Готові списки джерел за темами / Acid-sensitive

Добірка наукової літератури з теми "Acid-sensitive"

Автор: Grafiati

Опубліковано: 7 липня 2024

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Статті в журналах з теми "Acid-sensitive":

Rotte, Anand, Madhuri Bhandaru, Michael Föller, Raja Biswas, Andreas F. Mack, Björn Friedrich, Rexhep Rexhepaj, et al. "APC Sensitive Gastric Acid Secretion." Cellular Physiology and Biochemistry 23, no. 1-3 (2009): 133–42. http://dx.doi.org/10.1159/000204102.

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KONDO, Eiko, and Koomi KANAI. "FATTY ACID-SENSITIVE ACID PHOSPHATASE ACTIVITY OF TUBERCLE BACILLI." Japanese Journal of Medical Science and Biology 45, no. 1 (1992): 19–34. http://dx.doi.org/10.7883/yoken1952.45.19.

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Kelly, C. A., J. W. M. Rudd, R. H. Hesslein, D. W. Schindler, P. J. Dillon, C. T. Driscoll, S. A. Gherini, and R. E. Hecky. "Prediction of biological acid neutralization in acid-sensitive lakes." Biogeochemistry 3, no. 1-3 (February 1987): 129–40. http://dx.doi.org/10.1007/bf02185189.

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Sinclair, Meeghan. "An ultra-sensitive nucleic acid sensor?" Nature Biotechnology 19, no. 1 (January 2001): 9. http://dx.doi.org/10.1038/83632.

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Kim, Soeun, Olga Linker, Kim Garth, and Kenneth R. Carter. "Degradation kinetics of acid-sensitive hydrogels." Polymer Degradation and Stability 121 (November 2015): 303–10. http://dx.doi.org/10.1016/j.polymdegradstab.2015.09.014.

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Yang, T., Y. Ding, Y. Zhu, Y. Li, X. Wang, R. Yang, G. Lu, J. Qi, and Y. Yang. " Rhizosphere bacteria induced by aluminum-tolerant and aluminum-sensitive soybeans in acid soil." Plant, Soil and Environment 58, No. 6 (June 18, 2012): 262–67. http://dx.doi.org/10.17221/652/2011-pse.

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Rhizosphere microbial communities play a major role in multiple soil functions. The aim of this study is to assess the relation of bacteria and organic acids in rhizosphere soil and community function induced by soybean genotypes, BX10 [aluminum (Al)-tolerant soybean] and BD2 (Al-sensitive soybean). Organic acid analysis in the rhizosphere soil indicates that BX10 increased the concentration of citric acid, whereas BD2 decreased it; malic acid was only found in the rhizosphere soil of BX10. Redundancy analysis results also showed that the two soybean genotypes induced distinct rhizosphere microbial communities, and citric acid and malic acid had a significantly positive correlation with rhizosphere bacteria of BX10. The community level physiological profiling showed that BX10 might have more influence than BD2 on the ability to metabolize organic C substrates. Sequence analysis indicates that two soybeans stimulate some rhizobacteria, such as species of Acinetobacter, Candidatus Amoebinatus, and uncultured proteobacterium. This study revealed that rhizobacteria of two soybeans may be related to their organic acid exudation.    

Bybee, Karen. "Phosphonic Acid for Stimulating HF-Sensitive Reservoirs." Journal of Petroleum Technology 56, no. 07 (July 1, 2004): 47–48. http://dx.doi.org/10.2118/0704-0047-jpt.

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HWANG, Jongseung, Heetae KIM, Jaehyun LEE, Dongmok WHANG, and Sungwoo HWANG. "Deoxyribonucleic Acid Sensitive Graphene Field-Effect Transistors." IEICE Transactions on Electronics E94-C, no. 5 (2011): 826–29. http://dx.doi.org/10.1587/transele.e94.c.826.

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Szczeklik, A., R. J. Gryglewski, G. Czerniawska-Mysik, and E. Nizankowska. "Aspirin Sensitive Asthma and Arachidonic Acid Transformation." Allergy and Asthma Proceedings 7, no. 1 (January 1, 1986): 21–25. http://dx.doi.org/10.2500/108854186779045548.

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Hagar, William G., Barbara A. Crosby, and Bruce W. Stallsmith. "Comparing and assessing acid rain-sensitive ponds." Journal of Hazardous Materials 74, no. 1-2 (May 2000): 125–31. http://dx.doi.org/10.1016/s0304-3894(99)00203-4.

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Дисертації з теми "Acid-sensitive":

Jones, John I. W. "Characterisation of acid-sensitive dyspepsia." Thesis, Nottingham Trent University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272811.

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Gallovic, Matthew D. "Acid-Sensitive Polymer Microparticles for Subunit Vaccine Delivery." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1468803443.

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Lamb, Justin. "Molecular aspects of amino acid sensitive cell cycle control." Thesis, University of Aberdeen, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245976.

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The existence and molecular basis of an amino acid sensitive cell cycle control mechanism in human cells is described for the first time. Withdrawal of a single amino acid (arginine) from normal human fibroblast cultures caused a rapid cessation of proliferation characterised with a loss of accumulation of cells with G1 DNA content, consistent with a loss of cyclin D1-associated kinase activity and the predominance of hypo-phosphorylated pRb. Restoration of amino acid caused a synchronous reentry to cycle after a delay in excess of that for M to S transit in freely cycling populations, indicating exit from a quiescent-like state. The cellular response was thus consistent with Pardee's concept of a pivotal cell cycle control mechanism in G1, sensitive to extracellular conditions (ie the R-point) (Pardee, 1974). Inhibition of expression of the pRb phosphorylating kinase, cdk4, was identified as the key regulatory element in the response. A hypothetical cellular communication pathway coupling amino acid shortage to translational suppression of cdk4 (the '-Arg/cdk4 response pathway') has been synthesised from the known biochemical effects of deprivation and the recognised determinants of this suppression, including a 5'UTR mediated wild-type p53 dependency. A strategy for analysis and interrogation of this translational control mechanism, based upon the synthesis of epitope-tagged protein from full length or 5'URT truncated cdk4 cDNAs, and attempts to confirm the primacy of cdk4 suppression to the antiproliferative response by its enforced expression, are described. A highly deranged human tumour cell line (HeLa) was found to be deficient in amino acid sensitive cell cycle control. These cells continued in cycle after withdrawal but this was accompanied by a rapid loss of viability and cell disintegration. Simultaneous cell cycle blocks conferred partial protection from arginine deprivation induced cell death. The possibility that inappropriate cell cycle progression was the cause of cell death is discussed. Not all human tumour lines were vulnerable to arginine deprivation. This responsivity was found to be predicted by the status of the functional determinants identified or inferred (ie wild-type pRb, with cdk4 as the predominant phosphorylating kinase, intact'-Arg'cdk4 response pathway). This work describes a novel cellular response mechanism, complementing recent similar findings from elsewhere, to connect cellular biosynthetic capacity with control of cell cycle progression, with significance to the maintenance of normal cell growth regulation and suppression of the malignant phenotype, and providing a broader understanding of 'physiological' cell cycle control.

