Science.gov

Sample records for arabidopsis sieve elements

  1. Live Imaging of Companion Cells and Sieve Elements in Arabidopsis Leaves

    PubMed Central

    Cayla, Thibaud; Batailler, Brigitte; Le Hir, Rozenn; Revers, Frédéric; Anstead, James A.; Thompson, Gary A.; Grandjean, Olivier; Dinant, Sylvie

    2015-01-01

    The phloem is a complex tissue composed of highly specialized cells with unique subcellular structures and a compact organization that is challenging to study in vivo at cellular resolution. We used confocal scanning laser microscopy and subcellular fluorescent markers in companion cells and sieve elements, for live imaging of the phloem in Arabidopsis leaves. This approach provided a simple framework for identifying phloem cell types unambiguously. It highlighted the compactness of the meshed network of organelles within companion cells. By contrast, within the sieve elements, unknown bodies were observed in association with the PP2-A1:GFP, GFP:RTM1 and RTM2:GFP markers at the cell periphery. The phloem lectin PP2-A1:GFP marker was found in the parietal ground matrix. Its location differed from that of the P-protein filaments, which were visualized with SEOR1:GFP and SEOR2:GFP. PP2-A1:GFP surrounded two types of bodies, one of which was identified as mitochondria. This location suggested that it was embedded within the sieve element clamps, specific structures that may fix the organelles to each another or to the plasma membrane in the sieve tubes. GFP:RTM1 was associated with a class of larger bodies, potentially corresponding to plastids. PP2-A1:GFP was soluble in the cytosol of immature sieve elements. The changes in its subcellular localization during differentiation provide an in vivo blueprint for monitoring this process. The subcellular features obtained with these companion cell and sieve element markers can be used as landmarks for exploring the organization and dynamics of phloem cells in vivo. PMID:25714357

  2. Vascular Cell Induction Culture System Using Arabidopsis Leaves (VISUAL) Reveals the Sequential Differentiation of Sieve Element-Like Cells.

    PubMed

    Kondo, Yuki; Nurani, Alif Meem; Saito, Chieko; Ichihashi, Yasunori; Saito, Masato; Yamazaki, Kyoko; Mitsuda, Nobutaka; Ohme-Takagi, Masaru; Fukuda, Hiroo

    2016-06-01

    Cell differentiation is a complex process involving multiple steps, from initial cell fate specification to final differentiation. Procambial/cambial cells, which act as vascular stem cells, differentiate into both xylem and phloem cells during vascular development. Recent studies have identified regulatory cascades for xylem differentiation. However, the molecular mechanism underlying phloem differentiation is largely unexplored due to technical challenges. Here, we established an ectopic induction system for phloem differentiation named Vascular Cell Induction Culture System Using Arabidopsis Leaves (VISUAL). Our results verified similarities between VISUAL-induced Arabidopsis thaliana phloem cells and in vivo sieve elements. We performed network analysis using transcriptome data with VISUAL to dissect the processes underlying phloem differentiation, eventually identifying a factor involved in the regulation of the master transcription factor gene APL Thus, our culture system opens up new avenues not only for genetic studies of phloem differentiation, but also for future investigations of multidirectional differentiation from vascular stem cells. PMID:27194709

  3. A Plasma Membrane-Anchored Fluorescent Protein Fusion Illuminates Sieve Element Plasma Membranes in Arabidopsis and Tobacco1[W][OA

    PubMed Central

    Thompson, Matthew V.; Wolniak, Stephen M.

    2008-01-01

    Rapid acquisition of quantitative anatomical data from the sieve tubes of angiosperm phloem has been confounded by their small size, their distance from organ surfaces, and the time-consuming nature of traditional methods, such as transmission electron microscopy. To improve access to these cells, for which good anatomical data are critical, a monomeric yellow fluorescent protein (mCitrine) was N-terminally fused to a small (approximately 6 kD) membrane protein (AtRCI2A) and stably expressed in Arabidopsis thaliana (Columbia-0 ecotype) and Nicotiana tabacum (‘Samsun’) under the control of a companion cell-specific promoter (AtSUC2p). The construct, called by its abbreviation SUmCR, yielded stable sieve element (SE) plasma membrane fluorescence labeling, even after plastic (methacrylate) embedding. In conjunction with wide-field fluorescence measurements of sieve pore number and position using aniline blue-stained callose, mCitrine-labeled material was used to calculate rough estimates of sieve tube-specific conductivity for both species. The SUmCR construct also revealed a hitherto unknown expression domain of the AtSUC2 Suc-H+ symporter in the epidermis of the cell division zone of developing root tips. The success of this construct in targeting plasma membrane-anchored fluorescent proteins to SEs could be attributable to the small size of AtRCI2A or to the presence of other signals innate to AtRCI2A that permit the protein to be trafficked to SEs. The construct provides a hitherto unique entrée into companion cell-to-SE protein targeting, as well as a new tool for studying whole-plant phloem anatomy and architecture. PMID:18223149

  4. P-proteins in Arabidopsis are heteromeric structures involved in rapid sieve tube sealing

    PubMed Central

    Jekat, Stephan B.; Ernst, Antonia M.; von Bohl, Andreas; Zielonka, Sascia; Twyman, Richard M.; Noll, Gundula A.; Prüfer, Dirk

    2013-01-01

    Structural phloem proteins (P-proteins) are characteristic components of the sieve elements in all dicotyledonous and many monocotyledonous angiosperms. Tobacco P-proteins were recently confirmed to be encoded by the widespread sieve element occlusion (SEO) gene family, and tobacco SEO proteins were shown to be directly involved in sieve tube sealing thus preventing the loss of photosynthate. Analysis of the two Arabidopsis SEO proteins (AtSEOa and AtSEOb) indicated that the corresponding P-protein subunits do not act in a redundant manner. However, there are still pending questions regarding the interaction properties and specific functions of AtSEOa and AtSEOb as well as the general function of structural P-proteins in Arabidopsis. In this study, we characterized the Arabidopsis P-proteins in more detail. We used in planta bimolecular fluorescence complementation assays to confirm the predicted heteromeric interactions between AtSEOa and AtSEOb. Arabidopsis mutants depleted for one or both AtSEO proteins lacked the typical P-protein structures normally found in sieve elements, underlining the identity of AtSEO proteins as P-proteins and furthermore providing the means to determine the role of Arabidopsis P-proteins in sieve tube sealing. We therefore developed an assay based on phloem exudation. Mutants with reduced AtSEO expression levels lost twice as much photosynthate following injury as comparable wild-type plants, confirming that Arabidopsis P-proteins are indeed involved in sieve tube sealing. PMID:23840197

  5. SUT2, a Putative Sucrose Sensor in Sieve Elements

    PubMed Central

    Barker, Laurence; Kühn, Christina; Weise, Andreas; Schulz, Alexander; Gebhardt, Christiane; Hirner, Brigitte; Hellmann, Hanjo; Schulze, Waltraud; Ward, John M.; Frommer, Wolf B.

    2000-01-01

    In leaves, sucrose uptake kinetics involve high- and low-affinity components. A family of low- and high-affinity sucrose transporters (SUT) was identified. SUT1 serves as a high-affinity transporter essential for phloem loading and long-distance transport in solanaceous species. SUT4 is a low-affinity transporter with an expression pattern overlapping that of SUT1. Both SUT1 and SUT4 localize to enucleate sieve elements of tomato. New sucrose transporter–like proteins, named SUT2, from tomato and Arabidopsis contain extended cytoplasmic domains, thus structurally resembling the yeast sugar sensors SNF3 and RGT2. Features common to these sensors are low codon bias, environment of the start codon, low expression, and lack of detectable transport activity. In contrast to LeSUT1, which is induced during the sink-to-source transition of leaves, SUT2 is more highly expressed in sink than in source leaves and is inducible by sucrose. LeSUT2 protein colocalizes with the low- and high-affinity sucrose transporters in sieve elements of tomato petioles, indicating that multiple SUT mRNAs or proteins travel from companion cells to enucleate sieve elements. The SUT2 gene maps on chromosome V of potato and is linked to a major quantitative trait locus for tuber starch content and yield. Thus, the putative sugar sensor identified colocalizes with two other sucrose transporters, differs from them in kinetic properties, and potentially regulates the relative activity of low- and high-affinity sucrose transport into sieve elements. PMID:10899981

  6. SEORious business: structural proteins in sieve tubes and their involvement in sieve element occlusion.

    PubMed

    Knoblauch, Michael; Froelich, Daniel R; Pickard, William F; Peters, Winfried S

    2014-04-01

    The phloem provides a network of sieve tubes for long-distance translocation of photosynthates. For over a century, structural proteins in sieve tubes have presented a conundrum since they presumably increase the hydraulic resistance of the tubes while no potential function other than sieve tube or wound sealing in the case of injury has been suggested. Here we summarize and critically evaluate current speculations regarding the roles of these proteins. Our understanding suffers from the suggestive power of images; what looks like a sieve tube plug on micrographs may not actually impede translocation very much. Recent reports of an involvement of SEOR (sieve element occlusion-related) proteins, a class of P-proteins, in the sealing of injured sieve tubes are inconclusive; various lines of evidence suggest that, in neither intact nor injured plants, are SEORs determinative of translocation stoppage. Similarly, the popular notion that P-proteins serve in the defence against phloem sap-feeding insects is unsupported by empirical facts; it is conceivable that in functional sieve tubes, aphids actually could benefit from inducing a plug. The idea that rising cytosolic Ca(2+) generally triggers sieve tube blockage by P-proteins appears widely accepted, despite lacking experimental support. Even in forisomes, P-protein assemblages restricted to one single plant family and the only Ca(2+)-responsive P-proteins known, the available evidence does not unequivocally suggest that plug formation is the cause rather than a consequence of translocation stoppage. We conclude that the physiological roles of structural P-proteins remain elusive, and that in vivo studies of their dynamics in continuous sieve tube networks combined with flow velocity measurements will be required to (hopefully) resolve this scientific roadblock. PMID:24591057

  7. [Removal Characteristics of Elemental Mercury by Mn-Ce/molecular Sieve].

    PubMed

    Tan, Zeng-qiang; Niu, Guo-ping; Chen, Xiao-wen; An, Zhen

    2015-06-01

    The impregnation method was used to support molecular sieve with active manganese and cerium components to obtain a composite molecular sieve catalyst. The mercury removal performance of the catalyst was studied with a bench-scale setup. XPS analysis was used to characterize the sample before and after the modification in order to study the changes in the active components of the catalyst prepared. The results showed that the catalyst carrying manganese and cerium components had higher oxidation ability of elemental mercury in the temperature range of 300 degrees C - 450 degrees C, especially at 450 degrees C, the oxidation efficiency of elemental mercury was kept above 80%. The catalyst had more functional groups that were conducive to the oxidation of elemental mercury, and the mercury removal mainly depended on the chemical adsorption. The SO2 and NO in flue gas could inhibit the oxidation of elemental mercury to certain extent. PMID:26387298

  8. OHMS**: Phytoplasmas dictate changes in sieve-element ultrastructure to accommodate their requirements for nutrition, multiplication and translocation

    PubMed Central

    Musetti, Rita; Pagliari, Laura; Buxa, Stefanie V.; Degola, Francesca; De Marco, Federica; Loschi, Alberto; Kogel, Karl-Heinz; van Bel, Aart J. E.

    2016-01-01

    ABSTRACT Phytoplasmas are among the most recently discovered plant pathogenic microorganisms so, many traits of the interactions with host plants and insect vectors are still unclear and need to be investigated. At now, it is impossible to determine the precise sequences leading to the onset of the relationship with the plant host cell. It is still unclear how phytoplasmas, located in the phloem sieve elements, exploit host cell to draw nutrition for their metabolism, growth and multiplication. In this work, basing on microscopical observations, we give insight about the structural interactions established by phytoplasmas and the sieve element plasma membrane, cytoskeleton, sieve endoplasmic reticulum, speculating about a possible functional role. PMID:26795235

  9. Sieve Element Ca2+ Channels as Relay Stations between Remote Stimuli and Sieve Tube Occlusion in Vicia faba[W

    PubMed Central

    Furch, Alexandra C.U.; van Bel, Aart J.E.; Fricker, Mark D.; Felle, Hubert H.; Fuchs, Maike; Hafke, Jens B.

    2009-01-01

    Damage induces remote occlusion of sieve tubes in Vicia faba by forisome dispersion, triggered during the passage of an electropotential wave (EPW). This study addresses the role of Ca2+ channels and cytosolic Ca2+ elevation as a link between EPWs and forisome dispersion. Ca2+ channel antagonists affect the initial phase of the EPW as well as the prolonged plateau phase. Resting levels of sieve tube Ca2+ of ∼50 nM were independently estimated using Ca2+-selective electrodes and a Ca2+-sensitive dye. Transient changes in cytosolic Ca2+ were observed in phloem tissue in response to remote stimuli and showed profiles similar to those of EPWs. The measured elevation of Ca2+ in sieve tubes was below the threshold necessary for forisome dispersion. Therefore, forisomes need to be associated with Ca2+ release sites. We found an association between forisomes and endoplasmic reticulum (ER) at sieve plates and pore-plasmodesma units where high-affinity binding of a fluorescent Ca2+ channel blocker mapped an increased density of Ca2+ channels. In conclusion, propagation of EPWs in response to remote stimuli is linked to forisome dispersion through transiently high levels of parietal Ca2+, release of which depends on both plasma membrane and ER Ca2+ channels. PMID:19602624

  10. Morphine Biosynthesis in Opium Poppy Involves Two Cell Types: Sieve Elements and Laticifers[W][OPEN

    PubMed Central

    Onoyovwe, Akpevwe; Hagel, Jillian M.; Chen, Xue; Khan, Morgan F.; Schriemer, David C.; Facchini, Peter J.

    2013-01-01

    Immunofluorescence labeling and shotgun proteomics were used to establish the cell type–specific localization of morphine biosynthesis in opium poppy (Papaver somniferum). Polyclonal antibodies for each of six enzymes involved in converting (R)-reticuline to morphine detected corresponding antigens in sieve elements of the phloem, as described previously for all upstream enzymes transforming (S)-norcoclaurine to (S)-reticuline. Validated shotgun proteomics performed on whole-stem and latex total protein extracts generated 2031 and 830 distinct protein families, respectively. Proteins corresponding to nine morphine biosynthetic enzymes were represented in the whole stem, whereas only four of the final five pathway enzymes were detected in the latex. Salutaridine synthase was detected in the whole stem, but not in the latex subproteome. The final three enzymes converting thebaine to morphine were among the most abundant active latex proteins despite a limited occurrence in laticifers suggested by immunofluorescence labeling. Multiple charge isoforms of two key O-demethylases in the latex were revealed by two-dimensional immunoblot analysis. Salutaridine biosynthesis appears to occur only in sieve elements, whereas conversion of thebaine to morphine is predominant in adjacent laticifers, which contain morphine-rich latex. Complementary use of immunofluorescence labeling and shotgun proteomics has substantially resolved the cellular localization of morphine biosynthesis in opium poppy. PMID:24104569

  11. Phytoplasma infection in tomato is associated with re-organization of plasma membrane, ER stacks, and actin filaments in sieve elements

    PubMed Central

    Buxa, Stefanie V.; Degola, Francesca; Polizzotto, Rachele; De Marco, Federica; Loschi, Alberto; Kogel, Karl-Heinz; di Toppi, Luigi Sanità; van Bel, Aart J. E.; Musetti, Rita

    2015-01-01

    Phytoplasmas, biotrophic wall-less prokaryotes, only reside in sieve elements of their host plants. The essentials of the intimate interaction between phytoplasmas and their hosts are poorly understood, which calls for research on potential ultrastructural modifications. We investigated modifications of the sieve-element ultrastructure induced in tomato plants by ‘Candidatus Phytoplasma solani,’ the pathogen associated with the stolbur disease. Phytoplasma infection induces a drastic re-organization of sieve-element substructures including changes in plasma membrane surface and distortion of the sieve-element reticulum. Observations of healthy and stolbur-diseased plants provided evidence for the emergence of structural links between sieve-element plasma membrane and phytoplasmas. One-sided actin aggregates on the phytoplasma surface also inferred a connection between phytoplasma and sieve-element cytoskeleton. Actin filaments displaced from the sieve-element mictoplasm to the surface of the phytoplasmas in infected sieve elements. Western blot analysis revealed a decrease of actin and an increase of ER-resident chaperone luminal binding protein (BiP) in midribs of phytoplasma-infected plants. Collectively, the studies provided novel insights into ultrastructural responses of host sieve elements to phloem-restricted prokaryotes. PMID:26347766

  12. Involvement of the sieve element cytoskeleton in electrical responses to cold shocks.

    PubMed

    Hafke, Jens B; Ehlers, Katrin; Föller, Jens; Höll, Sabina-Roxana; Becker, Stefanie; van Bel, Aart J E

    2013-06-01

    This study dealt with the visualization of the sieve element (SE) cytoskeleton and its involvement in electrical responses to local cold shocks, exemplifying the role of the cytoskeleton in Ca(2+)-triggered signal cascades in SEs. High-affinity fluorescent phalloidin as well as immunocytochemistry using anti-actin antibodies demonstrated a fully developed parietal actin meshwork in SEs. The involvement of the cytoskeleton in electrical responses and forisome conformation changes as indicators of Ca(2+) influx was investigated by the application of cold shocks in the presence of diverse actin disruptors (latrunculin A and cytochalasin D). Under control conditions, cold shocks elicited a graded initial voltage transient, ΔV1, reduced by external La(3+) in keeping with the involvement of Ca(2+) channels, and a second voltage transient, ΔV2. Cytochalasin D had no effect on ΔV1, while ΔV1 was significantly reduced with 500 nm latrunculin A. Forisome dispersion was triggered by cold shocks of 4°C or greater, which was indicative of an all-or-none behavior. Forisome dispersion was suppressed by incubation with latrunculin A. In conclusion, the cytoskeleton controls cold shock-induced Ca(2+) influx into SEs, leading to forisome dispersion and sieve plate occlusion in fava bean (Vicia faba). PMID:23624858

  13. Transposition Pattern of the Maize Element Ds in Arabidopsis Thaliana

    PubMed Central

    Bancroft, I.; Dean, C.

    1993-01-01

    As part of establishing an efficient transposon tagging system in Arabidopsis using the maize elements Ac and Ds, we have analyzed the inheritance and pattern of Ds transposition in four independent Arabidopsis transformants. A low proportion (33%) of plants inheriting the marker used to monitor excision contained a transposed Ds. Selection for the transposed Ds increased this to at least 49%. Overall, 68% of Ds transpositions inherited with the excision marker were to genetically linked sites; however, the distribution of transposed elements varied around the different donor sites. Mapping of transposed Ds elements that were genetically unlinked to the donor site showed that a proportion (3 of 11 tested) integrated into sites which were still physically linked. PMID:8397137

  14. Massively parallel mathematical sieves

    SciTech Connect

    Montry, G.R.

    1989-01-01

    The Sieve of Eratosthenes is a well-known algorithm for finding all prime numbers in a given subset of integers. A parallel version of the Sieve is described that produces computational speedups over 800 on a hypercube with 1,024 processing elements for problems of fixed size. Computational speedups as high as 980 are achieved when the problem size per processor is fixed. The method of parallelization generalizes to other sieves and will be efficient on any ensemble architecture. We investigate two highly parallel sieves using scattered decomposition and compare their performance on a hypercube multiprocessor. A comparison of different parallelization techniques for the sieve illustrates the trade-offs necessary in the design and implementation of massively parallel algorithms for large ensemble computers.

  15. The Arabidopsis transposable element Tag1 is widely distributed among Arabidopsis ecotypes.

    PubMed

    Frank, M J; Preuss, D; Mack, A; Kuhlmann, T C; Crawford, N M

    1998-02-01

    Tag1 is an autonomous transposable element (3.3 kb in length) first identified as an insertion in the CHL1 (NRT1) gene of Arabidopsis thaliana. Tag1 has been found in the Landsberg erecta ecotype of A. thaliana but not in Columbia or WS. In this paper, 41 additional ecotypes were examined for the presence of Tag1. Using an internal Tag1 fragment as probe, we found that DNA form 19 of the 41 ecotypes strongly hybridized to Tag1. Almost all of the Tag1-containing ecotypes had only one or two copies of Tag1 per haploid genome, as determined by Southern blot analysis. The only exception, Bf-1 from Bretagny-sur-Orge, France, had four copies. Two ecotypes, Di-G and S96, gave identical Southern blot patterns to that of Landsberg erecta and were subsequently shown to contain Tag1 at the same two positions found in Landsberg erecta (loci designated as Tag1-2 and Tag1-3). Two other ecotypes, Ag-0 and Lo-1, had a Tag1 element located at Tag1-2 but not at Tag1-3. The distance between these two loci was determined to be 0.37 cM. Analysis of DNA from two related species, A. griffithiana and A. pumila, showed that both species contain sequences that hybridize to Tag1 and that could be amplified with an oligonucleotide specific to the terminal inverted repeats of Tag1. These results show that Tag1 and related elements are present, and may be useful for insertional mutagenesis, in many A. thaliana ecotypes and several Arabidopsis species. PMID:9529529

  16. Microautophagy involves programmed cell semi-death of sieve elements in developing caryopsis of Triticum aestivum L.

    PubMed

    Yang, Wenli; Cai, Jingtong; Zhou, Zhuqing; Zhou, Guangsheng; Mei, Fangzhu; Wang, Likai

    2015-12-01

    Differentiation of sieve elements (SEs) involves programmed cell semi-death, in which a small amount of organelles is retained. However, the mechanisms by which a large amount of SE cytoplasm is degraded and the specific proteases involved are not clear. In this study, we confirmed that the degradation of cytoplasm outside of the vacuole was mediated by microautophagy of the vacuole, and that the tonoplast selectively fused with the plasma membrane after most of the cytoplasm in the vacuoles was degraded. The integration of space enclosed a small amount of cytoplasm. Therefore, that fraction of the cytoplasm was preserved. At the same time, the cytosol was weakly acidic during membrane fusion because part of the tonoplast was ruptured. We also demonstrated that wheat aspartic protease (WAP1) and proteases including cathepsin B activity (PICA) were involved in programmed cell semi-death of SEs. PICA showed strongest activity before mass of the cytoplasm was degraded, which might contribute toward SE stability. We found that WAP1 mainly degraded the cytoplasm. Therefore, programmed cell semi-death of SEs might result from the joint action of vacuoles and multiple proteases. PMID:26146941

  17. Quantification of Plasmodesmatal Endoplasmic Reticulum Coupling between Sieve Elements and Companion Cells Using Fluorescence Redistribution after Photobleaching1[W

    PubMed Central

    Martens, Helle J.; Roberts, Alison G.; Oparka, Karl J.; Schulz, Alexander

    2006-01-01

    Transgenic tobacco (Nicotiana tabacum) was studied to localize the activity of phloem loading during development and to establish whether the endoplasmic reticulum (ER) of the companion cell (CC) and the sieve element (SE) reticulum is continuous by using a SUC2 promoter-green fluorescent protein (GFP) construct targeted to the CC-ER. Expression of GFP marked the collection phloem in source leaves and cotyledons as expected, but also the transport phloem in stems, petioles, midveins of sink leaves, nonphotosynthetic flower parts, roots, and newly germinated seedlings, suggesting that sucrose retrieval along the pathway is an integral component of phloem function. GFP fluorescence was limited to CCs where it was visualized as a well-developed ER network in close proximity to the plasma membrane. ER coupling between CC and SEs was tested in wild-type tobacco using an ER-specific fluorochrome and fluorescence redistribution after photobleaching (FRAP), and showed that the ER is continuous via pore-plasmodesma units. ER coupling between CC and SE was quantified by determining the mobile fraction and half-life of fluorescence redistribution and compared with that of other cell types. In all tissues, fluorescence recovered slowly when it was rate limited by plasmodesmata, contrasting with fast intracellular FRAP. FRAP was unaffected by treatment with cytochalasin D. The highest degree of ER coupling was measured between CC and SE. Intimate ER coupling is consistent with a possible role for ER in membrane protein and signal exchange between CC and SE. However, a complete lack of GFP transfer between CC and SE indicated that the intraluminal pore-plasmodesma contact has a size exclusion limit below 27 kD. PMID:16905664

  18. Arabidopsis thaliana—Aphid Interaction

    PubMed Central

    Louis, Joe; Singh, Vijay; Shah, Jyoti

    2012-01-01

    Aphids are important pests of plants that use their stylets to tap into the sieve elements to consume phloem sap. Besides the removal of photosynthates, aphid infestation also alters source-sink patterns. Most aphids also vector viral diseases. In this chapter, we will summarize on recent significant findings in plant-aphid interaction, and how studies involving Arabidopsis thaliana and Myzus persicae (Sülzer), more commonly known as the green peach aphid (GPA), are beginning to provide important insights into the molecular basis of plant defense and susceptibility to aphids. The recent demonstration that expression of dsRNA in Arabidopsis can be used to silence expression of genes in GPA has further expanded the utility of Arabidopsis for evaluating the contribution of the aphid genome-encoded proteins to this interaction. PMID:22666177

  19. Chromatin immunoprecipitation reveals that the 180-bp satellite repeat is the key functional DNA element of Arabidopsis thaliana centromeres.

    PubMed Central

    Nagaki, Kiyotaka; Talbert, Paul B; Zhong, Cathy Xiaoyan; Dawe, R Kelly; Henikoff, Steven; Jiang, Jiming

    2003-01-01

    The centromeres of Arabidopsis thaliana chromosomes contain megabases of complex DNA consisting of numerous types of repetitive DNA elements. We developed a chromatin immunoprecipitation (ChIP) technique using an antibody against the centromeric H3 histone, HTR12, in Arabidopsis. ChIP assays showed that the 180-bp centromeric satellite repeat was precipitated with the antibody, suggesting that this repeat is the key component of the centromere/kinetochore complex in Arabidopsis. PMID:12663558

  20. Generation of optical vortices by apodized photon sieves

    NASA Astrophysics Data System (ADS)

    Sun, Hai-bin; Wang, Xing-hai; Chen, Jun; Sun, Ping

    2016-05-01

    As a novel diffractive optical element, photon sieve has good focusing properties. We propose a method to verify the focusing properties by using apodized photon sieves. The apodized photon sieve is obtained by using a Gaussian window function to modulate the general photon sieve. Focusing properties of apodized photon sieve are studied by numerical simulations and experiments. It shows that photon sieves have good focusing ability, and the focusing ability of the photon sieve on the focal plane is stronger than that on other image planes. The experimental results also demonstrate that photon sieves can be used to generate optical vortices. The existence of optical vortices is confirmed by the formation of fork fringes. This apodized photon sieve is expected to have some practical applications in focusing analysis, optical imaging, and optical communication.

  1. The Sucrose Transporter StSUT1 Localizes to Sieve Elements in Potato Tuber Phloem and Influences Tuber Physiology and Development1[w

    PubMed Central

    Kühn, Christina; Hajirezaei, Mohammad-Reza; Fernie, Alisdair R.; Roessner-Tunali, Ute; Czechowski, Tomasz; Hirner, Brigitte; Frommer, Wolf B.

    2003-01-01

    The sucrose (Suc) H+-cotransporter StSUT1 from potato (Solanum tuberosum), which is essential for long-distance transport of Suc and assumed to play a role in phloem loading in mature leaves, was found to be expressed in sink tubers. To answer the question of whether SUT1 serves a function in phloem unloading in tubers, the promoter was fused to gusA and expression was analyzed in transgenic potato. SUT1 expression was unexpectedly detected not in tuber parenchyma but in the phloem of sink tubers. Immunolocalization demonstrated that StSUT1 protein was present only in sieve elements of sink tubers, cells normally involved in export of Suc from the phloem to supply developing tubers, raising the question of the role of SUT1 in tubers. SUT1 expression was inhibited by antisense in transgenic potato plants using a class I patatin promoter B33, which is primarily expressed in the phloem of developing tubers. Reduced SUT1 expression in tubers did not affect aboveground organs but led to reduced fresh weight accumulation during early stages of tuber development, indicating that in this phase SUT1 plays an important role for sugar transport. Changes in Suc- and starch-modifying enzyme activities and metabolite profiles are consistent with the developmental switch in unloading mechanisms. Altogether, the findings may suggest a role of SUT1 in retrieval of Suc from the apoplasm, thereby regulating the osmotic potential in the extracellular space, or a direct role in phloem unloading acting as a phloem exporter transferring Suc from the sieve elements into the apoplasm. PMID:12529519

  2. Comparative Modal Analysis of Sieve Hardware Designs

    NASA Technical Reports Server (NTRS)

    Thompson, Nathaniel

    2012-01-01

    The CMTB Thwacker hardware operates as a testbed analogue for the Flight Thwacker and Sieve components of CHIMRA, a device on the Curiosity Rover. The sieve separates particles with a diameter smaller than 150 microns for delivery to onboard science instruments. The sieving behavior of the testbed hardware should be similar to the Flight hardware for the results to be meaningful. The elastodynamic behavior of both sieves was studied analytically using the Rayleigh Ritz method in conjunction with classical plate theory. Finite element models were used to determine the mode shapes of both designs, and comparisons between the natural frequencies and mode shapes were made. The analysis predicts that the performance of the CMTB Thwacker will closely resemble the performance of the Flight Thwacker within the expected steady state operating regime. Excitations of the testbed hardware that will mimic the flight hardware were recommended, as were those that will improve the efficiency of the sieving process.

  3. Arabidopsis and the Genetic Potential for the Phytoremediation of Toxic Elemental and Organic Pollutants

    PubMed Central

    Cobbett, Christopher S.; Meagher, Richard B.

    2002-01-01

    In a process called phytoremediation, plants can be used to extract, detoxify, and/or sequester toxic pollutants from soil, water, and air. Phytoremediation may become an essential tool in cleaning the environment and reducing human and animal exposure to potential carcinogens and other toxins. Arabidopsis has provided useful information about the genetic, physiological, and biochemical mechanisms behind phytoremediation, and it is an excellent model genetic organism to test foreign gene expression. This review focuses on Arabidopsis studies concerning: 1) the remediation of elemental pollutants; 2) the remediation of organic pollutants; and 3) the phytoremediation genome. Elemental pollutants include heavy metals and metalloids (e.g., mercury, lead, cadmium, arsenic) that are immutable. The general goal of phytoremediation is to extract, detoxify, and hyperaccumulate elemental pollutants in above-ground plant tissues for later harvest. A few dozen Arabidopsis genes and proteins that play direct roles in the remediation of elemental pollutants are discussed. Organic pollutants include toxic chemicals such as benzene, benzo(a)pyrene, polychlorinated biphenyls, trichloroethylene, trinitrotoluene, and dichlorodiphenyltrichloroethane. Phytoremediation of organic pollutants is focused on their complete mineralization to harmless products, however, less is known about the potential of plants to act on complex organic chemicals. A preliminary survey of the Arabidopsis genome suggests that as many as 700 genes encode proteins that have the capacity to act directly on environmental pollutants or could be modified to do so. The potential of the phytoremediation proteome to be used to reduce human exposure to toxic pollutants appears to be enormous and untapped. PMID:22303204

  4. The transposition frequency of Tag1 elements is increased in transgenic Arabidopsis lines.

    PubMed Central

    Bhatt, A M; Lister, C; Crawford, N; Dean, C

    1998-01-01

    Tag1 was identified as a highly active endogenous transposable element in transgenic Arabidopsis thaliana Landsberg erecta plants carrying the maize transposable element Activator (Ac). Here, we describe experiments designed to determine the basis for the high activity of Tag1. The frequency of transposition of Tag1 elements was compared in lines containing or lacking Ac transposase to assess the effect of Ac transposase on Tag1 activity. Three populations of nontransgenic plants, including nontransformed regenerants, were also analyzed. The high level of activity of Tag1 did not correlate with the presence or absence of Ac transposase but was significantly higher in transgenic lines. This result was maintained through at least six generations after transformation. These data suggest that Tag1 transposition is stimulated by processes that occur during the Agrobacterium transformation and that thereafter remain active. Two Tag1 elements are tightly linked in the Landsberg erecta genome and map to the lower arm of chromosome 1. Tag1 elements were found in only a few A. thaliana ecotypes but were present in four other Arabidopsis species. PMID:9501115

  5. Population dynamics of an Ac-like transposable element in self- and cross-pollinating arabidopsis.

    PubMed Central

    Wright, S I; Le, Q H; Schoen, D J; Bureau, T E

    2001-01-01

    Theoretical models predict that the mating system should be an important factor driving the dynamics of transposable elements in natural populations due to differences in selective pressure on both element and host. We used a PCR-based approach to examine the abundance and levels of insertion polymorphism of Ac-III, a recently identified Ac-like transposon family, in natural populations of the selfing plant Arabidopsis thaliana and its close outcrossing relative, Arabidopsis lyrata. Although several insertions appeared to be ancient and shared between species, there is strong evidence for recent activity of this element family in both species. Sequences of the regions flanking insertions indicate that all Ac-III transposons segregating in natural populations are in noncoding regions and provide no evidence for local transposition events. Transposon display analysis suggests the presence of slightly higher numbers of insertion sites per individual but fewer total polymorphic insertions in the self-pollinating A. thaliana than A. lyrata. Element insertions appear to be segregating at significantly lower frequencies in A. lyrata than A. thaliana, which is consistent with a reduction in transposition rate, reduction in effective population size, or reduced efficacy of natural selection against element insertions in selfing populations. PMID:11454774

  6. Transcript Abundance Explains mRNA Mobility Data in Arabidopsis thaliana.

    PubMed

    Calderwood, Alexander; Kopriva, Stanislav; Morris, Richard J

    2016-03-01

    Recently, a large population of mRNA was shown to be able to travel between plant organs via sieve elements as a putative long-distance signaling molecule. However, a mechanistic basis by which transcripts are selected for transport has not yet been identified. Here, we show that experimental mRNA mobility data in Arabidopsis can be explained by transcript abundance and half-life. This suggests that the majority of identified mobile transcripts can be accounted for by non-sequence-specific movement of mRNA from companion cells into sieve elements. PMID:26952566

  7. Transcript Abundance Explains mRNA Mobility Data in Arabidopsis thaliana[OPEN

    PubMed Central

    Calderwood, Alexander

    2016-01-01

    Recently, a large population of mRNA was shown to be able to travel between plant organs via sieve elements as a putative long-distance signaling molecule. However, a mechanistic basis by which transcripts are selected for transport has not yet been identified. Here, we show that experimental mRNA mobility data in Arabidopsis can be explained by transcript abundance and half-life. This suggests that the majority of identified mobile transcripts can be accounted for by non-sequence-specific movement of mRNA from companion cells into sieve elements. PMID:26952566

  8. Transposable elements, a treasure trove to decipher epigenetic variation: insights from Arabidopsis and crop epigenomes.

