized hypermutation and associated gene losses in legume chloroplast genomes

    OpenAIRE

    KAVANAGH, THOMAS; WOLFE, KENNETH; POWELL, ANTOINETTE

    2010-01-01

    PUBLISHED Point mutations result from errors made during DNA replication or repair, so they are usually expected to be homogeneous across all regions of a genome. However, we have found a region of chloroplast DNA in plants related to sweetpea (Lathyrus) whose local point mutation rate is at least 20 times higher than elsewhere in the same molecule. There are very few precedents for such heterogeneity in any genome, and we suspect that the hypermutable region may be subject to an unusual p...

  10. Protein-Induced Modulation of Chloroplast Membrane Morphology

    OpenAIRE

    Machettira, Anu B.; Groß, Lucia E.; Tillmann, Bodo; Weis, Benjamin L.; Englich, Gisela; Sommer, Maik S.; Königer, Martina; Schleiff, Enrico

    2012-01-01

    Organelles are surrounded by membranes with a distinct lipid and protein composition. While it is well established that lipids affect protein functioning and vice versa, it has been only recently suggested that elevated membrane protein concentrations may affect the shape and organization of membranes. We therefore analyzed the effects of high chloroplast envelope protein concentrations on membrane structures using an in vivo approach with protoplasts. Transient expression of outer envelope p...

  11. Chloroplast gene sequences and the study of plant evolution.

    OpenAIRE

    Clegg, M T

    1993-01-01

    A large body of sequence data has accumulated for the chloroplast-encoded gene ribulose-1,5-biphosphate carboxylase/oxygenase (rbcL) as the result of a cooperative effort involving many laboratories. The data span all seed plants, including most major lineages from the angiosperms, and as such they provide an unprecedented opportunity to study plant evolutionary history. The full analysis of this large data set poses many problems and opportunities for plant evolutionary biologists and for bi...

  12. Regulation of chloroplast biogenesis: the immutans mutant of Arabidopsis

    Energy Technology Data Exchange (ETDEWEB)

    Rodermel, Steven

    2015-11-16

    The immutans (im) variegation mutant of Arabidopsis is an ideal model to gain insight into factors that control chloroplast biogenesis. im defines the gene for PTOX, a plastoquinol terminal oxidase that participates in control of thylakoid redox. Here, we report that the im defect can be suppressed during the late stages of plant development by gigantea (gi2), which defines the gene for GIGANTEA (GI), a central component of the circadian clock that plays a poorly-understood role in diverse plant developmental processes. imgi2 mutants are late-flowering and display other well-known phenotypes associated with gi2, such as starch accumulation and resistance to oxidative stress. We show that the restoration of chloroplast biogenesis in imgi2 is caused by a developmental-specific de-repression of cytokinin signaling that involves crosstalk with signaling pathways mediated by gibberellin (GA) and SPINDLY (SPY), a GA response inhibitor. Suppression of the plastid defect in imgi2 is likely caused by a relaxation of excitation pressures in developing plastids by factors contributed by gi2, including enhanced rates of photosynthesis and increased resistance to oxidative stress. Interestingly, the suppression phenotype of imgi can be mimicked by crossing im with the starch accumulation mutant, sex1, perhaps because sex1 utilizes pathways similar to gi. We conclude that our studies provide a direct genetic linkage between GIGANTEA and chloroplast biogenesis, and we construct a model of interactions between signaling pathways mediated by gi, GA, SPY, cytokinins, and sex1 that are required for chloroplast biogenesis.

  13. Chloroplast Phylogenomics Indicates that Ginkgo biloba Is Sister to Cycads

    OpenAIRE

    Wu, Chung-Shien; Chaw, Shu-Miaw; Huang, Ya-Yi

    2013-01-01

    Molecular phylogenetic studies have not yet reached a consensus on the placement of Ginkgoales, which is represented by the only living species, Ginkgo biloba (common name: ginkgo). At least six discrepant placements of ginkgo have been proposed. This study aimed to use the chloroplast phylogenomic approach to examine possible factors that lead to such disagreeing placements. We found the sequence types used in the analyses as the most critical factor in the conflicting placements of ginkgo. ...

  14. Optimal Placement and Sizing of Capacitor and Power-Electronic Interfaced Distributed Generation in Heavy Harmonic Polluted Systems

    Directory of Open Access Journals (Sweden)

    Mohamadreza Heydari Sharafdarkolai

    2014-06-01

    Full Text Available Presence of distributed generation (DG in distribution systems has significant impacts on the operational characteristics of these systems, also using capacitor for reactive compensation and loss reduction is so common. Injected harmonic currents from non-linear loads into distribution system distort all of voltages and currents and must be considered when placing the capacitor banks so that the resonance will not occur. Distributed Generation is often connected to the network via power-electronic interfaces for a proper coupling with the distribution networks. Inverters are capable of producing harmonic components and can be used as ancillary services for reducing harmonics by designing of a proper controlling system. In this paper discrete particle swarm optimization (DPSO approach is used for the optimal placement and sizing of distributed generations and capacitors in distorted distribution systems for simultaneous voltage profile improvement, loss and total harmonic distortion (THD reduction. Constraints include voltage limit, voltage THD, number/ size of capacitors and generators. For evaluating the proposed algorithm, the IEEE 33-bus test system is modified and employed.

  15. Optimization of an Electron Transport Layer to Enhance the Power Conversion Efficiency of Flexible Inverted Organic Solar Cells

    Directory of Open Access Journals (Sweden)

    Lee Kang Hyuck

    2010-01-01

    Full Text Available Abstract The photovoltaic (PV performance of flexible inverted organic solar cells (IOSCs with an active layer consisting of a blend of poly(3-hexylthiophene and [6, 6]-phenyl C61-butlyric acid methyl ester was investigated by varying the thicknesses of ZnO seed layers and introducing ZnO nanorods (NRs. A ZnO seed layer or ZnO NRs grown on the seed layer were used as an electron transport layer and pathway to optimize PV performance. ZnO seed layers were deposited using spin coating at 3,000 rpm for 30 s onto indium tin oxide (ITO-coated polyethersulphone (PES substrates. The ZnO NRs were grown using an aqueous solution method at a low temperature (90°C. The optimized device with ZnO NRs exhibited a threefold increase in PV performance compared with that of a device consisting of a ZnO seed layer without ZnO NRs. Flexible IOSCs fabricated using ZnO NRs with improved PV performance may pave the way for the development of PV devices with larger interface areas for effective exciton dissociation and continuous carrier transport paths.

  16. Non-canonical transit peptide for import into the chloroplast.

    Science.gov (United States)

    Miras, Stéphane; Salvi, Daniel; Ferro, Myriam; Grunwald, Didier; Garin, Jérôme; Joyard, Jacques; Rolland, Norbert

    2002-12-01

    The large majority of plastid proteins are nuclear-encoded and, thus, must be imported within these organelles. Unlike most of the outer envelope proteins, targeting of proteins to all other plastid compartments (inner envelope membrane, stroma, and thylakoid) is strictly dependent on the presence of a cleavable transit sequence in the precursor N-terminal region. In this paper, we describe the identification of a new envelope protein component (ceQORH) and demonstrate that its subcellular localization is limited to the inner membrane of the chloroplast envelope. Immunopurification, microsequencing of the natural envelope protein and cloning of the corresponding full-length cDNA demonstrated that this protein is not processed in the N-terminal region during its targeting to the inner envelope membrane. Transient expression experiments in plant cells were performed with truncated forms of the ceQORH protein fused to the green fluorescent protein. These experiments suggest that neither the N-terminal nor the C-terminal are essential for chloroplastic localization of the ceQORH protein. These observations are discussed in the frame of the endosymbiotic theory of chloroplast evolution and suggest that a domain of the ceQORH bacterial ancestor may have evolved so as to exclude the general requirement of an N-terminal plastid transit sequence. PMID:12368288

  17. Posttranslational modifications of FERREDOXIN-NADP+ OXIDOREDUCTASE in Arabidopsis chloroplasts.

    Science.gov (United States)

    Lehtimäki, Nina; Koskela, Minna M; Dahlström, Käthe M; Pakula, Eveliina; Lintala, Minna; Scholz, Martin; Hippler, Michael; Hanke, Guy T; Rokka, Anne; Battchikova, Natalia; Salminen, Tiina A; Mulo, Paula

    2014-12-01

    Rapid responses of chloroplast metabolism and adjustments to photosynthetic machinery are of utmost importance for plants' survival in a fluctuating environment. These changes may be achieved through posttranslational modifications of proteins, which are known to affect the activity, interactions, and localization of proteins. Recent studies have accumulated evidence about the crucial role of a multitude of modifications, including acetylation, methylation, and glycosylation, in the regulation of chloroplast proteins. Both of the Arabidopsis (Arabidopsis thaliana) leaf-type FERREDOXIN-NADP(+) OXIDOREDUCTASE (FNR) isoforms, the key enzymes linking the light reactions of photosynthesis to carbon assimilation, exist as two distinct forms with different isoelectric points. We show that both AtFNR isoforms contain multiple alternative amino termini and undergo light-responsive addition of an acetyl group to the α-amino group of the amino-terminal amino acid of proteins, which causes the change in isoelectric point. Both isoforms were also found to contain acetylation of a conserved lysine residue near the active site, while no evidence for in vivo phosphorylation or glycosylation was detected. The dynamic, multilayer regulation of AtFNR exemplifies the complex regulatory network systems controlling chloroplast proteins by a range of posttranslational modifications, which continues to emerge as a novel area within photosynthesis research. PMID:25301888

  18. Chloroplast quality control - balancing energy production and stress.

    Science.gov (United States)

    Woodson, Jesse D

    2016-10-01

    Contents 36 I. 36 II. 37 III. 37 IV. 38 V. 39 VI. 40 VII. 40 40 References 40 SUMMARY: All organisms require the ability to sense their surroundings and adapt. Such capabilities allow them to thrive in a wide range of habitats. This is especially true for plants, which are sessile and have to be genetically equipped to withstand every change in their environment. Plants and other eukaryotes use their energy-producing organelles (i.e. mitochondria and chloroplasts) as such sensors. In response to a changing cellular or external environment, these organelles can emit 'retrograde' signals that alter gene expression and/or cell physiology. This signaling is important in plants, fungi, and animals and impacts diverse cellular functions including photosynthesis, energy production/storage, stress responses, growth, cell death, ageing, and tumor progression. Originally, chloroplast retrograde signals in plants were known to lead to the reprogramming of nuclear transcription. New research, however, has pointed to additional posttranslational mechanisms that lead to chloroplast regulation and turnover in response to stress. Such mechanisms involve singlet oxygen, ubiquitination, the 26S proteasome, and cellular degradation machinery. PMID:27533783

  19. Carbonic anhydrase activity in isolated chloroplasts of chlamydomonas reinhardtii

    International Nuclear Information System (INIS)

    In a new assay of carbonic anhydrase, NaH14CO3 solution at the bottom of a sealed vessel releases 14CO3 which diffuses to the top of the vessel to be assimilated by actively photosynthesizing Chlamydomonas cells. The assay is initiated by illuminating cells and stopped by turning the light off and killing the cells with acid. Enzyme activity was estimated from acid stable radioactivity above the uncatalyzed background level. With bovine carbonic anhydrase, 1.5 Wilbur Anderson Unit (WAU) can be consistantly measured at 5-6 fold above background. Sonicated whole cells of air adapted wild type (+)gave 741.1 ± 12.4 WAU/mg chl. Intact washed cells of mixotrophically grown wall-less mutant CWD(-) and a high CO2 requiring wall-less double mutant CIA-3/CW15 (-) gave 7.1 ± 1.9 and 2.8 ± 7.8 WAU/mg chl respectively. Chloroplasts isolated from CWD and CIA-3/CW15 and subsequently disrupted gave 64.0 ± 14.7 and 2.8 ± 3.2 WAU/mg chl respectively. Chloroplast sonicate from another wall-less mutant CW15(-) gave activity comparable to CWD. Thus on a chlorophyll basis, enzyme activity in chloroplasts from mixotrophically grown cells is about 1/10th of the level found in air adapted wild type cells. CIA-3 seems to lack this activity

  20. The ALICE TPC Readout Electronics Design, performance optimization and verification of the DAQ circuit

    CERN Document Server

    Attiq, urRehman; Dieter, Røhrich

    2012-12-03

    ALICE (A Large Ion Collider Experiment) is a dedicated heavy-ion experiment at CERN’s LHC (Large Hadron Collider). It is designed to study the physics of strongly interacting matter and the quark-gluon plasma in heavy-ion collisions. It contains a large volume Time Projection Chamber (TPC) as its main tracking device. The ALICE TPC is the largest ever built gaseous TPC, both in terms of dimensions and number of read-out channels (557,578). A total number of 128 channels are packed in one TPC Front End Card (FEC) and 4,356 FECs are distributed over 216 independent readout partitions. Each readout partition steered by a single Readout Control Unit (RCU) functions as an independent unit in the data acquisition system of the TPC. The RCU functions as an interface between the FECs, Data AcQuisition system (DAQ), the Trigger and Timing Circuit (TTC) and the Detector Control System (DCS). The ALICE TPC readout electronics is in operation since the start of the LHC in November 2009. The primary objectives of the wo...

  1. Combined effects of light and water stress on chloroplast volume regulation.

    OpenAIRE

    McCain, D.C.

    1995-01-01

    A nuclear magnetic resonance technique was used to measure changes in the water content of Acer platanoides chloroplasts in leaf discs that had reached osmotic equilibrium with external solutions either in the dark or under exposure to light. Results showed that chloroplast volume regulation (CVR) maintained constant water content in the chloroplasts over a range of water potentials in the dark, but CVR failed when the water potential fell below a critical value. The critical potential was lo...

  2. Exploring photosynthesis evolution by comparative analysis of metabolic networks between chloroplasts and photosynthetic bacteria

    Directory of Open Access Journals (Sweden)

    Hou Jing

    2006-04-01

    Full Text Available Abstract Background Chloroplasts descended from cyanobacteria and have a drastically reduced genome following an endosymbiotic event. Many genes of the ancestral cyanobacterial genome have been transferred to the plant nuclear genome by horizontal gene transfer. However, a selective set of metabolism pathways is maintained in chloroplasts using both chloroplast genome encoded and nuclear genome encoded enzymes. As an organelle specialized for carrying out photosynthesis, does the chloroplast metabolic network have properties adapted for higher efficiency of photosynthesis? We compared metabolic network properties of chloroplasts and prokaryotic photosynthetic organisms, mostly cyanobacteria, based on metabolic maps derived from genome data to identify features of chloroplast network properties that are different from cyanobacteria and to analyze possible functional significance of those features. Results The properties of the entire metabolic network and the sub-network that consists of reactions directly connected to the Calvin Cycle have been analyzed using hypergraph representation. Results showed that the whole metabolic networks in chloroplast and cyanobacteria both possess small-world network properties. Although the number of compounds and reactions in chloroplasts is less than that in cyanobacteria, the chloroplast's metabolic network has longer average path length, a larger diameter, and is Calvin Cycle -centered, indicating an overall less-dense network structure with specific and local high density areas in chloroplasts. Moreover, chloroplast metabolic network exhibits a better modular organization than cyanobacterial ones. Enzymes involved in the same metabolic processes tend to cluster into the same module in chloroplasts. Conclusion In summary, the differences in metabolic network properties may reflect the evolutionary changes during endosymbiosis that led to the improvement of the photosynthesis efficiency in higher plants. Our

  3. Blocking the Metabolism of Starch Breakdown Products in Arabidopsis Leaves Triggers Chloroplast Degradation

    OpenAIRE

    Stettler, Michaela; Eicke, Simona; Mettler, Tabea; Messerli, Gaëlle; Hörtensteiner, Stefan; Zeeman, Samuel C.

    2009-01-01

    In most plants, a large fraction of photo-assimilated carbon is stored in the chloroplasts during the day as starch and remobilized during the subsequent night to support metabolism. Mutations blocking either starch synthesis or starch breakdown in Arabidopsis thaliana reduce plant growth. Maltose is the major product of starch breakdown exported from the chloroplast at night. The maltose excess 1 mutant (mex1), which lacks the chloroplast envelope maltose transporter, accumulates high levels...

  4. Development of the first chloroplast microsatellite loci in Ginkgo biloba (Ginkgoaceae) 1

    OpenAIRE

    Chun-Xiang Xie; Ming-Shui Zhao; Cheng-Xin Fu; Yun-Peng Zhao

    2013-01-01

    Premise of the study: To investigate population genetics, phylogeography, and cultivar origin of Ginkgo biloba, chloroplast microsatellite primers were developed. Methods and Results: Twenty-one chloroplast microsatellite markers were identified referring to the two published chloroplast genomes of G. biloba. Polymorphisms were assessed on four natural populations from the two refugia in China. Eight loci were detected to be polymorphic in these populations. The number of alleles per locus...

  5. CDP1, a novel component of chloroplast division site positioning system in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Min Zhang; Yong Hu; Jingjing Jia; Dapeng Li; Runjie Zhang; Hongbo Gao; Yikun He

    2009-01-01

    Chloroplasts are plant-specific organelles that evolved from endosymbiotic cyanobacteria. They divide through binary fission. Selection of the chloroplast division site is pivotal for the symmetric chloroplast division. In E. coli, positioning of the division site at the midpoint of the cell is regulated by dynamic oscillation of the Min system, which includes MinC, MinD and MinE. Homologs of Mind and MinE in plants are involved in chloroplast division. The homolog of MinC still has not been identified in higher plants. However, an FtsZ-like protein, ARC3, was found to be involved in chloroplast division site positioning. Here, we report that chloroplast division site positioning 1 (AtCDP1) is a novel chloroplast division protein involved in chloroplast division site placement in Arabidopsis. AtCDP1 was dis-covered by screening an Arabidopsis cDNA expression library in bacteria for colonies with a cell division phenotype. AtCDP1 is exclusively expressed in young green tissues in Arabidopsis. Elongated chloroplasts with multiple division sites were observed in the loss-of-function cdpl mutant. Overexpression of AtCDPI caused a chloroplast division phe-notype too. Protein interaction assays suggested that AtCDP1 may mediate the chloroplast division site positioning through the interaction with ARC3. Overall, our results indicate that AtCDP1 is a novel component of the chloroplast division site positioning system, and the working mechanism of this system is different from that of the traditional MinCDE system in prokaryotic cells.

  6. High-Throughput Sequencing of Three Lemnoideae (Duckweeds) Chloroplast Genomes from Total DNA

    OpenAIRE

    Wang, Wenqin; Messing, Joachim

    2011-01-01

    Background Chloroplast genomes provide a wealth of information for evolutionary and population genetic studies. Chloroplasts play a particularly important role in the adaption for aquatic plants because they float on water and their major surface is exposed continuously to sunlight. The subfamily of Lemnoideae represents such a collection of aquatic species that because of photosynthesis represents one of the fastest growing plant species on earth. Methods We sequenced the chloroplast genomes...

  7. Effect of growth temperature on chloroplast structure and activity in barley.

    Science.gov (United States)

    Smillie, R M; Critchley, C; Bain, J M; Nott, R

    1978-08-01

    Seedlings of barley (Hordeum vulgare L. cv. Abyssinian) were grown at constant temperature and light intensity and the properties and structure of chloroplasts in the primary leaf were examined. Seventeen growth temperatures ranging from 2 to 37 C were employed. Three major effects of the growth temperature were seen. (a) At very low and high growth temperatures chloroplast biogenesis was inhibited. This occurred in plants grown at temperatures above 32 C while growth at 2 C resulted in a mixed population of pale yellow, pale green, and green plants. (b) Chloroplasts were produced at all other temperatures tested but growth temperatures within a few degrees of those inhibitory to chloroplast development resulted in chloroplasts with abnormal properties and structure. Chloroplasts in the green plants grown at 2 and 5 C showed a number of structural peculiarities, including a characteristic crimping of granal thylakoids. Photoreductive activity, measured using ferricyanide as the Hill oxidant in the presence of gramicidin D, was high, but this activity in chloroplasts isolated from plants grown at 2 C showed thermal inactivation at temperatures 5 degrees lower than was the case with plants grown at higher temperatures. High growth temperatures (30 to 32 C) yielded chloroplasts with reduced photoreductive activity and a tendency toward the formation of large grana and disorientation of the lamellar systems with respect to one another. Chloroplasts of the most affected plants (grown at 32 C) frequently contained a very large elongated granum, with narrow intrathylakoid spaces. (c) Photoreductive activity was not constant at intermediate growth temperatures but steadily declined with decreasing growth temperatures between 27 and 11 C. Some alterations in chloroplast structure were also observed.The changes in chloroplast activity and structure indicate that acclimation to temperature takes place over the entire temperature range in which chloroplast development is

  8. Optimized calculation of the synergy conditions between electron cyclotron current drive and lower hybrid current drive on EAST

    Science.gov (United States)

    Wei, Wei; Bo-Jiang, Ding; Y, Peysson; J, Decker; Miao-Hui, Li; Xin-Jun, Zhang; Xiao-Jie, Wang; Lei, Zhang

    2016-01-01

    The optimized synergy conditions between electron cyclotron current drive (ECCD) and lower hybrid current drive (LHCD) with normal parameters of the EAST tokamak are studied by using the C3PO/LUKE code based on the understanding of the synergy mechanisms so as to obtain a higher synergistic current and provide theoretical reference for the synergistic effect in the EAST experiment. The dependences of the synergistic effect on the parameters of two waves (lower hybrid wave (LHW) and electron cyclotron wave (ECW)), including the radial position of the power deposition, the power value of the LH and EC waves, and the parallel refractive indices of the LHW (N∥) are presented and discussed. Project supported by the National Magnetic Confinement Fusion Science Program of China (Grant Nos. 2011GB102000, 2012GB103000, and 2013GB106001), the National Natural Science Foundation of China (Grant Nos. 11175206 and 11305211), the JSPS-NRF-NSFC A3 Foresight Program in the Field of Plasma Physics (Grant No. 11261140328), and the Fundamental Research Funds for the Central Universities of China (Grant No. JZ2015HGBZ0472).

  9. Alanine-EPR dosimetry in 10 MeV electron beam to optimize process parameters for food irradiation

    International Nuclear Information System (INIS)

    Absorbed dose in a food product is determined and controlled by several components of the LINAC irradiation facility as well as the product. Standardization of the parameters characterizing the facility components, process load and the irradiation conditions collectively termed as 'process parameters' are of paramount importance for successful dose delivery to the food products. In the present study alanine-EPR dosimetry system was employed to optimize the process parameters of 10 MeV electron beam of a LINAC facility for commercial irradiation of food. Three sets of experiments were carried out with different food commodities namely, mango, potato and rawa with the available product conveying system of different irradiation geometry like one sided or both sided mode of irradiation. Three dimensional dose distributions into the process load for low dose requiring food commodities (0.25 to 1 kGy) were measured in each experiment. The actual depth dose profile in food product and useful scan width of the electron beam were found out to be satisfactory for commercial radiation processing of food. Finally a scaled up experiment with commercial food product (packets of Rawa) exhibited adequate dose uniformity ratio of 3 proving the feasibility of the facility for large scale radiation processing of food commodities. (author)

  10. Optimization of Optical and Electronic properties of Carbon Fullerenes: Symmetry-Reduced C60 and Dumbbell-Like Novel Structures

    Energy Technology Data Exchange (ETDEWEB)

    Manaa, M R

    2008-06-13

    Using quantum chemical density functional calculations, we study two possible pathways for manipulating the optical and electronic properties of all-carbon fullerenes structures. In the first, the optical properties of C{sub 60} are shown to be enhanced via reduction of the perfectly spherical Ih symmetry structure to energetically feasible lower symmetries. A D{sub 3d} symmetry structure of C{sub 60} proved to be 39 meV lower in energy than the Ih conformation. This reduction in symmetry activates otherwise silent modes in the IR and Raman spectra, possibly achievable via solvation effects. In the second pathway, fusing a building block of an-all carbon hexagonal unit as a connector between two C{sub 60} cages is considered. Optimizations on a resulting series of dumbbell-like structures, molecular C{sub 126}, C{sub 132}, C{sub 138}, C{sub 144}, and C{sub 180}, impart distinct variation in the electronic properties of these novel structures with size. These structures are further shown to support stable anionic radical forms.

  11. Highly reliable field electron emitters produced from reproducible damage-free carbon nanotube composite pastes with optimal inorganic fillers

    International Nuclear Information System (INIS)

    Highly reliable field electron emitters were developed using a formulation for reproducible damage-free carbon nanotube (CNT) composite pastes with optimal inorganic fillers and a ball-milling method. We carefully controlled the ball-milling sequence and time to avoid any damage to the CNTs, which incorporated fillers that were fully dispersed as paste constituents. The field electron emitters fabricated by printing the CNT pastes were found to exhibit almost perfect adhesion of the CNT emitters to the cathode, along with good uniformity and reproducibility. A high field enhancement factor of around 10 000 was achieved from the CNT field emitters developed. By selecting nano-sized metal alloys and oxides and using the same formulation sequence, we also developed reliable field emitters that could survive high-temperature post processing. These field emitters had high durability to post vacuum annealing at 950 °C, guaranteeing survival of the brazing process used in the sealing of field emission x-ray tubes. We evaluated the field emitters in a triode configuration in the harsh environment of a tiny vacuum-sealed vessel and observed very reliable operation for 30 h at a high current density of 350 mA cm−2. The CNT pastes and related field emitters that were developed could be usefully applied in reliable field emission devices. (paper)

  12. Decision support system for the optimal location of electrical and electronic waste treatment plants: A case study in Greece

    International Nuclear Information System (INIS)

    Environmentally sound end-of-life management of Electrical and Electronic Equipment has been realised as a top priority issue internationally, both due to the waste stream's continuously increasing quantities, as well as its content in valuable and also hazardous materials. In an effort to manage Waste Electrical and Electronic Equipment (WEEE), adequate infrastructure in treatment and recycling facilities is considered a prerequisite. A critical number of such plants are mandatory to be installed in order: (i) to accommodate legislative needs, (ii) decrease transportation cost, and (iii) expand reverse logistics network and cover more areas. However, WEEE recycling infrastructures require high expenditures and therefore the decision maker need to be most precautious. In this context, special care should be given on the viability of infrastructure which is heavily dependent on facilities' location. To this end, a methodology aiming towards optimal location of Units of Treatment and Recycling is developed, taking into consideration economical together with social criteria, in an effort to interlace local acceptance and financial viability. For the decision support system's needs, ELECTRE III is adopted as a multicriteria analysis technique. The methodology's applicability is demonstrated with a real-world case study in Greece.

  13. Regulation of chloroplast number and DNA synthesis in higher plants. Final report, August 1995--August 1996

    Energy Technology Data Exchange (ETDEWEB)

    Mullet, J.E.

    1997-06-17

    The long term objective of this research is to understand the process of chloroplast development and its coordination with leaf development in higher plants. This is important because the photosynthetic capacity of plants is directly related to leaf and chloroplast development. This research focused on obtaining a detailed description of leaf development and the early steps in chloroplast development including activation of plastid DNA synthesis, changes in plastid DNA copy number, activation of chloroplast transcription and increases in plastid number per cell. The research focused on the isolation of the plastid DNA polymerase, and identification of genetic mutants which are altered in their accumulation of plastid DNA and plastid number per cell.

  14. Phosphorus compounds, proteins, nuclease and acid phosphatase activities in isolated spinach chloroplasts

    Directory of Open Access Journals (Sweden)

    E. Mikulska

    2015-05-01

    Full Text Available This paper deals with attempts to elaborate a simple method of spinach chloroplast isolation ensuring a high proportion of intact chloroplasts. We obtained 3 preparations of isolated chloroplasts. Several preliminary analyses of the obtained chloroplast fraction were also performed. Phosphorus compounds, total protein and the enzyme activities of RNase, DNase and GPase were determined. We found: 0,36-0,59% of RNA, 0,19-0,24% of DNA, 2,1-2,9% of phospholipids and 26-28% of protein. RNase activity was very high.