Agius, Ronald. "PH-sensitive binding of nickel(II) ions to aspartic acid." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971555737.

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Roberge, Stéphane. "Conjugated Linoleic Acid/Styrene/Butyl Acrylate Bulk and Emulsion Polymerization." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34536.

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The potential for conjugated linoleic acid (CLA) incorporation into pressure-sensitive adhesive (PSA) formulations was evaluated. A series of free radical bulk copolymerizations of CLA/styrene (Sty) and CLA/butyl acrylate (BA) were designed to allow the estimation of reactivity ratios. Bulk terpolymerizations of CLA/Sty/BA were also evaluated before moving to emulsion terpolymerizations of CLA/Sty/BA. The polymers were characterized for composition, conversion, molecular weight and glass transition temperature while latexes were characterized for viscosity, particle size, tack, peel strength, and shear strength. All experiments were performed at 80oC and monitored with attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. While bulk experiments were monitored off-line, the emulsion experiments were monitored in-line. Absorbance peaks related to the monomers and polymer were tracked to provide conversion and polymer composition data using a multivariate calibration method. Off-line measurements using gravimetry and 1H-NMR spectroscopy were compared to the ATR-FTIR data and no significant differences were detected between the measurement methods. Pseudo-kinetic models, developed and validated with the copolymer experimental data, were used to estimate reactivity ratios. The copolymer pseudo-kinetic models were extended to a terpolymer pseudo-kinetic model and validated with experimental data. The pseudo-kinetic models incorporated the ability of oleic acid, a common impurity found in CLA, to trap electrons thus influencing the reaction kinetics significantly. The influence of terpolymer composition, chain transfer agent concentration, cross-linker concentration, molecular weight, viscosity and particle size on tack, peel strength and shear strength was investigated by using a constrained mixture design. The final forms of the resulting empirical models allowed the creation of 3D response surfaces for PSA performance optimization. The incorporation of 30 wt.% CLA into a practical PSA application suitable for the removable adhesives category was achieved.

Virdee, Susan. "The use of acid sensitive dyes to monitor acid generation and diffusion in thin polymer films." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ32562.pdf.

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Goss, Heather Vanessa. "Contrasting Chemical Response to Experimental Acidification of Fice Acid-sensitive Streams." Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/GossHV2006.pdf.

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Jadhav, Amol. "Paramagnetic microparticle manipulation for rapid and sensitive nucleic acid sequence identification." Thesis, University of Newcastle upon Tyne, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608361.

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Evans, S. W. "The rate of release of aluminium from acidic and acid sensitive soils." Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308840.

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Schweitzer, Lawrence D. (Lawrence David). "Identification of novel proteins that regulate the amino acid-sensitive mTORC1 pathway." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/103249.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Biology, 2016.
Cataloged from PDF version of thesis. "February 2016."
Includes bibliographical references.
mTOR is a serine-threonine kinase that, as the catalytic subunit of mTORC1, promotes growth and anabolism. Due to its central role in metabolism, the local and systemic environment surrounding the cell tightly regulate mTORC1. Growth factors and nutrients are each required to activate mTORC1 and promote growth. Activation of mTORC1 by growth factors has been well-elucidated, but it is only recently becoming clear how nutrients, specifically amino acids, activate mTORC1. The presence of amino acids leads to the recruitment of mTORC1 from the cytosol to the surface of the lysosomal membrane, allowing it to be activated downstream of growth factors. This amino acid-induced translocation is mediated by the Rag GTPases and Ragulator (the scaffold for the Rag GTPases and mTORC1 on the lysosomal membrane). Here we describe the identification of two new components of Ragulator, HBXIP and c7orf59, that are required for the lysosomal localization of both the Rag GTPases and mTORC1 and that allowed us to identify new functions that Ragulator fulfills. We also characterized RagA-null mice and RagA-null mouse embryonic fibroblasts (MEFs). RagA is required for embryonic development, and, surprisingly, its deletion in adult mice leads to an expansion of monocytes. MEFs derived from RagA-null embryos display atypical, nutrient-insensitive mTORC1 activation. Finally, we identified c17orf59, a new Ragulator-interacting protein that inhibits the interaction between the Rag GTPases and Ragulator, inhibiting mTORC1 activation by amino acids. We report here our progress in characterizing the components of the amino acid-sensitive mTORC1 pathway and their physiological roles and we discuss the many open questions that remain to be studied regarding how amino acid sufficiency promotes the lysosomal localization of mTORC1.
by Lawrence D. Schweitzer.
Ph. D.

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Книги з теми "Acid-sensitive":

Bowman, J. J. Acid sensitive surface waters in Ireland: The impactof a major new sulphur emission on sensitive surface waters in an unacidified region. Dun Laoghaire: Environmental Research Unit, 1991.

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France, Robert. Use of sequential sampling of amphipod abundance to classify the biotic integrity of acid-sensitive lakes. [Toronto]: Environment Ontario, 1991.

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Yaworsky, Karen Lynne. Engagement of the insulin-sensitive pathway in the stimulation of glucose transport by [alpha]-lipoic acid. Ottawa: National Library of Canada, 1999.

