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  Stephanie

Stephanie S.M.H. Höhn

Postdoctoral researcher

Current work

I am a Research Associate in the Goldstein lab. I am using multiple imaging techniques to study the biological and biophysical mechanisms underlying embryonic development. I am using the multicellular microorganism Volvox and closely related genera as model organisms for embryonic cell sheet folding.






inversiontypes

Biomechanical features of cell sheet folding

Cell sheet folding is a common morphogenetic process during the development of multicellular organisms. Spheroidal green algae of the genus Volvox are uniquely suited as simple model systems for studying the basic principles of epithelial folding. Volvox embryos turn their spherical cell monolayer inside out to achieve their adult configuration; this process is called inversion. During my PhD studies I discovered fundamental differences between the cellular processes underlying inversion in different Volvox species (see previous work). One goal of my current research project is to understand the mechanisms that cause different inversion processes (fig. 1). Additionally, I intend to quantify the physical properties of inverting Volvox embryos. The resulting experimental data will be integrated in computational models of the moving cell sheet.



























Inversion_V.globator

Embryonic inversion in Volvox globator; selective plane illumination microscopy (SPIM).






V.carteri

Self-organisation of cellular patterns in Volvox

Volvox sp.consists of several thousand small somatic cells and few (4-40) reproductive cells (gonidia) (fig. 2). Each somatic cell possesses two flagella which enable the organism to swim and perform phototaxis. All cells are embedded in a gelatinous extracellular matrix (ECM) that is secreted by the cells. In order to allow for coordinated swimming, the flagellated cells need to be positioned regularly within the ECM. Very little is known about the self-organisation of the correct cellular patterns in Volvox [5]. I am using cell tracking techniques and time-lapse microscopy to reveal the underlying mechanisms of cell positioning in the developing spheroids.



















Previous work

Type B inversion in Volvox globator

I did my PhD research with Prof. Armin Hallmann in the Department of Cellular and Developmental Biology of Plants at the University of Bielefeld, on the embryonic type B inversion in Volvox globator.

V.globator inversion,type B