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Sherry, A. D., P. Zhao, A. J. Wiethoff, F. M. H. Jeffrey, and C. R. Malloy. "Effects of aminooxyacetate on glutamate compartmentation and TCA cycle kinetics in rat hearts." American Journal of Physiology-Heart and Circulatory Physiology 274, no. 2 (February 1, 1998): H591—H599. http://dx.doi.org/10.1152/ajpheart.1998.274.2.h591.
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The nonspecific transaminase inhibitor aminooxyacetate (AOA) has multiple influences on the dynamics of13C appearance in glutamate in rat hearts as measured by 13C nuclear magnetic resonance (NMR) without altering O2 consumption or tricarboxylic acid (TCA) cycle flux. These include the following: 1) a reduced rate of13C enrichment at glutamate C3 and C4; 2) a near coalescence of the C3 and C4 fractional enrichment curves; 3) a dramatic alteration in the time-dependent evolution of the glutamate C4 multiplets, C4S and C4D34; and 4) a decrease in the NMR visibility of glutamate. A fit of the13C fractional enrichment curves of glutamate C4 and C3 in the absence of inhibitor to a kinetic model of the TCA cycle gave values for transaminase flux of 7.5 μmol ⋅ min−1 ⋅ g dry wt−1 and TCA cycle flux of 7.5 μmol ⋅ min−1 ⋅ g dry wt−1, thereby confirming reports by others that the kinetics of13C enrichment of glutamate C3 and C4 in heart tissue is significantly affected by flux through reactions other than TCA cycle. The 13C fractional enrichment data collected in the presence of 0.5 mM AOA could not be fitted using this same kinetic model. However, kinetic simulations demonstrated that the time-dependent changes in C4S and C4D34 are only consistent with a 10-fold reduction in the size of intermediate pools undergoing rapid turnover in the TCA cycle. We conclude that inhibition of glutamic-oxalacetic transaminase by AOA effectively reduces the size of the α-ketoglutarate pool in rapid exchange with the TCA cycle. Our data indicate that changes in glutamate multiplet areas in the13C NMR spectra of heart (as demonstrated by glutamate C4S and C4D34) are more sensitive to alterations in metabolic pool sizes in exchange with the TCA cycle than are measurements of 13C fractional enrichment at glutamate C3 and C4.
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Hattersley, PW, and NE Stone. "Photosynthetic Enzyme Activities in the C3-C4 Intermediate Neurachne minor S. T . Blake (Poaceae)." Functional Plant Biology 13, no. 3 (1986): 399. http://dx.doi.org/10.1071/pp9860399.
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The activities of eight key photosynthetic enzymes were measured in leaf blade extracts of the C3-C4 intermediate Neurachne minor S. T. Blake, its C3 and C4 relatives, C3-C4 Panicum milioides Nees ex Trin., and controls (all Poaceae). Phosphoenolpyruvate (PEP) carboxylase (PEPC) activity in N. minor (5.46 �mol mg Chl-1 min-1) is higher than previously reported for any other C3-C3 plant, and the ratio of ribulose-1,5-bisphosphate carboxylase activity to PEPC activity is lower than for P. milioides or C3 species. Activity of pyruvate,PI dikinase (up to 0.88 �mol mg Chl-1 min-1) is 3-5 times higher than in P. milioides. Assays of NADP-malic enzyme (NADP-ME), NAD-malic enzyme (NAD-ME) and PEP carboxykinase (PCK) show Paraneurachne muelleri (Hack.) S. T. Blake and Neurachne munroi (F. Muell.) F. Muell., N. minor's two close C4 relatives, to be NADP-ME type, as predicted from leaf anatomy. Aspartate and alanine aminotransferase activities in these species are higher than expected, however. N. minor (C3-C4) exhibits higher C4 acid decarboxylase activity than C3 species or P. milioides, for NADP-ME only (up to 1.07 �mol mg Chl-1 min-1). Our results suggest that N. minor possesses a limited C4 acid cycle, and that it is the most C4-like C3-C4 intermediate grass currently identified, comparable with some of the known C3-C4 Flaveria (Asteraceae) species.
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Krall, JP, GE Edwards, and MSB Ku. "Quantum Yield of Photosystem II and Efficiency of CO2 Fixation in Flaveria (Asteraceae) Species under Varying Light and CO2." Functional Plant Biology 18, no. 4 (1991): 369. http://dx.doi.org/10.1071/pp9910369.
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The quantum yields of electron transport from photosystem II (PSII) (Φe, determined from chlorophyll a fluorescence), and CO2 assimilation (ΦCO2, photosynthetic rate/light intensity) were measured simultaneously in vivo with representative species of Flaveria which show a progression in development between C3 and C4 photosynthesis and in reduction of photorespiration. These were F. pringlei (C3), F. sonorensis (C3-C4, but lacking a C4 cycle), F. floridana (C3-C4, with partially functional C4 cycle), F. brownii (C4-like) and F. bidentis (C4). The level of PSII activity with varying CI under 210 mbar O2 was very similar in all species. However, the progressive development of C4 characteristics among the species produced an increased efficiency in utilisation of PSII derived energy for CO2 assimilation under 210 mbar O2, due to reduced photorespiratory losses at low CO2 levels. In all species, when photorespiration was limited by low O2 (20 mbar), there was a linear or near linear relationship between the quantum yield of PSII v. the quantum yield of CO2 fixation with varying intercellular levels of CO2 (Ci) indicating that CO2 fixation in this case is linked to PSII activity. When switching from 20 to 210 mbar O2 at atmosphere levels of CO2, there was a similar decrease in the efficiency in utilising PSII activity for CO2 assimilation at different light intensities, but the degree of sensitivity to O2 progressively decreased among the species concomitant with the development of C4 photosynthesis. These results may help explain why there is an advantage to evolution of C4 photosynthesis in environments where Ci becomes limiting.
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Salgia, Ravi, Benjamin J. Solomon, Alice Tsang Shaw, D. Ross Camidge, Tracey L. Evans, Dong-Wan Kim, Yuankai Shi, et al. "Visual effects in anaplastic lymphoma kinase (ALK)-positive advanced non-small cell lung cancer (NSCLC) patients treated with crizotinib." Journal of Clinical Oncology 30, no. 15_suppl (May 20, 2012): 7596. http://dx.doi.org/10.1200/jco.2012.30.15_suppl.7596.
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7596 Background: Crizotinib is an ALK inhibitor indicated in the US for advanced ALK-positive NSCLC. Visual effects reported by patients treated with crizotinib were characterized using the Visual Symptom Assessment Questionnaire (VSAQ). Methods: Patients with previously treated, advanced ALK-positive NSCLC were administered 250 mg BID crizotinib in an ongoing phase II study (PROFILE1005, NCT00932451; Pfizer). Patients completed the VSAQ at day 1 of each 21 day cycle and at end of treatment. The VSAQ has a recall period of 3 weeks and consists of 7 questions assessing presence, frequency, timing, duration and degree of bother of visual effects and their impact on Activities of Daily Living (ADL). The visual effects assessed included appearance of overlapping shadows/after images, flashing lights and streamers/strings/floaters, difficulty adapting to lights and seeing at night. Patients rated degree of bother on a 5-point scale ranging from ‘not at all’ to ‘extremely’. Impact on ADL was measured using a 10-point scale (0: no effect; 10: completely prevented ADL). Frequency analyses were performed. Results: As of June 1 2011, visual effects as identified by VSAQ were reported by 63% (114/182) of patients at cycle 2 (C2), 57% at C3 (85/149), 52% at C4 (64/123) and 41% at C5 (46/112). The most commonly experienced visual events were appearance of flashing lights (C2:81%; C3:82%; C4:84%; C5: 76%), streamers/strings/floaters (C2: 83%; C3:78%; C4: 81%; C5:87%) and overlapping shadows/after images (C2:70%; C3:77%; C4:87%; C5:84%). Most patients reported each event to last ≤1 minute (C2:61%; C3:71%; C4:77%; C5: 70%). Majority of patients reported event frequency at each cycle of < 7 days/wk (50–78%). Patients reported that the visual effects occurred mostly in the morning (52–62%) and/or evening (62–73%). Majority of patients reported that visual effects were not at all or a little bothersome (C2:62%; C3:61%; C4:66%; C5:65%). Majority of patients indicated no or minimal impact on ADL (C2:80%; C3:80%; C4:83%; C5:87%). Conclusions: Visual effects identified by VSAQ in patients treated with crizotinib were frequent, but were reported to be transient with no or minimal impact on ADL.
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Balcaen, A., E. Claeys, V. Fievez, P. Boeckx, O. van Cleemput, and S. de Smet. "Stable carbon isotope analysis of faecal and blood samples of sheep in relation to the diet." Proceedings of the British Society of Animal Science 2003 (2003): 159. http://dx.doi.org/10.1017/s1752756200013181.
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Stable isotopes have been extraordinarily helpful in understanding animal migration, diet, food webs and nutrient flow (Hilderbrand et al., 1996), based on the property that C3 and C4 plants possess distinctly different 13C/12C ratios (δ13C value) due to isotopic fractionation during photosynthetic carbon fixation (Smith & Epstein, 1971). Most woody species and temperate graminoids assimilate carbon via the Calvin cycle (C3), which discriminates stronger against the heavier isotope (13C) than Hatch-Slack (C4) species (tropical and subtropical graminoids and some shrubs). C3 and C4 plant species have mean δ13C values of -27 ‰ and -13 ‰ respectively (O’Leary, 1981). DeNiro & Epstein (1978) were one of the first to show that the isotopic composition of the whole animal body is similar to that of its diet. Other authors have also found relationships between the isotopic composition of animal tissues and the diet (González-Martin et al., 1999; Jones et al., 1979). The aim of this study was to investigate stable carbon isotope composition in sheep fed diets consisting of either C3 or C3+C4 plants.
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Mason, Graeme F., Douglas L. Rothman, Kevin L. Behar, and Robert G. Shulman. "NMR Determination of the TCA Cycle Rate and α-Ketoglutarate/Glutamate Exchange Rate in Rat Brain." Journal of Cerebral Blood Flow & Metabolism 12, no. 3 (May 1992): 434–47. http://dx.doi.org/10.1038/jcbfm.1992.61.
