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Letteratura scientifica selezionata sul tema "PH regulation"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 25 maggio 2024

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Articoli di riviste sul tema "PH regulation"

Boron, Walter F. "Regulation of intracellular pH". Advances in Physiology Education 28, n. 4 (dicembre 2004): 160–79. http://dx.doi.org/10.1152/advan.00045.2004.

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The approach that most animal cells employ to regulate intracellular pH (pHi) is not too different conceptually from the way a sophisticated system might regulate the temperature of a house. Just as the heat capacity (C) of a house minimizes sudden temperature (T) shifts caused by acute cold and heat loads, the buffering power (β) of a cell minimizes sudden pHi shifts caused by acute acid and alkali loads. However, increasing C (or β) only minimizes T (or pHi) changes; it does not eliminate the changes, return T (or pHi) to normal, or shift steady-state T (or pHi). Whereas a house may have a furnace to raise T, a cell generally has more than one acid-extruding transporter (which exports acid and/or imports alkali) to raise pHi. Whereas an air conditioner lowers T, a cell generally has more than one acid-loading transporter to lower pHi. Just as a house might respond to graded decreases (or increases) in T by producing graded increases in heat (or cold) output, cells respond to graded decreases (or increases) in pHi with graded increases (or decreases) in acid-extrusion (or acid-loading) rate. Steady-state T (or pHi) can change only in response to a change in chronic cold (or acid) loading or chronic heat (or alkali) loading as produced, for example, by a change in environmental T (or pH) or a change in the kinetics of the furnace (or acid extrudes) or air conditioner (or acid loaders). Finally, just as a temperature-control system might benefit from environmental sensors that provide clues about cold and heat loading, at least some cells seem to have extracellular CO2 or extracellular HCO3− sensors that modulate acid-base transport.

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DUNN, JEFF F., e GILLIAN J. WALLEY. "Renal pH regulation in hypertension". Biochemical Society Transactions 19, n. 4 (1 novembre 1991): 421S. http://dx.doi.org/10.1042/bst019421s.

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Hackam, David J., Sergio Grinstein e Ori D. Rotstein. "INTRACELLULAR pH REGULATION IN LEUKOCYTES". Shock 5, n. 1 (gennaio 1996): 17–21. http://dx.doi.org/10.1097/00024382-199601000-00005.

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Vaughan-Jones, Richard D., Kenneth W. Spitzer e Pawel Swietach. "Intracellular pH regulation in heart". Journal of Molecular and Cellular Cardiology 46, n. 3 (marzo 2009): 318–31. http://dx.doi.org/10.1016/j.yjmcc.2008.10.024.

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Lacruz, Rodrigo S., Antonio Nanci, Ira Kurtz, J. Timothy Wright e Michael L. Paine. "Regulation of pH During Amelogenesis". Calcified Tissue International 86, n. 2 (17 dicembre 2009): 91–103. http://dx.doi.org/10.1007/s00223-009-9326-7.

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Flintoft, Louisa. "pH regulation by histone acetylation". Nature Reviews Genetics 14, n. 1 (18 dicembre 2012): 7. http://dx.doi.org/10.1038/nrg3403.

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FELLE, HUBERT H. "pH Regulation in Anoxic Plants". Annals of Botany 96, n. 4 (15 luglio 2005): 519–32. http://dx.doi.org/10.1093/aob/mci207.

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Dashper, S. G., e E. C. Reynolds. "pH Regulation by Streptococcus mutans". Journal of Dental Research 71, n. 5 (maggio 1992): 1159–65. http://dx.doi.org/10.1177/00220345920710050601.

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Chu, Shaoyou, Shin Tanaka, Jonathan D. Kaunitz e Marshall H. Montrose. "Dynamic regulation of gastric surface pH by luminal pH". Journal of Clinical Investigation 103, n. 5 (1 marzo 1999): 605–12. http://dx.doi.org/10.1172/jci5217.

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Dijkstra, J., J. L. Ellis, E. Kebreab, A. B. Strathe, S. López, J. France e A. Bannink. "Ruminal pH regulation and nutritional consequences of low pH". Animal Feed Science and Technology 172, n. 1-2 (febbraio 2012): 22–33. http://dx.doi.org/10.1016/j.anifeedsci.2011.12.005.

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Tesi sul tema "PH regulation"

Stephen, John R. "pH regulation in enteric bacteria". Thesis, University of Aberdeen, 1997. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=130919.

