10 research outputs found
Differential elasticity in lineage segregation of embryonic stem cells
The question of what guides lineage segregation is central to development,
where cellular differentiation leads to segregated cell populations destined
for specialized functions. Here, using optical tweezers measurements of mouse
embryonic stem cells (mESCs), we reveal a mechanical mechanism based on
differential elasticity in the second lineage segregation of the embryonic
inner cell mass into epiblast (EPI) cells - that will develop into the fetus -
and primitive endoderm (PrE) - which will form extraembryonic structures such
as the yolk sac. Remarkably, we find that these mechanical differences already
occur during priming and not just after a cell has committed to
differentiation. Specifically, we show that the mESCs are highly elastic
compared to any other reported cell type and that the PrE cells are
significantly more elastic than EPI-primed cells. Using a model of two cell
types differing only in elasticity we show that differential elasticity alone
can lead to segregation between cell types, suggesting that the mechanical
attributes of the cells contribute to the segregation process. Our findings
present differential elasticity as a previously unknown mechanical contributor
to the lineage segregation during the embryo morphogenesis
Roadmap for Optical Tweezers 2023
Optical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nanoparticle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space exploration
Changes in Cell Morphology and Actin Organization in Embryonic Stem Cells Cultured under Different Conditions
The cellular cytoskeleton provides the cell with a mechanical rigidity that allows mechanical interaction between cells and the extracellular environment. The actin structure plays a key role in mechanical events such as motility or the establishment of cell polarity. From the earliest stages of development, as represented by the ex vivo expansion of naïve embryonic stem cells (ESCs), the critical mechanical role of the actin structure is becoming recognized as a vital cue for correct segregation and lineage control of cells and as a regulatory structure that controls several transcription factors. Naïve ESCs have a characteristic morphology, and the ultrastructure that underlies this condition remains to be further investigated. Here, we investigate the 3D actin cytoskeleton of naïve mouse ESCs using super-resolution optical reconstruction microscopy (STORM). We investigate the morphological, cytoskeletal, and mechanical changes in cells cultured in 2i or Serum/LIF media reflecting, respectively, a homogeneous preimplantation cell state and a state that is closer to embarking on differentiation. STORM imaging showed that the peripheral actin structure undergoes a dramatic change between the two culturing conditions. We also detected micro-rheological differences in the cell periphery between the cells cultured in these two media correlating well with the observed nano-architecture of the ESCs in the two different culture conditions. These results pave the way for linking physical properties and cytoskeletal architecture to cell morphology during early development
Filopodia rotate and coil by actively generating twist in their actin shaft
Filopodia are actin-rich structures, present on the surface of practically
every known eukaryotic cell. These structures play a pivotal role in specific
cell-cell and cell-matrix interactions by allowing cells to explore their
environment, generate mechanical forces, perform chemical signaling, or convey
signals via intercellular tunneling nano-bridges. The dynamics of filopodia
appear quite complex as they exhibit a rich behavior of buckling, pulling,
length and shape changes. Here, we show that filopodia additionally explore
their 3D extracellular space by combining growth and shrinking with axial
twisting and buckling of their actin rich core. Importantly, the actin core
inside filopodia performs a twisting or spinning motion which is observed for a
range of highly distinct and cognate cell types spanning from earliest
development to highly differentiated tissue cells. Non-equilibrium physical
modeling of actin and myosin confirm that twist, and hence rotation, is an
emergent phenomenon of active filaments confined in a narrow channel which
points to a generic mechanism present in all cells. Our measurements confirm
that filopodia exert traction forces and form helical buckles in a range of
different cell types that can be ascribed to accumulation of sufficient twist.
These results lead us to conclude that activity induced twisting of the actin
shaft is a general mechanism underlying fundamental functions of filopodia
Roadmap for optical tweezers
Optical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects, ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in the life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nano-particle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space exploration
Roadmap for optical tweezers
Optical tweezers are tools made of light that enable contactless pushing,
trapping, and manipulation of objects ranging from atoms to space light sails.
Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have
evolved into sophisticated instruments and have been employed in a broad range
of applications in life sciences, physics, and engineering. These include
accurate force and torque measurement at the femtonewton level, microrheology
of complex fluids, single micro- and nanoparticle spectroscopy, single-cell
analysis, and statistical-physics experiments. This roadmap provides insights
into current investigations involving optical forces and optical tweezers from
their theoretical foundations to designs and setups. It also offers
perspectives for applications to a wide range of research fields, from
biophysics to space exploration
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Roadmap for optical tweezers
Optical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects, ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in the life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nano-particle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space exploration
Roadmap for optical tweezers
Optical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects, ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in the life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nano-particle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space exploration