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A mathematical model of cerebral glucose metabolism was developed to analyze the isotopic labeling of carbon atoms C4 and C3 of glutamate following an intravenous infusion of [1-13C]glucose. The model consists of a series of coupled metabolic pools representing glucose, glycolytic intermediates, tricarboxylic acid (TCA) cycle intermediates, glutamate, aspartate, and glutamine. Based on the rate of 13C isotopic labeling of glutamate C4 measured in a previous study, the TCA cycle rate in rat brain was determined to be 1.58 ± 0.41 μmol min−1 g−1 (mean ± SD, n = 5). Analysis of the difference between the rates of isotopic enrichment of glutamate C4 and C3 permitted the rate of exchange between α-ketoglutarate (α-KG) and glutamate to be assessed in vivo. In rat brain, the exchange rate between α-KG and glutamate is between 89 ± 35 and 126 ± 22 times faster than the TCA cycle rate (mean ± SD, n = 4). The sensitivity of the calculated value of the TCA cycle rate to other metabolic fluxes and to concentrations of glycolytic and TCA cycle intermediates was tested and found to be small.
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Stitt, Mark, Gian Luca Borghi, and Stéphanie Arrivault. "Targeted metabolite profiling as a top-down approach to uncover interspecies diversity and identify key conserved operational features in the Calvin–Benson cycle." Journal of Experimental Botany 72, no. 17 (June 22, 2021): 5961–86. http://dx.doi.org/10.1093/jxb/erab291.
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Abstract Improving photosynthesis is a promising avenue to increase crop yield. This will be aided by better understanding of natural variance in photosynthesis. Profiling of Calvin–Benson cycle (CBC) metabolites provides a top-down strategy to uncover interspecies diversity in CBC operation. In a study of four C4 and five C3 species, principal components analysis separated C4 species from C3 species and also separated different C4 species. These separations were driven by metabolites that reflect known species differences in their biochemistry and pathways. Unexpectedly, there was also considerable diversity between the C3 species. Falling atmospheric CO2 and changing temperature, nitrogen, and water availability have driven evolution of C4 photosynthesis in multiple lineages. We propose that analogous selective pressures drove lineage-dependent evolution of the CBC in C3 species. Examples of species-dependent variation include differences in the balance between the CBC and the light reactions, and in the balance between regulated steps in the CBC. Metabolite profiles also reveal conserved features including inactivation of enzymes in low irradiance, and maintenance of CBC metabolites at relatively high levels in the absence of net CO2 fixation. These features may be important for photosynthetic efficiency in low light, fluctuating irradiance, and when stomata close due to low water availability.
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Zhang, Xuecai, Paulino Pérez-Rodríguez, Juan Burgueño, Michael Olsen, Edward Buckler, Gary Atlin, Boddupalli M. Prasanna, Mateo Vargas, Félix San Vicente, and José Crossa. "Rapid Cycling Genomic Selection in a Multiparental Tropical Maize Population." G3 Genes|Genomes|Genetics 7, no. 7 (July 1, 2017): 2315–26. http://dx.doi.org/10.1534/g3.117.043141.
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Abstract Genomic selection (GS) increases genetic gain by reducing the length of the selection cycle, as has been exemplified in maize using rapid cycling recombination of biparental populations. However, no results of GS applied to maize multi-parental populations have been reported so far. This study is the first to show realized genetic gains of rapid cycling genomic selection (RCGS) for four recombination cycles in a multi-parental tropical maize population. Eighteen elite tropical maize lines were intercrossed twice, and self-pollinated once, to form the cycle 0 (C0) training population. A total of 1000 ear-to-row C0 families was genotyped with 955,690 genotyping-by-sequencing SNP markers; their testcrosses were phenotyped at four optimal locations in Mexico to form the training population. Individuals from families with the best plant types, maturity, and grain yield were selected and intermated to form RCGS cycle 1 (C1). Predictions of the genotyped individuals forming cycle C1 were made, and the best predicted grain yielders were selected as parents of C2; this was repeated for more cycles (C2, C3, and C4), thereby achieving two cycles per year. Multi-environment trials of individuals from populations C0, C1, C2, C3, and C4, together with four benchmark checks were evaluated at two locations in Mexico. Results indicated that realized grain yield from C1 to C4 reached 0.225 ton ha−1 per cycle, which is equivalent to 0.100 ton ha−1 yr−1 over a 4.5-yr breeding period from the initial cross to the last cycle. Compared with the original 18 parents used to form cycle 0 (C0), genetic diversity narrowed only slightly during the last GS cycles (C3 and C4). Results indicate that, in tropical maize multi-parental breeding populations, RCGS can be an effective breeding strategy for simultaneously conserving genetic diversity and achieving high genetic gains in a short period of time.
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Angelo, Courtney L., and Curtis C. Daehler. "Temperature is the major driver of distribution patterns for C4 and C3 BEP grasses along tropical elevation gradients in Hawai‘i, and comparison with worldwide patterns." Botany 93, no. 1 (January 2015): 9–22. http://dx.doi.org/10.1139/cjb-2014-0075.
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The distribution patterns of C4 and C3 grasses in relation to climate have attracted much attention, but few studies have examined grass distributions along tropical elevation gradients. Previous studies identified either temperature, precipitation, or both variables as the major climatic factor(s) driving these distributions. Here we investigated relative dominance of C4 grasses in relation to climate along five elevation gradients in Hawai‘i. The transition temperature between C4 and C3 BEP (Bambusoideae, Ehrhartoideae, and Pooideae) grasses (where their relative dominance is equal) was determined; in our study, the subfamily Bambusoideae was not included. A worldwide synthesis of previous studies testing climatic factors and transition temperatures associated with C4 and C3 grass distributions was also carried out. Mean July maximum temperature was significantly correlated with C4 dominance along all elevation transects in Hawai‘i, while precipitation was only correlated along three transects when precipitation was correlated with temperature. A spatially explicit multiple regression model indicated that C4 relative cover was best explained by temperature. Temperature appears to be the major climatic factor shaping distribution patterns of C4 and C3 BEP grasses in Hawai‘i. According to the worldwide analysis, temperature primarily influenced grass distribution patterns more often in temperate studies (70%) than in tropical studies (45%). Degree of correlation or covariance between temperature and precipitation was rarely reported in previous studies, although this can strongly affect conclusions. C4-C3 BEP transition temperatures (mean July maximum) ranged from 18 to 21 °C in Hawai‘i; these transition temperatures are lower than those reported in temperate localities (26–31 °C), but similar to transition temperatures for other localities at tropical latitudes (21–22 °C). A warming climate is likely to shift C4 grass dominance upward in elevation, threatening higher elevation native communities by perpetuating a grass–fire cycle.
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Häusler, Rainer E., Heinz‐Josef Hirsch, Fritz Kreuzaler, and Christoph Peterhänsel. "Overexpression of C4‐cycle enzymes in transgenic C3 plants: a biotechnological approach to improve C3‐photosynthesis." Journal of Experimental Botany 53, no. 369 (April 1, 2002): 591–607. http://dx.doi.org/10.1093/jexbot/53.369.591.
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Sudderth, Erika A., Riyadh M. Muhaidat, Athena D. McKown, Ferit Kocacinar, and Rowan F. Sage. "Leaf anatomy, gas exchange and photosynthetic enzyme activity in Flaveria kochiana." Functional Plant Biology 34, no. 2 (2007): 118. http://dx.doi.org/10.1071/fp06263.
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Flaveria (Asteraceae) is one of the few genera known to contain both C3 and C4 species, in addition to numerous biochemically-intermediate species. C3-C4 and C4-like intermediate photosynthesis have arisen more than once in different phylogenetic clades of Flaveria. Here, we characterise for the first time the photosynthetic pathway of the recently described species Flaveria kochiana B.L. Turner. We examined leaf anatomy, activity and localisation of key photosynthetic enzymes, and gas exchange characteristics and compared these trait values with those from related C4 and C4-like Flaveria species. F. kochiana has Kranz anatomy that is typical of other C4 Flaveria species. As in the other C4 lineages within the Flaveria genus, the primary decarboxylating enzyme is NADP-malic enzyme. Immunolocalisation of the major C4 cycle enzymes, PEP carboxylase and pyruvate, orthophosphate dikinase, were restricted to the mesophyll, while Rubisco was largely localised to the bundle sheath. Gas exchange analysis demonstrated that F. kochiana operates a fully functional C4 pathway with little sensitivity to ambient oxygen levels. The CO2 compensation point (2.2 µbar) was typical for C4 species, and the O2-response of the CO2 compensation point was the same as the C4 species F. trinervia. Notably, F. vaginata (B.L. Robinson & Greenman), a putative C4-like species that is the nearest relative of F. kochiana, had an identical response of the CO2 compensation point to O2. Furthermore, F. vaginata, exhibited a carbon isotope ratio (–15.4‰) similar to C4 species including F. australasica Hooker, F. trinervia Spreng. C. Mohr and the newly characterised F. kochiana. F. vaginata could be considered a C4 species, but additional studies are necessary to confirm this hypothesis. In addition, our results show that F. kochiana uses an efficient C4 cycle, with the highest initial slope of the A/Ci curve of any C4 Flaveria species.
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Dunning, Luke T., Jose J. Moreno-Villena, Marjorie R. Lundgren, Jacqueline Dionora, Paolo Salazar, Claire Adams, Florence Nyirenda, et al. "Key changes in gene expression identified for different stages of C4 evolution in Alloteropsis semialata." Journal of Experimental Botany 70, no. 12 (April 5, 2019): 3255–68. http://dx.doi.org/10.1093/jxb/erz149.
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Abstract C4 photosynthesis is a complex trait that boosts productivity in tropical conditions. Compared with C3 species, the C4 state seems to require numerous novelties, but species comparisons can be confounded by long divergence times. Here, we exploit the photosynthetic diversity that exists within a single species, the grass Alloteropsis semialata, to detect changes in gene expression associated with different photosynthetic phenotypes. Phylogenetically informed comparative transcriptomics show that intermediates with a weak C4 cycle are separated from the C3 phenotype by increases in the expression of 58 genes (0.22% of genes expressed in the leaves), including those encoding just three core C4 enzymes: aspartate aminotransferase, phosphoenolpyruvate carboxykinase, and phosphoenolpyruvate carboxylase. The subsequent transition to full C4 physiology was accompanied by increases in another 15 genes (0.06%), including only the core C4 enzyme pyruvate orthophosphate dikinase. These changes probably created a rudimentary C4 physiology, and isolated populations subsequently improved this emerging C4 physiology, resulting in a patchwork of expression for some C4 accessory genes. Our work shows how C4 assembly in A. semialata happened in incremental steps, each requiring few alterations over the previous step. These create short bridges across adaptive landscapes that probably facilitated the recurrent origins of C4 photosynthesis through a gradual process of evolution.
