Integrated Calendar

Engineering next-generation materials that can grow into efficient multitasking agents, move rapidly, or discern environmental cues greatly benefits from inspiration from biological systems. In the first part of my talk, I will present a geometrical theory that explains the biomineralization-inspired growth and form of carbonate-silica microarchitectures in a dynamic reaction-diffusion system. The theory predicts new self-assembly pathways of intricate morphologies and thereby guides the synthesis of light-guiding optical structures. The second part is dedicated to a soft matter analog of controlled actuation and complex sensing in living systems. Specifically, I will introduce a continuum framework of a simple hydrogel system that is activated upon transport and reaction of chemical stimuli. The hydrogel exhibits unique cascades of mechanical and optical responses, suggesting that common gels have a much larger sensing space than currently employed. The theoretical work presented in my talk is intimately connected to modern materials science. The effective convergence of theory and experiment paves the way for optimized hard or soft biomimetic materials for applications ranging from bottom-up manufacturing to soft robotics.

The innervation of peripheral targets during embryonic development is largely regulated by the levels of target-derived trophic factors. But whether additional target-derived factors act in concert with these trophic factors and their identity is largely unknown. Sensory innervation of the mammary gland is controlled by Brain derived-neurotrophic factor (BDNF), and sexually dimorphic sequestering of BDNF by the truncated form of its receptor (TrkB.T1), directs male-specific axonal pruning in mice.
In search for cues that control the innervation together with BDNF I have found specific, non-dimorphic, expression of Semaphorin family members in the mouse mammary gland, which signal through PlexinA4. PlexinA4 deletion in both female and male embryos caused developmental hyperinnervation of the gland, which could be reduced by genetic co-reduction of BDNF. Moreover, in males, PlexinA4 ablation delayed axonal pruning, independently of the initial levels of innervation.
Overall, my study shows that precise sensory innervation of the mammary gland is regulated by the balance between trophic and repulsive signaling. Upon inhibition of trophic signaling, these repulsive factors are critical to promote axonal pruning.