  15. Improving approximate-optimized effective potentials by imposing exact conditions: Theory and applications to electronic statics and dynamics

    International Nuclear Information System (INIS)

    We develop a method that can constrain any local exchange-correlation potential to preserve basic exact conditions. Using the method of Lagrange multipliers, we calculate for each set of given Kohn-Sham orbitals a constraint-preserving potential which is closest to the given exchange-correlation potential. The method is applicable to both the time-dependent (TD) and independent cases. The exact conditions that are enforced for the time-independent case are Galilean covariance, zero net force and torque, and Levy-Perdew virial theorem. For the time-dependent case we enforce translational covariance, zero net force, Levy-Perdew virial theorem, and energy balance. We test our method on the exchange (only) Krieger-Li-Iafrate (xKLI) approximate-optimized effective potential for both cases. For the time-independent case, we calculated the ground state properties of some hydrogen chains and small sodium clusters for some constrained xKLI potentials and Hartree-Fock (HF) exchange. The results (total energy, Kohn-Sham eigenvalues, polarizability, and hyperpolarizability) indicate that enforcing the exact conditions is not important for these cases. On the other hand, in the time-dependent case, constraining both energy balance and zero net force yields improved results relative to TDHF calculations. We explored the electron dynamics in small sodium clusters driven by cw laser pulses. For each laser pulse we compared calculations from TD constrained xKLI, TD partially constrained xKLI, and TDHF. We found that electron dynamics such as electron ionization and moment of inertia dynamics for the constrained xKLI are most similar to the TDHF results. Also, energy conservation is better by at least one order of magnitude with respect to the unconstrained xKLI. We also discuss the problems that arise in satisfying constraints in the TD case with a non-cw driving force.

  16. Electrons

    International Nuclear Information System (INIS)

    Fast electrons are used to produce isotopes for studying the cooper metabolism: Cu-64 in a cyclotron and Cu-67 in a linear accelerator. Localized electrons are responsible for the chemical and physiological characteristics of the trace elements. Studied are I, Cu, Co, Zn, Mo, Mn, Fe, Se, Mg. The Cu/Mo and Cu/Zn interactions are investigated. The levels of molybdenum, sulfate and zinc in the food are analysed. The role of the electrons in free radicals is discussed. The protection action of peroxidases and super oxidases against electron dangerous effect on normal physiology is also considered. Calculation of radiation damage and radiation protection is made. (author)

  17. A versatile DSP, FPGA structure optimized for rapid prototyping and digital real-time simulation of power electronic and electrical drive systems

    OpenAIRE

    Karipidis, Claus-Ulrich

    2001-01-01

    A Versatile DSP/ FPGA Structure optimized for Rapid Prototyping and Digital Real-Time Simulation of Power Electronic and Electrical Drive Systems This thesis is devoted to the development of a powerful digital computer equipped with flexible interfaces. It is designed to suit Rapid Prototyping and digital real-time simulation methods of power electronic and electrical drive (PE&ED) systems. This universal hardware basis unites the possibilities (benefit) to implement control equipment and com...

  18. Whole genome sequencing of enriched chloroplast DNA using the Illumina GAII platform

    Directory of Open Access Journals (Sweden)

    Shepherd Lara D

    2010-09-01

    Full Text Available Abstract Background Complete chloroplast genome sequences provide a valuable source of molecular markers for studies in molecular ecology and evolution of plants. To obtain complete genome sequences, recent studies have made use of the polymerase chain reaction to amplify overlapping fragments from conserved gene loci. However, this approach is time consuming and can be more difficult to implement where gene organisation differs among plants. An alternative approach is to first isolate chloroplasts and then use the capacity of high-throughput sequencing to obtain complete genome sequences. We report our findings from studies of the latter approach, which used a simple chloroplast isolation procedure, multiply-primed rolling circle amplification of chloroplast DNA, Illumina Genome Analyzer II sequencing, and de novo assembly of paired-end sequence reads. Results A modified rapid chloroplast isolation protocol was used to obtain plant DNA that was enriched for chloroplast DNA, but nevertheless contained nuclear and mitochondrial DNA. Multiply-primed rolling circle amplification of this mixed template produced sufficient quantities of chloroplast DNA, even when the amount of starting material was small, and improved the template quality for Illumina Genome Analyzer II (hereafter Illumina GAII sequencing. We demonstrate, using independent samples of karaka (Corynocarpus laevigatus, that there is high fidelity in the sequence obtained from this template. Although less than 20% of our sequenced reads could be mapped to chloroplast genome, it was relatively easy to assemble complete chloroplast genome sequences from the mixture of nuclear, mitochondrial and chloroplast reads. Conclusions We report successful whole genome sequencing of chloroplast DNA from karaka, obtained efficiently and with high fidelity.

  19. Effect of dimethyl phthalate (DMP) on germination, antioxidant system, and chloroplast ultrastructure in Cucumis sativus L.

    Science.gov (United States)

    Zhang, Ying; Zhang, Hui; Sun, Xin; Wang, Lei; Du, Na; Tao, Yue; Sun, Guoqiang; Erinle, Kehinde O; Wang, Pengjie; Zhou, Changjian; Duan, Shuwei

    2016-01-01

    Pollution of agricultural soils caused by widely employed plastic products, such as phthalic acid esters (PAEs), are becoming widespread in China, and they have become a threat to human health and the environment. However, little information is available on the influence of PAEs on vegetable crops. In this study, effects of different dimethyl phthalate (DMP) treatments (0, 30, 50, 100, and 200 mg L(-1)) on seed germination and growth of cucumber seedlings were investigated. Although germination rate showed no significant difference compared to control, seed germination time was significantly delayed at DMP greater than 50 mg L(-1). Concentrations of DMP greater than 30 mg L(-1) reduced cucumber lateral root length and number. The measurement of five physiological indexes in cucumber leaves with increasing DMP concentration revealed a decrease in leaf chlorophyll content, while proline and H2O2 contents increased. Peroxidase (POD) and catalase (CAT) activities increased in cucumber plants under 30 and 50 mg L(-1) DMP treatments compared to control; while after a 7-day treatment, these activities were seriously reduced under 100 and 200 mg L(-1) DMP treatments. According to transmission electron microscopy (TEM) micrographic images, the control and 30 mg L(-1) DMP treatments caused no change to leaf chloroplast shape with well-structured thylakoid membrane and parallel pattern of lamellae. At concentrations higher than 30 mg L(-1), DMP altered the ultrastructure of chloroplast, damaged membrane structure, disordered the lamellae, and increased the number and volume of starch grains. Moreover, the envelope of starch grains began to degrade under 200 mg L(-1) DMP treatment. PMID:26631021

  20. Two interacting coiled-coil proteins, WEB1 and PMI2, maintain the chloroplast photorelocation movement velocity in Arabidopsis

    OpenAIRE

    Kodama, Yutaka; Suetsugu, Noriyuki; Kong, Sam-Geun; Wada, Masamitsu

    2010-01-01

    Chloroplasts move toward weak light (accumulation response) and away from strong light (avoidance response). The fast and accurate movement of chloroplasts in response to ambient light conditions is essential for efficient photosynthesis and photodamage prevention in chloroplasts. Here, we report that two Arabidopsis mutants, weak chloroplast movement under blue light 1 (web1) and web2, are defective in both the avoidance and the accumulation responses. Map-based cloning revealed that both ge...

  1. A Nucleus-Encoded Chloroplast Phosphoprotein Governs Expression of the Photosystem I Subunit PsaC in Chlamydomonas reinhardtii.

    Science.gov (United States)

    Douchi, Damien; Qu, Yujiao; Longoni, Paolo; Legendre-Lefebvre, Linnka; Johnson, Xenie; Schmitz-Linneweber, Christian; Goldschmidt-Clermont, Michel

    2016-05-01

    The nucleo-cytoplasmic compartment exerts anterograde control on chloroplast gene expression through numerous proteins that intervene at posttranscriptional steps. Here, we show that the maturation of psaC mutant (mac1) of Chlamydomonas reinhardtii is defective in photosystem I and fails to accumulate psaC mRNA. The MAC1 locus encodes a member of the Half-A-Tetratricopeptide (HAT) family of super-helical repeat proteins, some of which are involved in RNA transactions. The Mac1 protein localizes to the chloroplast in the soluble fraction. MAC1 acts through the 5' untranslated region of psaC transcripts and is required for their stability. Small RNAs that map to the 5'end of psaC RNA in the wild type but not in the mac1 mutant are inferred to represent footprints of MAC1-dependent protein binding, and Mac1 expressed in bacteria binds RNA in vitro. A coordinate response to iron deficiency, which leads to dismantling of the photosynthetic electron transfer chain and in particular of photosystem I, also causes a decrease of Mac1. Overexpression of Mac1 leads to a parallel increase in psaC mRNA but not in PsaC protein, suggesting that Mac1 may be limiting for psaC mRNA accumulation but that other processes regulate protein accumulation. Furthermore, Mac 1 is differentially phosphorylated in response to iron availability and to conditions that alter the redox balance of the electron transfer chain. PMID:27113776

  2. The Unicellular Green Alga Chlamydomonas reinhardtii as an Experimental System to Study Chloroplast RNA Metabolism

    Science.gov (United States)

    Nickelsen, J.; Kück, U.

    Chloroplasts are typical organelles of photoautotrophic eukaryotic cells which drive a variety of functions, including photosynthesis. For many years the unicellular green alga Chlamydomonas reinhardtii has served as an experimental organism for studying photosynthetic processes. The recent development of molecular tools for this organism together with efficient methods of genetic analysis and the availability of many photosynthesis mutants has now made this alga a powerful model system for the analysis of chloroplast biogenesis. For example, techniques have been developed to transfer recombinant DNA into both the nuclear and the chloroplast genome. This allows both complementation tests and analyses of gene functions in vivo. Moreover, site-specific DNA recombinations in the chloroplast allow targeted gene disruption experiments which enable a "reverse genetics" to be performed. The potential of the algal system for the study of chloroplast biogenesis is illustrated in this review by the description of regulatory systems of gene expression involved in organelle biogenesis. One example concerns the regulation of trans-splicing of chloroplast mRNAs, a process which is controlled by both multiple nuclear- and chloroplast-encoded factors. The second example involves the stabilization of chloroplast mRNAs. The available data lead us predict distinct RNA elements, which interact with trans-acting factors to protect the RNA against nucleolytic attacks.

  3. Thermoelectric properties optimization of Fe{sub 2}VGa by tuning electronic density of states via titanium doping

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Pai-Chun, E-mail: pcwei68@gmail.com, E-mail: cheny2@phys.sinica.edu.tw [Institute of Physics, Academia Sinica, 11529 Taipei, Taiwan (China); Huang, Ta-Sung; Chen, Yang-Yuan, E-mail: pcwei68@gmail.com, E-mail: cheny2@phys.sinica.edu.tw [Institute of Physics, Academia Sinica, 11529 Taipei, Taiwan (China); Graduate Institute of Applied Physics, National Chengchi University, 11605 Taipei, Taiwan (China); Lin, Shu-Wei [Department of Physics, National Taiwan University, 10617 Taipei, Taiwan (China); Guo, Guang-Yu [Department of Physics, National Taiwan University, 10617 Taipei, Taiwan (China); Physics Division, National Center for Theoretical Sciences, 30013 Hsinchu, Taiwan (China)

    2015-10-28

    We report the correlation between thermoelectric properties and electronic band structure of thermoelectric Heusler alloy Fe{sub 2}V{sub 1-x}Ti{sub x}Ga by comparing experimental measurements with theoretical calculations. The electrical resistivity data show that the semiconducting-like behavior of pure Fe{sub 2}VGa is transformed to a more metallic-like behavior at x = 0.1. Meanwhile, an enhancement of the Seebeck coefficient was observed for all Ti doped specimens at elevated temperatures with a peak value of 57 μV/K for x = 0.05 at 300 K. The experimental results can be elucidated by the calculated band structure, i.e., a gradual shifting of the Fermi level from the middle of the pseudogap to the region of valence bands. With optimized doping, the thermoelectric power factor can be significantly enhanced to 3.95 mW m{sup −1} K{sup −2} at room temperature, which is comparable to the power factors of Bi{sub 2}Te{sub 3}-based compounds. The synergy of thermal conductivity reduction due to the alloying effect and the significant increase of the thermoelectric power factor leads to higher order zT values than that of prime Fe{sub 2}VGa.

  4. Recent advances in PC-Linux systems for electronic structure computations by optimized compilers and numerical libraries.

    Science.gov (United States)

    Yu, Jen-Shiang K; Yu, Chin-Hui

    2002-01-01

    One of the most frequently used packages for electronic structure research, GAUSSIAN 98, is compiled on Linux systems with various hardware configurations, including AMD Athlon (with the "Thunderbird" core), AthlonMP, and AthlonXP (with the "Palomino" core) systems as well as the Intel Pentium 4 (with the "Willamette" core) machines. The default PGI FORTRAN compiler (pgf77) and the Intel FORTRAN compiler (ifc) are respectively employed with different architectural optimization options to compile GAUSSIAN 98 and test the performance improvement. In addition to the BLAS library included in revision A.11 of this package, the Automatically Tuned Linear Algebra Software (ATLAS) library is linked against the binary executables to improve the performance. Various Hartree-Fock, density-functional theories, and the MP2 calculations are done for benchmarking purposes. It is found that the combination of ifc with ATLAS library gives the best performance for GAUSSIAN 98 on all of these PC-Linux computers, including AMD and Intel CPUs. Even on AMD systems, the Intel FORTRAN compiler invariably produces binaries with better performance than pgf77. The enhancement provided by the ATLAS library is more significant for post-Hartree-Fock calculations. The performance on one single CPU is potentially as good as that on an Alpha 21264A workstation or an SGI supercomputer. The floating-point marks by SpecFP2000 have similar trends to the results of GAUSSIAN 98 package. PMID:12086529

  5. Chloroplast genetics of chlamydomonas. II. Mapping by cosegregation frequency analysis

    International Nuclear Information System (INIS)

    This paper presents segregation and cosegregation data for a set of 15 chloroplast genes of Chlamydomonas, and uses these data to generate a linear map of the chloroplast genome. The data were derived from pedigree analysis of a total of 1596 zoospore clones resulting from 12 crosses in each of which 4 to 7 pairs of chloroplast alleles were segregating. The crosses are a subset of those previously described. By means of pedigree analysis, Type III segregations (nonreciprocal conversion-like events) were distinguished from Type III segregations (reciprocal events). The average frequency of Type II segregation was found to be the same for all 15 genes, indicating randomness of this event with respect to map location. Type III segregations occurred with a different and characteristic frequency for each gene, and were interpreted as a measure of the distance of each gene from the postulated centromere-like attachment point. Cosegregations, involving two or more genes, occurred with frequencies characteristic of the particular genes and much lower than expected for the product of single-gene events, indicating strong positive interference. Pairwise cosegregation frequencies provided unambiguous data for the gene order, confirmed by cosegregation runs of three or more genes. Apparent lengths of cosegregation runs, as fractions of the total map, indicate much longer stretches of gene conversion-like events than have been reported for other genetic systems. Comparisons of cosegregation frequencies in cross 20 after 15'', 30'', and 15'' uv irradiation of the mt+ before mating, indicate little if any consistent effect of this irradiation on segregation events

  6. Chloroplasts Are Central Players in Sugar-Induced Leaf Growth.

    Science.gov (United States)

    Van Dingenen, Judith; De Milde, Liesbeth; Vermeersch, Mattias; Maleux, Katrien; De Rycke, Riet; De Bruyne, Michiel; Storme, Véronique; Gonzalez, Nathalie; Dhondt, Stijn; Inzé, Dirk

    2016-05-01

    Leaves are the plant's powerhouses, providing energy for all organs through sugar production during photosynthesis. However, sugars serve not only as a metabolic energy source for sink tissues but also as signaling molecules, affecting gene expression through conserved signaling pathways to regulate plant growth and development. Here, we describe an in vitro experimental assay, allowing one to alter the sucrose (Suc) availability during early Arabidopsis (Arabidopsis thaliana) leaf development, with the aim to identify the affected cellular and molecular processes. The transfer of seedlings to Suc-containing medium showed a profound effect on leaf growth by stimulating cell proliferation and postponing the transition to cell expansion. Furthermore, rapidly after transfer to Suc, mesophyll cells contained fewer and smaller plastids, which are irregular in shape and contain fewer starch granules compared with control mesophyll cells. Short-term transcriptional responses after transfer to Suc revealed the repression of well-known sugar-responsive genes and multiple genes encoded by the plastid, on the one hand, and up-regulation of a GLUCOSE-6-PHOSPHATE TRANSPORTER (GPT2), on the other hand. Mutant gpt2 seedlings showed no stimulation of cell proliferation and no repression of chloroplast-encoded transcripts when transferred to Suc, suggesting that GPT2 plays a critical role in the Suc-mediated effects on early leaf growth. Our findings, therefore, suggest that induction of GPT2 expression by Suc increases the import of glucose-6-phosphate into the plastids that would repress chloroplast-encoded transcripts, restricting chloroplast differentiation. Retrograde signaling from the plastids would then delay the transition to cell expansion and stimulate cell proliferation. PMID:26932234

  7. Photosynthetic electron transport system promotes synthesis of Au-nanoparticles.

    Science.gov (United States)

    Shabnam, Nisha; Pardha-Saradhi, P

    2013-01-01

    In this communication, a novel, green, efficient and economically viable light mediated protocol for generation of Au-nanoparticles using most vital organelle, chloroplasts, of the plant system is portrayed. Thylakoids/chloroplasts isolated from Potamogeton nodosus (an aquatic plant) and Spinacia oleracea (a terrestrial plant) turned Au³⁺ solutions purple in presence of light of 600 µmol m⁻² s⁻¹ photon flux density (PFD) and the purple coloration intensified with time. UV-Vis spectra of these purple colored solutions showed absorption peak at ∼545 nm which is known to arise due to surface plasmon oscillations specific to Au-nanoparticles. However, thylakoids/chloroplasts did not alter color of Au³⁺ solutions in dark. These results clearly demonstrated that photosynthetic electron transport can reduce Au³⁺ to Au⁰ which nucleate to form Au-nanoparticles in presence of light. Transmission electron microscopic studies revealed that Au-nanoparticles generated by light driven photosynthetic electron transport system of thylakoids/chloroplasts were in range of 5-20 nm. Selected area electron diffraction and powder X-ray diffraction indicated crystalline nature of these nanoparticles. Energy dispersive X-ray confirmed that these nanoparticles were composed of Au. To confirm the potential of light driven photosynthetic electron transport in generation of Au-nanoparticles, thylakoids/chloroplasts were tested for their efficacy to generate Au-nanoparticles in presence of light of PFD ranging from 60 to 600 µmol m⁻² s⁻¹. The capacity of thylakoids/chloroplasts to generate Au-nanoparticles increased remarkably with increase in PFD, which further clearly demonstrated potential of light driven photosynthetic electron transport in reduction of Au³⁺ to Au⁰ to form nanoparticles. The light driven donation of electrons to metal ions by thylakoids/chloroplasts can be exploited for large scale production of nanoparticles. PMID:23976990

  8. Photosynthetic electron transport system promotes synthesis of Au-nanoparticles.

    Directory of Open Access Journals (Sweden)

    Nisha Shabnam

    Full Text Available In this communication, a novel, green, efficient and economically viable light mediated protocol for generation of Au-nanoparticles using most vital organelle, chloroplasts, of the plant system is portrayed. Thylakoids/chloroplasts isolated from Potamogeton nodosus (an aquatic plant and Spinacia oleracea (a terrestrial plant turned Au³⁺ solutions purple in presence of light of 600 µmol m⁻² s⁻¹ photon flux density (PFD and the purple coloration intensified with time. UV-Vis spectra of these purple colored solutions showed absorption peak at ∼545 nm which is known to arise due to surface plasmon oscillations specific to Au-nanoparticles. However, thylakoids/chloroplasts did not alter color of Au³⁺ solutions in dark. These results clearly demonstrated that photosynthetic electron transport can reduce Au³⁺ to Au⁰ which nucleate to form Au-nanoparticles in presence of light. Transmission electron microscopic studies revealed that Au-nanoparticles generated by light driven photosynthetic electron transport system of thylakoids/chloroplasts were in range of 5-20 nm. Selected area electron diffraction and powder X-ray diffraction indicated crystalline nature of these nanoparticles. Energy dispersive X-ray confirmed that these nanoparticles were composed of Au. To confirm the potential of light driven photosynthetic electron transport in generation of Au-nanoparticles, thylakoids/chloroplasts were tested for their efficacy to generate Au-nanoparticles in presence of light of PFD ranging from 60 to 600 µmol m⁻² s⁻¹. The capacity of thylakoids/chloroplasts to generate Au-nanoparticles increased remarkably with increase in PFD, which further clearly demonstrated potential of light driven photosynthetic electron transport in reduction of Au³⁺ to Au⁰ to form nanoparticles. The light driven donation of electrons to metal ions by thylakoids/chloroplasts can be exploited for large scale production of nanoparticles.

  9. The complete chloroplast genome sequence of Curcuma flaviflora (Curcuma).

    Science.gov (United States)

    Zhang, Yan; Deng, Jiabin; Li, Yangyi; Gao, Gang; Ding, Chunbang; Zhang, Li; Zhou, Yonghong; Yang, Ruiwu

    2016-09-01

    The complete chloroplast (cp) genome of Curcuma flaviflora, a medicinal plant in Southeast Asia, was sequenced. The genome size was 160 478 bp in length, with 36.3% GC content. A pair of inverted repeats (IRs) of 26 946 bp were separated by a large single copy (LSC) of 88 008 bp and a small single copy (SSC) of 18 578 bp, respectively. The cp genome contained 132 annotated genes, including 79 protein coding genes, 30 tRNA genes, and four rRNA genes. And 19 of these genes were duplicated in inverted repeat regions. PMID:26367332

  10. Biotin Carboxyl Carrier Protein in Barley Chloroplast Membranes

    DEFF Research Database (Denmark)

    Kannangara, C. G.; Jense, C J

    1975-01-01

    Biotin localized in barley chloroplast lamellae is covalently bound to a single protein with an approximate molecular weight of 21000. It contains one mole of biotin per mole of protein and functions as a carboxyl carrier in the acetyl-CoA carboxylase reaction. The protein was obtained by...... solubilization of the lamellae in phenol/acetic acid/8 M urea. Feeding barley seedlings with [14C]-biotin revealed that the vitamin is not degraded into respiratory substrates by the plant, but is specifically incorporated into biotin carboxyl carrier protein....

  11. The complete chloroplast genome sequence of Hibiscus syriacus.

    Science.gov (United States)

    Kwon, Hae-Yun; Kim, Joon-Hyeok; Kim, Sea-Hyun; Park, Ji-Min; Lee, Hyoshin

    2016-09-01

    The complete chloroplast genome sequence of Hibiscus syriacus L. is presented in this study. The genome is composed of 161 019 bp in length, with a typical circular structure containing a pair of inverted repeats of 25 745 bp of length separated by a large single-copy region and a small single-copy region of 89 698 bp and 19 831 bp of length, respectively. The overall GC content is 36.8%. One hundred and fourteen genes were annotated, including 81 protein-coding genes, 4 ribosomal RNA genes and 29 transfer RNA genes. PMID:26357910

  12. Chloroplast transformation of Platymonas (Tetraselmis subcordiformis with the bar gene as selectable marker.

    Directory of Open Access Journals (Sweden)

    Yulin Cui

    Full Text Available The objective of this research was to establish a chloroplast transformation technique for Platymonas (Tetraselmis subcordiformis. Employing the gfp gene as a reporter and the bar gene as a selectable marker, transformation vectors of P. subcordiformis chloroplast were constructed with endogenous fragments rrn16S-trnI (left and trnA-rrn23S (right as a recombination site of the chloroplast genome. The plasmids were transferred into P. subcordiformis via particle bombardment. Confocal laser scanning microscopy indicated that the green fluorescence protein was localized in the chloroplast of P. subcordiformis, confirming the activity of the Chlamydomonas reinhardtii promoter. Cells transformed with the bar gene were selected using the herbicide Basta. Resistant colonies were analyzed by PCR and Southern blotting, and the results indicated that the bar gene was successfully integrated into the chloroplast genome via homologous recombination. The technique will improve genetic engineering of this alga.

  13. Update on Chloroplast Research: New Tools, New Topics, and New Trends

    Institute of Scientific and Technical Information of China (English)

    Ute Armbruster; Paolo Pesaresi; Mathias Pribil; Alexander Hertle; Dario Leister

    2011-01-01

    Chloroplasts, the green differentiation form of plastids, are the sites of photosynthesis and other important plant functions. Genetic and genomic technologies have greatly boosted the rate of discovery and functional characterization of chloroplast proteins during the past decade. Indeed, data obtained using high-throughput methodologies, in particular proteomics and transcriptomics, are now routinely used to assign functions to chloroplast proteins. Our knowledge of many chloroplast processes, notably photosynthesis and photorespiration, has reached such an advanced state that biotechnological approaches to crop improvement now seem feasible. Meanwhile, efforts to identify the entire complement of chloroplast proteins and their interactions are progressing rapidly, making the organelle a prime target for systems biology research in plants.

  14. Optimization of the laser-induced photoemission for the production of polarized electron beams at the 50-keV source of the Bonn accelerator facility ELSA

    International Nuclear Information System (INIS)

    Medium energy experiments requiring circularly polarized photons (produced by Bremsstrahlung of longitudinally polarized electrons) have started at the electron stretcher ELSA in Bonn. To fulfill the demands of the experiment (GDH) the laser induced photoemission of the 50 keV electron source has been optimized. Systematic studies with a titan-sapphire laser to optimize the pulse structure of the laser pulse and the emitted spectral width has been done. Using a Be-InGaAs/Be-AlGaAs strained superlattice photocathode a beam polarization of 80% with a quantum efficiency of 0.4% has been obtained while producing a space charge limited 100 mA beam current. (orig.)

  15. YGL9, encoding the putative chloroplast signal recognition particle 43 kDa protein in rice, is involved in chloroplast development

    Institute of Scientific and Technical Information of China (English)

    WANG Zhong-wei; LI Yun-feng; LING Ying-hua; SANG Xian-chun; HE Guang-hua; ZHANG Tian-quan; XING Ya-di; ZENG Xiao-qin; WANG Ling; LIU Zhong-xian; SHI Jun-qiong; ZHU Xiao-yan; MA Ling

    2016-01-01

    The nuclear-encoded light-harvesting chlorophyla/b-binding proteins (LHCPs) are speciifcaly translocated from the stroma into the thylakoid membrane through the chloroplast signal recognition particle (cpSRP) pathway. The cpSRP is composed of a cpSRP43 protein and a cpSRP54 protein, and it forms a soluble transit complex with LHCP in the chloroplast stroma. Here, we identiifed theYGL9gene that is predicted to encode the probable rice cpSRP43 protein from a rice yelow-green leaf mutant. A phylogenetic tree showed that an important conserved protein family, cpSRP43, is present in almost al green photosynthetic organisms such as higher plants and green algae. Sequence analysis showed that YGL9 comprises a chloroplast transit peptide, three chromodomains and four ankyrin repeats, and the chromodomains and ankyrin repeats are probably involved in protein-protein interactions. Subcelular localization showed that YGL9 is localized in the chloroplast. Expression pattern analysis indicated thatYGL9is mainly expressed in green leaf sheaths and leaves. Quantitative real-time PCR analysis showed that the expression levels of genes associated with pigment metabolism, chloroplast development and photosynthesis were distinctly affected in theygl9mutant. These results indicated thatYGL9 is possibly involved in pigment metabolism, chloroplast development and photosynthesis in rice.

  16. Chloroplast genome sequence of the moss Tortula ruralis: gene content, polymorphism, and structural arrangement relative to other green plant chloroplast genomes

    Directory of Open Access Journals (Sweden)

    Wolf Paul G

    2010-02-01

    Full Text Available Abstract Background Tortula ruralis, a widely distributed species in the moss family Pottiaceae, is increasingly used as a model organism for the study of desiccation tolerance and mechanisms of cellular repair. In this paper, we present the chloroplast genome sequence of T. ruralis, only the second published chloroplast genome for a moss, and the first for a vegetatively desiccation-tolerant plant. Results The Tortula chloroplast genome is ~123,500 bp, and differs in a number of ways from that of Physcomitrella patens, the first published moss chloroplast genome. For example, Tortula lacks the ~71 kb inversion found in the large single copy region of the Physcomitrella genome and other members of the Funariales. Also, the Tortula chloroplast genome lacks petN, a gene found in all known land plant plastid genomes. In addition, an unusual case of nucleotide polymorphism was discovered. Conclusions Although the chloroplast genome of Tortula ruralis differs from that of the only other sequenced moss, Physcomitrella patens, we have yet to determine the biological significance of the differences. The polymorphisms we have uncovered in the sequencing of the genome offer a rare possibility (for mosses of the generation of DNA markers for fine-level phylogenetic studies, or to investigate individual variation within populations.

  17. The complete chloroplast genome of banana (Musa acuminata, Zingiberales: insight into plastid monocotyledon evolution.