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Voznesenskaya, Elena V., Simon D. X. Chuong, Nuria K. Koteyeva, Gerald E. Edwards, and Vincent R. Franceschi. "Functional compartmentation of C4 photosynthesis in the triple layered chlorenchyma of Aristida (Poaceae)." Functional Plant Biology 32, no. 1 (2005): 67. http://dx.doi.org/10.1071/fp04118.
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The genus Aristida (Poaceae), is composed of species that have Kranz anatomy and C4 photosynthesis. Kranz anatomy typically consists of two photosynthetic cell types: a layer of mesophyll cells where atmospheric CO2 is fixed into C4 acids, and an internal, chlorenchymatous vascular bundle sheath to which C4 acids are transferred and then decarboxylated to donate CO2 to the C3 cycle. The anatomy of Aristida species is unusual as it has three distinct layers of chlorenchyma cells surrounding the vascular tissue: an inner bundle sheath, an outer bundle sheath and the mesophyll cells. In this study of Aristida purpurea Nutt. var. longiseta, the functions of the three layers of chlorenchyma cells relative to the C4 photosynthetic mechanism were determined using ultrastructural analysis, western blots, immunolocalisation of photosynthetic enzymes and starch histochemistry. The results indicate that mesophyll cells contain high levels of phosphoenolpyruvate carboxylase (PEPC) and pyruvate Pi dikinase (PPDK), and function to capture CO2 in the C4 cycle. The inner bundle sheath, which is high in Rubisco and contains NADP-malic enzyme and glycine decarboxylase, functions to transfer CO2 to the C3 cycle through decarboxylation of C4 acids and by decarboxylation of glycine in the glycolate pathway. The outer chlorenchymatous sheath is where ADPG pyrophosphorylase is mainly located, and this cell layer functions as the primary site of starch storage. The outer sheath, which has low levels of Rubisco and PEPC, may also have a role in refixation of any CO2 that leaks from the inner bundle sheath cells.
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Roell, Marc-Sven, Lennart Schada von Borzyskowski, Philipp Westhoff, Anastasija Plett, Nicole Paczia, Peter Claus, Urte Schlueter, Tobias J. Erb, and Andreas P. M. Weber. "A synthetic C4 shuttle via the β-hydroxyaspartate cycle in C3 plants." Proceedings of the National Academy of Sciences 118, no. 21 (May 17, 2021): e2022307118. http://dx.doi.org/10.1073/pnas.2022307118.
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Plants depend on the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) for CO2 fixation. However, especially in C3 plants, photosynthetic yield is reduced by formation of 2-phosphoglycolate, a toxic oxygenation product of Rubisco, which needs to be recycled in a high-flux–demanding metabolic process called photorespiration. Canonical photorespiration dissipates energy and causes carbon and nitrogen losses. Reducing photorespiration through carbon-concentrating mechanisms, such as C4 photosynthesis, or bypassing photorespiration through metabolic engineering is expected to improve plant growth and yield. The β-hydroxyaspartate cycle (BHAC) is a recently described microbial pathway that converts glyoxylate, a metabolite of plant photorespiration, into oxaloacetate in a highly efficient carbon-, nitrogen-, and energy-conserving manner. Here, we engineered a functional BHAC in plant peroxisomes to create a photorespiratory bypass that is independent of 3-phosphoglycerate regeneration or decarboxylation of photorespiratory precursors. While efficient oxaloacetate conversion in Arabidopsis thaliana still masks the full potential of the BHAC, nitrogen conservation and accumulation of signature C4 metabolites demonstrate the proof of principle, opening the door to engineering a photorespiration-dependent synthetic carbon–concentrating mechanism in C3 plants.
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Xin, Lijing, Bernard Lanz, gxia Lei, and Rolf Gruetter. "Assessment of Metabolic Fluxes in the Mouse Brain in Vivo Using 1H-[13C] NMR Spectroscopy at 14.1 Tesla." Journal of Cerebral Blood Flow & Metabolism 35, no. 5 (January 21, 2015): 759–65. http://dx.doi.org/10.1038/jcbfm.2014.251.
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13C magnetic resonance spectroscopy (MRS) combined with the administration of 13C labeled substrates uniquely allows to measure metabolic fluxes in vivo in the brain of humans and rats. The extension to mouse models may provide exclusive prospect for the investigation of models of human diseases. In the present study, the short-echo-time (TE) full-sensitivity 1H-[13C] MRS sequence combined with high magnetic field (14.1 T) and infusion of [U-13C6] glucose was used to enhance the experimental sensitivity in vivo in the mouse brain and the 13C turnover curves of glutamate C4, glutamine C4, glutamate+glutamine C3, aspartate C2, lactate C3, alanine C3, γ-aminobutyric acid C2, C3 and C4 were obtained. A one-compartment model was used to fit 13C turnover curves and resulted in values of metabolic fluxes including the tricarboxylic acid (TCA) cycle flux VTCA (1.05 ± 0.04 μmol/g per minute), the exchange flux between 2-oxoglutarate and glutamate Vx (0.48 ± 0.02 μmol/g per minute), the glutamate-glutamine exchange rate Vgln (0.20 ± 0.02 μmol/g per minute), the pyruvate dilution factor Kdil (0.82 ± 0.01), and the ratio for the lactate conversion rate and the alanine conversion rate VLac/ VAla (10 ± 2). This study opens the prospect of studying transgenic mouse models of brain pathologies.
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Laisk, Agu, and Gerald E. Edwards. "CO2 and Temperature-dependent Induction in C4 Photosynthesis: an Approach to the Hierarchy of Rate-limiting Processes." Functional Plant Biology 24, no. 4 (1997): 505. http://dx.doi.org/10.1071/pp97011.
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Rate-limiting processes for C4 photosynthesis were examined in Sorghum bicolor, an NADP-ME type species, and Amaranthus cruentus, an NAD-ME type C4 species, by studying the kinetics of transient changes in photosynthetic rates following rapid changes in CO2 or temperature. Primary responses (faster than 15 s) to increasing CO2 or temperature are considered direct effects on the turnover rate of the C4 cycle, whereas medium transient changes (2–3 min) are considered due to build-up of C4 cycle intermediates, and the slowest transient changes (20–30 min) are thought to be related to end product synthesis. Reciprocal plot of carboxylation rates versus cell wall (dissolved) CO2 concentration (Cw) gives an apparent Km (CO2) of 8 µM and a Vm of 200 µmol m-2 s-1 for PEP carboxylase, which is about 4 times higher than the maximum rate of photosynthesis. Under strictly limiting CO2, the rate of PEP carboxylation in C4 photosynthesis is independent of temperature (20–35°C), suggesting a physical rather than a biochemical limitation. It is suggested that the rates of C3 and C4 cycles are coordinated through the pool sizes of the C4 cycle, which are in equilibrium with the pool of 3-phosphoglyceric acid. At low CO2, the C4 pools decrease and are slowly regenerated at elevated CO2, restricting the CO2 response of C4 photosynthesis.
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Blaitt, Regina Maria Nascimento Augusto, Vivian Lo Tierzo, Juliana Célia Denadai, Cibele Regina de Souza Kruliski, Carlos Ducatti, Dirlei Antonio Berto, and Maria Márcia Pereira Sartori. "Isotopic carbon turnover in pig hoof and rib." Acta Scientiarum. Animal Sciences 43 (April 23, 2021): e48299. http://dx.doi.org/10.4025/actascianimsci.v43i1.48299.
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The objective of this study was to evaluate the behavior of carbon incorporation and turnover in hoof and ribs of pigs at different periods of development in the search for tissues that reflect longer the former diet. We used 132 commercial hybrids (barrows and females), weaned at an average age of 21 days, distributed in a completely randomized design with four treatments on different days of substitution of corn (C4 cycle plant grain) diets with broken rice (C3 cycle plant grain) at 21, 42, 63 and 110 days of age to change the carbon-13 isotope signal. By means of isotopic dilution curves, we observed that animals whose C4 diet was replaced with C3 diet at 21, 42, 63 and 110 days of age, for hoof and rib, reached a new level of isotope equilibrium. Bone samples are better choices to reflect the former diet, due to conservation of the isotopic signal for longer.
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Rütting, Tobias, and Mark J. Hovenden. "Soil nitrogen cycle unresponsive to decadal long climate change in a Tasmanian grassland." Biogeochemistry 147, no. 1 (December 10, 2019): 99–107. http://dx.doi.org/10.1007/s10533-019-00627-9.
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AbstractIncreases in atmospheric carbon dioxide (CO2) and global air temperature affect all terrestrial ecosystems and often lead to enhanced ecosystem productivity, which in turn dampens the rise in atmospheric CO2 by removing CO2 from the atmosphere. As most terrestrial ecosystems are limited in their productivity by the availability of nitrogen (N), there is concern about the persistence of this terrestrial carbon sink, as these ecosystems might develop a progressive N limitation (PNL). An increase in the gross soil N turnover may alleviate PNL, as more mineral N is made available for plant uptake. So far, climate change experiments have mainly manipulated one climatic factor only, but there is evidence that single-factor experiments usually overestimate the effects of climate change on terrestrial ecosystems. In this study, we investigated how simultaneous, decadal-long increases in CO2 and temperature affect the soil gross N dynamics in a native Tasmanian grassland under C3 and C4 vegetation. Our laboratory 15N labeling experiment showed that average gross N mineralization ranged from 4.9 to 11.3 µg N g−1 day−1 across the treatment combinations, while gross nitrification was about ten-times lower. Considering all treatment combinations, no significant effect of climatic treatments or vegetation type (C3 versus C4 grasses) on soil N cycling was observed.
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Peterhansel, C. "Best practice procedures for the establishment of a C4 cycle in transgenic C3 plants." Journal of Experimental Botany 62, no. 9 (February 18, 2011): 3011–19. http://dx.doi.org/10.1093/jxb/err027.
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Hatté, C., C. Gauthier, D. D. Rousseau, P. Antoine, M. Fuchs, F. Lagroix, S. B. Markovich, O. Moine, and A. Sima. "Excursions to C<sub>4</sub> vegetation recorded in the Upper Pleistocene loess of Surduk (Northern Serbia): an organic isotope geochemistry study." Climate of the Past Discussions 9, no. 1 (January 11, 2013): 187–215. http://dx.doi.org/10.5194/cpd-9-187-2013.