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Donnelly, Eilish Teresa. An investigation of DNA repair in wild-type, amino acid auxotrophs and UV-sensitive mutants of Aspergillus nidulans. [s.l: The Author], 1995.

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Varodayan, Florence Prabha. Alcohol alters the expression of Soluble N-Ethylmaleimide-Sensitive Factor Attachment Protein Receptors (SNAREs) and spontaneous γ-Aminobutyric Acid (GABA) release... [New York, N.Y.?]: [publisher not identified], 2013.

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Brereton, Christine. Prediction of Crayfish (Cambarus bartoni, Cambarus robustus, Orconectes propinquus, and Orconectes virilis) presence in acid-sensitive, softwater lakes in and around Killarney Provincial Park. Sudbury, Ont: Laurentian University, Department of Geography, 1998.

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David, S. M. Long-term trends in the relative abundance of crayfish from acid sensitive, softwater lakes in South Central Ontario: A data summary for the first five years, 1988-1992. [Toronto?: Ontario, Ministry of Environment and Energy], 1994.

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Fiske, Steven. Macroinvertebrate survey of 25 soft water-pH sensitive lakes in Vermont. [Waterbury, Vt.?]: Special Studies & Surveillance Unit, Dept. of Environmental Conservation, 1987.

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Mewes, Hans-Werner. Schnelle Identifizierung von Peptiden durch sensitive Bestimmung ihrer Aminosäurezusammensetzung und Zugriff auf Sequenzdatenbanken. Gauting bei München: Intemann, 1989.

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Towards a fibre optic nucleic acid biosensor: Thiazole organge derivatives as sensitive fluorescent probes to detect DNA hybridization. Ottawa: National Library of Canada, 1998.

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Частини книг з теми "Acid-sensitive":

Kratz, Felix. "Acid-Sensitive Prodrugs of Doxorubicin." In Topics in Current Chemistry, 73–97. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/128_2007_5.

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Kamp, R. M. "Highly Sensitive Amino Acid Analysis." In Protein Structure Analysis, 231–48. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-642-59219-5_15.

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Brunsvold, W., W. Conley, W. Montgomery, and W. Moreau. "Acid-Sensitive Phenol—Formaldehyde Polymeric Resists." In ACS Symposium Series, 333–47. Washington, DC: American Chemical Society, 1993. http://dx.doi.org/10.1021/bk-1994-0537.ch022.

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Holzer, Peter. "Acid-Sensitive Ion Channels and Receptors." In Sensory Nerves, 283–332. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-79090-7_9.

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Penke, B., W. Gray, C. A. Hoeger, and J. Rivier. "Solid phase synthesis of acid-sensitive peptide amides." In Peptides, 261–63. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-010-9595-2_78.

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Inaki, Yoshiaki, Nobuo Matsumura, and Kiichi Takemoto. "Acid-Sensitive Pyrimidine Polymers for Chemical Amplification Resists." In ACS Symposium Series, 142–64. Washington, DC: American Chemical Society, 1993. http://dx.doi.org/10.1021/bk-1994-0537.ch010.

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Welch, E. B., D. E. Spyridakis, and T. Smayda. "Temporal Chemical Variability in Acid Sensitive High Elevation Lakes." In Acidic Precipitation, 1089–98. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-3385-9_109.

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Fjellheim, Arne, Åsmund Tysse, and Vilhelm Bjerknes. "Reappearance of Highly Acid-Sensitive Invertebrates after Liming of an Alpine Lake Ecosystem." In Acid rain 2000, 1391–96. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-007-0810-5_79.

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Brezonik, Patrick L., Lawrence A. Baker, and Todd E. Perry. "Mechanisms of Alkalinity Generation in Acid-Sensitive Soft Water Lakes." In Sources and Fates of Aquatic Pollutants, 229–60. Washington, DC: American Chemical Society, 1987. http://dx.doi.org/10.1021/ba-1987-0216.ch009.

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Joshi, Anju, and C. N. Tharamani. "Highly Sensitive Determination of Ascorbic Acid, Dopamine and Uric Acid Using Mesoporous Nitrogen Containing Carbon." In Biotechnology and Biochemical Engineering, 179–86. Singapore: Springer Singapore, 2016. http://dx.doi.org/10.1007/978-981-10-1920-3_20.

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Тези доповідей конференцій з теми "Acid-sensitive":

Liu, He, Danfeng Xiao, Keming Fan, Lifeng Jin, and Shilin Zhang. "Successful Acid Stimulation in Acid-sensitive Reservoirs." In Asia Pacific Oil and Gas Conference & Exhibition. Society of Petroleum Engineers, 2009. http://dx.doi.org/10.2118/121014-ms.

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Mayya, K. Subramanya, Yool Kang, Takahiro Yasue, Seok-Hwan Oh, Seong-Woon Choi, and Chan-Hoon Park. "EUV sensitive photo-acid generator sans chromophore." In SPIE Lithography Asia, edited by Alek C. Chen, Woo-Sung Han, Burn J. Lin, and Anthony Yen. SPIE, 2009. http://dx.doi.org/10.1117/12.837341.

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Peters, F. W., and R. E. Cooper. "A New Stimulation Technique for Acid-Sensitive Formations." In SPE Asia-Pacific Conference. Society of Petroleum Engineers, 1989. http://dx.doi.org/10.2118/19490-ms.

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Sekiguchi, Atsushi, Yoko Matsumoto, Hiroko Konishi, Kengo Moriyasu, and Yukihiro Morimoto. "Analysis of the generating action of the acid from PAG using acid sensitive dyes." In SPIE Advanced Lithography, edited by Robert D. Allen and Mark H. Somervell. SPIE, 2011. http://dx.doi.org/10.1117/12.879199.

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Kim, Jungju, In Sook Kim, Soon Jung Hwang, Ho Chul Kim, Yongdoo Park, and Kyung Sun. "Bone regeneration using MMP sensitive-hyaluronic acid based hydrogels." In 2009 IEEE 35th Annual Northeast Bioengineering Conference. IEEE, 2009. http://dx.doi.org/10.1109/nebc.2009.4967789.