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Escherichia coli mutants impaired in growth and survival at low external pH in minimal medium were selected and attempts made to identify the disrupted genes. This study suggested that clpX, encoding a heat-shock induced protease and molecular chaperone, was functional in survival of E. coli at pH 3.3. Promoter probe plasmid libraries of Salmonella typhimurium LT2 DNA were created in E. coli and screened for acid-inducible transcriptional elements, and transcriptionally active fragments of degradative amino-acid decarboxylase genes recovered. Chromosomal gene fusions to the reporter gene lacZ in E. coli generated by Mu DII 1734 insertion were screened in a similar way and suggested that the gene encoding adenylate cyclase (cya) could be induced by mild cytoplasmic acidification. The sequence of a gene known to be inducible by cytoplasmic acidification, inaA, became available during the course of this study. The 5' region of this gene was used to generate a set of plasmids carrying fragments of the acid-inducible promoter transcriptionally fused to a luciferase based reporter system. Elements of the sequence required for induction by cytoplasmic acidification were identified. One of these reporter constructs was used to screen an E. coli Tn10 chromosomal insertional mutant library for genes involved in the regulation of inaA. One such mutant had a multiple antibiotic resistant (mar) phenotype. The disrupted loci in 2 other mutants were identified by inverse PCR, sequence analysis and database searches. Both were known only as open reading frames (ORFs) discovered during the sequencing of the entire E. coli genome, and were tentatively identified as yddB (closely linked to gadB and gadC; required for glutamate dependent acid resistance) and f300 (closely linked to pldA; required for detergent resistance). The promoter of f300 was shown to be sensitive to cytoplasmic acidification. The inaA promoter was also demonstrated to be induced at the onset of stationary phase, and to be independent of the stationary phase and weak-acid inducible σ factor RpoS and also of cAMP levels.

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Witzel, Dirk. "Pharmakologische Beeinflussung der pH-Regulation kardialer Fibroblasten". [S.l.] : [s.n.], 2003. http://archiv.ub.uni-marburg.de/diss/z2003/0424/.

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Rudnicka, Joanna Dorota. "Aspects of pH regulation in Aspergillus nidulans". Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415560.

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Huertas, Tatiana Munera. "Aspects of pH regulation in Aspergillus nidulans". Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526381.

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Rivinoja, A. (Antti). "Golgi pH and glycosylation". Doctoral thesis, University of Oulu, 2009. http://urn.fi/urn:isbn:9789514292699.

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Abstract Glycans, as a part of glycoproteins, glycolipids and other glycoconjugates, are involved in many vital intra- and inter-cellular tasks, such as protein folding and sorting, protein quality control, vesicular trafficking, cell signalling, immunological defence, cell motility and adhesion. Therefore, their correct construction is crucial for the normal functioning of eukaryotic cells and organisms they form. Most cellular glycans are constructed in the Golgi, and abnormalities in their structure may derive, for instance, from alkalinization of the Golgi lumen. In this work we show that Golgi pH is generally higher and more variable in abnormally glycosylating, i.e. strongly T-antigen (Gal-β1,3-GalNAc-ser/thr) expressing cancer cells, than in non-T-antigen expressing cells. We also confirmed that the Golgi pH alterations detected in cancer cells have the potential to induce glycosylation changes. A mere 0.2 pH unit increase in Golgi pH is able to induce T-antigen expression and inhibit terminal N-glycosylation in normally glycosylating cells. The mechanism of inhibition involves mislocalization of the corresponding glycosyltransferases. We also studied potential factors that can promote Golgi pH misregulation in health and disease, and found that cultured cancer cells, despite variation and elevation in Golgi pH, are fully capable of acidifying the Golgi lumen under the normal Golgi pH. Moreover, we introduce a Golgi localized Cl-/HCO3- exchanger, AE2a, that participates in Golgi pH regulation by altering luminal bicarbonate concentration and thus also buffering capacity. Participation of AE2a in Golgi pH regulation is especially intriguing, because it also provides a novel mechanism for expelling protons from the Golgi lumen.

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Furimsky, Marosh. "Intracellular pH regulation in hepatocytes of teleost fish". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58273.pdf.

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Grace, Andrew Ashley. "The regulation of intracellular pH and cardiac contraction". Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319389.

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Taylor, Caroline Joanne. "Intracellular pH regulation in rat brain endothelial cells". Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616055.

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Lundin, Karl, e Oscar Olli. "Automated hydroponics greenhouse : Regulation of pH and nutrients". Thesis, KTH, Maskinkonstruktion (Inst.), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-226662.

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The purpose of this project is to create a fully automatedgreenhouse that can produce year-round crops, using sensorsand actuators. Temperature in both water and air,relative humidity, water level, nutrient level and pH are allmeasured with different sensors. Though only water level,pH and nutrients will be regulated. The greenhouse will berelying on a hydroponic growing technique, meaning thatthe growing is soil-less and will be done in water. Thismakes measuring and controlling said levels easier and alsominimizes water waste and makes for a more environmentalsystem. The main focus of this project is on regulating pHand nutrient levels of the water. The system has shown tobe stable and self regulating within the desired intervals fornutrient concentration and pH for growing basil.
Syftet med det här projektet är att skapa ett automatiserat växthus som kan producera grödor året runt med hjälp av sensorer och aktuatorer. Med olika sensorer mäts temperaturen i både vattnet och luften, relativa luftfuktigheten, vattennivå, pH- och näringsvärden. Dock kommer endast vattennivå, pH- och näringsvärden regleras. Växthuset använder sig av så kallad hydroponisk odling, vilket innebär att odlingen inte sker i jord utan i vatten. Detta underlättar bland annat mätningar och kontrollering av systemet men minimerar även vattenkonsumptionen och bidrar till ett mera miljövänligt system. Projektet kommer i huvudsak inrikta sig på reglering av pH och näringsnivåer av vattnet. Systemet har visats stabilt och har förmågan att reglera sig självt inom önskat intervall för näringskoncentration och pH för att odla basilika.