    Directory of Open Access Journals (Sweden)

    Guillaume Martin

    Full Text Available BACKGROUND: Banana (genus Musa is a crop of major economic importance worldwide. It is a monocotyledonous member of the Zingiberales, a sister group of the widely studied Poales. Most cultivated bananas are natural Musa inter-(sub-specific triploid hybrids. A Musa acuminata reference nuclear genome sequence was recently produced based on sequencing of genomic DNA enriched in nucleus. METHODOLOGY/PRINCIPAL FINDINGS: The Musa acuminata chloroplast genome was assembled with chloroplast reads extracted from whole-genome-shotgun sequence data. The Musa chloroplast genome is a circular molecule of 169,972 bp with a quadripartite structure containing two single copy regions, a Large Single Copy region (LSC, 88,338 bp and a Small Single Copy region (SSC, 10,768 bp separated by Inverted Repeat regions (IRs, 35,433 bp. Two forms of the chloroplast genome relative to the orientation of SSC versus LSC were found. The Musa chloroplast genome shows an extreme IR expansion at the IR/SSC boundary relative to the most common structures found in angiosperms. This expansion consists of the integration of three additional complete genes (rps15, ndhH and ycf1 and part of the ndhA gene. No such expansion has been observed in monocots so far. Simple Sequence Repeats were identified in the Musa chloroplast genome and a new set of Musa chloroplastic markers was designed. CONCLUSION: The complete sequence of M. acuminata ssp malaccensis chloroplast we reported here is the first one for the Zingiberales order. As such it provides new insight in the evolution of the chloroplast of monocotyledons. In particular, it reinforces that IR/SSC expansion has occurred independently several times within monocotyledons. The discovery of new polymorphic markers within Musa chloroplast opens new perspectives to better understand the origin of cultivated triploid bananas.

  18. Chloroplast His-to-Asp signal transduction: a potential mechanism for plastid gene regulation in Heterosigma akashiwo (Raphidophyceae

    Directory of Open Access Journals (Sweden)

    Jacobs Michael A

    2007-05-01

    Full Text Available Abstract Background Maintenance of homeostasis requires that an organism perceive selected physical and chemical signals within an informationally dense environment. Functionally, an organism uses a variety of signal transduction arrays to amplify and convert these perceived signals into appropriate gene transcriptional responses. These changes in gene expression serve to modify selective metabolic processes and thus optimize reproductive success. Here we analyze a chloroplast-encoded His-to-Asp signal transduction circuit in the stramenopile Heterosigma akashiwo (Hada Hada ex Y. Hara et Chihara [syn. H. carterae (Hulburt F.J.R. Taylor]. The presence, structure and putative function of this protein pair are discussed in the context of their evolutionary homologues. Results Bioinformatic analysis of the Heterosigma akashiwo chloroplast genome sequence revealed the presence of a single two-component His-to-Asp (designated Tsg1/Trg1 pair in this stramenopile (golden-brown alga. These data represent the first documentation of a His-to-Asp array in stramenopiles and counter previous reports suggesting that such regulatory proteins are lacking in this taxonomic cluster. Comparison of the 43 kDa H. akashiwo Tsg1 with bacterial sensor kinases showed that the algal protein exhibits a moderately maintained PAS motif in the sensor kinase domain as well as highly conserved H, N, G1 and F motifs within the histidine kinase ATP binding site. Molecular modelling of the 27 kDa H. akashiwo Trg1 regulator protein was consistent with a winged helix-turn-helix identity – a class of proteins that is known to impact gene expression at the level of transcription. The occurrence of Trg1 protein in actively growing H. akashiwo cells was verified by Western analysis. The presence of a PhoB-like RNA polymerase loop in Trg1 and its homologues in the red-algal lineage support the hypothesis that Trg1 and its homologues interact with a sigma 70 (σ70 subunit (encoded by

  19. Electronics

    International Nuclear Information System (INIS)

    Some of the electronic equipment used in pulse counting and mean current radiation detection systems is described. This includes the high voltage supply, amplifier, amplitude discriminator, scalers or counters, ratemeters, single-channel pulse height analyser, multi-channel pulse height analyser, d.c. amplifiers, coincidence and anticoincidence units and gain stabilisers

  20. Altered cytokinin metabolism affects cytokinin, auxin, and abscisic acid contents in leaves and chloroplasts, and chloroplast ultrastructure in transgenic tobacco

    Czech Academy of Sciences Publication Activity Database

    Polanská, Lenka; Vičánková, Anna; Nováková, Marie; Malbeck, Jiří; Dobrev, Petre; Brzobohatý, Břetislav; Vaňková, Radomíra; Macháčková, Ivana

    2007-01-01

    Roč. 58, č. 3 (2007), s. 637-649. ISSN 0022-0957 R&D Projects: GA ČR GA206/03/0369; GA ČR GA206/06/1306; GA AV ČR IAA600040612 Institutional research plan: CEZ:AV0Z50380511; CEZ:AV0Z50040507 Source of funding: V - iné verejné zdroje ; V - iné verejné zdroje Keywords : abscisic acid * auxin * chloroplast ultrastructure Subject RIV: EF - Botanics Impact factor: 3.917, year: 2007

  1. The complete chloroplast genome of Cinnamomum kanehirae Hayata (Lauraceae).

    Science.gov (United States)

    Wu, Chia-Chen; Ho, Cheng-Kuen; Chang, Shu-Hwa

    2016-07-01

    The complete chloroplast genome of Cinnamomum kanehirae (Hayata), the first to be completely sequenced of Lauraceae family, is presented in this study. The total genome size is 152,700 bp, with a typical circular structure including a pair of inverted repeats (IRa/b) of 20,107 bp of length separated by a large single-copy region (LSC) and a small single-copy region (SSC) of 93,642 bp and 18,844 bp of length, respectively. The overall GC content of the genome is 39.1%. The nucleotide sequence shows 91% identities with Liriodendron tulipifera in the Magnoliaceae. In total, 123 annotated genes consisted of 79 coding genes, eight rRNA genes, and 36 tRNA genes. Among all 79 coding genes, seven genes (rpoC1, atpF, rpl2, ndhB, ndhA, rps16, and rpl2) contain one intron, while two genes (ycf3 and clpP) contain two introns. The maximum likelihood phylogenetic analysis revealed that C. kanehirae chloroplast genome is closely related to Calycanthus fertilis within Laurales order. PMID:26053940

  2. Chloroplast protein synthesis: thylakoid bound polysomes synthesize thylakoid proteins

    International Nuclear Information System (INIS)

    Previous work indicated more polysomes bound to pea thylakoids in light than in the dark, in vivo. With isolated intact chloroplasts incubated in darkness, 24 to 74% more RNA was thylakoid-bound at pH 8.3 than at pH 7. Thus the major effect of light in vivo may be due to higher stroma pH. In isolated pea chloroplasts, initiation inhibitors (pactamycin and kanamycin) decreased the extent of RNA binding, and elongation inhibitors (lincomycin and streptomycin) increased it. Thus translation initiation and termination probably control the cycling of bound ribosomes. While only 3 to 6% of total RNA is in bound polysomes the incorporation of 3H-Leu into thylakoids was proportional to the amount of this bound RNA. When Micrococcal nuclease-treated thylakoids were added to labeled runoff translation products of stroma ribosomes, less than 1% of the label adhered to the added membranes; but 37% of the labeled products made by thylakoid polysomes were bound. These data support the concept that stroma ribosomes are recruited into thylakoid proteins

  3. Unique Thylakoid Membrane Architecture of a Unicellular N2-Fixing Cyanobacterium Revealed by Electron Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Liberton, Michelle L.; Austin, Jotham R.; Berg, R. H.; Pakrasi, Himadri B.

    2011-04-01

    Cyanobacteria, descendants of the endosymbiont that gave rise to modern-day chloroplasts, are vital contributors to global biological energy conversion processes. A thorough understanding of the physiology of cyanobacteria requires detailed knowledge of these organisms at the level of cellular architecture and organization. In these prokaryotes, the large membrane protein complexes of the photosynthetic and respiratory electron transport chains function in the intracellular thylakoid membranes. Like plants, the architecture of the thylakoid membranes in cyanobacteria has direct impact on cellular bioenergetics, protein transport, and molecular trafficking. However, whole-cell thylakoid organization in cyanobacteria is not well understood. Here we present, by using electron tomography, an in-depth analysis of the architecture of the thylakoid membranes in a unicellular cyanobacterium, Cyanothece sp. ATCC 51142. Based on the results of three-dimensional tomographic reconstructions of near-entire cells, we determined that the thylakoids in Cyanothece 51142 form a dense and complex network that extends throughout the entire cell. This thylakoid membrane network is formed from the branching and splitting of membranes and encloses a single lumenal space. The entire thylakoid network spirals as a peripheral ring of membranes around the cell, an organization that has not previously been described in a cyanobacterium. Within the thylakoid membrane network are areas of quasi-helical arrangement with similarities to the thylakoid membrane system in chloroplasts. This cyanobacterial thylakoid arrangement is an efficient means of packing a large volume of membranes in the cell while optimizing intracellular transport and trafficking.

  4. Unique thylakoid membrane architecture of a unicellular N2-fixing cyanobacterium revealed by electron tomography

    Energy Technology Data Exchange (ETDEWEB)

    Liberton, Michelle; Austin II, Jotham R; Berg, R. Howard; Pakrasi, Himadri B

    2011-04-01

    Cyanobacteria, descendants of the endosymbiont that gave rise to modern-day chloroplasts, are vital contributors to global biological energy conversion processes. A thorough understanding of the physiology of cyanobacteria requires detailed knowledge of these organisms at the level of cellular architecture and organization. In these prokaryotes, the large membrane protein complexes of the photosynthetic and respiratory electron transport chains function in the intracellular thylakoid membranes. Like plants, the architecture of the thylakoid membranes in cyanobacteria has direct impact on cellular bioenergetics, protein transport, and molecular trafficking. However, whole-cell thylakoid organization in cyanobacteria is not well understood. Here we present, by using electron tomography, an in-depth analysis of the architecture of the thylakoid membranes in a unicellular cyanobacterium, Cyanothece sp. ATCC 51142. Based on the results of three-dimensional tomographic reconstructions of near-entire cells, we determined that the thylakoids in Cyanothece 51142 form a dense and complex network that extends throughout the entire cell. This thylakoid membrane network is formed from the branching and splitting of membranes and encloses a single lumenal space. The entire thylakoid network spirals as a peripheral ring of membranes around the cell, an organization that has not previously been described in a cyanobacterium. Within the thylakoid membrane network are areas of quasi-helical arrangement with similarities to the thylakoid membrane system in chloroplasts. This cyanobacterial thylakoid arrangement is an efficient means of packing a large volume of membranes in the cell while optimizing intracellular transport and trafficking.

  5. Flash X-Ray (FXR) Accelerator Optimization Electronic Time-Resolved Measurement of X-Ray Source Size

    International Nuclear Information System (INIS)

    Lawrence Livermore National Laboratory (LLNL) is currently investigating various approaches to minimize the x-ray source size on the Flash X-Ray (FXR) linear induction accelerator in order to improve x-ray flux and increase resolution for hydrodynamic radiography experiments. In order to effectively gauge improvements to final x-ray source size, a fast, robust, and accurate system for measuring the spot size is required. Timely feedback on x-ray source size allows new and improved accelerator tunes to be deployed and optimized within the limited run-time constraints of a production facility with a busy experimental schedule; in addition, time-resolved measurement capability allows the investigation of not only the time-averaged source size, but also the evolution of the source size, centroid position, and x-ray dose throughout the 70 ns beam pulse. Combined with time-resolved measurements of electron beam parameters such as emittance, energy, and current, key limiting factors can be identified, modeled, and optimized for the best possible spot size. Roll-bar techniques are a widely used method for x-ray source size measurement, and have been the method of choice at FXR for many years. A thick bar of tungsten or other dense metal with a sharp edge is inserted into the path of the x-ray beam so as to heavily attenuate the lower half of the beam, resulting in a half-light, half-dark image as seen downstream of the roll-bar; by measuring the width of the transition from light to dark across the edge of the roll-bar, the source size can be deduced. For many years, film has been the imaging medium of choice for roll-bar measurements thanks to its high resolution, linear response, and excellent contrast ratio. Film measurements, however, are fairly cumbersome and require considerable setup and analysis time; moreover, with the continuing trend towards all-electronic measurement systems, film is becoming increasingly difficult and expensive to procure. Here, we shall

  6. Chloroplast genes are expressed during intracellular symbiotic association of Vaucheria litorea plastids with the sea slug Elysia chlorotica.

    Science.gov (United States)

    Mujer, C V; Andrews, D L; Manhart, J R; Pierce, S K; Rumpho, M E

    1996-10-29

    The marine slug Elysia chlorotica (Gould) forms an intracellular symbiosis with photosynthetically active chloroplasts from the chromophytic alga Vaucheria litorea (C. Agardh). This symbiotic association was characterized over a period of 8 months during which E. chlorotica was deprived of V. litorea but provided with light and CO2. The fine structure of the symbiotic chloroplasts remained intact in E. chlorotica even after 8 months of starvation as revealed by electron microscopy. Southern blot analysis of total DNA from E. chlorotica indicated that algal genes, i.e., rbcL, rbcS, psaB, psbA, and 16S rRNA are present in the animal. These genes are typically localized to the plastid genome in higher plants and algae except rbcS, which is nuclear-encoded in higher plants and green (chlorophyll a/b) algae. Our analysis suggests, however, that similar to the few other chromophytes (chlorophyll a/c) examined, rbcS is chloroplast encoded in V. litorea. Levels of psbA transcripts remained constant in E. chlorotica starved for 2 and 3 months and then gradually declined over the next 5 months corresponding with senescence of the animal in culture and in nature. The RNA synthesis inhibitor 6-methylpurine reduced the accumulation of psbA transcripts confirming active transcription. In contrast to psbA, levels of 16S rRNA transcripts remained constant throughout the starvation period. The levels of the photosystem II proteins, D1 and CP43, were high at 2 and 4 months of starvation and remained constant at a lower steady-state level after 6 months. In contrast, D2 protein levels, although high at 2 and 4 months, were very low at all other periods of starvation. At 8 months, de novo synthesis of several thylakoid membrane-enriched proteins, including D1, still occurred. To our knowledge, these results represent the first molecular evidence for active transcription and translation of algal chloroplast genes in an animal host and are discussed in relation to the endosymbiotic

  7. Chloroplast ultra structure, photosynthesis and enzyme activities in regenerated plants of Stevia rebaudiana (Bert.) Bertoni as influenced by copper sulphate in the medium.

    Science.gov (United States)

    Jain, Pourvi; Kachhwaha, Sumita; Kothari, S L

    2014-09-01

    Stevia rebaudiana (Bert.) Bertoni is an important medicinal plant used as noncaloric commercial sweetener. Plants regenerated with higher levels of copper sulphate in the medium exhibited enhanced activity of peroxidase and polyphenoloxidase (PPO) enzymes. Transmission electron microscopy (TEM) revealed increase in size and number of electron dense inclusions in the chloroplasts of plants regenerated at optimised level of copper sulphate (0.5 microM) in the medium. There was decrease in chlorogenic acid (CGA) content. Chl-a-fluorescence transient pattern (OJIP) showed that the photosynthesis process was more efficient at 0.5 microM CuSO4 in the medium. PMID:25241590

  8. Extension of high-order harmonic cutoff frequency by synthesizing the waveform of a laser field via the optimization of classical electron trajectory in the laser field

    International Nuclear Information System (INIS)

    We theoretically investigate high-order harmonic generation by employing strong-field approximation (SFA) and present a new approach to the extension of the high-order harmonic cutoff frequency via an exploration of the dependence of high-order harmonic generation on the waveform of laser fields. The dependence is investigated via detailed analysis of the classical trajectories of the ionized electron moving in the continuum in the velocity—position plane. The classical trajectory consists of three sections (Acceleration Away, Deceleration Away, and Acceleration Back), and their relationship with the electron recollision energy is investigated. The analysis of classical trajectories indicates that, besides the final (Acceleration Back) section, the electron recollision energy also relies on the previous two sections. We simultaneously optimize the waveform in all three sections to increase the electron recollision energy, and an extension of the cutoff frequency up to Ip + 20.26Up is presented with a theoretically synthesized waveform of the laser field

  9. A high-throughput method for detection of DNA in chloroplasts using flow cytometry

    Directory of Open Access Journals (Sweden)

    Oldenburg Delene J

    2007-03-01

    Full Text Available Abstract Background The amount of DNA in the chloroplasts of some plant species has been shown recently to decline dramatically during leaf development. A high-throughput method of DNA detection in chloroplasts is now needed in order to facilitate the further investigation of this process using large numbers of tissue samples. Results The DNA-binding fluorophores 4',6-diamidino-2-phenylindole (DAPI, SYBR Green I (SG, SYTO 42, and SYTO 45 were assessed for their utility in flow cytometric analysis of DNA in Arabidopsis chloroplasts. Fluorescence microscopy and real-time quantitative PCR (qPCR were used to validate flow cytometry data. We found neither DAPI nor SYTO 45 suitable for flow cytometric analysis of chloroplast DNA (cpDNA content, but did find changes in cpDNA content during development by flow cytometry using SG and SYTO 42. The latter dye provided more sensitive detection, and the results were similar to those from the fluorescence microscopic analysis. Differences in SYTO 42 fluorescence were found to correlate with differences in cpDNA content as determined by qPCR using three primer sets widely spaced across the chloroplast genome, suggesting that the whole genome undergoes copy number reduction during development, rather than selective reduction/degradation of subgenomic regions. Conclusion Flow cytometric analysis of chloroplasts stained with SYTO 42 is a high-throughput method suitable for determining changes in cpDNA content during development and for sorting chloroplasts on the basis of DNA content.

  10. A multiple-method approach reveals a declining amount of chloroplast DNA during development in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Oldenburg Delene J

    2009-01-01

    Full Text Available Abstract Background A decline in chloroplast DNA (cpDNA during leaf maturity has been reported previously for eight plant species, including Arabidopsis thaliana. Recent studies, however, concluded that the amount of cpDNA during leaf development in Arabidopsis remained constant. Results To evaluate alternative hypotheses for these two contradictory observations, we examined cpDNA in Arabidopsis shoot tissues at different times during development using several methods: staining leaf sections as well as individual isolated chloroplasts with 4',6-diamidino-2-phenylindole (DAPI, real-time quantitative PCR with DNA prepared from total tissue as well as from isolated chloroplasts, fluorescence microscopy of ethidium-stained DNA molecules prepared in gel from isolated plastids, and blot-hybridization of restriction-digested total tissue DNA. We observed a developmental decline of about two- to three-fold in mean DNA per chloroplast and two- to five-fold in the fraction of cellular DNA represented by chloroplast DNA. Conclusion Since the two- to five-fold reduction in cpDNA content could not be attributed to an artifact of chloroplast isolation, we conclude that DNA within Arabidopsis chloroplasts is degraded in vivo as leaves mature.

  11. The Chloroplast Outer Envelope Membrane: The Edge of Light and Excitement

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The chloroplast is surrounded by a double-membrane envelope at which proteins, ions, and numerous metabolites Including nucleotides, amino acids, fatty acids, and carbohydrates are exchanged between the two aqueous phases, the cytoplasm and the chloroplast stroma. The chloroplast envelope is also the location where the biosynthesis and accumulation of various lipids take place. By contrast to the inner membrane, which contains a number of specific transporters and acts as the permeability barrier, the chloroplast outer membrane has often been considered a passive compartment derived from the phagosomal membrane. However, the presence of galactoglycerolipids and β-barrel membrane proteins support the common origin of the outer membranes of the chloroplast envelope and extant cyanobacteria. Furthermore, recent progress in the field underlines that the chloroplast outer envelope plays important roles not only for translocation of various molecules, but also for regulation of metabolic activities and signaling processes. The chloroplast outer envelope membrane offers various interesting and challenging questions that are relevant to the understanding of organelle biogenesis, plant growth and development, and also membrane biology in general.

  12. Is Chloroplast Movement in Tobacco Plants Influenced Systemically after Local Illumination or Burning Stress?

    Institute of Scientific and Technical Information of China (English)

    Jan Naus; Monika Rolencova; Vladimira Hlavackova

    2008-01-01

    Chloroplast movement has been studied In many plants mainly in relation to the local light, mechanical or stress effects. Here we investigated possible systemic responses of chloroplast movement to local light or burning stress in tobacco plants (Nicotiana tabacum cv. Samsun). Chloroplast movement was measured using two independent methods: one with a SPAD 502 Chlorophyll meter and another by collimated transmittance at a selected wavelength (676 nm). A sensitive pedodic movement of chloroplasts was used in high or low (2 000 or 50 μmol/m2 per s photosynthetically active radiation, respectively) cold white light with periods of 50 or 130 min. Measurements were carried out in the irradiated area, in the non-irradiated area of the same leaf or in the leaf located on the stem below the irradiated or burned one. No significant changes in systemic chloroplast movement in non-irradiated parts of the leaf and in the non-treated leaf were detected. Our data indicate that chloroplast movement in tobacco is dependent dominantly on the intensity and spectral composition of the incident light and on the local stimulation and state of the target tissue. No systemic signal was strong enough tovoke a detectable systemic response in chloroplast movement in distant untreated tissues of tobacco plants.

  13. The chloroplast genome of a symbiodinium sp. clade C3 isolate

    KAUST Repository

    Barbrook, Adrian C.

    2014-01-01

    Dinoflagellate algae of the genus Symbiodinium form important symbioses within corals and other benthic marine animals. Dinoflagellates possess an extremely reduced plastid genome relative to those examined in plants and other algae. In dinoflagellates the plastid genes are located on small plasmids, commonly referred to as \\'minicircles\\'. However, the chloroplast genomes of dinoflagellates have only been extensively characterised from a handful of species. There is also evidence of considerable variation in the chloroplast genome organisation across those species that have been examined. We therefore characterised the chloroplast genome from an environmental coral isolate, in this case containing a symbiont belonging to the Symbiodinium sp. clade C3. The gene content of the genome is well conserved with respect to previously characterised genomes. However, unlike previously characterised dinoflagellate chloroplast genomes we did not identify any \\'empty\\' minicircles. The sequences of this chloroplast genome show a high rate of evolution relative to other algal species. Particularly notable was a surprisingly high level of sequence divergence within the core polypeptides of photosystem I, the reasons for which are currently unknown. This chloroplast genome also possesses distinctive codon usage and GC content. These features suggest that chloroplast genomes in Symbiodinium are highly plastic. © 2013 Adrian C. Barbrook.

  14. The DnaJ-Like Zinc Finger Domain Protein PSA2 Affects Light Acclimation and Chloroplast Development in Arabidopsis thaliana.

    Science.gov (United States)

    Wang, Yan-Wen; Chen, Si-Ming; Wang, Wei-Jie; Huang, Xing-Qi; Zhou, Chang-Fang; Zhuang, Zhong; Lu, Shan

    2016-01-01

    The biosynthesis of chlorophylls and carotenoids and the assembly of thylakoid membranes are critical for the photoautotrophic growth of plants. Different factors are involved in these two processes. In recent years, members of the DnaJ-like zinc finger domain proteins have been found to take part in the biogenesis and/or the maintenance of plastids. One member of this family of proteins, PSA2, was recently found to localize to the thylakoid lumen and regulate the accumulation of photosystem I. In this study, we report that the silencing of PSA2 in Arabidopsis thaliana resulted in variegated leaves and retarded growth. Although both chlorophylls and total carotenoids decreased in the psa2 mutant, violaxanthin, and zeaxanthin accumulated in the mutant seedlings grown under growth condition. Lower levels of non-photochemical quenching and electron transport rate were also found in the psa2 mutant seedlings under growth condition compared with those of the wild-type plants, indicating an impaired capability to acclimate to normal light irradiance when PSA2 was silenced. Moreover, we also observed an abnormal assembly of grana thylakoids and poorly developed stroma thylakoids in psa2 chloroplasts. Taken together, our results demonstrate that PSA2 is a member of the DnaJ-like zinc finger domain protein family that affects light acclimation and chloroplast development. PMID:27047527

  15. Calredoxin represents a novel type of calcium-dependent sensor-responder connected to redox regulation in the chloroplast.

    Science.gov (United States)

    Hochmal, Ana Karina; Zinzius, Karen; Charoenwattanasatien, Ratana; Gäbelein, Philipp; Mutoh, Risa; Tanaka, Hideaki; Schulze, Stefan; Liu, Gai; Scholz, Martin; Nordhues, André; Offenborn, Jan Niklas; Petroutsos, Dimitris; Finazzi, Giovanni; Fufezan, Christian; Huang, Kaiyao; Kurisu, Genji; Hippler, Michael

    2016-01-01

    Calcium (Ca(2+)) and redox signalling play important roles in acclimation processes from archaea to eukaryotic organisms. Herein we characterized a unique protein from Chlamydomonas reinhardtii that has the competence to integrate Ca(2+)- and redox-related signalling. This protein, designated as calredoxin (CRX), combines four Ca(2+)-binding EF-hands and a thioredoxin (TRX) domain. A crystal structure of CRX, at 1.6 Å resolution, revealed an unusual calmodulin-fold of the Ca(2+)-binding EF-hands, which is functionally linked via an inter-domain communication path with the enzymatically active TRX domain. CRX is chloroplast-localized and interacted with a chloroplast 2-Cys peroxiredoxin (PRX1). Ca(2+)-binding to CRX is critical for its TRX activity and for efficient binding and reduction of PRX1. Thereby, CRX represents a new class of Ca(2+)-dependent 'sensor-responder' proteins. Genetically engineered Chlamydomonas strains with strongly diminished amounts of CRX revealed altered photosynthetic electron transfer and were affected in oxidative stress response underpinning a function of CRX in stress acclimation. PMID:27297041

  16. Calredoxin represents a novel type of calcium-dependent sensor-responder connected to redox regulation in the chloroplast

    Science.gov (United States)

    Hochmal, Ana Karina; Zinzius, Karen; Charoenwattanasatien, Ratana; Gäbelein, Philipp; Mutoh, Risa; Tanaka, Hideaki; Schulze, Stefan; Liu, Gai; Scholz, Martin; Nordhues, André; Offenborn, Jan Niklas; Petroutsos, Dimitris; Finazzi, Giovanni; Fufezan, Christian; Huang, Kaiyao; Kurisu, Genji; Hippler, Michael

    2016-01-01

    Calcium (Ca2+) and redox signalling play important roles in acclimation processes from archaea to eukaryotic organisms. Herein we characterized a unique protein from Chlamydomonas reinhardtii that has the competence to integrate Ca2+- and redox-related signalling. This protein, designated as calredoxin (CRX), combines four Ca2+-binding EF-hands and a thioredoxin (TRX) domain. A crystal structure of CRX, at 1.6 Å resolution, revealed an unusual calmodulin-fold of the Ca2+-binding EF-hands, which is functionally linked via an inter-domain communication path with the enzymatically active TRX domain. CRX is chloroplast-localized and interacted with a chloroplast 2-Cys peroxiredoxin (PRX1). Ca2+-binding to CRX is critical for its TRX activity and for efficient binding and reduction of PRX1. Thereby, CRX represents a new class of Ca2+-dependent ‘sensor-responder' proteins. Genetically engineered Chlamydomonas strains with strongly diminished amounts of CRX revealed altered photosynthetic electron transfer and were affected in oxidative stress response underpinning a function of CRX in stress acclimation. PMID:27297041

  17. Free radical generation and antioxidant content in chloroplasts from soybean leaves expsoed to ultraviolet-B

    Energy Technology Data Exchange (ETDEWEB)

    Galatro, A.; Simontacchi, M.; Puntarulo, S. [Univ. of Buenos Aires, School of Pharmacy and Biochemistry, Physical Chemistry, Buenos Aires (Argentina)

    2001-07-01

    The aim of this work was to study the effect of ultraviolet-B (UV-B) exposure on oxidative status in chloroplasts isolated from soybean (Glycine max cv. Hood). Chloroplasts were isolated from soybean leaves excised from either control seedlings or those exposed to 30 and 60 kJ m{sup -2} day{sup -1} of UV-B radiation for 4 days. Chloroplastic oxidative conditions were assessed as carbon-centered radical, carbonyl groups and ascorbyl radical content. Treatment with UV-B increased the carbon-centered radical-dependent EPR signal significantly by 55 and 100% in chloroplasts from leaves exposed to 30 and 60 kJ m{sup -2} day{sup -1} UV-B, respectively, compared to radical content in chloroplasts from control leaves. The content of carbonyl groups increased by 37 and 62% in chloroplasts isolated from soybean leaves irradiated for 4 days with 30 and 60 kJ m{sup -2} day{sup -1} UV-B, respectively. The content of soluble metabolites in isolated chloroplasts should not be taken as absolute in vivo values; however, these data are valuable for comparative studies. UV-B exposure did not significantly affect ascorbyl radical content compared to controls. The content of ascorbic acid and thiols in chloroplasts isolated from leaves exposed to 60 kJ m{sup -2} day{sup -1} UV-B was increased by 117 and 20.8%, respectively, compared to controls. Neither the content of total carotene nor that of {beta}-carotene or {alpha}-tocopherol was affected by the irradiation. The results: presented here suggest that the increased content of lipid radicals and oxidized proteins in the chloroplasts isolated from leaves exposed to UV-B could be ascribed to both the lack of antioxidant response in the lipid soluble fraction and the modest increase in the soluble antioxidant content. (au)

  18. Transcriptome analysis of ectopic chloroplast development in green curd cauliflower (Brassica oleracea L. var. botrytis

    Directory of Open Access Journals (Sweden)

    Zhou Xiangjun

    2011-11-01

    Full Text Available Abstract Background Chloroplasts are the green plastids where photosynthesis takes place. The biogenesis of chloroplasts requires the coordinate expression of both nuclear and chloroplast genes and is regulated by developmental and environmental signals. Despite extensive studies of this process, the genetic basis and the regulatory control of chloroplast biogenesis and development remain to be elucidated. Results Green cauliflower mutant causes ectopic development of chloroplasts in the curd tissue of the plant, turning the otherwise white curd green. To investigate the transcriptional control of chloroplast development, we compared gene expression between green and white curds using the RNA-seq approach. Deep sequencing produced over 15 million reads with lengths of 86 base pairs from each cDNA library. A total of 7,155 genes were found to exhibit at least 3-fold changes in expression between green and white curds. These included light-regulated genes, genes encoding chloroplast constituents, and genes involved in chlorophyll biosynthesis. Moreover, we discovered that the cauliflower ELONGATED HYPOCOTYL5 (BoHY5 was expressed higher in green curds than white curds and that 2616 HY5-targeted genes, including 1600 up-regulated genes and 1016 down-regulated genes, were differently expressed in green in comparison to white curd tissue. All these 1600 up-regulated genes were HY5-targeted genes in the light. Conclusions The genome-wide profiling of gene expression by RNA-seq in green curds led to the identification of large numbers of genes associated with chloroplast development, and suggested the role of regulatory genes in the high hierarchy of light signaling pathways in mediating the ectopic chloroplast development in the green curd cauliflower mutant.