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Wang, Yanqiao, Liusheng Chen, Ruisong Ding, Zhenwen Di, Jinhuan Du, Guanglin Zheng, and Jinwei Zhou. "Acid-sensitive color-changing recording material for electronic imaging." In Photonics West '98 Electronic Imaging, edited by Divyendu Sinha. SPIE, 1998. http://dx.doi.org/10.1117/12.302423.

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Sekiguchi, Atsushi, Yoko Matsumoto, and John J. Biafore. "Analysis of acid-generating action of PAG in an EUV resist using acid-sensitive dyes." In SPIE Advanced Lithography, edited by Mark H. Somervell. SPIE, 2013. http://dx.doi.org/10.1117/12.2012106.

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Zhang, Bailin, Shatha Dallo, Ralph Peterson, Syed Hussain, Tao Weitao, and Jing Yong Ye. "Development of a Highly Sensitive Label-Free Nucleic Acid Biosensor." In Biomedical Optics. Washington, D.C.: OSA, 2012. http://dx.doi.org/10.1364/biomed.2012.bsu3a.5.

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Ito, Hiroshi, Lester A. Pederson, Kaolin N. Chiong, Susan Sonchik, and Cecilia Tsai. "Sensitive Electron Beam Resist Systems Based On Acid-Catalyzed Deprotection." In 1989 Microlithography Conferences, edited by Elsa Reichmanis. SPIE, 1989. http://dx.doi.org/10.1117/12.953013.

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Song, Yusheng, Jiabao Zheng, Shipeng Wang, Like Li, and Yanan Zhang. "Plug-in Highly-sensitive pH Sensor Based on Polyacrylic Acid-chitosan Sensitive Film Coated Optical Fiber." In 2022 IEEE 14th International Conference on Advanced Infocomm Technology (ICAIT). IEEE, 2022. http://dx.doi.org/10.1109/icait56197.2022.9862762.

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Звіти організацій з теми "Acid-sensitive":

Campobasso, Marissa, Musa Ibrahim, Amanda Chisholm, Julia Miazek, and Martin Page. pH pivoting for algae coagulation : bench-scale experimentation. Engineer Research and Development Center (U.S.), May 2024. http://dx.doi.org/10.21079/11681/48611.

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Harmful algal blooms (HABs) threaten recreational waters and public supplies across the US, causing detrimental economic and environmental effects to communities. HABs can be mitigated with dissolved air flotation (DAF) treatment, which requires addition of pH-sensitive charged chemicals to neutralize algae, allowing them to attach to microbubbles and float to the surface. During HAB events and photosynthesis, algae raise the pH to levels that are not ideal for DAF. Traditionally, pH is reduced with a strong acid; however, this adds operational cost and permanently adjusts the water’s pH. This study assessed an approach that might allow for infusing CO₂ from diesel-powered electricity generators into the water prior to DAF treatment. It was hypothesized that formation of carbonic acid could temporarily reduce the pH. Results showed that 2.5%–5.0% CO₂ mixed within compressed air can achieve pH levels between 6–7 in algal water with an initial pH of 9–11 and alkalinity of 150 mg/L as CaCO₃. Further, dosing CO₂ before chemical addition yielded a 31% improvement in water clarification. Returning the pH back to natural levels was not achieved using ambient air microbubbles; however, coarse bubble air spargers should be tested to provide more volumetric capacity for CO₂ absorption.

Barefoot, Susan, Benjamin Juven, Thomas Hughes, Avraham Lalazar, A. B. Bodine, Yitzhak Ittah, and Bonita Glatz. Characterization of Bacteriocins Produced by Food Bioprocessing Propionobacteria. United States Department of Agriculture, August 1992. http://dx.doi.org/10.32747/1992.7561061.bard.

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Objectives were to further characterize activity spectra of dairy propionibacteria bacteriocins, jenseniin G and propionicin PLG-1, purify them, examine the role of cell walls in resistance, examine their interactions with cytoplasmic membrane, explain producer immunity, and clone the responsible genes. Inhibitory spectra of both bacteriocins were further characterized. Propionicin was most effective in controlling Gram-positive, rather than Gram-negative organisms; it controlled growth of sensitive cells both in a culture medium and a model food system. Jenseniin inhibited yogurt cultures and may help prevent yogurt over-acidification. Both were active against botulinal spores; jenseniin was sporostatic; propionicin was sporicidal. Jenseniin was produced in broth culture, was stable to pH and temperature extremes, and was purified. Its molecular mass (3649 Da) and partial amino acid composition (74%) were determined. A blocked jenseniin N-terminus prevented sequencing. Methods to produce propionicin in liquid culture were improved, and large scale culture protocols to yield high titers were developed. Methods to detect and quantify propionicin activity were optimized and standardized. Stability of partially purified propionicin was demonstrated and an improved purification scheme was developed. Purified propionicin had a 9328-Da molecular mass, contained 99 amino acids, and was significantly hydrophobic; ten N-terminal amino acids were identified. Propionicin and Jenseniin interacted with cytoplasmic membranes; resistance of insensitive species was cell wall-related. Propionicin and jenseniin acted similarly; their mode of action appeared to differ from nisin. Spontaneous jenseniin-resistant mutants were resistant to propionicin but nisin-sensitive. The basis for producer immunity was not resolved. Although bacteriocin genes were not cloned, a jenseniin producer DNA clone bank and three possible vectors for cloning genes in propionibacteria were constructed. In addition, transposon Tn916 was conjugatively transferred to the propionicin producer from chromosomal and plasmid locations at transfer frequencies high enough to permit use of Tn916 for insertional mutagenesis or targeting genes in propionibacteria. The results provide information about the bacteriocins that further supports their usefulness as adjuncts to increase food safety and/or quality.

Mevarech, Moshe, Jeremy Bruenn, and Yigal Koltin. Virus Encoded Toxin of the Corn Smut Ustilago Maydis - Isolation of Receptors and Mapping Functional Domains. United States Department of Agriculture, September 1995. http://dx.doi.org/10.32747/1995.7613022.bard.

