Seminarkalender

August 2016
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Seminare

Seminare

Das Max-Planck-Institut für Molekulare Pflanzenphysiologie hat regelmäßig herausragende Forscher zu Gast, die Vorträge über ihre aktuellen Projekte halten und so den Austausch unter den Wissenschaftlern fördern.

Eine Übersicht über die kommenden Veranstaltungen finden Sie hier. Seminare finden für gewöhnlich Mittwochs in der Zeit von 14:00 Uhr bis 15:30 Uhr im Seminarraum im Zentralgebäude (1.052 und 1.053) statt, Abweichungen in Zeit und Ort sind jedoch möglich.

September 2016

Milos Tanurdzic - Large genomes and small RNA: Transcriptome reprogramming by planthormone signaling in plant development

We are exploringhow plants execute and fine-tune their developmental programs in response tointernal and external cues that rely on plant hormone signaling. In particularwe are interested in the transcriptional and post-transcriptional regulationduring early developmental decisions, such as giberellic acid (GA)-regulatedsex determination in 3-6 cell fern gametophytes, or strigolactone (SL)-inducedrepression of branching via arrest of axillary meristems in garden pea. Ourexperimental approaches rely on next generation sequencing to identify andquantify coding and non-coding transcripts in plants without reference genomesequence (but otherwise excellent model organisms). I will illustrate how planthormones can have very different effects on gene expression throughoutdevelopment. In fern gametophytes GA induces extensive transcriptome (andlikely epigenome) reprogramming, where we discovered over 1100 genes affectedby GA, mostly up-regulated, including signatures of extensive chromatinremodeling, activation of several hormone signaling cascades, and extensivechanges in non-coding RNA, including microRNA, well before any morphologicaldifferences can be observed. In contrast, we found that SL induces small butvery fast and specific transcriptional responses in garden pea axillary buds,including several key transcription factors, implicating other hormonesignaling pathways, as well as post-transcriptional and post-translationalcontrol in the regulation of branching. [mehr]

Ilka Axmann - Career Talk

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October 2016

Dave Savage - Fixed: Systems and synthetic biological approaches for understanding photosynthetic CO2 fixation

Cells usestructure to catalyze and facilitate the chemical reactions of metabolism. Thisprinciple is exemplified by the process of carbon dioxide assimilation inphotosynthetic cyanobacteria, which coordinate myriad biochemical components inspace and time, in order to achieve a single physiological goal – convert solarpower into fixed chemical energy. An essential player in this process is thecarboxysome, a protein-based organelle composed of an icosahedral proteinshell, which encapsulates the enzymes RuBisCO and carbon anhydrase within a~100 nm structure. Despite knowledge of the overall structure of thecarboxysome, much less is known about the molecular interactions driving itsself-assembly and how this process is capable of occurring in the complex invivo environment. Here, I describe our biochemical efforts to elucidate amechanistic picture of how the carboxysome assembles and functions in the cell.At the same time, our lab is also interested in developing a holistic pictureof how a coordinated physiology emerges from the many different proteinactivities, including the carboxysome and numerous transporters, found incyanobacteria. To this end, I present our recent efforts at reconciling theseactivities using a mathematical reaction-diffusion model of carbon dioxideassimilation. Finally, a general challenge to studying physiology is the lowthroughput of assays for quantifying metabolism. I therefore conclude with ourefforts at using protein engineering for constructing fluorescent metabolitebiosensors and enabling high-throughput studies of metabolism.  [mehr]

Patricia Leon-Mejia - Chloroplastsignals that impact leaf development

Chloroplast signals that impactleaf developmentThe most conspicuousfunction of chloroplasts is photosynthesis. However, these organelles alsofunction as factories that synthesized a pletora of essential compounds forplant life. Chloroplasts are thus central an enviromental sensor of the cell,and this information is transmitted to the ncucleus through retrogradesignaling, modulating the expression of nuclear-genes to fine-tune the generalplant developmental and external responses. Recent advances have demonstratedthe existence of multiple retrograde signaling pathways, but only few signalsresponsible for this regulation have been identified.  In recent years,evidence has supported that apocarotenoids are important signals that regulatediverse aspects of plant and animal development. The characterization of an Arabidopsisclb5 mutant, impaired in early chloroplast development, provided geneticand molecular evidences that the accumulation of apocarotenoid profoundlyaffects nuclear and plastid gene expression as well as leaf development. Thealbino clb5 mutant of Arabidopsis displays a unique defect in themorphology of the leaf with radial shape and defects in leaf polarity, that isnot observed in other albino mutants supporting the idea that chloroplaststatus is tightly monitored and strongly correlated with leaf development.These phenotypes are a consequence of the defect in the zeta carotenedesaturase (ZDS) activity that results in the accumulation of phytofluene andz-carotenoid intermediates. Our work also demonstrates that the signal responsiblefor the clb5 phenotypes is produced through specific cleavage ofphytofluene or z-carotenoids by the CCD4 enzyme. Furthermore, theanalysis of gene expression for ZDS and CCD4 shows an correlation acrossmultiple tissues and developmental stages. Using wide genome analysis, we havefound that this signal affects the expression of key nuclear-encoded genesimportant for leaf and plastid development as well as genes from thechloroplast genome in comparison to the carotenoid-deficient pds3 mutantplant, supporting the unique role that these carotenoids have over plantdevelopment. Finally, we found that the regulation on gene expression dependson specific cis-acting sequences located in the promoter region of thetarget genes. [mehr]

Olaf Czarnecki - Career Talk

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November 2016

Jane Mellor

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Łucja Kowalewska

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Magalie Uyttewaal

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Jenny Russinova

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January 2017

Steve Penfield

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Marja Timmermans

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March 2017

Keiko Sugimoto

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