    PubMed

    Mirouze, Marie; Vitte, Clémentine

    2014-06-01

    In the past decade, plant biologists and breeders have developed a growing interest in the field of epigenetics, which is defined as the study of heritable changes in gene expression that cannot be explained by changes in the DNA sequence. Epigenetic marks can be responsive to the environment, and evolve faster than genetic changes. Therefore, epigenetic diversity may represent an unexplored resource of natural variation that could be used in plant breeding programmes. On the other hand, crop genomes are largely populated with transposable elements (TEs) that are efficiently targeted by epigenetic marks, and part of the epigenetic diversity observed might be explained by TE polymorphisms. Characterizing the degree to which TEs influence epigenetic variation in crops is therefore a major goal to better use epigenetic variation. To date, epigenetic analyses have been mainly focused on the model plant Arabidopsis thaliana, and have provided clues on epigenome features, components that silence pathways, and effects of silencing impairment. But to what extent can Arabidopsis be used as a model for the epigenomics of crops? In this review, we discuss the similarities and differences between the epigenomes of Arabidopsis and crops. We explore the relationship between TEs and epigenomes, focusing on TE silencing control and escape, and the impact of TE mobility on epigenomic variation. Finally, we provide insights into challenges to tackle, and future directions to take in the route towards using epigenetic diversity in plant breeding programmes. PMID:24744427

  9. Sieve Tube Geometry in Relation to Phloem Flow

    PubMed Central

    Mullendore, Daniel L.; Windt, Carel W.; Van As, Henk; Knoblauch, Michael

    2010-01-01

    Sieve elements are one of the least understood cell types in plants. Translocation velocities and volume flow to supply sinks with photoassimilates greatly depend on the geometry of the microfluidic sieve tube system and especially on the anatomy of sieve plates and sieve plate pores. Several models for phloem translocation have been developed, but appropriate data on the geometry of pores, plates, sieve elements, and flow parameters are lacking. We developed a method to clear cells from cytoplasmic constituents to image cell walls by scanning electron microscopy. This method allows high-resolution measurements of sieve element and sieve plate geometries. Sieve tube–specific conductivity and its reduction by callose deposition after injury was calculated for green bean (Phaseolus vulgaris), bamboo (Phyllostachys nuda), squash (Cucurbita maxima), castor bean (Ricinus communis), and tomato (Solanum lycopersicum). Phloem sap velocity measurements by magnetic resonance imaging velocimetry indicate that higher conductivity is not accompanied by a higher velocity. Studies on the temporal development of callose show that small sieve plate pores might be occluded by callose within minutes, but plants containing sieve tubes with large pores need additional mechanisms. PMID:20354199

  10. Direct and residual effects of cadmium on the growth and elemental composition of Arabidopsis thaliana

    SciTech Connect

    Moser, T.J.; Tingey, D.; Rodecap, K.D.

    1986-01-01

    Experiments were conducted to determine the direct (first generation) and residual (second generation) phytotoxicity of a range of cadmium concentrations on Arabidopsis thaliana. Plants were grown under greenhouse conditions in double-container, vermiculite-hydroponic plot-culture systems. First generation plants were continuously exposed to nutrient solutions ranging from 0 to 100 micrometers CdCl/sub 2/. Biomass in the first generation plants decreased in response to nutrient solution containing increasing Cd concentrations. The 100 micrometers Cd treatment significantly reduced rosette, raceme and mature seed biomass. The progeny from the first-generation plants revealed no significant residual effects as far as growth and elemental composition are concerned.

  11. Germinal and Somatic Activity of the Maize Element Activator (Ac) in Arabidopsis

    PubMed Central

    Keller, J.; Lim, E.; James-Jr., D. W.; Dooner, H. K.

    1992-01-01

    We have investigated the germinal and somatic activity of the maize Activator (Ac) element in Arabidopsis with the objective of developing an efficient transposon-based system for gene isolation in that plant. Transposition activity was assayed with a chimeric marker that consists of the cauliflower mosaic virus 35S promoter and a bacterial streptomycin phosphotransferase gene (SPT). Somatic activity was detected in seedlings germinated on plates containing streptomycin as green-resistant sectors against a background of white-sensitive cells. Germinal excisions resulted in fully green seedlings. The transposition frequency was extremely low when a single copy of the transposon was present, but appeared to increase with an increase in Ac copy number. Plants that were selected as variegated produced an increased number of green progeny. The methylation state of the Ac elements in lines with either low or high levels of excision was assessed by restriction analysis. No difference was found between these lines, indicating that the degree of methylation did not contribute to the level of Ac activity. Germinal excision events were analyzed molecularly and shown to carry reinserted transposons in about 50% of the cases. In several instances, streptomycin-resistant siblings carried the same transposed Ac element, indicating that excision had occurred prior to meiosis in the parent. We discuss parameters that need to be considered to optimize the use of Ac as a transposon tag in Arabidopsis. PMID:1322854

  12. Characterization and identification of cis-regulatory elements in Arabidopsis based on single-nucleotide polymorphism information.

    PubMed

    Korkuc, Paula; Schippers, Jos H M; Walther, Dirk

    2014-01-01

    Identifying regulatory elements and revealing their role in gene expression regulation remains a central goal of plant genome research. We exploited the detailed genomic sequencing information of a large number of Arabidopsis (Arabidopsis thaliana) accessions to characterize known and to identify novel cis-regulatory elements in gene promoter regions of Arabidopsis by relying on conservation as the hallmark signal of functional relevance. Based on the genomic layout and the obtained density profiles of single-nucleotide polymorphisms (SNPs) in sequence regions upstream of transcription start sites, the average length of promoter regions in Arabidopsis could be established at 500 bp. Genes associated with high degrees of variability of their respective upstream regions are preferentially involved in environmental response and signaling processes, while low levels of promoter SNP density are common among housekeeping genes. Known cis-elements were found to exhibit a decreased SNP density than sequence regions not associated with known motifs. For 15 known cis-element motifs, strong positional preferences relative to the transcription start site were detected based on their promoter SNP density profiles. Five novel candidate cis-element motifs were identified as consensus motifs of 17 sequence hexamers exhibiting increased sequence conservation combined with evidence of positional preferences, annotation information, and functional relevance for inducing correlated gene expression. Our study demonstrates that the currently available resolution of SNP data offers novel ways for the identification of functional genomic elements and the characterization of gene promoter sequences. PMID:24204023

  13. Reversed end Ds element: a novel tool for chromosome engineering in Arabidopsis.

    PubMed

    Krishnaswamy, Lakshminarasimhan; Zhang, Jianbo; Peterson, Thomas

    2008-11-01

    The maize Ac/Ds transposable element (TE) transposes by a "cut and paste" mechanism. Previous studies in maize showed that when the TE ends are in reversed orientation with respect to each other, alternative transposition reactions can occur resulting in large scale genome rearrangements including deletions and inversions. To test whether similar genome rearrangements can also occur in other plants, we studied the efficacy of such alternative transposition-mediated genome rearrangements in Arabidopsis. Here we present our analysis of 33 independent chromosome rearrangements. Transposition at the reversed ends Ds element can cause deletions over 1 Mbp, and inversions up to 2.4 Mbp in size. We identified additional rearrangements including a reciprocal translocation and a putative ring chromosome. Some of the deletions and inversions are germinally transmitted. PMID:18685955

  14. Evolution of Cis-Regulatory Elements and Regulatory Networks in Duplicated Genes of Arabidopsis1[OPEN

    PubMed Central

    Guo, Xu Qiu; Adams, Keith L.

    2015-01-01

    Plant genomes contain large numbers of duplicated genes that contribute to the evolution of new functions. Following duplication, genes can exhibit divergence in their coding sequence and their expression patterns. Changes in the cis-regulatory element landscape can result in changes in gene expression patterns. High-throughput methods developed recently can identify potential cis-regulatory elements on a genome-wide scale. Here, we use a recent comprehensive data set of DNase I sequencing-identified cis-regulatory binding sites (footprints) at single-base-pair resolution to compare binding sites and network connectivity in duplicated gene pairs in Arabidopsis (Arabidopsis thaliana). We found that duplicated gene pairs vary greatly in their cis-regulatory element architecture, resulting in changes in regulatory network connectivity. Whole-genome duplicates (WGDs) have approximately twice as many footprints in their promoters left by potential regulatory proteins than do tandem duplicates (TDs). The WGDs have a greater average number of footprint differences between paralogs than TDs. The footprints, in turn, result in more regulatory network connections between WGDs and other genes, forming denser, more complex regulatory networks than shown by TDs. When comparing regulatory connections between duplicates, WGDs had more pairs in which the two genes are either partially or fully diverged in their network connections, but fewer genes with no network connections than the TDs. There is evidence of younger TDs and WGDs having fewer unique connections compared with older duplicates. This study provides insights into cis-regulatory element evolution and network divergence in duplicated genes. PMID:26474639

  15. Differential interactions of promoter elements in stress responses of the Arabidopsis Adh gene.

    PubMed Central

    Dolferus, R; Jacobs, M; Peacock, W J; Dennis, E S

    1994-01-01

    The Adh (alcohol dehydrogenase, EC 1.1.1.1.) gene from Arabidopsis thaliana (L.) Heynh. can be induced by dehydration and cold, as well as by hypoxia. A 1-kb promoter fragment (CADH: -964 to +53) is sufficient to confer the stress induction and tissue-specific developmental expression characteristics of the Adh gene to a beta-glucuronidase reporter gene. Deletion mapping of the 5' end and site-specific mutagenesis identified four regions of the promoter essential for expression under the three stress conditions. Some sequence elements are important for response to all three stress treatments, whereas others are stress specific. The most critical region essential for expression of the Arabidopsis Adh promoter under all three environmental stresses (region IV: -172 to -141) contains sequences homologous to the GT motif (-160 to -152) and the GC motif (-147 to -144) of the maize Adh1 anaerobic responsive element. Region III (-235 to -172) contains two regions shown by R.J. Ferl and B.H. Laughner ([1989] Plant Mol Biol 12: 357-366) to bind regulatory proteins; mutation of the G-box-1 region (5'-CCACGTGG-3', -216 to -209) does not affect expression under uninduced or hypoxic conditions, but significantly reduces induction by cold stress and, to a lesser extent, by dehydration stress. Mutation of the other G-box-like sequence (G-box-2: 5'-CCAAGTGG-3', -193 to -182) does not change hypoxic response and affects cold and dehydration stress only slightly. G-box-2 mutations also promote high levels of expression under uninduced conditions. Deletion of region I (-964 to -510) results in increased expression under uninduced and all stress conditions, suggesting that this region contains a repressor binding site. Region II (-510 to -384) contains a positive regulatory element and is necessary for high expression levels under all treatments. PMID:7972489

  16. Characterization of Putative cis-Regulatory Elements in Genes Preferentially Expressed in Arabidopsis Male Meiocytes

    PubMed Central

    Li, Mingjun

    2014-01-01

    Meiosis is essential for plant reproduction because it is the process during which homologous chromosome pairing, synapsis, and meiotic recombination occur. The meiotic transcriptome is difficult to investigate because of the size of meiocytes and the confines of anther lobes. The recent development of isolation techniques has enabled the characterization of transcriptional profiles in male meiocytes of Arabidopsis. Gene expression in male meiocytes shows unique features. The direct interaction of transcription factors (TFs) with DNA regulatory sequences forms the basis for the specificity of transcriptional regulation. Here, we identified putative cis-regulatory elements (CREs) associated with male meiocyte-expressed genes using in silico tools. The upstream regions (1 kb) of the top 50 genes preferentially expressed in Arabidopsis meiocytes possessed conserved motifs. These motifs are putative binding sites of TFs, some of which share common functions, such as roles in cell division. In combination with cell-type-specific analysis, our findings could be a substantial aid for the identification and experimental verification of the protein-DNA interactions for the specific TFs that drive gene expression in meiocytes. PMID:25250331

  17. Elemental concentrations in the seed of mutants and natural variants of Arabidopsis thaliana grown under varying soil conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The concentrations of mineral nutrients in seeds are critical to both the life cycle of plants as well as human nutrition. These concentrations are strongly influenced by soil conditions, as shown here by quantifying the concentration of 14 elements in seeds from Arabidopsis thaliana plants grown un...

  18. Epigenetic regulation of repetitive elements is attenuated by prolonged heat stress in Arabidopsis.

    PubMed

    Pecinka, Ales; Dinh, Huy Q; Baubec, Tuncay; Rosa, Marisa; Lettner, Nicole; Mittelsten Scheid, Ortrun

    2010-09-01

    Epigenetic factors determine responses to internal and external stimuli in eukaryotic organisms. Whether and how environmental conditions feed back to the epigenetic landscape is more a matter of suggestion than of substantiation. Plants are suitable organisms with which to address this question due to their sessile lifestyle and diversification of epigenetic regulators. We show that several repetitive elements of Arabidopsis thaliana that are under epigenetic regulation by transcriptional gene silencing at ambient temperatures and upon short term heat exposure become activated by prolonged heat stress. Activation can occur without loss of DNA methylation and with only minor changes to histone modifications but is accompanied by loss of nucleosomes and by heterochromatin decondensation. Whereas decondensation persists, nucleosome loading and transcriptional silencing are restored upon recovery from heat stress but are delayed in mutants with impaired chromatin assembly functions. The results provide evidence that environmental conditions can override epigenetic regulation, at least transiently, which might open a window for more permanent epigenetic changes. PMID:20876829

  19. Studies on the introduction and mobility of the maize Activator element in Arabidopsis thaliana and Daucus carota.

    PubMed Central

    Van Sluys, M A; Tempé, J; Fedoroff, N

    1987-01-01

    We have co-transformed carrot (Daucus carota) and Arabidopsis thaliana with an Agrobacterium tumefaciens non-tumorigenic T-DNA carrying the maize transposable element Activator (Ac) and an Agrobacterium rhizogenes Ri T-DNA. We present evidence that the Ac element transposes in transformed root or root-derived callus cultures of both species. We show that fertile plants can be regenerated from transformed, root-derived callus cultures of Arabidopsis, demonstrating the utility of the Ri plasmid for introducing the maize Ac element into plants. We also present evidence that Ac elements that excise from the transforming T-DNA early after transformation continue to be mobile in carrot root cultures. Images Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. 7. PMID:2832144

  20. Cellular compartmentation of cadmium and zinc in relation to other elements in the hyperaccumulator Arabidopsis halleri.

    PubMed

    Küpper, H; Lombi, E; Zhao, F J; McGrath, S P

    2000-12-01

    The cellular compartmentation of elements was analysed in the Zn hyperaccumulator Arabidopsis halleri (L.) O'Kane & Al-Shehbaz (=Cardaminopsis halleri) using energy-dispersive X-ray microanalysis of frozen-hydrated tissues. Quantitative data were obtained using oxygen as an internal standard in the analyses of vacuoles, whereas a peak/background ratio method was used for quantification of elements in pollen and dehydrated trichomes. Arabidopsis halleri was found to hyperaccumulate not only Zn but also Cd in the shoot biomass. While large concentrations of Zn and Cd were found in the leaves and roots, flowers contained very little. In roots grown hydroponically, Zn and Cd accumulated in the cell wall of the rhizodermis (root epidermis), mainly due to precipitation of Zn/Cd phosphates. In leaves, the trichomes had by far the largest concentrations of Zn and Cd. Inside the trichomes there was a striking sub-cellular compartmentation, with almost all the Zn and Cd being accumulated in a narrow ring in the trichome base. This distribution pattern was very different from that for Ca and P. The epidermal cells other than trichomes were very small and contained lower concentrations of Zn and Cd than mesophyll cells. In particular, the concentrations of Cd and Zn in the mesophyll cells increased markedly in response to increasing Zn and Cd concentrations in the nutrient solution. This indicates that the mesophyll cells in the leaves of A. halleri are the major storage site for Zn and Cd, and play an important role in their hyperaccumulation. PMID:11219586

  1. Analysis of the chromatin domain organisation around the plastocyanin gene reveals an MAR-specific sequence element in Arabidopsis thaliana.

    PubMed Central

    van Drunen, C M; Oosterling, R W; Keultjes, G M; Weisbeek, P J; van Driel, R; Smeekens, S C

    1997-01-01

    The Arabidopsis thaliana genome is currently being sequenced, eventually leading towards the unravelling of all potential genes. We wanted to gain more insight into the way this genome might be organized at the ultrastructural level. To this extent we identified matrix attachment regions demarking potential chromatin domains, in a 16 kb region around the plastocyanin gene. The region was cloned and sequenced revealing six genes in addition to the plastocyanin gene. Using an heterologous in vitro nuclear matrix binding assay, to search for evolutionary conserved matrix attachment regions (MARs), we identified three such MARs. These three MARs divide the region into two small chromatin domains of 5 kb, each containing two genes. Comparison of the sequence of the three MARs revealed a degenerated 21 bp sequence that is shared between these MARs and that is not found elsewhere in the region. A similar sequence element is also present in four other MARs of Arabidopsis.Therefore, this sequence may constitute a landmark for the position of MARs in the genome of this plant. In a genomic sequence database of Arabidopsis the 21 bp element is found approximately once every 10 kb. The compactness of the Arabidopsis genome could account for the high incidence of MARs and MRSs we observed. PMID:9380515

  2. Microfluidic sieve valves

    SciTech Connect

    Quake, Stephen R; Marcus, Joshua S; Hansen, Carl L

    2015-01-13

    Sieve valves for use in microfluidic device are provided. The valves are useful for impeding the flow of particles, such as chromatography beads or cells, in a microfluidic channel while allowing liquid solution to pass through the valve. The valves find particular use in making microfluidic chromatography modules.

  3. The role of CAX1 and CAX3 in elemental distribution and abundance in Arabidopsis seed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability to alter nutrient partitioning within plant cells is poorly understood. In Arabidopsis (Arabidopsis thaliana), a family of endomembrane cation exchangers (CAXs) transports Ca(2+) and other cations. However, experiments have not focused on how the distribution and partitioning of calcium ...

  4. Copper crystallite in carbon molecular sieves for selective oxygen removal

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K. (Inventor); Seshan, Panchalam K. (Inventor)

    1993-01-01

    Carbon molecular sieves modified by the incorporation of finely divided elemental copper useful for the selective sorption of oxygen at elevated temperatures. The carbon molecular sieves can be regenerated by reduction with hydrogen. The copper modified carbon molecular sieves are prepared by pyrolysis of a mixture of a copper-containing material and polyfurfuryl alcohol to form a sorbent precursor. The sorbent precursors are then heated and reduced to produce copper modified carbon molecular sieves. The copper modified carbon molecular sieves are useful for sorption of all concentrations of oxygen at temperatures up to about 200.degree. C. They are also useful for removal of trace amount of oxygen from gases at temperatures up to about 600.degree. C.

  5. Copper modified carbon molecular sieves for selective oxygen removal

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K. (Inventor); Seshan, Panchalam K. (Inventor)

    1992-01-01

    Carbon molecular sieves modified by the incorporation of finely divided elemental copper useful for the selective sorption of oxygen at elevated temperatures. The carbon molecular sieves can be regenerated by reduction with hydrogen. The copper modified carbon molecular sieves are prepared by pyrolysis of a mixture of a copper-containing material and polyfunctional alcohol to form a sorbent precursor. The sorbent precursors are then heated and reduced to produce copper modified carbon molecular sieves. The copper modified carbon molecular sieves are useful for sorption of all concentrations of oxygen at temperatures up to about 200.degree. C. They are also useful for removal of trace amount of oxygen from gases at temperatures up to about 600.degree. C.

  6. Expression of the Arabidopsis transposable element Tag1 is targeted to developing gametophytes.

    PubMed

    Galli, Mary; Theriault, Angie; Liu, Dong; Crawford, Nigel M

    2003-12-01

    The Arabidopsis transposon Tag1 undergoes late excision during vegetative and germinal development in plants containing 35S-Tag1-GUS constructs. To determine if transcriptional regulation can account for the developmental control of Tag1 excision, the transcriptional activity of Tag1 promoter-GUS fusion constructs of various lengths was examined in transgenic plants. All constructs showed expression in the reproductive organs of developing flowers but no expression in leaves. Expression was restricted to developing gametophytes in both male and female lineages. Quantitative RT-PCR analysis confirmed that Tag1 expression predominates in the reproductive organs of flower buds. These results are consistent with late germinal excision of Tag1, but they cannot explain the vegetative excision activity of Tag1 observed with 35S-Tag1-GUS constructs. To resolve this issue, Tag1 excision was reexamined using elements with no adjacent 35S promoter sequences. Tag1 excision in this context is restricted to germinal events with no detectable vegetative excision. If a 35S enhancer sequence is placed next to Tag1, vegetative excision is restored. These results indicate that the intrinsic activity of Tag1 is restricted to germinal excision due to targeted expression of the Tag1 transposase to developing gametophytes and that this activity is altered by the presence of adjacent enhancers or promoters. PMID:14704189

  7. Codon usage biases of transposable elements and host nuclear genes in Arabidopsis thaliana and Oryza sativa.

    PubMed

    Jia, Jia; Xue, Qingzhong

    2009-12-01

    Transposable elements (TEs) are mobile genetic entities ubiquitously distributed in nearly all genomes. High frequency of codons ending in A/T in TEs has been previously observed in some species. In this study, the biases in nucleotide composition and codon usage of TE transposases and host nuclear genes were investigated in the AT-rich genome of Arabidopsis thaliana and the GC-rich genome of Oryza sativa. Codons ending in A/T are more frequently used by TEs compared with their host nuclear genes. A remarkable positive correlation between highly expressed nuclear genes and C/G-ending codons were detected in O. sativa (r=0.944 and 0.839, respectively, P<0.0001) but not in A. thaliana, indicating a close association between the GC content and gene expression level in monocot species. In both species, TE codon usage biases are similar to that of weakly expressed genes. The expression and activity of TEs may be strictly controlled in plant genomes. Mutation bias and selection pressure have simultaneously acted on the TE evolution in A. thaliana and O. sativa. The consistently observed biases of nucleotide composition and codon usage of TEs may also provide a useful clue to accurately detect TE sequences in different species. PMID:20172490

  8. Proteomic Analysis of Microtubule Interacting Proteins over the Course of Xylem Tracheary Element Formation in Arabidopsis.

    PubMed

    Derbyshire, Paul; Ménard, Delphine; Green, Porntip; Saalbach, Gerhard; Buschmann, Henrik; Lloyd, Clive W; Pesquet, Edouard

    2015-10-01

    Plant vascular cells, or tracheary elements (TEs), rely on circumferential secondary cell wall thickenings to maintain sap flow. The patterns in which TE thickenings are organized vary according to the underlying microtubule bundles that guide wall deposition. To identify microtubule interacting proteins present at defined stages of TE differentiation, we exploited the synchronous differentiation of TEs in Arabidopsis thaliana suspension cultures. Quantitative proteomic analysis of microtubule pull-downs, using ratiometric (14)N/(15)N labeling, revealed 605 proteins exhibiting differential accumulation during TE differentiation. Microtubule interacting proteins associated with membrane trafficking, protein synthesis, DNA/RNA binding, and signal transduction peaked during secondary cell wall formation, while proteins associated with stress peaked when approaching TE cell death. In particular, CELLULOSE SYNTHASE-INTERACTING PROTEIN1, already associated with primary wall synthesis, was enriched during secondary cell wall formation. RNAi knockdown of genes encoding several of the identified proteins showed that secondary wall formation depends on the coordinated presence of microtubule interacting proteins with nonoverlapping functions: cell wall thickness, cell wall homogeneity, and the pattern and cortical location of the wall are dependent on different proteins. Altogether, proteins linking microtubules to a range of metabolic compartments vary specifically during TE differentiation and regulate different aspects of wall patterning. PMID:26432860

  9. Compilation of mRNA Polyadenylation Signals in Arabidopsis Revealed a New Signal Element and Potential Secondary Structures1[w

    PubMed Central

    Loke, Johnny C.; Stahlberg, Eric A.; Strenski, David G.; Haas, Brian J.; Wood, Paul Chris; Li, Qingshun Quinn

    2005-01-01

    Using a novel program, SignalSleuth, and a database containing authenticated polyadenylation [poly(A)] sites, we analyzed the composition of mRNA poly(A) signals in Arabidopsis (Arabidopsis thaliana), and reevaluated previously described cis-elements within the 3′-untranslated (UTR) regions, including near upstream elements and far upstream elements. As predicted, there are absences of high-consensus signal patterns. The AAUAAA signal topped the near upstream elements patterns and was found within the predicted location to only approximately 10% of 3′-UTRs. More importantly, we identified a new set, named cleavage elements, of poly(A) signals flanking both sides of the cleavage site. These cis-elements were not previously revealed by conventional mutagenesis and are contemplated as a cluster of signals for cleavage site recognition. Moreover, a single-nucleotide profile scan on the 3′-UTR regions unveiled a distinct arrangement of alternate stretches of U and A nucleotides, which led to a prediction of the formation of secondary structures. Using an RNA secondary structure prediction program, mFold, we identified three main types of secondary structures on the sequences analyzed. Surprisingly, these observed secondary structures were all interrupted in previously constructed mutations in these regions. These results will enable us to revise the current model of plant poly(A) signals and to develop tools to predict 3′-ends for gene annotation. PMID:15965016

  10. DIRECT AND RESIDUAL EFFECTS OF CADMIUM ON THE GROWTH AND ELEMENTAL COMPOSITION OF 'ARABIDOPSIS THALIANA'

    EPA Science Inventory

    Experiments were conducted to determine the direct (first generation) and residual (second generation) phytotoxicity of a range of cadmium concentrations on Arabidopsis thaliana. Plants were grown under greenhouse conditions in double-container, vermiculite-hydroponic plot-cultur...

  11. Generalized Fibonacci photon sieves.

    PubMed

    Ke, Jie; Zhang, Junyong

    2015-08-20

    We successfully extend the standard Fibonacci zone plates with two on-axis foci to the generalized Fibonacci photon sieves (GFiPS) with multiple on-axis foci. We also propose the direct and inverse design methods based on the characteristic roots of the recursion relation of the generalized Fibonacci sequences. By switching the transparent and opaque zones, according to the generalized Fibonacci sequences, we not only realize adjustable multifocal distances but also fulfill the adjustable compression ratio of focal spots in different directions. PMID:26368763

  12. Cis-Regulatory Elements Determine Germline Specificity and Expression Level of an Isopentenyltransferase Gene in Sperm Cells of Arabidopsis.

    PubMed

    Zhang, Jinghua; Yuan, Tong; Duan, Xiaomeng; Wei, Xiaoping; Shi, Tao; Li, Jia; Russell, Scott D; Gou, Xiaoping

    2016-03-01

    Flowering plant sperm cells transcribe a divergent and complex complement of genes. To examine promoter function, we chose an isopentenyltransferase gene known as PzIPT1. This gene is highly selectively transcribed in one sperm cell morphotype of Plumbago zeylanica, which preferentially fuses with the central cell during fertilization and is thus a founding cell of the primary endosperm. In transgenic Arabidopsis (Arabidopsis thaliana), PzIPT1 promoter displays activity in both sperm cells and upon progressive promoter truncation from the 5'-end results in a progressive decrease in reporter production, consistent with occurrence of multiple enhancer sites. Cytokinin-dependent protein binding motifs are identified in the promoter sequence, which respond with stimulation by cytokinin. Expression of PzIPT1 promoter in sperm cells confers specificity independently of previously reported Germline Restrictive Silencer Factor binding sequence. Instead, a cis-acting regulatory region consisting of two duplicated 6-bp Male Gamete Selective Activation (MGSA) motifs occurs near the site of transcription initiation. Disruption of this sequence-specific site inactivates expression of a GFP reporter gene in sperm cells. Multiple copies of the MGSA motif fused with the minimal CaMV35S promoter elements confer reporter gene expression in sperm cells. Similar duplicated MGSA motifs are also identified from promoter sequences of sperm cell-expressed genes in Arabidopsis, suggesting selective activation is possibly a common mechanism for regulation of gene expression in sperm cells of flowering plants. PMID:26739233

  13. Identification of unique cis-element pattern on simulated microgravity treated Arabidopsis by in silico and gene expression

    NASA Astrophysics Data System (ADS)

    Soh, Hyuncheol; Choi, Yongsang; Lee, Taek-Kyun; Yeo, Up-Dong; Han, Kyeongsik; Auh, Chungkyun; Lee, Sukchan

    2012-08-01

    Arabidopsis gene expression microarray (44 K) was used to detect genes highly induced under simulated microgravity stress (SMS). Ten SMS-inducible genes were selected from the microarray data and these 10 genes were found to be abundantly expressed in 3-week-old plants. Nine out of the 10 SMS-inducible genes were also expressed in response to the three abiotic stresses of drought, touch, and wounding in 3-week-old Arabidopsis plants respectively. However, WRKY46 was elevated only in response to SMS. Six other WRKY genes did not respond to SMS. To clarify the characteristics of the genes expressed at high levels in response to SMS, 20 cis-elements in the promoters of the 40 selected genes including the 10 SMS-inducible genes, the 6 WRKY genes, and abiotic stress-inducible genes were analyzed and their spatial positions on each promoter were determined. Four cis-elements (M/T-G-T-P from MYB1AT or TATABOX5, GT1CONSENSUS, TATABOX5, and POLASIG1) showed a unique spatial arrangement in most SMS-inducible genes including WRKY46. Therefore the M/T-G-T-P cis-element patterns identified in the promoter of WRKY46 may play important roles in regulating gene expression in response to SMS. The presences of the cis-element patterns suggest that the order or spatial positioning of certain groups of cis-elements is more important than the existence or numbers of specific cis-elements. Taken together, our data indicate that WRKY46 is a novel SMS inducible transcription factor and the unique spatial arrangement of cis-elements shown in WRKY46 promoter may play an important role for its response to SMS.

  14. The Role of CAX1 and CAX3 in Elemental Distribution and Abundance in Arabidopsis Seed1[W][OA

    PubMed Central

    Punshon, Tracy; Hirschi, Kendal; Yang, Jian; Lanzirotti, Antonio; Lai, Barry; Guerinot, Mary Lou

    2012-01-01

    The ability to alter nutrient partitioning within plants cells is poorly understood. In Arabidopsis (Arabidopsis thaliana), a family of endomembrane cation exchangers (CAXs) transports Ca2+ and other cations. However, experiments have not focused on how the distribution and partitioning of calcium (Ca) and other elements within seeds are altered by perturbed CAX activity. Here, we investigate Ca distribution and abundance in Arabidopsis seed from cax1 and cax3 loss-of-function lines and lines expressing deregulated CAX1 using synchrotron x-ray fluorescence microscopy. We conducted 7- to 10-μm resolution in vivo x-ray microtomography on dry mature seed and 0.2-μm resolution x-ray microscopy on embryos from lines overexpressing deregulated CAX1 (35S-sCAX1) and cax1cax3 double mutants only. Tomograms showed an increased concentration of Ca in both the seed coat and the embryo in cax1, cax3, and cax1cax3 lines compared with the wild type. High-resolution elemental images of the mutants showed that perturbed CAX activity altered Ca partitioning within cells, reducing Ca partitioning into organelles and/or increasing Ca in the cytosol and abolishing tissue-level Ca gradients. In comparison with traditional volume-averaged metal analysis, which confirmed subtle changes in seed elemental composition, the collection of spatially resolved data at varying resolutions provides insight into the impact of altered CAX activity on seed metal distribution and indicates a cell type-specific function of CAX1 and CAX3 in partitioning Ca into organelles. This work highlights a powerful technology for inferring transport function and quantifying nutrient changes. PMID:22086421

  15. Space station molecular sieve development

    NASA Technical Reports Server (NTRS)

    Chang, C.; Rousseau, J.

    1986-01-01

    An essential function of a space environmental control system is the removal of carbon dioxide (CO2) from the atmosphere to control the partial pressure of this gas at levels lower than 3 mm Hg. The use of regenerable solid adsorbents for this purpose was demonstrated effectively during the Skylab mission. Earlier sorbent systems used zeolite molecular sieves. The carbon molecular sieve is a hydrophobic adsorbent with excellent potential for space station application. Although carbon molecular sieves were synthesized and investigated, these sieves were designed to simulate the sieving properties of 5A zeolite and for O2/N2 separation. This program was designed to develop hydrophobic carbon molecular sieves for CO2 removal from a space station crew environment. It is a first phase effort involved in sorbent material development and in demonstrating the utility of such a material for CO2 removal on space stations. The sieve must incorporate the following requirements: it must be hydrophobic; it must have high dynamic capacity for carbon dioxide at the low partial pressure of the space station atmosphere; and it must be chemiclly stable and will not generate contaminants.

  16. Molecular Sieve Regeneration System (MSRS)

    SciTech Connect

    Nasise, J.E.; Anderson, J.L. ); Naruse, Y. )

    1992-01-01

    A Molecular Sieve Regeneration System (MSRS) was added to the existing Tritium Waste Treatment system (TWT) within the Tritium Systems Test Assembly (TSTA) at Los Alamos National Laboratory. The Department of Energy (DOE) no longer allows inventory by difference'' for radioactive wastes that are to be buried. The MSRS was designed and built to comply with this requirement. Within the TWT, water is generated by the catalytic conversion of hydrogen isotopes and removed by molecular sieve trapping prior to release to the environment. Molecular sieve regeneration is required to remove the trapped water and to rejuvenate the beds. The MSRS permits the collection and direct tritium assay of regenerated tritiated water from molecular sieve beds. This paper describes the MSRS in detail and how it is interfaced with the TWT.

  17. Molecular Sieve Regeneration System (MSRS)

    SciTech Connect

    Nasise, J.E.; Anderson, J.L.; Naruse, Y.

    1992-03-01

    A Molecular Sieve Regeneration System (MSRS) was added to the existing Tritium Waste Treatment system (TWT) within the Tritium Systems Test Assembly (TSTA) at Los Alamos National Laboratory. The Department of Energy (DOE) no longer allows ``inventory by difference`` for radioactive wastes that are to be buried. The MSRS was designed and built to comply with this requirement. Within the TWT, water is generated by the catalytic conversion of hydrogen isotopes and removed by molecular sieve trapping prior to release to the environment. Molecular sieve regeneration is required to remove the trapped water and to rejuvenate the beds. The MSRS permits the collection and direct tritium assay of regenerated tritiated water from molecular sieve beds. This paper describes the MSRS in detail and how it is interfaced with the TWT.

  18. Genome-wide comparative analysis of the transposable elements in the related species Arabidopsis thaliana and Brassica oleracea.

    PubMed

    Zhang, Xiaoyu; Wessler, Susan R

    2004-04-13

    Transposable elements (TEs) are the major component of plant genomes where they contribute significantly to the >1,000-fold genome size variation. To understand the dynamics of TE-mediated genome expansion, we have undertaken a comparative analysis of the TEs in two related organisms: the weed Arabidopsis thaliana (125 megabases) and Brassica oleracea ( approximately 600 megabases), a species with many crop plants. Comparison of the whole genome sequence of A. thaliana with a partial draft of B. oleracea has permitted an estimation of the patterns of TE amplification, diversification, and loss that has occurred in related species since their divergence from a common ancestor. Although we find that nearly all TE lineages are shared, the number of elements in each lineage is almost always greater in B. oleracea. Class 1 (retro) elements are the most abundant TE class in both species with LTR and non-LTR elements comprising the largest fraction of each genome. However, several families of class 2 (DNA) elements have amplified to very high copy number in B. oleracea where they have contributed significantly to genome expansion. Taken together, the results of this analysis indicate that amplification of both class 1 and class 2 TEs is responsible, in part, for B. oleracea genome expansion since divergence from a common ancestor with A. thaliana. In addition, the observation that B. oleracea and A. thaliana share virtually all TE lineages makes it unlikely that wholesale removal of TEs is responsible for the compact genome of A. thaliana. PMID:15064405

  19. A Transposable Element within the Non-canonical Telomerase RNA of Arabidopsis thaliana Modulates Telomerase in Response to DNA Damage

    PubMed Central

    Xu, Hengyi; Nelson, Andrew D. L.; Shippen, Dorothy E.