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Müller, Matthias. "pH-Regulation und Glukosestoffwechsel - Wirkung von Glut1-Überexpression, Serum und Dexamethason auf den zytosolischen pH". [S.l. : s.n.], 2003. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB10733068.

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Libri sul tema "PH regulation"

Turk, Boris. Papain-like cysteine proteinases: Regulation by proteinase inhibitors and pH. Uppsala: SverigesLantbruksuniversitet, 1996.

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Williams, Mark R. pH and calcium regulation in lens epithelial cells: A fluorimetric dye study. Norwich: University of East Anglia, 1993.

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S, Egginton, Taylor E. W e Raven John A, a cura di. Regulation of tissue pH in plants and animals: A reappraisal of current techniques. Cambridge, UK: Cambridge University Press, 1999.

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Maidorn, Robert. Inhibition of the regulation of intracellular pH by analogues of amiloride as a possible mechanism of tumour selective therapy. Ottawa: National Library of Canada = Bibliothèque nationale du Canada, 1992.

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Numata, Masa. Ion Transporters and PH Regulation. Morgan & Claypool Life Science Publishers, 2014.

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The regulation of hydrogen and body pH. Brighton: University of Brighton, 1998.

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Egginton, S., Edwin W. Taylor e J. A. Raven, a cura di. Regulation of Tissue pH in Plants and Animals. Cambridge University Press, 1999. http://dx.doi.org/10.1017/cbo9780511542640.

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Rotin, Daniela. Regulation of intracellular pH as an important determinant of tumour cell viability. 1988.

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Swallow, Carol Jane. Cytoplasmic pH regulation in murine peritoneal macrophages: mechanisms, modulation and functional significance. 1993.

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Egginton, S., Edwin W. Taylor e J. A. Raven. Regulation of Tissue pH in Plants and Animals: A Reappraisal of Current Techniques. Cambridge University Press, 2005.

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Capitoli di libri sul tema "PH regulation"

Spillman, Natalie Jane, e Leann Tilley. "pH Regulation". In Encyclopedia of Malaria, 1–11. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-8757-9_32-1.

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Baker, Julien S., Fergal Grace, Lon Kilgore, David J. Smith, Stephen R. Norris, Andrew W. Gardner, Robert Ringseis et al. "pH Regulation". In Encyclopedia of Exercise Medicine in Health and Disease, 703. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-540-29807-6_2862.

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Boron, Walter F. "Intracellular pH Regulation". In Membrane Transport Processes in Organized Systems, 39–51. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-5404-8_3.

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Boron, Walter F. "Intracellular pH Regulation". In Physiology of Membrane Disorders, 423–35. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4613-2097-5_26.

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Moe, Orson W., e Robert J. Alpern. "Regulation of Cell pH". In Molecular Biology of Membrane Transport Disorders, 407–25. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-1143-0_20.

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Lote, Chris. "Renal regulation of body fluid pH". In Principles of Renal Physiology, 124–42. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-011-4086-7_10.

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Heber, U., M. Hauser, V. Oja, A. Laisk, R. Bligny e R. Douce. "Photosynthesis and pH Regulation in Leaves". In Photosynthesis: from Light to Biosphere, 4333–38. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-009-0173-5_1019.

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Arst, H. N. "Regulation of Gene Expression by pH". In Biochemistry and Molecular Biology, 235–40. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-662-10367-8_10.

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Stumpp, Meike, e Marian Y. Hu. "pH Regulation and Excretion in Echinoderms". In Acid-Base Balance and Nitrogen Excretion in Invertebrates, 261–73. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-39617-0_10.

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Curthoys, Norman P., Aimin Tang e Gerhard Gstraunthaler. "pH Regulation of Renal Gene Expression". In Novartis Foundation Symposia, 100–114. Chichester, UK: John Wiley & Sons, Ltd, 2008. http://dx.doi.org/10.1002/0470868716.ch7.

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Atti di convegni sul tema "PH regulation"

Эшонқулов, Санжар, Ғайбулла Бобоев e Манучеҳр Мирзаев. "ANALYSIS OF GLASS ELECTRODE pH-METERS". In Status and development trends of standardization and technical regulation in the world. Tashkent state technical university, 2022. http://dx.doi.org/10.51346/tstu-conf.22.1-77-0091.

