- Seminars - maillist.psb.ugent.be

PSB event reminder
by contact＠psb.vib-ugent.be 02 Jul '12

02 Jul '12

Calendar Name: seminars Scheduled for: Monday, July 2 2012, 11:00 - 12:30 Event text: Dr Javier Palatnik IBR (Instituto de Biologia Molecuar y Celular de Rosario) Rosario ARGENTINA Details: �microRNA biogenesis and function in plants� ABSTRACT MicroRNAs are small RNAs of ~21 nt that recognize partially complementary sites in target mRNAs and guide them to cleavage or translational arrest. The microRNAs are distinguished from other small RNAs by their unique biogenesis, which involves a precise excision from the stem of a fold-back precursor located in a long primary transcript. The type III ribonuclease DICER-LIKE1 (DCL1) with the aid of the accessory proteins cleaves the precursors to release the microRNAs. However, plant microRNA precursors come in variable sizes and shapes, and we are interested in understanding how these different precursors can be processed to generate the mature microRNAs. We have found that many precursors are processed in a base-to-loop direction, while others are processed by a non-canonical loop-to-base mechanism. We use a combination of approaches to study microRNA processing, including the analysis of libraries of random mutant precursors and the identification of processing intermediates with the aid of next generation sequencing techniques. In plants, many of the evolutionary conserved miRNAs regulate transcription factors, which in turn play key biological functions. Perturbation of these miRNA regulatory networks, by mutations in microRNA encoding genes or by interference with their activity usually causes severe developmental defects. We are interested in identifying the targets of plant microRNAs, as well as their biological functions. The lab specifically focuses in the control of cell proliferation and differentiation by two microRNAs, miR396 and miR319. Related Publications: Bologna, N.G., Mateos, J., Bresso, E.G., and Palatnik, J.F.. (2009) A loop-to-base processing mechanism underlies the biogenesis of plant microRNAs miR319 and miR159. EMBO J, 28:3646-56. Mateos, J., Bologna, N.G., Chorostecki, U., and Palatnik, J.F. (2010) Identification of Structural Determinants for MicroRNA Processing in Plants by Random Mutagenesis of MIR172a Precursor. Current Biology, 20:49-54. Rodriguez, R., Mecchia, M., Debernardi, J.M., Schommer, C., Weigel, D., and Palatnik, J.F. (2010) Control of cell proliferation by microRNA miR396. Development, 137:103-12. Debernardi, J.M., Rodriguez, R.E., Mecchia, M., and Palatnik, J.F. (2012) Functional specialization of the plant miR396 regulatory network through distinct microRNA-target interactions, PLoS Genetics, 8: e1002419. Chorostecki, U., Crosa, V.C., Lodeyro, A.F., Bologna, N.G., Martin, A.P., Carrillo, C., Schommer, C. and Palatnik, J.F. (2012) Identification of new microRNA-regulated genes by conserved targeting in plant species, in press.

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PSB event reminder
by contact＠psb.vib-ugent.be 30 Jun '12

30 Jun '12

Calendar Name: seminars Scheduled for: Monday, July 2 2012, 11:00 - 12:30 Event text: Dr Javier Palatnik IBR (Instituto de Biologia Molecuar y Celular de Rosario) Rosario ARGENTINA Details: �microRNA biogenesis and function in plants� ABSTRACT MicroRNAs are small RNAs of ~21 nt that recognize partially complementary sites in target mRNAs and guide them to cleavage or translational arrest. The microRNAs are distinguished from other small RNAs by their unique biogenesis, which involves a precise excision from the stem of a fold-back precursor located in a long primary transcript. The type III ribonuclease DICER-LIKE1 (DCL1) with the aid of the accessory proteins cleaves the precursors to release the microRNAs. However, plant microRNA precursors come in variable sizes and shapes, and we are interested in understanding how these different precursors can be processed to generate the mature microRNAs. We have found that many precursors are processed in a base-to-loop direction, while others are processed by a non-canonical loop-to-base mechanism. We use a combination of approaches to study microRNA processing, including the analysis of libraries of random mutant precursors and the identification of processing intermediates with the aid of next generation sequencing techniques. In plants, many of the evolutionary conserved miRNAs regulate transcription factors, which in turn play key biological functions. Perturbation of these miRNA regulatory networks, by mutations in microRNA encoding genes or by interference with their activity usually causes severe developmental defects. We are interested in identifying the targets of plant microRNAs, as well as their biological functions. The lab specifically focuses in the control of cell proliferation and differentiation by two microRNAs, miR396 and miR319. Related Publications: Bologna, N.G., Mateos, J., Bresso, E.G., and Palatnik, J.F.. (2009) A loop-to-base processing mechanism underlies the biogenesis of plant microRNAs miR319 and miR159. EMBO J, 28:3646-56. Mateos, J., Bologna, N.G., Chorostecki, U., and Palatnik, J.F. (2010) Identification of Structural Determinants for MicroRNA Processing in Plants by Random Mutagenesis of MIR172a Precursor. Current Biology, 20:49-54. Rodriguez, R., Mecchia, M., Debernardi, J.M., Schommer, C., Weigel, D., and Palatnik, J.F. (2010) Control of cell proliferation by microRNA miR396. Development, 137:103-12. Debernardi, J.M., Rodriguez, R.E., Mecchia, M., and Palatnik, J.F. (2012) Functional specialization of the plant miR396 regulatory network through distinct microRNA-target interactions, PLoS Genetics, 8: e1002419. Chorostecki, U., Crosa, V.C., Lodeyro, A.F., Bologna, N.G., Martin, A.P., Carrillo, C., Schommer, C. and Palatnik, J.F. (2012) Identification of new microRNA-regulated genes by conserved targeting in plant species, in press.