  19. Integrated approach to planning and optimization processes maintenance and repair of vehicles using telemetry systems for remote electronic diagnostic

    OpenAIRE

    Аулін, Віктор Васильович; Панарін, Д. Є.

    2014-01-01

    In article the modern condition of questions, on systems of remote electronic diagnostics is analysed, the interrelation of remote electronic diagnostics with process of maintenance service of cars is considered.Opportunities of remote electronic diagnostics of automobile systems, and advantages of this type of diagnostics during maintenance service and operating repair are investigated. Having considered opportunities of electronic control systems in units and units of the car while in servi...

  20. Comparison of optimal performance at 300 keV of three direct electron detectors for use in low dose electron microscopy

    CERN Document Server

    McMullan, G; Clare, D; Henderson, R

    2014-01-01

    Low dose electron imaging applications such as electron cyro-microscopy are now benefitting from the improved performance and flexibility of recently introduced electron imaging detectors in which electrons are directly incident on backthinned CMOS sensors. There are currently three commercially available detectors of this type: the Direct Electron DE 20, the FEI Falcon II and the Gatan K2 Summit. These have different characteristics and so it is important to compare their imaging properties carefully with a view to optimising how each is used. Results at 300 keV for both the modulation transfer function (MTF) and detective quantum efficiency (DQE) are presented. Of these, the DQE is the most important in the study of radiation sensitive samples where detector performance is crucial. We find that all three detectors have a better DQE than film. The K2 Summit has the best DQE at low spatial frequencies but with increasing spatial frequency its DQE falls below that of the Falcon II.

  1. Analysis of DoD inkjet printhead performance for printable electronics fabrication using dynamic lumped element modeling and swarm intelligence based optimal prediction

    Institute of Scientific and Technical Information of China (English)

    何茂伟; 孙丽玲; 胡琨元; 朱云龙; 陈瀚宁

    2015-01-01

    The major challenge in printable electronics fabrication is to effectively and accurately control a drop-on-demand (DoD) inkjet printhead for high printing quality. In this work, an optimal prediction model, constructed with the lumped element modeling (LEM) and the artificial bee colony (ABC) algorithm, was proposed to efficiently predict the combination of waveform parameters for obtaining the desired droplet properties. For acquiring higher simulation accuracy, a modified dynamic lumped element model (DLEM) was proposed with time-varying equivalent circuits, which can characterize the nonlinear behaviors of piezoelectric printhead. The proposed method was then applied to investigate the influences of various waveform parameters on droplet volume and velocity of nano-silver ink, and to predict the printing quality using nano-silver ink. Experimental results show that, compared with two-dimension manual search, the proposed optimal prediction model perform efficiently and accurately in searching the appropriate combination of waveform parameters for printable electronics fabrication.

  2. Structure and transcription of the spinach chloroplast rDNA leader region.

    OpenAIRE

    Briat, J F; Dron, M; Loiseaux, S; Mache, R

    1982-01-01

    A cloned fragment of spinach chloroplast DNA carrying 140 bp of the 16S rRNA gene and 691 bp upstream this gene has been analysed by DNA sequencing, by in vitro transcription, by S1 mapping with chloroplast RNAs and purified 16S rRNA from 30S ribosomal subunits. A tRNAVal gene has been located between the position 394 and 465. Crude chloroplast RNA polymerase has been purified by heparin sepharose chromatography of a 80 000 g supernatant from pure lysed spinach plastids and used to transcribe...

  3. The complete chloroplast genome sequence of Anoectochilus emeiensis.

    Science.gov (United States)

    Zhu, Shuying; Niu, Zhitao; Yan, Wenjin; Xue, Qingyun; Ding, Xiaoyu

    2016-09-01

    The complete chloroplast (cp) genome sequence of Anoectochilus emeiensis, an extremely endangered medical plant with important economic value, was determined and characterized. The genome size was 152 650 bp, containing a pair of inverted repeats (IRs) (26 319 bp) which were separated by a large single copy (LSC) (82 670 bp) and a small single copy (SSC) (17 342 bp). The cpDNA of A. emeiensis contained 113 unique genes, including 79 protein coding genes, 30 tRNA genes and 4 rRNA genes. Among them, 18 genes contained one or two introns. The overall AT content of the genome was 63.1%. PMID:26403535

  4. The complete chloroplast genome sequence of Euonymus japonicus (Celastraceae).

    Science.gov (United States)

    Choi, Kyoung Su; Park, SeonJoo

    2016-09-01

    The complete chloroplast (cp) genome sequence of the Euonymus japonicus, the first sequenced of the genus Euonymus, was reported in this study. The total length was 157 637 bp, containing a pair of 26 678 bp inverted repeat region (IR), which were separated by small single copy (SSC) region and large single copy (LSC) region of 18 340 bp and 85 941 bp, respectively. This genome contains 107 unique genes, including 74 coding genes, four rRNA genes, and 29 tRNA genes. Seventeen genes contain intron of E. japonicus, of which three genes (clpP, ycf3, and rps12) include two introns. The maximum likelihood (ML) phylogenetic analysis revealed that E. japonicus was closely related to Manihot and Populus. PMID:26407184

  5. The complete chloroplast genomes of Cannabis sativa and Humulus lupulus.

    Science.gov (United States)

    Vergara, Daniela; White, Kristin H; Keepers, Kyle G; Kane, Nolan C

    2016-09-01

    Cannabis and Humulus are sister genera comprising the entirety of the Cannabaceae sensu stricto, including C. sativa L. (marijuana, hemp), and H. lupulus L. (hops) as two economically important crops. These two plants have been used by humans for many purposes including as a fiber, food, medicine, or inebriant in the case of C. sativa, and as a flavoring component in beer brewing in the case of H. lupulus. In this study, we report the complete chloroplast genomes for two distinct hemp varieties of C. sativa, Italian "Carmagnola" and Russian "Dagestani", and one Czech variety of H. lupulus "Saazer". Both C. sativa genomes are 153 871 bp in length, while the H. lupulus genome is 153 751 bp. The genomes from the two C. sativa varieties differ in 16 single nucleotide polymorphisms (SNPs), while the H. lupulus genome differs in 1722 SNPs from both C. sativa cultivars. PMID:26329384

  6. The whole chloroplast genomes of two Eutrema species (Brassicaceae).

    Science.gov (United States)

    Hao, Guoqian; Bi, Hao; Li, Yuanshuo; He, Qi; Ma, Yazhen; Guo, Xinyi; Ma, Tao

    2016-09-01

    In this study, we determined the complete chloroplast genomes from two crucifer species of the Eutrema genus. The sizes of the two cp genomes were 153 948 bp (E. yunnanense) and 153 876 bp (E. heterophyllum). Both genomes have the typical quadripartite structure consisting of a large single copy region, a small single copy region and two inverted repeats. Gene contents and their relative positions of the 132 individual genes (87 protein-coding genes, eight rRNA, and 37 tRNA genes) of either genome were identical to each other. Phylogenetic analysis supports the idea that the currently recognized Eutrema genus is monophyletic and that E. salsugineum and Schrenkiella parvula evolved salt tolerance independently. PMID:26329763

  7. [Study of Chloroplast DNA Polymorphism in the Sunflower (Helianthus L.)].

    Science.gov (United States)

    Markina, N V; Usatov, A V; Logacheva, M D; Azarin, K V; Gorbachenko, C F; Kornienko, I V; Gavrilova, V A; Tihobaeva, V E

    2015-08-01

    The polymorphism of microsatellite loci of chloroplast genome in six Helianthus species and 46 lines of cultivated sunflower H. annuus (17 CMS lines and 29 Rf-lines) were studied. The differences between species are confined to four SSR loci. Within cultivated forms of the sunflower H. annuus, the polymorphism is absent. A comparative analysis was performed on sequences of the cpDNA inbred line 3629, line 398941 of the wild sunflower, and the American line HA383 H. annuus. As a result, 52 polymorphic loci represented by 27 SSR and 25 SNP were found; they can be used for genotyping of H. annuus samples, including cultural varieties: twelve polymorphic positions, of which eight are SSR and four are SNP. PMID:26601486

  8. Arabidopsis thaliana DNA gyrase is targeted to chloroplasts and mitochondria

    Science.gov (United States)

    Wall, Melisa K.; Mitchenall, Lesley A.; Maxwell, Anthony

    2004-01-01

    DNA gyrase is the bacterial DNA topoisomerase (topo) that supercoils DNA by using the free energy of ATP hydrolysis. The enzyme, an A2B2 tetramer encoded by the gyrA and gyrB genes, catalyses topological changes in DNA during replication and transcription, and is the only topo that is able to introduce negative supercoils. Gyrase is essential in bacteria and apparently absent from eukaryotes and is, consequently, an important target for antibacterial agents (e.g., quinolones and coumarins). We have identified four putative gyrase genes in the model plant Arabidopsis thaliana; one gyrA and three gyrB homologues. DNA gyrase protein A (GyrA) has a dual translational initiation site targeting the mature protein to both chloroplasts and mitochondria, and there are individual targeting sequences for two of the DNA gyrase protein B (GyrB) homologues. N-terminal fusions of the organellar targeting sequences to GFPs support the hypothesis that one enzyme is targeted to the chloroplast and another to the mitochondrion, which correlates with supercoiling activity in isolated organelles. Treatment of seedlings and cultured cells with gyrase-specific drugs leads to growth inhibition. Knockout of A. thaliana gyrA is embryo-lethal whereas knockouts in the gyrB genes lead to seedling-lethal phenotypes or severely stunted growth and development. The A. thaliana genes have been cloned in Escherichia coli and found to complement gyrase temperature-sensitive strains. This report confirms the existence of DNA gyrase in eukaryotes and has important implications for drug targeting, organelle replication, and the evolution of topos in plants. PMID:15136745

  9. Comparative analyses of chloroplast genome data representing nine green algae in Sphaeropleales (Chlorophyceae, Chlorophyta).

    Science.gov (United States)

    Fučíková, Karolina; Lewis, Louise A; Lewis, Paul O

    2016-06-01

    The chloroplast genomes of green algae are highly variable in their architecture. In this article we summarize gene content across newly obtained and published chloroplast genomes in Chlorophyceae, including new data from nine of species in Sphaeropleales (Chlorophyceae, Chlorophyta). We present genome architecture information, including genome synteny analysis across two groups of species. Also, we provide a phylogenetic tree obtained from analysis of gene order data for species in Chlorophyceae with fully sequenced chloroplast genomes. Further analyses and interpretation of the data can be found in "Chloroplast phylogenomic data from the green algal order Sphaeropleales (Chlorophyceae, Chlorophyta) reveal complex patterns of sequence evolution" (Fučíková et al., In review) [1]. PMID:27054159

  10. Programmed chloroplast destruction during leaf senescence involves 13-lipoxygenase (13-LOX).

    Science.gov (United States)

    Springer, Armin; Kang, ChulHee; Rustgi, Sachin; von Wettstein, Diter; Reinbothe, Christiane; Pollmann, Stephan; Reinbothe, Steffen

    2016-03-22

    Leaf senescence is the terminal stage in the development of perennial plants. Massive physiological changes occur that lead to the shut down of photosynthesis and a cessation of growth. Leaf senescence involves the selective destruction of the chloroplast as the site of photosynthesis. Here, we show that 13-lipoxygenase (13-LOX) accomplishes a key role in the destruction of chloroplasts in senescing plants and propose a critical role of its NH2-terminal chloroplast transit peptide. The 13-LOX enzyme identified here accumulated in the plastid envelope and catalyzed the dioxygenation of unsaturated membrane fatty acids, leading to a selective destruction of the chloroplast and the release of stromal constituents. Because 13-LOX pathway products comprise compounds involved in insect deterrence and pathogen defense (volatile aldehydes and oxylipins), a mechanism of unmolested nitrogen and carbon relocation is suggested that occurs from leaves to seeds and roots during fall. PMID:26969728

  11. Running a little late: chloroplast Fe status and the circadian clock

    OpenAIRE

    Wilson, Grandon T; Erin L Connolly

    2013-01-01

    Iron homeostasis is essential for plant growth and survival. Two papers now report that chloroplast Iron levels also regulate the period of the circadian clock, which might confer fitness advantage by linking iron status to daily changes in environmental conditions.

  12. Development of the First Chloroplast Microsatellite Loci in Ginkgo biloba (Ginkgoaceae

    Directory of Open Access Journals (Sweden)

    Chun-Xiang Xie

    2013-07-01

    Full Text Available Premise of the study: To investigate population genetics, phylogeography, and cultivar origin of Ginkgo biloba, chloroplast microsatellite primers were developed. Methods and Results: Twenty-one chloroplast microsatellite markers were identified referring to the two published chloroplast genomes of G. biloba. Polymorphisms were assessed on four natural populations from the two refugia in China. Eight loci were detected to be polymorphic in these populations. The number of alleles per locus ranged from three to seven, and the unbiased haploid diversity per locus varied from 0.441 to 0.807. Conclusions: For the first time, we developed 21 chloroplast microsatellite markers for G. biloba, including 13 monomorphic and eight polymorphic ones within the assessed natural populations. These markers should provide a powerful tool for the study of genetic variation of both natural and cultivated populations of G. biloba, as well as cultivars.

  13. The complete chloroplast genome sequence of an important medicinal plant Cynanchum wilfordii (Maxim.) Hemsl. (Apocynaceae).

    Science.gov (United States)

    Park, Hyun-Seung; Kim, Kyu-Yeob; Kim, Kyunghee; Lee, Sang-Choon; Lee, Junki; Seong, Rack Seon; Shim, Young Hun; Sung, Sang Hyun; Yang, Tae-Jin

    2016-09-01

    Cynanchum wilfordii (Maxim.) Hemsl. is a traditional medicinal herb belonging to the Asclepiadoideae subfamily, whose dried roots have been used as traditional medicine in Asia. The complete chloroplast genome of C. wilfordii was generated by de novo assembly using the small amount of whole genome sequencing data. The chloroplast genome of C. wilfordii was 161 241 bp long, composed of large single copy region (91 995 bp), small single copy region (19 930 bp) and a pair of inverted repeat regions (24 658 bp). The overall GC contents of the chloroplast genome was 37.8%. A total of 114 genes were annotated, which included 80 protein-coding genes, 30 tRNA genes and 4 rRNA genes. Phylogenetic analysis with the reported chloroplast genomes revealed that C. wilfordii is most closely related to Asclepias nivea (Caribbean milkweed) and Asclepias syriaca (common milkweed) within the Asclepiadoideae subfamily. PMID:26358391

  14. The complete chloroplast genome of Eleutherococcus gracilistylus (W.W.Sm.) S.Y.Hu (Araliaceae).

    Science.gov (United States)

    Kim, Kyunghee; Lee, Junki; Lee, Sang-Choon; Kim, Nam-Hoon; Jang, Woojong; Kim, Soonok; Sung, Sangmin; Lee, Jungho; Yang, Tae-Jin

    2016-09-01

    Eleutherococcus gracilistylus is a plant species that is close to E. senticosus, a famous medicinal plant called Siberian ginseng. The complete chloroplast genome sequence of the E. gracilistylus was determined by de novo assembly using whole genome next generation sequences. The chloroplast genome of E. gracilistylus was 156 770 bp long and showed distinct four partite structures such as a large single copy region of 86 729 bp, a small single copy region of 18 175 bp, and a pair of inverted repeat regions of 25 933 bp. The overall GC contents of the genome sequence were 36.8%. The chloroplast genome of E. gracilistylus contains 79 protein-coding sequences, 30 tRNA genes, and four rRNA genes. The phylogenetic analysis with the reported chloroplast genomes confirmed close taxonomical relationship of E. gracilistylus with E. senticosus. PMID:26358682

  15. In Vivo Quantification of Peroxisome Tethering to Chloroplasts in Tobacco Epidermal Cells Using Optical Tweezers.

    Science.gov (United States)

    Gao, Hongbo; Metz, Jeremy; Teanby, Nick A; Ward, Andy D; Botchway, Stanley W; Coles, Benjamin; Pollard, Mark R; Sparkes, Imogen

    2016-01-01

    Peroxisomes are highly motile organelles that display a range of motions within a short time frame. In static snapshots, they can be juxtaposed to chloroplasts, which has led to the hypothesis that they are physically interacting. Here, using optical tweezers, we tested the dynamic physical interaction in vivo. Using near-infrared optical tweezers combined with TIRF microscopy, we were able to trap peroxisomes and approximate the forces involved in chloroplast association in vivo in tobacco (Nicotiana tabacum) and observed weaker tethering to additional unknown structures within the cell. We show that chloroplasts and peroxisomes are physically tethered through peroxules, a poorly described structure in plant cells. We suggest that peroxules have a novel role in maintaining peroxisome-organelle interactions in the dynamic environment. This could be important for fatty acid mobilization and photorespiration through the interaction with oil bodies and chloroplasts, highlighting a fundamentally important role for organelle interactions for essential biochemistry and physiological processes. PMID:26518344

  16. Regulation of chloroplast number and DNA synthesis in higher plants. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Mullet, J.E.

    1995-11-10

    The long term objective of this research is to understand the process of chloroplast development and its coordination with leaf development in higher plants. This is important because the photosynthetic capacity of plants is directly related to leaf and chloroplast development. This research focuses on obtaining a detailing description of leaf development and the early steps in chloroplast development including activation of plastid DNA synthesis, changes in plastid DNA copy number, activation of chloroplast transcription and increases in plastid number per cell. The grant will also begin analysis of specific biochemical mechanisms by isolation of the plastid DNA polymerase, and identification of genetic mutants which are altered in their accumulation of plastid DNA and plastid number per cell.

  17. Regulation of chloroplast number and DNA synthesis in higher plants. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Mullet, J.E.

    1995-11-10

    The long term objective of this research is to understand the process of chloroplast development and its coordination with leaf development in higher plants. This is important because the photosynthetic capacity of plants is directly related to leaf and chloroplast development. This research focuses on obtaining a detailed description of leaf development and the early steps in chloroplast development including activation of plastid DNA synthesis, changes in plastid DNA copy number, activation of chloroplast transcription and increases in plastid number per cell. The grant will also begin analysis of specific biochemical mechanisms by isolation of the plastid DNA polymerase, and identification of genetic mutants which are altered in their accumulation of plastid DNA and plastid number per cell.

  18. Arabidopsis VARIEGATED 3 encodes a chloroplast-targeted, zinc-finger protein required for chloroplast and palisade cell development

    DEFF Research Database (Denmark)

    Næsted, Henrik; Holm, Agnethe; Jenkins, Tom; Nielsen, Henrik Bjørn; Harris, Cassandra A.; Beale, Michael H.; Andersen, Mathias; Mant, Alexandra; Scheller, Henrik Vibe; Camara, Bilal; Mattsson, Ole; Mundy, John

    2004-01-01

    The stable, recessive Arabidopsis variegated 3 (var3) mutant exhibits a variegated phenotype due to somatic areas lacking or containing developmentally retarded chloroplasts and greatly reduced numbers of palisade cells. The VAR3 gene, isolated by transposon tagging, encodes the 85.9 kDa VAR3 pro...... pigment profiles are qualitatively similar in wild type and var3, although var3 accumulates lower levels of chlorophylls and carotenoids. These results indicate that VAR3 is a part of a protein complex required for normal chloroplast and palisade cell development....... protein containing novel repeats and zinc fingers described as protein interaction domains. VAR3 interacts specifically in yeast and in vitro with NCED4, a putative polyene chain or carotenoid dioxygenase, and both VAR3 and NCED4 accumulate in the chloroplast stroma. Metabolic profiling demonstrates that...

  19. Comparison of optimal performance at 300 keV of three direct electron detectors for use in low dose electron microscopy

    Science.gov (United States)

    McMullan, G.; Faruqi, A.R.; Clare, D.; Henderson, R.

    2014-01-01

    Low dose electron imaging applications such as electron cryo-microscopy are now benefitting from the improved performance and flexibility of recently introduced electron imaging detectors in which electrons are directly incident on backthinned CMOS sensors. There are currently three commercially available detectors of this type: the Direct Electron DE-20, the FEI Falcon II and the Gatan K2 Summit. These have different characteristics and so it is important to compare their imaging properties carefully with a view to optimise how each is used. Results at 300 keV for both the modulation transfer function (MTF) and the detective quantum efficiency (DQE) are presented. Of these, the DQE is the most important in the study of radiation sensitive samples where detector performance is crucial. We find that all three detectors have a better DQE than film. The K2 Summit has the best DQE at low spatial frequencies but with increasing spatial frequency its DQE falls below that of the Falcon II. PMID:25194828

  20. PAPP5 is involved in the tetrapyrrole mediated plastid signalling during chloroplast development

    OpenAIRE

    Juan de Dios Barajas-López; Dmitry Kremnev; Jehad Shaikhali; Aurora Piñas-Fernández; Asa Strand

    2013-01-01

    The initiation of chloroplast development in the light is dependent on nuclear encoded components. The nuclear genes encoding key components in the photosynthetic machinery are regulated by signals originating in the plastids. These plastid signals play an essential role in the regulation of photosynthesis associated nuclear genes (PhANGs) when proplastids develop into chloroplasts. One of the plastid signals is linked to the tetrapyrrole biosynthesis and accumulation of the intermediates the...

  1. Milestones in chloroplast genetic engineering: an environmentally friendly era in biotechnology

    OpenAIRE

    Daniell, Henry; Khan, Muhammad S.; Allison, Lori

    2002-01-01

    Chloroplast genomes defied the laws of Mendelian inheritance at the dawn of plant genetics, and continue to defy the mainstream approach to biotechnology, leading the field in an environmentally friendly direction. Recent success in engineering the chloroplast genome for resistance to herbicides, insects, disease and drought, and for production of biopharmaceuticals, has opened the door to a new era in biotechnology. The successful engineering of tomato chromoplasts for high-level transgene e...

  2. Chloroplast-Derived Vaccine Antigens and Biopharmaceuticals: Expression, Folding, Assembly and Functionality

    OpenAIRE

    Chebolu, S.; Daniell, H

    2009-01-01

    Chloroplast genetic engineering offers several advantages, including high levels of transgene expression, transgene containment via maternal inheritance, and multi-gene expression in a single transformation event. Oral delivery is facilitated by hyperexpression of vaccine antigens against cholera, tetanus, anthrax, plague, or canine parvovirus (4%–31% of total soluble protein, TSP) in transgenic chloroplasts (leaves) or non-green plastids (carrots, tomato) as well as the availability of antib...

  3. Comparative analyses of chloroplast genome data representing nine green algae in Sphaeropleales (Chlorophyceae, Chlorophyta)

    OpenAIRE

    Fučíková, Karolina; Lewis, Louise A.; Lewis, Paul O.

    2016-01-01

    The chloroplast genomes of green algae are highly variable in their architecture. In this article we summarize gene content across newly obtained and published chloroplast genomes in Chlorophyceae, including new data from nine of species in Sphaeropleales (Chlorophyceae, Chlorophyta). We present genome architecture information, including genome synteny analysis across two groups of species. Also, we provide a phylogenetic tree obtained from analysis of gene order data for species in Chlorophy...

  4. Large-scale Arabidopsis phosphoproteome profiling reveals novel chloroplast kinase substrates and phosphorylation networks

    OpenAIRE

    Reiland, S; Messerli, G.; Baerenfaller, K.; Gerrits, B.; Endler, A; Grossmann, J.; Gruissem, W; Baginsky, S

    2009-01-01

    We have characterized the phosphoproteome of Arabidopsis (Arabidopsis thaliana) seedlings using high-accuracy mass spectrometry and report the identification of 1,429 phosphoproteins and 3,029 unique phosphopeptides. Among these, 174 proteins were chloroplast phosphoproteins. Motif-X (motif extractor) analysis of the phosphorylation sites in chloroplast proteins identified four significantly enriched kinase motifs, which include casein kinase II (CKII) and proline-directed kinase motifs, as w...

  5. Increased resistance to oxidative stress in transgenic plants that overexpress chloroplastic Cu/Zn superoxide dismutase.

    OpenAIRE

    Gupta, A. S.; Heinen, J L; Holaday, A S; Burke, J. J.; Allen, R D

    1993-01-01

    Transgenic tobacco plants that express a chimeric gene that encodes chloroplast-localized Cu/Zn superoxide dismutase (SOD) from pea have been developed. To investigate whether increased expression of chloroplast-targeted SOD could alter the resistance of photosynthesis to environmental stress, these plants were subjected to chilling temperatures and moderate (500 mumol of quanta per m2 per s) or high (1500 mumol of quanta per m2 per s) light intensity. During exposure to moderate stress, tran...

  6. Chloroplast envelope membranes: a dynamic interface between plastids and the cytosol

    OpenAIRE

    Block, Maryse A.; Douce, Roland; Joyard, Jacques; Rolland, Norbert

    2007-01-01

    Chloroplasts are bounded by a pair of outer membranes, the envelope, that is the only permanent membrane structure of the different types of plastids. Chloroplasts have had a long and complex evolutionary past and integration of the envelope membranes in cellular functions is the result of this evolution. Plastid envelope membranes contain a wide diversity of lipids and terpenoid compounds serving numerous biochemical functions and the flexibility of their biosynthetic pathways allow plants t...

  7. Stress induces the assembly of RNA granules in the chloroplast of Chlamydomonas reinhardtii

    OpenAIRE

    Uniacke, James; Zerges, William

    2008-01-01

    Eukaryotic cells under stress repress translation and localize these messenger RNAs (mRNAs) to cytoplasmic RNA granules. We show that specific stress stimuli induce the assembly of RNA granules in an organelle with bacterial ancestry, the chloroplast of Chlamydomonas reinhardtii. These chloroplast stress granules (cpSGs) form during oxidative stress and disassemble during recovery from stress. Like mammalian stress granules, cpSGs contain poly(A)-binding protein and the small, but not the lar...

  8. An Improved Protocol for Intact Chloroplasts and cpDNA Isolation in Conifers

    OpenAIRE

    Vieira, Leila do Nascimento; Faoro, Helisson; Fraga, Hugo Pacheco de Freitas; Rogalski, Marcelo; de Souza, Emanuel Maltempi; de Oliveira Pedrosa, Fábio; Nodari, Rubens Onofre; Guerra, Miguel Pedro

    2014-01-01

    Background Performing chloroplast DNA (cpDNA) isolation is considered a major challenge among different plant groups, especially conifers. Isolating chloroplasts in conifers by such conventional methods as sucrose gradient and high salt has not been successful. So far, plastid genome sequencing protocols for conifer species have been based mainly on long-range PCR, which is known to be time-consuming and difficult to implement. Methodology/Principal Findings We developed a protocol for cpDNA ...

