Former Lab Members

Alexandre Pfister, Former Phd student/Postdoc e-mail

AlexAlexandre obtained his master degree in March 2010 in the University of Lausanne. He joined Niko Geldner’s lab in February 2009 to do his master project on the endodermis of Arabidopsis thaliana. The project focused on CASP1 localization, a member of the CASPs family. Using site-directed mutagenesis, highly conserved amino acids within the CASPs were replaced in CASP1 and the different construct were expressed under CASP1 promoter and fused to GFP. The subcellular localization of these different CASP1 variants was then analyzed by confocal microscopy. Interestingly, it could be shown that some amino acids in the second extracellular domain of CASP1 were important for the correct CSD localization. Because his interest in endodermis development, including Casparian strip formation increased during his master project, he began his PhD in the same lab in July 2010. Unfortunately, no specific mutants with defective CS were available until now, it was then not possible to test in which conditions this specialized structure is indeed important and how plants would respond to its absence. Recently, such a mutant encoding a LRR-RLK with an impaired endodermal barrier was found by forward and reverse genetic approaches. The aims of his project was to understand the role of this receptor-like kinase in CS development and to characterize the phenotype of its corresponding mutant in detail.

Joop Vermeer, Former Post doc e-mail

joopJoop did his PhD research in the lab of Dorus Gadella where developed genetically encoded fluorescent lipid biosensors and how to use them to image phosphoinositides in living plants. After this, he moved to the lab of Teun Munnik for a post-doc to study the role of phospholipids in plant growth and development. Subsequently, Joop received a Marie Curie grant to join the Geldner lab in February 2010. Joop is interested in the role of the endodermis during lateral root formation and emergence. He wants to understand the cell fate of the endodermis during this process, but also when the CS disappears, which factors are needed for this process and how the CS of the lateral root gets re-connected with the CS of the primary root. To solve this, he uses functional genomics and 4D live-cell imaging.

Deborah Mühlemann, Former Technical Assistant e-mail

DeboDeborah studied her Bachelors in Biology at the University of Lausanne. During her last years of studies she joined our group as an Undergraduate Assistant, helping everyone with the most fun tasks as seed harvesting and preparing petri dishes. During those years she learned most of the techniques used by the group. Currently she has been recruited as a technical assistant.

Frédéric Brun, Former technician e-mail

FredFrédéric comes from Montpellier (France), where he obtained his Bachelor (2009) and a Masters in Functional Plant Biology (2011). His first scientific project was performed in the group of Christophe Maurel, where he studied the transport of H2O2 across aquaporins leading to aperture/closure disorder in Arabidopsis thaliana. He did his Masters thesis in Alain Gojon’s group. He investigated nitrate responses controlled by the nitrate transceptor NRT1.1, namely the stimulation of root growth, and the regulation of genes related with the nitrate assimilation pathway (other transporters and enzymes). After finishing his Masters, he decided to move in Switzerland, where he got a position as Research Assistant in the Centre of Integrative Genomic of Lausanne (UNIL). Here, his work was to perform genetic and biochemical analysis of mammal’s circadian cycle genes. In 2013, he joined Niko Geldner’s group. Here he is performing, in one hand, confocal and two-photon imagery on some transgenic plants and in the other hand, biochemistry on Casparian strip membrane domain proteins.

Enrique Neumann, Former postdoc e-mail

QuiqueEnrique is originally from Montevideo, Uruguay. He obtained a Degree in Biology of the University of Santiago de Compostela, Spain, in 2009. As an undergraduate he worked in the Department of Physical Anthropology with the group of José Luis Blázquez Caeiro. He finally specialized in Plant Biology, and collaborated reclassifying the herbarium of the Museum of Natural History of the University. He carried out a PhD at Gwyneth Ingram’s lab at the University of Edinburgh, Scotland and later at the École Normale Supérieure de Lyon, France. There he worked characterizing the putative role of the phytocalpain DEK1 in mechanosensing. He joined our group as a Postdoc in May 2013, where his main interest was to study the role that the endodermis plays in pH and calcium homeostasis. He also worked to develop novel ways to phenotype the functionality of the casparian strip.

Sadaf Naseer, Former PhD Student

sadafSadaf obtained her master degree (Masters 1) in Agrobiosciences with specialization in Food safety from University Paul Sabatier, Toulouse, France in July 2006. She continued her studies on the same subject and obtained a Masters 2 degree in July 2007 from same University. She worked at the «Laboratoire de Gènie Chimique, Départements de Toxicologie et Sécurité Alimentaire» with the team of Dr. Annie Leszkowicz at the École Nationale Supérieure Agronomique de Toulouse (ENSAT), France on the molecular mechanism of nephrotoxic mycotoxins and a toxin of herbal tea (Aristolochic acid), comparing the DNA adduct formation and repair, in human kidney cell culture by P32 post-labeling analysis and evaluating the toxin by HPLC analysis. She also analyzed the presence of mycotoxins in different breakfast cereals. She joined the Geldner lab as a PhD student in April 2008. Her project was centered in understanding the chemical nature and function of Casparian strips.

