I consider the microscopic mechanisms by which a particular left-right (L/R) asymmetry is generated at URLanism level from the microscopic handedness of cytoskeletal molecules. In light of a fundamental symmetry principle, the typical pattern-formation mechanisms of diffusion plus regulation cannot implement the "right-hand rule"; in fact, the cytoskeleton (made of helical fibers) seems always to be involved, usually in collective states induced by molecular motors.  I detail a possible scenario involving actin/myosin layers in snails (and in%DIFDELCMD < {\it %%%  C. elegans ), and outline other mechanisms which might govern handedness in eukaryote cell motility and in plants .
I consider the microscopic mechanisms by which a particular left-right (L/R) asymmetry is generated at URLanism level from the microscopic handedness of cytoskeletal molecules. In light of a fundamental symmetry principle, the typical pattern-formation mechanisms of diffusion plus regulation cannot implement the "right-hand rule"; at the microscopic level, the cell's cytoskeleton of chiral filaments seems always to be involved, usually in collective states driven by polymerization forces or molecular motors. It seems particularly easy for handedness to emerge in a shear or rotation in the background of an effectively two-dimensional system, such as the cell membrane or a layer of cells, as this requires no pre-existing axis apart from the layer normal. I detail a scenario involving actin/myosin layers in snails %DIFDELCMD < {\it %%% and in C. elegans , and also one about the microtubule layer in plant cells. I also survey the other examples that I am aware of, such as the emergence of handedness such as the emergence of handedness in neurons, in eukaryote cell motility , and in non-flagellated bacteria .
R
in fact, the cytoskeleton (made of helical fibers)
at the microscopic level, the cell's cytoskeleton of chiral filaments
R
induced by
driven by polymerization forces or
A
It seems particularly easy for handedness to emerge in a shear or rotation in the background of an effectively two-dimensional system, such as the cell membrane or a layer of cells, as this requires no pre-existing axis apart from the layer normal.
D
possible
D
(and in
A
and in
R
), and outline other mechanisms which might govern handedness in
, and also one about the microtubule layer in plant cells. I also survey the other examples that I am aware of, such as the emergence of handedness such as the emergence of handedness in neurons, in
R
and in plants
, and in non-flagellated bacteria