  9. The Complete Chloroplast Genome of Banana (Musa acuminata, Zingiberales): Insight into Plastid Monocotyledon Evolution

    OpenAIRE

    Guillaume Martin; Franc-Christophe Baurens; Céline Cardi; Jean-Marc Aury; Angélique D'Hont

    2013-01-01

    BACKGROUND: Banana (genus Musa) is a crop of major economic importance worldwide. It is a monocotyledonous member of the Zingiberales, a sister group of the widely studied Poales. Most cultivated bananas are natural Musa inter-(sub-)specific triploid hybrids. A Musa acuminata reference nuclear genome sequence was recently produced based on sequencing of genomic DNA enriched in nucleus. METHODOLOGY/PRINCIPAL FINDINGS: The Musa acuminata chloroplast genome was assembled with chloroplast reads e...

  10. Sorting signals, N-terminal modifications and abundance of the chloroplast proteome.

    Directory of Open Access Journals (Sweden)

    Boris Zybailov

    Full Text Available Characterization of the chloroplast proteome is needed to understand the essential contribution of the chloroplast to plant growth and development. Here we present a large scale analysis by nanoLC-Q-TOF and nanoLC-LTQ-Orbitrap mass spectrometry (MS of ten independent chloroplast preparations from Arabidopsis thaliana which unambiguously identified 1325 proteins. Novel proteins include various kinases and putative nucleotide binding proteins. Based on repeated and independent MS based protein identifications requiring multiple matched peptide sequences, as well as literature, 916 nuclear-encoded proteins were assigned with high confidence to the plastid, of which 86% had a predicted chloroplast transit peptide (cTP. The protein abundance of soluble stromal proteins was calculated from normalized spectral counts from LTQ-Obitrap analysis and was found to cover four orders of magnitude. Comparison to gel-based quantification demonstrates that 'spectral counting' can provide large scale protein quantification for Arabidopsis. This quantitative information was used to determine possible biases for protein targeting prediction by TargetP and also to understand the significance of protein contaminants. The abundance data for 550 stromal proteins was used to understand abundance of metabolic pathways and chloroplast processes. We highlight the abundance of 48 stromal proteins involved in post-translational proteome homeostasis (including aminopeptidases, proteases, deformylases, chaperones, protein sorting components and discuss the biological implications. N-terminal modifications were identified for a subset of nuclear- and chloroplast-encoded proteins and a novel N-terminal acetylation motif was discovered. Analysis of cTPs and their cleavage sites of Arabidopsis chloroplast proteins, as well as their predicted rice homologues, identified new species-dependent features, which will facilitate improved subcellular localization prediction. No evidence

  11. Uncovering the protein lysine and arginine methylation network in Arabidopsis chloroplasts.

    Science.gov (United States)

    Alban, Claude; Tardif, Marianne; Mininno, Morgane; Brugière, Sabine; Gilgen, Annabelle; Ma, Sheng; Mazzoleni, Meryl; Gigarel, Océane; Martin-Laffon, Jacqueline; Ferro, Myriam; Ravanel, Stéphane

    2014-01-01

    Post-translational modification of proteins by the addition of methyl groups to the side chains of Lys and Arg residues is proposed to play important roles in many cellular processes. In plants, identification of non-histone methylproteins at a cellular or subcellular scale is still missing. To gain insights into the extent of this modification in chloroplasts we used a bioinformatics approach to identify protein methyltransferases targeted to plastids and set up a workflow to specifically identify Lys and Arg methylated proteins from proteomic data used to produce the Arabidopsis chloroplast proteome. With this approach we could identify 31 high-confidence Lys and Arg methylation sites from 23 chloroplastic proteins, of which only two were previously known to be methylated. These methylproteins are split between the stroma, thylakoids and envelope sub-compartments. They belong to essential metabolic processes, including photosynthesis, and to the chloroplast biogenesis and maintenance machinery (translation, protein import, division). Also, the in silico identification of nine protein methyltransferases that are known or predicted to be targeted to plastids provided a foundation to build the enzymes/substrates relationships that govern methylation in chloroplasts. Thereby, using in vitro methylation assays with chloroplast stroma as a source of methyltransferases we confirmed the methylation sites of two targets, plastid ribosomal protein L11 and the β-subunit of ATP synthase. Furthermore, a biochemical screening of recombinant chloroplastic protein Lys methyltransferases allowed us to identify the enzymes involved in the modification of these substrates. The present study provides a useful resource to build the methyltransferases/methylproteins network and to elucidate the role of protein methylation in chloroplast biology. PMID:24748391

  12. THE OCCURRENCE AND SIGNIFICANCE OF ENDOSYMBIOTIC CHLOROPLASTS IN THE DIGESTIVE GLANDS OF HERBIVOROUS OPISTHOBRANCHS(1).

    Science.gov (United States)

    Taylor, D L

    1967-12-01

    Intact algal chloroplasts have been found in the digestive glands of 5 species of Opisthobranchia belonging to the order Saccoglossa. Preliminary studies on 3 of these confirm their endosymbiotic nature. It is suggested that the occurrence of these endosymbiotic organelles may be widespread among related species of Saccoglossa. Their independent functional existence supports the view that chloroplasts possess a system of nonchromosomal inheritance. PMID:27065036

  13. Molecular and biochemical analyses of transgenic nicotiana tabacum plants metabolizing glycolate in the chloroplasts

    OpenAIRE

    Thiruveedhi, Krishnaveni

    2006-01-01

    The photorespiratory pathway in C3 plants consumes not only ATP and reducing equivalents but also results in loss of ~ 25% carbon that has been fixed during the process of photosynthesis. In the present study, an alternative biochemical pathway for the metabolism of glycolate was established in the chloroplasts of tobacco (Nicotiana tabacum) plants. The new pathway aims at increasing the refixation of CO2 inside the chloroplasts and thereby at suppressing photorespiration in C3 plants. The pa...

  14. Complete Chloroplast Genome Sequence of Omani Lime (Citrus aurantiifolia) and Comparative Analysis within the Rosids

    OpenAIRE

    Huei-Jiun Su; Hogenhout, Saskia A.; Al-Sadi, Abdullah M.; Chih-Horng Kuo

    2014-01-01

    The genus Citrus contains many economically important fruits that are grown worldwide for their high nutritional and medicinal value. Due to frequent hybridizations among species and cultivars, the exact number of natural species and the taxonomic relationships within this genus are unclear. To compare the differences between the Citrus chloroplast genomes and to develop useful genetic markers, we used a reference-assisted approach to assemble the complete chloroplast genome of Omani lime (C....

  15. Acquired phototrophy through retention of functional chloroplasts increases growth efficiency of the sea slug Elysia viridis.

    Directory of Open Access Journals (Sweden)

    Finn A Baumgartner

    Full Text Available Photosynthesis is a fundamental process sustaining heterotrophic organisms at all trophic levels. Some mixotrophs can retain functional chloroplasts from food (kleptoplasty, and it is hypothesized that carbon acquired through kleptoplasty may enhance trophic energy transfer through increased host growth efficiency. Sacoglossan sea slugs are the only known metazoans capable of kleptoplasty, but the relative fitness contributions of heterotrophy through grazing, and phototrophy via kleptoplasts, are not well understood. Fitness benefits (i.e. increased survival or growth of kleptoplasty in sacoglossans are commonly studied in ecologically unrealistic conditions under extended periods of complete darkness and/or starvation. We compared the growth efficiency of the sacoglossan Elysia viridis with access to algal diets providing kleptoplasts of differing functionality under ecologically relevant light conditions. Individuals fed Codium fragile, which provide highly functional kleptoplasts, nearly doubled their growth efficiency under high compared to low light. In contrast, individuals fed Cladophora rupestris, which provided kleptoplasts of limited functionality, showed no difference in growth efficiency between light treatments. Slugs feeding on Codium, but not on Cladophora, showed higher relative electron transport rates (rETR in high compared to low light. Furthermore, there were no differences in the consumption rates of the slugs between different light treatments, and only small differences in nutritional traits of algal diets, indicating that the increased growth efficiency of E. viridis feeding on Codium was due to retention of functional kleptoplasts. Our results show that functional kleptoplasts from Codium can provide sacoglossan sea slugs with fitness advantages through photosynthesis.

  16. Comparative proteomics of chloroplasts envelopes from bundle sheath and mesophyll chloroplasts reveals novel membrane proteins with a possible role in C4-related metabolite fluxes and development.

    Directory of Open Access Journals (Sweden)

    Kalpana eManandhar-Shrestha

    2013-03-01

    Full Text Available As the world population grows, our need for food increases drastically. Limited amounts of arable land lead to a competition between food and fuel crops, while changes in the global climate may impact future crop yields. Thus, a second green revolution will need a better understanding of the processes essential for plant growth and development. One approach toward the solution of this problem is to better understand regulatory and transport processes in C4 plants. C4 plants display an up to 10-fold higher apparent CO2 assimilation and higher yields while maintaining high water use efficiency. This requires differential regulation of mesophyll (M and bundle sheath (BS chloroplast development as well as higher metabolic fluxes of photosynthetic intermediates between cells and across chloroplast envelopes. While previous analyses of overall chloroplast membranes have yielded significant insight, our comparative proteomics approach using enriched BS and M chloroplast envelopes of Zea mays allowed us to identify 37 proteins of unknown function that have not been seen in these earlier studies. We identified 280 proteins, 84% of which are known/predicted to be present in chloroplasts (cp. 74% have a known or predicted membrane association. 21 membrane proteins were 2-15 times more abundant in BS cells, while 36 proteins were more abundant in M cp envelopes. These proteins could represent additional candidates of proteins essential for development or metabolite transport processes in C4 plants. RT-PCR confirmed differential expression of thirteen candidate genes. Cp association was confirmed using GFP labeling. Genes for a PIC-like protein and an ER-AP-like protein show an early transient increase in gene expression during the transition to light. In addition, PIC gene expression is increased in the immature part of the leaf and was lower in the fully developed parts of the leaf, suggesting a need for/incorporation of the protein during chloroplast

  17. Effect of kinetin and chloramphenicol on chlorophyll synthesis and chloroplast development in detached lupin cotyledons under low light intensity

    Directory of Open Access Journals (Sweden)

    Fortunat Młodzianowski

    2015-05-01

    Full Text Available Chlorophyll synthesis in detached lupin cotyledons under low light intensity was stimulated by kinetin at 20 mg/l and inhibited by chloramphenicol at 50 mg/1. Kinetin not only conteracted the inhibitory effect of chloramphenicol, but stimulated1 the chlorophyll syntesis to a greater level than in the control material. Kinetin accelerated the starch degradation and the development of chloroplast; its prolonged, action, however, produced some abnormalities, such as an excessive growth of plastids resulting in some cases in bursting of their envelopes, the formation and release f r om plastids of numerous membrane - bound bodies and the accumulation in released and swollen thylakoids of electron - dense substance. In the presence of chloramphenicol, some disturbances in structure of the stroma thylakoids and the appearance of vesicular structures in the stroma and the enlargement of grana and swelling of their thylakoids were observed. Kinetin prevented some of these abnormalities.

  18. Optimization of beam parameters of electron gun for 2.5 MeV/100 kW high power industrial accelerator

    International Nuclear Information System (INIS)

    A 2.5 MeV/100 kW transformer type industrial accelerator is being developed at RRCAT. A Pierce type electron gun consisting of 10 mm diameter LaB6 disc (indirectly heated) is used as a source of electron beam. The cathode assembly is put on the top of the accelerating structure, which consists of many electrostatic lenses of which the first lens acts as anode of the gun. The quality of the beam injected into the accelerating structure depends on the anode voltage, shape and size of anode and its distance from the cathode. The anode is subjected to variable voltage during the operation of accelerator from energy 1 MeV to 2.5 MeV, which results in variable emittance at the exit of the electron gun. The electron beam from the gun should provide parallel or slightly convergent beam with long focal length and the emittance of the beam at the exit of electron gun should match the beam acceptance limit of the accelerating structure. The EGUN code is used to optimize the shape and size of the anode, its distance from the cathode to achieve above objectives. Our study suggests that the desired beam parameters at the exit of the anode can be obtained by reducing the aperture size of the anode and by applying suitable voltage gradient to the anode. (author)

  19. Electronic structure of crystalline uranium nitrides UN, U2N3 and UN2: LCAO calculations with the basis set optimization

    International Nuclear Information System (INIS)

    The results of LCAO DFT calculations of lattice parameters, cohesive energy and bulk modulus of the crystalline uranium nitrides UN, U2N3 and UN2 are presented and discussed. The LCAO computer codes Gaussian03 and Crystal06 are applied. The calculations are made with the uranium atom relativistic effective small core potential by Stuttgart-Cologne group (60 electrons in the core). The calculations include the U atom basis set optimization. Powell, Hooke-Jeeves, conjugated gradient and Box methods are implemented in the author's optimization package, being external to the codes for molecular and periodic calculations. The basis set optimization in LCAO calculations improves the agreement of the lattice parameter and bulk modulus of UN crystal with the experimental data, the change of the cohesive energy due to the optimization is small. The mixed metallic-covalent chemical bonding is found both in LCAO calculations of UN and U2N3 crystals; UN2 crystal has the semiconducting nature

  20. Different fates of the chloroplast tufA gene following its transfer to the nucleus in green algae.

    OpenAIRE

    Baldauf, S L; Manhart, J R; J.D. Palmer

    1990-01-01

    Previous work suggested that the tufA gene, encoding protein synthesis elongation factor Tu, was transferred from the chloroplast to the nucleus within the green algal lineage giving rise to land plants. In this report we investigate the timing and mode of transfer by examining chloroplast and nuclear DNA from the three major classes of green algae, with emphasis on the class Charophyceae, the proposed sister group to land plants. Filter hybridizations reveal a chloroplast tufA gene in all Ul...

  1. Norm Optimal Iterative Learning Control with Application to Problems in Accelerator based Free Electron Lasers and Rehabilitation Robotics

    OpenAIRE

    Rogers, E.; Owens, D H; Werner, H; Freeman, C T; Lewin, P L; Kichhoff, S; Schmidt, C; Lichtenberg, G.

    2010-01-01

    This paper gives an overview of the theoretical basis of the norm optimal approach to iterative learning control followed by results that describe more recent work which has experimentally benchmarking the performance that can be achieved. The remainder of then paper then describes its actual application to a physical process and a very novel application in stroke rehabilitation.

  2. Genetic interactions reveal that specific defects of chloroplast translation are associated with the suppression of var2-mediated leaf variegation.

    Science.gov (United States)

    Liu, Xiayan; Zheng, Mengdi; Wang, Rui; Wang, Ruijuan; An, Lijun; Rodermel, Steve R; Yu, Fei

    2013-10-01

    Arabidopsis thaliana L. yellow variegated (var2) mutant is defective in a chloroplast FtsH family metalloprotease, AtFtsH2/VAR2, and displays an intriguing green and white leaf variegation. This unique var2-mediated leaf variegation offers a simple yet powerful tool for dissecting the genetic regulation of chloroplast development. Here, we report the isolation and characterization of a new var2 suppressor gene, SUPPRESSOR OF VARIEGATION8 (SVR8), which encodes a putative chloroplast ribosomal large subunit protein, L24. Mutations in SVR8 suppress var2 leaf variegation at ambient temperature and partially suppress the cold-induced chlorosis phenotype of var2. Loss of SVR8 causes unique chloroplast rRNA processing defects, particularly the 23S-4.5S dicistronic precursor. The recovery of the major abnormal processing site in svr8 23S-4.5S precursor indicate that it does not lie in the same position where SVR8/L24 binds on the ribosome. Surprisingly, we found that the loss of a chloroplast ribosomal small subunit protein, S21, results in aberrant chloroplast rRNA processing but not suppression of var2 variegation. These findings suggest that the disruption of specific aspects of chloroplast translation, rather than a general impairment in chloroplast translation, suppress var2 variegation and the existence of complex genetic interactions in chloroplast development. PMID:23721655

  3. RNA transcription in isolated chloroplasts during senescence and rejuvenation of intact cotyledons of CUCURBITA PEPO L. (ZUCCHINI)

    International Nuclear Information System (INIS)

    RNA transcription was studied in intact chloroplasts isolated from cotyledons of Cucurbita pepoL. (zucchini) during their growth and development including natural senescence and rejuvenation. Rejuvenation of cotyledons was studied after decapitation of the epicotyl above the senescing yellow cotyledons. Maximal incorporation of [32P] UTP into overall chloroplast RNA was measured two days after exposure of seedlings to light (day 6 th after the onset of germination), followed by a gradual decrease reaching minimal values at the age of 25-28 days when cotyledons began to yellow and eventually die. Rejuvenation of cotyledons completely restored chloroplast RNA synthesis and fifteen days after decapitation (at the age of 40 days), the values of chloroplast transcription even exceeded that of the maximal transcriptional activity in young cotyledons. Inhibitory analysis with tagetitoxin (a specific inhibitor of plastid encoded chloroplast RNA polymerase (PEP)) showed that in young and rejuvenated cotyledons about 85% of chloroplast RNA polymerase activity was due to PEP and only 15% corresponded to the nuclear encoded plastid RNA polymerase (NEP). Definite regions of two chloroplast encoded genes were amplified by means of PCR technique using specific DNA primers for Rubisco large subunit gene (rbcL) and the housekeeping gene for chloroplast 16S rRNA as well as chloroplast DNA as a template. The appropriate lengths of the amplified DNA fragments were checked by restriction analysis

  4. Genetic Interactions Reveal that Specific Defects of Chloroplast Translation are Associated with the Suppression of var2-Mediated Leaf Variegation

    Institute of Scientific and Technical Information of China (English)

    Xiayan Liu; Mengdi Zheng; Rui Wang; Ruijuan Wang; Lijun An; Steve R. Rodermel; Fei Yu

    2013-01-01

    Arabidopsis thaliana L. yellow variegated (var2) mutant is defective in a chloroplast FtsH family metalloprotease, AtFtsH2/VAR2, and displays an intriguing green and white leaf variegation. This unique var2-mediated leaf variegation offers a simple yet powerful tool for dissecting the genetic regulation of chloroplast development. Here, we report the isolation and characterization of a new var2 suppressor gene, SUPPRESSOR OF VARIEGATION8 (SVR8), which encodes a putative chloroplast ribosomal large subunit protein, L24. Mutations in SVR8 suppress var2 leaf variegation at ambient temperature and partially suppress the cold-induced chlorosis phenotype of var2. Loss of SVR8 causes unique chloroplast rRNA processing defects, particularly the 23S-4.5S dicistronic precursor. The recovery of the major abnormal processing site in svr8 23S-4.5S precursor indicate that it does not lie in the same position where SVR8/L24 binds on the ribosome. Surprisingly, we found that the loss of a chloroplast ribosomal small subunit protein, S21, results in aberrant chloroplast rRNA processing but not suppression of var2 variegation. These findings suggest that the disruption of specific aspects of chloroplast translation, rather than a general impairment in chloroplast translation, suppress var2 variegation and the existence of complex genetic interactions in chloroplast development.

  5. Study of Dye-Sensitized Solar Cells by Scanning Electron Micrograph Observation and Thickness Optimization of Porous TiO2 Electrodes

    OpenAIRE

    Seigo Ito; Nazeeruddin, Mohammad K.; Zakeeruddin, Shaik M.; Peter Péchy; Pascal Comte; Michael Grätzel; Takaki Mizuno; Atsushi Tanaka; Tsuguo Koyanagi

    2009-01-01

    In order to improve the photoenergy conversion efficiency of dye-sensitized solar cells (DSCs), it is important to optimize their porous TiO2 electrodes. This paper examines the surface and cross-sectional views of the electrodes using scanning electron micrography. Two types of samples for cross-sectional viewing were prepared by mechanically breaking the substrate and by using an Ar-ion etching beam. The former displays the surface of the TiO2 particles and the latter shows the cross-secti...

  6. Transient light effects in the Hill reaction of disintegrating chloroplasts in vitro.

    Science.gov (United States)

    Harnischfeger, G; Gaffron, H

    1970-06-01

    The transient color sensitivity observed earlier in the Hill reaction of disintegrating chloroplasts (red-blue effect) was studied in detail. I. The effect was measured mainly as rates of the reduction of DPIP. It could be followed also by ferricyanide reduction or oxygen evolution. It is independent of the composition of the suspension medium and not influenced by uncouplers like methylamine. 2. Light intensity curves taken before, during and after the development of the blue decay show its presence at all light intensities. The action spectrum shows a loss of efficiency for the region λ 450-500 nm. 3. A second disintegration step which usually follows an hour later and lowers the rates in red light, has similar kinetic characteristics, but so far no particular spectral region could be implicated. 4. With ultrasonic treatment lasting from a few seconds to several minutes the double sequence of the natural loss of activity in blue and then in red light can be evoked at any time. 5. To explain these observations we assume that initially the transfer of energy from blue absorbing accessory pigments to chlorophyll is interrupted and that the same kind of pigment separation happens a second time, some-what later, among the chlorophyll pigments. The moment the light energy absorbed by the detached pigment cannot be utilized in a normal way, it promotes destructive sensitization processes which attack part of the electron transport system. The damage to the pigment system appears to occur in system II. A preliminary fluorescence curve also supports this assumption. System I (methyl red reduction) suffers through destruction of components of the electron transport chain. PMID:24496706

  7. Design and optimization of a highly efficient optical multipass system for γ-ray beam production from electron laser beam Compton scattering

    Science.gov (United States)

    Dupraz, K.; Cassou, K.; Delerue, N.; Fichot, P.; Martens, A.; Stocchi, A.; Variola, A.; Zomer, F.; Courjaud, A.; Mottay, E.; Druon, F.; Gatti, G.; Ghigo, A.; Hovsepian, T.; Riou, J. Y.; Wang, F.; Mueller, A. C.; Palumbo, L.; Serafini, L.; Tomassini, P.

    2014-03-01

    A new kind of nonresonant optical recirculator, dedicated to the production of γ rays by means of Compton backscattering, is described. This novel instrument, inspired by optical multipass systems, has its design focused on high flux and very small spectral bandwidth of the γ-ray beam. It has been developed to fulfill the project specifications of the European Extreme Light Infrastructure "Nuclear Pillar," i.e., the Gamma Beam System. Our system allows a single high power laser pulse to recirculate 32 times synchronized on the radio frequency driving accelerating cavities for the electron beam. Namely, the polarization of the laser beam and crossing angle between laser and electrons are preserved all along the 32 passes. Moreover, optical aberrations are kept at a negligible level. The general tools developed for designing, optimizing, and aligning the system are described. A detailed simulation demonstrates the high efficiency of the device.

  8. Insights from the complete chloroplast genome into the evolution of Sesamum indicum L.

    Directory of Open Access Journals (Sweden)

    Haiyang Zhang

    Full Text Available Sesame (Sesamum indicum L. is one of the oldest oilseed crops. In order to investigate the evolutionary characters according to the Sesame Genome Project, apart from sequencing its nuclear genome, we sequenced the complete chloroplast genome of S. indicum cv. Yuzhi 11 (white seeded using Illumina and 454 sequencing. Comparisons of chloroplast genomes between S. indicum and the 18 other higher plants were then analyzed. The chloroplast genome of cv. Yuzhi 11 contains 153,338 bp and a total of 114 unique genes (KC569603. The number of chloroplast genes in sesame is the same as that in Nicotiana tabacum, Vitis vinifera and Platanus occidentalis. The variation in the length of the large single-copy (LSC regions and inverted repeats (IR in sesame compared to 18 other higher plant species was the main contributor to size variation in the cp genome in these species. The 77 functional chloroplast genes, except for ycf1 and ycf2, were highly conserved. The deletion of the cp ycf1 gene sequence in cp genomes may be due either to its transfer to the nuclear genome, as has occurred in sesame, or direct deletion, as has occurred in Panax ginseng and Cucumis sativus. The sesame ycf2 gene is only 5,721 bp in length and has lost about 1,179 bp. Nucleotides 1-585 of ycf2 when queried in BLAST had hits in the sesame draft genome. Five repeats (R10, R12, R13, R14 and R17 were unique to the sesame chloroplast genome. We also found that IR contraction/expansion in the cp genome alters its rate of evolution. Chloroplast genes and repeats display the signature of convergent evolution in sesame and other species. These findings provide a foundation for further investigation of cp genome evolution in Sesamum and other higher plants.

  9. Complete chloroplast genome sequences of Mongolia medicine Artemisia frigida and phylogenetic relationships with other plants.

    Directory of Open Access Journals (Sweden)

    Yue Liu

    Full Text Available BACKGROUND: Artemisia frigida Willd. is an important Mongolian traditional medicinal plant with pharmacological functions of stanch and detumescence. However, there is little sequence and genomic information available for Artemisia frigida, which makes phylogenetic identification, evolutionary studies, and genetic improvement of its value very difficult. We report the complete chloroplast genome sequence of Artemisia frigida based on 454 pyrosequencing. METHODOLOGY/PRINCIPAL FINDINGS: The complete chloroplast genome of Artemisia frigida is 151,076 bp including a large single copy (LSC region of 82,740 bp, a small single copy (SSC region of 18,394 bp and a pair of inverted repeats (IRs of 24,971 bp. The genome contains 114 unique genes and 18 duplicated genes. The chloroplast genome of Artemisia frigida contains a small 3.4 kb inversion within a large 23 kb inversion in the LSC region, a unique feature in Asteraceae. The gene order in the SSC region of Artemisia frigida is inverted compared with the other 6 Asteraceae species with the chloroplast genomes sequenced. This inversion is likely caused by an intramolecular recombination event only occurred in Artemisia frigida. The existence of rich SSR loci in the Artemisia frigida chloroplast genome provides a rare opportunity to study population genetics of this Mongolian medicinal plant. Phylogenetic analysis demonstrates a sister relationship between Artemisia frigida and four other species in Asteraceae, including Ageratina adenophora, Helianthus annuus, Guizotia abyssinica and Lactuca sativa, based on 61 protein-coding sequences. Furthermore, Artemisia frigida was placed in the tribe Anthemideae in the subfamily Asteroideae (Asteraceae based on ndhF and trnL-F sequence comparisons. CONCLUSION: The chloroplast genome sequence of Artemisia frigida was assembled and analyzed in this study, representing the first plastid genome sequenced in the Anthemideae tribe. This complete chloroplast genome

  10. The effect of medium viscosity on kinetics of ATP hydrolysis by the chloroplast coupling factor CF1.

    Science.gov (United States)

    Malyan, Alexander N

    2016-05-01

    The coupling factor CF1 is a catalytic part of chloroplast ATP synthase which is exposed to stroma whose viscosity is many-fold higher than that of reaction mixtures commonly used to measure kinetics of CF1-catalyzed ATP hydrolysis. This study is focused on the effect of medium viscosity modulated by sucrose or bovine serum albumin (BSA) on kinetics of Ca(2+)- and Mg(2+)-dependent ATP hydrolysis by CF1. These agents were shown to reduce the maximal rate of Ca(2+)-dependent ATPase without changing the apparent Michaelis constant (К m), thus supporting the hypothesis on viscosity dependence of CF1 activity. For the sulfite- and ethanol-stimulated Mg(2+)-dependent reaction, the presence of sucrose increased К m without changing the maximal rate that is many-fold as high as that of Ca(2+)-dependent hydrolysis. The hydrolysis reaction was shown to be stimulated by low concentrations of BSA and inhibited by its higher concentrations, with the increasing maximal reaction rate estimated by extrapolation. Sucrose- or BSA-induced inhibition of the Mg(2+)-dependent ATPase reaction is believed to result from diffusion-caused deceleration, while its BSA-induced stimulation is probably caused by optimization of the enzyme structure. Molecular mechanisms of the inhibitory effect of viscosity are discussed. Taking into account high protein concentrations in the chloroplast stroma, it was suggested that kinetic parameters of ATP hydrolysis, and probably those of ATP synthesis in vivo as well, must be quite different from measurements taken at a viscosity level close to that of water. PMID:26754050

  11. Preferential translation of chloroplast ribosomal proteins in Chlamydomonas reinhardtti

    International Nuclear Information System (INIS)

    The nuclear cr-1 mutant of C. reinhardtii is deficient in the 30S subunit of the chloroplast (cp) ribosome and in cp protein synthesis. The cp spectinomycin resistant mutant, spr-u-1-27-3, has a normal level of 70S ribosomes but only a low rate of cp protein synthesis with spectinomycin present. In both mutants there is little accumulation of the large subunit of ribulose 1,5-bisphosphate carboxylase (Rubisco LSU), but near wild-type levels of cp synthesized r-proteins. In cells pulse-labelled with 35SO4 and immunoprecipitated with specific antisera, the ratio of the rate of synthesis of cp r-proteins to that of Rubisco LSU is 7 times greater in both mutants than in wild-type. No difference in the rate of turnover between r-proteins and Rubisco LSU in mutant and wild-type cells was observed during a one hour chase. The mRNA levels for r-protein L1 and Rubisco LSU actually increase slightly in the mutants. These data suggest that C. reinhardtii has a translation mechanism for preferential synthesis of cp r-proteins that operates under conditions of reduced total cp protein synthesis