    2015-01-01

    Long noncoding RNAs (lncRNAs) have emerged as critical factors in many biological processes, but little is known about how their regulatory functions evolved. One of the best-studied lncRNAs is TER, the essential RNA template for telomerase reverse transcriptase. We previously showed that Arabidopsis thaliana harbors three TER isoforms: TER1, TER2 and TER2S. TER1 serves as a canonical telomere template, while TER2 is a novel negative regulator of telomerase activity, induced in response to double-strand breaks (DSBs). TER2 contains a 529 nt intervening sequence that is removed along with 36 nt at the RNA 3’ terminus to generate TER2S, an RNA of unknown function. Here we investigate how A. thaliana TER2 acquired its regulatory function. Using data from the 1,001 Arabidopsis genomes project, we report that the intervening sequence within TER2 is derived from a transposable element termed DSB responsive element (DRE). DRE is found in the TER2 loci of most but not all A. thaliana accessions. By analyzing accessions with (TER2) and without DRE (TER2Δ) we demonstrate that this element is responsible for many of the unique properties of TER2, including its enhanced binding to TERT and telomerase inhibitory function. We show that DRE destabilizes TER2, and further that TER2 induction by DNA damage reflects increased RNA stability and not increased transcription. DRE-mediated changes in TER2 stability thus provide a rapid and sensitive switch to fine-tune telomerase enzyme activity. Altogether, our data shows that invasion of the TER2 locus by a small transposon converted this lncRNA into a DNA damage sensor that modulates telomerase enzyme activity in response to genome assault. PMID:26075395

  20. HDA6 Directly Interacts with DNA Methyltransferase MET1 and Maintains Transposable Element Silencing in Arabidopsis1[W][OA

    PubMed Central

    Liu, Xuncheng; Yu, Chun-Wei; Duan, Jun; Luo, Ming; Wang, Koching; Tian, Gang; Cui, Yuhai; Wu, Keqiang

    2012-01-01

    The molecular mechanism of how the histone deacetylase HDA6 participates in maintaining transposable element (TE) silencing in Arabidopsis (Arabidopsis thaliana) is not yet defined. In this study, we show that a subset of TEs was transcriptionally reactivated and that TE reactivation was associated with elevated histone H3 and H4 acetylation as well as increased H3K4Me3 and H3K4Me2 in hda6 mutants. Decreased DNA methylation of the TEs was also detected in hda6 mutants, suggesting that HDA6 silences the TEs by regulating histone acetylation and methylation as well as the DNA methylation status of the TEs. Similarly, transcripts of some of these TEs were also increased in the methyltransferase1 (met1) mutant, with decreased DNA methylation. Furthermore, H4 acetylation, H3K4Me3, H3K4Me2, and H3K36Me2 were enriched at the coregulated TEs in the met1 and hda6 met1 mutants. Protein-protein interaction analysis indicated that HDA6 physically interacts with MET1 in vitro and in vivo, and further deletion analysis demonstrated that the carboxyl-terminal region of HDA6 and the bromo-adjacent homology domain of MET1 were responsible for the interaction. These results suggested that HDA6 and MET1 interact directly and act together to silence TEs by modulating DNA methylation, histone acetylation, and histone methylation status. PMID:21994348

  1. Discrete spatial and temporal cis-acting elements regulate transcription of the Arabidopsis floral homeotic gene APETALA3.

    PubMed

    Hill, T A; Day, C D; Zondlo, S C; Thackeray, A G; Irish, V F

    1998-05-01

    The APETALA3 floral homeotic gene is required for petal and stamen development in Arabidopsis. APETALA3 transcripts are first detected in a meristematic region that will give rise to the petal and stamen primordia, and expression is maintained in this region during subsequent development of these organs. To dissect how the APETALA3 gene is expressed in this spatially and temporally restricted domain, various APETALA3 promoter fragments were fused to the uidA reporter gene encoding beta-glucuronidase and assayed for the resulting patterns of expression in transgenic Arabidopsis plants. Based on these promoter analyses, we defined cis-acting elements required for distinct phases of APETALA3 expression, as well as for petal-specific and stamen-specific expression. By crossing the petal-specific construct into different mutant backgrounds, we have shown that several floral genes, including APETALA3, PISTILLATA, UNUSUAL FLORAL ORGANS, and APETALA1, encode trans-acting factors required for second-whorl-specific APETALA3 expression. We have also shown that the products of the APETALA1, APETALA3, PISTILLATA and AGAMOUS genes bind to several conserved sequence motifs within the APETALA3 promoter. We present a model whereby spatially and temporally restricted APETALA3 transcription is controlled via interactions between proteins binding to different domains of the APETALA3 promoter. PMID:9521909

  2. Analysis of changes in relative elemental growth rate patterns in the elongation zone of Arabidopsis roots upon gravistimulation

    NASA Technical Reports Server (NTRS)

    Mullen, J. L.; Ishikawa, H.; Evans, M. L.

    1998-01-01

    Although Arabidopsis is an important system for studying root physiology, the localized growth patterns of its roots have not been well defined, particularly during tropic responses. In order to characterize growth rate profiles along the apex of primary roots of Arabidopsis thaliana (L.) Heynh (ecotype Columbia) we applied small charcoal particles to the root surface and analyzed their displacement during growth using an automated video digitizer system with custom software for tracking the markers. When growing vertically, the maximum elongation rate occurred 481 +/- 50 microns back from the extreme tip of the root (tip of root cap), and the elongation zone extended back to 912 +/- 137 microns. The distal elongation zone (DEZ) has previously been described as the apical region of the elongation zone in which the relative elemental growth rate (REGR) is < or = 30% of the peak rate in the central elongation zone. By this definition, our data indicate that the basal limit of the DEZ was located 248 +/- 30 microns from the root tip. However, after gravistimulation, the growth patterns of the root changed. Within the first hour of graviresponse, the basal limit of the DEZ and the position of peak REGR shifted apically on the upper flank of the root. This was due to a combination of increased growth in the DEZ and growth inhibition in the central elongation zone. On the lower flank, the basal limit of the DEZ shifted basipetally as the REGR decreased. These factors set up the gradient of growth rate across the root, which drives curvature.

  3. Antagonistic Gene Activities Determine the Formation of Pattern Elements along the Mediolateral Axis of the Arabidopsis Fruit

    PubMed Central

    González-Reig, Santiago; Ripoll, Juan José; Vera, Antonio; Yanofsky, Martin F.; Martínez-Laborda, Antonio

    2012-01-01

    The Arabidopsis fruit mainly consists of a mature ovary that shows three well defined territories that are pattern elements along the mediolateral axis: the replum, located at the medial plane of the flower, and the valve and the valve margin, both of lateral nature. JAG/FIL activity, which includes the combined functions of JAGGED (JAG), FILAMENTOUS FLOWER (FIL), and YABBY3 (YAB3), contributes to the formation of the two lateral pattern elements, whereas the cooperating genes BREVIPEDICELLUS (BP) and REPLUMLESS (RPL) promote replum development. A recent model to explain pattern formation along the mediolateral axis hypothesizes that JAG/FIL activity and BP/RPL function as antagonistic lateral and medial factors, respectively, which tend to repress each other. In this work, we demonstrate the existence of mutual exclusion mechanisms between both kinds of factors, and how this determines the formation and size of the three territories. Medial factors autonomously constrain lateral factors so that they only express outside the replum, and lateral factors negatively regulate the medially expressed BP gene in a non-autonomous fashion to ensure correct replum development. We also have found that ASYMMETRIC LEAVES1 (AS1), previously shown to repress BP both in leaves and ovaries, collaborates with JAG/FIL activity, preventing its repression by BP and showing synergistic interactions with JAG/FIL activity genes. Therefore AS gene function (the function of the interacting genes AS1 and AS2) has been incorporated in the model as a new lateral factor. Our model of antagonistic factors provides explanation for mutant fruit phenotypes in Arabidopsis and also may help to understand natural variation of fruit shape in Brassicaceae and other species, since subtle changes in gene expression may cause conspicuous changes in the size of the different tissue types. PMID:23133401

  4. Ultra-broadband achromatic imaging with diffractive photon sieves

    PubMed Central

    Zhao, Xiaonan; Hu, Jingpei; Lin, Yu; Xu, Feng; Zhu, Xiaojun; Pu, Donglin; Chen, Linsen; Wang, Chinhua

    2016-01-01

    Diffractive optical elements suffer from large chromatic aberration due to the strong wavelength-dependent nature in diffraction phenomena, and therefore, diffractive elements can work only at a single designed wavelength, which significantly limits the applications of diffractive elements in imaging. Here, we report on a demonstration of a wavefront coded broadband achromatic imaging with diffractive photon sieves. The broadband diffraction imaging is implemented with a wavefront coded pinhole pattern that generates equal focusing power for a wide range of operating wavelength in a single thin-film element without complicated auxiliary optical system. Experimental validation was performed using an UV-lithography fabricated wavefront coded photon sieves. Results show that the working bandwidth of the wavefront coded photon sieves reaches 28 nm compared with 0.32 nm of the conventional one. Further demonstration of the achromatic imaging with a bandwidth of 300 nm is also performed with a wavefront coded photon sieves integrated with a refractive element. PMID:27328713

  5. Ultra-broadband achromatic imaging with diffractive photon sieves.

    PubMed

    Zhao, Xiaonan; Hu, Jingpei; Lin, Yu; Xu, Feng; Zhu, Xiaojun; Pu, Donglin; Chen, Linsen; Wang, Chinhua

    2016-01-01

    Diffractive optical elements suffer from large chromatic aberration due to the strong wavelength-dependent nature in diffraction phenomena, and therefore, diffractive elements can work only at a single designed wavelength, which significantly limits the applications of diffractive elements in imaging. Here, we report on a demonstration of a wavefront coded broadband achromatic imaging with diffractive photon sieves. The broadband diffraction imaging is implemented with a wavefront coded pinhole pattern that generates equal focusing power for a wide range of operating wavelength in a single thin-film element without complicated auxiliary optical system. Experimental validation was performed using an UV-lithography fabricated wavefront coded photon sieves. Results show that the working bandwidth of the wavefront coded photon sieves reaches 28 nm compared with 0.32 nm of the conventional one. Further demonstration of the achromatic imaging with a bandwidth of 300 nm is also performed with a wavefront coded photon sieves integrated with a refractive element. PMID:27328713

  6. Functional analysis of the Arabidopsis PLDZ2 promoter reveals an evolutionarily conserved low-Pi-responsive transcriptional enhancer element

    PubMed Central

    Oropeza-Aburto, Araceli; Cruz-Ramírez, Alfredo; Acevedo-Hernández, Gustavo J.; Pérez-Torres, Claudia-Anahí; Caballero-Pérez, Juan; Herrera-Estrella, Luis

    2012-01-01

    Plants have evolved a plethora of responses to cope with phosphate (Pi) deficiency, including the transcriptional activation of a large set of genes. Among Pi-responsive genes, the expression of the Arabidopsis phospholipase DZ2 (PLDZ2) is activated to participate in the degradation of phospholipids in roots in order to release Pi to support other cellular activities. A deletion analysis was performed to identify the regions determining the strength, tissue-specific expression, and Pi responsiveness of this regulatory region. This study also reports the identification and characterization of a transcriptional enhancer element that is present in the PLDZ2 promoter and able to confer Pi responsiveness to a minimal, inactive 35S promoter. This enhancer also shares the cytokinin and sucrose responsive properties observed for the intact PLDZ2 promoter. The EZ2 element contains two P1BS motifs, each of which is the DNA binding site of transcription factor PHR1. Mutation analysis showed that the P1BS motifs present in EZ2 are necessary but not sufficient for the enhancer function, revealing the importance of adjacent sequences. The structural organization of EZ2 is conserved in the orthologous genes of at least eight families of rosids, suggesting that architectural features such as the distance between the two P1BS motifs are also important for the regulatory properties of this enhancer element. PMID:22210906

  7. Tomato ovary-to-fruit transition is characterized by a spatial shift of mRNAs for cell wall invertase and its inhibitor with the encoded proteins localized to sieve elements.

    PubMed

    Palmer, William M; Ru, Lei; Jin, Ye; Patrick, John W; Ruan, Yong-Ling

    2015-02-01

    Central to understanding fruit development is to elucidate the processes mediating a successful transition from pre-pollination ovaries to newly set fruit, a key step in establishing fruit yield potential. In tomato, cell wall invertase (CWIN) LIN5 and its inhibitor INH1 are essential for fruit growth. However, the molecular and cellular basis by which they exert their roles in ovary-to-fruit transition remains unknown. To address this issue, we conducted a study focusing on ovaries and fruitlets at 2 days before and 2 days after anthesis, respectively. In situ hybridization analyses revealed that LIN5 and INH1 exhibited a dispersed expression in ovaries compared with their phloem-specific expression in fruitlets. Remarkably, LIN5 and INH1 proteins were immunologically co-localized to cell walls of sieve elements (SEs) in ovaries immediately prior to anthesis and in young fruitlets, but were undetectable in provascular bundles of younger ovaries. A burst in CWIN activity occurred during ovary-to-fruit transition. Interestingly, the ovaries, but not the fruitlets, exhibited high expression of a defective invertase, SldeCWIN1, an ortholog of which is known to enhance inhibition of INH on CWIN activity in tobacco. Imaging of a fluorescent symplasmic tracer indicated an apoplasmic phloem unloading pathway operated in ovaries, contrary to the previously observed symplasmic unloading pathway in fruit pericarp. These new data indicate that (1) a phloem-specific patterning of the CWIN and INH mRNAs is induced during ovary-to-fruit transition, and (2) LIN5 protein functions specifically in walls of SEs and increases its activity during ovary-to-fruit transition, probably to facilitate phloem unloading and to generate a glucose signal positively regulating cell division, hence fruit set. PMID:25680776

  8. Mesh Algorithms for PDE with Sieve I: Mesh Distribution

    DOE PAGESBeta

    Knepley, Matthew G.; Karpeev, Dmitry A.

    2009-01-01

    We have developed a new programming framework, called Sieve, to support parallel numerical partial differential equation(s) (PDE) algorithms operating over distributed meshes. We have also developed a reference implementation of Sieve in C++ as a library of generic algorithms operating on distributed containers conforming to the Sieve interface. Sieve makes instances of the incidence relation, or arrows, the conceptual first-class objects represented in the containers. Further, generic algorithms acting on this arrow container are systematically used to provide natural geometric operations on the topology and also, through duality, on the data. Finally, coverings and duality are used to encode notmore » only individual meshes, but all types of hierarchies underlying PDE data structures, including multigrid and mesh partitions. In order to demonstrate the usefulness of the framework, we show how the mesh partition data can be represented and manipulated using the same fundamental mechanisms used to represent meshes. We present the complete description of an algorithm to encode a mesh partition and then distribute a mesh, which is independent of the mesh dimension, element shape, or embedding. Moreover, data associated with the mesh can be similarly distributed with exactly the same algorithm. The use of a high level of abstraction within the Sieve leads to several benefits in terms of code reuse, simplicity, and extensibility. We discuss these benefits and compare our approach to other existing mesh libraries.« less

  9. The Arabidopsis Xylem Peptidase XCP1 Is a Tracheary Element Vacuolar Protein That May Be a Papain Ortholog1

    PubMed Central

    Funk, Vanessa; Kositsup, Boonthida; Zhao, Chengsong; Beers, Eric P.

    2002-01-01

    XCP1 is a xylem-specific papain-like cysteine peptidase in Arabidopsis. To determine whether XCP1 could be involved in tracheary element autolysis, promoter activity and localization of XCP1 were investigated using XCP1 promoter-β-glucuronidase fusions and immunofluorescence confocal microscopy. A tracheary element expression pattern was detected for XCP1. Results from confocal microscopy and biochemical subcellular fractionation indicated that XCP1 was localized in the vacuole. Ectopic expression of XCP1 resulted in a reduction in plant size in some lines and early leaf senescence, as indicated by early loss of leaf chlorophyll. Reduced plant size was correlated with higher levels of XCP1, as shown by immunoblot and peptidase activity gel analyses. The XCP1 prodomain exhibits exceptionally high similarity (greater than 80%) to the prodomains of papain and other papain-like enzymes isolated from papaya (Carica papaya) laticifers when compared with all other reported papain-like enzymes. The potential for XCP1 and papain to perform common functions as catalysts of autolytic processing following cell death due to programmed suicide or to wounding is discussed. PMID:11788755

  10. Biodiversity of mineral nutrient and trace element accumulation in Arabidopsis thaliana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order to grow on soils that vary widely in chemical composition, plants have evolved mechanisms for regulating the elemental composition of their tissues to balance the mineral nutrient and trace element bioavailability in the soil with the requirements of the plant for growth and development. T...

  11. Activation of Tag1 transposable elements in Arabidopsis dedifferentiating cells and their regulation by CHROMOMETHYLASE 3-mediated CHG methylation.

    PubMed

    Khan, Asif; Yadav, Narendra Singh; Morgenstern, Yaakov; Zemach, Assaf; Grafi, Gideon

    2016-10-01

    Dedifferentiation, that is, the acquisition of stem cell-like state, commonly induced by stress (e.g., protoplasting), is characterized by open chromatin conformation, a chromatin state that could lead to activation of transposable elements (TEs). Here, we studied the activation of the Arabidopsis class II TE Tag1, in which two copies, situated close to each other (near genes) on chromosome 1 are found in Landsberg erecta (Ler) but not in Columbia (Col). We first transformed protoplasts with a construct in which a truncated Tag1 (ΔTag1 non-autonomous) blocks the expression of a reporter gene AtMBD5-GFP and found a relatively high ectopic excision of ΔTag1 accompanied by expression of AtMBD5-GFP in protoplasts derived from Ler compared to Col; further increase was observed in ddm1 (decrease in DNA methylation1) protoplasts (Ler background). Ectopic excision was associated with transcription of the endogenous Tag1 and changes in histone H3 methylation at the promoter region. Focusing on the endogenous Tag1 elements we found low level of excision in Ler protoplasts, which was slightly and strongly enhanced in ddm1 and cmt3 (chromomethylase3) protoplasts, respectively, concomitantly with reduction in Tag1 gene body (GB) CHG methylation and increased Tag1 transcription; strong activation of Tag1 was also observed in cmt3 leaves. Notably, in cmt3, but not in ddm1, Tag1 elements were excised out from their original sites and transposed elsewhere in the genome. Our results suggest that dedifferentiation is associated with Tag1 activation and that CMT3 rather than DDM1 plays a central role in restraining Tag1 activation via inducing GB CHG methylation. PMID:27475038

  12. Niobate-based octahedral molecular sieves

    DOEpatents

    Nenoff, Tina M.; Nyman, May D.

    2006-10-17

    Niobate-based octahedral molecular sieves having significant activity for multivalent cations and a method for synthesizing such sieves are disclosed. The sieves have a net negatively charged octahedral framework, comprising niobium, oxygen, and octahedrally coordinated lower valence transition metals. The framework can be charge balanced by the occluded alkali cation from the synthesis method. The alkali cation can be exchanged for other contaminant metal ions. The ion-exchanged niobate-based octahedral molecular sieve can be backexchanged in acidic solutions to yield a solution concentrated in the contaminant metal. Alternatively, the ion-exchanged niobate-based octahedral molecular sieve can be thermally converted to a durable perovskite phase waste form.

  13. Niobate-based octahedral molecular sieves

    DOEpatents

    Nenoff, Tina M.; Nyman, May D.

    2003-07-22

    Niobate-based octahedral molecular sieves having significant activity for multivalent cations and a method for synthesizing such sieves are disclosed. The sieves have a net negatively charged octahedral framework, comprising niobium, oxygen, and octahedrally coordinated lower valence transition metals. The framework can be charge balanced by the occluded alkali cation from the synthesis method. The alkali cation can be exchanged for other contaminant metal ions. The ion-exchanged niobate-based octahedral molecular sieve can be backexchanged in acidic solutions to yield a solution concentrated in the contaminant metal. Alternatively, the ion-exchanged niobate-based octahedral molecular sieve can be thermally converted to a durable perovskite phase waste form.

  14. The Inheritance Pattern of 24 nt siRNA Clusters in Arabidopsis Hybrids Is Influenced by Proximity to Transposable Elements

    PubMed Central

    Li, Ying; Varala, Kranthi; Moose, Stephen P.; Hudson, Matthew E.

    2012-01-01

    Hybrids often display increased size and growth, and thus are widely cultivated in agriculture and horticulture. Recent discoveries demonstrating the important regulatory roles of small RNAs have greatly improved our understanding of many basic biological questions, and could illuminate the molecular basis for the enhanced growth and size of hybrid plants. We profiled small RNAs by deep sequencing to characterize the inheritance patterns of small RNA levels in reciprocal hybrids of two Arabidopsis thaliana accessions, Columbia and Landsberg erecta. We find 24-nt siRNAs predominate among those small RNAs that are differentially expressed between the parents. Following hybridization, the transposable element (TE)-derived siRNAs are often inherited in an additive manner, whereas siRNAs associated with protein-coding genes are often down-regulated in hybrids to the levels observed for the parent with lower relative siRNA levels. Among the protein-coding genes that exhibit this pattern, genes that function in pathogen defense, abiotic stress tolerance, and secondary metabolism are significantly enriched. Small RNA clusters from protein-coding genes where a TE is present within one kilobase show a different predominant inheritance pattern (additive) from those that do not (low-parent dominance). Thus, down-regulation in the form of low-parent dominance is likely the default pattern of inheritance for genic siRNA, and a different inheritance mechanism for TE siRNA is suggested. PMID:23118865

  15. Proteomic Analysis of Microtubule Interacting Proteins over the Course of Xylem Tracheary Element Formation in Arabidopsis[OPEN

    PubMed Central

    Buschmann, Henrik; Lloyd, Clive W.

    2015-01-01

    Plant vascular cells, or tracheary elements (TEs), rely on circumferential secondary cell wall thickenings to maintain sap flow. The patterns in which TE thickenings are organized vary according to the underlying microtubule bundles that guide wall deposition. To identify microtubule interacting proteins present at defined stages of TE differentiation, we exploited the synchronous differentiation of TEs in Arabidopsis thaliana suspension cultures. Quantitative proteomic analysis of microtubule pull-downs, using ratiometric 14N/15N labeling, revealed 605 proteins exhibiting differential accumulation during TE differentiation. Microtubule interacting proteins associated with membrane trafficking, protein synthesis, DNA/RNA binding, and signal transduction peaked during secondary cell wall formation, while proteins associated with stress peaked when approaching TE cell death. In particular, CELLULOSE SYNTHASE-INTERACTING PROTEIN1, already associated with primary wall synthesis, was enriched during secondary cell wall formation. RNAi knockdown of genes encoding several of the identified proteins showed that secondary wall formation depends on the coordinated presence of microtubule interacting proteins with nonoverlapping functions: cell wall thickness, cell wall homogeneity, and the pattern and cortical location of the wall are dependent on different proteins. Altogether, proteins linking microtubules to a range of metabolic compartments vary specifically during TE differentiation and regulate different aspects of wall patterning. PMID:26432860

  16. Multiprocessing the Sieve of Eratosthenes

    SciTech Connect

    Bokhari, S.H.

    1987-04-01

    More than two thousand years ago, Eratosthenes of Cyrene described a procedure for finding all prime numbers in a given range. This straightforward algorithm, known as the Sieve of Eratosthenes, is to this day the only procedure for finding prime numbers. In recent years it has been of interest to computer scientists and engineers because it serves as a convenient benchmark against which to measure some aspects of a computer's performance. Specifically, the Sieve tests the power of a machine (or of a compiler) to access a very large array in memory rapidly and repeatedly. This power is clearly influenced by memory access time, the speed at which indexing is done, and the overhead of looping. The parallel version of the Sieve is very useful as a test of some of the capabilities of a parallel machine. The parallel algorithm is straightforward, and so is the process for checking the final results. However, the efficient implementation of the algorithm on a real parallel machine, especially in the dynamic load-balancing case, requires thoughtful design.

  17. Preparation of amorphous sulfide sieves

    DOEpatents

    Siadati, Mohammad H.; Alonso, Gabriel; Chianelli, Russell R.

    2006-11-07

    The present invention involves methods and compositions for synthesizing catalysts/porous materials. In some embodiments, the resulting materials are amorphous sulfide sieves that can be mass-produced for a variety of uses. In some embodiments, methods of the invention concern any suitable precursor (such as thiomolybdate salt) that is exposed to a high pressure pre-compaction, if need be. For instance, in some cases the final bulk shape (but highly porous) may be same as the original bulk shape. The compacted/uncompacted precursor is then subjected to an open-flow hot isostatic pressing, which causes the precursor to decompose and convert to a highly porous material/catalyst.

  18. Cis-Regulatory Elements Determine Germline Specificity and Expression Level of an Isopentenyltransferase Gene in Sperm Cells of Arabidopsis1[OPEN

    PubMed Central

    Yuan, Tong; Duan, Xiaomeng; Wei, Xiaoping; Li, Jia

    2016-01-01

    Flowering plant sperm cells transcribe a divergent and complex complement of genes. To examine promoter function, we chose an isopentenyltransferase gene known as PzIPT1. This gene is highly selectively transcribed in one sperm cell morphotype of Plumbago zeylanica, which preferentially fuses with the central cell during fertilization and is thus a founding cell of the primary endosperm. In transgenic Arabidopsis (Arabidopsis thaliana), PzIPT1 promoter displays activity in both sperm cells and upon progressive promoter truncation from the 5′-end results in a progressive decrease in reporter production, consistent with occurrence of multiple enhancer sites. Cytokinin-dependent protein binding motifs are identified in the promoter sequence, which respond with stimulation by cytokinin. Expression of PzIPT1 promoter in sperm cells confers specificity independently of previously reported Germline Restrictive Silencer Factor binding sequence. Instead, a cis-acting regulatory region consisting of two duplicated 6-bp Male Gamete Selective Activation (MGSA) motifs occurs near the site of transcription initiation. Disruption of this sequence-specific site inactivates expression of a GFP reporter gene in sperm cells. Multiple copies of the MGSA motif fused with the minimal CaMV35S promoter elements confer reporter gene expression in sperm cells. Similar duplicated MGSA motifs are also identified from promoter sequences of sperm cell-expressed genes in Arabidopsis, suggesting selective activation is possibly a common mechanism for regulation of gene expression in sperm cells of flowering plants. PMID:26739233

  19. Multiprocessing the Sieve of Eratosthenes

    NASA Technical Reports Server (NTRS)

    Bokhari, S.

    1986-01-01

    The Sieve of Eratosthenes for finding prime numbers in recent years has seen much use as a benchmark algorithm for serial computers while its intrinsically parallel nature has gone largely unnoticed. The implementation of a parallel version of this algorithm for a real parallel computer, the Flex/32, is described and its performance discussed. It is shown that the algorithm is sensitive to several fundamental performance parameters of parallel machines, such as spawning time, signaling time, memory access, and overhead of process switching. Because of the nature of the algorithm, it is impossible to get any speedup beyond 4 or 5 processors unless some form of dynamic load balancing is employed. We describe the performance of our algorithm with and without load balancing and compare it with theoretical lower bounds and simulated results. It is straightforward to understand this algorithm and to check the final results. However, its efficient implementation on a real parallel machine requires thoughtful design, especially if dynamic load balancing is desired. The fundamental operations required by the algorithm are very simple: this means that the slightest overhead appears prominently in performance data. The Sieve thus serves not only as a very severe test of the capabilities of a parallel processor but is also an interesting challenge for the programmer.

  20. Common and unique elements of the ABA-regulated transcriptome of Arabidopsis guard cells

    PubMed Central

    2011-01-01

    , the type 2C protein phosphatases. Our data also provide evidence for cross-talk at the transcriptional level between ABA and another hormonal inhibitor of stomatal opening, methyl jasmonate. Conclusions Our results engender new insights into the basic cell biology of guard cells, reveal common and unique elements of ABA-regulation of gene expression in guard cells, and set the stage for targeted biotechnological manipulations to improve plant water use efficiency. PMID:21554708

  1. Arabidopsis thaliana—Myzus persicae interaction: shaping the understanding of plant defense against phloem-feeding aphids

    PubMed Central

    Louis, Joe; Shah, Jyoti

    2013-01-01

    The phloem provides a unique niche for several organisms. Aphids are a large group of Hemipteran insects that utilize stylets present in their mouthparts to pierce sieve elements and drink large volumes of phloem sap. In addition, many aphids also vector viral diseases. Myzus persicae, commonly known as the green peach aphid (GPA), is an important pest of a large variety of plants that includes Arabidopsis thaliana. This review summarizes recent studies that have exploited the compatible interaction between Arabidopsis and GPA to understand the molecular and physiological mechanisms utilized by plants to control aphid infestation, as well as genes and mechanisms that contribute to susceptibility. In addition, recent efforts to identify aphid-delivered elicitors of plant defenses and novel aphid salivary components that facilitate infestation are also discussed. PMID:23847627

  2. An artificial compound eye of photon Sieves

    NASA Astrophysics Data System (ADS)

    Jiang, Wenbo; Hu, Song; He, Yu; Bu, Yun

    2015-11-01

    The compound eye of insects has numerous extraordinary optical performances, such as minimum chromatic aberration, wide-angle field of view, and high sensitivity to the incidence light. Inspired by these unique performances, we present a novel artificial compound eye of photon sieves in this paper, where the photon sieves play the roles of insects' ommatidia. These photon sieves have the same focal length. The incidence light can be focused into the same focal plane and produce the superposition effect, the utilization ratio of energy can be largely improved. Through the numerical simulation, the results show that this novel structure has similar focusing performance with the conventional photon sieves, but has higher utilization ratio of energy and wider angle field of view than that of the conventional photon sieves. Our findings provide a new direction for optics and biology researchers, which will be beneficial for medical imaging, astronomy, etc.

  3. Aphid salivary proteases are capable of degrading sieve-tube proteins.

    PubMed

    Furch, Alexandra C U; van Bel, Aart J E; Will, Torsten

    2015-02-01

    Sieve tubes serve as transport conduits for photo-assimilates and other resources in angiosperms and are profitable targets for piercing-sucking insects such as aphids. Sieve-tube sap also contains significant amounts of proteins with diverse functions, for example in signalling, metabolism, and defence. The identification of salivary proteases in Acyrthosiphon pisum led to the hypothesis that aphids might be able to digest these proteins and by doing so suppress plant defence and access additional nitrogen sources. Here, the scarce knowledge of proteases in aphid saliva is briefly reviewed. In order to provide a better platform for discussion, we conducted a few tests on in vitro protease activity and degradation of sieve-tube sap proteins of Cucurbita maxima by watery saliva. Inhibition of protein degradation by EDTA indicates the presence of different types of proteases (e.g. metalloproteses) in saliva of A. pisum. Proteases in the watery saliva from Macrosiphum euphorbiae and A. pisum were able to degrade the most abundant phloem protein, which is phloem protein 1. Our results provide support for the breakdown of sieve-element proteins by aphid saliva in order to suppress/neutralize the defence responses of the plant and to make proteins of sieve-tube sap accessible as a nitrogen source, as is discussed in detail. Finally, we discuss whether glycosylation of sieve-element proteins and the presence of protease inhibitors may confer partial protection against the proteolytic activity of aphid saliva. PMID:25540441

  4. Rapid Transcriptome Changes Induced by Cytosolic Ca2+ Transients Reveal ABRE-Related Sequences as Ca2+-Responsive cis Elements in Arabidopsis[W

    PubMed Central

    Kaplan, Boaz; Davydov, Olga; Knight, Heather; Galon, Yael; Knight, Marc R.; Fluhr, Robert; Fromm, Hillel

    2006-01-01

    The regulation of gene expression by cellular calcium is crucial for plant defense against biotic and abiotic stresses. However, the number of genes known to respond to specific transient calcium signals is limited, and as yet there is no definition of a calcium-responsive cis element in plants. Here, we generated specific cytosolic calcium transients in intact Arabidopsis thaliana seedlings and linked them to early transcriptome changes, followed by bioinformatic analysis of the responsive genes. A cytosolic calcium transient induced by calmodulin antagonists and blocked by lanthanides was characterized using aequorin-based luminometry and photon imaging. Analysis of transcriptome changes revealed 230 calcium-responsive genes, of which 162 were upregulated and 68 were downregulated. These include known early stress-responsive genes as well as genes of unknown function. Analysis of their upstream regions revealed, exclusively in the upregulated genes, a highly significant occurrence of a consensus sequence (P < 10−13) comprising two abscisic acid–specific cis elements: the abscisic acid–responsive element (ABRE; CACGTG[T/C/G]) and its coupling element ([C/A]ACGCG[T/C/A]). Finally, we show that a tetramer of the ABRE cis element is sufficient to confer transcriptional activation in response to cytosolic Ca2+ transients. Thus, at least for some specific Ca2+ transients and motif combinations, ABREs function as Ca2+-responsive cis elements. PMID:16980540

  5. Enhanced Molecular Sieve CO2 Removal Evaluation

    NASA Technical Reports Server (NTRS)

    Rose, Susan; ElSherif, Dina; MacKnight, Allen

    1996-01-01

    The objective of this research is to quantitatively characterize the performance of two major types of molecular sieves for two-bed regenerative carbon dioxide removal at the conditions compatible with both a spacesuit and station application. One sorbent is a zeolite-based molecular sieve that has been substantially improved over the materials used in Skylab. The second sorbent is a recently developed carbon-based molecular sieve. Both molecular sieves offer the potential of high payoff for future manned missions by reducing system complexity, weight (including consumables), and power consumption in comparison with competing concepts. The research reported here provides the technical data required to improve CO2 removal systems for regenerative life support systems for future IVA and EVA missions.

  6. Carbon fiber composite molecular sieves

    SciTech Connect

    Burchell, T.D.; Rogers, M.R.; Williams, A.M.

    1996-06-01

    The removal of CO{sub 2} is of significance in several energy applications. The combustion of fossil fuels, such as coal or natural gas, releases large volumes of CO{sub 2} to the environment. Several options exist to reduce CO{sub 2} emissions, including substitution of nuclear power for fossil fuels, increasing the efficiency of fossil plants and capturing the CO{sub 2} prior to emission to the environment. All of these techniques have the attractive feature of limiting the amount of CO{sub 2} emitted to the atmosphere, but each has economic, technical, or societal limitations. In the production of natural gas, the feed stream from the well frequently contains contaminants and diluents which must be removed before the gas can enter the pipeline distribution system. Notable amongst these diluent gasses is CO{sub 2}, which has no calorific value. Currently, the pipeline specification calls for <2 mol % CO{sub 2} in the gas. Gas separation is thus a relevant technology in the field of energy production. A novel separation system based on a parametric swing process has been developed that utilizes the unique combination of properties exhibited by our carbon fiber composite molecular sieve (CFCMS).

  7. The Arabidopsis floral homeotic gene PISTILLATA is regulated by discrete cis-elements responsive to induction and maintenance signals.

