Professional Education


  • Doctor of Philosophy, Rheinische Friedrich-Wilhelms-Univ (2012)
  • Diplom, Rheinische Friedrich-Wilhelms-Univ (2008)

Stanford Advisors


All Publications


  • A K(+)-selective CNG channel orchestrates Ca(2+) signalling in zebrafish sperm. eLife Fechner, S., Alvarez, L., Bönigk, W., Müller, A., Berger, T. K., Pascal, R., Trötschel, C., Poetsch, A., Stölting, G., Siegfried, K. R., Kremmer, E., Seifert, R., Kaupp, U. B. 2015; 4

    Abstract

    Calcium in the flagellum controls sperm navigation. In sperm of marine invertebrates and mammals, Ca(2+) signalling has been intensely studied, whereas for fish little is known. In sea urchin sperm, a cyclic nucleotide-gated K(+) channel (CNGK) mediates a cGMP-induced hyperpolarization that evokes Ca(2+) influx. Here, we identify in sperm of the freshwater fish Danio rerio a novel CNGK family member featuring non-canonical properties. It is located in the sperm head rather than the flagellum and is controlled by intracellular pH, but not cyclic nucleotides. Alkalization hyperpolarizes sperm and produces Ca(2+) entry. Ca(2+) induces spinning-like swimming, different from swimming of sperm from other species. The "spinning" mode probably guides sperm into the micropyle, a narrow entrance on the surface of fish eggs. A picture is emerging of sperm channel orthologues that employ different activation mechanisms and serve different functions. The channel inventories probably reflect adaptations to species-specific challenges during fertilization.

    View details for DOI 10.7554/eLife.07624

    View details for PubMedID 26650356

  • Synaptic Communication upon Gentle Touch. Neuron Fechner, S., Goodman, M. B. 2018; 100 (6): 1272–74

    Abstract

    Gentle touch sensation in mammals depends on synaptic transmission from primary sensory cells (Merkel cells) to secondary sensory neurons. Hoffman etal. (2018) identify norepinephrine and beta2-adrendergic receptors as the neurotransmitter-receptor pair responsible for sustained touch responses. The findings may deepen understanding of how drugs affect touch and pain sensation.

    View details for DOI 10.1016/j.neuron.2018.12.001

    View details for PubMedID 30571937

  • Physiological evidence of sensory integration in the electrosensory lateral line lobe of Gnathonemus petersii PLOS ONE Fechner, S., Grant, K., von der Emde, G., Engelmann, J. 2018; 13 (4): e0194347

    Abstract

    Mormyrid fish rely on reafferent input for active electrolocation. Their electrosensory input consists of phase and amplitude information. These are encoded by differently tuned receptor cells within the Mormyromasts, A- and B-cells, respectively, which are distributed over the animal's body. These convey their information to two topographically ordered medullary zones in the electrosensory lateral line lobe (ELL). The so-called medial zone receives only amplitude information, while the dorsolateral zone receives amplitude and phase information. Using both sources of information, Mormyrid fish can disambiguate electrical impedances. Where and how this disambiguation takes place is presently unclear. We here investigate phase-sensitivity downstream from the electroreceptors. We provide first evidence of phase-sensitivity in the medial zone of ELL. In this zone I-cells consistently decreased their rate to positive phase-shifts (6 of 20 cells) and increased their rate to negative shifts (11/20), while E-cells of the medial zone (3/9) responded oppositely to I-cells. In the dorsolateral zone the responses of E- and I-cells were opposite to those found in the medial zone. Tracer injections revealed interzonal projections that interconnect the dorsolateral and medial zones in a somatotopic manner. In summary, we show that phase information is processed differently in the dorsolateral and the medial zones. This is the first evidence for a mechanism that enhances the contrast between two parallel sensory channels in Mormyrid fish. This could be beneficial for impedance discrimination that ultimately must rely on a subtractive merging of these two sensory streams.

    View details for DOI 10.1371/journal.pone.0194347

    View details for Web of Science ID 000429742900030

    View details for PubMedID 29641541

    View details for PubMedCentralID PMC5894992

  • A Hyperpolarization-Activated Proton Channel in Zebrafish Sperm Seifert, R., Wobig, L., Wolfenstetter, T., Fechner, S., Boenigk, W., Koerschen, H., Kaupp, U., Berger, T. CELL PRESS. 2018: 379A
  • Characterization of DEGT-1: A DEG/ENaC/ASIC Ion Channel Subunit Involved in Touch Sensation Fechner, S., Loizeau, F., Nekimken, A. L., D'Alessandro, I., Pruitt, B. L., Goodman, M. B. CELL PRESS. 2018: 157A
  • Microfluidics for mechanobiology of model organisms. Methods in cell biology Kim, A. A., Nekimken, A. L., Fechner, S., O'Brien, L. E., Pruitt, B. L. 2018; 146: 217–59

    Abstract

    Mechanical stimuli play a critical role in organ development, tissue homeostasis, and disease. Understanding how mechanical signals are processed in multicellular model systems is critical for connecting cellular processes to tissue- and organism-level responses. However, progress in the field that studies these phenomena, mechanobiology, has been limited by lack of appropriate experimental techniques for applying repeatable mechanical stimuli to intact organs and model organisms. Microfluidic platforms, a subgroup of microsystems that use liquid flow for manipulation of objects, are a promising tool for studying mechanobiology of small model organisms due to their size scale and ease of customization. In this work, we describe design considerations involved in developing a microfluidic device for studying mechanobiology. Then, focusing on worms, fruit flies, and zebrafish, we review current microfluidic platforms for mechanobiology of multicellular model organisms and their tissues and highlight research opportunities in this developing field.

    View details for DOI 10.1016/bs.mcb.2018.05.010

    View details for PubMedID 30037463