  12. Identification of the Elusive Pyruvate Reductase of Chlamydomonas reinhardtii Chloroplasts.

    Science.gov (United States)

    Burgess, Steven J; Taha, Hussein; Yeoman, Justin A; Iamshanova, Oksana; Chan, Kher Xing; Boehm, Marko; Behrends, Volker; Bundy, Jacob G; Bialek, Wojciech; Murray, James W; Nixon, Peter J

    2016-01-01

    Under anoxic conditions the green alga Chlamydomonas reinhardtii activates various fermentation pathways leading to the creation of formate, acetate, ethanol and small amounts of other metabolites including d-lactate and hydrogen. Progress has been made in identifying the enzymes involved in these pathways and their subcellular locations; however, the identity of the enzyme involved in reducing pyruvate to d-lactate has remained unclear. Based on sequence comparisons, enzyme activity measurements, X-ray crystallography, biochemical fractionation and analysis of knock-down mutants, we conclude that pyruvate reduction in the chloroplast is catalyzed by a tetrameric NAD(+)-dependent d-lactate dehydrogenase encoded by Cre07.g324550. Its expression during aerobic growth supports a possible function as a 'lactate valve' for the export of lactate to the mitochondrion for oxidation by cytochrome-dependent d-lactate dehydrogenases and by glycolate dehydrogenase. We also present a revised spatial model of fermentation based on our immunochemical detection of the likely pyruvate decarboxylase, PDC3, in the cytoplasm. PMID:26574578

  13. Wood identification with PCR targeting noncoding chloroplast DNA.

    Science.gov (United States)

    Tang, Xiaoshu; Zhao, Guangjie; Ping, Liyan

    2011-12-01

    Wood identification is extremely important in the modern forest industry. It also has significant applications in forensics, as well as in archeology and ecological research. In this study, five universal primer pairs amplifying chloroplast noncoding sequences of 300-1,200 bp were designed. Sequencing these amplicons in combination can lead to reliable identification of logs and wood products to cultivar, ecotype, or even the falling population. These primer pairs work on both gymnosperms and angiosperm trees. They also are potentially applicable to accurately identify shrubs and herbaceous species. In addition, a wood DNA purification method is proposed in which N-phenacylthiazolium bromide (PTB) is used to increase the quality and quantity of extracted DNA. This method was first validated using air-dried timber disks from three different tree species that were felled 4 years ago. The sapwood and outer heartwood provided the best locations for DNA extraction. The method was also successfully applied to extract DNA from the recalcitrant processed white oak wood, randomly selected staves of wine barrels. The single nucleotide polymorphism detected on the oak DNA sequences showed correlation to their geographical origins. PMID:22038094

  14. Two complete chloroplast genome sequences of Cannabis sativa varieties.

    Science.gov (United States)

    Oh, Hyehyun; Seo, Boyoung; Lee, Seunghwan; Ahn, Dong-Ha; Jo, Euna; Park, Jin-Kyoung; Min, Gi-Sik

    2016-07-01

    In this study, we determined the complete chloroplast (cp) genomes from two varieties of Cannabis sativa. The genome sizes were 153,848 bp (the Korean non-drug variety, Cheungsam) and 153,854 bp (the African variety, Yoruba Nigeria). The genome structures were identical with 131 individual genes [86 protein-coding genes (PCGs), eight rRNA, and 37 tRNA genes]. Further, except for the presence of an intron in the rps3 genes of two C. sativa varieties, the cp genomes of C. sativa had conservative features similar to that of all known species in the order Rosales. To verify the position of C. sativa within the order Rosales, we conducted phylogenetic analysis by using concatenated sequences of all PCGs from 17 complete cp genomes. The resulting tree strongly supported monophyly of Rosales. Further, the family Cannabaceae, represented by C. sativa, showed close relationship with the family Moraceae. The phylogenetic relationship outlined in our study is well congruent with those previously shown for the order Rosales. PMID:26104156

  15. The complete chloroplast genome sequence of Abies nephrolepis (Pinaceae: Abietoideae

    Directory of Open Access Journals (Sweden)

    Dong-Keun Yi

    2016-06-01

    Full Text Available The plant chloroplast (cp genome has maintained a relatively conserved structure and gene content throughout evolution. Cp genome sequences have been used widely for resolving evolutionary and phylogenetic issues at various taxonomic levels of plants. Here, we report the complete cp genome of Abies nephrolepis. The A. nephrolepis cp genome is 121,336 base pairs (bp in length including a pair of short inverted repeat regions (IRa and IRb of 139 bp each separated by a small single copy (SSC region of 54,323 bp (SSC and a large single copy region of 66,735 bp (LSC. It contains 114 genes, 68 of which are protein coding genes, 35 tRNA and four rRNA genes, six open reading frames, and one pseudogene. Seventeen repeat units and 64 simple sequence repeats (SSR have been detected in A. nephrolepis cp genome. Large IR sequences locate in 42-kb inversion points (1186 bp. The A. nephrolepis cp genome is identical to Abies koreana’s which is closely related to taxa. Pairwise comparison between two cp genomes revealed 140 polymorphic sites in each. Complete cp genome sequence of A. nephrolepis has a significant potential to provide information on the evolutionary pattern of Abietoideae and valuable data for development of DNA markers for easy identification and classification.

  16. Optimization of a Differential Ion Mobility Spectrometry-Tandem Mass Spectrometry Method for High-Throughput Analysis of Nicotine and Related Compounds: Application to Electronic Cigarette Refill Liquids.

    Science.gov (United States)

    Regueiro, Jorge; Giri, Anupam; Wenzl, Thomas

    2016-06-21

    Fast market penetration of electronic cigarettes is leading to an exponentially growing number of electronic refill liquids with different nicotine contents and an endless list of flavors. Therefore, rapid and simple methods allowing a fast screening of these products are necessary to detect harmful substances which can negatively impact the health of consumers. In this regard, the present work explores the capabilities of differential ion mobility spectrometry coupled to tandem mass spectrometry for high-throughput analysis of nicotine and 11 related compounds in commercial refill liquids for electronic cigarettes. The influence of main factors affecting the ion mobility separation, such as modifier types and concentration, separation voltage, and temperature, was systematically investigated. Despite small molecular weight differences among the studied compounds, a good separation was achieved in the ion mobility cell under the optimized conditions, which involved the use of ethanol as a polar gas-phase chemical modifier. Indeed, differential ion mobility was able to resolve (resolution >4) nicotine from its structural isomer anabasine without the use of any chromatographic separation. The quantitative performance of the proposed method was then evaluated, showing satisfactory precision (RSD ≤ 16%) and recoveries ranging from 85 to 100% for nicotine, and from 84 to 126% for the rest of the target analytes. Several commercial electronic cigarette refill liquids were analyzed to demonstrate the applicability of the method. In some cases, significant differences were found between labeled and measured levels of nicotine. Anatabine, cotinine, myosmine, and nornicotine were also found in some of the analyzed samples. PMID:27173877

  17. Optimal electron irradiation as a tool for functionalization of MoS2: Theoretical and experimental investigation

    International Nuclear Information System (INIS)

    We demonstrate the utility of electron irradiation as a tool to enhance device functionality of graphene-analogous MoS2. With the help of first-principles based calculations, vacancy-induced changes of various electronic properties are shown to be a combined result of crystal-field modification and spin-orbital coupling. A comparative theoretical study of various possible vacancy configurations both in bulk and monolayer MoS2 and related changes in their respective band-structures help us to explain plausible irradiation induced effects. Experimentally, various structural forms of MoS2 in bulk, few layered flakes, and nanocrystals are observed to exhibit important modification of their magnetic, transport, and vibrational properties, following low doses of electron irradiation. While irradiated single crystals and nanocrystals show an enhanced magnetization, transport properties of few-layered devices show a significant increase in their conductivity, which can be very useful for fabrication of electronic devices. Our theoretical calculations reveal that this increase in n-type conductivity and magnetization can be correlated with the presence of sulfur and molybdenum vacancies

  18. Chloroplast genome sequencing analysis of Heterosigma akashiwo CCMP452 (West Atlantic and NIES293 (West Pacific strains

    Directory of Open Access Journals (Sweden)

    Lybrand Terry

    2008-05-01

    Full Text Available Abstract Background Heterokont algae form a monophyletic group within the stramenopile branch of the tree of life. These organisms display wide morphological diversity, ranging from minute unicells to massive, bladed forms. Surprisingly, chloroplast genome sequences are available only for diatoms, representing two (Coscinodiscophyceae and Bacillariophyceae of approximately 18 classes of algae that comprise this taxonomic cluster. A universal challenge to chloroplast genome sequencing studies is the retrieval of highly purified DNA in quantities sufficient for analytical processing. To circumvent this problem, we have developed a simplified method for sequencing chloroplast genomes, using fosmids selected from a total cellular DNA library. The technique has been used to sequence chloroplast DNA of two Heterosigma akashiwo strains. This raphidophyte has served as a model system for studies of stramenopile chloroplast biogenesis and evolution. Results H. akashiwo strain CCMP452 (West Atlantic chloroplast DNA is 160,149 bp in size with a 21,822-bp inverted repeat, whereas NIES293 (West Pacific chloroplast DNA is 159,370 bp in size and has an inverted repeat of 21,665 bp. The fosmid cloning technique reveals that both strains contain an isomeric chloroplast DNA population resulting from an inversion of their single copy domains. Both strains contain multiple small inverted and tandem repeats, non-randomly distributed within the genomes. Although both CCMP452 and NIES293 chloroplast DNAs contains 197 genes, multiple nucleotide polymorphisms are present in both coding and intergenic regions. Several protein-coding genes contain large, in-frame inserts relative to orthologous genes in other plastids. These inserts are maintained in mRNA products. Two genes of interest in H. akashiwo, not previously reported in any chloroplast genome, include tyrC, a tyrosine recombinase, which we hypothesize may be a result of a lateral gene transfer event, and an

  19. Combined analysis of the chloroplast genome and transcriptome of the Antarctic vascular plant Deschampsia antarctica Desv.

    Directory of Open Access Journals (Sweden)

    Jungeun Lee

    Full Text Available BACKGROUND: Antarctic hairgrass (Deschampsia antarctica Desv. is the only natural grass species in the maritime Antarctic. It has been researched as an important ecological marker and as an extremophile plant for studies on stress tolerance. Despite its importance, little genomic information is available for D. antarctica. Here, we report the complete chloroplast genome, transcriptome profiles of the coding/noncoding genes, and the posttranscriptional processing by RNA editing in the chloroplast system. RESULTS: The complete chloroplast genome of D. antarctica is 135,362 bp in length with a typical quadripartite structure, including the large (LSC: 79,881 bp and small (SSC: 12,519 bp single-copy regions, separated by a pair of identical inverted repeats (IR: 21,481 bp. It contains 114 unique genes, including 81 unique protein-coding genes, 29 tRNA genes, and 4 rRNA genes. Sequence divergence analysis with other plastomes from the BEP clade of the grass family suggests a sister relationship between D. antarctica, Festuca arundinacea and Lolium perenne of the Poeae tribe, based on the whole plastome. In addition, we conducted high-resolution mapping of the chloroplast-derived transcripts. Thus, we created an expression profile for 81 protein-coding genes and identified ndhC, psbJ, rps19, psaJ, and psbA as the most highly expressed chloroplast genes. Small RNA-seq analysis identified 27 small noncoding RNAs of chloroplast origin that were preferentially located near the 5'- or 3'-ends of genes. We also found >30 RNA-editing sites in the D. antarctica chloroplast genome, with a dominance of C-to-U conversions. CONCLUSIONS: We assembled and characterized the complete chloroplast genome sequence of D. antarctica and investigated the features of the plastid transcriptome. These data may contribute to a better understanding of the evolution of D. antarctica within the Poaceae family for use in molecular phylogenetic studies and may also help researchers

  20. Insights into the subunit in-teractions of the chloroplast ATP synthase

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Subunit interactions of the chloroplast F0F1- ATP synthase were studied using the yeast two-hybrid system. The coding sequences of all the nine subunits of spinach chloroplast ATP synthase were cloned in two-hybrid vectors. The vectors were transformed into the yeast strains HF7c and SFY526 by various pairwise combinations, and the protein interactions were analyzed by measuring the yeast growth on minimal SD medium without serine, lucine and histidine. Interactions of γ Subunit with wild type or two truncated mutants of γ sununit, △εN21 and △εC45, which lose their abilities to inhibit the ATP hydrolysis, were also detected by in vitro and in vivo binding assay. The present results are largely accordant to the common structure model of F0F1-ATP synthase. Different from that in the E. Coli F0F1-ATP synthase, the δ subunit of chloroplast ATP syn- thase could interact with β,γ,ε and all the CF0 subunits in the two-hybrid system. These results suggested that though the chloroplast ATP synthase shares the similar structure and composition of subunits with the enzyme from E. Coli, it may be different in the subunit interactions and con- formational change during catalysis between these two sources of ATP synthase. Based on the present results and our knowledge of structure model of E. Coli ATP synthase, a deduced structure model of chloroplast ATP synthase was proposed.

  1. Comparative Analysis of Codon Usage Patterns Among Mitochondrion, Chloroplast and Nuclear Genes in Triticum aestivum L.

    Institute of Scientific and Technical Information of China (English)

    Wen-Juan Zhang; Jie Zhou; Zuo-Feng Li; Li Wang; Xun Gu; Yang Zhong

    2007-01-01

    In many organisms, the difference in codon usage patterns among genes reflects variation in local base compositional biases and the intensity of natural selection. In this study, a comparative analysis was performed to investigate the characteristics of codon bias and factors in shaping the codon usage patterns among mitochondrion,chloroplast and nuclear genes in common wheat (Triticum aestivum L.). GC contents in nuclear genes were higher than that in mitochondrion and chloroplast genes. The neutrality and correspondence analyses indicated that the codon usage in nuclear genes would be a result of relative strong mutational bias, while the codon usage patterns of rnitochondrion and chloroplast genes were more conserved in GC content and influenced by translation level.The Parity Rule 2 (PR2) plot analysis showed that pyrimidines were used more frequently than purines at the third codon position in the three genomes. In addition, using a new alterative strategy, 11, 12, and 24 triplets were defined as preferred codons in the mitochondrion, chloroplast and nuclear genes, respectively. These findings suggested that the mitochondrion, chloroplast and nuclear genes shared particularly different features of codon usage and evolutionary constraints.

  2. The effect of UV-B radiation on chloroplast translation in Pisum sativum

    International Nuclear Information System (INIS)

    UV-B radiation has previously been reported to reduce growth, flowering, and net photosynthesis. The present study examines the effect of UV-B radiation on isolated chloroplast of 7-10 day old pea seedlings. Amount of (3H)-Leu incorporated into isolated chloroplasts was measured in the presence or absence of UV-B exposure. Preliminary experiments show a 30% inhibition of protein synthesis in isolated chloroplasts after only 20 mins of UV-B exposure (6.9 J/m2/30 min). Percent inhibition of chloroplast translation is directly correlated with UV-B exposure over a 60 min time span. Preliminary studies also show no change in both cold and radiolabeled protein profiles as expressed on 1-D PAGE and autofluorography. Comparative studies on the sensitivity of e- flow vs protein synthesis following UV-B exposure are underway. Further work on the role of oxygen free radicals and the specific site of action of UV-B damage to the translation machinery of chloroplasts will be discussed

  3. Proteomic comparison reveals the contribution of chloroplast to salt tolerance of a wheat introgression line.

    Science.gov (United States)

    Xu, Wenjing; Lv, Hongjun; Zhao, Mingming; Li, Yongchao; Qi, Yueying; Peng, Zhenying; Xia, Guangmin; Wang, Mengcheng

    2016-01-01

    We previously bred a salt tolerant wheat cv. SR3 with bread wheat cv. JN177 as the parent via asymmetric somatic hybridization, and found that the tolerance is partially attributed to the superior photosynthesis capacity. Here, we compared the proteomes of two cultivars to unravel the basis of superior photosynthesis capacity. In the maps of two dimensional difference gel electrophoresis (2D-DIGE), there were 26 differentially expressed proteins (DEPs), including 18 cultivar-based and 8 stress-responsive ones. 21 of 26 DEPs were identified and classified into four categories, including photosynthesis, photosynthesis system stability, linolenic acid metabolism, and protein synthesis in chloroplast. The chloroplast localization of some DEPs confirmed that the identified DEPs function in the chloroplast. The overexpression of a DEP enhanced salt tolerance in Arabidopsis thaliana. In line with these data, it is concluded that the contribution of chloroplast to high salinity tolerance of wheat cv. SR3 appears to include higher photosynthesis efficiency by promoting system protection and ROS clearance, stronger production of phytohormone JA by enhancing metabolism activity, and modulating the in chloroplast synthesis of proteins. PMID:27562633

  4. Homologous Comparisons of Photosynthetic System 1 Genes among Cyanobacteria and Chloroplasts

    Institute of Scientific and Technical Information of China (English)

    Jie Yu; Pei-Jun Ma; Ding-Ji Shi; Shi-Ming Li; Chang-Lu Wang

    2008-01-01

    It has now believed that chloroplasts arose from cyanobacteria,however,during endosymbiosis,the photosynthetic genes in chloroplasts have been reduced.How these changes occurred during plant evolution was the focus of the present study.Beginning with photosystem Ⅰ (PSI) genes,a homologous comparison of amino acid sequences of 18 subunits of PSI from 10 species of cyanobacteria,chloroplasts in 12 species of eucaryotic algae,and 28 species of plants (including bryophytes,pteridophytes,gymnospermae,dicotyledon and monocotyledon) was undertaken.The data showed that 18 genes of PSIcan be divided into two groups: Part Ⅰ including seven genes (psaA,psaB,psaC,psaI,psaJ,yct3 and ycf4) shared both by cyanobacteria and plant chloroplasts;Part Ⅱ containing another 11 genes (psaD,psaE,psaF,psaK,psaL,psaM,btpA,ycf37,psaG,psaH and psaN) appeared to have diversified in different plant groups.Among Part I genes,psaC,psaA and psaB had higher homology in all species of cyanobacteria and chloroplasts.Among Part II genes,only psaG,psaH and psaN emerged in seed plants.

  5. Recombination and Heterologous Expression of Allophycocyanin Gene in the Chloroplast of Chlamydomonas reinhardtii

    Institute of Scientific and Technical Information of China (English)

    Zhong-Liang SU; Kai-Xian QIAN; Cong-Ping TAN; Chun-Xiao MENG; Song QIN

    2005-01-01

    Heterogeneous expression of multiple genes in the nucleus of transgenic plants requires the introduction of an individual gene and the subsequent backcross to reconstitute multi-subunit proteins or metabolic pathways. In order to accomplish the expression of multiple genes in a single transformation event, we inserted both large and small subunits of allophycocyanin gene (apcA and apcB) into Chlamydomonas reinhardtii chloroplast expression vector, resulting in papc-S. The constructed vector was then introduced into the chloroplast of C. reinhardtii by micro-particle bombardment. Polymerase chain reaction and Southern blot analysis revealed that the two genes had integrated into the chloroplast genome. Western blot and enzyme-linked immunosorbent assay showed that the two genes from the prokaryotic cyanobacteria could be correctly expressed in the chloroplasts of C. reinhardtii. The expressed foreign protein in transformants accounted for about 2%-3% of total soluble proteins. These findings pave the way to the reconstitution of multi-subunit proteins or metabolic pathways in transgenic C. reinhardtii chloroplasts in a single transformation event.

  6. Construction of a chloroplast protein interaction network and functional mining of photosynthetic proteins in Arabidopsis thaliana

    Institute of Scientific and Technical Information of China (English)

    Qing-Bo Yu; Yong-Lan Cui; Kang Chong; Yi-Xue Li; Yu-Hua Li; Zhongming Zhao; Tie-Liu Shi; Zhong-Nan Yang; Guang Li; Guan Wang; Jing-Chun Sun; Peng-Cheng Wang; Chen Wang; Hua-Ling Mi; Wei-Min Ma; Jian Cui

    2008-01-01

    Chloroplast is a typical plant cell organeUe where photosynthesis takes place.In this study,a total of 1 808 chloroplast core proteins in Arabidopsis thaliana were reliably identified by combining the results of previously published studies and our own predictions.We then constructed a chloroplast protein interaction network primarily based on these core protein interactions.The network had 22 925 protein interaction pairs which involved 2 214 proteins.A total of 160 previously uncharacterized proteins were annotated in this network.The subunits of the photosynthetic complexes were modularized,and the functional relationships among photosystem Ⅰ (PSI),photosystem Ⅱ (PSII),light harvesting complex of photosystem Ⅰ (LHC Ⅰ) and light harvesting complex of photosystem Ⅰ (LHC Ⅱ) could be deduced from the predicted protein interactions in this network.We further confirmed an interaction between an unknown protein AT1G52220 and a photosynthetic subunit PSI-D2 by yeast two-hybrid analysis.Our chloroplast protein interaction network should be useful for functional mining of photosynthetic proteins and investigation of chloroplast-related functions at the systems biology level in Arabidopsis.

  7. Chloroplast lipid transfer processes in Chlamydomonas reinhardtii involving a TRIGALACTOSYLDIACYLGLYCEROL 2 (TGD2) orthologue.

    Science.gov (United States)

    Warakanont, Jaruswan; Tsai, Chia-Hong; Michel, Elena J S; Murphy, George R; Hsueh, Peter Y; Roston, Rebecca L; Sears, Barbara B; Benning, Christoph

    2015-12-01

    In plants, lipids of the photosynthetic membrane are synthesized by parallel pathways associated with the endoplasmic reticulum (ER) and the chloroplast envelope membranes. Lipids derived from the two pathways are distinguished by their acyl-constituents. Following this plant paradigm, the prevalent acyl composition of chloroplast lipids suggests that Chlamydomonas reinhardtii (Chlamydomonas) does not use the ER pathway; however, the Chlamydomonas genome encodes presumed plant orthologues of a chloroplast lipid transporter consisting of TGD (TRIGALACTOSYLDIACYLGLYCEROL) proteins that are required for ER-to-chloroplast lipid trafficking in plants. To resolve this conundrum, we identified a mutant of Chlamydomonas deleted in the TGD2 gene and characterized the respective protein, CrTGD2. Notably, the viability of the mutant was reduced, showing the importance of CrTGD2. Galactoglycerolipid metabolism was altered in the tgd2 mutant with monogalactosyldiacylglycerol (MGDG) synthase activity being strongly stimulated. We hypothesize this to be a result of phosphatidic acid accumulation in the chloroplast outer envelope membrane, the location of MGDG synthase in Chlamydomonas. Concomitantly, increased conversion of MGDG into triacylglycerol (TAG) was observed. This TAG accumulated in lipid droplets in the tgd2 mutant under normal growth conditions. Labeling kinetics indicate that Chlamydomonas can import lipid precursors from the ER, a process that is impaired in the tgd2 mutant. PMID:26496373

  8. Blue-light induced development of chloroplasts in isolated seedling roots

    International Nuclear Information System (INIS)

    Excised roots of pea seedlings (Pisum sativum var. 'Alaska') cultured in a synthetic medium under sterile conditions exhibited differentiation of functional chloroplasts from leucoplasts when irradiated with blue light (350 to 550 nm). This transition was a relatively slow process; nevertheless, the chloroplasts formed in blue light compared very well to leaf chloroplasts as far as micro-structure and photosynthetic activities are concerned. Apparently certain activities of the apical meristem are mandatory in bringing about a transition from leucoplasts to chloroplasts in blue light. After short-time labelling with [3H]uridine the synthesis of plastid ribosomal RNA (rRNA) was studied either during irradiation with blue and red light (600 to 700 nm), respectively, or in darkness. Polyacrylamide gel electrophoresis revealed that in blue light the synthesis of specific chloroplast rRNA species with molecular weights of 1.1 x 106 and 0.56 x 106 daltons was markedly stimulated. In contrast, in dark cultured roots these RNA species were synthesized to a limited extent only whereas the cytoplasmic rRNA species of 1.3 x 106 and 0.7 x 106 daltons molecular weight were preferentially formed. The same held true for roots irradiated with red light. (author)

  9. Polyuridylylation and processing of transcripts from multiple gene minicircles in chloroplasts of the dinoflagellate Amphidinium carterae

    KAUST Repository

    Barbrook, Adrian C.

    2012-05-05

    Although transcription and transcript processing in the chloroplasts of plants have been extensively characterised, the RNA metabolism of other chloroplast lineages across the eukaryotes remains poorly understood. In this paper, we use RT-PCR to study transcription and transcript processing in the chloroplasts of Amphidinium carterae, a model peridinin-containing dinoflagellate. These organisms have a highly unusual chloroplast genome, with genes located on multiple small \\'minicircle\\' elements, and a number of idiosyncratic features of RNA metabolism including transcription via a rolling circle mechanism, and 3′ terminal polyuridylylation of transcripts. We demonstrate that transcription occurs in A. carterae via a rolling circle mechanism, as previously shown in the dinoflagellate Heterocapsa, and present evidence for the production of both polycistronic and monocistronic transcripts from A. carterae minicircles, including several regions containing ORFs previously not known to be expressed. We demonstrate the presence of both polyuridylylated and non-polyuridylylated transcripts in A. carterae, and show that polycistronic transcripts can be terminally polyuridylylated. We present a model for RNA metabolism in dinoflagellate chloroplasts where long polycistronic precursors are processed to form mature transcripts. Terminal polyuridylylation may mark transcripts with the correct 3′ end. © 2012 Springer Science+Business Media B.V.

  10. CHLOROPLAST GENETIC TOOL FOR THE GREEN MICROALGAE HAEMATOCOCCUS PLUVIALIS (CHLOROPHYCEAE, VOLVOCALES)(1).

    Science.gov (United States)

    Gutiérrez, Carla L; Gimpel, Javier; Escobar, Carolina; Marshall, Sergio H; Henríquez, Vitalia

    2012-08-01

    At present, there is strong commercial demand for recombinant proteins, such as antigens, antibodies, biopharmaceuticals, and industrial enzymes, which cannot be fulfilled by existing procedures. Thus, an intensive search for alternative models that may provide efficiency, safety, and quality control is being undertaken by a number of laboratories around the world. The chloroplast of the eukaryotic microalgae Haematococcus pluvialis Flotow has arisen as a candidate for a novel expression platform for recombinant protein production. However, there are important drawbacks that need to be resolved before it can become such a system. The most significant of these are chloroplast genome characterizations, and the development of chloroplast transformation vectors based upon specific endogenous promoters and on homologous targeting regions. In this study, we report the identification and characterization of endogenous chloroplast sequences for use as genetic tools for the construction of H. pluvialis specific expression vectors to efficiently transform the chloroplast of this microalga via microprojectile bombardment. As a consequence, H. pluvialis shows promise as a platform for expressing recombinant proteins for biotechnological applications, for instance, the development of oral vaccines for aquaculture. PMID:27009007

  11. Influence of lanthanum on chloroplast ultrastructure of soybean leaves under ultraviolet-B stress

    Institute of Scientific and Technical Information of China (English)

    PENG Qian; ZHOU Qing

    2009-01-01

    In order to investigate the effects of lanthanum(Ⅲ) on cell ultrastructure of soybean leaves under elevated ultraviolet-B irradiation (UV-B, 280-320 rim), the chloroplast ultrastructure of soybean seedlings was studied by hydroponics under laboratory conditions. The re-sults showed that the thylakoid in chloroplast was orderly and clearly as soybean leaves were pretreated by La(Ⅲ). The thylakoid was indis-tinctly disordered, expanded and even indiscoverable in the chloroplast under UV-B stress. The impact on the thylakoid by the high in-tensity UV-B irradiation (T2) was bigger than that by the low intensity UV-B irradiation (T1). However, the destruction of the chloroplast structure caused by UV-B stress was alleviated by La(Ⅲ), and the arrangement of the thylakoid in the chloroplast became orderly and clearly. The effect of the alleviation by La(Ⅲ) under the low intensity UV-B irradiation (T1) was better than that under the high intensity UV-B irradiation (T2).

  12. Complete chloroplast genome sequence of Omani lime (Citrus aurantiifolia and comparative analysis within the rosids.

    Directory of Open Access Journals (Sweden)

    Huei-Jiun Su

    Full Text Available The genus Citrus contains many economically important fruits that are grown worldwide for their high nutritional and medicinal value. Due to frequent hybridizations among species and cultivars, the exact number of natural species and the taxonomic relationships within this genus are unclear. To compare the differences between the Citrus chloroplast genomes and to develop useful genetic markers, we used a reference-assisted approach to assemble the complete chloroplast genome of Omani lime (C. aurantiifolia. The complete C. aurantiifolia chloroplast genome is 159,893 bp in length; the organization and gene content are similar to most of the rosids lineages characterized to date. Through comparison with the sweet orange (C. sinensis chloroplast genome, we identified three intergenic regions and 94 simple sequence repeats (SSRs that are potentially informative markers with resolution for interspecific relationships. These markers can be utilized to better understand the origin of cultivated Citrus. A comparison among 72 species belonging to 10 families of representative rosids lineages also provides new insights into their chloroplast genome evolution.