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Seminar Dr Javier Palatnik 2/7
by Delphine Verspeel 22 Jun '12

22 Jun '12

You are receiving this e-mail because you subscribed to our seminars announcements and reminders service at <https://maillist.psb.ugent.be/mailman/listinfo/seminars> https://maillist.psb.ugent.be/mailman/listinfo/seminars. If you do not wish to receive this information anymore, please unsubscribe from future mailings at <https://maillist.psb.ugent.be/mailman/options/seminars> https://maillist.psb.ugent.be/mailman/options/seminars. cid:946540515@15122008-0D1C PSB cid:946540515@15122008-0D23 VIB - Department of Plant Systems Biology Technologiepark 927 B - 9052 Gent/Zwijnaarde Phone: +32 9 33 13 800 Fax: +32 9 33 13 809 Http://www.psb.vib-ugent.be

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Upcoming seminar July
by Delphine Verspeel 22 Jun '12

22 Jun '12

Dear All, Enclosed you can find our upcoming seminar for July. Kind regards, Delphine ___________________________________________ Delphine Verspeel Administrative Assistant VIB, Department of Plant Systems Biology Ghent University Technologiepark 927 9052 Gent Belgium Phone: +32/9/33.13.800 Fax: +32/9/33.13.809 Http://www.psb.ugent.be despe(a)psb.vib-ugent.be

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PSB event reminder
by contact＠psb.vib-ugent.be 21 Jun '12

21 Jun '12

Calendar Name: seminars Scheduled for: Thursday, June 21 2012, 11:00 - 12:30 Event text: Prof Pierre Hilson VIB, Dept. of Plant Systems Biology Ghent University Gent BELGIUM Details: �Signaling peptides regulate plant tropic growth and root development� ABSTRACT: Plant growth and development are coordinated by an array of intercellular signals, including phytohormones and secreted peptides. A cursory analysis of plant genomes suggests that the role of the latter class of molecules may still be underestimated. Furthermore, while both classes can be implicated in the same developmental processes, little is known about the interplay between phytohormone action and peptide signaling within the cellular microenvironment. We have shown that plant-specific genes coding for small secretory peptides, designated GOLVEN (GLV), modulate the distribution of the phytohormone auxin in Arabidopsis. The deregulation of the GLV function impairs the formation of auxin gradients via PIN proteins, thereby altering the reorientation of shoots and roots after a gravity stimulus, affecting meristem size, or preventing the proper development of lateral roots. We have also identified proteolytic enzymes important for the production of the bioactive GLV signal and will discuss their potential regulation. A complementary research project will be introduced. We have built a high-content screening platform to study the cellular phenotypes of isolated plant cells. This system has been optimized to track the proliferation of isolated Arabidopsis cells with high-throughput and robotized protocols. The properties of several molecules identified in large-scale screens will be described.

