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Phytochrome, Carbon Sensing, Metabolism, and Plant Growth Plasticity.
Krahmer, J, Ganpudi, A, Abbas, A, Romanowski, A, Halliday, KJ
Plant physiology. 2018;(2):1039-1048
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Abstract
Phytochrome signaling controls biomass accumulation, growth plasticity, and metabolism.
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Combined use of a nanocarbon suspension and 99mTc-MIBI for the intra-operative localization of the parathyroid glands.
Chen, J, Zhou, Q, Feng, J, Wang, J
American journal of otolaryngology. 2018;(2):138-141
Abstract
OBJECTIVE To investigate the combined use of a nanocarbon (NC) suspension and low-dose 99mTc-MIBI for parathyroid localization during surgery in patients with secondary hyperparathyroidism (sHPT). METHODS Between March 2010 and September 2015, 40 patients with sHPT were enrolled in this study and were randomized to receive either low-dose 99mTc-MIBI+NC (group I) or low-dose 99mTc-MIBI (group II). Pre- and post-operative serum levels of intact PTH (iPTH), calcium and phosphorus between groups were compared and the intra-operative radioactive counts of the parathyroid glands were measured. RESULTS The post-operative iPTH level was significantly lower in patients of group I (24.2±31ng/L) than in those of group II (106±155ng/L) (P=0.03) while there were no significant differences in intra-operative parathyroid gland radioactive counts between the groups. The duration of the surgical procedure was shorter for patients of group I than patients of group II. There were no serious intra-operative or post-operative complications. CONCLUSION The combined use of an NC suspension and 99mTc-MIBI for patients with sHPT is strongly recommended for the localization of parathyroid glands during surgery and is likely to improve clinical outcomes for patients.
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One-Carbon Metabolism: Biological Players in Epithelial Ovarian Cancer.
Rizzo, A, Napoli, A, Roggiani, F, Tomassetti, A, Bagnoli, M, Mezzanzanica, D
International journal of molecular sciences. 2018;(7)
Abstract
Metabolism is deeply involved in cell behavior and homeostasis maintenance, with metabolites acting as molecular intermediates to modulate cellular functions. In particular, one-carbon metabolism is a key biochemical pathway necessary to provide carbon units required for critical processes, including nucleotide biosynthesis, epigenetic methylation, and cell redox-status regulation. It is, therefore, not surprising that alterations in this pathway may acquire fundamental importance in cancer onset and progression. Two of the major actors in one-carbon metabolism, folate and choline, play a key role in the pathobiology of epithelial ovarian cancer (EOC), the deadliest gynecological malignancy. EOC is characterized by a cholinic phenotype sustained via increased activity of choline kinase alpha, and via membrane overexpression of the alpha isoform of the folate receptor (FRα), both of which are known to contribute to generating regulatory signals that support EOC cell aggressiveness and proliferation. Here, we describe in detail the main biological processes associated with one-carbon metabolism, and the current knowledge about its role in EOC. Moreover, since the cholinic phenotype and FRα overexpression are unique properties of tumor cells, but not of normal cells, they can be considered attractive targets for the development of therapeutic approaches.
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Synthetic biology approaches to access renewable carbon source utilization in Corynebacterium glutamicum.
Zhao, N, Qian, L, Luo, G, Zheng, S
Applied microbiology and biotechnology. 2018;(22):9517-9529
Abstract
Corynebacterium glutamicum (C. glutamicum), an important industrial workhorse, is capable of efficiently producing a variety of value-added chemicals and fuels beyond amino acids. C. glutamicum has a broad natural substrate spectrum and can simultaneously utilize various carbon sources in blends. The substrate spectrum of C. glutamicum has been further extended by detailed knowledge of carbon core metabolism and well-established genetic tools and engineering strategies. At present, many pathways have been successfully engineered in C. glutamicum for access to alternative renewable sources to produce natural or non-natural products, making C. glutamicum a promising and favorable microbial cell factory. In this review, we mainly focus on synthetic biology and metabolic engineering strategies for developing synthetic strains that grow on renewable sources to produce the target products. At the same time, we also explore the promotion and future challenges of existing synthetic biology platforms for industrial platform microorganism metabolic engineering efforts.