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Abstract. Loess sequences have been intensively studied to characterize past glacial climates of the 40–50 ° North and South latitude zones. Combining different approaches of sedimentology, magnetism, geochemistry, geochronology and malacology allows the general pattern of the climate and environment of the last interglacial-glacial cycle in Eurasia and America to be characterized. Previous studies performed in Europe have highlighted the predominance (if not the sole occurrence) of C3 vegetation. The presence of C3 plants suggests a regular distribution of precipitation along the year. Therefore, even if the mean annual precipitation remained very low during the most extensive glacial times, free water was available for more than 2 months per year. Contrarily, the δ13C record of Surduk (Serbia) clearly shows the occurrence and dominance of C4 plants during at least 4 episodes of the last glacial times at [26.0–28.0], [30.0–31.4], [44.5–53.4] and [66.1–86.8] (in kyrs cal. B.P.). The C4 plant development is interpreted as a specific atmospheric circulation pattern that induces short and dry summer conditions. As possible explanation, we propose that during "C4 episodes", the Mediterranean Sea would have been under the combined influence of the following: (i) a strong meridional circulation unfavorable to water evaporation that reduced the Mediterranean precipitation on the Balkans; and (ii) a high positive North Atlantic Western Russian (NAWR)-like atmospheric pattern that favored northerlies over westerlies and reduced Atlantic precipitation over the Balkans. This configuration would imply very dry summers that did not allow C3 plants to grow, thus supporting C4 development. The intra "C4 episode" periods would have occurred under less drastic oceanic and atmospheric patterns that made the influence of westerlies on the Balkans possible.
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Doyle, Jason R., James N. Burnell, Dianne S. Haines, Lyndon E. Llewellyn, Cherie A. Motti, and Dianne M. Tapiolas. "A Rapid Screening Method to Detect Specific Inhibitors of Pyruvate Orthophosphate Dikinase as Leads for C₄ Plant-Selective Herbicides." Journal of Biomolecular Screening 10, no. 1 (February 2005): 67–75. http://dx.doi.org/10.1177/1087057104269978.
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Plants using the C4 photosynthetic pathway are highly represented among the world’s worst weeds, with only 4 C4 species being agriculturally productive (maize, sorghum, millet, and sugar cane). With the C4 acid cycle operating as a biochemical appendage of C3 photosynthesis, the additional enzymes involved in C4 photosynthesis represent an attractive target for the development of weed-specific herbicides. The rate-limiting enzyme of this metabolic pathway is pyruvate orthophosphate dikinase (PPDK). PPDK, coupled with phosphoenolpyruvate carboxylase and nicotinamide adenine dinucleotide-malate dehydrogenase, was used to develop a microplate-based assay to detect inhibitors of enzymes of the C4 acid cycle. The resulting assay had a Z′ factor of 0.61, making it a high-quality assay able to reliably identify active test samples. Organic extracts of 6679 marine macroscopic organisms were tested within the assay, and 343 were identified that inhibited the 3 enzyme-coupled reaction. A high confirmation rate was achieved, with 95% of these hit extracts proving active again upon retesting. Sequential addition of phosphoenolpyruvate and oxaloacetate to the assay facilitated identification of 83 extracts that specifically inhibited PPDK. ( Journal of Biomolecular Screening 2005:67-75)
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Wilson, J. P., R. N. Gates, and M. S. Panwar. "Dynamic Multiline Population Approach to Resistance Gene Management." Phytopathology® 91, no. 3 (March 2001): 255–60. http://dx.doi.org/10.1094/phyto.2001.91.3.255.
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The dynamic multiline population breeding strategy integrates principles from the gene stacking and multiline approaches and allows application of the multiline strategy to cross-pollinated hybrid crops. Experiments were conducted to evaluate the effectiveness of the breeding approach. Backcross derivatives of pearl millet Tift 23DB were developed with rust resistance from 18 Burkina Faso landraces, 3 Pennisetum glaucum subsp. monodii accessions, and 2 elite inbreds (1 from India and 1 from the United States). Four cycles of open pollination were made, the last two in the field in rust epidemics. Cytoplasmic male-sterile (CMS) counterparts of the populations in the A4 cytoplasm were included and advanced simultaneously with the B population. Hybrids with Tift 383 were produced on CMS cycles 1 (C1) through C4. Frequency of hybrid seedlings with resistance increased with each cycle, and frequencies averaged 18 to 38% in C1 to C4 hybrids, respectively, when inoculated with five single-uredinium isolates of Puccinia substriata var. indica. The hybrid populations and Tifleaf (TL)1 and TL2 were evaluated in three yield trials in 1998 to 1999. Disease-free forage dry matter yields did not differ among hybrids. Across trials, area under the disease progress curve (AUDPC) of TL1 and TL2 averaged 1,307, C1 and C2 averaged 914, and C3 and C4 averaged 604. Final severities of TL1 and TL2 averaged 67%, C1 and C2 averaged 47%, and C3 and C4 averaged 30%. When analyzed by regression analysis, AUDPC was reduced 12.2%, final rust severity was reduced 13.3%, and digestible biomass was increased 4.1% per cycle.
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Laisk, Agu, and Gerald E. Edwards. "Post-illumination CO2 Exchange and Light-induced CO2 Bursts during C4 Photosynthesis." Functional Plant Biology 24, no. 4 (1997): 517. http://dx.doi.org/10.1071/pp97002.
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Detailed kinetics of the post-illumination CO2 exchange, and darklight transients following post-illumination exchange, were measured in leaves of Sorghum bicolor, a NADP-malic enzyme (NADP-ME), and Amaranthus cruentus, a NAD-malic enzyme (NAD-ME) type C4 plant using a gas system that has a full-response time of 3.5 s. The amount of CO2 fixed in the dark (assimilatory charge, AC) was up to 200 µmol m-2 for A. cruentus and 350-450 µmol m-2 for S. bicolor. AC was at its maximum value at CO2 concentrations close to the inflection of the CO2 response curve, and decreased when photosynthesis was limited by low light intensity. The kinetics of post-illumination CO2 fixation indicate that the rate of carboxylation in the C4 cycle is limited by the supply of phosphoenolpyruvate. In A. cruentus, under saturating CO2 the post-illumination CO2 uptake was replaced by a burst (68 µmol m-2). In S. bicolor, the dark-light induction commenced with a rapid CO2 burst (less than 5 s) of 46 µmol m-2, followed by a gulp. The observed CO2 transients show imbalances in the C4 and C3 cycles. In S. bicolor the lack of a post-illumination burst, and the presence of the light- induced CO2 burst is taken as evidence for strict coupling of malate decarboxylation to PGA reduction in NADP-ME species; the opposite response in A. cruentus indicates the lack of strict coupling between the C4 and C3 cycle in NAD-ME species.
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Hatté, C., C. Gauthier, D. D. Rousseau, P. Antoine, M. Fuchs, F. Lagroix, S. B. Marković, O. Moine, and A. Sima. "Excursions to C<sub>4</sub> vegetation recorded in the Upper Pleistocene loess of Surduk (Northern Serbia): an organic isotope geochemistry study." Climate of the Past 9, no. 3 (May 3, 2013): 1001–14. http://dx.doi.org/10.5194/cp-9-1001-2013.
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Abstract. Loess sequences have been intensively studied to characterize past glacial climates of the 40–50° north and south latitude zones. Combining different approaches of sedimentology, magnetism, geochemistry, geochronology and malacology allows the general pattern of the climate and environment of the last interglacial–glacial cycle in Eurasia and America to be characterized. Previous studies performed in Europe have highlighted the predominance (if not the sole occurrence) of C3 vegetation. The presence of C3 plants suggests a regular distribution of precipitation along the year. Therefore, even if the mean annual precipitation remained very low during the most extensive glacial times, free water was available for more than 2 months per year. Contrarily, the δ13C record of Surduk (Serbia) clearly shows the occurrence and dominance of C4 plants during at least 4 episodes of the last glacial times at 28.0–26.0 kyr cal BP, 31.4–30.0 kyr cal BP, 53.4–44.5 kyr cal BP and 86.8–66.1 kyr. The C4 plant development is interpreted as a specific atmospheric circulation pattern that induces short and dry summer conditions. As possible explanation, we propose that during "C4 episodes", the Mediterranean Sea would have been under the combined influence of the following: (i) a strong meridional circulation unfavorable to water evaporation that reduced the Mediterranean precipitation on the Balkans; and (ii) a high positive North Atlantic Western Russian (NA/WR)-like atmospheric pattern that favored northerlies over westerlies and reduced Atlantic precipitation over the Balkans. This configuration would imply very dry summers that did not allow C3 plants to grow, thus supporting C4 development. The intra-"C4 episode" periods would have occurred under less drastic oceanic and atmospheric patterns that made the influence of westerlies on the Balkans possible.
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Lischiner, I. I., O. V. Malova, and A. L. Tarasov. "Conversion of Associated Petroleum Gas (APG) to Aromatic Hydrocarbons." Kataliz v promyshlennosti 18, no. 5 (September 18, 2018): 45–52. http://dx.doi.org/10.18412/1816-0387-2018-5-45-52.
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The studies demonstrated the possibility of effective catalytic synthesis of aromatic hydrocarbons over a zinc oxide modified zeolite catalyst during several reaction-regeneration cycles. The service cycle was shown to be no less than 130–150 hours – a good parameter for the high temperature process. Dependencies of the conversion of fatty C3–C4 constituents of APG on the reaction temperature and time were determined.
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Park, Joonho, Thomas W. Okita, and Gerald E. Edwards. "Expression profiling and proteomic analysis of isolated photosynthetic cells of the non-Kranz C4 species Bienertia sinuspersici." Functional Plant Biology 37, no. 1 (2010): 1. http://dx.doi.org/10.1071/fp09074.
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Bienertia sinuspersici Akhani represents one form of C4 photosynthesis that occurs without Kranz anatomy in family Chenopodiaceae. Analysis of transcript profiles and proteomics were made to gain information on this single-cell C4 photosynthetic mechanism. Chlorenchyma cells were isolated and purified from mature leaves. From these cells, a cDNA library was made from which sequences were obtained on 2385 clones using conventional methods. To obtain a protein profile, the multi dimensional protein identification technique was used, resulting in identification of 322 unique proteins in chlorenchyma cells. After analysing datasets from the EST library and proteomics, genes and proteins were classified into 23 and 17 categories according to types of biological processes, respectively. These include photosynthesis and photorespiration, other biosynthetic and metabolic processes, cell wall modification, defence response, DNA repair, electron transport, other cellular and developmental processes, protein folding, protein targeting, protein modification, proteolysis, redox and ion homeostasis, response to biotic and abiotic stresses, RNA modification, transcription, translation, transport and unknowns. Sequence and phylogenetic analyses were made of C4 cycle enzymes to characterise the relationship between homologues found in Bienertia with public gene sequences from other chenopods and representative C3 and C4 species from other families. Identified photosynthetic genes and proteins are discussed with respect to the proposed function of an NAD-ME type C4 cycle in this single-cell C4 system.