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PSB event reminder
by contact＠psb.vib-ugent.be 19 Jun '12

19 Jun '12

Calendar Name: seminars Scheduled for: Thursday, June 21 2012, 11:00 - 12:30 Event text: Prof Pierre Hilson VIB, Dept. of Plant Systems Biology Ghent University Gent BELGIUM Details: �Signaling peptides regulate plant tropic growth and root development� ABSTRACT: Plant growth and development are coordinated by an array of intercellular signals, including phytohormones and secreted peptides. A cursory analysis of plant genomes suggests that the role of the latter class of molecules may still be underestimated. Furthermore, while both classes can be implicated in the same developmental processes, little is known about the interplay between phytohormone action and peptide signaling within the cellular microenvironment. We have shown that plant-specific genes coding for small secretory peptides, designated GOLVEN (GLV), modulate the distribution of the phytohormone auxin in Arabidopsis. The deregulation of the GLV function impairs the formation of auxin gradients via PIN proteins, thereby altering the reorientation of shoots and roots after a gravity stimulus, affecting meristem size, or preventing the proper development of lateral roots. We have also identified proteolytic enzymes important for the production of the bioactive GLV signal and will discuss their potential regulation. A complementary research project will be introduced. We have built a high-content screening platform to study the cellular phenotypes of isolated plant cells. This system has been optimized to track the proliferation of isolated Arabidopsis cells with high-throughput and robotized protocols. The properties of several molecules identified in large-scale screens will be described.

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PSB event reminder
by contact＠psb.vib-ugent.be 15 Jun '12

15 Jun '12

Calendar Name: seminars Scheduled for: Friday, June 15 2012, 14:00 - 15:30 Event text: Prof Stanislaw M. Karpiński Dept. of Plant Genetics, Breeding & Biotechnology Faculty of Horticulture & Landscape Architecture Warsaw University of Life Sciences Warsaw POLAND Details: �Quantum-molecular, photo-electrochemical and algorithmic regulation of Darwinian fitness in Arabidopsis� ABSTRACT In a simplified model of photosynthesis, light energy absorbed by chlorophylls of photosystem II is distributed between photochemistry, fluorescence, and heat. Spectrally and time-resolved fluorescence combined with foliar heat dynamics measurements demonstrates that higher plants evolved genetic and physiological global regulatory system, which optimizes photosystem II quantum-molecular functions and the fate of photons absorbed in excess (1, 2). Our results indicate the role of the PsbS and the photosystem II antenna organization in efficient en discrete global regulation of the rates between photochemistry, fluorescence, and heat (3). This in turn specifically influences global electrochemical signalling and regulates growth, acclamatory and defense responses in Arabidopsis. Changes in phytochemistry, water use efficiency, hormonal and reactive oxygen species cellular homeostasis and seed yield of Arabidopsis can be defined by the exponential function and simple equation with natural logarithm (y = y0*e-Kx), that depends on molecular regulators: LESION SIMULATING DISEASE 1 (LSD1), ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1) and PHYTOALEXIN DEFICIENT 4 (PAD4) (4-8). The LSD1 recessive null mutant (lsd1) regardless of permissive laboratory or non-permissive laboratory and field conditions demonstrates constant seed yield, but significant variation in phytochemistry and water use efficiencies, and in foliar transcriptomes that depend on EDS1 and PAD4. Obtained results suggest that LSD1/EDS1/PAD4 constitute at least tree component molecular machinery regulating plant Darwinian fitness. Our experiments supported with mathematical modelling indicate that Arabidopsis plants perform discrete global regulation of the rates between photochemistry, fluorescence and heat, thus perform biological processing aimed at optimizing and integrating photosynthesis, water use efficiency, reactive oxygen species and hormonal cellular homeostasis. This processing allows to reach the best possible seed yield and Darwinian fitness in multivariable natural environment. 1. K. Asada, Annu. Rev. Plant Physiol. Plant Mol. Biol. 50:601-639 (1999). 2. S. Karpiński, et al., Science 284: 654-657 (1999). 3. Kulasek et al., submitted (2012) 4. Mateo et al., Plant Physiol. 136: 2818-3280 (2004) 5. Muhlenbock et al., Plant Cell 19: 3819-3830 (2007) 6. Muhlenbock et al., Plant Cell 20: 2339-2356 (2008) 7. Szechynska-Hebda et al., Plant Cell 22: 2201-2218 (2010) 8. Wituszyńska et al. submitted (2012)

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PSB event reminder
by contact＠psb.vib-ugent.be 13 Jun '12