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Critical steps in carbon metabolism affecting lipid accumulation and their regulation in oleaginous microorganisms.
Dourou, M, Aggeli, D, Papanikolaou, S, Aggelis, G
Applied microbiology and biotechnology. 2018;(6):2509-2523
Abstract
Oleaginous microorganisms are able to convert numerous agro-industrial and municipal wastes into storage lipids (single cell oil (SCO)) and are therefore considered as potential biofuel producers. While from an environmental and technological point of view the idea to convert waste materials into fuels is very attractive, the production cost of SCO is not currently competitive to that of conventional oils due to the low productivity of oleaginous microorganisms in combination with the high fermentation cost. Current strategies used to optimize the lipid-accumulating capacity of oleaginous microorganisms include the overexpression of genes encoding for key enzymes implicated in fatty acid and triacylglycerol synthesis, such as ATP-dependent citrate lyase, acetyl-CoA carboxylase, malic enzyme, proteins of the fatty acid synthase complex, glycerol 3-phosphate dehydrogenase and various acyltransferases, and/or the inactivation of genes encoding for enzymes implicated in storage lipid catabolism, such as lipases and acyl-CoA oxidases. Furthermore, blocking, even partially, pathways competitive to lipid biosynthesis (e.g., those involved in the accumulation of storage polysaccharide or organic acid and polyol excretion) can also increase lipid-accumulating ability in oleaginous microorganisms. Methodologies, such as adaptive laboratory evolution, can be included in existing workflows for the generation of strains with improved lipid accumulation capacity. In our opinion, efforts should be focused in the construction of strains with high carbon uptake rates and a reprogrammed coordination of the individual parts of the oleaginous machinery that maximizes carbon flux towards lipogenesis.
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Root hairs increase rhizosphere extension and carbon input to soil.
Holz, M, Zarebanadkouki, M, Kuzyakov, Y, Pausch, J, Carminati, A
Annals of botany. 2018;(1):61-69
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Abstract
BACKGROUND AND AIMS Although it is commonly accepted that root exudation enhances plant-microbial interactions in the rhizosphere, experimental data on the spatial distribution of exudates are scarce. Our hypothesis was that root hairs exude organic substances to enlarge the rhizosphere farther from the root surface. METHODS Barley (Hordeum vulgare 'Pallas' - wild type) and its root-hairless mutant (brb) were grown in rhizoboxes and labelled with 14CO2. A filter paper was placed on the soil surface to capture, image and quantify root exudates. KEY RESULTS Plants with root hairs allocated more carbon (C) to roots (wild type: 13 %; brb: 8 % of assimilated 14C) and to rhizosheaths (wild type: 1.2 %; brb: 0.2 %), while hairless plants allocated more C to shoots (wild type: 65 %; brb: 75 %). Root hairs increased the radial rhizosphere extension three-fold, from 0.5 to 1.5 mm. Total exudation on filter paper was three times greater for wild type plants compared to the hairless mutant. CONCLUSION Root hairs increase exudation and spatial rhizosphere extension, which probably enhance rhizosphere interactions and nutrient cycling in larger soil volumes. Root hairs may therefore be beneficial to plants under nutrient-limiting conditions. The greater C allocation below ground in the presence of root hairs may additionally foster C sequestration.
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Candidate genes linking maternal nutrient exposure to offspring health via DNA methylation: a review of existing evidence in humans with specific focus on one-carbon metabolism.