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Casillas-Romero, S. A., e O. Begovich. "Monitoring and pH regulation in urban hydroponic systems". In 2021 IEEE International Autumn Meeting on Power, Electronics and Computing (ROPEC). IEEE, 2021. http://dx.doi.org/10.1109/ropec53248.2021.9668154.

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Tsai, Huei-Hsuan. "pH-dependent regulation of iron deficiency response in Arabidopsis". In ASPB PLANT BIOLOGY 2020. USA: ASPB, 2020. http://dx.doi.org/10.46678/pb.20.1374628.

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Lakatos, I., J. Lakatos-Szabo e B. Kosztin. "Optimization of Barite Dissolvers by Organic Acids and pH Regulation". In International Symposium on Oilfield Scale. Society of Petroleum Engineers, 2002. http://dx.doi.org/10.2118/74667-ms.

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Vigier, Nathalie, Steeve Comeau, Laurent Counillon, Malcom McCulloch e Riccardo Rodolfo-Metalpa. "Lithium Isotope Composition of Scleratinian Corals is Sensitive to Internal pH Regulation". In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.2682.

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Maruyama, Hisataka, Naoya Inoue e Fumihito Arai. "Optical pH regulation using photochromic material for selective cell injection of nanosensors". In 2010 IEEE Nanotechnology Materials and Devices Conference (NMDC). IEEE, 2010. http://dx.doi.org/10.1109/nmdc.2010.5652526.

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LIU, L., W. SCHULTZ e JW HASTINGS. "pH REGULATION OF LUCIFERASE ACTIVITY IN DINOFLAGELLATES INVOLVES A NOVEL ENZYMATIC MECHANISM". In Proceedings of the 13th International Symposium. WORLD SCIENTIFIC, 2005. http://dx.doi.org/10.1142/9789812702203_0004.

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Satoh, Wataru, Hiroki Hosono, Mariko Toya, Katsuya Morimoto, Junji Fukuda e Hiroaki Suzuki. "Microanalysis System Based on Electrochemiluminescence with Automatic Mixing and pH-Regulation Functions". In TRANSDUCERS 2007 - 2007 International Solid-State Sensors, Actuators and Microsystems Conference. IEEE, 2007. http://dx.doi.org/10.1109/sensor.2007.4300678.

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Limchesing, Tristan Joseph C., Rhen Anjerome Bedruz, Ryan Rhay Vicerra, John Anthony Jose e Nilo Bugtai. "A pH Regulation System for Perfusion Machine Using Computer Vision and Fuzzy Logic". In 2019 4th Asia-Pacific Conference on Intelligent Robot Systems (ACIRS). IEEE, 2019. http://dx.doi.org/10.1109/acirs.2019.8936033.

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Maruyama, Hisataka, Taisuke Masuda, Naoya Inoue, Ayae Honda, Tatsuro Takahata e Fumihito Arai. "Optical pH regulation using functional nanotool impregnating with photo-responsive chemical for intracellular measurement". In 2010 International Symposium on Micro-NanoMechatronics and Human Science (MHS). IEEE, 2010. http://dx.doi.org/10.1109/mhs.2010.5669557.

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Rapporti di organizzazioni sul tema "PH regulation"

Taiz, Lincoln. Regulation of Vacuolar pH in Citrus limon. Office of Scientific and Technical Information (OSTI), giugno 2005. http://dx.doi.org/10.2172/841076.

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Gillies, Robert J. PH Regulation by Breast Cancer Cells In Vitro and In Vivo. Fort Belvoir, VA: Defense Technical Information Center, settembre 1997. http://dx.doi.org/10.21236/ada337859.

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Gillies, Robert J. PH Regulation by Breast Cancer Cells In Vitro and In Vivo. Fort Belvoir, VA: Defense Technical Information Center, settembre 1999. http://dx.doi.org/10.21236/ada391288.

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Prusky, Dov, e Jeffrey Rollins. Modulation of pathogenicity of postharvest pathogens by environmental pH. United States Department of Agriculture, dicembre 2006. http://dx.doi.org/10.32747/2006.7587237.bard.