13 Jun '12

Calendar Name: seminars Scheduled for: Friday, June 15 2012, 14:00 - 15:30 Event text: Prof Stanislaw M. Karpiński Dept. of Plant Genetics, Breeding & Biotechnology Faculty of Horticulture & Landscape Architecture Warsaw University of Life Sciences Warsaw POLAND Details: �Quantum-molecular, photo-electrochemical and algorithmic regulation of Darwinian fitness in Arabidopsis� ABSTRACT In a simplified model of photosynthesis, light energy absorbed by chlorophylls of photosystem II is distributed between photochemistry, fluorescence, and heat. Spectrally and time-resolved fluorescence combined with foliar heat dynamics measurements demonstrates that higher plants evolved genetic and physiological global regulatory system, which optimizes photosystem II quantum-molecular functions and the fate of photons absorbed in excess (1, 2). Our results indicate the role of the PsbS and the photosystem II antenna organization in efficient en discrete global regulation of the rates between photochemistry, fluorescence, and heat (3). This in turn specifically influences global electrochemical signalling and regulates growth, acclamatory and defense responses in Arabidopsis. Changes in phytochemistry, water use efficiency, hormonal and reactive oxygen species cellular homeostasis and seed yield of Arabidopsis can be defined by the exponential function and simple equation with natural logarithm (y = y0*e-Kx), that depends on molecular regulators: LESION SIMULATING DISEASE 1 (LSD1), ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1) and PHYTOALEXIN DEFICIENT 4 (PAD4) (4-8). The LSD1 recessive null mutant (lsd1) regardless of permissive laboratory or non-permissive laboratory and field conditions demonstrates constant seed yield, but significant variation in phytochemistry and water use efficiencies, and in foliar transcriptomes that depend on EDS1 and PAD4. Obtained results suggest that LSD1/EDS1/PAD4 constitute at least tree component molecular machinery regulating plant Darwinian fitness. Our experiments supported with mathematical modelling indicate that Arabidopsis plants perform discrete global regulation of the rates between photochemistry, fluorescence and heat, thus perform biological processing aimed at optimizing and integrating photosynthesis, water use efficiency, reactive oxygen species and hormonal cellular homeostasis. This processing allows to reach the best possible seed yield and Darwinian fitness in multivariable natural environment. 1. K. Asada, Annu. Rev. Plant Physiol. Plant Mol. Biol. 50:601-639 (1999). 2. S. Karpiński, et al., Science 284: 654-657 (1999). 3. Kulasek et al., submitted (2012) 4. Mateo et al., Plant Physiol. 136: 2818-3280 (2004) 5. Muhlenbock et al., Plant Cell 19: 3819-3830 (2007) 6. Muhlenbock et al., Plant Cell 20: 2339-2356 (2008) 7. Szechynska-Hebda et al., Plant Cell 22: 2201-2218 (2010) 8. Wituszyńska et al. submitted (2012)

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seminar 21/06 Prof Pierre Hilson
by Nathalie Vanden Hautte 11 Jun '12

11 Jun '12

You are receiving this e-mail because you subscribed to our seminars announcements and reminders service at https://maillist.psb.ugent.be/mailman/listinfo/seminars . If you do not wish to receive this information anymore, please unsubscribe from future mailings at https://maillist.psb.ugent.be/mailman/options/seminars . cid:946540515@15122008-0D1CPSBcid:946540515@15122008-0D23 VIB - Department of Plant Systems Biology Technologiepark 927 B - 9052 Gent/Zwijnaarde Phone: +32 9 33 13 800 Fax: +32 9 33 13 809 Http://www.psb.vib-ugent.be

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PSB event reminder
by contact＠psb.vib-ugent.be 07 Jun '12

07 Jun '12

Calendar Name: seminars Scheduled for: Thursday, June 7 2012, 11:00 - 12:30 Event text: Prof Gerrit Beemster Laboratory for Molecular Plant Physiology and Biotechnology University of Antwerp Antwerp BELGIUM Details: �Virtual Leaf 2.0: An improved tool to model plant growth regulation� ABSTRACT Virtual leaf is a software package that we developed for the simulation of hormone transport and growth regulation in multicellular plant organs. Over the last few years we have further refined this tool, so that we will be able to release a completely new version soon. Improvements encompass technical aspects such as a version tracking system for the software development, output to a standard format (hdf5) for import in external viewers and code optimization for faster performance. In terms of biology we have developed adaptations to enable the modelling of root tipgrowth. We also implemented more physiological realistic models for the regulation of cell expansion and cell division. Finally we have developed bifurcation analysis techniques to investigate the effect and importance of individual model parameters on the overall behaviour.

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