  13. The Complete Chloroplast Genome Sequences of the Medicinal Plant Pogostemon cablin.

    Science.gov (United States)

    He, Yang; Xiao, Hongtao; Deng, Cao; Xiong, Liang; Yang, Jian; Peng, Cheng

    2016-01-01

    Pogostemon cablin, the natural source of patchouli alcohol, is an important herb in the Lamiaceae family. Here, we present the entire chloroplast genome of P. cablin. This genome, with 38.24% GC content, is 152,460 bp in length. The genome presents a typical quadripartite structure with two inverted repeats (each 25,417 bp in length), separated by one small and one large single-copy region (17,652 and 83,974 bp in length, respectively). The chloroplast genome encodes 127 genes, of which 107 genes are single-copy, including 79 protein-coding genes, four rRNA genes, and 24 tRNA genes. The genome structure, GC content, and codon usage of this chloroplast genome are similar to those of other species in the family, except that it encodes less protein-coding genes and tRNA genes. Phylogenetic analysis reveals that P. cablin diverged from the Scutellarioideae clade about 29.45 million years ago (Mya). Furthermore, most of the simple sequence repeats (SSRs) are short polyadenine or polythymine repeats that contribute to high AT content in the chloroplast genome. Complete sequences and annotation of P. cablin chloroplast genome will facilitate phylogenic, population and genetic engineering research investigations involving this particular species. PMID:27275817

  14. The Complete Chloroplast Genome Sequences of the Medicinal Plant Pogostemon cablin

    Directory of Open Access Journals (Sweden)

    Yang He

    2016-06-01

    Full Text Available Pogostemon cablin, the natural source of patchouli alcohol, is an important herb in the Lamiaceae family. Here, we present the entire chloroplast genome of P. cablin. This genome, with 38.24% GC content, is 152,460 bp in length. The genome presents a typical quadripartite structure with two inverted repeats (each 25,417 bp in length, separated by one small and one large single-copy region (17,652 and 83,974 bp in length, respectively. The chloroplast genome encodes 127 genes, of which 107 genes are single-copy, including 79 protein-coding genes, four rRNA genes, and 24 tRNA genes. The genome structure, GC content, and codon usage of this chloroplast genome are similar to those of other species in the family, except that it encodes less protein-coding genes and tRNA genes. Phylogenetic analysis reveals that P. cablin diverged from the Scutellarioideae clade about 29.45 million years ago (Mya. Furthermore, most of the simple sequence repeats (SSRs are short polyadenine or polythymine repeats that contribute to high AT content in the chloroplast genome. Complete sequences and annotation of P. cablin chloroplast genome will facilitate phylogenic, population and genetic engineering research investigations involving this particular species.

  15. Optimal all-optical switching of a microcavity resonance in the telecom range using the electronic Kerr effect

    CERN Document Server

    Yüce, Emre; Claudon, Julien; Gérard, Jean-Michel; Vos, Willem L

    2015-01-01

    We have switched GaAs/AlAs and AlGaAs/AlAs planar microcavities operating in the "original" telecom band by exploiting the instantaneous electronic Kerr effect. We demonstrate that resonance frequency reversibly shifts within a picosecond and the magnitude of the shift is affected by the backbone of the $\\lambda-$layer. We investigate experimentally and theoretically the role of the quality factor in terms of its effect on resonance frequency shift. Our model shows that the magnitude of the resonance frequency shift depends on the pump pulse duration and is maximized when the cavity cavity storage time is matched. Our experiments and our calculations indicate that the resonance frequency shift induced via the electronic Kerr effect can be maximized by judicious tuning of the pump frequency, pump power and pump pulse duration relative to the storage time of the cavity.

  16. Optimal all-optical switching of a microcavity resonance in the telecom range using the electronic Kerr effect

    Science.gov (United States)

    Yüce, Emre; Ctistis, Georgios; Claudon, Julien; Gérard, Jean-Michel; Vos, Willem L.

    2016-01-01

    We have switched GaAs/AlAs and AlGaAs/AlAs planar microcavities that operate in the "Original" (O) telecom band by exploiting the instantaneous electronic Kerr effect. We observe that the resonance frequency reversibly shifts within one picosecond. We investigate experimentally and theoretically the role of several main parameters: the material backbone and its electronic bandgap, the pump power, the quality factor, and the duration of the switch pulse. The magnitude of the shift is reduced when the backbone of the central $\\lambda-$layer has a greater electronic bandgap; pumping with photon energies near the bandgap resonantly enhances the switched magnitude. Our model shows that the magnitude of the resonance frequency shift depends on the pump pulse duration and is maximized when the duration matches the cavity storage time that is set by the quality factor. We provide the settings for the essential parameters so that the frequency shift of the cavity resonance can be increased to one linewidth.

  17. Investigation and optimization of low-frequency noise performance in readout electronics of dc superconducting quantum interference device

    International Nuclear Information System (INIS)

    We investigated and optimized the low-frequency noise characteristics of a preamplifier used for readout of direct current superconducting quantum interference devices (SQUIDs). When the SQUID output was detected directly using a room-temperature low-voltage-noise preamplifier, the low-frequency noise of a SQUID system was found to be dominated by the input current noise of the preamplifiers in case of a large dynamic resistance of the SQUID. To reduce the current noise of the preamplifier in the low-frequency range, we investigated the dependence of total preamplifier noise on the collector current and source resistance. When the collector current was decreased from 8.4 mA to 3 mA in the preamplifier made of 3 parallel SSM2220 transistor pairs, the low-frequency total voltage noise of the preamplifier (at 0.1 Hz) decreased by about 3 times for a source resistance of 30 Ω whereas the white noise level remained nearly unchanged. Since the relative contribution of preamplifier's input voltage and current noise is different depending on the dynamic resistance or flux-to-voltage transfer of the SQUID, the results showed that the total noise of a SQUID system at low-frequency range can be improved significantly by optimizing the preamplifier circuit parameters, mainly the collector current in case of low-noise bipolar transistor pairs

  18. Towards resolving Lamiales relationships: insights from rapidly evolving chloroplast sequences

    Directory of Open Access Journals (Sweden)

    Heubl Günther

    2010-11-01

    Full Text Available Abstract Background In the large angiosperm order Lamiales, a diverse array of highly specialized life strategies such as carnivory, parasitism, epiphytism, and desiccation tolerance occur, and some lineages possess drastically accelerated DNA substitutional rates or miniaturized genomes. However, understanding the evolution of these phenomena in the order, and clarifying borders of and relationships among lamialean families, has been hindered by largely unresolved trees in the past. Results Our analysis of the rapidly evolving trnK/matK, trnL-F and rps16 chloroplast regions enabled us to infer more precise phylogenetic hypotheses for the Lamiales. Relationships among the nine first-branching families in the Lamiales tree are now resolved with very strong support. Subsequent to Plocospermataceae, a clade consisting of Carlemanniaceae plus Oleaceae branches, followed by Tetrachondraceae and a newly inferred clade composed of Gesneriaceae plus Calceolariaceae, which is also supported by morphological characters. Plantaginaceae (incl. Gratioleae and Scrophulariaceae are well separated in the backbone grade; Lamiaceae and Verbenaceae appear in distant clades, while the recently described Linderniaceae are confirmed to be monophyletic and in an isolated position. Conclusions Confidence about deep nodes of the Lamiales tree is an important step towards understanding the evolutionary diversification of a major clade of flowering plants. The degree of resolution obtained here now provides a first opportunity to discuss the evolution of morphological and biochemical traits in Lamiales. The multiple independent evolution of the carnivorous syndrome, once in Lentibulariaceae and a second time in Byblidaceae, is strongly supported by all analyses and topological tests. The evolution of selected morphological characters such as flower symmetry is discussed. The addition of further sequence data from introns and spacers holds promise to eventually obtain a

  19. Geographic variation of chloroplast DNA in Platycarya strobilacea (Juglandaceae)

    Institute of Scientific and Technical Information of China (English)

    Shi-Chao CHEN; Li ZHANG; Jie ZENG; Fei SHI; Hong YANG; Yun-Rui MAO; Cheng-Xin FU

    2012-01-01

    The monotypic genus Platycarya (Juglandaceae) is one of the most widespread temperate tree species in East Asia.In this research,we implemented a phylogeographical study using chloroplast DNA (cpDNA) (psbA-trnH and atpB-rbcL intergenic spacer) sequences on Platycarya strobilacea,in order to identify the locations of the species' main refugia and migration routes.A total of 180 individuals of P.stobilacea from 27 populations from China and Jeju Island (Korea) were collected.The results revealed that P.strobilacea had 35 haplotypes for the two intergenic spacers and high genetic diversity (hT =0.926).This surprisingly high diversity ofhaplotypes indicates its long evolutionary history,which is in agreement with previous phylogenetic analyses and fossil records.Significant cpDNA population subdivision was detected (GST =0.720; NST =0.862),suggesting low levels of recurrent gene flow through seeds among populations and significant phylogeographical structure (NST > GST,P < 0.05).The construction of phylogenetic relationships of the 35 chlorotypes detected four major cpDNA clades.Divergence dating analyses using BEAST suggest that the divergence of the major cpDNA clades occurred before the Miocene.Demographic analysis indicated that the Eastern clade underwent localized demographic expansions.The molecular phylogenetic data,together with the geographic distribution of the haplotypes,suggest the existence of multiple glacial refugia in most of its current range in China through Quaternary climatic oscillations.

  20. The complete chloroplast genome sequence of Lilium hansonii Leichtlin ex D.D.T.Moore.

    Science.gov (United States)

    Kim, Kyunghee; Hwang, Yoon-Jung; Lee, Sang-Choon; Yang, Tae-Jin; Lim, Ki-Byung

    2016-09-01

    Lilium hansonii is a lily species native to Korea and an important wild species for lily breeding. The chloroplast genome of L. hansonii was completed by de novo assembly using the small amount of whole genome sequencing data. The chloroplast genome of L. hansonii was 152 655 bp long and consisted of large single copy region (82 051 bp), small single copy region (17 620 bp) and a pair of inverted repeat regions (26 492 bp). A total of 115 genes were annotated, which included 81 protein-coding genes, 30 tRNA genes and 4 rRNA genes. Phylogenetic analysis with the reported chloroplast genomes revealed that L. hansonii is most closely related to L. superbum (Turk's-cap lily) and L. longiflorum (Easter lily). PMID:26404645

  1. Identification of CP12 as a Novel Calcium-Binding Protein in Chloroplasts

    Directory of Open Access Journals (Sweden)

    Agostinho Gomes Rocha

    2013-08-01

    Full Text Available Calcium plays an important role in the regulation of several chloroplast processes. However, very little is still understood about the calcium fluxes or calcium-binding proteins present in plastids. Indeed, classical EF-hand containing calcium-binding proteins appears to be mostly absent from plastids. In the present study we analyzed the stroma fraction of Arabidopsis chloroplasts for the presence of novel calcium-binding proteins using 2D-PAGE separation followed by calcium overlay assay. A small acidic protein was identified by mass spectrometry analyses as the chloroplast protein CP12 and the ability of CP12 to bind calcium was confirmed with recombinant proteins. CP12 plays an important role in the regulation of the Calvin-Benson-Bassham Cycle participating in the assembly of a supramolecular complex between phosphoribulokinase and glyceraldehyde 3-phosphate dehydrogenase, indicating that calcium signaling could play a role in regulating carbon fixation.

  2. In vitro chloroplast protein synthesis by the chromophytic alga Olisthodiscus luteus

    International Nuclear Information System (INIS)

    The chloroplasts of chlorophytic and chromophytic plants exhibit significant morphological and biochemical differences. Presently, it is impossible to compare the influence of ctDNA on the structure and function of organelles within these two phylogenetic groups for no data exist in the literature on the profile of protein products synthesized by a chromophytic plastid. In this paper, the chloroplast DNA coded proteins of the chromophytic plant Olisthodiscus luteus are investigated by labeling isolated chloroplasts in vitro. Isolated plastids of excellent morphological condition are pulse labeled with [35S]methionine. Approximately 100 proteins are detected by two-dimensional gel electrophoresis and fluorography. However, these isolated plastids have a number of unusual characteristics: (1) they are photosynthetically inactive; (2) in vitro protein synthesis is light independent; (3) all proteins synthesized in vitro are membrane associated

  3. The complete chloroplast genome sequence of the medicinal plant Rheum palmatum L. (Polygonaceae).

    Science.gov (United States)

    Fan, Kai; Sun, Xiao-Jie; Huang, Min; Wang, Xu-Mei

    2016-07-01

    The complete chloroplast genome of the medicinal plant Rheum palmatum L. (Polygonaceae) has been reconstructed from the whole-genome Illumina sequencing data. The genome is 161 541 bp in length, and exhibits a typical quadripartite structure of the large (LSC, 86 518 bp) and small (SSC, 13 111 bp) single-copy regions, separated by a pair of inverted repeats (IRs, 30 956 bp each). The chloroplast genome contains 131 genes, including 84 protein-coding genes (78 PCG species), eight ribosomal RNA genes (four rRNA species) and 37 transfer RNA genes (28 tRNA species). Phylogenetic tree based on the maximum parsimony (MP) analysis of 65 chloroplast protein-coding genes for 13 taxa demonstrated a close relationship between R. palmatum and Fagopyrum esculentum subsp. ancestrale in Polygonaceae. PMID:26153751

  4. Metabolic engineering of chloroplasts for artemisinic acid biosynthesis and impact on plant growth

    Indian Academy of Sciences (India)

    Bhawna Saxena; Mayavan Subramaniyan; Karan Malhotra; Neel Sarovar Bhavesh; Shobha Devi Potlakayala; Shashi Kumar

    2014-03-01

    Chloroplasts offer high-level transgene expression and transgene containment due to maternal inheritance, and are ideal hosts for biopharmaceutical biosynthesis via multigene engineering. To exploit these advantages, we have expressed 12 enzymes in chloroplasts for the biosynthesis of artemisinic acid (precursor of artemisinin, antimalarial drug) in an alternative plant system. Integration of transgenes into the tobacco chloroplast genome via homologous recombination was confirmed by molecular analysis, and biosynthesis of artemisinic acid in plant leaf tissues was detected with the help of 13C NMR and ESI-mass spectrometry. The excess metabolic flux of isopentenyl pyrophosphate generated by an engineered mevalonate pathway was diverted for the biosynthesis of artemisinic acid. However, expression of megatransgenes impacted the growth of the transplastomic plantlets. By combining two exogenous pathways, artemisinic acid was produced in transplastomic plants, which can be improved further using better metabolic engineering strategies for commercially viable yield of desirable isoprenoid products.

  5. Identification of the 64 kilodalton chloroplast stromal phosphoprotein as phosphoglucomutase. [Pisum sativum

    Energy Technology Data Exchange (ETDEWEB)

    Salvucci, M.E.; Drake, R.R.; Broadbent, K.P.; Haley, B.E. (Univ. of Kentucky, Lexington (USA)); Hanson, K.R.; McHale, N.A. (Connecticut Agricultural Experiment Station, New Haven, CT (USA))

    1990-05-01

    Phosphorylation of the 64 kilodalton stromal phosphoprotein by incubation of pea (Pisum sativum) chloroplast extracts with ({gamma}-{sup 32}P)ATP decreased in the presence of Glc-6-P and Glc-1,6-P{sub 2}, but was stimulated by glucose. Two-dimensional gel electrophoresis following incubation of intact chloroplasts and stromal extracts with ({gamma}-{sup 32}P)ATP, or incubation of stromal extracts and partially purified phosphoglucomutase (EC 2.7.5.1) with ({sup 32}P)Glc-1-P showed that the identical 64 kilodalton polypeptide was labeled. A 62 kilodalton polypeptide was phosphorylated by incubation of tobacco (Nicotiana sylvestris) stromal extracts with either ({gamma}-{sup 32}P)ATP or ({sup 32}P)Glc-1-P. In contrast, an analogous polypeptide was not phosphorylated in extracts from a tobacco mutant deficient in plastid phosphoglucomutase activity. The results indicate that the 64 (or 62) kilodalton chloroplast stromal phosphoprotein is phosphoglucomutase.

  6. The complete sequence of the chloroplast genome of the green microalga Lobosphaera (Parietochloris) incisa.

    Science.gov (United States)

    Tourasse, Nicolas J; Barbi, Tommaso; Waterhouse, Janet C; Shtaida, Nastassia; Leu, Stefan; Boussiba, Sammy; Purton, Saul; Vallon, Olivier

    2016-05-01

    We hereby report the complete chloroplast genome sequence of the green unicellular alga Lobosphaera (Parietochloris) incisa (strain SAG 2468). The genome consists of a circular chromosome of 156,028 bp, which is 72% A-T rich and does not contain a large rRNA-encoding inverted repeat. It is predicted to encode a total of 111 genes including 78 protein-coding, three rRNA, and 30 tRNA genes. The genome sequence also carries a self-splicing group I intron and a group II intron remnant. Overall, the gene and intron content of the L. incisa chloroplast genome is highly similar to that of other species of Trebouxiophyceae. In contrast, the L. incisa chloroplast genome harbors 88 copies of various intergenic dispersed DNA repeat sequences that are all unique to L. incisa. PMID:25423517

  7. Evolution from the prokaryotic to the higher plant chloroplast signal recognition particle

    DEFF Research Database (Denmark)

    Träger, Chantal; Rosenblad, Magnus Alm; Ziehe, Dominik;

    2012-01-01

    the conserved SRP54 and the SRP receptor, FtsY, are present in higher plant chloroplasts. In this study, we analyzed the phylogenetic distribution of SRP components in photosynthetic organisms to elucidate the evolution of the SRP system. We identified conserved plastid SRP RNAs within all...... data lead to the view that the P. patens cpSRP system occupies an intermediate position in the evolution from bacterial-type SRP to higher plant-type cpSRP system.......The protein targeting signal recognition particle (SRP) pathway in chloroplasts of higher plants has undergone dramatic evolutionary changes. It disposed of its RNA, which is an essential SRP component in bacteria, and uses a unique chloroplast-specific protein cpSRP43. Nevertheless, homologs of...

  8. Phylogenomic analysis of transcriptomic sequences of mitochondria and chloroplasts of essential brown algae (Phaeophyceae) in China

    Institute of Scientific and Technical Information of China (English)

    JIA Shangang; LIU Tao; WU Shuangxiu; WANG Xumin; LI Tianyong; QIAN Hao; SUN Jing; WANG Liang; YU Jun; REN Lufeng; YIN Jinlong

    2014-01-01

    The chloroplast and mitochondrion of brown algae (Class Phaeophyceae of Phylum Ochrophyta) may have originated from different endosymbiosis. In this study, we carried out phylogenomic analysis to distinguish their evolutionary lineages by using algal RNA-seq datasets of the 1 000 Plants (1KP) Project and publicly available complete genomes of mitochondria and chloroplasts of Kingdom Chromista. We have found that there is a split between Class Phaeophyceae of Phylum Ochrophyta and the others (Phylum Cryptophyta and Haptophyta) in Kingdom Chromista, and identified more diversity in chloroplast genes than mitochondrial ones in their phylogenetic trees. Taxonomy resolution for Class Phaeophyceae showed that it was divided into Laminariales-Ectocarpales clade and Fucales clade, and phylogenetic positions of Kjellmaniella crassi-folia, Hizikia fusifrome and Ishige okamurai were confirmed. Our analysis provided the basic phylogenetic relationships of Chromista algae, and demonstrated their potential ability to study endosymbiotic events.

  9. Optimization of poly(vinylidene fluoride-trifluoroethylene) films as non-volatile memory for flexible electronics

    KAUST Repository

    Mao, Duo

    2010-05-01

    The impact of thermal treatment and thickness on the polarization and leakage current of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer thin film capacitors has been studied. The evolution of the film morphology, crystallinity and bonding orientation as a function of annealing temperature and thickness were characterized using multiple techniques. Electrical performance of the devices was correlated with the material properties. It was found that annealing at or slightly above the Curie temperature (Tc) is the optimal temperature for high polarization, smooth surface morphology and low leakage current. Higher annealing temperature (but below the melting temperature Tm) favors larger size β crystallites through molecular chain self-organization, resulting in increased film roughness, and the vertical polarization tends to saturate. Metal-Ferroelectric-Metal (MFM) capacitors consistently achieved Ps, Pr and Vc of 8.5 μC/cm2, 7.4 μC/cm2 and 10.2 V, respectively.

  10. Band-Like Electron Transport in Organic Transistors and Implication of the Molecular Structure for Performance Optimization

    OpenAIRE

    Minder, Nikolas A.; Ono, Shimpei; Chen, Zhihua; Facchetti, Antonio; Morpurgo, Alberto F.

    2012-01-01

    Single-crystal organic field-effect transistors (OFETs) based on p-channel molecular semiconductors have led to breakthrough carrier mobilities and to the observation of band-like transport. These results represent the limit in our quest for the ultimate OFET performance. However, band-like transport has not been reported for n-channel OFETs and, for p-channel transistors, it is not understood why it occurs only for certain molecular materials. Here we report band-like electron transport for ...

  11. Structure-property optimizations in donor polymers via electronics, substituents, and side chains toward high efficiency solar cells.

    Science.gov (United States)

    Uy, Rycel L; Price, Samuel C; You, Wei

    2012-07-26

    Many advances in organic photovoltaic efficiency are not yet fully understood and new insight into structure-property relationships is required to push this technology into broad commercial use. The aim of this article is not to comprehensively review recent work, but to provide commentary on recent successes and forecast where researchers should look to enhance the efficiency of photovoltaics. By lowering the LUMO level, utilizing electron-withdrawing substituents advantageously, and employing appropriate side chains on donor polymers, researchers can elucidate further aspects of polymer-PCBM interactions while ultimately developing materials that will push past 10% efficiency. PMID:22588903

  12. Slugs' last meals: molecular identification of sequestered chloroplasts from different algal origins in Sacoglossa (Opisthobranchia, Gastropoda).

    Science.gov (United States)

    Händeler, Katharina; Wägele, Heike; Wahrmund, Ute; Rüdinger, Mareike; Knoop, Volker

    2010-11-01

    Some sacoglossan sea slugs have become famous for their unique capability to extract and incorporate functional chloroplasts from algal food organisms (mainly Ulvophyceae) into their gut cells. The functional incorporation of the so-called kleptoplasts allows the slugs to rely on photosynthetic products for weeks to months, enabling them to survive long periods of food shortage over most of their life-span. The algal food spectrum providing kleptoplasts as temporary, non-inherited endosymbionts appears to vary among sacoglossan slugs, but detailed knowledge is sketchy or unavailable. Accurate identification of algal donor species, which provide the chloroplasts for long-term retention is of primary importance to elucidate the biochemical mechanisms allowing long-term functionality of the captured chloroplast in the foreign animal cell environment. Whereas some sacoglossans forage on a variety of algal species, (e.g. Elysia crispata and E. viridis) others are more selective. Hence, characterizing the range of functional sacoglossan-chloroplast associations in nature is a prerequisite to understand the basis of this enigmatic endosymbiosis. Here, we present a suitable chloroplast gene (tufA) as a marker, which allows identification of the respective algal kleptoplast donor taxa by analysing DNA from whole animals. This novel approach allows identification of donor algae on genus or even species level, thus providing evidence for the taxonomic range of food organisms. We report molecular evidence that chloroplasts from different algal sources are simultaneously incorporated in some species of Elysia. NeigborNet analyses for species assignments are preferred over tree reconstruction methods because the former allow more reliable statements on species identification via barcoding, or rather visualize alternative allocations not to be seen in the latter. PMID:21565106

  13. Photoregulation of fructose and glucose respiration in the intact chloroplasts of Chlamydomonas reinhardtii F-60 and spinach

    International Nuclear Information System (INIS)

    The photoregulation of chloroplastic respiration was studied by monitoring in darkness and in light the release of 14CO2 from whole chloroplasts of Chlamydomonas reinhardtii F-60 and spinach (Spinacia oleracea L.) supplied externally with [14C]glucose and [14C]fructose, respectively. CO2 release was inhibited more than 90% in both chloroplasts by a light intensity of 4 W m-2. Oxidants, oxaloacetate in Chlamydomonas, nitrite in spinach, and phenazine methosulfate in both chloroplasts, reversed the inhibition. The onset of the photoinhibitory effect on CO2 release was relatively rapid compared to the restoration of CO2 release following illumination. In both darkened chloroplasts, dithiothreitol inhibited release. Of the four enzymes (fructokinase, phosphoglucose isomerase, glucose-6-P dehydrogenase, and gluconate-6-P dehydrogenase) in the pathway catalyzing the release of CO2 from fructose, only glucose-6-P dehydrogenase was deactivated by light and by dithiothreitol. 33 refs., 3 figs., 4 tabs

  14. Spectral characteristics and orientation of native forms of pigment in chloroplasts of barley seedlings under intermittent and continuous irradiation

    International Nuclear Information System (INIS)

    Chorophyll (Chl) form at 710-712 nm localized on the small protein simultaneously connected with the reaction centre of photosystem 1 (RC PS1) and the light-harvesting complex I (LHC-I) polypeptides is supposed to be the source of long-wavelength band of low-temperature fluorescence of chloroplasts at 735-740 nm. Chloroplasts of intermittently irradiated seedlings (or chloroplasts of the Chl b-less barley mutant) did not differ from chloroplasts of continuously irradiated seedlings (or chloroplasts of wild type barley) in the set of Chl a and beta-carotene forms and their orientation in the membrane. A competition for the newly synthesized Chl a molecules occurred between the RC PS 2 and LHC-II polypeptides

  15. Design and optimization of directly heated LaB6 cathode assemblies for electron-beam instruments

    International Nuclear Information System (INIS)

    A description is given of the design and testing of a directly heated, stable, electron source utilizing a single-crystal lanthanum hexaboride (LaB6) cathode. The emitter mounting fixture consists of an adjustable molybdenum base unit supported on gas-impervious alumina or machinable glass. Single-crystal cathode rods are securely clamped and positioned between vitreous carbon jaws that are resistively heated. The complete assembly is designed to be a direct ''plug-in'' substitute for the conventional tungsten thermionic filaments used in electron-beam instruments. The cathode current density for axial orientations is found to be ten times higher than that for orientations under equivalent conditions, a value of 50 A cm-2 being measured at 15000C with an observed lifetime in excess of 300 h. Optimum vacuum conditions for high lifetime and stable operation are in the range 1 x 10-6 Torr and lower. Comparison values for the emission at various temperatures from other borides, and tungsten, are also given

  16. Proton Gradients and Proton-Dependent Transport Processes in the Chloroplast

    OpenAIRE

    Höhner, Ricarda; Aboukila, Ali; Kunz, Hans-Henning; Venema, Kees

    2016-01-01

    Proton gradients are fundamental to chloroplast function. Across thylakoid membranes, the light induced -proton gradient is essential for ATP synthesis. As a result of proton pumping into the thylakoid lumen, an alkaline stromal pH develops, which is required for full activation of pH-dependent Calvin Benson cycle enzymes. This implies that a pH gradient between the cytosol (pH 7) and the stroma (pH 8) is established upon illumination. To maintain this pH gradient chloroplasts actively extrud...

  17. The complete chloroplast genome sequence of Tetrastigma hemsleyanum Diels at Gilg.

    Science.gov (United States)

    Li, Mengzhu; Chen, Qinyi; Yang, Bingxian; Ma, Ji; Li, Baoguo; Zhang, Lin

    2016-09-01

    The complete chloroplast genome sequence of Tetrastigma hemsleyanum Diels at Gilg, a critical Chinese medicine, is reported here. The complete chloroplast genome of Tetrastigma hemsleyanum Diels at Gilg is 159 914 bp in length with 37.55% overall GC content. A pair of IRs (inverted repeats) of 26 510 bp were separated by LSC (87 927 bp) and SSC (18 967 bp). The phylogenetic analysis of 40 taxa showed a strong sister relationship with all other rosids. However, the placement of Myrtales still needs further verification. PMID:26329851

  18. Evolutionary, Molecular and Genetic Analyses of Tic22 Homologues in Arabidopsis thaliana Chloroplasts

    OpenAIRE

    Kasmati, Ali Reza; Töpel, Mats; Khan, Nadir Zaman; Patel, Ramesh; Ling, Qihua; Karim, Sazzad; Aronsson, Henrik; Jarvis, Paul

    2013-01-01

    The Tic22 protein was previously identified in pea as a putative component of the chloroplast protein import apparatus. It is a peripheral protein of the inner envelope membrane, residing in the intermembrane space. In Arabidopsis, there are two Tic22 homologues, termed atTic22-III and atTic22-IV, both of which are predicted to localize in chloroplasts. These two proteins defined clades that are conserved in all land plants, which appear to have evolved at a similar rates since their separati...