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Until recently, environmental pH was not considered a factor in determining pathogen compatibility. Our hypothesis was that the environmental pH at the infection site, which is dynamically controlled by activities of both the host and the pathogen, regulates the expression of genes necessary for disease development in Colletotrichum gloeosporioides and Sclerotinia sclerotiorum. This form of regulation ensures that genes are expressed at optimal conditions for their encoded activities.Pectate lyase encoded by pelB, has been demonstrated to play a key role in virulence of C. gloeosporioides in avocado fruit. Polyglacturonase synergism with oxalic acid production is considered to be an essential pathogenicity determinant in the interactions of S. sclerotiorum with its numerous hosts. A common regulatory feature of these virulence and pathogenicity factors is their dependence upon environmental pH conditions within the host niche to create optimal conditions for expression and secretion. In this proposal we have examined, 1) the mechanisms employed by these fungi to establish a suitable pH environment, 2) the molecular levels at which genes and gene products are regulated in response to environmental pH, and 3) the molecular basis and functional importance of pH-responsive gene regulation during pathogenicity. The specific objectives of the proposal were: 1. Characterize the mechanism of local pH modulation and the effect of ambient pH on the expression and secretion of virulence factors. 2. Provide evidence that a conserved molecular pathway for pH-responsive gene expression exists in C. gloeosporioides by cloning a pacC gene homologue. 3. Determine the role of pacC in pathogenicity by gene disruption and activating mutations. Major conclusions 1. We determined the importance of nitrogen source and external pH in the secretion of the virulence factor pectate lyase with respect to the ambient pH transcriptional regulator pacC. It was concluded that nitrogen source availability and ambient pH are two independent signals for the transcriptional regulation of genes required for the disease process of C. gloeosporioides and possibly of other pathogens. 2. We also determined that availability of ammonia regulate independently the alkalinization process and pelB expression, pecate lyase secretion and virulence of C. gloeosporioides. 3. Gene disruption of pacC reduced virulence of C. gloeosporioides however did not reduced fully pelB expression. It was concluded that pelB expression is regulated by several factors including pH, nitrogen and carbon sources. 4. Gene disruption of pacC reduced virulence of S. slcerotiourum Creation of a dominant activating

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Prusky, Dov, Nancy P. Keller e Amir Sherman. global regulation of mycotoxin accumulation during pathogenicity of Penicillium expansum in postharvest fruits. United States Department of Agriculture, gennaio 2014. http://dx.doi.org/10.32747/2014.7600012.bard.

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Background to the topic- Penicilliumas a postharvest pathogen and producer of the mycotoxin PAT. Penicilliumspp. are destructive phytopathogens, capable of causing decay in many deciduous fruits, during postharvest handling and storage; and the resulting losses can amount to 10% of the stored produce and the accumulation of large amounts of the mycotoxinpatulin. The overall goal of this proposal is to identify critical host and pathogen factors that modulate P. expansummycotoxin genes and pathways which are required for PAT production and virulence. Our preliminary results indicated that gluconic acid are strongly affecting patulin accumulation during colonization. P. expansumacidifies apple fruit tissue during colonization in part through secretion of gluconic acid (GLA). Several publications suggested that GLA accumulation is an essential factor in P. expansumpathogenicity. Furthermore, down regulation of GOX2 significantly reduced PAT accumulation and pathogenicity. PAT is a polyketide and its biosynthesis pathway includes a 15-gene cluster. LaeA is a global regulator of mycotoxin synthesis. It is now known that patulin synthesis might be subjected to LaeA and sometimes by environmental sensing global regulatory factors including the carbon catabolite repressor CreA as well as the pH regulator factor PacC and nitrogen regulator AreA. The mechanisms by which LaeA regulates patulin synthesis was not fully known and was part of our work. Furthermore, the regulatory system that controls gene expression in accordance with ambient pH was also included in our work. PacC protein is in an inactive conformation and is unable to bind to the promoter sites of the target genes; however, under alkaline growth conditions activated PacC acts as both an activator of alkaline-expressed genes and a repressor of acid-expressed genes. The aims of the project- This project aims to provide new insights on the roles of LaeA and PacC and their signaling pathways that lead to GLA and PAT biosynthesis and pathogenicity on the host. Specifically, our specific aims were: i) To elucidate the mechanism of pH-controlled regulation of GLA and PAT, and their contribution to pathogenesis of P. expansum. We are interested to understanding how pH and/or GLA impact/s under PacC regulation affect PAT production and pathogenesis. ii) To characterize the role of LaeA, the global regulator of mycotoxin production, and its effect on PAT and PacC activity. iii) To identify the signaling pathways leading to GLA and PAT synthesis. Using state- of-the-art RNAseq technologies, we will interrogate the transcriptomes of laeAand pacCmutants, to identify the common signaling pathways regulating synthesis of both GLA and PAT. Major conclusions, solutions, achievements- In our first Aim our results demonstrated that ammonia secreted at the leading edge of the fungal colony induced transcript activation of the global pH modulator PacC and PAT accumulation in the presence of GLA. We assessed these parameters by: (i) direct exogenous treatment of P. expansumgrowing on solid medium; (ii) direct exogenous treatment on colonized apple tissue; (iii) growth under self-ammonia production conditions with limited carbon; and (iv) analysis of the transcriptional response to ammonia of the PAT biosynthesis cluster. Ammonia induced PAT accumulation concurrently with the transcript activation of pacCand PAT biosynthesis cluster genes, indicating the regulatory effect of ammonia on pacCtranscript expression under acidic conditions. Transcriptomic analysis of pH regulated processes showed that important genes and BARD Report - Project 4773 Page 2 of 10 functionalities of P. expansumwere controlled by environmental pH. The differential expression patterns of genes belonging to the same gene family suggest that genes were selectively activated according to their optimal environmental conditions to enable the fungus to cope with varying conditions and to make optimal use of available enzymes. Concerning the second and third Aims, we demonstrated that LaeA regulates several secondary metabolite genes, including the PAT gene cluster and concomitant PAT synthesis invitro. Virulence studies of ΔlaeAmutants of two geographically distant P. expansumisolates (Pe-21 from Israel and Pe-T01 from China) showed differential reduction in disease severity in freshly harvested fruit ranging from no reduction for Ch-Pe-T01 strains in immature fruit to 15–25% reduction for both strains in mature fruit, with the ΔlaeAstrains of Is-Pe-21 always showing a greater loss in virulence. Results suggest the importance of LaeA regulation of PAT and other secondary metabolites on pathogenicity. Our work also characterized for the first time the role of sucrose, a key nutritional factor present in apple fruit, as a negative regulator of laeAexpression and consequent PAT production in vitro. This is the first report of sugar regulation of laeAexpression, suggesting that its expression may be subject to catabolite repression by CreA. Some, but not all of the 54 secondary metabolite backbone genes in the P. expansumgenome, including the PAT polyketide backbone gene, were found to be regulated by LaeA. Together, these findings enable for the first time a straight analysis of a host factor that potentially activates laeAand subsequent PAT synthesis.

