Global ETD Search

1	The Role of Tubulin Polyglycylation and Polyglutamylation in Ciliary Mechanics Alvarez Viar, Gonzalo 13 December 2021 (has links) Tubulin post-translational modifications (tPTMs) are currently studied as vital, yet obscure, cytoskeletal regulators. Their regulatory function relies on the spatiotemporal control over the activity of multiple tubulin modifying enzymes that functionalize microtubules, enabling their differentiation. The cilium, one of the organelles with the richest tPTMs diversity, has been studied with determination for the last decades, allowing the interrogation of the molecular processes that give rise to its function. The inner structure of this thin organelle, the axoneme, comprises a microtubule scaffold periodically decorated with macromolecular complexes whose characterization has been achieved with pseudoatomic detail. The molecular distribution and mechanism of action of tPTMs in cilia remain elusive. Using a combination of immunolabelling and cryoelectron tomography we interrogated the molecular function two tPTMs in the axonemal context. We showed that tubulin polyglycylation spanned most of the microtubular surface and was required for axonemal dynein activity regulation and male fertility. Additionally, there was an enrichment of polyglutamylation on a single microtubule protofilament, forming a pattern complementary to that of polyglycylation, that was required for proper coupling of microtubule sliding and bending forces during ciliary beating. info:eu-repo/classification/ddc/570 ddc:570
2	Dynamics of Cilia and Flagella / Bewegung von Zilien und Geißeln Hilfinger, Andreas 14 January 2006 (has links) (PDF) Cilia and flagella are hair-like appendages of eukaryotic cells. They are actively bending structures that exhibit regular beat patterns and thereby play an important role in many different circumstances where motion on a cellular level is required. Most dramatic is the effect of nodal cilia whose vortical motion leads to a fluid flow that is directly responsible for establishing the left-right axis during embryological development in many vertebrate species, but examples range from the propulsion of single cells, such as the swimming of sperm, to the transport of mucus along epithelial cells, e.g. in the ciliated trachea. Cilia and flagella contain an evolutionary highly conserved structure called the axoneme, whose characteristic architecture is based on a cylindrical arrangement of elastic filaments (microtubules). In the presence of a chemical fuel (ATP), molecular motors (dynein) exert shear forces between neighbouring microtubules, leading to a bending of the axoneme through structural constraints. We address the following two questions: How can these organelles generate regular oscillatory beat patterns in the absence of a biochemical signal regulating the activity of the force generating elements? And how can the beat patterns be so different for apparently very similar structures? We present a theoretical description of the axonemal structure as an actively bending elastic cylinder, and show that in such a system bending waves emerge from a non-oscillatory state via a dynamic instability. The corresponding beat patterns are solutions to a set of coupled partial differential equations presented herein. Axonem Bewegung bei kleinen Reynolds Zahlen Biophysik Flagellen Geißeln Molekulare Motoren Nodale Zilien Physik Selbstorganisierte Schlagmuster Situs inversus Spermien Wimpern Zilien Situs inversus axoneme biophysics cilia dynein flagella left-right axis formation low Reynolds number dynamics molecular motors nodal cilia physics spermatozoa spontaneous oscillations ddc:530 rvk:UF 5000 Cilie Flagelline Geißel &lt;Biologie&gt; Molekularer Motor Reynolds-Zahl Selbstorganisation Spermium Zilie
3	Dynamics of Cilia and Flagella Hilfinger, Andreas 07 February 2006 (has links) Cilia and flagella are hair-like appendages of eukaryotic cells. They are actively bending structures that exhibit regular beat patterns and thereby play an important role in many different circumstances where motion on a cellular level is required. Most dramatic is the effect of nodal cilia whose vortical motion leads to a fluid flow that is directly responsible for establishing the left-right axis during embryological development in many vertebrate species, but examples range from the propulsion of single cells, such as the swimming of sperm, to the transport of mucus along epithelial cells, e.g. in the ciliated trachea. Cilia and flagella contain an evolutionary highly conserved structure called the axoneme, whose characteristic architecture is based on a cylindrical arrangement of elastic filaments (microtubules). In the presence of a chemical fuel (ATP), molecular motors (dynein) exert shear forces between neighbouring microtubules, leading to a bending of the axoneme through structural constraints. We address the following two questions: How can these organelles generate regular oscillatory beat patterns in the absence of a biochemical signal regulating the activity of the force generating elements? And how can the beat patterns be so different for apparently very similar structures? We present a theoretical description of the axonemal structure as an actively bending elastic cylinder, and show that in such a system bending waves emerge from a non-oscillatory state via a dynamic instability. The corresponding beat patterns are solutions to a set of coupled partial differential equations presented herein. info:eu-repo/classification/ddc/530 ddc:530

1

Page generated in 0.0374 seconds