  19. Noncoding RNA mediated traffic of foreign mRNA into chloroplasts reveals a novel signaling mechanism in plants.

    Directory of Open Access Journals (Sweden)

    Gustavo Gómez

    Full Text Available Communication between chloroplasts and the nucleus is one of the milestones of the evolution of plants on earth. Proteins encoded by ancestral chloroplast-endogenous genes were transferred to the nucleus during the endosymbiotic evolution and originated this communication, which is mainly dependent on specific transit-peptides. However, the identification of nuclear-encoded proteins targeted to the chloroplast lacking these canonical signals suggests the existence of an alternative cellular pathway tuning this metabolic crosstalk. Non-coding RNAS (NcRNAs are increasingly recognized as regulators of gene expression as they play roles previously believed to correspond to proteins. Avsunviroidae family viroids are the only noncoding functional RNAs that have been reported to traffic inside the chloroplasts. Elucidating mechanisms used by these pathogens to enter this organelle will unearth novel transport pathways in plant cells. Here we show that a viroid-derived NcRNA acting as a 5'UTR-end mediates the functional import of Green Fluorescent Protein (GFP mRNA into chloroplast. This claim is supported by the observation at confocal microscopy of a selective accumulation of GFP in the chloroplast of the leaves expressing the chimeric vd-5'UTR/GFP and by the detection of the GFP mRNA in chloroplasts isolated from cells expressing this construct. These results support the existence of an alternative signaling mechanism in plants between the host cell and chloroplasts, where an ncRNA functions as a key regulatory molecule to control the accumulation of nuclear-encoded proteins in this organelle. In addition, our findings provide a conceptual framework to develop new biotechnological tools in systems using plant chloroplast as bioreactors. Finally, viroids of the family Avsunviroidae have probably evolved to subvert this signaling mechanism to regulate their differential traffic into the chloroplast of infected cells.

  20. Electron Transfer Reactivity Patterns at Chemically Modified Electrodes: Fundamentals and Application to the Optimization of Redox Recycling Amplification Systems

    Energy Technology Data Exchange (ETDEWEB)

    Adam Johan Bergren

    2006-05-01

    Electroanalytical chemistry is often utilized in chemical analysis and Fundamental studies. Important advances have been made in these areas since the advent of chemically modified electrodes: the coating of an electrode with a chemical film in order to impart desirable, and ideally, predictable properties. These procedures enable the exploitation of unique reactivity patterns. This dissertation presents studies that investigate novel reaction mechanisms at self-assembled monolayers on gold. In particular, a unique electrochemical current amplification scheme is detailed that relies on a selective electrode to enable a reactivity pattern that results in regeneration of the analyte (redox recycling). This regenerating reaction can occur up to 250 times for each analyte molecule, leading to a notable enhancement in the observed current. The requirements of electrode selectivity and the resulting amplification and detection limit improvements are described with respect to the heterogeneous and homogeneous electron transfer rates that characterize the system. These studies revealed that the heterogeneous electrolysis of the analyte should ideally be electrochemically reversible, while that for the regenerating agent should be held to a low level. Moreover, the homogeneous reaction that recycles the analyte should occur at a rapid rate. The physical selectivity mechanism is also detailed with respect to the properties of the electrode and redox probes utilized. It is shown that partitioning of the analyte into/onto the adlayer leads to the extraordinary selectivity of the alkanethiolate monolayer modified electrode. Collectively, these studies enable a thorough understanding of the complex electrode mechanism required for successful redox recycling amplification systems, Finally, in a separate (but related) study, the effect of the akyl chain length on the heterogeneous electron transfer behavior of solution-based redox probes is reported, where an odd-even oscillation

  1. Electronic optimization for an energy harvesting system based on magnetoelectric Metglas/poly(vinylidene fluoride)/Metglas composites

    Science.gov (United States)

    Reis, S.; Silva, M. P.; Castro, N.; Correia, V.; Rocha, J. G.; Martins, P.; Lasheras, A.; Gutierrez, J.; Lanceros-Mendez, S.

    2016-08-01

    Harvesting magnetic energy from the environment is becoming increasingly attractive for being a renewable and inexhaustible power source, ubiquitous and accessible in remote locations. In particular, magnetic harvesting with polymer-based magnetoelectric (ME) materials meet the industry demands of being flexible, showing large area potential, lightweight and biocompatibility. In order to get the best energy harvesting process, the extraction circuit needs to be optimized in order to be useful for powering devices. This paper discusses the design and performance of five interface circuits, a full-wave bridge rectifier, two Cockcroft–Walton voltage multipliers (with 1 and 2 stages) and two Dickson voltage multipliers (with 2 and 3 stages), for the energy harvesting from a Fe61.6Co16.4Si10.8B11.2 (Metglas)/polyvinylidene fluoride/Metglas ME composite. Maximum power and power density values of 12 μW and 0.9 mW cm‑3 were obtained, respectively, with the Dickson voltage multiplier with two stages, for a load resistance of 180 kΩ, at 7 Oe DC magnetic field and a 54.5 kHz resonance frequency. Such performance is useful for microdevice applications in hard-to-reach locations and for traditional devices such as electric windows, door locking, and tire pressure monitoring.

  2. Electron-beam induced disorder effects in optimally doped Bi2Sr2CaCu2O8+x single crystal samples

    Science.gov (United States)

    Vobornik, I.; Berger, H.; Pavuna, D.; Margaritondo, G.; Forro, L.; Grioni, M.; Rullier-Albenque, F.; Onellion, M.; EPFL Collaboration; Laboratoire Des Solides Irradiés Collaboration

    2000-03-01

    We report on the effects of electron-beam induced disorder in optimally doped Bi2Sr2CaCu2O8+x single crystal samples, measured with angle-resolved photoemission. In the superconducting state, the disorder fills in the gap, without changing the binding energy or the width of the narrow coherent feature.[1] In the normal state, disorder leads to an anisotropic pseudogap in angle-resolved photoemission, with the largest pseudogap near the (0,p) point and no pseudogap in the direction.[2,3] We discuss implications of these data. 1. I. Vobornik et.al., Phys. Rev. Lett. 82 , 3128 (1999). 2. I. Vobornik, Ph.D. thesis, EPFL, Lausanne, Switzerland, October, 1999. 3. I. Vobornik et.al., unpublished.

  3. Optimizing electron-positron pair production on kilojoule-class high-intensity lasers for the purpose of pair-plasma creation

    Science.gov (United States)

    Myatt, J.; Delettrez, J. A.; Maximov, A. V.; Meyerhofer, D. D.; Short, R. W.; Stoeckl, C.; Storm, M.

    2009-06-01

    Expressions for the yield of electron-positron pairs, their energy spectra, and production rates have been obtained in the interaction of multi-kJ pulses of high-intensity laser light interacting with solid targets. The Bethe-Heitler conversion of hard x-ray bremsstrahlung [D. A. Gryaznykh, Y. Z. Kandiev, and V. A. Lykov, JETP Lett. 67, 257 (1998); K. Nakashima and H. Takabe, Phys. Plasmas 9, 1505 (2002)] is shown to dominate over direct production (trident process) [E. P. Liang, S. C. Wilks, and M. Tabak, Phys. Rev. Lett. 81, 4887 (1998)]. The yields and production rates have been optimized as a function of incident laser intensity by the choice of target material and dimensions, indicating that up to 5×1011 pairs can be produced on the OMEGA EP laser system [L. J. Waxer , Opt. Photonics News 16, 30 (2005)]. The corresponding production rates are high enough to make possible the creation of a pair plasma.

  4. Study of Dye-Sensitized Solar Cells by Scanning Electron Micrograph Observation and Thickness Optimization of Porous TiO2 Electrodes

    Directory of Open Access Journals (Sweden)

    Seigo Ito

    2009-01-01

    Full Text Available In order to improve the photoenergy conversion efficiency of dye-sensitized solar cells (DSCs, it is important to optimize their porous TiO2 electrodes. This paper examines the surface and cross-sectional views of the electrodes using scanning electron micrography. Two types of samples for cross-sectional viewing were prepared by mechanically breaking the substrate and by using an Ar-ion etching beam. The former displays the surface of the TiO2 particles and the latter shows the cross-section of the TiO2 particles. We found interesting surface and cross-sectional structures in the scattering layer containing the 400 nm diameter particles, which have an angular and horned shape. The influence of TiO2 particle size and the thickness of the nanocrystalline-TiO2 electrode in DSCs using four kinds of sensitizing dyes (D149, K19, N719 and Z907 and two kinds of electrolytes (acetonitrile-based and ionic-liquid electrolytes are discussed in regards to conversion efficiency, which this paper aims to optimize.

  5. Optimizing photon-pair generation electronically using a p-i-n diode incorporated in a silicon microring resonator

    Energy Technology Data Exchange (ETDEWEB)

    Savanier, Marc, E-mail: msavanier@eng.ucsd.edu; Kumar, Ranjeet; Mookherjea, Shayan, E-mail: smookherjea@eng.ucsd.edu [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States)

    2015-09-28

    Silicon photonic microchips may be useful for compact, inexpensive, room-temperature optically pumped photon-pair sources, which unlike conventional photon-pair generators based on crystals or optical fibers, can be manufactured using CMOS-compatible processes on silicon wafers. It has been shown that photon pairs can be created in simple structures such as microring resonators at a rate of a few hundred kilohertz using less than a milliwatt of optical pump power, based on the process of spontaneous four-wave mixing. To create a practical photon-pair source, however, also requires some way of monitoring the device and aligning the pump wavelength when the temperature varies, since silicon resonators are highly sensitive to temperature. In fact, monitoring photodiodes are standard components in classical laser diodes, but the incorporation of germanium or InGaAs photodiodes would raise the cost and fabrication complexity. Here, we present a simple and effective all-electronic technique for finding the optimum operating point for the microring used to generate photon pairs, based on measuring the reverse-biased current in a silicon p-i-n junction diode fabricated across the waveguide that constitutes the silicon microring. We show that by monitoring the current, and using it to tune the pump laser wavelength, the photon-pair generation properties of the microring can be preserved over a temperature range of more than 30 °C.

  6. Function of the chloroplast hydrogenase in the microalga Chlamydomonas: the role of hydrogenase and state transitions during photosynthetic activation in anaerobiosis.

    Directory of Open Access Journals (Sweden)

    Bart Ghysels

    Full Text Available Like a majority of photosynthetic microorganisms, the green unicellular alga Chlamydomonas reinhardtii may encounter O2 deprived conditions on a regular basis. In response to anaerobiosis or in a respiration defective context, the photosynthetic electron transport chain of Chlamydomonas is remodeled by a state transition process to a conformation that favours the photoproduction of ATP at the expense of reductant synthesis. In some unicellular green algae including Chlamydomonas, anoxia also triggers the induction of a chloroplast-located, oxygen sensitive hydrogenase, which accepts electrons from reduced ferredoxin to convert protons into molecular hydrogen. Although microalgal hydrogen evolution has received much interest for its biotechnological potential, its physiological role remains unclear. By using specific Chlamydomonas mutants, we demonstrate that the state transition ability and the hydrogenase function are both critical for induction of photosynthesis in anoxia. These two processes are thus important for survival of the cells when they are transiently placed in an anaerobic environment.

  7. Function of the chloroplast hydrogenase in the microalga Chlamydomonas: the role of hydrogenase and state transitions during photosynthetic activation in anaerobiosis.

    Science.gov (United States)

    Ghysels, Bart; Godaux, Damien; Matagne, René F; Cardol, Pierre; Franck, Fabrice

    2013-01-01

    Like a majority of photosynthetic microorganisms, the green unicellular alga Chlamydomonas reinhardtii may encounter O2 deprived conditions on a regular basis. In response to anaerobiosis or in a respiration defective context, the photosynthetic electron transport chain of Chlamydomonas is remodeled by a state transition process to a conformation that favours the photoproduction of ATP at the expense of reductant synthesis. In some unicellular green algae including Chlamydomonas, anoxia also triggers the induction of a chloroplast-located, oxygen sensitive hydrogenase, which accepts electrons from reduced ferredoxin to convert protons into molecular hydrogen. Although microalgal hydrogen evolution has received much interest for its biotechnological potential, its physiological role remains unclear. By using specific Chlamydomonas mutants, we demonstrate that the state transition ability and the hydrogenase function are both critical for induction of photosynthesis in anoxia. These two processes are thus important for survival of the cells when they are transiently placed in an anaerobic environment. PMID:23717558

  8. A chloroplast genealogy of hordeum (poaceae): Long-term persisting haplotypes, incomplete lineage sorting, regional extinction, and the consequences for phylogenetic inference.

    Science.gov (United States)

    Jakob, Sabine S; Blattner, Frank R

    2006-08-01

    To analyze reasons for inconclusive results of earlier chloroplast phylogenies in the grass genus Hordeum, we established a genealogy of chloroplast haplotypes by sequencing the trnL-trnF region in 875 individuals, covering all 31 species of the genus. Although the outcomes of phenetic and parsimony analyses of 88 haplotypes were ambiguous, a network approach showed that in Hordeum ancient chloroplast types co-occur with their descendants. Moreover, we found up to 18 different chloroplast haplotypes within a single species and up to 6 species sharing single haplotypes. Persisting polymorphisms together with incomplete lineage sorting occurred preferentially in the rapidly speciating New World taxa of the genus, where ancient chloroplast types have survived for at least 4 Myr. Lineages-through-time plots and a high number of missing chloroplast haplotypes indicated far-reaching extinction of chloroplast lineages in Europe and particularly the Mediterranean. Survival of these lineages in East Asia and North America resulted in chloroplast relationships that markedly differed from nuclear estimations of species relationships. Thus, even for the deepest splits in the genus, reaching back more than 9 Myr, no safe phylogenetic inference from chloroplast data is possible in Hordeum. The chloroplast genealogy, however, revealed biogeographic patterns and indicated processes involved in speciation in Hordeum. We conclude that the described phenomena are not restricted to Hordeum and that the knowledge of the chloroplast relationships within a genus is indispensable to prevent misinterpretation of phylogeographic data within single species. PMID:16754643

  9. Growth optimization and characterization of high mobility two-dimensional electron systems in AlAs quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Dasgupta, Shivaji

    2009-02-15

    In this work two-dimensional electron systems (2DESs) based on AlAs/AlGaAs heterostructures doped with Si are investigated. The electrons are confined in AlAs quantum wells (QWs) sandwiched between AlGaAs buffers. Analytical calculations and simulations for AlAs QWs are presented in the first chapter. The results show a cross-over width, above which the wide (001)-oriented QWs show double valley occupancy and wide (110)-oriented QWs show single valley occupancy. We solve the Schroedinger equation analytically for anisotropic masses. The solution shows the orientation dependence of the elliptical cyclotron orbit due to the anisotropic mass. We also present an introduction to the Landau level crossings based on g{sup *}m{sup *} product. In the next chapter, we present experimental results for the double-valley (001)-oriented AlAs QWs. We present the different structures of the deep AlAs QWs along with the low temperature magnetotransport data for these QWs. Thereafter, we present the results on shallow AlAs QWs. We achieved a mobility of 4.2 x 10{sup 5} cm{sup 2}/Vs at 330 mK for the deep backside doped AlAs QW. For the shallow QWs, we achieved a mobility of2.3 x 10{sup 5} cm{sup 2}/Vs at 330 mK, for a density of 2.9 x 10{sup 11} cm{sup -2}. From the magneto-transport data, we see evidence of the double-valley occupation for the (001)-oriented AlAs wide QWs. In the next chapter, we present experimental results for the single-valley (110)-oriented AlAs QWs. We deduced the donor binding energy and the doping efficiency for this facet from a doping series of double-sided doped QWs. Thereafter, we designed different structures for the (110)-oriented AlAs QWs, which we present along with their respective low temperature magneto-transport data. We measured one of the double-sided doped AlAs QWs at very high magnetic fields and low temperatures, down to 60 mK. At the end of the chapter, we present a spike feature observed in the magneto-transport data of these QWs. This

  10. Role of membrane glycerolipids in photosynthesis, thylakoid biogenesis and chloroplast development.

    Science.gov (United States)

    Kobayashi, Koichi

    2016-07-01

    The lipid bilayer of the thylakoid membrane in plant chloroplasts and cyanobacterial cells is predominantly composed of four unique lipid classes; monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulfoquinovosyldiacylglycerol (SQDG) and phosphatidylglycerol (PG). MGDG and DGDG are uncharged galactolipids that constitute the bulk of thylakoid membrane lipids and provide a lipid bilayer matrix for photosynthetic complexes as the main constituents. The glycolipid SQDG and phospholipid PG are anionic lipids with a negative charge on their head groups. SQDG and PG substitute for each other to maintain the amount of total anionic lipids in the thylakoid membrane, with PG having indispensable functions in photosynthesis. In addition to biochemical studies, extensive analyses of mutants deficient in thylakoid lipids have revealed important roles of these lipids in photosynthesis and thylakoid membrane biogenesis. Moreover, recent studies of Arabidopsis thaliana suggest that thylakoid lipid biosynthesis triggers the expression of photosynthesis-associated genes in both the nucleus and plastids and activates the formation of photosynthetic machineries and chloroplast development. Meanwhile, galactolipid biosynthesis is regulated in response to chloroplast functionality and lipid metabolism at transcriptional and post-translational levels. This review summarizes the roles of thylakoid lipids with their biosynthetic pathways in plants and discusses the coordinated regulation of thylakoid lipid biosynthesis with the development of photosynthetic machinery during chloroplast biogenesis. PMID:27114097

  11. Cowpea chloroplastic ATP synthase is the source of multiple plant defense elicitors during insect herbivory

    Science.gov (United States)

    Plant responses to damage vary dependant upon the nature of the biotic and abiotic stresses. We recently described an elicitor, from Fall armyworm (Spodoptera frugiperda) oral secretions (OS) termed inceptin, derived from chloroplastic ATP synthase '-subunit (cATPC) proteins that activate phytohormo...

  12. Chloroplast evolution in the Pinus montezumae complex: a coalescent approach to hybridization.

    Science.gov (United States)

    Matos, J A; Schaal, B A

    2000-08-01

    This study addresses the evolutionary history of the chloroplast genomes of two closely related pine species, Pinus hartwegii Lindl. and P. montezumae Lamb (subsect. Ponderosae) using coalescent theory and some of the statistical tools that have been developed from it during the past two decades. Pinus hartwegii and P. montezumae are closely related species in the P. montezumae complex (subsect. Ponderosae) of Mexico and Central America. Pinus hartwegii is a high elevation species, whereas P. montezumae occurs at lower elevations. The two species occur on many of the same mountains throughout Mexico. A total of 350 individuals of P. hartwegii and P. montezumae were collected from Nevado de Colima (Jalisco), Cerro Potosí (Nuevo León), Iztaccihuatl/Popocatepetl (México), and Nevado de Toluca (México). The chloroplast genome of P. hartwegii and P. montezumae was mapped using eight restriction enzymes. Fifty-one different haplotypes were characterized; 38 of 160 restriction sites were polymorphic. Clades of most parsimoniously related chloroplast haplotypes are geographically localized and do not overlap in distribution, and the geographically localized clades of haplotypes include both P. hartwegii and P. montezumae. Some haplotypes in the clades occur in only one of the two species, whereas other haplotypes occur in both species. These data strongly suggest ancient and/or ongoing hybridization between P. hartwegii and P. montezumae and a shared chloroplast genome history within geographic regions of Mexico. PMID:11005290

  13. Energetic cost of protein import across the envelope membranes of chloroplasts.

    Science.gov (United States)

    Shi, Lan-Xin; Theg, Steven M

    2013-01-15

    Chloroplasts are the organelles of green plants in which light energy is transduced into chemical energy, forming ATP and reduced carbon compounds upon which all life depends. The expenditure of this energy is one of the central issues of cellular metabolism. Chloroplasts contain ~3,000 proteins, among which less than 100 are typically encoded in the plastid genome. The rest are encoded in the nuclear genome, synthesized in the cytosol, and posttranslationally imported into the organelle in an energy-dependent process. We report here a measurement of the amount of ATP hydrolyzed to import a protein across the chloroplast envelope membranes--only the second complete accounting of the cost in Gibbs free energy of protein transport to be undertaken. Using two different precursors prepared by three distinct techniques, we show that the import of a precursor protein into chloroplasts is accompanied by the hydrolysis of ~650 ATP molecules. This translates to a ΔG(protein) (transport) of some 27,300 kJ/mol protein imported. We estimate that protein import across the plastid envelope membranes consumes ~0.6% of the total light-saturated energy output of the organelle. PMID:23277572

  14. Expression patterns of cotton chloroplast genes during development: implications for development of plastid transformation vectors

    Science.gov (United States)

    In order to express genes of interest in plastids, transformation vectors must be developed that include appropriate promoters to drive expression at effective levels in both green and non-green tissues. Typically, chloroplasts are transformed with vectors that contain ribosomal RNA promoters for h...

  15. A tiling microarray for global analysis of chloroplast genome expression in cucumber and other plants

    Directory of Open Access Journals (Sweden)

    Pląder Wojciech

    2011-09-01

    Full Text Available Abstract Plastids are small organelles equipped with their own genomes (plastomes. Although these organelles are involved in numerous plant metabolic pathways, current knowledge about the transcriptional activity of plastomes is limited. To solve this problem, we constructed a plastid tiling microarray (PlasTi-microarray consisting of 1629 oligonucleotide probes. The oligonucleotides were designed based on the cucumber chloroplast genomic sequence and targeted both strands of the plastome in a non-contiguous arrangement. Up to 4 specific probes were designed for each gene/exon, and the intergenic regions were covered regularly, with 70-nt intervals. We also developed a protocol for direct chemical labeling and hybridization of as little as 2 micrograms of chloroplast RNA. We used this protocol for profiling the expression of the cucumber chloroplast plastome on the PlasTi-microarray. Owing to the high sequence similarity of plant plastomes, the newly constructed microarray can be used to study plants other than cucumber. Comparative hybridization of chloroplast transcriptomes from cucumber, Arabidopsis, tomato and spinach showed that the PlasTi-microarray is highly versatile.

  16. Chloroplast DNA variation of oaks in western Central Europe and genetic consequences of human influences

    NARCIS (Netherlands)

    König, A.O.; Ziegenhagen, B.; Dam, van B.C.; Csaikl, U.M.; Coart, E.; Degen, B.; Burg, K.; Vries, de S.M.G.; Petit, R.J.

    2002-01-01

    Oak chloroplast DNA (cpDNA) variation was studied in a grid-based inventory in western Central Europe, including Belgium, The Netherlands, Luxembourg, Germany, the Czech Republic, and the northern parts of Upper and Lower Austria. A total of 2155 trees representing 426 populations of Quercus robur L

  17. Ion Channels in Plant Bioenergetic Organelles, Chloroplasts and Mitochondria: From Molecular Identification to Function.

    Science.gov (United States)

    Carraretto, Luca; Teardo, Enrico; Checchetto, Vanessa; Finazzi, Giovanni; Uozumi, Nobuyuki; Szabo, Ildiko

    2016-03-01

    Recent technical advances in electrophysiological measurements, organelle-targeted fluorescence imaging, and organelle proteomics have pushed the research of ion transport a step forward in the case of the plant bioenergetic organelles, chloroplasts and mitochondria, leading to the molecular identification and functional characterization of several ion transport systems in recent years. Here we focus on channels that mediate relatively high-rate ion and water flux and summarize the current knowledge in this field, focusing on targeting mechanisms, proteomics, electrophysiology, and physiological function. In addition, since chloroplasts evolved from a cyanobacterial ancestor, we give an overview of the information available about cyanobacterial ion channels and discuss the evolutionary origin of chloroplast channels. The recent molecular identification of some of these ion channels allowed their physiological functions to be studied using genetically modified Arabidopsis plants and cyanobacteria. The view is emerging that alteration of chloroplast and mitochondrial ion homeostasis leads to organelle dysfunction, which in turn significantly affects the energy metabolism of the whole organism. Clear-cut identification of genes encoding for channels in these organelles, however, remains a major challenge in this rapidly developing field. Multiple strategies including bioinformatics, cell biology, electrophysiology, use of organelle-targeted ion-sensitive probes, genetics, and identification of signals eliciting specific ion fluxes across organelle membranes should provide a better understanding of the physiological role of organellar channels and their contribution to signaling pathways in plants in the future. PMID:26751960

  18. Chloroplast β chaperonins from A. thaliana function with endogenous cpn10 homologs in vitro.

    Science.gov (United States)

    Vitlin, Anna; Weiss, Celeste; Demishtein-Zohary, Keren; Rasouly, Aviram; Levin, Doron; Pisanty-Farchi, Odelia; Breiman, Adina; Azem, Abdussalam

    2011-09-01

    The involvement of type I chaperonins in bacterial and organellar protein folding has been well-documented. In E. coli and mitochondria, these ubiquitous and highly conserved proteins form chaperonin oligomers of identical 60 kDa subunits (cpn60), while in chloroplasts, two distinct cpn60 α and β subunit types co-exist together. The primary sequence of α and β subunits is ~50% identical, similar to their respective homologies to the bacterial GroEL. Moreover, the A. thaliana genome contains two α and four β genes. The functional significance of this variability in plant chaperonin proteins has not yet been elucidated. In order to gain insight into the functional variety of the chloroplast chaperonin family members, we reconstituted β homo-oligomers from A. thaliana following their expression in bacteria and subjected them to a structure-function analysis. Our results show for the first time, that A. thaliana β homo-oligomers can function in vitro with authentic chloroplast co-chaperonins (ch-cpn10 and ch-cpn20). We also show that oligomers made up of different β subunit types have unique properties and different preferences for co-chaperonin partners. We propose that chloroplasts may contain active β homo-oligomers in addition to hetero-oligomers, possibly reflecting a variety of cellular roles. PMID:21633907

  19. The complete chloroplast genome sequence of Ledebouriella seseloides (Hoffm.) H. Wolff.

    Science.gov (United States)

    Lee, Hyun Oh; Kim, Kyunghee; Lee, Sang-Choon; Lee, Junki; Lee, Jonghoon; Kim, Soonok; Yang, Tae-Jin

    2016-09-01

    Ledebouriella seseloides (Hoffm.) H.Wolff is a traditional medicinal herb belonging to Apiaceae family, whose dried roots and rhizomes have been used as traditional medicine in East Asian countries. The complete chloroplast genome of L. seseloides was obtained by de novo assembly using the small amount of whole genome sequencing data. The chloroplast genome of L. seseloides was 147 880 bp in length, which consisted of large single copy region (93 222 bp), small single copy region (17 324 bp), and a pair of inverted repeat regions (18 667 bp). The overall GC contents of the chloroplast genome were 37.5%. A total of 113 genes were annotated, which included 79 protein-coding genes, 30 tRNA genes, and four rRNA genes. Phylogenetic analysis with the reported chloroplast genomes revealed that L. seseloides is most closely related to Petroselinum crispum (parsley), an herb widely used in cooking. PMID:26218226

  20. Heterologous nuclear and chloroplast microsatellite amplification and variation in tea, Camellia sinensis.

    Science.gov (United States)

    Kaundun, Shiv Shankhar; Matsumoto, Satoru

    2002-12-01

    The advantage of the cross transferability of heterologous chloroplast and nuclear microsatellite primers was taken to detect polymorphism among 24 tea (Camellia sinensis (L.) O. Kuntze) genotypes, including both the assamica and the sinensis varieties. Primer information was obtained from the closely related Camellia japonica species for four nuclear microsatellites, and from Nicotiana tabaccum for seven universal chloroplast microsatellites. All of the nuclear microsatellite loci tested generated an expected DNA fragment in tea, revealing between three and five alleles per locus. Four out of the seven chloroplast microsatellites primers amplified positively, and of these only one was polymorphic with three alleles, which is in agreement with the conserved nature of chloroplast microsatellites at the intraspecific level. A factorial correspondence analysis carried out on all genotypes and nuclear microsatellite alleles separated the assamica and sinensis genotypes into two groups, thus demonstrating the value of these markers in establishing the genetic relationship between tea varieties. Genetic diversity measured with nuclear microsatellites was higher than that measured with other types of molecular markers, offering prospects for their use in fingerprinting, mapping, and population genetic studies, whereas polymorphisms detected at a cpSSR locus will allow the determination of plastid inheritance in the species. PMID:12502248