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Anwar, Md Parvez, A. K. M. Mominul Islam, Sabina Yeasmin, Md Harun Rashid, Abdul Shukor Juraimi, Sharif Ahmed, and Anil Shrestha. "Weeds and Their Responses to Management Efforts in A Changing Climate." Agronomy 11, no. 10 (September 25, 2021): 1921. http://dx.doi.org/10.3390/agronomy11101921.
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Crop production is a constant battle with weeds, in which weeds, generally, are victorious. Therefore, rather than channeling our efforts into the development of a “silver bullet” to control weeds, the focus should be on sustainable weed management in both natural- and agro-ecosystems. However, sustainable weed management can be a challenge in the context of global climate change. Over the past few decades, global climate change, mostly indicated by phenomena such as increased atmospheric temperature and elevated CO2 levels, is evident due to human activities and natural events. These phenomena also affect regional/local climate, resulting in significant influences on the agricultural systems of a particular region. Rising CO2 levels may give comparative advantages to C3 plants through increased photosynthesis, biomass production and yield, compared to C4 plants. Plants with C4 photosynthetic pathways, on the other hand, are likely to benefit more from rising global temperatures than C3 plants. Thus, the differential responses of C3 and C4 plants to climate change may alter crop–weed interactions and competition outcomes, most likely at the expense of the crop. Climate change will likely cause shifts in weed community compositions, their population dynamics, life cycle, phenology, and infestation pressure. Some weed species may go extinct, while some others may become more aggressive invaders. Weeds are, generally, colonizers and have some unique biological traits and ecological amplitudes that enable them to successfully dominate crops in a habitat with changed environmental conditions. Moreover, climate shifts, especially erratic rainfall and drought, may affect herbicide selectivity and efficacy or the success of bio-control agents resulting in an establishment of a mixed and complex population of C3 and C4 weed species adding to the complexity of weed management. Although elevated CO2 levels will stimulate the productivity of major C3 crops, most troublesome agricultural weeds will likely be more responsive to a rise in CO2 than crops, and thus may dominate the agro-ecosystem. It is predicted that, as temperature rises, the majority of the C4 weeds will flourish and will pose serious crop yield losses. Understanding and assessment of the impact of simultaneous changes in multiple climate factors and their complex interactions on crops and weeds are therefore necessary to formulate an adaptive weed management approach and build resilience. Moreover, strategic policies and strong actions need to be taken to reduce the root causes of CO2 and other greenhouse gas emissions to minimize the impact of climate change on weed biology and management.
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Soh, I. Peng Thomas, Maria Jannet Mogro, Ross A. Soo, Angela Pang, Chee Seng Tan, Benjamin Chuah, Ying Kiat Zee, et al. "The optimization of 5-fluorouracil (5FU) dose by pharmacokinetic (PK) monitoring in Asian patients with advanced-stage gastrointestinal (GI) cancer." Journal of Clinical Oncology 33, no. 3_suppl (January 20, 2015): 770. http://dx.doi.org/10.1200/jco.2015.33.3_suppl.770.
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770 Background: PK guided dose management and systemic plasma levels of 5FU have shown correlation with both reduced toxicity and improved efficacy. However, data for Asian patients are lacking. Levels are highly variable with doses based on body surface area. Methods: Area under the curve (AUC) was estimated using a nanoparticle immunoassay from Saladax Biomedical (My5-FU). Patients with GI cancers receiving de Gramont, FOLFIRI or mFOLFOX6 regimens had 5 PK sampling time points obtained (reduced to 2 samplings after first 15 patients). If target AUC (18-28 mg.h/L) was reached for 2 consecutive cycles, monitoring is performed for alternate cycles. With dose adjustments, PK sampling will be done in the next cycle. Results: 50 patients (33 males, 17 females) enrolled, with 349 PK samplings done, and 291 analyzable. 31 (62%) had mFOLFOX6, 18 (36%) FOLIRI and 1 (2%) de Gramont. Colorectal cancer (76%) and gastric cancer (12%) were the most common cancer types. Median AUC (35 evaluable) was 24.2 in C1, 23.65 in C2 (n=38), 20.6 in C3 (n=38) and 22 mg.hr/L in C4 (n=35). Proportion of patients achieving target AUC were 54.3%, 32%, 39.5% and 51% respectively and did not change significantly despite PK guided doses adjustments (C1 vs. C4 p=0.81, C2 vs. C3 p= 0.63, C2 vs. C4 p=0.085, C3 vs. C4 p=0.31). Higher than expected rate of G3/4 neutropenia (52%) and fewer mucositis (0%) and diarrhea (8%) were observed. Other toxicities (all grades) were fairly consistent with historical data. There were no inter-cycle differences in rates of toxicity, and no relationship with G3/4 toxicities and high AUC levels were observed. Correlation of response rates, efficacy with AUC were omitted due to heterogeneous tumor types. Conclusions: Contrary to past studies, PK guided 5FU did not result in a greater number of patients achieving target AUC in Asian patients. Furthermore, AUC levels of 5FU did not correlate with toxicity. Larger numbers are needed to confirm the clinical utility and benefit of PK guided 5FU in Asian patients. Clinical trial information: NCT00943137.
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Ningsih, Rahayuningsih. "PEMBELAJARAN KONTEKSTUAL DENGAN TEAMS GAMES TOURNAMENTS (TGT) UNTUK MENINGKATKAN HASIL BELAJAR." JURNAL PEMBELAJARAN FISIKA 9, no. 4 (December 28, 2020): 169. http://dx.doi.org/10.19184/jpf.v9i4.19551.
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Penelitian tindakan kelas dengan judul Pembelajaran Kontekstual dengan Teams Games Tournament (TGT) untuk Meningkatkan Hasil Belajar telah dilakukan pada bulan Agustus – Oktober 2017. Subjek penelitian siswa kelas IXA SMPN 3 Jember.Tujuan penelitian untuk meningkatkan hasil belajar siswa. Hasil penelitian menunjukkan bahwa penerapan pembelajaran kontekstual dengan metode belajar kooperatif TGT dapat meningkatkan hasil belajar siswa. Data hasil belajar meningkat dari dari siklus I (75%) ke siklus II (100%). Data hasil belajar berdasarkan sub ranah kognitif (C1, C2, C3, C4, C5) meningkat dari siklus I ke siklus II
Guru diharapkan menerapkan pembelajaran ini karena membantu siswa membangun kebiasaan berpikir positif dan memotivasi siswa lebih giat belajar.
Kata kunci: Pembelajaran kontekstual, TGT, hasil belajar
Classroom action research with the title of Contextual Learning using Teams Games Tournament (TGT) Cooperative Learning to Enhance Result have been conducted in Agustus – Oktober 2017. The source of data in this research were students of class IXA State Junior High School 3 Jember. The result of the research shows that the students’ result increased. Increased result observation the first cycle (75%) to the second cycle (100%). Increased result oof learning observation base on domain of cognitive from the first cycle (C1, C2, C3, C4, C5) to the second cycle. Teachers should implement this kind of teaching and learning activities because to help students build more positive thinking and motivate them to be more actively involved in the Science subject teaching and learning process
Key word: Contextual learning, TGT, result of learning
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Boyd, Christine N., Vincent R. Franceschi, Simon D. X. Chuong, Hossein Akhani, Olavi Kiirats, Monica Smith, and Gerald E. Edwards. "Flowers of Bienertia cycloptera and Suaeda aralocaspica (Chenopodiaceae) complete the life cycle performing single-cell C4 photosynthesis." Functional Plant Biology 34, no. 4 (2007): 268. http://dx.doi.org/10.1071/fp06283.
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Leaves and cotyledons of the terrestrial C4 plants, Bienertia cycloptera Bunge ex Boiss. and Suaeda aralocaspica (Bunge) Freitag & Schütze (Chenopodiaceae), accomplish C4 photosynthesis within individual chlorenchyma cells: each species having a unique means of intracellular spatial partitioning of biochemistry and organelles. In this study the chlorenchyma tissue in flowers and stems of these species was investigated. Flowers have an outer whorl of green tepals with a layer of chlorenchyma cells, which are located on the abaxial side, exposed to the atmosphere. Anatomical, immunocytochemical, western blots and starch analyses show that the chlorenchyma cells in tepals are specialised for performance of single-cell C4 photosynthesis like that in leaves. In the tepals of B. cycloptera, chlorenchyma cells have a distinctive central cytoplasmic compartment, with chloroplasts which contain Rubisco, separated by cytoplasmic channels from a peripheral chloroplast-containing compartment, with phosphoenolpyruvate carboxylase (PEPC) distributed throughout the cytoplasm. In the tepals of S. aralocaspica, chlorenchyma cells have chloroplasts polarised towards opposite ends of the cells. Rubisco is found in chloroplasts towards the proximal end of the cell and PEPC is found throughout the cytoplasm. Also, green stems of B. cycloptera have a single layer of the specialised C4 type chlorenchyma cells beneath the epidermis, and in stems of S. aralocaspica, chlorenchyma cells are scattered throughout the cortical tissue with chloroplasts around their periphery, typical of C3 type chlorenchyma. During reproductive development, green flowers become very conspicuous, and their photosynthesis is suggested to be important in completion of the life cycle of these single-cell C4 functioning species.
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Olszański, Romuald, Maciej Konarski, and Piotr Siermontowski. "Hyperbaric Oxygen Therapy (HBOT) as a Therapeutic Option for Patients with Atopic Dermatitis (AD) – Own Experiences and Literature Review." Polish Hyperbaric Research 60, no. 3 (October 26, 2017): 13–18. http://dx.doi.org/10.1515/phr-2017-0012.
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Abstract The paper discusses the treatment results of ten patients with severe atopic dermatitis (AD) who did not respond to standard pharmacotherapy and underwent hyperbaric oxygen therapy (HBOT). Each patient was subject to 10 oxygen exposures at pO2 2.5 ATA (~ 250 kPa) with the duration time of 60 minutes. In the period of implementation of the hyperbaric procedures the general treatment plan was suspended for all patients while maintaining typical local treatment. Clinical evaluation was performed in the study group as well as determination of levels of immunoglobulins: IgA, IgG, IgM and IgE and C3 and C4 complement. All patients indicated clinical improvement and a decreased IgE immunoglobulin and complement C3 level upon the completion of the exposure cycle. Taking into account the authors’ own observations and data from literature, an overall improvement in the clinical status and a decrease in the level of immunoglobulin E and C3 complement following a cycle of exposures may be indicative of an immunomodulating HBOT effect on AD, whereas hyperbaric oxygenation may constitute a therapeutic option for some patients with AD, especially those exhibiting a poor response to standard treatment.
