Betz, Timo

[["dc.bibliographiccitation.firstpage","5130"],["dc.bibliographiccitation.issue","12"],["dc.bibliographiccitation.journal","Biophysical Journal"],["dc.bibliographiccitation.lastpage","5138"],["dc.bibliographiccitation.volume","96"],["dc.contributor.author","Betz, Timo"],["dc.contributor.author","Koch, Daniel"],["dc.contributor.author","Lim, Daryl"],["dc.contributor.author","Käs, Josef A"],["dc.date.accessioned","2020-11-23T10:37:41Z"],["dc.date.available","2020-11-23T10:37:41Z"],["dc.date.issued","2009-06-17"],["dc.description.abstract","Neuronal growth is an extremely complex yet reliable process that is directed by a dynamic lamellipodial structure at the tip of every growing neurite, called the growth cone. Lamellipodial edge fluctuations are controlled by the interplay between actin polymerization pushing the edge forward and molecular motor driven retrograde actin flow retracting the actin network. The leading edge switches randomly between extension and retraction processes. We identify switching of \"on/off\" states in actin polymerization as the main determinant of lamellipodial advancement. Our analysis of motility statistics allows for a prediction of growth direction. This was used in simulations explaining the amazing signal detection capabilities of neuronal growth by the experimentally found biased stochastic processes. Our measurements show that the intensity of stochastic fluctuations depend on changes in the underlying active intracellular processes and we find a power law eta = a x(alpha) with exponent alpha = 2.63 +/- 0.12 between noise intensity eta and growth cone activity x, defined as the sum of protrusion and retraction velocity. Differences in the lamellipodial dynamics between primary neurons and a neuronal cell line further suggests that active processes tune the observed stochastic fluctuations. This hints at a possible role of noise intensity in determining signal detection sensitivity."],["dc.identifier.doi","10.1016/j.bpj.2009.03.045"],["dc.identifier.pmid","19527673"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/68920"],["dc.language.iso","en"],["dc.relation.eissn","1542-0086"],["dc.relation.issn","0006-3495"],["dc.title","Stochastic actin polymerization and steady retrograde flow determine growth cone advancement"],["dc.type","journal_article"],["dc.type.internalPublication","no"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","13420"],["dc.bibliographiccitation.issue","33"],["dc.bibliographiccitation.journal","Proceedings of the National Academy of Sciences of the United States of America"],["dc.bibliographiccitation.lastpage","13425"],["dc.bibliographiccitation.volume","108"],["dc.contributor.author","Betz, Timo"],["dc.contributor.author","Koch, Daniel"],["dc.contributor.author","Lu, Yun-Bi"],["dc.contributor.author","Franze, Kristian"],["dc.contributor.author","Käs, Josef A"],["dc.date.accessioned","2020-11-23T10:40:36Z"],["dc.date.available","2020-11-23T10:40:36Z"],["dc.date.issued","2011-08-16"],["dc.description.abstract","Many biochemical processes in the growth cone finally target its biomechanical properties, such as stiffness and force generation, and thus permit and control growth cone movement. Despite the immense progress in our understanding of biochemical processes regulating neuronal growth, growth cone biomechanics remains poorly understood. Here, we combine different experimental approaches to measure the structural and mechanical properties of a growth cone and to simultaneously determine its actin dynamics and traction force generation. Using fundamental physical relations, we exploited these measurements to determine the internal forces generated by the actin cytoskeleton in the lamellipodium. We found that, at timescales longer than the viscoelastic relaxation time of τ = 8.5 ± 0.5 sec, growth cones show liquid-like characteristics, whereas at shorter time scales they behaved elastically with a surprisingly low elastic modulus of E = 106 ± 21 Pa. Considering the growth cone's mechanical properties and retrograde actin flow, we determined the internal stress to be on the order of 30 pN per μm(2). Traction force measurements confirmed these values. Hence, our results indicate that growth cones are particularly soft and weak structures that may be very sensitive to the mechanical properties of their