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Sionov, Edward, Nancy Keller e Shiri Barad-Kotler. Mechanisms governing the global regulation of mycotoxin production and pathogenicity by Penicillium expansum in postharvest fruits. United States Department of Agriculture, gennaio 2017. http://dx.doi.org/10.32747/2017.7604292.bard.

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The original objectives of the study, as defined in the approved proposal, are: To characterize the relationship of CreA and LaeA in regulation of P T production To understand how PacC modulates P. expansumpathogenicity on apples To examine if other secondary metabolites are involved in virulence or P. expansumfitness To identify the signaling pathways leading to PAT synthesis Penicilliumexpansum, the causal agent of blue mould rot, is a critical health concern because of the production of the mycotoxinpatulin (PAT) in colonized apple fruit tissue. Although PAT is produced by many Penicilliumspecies, the factors activating its biosynthesis were not clear. This research focused on host and fungal mechanisms of activation of LaeA (the global regulator of secondary metabolism), PacC (the global pH modulator) and CreA (the global carbon catabolite regulator) on PAT synthesis with intention to establish P. expansumas the model system for understanding mycotoxin synthesis in fruits. The overall goal of this proposal is to identify critical host and pathogen factors that mechanistically modulate P. expansumgenes and pathways to control activation of PAT production and virulence in host. Several fungal factors have been correlated with disease development in apples, including the production of PAT, acidification of apple tissue by the fungus, sugar content and the global regulator of secondary metabolism and development, LaeA. An increase in sucrose molarity in the culture medium from 15 to 175 mM negatively regulated laeAexpression and PAT accumulation, but, conversely, increased creAexpression, leading to the hypothesis that CreA could be involved in P. expansumPAT biosynthesis and virulence, possibly through the negative regulation of LaeA. We found evidence for CreAtranscriptional regulation of laeA, but this was not correlated with PAT production either in vitro or in vivo, thus suggesting that CreA regulation of PAT is independent of LaeA. Our finding that sucrose, a key ingredient of apple fruit, regulates PAT synthesis, probably through suppression of laeAexpression, suggests a potential interaction between CreA and LaeA, which may offer control therapies for future study. We have also identified that in addition to PAT gene cluster, CreA regulates other secondary metabolite clusters, including citrinin, andrastin, roquefortine and communesins, during pathogenesis or during normal fungal growth. Following creation of P. expansumpacCknockout strain, we investigated the involvement of the global pH regulator PacC in fungal pathogenicity. We demonstrated that disruption of the pH signaling transcription factor PacC significantly decreased the virulence of P. expansumon deciduous fruits. This phenotype is associated with an impairment in fungal growth, decreased accumulation of gluconic acid and reduced synthesis of pectolytic enzymes. We showed that glucose oxidase- encoding gene, which is essential for gluconic acid production and acidification during fruit colonization, was significantly down regulated in the ΔPepacCmutant, suggesting that gox is PacC- responsive gene. We have provided evidence that deletion of goxgene in P. expansumled to a reduction in virulence toward apple fruits, further indicating that GOX is a virulence factor of P. expansum, and its expression is regulated by PacC. It is also clear from the present data that PacC in P. expansumis a key factor for the biosynthesis of secondary metabolites, such as PAT. On the basis of RNA-sequencing (RNA-seq) analysis and physiological experimentation, the P. expansumΔlaeA, ΔcreAand ΔpacCmutants were unable to successfully colonize apples for a multitude of potential mechanisms including, on the pathogen side, a decreased ability to produce proteolytic enzymes and to acidify the environment and impaired carbon/nitrogen metabolism and, on the host side, an increase in the oxidative defence pathways. Our study defines these global regulatory factors and their downstream signalling pathways as promising targets for the development of strategies to fight against this post-harvest pathogen.

