Figure 2.
Temperature-induced volume transitions in isolated HL60 nuclei. (A) Schematic of OS operating with 1064 nm (significant heating) or 780 nm wavelength (reduced heating). Nuclei flowing through the microfluidic channel were serially trapped and stretched/heated by two counterpropagating laser beams. (B) Deformation curves for nuclei stretched in a 780 nm OS at 1.6 W at . In heavy water (black, n = 104), nuclei showed positive (and negative) deformation along the major (solid circle) and minor axes (open circle), respectively, indicating volume conservation. Replacing heavy water with deionized water led to an increase in temperature jump and swelling along both the major and minor axes (red, n = 108). (C) Deformation curves for nuclei stretched in a 1064 nm OS at 1.6 W at , in heavy (black, n = 85) and deionized water (red, n = 53). (D) Deformation curves for nuclei stretched in a 780 nm OS at 1.6 W at . Similar volume conservation in heavy water (black, n = 53) and swelling in deionized water (red, n = 60) were observed. (E) Temperature-induced volume change of nuclei at different ambient temperatures, based on collective data from both 780 and 1064 nm OS. n > 40 for each data point. (F) Volume changes for nuclei in response to linearly increasing laser powers in 1064 nm OS at 23°C. Maximum power reached was 2.2 W . Heat ramp was performed over 1 s (black, n = 24), 5 s (red, n = 37), 12 s (blue, n = 22), and 60 s (magenta, n = 10), with the respective rates of heat increase indicated in the legend. All error bars denote SE. To see this figure in color, go online.