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Ustilago maydis is a fungal pathogen of maize. Some strains of U. maydis encode secreted polypeptide toxins capable of killing other susceptible strains of U. maydis. Resistance to the toxins is conferred by recessive nuclear genes. The toxins are encoded by genomic segments of resident double-strande RNA viruses. The best characterized toxin, KP6, is composed of two polypeptides, a and b, which are not covalently linked. It is encoded by P6M2 dsRNA, which has been cloned, sequenced and expressed in a variety of systems. In this study we have shown that the toxin acts on the membranes of sensitive cells and that both polypeptides are required for toxin activity. The toxin has been shown to function by creating new pores in the cell membrane and disrupting ion fluxes. The experiments performed on artificial phospholipid bilayers indicated that KP6 forms large voltage-independent, cation-selective channels. Experiments leading to the resolution of structure-function relationship of the toxin by in vitro analysis have been initiated. During the course of this research the collaboration also yielded X-ray diffracion data of the crystallized a polypeptide. The effect of the toxin on the pathogen has been shown to be receptor-mediated. A potential receptor protein, identified in membrane fractions of sensitive cells, was subjected to tryptic hydrolysis followed by amino-acid analysis. The peptides obtained were used to isolate a cDNA fragment by reverse PCR, which showed 30% sequence homology to the human HLA protein. Analysis of other toxins secreted by U. maydis, KP1 and KP4, have demonstrated that, unlike KP6, they are composed of a single polypeptide. Finally, KP6 has been expressed in transgenic tobacco plants, indicating that accurate processing by Kex2p-like activity occurs in plants as well. Using tobacco as a model system, we determined that active antifungal toxins can be synthesized and targeted to the outside of transgenic plant cells. If this methodology can be applied to other agronomically crop species, then U. maydis toxins may provide a novel means for biological control of pathogenic fungi.

Hochman, Ayala, Thomas Nash III, and Pamela Padgett. Physiological and Biochemical Characterization of the Effects of Oxidant Air Pollutants, Ozone and Gas-phase Nitric Acid, on Plants and Lichens for their Use as Early Warning Biomonitors of these Air Pollutants. United States Department of Agriculture, January 2011. http://dx.doi.org/10.32747/2011.7697115.bard.

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Introduction. Ozone and related oxidants are regarded as the most important phytotoxic air pollutant in many parts of the western world. A previously unrecognized component of smog, nitric acid, may have even greater deleterious effects on plants either by itself or by augmenting ozone injury. The effects of ozone on plants are well characterized with respect to structural and physiological changes, but very little is known about the biochemical changes in plants and lichens exposed to ozone and/or HNO3. Objectives.To compare and contrast the responses of crop plants and lichens to dry deposition of HNO3 and O3., separately, and combined in order to assess our working hypothesis that lichens respond to air pollution faster than plants. Lichens are most suitable for use as biomonitors because they offer a live-organism-based system that does not require maintenance and can be attached to any site, without the need for man-made technical support systems. Original Immediate aims To expose the tobacco (Nicotiana tabacum L.) cultivar Bel-W3 that is ozone supersensitive and the ozone sensitive red kidney bean (Phaseolusvulgaris) and the lichen Ramalinamenziesii to controlled HNO3 and O3 fumigations and combined and to follow the resulting structural, physiological and biochemical changes, with special reference to reactive oxygen species related parameters. Revised. Due to technical problems and time limitations we studied the lichen Ramalinamenziesii and two cultivar of tobacco: Bel-W3 that is ozone supersensitive and a resistant cultivar, which were exposed to HNO3 and O3 alone (not combined). Methodology. Plants and lichens were exposed in fumigation experiments to HNO3 and O3, in constantly stirred tank reactors and the resulting structural, physiological and biochemical changes were analyzed. Results. Lichens. Exposure of Ramalinamenziesiito HNO3 resulted in cell membrane damage that was evident by 14 days and continues to worsen by 28 days. Chlorophyll, photosynthesis and respiration all declined significantly in HNO3 treatments, with the toxic effects increasing with dosage. In contrast, O3 fumigations of R. menziesii showed no significant negative effects with no differences in the above response variables between high, moderate and low levels of fumigations. There was a gradual decrease in catalase activity with increased levels of HNO3. The activity of glutathione reductase dropped to 20% in thalli exposed to low HNO3 but increased with its increase. Glucose 6-phosphate dehydrogenase activity increase by 20% with low levels of the pollutants but decreased with its increase. Tobacco. After 3 weeks of exposure of the sensitive tobacco cultivar to ozone there were visible symptoms of toxicity, but no danmage was evident in the tolerant cultivar. Neither cultivar showed any visible symptoms after exposure to HNO3.In tobacco fumigated with O3, there was a significant decrease in maximum photosynthetic CO2 assimilation and stomatal conductance at high levels of the pollutant, while changes in mesophyll conductance were not significant. However, under HNO3 fumigation there was a significant increase in mesophyll conductance at low and high HNO3 levels while changes in maximum photosynthetic CO2 assimilation and stomatal conductance were not significant. We could not detect any activity of the antioxidant enzymes in the fumigated tobacco leaves. This is in spite of the fact that we were able to assay the enzymes in tobacco leaves grown in Israel. Conclusions. This project generated novel data, and potentially applicable to agriculture, on the differential response of lichens and tobacco to HNO3 and O3 pollutants. However, due to experimental problems and time limitation discussed in the body of the report, our data do not justify yet application for a full, 4-year grant. We hope that in the future we shall conduct more experiments related to our objectives, which will serve as a basis for a larger scale project to explore the possibility of using lichens and/or plants for biomonitoring of ozone and nitric acid air pollution.

Porat, Ron, Gregory T. McCollum, Amnon Lers, and Charles L. Guy. Identification and characterization of genes involved in the acquisition of chilling tolerance in citrus fruit. United States Department of Agriculture, December 2007. http://dx.doi.org/10.32747/2007.7587727.bard.