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Fromm, Hillel, e Joe Poovaiah. Calcium- and Calmodulin-Mediated Regulation of Plant Responses to Stress. United States Department of Agriculture, settembre 1993. http://dx.doi.org/10.32747/1993.7568096.bard.

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We have taken a molecular approach to clone cellular targets of calcium/calmodulin (Ca2+/CaM). A 35S-labeled recombinant CaM was used as a probe to screen various cDNA expression libraries. One of the isolated clones from petunia codes for the enzyme glutamate decarboxylase (GAD) which catalyzes the conversion of glutamate to g-aminobutyric acid (GABA). The activity of plant GAD has been shown to be dramatically enhanced in response to cold and heat shock, anoxia, drought, mechanical manipulations and by exogenous application of the stress phytohormone ABA in wheat roots. We have purified the recombinant GAD by CaM-affinity chromatography and studied its regulation by Ca2+/CaM. At a physiological pH range (7.0-7.5), the purified enzyme was inactive in the absence of Ca2+ and CaM but could be stimulated to high levels of activity by the addition of exogenous CaM (K0.5 = 15 nM) in the presence of Ca2+ (K 0.5 = 0.8 mM). Neither Ca2+ nor CaM alone had any effect on GAD activity. Transgenic tobacco plants expressing a mutant petunia GAD lacking the CaM-binding domain, or transgenic plants expressing the intact GAD were prepared and studied in detail. We have shown that the CaM-binding domain is necessary for the regulation of glutamate and GABA metabolism and for normal plant development. Moreover, we found that CaM is tightly associated with a 500 kDa GAD complex. The tight association of CaM with its target may be important for the rapid modulation of GAD activity by Ca2+ signaling in response to stresses.

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Moran, Nava, Richard Crain e Wolf-Dieter Reiter. Regulation by Light of Plant Potassium Uptake through K Channels: Biochemical, Physiological and Biophysical Study. United States Department of Agriculture, settembre 1995. http://dx.doi.org/10.32747/1995.7571356.bard.

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The swelling of plant motor cells is regulated by various signals with almost unknown mediators. One of the obligatory steps in the signaling cascade is the activation of K+-influx channels -K+ channels activated by hyperpolarization (KH channels). We thus explored the regulation of these channels in our model system, motor cell protoplasts from Samanea saman, using patch-clamp in the "whole cell" configuration. (a) The most novel finding was that the activity of KH channels in situ varied with the time of the day, in positive correlation with cell swelling: in Extensor cells KH channels were active in the earlier part of the day, while in Flexor cells only during the later part of the day; (b) High internal pH promoted the activity of these channels in Extensor cells, opposite to the behavior of the equivalent channels in guard cells, but in conformity with the predicted behavior of the putative KH channel, cloned from S. saman recently; (c) HIgh external K+ concentration increased (KH channel currents in Flexor cells. BL depolarized the Flexor cells, as detected in cell-attached patch-clamp recording, using KD channels (the K+-efflux channels) as "voltage-sensing devices". Subsequent Red-Light (RL) pulse followed by Darkness, hyperpolarized the cell. We attribute these changes to the inhibition of the H+-pump by BL and its reactivation by RL, as they were abolished by an H+-pump inhibitor. BL increased also the activity KD channels, in a voltage-independent manner - in all probability by an independent signaling pathway. Blue-Light (BL), which stimulates shrinking of Flexor cells, evoked the IP3 signaling cascade (detected directly by IP3 binding assay), known to mobilize cytosolic Ca2+. Nevertheless, cytosolic Ca2+ . did not activate the KD channel in excised, inside-out patches. In this study we established a close functional similarity of the KD channels between Flexor and Extensior cells. Thus the differences in their responses must stem from different links to signaling in both cell types.

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Schuster, Gadi, e David Stern. Integrated Studies of Chloroplast Ribonucleases. United States Department of Agriculture, settembre 2011. http://dx.doi.org/10.32747/2011.7697125.bard.

