The mechanics clarifying counterclockwise rotation in most IVF eggs in mice

Ishimoto, Kenta; Ikawa, Masahito; Okabe, Masaru

doi:10.1038/srep43456

Cited by 3 publications

(7 citation statements)

References 25 publications

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“…When the cell body takes the shape of a prolate spheroid such as of E. coli, C D1 /C D3 > 2 still holds and we obtain the same relation as (4.24). Other straightforward extensions include the situation in which the cell body is located near a planar infinite wall, a situation relevant to a sperm-egg cluster that tends to rotate without translation [29]. The predominance of rotation could be rationalized in that case using lubrication theory [30], which shows that drag coefficients C D1 and C D3 diverge as the spherical cell body approaches the wall, while the value of the rotation drag coefficient C R3 remains very close to that in the bulk.…”

Section: Discussionmentioning

confidence: 99%

“…We proceed to consider the torque balance relation for each flagellum, which experiences both hydrodynamic torque and an elastic spring restoring torque at the flagellum-cell body junction [12,26]. The hydrodynamic torque follows from the discussion above and we now consider the torque balance at the flagellum-cell body junction point.…”

Section: Torque Balance For Each Flagellummentioning

confidence: 99%

“…Theorem IV.1 The linear system (12) includes the six modes associated with a rigid-body motion, with eigenvalues A T , A T , A T 3 , A R , A R3 , A R3 . The remaining 2N − 6 degrees of freedom all generate identical negative eigenvalues, κ/k F < 0.…”

Section: General N Casementioning

confidence: 99%

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TheN-flagella problem: elastohydrodynamic motility transition of multi-flagellated bacteria

Ishimoto

Lauga

2019

Proc. R. Soc. A.

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Peritrichous bacteria such as Escherichia coli swim in viscous fluids by forming a helical bundle of flagellar filaments. The filaments are spatially distributed around the cell body to which they are connected via a flexible hook. To understand how the swimming direction of the cell is determined, we theoretically investigate the elastohydrodynamic motility problem of a multi-flagellated bacterium. Specifically, we consider a spherical cell body with a number N of flagella which are initially symmetrically arranged in a plane in order to provide an equilibrium state. We analytically solve the linear stability problem and find that at most 6 modes can be unstable and that these correspond to the degrees of freedom for the rigid-body motion of the cell body. Although there exists a rotation-dominated mode that generates negligible locomotion, we show that for the typical morphological parameters of bacteria the most unstable mode results in linear swimming in one direction accompanied by rotation around the same axis, as observed experimentally.

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Section: Discussionmentioning

confidence: 99%

Section: Torque Balance For Each Flagellummentioning

confidence: 99%

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TheN-flagella problem: elastohydrodynamic motility transition of multi-flagellated bacteria

Ishimoto

Lauga

2019

Proc. R. Soc. A.

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“…The elastohydrodynamic stability analysis of a multi-flagellated bacterium (Ishimoto & Lauga 2019) suggests that the vertical spinning mode is the most unstable when the flagellum is sufficiently short, but detailed theoretical analysis has not yet been done in the presence of the wall boundary. Further, the biased rotation direction of T. majus could be understood by the symmetry being broken by the flagellar chirality and inhomogeneous propulsion due to the presence of a wall, as found in the anticlockwise rotation of a sperm–egg cluster in mice in vitro fertilization (Ishimoto, Ikawa & Okabe 2017). Similarly, the elastohydrodynamics in the swimming of multi-flagellated bacteria would provide a better understanding of the boundary-following swimming of E. coli .…”

Section: Discussionmentioning

confidence: 99%

Bacterial spinning top

Ishimoto

2019

J. Fluid Mech.

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We have investigated the dynamics of a monotrichous bacteria cell near a wall boundary, taking elastic hook flexibility into consideration. Combining theoretical linear stability analysis and direct numerical computations via the boundary element method, we have found that the elastohydrodynamic coupling between the hook elasticity and cell rotational motion enables a stable vertical spinning behaviour like a low-Reynolds-number spinning top. The forwardly rotated flagellum, which generates the force exertion pushing towards the cell body, typically destabilizes the vertical upright position and leads to a boundary-following motion. In contrast, the backward rotation of the flagellum, generating a force pulling the cell body, contributes to stable upright behaviour in a large range of hook rigidity. Further numerical investigations have demonstrated that the non-spherical geometry of the cell body and boundary adhesive interactions affect the bacterial dynamics, leading to complex behaviours such as horizontal spinning and unstable vertical spinning motions, both of which are experimentally observed in Pseudomonas aeruginosa bacteria. These results highlight the rich diversity of bacterial surface motility emerging from mechanical boundary interactions coupled with the cell swimming and hook flexibility.

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“…In mammals, it is unknown whether the eggs rotate through the interaction with the oviducts, though the eggs are rotated by chiral beating of spermatozoa in a counterclockwise manner during fertilization [ 137 ]. More extensive observations of the dynamics of the eggs and the oviducts will be informative to understand the mechanical roles of the oviducts in egg rotation as well as embryogenesis and egg transportation.…”

Section: Role Of Oviduct and Egg Shape In Embryogenesismentioning

confidence: 99%

Biophysics in oviduct: Planar cell polarity, cilia, epithelial fold and tube morphogenesis, egg dynamics

2019

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Organs and tissues in multi-cellular organisms exhibit various morphologies. Tubular organs have multi-scale morphological features which are closely related to their functions. Here we discuss morphogenesis and the mechanical functions of the vertebrate oviduct in the female reproductive tract, also known as the fallopian tube. The oviduct functions to convey eggs from the ovary to the uterus. In the luminal side of the oviduct, the epithelium forms multiple folds (or ridges) well-aligned along the longitudinal direction of the tube. In the epithelial cells, cilia are formed orienting toward the downstream of the oviduct. The cilia and the folds are supposed to be involved in egg transportation. Planar cell polarity (PCP) is developed in the epithelium, and the disruption of the Celsr1 gene, a PCP related-gene, causes randomization of both cilia and fold orientations, discontinuity of the tube, inefficient egg transportation, and infertility. In this review article, we briefly introduce various biophysical and biomechanical issues in the oviduct, including physical mechanisms of formation of PCP and organized cilia orientation, epithelial cell shape regulation, fold pattern formation generated by mechanical buckling, tubulogenesis, and egg transportation regulated by fluid flow. We also mention about possible roles of the oviducts in egg shape formation and embryogenesis, sinuous patterns of tubes, and fold and tube patterns observed in other tubular organs such as the gut, airways, etc.

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The mechanics clarifying counterclockwise rotation in most IVF eggs in mice

Cited by 3 publications

References 25 publications

TheN-flagella problem: elastohydrodynamic motility transition of multi-flagellated bacteria

TheN-flagella problem: elastohydrodynamic motility transition of multi-flagellated bacteria

Bacterial spinning top

Biophysics in oviduct: Planar cell polarity, cilia, epithelial fold and tube morphogenesis, egg dynamics

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