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Citrus, like many other tropical and subtropical fruit are sensitive to chilling temperatures. However, application of a pre-storage temperature conditioning (CD) treatment at 16°C for 7 d or of a hot water brushing (HWB) treatment at 60°C for 20 sec remarkably enhances chilling tolerance and reduces the development of chilling injuries (CI) upon storage at 5°C. In the current research, we proposed to identify and characterize grapefruit genes that are induced by CD, and may contribute to the acquisition of fruit chilling tolerance, by two different molecular approaches: cDNA array analysis and PCR cDNA subtraction. In addition, following the recent development and commercialization of the new Affymetrix Citrus Genome Array, we further performed genome-wide transcript profiling analysis following exposure to CD and chilling treatments. To conduct the cDNA array analysis, we constructed cDNA libraries from the peel tissue of CD- and HWB-treated grapefruit, and performed an EST sequencing project including sequencing of 3,456 cDNAs from each library. Based on the obtained sequence information, we chose 70 stress-responsive and chilling-related genes and spotted them on nylon membranes. Following hybridization the constructed cDNA arrays with RNA probes from control and CD-treated fruit and detailed confirmations by RT-PCR analysis, we found that six genes: lipid-transfer protein, metallothionein-like protein, catalase, GTP-binding protein, Lea5, and stress-responsive zinc finger protein, showed higher transcript levels in flavedo of conditioned than in non-conditioned fruit stored at 5 ᵒC. The transcript levels of another four genes: galactinol synthase, ACC oxidase, temperature-induced lipocalin, and chilling-inducible oxygenase, increased only in control untreated fruit but not in chilling-tolerant CD-treated fruit. By PCR cDNA subtraction analysis we identified 17 new chilling-responsive and HWB- and CD-induced genes. Overall, characterization of the expression patterns of these genes as well as of 11 more stress-related genes by RNA gel blot hybridizations revealed that the HWB treatment activated mainly the expression of stress-related genes(HSP19-I, HSP19-II, dehydrin, universal stress protein, EIN2, 1,3;4-β-D-glucanase, and SOD), whereas the CD treatment activated mainly the expression of lipid modification enzymes, including fatty acid disaturase2 (FAD2) and lipid transfer protein (LTP). Genome wide transcriptional profiling analysis using the newly developed Affymetrix Citrus GeneChip® microarray (including 30,171 citrus probe sets) revealed the identification of three different chilling-related regulons: 1,345 probe sets were significantly affected by chilling in both control and CD-treated fruits (chilling-response regulon), 509 probe sets were unique to the CD-treated fruits (chilling tolerance regulon), and 417 probe sets were unique to the chilling-sensitive control fruits (chilling stress regulon). Overall, exposure to chilling led to expression governed arrest of general cellular metabolic activity, including concretive down-regulation of cell wall, pathogen defense, photosynthesis, respiration, and protein, nucleic acid and secondary metabolism. On the other hand, chilling enhanced various adaptation processes, such as changes in the expression levels of transcripts related to membranes, lipid, sterol and carbohydrate metabolism, stress stimuli, hormone biosynthesis, and modifications in DNA binding and transcription factors.

Friedman, Haya, Chris Watkins, Susan Lurie, and Susheng Gan. Dark-induced Reactive Oxygen Species Accumulation and Inhibition by Gibberellins: Towards Inhibition of Postharvest Senescence. United States Department of Agriculture, December 2009. http://dx.doi.org/10.32747/2009.7613883.bard.

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Dark-induced senescence could pose a major problem in export of various crops including cuttings. The assumption of this work was that ROS which is increased at a specific organelle can serve as a signal for activation of cell senescence program. Hormones which reduce senescence in several crops like gibberellic acid (GA) and possibly cytokinin (CK) may reduce senescence by inhibiting this signal. In this study we worked on Pelargonium cuttings as well as Arabidopsis rosette. In Pelargonium the increase in ROS occurred concomitantly with increase in two SAGs, and the increase persisted in isolated chloroplasts. In Arabidopsis we used two recentlydeveloped technologies to examine these hypotheses; one is a transcriptome approach which, on one hand, enabled to monitor expression of genes within the antioxidants network, and on the other hand, determine organelle-specific ROS-related transcriptome footprint. This last approach was further developed to an assay (so called ROSmeter) for determination of the ROS-footprint resulting from defined ROS stresses. The second approach involved the monitoring of changes in the redox poise in different organelles by measuring fluorescence ratio of redox-sensitive GFP (roGFP) directed to plastids, mitochondria, peroxisome and cytoplasm. By using the roGFP we determined that the mitochondria environment is oxidized as early as the first day under darkness, and this is followed by oxidation of the peroxisome on the second day and the cytoplast on the third day. The plastids became less oxidized at the first day of darkness and this was followed by a gradual increase in oxidation. The results with the ROS-related transcriptome footprint showed early changes in ROS-related transcriptome footprint emanating from mitochondria and peroxisomes. Taken together these results suggest that the first ROS-related change occurred in mitochondria and peroxisomes. The analysis of antioxidative gene’s network did not yield any clear results about the changes occurring in antioxidative status during extended darkness. Nevertheless, there is a reduction in expression of many of the plastids antioxidative related genes. This may explain a later increase in the oxidation poise of the plastids, occurring concomitantly with increase in cell death. Gibberellic acid (GA) prevented senescence in Pelargonium leaves; however, in Arabidopsis it did not prevent chlorophyll degradation, but prevented upregulation of SAGs (Apendix Fig. 1). Gibberellic acid prevented in Pelargonium the increase in ROS in chloroplast, and we suggested that this prevents the destruction of the chloroplasts and hence, the tissue remains green. In Arabidopsis, reduction in endogenous GA and BA are probably not causing dark-induced senescence, nevertheless, these materials have some effect at preventing senescence. Neither GA nor CK had any effect on transcriptome footprint related to ROS in the various organelles, however while GA reduced expression of few general ROS-related genes, BA mainly prevented the decrease in chloroplasts genes. Taken together, GA and BA act by different pathways to inhibit senescence and GA might act via ROS reduction. Therefore, application of both hormones may act synergistically to prevent darkinduced senescence of various crops.

Shapira, Roni, Judith Grizzle, Nachman Paster, Mark Pines, and Chamindrani Mendis-Handagama. Novel Approach to Mycotoxin Detoxification in Farm Animals Using Probiotics Added to Feed Stuffs. United States Department of Agriculture, May 2010. http://dx.doi.org/10.32747/2010.7592115.bard.