    PubMed

    Honma, T; Goto, K

    2000-05-01

    PISTILLATA is a B-class floral organ identity gene required for the normal development of petals and stamens in Arabidopsis. PISTILLATA expression is induced in the stage 3 flowers (early expression) and is maintained until anthesis (late expression). To explore in more detail the developmentally regulated gene expression of PISTILLATA, we have analyzed the PISTILLATA promoter using uidA (beta)-glucuronidase gene) fusion constructs (PI::GUS) in transgenic Arabidopsis. Promoter deletion analyses suggest that early PISTILLATA expression is mediated by the distal region and that late expression is mediated by the proximal region. Based on the PI::GUS expression patterns in the loss- and gain-of-function alleles of meristem or organ identity genes, we have shown that LEAFY and UNUSUAL FLORAL ORGANS induce PISTILLATA expression in a flower-independent manner via a distal promoter, and that PISTILLATA and APETALA3 maintain PISTILLATA expression (autoregulation) in the later stages of flower development via a proximal promoter. In addition, we have demonstrated that de novo protein synthesis is required for the PISTILLATA autoregulatory circuit. PMID:10769227

  8. ATTED-II: a database of co-expressed genes and cis elements for identifying co-regulated gene groups in Arabidopsis

    PubMed Central

    Obayashi, Takeshi; Kinoshita, Kengo; Nakai, Kenta; Shibaoka, Masayuki; Hayashi, Shinpei; Saeki, Motoshi; Shibata, Daisuke; Saito, Kazuki; Ohta, Hiroyuki

    2007-01-01

    Publicly available database of co-expressed gene sets would be a valuable tool for a wide variety of experimental designs, including targeting of genes for functional identification or for regulatory investigation. Here, we report the construction of an Arabidopsis thaliana trans-factor and cis-element prediction database (ATTED-II) that provides co-regulated gene relationships based on co-expressed genes deduced from microarray data and the predicted cis elements. ATTED-II () includes the following features: (i) lists and networks of co-expressed genes calculated from 58 publicly available experimental series, which are composed of 1388 GeneChip data in A.thaliana; (ii) prediction of cis-regulatory elements in the 200 bp region upstream of the transcription start site to predict co-regulated genes amongst the co-expressed genes; and (iii) visual representation of expression patterns for individual genes. ATTED-II can thus help researchers to clarify the function and regulation of particular genes and gene networks. PMID:17130150

  9. A novel pairwise comparison method for in silico discovery of statistically significant cis-regulatory elements in eukaryotic promoter regions: application to Arabidopsis.

    PubMed

    Shamloo-Dashtpagerdi, Roohollah; Razi, Hooman; Aliakbari, Massumeh; Lindlöf, Angelica; Ebrahimi, Mahdi; Ebrahimie, Esmaeil

    2015-01-01

    Cis regulatory elements (CREs), located within promoter regions, play a significant role in the blueprint for transcriptional regulation of genes. There is a growing interest to study the combinatorial nature of CREs including presence or absence of CREs, the number of occurrences of each CRE, as well as of their order and location relative to their target genes. Comparative promoter analysis has been shown to be a reliable strategy to test the significance of each component of promoter architecture. However, it remains unclear what level of difference in the number of occurrences of each CRE is of statistical significance in order to explain different expression patterns of two genes. In this study, we present a novel statistical approach for pairwise comparison of promoters of Arabidopsis genes in the context of number of occurrences of each CRE within the promoters. First, using the sample of 1000 Arabidopsis promoters, the results of the goodness of fit test and non-parametric analysis revealed that the number of occurrences of CREs in a promoter sequence is Poisson distributed. As a promoter sequence contained functional and non-functional CREs, we addressed the issue of the statistical distribution of functional CREs by analyzing the ChIP-seq datasets. The results showed that the number of occurrences of functional CREs over the genomic regions was determined as being Poisson distributed. In accordance with the obtained distribution of CREs occurrences, we suggested the Audic and Claverie (AC) test to compare two promoters based on the number of occurrences for the CREs. Superiority of the AC test over Chi-square (2×2) and Fisher's exact tests was also shown, as the AC test was able to detect a higher number of significant CREs. The two case studies on the Arabidopsis genes were performed in order to biologically verify the pairwise test for promoter comparison. Consequently, a number of CREs with significantly different occurrences was identified between

  10. Catalytic cracking catalysts using silicoaluminophosphate molecular sieves

    SciTech Connect

    Pellet, R.J.; Coughlin, P.K.; Staniulis, M.T.; Long, G.N.; Rabo, J.A.

    1987-05-19

    A cracking catalyst is described comprising: a silicoaluminophosphate molecular sieve of U.S. Pat. No. 4,440,871 characterized in its calcined form by an adsorption of isobutane of at least 2 percent by weight at a pressure of 500 torr and a temperature of 20/sup 0/C and having an effective amount of the cations associated with the silicoaluminophosphate molecular sieve selected from the group consisting of H+, ammonium, Group IIA, groups IIIB to VIIB, cerium, lanthanum, praseodymium, neodymium, and promethium.

  11. Synthesis of biological molecules on molecular sieves.

    PubMed

    Poncelet, G; Van Assche, A T; Fripiat, J J

    1975-07-01

    Catalytic properties of aluminosilicates may play a role in the synthesis of biological molecules from simple gaseous molecules commonly found in planetary atmospheres. Urea, amino acids and UV absorbing substances have been obtained by heating CO and NH3 with Linde molecular sieves saturated with Ca+2, NH4+ or Fe+3. The yields of amino acids produced have been determined by an amino acid analyzer. The quantity of urea produced largely depends on the nature of the saturating cation. Experiments using 14CO confirm that the amino acids are not due to contaminants adsorbed on the surface of the molecular sieves. PMID:171609

  12. DNA Damage-Induced Transcription of Transposable Elements and Long Non-coding RNAs in Arabidopsis Is Rare and ATM-Dependent.

    PubMed

    Wang, Zhenxing; Schwacke, Rainer; Kunze, Reinhard

    2016-08-01

    Induction and mobilization of transposable elements (TEs) following DNA damage or other stresses has been reported in prokaryotes and eukaryotes. Recently it was discovered that eukaryotic TEs are frequently associated with long non-coding RNAs (lncRNAs), many of which are also upregulated by stress. Yet, it is unknown whether DNA damage-induced transcriptional activation of TEs and lncRNAs occurs sporadically or is a synchronized, genome-wide response. Here we investigated the transcriptome of Arabidopsis wild-type (WT) and ataxia telangiectasia mutated (atm) mutant plants 3 h after induction of DNA damage. In WT, expression of 5.2% of the protein-coding genes is ≥2-fold changed, whereas in atm plants, only 2.6% of these genes are regulated, and the response of genes associated with DNA repair, replication, and cell cycle is largely lost. In contrast, only less than 0.6% of TEs and lncRNAs respond to DNA damage in WT plants, and the regulation of ≥95% of them is ATM-dependent. The ATM-downstream factors BRCA1, DRM1, JMJ30, AGO2, and the ATM-independent AGO4 participate in the regulation of individual TEs and lncRNAs. Remarkably, protein-coding genes located adjacent to DNA damage-responsive TEs and lncRNAs are frequently coexpressed, which is consistent with the hypothesis that TEs and lncRNAs located close to genes commonly function as controlling elements. PMID:27150037

  13. Inferring the Geometry of Fourth-Period Metallic Elements in Arabidopsis thaliana Seeds using Synchrotron-Based Multi-Angle X-ray Fluorescence Mapping

    SciTech Connect

    Young, Lester; Westcott, Neil; Christensen, Colleen; Terry, Jeff; Lydiate, Derek; Reaney, Martin

    2008-06-16

    Improving our knowledge of plant metal metabolism is facilitated by the use of analytical techniques to map the distribution of elements in tissues. One such technique is X-ray fluorescence (XRF), which has been used previously to map metal distribution in both two and three dimensions. One of the difficulties of mapping metal distribution in two dimensions is that it can be difficult to normalize for tissue thickness. When mapping metal distribution in three dimensions, the time required to collect the data can become a major constraint. In this article a compromise is suggested between two- and three-dimensional mapping using multi-angle XRF imaging. A synchrotron-based XRF microprobe was used to map the distribution of K, Ca, Mn, Fe, Ni, Cu and Zn in whole Arabidopsis thaliana seeds. Relative concentrations of each element were determined by measuring fluorescence emitted from a 10 {micro}m excitation beam at 13 keV. XRF spectra were collected from an array of points with 25 or 30 {micro}m steps. Maps were recorded at 0 and 90{sup o}, or at 0, 60 and 120{sup o} for each seed. Using these data, circular or ellipsoidal cross-sections were modelled, and from these an apparent pathlength for the excitation beam was calculated to normalize the data. Elemental distribution was mapped in seeds from ecotype Columbia-4 plants, as well as the metal accumulation mutants manganese accumulator 1 (man1) and nicotianamine synthetase (nasx). Multi-angle XRF imaging will be useful for mapping elemental distribution in plant tissues. It offers a compromise between two- and three-dimensional XRF mapping, as far as collection times, image resolution and ease of visualization. It is also complementary to other metal-mapping techniques. Mn, Fe and Cu had tissue-specific accumulation patterns. Metal accumulation patterns were different between seeds of the Col-4, man1 and nasx genotypes.

  14. In-situ preparation of functionalized molecular sieve material and a methodology to remove template.

    PubMed

    Yadav, Rekha; Ahmed, Maqsood; Singh, Arvind Kumar; Sakthivel, Ayyamperumal

    2016-01-01

    A series of diaminosilane-functionalized silicoaluminophosphate molecular sieve (SAPO-37) was prepared by in-situ synthesis, and a novel method was developed for the selective removal of structure directing agent (SDA)/template from the functionalized SAPO-37.The complete removal of the SDA was evident according to FT-IR, TGA, (13)C MAS-NMR and elemental analysis. The developed method was found to be efficient for removal of template from microporous molecular sieve viz., SAPO-37 and can be applied for other microporous molecular sieves such as SAPO-5, SAPO-40, etc. The powder XRD pattern of the template-removed samples showed a highly crystalline SAPO-37 phase. Argentometric titration revealed that more than 90% of diamine functionality exposed on the surface was accessible for catalytic applications. The resultant materials showed promising activity for ring opening of epoxide with aniline to yield β-amino-alcohol. PMID:26960707

  15. In-situ preparation of functionalized molecular sieve material and a methodology to remove template

    PubMed Central

    Yadav, Rekha; Ahmed, Maqsood; Singh, Arvind Kumar; Sakthivel, Ayyamperumal

    2016-01-01

    A series of diaminosilane-functionalized silicoaluminophosphate molecular sieve (SAPO-37) was prepared by in-situ synthesis, and a novel method was developed for the selective removal of structure directing agent (SDA)/template from the functionalized SAPO-37.The complete removal of the SDA was evident according to FT-IR, TGA, 13C MAS-NMR and elemental analysis. The developed method was found to be efficient for removal of template from microporous molecular sieve viz., SAPO-37 and can be applied for other microporous molecular sieves such as SAPO-5, SAPO-40, etc. The powder XRD pattern of the template-removed samples showed a highly crystalline SAPO-37 phase. Argentometric titration revealed that more than 90% of diamine functionality exposed on the surface was accessible for catalytic applications. The resultant materials showed promising activity for ring opening of epoxide with aniline to yield β-amino-alcohol. PMID:26960707

  16. In-situ preparation of functionalized molecular sieve material and a methodology to remove template

    NASA Astrophysics Data System (ADS)

    Yadav, Rekha; Ahmed, Maqsood; Singh, Arvind Kumar; Sakthivel, Ayyamperumal

    2016-03-01

    A series of diaminosilane-functionalized silicoaluminophosphate molecular sieve (SAPO-37) was prepared by in-situ synthesis, and a novel method was developed for the selective removal of structure directing agent (SDA)/template from the functionalized SAPO-37.The complete removal of the SDA was evident according to FT-IR, TGA, 13C MAS-NMR and elemental analysis. The developed method was found to be efficient for removal of template from microporous molecular sieve viz., SAPO-37 and can be applied for other microporous molecular sieves such as SAPO-5, SAPO-40, etc. The powder XRD pattern of the template-removed samples showed a highly crystalline SAPO-37 phase. Argentometric titration revealed that more than 90% of diamine functionality exposed on the surface was accessible for catalytic applications. The resultant materials showed promising activity for ring opening of epoxide with aniline to yield β-amino-alcohol.

  17. 7 CFR 801.8 - Tolerances for sieves.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ....3 percent, mean deviation from standard sieve using barley ±0.5 percent, mean deviation from standard sieve using barley 55/64×3/4 inch slotted ±0.5 percent, mean deviation from standard sieve using barley ±0.7 percent, mean deviation from standard sieve using barley 6/64×3/4 inch slotted ±0.7...

  18. 7 CFR 801.8 - Tolerances for sieves.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ....3 percent, mean deviation from standard sieve using barley ±0.5 percent, mean deviation from standard sieve using barley 55/64×3/4 inch slotted ±0.5 percent, mean deviation from standard sieve using barley ±0.7 percent, mean deviation from standard sieve using barley 6/64×3/4 inch slotted ±0.7...

  19. 7 CFR 801.8 - Tolerances for sieves.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ....3 percent, mean deviation from standard sieve using barley ±0.5 percent, mean deviation from standard sieve using barley 55/64×3/4 inch slotted ±0.5 percent, mean deviation from standard sieve using barley ±0.7 percent, mean deviation from standard sieve using barley 6/64×3/4 inch slotted ±0.7...

  20. 7 CFR 801.8 - Tolerances for sieves.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ....3 percent, mean deviation from standard sieve using barley ±0.5 percent, mean deviation from standard sieve using barley 55/64×3/4 inch slotted ±0.5 percent, mean deviation from standard sieve using barley ±0.7 percent, mean deviation from standard sieve using barley 6/64×3/4 inch slotted ±0.7...

  1. 7 CFR 801.8 - Tolerances for sieves.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ....3 percent, mean deviation from standard sieve using barley ±0.5 percent, mean deviation from standard sieve using barley 55/64×3/4 inch slotted ±0.5 percent, mean deviation from standard sieve using barley ±0.7 percent, mean deviation from standard sieve using barley 6/64×3/4 inch slotted ±0.7...

  2. Recent Improvements To the Sieve of Eratosthenes.

    ERIC Educational Resources Information Center

    Quesada, Antonio R.

    1997-01-01

    Presents recently developed generalizations to the sieve of Eratosthenes, showing the principles underlying these improvements, which increase its efficiency without changing too much of its simplicity. Offers several possibilities to propose good investigations for students to explore, find patterns, and make generalizations. (JRH)

  3. Molecular sieving silica membrane fabrication process

    DOEpatents

    Raman, Narayan K.; Brinker, Charles Jeffrey

    1998-01-01

    A process for producing a molecular sieve silica membrane comprising depositing a hybrid organic-inorganic polymer comprising at least one organic constituent and at least one inorganic constituent on a porous substrate material and removing at least a portion of the at least one organic constituent of the hybrid organic-inorganic polymer, forming a porous film.

  4. Molecular sieving silica membrane fabrication process

    DOEpatents

    Raman, Narayan K.; Brinker, Charles Jeffrey

    1999-01-01

    A process for producing a molecular sieve silica membrane comprising depositing a hybrid organic-inorganic polymer comprising at least one organic constituent and at least one inorganic constituent on a porous substrate material and removing at least a portion of the at least one organic constituent of the hybrid organic-inorganic polymer, forming a porous film.

  5. Molecular sieving silica membrane fabrication process

    DOEpatents

    Raman, N.K.; Brinker, C.J.

    1999-08-10

    A process is described for producing a molecular sieve silica membrane comprising depositing a hybrid organic-inorganic polymer comprising at least one organic constituent and at least one inorganic constituent on a porous substrate material and removing at least a portion of the at least one organic constituent of the hybrid organic-inorganic polymer, forming a porous film. 11 figs.

  6. The Responses of Arabidopsis Early Light-Induced Protein2 to Ultraviolet B, High Light, and Cold Stress Are Regulated by a Transcriptional Regulatory Unit Composed of Two Elements.

    PubMed

    Hayami, Natsuki; Sakai, Yusaku; Kimura, Mitsuhiro; Saito, Tatsunori; Tokizawa, Mutsutomo; Iuchi, Satoshi; Kurihara, Yukio; Matsui, Minami; Nomoto, Mika; Tada, Yasuomi; Yamamoto, Yoshiharu Y

    2015-09-01

    The Arabidopsis (Arabidopsis thaliana) Early Light-Induced Protein (ELIP) is thought to act as a photoprotectant, reducing the damaging effects of high light (HL). Expression of ELIP2 is activated by multiple environmental stresses related to photoinhibition. We have identified putative regulatory elements in an ELIP2 promoter using an octamer-based frequency comparison method, analyzed the role of these elements using synthetic promoters, and revealed a key transcriptional regulatory unit for ultraviolet B (UV-B) radiation, HL, and cold stress responses. The unit is composed of two elements, designated as Elements A (TACACACC) and B (GGCCACGCCA), and shows functionality only when paired. Our genome-wide correlation analysis between possession of these elements in the promoter region and expression profiles in response to UV-B, HL, and cold suggests that Element B receives and integrates these multiple stress signals. In vitro protein-DNA binding assays revealed that LONG HYPOCOTYL5 (HY5), a basic domain-Leucine zipper transcription factor, directly binds to Element B. In addition, mutant analysis of HY5 showed partial involvement in the UV-B and HL responses but not in the cold stress response. These results suggest that signals for UV-B, HL, and cold stress join at Element B, which recognizes the signals of multiple transcription factors, including HY5. PMID:26175515

  7. The Responses of Arabidopsis Early Light-Induced Protein2 to Ultraviolet B, High Light, and Cold Stress Are Regulated by a Transcriptional Regulatory Unit Composed of Two Elements1[OPEN

    PubMed Central

    Hayami, Natsuki; Sakai, Yusaku; Kimura, Mitsuhiro; Saito, Tatsunori; Tokizawa, Mutsutomo; Iuchi, Satoshi; Kurihara, Yukio; Matsui, Minami; Nomoto, Mika; Tada, Yasuomi; Yamamoto, Yoshiharu Y.

    2015-01-01

    The Arabidopsis (Arabidopsis thaliana) Early Light-Induced Protein (ELIP) is thought to act as a photoprotectant, reducing the damaging effects of high light (HL). Expression of ELIP2 is activated by multiple environmental stresses related to photoinhibition. We have identified putative regulatory elements in an ELIP2 promoter using an octamer-based frequency comparison method, analyzed the role of these elements using synthetic promoters, and revealed a key transcriptional regulatory unit for ultraviolet B (UV-B) radiation, HL, and cold stress responses. The unit is composed of two elements, designated as Elements A (TACACACC) and B (GGCCACGCCA), and shows functionality only when paired. Our genome-wide correlation analysis between possession of these elements in the promoter region and expression profiles in response to UV-B, HL, and cold suggests that Element B receives and integrates these multiple stress signals. In vitro protein-DNA binding assays revealed that LONG HYPOCOTYL5 (HY5), a basic domain-Leucine zipper transcription factor, directly binds to Element B. In addition, mutant analysis of HY5 showed partial involvement in the UV-B and HL responses but not in the cold stress response. These results suggest that signals for UV-B, HL, and cold stress join at Element B, which recognizes the signals of multiple transcription factors, including HY5. PMID:26175515

  8. Computational image formation with photon sieves for milli-arcsecond solar imaging

    NASA Astrophysics Data System (ADS)

    Oktem, Figen S.; Kamalabadi, Farzad; Davila, Joseph

    2016-07-01

    A photon sieve is a modification of a Fresnel zone plate in which open zones are replaced by a large number of circular holes. This diffractive imaging element is specially suited to observations at UV and x-ray wavelengths where refractive lenses are not available due to strong absorption of materials, and reflective mirrors are difficult to manufacture with sufficient surface figure accuracy to achieve diffraction-limited resolution. On the other hand, photon sieves enable diffraction-limited imaging with much more relaxed tolerances than conventional imaging technology. In this presentation, we present the capabilities of an instrument concept that is based on computational image formation with photon sieves. The instrument enables high-resolution spectral imaging by distributing the imaging task between a photon sieve system and a computational method. A photon sieve coupled with a moving detector provides measurements from multiple planes. Then computational image formation, which involves deconvolution, is performed in a Bayesian estimation framework to reconstruct the multi-spectral images from these measurements. In addition to diffraction-limited high spatial resolution enabled by photon sieves, this instrument can also achieve higher spectral resolution than the conventional spectral imagers, since the technique offers the possibility of separating nearby spectral components that would not otherwise be possible using wavelength filters. Here, the promising capabilities and the imaging performance are shown for imaging the solar corona at EUV wavelengths. The effectiveness of various potential observing scenarios, the effects of interfering emission lines, and the appropriate form of the cost function for image deconvolution are examined.

  9. Factorization using the quadratic sieve algorithm

    SciTech Connect

    Davis, J.A.; Holdridge, D.B.

    1983-12-01

    Since the cryptosecurity of the RSA two key cryptoalgorithm is no greater than the difficulty of factoring the modulus (product of two secret primes), a code that implements the Quadratic Sieve factorization algorithm on the CRAY I computer has been developed at the Sandia National Laboratories to determine as sharply as possible the current state-of-the-art in factoring. Because all viable attacks on RSA thus far proposed are equivalent to factorization of the modulus, sharper bounds on the computational difficulty of factoring permit improved estimates for the size of RSA parameters needed for given levels of cryptosecurity. Analysis of the Quadratic Sieve indicates that it may be faster than any previously published general purpose algorithm for factoring large integers. The high speed of the CRAY I coupled with the capability of the CRAY to pipeline certain vectorized operations make this algorithm (and code) the front runner in current factoring techniques.

  10. Factorization using the quadratic sieve algorithm

    SciTech Connect

    Davis, J.A.; Holdridge, D.B.

    1983-01-01

    Since the cryptosecurity of the RSA two key cryptoalgorithm is no greater than the difficulty of factoring the modulus (product of two secret primes), a code that implements the Quadratic Sieve factorization algorithm on the CRAY I computer has been developed at the Sandia National Laboratories to determine as sharply as possible the current state-of-the-art in factoring. Because all viable attacks on RSA thus far proposed are equivalent to factorization of the modulus, sharper bounds on the computational difficulty of factoring permit improved estimates for the size of RSA parameters needed for given levels of cryptosecurity. Analysis of the Quadratic Sieve indicates that it may be faster than any previously published general purpose algorithm for factoring large integers. The high speed of the CRAY I coupled with the capability of the CRAY to pipeline certain vectorized operations make this algorithm (and code) the front runner in current factoring techniques.

  11. The role of promoter cis-element, mRNA capping, and ROS in the repression and salt-inducible expression of AtSOT12 in Arabidopsis

    PubMed Central

    Chen, Jinhua; Wang, Bangshing; Chung, Jung-Sung; Chai, Haoxi; Liu, Chunlin; Ruan, Ying; Shi, Huazhong

    2015-01-01

    Inducible gene expression is a gene regulatory mechanism central to plant response to environmental cues. The inducible genes are often repressed under normal growth conditions while their expression levels are significantly elevated by conditions such as abiotic stresses. Induction of gene expression requires both cis-acting DNA elements and trans-acting proteins that are modulated through signal transduction pathways. Here we report several molecular events that affect salt induced expression of the Arabidopsis AtSOT12 gene. Promoter deletion analysis revealed that DNA elements residing in the 5′ UTR are required for the salt induced expression of AtSOT12. Cytosine methylation in the promoter was low and salt stress slightly increased the DNA methylation level, suggesting that DNA methylation may not contribute to AtSOT12 gene repression. Co-transcriptional processing of AtSOT12 mRNA including capping and polyadenylation site selection was also affected by salt stress. The percentage of capped mRNA increased by salt treatment, and the polyadenylation sites were significantly different before and after exposure to salt stress. The expression level of AtSOT12 under normal growth conditions was markedly higher in the oxi1 mutant defective of reactive oxygen species (ROS) signaling than in the wild type. Moreover, AtSOT12 transcript level was elevated by treatments with DPI and DMTU, two chemicals preventing ROS accumulation. These results suggest that repression of AtSOT12 expression may require physiological level of ROS and ROS signaling. PMID:26594223

  12. In situ microscopy reveals reversible cell wall swelling in kelp sieve tubes: one mechanism for turgor generation and flow control?

    PubMed

    Knoblauch, Jan; Tepler Drobnitch, Sarah; Peters, Winfried S; Knoblauch, Michael

    2016-08-01

    Kelps, brown algae (Phaeophyceae) of the order Laminariales, possess sieve tubes for the symplasmic long-distance transport of photoassimilates that are evolutionarily unrelated but structurally similar to the tubes in the phloem of vascular plants. We visualized sieve tube structure and wound responses in fully functional, intact Bull Kelp (Nereocystis luetkeana [K. Mertens] Postels & Ruprecht 1840). In injured tubes, apparent slime plugs formed but were unlikely to cause sieve tube occlusion as they assembled at the downstream side of sieve plates. Cell walls expanded massively in the radial direction, reducing the volume of the wounded sieve elements by up to 90%. Ultrastructural examination showed that a layer of the immediate cell wall characterized by circumferential cellulose fibrils was responsible for swelling and suggested that alginates, abundant gelatinous polymers of the cell wall matrix, were involved. Wall swelling was rapid, reversible and depended on intracellular pressure, as demonstrated by pressure-injection of silicon oil. Our results revive the concept of turgor generation and buffering by swelling cell walls, which had fallen into oblivion over the last century. Because sieve tube transport is pressure-driven and controlled physically by tube diameter, a regulatory role of wall swelling in photoassimilate distribution is implied in kelps. PMID:26991892

  13. Deep Investigation of Arabidopsis thaliana Junk DNA Reveals a Continuum between Repetitive Elements and Genomic Dark Matter

    PubMed Central

    Maumus, Florian; Quesneville, Hadi

    2014-01-01

    Eukaryotic genomes contain highly variable amounts of DNA with no apparent function. This so-called junk DNA is composed of two components: repeated and repeat-derived sequences (together referred to as the repeatome), and non-annotated sequences also known as genomic dark matter. Because of their high duplication rates as compared to other genomic features, transposable elements are predominant contributors to the repeatome and the products of their decay is thought to be a major source of genomic dark matter. Determining the origin and composition of junk DNA is thus important to help understanding genome evolution as well as host biology. In this study, we have used a combination of tools enabling to show that the repeatome from the small and reducing A. thaliana genome is significantly larger than previously thought. Furthermore, we present the concepts and results from a series of innovative approaches suggesting that a significant amount of the A. thaliana dark matter is of repetitive origin. As a tentative standard for the community, we propose a deep compendium annotation of the A. thaliana repeatome that may help addressing farther genome evolution as well as transcriptional and epigenetic regulation in this model plant. PMID:24709859

  14. Overexpression of Arabidopsis Dehydration-Responsive Element-Binding protein 2A confers tolerance to salinity stress to transgenic canola.

    PubMed

    Shafeinie, Alireza; Mohammadi, Valiollah; Alizadeh, Houshang; Zali, Abas Ali

    2014-05-01

    Stress responsive transcriptional regulation is an adaptive strategy of plants that alleviates the adverse effects of environmental stresses. The ectopic overexpression of Dehydration-Responsive Element Binding transcription factors (DREBs) either in homologous or in heterologous plants are the classical transcriptional regulators involved in plant responses to drought, salt and cold stresses. To elucidate the transcriptional mechanism associated with the DREB2A gene after removing PEST sequence, which acts as a signal peptide for protein degradation, 34 transgenic T0 canola plants overexpressing DREB2A were developed. The quantitative Real time PCR of transgenic plants showed higher expression of downstream stress-responsive genes including COR14, HSF3, HSP70, PEROX and RD20. The transgenic plants exhibited enhanced tolerance to salt stress. At the high concentration of NaCl the growth of non-transformed plants had been clearly diminished, whereas transgenic line was survived. These results indicated that transformed DREB2A gene might improve the plant response to salinity in transgenic canola plants. PMID:26030994

  15. Coal-based carbons with molecular sieve properties

    SciTech Connect

    El-Wakil, A.M.; Youssef, A.M.; Tollan, K.A. )

    1991-01-01

    Carbon molecular sieves are used extensively in gas chromatography for the separation of permanent gases and light hydrocarbons. Carbon molecular sieves also find commercial application for the manufacture of pure hydrogen from hydrogen-rich gases such as coke-oven gas, and for the separation of air by the pressure-swing adsorption technique. The objective of this investigation was to prepare carbons from Maghara coal, recently available on the commercial market. Coal-based carbons, if they possess molecular sieve properties, are superior to molecular sieve carbons from agricultural by-products because they have more satisfactory mechanical properties.

  16. Adsorption of gases on carbon molecular sieves

    SciTech Connect

    Vyas, S.N.; Patwardhan, S.R.; Vijayalakshmi, S. . Dept. of Chemical Engineering); Ganesh, K.S. )

    1994-12-01

    Adsorption on carbon molecular sieves (CMS) prepared by coke deposition has become an interesting area of adsorption due to its microporous nature and favorable separation factor on size and shape selectivity basis for many gaseous systems. In the present work CMS was synthesized from coconut shell through three major steps, namely, carbonization, activation, and coke deposition by hydrocarbon cracking. The crushed, washed, and sieved granules of coconut shell (particle size 2--3 mm) were pretreated with sodium silicate solution and oven-dried at 150 C to create the inorganic sites necessary for coke deposition. Carbonization and activation of the dried granules were carried out at 800 C, for 30 min each. The activated char thus produced was subjected to hydrocarbon cracking at 600 C for periods varying from 30 to 180 min. The product samples were characterized in terms of adsorption isotherm, kinetic adsorption curve, surface area, pore volume, pore size distribution, and characteristic energy for adsorption by using O[sub 2], N[sub 2], C[sub 2]H[sub 2], CO[sub 2], C[sub 3]H[sub 6], and CH[sub 4].

  17. Cadherin selectivity filter regulates endothelial sieving properties

    PubMed Central

    Quadri, Sadiqa K.; Sun, Li; Islam, Mohammad Naimul; Shapiro, Lawrence; Bhattacharya, Jahar

    2013-01-01

    The molecular basis of endothelial protein sieving, the critical vascular barrier function that restricts flow of large plasma proteins into tissues while allowing small molecules and water to pass, is not understood. Here, we address this issue using a novel assay to detect macromolecular penetrance at microdomains of endothelial adherens junctions. Adherens junctions, as detected by cadherin-GFP expression, were distributed in the cell perimeter as high- or low-density segments. Low but not high-density segments permitted penetrance of a 70-kDa fluorescent dextran, a molecule of equivalent size to albumin. Expression of a cadherin mutant that abrogates strand–swap adhesive binding in the cadherin EC1 ectodomain, or alternatively of an α-actinin-1 mutant that inhibits F-actin bundling, increased both cadherin mobility and 70 kDa dextran penetrance at high-density segments. These findings suggest that adhesive interactions in the cadherin EC1 domain, which underlie adherens junction structure, are critical determinants of endothelial macromolecular sieving. PMID:23033075

  18. Clad photon sieve for generating localized hollow beams

    NASA Astrophysics Data System (ADS)

    Cheng, Yiguang; Tong, Junmin; Zhu, Jiangping; Liu, Junbo; Hu, Song; He, Yu

    2016-02-01

    A novel photon sieve structure called clad photon sieve is proposed to generate localized hollow beams and its design principle and focusing properties are studied. The clad photon sieve is composed of the internal zone and external zone with pinholes being positioned on the dark zones. Pinholes in the internal zone and in the external zone give destructive interference to the focus, leading to localized hollow beams being generated on the focal plane. Focusing properties of clad photon sieve with different focal lengths, zone numbers and modulation factors are also studied by theoretical calculations, numerical simulations and experiments, showing that the central dark spot size can be controlled by the focal length and rings number, and the intensity of the central dark spot varies with different modulation factors related with the internal zone and the external zone. This photon sieve can be useful for trapping and manipulating of particles and cooling of atoms.

  19. Sieving wastewater--cellulose recovery, economic and energy evaluation.

    PubMed

    Ruiken, C J; Breuer, G; Klaversma, E; Santiago, T; van Loosdrecht, M C M

    2013-01-01

    Application of fine-mesh sieves (<0.35 mm) as pretreatment for municipal biological wastewater treatment gives an opportunity to recover resources and increase sustainability of wastewater treatment processes. Sieves are traditionally used for single stage mechanical treatment (typical mesh of 0.35 mm) or in combination with an MBR (typical mesh >0.7 mm). When sieves with a mesh of 0.35 mm are used on raw sewage we observed that cellulose fibres mainly originating from toilet paper are removed efficiently from the influent with a high recovery and purity. The application of sieves as pretreatment for conventional activated sludge processes has been evaluated based on pilot plant research at three WWTPs in the Netherlands. With sieving applied to the dry weather flow only the overall energy usage of the WWTP including sludge treatment can be decreased by at least 40% with a payback time of 7 years. PMID:23121895

  20. The proteins encoded by the pogo-like Lemi1 element bind the TIRs and subterminal repeated motifs of the Arabidopsis Emigrant MITE: consequences for the transposition mechanism of MITEs

    PubMed Central

    Loot, Céline; Santiago, Néstor; Sanz, Alicia; Casacuberta, Josep M.

    2006-01-01

    MITEs (miniature inverted-repeated transposable elements) are a particular class of defective DNA transposons usually present within genomes as high copy number populations of highly homogeneous elements. Although an active MITE, the mPing element, has recently been characterized in rice, the transposition mechanism of MITEs remains unknown. It has been proposed that transposases of related transposons could mobilize MITEs in trans. Moreover, it has also been proposed that the presence of conserved terminal inverted-repeated (TIR) sequences could be the only requirement of MITEs for mobilization, allowing divergent or unrelated elements to be mobilized by a particular transposase. We present here evidence for a recent mobility of the Arabidopsis Emigrant MITE and we report on the capacity of the proteins encoded by the related Lemi1 transposon, a pogo-related element, to specifically bind Emigrant elements. This suggests that Lemi1 could mobilize Emigrant elements and makes the Lemi1/Emigrant couple an ideal system to study the transposition mechanism of MITEs. Our results show that Lemi1 proteins bind Emigrant TIRs but also bind cooperatively to subterminal repeated motifs. The requirement of internal sequences for the formation of proper DNA/protein structure could affect the capacity of divergent MITEs to be mobilized by distantly related transposases. PMID:17003053

  1. Octahedral molecular sieve sorbents and catalysts

    DOEpatents

    Li, Liyu [Richland, WA; King, David L [Richland, WA

    2010-04-20

    Octahedral molecular sieve sorbents and catalysts are disclosed, including silver hollandite and cryptomelane. These materials can be used, for example, to catalyze the oxidation of CO.sub.x (e.g., CO), NO.sub.x (e.g., NO), hydrocarbons (e.g., C.sub.3H.sub.6) and/or sulfur-containing compounds. The disclosed materials also may be used to catalyze other reactions, such as the reduction of NO.sub.2. In some cases, the disclosed materials are capable of sorbing certain products from the reactions they catalyze. Silver hollandite, in particular, can be used to remove a substantial portion of certain sulfur-containing compounds from a gas or liquid by catalysis and/or sorption. The gas or liquid can be, for example, natural gas or a liquid hydrocarbon.

  2. Silicotitanate molecular sieve and condensed phases

    DOEpatents

    Nenoff, Tina M.; Nyman, May D.

    2002-01-01

    A new microporous crystalline molecular sieve material having the formula Cs.sub.3 TiSi.sub.3 O.sub.95.cndot.3H.sub.2 O and its hydrothermally condensed phase, Cs.sub.2 TiSi.sub.6 O.sub.15, are disclosed. The microporous material can adsorb divalent ions of radionuclides or other industrial metals such as chromium, nickel, lead, copper, cobalt, zinc, cadmium, barium, and mercury, from aqueous or hydrocarbon solutions. The adsorbed metal ions can be leached out for recovery purposes or the microporous material can be hydrothermally condensed to a radiation resistant, structurally and chemically stable phase which can serve as a storage waste form for radionuclides.