Jonathan Hamilton, Former Technical Assistant

JonAfter the obtention of his Tech Lab dimploma (2009) Jonathan started his professional life at the CHUV, in the Molecular Diagnostic Lab (Institute of Microbiology) working on the H1N1 virus. For 6 months, he was in charge of DNA extractions and, in parallel, worked on establishing a protocol for the beta-glucan quantification in serum. He had the oppurtinity of working at the Geneva Research Center of Merck Serono in the Genetics Laboratory as Research Assistant. His main tasks there were HLA genotyping, polymorphism detection, somatic mutation and DNA methylation analysis (qPCR, sequencing, microarrays).

Yuree Lee, Former Postdoc

YureeYuree, who had worked as a computer programmer changed her carrier from computer science into biology because of curiosity and interests in basic science. She started to study biology in Korea University and did her diploma thesis in 2002. Though her diploma thesis was about animal cancer cell growth, she was more interested in plants and started to work in the lab of Youngsook Lee in POSTECH (Pohang University of Science and Technology). She did her PhD thesis (2002-2008) in the same laboratory, studying the roles of phosphoinositides, especially PtdIns(4,5)P2 and PtdIns(3)P, in guard cells, pollen and root hairs. During her thesis, she has been interested in cell polarity and endo-/exocytosis in plant cells, and moved to Lausanne to further study vesicle trafficking in February 2009.

Valérie Dénervaud-Tendon, Former Technical Assistant

IMG_4453Valérie Dénervaud-Tendon joined our lab in October 2007 and enjoyed the shopping in order to set up the lab. She began her professional life in Nestlé Research Center where she obtained her professional diploma. To continue her studies, she studied at an Engineering in Food technology and Biotechnology in Sion, Switzerland. She went to University of Lausanne and started in Dieter Haas’s lab in the Department of Fundamental Microbiology (DMF). There, her research was focused on the virulence of Pseudomonas aeruginosa and the role of the quorum sensing regulatory network. She then enjoyed Irish life style while working in University College of Cork, Ireland in the lab of Fergal O’Gara.

Julien Spielmann, Former Masters student

julienJulien started studying biology in the University of Lausanne in 2007. He joined our lab in February 2012 and obtained his master degree in January 2013. During his Masters he worked on root copper response at tissue and protein–levels. Using confocal microscopy, he localized different proteins involved in copper homeostasis and analyzed their expressions in different copper concentration. He investigated the role of the Casparian strip in copper metabolism and homeostasis. He was also interested in how copper availability in growth media can affect the lignifications of Casparian strips.

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Esther M. N. Dohmann, Former Postdoc

estherEsther studied Biology at Bielefeld University, where she obtained her Diploma in 2003 with a project comparing leghemoglobins during nodule and micorrhiza symbiosis in Medicago truncatula. For her PhD she went on to the University of Tübingen, where she joined the Lab of Claus Schwechheimer at the centre for molecular plant biology (ZMBP). In her PhD project she was working on the role of the COP9 Signalosome (CSN) in plant development. As a key finding she could show that csn mutants arrest in G2 phase of the cell cycle and that this arrest correlates DNA damage, which is a possible explanation for the csn mutant growth arrest. Subsequently, she was awarded an EMBO fellowship to join the lab in 2009. Here she changed to cell biology to continue Niko’s work on BRI1 trafficking. In 2011, Esther obtained a short term fellowship of the Japan Society for the Promotion of Science (JSPS), to work for three month at Tokyo University as a gues researcher in the Lab of Aki Nakano. After her return, she expanded her project and is now conducting a study comparing the effects of different dominant negative Rabs on BRI1 and other marker proteins. Esther left the university life and works as a Coodinating Editor for the Journal of Hepatology.