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T-2 toxin, a toxic product belongs to the trichothecene mycotoxins, attracts major interest because of its severe detrimental effects on the health of human and farm animals. The occurrence of trichothecenes contamination is global and they are very resistant to physical or chemical detoxification techniques. Trichothecenes are absorbed in the small intestine into the blood stream. The hypothesis of this project was to develop a protecting system using probiotic bacteria that will express trichothecene 3-O-acetyltransferase (Tri101) that convert T-2 to a less toxic intermediate to reduce ingested levels in-situ. The major obstacle that we had faced during the project is the absence of stable and efficient expression vectors in probiotics. Most of the project period was invested to screen and isolate strong promoter to express high amounts of the detoxify enzyme on one hand and to stabilize the expression vector on the other hand. In order to estimate the detoxification capacity of the isolated promoters we had developed two very sensitive bioassays.The first system was based on Saccharomyces cerevisiae cells expressing the green fluorescent protein (GFP). Human liver cells proliferation was used as the second bioassay system.Using both systems we were able to prove actual detoxification on living cells by probiotic bacteria expressing Tri101. The first step was the isolation of already discovered strong promoters from lactic acid bacteria, cloning them downstream the Tri101 gene and transformed vectors to E. coli, a lactic acid bacteria strain Lactococcuslactis MG1363, and a probiotic strain of Lactobacillus casei. All plasmid constructs transformed to L. casei were unstable. The promoter designated lacA found to be the most efficient in reducing T-2 from the growth media of E. coli and L. lactis. A prompter library was generated from L. casei in order to isolate authentic probiotic promoters. Seven promoters were isolated, cloned downstream Tri101, transformed to bacteria and their detoxification capability was compared. One of those prompters, designated P201 showed a relatively high efficiency in detoxification. Sequence analysis of the promoter region of P201 and another promoter, P41, revealed the consensus region recognized by the sigma factor. We further attempted to isolate an inducible, strong promoter by comparing the protein profiles of L. casei grown in the presence of 0.3% bile salt (mimicking intestine conditions). Six spots that were consistently overexpressed in the presence of bile salts were isolated and identified. Their promoter reigns are now under investigation and characterization.

Zhou, Ting, Roni Shapira, Peter Pauls, Nachman Paster, and Mark Pines. Biological Detoxification of the Mycotoxin Deoxynivalenol (DON) to Improve Safety of Animal Feed and Food. United States Department of Agriculture, July 2010. http://dx.doi.org/10.32747/2010.7613885.bard.

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The trichothecene deoxynivalenol (DON, vomitoxin), one of the most common mycotoxin contaminants of grains, is produced by members of the Fusarium genus. DON poses a health risk to consumers and impairs livestock performance because it causes feed refusal, nausea, vomiting, diarrhea, hemolytic effects and cellular injury. The occurrence of trichothecenes contamination is global and they are very resistant to physical or chemical detoxification techniques. Trichothecenes are absorbed in the small intestine into the blood stream. The overall objective of this project was to develop a protecting system using probiotic bacteria that will express trichothecene 3-O-acetyltransferase (Tri101) that convert T-2 to a less toxic intermediate to reduce ingested levels in-situ. The major obstacle that we had faced during the project is the absence of stable and efficient expression vectors in probiotics. Most of the project period was invested to screen and isolate strong promoter to express high amounts of the detoxify enzyme on one hand and to stabilize the expression vector on the other hand. In order to estimate the detoxification capacity of the isolated promoters we had developed two very sensitive bioassays.The first system was based on Saccharomyces cerevisiae cells expressing the green fluorescent protein (GFP). Human liver cells proliferation was used as the second bioassay system.Using both systems we were able to prove actual detoxification on living cells by probiotic bacteria expressing Tri101. The first step was the isolation of already discovered strong promoters from lactic acid bacteria, cloning them downstream the Tri101 gene and transformed vectors to E. coli, a lactic acid bacteria strain Lactococcuslactis MG1363, and a probiotic strain of Lactobacillus casei. All plasmid constructs transformed to L. casei were unstable. The promoter designated lacA found to be the most efficient in reducing T-2 from the growth media of E. coli and L. lactis. A prompter library was generated from L. casei in order to isolate authentic probiotic promoters. Seven promoters were isolated, cloned downstream Tri101, transformed to bacteria and their detoxification capability was compared. One of those prompters, designated P201 showed a relatively high efficiency in detoxification. Sequence analysis of the promoter region of P201 and another promoter, P41, revealed the consensus region recognized by the sigma factor. We further attempted to isolate an inducible, strong promoter by comparing the protein profiles of L. casei grown in the presence of 0.3% bile salt (mimicking intestine conditions). Six spots that were consistently overexpressed in the presence of bile salts were isolated and identified. Their promoter reigns are now under investigation and characterization.

Locy, Robert D., Hillel Fromm, Joe H. Cherry, and Narendra K. Singh. Regulation of Arabidopsis Glutamate Decarboxylase in Response to Heat Stress: Modulation of Enzyme Activity and Gene Expression. United States Department of Agriculture, January 2001. http://dx.doi.org/10.32747/2001.7575288.bard.