  3. The MPK6-ERF6-ROS-Responsive cis-Acting Element7/GCC Box Complex Modulates Oxidative Gene Transcription and the Oxidative Response in Arabidopsis1[W][OA

    PubMed Central

    Wang, Pengcheng; Du, Yanyan; Zhao, Xiaoliang; Miao, Yuchen; Song, Chun-Peng

    2013-01-01

    Reactive oxygen species (ROS) have been characterized as both important signaling molecules and universal stressors that mediate many developmental and physiological responses. So far, details of the transcriptional mechanism of ROS-responsive genes are largely unknown. In the study reported here, we identified seven potential ROS-responsive cis-acting elements (ROSEs) from the promoters of genes up-regulated by ROS in Arabidopsis (Arabidopsis thaliana). We also found that the APETALA2/ethylene-responsive element binding factor6 (ERF6) could bind specifically to the ROSE7/GCC box. Coexpression of ERF6 enhanced luciferase activity driven by ROSE7. The deficient mutants of ERF6 showed growth retardation and higher sensitivity to photodamage. ERF6 interacted physically with mitogen-activated protein kinase6 (MPK6) and also served as a substrate of MPK6. MPK6-mediated ERF6 phosphorylation at both serine-266 and serine-269 affected the dynamic alternation of the ERF6 protein, which resulted in changes in ROS-responsive gene transcription. These data might provide new insight into the mechanisms that regulate ROS-responsive gene transcription via a complex of MPK6, ERF6, and the ROSE7/GCC box under oxidative stress or a fluctuating light environment. PMID:23300166

  4. AthaMap web tools for database-assisted identification of combinatorial cis-regulatory elements and the display of highly conserved transcription factor binding sites in Arabidopsis thaliana.

    PubMed

    Steffens, Nils Ole; Galuschka, Claudia; Schindler, Martin; Bülow, Lorenz; Hehl, Reinhard

    2005-07-01

    The AthaMap database generates a map of cis-regulatory elements for the Arabidopsis thaliana genome. AthaMap contains more than 7.4 x 10(6) putative binding sites for 36 transcription factors (TFs) from 16 different TF families. A newly implemented functionality allows the display of subsets of higher conserved transcription factor binding sites (TFBSs). Furthermore, a web tool was developed that permits a user-defined search for co-localizing cis-regulatory elements. The user can specify individually the level of conservation for each TFBS and a spacer range between them. This web tool was employed for the identification of co-localizing sites of known interacting TFs and TFs containing two DNA-binding domains. More than 1.8 x 10(5) combinatorial elements were annotated in the AthaMap database. These elements can also be used to identify more complex co-localizing elements consisting of up to four TFBSs. The AthaMap database and the connected web tools are a valuable resource for the analysis and the prediction of gene expression regulation at http://www.athamap.de. PMID:15980498

  5. 21 CFR 173.40 - Molecular sieve resins.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...) The molecular sieve resins consist of purified dextran having an average molecular weight of 40,000, cross-linked with epichlorohydrin in a ratio of 1 part of dextran to 10 parts of epichlorohydrin,...

  6. 21 CFR 173.40 - Molecular sieve resins.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...) The molecular sieve resins consist of purified dextran having an average molecular weight of 40,000, cross-linked with epichlorohydrin in a ratio of 1 part of dextran to 10 parts of epichlorohydrin,...

  7. Differential Expression of the Arabidopsis Cytochrome c Genes Cytc-1 and Cytc-2. Evidence for the Involvement of TCP-Domain Protein-Binding Elements in Anther- and Meristem-Specific Expression of the Cytc-1 Gene1

    PubMed Central

    Welchen, Elina; Gonzalez, Daniel H.

    2005-01-01

    The promoters of the Arabidopsis (Arabidopsis thaliana) cytochrome c genes, Cytc-1 and Cytc-2, were analyzed using plants transformed with fusions to the β-glucuronidase coding sequence. Histochemical staining of plants indicated that the Cytc-1 promoter directs preferential expression in root and shoot meristems and in anthers. In turn, plants transformed with the Cytc-2 promoter fusions showed preferential expression in vascular tissues of cotyledons, leaves, roots, and hypocotyls, and also in anthers. Quantitative measurements in extracts prepared from different organs suggested that expression of Cytc-1 is higher in flowers, while that of Cytc-2 is higher in leaves. The analysis of a set of deletions and site-directed mutants of the Cytc-1 promoter indicated that a segment located between −147 and −156 from the translation start site is required for expression and that site II elements (TGGGCC/T) located in this region, coupled with a downstream internal telomeric repeat (AAACCCTAA), are responsible for the expression pattern of this gene. Proteins present in cauliflower nuclear extracts, as well as a recombinant protein from the TCP-domain family, were able to specifically bind to the region required for expression. We propose that expression of the Cytc-1 gene is linked to cell proliferation through the elements described above. The fact that closely located site II motifs are present in similar locations in several genes encoding proteins involved in cytochrome c-dependent respiration suggests that these elements may be the target of factors that coordinate the expression of nuclear genes encoding components of this part of the mitochondrial respiratory chain. PMID:16113211

  8. Porous Organic Cage Thin Films and Molecular-Sieving Membranes.

    PubMed

    Song, Qilei; Jiang, Shan; Hasell, Tom; Liu, Ming; Sun, Shijing; Cheetham, Anthony K; Sivaniah, Easan; Cooper, Andrew I

    2016-04-01

    Porous organic cage molecules are fabricated into thin films and molecular-sieving membranes. Cage molecules are solution cast on various substrates to form amorphous thin films, with the structures tuned by tailoring the cage chemistry and processing conditions. For the first time, uniform and pinhole-free microporous cage thin films are formed and demonstrated as molecular-sieving membranes for selective gas separation. PMID:26800019

  9. A 99 percent purity molecular sieve oxygen generator

    NASA Technical Reports Server (NTRS)

    Miller, G. W.

    1991-01-01

    Molecular sieve oxygen generating systems (MSOGS) have become the accepted method for the production of breathable oxygen on military aircraft. These systems separate oxygen for aircraft engine bleed air by application of pressure swing adsorption (PSA) technology. Oxygen is concentrated by preferential adsorption in nitrogen in a zeolite molecular sieve. However, the inability of current zeolite molecular sieves to discriminate between oxygen and argon results in an oxygen purity limitations of 93-95 percent (both oxygen and argon concentrate). The goal was to develop a new PSA process capable of exceeding the present oxygen purity limitations. A novel molecular sieve oxygen concentrator was developed which is capable of generating oxygen concentrations of up to 99.7 percent directly from air. The process is comprised of four absorbent beds, two containing a zeolite molecular sieve and two containing a carbon molecular sieve. This new process may find use in aircraft and medical breathing systems, and industrial air separation systems. The commercial potential of the process is currently being evaluated.

  10. Turnover of Soluble Proteins in the Wheat Sieve Tube

    PubMed Central

    Fisher, Donald B.; Wu, Yujia; Ku, Maurice S. B.

    1992-01-01

    Although the enucleate conducting cells of the phloem are incapable of protein synthesis, phloem exudates characteristically contain low concentrations of soluble proteins. The role of these proteins and their movement into and out of the sieve tubes poses important questions for phloem physiology and for cell-to-cell protein movement via plasmodesmata. The occurrence of protein turnover in sieve tubes was investigated by [35S]methionine labeling and by the use of aphid stylets to sample the sieve tube contents at three points along a source-to-sink pathway (flag leaf to grains) in wheat plants (Triticum aestivum L.). Protein concentration and composition were similar at all sampling sites. The kinetics of 35S-labeling of protein suggested a basically source-to-sink pattern of movement for many proteins. However, an appreciable amount of protein synthesis and, presumably, removal also occurred along the path. This movement appeared to be protein specific and not based on passive molecular sieving. The results have important implications for the transport capacities of plasmodesmata between sieve tubes and companion cells. The observations considerably expand the possible basis for ongoing sieve tube-companion cell interactions and, perhaps, interaction between sources and sinks. Images Figure 2 Figure 3 Figure 4 Figure 5 Figure 8 Figure 10 Figure 11 Figure 12 PMID:16653142

  11. Antibacterial mesoporous molecular sieves modified with polymeric N-halamine.

    PubMed

    Wang, Yingfeng; Li, Lin; Liu, Ying; Ren, Xuehong; Liang, Jie

    2016-12-01

    In this research, a new kind of porous N-halamine material with high antibacterial efficacies was prepared. Poly [5,5-dimethyl-3-(3'-triethoxysilylpropyl)-hydantoin] (PSPH), an N-halamine precursor, was synthesized and grafted onto the surface of mesoporous molecular sieves (SBA-15). The mesoporous molecular sieves modified with the N-halamine polymer could be rendered biocidal upon exposure to dilute household bleach. The modified mesoporous molecular sieves were characterized by SEM, TEM, FTIR, XPS, TGA, XRD and BET analysis. It was found that the PSPH has been successfully grafted on the surface of mesoporous molecular sieves, and the morphology and structure of the modified mesoporous molecular sieves were slightly affected. The N-halamine modified mesoporous molecular sieves showed excellent antibacterial property, and inactivated 100% of S. aureus and E. coli O157:H7 with 8.05 and 7.92 log reductions within 1min of contact, respectively. The modified SBA-15 with high-antibacterial efficiency has potential application in water treatment and biomaterials areas. PMID:27612805

  12. Molecular Sieve Bench Testing and Computer Modeling

    NASA Technical Reports Server (NTRS)

    Mohamadinejad, Habib; DaLee, Robert C.; Blackmon, James B.

    1995-01-01

    The design of an efficient four-bed molecular sieve (4BMS) CO2 removal system for the International Space Station depends on many mission parameters, such as duration, crew size, cost of power, volume, fluid interface properties, etc. A need for space vehicle CO2 removal system models capable of accurately performing extrapolated hardware predictions is inevitable due to the change of the parameters which influences the CO2 removal system capacity. The purpose is to investigate the mathematical techniques required for a model capable of accurate extrapolated performance predictions and to obtain test data required to estimate mass transfer coefficients and verify the computer model. Models have been developed to demonstrate that the finite difference technique can be successfully applied to sorbents and conditions used in spacecraft CO2 removal systems. The nonisothermal, axially dispersed, plug flow model with linear driving force for 5X sorbent and pore diffusion for silica gel are then applied to test data. A more complex model, a non-darcian model (two dimensional), has also been developed for simulation of the test data. This model takes into account the channeling effect on column breakthrough. Four FORTRAN computer programs are presented: a two-dimensional model of flow adsorption/desorption in a packed bed; a one-dimensional model of flow adsorption/desorption in a packed bed; a model of thermal vacuum desorption; and a model of a tri-sectional packed bed with two different sorbent materials. The programs are capable of simulating up to four gas constituents for each process, which can be increased with a few minor changes.

  13. Similar Intracellular Location and Stimulus Reactivity, but Differential Mobility of Tailless (Vicia faba) and Tailed Forisomes (Phaseolus vulgaris) in Intact Sieve Tubes

    PubMed Central

    van Bel, Aart J. E.

    2015-01-01

    Sieve elements of legumes contain forisomes—fusiform protein bodies that are responsible for sieve-tube occlusion in response to damage or wound signals. Earlier work described the existence of tailless and tailed forisomes. This study intended to quantify and compare location and position of tailless (in Vicia faba) and tailed (in Phaseolus vulgaris) forisomes inside sieve elements and to assess their reactivity and potential mobility in response to a remote stimulus. Location (distribution within sieve elements) and position (forisome tip contacts) of more than altogether 2000 forisomes were screened in 500 intact plants by laser scanning confocal microscopy in the transmission mode. Furthermore, we studied the dispersion of forisomes at different locations in different positions and their positional behaviour in response to distant heat shocks. Forisome distribution turned out to be species-specific, whereas forisome positions at various locations were largely similar in bushbean (Phaseolus) and broadbean (Vicia). In general, the tailless forisomes had higher dispersion rates in response to heat shocks than the tailed forisomes and forisomes at the downstream (basal) end dispersed more frequently than those at the upstream end (apical). In contrast to the tailless forisomes that only oscillate in response to heat shocks, downstream-located tailed forisomes can cover considerable distances within sieve elements. This displacement was prevented by gentle rubbing of the leaf (priming) before the heat shock. Movement of these forisomes was also prohibited by Latrunculin A, an inhibitor of actin polymerization. The apparently active mobility of tailed forisomes gives credence to the idea that at least the latter forisomes are not free-floating, but connected to other sieve-element structures. PMID:26624625

  14. Similar Intracellular Location and Stimulus Reactivity, but Differential Mobility of Tailless (Vicia faba) and Tailed Forisomes (Phaseolus vulgaris) in Intact Sieve Tubes.

    PubMed

    Furch, Alexandra C U; Buxa, Stefanie V; van Bel, Aart J E

    2015-01-01

    Sieve elements of legumes contain forisomes-fusiform protein bodies that are responsible for sieve-tube occlusion in response to damage or wound signals. Earlier work described the existence of tailless and tailed forisomes. This study intended to quantify and compare location and position of tailless (in Vicia faba) and tailed (in Phaseolus vulgaris) forisomes inside sieve elements and to assess their reactivity and potential mobility in response to a remote stimulus. Location (distribution within sieve elements) and position (forisome tip contacts) of more than altogether 2000 forisomes were screened in 500 intact plants by laser scanning confocal microscopy in the transmission mode. Furthermore, we studied the dispersion of forisomes at different locations in different positions and their positional behaviour in response to distant heat shocks. Forisome distribution turned out to be species-specific, whereas forisome positions at various locations were largely similar in bushbean (Phaseolus) and broadbean (Vicia). In general, the tailless forisomes had higher dispersion rates in response to heat shocks than the tailed forisomes and forisomes at the downstream (basal) end dispersed more frequently than those at the upstream end (apical). In contrast to the tailless forisomes that only oscillate in response to heat shocks, downstream-located tailed forisomes can cover considerable distances within sieve elements. This displacement was prevented by gentle rubbing of the leaf (priming) before the heat shock. Movement of these forisomes was also prohibited by Latrunculin A, an inhibitor of actin polymerization. The apparently active mobility of tailed forisomes gives credence to the idea that at least the latter forisomes are not free-floating, but connected to other sieve-element structures. PMID:26624625

  15. Visualization of Uptake of Mineral Elements and the Dynamics of Photosynthates in Arabidopsis by a Newly Developed Real-Time Radioisotope Imaging System (RRIS)

    PubMed Central

    Sugita, Ryohei; Kobayashi, Natsuko I.; Hirose, Atsushi; Saito, Takayuki; Iwata, Ren; Tanoi, Keitaro; Nakanishi, Tomoko M.

    2016-01-01

    Minerals and photosynthates are essential for many plant processes, but their imaging in live plants is difficult. We have developed a method for their live imaging in Arabidopsis using a real-time radioisotope imaging system. When each radioisotope, 22Na, 28Mg, 32P-phosphate, 35S-sulfate, 42K, 45Ca, 54Mn and 137Cs, was employed as an ion tracer, ion movement from root to shoot over 24 h was clearly observed. The movements of 22Na, 42K, 32P, 35S and 137Cs were fast so that they spread to the tip of stems. In contrast, high accumulation of 28Mg, 45Ca and 54Mn was found in the basal part of the main stem. Based on this time-course analysis, the velocity of ion movement in the main stem was calculated, and found to be fastest for S and K among the ions we tested in this study. Furthermore, application of a heat-girdling treatment allowed determination of individual ion movement via xylem flow alone, excluding phloem flow, within the main stem of 43-day-old Arabidopsis inflorescences. We also successfully developed a new system for visualizing photosynthates using labeled carbon dioxide, 14CO2. Using this system, the switching of source/sink organs and phloem flow direction could be monitored in parts of whole shoots and over time. In roots, 14C photosynthates accumulated intensively in the growing root tip area, 200–800 µm behind the meristem. These results show that this real-time radioisotope imaging system allows visualization of many nuclides over a long time-course and thus constitutes a powerful tool for the analysis of various physiological phenomena. PMID:27016100

  16. Visualization of Uptake of Mineral Elements and the Dynamics of Photosynthates in Arabidopsis by a Newly Developed Real-Time Radioisotope Imaging System (RRIS).

    PubMed

    Sugita, Ryohei; Kobayashi, Natsuko I; Hirose, Atsushi; Saito, Takayuki; Iwata, Ren; Tanoi, Keitaro; Nakanishi, Tomoko M

    2016-04-01

    Minerals and photosynthates are essential for many plant processes, but their imaging in live plants is difficult. We have developed a method for their live imaging in Arabidopsis using a real-time radioisotope imaging system. When each radioisotope,(22)Na,(28)Mg,(32)P-phosphate,(35)S-sulfate,(42)K,(45)Ca,(54)Mn and(137)Cs, was employed as an ion tracer, ion movement from root to shoot over 24 h was clearly observed. The movements of(22)Na,(42)K,(32)P,(35)S and(137)Cs were fast so that they spread to the tip of stems. In contrast, high accumulation of(28)Mg,(45)Ca and(54)Mn was found in the basal part of the main stem. Based on this time-course analysis, the velocity of ion movement in the main stem was calculated, and found to be fastest for S and K among the ions we tested in this study. Furthermore, application of a heat-girdling treatment allowed determination of individual ion movement via xylem flow alone, excluding phloem flow, within the main stem of 43-day-old Arabidopsis inflorescences. We also successfully developed a new system for visualizing photosynthates using labeled carbon dioxide,(14)CO2 Using this system, the switching of source/sink organs and phloem flow direction could be monitored in parts of whole shoots and over time. In roots,(14)C photosynthates accumulated intensively in the growing root tip area, 200-800 µm behind the meristem. These results show that this real-time radioisotope imaging system allows visualization of many nuclides over a long time-course and thus constitutes a powerful tool for the analysis of various physiological phenomena. PMID:27016100

  17. Molecular Sieve Regeneration System for assaying HTO from detritiation systems

    SciTech Connect

    Nasise, J.E.; Anderson, J.L.; Naruse, Y.

    1992-07-01

    A Molecular Sieve Regeneration System (MSRS) is being added to the existing Tritium Waste Treatment system (TWT) within the Tritium Systems Test Assembly (TSTA) at the Los Alamos National Laboratory. This system is an upgrade to the TWT to provide accurate measurements of the liquid waste generated from this system. Within the TWT, hydrogen isotopes are removed from the effluent gas stream by the catalytic conversion to water and the subsequent removal of water by molecular sieve trapping prior to the release to the environment. Within the TWT and similar systems, molecular sieve regeneration is required to rejuvenate the beds. The major difference of the MSRS and other regeneration systems is the capability of direct assay of long-term storage waste containers. This is accomplished with loop-flow regeneration, water collection, and tritiated water assay by scintillation and calorimetric techniques. This paper describes the MSRS in detail and how it is interfaced with the Tritium Waste Treatment system.

  18. Molecular Sieve Regeneration System for assaying HTO from detritiation systems

    SciTech Connect

    Nasise, J.E.; Anderson, J.L. ); Naruse, Y. )

    1992-01-01

    A Molecular Sieve Regeneration System (MSRS) is being added to the existing Tritium Waste Treatment system (TWT) within the Tritium Systems Test Assembly (TSTA) at the Los Alamos National Laboratory. This system is an upgrade to the TWT to provide accurate measurements of the liquid waste generated from this system. Within the TWT, hydrogen isotopes are removed from the effluent gas stream by the catalytic conversion to water and the subsequent removal of water by molecular sieve trapping prior to the release to the environment. Within the TWT and similar systems, molecular sieve regeneration is required to rejuvenate the beds. The major difference of the MSRS and other regeneration systems is the capability of direct assay of long-term storage waste containers. This is accomplished with loop-flow regeneration, water collection, and tritiated water assay by scintillation and calorimetric techniques. This paper describes the MSRS in detail and how it is interfaced with the Tritium Waste Treatment system.

  19. Double rotation NMR studies of zeolites and aluminophosphate molecular sieves

    SciTech Connect

    Jelinek, R. |

    1993-07-01

    Goal is to study the organization and structures of guest atoms and molecules and their reactions on internal surfaces within pores of zeolites and aluminophosphate molecular sieves. {sup 27}Al and {sup 23}Na double rotation NMR (DOR) is used since it removes the anisotropic broadening in NMR spectra of quadrupolar nuclei, thus increasing resolution. This work concentrates on probing aluminum framework atoms in aluminophosphate molecular sieves and sodium extra framework cations in porous aluminosilicates. In aluminophosphates, ordering and electronic environments of the framework {sup 27}Al nuclei are modified upon adsorption of water molecules within the channels; a relation is sought between the sieve channel topology and the organization of adsorbed water, as well as the interaction between the Al nuclei and the water molecules. Extra framework Na{sup +} cations are directly involved in adsorption processes and reactions in zeolite cavities.

  20. Carbon molecular sieves for air separation from Nomex aramid fibers.

    PubMed

    Villar-Rodil, Silvia; Martínez-Alonso, Amelia; Tascón, Juan M D

    2002-10-15

    Activated carbon fibers prepared from aramid fibers have proved to possess outstanding homogeneity in pore size, most of all when Nomex aramid fiber is used as precursor. Taking advantage of this feature, microporous carbon molecular sieves for air separation have been prepared through carbon vapor deposition of benzene on Nomex-derived carbon fibers activated to two different burnoff degrees. Carbon molecular sieves with good selectivity for this separation and showing acceptable adsorption capacities were obtained from ACFs activated to the two burnoff degrees chosen. PMID:12702417

  1. Cell Geometry Guides the Dynamic Targeting of Apoplastic GPI-Linked Lipid Transfer Protein to Cell Wall Elements and Cell Borders in Arabidopsis thaliana

    PubMed Central

    Wasteneys, Geoffrey

    2013-01-01

    During cellular morphogenesis, changes in cell shape and cell junction topology are fundamental to normal tissue and organ development. Here we show that apoplastic Glycophosphatidylinositol (GPI)-anchored Lipid Transfer Protein (LTPG) is excluded from cell junctions and flat wall regions, and passively accumulates around their borders in the epidermal cells of Arabidopsis thaliana. Beginning with intense accumulation beneath highly curved cell junction borders, this enrichment is gradually lost as cells become more bulbous during their differentiation. In fully mature epidermal cells, YFP-LTPG often shows a fibrous cellulose microfibril-like pattern within the bulging outer faces. Physical contact between a flat glass surface and bulbous cell surface induces rapid and reversible evacuation from contact sites and accumulation to the curved wall regions surrounding the contact borders. Thus, LTPG distribution is dynamic, responding to changes in cell shape and wall curvature during cell growth and differentiation. We hypothesize that this geometry-based mechanism guides wax-carrying LTPG to functional sites, where it may act to “seal” the vulnerable border surrounding cell-cell junctions and assist in cell wall fortification and cuticular wax deposition. PMID:24260561

  2. Arabidopsis Flower and Embryo Developmental Genes are Repressed in Seedlings by Different Combinations of Polycomb Group Proteins in Association with Distinct Sets of Cis-regulatory Elements

    PubMed Central

    Liu, Jian; Zhang, Lei; He, Chongsheng; Shen, Wen-Hui; Jin, Hong; Xu, Lin; Zhang, Yijing

    2016-01-01

    Polycomb repressive complexes (PRCs) play crucial roles in transcriptional repression and developmental regulation in both plants and animals. In plants, depletion of different members of PRCs causes both overlapping and unique phenotypic defects. However, the underlying molecular mechanism determining the target specificity and functional diversity is not sufficiently characterized. Here, we quantitatively compared changes of tri-methylation at H3K27 in Arabidopsis mutants deprived of various key PRC components. We show that CURLY LEAF (CLF), a major catalytic subunit of PRC2, coordinates with different members of PRC1 in suppression of distinct plant developmental programs. We found that expression of flower development genes is repressed in seedlings preferentially via non-redundant role of CLF, which specifically associated with LIKE HETEROCHROMATIN PROTEIN1 (LHP1). In contrast, expression of embryo development genes is repressed by PRC1-catalytic core subunits AtBMI1 and AtRING1 in common with PRC2-catalytic enzymes CLF or SWINGER (SWN). This context-dependent role of CLF corresponds well with the change in H3K27me3 profiles, and is remarkably associated with differential co-occupancy of binding motifs of transcription factors (TFs), including MADS box and ABA-related factors. We propose that different combinations of PRC members distinctively regulate different developmental programs, and their target specificity is modulated by specific TFs. PMID:26760036

  3. Decolorization / deodorization of zein via activated carbons and molecular sieves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective is to evaluate a series of granular media consisting of activated carbons and molecular sieves in a batch process for the purpose of clarifying and removal of color and odor components from yellow zein dispersed in an aqueous alcohol medium. The major contributors of yellow zein is du...

  4. 21 CFR 173.40 - Molecular sieve resins.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... gram of dry resin (expressed in terms of water regain), and a particle size of 10 to 300 microns. (b) The molecular sieve resins are thoroughly washed with potable water prior to their first use in... purification of partially delactosed whey. The gel bed shall be maintained in a sanitary manner in...

  5. Binding Properties of the N-Acetylglucosamine and High-Mannose N-Glycan PP2-A1 Phloem Lectin in Arabidopsis[W

    PubMed Central

    Beneteau, Julie; Renard, Denis; Marché, Laurent; Douville, Elise; Lavenant, Laurence; Rahbé, Yvan; Dupont, Didier; Vilaine, Françoise; Dinant, Sylvie

    2010-01-01

    Phloem Protein2 (PP2) is a component of the phloem protein bodies found in sieve elements. We describe here the lectin properties of the Arabidopsis (Arabidopsis thaliana) PP2-A1. Using a recombinant protein produced in Escherichia coli, we demonstrated binding to N-acetylglucosamine oligomers. Glycan array screening showed that PP2-A1 also bound to high-mannose N-glycans and 9-acyl-N-acetylneuraminic sialic acid. Fluorescence spectroscopy-based titration experiments revealed that PP2-A1 had two classes of binding site for N,N′,N″-triacetylchitotriose, a low-affinity site and a high-affinity site, promoting the formation of protein dimers. A search for structural similarities revealed that PP2-A1 aligned with the Cbm4 and Cbm22-2 carbohydrate-binding modules, leading to the prediction of a β-strand structure for its conserved domain. We investigated whether PP2-A1 interacted with phloem sap glycoproteins by first characterizing abundant Arabidopsis phloem sap proteins by liquid chromatography-tandem mass spectrometry. Then we demonstrated that PP2-A1 bound to several phloem sap proteins and that this binding was not completely abolished by glycosidase treatment. As many plant lectins have insecticidal activity, we also assessed the effect of PP2-A1 on weight gain and survival in aphids. Unlike other mannose-binding lectins, when added to an artificial diet, recombinant PP2-A1 had no insecticidal properties against Acyrthosiphon pisum and Myzus persicae. However, at mid-range concentrations, the protein affected weight gain in insect nymphs. These results indicate the presence in PP2-A1 of several carbohydrate-binding sites, with potentially different functions in the trafficking of endogenous proteins or in interactions with phloem-feeding insects. PMID:20442276

  6. High-Resolution Solar Imaging With Photon Sieves

    NASA Astrophysics Data System (ADS)

    Oktem, F. S.; Kamalabadi, F.; Davila, J. M.

    2014-12-01

    A photon sieve is a modification of a Fresnel zone plate in which open zones are replaced by a large number of circular holes. This lightweight optical device offers a superior image forming capability compared with the Fresnel zone plate, and is specially suited to observations at UV and x-ray wavelengths where refractive lenses are not available due to strong absorption of materials, and reflective mirrors are difficult to manufacture to achieve near diffraction-limited resolution. At these shorter wavelengths, photon sieves enable diffraction-limited imaging performance with relaxed manufacturing tolerances, and simple and low-cost fabrication. In this work, we present a new photon sieve imaging modality that, unlike previous designs, takes advantage of chromatic aberration. The fact that different wavelengths are focused at different distances from photon sieve is exploited to develop a novel multi-spectral imaging technique. The idea is to use a photon sieve imaging system with a moving detector which records images at different planes. Each measurement consists of superimposed images of different wavelengths, with each individual image being either in focus or out of focus. For spatially incoherent illumination, we study the problem of recovering the individual images from these superimposed measurements. We first formulate the discrete forward problem using the closed-form Fresnel imaging formulas. The inverse problem is then a multi-frame deconvolution problem involving multiple objects, and is formulated as a maximum posterior estimation problem. The resulting nonlinear optimization problem is solved using a fixed-point iterative algorithm. In contrast to traditional spectral imagers employing a series of wavelength filters, the proposed technique relies on a simple optical system, but incorporates powerful image processing methods to form spectral images computationally. In addition to diffraction-limited high spatial resolution enabled by photon sieves

  7. Sulfur-Responsive Elements in the 3′-Nontranscribed Intergenic Region Are Essential for the Induction of SULFATE TRANSPORTER 2;1 Gene Expression in Arabidopsis Roots under Sulfur Deficiency

    PubMed Central

    Maruyama-Nakashita, Akiko; Watanabe-Takahashi, Akiko; Inoue, Eri; Yamaya, Tomoyuki; Saito, Kazuki; Takahashi, Hideki

    2015-01-01

    Under sulfur deficiency (−S), plants induce expression of the sulfate transport systems in roots to increase uptake and root-to-shoot transport of sulfate. The low-affinity sulfate transporter SULTR2;1 is predominantly expressed in xylem parenchyma and pericycle cells in Arabidopsis thaliana roots under –S. The mechanisms underlying –S-inducible expression of SULTR2;1 in roots have remained unclear, despite the possible significance of SULTR2;1 for acclimation to low-sulfur conditions. In this investigation, examination of deletions and base substitutions in the 3′-intergenic region of SULTR2;1 revealed novel sulfur-responsive elements, SURE21A (5′-CAATGTATC-3′) and SURE21B (5′-CTAGTAC-3′), located downstream of the SULTR2;1 3′-untranslated region. SURE21A and SULTR21B effectively induced reporter gene expression from fusion constructs under –S in combination with minimal promoters or promoters not inducible by –S, suggesting their versatility in controlling transcription. T-DNA insertions near SURE21A and SULTR21B abolished −S-inducible expression of SULTR2;1 in roots and reduced the uptake and root-to-shoot transport of sulfate. In addition, these mutations partially suppressed SULTR2;1 expression in shoots, without changing its –S-responsive expression. These findings indicate that SULTR2;1 contributes to the increase in uptake and internal translocation of sulfate driven by gene expression induced under the control of sulfur-responsive elements in the 3′-nontranscribed intergenic region of SULTR2;1. PMID:25855406

  8. Arabidopsis hybrid speciation processes

    PubMed Central

    Schmickl, Roswitha; Koch, Marcus A.

    2011-01-01

    The genus Arabidopsis provides a unique opportunity to study fundamental biological questions in plant sciences using the diploid model species Arabidopsis thaliana and Arabidopsis lyrata. However, only a few studies have focused on introgression and hybrid speciation in Arabidopsis, although polyploidy is a common phenomenon within this genus. More recently, there is growing evidence of significant gene flow between the various Arabidopsis species. So far, we know Arabidopsis suecica and Arabidopsis kamchatica as fully stabilized allopolyploid species. Both species evolved during Pleistocene glaciation and deglaciation cycles in Fennoscandinavia and the amphi-Beringian region, respectively. These hybrid studies were conducted either on a phylogeographic scale or reconstructed experimentally in the laboratory. In our study we focus at a regional and population level. Our research area is located in the foothills of the eastern Austrian Alps, where two Arabidopsis species, Arabidopsis arenosa and A. lyrata ssp. petraea, are sympatrically distributed. Our hypothesis of genetic introgression, migration, and adaptation to the changing environment during the Pleistocene has been confirmed: We observed significant, mainly unidirectional gene flow between the two species, which has given rise to the tetraploid A. lyrata. This cytotype was able to escape from the narrow ecological niche occupied by diploid A. lyrata ssp. petraea on limestone outcrops by migrating northward into siliceous areas, leaving behind a trail of genetic differentiation. PMID:21825128

  9. The feasibility of images reconstructed with the method of sieves

    SciTech Connect

    Veklerov, E.; Llacer, J.

    1989-04-01

    The concept of sieves has been applied with the Maximum likelihood Estimator (MLE) to image reconstruction. While it makes it possible to recover smooth images consistent with the data, the degree of smoothness provided by it is arbitrary. It is shown that the concept of feasibility is able to resolve this arbitrariness. By varying the values of parameters determining the degree of smoothness, one can generate images on both sides of the feasibility region, as well as within the region. Feasible images recovered by using different sieve parameters are compared with feasible results of other procedures. One- and two-dimensional examples using both simulated and real data sets are considered. 12 refs., 3 figs., 2 tabs.

  10. Focusing properties of phase-only generalized Fibonacci photon sieves

    NASA Astrophysics Data System (ADS)

    Ke, Jie; Zhang, Junyong

    2016-06-01

    We propose a new algorithm to extend the standard Fibonacci photon sieve to the phase-only generalized Fibonacci photon sieve (GFiPS) and find that the focusing properties of the phase-only GFiPS are only relevant to the characteristic roots of the recursion relation of the generalized Fibonacci sequences. By switching the transparent and opaque zones on the basis of the generalized Fibonacci sequences, we not only realize adjustable bifocal lengths, but also give their corresponding analytic expressions. Besides, we investigate a special phase-only GFiPS, a spiral-phase GFiPS, which can present twin vortices along the axial coordinate. Compared with the single focusing system, bifocal system can be exploited to enhance the processing speed, and offer a broad range of applications, such as direct laser writing, optical tweezers or atom trapping and paralleled fluorescence microscope.

  11. [Synergetic effects of silicon carbide and molecular sieve loaded catalyst on microwave assisted catalytic oxidation of toluene].

    PubMed

    Wang, Xiao-Hui; Bo, Long-Li; Liu, Hai-Nan; Zhang, Hao; Sun, Jian-Yu; Yang, Li; Cai, Li-Dong

    2013-06-01

    Molecular sieve loaded catalyst was prepared by impregnation method, microwave-absorbing material silicon carbide and the catalyst were investigated for catalytic oxidation of toluene by microwave irradiation. Research work examined effects of silicon carbide and molecular sieve loading Cu-V catalyst's mixture ratio as well as mixed approach changes on degradation of toluene, and characteristics of catalyst were measured through scanning electron microscope, specific surface area test and X-ray diffraction analysis. The result showed that the fixed bed reactor had advantages of both thermal storage property and low-temperature catalytic oxidation when 20% silicon carbide was filled at the bottom of the reactor, and this could effectively improve the utilization of microwave energy as well as catalytic oxidation efficiency of toluene. Under microwave power of 75 W and 47 W, complete-combustion temperatures of molecular sieve loaded Cu-V catalyst and Cu-V-Ce catalyst to toluene were 325 degrees C and 160 degrees C, respectively. Characteristics of the catalysts showed that mixture of rare-earth element Ce increased the dispersion of active components in the surface of catalyst, micropore structure of catalyst effectively guaranteed high adsorption capacity for toluene, while amorphous phase of Cu and V oxides increased the activity of catalyst greatly. PMID:23947020

  12. Carbon fiber composite molecular sieve electrically regenerable air filter media

    DOEpatents

    Wilson, Kirk A.; Burchell, Timothy D.; Judkins, Roddie R.

    1998-01-01

    An electrically regenerable gas filter system includes a carbon fiber composite molecular sieve (CFCMS) filter medium. After a separate medium-efficiency pre-filter removes particulate from the supply airstream, the CFCMS filter sorbs gaseous air pollutants before the air is recirculated to the space. When saturated, the CFCMS media is regenerated utilizing a low-voltage current that is caused to pass through the filter medium.

  13. Carbon fiber composite molecular sieve electrically regenerable air filter media

    DOEpatents

    Wilson, K.A.; Burchell, T.D.; Judkins, R.R.