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Gene regulation at the RNA level encompasses multiple mechanisms in prokaryotes and eukaryotes, including splicing, editing, endo- and exonucleolytic cleavage, and various phenomena related to small or interfering RNAs. Ribonucleases are key players in nearly all of these post-transcriptional mechanisms, as the catalytic agents. This proposal continued BARD-funded research into ribonuclease activities in the chloroplast, where RNase mutation or deficiency can cause metabolic defects and is often associated with plant chlorosis, embryo or seedling lethality, and/or failure to tolerate nutrient stress. The first objective of this proposal was to examined a series of point mutations in the PNPase enzyme of Arabidopsis both in vivo and in vitro. This goal is related to structure-function analysis of an enzyme whose importance in many cellular processes in prokaryotes and eukaryotes has only begun to be uncovered. PNPase substrates are mostly generated by endonucleolytic cleavages for which the catalytic enzymes remain poorly described. The second objective of the proposal was to examine two candidate enzymes, RNase E and RNase J. RNase E is well-described in bacteria but its function in plants was still unknown. We hypothesized it catalyzes endonucleolytic cleavages in both RNA maturation and decay. RNase J was recently discovered in bacteria but like RNase E, its function in plants had yet to be explored. The results of this work are described in the scientific manuscripts attached to this report. We have completed the first objective of characterizing in detail TILLING mutants of PNPase Arabidopsis plants and in parallel introducing the same amino acids changes in the protein and characterize the properties of the modified proteins in vitro. This study defined the roles for both RNase PH core domains in polyadenylation, RNA 3’-end maturation and intron degradation. The results are described in the collaborative scientific manuscript (Germain et al 2011). The second part of the project aimed at the characterization of the two endoribonucleases, RNase E and RNase J, also in this case, in vivo and in vitro. Our results described the limited role of RNase E as compared to the pronounced one of RNase J in the elimination of antisense transcripts in the chloroplast (Schein et al 2008; Sharwood et al 2011). In addition, we characterized polyadenylation in the chloroplast of the green alga Chlamydomonas reinhardtii, and in Arabidopsis (Zimmer et al 2009). Our long term collaboration enabling in vivo and in vitro analysis, capturing the expertise of the two collaborating laboratories, has resulted in a biologically significant correlation of biochemical and in planta results for conserved and indispensable ribonucleases. These new insights into chloroplast gene regulation will ultimately support plant improvement for agriculture.

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Blumwald, Eduardo, e Avi Sadka. Sugar and Acid Homeostasis in Citrus Fruit. United States Department of Agriculture, gennaio 2012. http://dx.doi.org/10.32747/2012.7697109.bard.

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Citrus fruit quality standards have been determined empirically, depending on species and on the particular growing regions. In general, the TSS (total soluble solids) to total acidity (TA) ratio determines whether citrus fruit can be marketed. Soluble sugars account for most of the TSS during harvest while TA is determined almost solely by the citric acid content, which reaches levels of 1-5% by weight in many cultivated varieties. Acid and sugar homeostasis in the fruit is critical for the management of existing cultivars, the development of new cultivars, the improvement of pre- and post-harvest strategies and the control of fruit quality and disorders. The current proposal (a continuation of a previous proposal) aimed at: (1) completing the citrus fruit proteome and metabolome, and establish a citrus fruit functional database, (2) further characterization of the control of fruit acidity by studying the regulation of key steps affecting citrate metabolism, and determine the fate of citrate during acid decline stage, and (3) Studying acid and sugar homeostasis in citrus fruits by characterizing transport mechanisms across membranes. These aims were completed as the following: (1) Our initial efforts were aimed at the characterization and identification of citric acid transporters in citrus juice cells. The identification of citrate transporters at the vacuole of the citrus juice cell indicated that the steady-state citrate cytosolic concentration and the action of the cytosolic aconitase were key elements in establishing the pH homeostat in the cell that regulates the metabolic shift towards carbon usage in the fruit during the later stages of fruit development. We focused on the action of aconitase, the enzyme mediating the metabolic use of citric acid in the cells, and identified processes that control carbon fluxes in developing citrus fruits that control the fruit acid load; (2) The regulation of aconitase, catalyzing a key step in citrate metabolism, was further characterized by using two inhibitors, citramalte and oxalomalte. These compounds significantly increased citrate content and reduced the enzyme’s activity. Metabolite profiling and changes of amino-acid metabolizing enzymes in oxalomalate- treated cells suggested that the increase in citrate, caused by aconitase inhibition, induces amino acid synthesis and the GABA shunt, in accordance with the suggested fate of citrate during the acid decline stage in citrus fruit. (3) We have placed a considerable amount of time on the development of a citrus fruit proteome that will serve to identify all of the proteins in the juice cells and will also serve as an aid to the genomics efforts of the citrus research community (validating the annotation of the fruit genes and the different ESTs). Initially, we identified more than 2,500 specific fruit proteins and were able to assign a function to more than 2,100 proteins (Katz et al., 2007). We have now developed a novel Differential Quantitative LC-MS/MS Proteomics Methodology for the identification and quantitation of key biochemical pathways in fruits (Katz et al., 2010) and applied this methodology to identify determinants of key traits for fruit quality (Katz et al., 2011). We built “biosynthesis maps” that will aid in defining key pathways associated with the development of key fruit quality traits. In addition, we constructed iCitrus (http://wiki.bioinformatics.ucdavis.edu/index.php/ICitrus), a “functional database” that is essentially a web interface to a look-up table that allows users to use functional annotations in the web to identify poorly annotated citrus proteins. This resource will serve as a tool for growers and field extension specialists.

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