environment."],["dc.identifier.doi","10.1073/pnas.1106145108"],["dc.identifier.pmid","21813757"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/68954"],["dc.language.iso","en"],["dc.relation.eissn","1091-6490"],["dc.relation.issn","0027-8424"],["dc.title","Growth cones as soft and weak force generators"],["dc.type","journal_article"],["dc.type.internalPublication","no"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","054009"],["dc.bibliographiccitation.issue","5"],["dc.bibliographiccitation.journal","Journal of Biomedical Optics"],["dc.bibliographiccitation.volume","10"],["dc.contributor.author","Betz, Timo"],["dc.contributor.author","Teipel, Jörn"],["dc.contributor.author","Koch, Daniel"],["dc.contributor.author","Härtig, Wolfgang"],["dc.contributor.author","Guck, Jochen"],["dc.contributor.author","Käs, Josef"],["dc.contributor.author","Giessen, Harald"],["dc.date.accessioned","2020-11-23T10:41:44Z"],["dc.date.available","2020-11-23T10:41:44Z"],["dc.date.issued","2005"],["dc.description.abstract","Confocal and multiphoton microscopy are essential tools in modern life sciences. They allow fast and highly resolved imaging of a steadily growing number of fluorescent markers, ranging from fluorescent proteins to quantum dots and other fluorophores, used for the localization of molecules and the quantitative detection of molecular properties within living cells and organisms. Up to now, only one physical limitation seemed to be unavoidable. Both confocal and multiphoton microscopy rely on lasers as excitation sources, and their monochromatic radiation allows only a limited number of simultaneously usable dyes, which depends on the specific number of laser lines available in the used microscope. We have overcome this limitation by successfully replacing all excitation lasers in a standard confocal microscope with pulsed white light ranging from 430 to 1300 nm generated in a tapered silica fiber. With this easily reproducible method, simultaneous confocal and multiphoton microscopy was demonstrated. By developing a coherent and intense laser source with spectral width comparable to a mercury lamp, we provide the flexibility to excite any desired fluorophore combination."],["dc.identifier.doi","10.1117/1.2114788"],["dc.identifier.pmid","16292969"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/68968"],["dc.language.iso","en"],["dc.relation.issn","1083-3668"],["dc.title","Excitation beyond the monochromatic laser limit: simultaneous 3-D confocal and multiphoton microscopy with a tapered fiber as white-light laser source"],["dc.type","journal_article"],["dc.type.internalPublication","no"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","428"],["dc.contributor.author","Koch, Daniel"],["dc.contributor.author","Betz, Timo"],["dc.contributor.author","Ehrlicher, Allen"],["dc.contributor.author","Gogler, Michael"],["dc.contributor.author","Stuhrmann, Bjorn"],["dc.contributor.author","Kas, Josef"],["dc.contributor.editor","Dholakia, Kishan"],["dc.contributor.editor","Spalding, Gabriel C."],["dc.date.accessioned","2020-11-23T10:30:31Z"],["dc.date.available","2020-11-23T10:30:31Z"],["dc.date.issued","2004"],["dc.identifier.doi","10.1117/12.559672"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/68916"],["dc.relation.eventend","2004-08-06"],["dc.relation.eventlocation","Denver, Colorado"],["dc.relation.eventstart","2004-08-02"],["dc.relation.ispartof","Optical Trapping and Optical Micromanipulation"],["dc.relation.issn","0277-786X"],["dc.title","Optical control of neuronal growth"],["dc.type","conference_paper"],["dc.type.internalPublication","no"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","495"],["dc.bibliographiccitation.lastpage","520"],["dc.contributor.author","Ehrlicher, Allen"],["dc.contributor.author","Betz, Timo"],["dc.contributor.author","Stuhrmann, Björn"],["dc.contributor.author","Gögler, Michael"],["dc.contributor.author","Koch, Daniel"],["dc.contributor.author","Franze, Kristian"],["dc.contributor.author","Lu, Yunbi"],["dc.contributor.author","Käs, Josef"],["dc.date.accessioned","2020-11-23T10:39:19Z"],["dc.date.available","2020-11-23T10:39:19Z"],["dc.date.issued","2007"],["dc.identifier.doi","10.1016/S0091-679X(07)83021-4"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/68938"],["dc.relation.isbn","978-0-12-370500-6"],["dc.relation.ispartof","Cell Mechanics"],["dc.title","Optical Neuronal Guidance"],["dc.type","book_chapter"],["dc.type.internalPublication","no"],["dspace.entity.type","Publication"]]