    1998-10-27

    An electrically regenerable gas filter system includes a carbon fiber composite molecular sieve (CFCMS) filter medium. After a separate medium-efficiency pre-filter removes particulate from the supply air stream, the CFCMS filter sorbs gaseous air pollutants before the air is recirculated to the space. When saturated, the CFCMS media is regenerated utilizing a low-voltage current that is caused to pass through the filter medium. 3 figs.

  14. A differential delay equation arising from the sieve of Eratosthenes

    NASA Technical Reports Server (NTRS)

    Cheer, A. Y.; Goldston, D. A.

    1990-01-01

    Consideration is given to the differential delay equation introduced by Buchstab (1937) in connection with an asymptotic formula for the uncanceled terms in the sieve of Eratosthenes. Maier (1985) used this result to show there is unexpected irreqularity in the distribution of primes in short intervals. The function omega(u) is studied in this paper using numerical and analytical techniques. The results are applied to give some numerical constants in Maier's theorem.

  15. 3D Oxidized Graphene Frameworks for Efficient Nano Sieving.

    PubMed

    Pawar, Pranav Bhagwan; Saxena, Sumit; Badhe, Dhanashree Kamlesh; Chaudhary, Raghvendra Pratap; Shukla, Shobha

    2016-01-01

    The small size of Na(+) and Cl(-) ions provides a bottleneck in desalination and is a challenge in providing alternatives for continuously depleting fresh water resources. Graphene by virtue of its structural properties has the potential to address this issue. Studies have indicated that use of monolayer graphene can be used to filter micro volumes of saline solution. Unfortunately it is extremely difficult, resource intensive and almost impractical with current technology to fabricate operational devices using mono-layered graphene. Nevertheless, graphene based devices still hold the key to solve this problem due to its nano-sieving ability. Here we report synthesis of oxidized graphene frameworks and demonstrate a functional device to desalinate and purify seawater from contaminants including Na(+) and Cl(-) ions, dyes and other microbial pollutants. Micro-channels in these frameworks help in immobilizing larger suspended solids including bacteria, while nano-sieving through graphene enables the removal of dissolved ions (e.g. Cl(-)). Nano-sieving incorporated with larger frameworks has been used in filtering Na(+) and Cl(-) ions in functional devices. PMID:26892277

  16. NMR of small solutes in liquid crystals and molecular sieves

    NASA Astrophysics Data System (ADS)

    Ylihautala, Mika Petri

    The present thesis deals with the nuclear magnetic resonance (NMR) spectroscopy of small solutes applied to the studies of liquid crystals and molecular sieves. In this method, changes induced by the investigated environment to the static spectral parameters (i.e. nuclear shielding, indirect and direct spin-spin coupling and quadrupole coupling) of the solute are measured. The nuclear shielding of dissolved noble gases is utilized for the studies of thermotropic liquid crystals. The relation between the symmetry properties of mesophases and the nuclear shielding is described. The different interaction mechanisms perturbing the observed noble gas nuclear shielding are discussed, particularly, the role of long-range attractive van der Waals interactions is brought out. The suitability of the noble gas NMR spectroscopy to the studies of Iyotropic liquid crystals is investigated in terms of nuclear shielding and quadrupole coupling interactions. In molecular sieve systems, the effect of inter- and intracrystalline motions of solutes on their NMR spectra is discussed. A novel method for the measurement of the intracrystalline motions is developed. The distinctions in the 13C shielding of methane adsorbed in AlPO4-11 and SAPO-11, two structurally similar molecular sieves differing in composition, are indicated.

  17. Predictability sieve, pointer states, and the classicality of quantum trajectories

    SciTech Connect

    Dalvit, D. A. R.; Zurek, W. H.; Dziarmaga, J.

    2005-12-15

    We study various measures of classicality of the states of open quantum systems subject to decoherence. Classical states are expected to be stable in spite of decoherence, and are thought to leave conspicuous imprints on the environment. Here these expected features of environment-induced superselection are quantified using four different criteria: predictability sieve (which selects states that produce least entropy), purification time (which looks for states that are the easiest to find out from the imprint they leave on the environment), efficiency threshold (which finds states that can be deduced from measurements on a smallest fraction of the environment), and purity loss time (that looks for states for which it takes the longest to lose a set fraction of their initial purity). We show that when pointer states--the most predictable states of an open quantum system selected by the predictability sieve--are well defined, all four criteria agree that they are indeed the most classical states. We illustrate this with two examples: an underdamped harmonic oscillator, for which coherent states are unanimously chosen by all criteria, and a free particle undergoing quantum Brownian motion, for which most criteria select almost identical Gaussian states (although, in this case, the predictability sieve does not select well defined pointer states)

  18. 3D Oxidized Graphene Frameworks for Efficient Nano Sieving

    PubMed Central

    Pawar, Pranav Bhagwan; Saxena, Sumit; Badhe, Dhanashree Kamlesh; Chaudhary, Raghvendra Pratap; Shukla, Shobha

    2016-01-01

    The small size of Na+ and Cl− ions provides a bottleneck in desalination and is a challenge in providing alternatives for continuously depleting fresh water resources. Graphene by virtue of its structural properties has the potential to address this issue. Studies have indicated that use of monolayer graphene can be used to filter micro volumes of saline solution. Unfortunately it is extremely difficult, resource intensive and almost impractical with current technology to fabricate operational devices using mono-layered graphene. Nevertheless, graphene based devices still hold the key to solve this problem due to its nano-sieving ability. Here we report synthesis of oxidized graphene frameworks and demonstrate a functional device to desalinate and purify seawater from contaminants including Na+ and Cl− ions, dyes and other microbial pollutants. Micro-channels in these frameworks help in immobilizing larger suspended solids including bacteria, while nano-sieving through graphene enables the removal of dissolved ions (e.g. Cl−). Nano-sieving incorporated with larger frameworks has been used in filtering Na+ and Cl− ions in functional devices. PMID:26892277

  19. Molecular Sieves: Porous Organic Cage Thin Films and Molecular-Sieving Membranes (Adv. Mater. 13/2016).

    PubMed

    Song, Qilei; Jiang, Shan; Hasell, Tom; Liu, Ming; Sun, Shijing; Cheetham, Anthony K; Sivaniah, Easan; Cooper, Andrew I

    2016-04-01

    Porous organic cage molecules are a new class of molecular materials that combine microporosity and solution-processability. On page 2629, E. Sivaniah, A. I. Cooper, and co-workers demonstrate solution processing of cage molecules into thin films with tunable structures. For the first time, cage molecules are fabricated into continuous and pinhole-free microporous molecular-sieving membranes, as confirmed by selective gas transport in terms of high permeance and molecular selectivity. Image credit: Adam Kewley. PMID:27037946

  20. Phloem parenchyma transfer cells in Arabidopsis – an experimental system to identify transcriptional regulators of wall ingrowth formation

    PubMed Central

    Arun Chinnappa, Kiruba S.; Nguyen, Thi Thu S.; Hou, Jiexi; Wu, Yuzhou; McCurdy, David W.

    2013-01-01

    In species performing apoplasmic loading, phloem cells adjacent to sieve elements often develop into transfer cells (TCs) with wall ingrowths. The highly invaginated wall ingrowths serve to amplify plasma membrane surface area to achieve increased rates of apoplasmic transport, and may also serve as physical barriers to deter pathogen invasion. Wall ingrowth formation in TCs therefore plays an important role in phloem biology, however, the transcriptional switches regulating the deposition of this unique example of highly localized wall building remain unknown. Phloem parenchyma (PP) TCs in Arabidopsis veins provide an experimental system to identify such switches. The extent of ingrowth deposition responds to various abiotic and applied stresses, enabling bioinformatics to identify candidate regulatory genes. Furthermore, simple fluorescence staining of PP TCs in leaves enables phenotypic analysis of relevant mutants. Combining these approaches resulted in the identification of GIGANTEA as a regulatory component in the pathway controlling wall ingrowth development in PP TCs. Further utilization of this approach has identified two NAC (NAM, ATAF1/2 and CUC2)-domain and two MYB-related genes as putative transcriptional switches regulating wall ingrowth deposition in these cells. PMID:23630536

  1. Cis and trans-acting elements involved in the activation of Arabidopsis thaliana A1 gene encoding the translation elongation factor EF-1 alpha.

    PubMed

    Curie, C; Liboz, T; Bardet, C; Gander, E; Médale, C; Axelos, M; Lescure, B

    1991-03-25

    In A. thaliana the translation elongation factor EF-1 alpha is encoded by a small multigenic family of four members (A1-A4). The A1 gene promoter has been dissected and examined in a transient expression system using the GUS reporter gene. Deletion analysis has shown that several elements are involved in the activation process. One cis-acting domain, the TEF 1 box, has been accurately mapped 100 bp upstream of the transcription initiation site. This domain is the target for trans-acting factors identified in nuclear extracts prepared from A. thaliana. Homologies are found between the TEF 1 box and sequences present at the same location within the A2, A3 and A4 promoters. This observation, together with those obtained from gel retardation assays performed using DNA fragments from the A4 promoter, suggest that the activation process mediated by the TEF 1 element is conserved among the A. thaliana EF-1 alpha genes. Analysis of nearly full length cDNA clones has shown that in addition to a single intron located within the coding region, the A1 gene contains a second intron located within the 5' non coding region. Such an intron is also present within the A2, A3 and A4 genes. This 5' intervening sequence appears to be essential to obtain a maximum GUS activity driven by the A1 gene promoter. PMID:1840652

  2. Cis and trans-acting elements involved in the activation of Arabidopsis thaliana A1 gene encoding the translation elongation factor EF-1 alpha.

    PubMed Central

    Curie, C; Liboz, T; Bardet, C; Gander, E; Médale, C; Axelos, M; Lescure, B

    1991-01-01

    In A. thaliana the translation elongation factor EF-1 alpha is encoded by a small multigenic family of four members (A1-A4). The A1 gene promoter has been dissected and examined in a transient expression system using the GUS reporter gene. Deletion analysis has shown that several elements are involved in the activation process. One cis-acting domain, the TEF 1 box, has been accurately mapped 100 bp upstream of the transcription initiation site. This domain is the target for trans-acting factors identified in nuclear extracts prepared from A. thaliana. Homologies are found between the TEF 1 box and sequences present at the same location within the A2, A3 and A4 promoters. This observation, together with those obtained from gel retardation assays performed using DNA fragments from the A4 promoter, suggest that the activation process mediated by the TEF 1 element is conserved among the A. thaliana EF-1 alpha genes. Analysis of nearly full length cDNA clones has shown that in addition to a single intron located within the coding region, the A1 gene contains a second intron located within the 5' non coding region. Such an intron is also present within the A2, A3 and A4 genes. This 5' intervening sequence appears to be essential to obtain a maximum GUS activity driven by the A1 gene promoter. Images PMID:1840652

  3. The Arabidopsis Circadian System

    PubMed Central

    McClung, C. Robertson; Salomé, Patrice A.; Michael, Todd P.

    2002-01-01

    Rhythms with periods of approximately 24 hr are widespread in nature. Those that persist in constant conditions are termed circadian rhythms and reflect the activity of an endogenous biological clock. Plants, including Arabidopsis, are richly rhythmic. Expression analysis, most recently on a genomic scale, indicates that the Arabidopsis circadian clock regulates a number of key metabolic pathways and stress responses. A number of sensitive and high-throughput assays have been developed to monitor the Arabidopsis clock. These assays have facilitated the identification of components of plant circadian systems through genetic and molecular biological studies. Although much remains to be learned, the framework of the Arabidopsis circadian system is coming into focus. Dedication This review is dedicated to the memory of DeLill Nasser, a wonderful mentor and an unwavering advocate of both Arabidopsis and circadian rhythms research. PMID:22303209

  4. The function of LPR1 is controlled by an element in the promoter and is independent of SUMO E3 Ligase SIZ1 in response to low Pi stress in Arabidopsis thaliana.

    PubMed

    Wang, Xuemin; Du, Guankui; Wang, Xuming; Meng, Yijun; Li, Yiyi; Wu, Ping; Yi, Keke

    2010-03-01

    In Arabidopsis thaliana, there exist many typical responses to low phosphate (LP) stress, such as inhibition of primary root elongation, proliferation of lateral roots and accumulation of anthocyanin in leaves. The physiological, genetic and molecular mechanisms of these developmental responses remain undefined. We have isolated a phosphorus starvation-insensitive (psi) mutant. The mutant shows impaired inhibition of primary root growth, reduction of root hair growth and reduction of anthocyanin accumulation compared with the wild-type (WT) plants under an LP level. CycB1;1::GUS (cyclin B1;1::beta-glucuronidase) staining suggests that the mutant has a higher ability to maintain cell elongation and cell division than the WT. The genetic analysis and gene cloning indicate that psi is a new allele of lpr1 and that an AC-repeat element in the promoter plays important roles in controlling the expression of LPR1. The psi mutant also shows less sensitivity to auxin treatment compared with the WT and the mutant has an enhanced higher ability to maintain the auxin response in the root tip under LP. However, enhancing the auxin response in the quiescent center cannot mimic the mutant phenotype. These observations suggest that LPR1 is involved in the regulation of the auxin response to Pi starvation and auxin is probably not the only factor affected for maintaining the long-root phenotype under LP stress. Our results also indicate that the function of LPR1 is probably independent of SUMO E3 ligase SIZ1 in response to Pi starvation. The insensitive response of the psi mutant to brefeldin A suggests that LPR1 and PDR2 (Pi Deficiency Response 2) function in opposite ways in regulating the root growth response to Pi starvation in the endoplamic reticulum. PMID:20071375

  5. Arabidopsis miR171-Targeted Scarecrow-Like Proteins Bind to GT cis-Elements and Mediate Gibberellin-Regulated Chlorophyll Biosynthesis under Light Conditions

    PubMed Central

    Ma, Zhaoxue; Hu, Xupeng; Cai, Wenjuan; Huang, Weihua; Zhou, Xin; Luo, Qian; Yang, Hongquan; Wang, Jiawei; Huang, Jirong

    2014-01-01

    An extraordinarily precise regulation of chlorophyll biosynthesis is essential for plant growth and development. However, our knowledge on the complex regulatory mechanisms of chlorophyll biosynthesis is very limited. Previous studies have demonstrated that miR171-targeted scarecrow-like proteins (SCL6/22/27) negatively regulate chlorophyll biosynthesis via an unknown mechanism. Here we showed that SCLs inhibit the expression of the key gene encoding protochlorophyllide oxidoreductase (POR) in light-grown plants, but have no significant effect on protochlorophyllide biosynthesis in etiolated seedlings. Histochemical analysis of β-glucuronidase (GUS) activity in transgenic plants expressing pSCL27::rSCL27-GUS revealed that SCL27-GUS accumulates at high levels and suppresses chlorophyll biosynthesis at the leaf basal proliferation region during leaf development. Transient gene expression assays showed that the promoter activity of PORC is indeed regulated by SCL27. Consistently, chromatin immunoprecipitation and quantitative PCR assays showed that SCL27 binds to the promoter region of PORC in vivo. An electrophoretic mobility shift assay revealed that SCL27 is directly interacted with G(A/G)(A/T)AA(A/T)GT cis-elements of the PORC promoter. Furthermore, genetic analysis showed that gibberellin (GA)-regulated chlorophyll biosynthesis is mediated, at least in part, by SCLs. We demonstrated that SCL27 interacts with DELLA proteins in vitro and in vivo by yeast-two-hybrid and coimmunoprecipitation analysis and found that their interaction reduces the binding activity of SCL27 to the PORC promoter. Additionally, we showed that SCL27 activates MIR171 gene expression, forming a feedback regulatory loop. Taken together, our data suggest that the miR171-SCL module is critical for mediating GA-DELLA signaling in the coordinate regulation of chlorophyll biosynthesis and leaf growth in light. PMID:25101599

  6. Centrifugal Size-Separation Sieve for Granular Materials

    NASA Technical Reports Server (NTRS)

    Walton, Otis (Inventor); Dreyer, Christopher (Inventor); Riedel, Edward (Inventor)

    2015-01-01

    A centrifugal sieve and method utilizes centrifugal force in rapidly-rotated cylindrical or conical screens as the primary body force contributing to size segregation. Within the centrifugal acceleration field, vibration and/or shearing flows are induced to facilitate size segregation and eventual separation of the fines from the coarse material. Inside a rotating cylindrical or conical screen, a separately-rotated screw auger blade can be used to transport material along the rotating cylinder or conical wall and to induce shearing in the material.

  7. Nios II hardware acceleration of the epsilon quadratic sieve algorithm

    NASA Astrophysics Data System (ADS)

    Meyer-Bäse, Uwe; Botella, Guillermo; Castillo, Encarnacion; García, Antonio

    2010-04-01

    The quadratic sieve (QS) algorithm is one of the most powerful algorithms to factor large composite primes used to break RSA cryptographic systems. The hardware structure of the QS algorithm seems to be a good fit for FPGA acceleration. Our new ɛ-QS algorithm further simplifies the hardware architecture making it an even better candidate for C2H acceleration. This paper shows our design results in FPGA resource and performance when implementing very long arithmetic on the Nios microprocessor platform with C2H acceleration for different libraries (GMP, LIP, FLINT, NRMP) and QS architecture choices for factoring 32-2048 bit RSA numbers.

  8. A differential delay equation arising from the sieve of Eratosthenes

    NASA Astrophysics Data System (ADS)

    Cheer, A. Y.; Goldston, D. A.

    1990-07-01

    The differential delay equation defined by ω (u) = 1/u for 1 ≤ u ≤ 2 and (uω (u))' = ω (u - 1) for u ≥ 2 was introduced by Buchstab in connection with an asymptotic formula for the number of uncanceled terms in the sieve of Eratosthenes. Maier has recently used this result to show there is unexpected irregularity in the distribution of primes in short intervals. The function ω (u) is studied in this paper using numerical and analytical techniques. The results are applied to give some numerical constants in Maier's theorem.

  9. A controllable molecular sieve for Na+ and K+ ions.

    PubMed

    Gong, Xiaojing; Li, Jichen; Xu, Ke; Wang, Jianfeng; Yang, Hui

    2010-02-17

    The selective rate of specific ion transport across nanoporous material is critical to biological and nanofluidic systems. Molecular sieves for ions can be achieved by steric and electrical effects. However, the radii of Na(+) and K(+) are quite similar; they both carry a positive charge, making them difficult to separate. Biological ionic channels contain precisely arranged arrays of amino acids that can efficiently recognize and guide the passage of K(+) or Na(+) across the cell membrane. However, the design of inorganic channels with novel recognition mechanisms that control the ionic selectivity remains a challenge. We present here a design for a controllable ion-selective nanopore (molecular sieve) based on a single-walled carbon nanotube with specially arranged carbonyl oxygen atoms modified inside the nanopore, which was inspired by the structure of potassium channels in membrane spanning proteins (e.g., KcsA). Our molecular dynamics simulations show that the remarkable selectivity is attributed to the hydration structure of Na(+) or K(+) confined in the nanochannels, which can be precisely tuned by different patterns of the carbonyl oxygen atoms. The results also suggest that a confined environment plays a dominant role in the selectivity process. These studies provide a better understanding of the mechanism of ionic selectivity in the KcsA channel and possible technical applications in nanotechnology and biotechnology, including serving as a laboratory-in-nanotube for special chemical interactions and as a high-efficiency nanodevice for purification or desalination of sea and brackish water. PMID:20102186

  10. Evaluation of Strontium Selectivity by Sandia Octahedral Molecular Sieves (SOMS).

    SciTech Connect

    Rigali, Mark J.; Stewart, Thomas Austin

    2016-01-01

    Sandia National Laboratories has collaborated with Pleasanton Ridge Research Company (PRRC) to determine whether Sandia Octahedral Molecular Sieves (SOMS) and modified SOMs materials can be synthesized in large batches and produced in granular form. Sandia National Laboratories tested these SOMS and its variants based in aqueous chemical environments for an application-based evaluation of material performance as a sorbent. Testing focused primarily on determining the distribution coefficients (K d ) and chemical selectivity SOMs for alkali earth (Sr) ions in aqueous and dilute seawater solutions. In general the well-crystallized SOMS materials tested exhibited very high K d values (>10 6 ) in distilled water but K d values dropped substantially (%7E10 2 -10 3 ) in the dilute seawater (3%). However, one set of SOMS samples (1.4.2 and 1.4.6) provided by PRRC yielded relatively high K d (approaching 10 4 ) in dilute seawater. Further examination of these samples by scanning electron microscopy (SEM) revealed the presence of at least two phases at least one of which may be accounting for the improved K d values in dilute seawater. Evaluation of Strontium Selectivity by Sandia Octahedral Molecular Sieves (SOMS) January 20, 2016

  11. Analyzing Synthetic Promoters Using Arabidopsis Protoplasts.

    PubMed

    Stracke, Ralf; Thiedig, Katharina; Kuhlmann, Melanie; Weisshaar, Bernd

    2016-01-01

    This chapter describes a transient protoplast co-transfection method that can be used to quantitatively study in vivo the activity and function of promoters and promoter elements (reporters), and their induction or repression by transcription factors (effectors), stresses, hormones, or metabolites. A detailed protocol for carrying out transient co-transfection assays with Arabidopsis At7 protoplasts and calculating the promoter activity is provided. PMID:27557761

  12. Overexpression of IRM1 Enhances Resistance to Aphids in Arabidopsis thaliana

    PubMed Central

    Chen, Xi; Zhang, Zhao; Visser, Richard G. F.; Broekgaarden, Colette; Vosman, Ben

    2013-01-01

    Aphids are insects that cause direct damage to crops by the removal of phloem sap, but more importantly they spread devastating viruses. Aphids use their sophisticated mouthpart (i.e. stylet) to feed from the phloem sieve elements of the host plant. To identify genes that affect host plant resistance to aphids, we previously screened an Arabidopsis thaliana activation tag mutant collection. In such mutants, tagged genes are overexpressed by a strong 35S enhancer adjacent to the natural promoter, resulting in a dominant gain-of-function phenotype. We previously identified several of these mutants on which the aphid Myzus persicae showed a reduced population development compared with wild type. In the present study we show that the gene responsible for the phenotype of one of the mutants is At5g65040 and named this gene Increased Resistance to Myzus persicae 1 (IRM1). Overexpression of the cloned IRM1 gene conferred a phenotype identical to that of the original mutant. Conversely, an IRM1 knockout mutant promoted aphid population development compared to the wild type. We performed Electrical Penetration Graph analysis to investigate how probing and feeding behaviour of aphids was affected on plants that either overexpressed IRM1 or contained a knockout mutation in this gene. The EPG results indicated that the aphids encounter resistance factors while reaching for the phloem on the overexpressing line. This resistance mechanism also affected other aphid species and is suggested to be of mechanical nature. Interestingly, genetic variation for IRM1 expression in response to aphid attack was observed. Upon aphid attack the expression of IRM1 was initially (after 6 hours) induced in ecotype Wassilewskija followed by suppression. In Columbia-0, IRM1 expression was already suppressed six hours after the start of the infestation. The resistance conferred by the overexpression of IRM1 in A. thaliana trades off with plant growth. PMID:23951039

  13. Fractionation of distillers dried grains with solubles (DDGS) by sieving and winnowing.

    PubMed

    Liu, KeShun

    2009-12-01

    Four commercial samples of distillers dried grains with solubles (DDGS) were sieved. All sieved fractions except for the pan fraction, constituting about 90% of original mass, were then winnowed with an air blast seed cleaner. Sieving was effective in producing fractions with varying composition. As the particle size decreased, protein and ash contents increased, and total carbohydrate (CHO) decreased. Winnowing sieved fractions was also effective in shifting composition, particularly for larger particle classes. Heavy sub-fractions were enriched in protein, oil and ash, while light sub-fractions were enriched for CHO. For protein, the combination of the two procedures resulted in a maximum 56.4% reduction in a fraction and maximum 60.2% increase in another fraction. As airflow velocity increased, light sub-fraction mass increased, while the compositional difference between the heavy and light sub-fractions decreased. Winnowing three times at a lower velocity was as effective as winnowing one time at a medium velocity. Winnowing the whole DDGS was much less effective than winnowing sieved fractions in changing composition, but sieving winnowed fractions was more effective than sieving whole DDGS. The two combination sequences gave comparable overall effects but sieving followed by winnowing is recommended because it requires less time. Regardless of combinational sequence, the second procedure was more effective in shifting composition than the first procedure. PMID:19692227

  14. Investigation of Y/SBA Composite Molecular Sieves Morphology Control and Catalytic Performance for n-Pentane Aromatization.

    PubMed

    Shi, Chun-Wei; Wu, Wen-Yuan; Li, Shuai; Bian, Xue; Zhao, Shan-Lin; Pei, Ming-Yuan

    2016-01-01

    Using Y molecular sieve as the core, Y/SBA-15 composite molecular sieves were prepared by different crystallization methods in the paper. The growth process and morphologies of the composite molecular sieves were controlled by adjusting the synthesis factors. The structures and acidity of two kinds of composite molecular sieves were characterized by X-ray diffraction (XRD), N2 adsorption/desorption, transmission electron microscopy (TEM), and NH3-TPD. The catalysis performances of the composite molecular sieves were investigated in the aromatization reaction of n-pentane. The results indicated that the desired core-shell composite molecular sieves were obtained when the crystallization conditions were 36 hours, 100 °C and secondary crystallization. The aromatization results showed that core-shell composite molecular sieves had better selectivity for producing high application value xylenes compared to mixed-crystal composite molecular sieves. PMID:27029526

  15. Investigation of Y/SBA Composite Molecular Sieves Morphology Control and Catalytic Performance for n-Pentane Aromatization

    PubMed Central

    Shi, Chun-Wei; Wu, Wen-Yuan; Li, Shuai; Bian, Xue; Zhao, Shan-lin; Pei, Ming-Yuan

    2016-01-01

    Using Y molecular sieve as the core, Y/SBA-15 composite molecular sieves were prepared by different crystallization methods in the paper. The growth process and morphologies of the composite molecular sieves were controlled by adjusting the synthesis factors. The structures and acidity of two kinds of composite molecular sieves were characterized by X-ray diffraction (XRD), N2 adsorption/desorption, transmission electron microscopy (TEM), and NH3-TPD. The catalysis performances of the composite molecular sieves were investigated in the aromatization reaction of n-pentane. The results indicated that the desired core-shell composite molecular sieves were obtained when the crystallization conditions were 36 hours, 100 °C and secondary crystallization. The aromatization results showed that core-shell composite molecular sieves had better selectivity for producing high application value xylenes compared to mixed-crystal composite molecular sieves. PMID:27029526

  16. Arabidopsis Type I Proton-Pumping Pyrophosphatase Expresses Strongly in Phloem, Where It Is Required for Pyrophosphate Metabolism and Photosynthate Partitioning1[OPEN

    PubMed Central

    Pizzio, Gaston A.; Paez-Valencia, Julio; Khadilkar, Aswad S.; Regmi, Kamesh; Patron-Soberano, Araceli; Zhang, Shangji; Sanchez-Lares, Jonathan; Furstenau, Tara; Li, Jisheng; Sanchez-Gomez, Concepcion; Valencia-Mayoral, Pedro; Yadav, Umesh P.; Ayre, Brian G.; Gaxiola, Roberto A.

    2015-01-01

    Phloem loading is a critical process in plant physiology. The potential of regulating the translocation of photoassimilates from source to sink tissues represents an opportunity to increase crop yield. Pyrophosphate homeostasis is crucial for normal phloem function in apoplasmic loaders. The involvement of Arabidopsis (Arabidopsis thaliana) type I proton-pumping pyrophosphatase (AVP1) in phloem loading was analyzed at genetic, histochemical, and physiological levels. A transcriptional AVP1 promoter::GUS fusion revealed phloem activity in source leaves. Ubiquitous AVP1 overexpression (35S::AVP1 cassette) enhanced shoot biomass, photoassimilate production and transport, rhizosphere acidification, and expression of sugar-induced root ion transporter genes (POTASSIUM TRANSPORTER2 [KUP2], NITRATE TRANSPORTER2.1 [NRT2.1], NRT2.4, and PHOSPHATE TRANSPORTER1.4 [PHT1.4]). Phloem-specific AVP1 overexpression (Commelina Yellow Mottle Virus promoter [pCOYMV]::AVP1) elicited similar phenotypes. By contrast, phloem-specific AVP1 knockdown (pCoYMV::RNAiAVP1) resulted in stunted seedlings in sucrose-deprived medium. We also present a promoter mutant avp1-2 (SALK046492) with a 70% reduction of expression that did not show severe growth impairment. Interestingly, AVP1 protein in this mutant is prominent in the phloem. Moreover, expression of an Escherichia coli-soluble pyrophosphatase in the phloem (pCoYMV::pyrophosphatase) of avp1-2 plants resulted in severe dwarf phenotype and abnormal leaf morphology. We conclude that the Proton-Pumping Pyrophosphatase AVP1 localized at the plasma membrane of the sieve element-companion cell complexes functions as a synthase, and that this activity is critical for the maintenance of pyrophosphate homeostasis required for phloem function. PMID:25681328

  17. Association between minor loading vein architecture and light- and CO2-saturated rates of photosynthetic oxygen evolution among Arabidopsis thaliana ecotypes from different latitudes

    PubMed Central

    Cohu, Christopher M.; Muller, Onno; Stewart, Jared J.; Demmig-Adams, Barbara; Adams, William W.

    2013-01-01

    Through microscopic analysis of veins and assessment of light- and CO2-saturated rates of photosynthetic oxygen evolution, we investigated the relationship between minor loading vein anatomy and photosynthesis of mature leaves in three ecotypes of Arabidopsis thaliana grown under four different combinations of temperature and photon flux density (PFD). All three ecotypes exhibited greater numbers and cross-sectional area of phloem cells as well as higher photosynthesis rates in response to higher PFD and especially lower temperature. The Swedish ecotype exhibited the strongest response to these conditions, the Italian ecotype the weakest response, and the Col-0 ecotype exhibited an intermediate response. Among all three ecotypes, strong linear relationships were found between light- and CO2-saturated rates of photosynthetic oxygen evolution and the number and area of either sieve elements or of companion and phloem parenchyma cells in foliar minor loading veins, with the Swedish ecotype showing the highest number of cells in minor loading veins (and largest minor veins) coupled with unprecedented high rates of photosynthesis. Linear, albeit less significant, relationships were also observed between number and cross-sectional area of tracheids per minor loading vein versus light- and CO2-saturated rates of photosynthetic oxygen evolution. We suggest that sugar distribution infrastructure in the phloem is co-regulated with other features that set the upper limit for photosynthesis. The apparent genetic differences among Arabidopsis ecotypes should allow for future identification of the gene(s) involved in augmenting sugar-loading and -transporting phloem cells and maximal rates of photosynthesis. PMID:23898338

  18. Method of recovering adsorbed liquid compounds from molecular sieve columns

    DOEpatents

    Burkholder, Harvey R.; Fanslow, Glenn E.

    1983-01-01

    Molecularly adsorbed volatile liquid compounds are recovered from molecular sieve adsorbent columns by directionally applying microwave energy to the bed of the adsorbent to produce a mixed liquid-gas effluent. The gas portion of the effluent generates pressure within the bed to promote the discharge of the effluent from the column bottoms. Preferably the discharged liquid-gas effluent is collected in two to three separate fractions, the second or intermediate fraction having a substantially higher concentration of the desorbed compound than the first or third fractions. The desorption does not need to be assisted by passing a carrier gas through the bed or by applying reduced pressure to the outlet from the bed.

  19. Transformation of metal-organic frameworks for molecular sieving membranes

    PubMed Central

    Li, Wanbin; Zhang, Yufan; Zhang, Congyang; Meng, Qin; Xu, Zehai; Su, Pengcheng; Li, Qingbiao; Shen, Chong; Fan, Zheng; Qin, Lei; Zhang, Guoliang

    2016-01-01

    The development of simple, versatile strategies for the synthesis of metal-organic framework (MOF)-derived membranes are of increasing scientific interest, but challenges exist in understanding suitable fabrication mechanisms. Here we report a route for the complete transformation of a series of MOF membranes and particles, based on multivalent cation substitution. Through our approach, the effective pore size can be reduced through the immobilization of metal salt residues in the cavities, and appropriate MOF crystal facets can be exposed, to achieve competitive molecular sieving capabilities. The method can also be used more generally for the synthesis of a variety of MOF membranes and particles. Importantly, we design and synthesize promising MOF membranes candidates that are hard to achieve through conventional methods. For example, our CuBTC/MIL-100 membrane exhibits 89, 171, 241 and 336 times higher H2 permeance than that of CO2, O2, N2 and CH4, respectively. PMID:27090597

  20. Method of recovering adsorbed liquid compounds from molecular sieve columns

    DOEpatents

    Burkholder, H.R.; Fanslow, G.E.

    1983-12-20

    Molecularly adsorbed volatile liquid compounds are recovered from molecular sieve adsorbent columns by directionally applying microwave energy to the bed of the adsorbent to produce a mixed liquid-gas effluent. The gas portion of the effluent generates pressure within the bed to promote the discharge of the effluent from the column bottoms. Preferably the discharged liquid-gas effluent is collected in two to three separate fractions, the second or intermediate fraction having a substantially higher concentration of the desorbed compound than the first or third fractions. The desorption does not need to be assisted by passing a carrier gas through the bed or by applying reduced pressure to the outlet from the bed. 8 figs.

  1. Transformation of metal-organic frameworks for molecular sieving membranes

    NASA Astrophysics Data System (ADS)

    Li, Wanbin; Zhang, Yufan; Zhang, Congyang; Meng, Qin; Xu, Zehai; Su, Pengcheng; Li, Qingbiao; Shen, Chong; Fan, Zheng; Qin, Lei; Zhang, Guoliang

    2016-04-01

    The development of simple, versatile strategies for the synthesis of metal-organic framework (MOF)-derived membranes are of increasing scientific interest, but challenges exist in understanding suitable fabrication mechanisms. Here we report a route for the complete transformation of a series of MOF membranes and particles, based on multivalent cation substitution. Through our approach, the effective pore size can be reduced through the immobilization of metal salt residues in the cavities, and appropriate MOF crystal facets can be exposed, to achieve competitive molecular sieving capabilities. The method can also be used more generally for the synthesis of a variety of MOF membranes and particles. Importantly, we design and synthesize promising MOF membranes candidates that are hard to achieve through conventional methods. For example, our CuBTC/MIL-100 membrane exhibits 89, 171, 241 and 336 times higher H2 permeance than that of CO2, O2, N2 and CH4, respectively.

  2. Carbon dioxide sorption in a nanoporous octahedral molecular sieve

    NASA Astrophysics Data System (ADS)

    Williamson, Izaak; Nelson, Eric B.; Li, Lan

    2015-08-01

    We have performed first-principles density functional theory calculations, incorporated with van der Waals interactions, to study CO2 adsorption and diffusion in nanoporous solid—OMS-2 (Octahedral Molecular Sieve). We found the charge, type, and mobility of a cation, accommodated in a porous OMS-2 material for structural stability, can affect not only the OMS-2 structural features but also CO2 sorption performance. This paper targets K+, Na+, and Ba2+ cations. First-principles energetics and electronic structure calculations indicate that Ba2+ has the strongest interaction with the OMS-2 porous surface due to valence electrons donation to the OMS-2 and molecular orbital hybridization. However, the Ba-doped OMS-2 has the worst CO2 uptake capacity. We also found evidence of sorption hysteresis in the K- and Na-doped OMS-2 materials.

