Profil Beatrix Zaban
Die Natur ist das einzige Buch, das auf allen Blättern grossen Gehalt bietet.
Nature is the only book that offers great content on all sheets.-
(Johann Wolfgang von Goethe, 1749 – 1832)
During current semesters, main focus of my work has been on teaching courses including:
- responsible instructor for module Ang-01 (Nutzpflanzenpraktikum / Practical Course of Crop Plants) as well as the tutorial for this module
- assistance in module BA-03 (Botanische Bestimmungsübungen / Exercises in Botanical Taxonomy and Botanische Exkursionen / Excursion in Botany)
- assistance for module BA LMC-3 (Mikroskopisches Anfängerpraktikum / Practical Course in Microscopy) and MA LMC-4 (Nutzpflanzen und Gentechnik / Crop Plants and Gene Technology)
A further part of my work are the public tours in the KIT Botanical Garden covering different topics, as well as guided tours or interactive events for school classes, associations, or private visitor groups.
1. The search for the secrets of peppermint oil
Mints are ancient herbs and thereby have been highly valued by humans for a long time. Already in Greek mythology the origin of the mint was described by the nice story of the nymph “Minthe”.
Peppermint itself is a cross between the watermint and spearmint (Mentha x piperita) and was first described by Carl Linné in 1753. Peppermint is a common element of our daily life and used worldwide - its use in folk medicine and in wellness is well established.
There exist numerous cultivars, and the diversity within this genus is tremendous, but all species harbour high concentrations of menthol and menthone. Interestingly, peppermint oil also contains a high concentration of natural pesticides, mainly pulegone. Also different monoterpenes of mints offer an interesting research field, especially in terms of recently discovered anti-cancer activity.
2. M&M’s: Monoterpenes and Microtubules
Monoterpenes contain two isoprene units and are synthesized like all the other terpenes and terpenoids via the terpene synthases. They are primary constituents of essential oils and occur in many plants. The most well known terpenoid is vitamin A. However, also many other terpenes are useful active compounds, for instance as natural pesticides. Their cellular effect, is now in focus, for instance, there potential impact on microtubules.
1. The induction of plant polarity in tobacco BY-2 cells
To study how polarity and axes are induced de novo, protoplasts of tobacco Nicotiana tabacum L. cv. BY-2 expressing fluorescently tagged cytoskeletal markers were investigated. A standardized system (“tabula rasa”) was developed to generate and integrate quantitative data on the temporal patterns of regeneration stages. Later, the tabula rasa system was integrated into a microfluidic platform to study the impacts of chemical and geometrical stimuli during the establishment of polarity. (Zaban et al., 2013)
Changes in the cytoskeleton and synthesis of a new cell wall in regenerating BY-2 protoplast
The synthesis of a new cell wall marks the transition to the first stage of regeneration and proceeds after a long preparatory phase within a few minutes. During this preparatory phase (about 0.5 d), the nucleus migrates actively and cytoplasmic strands remodel vigorously. Cell wall formation is followed by the induction of a new cell pole (stage 1), requiring dynamic actin filaments. The new cell axis (stage 2) is manifested as elongation growth perpendicular to the orientation of the aligned cortical microtubules.
This system was probed for the effect of anticytoskeletal compounds, inducible bundling of actin, RGD-peptides, and temperature. The suppression of actin dynamics at an early stage leads to aberrant tripolar cells, whereas suppression of microtubule dynamics produces aberrant sausage-like cells with asymmetric cell walls. These data were integrated into a model, where the microtubular cytoskeleton conveys positional information between the nucleus and the membrane controlling the release or activation of components required for cell wall synthesis.
2. Geometry sensing in tobacco BY-2 cells
Cell polarity and axis development are central for plant morphogenesis. Cell movement as central mechanism for animal morphogenesis does not play a role in the walled cells of higher plants. Plant development rather relies on flexible alignment of cell axis adjusting cellular differentiation with respect to directional cues. As central input, vectorial fields of mechanical stress, but also gradients of the phytohormone auxin have been discussed. In a tissue context mechanical and chemical signals will always act in concert, which makes it experimentally difficult to dissect their individual roles. To overcome this limitation, a novel microfluidic approach, based on cells where directionality has been eliminated by removal of the cell wall, was designed. (Zaban et al., 2014)
Chemical vs. mechanical stimuli in plants
For studying the chemical and geometrical impacts acting on this system, a new cell axis, using a microfluidic set-up to generate auxin gradients where rectangular microvessels are integrated orthogonally with the gradient, was imposed. Cells in these microvessels align their new axis with microvessel geometry before touching the wall. This alignment depends on the position in the auxin gradient. Auxin efflux is necessary for this touch-independent exploration of geometry. A model, where auxin gradients can be used to align cell axis in tissues in a manner as to minimize mechanical tensions, was accomplished.
Zaban B, Maisch J, Nick P. Dynamic actin controls polarity induction de novo in protoplasts. J Int Plant Biol 55, 142-159 - pdf
Zaban B, Liu WW, Jiang X, Nick P (2014) Plant Cells Use Auxin Fluxes to Explore Geometry. Nature Scientific Reports doi:10.1038/srep05852 - pdf