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Ranjith, SA, FC Meinzer, MH Perry, and M. Thom. "Partitioning of Carboxylase Activity in Nitrogen-Stressed Sugarcane and Its Relationship to Bundle Sheath Leakiness to CO2, Photosynthesis and Carbon Isotope Discrimination." Functional Plant Biology 22, no. 6 (1995): 903. http://dx.doi.org/10.1071/pp9950903.
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We studied the effects of external nitrogen (N) supply on ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity, phosphoenolpyruvate carboxylase (PEPC) activity, leaf gas exchange, carbon isotope discrimination (Δ), and bundle sheath leakiness to CO2 (Φ) in two cultivars of the C4 grass, sugarcane (Saccharum spp. hybrid). In addition to reducing overall levels of carboxylase activity and therefore photosynthetic rates, reduced N supply altered the partitioning of carboxylase activity. Under long-term N stress (4 months) Rubisco activity decreased more than PEPC activity causing significant reductions in the Rubisco/PEPC activity ratio, a measure of the ratio of C3 to C4 cycle activity. Concurrent determinations of Δ for leaf dry matter and the prevailing ratio of intercellular to ambient partial pressure of CO2 (pI/pa) during leaf gas exchange suggested that the decreased partitioning of N to Rubisco activity under long-term N stress led to increased Φ and reduced photosynthetic efficiency. The two cultivars studied maintained similar PEPC activities but differed genetically in regard to investment of N in Rubisco. Greater investment of N in Rubisco was associated with higher rates of photosynthesis and growth at similar or slightly lower leaf N content, indicating that greater relative investment of N in Rubisco activity also led to higher N-use efficiency. The results suggest that regulation of the ratio of C3 to C4 pathway activity and its consequences for Φ may play a key role in the photosynthetic performance and growth of C4 grasses under both favourable and stressful conditions.
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Gruetter, Rolf, Elizabeth R. Seaquist, and Kâmil Ugurbil. "A mathematical model of compartmentalized neurotransmitter metabolism in the human brain." American Journal of Physiology-Endocrinology and Metabolism 281, no. 1 (July 1, 2001): E100—E112. http://dx.doi.org/10.1152/ajpendo.2001.281.1.e100.
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After administration of enriched [1-13C]glucose, the rate of 13C label incorporation into glutamate C4, C3, and C2, glutamine C4, C3, and C2, and aspartate C2 and C3 was simultaneously measured in six normal subjects by 13C NMR at 4 Tesla in 45-ml volumes encompassing the visual cortex. The resulting eight time courses were simultaneously fitted to a mathematical model. The rate of (neuronal) tricarboxylic acid cycle flux ( V PDH), 0.57 ± 0.06 μmol · g−1 · min−1, was comparable to the exchange rate between (mitochondrial) 2-oxoglutarate and (cytosolic) glutamate ( V x, 0.57 ± 0.19 μmol · g−1 · min−1), which may reflect to a large extent malate-aspartate shuttle activity. At rest, oxidative glucose consumption [CMRGlc(ox)] was 0.41 ± 0.03 μmol · g−1 · min−1, and (glial) pyruvate carboxylation ( V PC) was 0.09 ± 0.02 μmol · g−1 · min−1. The flux through glutamine synthetase ( V syn) was 0.26 ± 0.06 μmol · g−1 · min−1. A fraction of V syn was attributed to be from (neuronal) glutamate, and the corresponding rate of apparent glutamatergic neurotransmission ( V NT) was 0.17 ± 0.05 μmol · g−1 · min−1. The ratio [ V NT/CMRGlc(ox)] was 0.41 ± 0.14 and thus clearly different from a 1:1 stoichiometry, consistent with a significant fraction (∼90%) of ATP generated in astrocytes being oxidative. The study underlines the importance of assumptions made in modeling 13C labeling data in brain.
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Schwenen, Ludger, Dieter Komoßa, and Wolfgang Barz. "Metabolism and Degradation of Nicotinic Acid in Parsley (Petroselinum hortense) Cell Suspension Cultures and Seedlings." Zeitschrift für Naturforschung C 41, no. 1-2 (February 1, 1986): 148–57. http://dx.doi.org/10.1515/znc-1986-1-222.
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Abstract Application of [6-14C]-or [7-14C]nicotinic acid to parsley cell suspension cultures led to the accumulation of labelled nicotinamide mononucleotide, nicotinamide adenine dinucleotide, nicotinamide N-riboside, nicotinamide and nicotinic acid, indicating the operation of the pyridine nucleotide cycle in these cells. As main conjugates, nicotinic acid N-glucoside and nicotinic acid glucose ester were found. For nicotinic acid degradation the following sequence is suggested: nicotinic acid → 6-hydroxynicotinic acid → 2,5-dihydroxypyridine → a C4/C3 unit of unknown structure → CO2. In aseptically grown parsley seedlings nicotinic acid is also degraded to CO2
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Meinzer, Frederick C., and Jun Zhu. "Efficiency of C4 photosynthesis in Atriplex lentiformis under salinity stress." Functional Plant Biology 26, no. 1 (1999): 79. http://dx.doi.org/10.1071/pp98143.
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Photosynthetic gas exchange, carboxylase activities, and leaf tissue carbon isotope discrimination (Δ) were measured in Atriplex lentiformis (Torr.) Wats. (saltbush) plants grown in a glasshouse at five levels of salinity ranging from 0 to 600 mM NaCl. The net CO2 assimilation rate decreased by 64% from the lowest to the highest level of salinity imposed. The quantum yield for CO2 uptake was maximal in plants grown at 50 mM NaCl, and decreased sharply above and below this salinity level. The ratio of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity to that of phosphoenolpyruvate carboxylase (PEPC) decreased from 0.96 in plants grown at 0 mM NaCl to 0.37 in plants grown at 600 mM NaCl because PEPC activity on a leaf area basis increased linearly with increasing salinity, while Rubisco activity remained relatively constant. Compensatory changes in the leaf area/dry weight ratio and area-based leaf N content with increasing salinity suggested that the linear increase in PEPC activity was a passive response to increasing area-based leaf N content, whereas Rubisco activity on a leaf N basis actually dropped sharply. Relative leakage of CO2 from the bundle sheath, calculated from measurements of gas exchange and foliar Δ values, increased with increasing salinity in parallel with the decrease in the ratio of C3 cycle activity relative to C4 cycle activity. These results suggest that salinity stress diminished the inherent efficiency of the C4 CO2 concentrating mechanism in addition to reducing net CO2 uptake.
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Arrivault, Stéphanie, Thiago Alexandre Moraes, Toshihiro Obata, David B. Medeiros, Alisdair R. Fernie, Alix Boulouis, Martha Ludwig, et al. "Metabolite profiles reveal interspecific variation in operation of the Calvin–Benson cycle in both C4 and C3 plants." Journal of Experimental Botany 70, no. 6 (February 18, 2019): 1843–58. http://dx.doi.org/10.1093/jxb/erz051.
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Monson, R. K., J. A. Teeri, M. S. B. Ku, J. Gurevitch, L. J. Mets, and S. Dudley. "Carbon-isotope discrimination by leaves of Flaveria species exhibiting different amounts of C3-and C4-cycle co-function." Planta 174, no. 2 (May 1988): 145–51. http://dx.doi.org/10.1007/bf00394765.
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Zhou, Yong, Thomas W. Boutton, and X. Ben Wu. "A Three-Dimensional Assessment of Soil δ13C in a Subtropical Savanna: Implications for Vegetation Change and Soil Carbon Dynamics." Soil Systems 3, no. 4 (November 13, 2019): 73. http://dx.doi.org/10.3390/soilsystems3040073.
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Tree/shrub encroachment into drylands is a geographically widespread vegetation change that often modifies soil organic carbon (SOC) storage and dynamics, and represents an important yet uncertain aspect of the global carbon (C) cycle. We quantified spatial patterns of soil δ13C to 1.2 m depth in a subtropical savanna to evaluate the magnitude and timing of woody encroachment, and its impacts on SOC dynamics. Woody encroachment dramatically altered soil δ13C spatial patterns throughout the profile; values were lowest in the interiors of woody patches, increased towards the peripheries of those patches, and reached highest values in the surrounding grasslands. Soil δ13C and 14C revealed this landscape was once dominated by C4 grasses. However, a rapid vegetation change occurred during the past 100–200 years, characterized by (1) the formation and expansion of woody patches across this landscape, and (2) increased C3 forb abundance within remnant grasslands. Tree/shrub encroachment has substantially increased SOC and the proportion of new SOC derived from C3 plants in the SOC pool. These findings support the emerging perspective that vegetation in many dryland ecosystems is undergoing dramatic and rapid increases in SOC storage, with implications for the C cycle at regional and global scales.
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Novara, A., J. Rühl, T. La Mantia, L. Gristina, S. La Bella, and T. Tuttolomondo. "Litter contribution to soil organic carbon in the processes of agriculture abandon." Solid Earth 6, no. 2 (April 24, 2015): 425–32. http://dx.doi.org/10.5194/se-6-425-2015.
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Abstract. The mechanisms of litter decomposition, translocation and stabilization into soil layers are fundamental processes in the functioning of the ecosystem, as they regulate the cycle of soil organic matter (SOM) and CO2 emission into the atmosphere. In this study the contribution of litters of different stages of Mediterranean secondary succession on carbon sequestration was investigated, analyzing the role of earthworms in the translocation of SOM into the soil profile. For this purpose the δ13C difference between meadow C4-C soil and C3-C litter was used in a field experiment. Four undisturbed litters of different stages of succession (45, 70, 100 and 120 since agriculture abandon) were collected and placed on the top of isolated C4 soil cores. The litter contribution to C stock was affected by plant species and it increased with the age of the stage of secondary succession. One year after the litter position, the soil organic carbon increased up to 40% in comparison to soils not treated with litter after 120 years of abandon. The new carbon derived from C3 litter was decomposed and transferred into soil profile thanks to earthworms and the leaching of dissolved organic carbon. After 1 year the carbon increase attributed to earthworm activity was 6 and 13% in the soils under litter of fields abandoned for 120 and 45 years, respectively.
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Wang, Yingxue, Bridgette A. Christopher, Kirkland A. Wilson, Deborah Muoio, Robert W. McGarrah, Henri Brunengraber, and Guo-Fang Zhang. "Propionate-induced changes in cardiac metabolism, notably CoA trapping, are not altered by l-carnitine." American Journal of Physiology-Endocrinology and Metabolism 315, no. 4 (October 1, 2018): E622—E633. http://dx.doi.org/10.1152/ajpendo.00081.2018.