  3. A Sieving ANN for Emotion-Based Movie Clip Classification

    NASA Astrophysics Data System (ADS)

    Watanapa, Saowaluk C.; Thipakorn, Bundit; Charoenkitkarn, Nipon

    Effective classification and analysis of semantic contents are very important for the content-based indexing and retrieval of video database. Our research attempts to classify movie clips into three groups of commonly elicited emotions, namely excitement, joy and sadness, based on a set of abstract-level semantic features extracted from the film sequence. In particular, these features consist of six visual and audio measures grounded on the artistic film theories. A unique sieving-structured neural network is proposed to be the classifying model due to its robustness. The performance of the proposed model is tested with 101 movie clips excerpted from 24 award-winning and well-known Hollywood feature films. The experimental result of 97.8% correct classification rate, measured against the collected human-judges, indicates the great potential of using abstract-level semantic features as an engineered tool for the application of video-content retrieval/indexing.

  4. Transformation of metal-organic frameworks for molecular sieving membranes.

    PubMed

    Li, Wanbin; Zhang, Yufan; Zhang, Congyang; Meng, Qin; Xu, Zehai; Su, Pengcheng; Li, Qingbiao; Shen, Chong; Fan, Zheng; Qin, Lei; Zhang, Guoliang

    2016-01-01

    The development of simple, versatile strategies for the synthesis of metal-organic framework (MOF)-derived membranes are of increasing scientific interest, but challenges exist in understanding suitable fabrication mechanisms. Here we report a route for the complete transformation of a series of MOF membranes and particles, based on multivalent cation substitution. Through our approach, the effective pore size can be reduced through the immobilization of metal salt residues in the cavities, and appropriate MOF crystal facets can be exposed, to achieve competitive molecular sieving capabilities. The method can also be used more generally for the synthesis of a variety of MOF membranes and particles. Importantly, we design and synthesize promising MOF membranes candidates that are hard to achieve through conventional methods. For example, our CuBTC/MIL-100 membrane exhibits 89, 171, 241 and 336 times higher H2 permeance than that of CO2, O2, N2 and CH4, respectively. PMID:27090597

  5. Biofuel Manufacturing from Woody Biomass: Effects of Sieve Size Used in Biomass Size Reduction

    PubMed Central

    Zhang, Meng; Song, Xiaoxu; Deines, T. W.; Pei, Z. J.; Wang, Donghai

    2012-01-01

    Size reduction is the first step for manufacturing biofuels from woody biomass. It is usually performed using milling machines and the particle size is controlled by the size of the sieve installed on a milling machine. There are reported studies about the effects of sieve size on energy consumption in milling of woody biomass. These studies show that energy consumption increased dramatically as sieve size became smaller. However, in these studies, the sugar yield (proportional to biofuel yield) in hydrolysis of the milled woody biomass was not measured. The lack of comprehensive studies about the effects of sieve size on energy consumption in biomass milling and sugar yield in hydrolysis process makes it difficult to decide which sieve size should be selected in order to minimize the energy consumption in size reduction and maximize the sugar yield in hydrolysis. The purpose of this paper is to fill this gap in the literature. In this paper, knife milling of poplar wood was conducted using sieves of three sizes (1, 2, and 4 mm). Results show that, as sieve size increased, energy consumption in knife milling decreased and sugar yield in hydrolysis increased in the tested range of particle sizes. PMID:22665985

  6. Clast-contact conglomerates in submarine canyons: possible subaqueous sieve deposits

    SciTech Connect

    Fitzgerald, M.S.

    1987-05-01

    Thick, coarse, clast-contact conglomerates in submarine canyon fill have previously been attributed to rock-fall, grain-flow, or winnowing processes. However, these processes do not adequately explain some thick conglomeratic sequences. The proposed process of subaqueous sieve deposition could account for these clast-contact conglomerates. Subaerial sieve deposition has been documented on small-scale fan models and on alluvial fans. A subaerial sieve deposit begins as a debris flow which at some point freezes up. The matrix is then lost by subsequent filtration or outflow, and the emplacement of a clast-contact gravel ensues. A subaqueous sieve deposit would be slightly modified in that the matrix would not be lost by filtration into the submarine canyon floor, but rather by outflow at the terminus of the lobe immediately after deposition, or possibly from the top and/or sides of the freezing flow mass during transport. Besides forming in submarine canyons, subaqueous sieve deposits might also occur in paralic, submarine fan channel, and base-of-the-slope settings. In substantiating the existence of subaqueous sieve deposits, the sedimentary structures and grain-size data from recent sieve deposits on alluvial fans are compared to those of ancient submarine canyon deposits. Numerous similarities are found supporting this new method of deposition. Some discrepancies are encountered, but these are expected due to modifications caused by an aqueous medium.

  7. H+-PPase AVP1 is necessary for phloem development in Arabidopsis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The presence of a plasma membrane (PM) localized type I H+-PPase in sieve elements of Ricinus communis was documented years ago. Unfortunately, the physiological and developmental relevance of these findings remained obscure due to the lack of genetic and molecular reagents to study Ricinus communis...

  8. Fringe field NMR diffusometry of anomalous self-diffusion in molecular sieves

    NASA Astrophysics Data System (ADS)

    Ylihautala, Mika; Jokisaari, Jukka; Fischer, Elmar; Kimmich, Rainer

    1998-06-01

    Superconducting magnet fringe field NMR diffusometry is applied to an adsorbate-molecular sieve system in order to obtain intracrystalline self-diffusion of adsorbed molecules. Effects of self-diffusion, exchange, relaxation, and dipolar correlation are discussed. The proper equations for one- and two-dimensional anomalous self-diffusion with and without macroscopic order are derived. The method is applied to investigate methane self-diffusion in the molecular sieve silicoaluminophosphate, type 11 (SAPO-11). It is concluded that the nature of the methane displacements in the sieve channels is single-file self-diffusion.

  9. Peculiarities in formation of Arabidopsis Thaliana (L.) Heynh, generative organs under space flight conditions

    NASA Technical Reports Server (NTRS)

    Kordyum, Y. L.; Chernyayeva, I. I.

    1983-01-01

    Peculiarities in the formation of the andrecium and gynecium elements are described for Arabidopsis plants grown from the stages of two cotyledonous leaves in the Svitoblok-1 device on board the Salyut 6 orbital research station and in the laboratory. It is established that flower buds and flowers, normally formed in habitus, contain sterile elements of andrecium and gynecium whose degeneration occurs at different developmental stages of the Arabidopsis plants in the experiment under conditions of weightlessness.

  10. Copia-, Gypsy- and Line-like Retrotransposon Fragments in the Mitochondrial Genome of Arabidopsis Thaliana

    PubMed Central

    Knoop, V.; Unseld, M.; Marienfeld, J.; Brandt, P.; Sunkel, S.; Ullrich, H.; Brennicke, A.

    1996-01-01

    Several retrotransposon fragments are integrated in the mitochondrial genome of Arabidopsis thaliana. These insertions are derived from all three classes of nuclear retrotransposons, the Ty1/copia-, Ty3/gypsy- and non-LTR/LINE-families. Members of the Ty3/gypsy group of elements have not yet been identified in the nuclear genome of Arabidopsis. The varying degrees of similarity with nuclear elements and the dispersed locations of the sequences in the mitochondrial genome suggest numerous independent transfer-insertion events in the evolutionary history of this plant mitochondrial genome. Overall, we estimate remnants of retrotransposons to cover >/=5% of the mitochondrial genome in Arabidopsis. PMID:8852855

  11. Design, in vitro and in vivo assessment of a multi-channel sieve electrode with integrated multiplexer

    NASA Astrophysics Data System (ADS)

    Ramachandran, Anup; Schuettler, Martin; Lago, Natalia; Doerge, Thomas; Koch, Klaus Peter; Navarro, Xavier; Hoffmann, Klaus-Peter; Stieglitz, Thomas

    2006-06-01

    This paper reports on the design, in vitro and in vivo investigation of a flexible, lightweight, polyimide based implantable sieve electrode with a hybrid assembly of multiplexers and polymer encapsulation. The integration of multiplexers enables us to connect a large number of electrodes on the sieve using few input connections. The implant assembly of the sieve electrode with the electronic circuitry was verified by impedance measurement. The 27 platinum electrodes of the sieve were coated with platinum black to reduce the electrode impedance. The impedance magnitude of the electrode sites on the sieve (geometric surface area 2200 µm2) was |Zf=1kHz| = 5.7 kΩ. The sieve electrodes, encased in silicone, have been implanted in the transected sciatic nerve of rats. Initial experiments showed that axons regenerated through the holes of the sieve and reinnervated distal target organs. Nerve signals were recorded in preliminary tests after 3-7 months post-implantation.

  12. Use of Carbon Fiber Composite Molecular Sieves for Air Separation

    SciTech Connect

    Baker, Frederick S; Contescu, Cristian I; Gallego, Nidia C; Burchell, Timothy D

    2005-09-01

    A novel adsorbent material, 'carbon fiber composite molecular sieve' (CFCMS), has been developed by the Oak Ridge National Laboratory. Its features include high surface area, large pore volume, and a rigid, permeable carbon structure that exhibits significant electrical conductivity. The unique combination of high adsorptive capacity, permeability, good mechanical properties, and electrical conductivity represents an enabling technology for the development of novel gas separation and purification systems. In this context, it is proposed that a fast-cycle air separation process that exploits a kinetic separation of oxygen and nitrogen should be possible using a CFCMS material coupled with electrical swing adsorption (ESA). The adsorption of O{sub 2}, N{sub 2}, and CO{sub 2} on activated carbon fibers was investigated using static and dynamic techniques. Molecular sieving effects in the activated carbon fiber were highlighted by the adsorption of CO{sub 2}, a more sensitive probe molecule for the presence of microporosity in adsorbents. The kinetic studies revealed that O2 was more rapidly adsorbed on the carbon fiber than N{sub 2}, and with higher uptake under equilibrium conditions, providing the fiber contained a high proportion of very narrow micropores. The work indicated that CFCMS is capable of separating O{sub 2} and N{sub 2} from air on the basis of the different diffusion rates of the two molecules in the micropore network of the activated carbon fibers comprising the composite material. In response to recent enquires from several potential users of CFCMS materials, attention has been given to the development of a viable continuous process for the commercial production of CFCMS material. As part of this effort, work was implemented on characterizing the performance of lignin-based activated carbon fiber, a potentially lower cost fiber than the pitch-based fibers used for CFCMS production to date. Similarly, to address engineering issues, measurements were

  13. Starch Metabolism in Arabidopsis

    PubMed Central

    Streb, Sebastian; Zeeman, Samuel C.

    2012-01-01

    Starch is the major non-structural carbohydrate in plants. It serves as an important store of carbon that fuels plant metabolism and growth when they are unable to photosynthesise. This storage can be in leaves and other green tissues, where it is degraded during the night, or in heterotrophic tissues such as roots, seeds and tubers, where it is stored over longer time periods. Arabidopsis accumulates starch in many of its tissues, but mostly in its leaves during the day. It has proven to be a powerful genetic system for discovering how starch is synthesised and degraded, and new proteins and processes have been discovered. Such work has major significance for our starch crops, whose yield and quality could be improved by the application of this knowledge. Research into Arabidopsis starch metabolism has begun to reveal how its daily turnover is integrated into the rest of metabolism and adapted to the environmental conditions. Furthermore, Arabidopsis mutant lines deficient in starch metabolism have been employed as tools to study other biological processes ranging from sugar sensing to gravitropism and flowering time control. This review gives a detailed account of the use of Arabidopsis to study starch metabolism. It describes the major discoveries made and presents an overview of our understanding today, together with some as-yet unresolved questions. PMID:23393426

  14. Tunable ionic-conductivity of collapsed Sandia octahedral molecular sieves (SOMS).

    SciTech Connect

    Pless, Jason; Nenoff, Tina Maria; Garino, Terry J.; Axness, Marlene

    2006-11-01

    This proposal focuses on the synthesis and characterization of ''tunable'' perovskite ceramics with resulting controlled strength and temperature of dielectric constants and/or with ionic conductivity. Traditional methods of synthesis involve high temperature oxide mixing and baking. We developed a new methodology of synthesis involving the (1) low temperature hydrothermal synthesis of metastable porous phases with ''tuned'' stoichiometry, and element types, and then (2) low temperature heat treatment to build exact stoichiometry perovskites, with the desired vacancy concentrations. This flexible pathway can lead to compositions and structures not attainable by conventional methods. During the course of this program, a series of Na-Nb perovskites were synthesized by calcining and collapsing microporous Sandia Octahedral Molecular Sieve (SOMS) phases. These materials were studied by various characterization techniques and conductivity measurements to better delineate stability and stoichiometry/bulk conductivity relationships. The conductivity can be altered by changing the concentration and type of the substituting framework cation(s) or by ion exchange of sodium. To date, the Na{sub 0.9}Mg{sub 0.1}Nb{sub 0.8}Ti{sub 0.2}O{sub 3-{delta}} shows the best conductivity.

  15. Covalent anchoring of chloroperoxidase and glucose oxidase on the mesoporous molecular sieve SBA-15.

    PubMed

    Jung, Dirk; Streb, Carsten; Hartmann, Martin

    2010-01-01

    Functionalization of porous solids plays an important role in many areas, including heterogeneous catalysis and enzyme immobilization. In this study, large-pore ordered mesoporous SBA-15 molecular sieves were synthesized with tetraethyl orthosilicate (TEOS) in the presence of the non-ionic triblock co-polymer Pluronic P123 under acidic conditions. These materials were grafted with 3-aminopropyltrimethoxysilane (ATS), 3-glycidoxypropyltrimethoxysilane (GTS) and with 3-aminopropyltrimethoxysilane and glutaraldehyde (GA-ATS) in order to provide covalent anchoring points for enzymes. The samples were characterized by nitrogen adsorption, powder X-ray diffraction, solid-state NMR spectroscopy, elemental analysis, diffuse reflectance fourier transform infrared spectroscopy and diffuse reflectance UV/Vis spectroscopy. The obtained grafted materials were then used for the immobilization of chloroperoxidase (CPO) and glucose oxidase (GOx) and the resulting biocatalysts were tested in the oxidation of indole. It is found that enzymes anchored to the mesoporous host by the organic moieties can be stored for weeks without losing their activity. Furthermore, the covalently linked enzymes are shown to be less prone to leaching than the physically adsorbed enzymes, as tested in a fixed-bed reactor under continuous operation conditions. PMID:20386667

  16. Dr. Grant Heikan examines lunar material in sieve from sample container

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Dr. Grant Heikan, Manned Spacecraft Center and a Lunar Sample preliminary Examination Team member, examines lunar material in a sieve from the bulk sample container which was opened in the Biopreparation Laboratory of the Lunar Receiving Laboratory.

  17. Centrifugal Sieve for Gravity-Level-Independent Size Segregation of Granular Materials

    NASA Technical Reports Server (NTRS)

    Walton, Otis R.; Dreyer, Christopher; Riedel, Edward

    2013-01-01

    Conventional size segregation or screening in batch mode, using stacked vibrated screens, is often a time-consuming process. Utilization of centrifugal force instead of gravity as the primary body force can significantly shorten the time to segregate feedstock into a set of different-sized fractions. Likewise, under reduced gravity or microgravity, a centrifugal sieve system would function as well as it does terrestrially. When vibratory and mechanical blade sieving screens designed for terrestrial conditions were tested under lunar gravity conditions, they did not function well. The centrifugal sieving design of this technology overcomes the issues that prevented sieves designed for terrestrial conditions from functioning under reduced gravity. These sieves feature a rotating outer (cylindrical or conical) screen wall, rotating fast enough for the centrifugal forces near the wall to hold granular material against the rotating screen. Conventional centrifugal sieves have a stationary screen and rapidly rotating blades that shear the granular solid near the stationary screen, and effect the sieving process assisted by the airflow inside the unit. The centrifugal sieves of this new design may (or may not) have an inner blade or blades, moving relative to the rotating wall screen. Some continuous flow embodiments would have no inner auger or blades, but achieve axial motion through vibration. In all cases, the shearing action is gentler than conventional centrifugal sieves, which have very high velocity differences between the stationary outer screen and the rapidly rotating blades. The new design does not depend on airflow in the sieving unit, so it will function just as well in vacuum as in air. One advantage of the innovation for batch sieving is that a batch-mode centrifugal sieve may accomplish the same sieving operation in much less time than a conventional stacked set of vibrated screens (which utilize gravity as the primary driving force for size separation

  18. A patterned anisotropic nanofluidic sieving structure for continuous-flow separation of DNA and proteins

    PubMed Central

    Fu, Jianping; Schoch, Reto B.; Stevens, Anna L.; Tannenbaum, Steven R.; Han, Jongyoon

    2008-01-01

    Microfabricated regular sieving structures hold great promise as an alternative to gels to improve biomolecule separation speed and resolution. In contrast to disordered gel porous networks, these regular structures also provide well-defined environments ideal for study of molecular dynamics in confining spaces. However, previous regular sieving structures have been limited for separation of long DNA molecules, and separation of smaller, physiologically-relevant macromolecules, such as proteins, still remains as a challenge. Here we report a microfabricated anisotropic sieving structure consisting of a two-dimensional periodic nanofluidic filter array (Anisotropic Nanofilter Array: ANA). The designed structural anisotropy in the ANA causes different-sized or -charged biomolecules to follow distinct trajectories, leading to efficient separation. Continuous-flow size-based separation of DNA and proteins as well as electrostatic separation of proteins were achieved, thus demonstrating the potential of the ANA as a generic molecular sieving structure for an integrated biomolecule sample preparation and analysis system. PMID:18654231

  19. Continuous-Flow Bioseparation Using Microfabricated Anisotropic Nanofluidic Sieving Structures

    PubMed Central

    Fu, Jianping; Mao, Pan; Han, Jongyoon

    2010-01-01

    The anisotropic nanofluidic filter (nanofilter) array (ANA) is a unique molecular sieving structure for separating biomolecules. Here we describe fabrication of planar and vertical ANA chips and how to perform continuous-flow bioseparation using them. This protocol is most useful for bioengineers that are interested in developing automated multistep chip-based bioanalysis systems and assumes prior cleanroom microfabrication knowledge. The ANA consists of a two-dimensional periodic nanofilter array, and the designed structural anisotropy of the ANA causes different sized- or charged-biomolecules to follow distinct trajectories under applied electric fields, leading to efficient continuous-flow separation. Using microfluidic channels surrounding the ANA, the fractionated biomolecule streams are collected and routed to different fluid channels or reservoirs for convenient sample recovery and downstream bioanalysis. The ANA is physically robust and can be reused repeatedly. Compared to conventional gel-based separation techniques, the ANA offers the potential for faster separation, higher throughput, and more convenient sample recovery. PMID:19876028

  20. Shape-selective sieving layers on an oxide catalyst surface.

    PubMed

    Canlas, Christian P; Lu, Junling; Ray, Natalie A; Grosso-Giordano, Nicolas A; Lee, Sungsik; Elam, Jeffrey W; Winans, Randall E; Van Duyne, Richard P; Stair, Peter C; Notestein, Justin M

    2012-12-01

    New porous materials such as zeolites, metal-organic frameworks and mesostructured oxides are of immense practical utility for gas storage, separations and heterogeneous catalysis. Their extended pore structures enable selective uptake of molecules or can modify the product selectivity (regioselectivity or enantioselectivity) of catalyst sites contained within. However, diffusion within pores can be problematic for biomass and fine chemicals, and not all catalyst classes can be readily synthesized with pores of the correct dimensions. Here, we present a novel approach that adds reactant selectivity to existing, non-porous oxide catalysts by first grafting the catalyst particles with single-molecule sacrificial templates, then partially overcoating the catalyst with a second oxide through atomic layer deposition. This technique is used to create sieving layers of Al(2)O(3) (thickness, 0.4-0.7 nm) with 'nanocavities' (<2 nm in diameter) on a TiO(2) photocatalyst. The additional layers result in selectivity (up to 9:1) towards less hindered reactants in otherwise unselective, competitive photocatalytic oxidations and transfer hydrogenations. PMID:23174984

  1. Shape-selective sieving layers on an oxide catalyst surface

    NASA Astrophysics Data System (ADS)

    Canlas, Christian P.; Lu, Junling; Ray, Natalie A.; Grosso-Giordano, Nicolas A.; Lee, Sungsik; Elam, Jeffrey W.; Winans, Randall E.; van Duyne, Richard P.; Stair, Peter C.; Notestein, Justin M.

    2012-12-01

    New porous materials such as zeolites, metal-organic frameworks and mesostructured oxides are of immense practical utility for gas storage, separations and heterogeneous catalysis. Their extended pore structures enable selective uptake of molecules or can modify the product selectivity (regioselectivity or enantioselectivity) of catalyst sites contained within. However, diffusion within pores can be problematic for biomass and fine chemicals, and not all catalyst classes can be readily synthesized with pores of the correct dimensions. Here, we present a novel approach that adds reactant selectivity to existing, non-porous oxide catalysts by first grafting the catalyst particles with single-molecule sacrificial templates, then partially overcoating the catalyst with a second oxide through atomic layer deposition. This technique is used to create sieving layers of Al2O3 (thickness, 0.4-0.7 nm) with ‘nanocavities’ (<2 nm in diameter) on a TiO2 photocatalyst. The additional layers result in selectivity (up to 9:1) towards less hindered reactants in otherwise unselective, competitive photocatalytic oxidations and transfer hydrogenations.

  2. Sieve of Eratosthenes benchmarks for the Z8 FORTH microcontroller

    SciTech Connect

    Edwards, R.

    1989-02-01

    This report presents benchmarks for the Z8 FORTH microcontroller system that ORNL uses extensively in proving concepts and developing prototype test equipment for the Smart House Project. The results are based on the sieve of Eratosthenes algorithm, a calculation used extensively to rate computer systems and programming languages. Three benchmark refinements are presented,each showing how the execution speed of a FORTH program can be improved by use of a particular optimization technique. The last version of the FORTH benchmark shows that optimization is worth the effort: It executes 20 times faster than the Gilbreaths' widely-published FORTH benchmark program. The National Association of Home Builders Smart House Project is a cooperative research and development effort being undertaken by American home builders and a number of major corporations serving the home building industry. The major goal of the project is to help the participating organizations incorporate advanced technology in communications,energy distribution, and appliance control products for American homes. This information is provided to help project participants use the Z8 FORTH prototyping microcontroller in developing Smart House concepts and equipment. The discussion is technical in nature and assumes some experience with microcontroller devices and the techniques used to develop software for them. 7 refs., 5 tabs.

  3. A sieving method for collecting the metacercariae of trematode parasites from freshwater fish.

    PubMed

    Fan, P C; Wu, C C; Huang, P; Yen, C W

    2002-03-01

    This study describes a sieving method for the collection of metacercariae from frozen (-20 degrees C) freshwater fish. Digested fish tissue is filtered through a series of sieves; the crude filtrate is then centrifuged. Centrifugation produces a sediment from which metacercariae can be removed. Half of the metracercariae that were obtained from the fish meat that had been frozen for 10 days (-20 degrees C) were dead; the other half were alive and some larvae were moving slowly. PMID:12118453

  4. Sieve efficiency in benthic sampling as related to chironomid head capsule width

    USGS Publications Warehouse

    Hudson, Patrick L.; Adams, Jean V.

    1998-01-01

    The width of the head capsule in chironomid larvae is the most important morphometric character controlling retention of specimens in sieving devices. Knowledge of the range in size of these widths within any chironomid community is fundamental to sampling and interpreting the resulting data. We present the head capsule widths of 30 species of chironomids and relate their size distribution to loss or retention in several experiments using graded sieve sizes. Based on our measurements and those found in the literature we found the head capsule width of fourth instars in half the chironomids species to be less than 350 I?m. Many species may never be collected with the commonly used U.S. Standard No. 30 sieve (589 I?m), and the No. 60 (246 I?m) screen appears to retain most species only qualitatively. We found 70 to 90% of the chironomid larvae and 19 to 34% of their biomass can pass through a No. 80 sieve (177 I?m). The implications of sieve loss and other factors affecting sieving efficiency are discussed.

  5. Isotherms for Water Adsorption on Molecular Sieve 3A: Influence of Cation Composition

    DOE PAGESBeta

    Lin, Ronghong; Ladshaw, Austin; Nan, Yue; Liu, Jiuxu; Yiacoumi, Sotira; Tsouris, Costas; DePaoli, David W.; Tavlarides, Lawrence L.

    2015-06-16

    This study is part of our continuing efforts to address engineering issues related to the removal of tritiated water from off-gases produced in used nuclear fuel reprocessing facilities. In the current study, adsorption equilibrium of water on molecular sieve 3A beads was investigated. Adsorption isotherms for water on the UOP molecular sieve 3A were measured by a continuous-flow adsorption system at 298, 313, 333, and 353 K. Experimental data collected were analyzed by the Generalized Statistical Thermodynamic Adsorption (GSTA) isotherm model. The K+/Na+ molar ratio of this particular type of molecular sieve 3A was ~4:6. Our results showed that themore » GSTA isotherm model worked very well to describe the equilibrium behavior of water adsorption on molecular sieve 3A. The optimum number of parameters for the current experimental data was determined to be a set of four equilibrium parameters. This result suggests that the adsorbent crystals contain four energetically distinct adsorption sites. In addition, it was found that water adsorption on molecular sieve 3A follows a three-stage adsorption process. This three-stage adsorption process confirmed different water adsorption sites in molecular sieve crystals. In addition, the second adsorption stage is significantly affected by the K+/Na+ molar ratio. In this stage, the equilibrium adsorption capacity at a given water vapor pressure increases as the K+/Na+ molar ratio increases.« less

  6. Isotherms for Water Adsorption on Molecular Sieve 3A: Influence of Cation Composition

    SciTech Connect

    Lin, Ronghong; Ladshaw, Austin; Nan, Yue; Liu, Jiuxu; Yiacoumi, Sotira; Tsouris, Costas; DePaoli, David W.; Tavlarides, Lawrence L.

    2015-06-16

    This study is part of our continuing efforts to address engineering issues related to the removal of tritiated water from off-gases produced in used nuclear fuel reprocessing facilities. In the current study, adsorption equilibrium of water on molecular sieve 3A beads was investigated. Adsorption isotherms for water on the UOP molecular sieve 3A were measured by a continuous-flow adsorption system at 298, 313, 333, and 353 K. Experimental data collected were analyzed by the Generalized Statistical Thermodynamic Adsorption (GSTA) isotherm model. The K+/Na+ molar ratio of this particular type of molecular sieve 3A was ~4:6. Our results showed that the GSTA isotherm model worked very well to describe the equilibrium behavior of water adsorption on molecular sieve 3A. The optimum number of parameters for the current experimental data was determined to be a set of four equilibrium parameters. This result suggests that the adsorbent crystals contain four energetically distinct adsorption sites. In addition, it was found that water adsorption on molecular sieve 3A follows a three-stage adsorption process. This three-stage adsorption process confirmed different water adsorption sites in molecular sieve crystals. In addition, the second adsorption stage is significantly affected by the K+/Na+ molar ratio. In this stage, the equilibrium adsorption capacity at a given water vapor pressure increases as the K+/Na+ molar ratio increases.

  7. Comparison of radioactive transmission and mechanical properties of Portland cement and a modified cement with trommel sieve waste

    SciTech Connect

    Boncukcuoglu, Recep . E-mail: rboncuk@yahoo.com; Icelli, Orhan; Erzeneoglu, Salih; Muhtar Kocakerim, M.

    2005-06-01

    In this study, it was aimed to stabilize trommel sieve waste (TSW) occurring during manufacture of borax from tincal. The effects of TSW added on the mechanical properties and radioactive transmission of modified cement prepared by adding TSW to clinker was investigated. The properties which TSW as additive caused the cement to gain were tested and compared with normal Portland cement. Measurements have been made to determine variation of mass attenuation coefficients of TSW and cement by using an extremely narrow-collimated-beam transmission method in the energy range 15.746-40.930 keV with X-ray transmission method. The characteristic K{alpha} and K{beta} X-rays of the different elements (Zr, Mo, Ag, In, Sb, Ba and Pr) passed through TSW and cement were detected with a high-resolution Si(Li) detector. Results are presented and discussed in this paper.

  8. Modification of molecular sieves MCM-41 and SBA-15 with covalently grafted pyromellitimide and 1,4,5,8-naphthalenediimide.

    PubMed

    Trindade, Fabiane Jesus; Rey, José Fernando Queiruga; Brochsztain, Sergio

    2012-02-15

    This article describes the covalent grafting of pyromellitimide and 1,4,5,8-naphthalenediimide, which are organic semiconductors with very interesting electro-optical properties, onto the walls of mesoporous molecular sieves. The mesoporous materials MCM-41 and SBA-15 were first treated with 3-aminopropyltriethoxysilane, generating materials with a surface coverage of primary amino groups. These materials were further reacted with either pyromellitic dianhydride or 1,4,5,8-naphthalenetetracarboxylic dianhydride, generating surface-bound pyromellitimide or 1,4,5,8-naphthalenediimide, respectively. The success of the modification reactions was confirmed by elemental and thermogravimetric analyses, X-ray diffraction patterns and infrared, reflectance and fluorescence spectroscopies. The results indicated that the mesoporous structure of the new materials was preserved after the modification reactions and that the chromophores were included inside the mesoporous channels with stacked aromatic rings. PMID:22153336

  9. Computational identification of 69 retroposons in Arabidopsis.

    PubMed

    Zhang, Yujun; Wu, Yongrui; Liu, Yilei; Han, Bin

    2005-06-01

    Retroposition is a shot-gun strategy of the genome to achieve evolutionary diversities by mixing and matching coding sequences with novel regulatory elements. We have identified 69 retroposons in the Arabidopsis (Arabidopsis thaliana) genome by a computational approach. Most of them were derivatives of mature mRNAs, and 20 genes contained relics of the reverse transcription process, such as truncations, deletions, and extra sequence additions. Of them, 22 are processed pseudogenes, and 52 genes are likely to be actively transcribed, especially in tissues from apical meristems (roots and flowers). Functional compositions of these retroposon parental genes imply that not the mRNA itself but its expression in gamete cells defines a suitable template for retroposition. The presence/absence patterns of retroposons can be used as cladistic markers for biogeographic research. Effects of human and the Mediterranean Pleistocene refugia in Arabidopsis biogeographic distributions were revealed based on two recent retroposons (At1g61410 and At5g52090). An evolutionary rate of new gene creation by retroposition was calculated as 0.6 genes per million years. Retroposons can also be used as molecular fossils of the parental gene expressions in ancient time. Extensions of 3' untranslated regions for those expressed parental genes are revealed as a possible trend of plant transcriptome evolution. In addition, we reported the first plant functional chimeric gene that adapts to intercompartmental transport by capturing two additional exons after retroposition. PMID:15923328

  10. Titanium modified {beta} and MCM-41 molecular sieves K

    SciTech Connect

    Reddy, K.M.; Reddy, J.S.; Dicko, A.

    1995-12-01

    Ti modified large Pore {beta} zeolite and mesoporous MCM-41 molecular sieve were synthesized using hydrothermal procedures. Several other Ti-{beta} zeolites were prepared by treating a {beta} zeolite (Si/Al = 100) with ammonium titanyl oxalate solution. All samples were characterized by atomic absorption, XRD, IR, UV-Vis, Raman and XPS. The presence of tetrahedral Ti was evidenced particularly by the presence of a 212 nm absorption band in the UV-Vis spectra and a Ti(2p{sub 3/2}) binding energy of 459.5 eV. All samples were tested for the hydroxylation of hexane, benzene and phenol, and also for the epoxidation of 1-hexene. High catalytic activity was found only for the epoxidation reaction. Previous reports showed that, contrary to TS-1 and TS-2 zeolites, Ti modified {beta} (M.E. Davis et al. Prepr. Div. Petrol. Chem. 1993, p.769) and ZSM-48 (A. Sayari et at Catal. Lett. 23 (1994) 175) zeolites are poor hydroxylation catalysts in the presence of H{sub 2}O{sub 2}. In a paper devoted to Ti-MCM-41, Corma et al. (Chem. Commun. 1994, 147) reported only on the 1-hexene epoxidation. However, in the presence of excess H{sub 2}O{sub 2}, Pinnavaia et al. (Nature 368 (1994) 321) found that Ti-MCM-41 exhibits significant catalytic activity in the hydroxylation of benzene and substituted phenol. This behavior may indicate that in TS-1 and TS-2, Ti has a different local environment.

  11. Trichome morphogenesis in Arabidopsis.

    PubMed Central

    Schwab, B; Folkers, U; Ilgenfritz, H; Hülskamp, M

    2000-01-01

    Trichomes (plant hairs) in Arabidopsis thaliana are large non-secreting epidermal cells with a characteristic three-dimensional architecture. Because trichomes are easily accessible to a combination of genetic, cell biological and molecular methods they have become an ideal model system to study various aspects of plant cell morphogenesis. In this review we will summarize recent progress in the understanding of trichome morphogenesis. PMID:11128981

  12. Gains and Losses of Cis-regulatory Elements Led to Divergence of the Arabidopsis APETALA1 and CAULIFLOWER Duplicate Genes in the Time, Space, and Level of Expression and Regulation of One Paralog by the Other1[OPEN

    PubMed Central

    Wang, Bin

    2016-01-01

    How genes change their expression patterns over time is still poorly understood. Here, by conducting expression, functional, bioinformatic, and evolutionary analyses, we demonstrate that the differences between the Arabidopsis (Arabidopsis thaliana) APETALA1 (AP1) and CAULIFLOWER (CAL) duplicate genes in the time, space, and level of expression were determined by the presence or absence of functionally important transcription factor-binding sites (TFBSs) in regulatory regions. In particular, a CArG box, which is the autoregulatory site of AP1 that can also be bound by the CAL protein, is a key determinant of the expression differences. Because of the CArG box, AP1 is both autoregulated and cross-regulated (by AP1 and CAL, respectively), and its relatively high-level expression is maintained till to the late stages of sepal and petal development. The observation that the CArG box was gained recently further suggests that the autoregulation and cross-regulation of AP1, as well as its function in sepal and petal development, are derived features. By comparing the evolutionary histories of this and other TFBSs, we further indicate that the divergence of AP1 and CAL in regulatory regions has been markedly asymmetric and can be divided into several stages. Specifically, shortly after duplication, when AP1 happened to be the paralog that maintained the function of the ancestral gene, CAL experienced certain degrees of degenerate evolution, in which several functionally important TFBSs were lost. Later, when functional divergence allowed the survival of both paralogs, CAL remained largely unchanged in expression, whereas the functions of AP1 were gradually reinforced by gains of the CArG box and other TFBSs. PMID:27208240

  13. Gains and Losses of Cis-regulatory Elements Led to Divergence of the Arabidopsis APETALA1 and CAULIFLOWER Duplicate Genes in the Time, Space, and Level of Expression and Regulation of One Paralog by the Other.

