Bending with high curvature is one of the major mechanical properties of double‐stranded DNA (dsDNA) that is essential for its biological functions. The emergence of a kink arising from local melting in the middle of dsDNA has been suggested as a mechanism of releasing the energy cost of bending. Herein, we report that strong bending induces two types of short dsDNA deformations, induced by two types of local melting, namely, a kink in the middle and forks at the ends, which we demonstrate using D‐shaped DNA nanostructures. The two types of deformed dsDNA structures dynamically interconvert on a millisecond timescale. The transition from a fork to a kink is dominated by entropic contribution (anti‐Arrhenius behavior), while the transition from a kink to a fork is dominated by enthalpic contributions. The presence of mismatches in dsDNA accelerates kink formation, and the transition from a kink to a fork is removed when the mismatch size is three base pairs.

We study the unexpected high flexibility of short dsDNA which recently has been reported by a number of experiments. Via the Langevin dynamics simulation of our Breathing DNA model, first we observe the formation of bubbles within the duplex and also forks at the ends, with the size distributions independent of the contour length. We find that these local denaturations at a physiological temperature, despite their rare and transient presence, can lower the persistence length drastically for a short DNA segment in agreement with experiment.

Quantitatively understanding of the dynamics of an active Brownian particle (ABP) interacting with a viscoelastic polymer environment is a scientific challenge. It is intimately related to several interdisciplinary topics such...

Membrane nanotubes or tunneling nanotubes (TNTs) that connect cells have been recognized as a previously unidentified pathway for intercellular transport between distant cells. However, it is unknown how this delicate structure, which extends over tens of micrometers and remains robust for hours, is formed. Here, we found that a TNT develops from a double filopodial bridge (DFB) created by the physical contact of two filopodia through helical deformation of the DFB. The transition of a DFB to a close-ended TNT is most likely triggered by disruption of the adhesion of two filopodia by mechanical energy accumulated in a twisted DFB when one of the DFB ends is firmly attached through intercellular cadherin-cadherin interactions. These studies pinpoint the mechanistic questions about TNTs and elucidate a formation mechanism.

Bending with high curvature is one of the major mechanical properties of double-stranded DNA(dsDNA) that is essential for its biological functions.The emergence of akink arising from local melting in the middle of dsDNAh as been suggested as am echanism of releasing the energy cost of bending. Herein, we report that strong bending induces two types of short dsDNAd eformations,i nduced by two types of local melting, namely,akink in the middle and forks at the ends,w hich we demonstrate using D-shaped DNAn anostructures.T he two types of deformed dsDNAs tructures dynamically interconvert on am illisecond timescale.T he transition from af ork to ak ink is dominated by entropic contribution (anti-Arrhenius behavior), while the transition from akink to afork is dominated by enthalpic contributions. The presence of mismatches in dsDNAa ccelerates kink formation, and the transition from akink to afork is removed when the mismatchsize is three base pairs.