Julien Alassimone, Former PhD student

Julien_aBefore joining the Geldner Lab, Julien was interested in the possibility of improving crops by means of plant biotechnology. His Masters project was focused on studying plant adaptation to heavy metal stress at the department of Biochemistry and Molecular Physiology of Plants (BPMP) in Montpellier, France. He arrived in the early days of the lab, in October 2007, as Ph.D student. After measuring the rooms and participating in setting up the lab, he locked himself into the confocal room to describe how endodermal cells obtain their differentiation features. During his Ph.D, he investigated how these cells define membrane domains involved in the directional transport of nutrients. He also realized a forward genetic screen and identified a group of mutants defective in their Casparian Strip establishment; the schengen mutants. He considers being a part of the lab as “a unique, great and pleasant human adventure” that revealed his interest for developmental biology. Since March 2013, he moved to Dominique Bergmann’s Lab at the Stanford University (California) to investigate the connections between polarity establishment and the organization of asymmetric divisions. A project focused on another fundamental question: how does asymmetric cell division drive cell fate decisions in the stomata cell lineage?

Misako Yamazaki, Former Postdoc

Misako

Misako is very interested in the molecular mechanism of membrane traffic machinery and the physiological function of it. In the laboratory of Ikuko Hara-Nishimura, Kyoto University in Japan (2002-2009) she performed a reverse genetic approach to several VPS (vacuolar protein sorting) genes. She examined the function of the retromer complex (named after retrograde transport coatmer) in Arabidopsis developing seeds and showed that the retromer complex is not only required for vacuolar protein sorting but also for plant growth, leaf senescence and embryogenesis (Plant Cell Physiol. 2008 Feb; 49(2): 142-56). These results imply that the membrane traffic by the retromer is important in a lot of developmental stages dependent on the cargos, the targets of the retromer. In Niko’s group she worked on the endodermal polar proteins and tried to identify the mechanism to establish and maintain the polarity in plants. In 2012, she moved to Kentaro Shimizu’s lab at Zurich University. There she is working on the molecular mechanisms of evolution.

Daniele Roppolo, Former Postdoc

DanieleDaniele joined Nikos group in May 2008 and left 5 years later. His main contributions during these pleasant years of research were the identification of the CASPs and bark. He also reconstructed the phylogenetic history of the CASPs and established their link with the MARVEL protein family. Quoting him: “I worked in a fantastic environment doing good science with excellent colleagues. Niko offered me the possibility to grow in the plant biology field and all the members of the group contributed to the extremely enjoyable atmosphere (they also contributed to my work!).” From February 2013, he is project leader at the Institute of Plant Sciences at the University of Bern, where he is finding out how membrane fences are established in plants, how they do maintain polarity and to which extent local cell wall modifications are directed by plasma membrane protein scaffolds. He is also interested in the molecular mechanisms that establish tissue-specific gene expression and in the way these mechanisms mediate plant plasticity. Even though he is not working on them at the moment, he is still interested in the CASPs: if he were in the lab, he would probably fight against confocal resolution to understand how CASP domains from neighbouring cells get aligned.

Mª Carmen Rubio, Former Visiting Scientist

MariCarmen180

Mari Carmen studied chemistry at the University of Zaragoza (Spain). After getting her diploma, she did her PhD thesis in the laboratory of Manuel Becana at the Estación Experimental Aula Dei (EEAD-CSIC, Zaragoza), studying the superoxide dismutases in nodules of legumes at the biochemical level, as well as the effect of water stress on antioxidants of alfalfa (Medicago sativa) nodules. Then she got a postdoc position in the group of Herman Spaink at the University of Leiden (The Netherlands) where she continued studying the role of superoxide dismutases during root nodule development in the model legume Lotus japonicus. During her postdoc, she expanded her training with new skills and techniques on molecular and cell biology. She returned in May 2005 to the EEAD, where she got a permanent position in July 2008. In April 2011, she joined Geldner’s lab as a visiting scientist to study the role of reactive oxygen species in Casparian strip formation. Since August 2012, she is working again in the EEAD continuing with her studies on oxidative stress and also starting to work with CASP proteins in nodules.

Lothar Kalmbach, former Phd student e-mail

Lothar_180Lothar started studying biology in Mainz, Germany in 2004. After his 2nd year exams (Vordiplom) in 2006 he went to Umeå, Sweden and participated in a Master’s program in Plant and Forest Biotechnology. Upon his return to Germany in 2007 he continued his studies at the University of Würzburg. As his first scientific project he performed a brief electrophysiological characterization of the ligand-dependent gating of a potassium channel in maize. For his Diploma thesis he returned to Sweden and joined the group of Markus Grebe at the Umeå Plant Science Centre in 2009. He acquired a background in experimental plant cell biology, and performed a comprehensive analysis on leaf trichome orientation in Arabidopsis thaliana in a planar polarity context. Also, he characterized antibodies against a protein putatively involved in planar polarity signaling in Arabidopsis. Having decided to stay in science and to continue research in plant cell biology, he joined the Geldner lab as a PhD student in November 2010. Now he is looking for factors defining and organizing the Casparian Strip membrane domain in endodermal cells by a forward genetic approach.