    PubMed

    Ye, Lingling; Wang, Bin; Zhang, Wengen; Shan, Hongyan; Kong, Hongzhi

    2016-06-01

    How genes change their expression patterns over time is still poorly understood. Here, by conducting expression, functional, bioinformatic, and evolutionary analyses, we demonstrate that the differences between the Arabidopsis (Arabidopsis thaliana) APETALA1 (AP1) and CAULIFLOWER (CAL) duplicate genes in the time, space, and level of expression were determined by the presence or absence of functionally important transcription factor-binding sites (TFBSs) in regulatory regions. In particular, a CArG box, which is the autoregulatory site of AP1 that can also be bound by the CAL protein, is a key determinant of the expression differences. Because of the CArG box, AP1 is both autoregulated and cross-regulated (by AP1 and CAL, respectively), and its relatively high-level expression is maintained till to the late stages of sepal and petal development. The observation that the CArG box was gained recently further suggests that the autoregulation and cross-regulation of AP1, as well as its function in sepal and petal development, are derived features. By comparing the evolutionary histories of this and other TFBSs, we further indicate that the divergence of AP1 and CAL in regulatory regions has been markedly asymmetric and can be divided into several stages. Specifically, shortly after duplication, when AP1 happened to be the paralog that maintained the function of the ancestral gene, CAL experienced certain degrees of degenerate evolution, in which several functionally important TFBSs were lost. Later, when functional divergence allowed the survival of both paralogs, CAL remained largely unchanged in expression, whereas the functions of AP1 were gradually reinforced by gains of the CArG box and other TFBSs. PMID:27208240

  14. Characterization of Se-loaded molecular sieves A, X, Y, AlPO-5, and mordenite

    SciTech Connect

    Parise, J.B.; MacDougall, J.E.; Herron, N.; Farlee, R.; Sleight, A.W.; Ying Wang; Bein, T.; Moller, K.; Moroney, L.M.

    1988-01-27

    Selenium has been successfully loaded into molecular sieves A, X, Y, AlPO-5, and mordenite, and the products were characterized by using EXAFS, solid-state NMR, and diffuse-reflectance techniques. This study reveals selenium is predominantly of the trigonal (helical chains) form in all but the A sample, where only the Se/sub 8/-crown ring form is found. A mixture of allotropes and helical chains occupy the large 3D-pore and channel systems of molecular sieves X and Y; however, a single, probably fixed-pitch helical-chain allotrope occupies the more constrained 12-membered-ring channels found in mordenite and AlPO-5. The high degree of order in these last two sieves is reflected in a strong second-shell feature in the EXAFS spectra. 22 refs., 12 figs., 3 tabs.

  15. A systematic investigation of the preparation and properties of composite carbon molecular sieves containing inorganic oxides

    NASA Technical Reports Server (NTRS)

    Foley, Henry C.

    1990-01-01

    The objective of this research is to define the methodology for the preparation and characterization of new carbon-based molecular sieves with composite structures. Carbon molecular sieves have found increasing application in the field of separation and purification of gases. These materials are relatively easy to prepare and their surfaces can be modified to some extent. It is expected that by combining inorganic oxides with the carbonaceous structure one can begin to design composite materials with a wider range of possible chemical and physical properties. In this way, the IOM-CMS materials may confer distinct advantages over pure carbon molecular sieves, not just for separation, but also for catalysis. The most recent results in the design and characterization of these IOM-CMS materials are reviewed and summarized. Directions for further research are also presented.

  16. Laser Diffraction Techniques Replace Sieving for Lunar Soil Particle Size Distribution Data

    NASA Technical Reports Server (NTRS)

    Cooper, Bonnie L.; Gonzalez, C. P.; McKay, D. S.; Fruland, R. L.

    2012-01-01

    Sieving was used extensively until 1999 to determine the particle size distribution of lunar samples. This method is time-consuming, and requires more than a gram of material in order to obtain a result in which one may have confidence. This is demonstrated by the difference in geometric mean and median for samples measured by [1], in which a 14-gram sample produced a geometric mean of approx.52 micrometers, whereas two other samples of 1.5 grams resulted in gave means of approx.63 and approx.69 micrometers. Sample allocations for sieving are typically much smaller than a gram, and many of the sample allocations received by our lab are 0.5 to 0.25 grams in mass. Basu [2] has described how the finest fraction of the soil is easily lost in the sieving process, and this effect is compounded when sample sizes are small.

  17. Update on N2O4 Molecular Sieving with 3A Material at NASA/KSC

    NASA Technical Reports Server (NTRS)

    Davis, Chuck; Dorn, Claudia

    2000-01-01

    During its operational life, the Shuttle Program has experienced numerous failures in the Nitrogen Tetroxide (N2O4) portion of Reaction Control System (RCS), many of which were attributed to iron-nitrate contamination. Since the mid-1980's, N2O4 has been processed through a molecular sieve at the N2O4 manufacturer's facility which results in an iron content typically less than 0.5 parts-per-million-by-weight (ppmw). In February 1995, a Tiger Team was formed to attempt to resolve the iron nitrate problem. Eighteen specific actions were recommended as possibly reducing system failures. Those recommended actions include additional N2O4 molecular sieving at the Shuttle launch site. Testing at NASA White Sands Test Facility (WSTF) determined an alternative molecular sieve material could also reduce the water-equivalent content (free water and HNO3) and thereby further reduce the natural production of iron nitrate in N2O4 while stored in iron-alloy storage tanks. Since April '96, NASA Kennedy Space Center (KSC) has been processing N2O4 through the alternative molecular sieve material prior to delivery to Shuttle launch pad N2O4 storage tanks. A new, much larger capacity molecular sieve unit has also been used. This paper will evaluate the effectiveness of N2O4 molecular sieving on a large-scale basis and attempt to determine if the resultant lower-iron and lower-water content N2O4 maintains this new purity level in pad storage tanks and shuttle flight systems.

  18. An Egg Apparatus-Specific Enhancer of Arabidopsis, Identified by Enhancer Detection1

    PubMed Central

    Yang, Wei; Jefferson, Richard A.; Huttner, Eric; Moore, James M.; Gagliano, Wendy B.; Grossniklaus, Ueli

    2005-01-01

    Despite a central role in angiosperm reproduction, few gametophyte-specific genes and promoters have been isolated, particularly for the inaccessible female gametophyte (embryo sac). Using the Ds-based enhancer-detector line ET253, we have cloned an egg apparatus-specific enhancer (EASE) from Arabidopsis (Arabidopsis thaliana). The genomic region flanking the Ds insertion site was further analyzed by examining its capability to control gusA and GFP reporter gene expression in the embryo sac in a transgenic context. Through analysis of a 5′ and 3′ deletion series in transgenic Arabidopsis, the sequence responsible for egg apparatus-specific expression was delineated to 77 bp. Our data showed that this enhancer is unique in the Arabidopsis genome, is conserved among different accessions, and shows an unusual pattern of sequence variation. This EASE works independently of position and orientation in Arabidopsis but is probably not associated with any nearby gene, suggesting either that it acts over a large distance or that a cryptic element was detected. Embryo-specific ablation in Arabidopsis was achieved by transactivation of a diphtheria toxin gene under the control of the EASE. The potential application of the EASE element and similar control elements as part of an open-source biotechnology toolkit for apomixis is discussed. PMID:16258010

  19. Development of design information for molecular-sieve type regenerative CO2-removal systems

    NASA Technical Reports Server (NTRS)

    Wright, R. M.; Ruder, J. M.; Dunn, V. B.; Hwang, K. C.

    1973-01-01

    Experimental and analytic studies were conducted with molecular sieve sorbents to provide basic design information, and to develop a system design technique for regenerable CO2-removal systems for manned spacecraft. Single sorbate equilibrium data were obtained over a wide range of conditions for CO2, water, nitrogen, and oxygen on several molecular sieve and silica gel sorbents. The coadsorption of CO2 with water preloads, and with oxygen and nitrogen was experimentally evaluated. Mass-transfer, and some limited heat-transfer performance evaluations were accomplished under representative operating conditions, including the coadsorption of CO2 and water. CO2-removal system performance prediction capability was derived.

  20. Overtone and combination tone bands in the DRIFT spectra of molecular sieves

    NASA Astrophysics Data System (ADS)

    Peuker, Ch.; Splett, Ch.

    1993-03-01

    The DRIFT spectra of molecular sieves of type A, X, ZSM-5 and SAPO are measured. It is demonstrated that in some cases the overtone and combination tone bands of the lattice vibrations may be used for characterizing the structure of molecular sieves. For instance crystal phase transition due to thermal or hydrothermal treatment, can easily be studied in the region between 2500 and 1500 cm -1. In general the variations in the spectra of the samples due to structural distortion are less significant in the overtone and combination tone bands than in fundamental ones.

  1. MassSieve: panning MS/MS peptide data for proteins.

    PubMed

    Slotta, Douglas J; McFarland, Melinda A; Markey, Sanford P

    2010-08-01

    We present MassSieve, a Java-based platform for visualization and parsimony analysis of single and comparative LC-MS/MS database search engine results. The success of mass spectrometric peptide sequence assignment algorithms has led to the need for a tool to merge and evaluate the increasing data set sizes that result from LC-MS/MS-based shotgun proteomic experiments. MassSieve supports reports from multiple search engines with differing search characteristics, which can increase peptide sequence coverage and/or identify conflicting or ambiguous spectral assignments. PMID:20564260

  2. Chronic recording of regenerating VIIIth nerve axons with a sieve electrode

    NASA Technical Reports Server (NTRS)

    Mensinger, A. F.; Anderson, D. J.; Buchko, C. J.; Johnson, M. A.; Martin, D. C.; Tresco, P. A.; Silver, R. B.; Highstein, S. M.

    2000-01-01

    A micromachined silicon substrate sieve electrode was implanted within transected toadfish (Opsanus tau) otolith nerves. High fidelity, single unit neural activity was recorded from seven alert and unrestrained fish 30 to 60 days after implantation. Fibrous coatings of genetically engineered bioactive protein polymers and nerve guide tubes increased the number of axons regenerating through the electrode pores when compared with controls. Sieve electrodes have potential as permanent interfaces to the nervous system and to bridge missing connections between severed or damaged nerves and muscles. Recorded impulses might also be amplified and used to control prosthetic devices.

  3. Application of 3A molecular sieve layer in dye-sensitized solar cells

    SciTech Connect

    Yan, Yuan; Wang, Jinzhong E-mail: qingjiang.yu@hit.edu.cn; Yu, Qingjiang E-mail: qingjiang.yu@hit.edu.cn; Huang, Yuewu; Chang, Quanhong; Hao, Chunlei; Jiao, Shujie; Gao, Shiyong; Li, Hongtao; Wang, Dongbo

    2014-08-25

    3A molecular sieve layer was used as dehydration and electronic-insulation layer on the TiO{sub 2} electrode of dye-sensitized solar cells. This layer diminished the effect of water in electrolyte efficiently and enhanced the performance of cells. The conversion efficiency increased from 9.58% to 10.2%. The good moisture resistance of cells was attributed to the three-dimensional interconnecting structure of 3A molecular sieve with strong adsorption of water molecule. While the performance enhancement benefited from the suppression of the charge recombination of electronic-insulation layer and scattering effect of large particles.

  4. Microfluidic sieve using intertwined, free-standing carbon nanotube mesh as active medium

    DOEpatents

    Bakajin, Olgica; Noy, Aleksandr

    2007-11-06

    A microfluidic sieve having a substrate with a microfluidic channel, and a carbon nanotube mesh. The carbon nanotube mesh is formed from a plurality of intertwined free-standing carbon nanotubes which are fixedly attached within the channel for separating, concentrating, and/or filtering molecules flowed through the channel. In one embodiment, the microfluidic sieve is fabricated by providing a substrate having a microfluidic channel, and growing the intertwined free-standing carbon nanotubes from within the channel to produce the carbon nanotube mesh attached within the channel.

  5. CTR Fuel recovery system using regeneration of a molecular sieve drying bed

    DOEpatents

    Folkers, Charles L.

    1981-01-01

    A primary molecular sieve drying bed is regenerated by circulating a hot inert gas through the heated primary bed to desorb water held on the bed. The inert gas plus water vapor is then cooled and passed through an auxiliary molecular sieve bed which adsorbs the water originally desorbed from the primary bed. The main advantage of the regeneration technique is that the partial pressure of water can be reduced to the 10.sup.-9 atm. range. This is significant in certain CTR applications where tritiated water (T.sub.2 O, HTO) must be collected and kept at very low partial pressure.

  6. Bidirectional Translocation of Sugars in Sieve Tubes of Squash Plants 1

    PubMed Central

    Trip, P.; Gorham, P. R.

    1968-01-01

    Two streams of sugars moving in opposite directions in the petiole of a half-grown leaf were demonstrated by feeding tritiated glucose to a fully grown leaf of a squash plant (Cucurbita melopepo Bailey) and 14CO2 to the half-grown one. Autoradiographic evidence indicates that the movement of both streams occurred within the same sieve tubes. The data do not fit the mass flow theory of translocation which requires unidirectional flow of sugar solution in the lumen of the sieve tube. Images PMID:16656856

  7. Probing the structure of metal-substituted molecular sieves by solid-state NMR

    SciTech Connect

    Labouriau, A.; Crawford, S.N.; Ott, K.; Earl, W.L.

    1998-08-01

    Paramagnetic metal ions exert large influences on the NMR spectra of neighboring nuclei. The authors are using these effects to probe metal sites in zeolites and AlPO{sub 4} molecular sieves. In particular, they are studying [Co]-AlPO{sub 4}-5 because similar cobalt substituted AlPO{sub 4} sieves are reported in the literature. They have extended that work to probe the titanium zeolite TS-1 by comparing spectra of normal TS-1 to samples where the titanium has been reduced to the paramagnetic Ti{sup 3+}. This promises to be a useful technique for determining framework substitution in many zeolite systems.

  8. Arabidopsis peroxisome proteomics

    PubMed Central

    Bussell, John D.; Behrens, Christof; Ecke, Wiebke; Eubel, Holger

    2013-01-01

    The analytical depth of investigation of the peroxisomal proteome of the model plant Arabidopsis thaliana has not yet reached that of other major cellular organelles such as chloroplasts or mitochondria. This is primarily due to the difficulties associated with isolating and obtaining purified samples of peroxisomes from Arabidopsis. So far only a handful of research groups have been successful in obtaining such fractions. To make things worse, enriched peroxisome fractions frequently suffer from significant organellar contamination, lowering confidence in localization assignment of the identified proteins. As with other cellular compartments, identification of peroxisomal proteins forms the basis for investigations of the dynamics of the peroxisomal proteome. It is therefore not surprising that, in terms of functional analyses by proteomic means, peroxisomes are lagging considerably behind chloroplasts or mitochondria. Alternative strategies are needed to overcome the obstacle of hard-to-obtain organellar fractions. This will help to close the knowledge gap between peroxisomes and other organelles and provide a full picture of the physiological pathways shared between organelles. In this review, we briefly summarize the status quo and discuss some of the methodological alternatives to classic organelle proteomic approaches. PMID:23630535

  9. Habitat Temperature and Precipitation of Arabidopsis thaliana Ecotypes Determine the Response of Foliar Vasculature, Photosynthesis, and Transpiration to Growth Temperature

    PubMed Central

    Adams, William W.; Stewart, Jared J.; Cohu, Christopher M.; Muller, Onno; Demmig-Adams, Barbara

    2016-01-01

    Acclimatory adjustments of foliar vascular architecture, photosynthetic capacity, and transpiration rate in Arabidopsis thaliana ecotypes (Italian, Polish [Col-0], Swedish) were characterized in the context of habitat of origin. Temperatures of the habitat of origin decreased linearly with increasing habitat latitude, but habitat precipitation was greatest in Italy, lowest in Poland, and intermediate in Sweden. Plants of the three ecotypes raised under three different growth temperature regimes (low, moderate, and high) exhibited highest photosynthetic capacities, greatest leaf thickness, highest chlorophyll a/b ratio and levels of β-carotene, and greatest levels of wall ingrowths in phloem transfer cells, and, in the Col-0 and Swedish ecotypes, of phloem per minor vein in plants grown at the low temperature. In contrast, vein density and minor vein tracheary to sieve element ratio increased with increasing growth temperature – most strongly in Col-0 and least strongly in the Italian ecotype – and transpirational water loss correlated with vein density and number of tracheary elements per minor vein. Plotting of these vascular features as functions of climatic conditions in the habitat of origin suggested that temperatures during the evolutionary history of the ecotypes determined acclimatory responses of the foliar phloem and photosynthesis to temperature in this winter annual that upregulates photosynthesis in response to lower temperature, whereas the precipitation experienced during the evolutionary history of the ecotypes determined adjustment of foliar vein density, xylem, and transpiration to temperature. In particular, whereas photosynthetic capacity, leaf thickness, and foliar minor vein phloem features increased linearly with increasing latitude and decreasing temperature of the habitats of origin in response to experimental growth at low temperature, transpiration rate, foliar vein density, and minor vein tracheary element numbers and cross

  10. Habitat Temperature and Precipitation of Arabidopsis thaliana Ecotypes Determine the Response of Foliar Vasculature, Photosynthesis, and Transpiration to Growth Temperature.

    PubMed

    Adams, William W; Stewart, Jared J; Cohu, Christopher M; Muller, Onno; Demmig-Adams, Barbara

    2016-01-01

    Acclimatory adjustments of foliar vascular architecture, photosynthetic capacity, and transpiration rate in Arabidopsis thaliana ecotypes (Italian, Polish [Col-0], Swedish) were characterized in the context of habitat of origin. Temperatures of the habitat of origin decreased linearly with increasing habitat latitude, but habitat precipitation was greatest in Italy, lowest in Poland, and intermediate in Sweden. Plants of the three ecotypes raised under three different growth temperature regimes (low, moderate, and high) exhibited highest photosynthetic capacities, greatest leaf thickness, highest chlorophyll a/b ratio and levels of β-carotene, and greatest levels of wall ingrowths in phloem transfer cells, and, in the Col-0 and Swedish ecotypes, of phloem per minor vein in plants grown at the low temperature. In contrast, vein density and minor vein tracheary to sieve element ratio increased with increasing growth temperature - most strongly in Col-0 and least strongly in the Italian ecotype - and transpirational water loss correlated with vein density and number of tracheary elements per minor vein. Plotting of these vascular features as functions of climatic conditions in the habitat of origin suggested that temperatures during the evolutionary history of the ecotypes determined acclimatory responses of the foliar phloem and photosynthesis to temperature in this winter annual that upregulates photosynthesis in response to lower temperature, whereas the precipitation experienced during the evolutionary history of the ecotypes determined adjustment of foliar vein density, xylem, and transpiration to temperature. In particular, whereas photosynthetic capacity, leaf thickness, and foliar minor vein phloem features increased linearly with increasing latitude and decreasing temperature of the habitats of origin in response to experimental growth at low temperature, transpiration rate, foliar vein density, and minor vein tracheary element numbers and cross

  11. Transgenic Arabidopsis Gene Expression System

    NASA Technical Reports Server (NTRS)

    Ferl, Robert; Paul, Anna-Lisa

    2009-01-01

    The Transgenic Arabidopsis Gene Expression System (TAGES) investigation is one in a pair of investigations that use the Advanced Biological Research System (ABRS) facility. TAGES uses Arabidopsis thaliana, thale cress, with sensor promoter-reporter gene constructs that render the plants as biomonitors (an organism used to determine the quality of the surrounding environment) of their environment using real-time nondestructive Green Fluorescent Protein (GFP) imagery and traditional postflight analyses.

  12. Molecular sieve generation of aviator's oxygen: Performance of a prototype system under simulated flight conditions.

    PubMed

    Miller, R L; Ikels, K G; Lamb, M J; Boscola, E J; Ferguson, R H

    1980-07-01

    The molecular sieve method of generating an enriched-oxygen breathing gas is one of several candidate onboard oxygen generation (OBOG) systems under joint Army-Navy-Air Force development for application in tactical aircraft. The performance of a nominal two-man-capacity molecular sieve oxygen generation system was characterized under simulated flight conditions. Data are given on the composition of the molecular sieve-generated breathing gas (oxygen, nitrogen, carbon dioxide, and argon) as a function of inlet air pressure, altitude, breathing gas flow rate, and ambient temperature. The maximum oxygen concentration observed was 95%, with the balance argon. At low demand flow rates and certain conditions of pressure and altitude, the argon enrichment factor exceeded that of oxygen giving a maximum argon concentration of 6.6% with the balance oxygen. The structural integrity of the unit was verified by vibration and centrifuge testing. The performance of the molecular sieve unit is discussed in the context of aircraft operating envelopes using both diluter-demand and 100% delivery subsystems. PMID:6774707

  13. Experiments for the Undergraduate Laboratory that Illustrate the Size-Exclusion Properties of Zeolite Molecular Sieves

    ERIC Educational Resources Information Center

    Cooke, Jason; Henderson, Eric J.

    2009-01-01

    Experiments are presented that demonstrate the size-exclusion properties of zeolites and reveal the reason for naming zeolites "molecular sieves". If an IR spectrometer is available, the adsorption or exclusion of alcohols of varying sizes from dichloromethane or chloroform solutions can be readily demonstrated by monitoring changes in the…

  14. EVALUATION OF MOLECULAR SIEVES FOR SAMPLING N0X EMISSIONS AT ELECTRIC UTILITY PLANTS

    EPA Science Inventory

    A field study was conducted to evaluate the use of molecular sieves for collection of NOx (NO + NO2) emissions from utility boilers. It was found that NOx could be collected efficiently (99%) at sample flow rates of 1 L/min over 20- to 40-min sampling periods at the NOx levels en...

  15. Drying R-407C and R-410A refrigerant blends with molecular sieve desiccants

    SciTech Connect

    Cohen, A.P.; Tucker, D.M.

    1998-10-01

    The hydrofluorocarbon (HFC) R-32 (CF{sub 2}H{sub 2}) is a component of refrigerant blends in the 407 and 410 series being tested and commercialized for use as replacements for R-502 and the hydrochlorofluorocarbon (HCFC) R-22. The molecular sieve desiccants used with chlorofluorocarbon (CFC) and HCFC mineral oil systems in the past have achieved high water capacity by excluding the refrigerant and adsorbing only the water. Unfortunately, R-32 is adsorbed on commercial type 3A molecular sieve desiccant products. The result of this adsorption is a loss of water capacity when drying R-32 compared to drying R-22 or R-502 and a reduced level of chemical compatibility of the desiccant with the refrigerant. Some compressor manufacturers are seeking a water concentration as low as 10 mg/kg (ppm[wt]) in the circulating refrigerant of polyolester-lubricated refrigerating equipment using these HFC blends. This paper compares unmodified commercial type 3A molecular sieve desiccants with a recently developed, modified 3A molecular sieve that excludes R-32. The modified 3A has better chemical compatibility with R-32 and high water capacity in liquid R-407C and R-410A. The drying rates of the two desiccants in R-407C and R-410A are similar. Data and test methods are reported on refrigerant adsorption, water capacity, drying rate, and chemical compatibility.

  16. Effect of barley roller milling on fractionation of flour using sieving and air classification

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Separation of hulls prior to fermentation of barley flour could increase fuel ethanol productivity and the hulls would be an additional coproduct. In a recent study, it was found that the Elusieve process, a combination of sieving and elutriation (air classification) was effective in separating hul...

  17. Separation of fiber from distillers dried grains (DDG) using sieving and elutriation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We recently developed a new process that combined sieving and elutriation (upward air flow) to separate fiber from distillers dried grains and solubles (DDGS). The current study was designed to evaluate the elusieve process for the first time using distillers dried grains (DDG) instead of DDGS. Be...

  18. A reconstruction strategy to synthesize mesoporous SAPO molecular sieve single crystals with high MTO catalytic activity.

    PubMed

    Wang, Chan; Yang, Miao; Li, Mingrun; Xu, Shutao; Yang, Yue; Tian, Peng; Liu, Zhongmin

    2016-05-11

    Mesoporous SAPO-34 single crystals with tunable porosity and Si content have been fast synthesized within 4 hours by a reconstruction strategy, which show excellent hydrothermal stability and MTO catalytic activity. This new strategy is further proven to be applicable to prepare other mesoporous SAPO molecular sieve single crystals. PMID:27101359

  19. Importance of neutralization sieve analyses when seeking correlates of HIV-1 vaccine efficacy

    PubMed Central

    Montefiori, David C

    2014-01-01

    This commentary describes a rationale for the use of breakthrough viruses from clinical trial participants to assess neutralizing antibodies as a correlate of HIV-1 vaccine efficacy. The rationale is based on principles of a genetic sieve analysis, where the 2 analyses may be cooperative for delineating neutralizing antibodies as a mechanistic correlate of protection. PMID:25424964

  20. Low Temperature VOC Combustion Over Manganese, Cobalt and Zinc AlPO{sub 4} Molecular Sieves

    SciTech Connect

    Szostak, R.

    1997-03-31

    The objective of this project is to prepare manganese, cobalt and zinc containing AlPO{sub 4} molecular sieves and evaluate their catalytic activities for the removal of low levels of volatile organic compounds (VOCs) from gas streams. This report highlights our research activities for period October 1,1996 to March 31, 1997.

  1. Alternative sieving method for extraction of light filth from cheeses: collaborative study.

    PubMed

    Nakashima, M J

    1994-01-01

    A collaborative study was conducted on an alternative sieving method for the extraction of light filth from cheeses. The alternative method was developed that is applicable to broad variety of cheeses. A 225 g test portion is dispersed in a solution of 5.7% HCl, Igepal CO-730, and Igepal DM-710. Digested cheese is wet-sieved on a No. 230 sieve. The residue is treated with Tergitol Anionic 4, transferred to 1% sodium lauryl sulfate solution, heated, and maintained at 65 degrees-75 degrees C for 10 min. The residue is washed with these 2 surfactants a maximum of 4 times until it is reduced to an amount that is filterable. The residue is filtered and the filter papers are examined microscopically at a magnification of ca 30x. Average recoveries by 9 collaborators for 3 spike levels of rat hairs (5, 10, and 15) were 80, 68, and 81%, respectively; for insect fragments (5, 15, and 30) recoveries were 97, 90, and 92%, respectively. The alternative sieving method for extraction of light filth from cheeses has been adopted first action by AOAC INTERNATIONAL. PMID:7950417

  2. An Arabidopsis callose synthase.

    PubMed

    Ostergaard, Lars; Petersen, Morten; Mattsson, Ole; Mundy, John

    2002-08-01

    Beta-1,3-glucan polymers are major structural components of fungal cell walls, while cellulosic beta-1,4-glucan is the predominant polysaccharide in plant cell walls. Plant beta-1,3-glucan, called callose, is produced in pollen and in response to pathogen attack and wounding, but it has been unclear whether callose synthases can also produce cellulose and whether plant cellulose synthases may also produce beta-1,3-glucans. We describe here an Arabidopsis gene, AtGsl5, encoding a plasma membrane-localized protein homologous to yeast beta-1,3-glucan synthase whose expression partially complements a yeast beta-1,3-glucan synthase mutant. AtGsl5 is developmentally expressed at highest levels in flowers, consistent with flowers having high beta-1,3-glucan synthase activities for deposition of callose in pollen. A role for AtGsl5 in callose synthesis is also indicated by AtGsl5 expression in the Arabidopsis mpk4 mutant which exhibits systemic acquired resistance (SAR), elevated beta-1,3-glucan synthase activity, and increased callose levels. In addition, AtGsl5 is a likely target of salicylic acid (SA)-dependent SAR, since AtGsl5 mRNA accumulation is induced by SA in wild-type plants, while expression of the nahG salicylate hydroxylase reduces AtGsl5 mRNA levels in the mpk4 mutant. These results indicate that AtGsl5 is likely involved in callose synthesis in flowering tissues and in the mpk4 mutant. PMID:12081364

  3. Epigenetic Natural Variation in Arabidopsis thaliana

    PubMed Central

    Jiang, Hongmei; Carrasquillo, Robert; Rabinowicz, Pablo D; Dedhia, Neilay; McCombie, W. Richard; Agier, Nicolas; Bulski, Agnès; Colot, Vincent; Doerge, R.W; Martienssen, Robert A

    2007-01-01

    Cytosine methylation of repetitive sequences is widespread in plant genomes, occurring in both symmetric (CpG and CpNpG) as well as asymmetric sequence contexts. We used the methylation-dependent restriction enzyme McrBC to profile methylated DNA using tiling microarrays of Arabidopsis Chromosome 4 in two distinct ecotypes, Columbia and Landsberg erecta. We also used comparative genome hybridization to profile copy number polymorphisms. Repeated sequences and transposable elements (TEs), especially long terminal repeat retrotransposons, are densely methylated, but one third of genes also have low but detectable methylation in their transcribed regions. While TEs are almost always methylated, genic methylation is highly polymorphic, with half of all methylated genes being methylated in only one of the two ecotypes. A survey of loci in 96 Arabidopsis accessions revealed a similar degree of methylation polymorphism. Within-gene methylation is heritable, but is lost at a high frequency in segregating F2 families. Promoter methylation is rare, and gene expression is not generally affected by differences in DNA methylation. Small interfering RNA are preferentially associated with methylated TEs, but not with methylated genes, indicating that most genic methylation is not guided by small interfering RNA. This may account for the instability of gene methylation, if occasional failure of maintenance methylation cannot be restored by other means. PMID:17579518

  4. Sieve-based relation extraction of gene regulatory networks from biological literature

    PubMed Central

    2015-01-01

    Background Relation extraction is an essential procedure in literature mining. It focuses on extracting semantic relations between parts of text, called mentions. Biomedical literature includes an enormous amount of textual descriptions of biological entities, their interactions and results of related experiments. To extract them in an explicit, computer readable format, these relations were at first extracted manually from databases. Manual curation was later replaced with automatic or semi-automatic tools with natural language processing capabilities. The current challenge is the development of information extraction procedures that can directly infer more complex relational structures, such as gene regulatory networks. Results We develop a computational approach for extraction of gene regulatory networks from textual data. Our method is designed as a sieve-based system and uses linear-chain conditional random fields and rules for relation extraction. With this method we successfully extracted the sporulation gene regulation network in the bacterium Bacillus subtilis for the information extraction challenge at the BioNLP 2013 conference. To enable extraction of distant relations using first-order models, we transform the data into skip-mention sequences. We infer multiple models, each of which is able to extract different relationship types. Following the shared task, we conducted additional analysis using different system settings that resulted in reducing the reconstruction error of bacterial sporulation network from 0.73 to 0.68, measured as the slot error rate between the predicted and the reference network. We observe that all relation extraction sieves contribute to the predictive performance of the proposed approach. Also, features constructed by considering mention words and their prefixes and suffixes are the most important features for higher accuracy of extraction. Analysis of distances between different mention types in the text shows that our choice

  5. The ethylene response pathway in Arabidopsis

    NASA Technical Reports Server (NTRS)

    Kieber, J. J.; Evans, M. L. (Principal Investigator)

    1997-01-01

    The simple gas ethylene influences a diverse array of plant growth and developmental processes including germination, senescence, cell elongation, and fruit ripening. This review focuses on recent molecular genetic studies, principally in Arabidopsis, in which components of the ethylene response pathway have been identified. The isolation and characterization of two of these genes has revealed that ethylene sensing involves a protein kinase cascade. One of these genes encodes a protein with similarity to the ubiquitous Raf family of Ser/Thr protein kinases. A second gene shows similarity to the prokaryotic two-component histidine kinases and most likely encodes an ethylene receptor. Additional elements involved in ethylene signaling have only been identified genetically. The characterization of these genes and mutants will be discussed.

  6. Stomatal Development in Arabidopsis

    PubMed Central

    Pillitteri, Lynn Jo; Dong, Juan

    2013-01-01

    Stomata consist of two guard cells that function as turgor-operated valves that regulate gas exchange in plants. In Arabidopsis, a dedicated cell lineage is initiated and undergoes a series of cell divisions and cell-state transitions to produce a stoma. A set of basic helix-loop-helix (bHLH) transcription factors regulates the transition and differentiation events through the lineage, while the placement of stomata relative to each other is controlled by intercellular signaling via peptide ligands, transmembrane receptors, and mitogen-activated protein kinase (MAPK) modules. Some genes involved in regulating stomatal differentiation or density are also involved in hormonal and environmental stress responses, which may provide a link between modulation of stomatal development or function in response to changes in the environment. Premitotic polarlylocalized proteins provide an added layer of regulation, which can be addressed more thoroughly with the identification of additional proteins in this pathway. Linking the networks that control stomatal development promises to bring advances to our understanding of signal transduction, cell polarity, and cell-fate specification in plants. PMID:23864836

  7. Synthesis of highly selective zeolite topology molecular sieve for adsorption of benzene gas

    NASA Astrophysics Data System (ADS)

    Wei, Lin; Chen, Yunlin; Zhang, Baoping; Zu, Zhinan

    2013-02-01

    Shangdong fly ash (SFA), Fangshan fly ash (FFA) and Heilongjiang fly ash (HFA) were selected as the raw materials to be used for synthesis of highly selective zeolite topology molecular sieve. Twice foaming method was studied in terms of synthetic zeolite. The experimental products were characterized by means of X-ray fluorescence (XRF), scanning electron microscope (SEM), X-ray diffraction (XRD), and automated surface area & pore size analyser. The results indicated that 10 M NaOH was chosen as modification experiment condition to process SFA. Crystallization temperature and time were 140 °C and 8 h, respectively. Zeolite topology molecular sieve was prepared with Si/Al molar ratio of 7.9, and its adsorption ratio of benzene gas was up to 66.51%.

  8. Chip-based optical microscopy for imaging membrane sieve plates of liver scavenger cells

    NASA Astrophysics Data System (ADS)

    Helle, Øystein I.; Øie, Cristina I.; McCourt, Peter; Ahluwalia, Balpreet S.

    2015-08-01

    The evanescent field on top of optical waveguides is used to image membrane network and sieve-plates of liver endothelial cells. In waveguide excitation, the evanescent field is dominant only near the surface (~100-150 nm) providing a default optical sectioning by illuminating fluorophores in close proximity to the surface and thus benefiting higher signal-to-noise ratio. The sieve plates of liver sinusoidal endothelial cells are present on the cell membrane, thus near-field waveguide chip-based microscopy configuration is preferred over epi-fluorescence. The waveguide chip is compatible with optical fiber components allowing easy multiplexing to different wavelengths. In this paper, we will discuss the challenges and opportunities provided by integrated optical microscopy for imaging cell membranes.

  9. Synthesis of a specified, silica molecular sieve by using computationally predicted organic structure-directing agents.

    PubMed

    Schmidt, Joel E; Deem, Michael W; Davis, Mark E

    2014-08-01

    Crystalline molecular sieves are used in numerous applications, where the properties exploited for each technology are the direct consequence of structural features. New materials are typically discovered by trial and error, and in many cases, organic structure-directing agents (OSDAs) are used to direct their formation. Here, we report the first successful synthesis of a specified molecular sieve through the use of an OSDA that was predicted from a recently developed computational method that constructs chemically synthesizable OSDAs. Pentamethylimidazolium is computationally predicted to have the largest stabilization energy in the STW framework, and is experimentally shown to strongly direct the synthesis of pure-silica STW. Other OSDAs with lower stabilization energies did not form STW. The general method demonstrated here to create STW may lead to new, simpler OSDAs for existing frameworks and provide a way to predict OSDAs for desired, theoretical frameworks. PMID:24961789

  10. Evaluation of RTV as a Moldable Matrix When Combined With Molecular Sieve and Organic Hydrogen Getter

    SciTech Connect

    Knight, J. A.

    2011-12-01

    This work was undertaken in an effort to develop a combined RTV 615/3Å molecular sieve/DEB molded component. A molded RTV 615/3Å molecular sieve component is currently in production, and an RTV 615/DEB component was produced in the past. However, all three materials have never before been combined in a single production part, and this is an opportunity to create a new component capable of being molded to shape, performing desiccation, and hydrogen gettering. This analysis looked at weapons system parameters and how they might influence part design. It also looked at material processing and how it related to mixing, activating a dessicant, and hydrogen uptake testing.