Philip H. Jones, Onofrio M. Maragò & Giovanni Volpe
Fig. 13.4 — Twisting DNA
(a) Torque is applied to dsDNA by the rotation of an optically trapped disc-shaped particle whose orientational angle is controlled by the polarisation direction of the trapping light. (b) Experimental system for overwinding a DNA molecule by rotating a micropipette while maintaining the DNA under tension using the optical trap. (c) Unwinding of overwound DNA with accompanying change in length and structural transformation. (d) Torque applied to DNA by rotation of a nanofabricated birefringent quartz cylinder. (e) Buckling of DNA on overwinding indicative of plectoneme formation.
Figure (a) is reprinted from Oroszi et al., Phys. Rev. Lett. 97, 058301. Copyright (2006) by the American Physical Society.
Figures (b) and (c) are reprinted by permission from Macmillan Publishers Ltd: Bryant et al., Nature 424, 338–41, copyright 2003.
Figure (d) is reprinted by permission from Macmillan Publishers Ltd: Deufel et al., Nature Methods 4, 223–5, copyright 2007.
Figure (e) is reprinted from Forth et al., Phys. Rev. Lett. 100, 148301. Copyright (2008) by the American Physical Society.