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High concentrations of propionate and its metabolites are found in several diseases that are often associated with the development of cardiac dysfunction, such as obesity, diabetes, propionic acidemia, and methylmalonic acidemia. In the present work, we employed a stable isotope-based metabolic flux approach to understand propionate-mediated perturbation of cardiac energy metabolism. Propionate led to accumulation of propionyl-CoA (increased by ~101-fold) and methylmalonyl-CoA (increased by 36-fold). This accumulation caused significant mitochondrial CoA trapping and inhibited fatty acid oxidation. The reduced energy contribution from fatty acid oxidation was associated with increased glucose oxidation. The enhanced anaplerosis of propionate and CoA trapping altered the pool sizes of tricarboxylic acid cycle (TCA) metabolites. In addition to being an anaplerotic substrate, the accumulation of proprionate-derived malate increased the recycling of malate to pyruvate and acetyl-CoA, which can enter the TCA for energy production. Supplementation of 3 mM l-carnitine did not relieve CoA trapping and did not reverse the propionate-mediated fuel switch. This is due to new findings that the heart appears to lack the specific enzyme catalyzing the conversion of short-chain (C3 and C4) dicarboxylyl-CoAs to dicarboxylylcarnitines. The discovery of this work warrants further investigation on the relevance of dicarboxylylcarnitines, especially C3 and C4 dicarboxylylcarnitines, in cardiac conditions such as heart failure.
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Callahan, Ann M., and Carole L. Bassett. "271 EXPRESSION OF NADP-MALIC ENZYME RNA LEVELS IN RIPENING PEACH FRUIT." HortScience 29, no. 5 (May 1994): 468f—468. http://dx.doi.org/10.21273/hortsci.29.5.468f.
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NADP-dependent Malic Enzyme (NADP-ME, EC 1.1.1.40) catalyzes the decarboxylation of malate, resulting in the release of CO2. In C3 plants the enzyme does not contribute CO2 directly to photosynthesis. Rather, it is associated with the supplemental synthesis of glycolytic and Krebs Cycle intermediates, although it may also be involved in regulating intracellular pH. NADP-ME activity increases during ripening of several fruits e.g. tomato and apple, usually in association with increased respiration of the developing fruit. We examined expression of NADP-ME during ripening in peach using a cDNA probe derived from F. trinervia (C4 dicot). The probe hybridized to a single RNA species of the predicted size and was low in abundance as expected for a C3 NADP-ME. As fruit matured, the RNA levels increased to a maximum around 133-140 days after bloom (fully ripe). NADP-ME RNA was not detectable from leaves isolated at the same time.
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Hunt, Stephen, Alison M. Smith, and Harold W. Woolhouse. "Evidence for a light-dependent system for reassimilation of photorespiratory CO2, which does not include a C4 cycle, in the C3?C4 intermediate species Moricandia arvensis." Planta 171, no. 2 (June 1987): 227–34. http://dx.doi.org/10.1007/bf00391098.
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Fury, M. G., J. Larkin, S. R. Gerst, P. Sabbatini, J. Konner, M. Orlando, D. F. Tai, T. Goss, C. Aghajanian, and M. L. Hensley. "Phase I study of pemetrexed (P) plus gemcitabine (G) in advanced solid tumors (ST)." Journal of Clinical Oncology 25, no. 18_suppl (June 20, 2007): 14055. http://dx.doi.org/10.1200/jco.2007.25.18_suppl.14055.
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14055 Background: P is active in multiple ST types, and preclinical data support P synergy with G. Methods: Eligible advanced ST patients (pts) with no prior P or G, no prior radiotherapy (RT) to ≡ 25% of the marrow, Karnofsky Performance Status ≡ 70%, and adequate organ function enrolled in cohorts (C) of 3, expanding to 6 if dose-limiting toxicity (DLT) occurred. P was given at 300 (C1), 400 (C2), 500 (C3) or 600 (C4) mg/m2 followed by G at 1500 mg/m2 q 14 days (d) without granulocyte-colony stimulating factor. Vitamin B12 and folate supplementation were given. Response was assessed by RECIST Results: 29 pts (median number prior regimens 2, range 1–5; 66% with prior RT) enrolled and are evaluable for safety; 23 are evaluable for response. There were no DLTs in C1. One pt in C2 was replaced after 1 cycle for progression of disease (PD). Among the next 6 pts, 2 had DLTs (1 G3 thrombocytopenia [TP] treatment delay; 1 neutropenic fever [NF]). C2-R (C2, Revised) re-opened after amendment permitting ≡ 2 prior cytotoxic regimens, no history of brain metastases/brain RT. C2-R enrolled 8 pts with 1 DLT (G3 TP with treatment delay) and 2 pts replaced (1 early PD, 1 no documented duration of neutropenia [NP]). C3 had 0/3 pts with DLT. C4 had 2/3 pts with DLTs (1 G4 hyponatremia; 1 herpes zoster-related treatment delay). C3 has been expanded to 5 of 6 planned patients, one with DLT (NF, G4 TP). Toxicities per cycle (n= 189 cycles, 29 patients): include NP-G3 (23%), G4 (14%); TP-G3 (2%); WBC-G3 (30%), G4 (4%); lymphopenia-G3 (11%), Hgb-G3 (4%); G3-NF (1%). 3/23 (13%) had objective partial responses (2 head and neck squamous cell cancer, HNSCC; 1 nasopharyngeal cancer, NPC), 4 stable disease (SD), 16 PD. (1 pt, no measurable disease at baseline; 5 pts, too early for response assesment). Conclusions: G + P is well-tolerated, and yields objective responses in HNSCC and NPC. C3 (P 500 mg/m2 + G 1500 mg/m2 q 14 d) was the phase II recommended dose in another phase I study of this regimen (Melemed ASCO 2005). Our final results will be available for ASCO 2007. No significant financial relationships to disclose.
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Zuanon, J. A. S., A. C. Pezzato, C. Ducatti, M. M. Barros, L. E. Pezzato, and J. R. S. Passos. "Muscle δ13C change in Nile tilapia (Oreochromis niloticus) fingerlings fed on C3-or C4-cycle plants grain-based diets." Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 147, no. 3 (July 2007): 761–65. http://dx.doi.org/10.1016/j.cbpa.2006.08.038.
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Rosiñol, Laura, Albert Oriol, Ana Isabel Teruel, Dolores Hernández, M. Jesús Blanchard, Javier De La Rubia, Miquel Granell, et al. "Kinetics of Response to Bortezomib/Thalidomide/Dexamethasone (VTD) in Multiple Myeloma: Implications for the Choice and Design of Pretransplantation Induction Regimens." Blood 124, no. 21 (December 6, 2014): 2108. http://dx.doi.org/10.1182/blood.v124.21.2108.2108.
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Abstract Background: Autologous stem-cell transplantation (ASCT) is the standard of care for younger patients with multiple myeloma (MM). The degree of tumor reduction after ASCT is the crucial factor associated with a prolonged PFS and OS, being the M-protein decrease at the time of transplant the most important predictor of residual disease after ASCT. While there is an agreement that bortezomib and dexamethasone associated to a third drug is the induction of choice, which should be the third drug (thalidomide, lenalidomide, doxorubicin or cyclophosphamide) and the optimal number of cycles remain unknown. The results of phase 3 PETHEMA study GEM05menos65 showing a CR rate of 35% increasing overtime during the 6 induction cycles of VTD (Rosiñol et al, Blood 2012) prompted us to study the kinetics of response to VTD and TD in this study and in similar historic data with the VD regimen in phase 2 PETHEMA VELCA/DEXA trial (Rosiñol et al, JCO 2007). Objective: To study the kinetics of response by cycle during the 6 cycles of induction with VTD, TD and VD using a random effects model methodology. Patients and Methods: In GEM05menos65 study patients were randomized to receive 6 induction cycles of either VTD or TD followed by ASCT. One hundred and thirteen patients were treated with TD (thalidomide 200 mg daily; dexamethasone 40 mg on days 1-4 and 9-12) and 122 with VTD (TD at identical doses plus bortezomib 1.3 mg/m2 on days 1, 4, 8 and 11) (Rosiñol et al, Blood 2012) and had complete data set for this analysis. In VELCA/DEXA study 40 patients received 6 induction cycles of bortezomib and dexamethasone on an alternating basis (Rosiñol et al, JCO 2007). Linear random effects models were employed to analyze the tumor response kinetics using the absolute decrease value of the serum M-protein after each cycle. Because the nonlinearity in the change of the M-protein overtime, a piecewise linear model was used to estimate mean changes in M-protein in each of the 6 cycles. Results: Three different comparisons were made: 1) the decrease of the M-protein by cycle within each treatment group, 2) the total M-protein decrease at the end of induction with VTD compared to TD and VD and 3) the decrease by cycle comparing VTD vs TD and VTD vs VD. Concerning the M-protein decrease by cycle within each arm, statistically significant decreases versus the previous cycle were observed in the first 5 cycles of VTD, the first 3 of TD and the first 4 of VD. The serum M-protein reduction at the end of the 6 induction cycles was significantly higher with VTD when compared with TD (p<0.0001) and VD (p<0.0001). Finally, when comparing the serum M-protein decrease between VTD and TD by cycle, the M-protein reduction was significantly higher with VTD in the first 5 cycles and the same analysis between VTD and VD showed that the serum M-protein decrease was significantly higher with VTD in the first 3 cycles (Tables 1 and 2). Conclusions: In the cycle by cycle analysis VTD continued to improve M-protein reduction significantly in the first 5 cycles. When compared with TD and VD, the M-protein decrease at the end of induction was significantly higher with VTD. Furthermore, in the cycle by cycle comparison there was a significantly higher efficacy of VTD over TD in the first 5 cycles and over VD in the first 3 cycles. Our results suggest a synergistic rather than only an additive effect between thalidomide and bortezomib supporting the use of an IMiD as the drug of choice to be combined with bortezomib and dexamethasone. Finally, our study supports an induction period beyond 3 or 4 cycles when using a bortezomib/IMiD regimen in order to maximize the induction efficacy. Table 1. Comparison between VTD versus TD by cycles overtime. Serum M-protein (g/dl) Change (VTH-TH) Estimate SE 95% CI P-value C1 – Baseline -3.0747 0.3461 (-3.7539, -2.3954) <.0001 C2 – C1 -1.1343 0.1294 (-1.3883, -0.8802) <.0001 C3 – C2 -0.4474 0.09586 (-0.6356, -0.2593) <.0001 C4 – C3 -0.2140 0.08224 (-0.3753, -0.05257) 0.0094 C5 – C4 -0.1339 0.07550 (-0.2821, -0.01428) 0.0765 C6 – C5 0.01862 0.05395 (-0.08725, 0.1245) 0.7300 Table 2. Comparison between VTD versus VD by cycles overtime. Serum M-protein (g/dl) Change (VTH-VD) Estimate SE 95% CI P-value C1 – Baseline -3.1553 0.2243 (-3.5957, -2.7150) <.0001 C2 – C1 -1.3748 0.2279 (-1.8223, -0.9272) <.0001 C3 – C2 -0.4266 0.2354 (-0.8887, 0.03552) 0.0703 C4 – C3 -0.05473 0.2439 (-0.5337, 0.4242) 0.8225 C5 – C4 -0.02217 0.2530 (-0.5189, 0.4745) 0.9302 C6 – C5 0.06493 0.2908 (-0.5060, 0.6358) 0.8234 Disclosures Rosiñol: Janssen: Honoraria; Celgene: Honoraria. Oriol:Janssen: Honoraria; Celgene: Honoraria. De La Rubia:Janssen: Honoraria; Celgene: Honoraria. Gutierrez:Janssen: Honoraria; Celgene: Honoraria. Mateos:Janssen: Honoraria; Celgene: Honoraria. Martinez-Lopez:Janssen: Honoraria; Celgene: Honoraria. Alegre:Janssen: Honoraria; Celgene: Honoraria. Feng:Janssen: Employment. van de Velde:Janssen: Employment. Lahuerta:Janssen: Honoraria; Celgene: Honoraria. San Miguel:Janssen: Honoraria; Celgene: Honoraria. Blade:Janssen: Honoraria; Celgene: Honoraria.