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Most plants accumulate the nonprotein amino acid, g-aminobutyric acid (GABA), in response to heat stress. GABA is made from glutamate in a reaction catalyzed by glutamate decarboxylase (GAD), an enzyme that has been shown by the Israeli PI to be a calmodulin (CaM) binding protein whose activity is regulated in vitro by calcium and CaM. In Arabidopsis there are at least 5 GAD genes, two isoforms of GAD, GAD1 and GAD2, are known to be expressed, both of which appear to be calmodulin-binding proteins. The role of GABA accumulation in stress tolerance remains unclear, and thus the objectives of the proposed work are intended to clarify the possible roles of GABA in stress tolerance by studying the factors which regulate the activity of GAD in vivo. Our intent was to demonstrate the factors that mediate the expression of GAD activity by analyzing the promoters of the GAD1 and GAD2 genes, to determine the role of stress induced calcium signaling in the regulation of GAD activity, to investigate the role of phosphorylation of the CaM-binding domain in the regulation of GAD activity, and to investigate whether ABA signaling could be involved in GAD regulation via the following set of original Project Objectives: 1. Construction of chimeric GAD1 and GAD2 promoter/reporter gene fusions and their utilization for determining cell-specific expression of GAD genes in Arabidopsis. 2. Utilizing transgenic plants harboring chimeric GAD1 promoter-luciferase constructs for isolating mutants in genes controlling GAD1 gene activation in response to heat shock. 3. Assess the role of Ca2+/CaM in the regulation of GAD activity in vivo in Arabidopsis. 4. Study the possible phosphorylation of GAD as a means of regulation of GAD activity. 5. Utilize ABA mutants of Arabidopsis to assess the involvement of this phytohormone in GAD activation by stress stimuli. The major conclusions of Objective 1 was that GAD1 was strongly expressed in the elongating region of the root, while GAD2 was mainly expressed along the phloem in both roots and shoots. In addition, GAD activity was found not to be transcriptionally regulated in response to heat stress. Subsequently, The Israeli side obtained a GAD1 knockout mutation, and in light of the objective 1 results it was determined that characterization of this knockout mutation would contribute more to the project than the proposed Objective 2. The major conclusion of Objective 3 is that heat-stress-induced changes in GAD activity can be explained by heat-stress-induced changes in cytosolic calcium levels. No evidence that GAD activity was transcriptionally or translationally regulated or that protein phosphorylation was involved in GAD regulation (objective 4) was obtained. Previously published data by others showing that in wheat roots ABA regulated GABA accumulation proved not to be the case in Arabidopsis (Objective 5). Consequently, we put the remaining effort in the project into the selection of mutants related to temperature adaptation and GABA utilization and attempting to characterize events resulting from GABA accumulation. A set of 3 heat sensitive mutants that appear to have GABA related mutations have been isolated and partially characterized, and a study linking GABA accumulation to growth stimulation and altered nitrate assimilation were conducted. By providing a better understanding of how GAD activity was and was not regulated in vivo, we have ruled out the use of certain genes for genetically engineering thermotolerance, and suggested other areas of endeavor related to the thrust of the project that may be more likely approaches to genetically engineering thermotolerance.

Carpita, Nicholas C., Ruth Ben-Arie, and Amnon Lers. Pectin Cross-Linking Dynamics and Wall Softening during Fruit Ripening. United States Department of Agriculture, July 2002. http://dx.doi.org/10.32747/2002.7585197.bard.

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Our study was designed to elucidate the chemical determinants of pectin cross-linking in developing fruits of apple and peach and to evaluate the role of breakage cross-linkages in swelling, softening, and cell separation during the ripening. Peaches cell walls soften and swell considerably during the ripening, whereas apples fruit cells maintain wall firmness but cells separate during late stages of ripening. We used a "double-reduction" technique to show that levels of non-methyl esters of polyuronic acid molecules were constant during the development and ripening and decreased only in overripe fruit. In peach, methyl and non-methyl esters increased during the development and decreased markedly during the ripening. Non-methyl ester linkages in both fruit decreased accompanied fruit softening. The identity of the second component of the linkage and its definitive role in the fruit softening remain elusive. In preliminary examination of isolated apples cell walls, we found that phenolic compounds accumulate early in wall development but decrease markedly during ripening. Quantitative texture analysis was used to correlate with changes to wall chemistry from the fresh-picked ripe stage to the stage during storage when the cell separation occurs. Cell wall composition is similar in all cultivars, with arabinose as the principal neutral sugar. Extensive de-branching of these highly branched arabinans pre-stages softening and cell-cell separation during over-ripening of apple. The longer 5-arabinans remain attached to the major pectic polymer rhamnogalacturonan I (RG I) backbone. The degree of RG I branching, as judged from the ratios of 2-Rha:2,4-Rha, also decreases, specially after an extensive arabinan de-branching. Loss of the 4-Rham linkages correlated strongly with the softening of the fruit. Loss of the monomer or polymer linked to the RG I produce directly or indirectly the softening of the fruit. This result will help to understand the fruit softening and to have better control of the textural changes in fruit during the ripening and especially during the storage. 'Wooliness', an undesirable mealy texture that is induced during chilling of some peach cultivars, greatly reduces the fruit storage possibilities. In order to examine the hypothesis that the basis for this disorder is related to abnormality in the cell wall softening process we have carried out a comparative analysis using the resistant cultivar, Sunsnow, and a sensitive one, Hermosa. We investigated the activity of several pectin- and glycan-modifying enzymes and the expression of their genes during ripening, chilling, and subsequent shelf-life. The changes in carbohydrate status and in methyl vs. non-methyl uronate ester levels in the walls of these cultivars were examined as well to provide a basis for comparison of the relevant gene expression that may impact appearance of the wooly character. The activities of the specific polygalacturonase (PGase) and a CMC-cellulase activities are significantly elevated in walls of peaches that have become wooly. Cellulase activities correlated well with increased level of the transcript, but differential expression of PGase did not correspond with the observed pattern of mRNA accumulation. When expression of ethylene biosynthesis related genes was followed no significant differences in ACC synthase gene expression was observed in the wooly fruit while the normal activation of the ACC oxidase was partially repressed in the Hermosa wooly fruits. Normal ripening-related loss of the uronic acid-rich polymers was stalled in the wooly Hermosa inconsistent with the observed elevation in a specific PGase activity but consistent with PG gene expression. In general, analysis of the level of total esterification, degree of methyl esterification and level of non-methyl esters did not reveal any major alterations between the different fruit varieties or between normal and abnormal ripening. Some decrease in the level of uronic acids methyl esterification was observed for both Hermosa and Sunsnow undergoing ripening following storage at low temperature but not in fruits ripening after harvest. Our results support a role for imbalanced cell wall degradation as a basis for the chilling disorder. While these results do not support a role for the imbalance between PG and pectin methyl esterase (PME) activities as the basis for the disorder they suggest a possible role for imbalance between cellulose and other cell wall polymer degradation during the softening process.