James, P, Sajjadi, S, Tomar, AS, Saffari, A, Fall, CHD, Prentice, AM, Shrestha, S, Issarapu, P, Yadav, DK, Kaur, L, et al
International journal of epidemiology. 2018;(6):1910-1937
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Abstract
BACKGROUND Mounting evidence suggests that nutritional exposures during pregnancy influence the fetal epigenome, and that these epigenetic changes can persist postnatally, with implications for disease risk across the life course. METHODS We review human intergenerational studies using a three-part search strategy. Search 1 investigates associations between preconceptional or pregnancy nutritional exposures, focusing on one-carbon metabolism, and offspring DNA methylation. Search 2 considers associations between offspring DNA methylation at genes found in the first search and growth-related, cardiometabolic and cognitive outcomes. Search 3 isolates those studies explicitly linking maternal nutritional exposure to offspring phenotype via DNA methylation. Finally, we compile all candidate genes and regions of interest identified in the searches and describe their genomic locations, annotations and coverage on the Illumina Infinium Methylation beadchip arrays. RESULTS We summarize findings from the 34 studies found in the first search, the 31 studies found in the second search and the eight studies found in the third search. We provide details of all regions of interest within 45 genes captured by this review. CONCLUSIONS Many studies have investigated imprinted genes as priority loci, but with the adoption of microarray-based platforms other candidate genes and gene classes are now emerging. Despite a wealth of information, the current literature is characterized by heterogeneous exposures and outcomes, and mostly comprise observational associations that are frequently underpowered. The synthesis of current knowledge provided by this review identifies research needs on the pathway to developing possible early life interventions to optimize lifelong health.
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Is there computational support for an unprotonated carbon in the E4 state of nitrogenase?
Siegbahn, PEM
Journal of computational chemistry. 2018;(12):743-747
Abstract
In the key enzyme for nitrogen fixation in nature, nitrogenase, the active site has a metal cluster with seven irons and one molybdenum bound by bridging sulfurs. Surprisingly, there is also a carbon in the center of the cluster, with a role that is not known. A mechanism has been suggested experimentally, where two hydrides leave as a hydrogen molecule in the critical E4 state. A structure with two hydrides, two protonated sulfurs and an unprotonated carbon has been suggested for this state. Rather recently, DFT calculations supported the experimental mechanism but found an active state where the central carbon is protonated all the way to CH3 . Even more recently, another DFT study was made that instead supported the experimentally suggested structure. To sort out the origin of these quite different computational results, additional calculations have here been performed using different DFT functionals. The conclusion from these calculations is very clear and shows no computational support for an unprotonated carbon in E4 . © 2017 Wiley Periodicals, Inc.
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Effect of plants in constructed wetlands for organic carbon and nutrient removal: a review of experimental factors contributing to higher impact and suggestions for future guidelines.
Jesus, JM, Danko, AS, Fiúza, A, Borges, MT
Environmental science and pollution research international. 2018;(5):4149-4164
Abstract
Constructed wetland is a proven technology for water pollution removal, but process mechanisms and their respective contribution are not fully understood. The present review details the effect of plants on removal efficiency of constructed wetlands by focusing on literature that includes experiments with unplanted controls for organic carbon and nutrient (N and P) removal. The contribution of plant direct uptake is also assessed. Although it was found that several studies, mostly at laboratory or pilot scales, showed no statistical differences between planted and unplanted controls, some factors were found that help maximize the effect of plants. This study intends to contribute to a better understanding of the significance of the effect of plants in a constructed wetland, as well as to suggest a set of experimental guidelines in this field.
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Solvent production by engineered Ralstonia eutropha: channeling carbon to biofuel.
Chakravarty, J, Brigham, CJ
Applied microbiology and biotechnology. 2018;(12):5021-5031
Abstract
Microbial production of solvents like acetone and butanol was a couple of the first industrial fermentation processes to gain global importance. These solvents are important feedstocks for the chemical and biofuel industry. Ralstonia eutropha is a facultatively chemolithoautotrophic bacterium able to grow with organic substrates or H2 and CO2 under aerobic conditions. This bacterium is a natural producer of polyhydroxyalkanoate biopolymers. Recently, with the advances in the development of genetic engineering tools, the range of metabolites R. eutropha can produce has enlarged. Its ability to utilize various carbon sources renders it an interesting candidate host for synthesis of renewable biofuel and solvent production. This review focuses on progress in metabolic engineering of R. eutropha for the production of alcohols, terpenes, methyl ketones, and alka(e)nes using various resources. Biological synthesis of solvents still presents the challenge of high production costs and competition from chemical synthesis. Better understanding of R. eutropha biology will support efforts to engineer and develop superior microbial strains for solvent production. Continued research on multiple fronts is required to engineer R. eutropha for truly sustainable and economical solvent production.