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Multi-scale analysis of glass skeletons in marine sponges & Hormonal control of zebrafish brain regeneration

CMCB PhD/Postdoc Seminar

Date:24.05.2019, 16:00 - 17:00
Speaker: Dr. Ronald Seidel, Dr. Christian Lange
Location: CRTD, auditorium left
Host: Dr. Igor Zlotnikov & Prof. Michael Brand

Speakers: Igor Zlotnikov, Ronald Seidel

Title: Multi-scale analysis of glass skeletons in marine sponges

Abstract: Demospongiae and Hexactinellida are two classes of marine sponges that fabricate skeletal elements, the spicules, made of amorphous silica. Astonishingly, despite the disordered nature of the mineral phase, these spicules exhibit a large variety of highly regular three-dimensional branched morphologies that are a paradigm example of symmetry in biological systems. Our work employs X-ray-based imaging and analysis methods to unravel the principles of spicules biomineralization and their hierarchical arrangement in sponge tissue.

Speakers: Michael Brand, Christian Lange

Title: Hormonal control of zebrafish brain regeneration

Abstract: Zebrafish can regenerate their brain after traumatic brain injury through induced reactive proliferation and neurogenesis from radial glia type stem cells. We are studying the molecular mechanisms underlying this paradigm of successful brain regeneration, with a view to developing strategies towards rekindling brain repair ability also in mammals. Thyroid hormone is an important factor in brain development and can function in adult neurogenic brain regions in mammals. We discovered a role of thyroid hormone in zebrafish brain regeneration after injury. By studying the role of thyroid hormone signaling for radial glia proliferation in the adult zebrafish telencephalon, we found that thyroid hormone signaling is upregulated in radial glia during brain regeneration. Genetic and pharmacological blockade of thyroid hormone generation shows its requirement for inducing radial glia proliferation and reparative neurogenesis after injury. Conversely, treating unlesioned adult fish with thyroid hormone is sufficient to increase proliferation of radial glia, apparently without triggering inflammation or apoptosis. Analysis of thyroid hormone receptor activation reveals that radial glia are primary targets for thyroid hormone signaling in the adult zebrafish brain. Thus, our data reveal a novel role of thyroid hormone as a physiological cue that is required and sufficient for the induction of radial glia proliferation and neural regeneration in adult zebrafish brain. These results suggest that manipulating thyroid hormone signaling may be a promising therapeutic strategy for brain repair in mammals, since manipulation of this pathway is already clinical practice.

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