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Wagenmakers, A. J., N. J. Rehrer, F. Brouns, W. H. Saris, and D. Halliday. "Breath 13CO2 background enrichment during exercise: diet-related differences between Europe and America." Journal of Applied Physiology 74, no. 5 (May 1, 1993): 2353–57. http://dx.doi.org/10.1152/jappl.1993.74.5.2353.
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A traditional North American diet contains a high percentage of carbohydrates (CHO) derived from C4 plants (maize, sugar cane), whereas a European diet contains primarily CHO derived from C3 plants (potato, sugar beet). The natural 13C enrichment of the first type of CHO is higher than that of the latter type. 13CO2 production from orally ingested C4 plant-derived CHO can, therefore, be used to quantify oxidation rates of orally ingested CHO at rest and during exercise. Recently it has been shown that oxidation rates assessed this way in North Americans should be corrected for an increase in breath background 13CO2 during exercise. We hypothesized that the indicated difference in metabolic origin of CHO would imply that no such correction is required for subjects on a European diet. We therefore studied changes from rest in breath 13CO2 enrichment in Dutch volunteers during cycle ergometry at 65% maximal work load (experiment 1, 2h, 6 subjects) and 70% maximal oxygen uptake (experiment 2, 90 min, 8 subjects) while ingesting water (experiments 1 and 2) and potato starch-derived glucose (experiment 2). Experiment 1 was done before and after careful instruction of the subjects to refrain from nutrient sources potentially containing CHO of C4 metabolic origin. No significant changes from rest 13CO2 enrichment were observed in tests with water and potato-derived glucose ingestion in subjects who excluded CHO of C4 metabolic origin from their diet.
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Shirasawa-Seo, Naomi, Yoshitaka Sano, Shigeo Nakamura, Taka Murakami, Shigemi Seo, Yuko Ohashi, Yoshifumi Hashimoto, and Tsuguo Matsumoto. "Characteristics of the promoters derived from the single-stranded DNA components of Milk vetch dwarf virus in transgenic tobacco." Journal of General Virology 86, no. 6 (June 1, 2005): 1851–60. http://dx.doi.org/10.1099/vir.0.80790-0.
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Predicted promoter regions of Milk vetch dwarf virus (MDV) components (C1–C11) were isolated and fused with a β-glucuronidase (GUS) reporter gene and the characteristics of the promoters were examined. In transgenic tobacco calli, promoters of MDV C4 (encoding a cell-cycle link protein), C5 and C7 (both encoding unknown proteins), C6 (encoding a nuclear-shuttle protein) and C8 (encoding a movement protein) generated a stronger level of GUS expression than the Cauliflower mosaic virus 35S RNA promoter (P35S). In leaves of transgenic tobacco plants, the promoters of C5 and C8 conferred a level of GUS activity comparable to that of P35S. Histochemical GUS analysis showed that the promoters of C4–C9, the latter encoding a capsid protein, were active in phloem and meristematic tissue. The promoter of C8 was also active in mesophyll and cortex cell types. A low level of activity was found for the promoters of C11, which encodes a master replication-initiator protein (Rep), and C1, C2, C3 and C10, which encode additional Reps, in both transgenic tobacco calli and plants.
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Mendoza, Mariano, Arnoldo Oyervides, Luis Latournerie, and Humberto De León. "selección recurrente de maíz para el trópico húmedo." Agronomía Mesoamericana 11, no. 1 (January 1, 2006): 89. http://dx.doi.org/10.15517/am.v11i1.17357.
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The objective of this study was to evaluate the genetic advancement of four cycles of selection obtained by recurrent selection family full-sib (RSFFS) with pedigree in the 24 Population. Treatments were divided in cycles (C0, C1, C2, C3 y C4) and three controls. This research was carried out in two localities Villa Ursulo Galván and Rinconada at the State of Veracruz, Mexico. A complete randomized block design was utilized with 10 repetitions. The results obtained were an increased 3.09% in yield, an increased in the number of ears per plant 4.92%, a lesser the stalk lodging 6.06%, and an improvement for husk cover of 12.05%. The gain for linear regression was 282.2 kg/ha/cycle is the same a 5.54%.
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Harper, Anna B., Peter M. Cox, Pierre Friedlingstein, Andy J. Wiltshire, Chris D. Jones, Stephen Sitch, Lina M. Mercado, et al. "Improved representation of plant functional types and physiology in the Joint UK Land Environment Simulator (JULES v4.2) using plant trait information." Geoscientific Model Development 9, no. 7 (July 22, 2016): 2415–40. http://dx.doi.org/10.5194/gmd-9-2415-2016.
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Abstract. Dynamic global vegetation models are used to predict the response of vegetation to climate change. They are essential for planning ecosystem management, understanding carbon cycle–climate feedbacks, and evaluating the potential impacts of climate change on global ecosystems. JULES (the Joint UK Land Environment Simulator) represents terrestrial processes in the UK Hadley Centre family of models and in the first generation UK Earth System Model. Previously, JULES represented five plant functional types (PFTs): broadleaf trees, needle-leaf trees, C3 and C4 grasses, and shrubs. This study addresses three developments in JULES. First, trees and shrubs were split into deciduous and evergreen PFTs to better represent the range of leaf life spans and metabolic capacities that exists in nature. Second, we distinguished between temperate and tropical broadleaf evergreen trees. These first two changes result in a new set of nine PFTs: tropical and temperate broadleaf evergreen trees, broadleaf deciduous trees, needle-leaf evergreen and deciduous trees, C3 and C4 grasses, and evergreen and deciduous shrubs. Third, using data from the TRY database, we updated the relationship between leaf nitrogen and the maximum rate of carboxylation of Rubisco (Vcmax), and updated the leaf turnover and growth rates to include a trade-off between leaf life span and leaf mass per unit area.Overall, the simulation of gross and net primary productivity (GPP and NPP, respectively) is improved with the nine PFTs when compared to FLUXNET sites, a global GPP data set based on FLUXNET, and MODIS NPP. Compared to the standard five PFTs, the new nine PFTs simulate a higher GPP and NPP, with the exception of C3 grasses in cold environments and C4 grasses that were previously over-productive. On a biome scale, GPP is improved for all eight biomes evaluated and NPP is improved for most biomes – the exceptions being the tropical forests, savannahs, and extratropical mixed forests where simulated NPP is too high. With the new PFTs, the global present-day GPP and NPP are 128 and 62 Pg C year−1, respectively. We conclude that the inclusion of trait-based data and the evergreen/deciduous distinction has substantially improved productivity fluxes in JULES, in particular the representation of GPP. These developments increase the realism of JULES, enabling higher confidence in simulations of vegetation dynamics and carbon storage.
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Klumpp, K., J. F. Soussana, and R. Falcimagne. "Long-term steady state <sup>13</sup>C labelling to investigate carbon turnover in plant soil systems." Biogeosciences Discussions 4, no. 2 (March 7, 2007): 797–821. http://dx.doi.org/10.5194/bgd-4-797-2007.
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Abstract. We have set up a facility allowing steady state 13CO2 labeling of short stature vegetation (12 m2) for several years. 13C labelling is obtained by scrubbing the CO2 from outdoors air with a self-regenerating molecular sieve and by replacing it with 13C depleted (−34.7±0.03‰) fossil-fuel derived CO2 The facility, which comprises 16 replicate mesocosms, allows tracing the fate of photosynthetic carbon in plant-soil systems in natural light and at outdoors temperature. This method was applied during 2 yrs to temperate grassland monoliths (0.5×0.5×0.4 m) sampled in a long term grazing experiment. During daytime, the canopy enclosure in each mesocosm was supplied in an open flow (0.67–0.88 volume per minute) with modified air (43% scrubbed air and 57% cooled and humidified ambient air) at mean CO2 concentration of 425 µmol mol−1 and δ13C of −21.5±0.27‰. Above and belowground CO2 fluxes were continuously monitored. The difference in δ13C between the CO2 at the outlet and at the inlet of each canopy enclosure was not significant (−0.35±0.39‰). Due to mixing with outdoors air, the CO2 concentration at enclosure inlet followed a seasonal cycle, often found in urban areas, where δ13C of CO2 is lower in winter than in summer. Mature C3 grass leaves were sampled monthly in each mesocosm, as well as leave from pot-grown control C4 (Paspalum dilatatum). The mean δ13C of fully labelled C3 and C4 leaves reached −41.4±0.67 and −28.7±0.39‰ respectively. On average, the labelling reduced by 12.7‰ the δ13C of C3 grass leaves. The isotope mass balance technique was used to calculate the fraction of "new" C in the soil organic matter (SOM) above 0.2 mm. A first order exponential decay model fitted to "old" C data showed that reducing aboveground disturbance by cutting increased from 22 to 31 months the mean residence time of belowground organic C (>0.2 mm) in the top soil.