Spatiotemporal dynamics of single cell stiffness in the early developing ascidian chordate embryo

摘要

a Schematic of AFM for measurement of the developing ascidian embryo weakly adhered on a dish in seawater. The inset shows an optical microscopic image of the customised colloidal probe cantilever arranging two silica beads from the AFM tip with epoxy glue. Scale bar, 10 μm. b Example of a bright-field optical microscopic image and AFM topographic, i.e., relative height H, and apparent Young’s modulus E, images of the ascidian embryo at around the 32-cell stage. The measured embryonic cells and cell lineage were identified by comparing the AFM images with a 3D model52. The values of soft and hard presented here are ν = 1.4 and 2.8 of ν = log10E (Pa), respectively. c Morphological change in the 3D ascidian embryo model at early developmental stages from the fertilised egg to the 112-cell stage before gastrulation, measured by AFM. Dotted line (red) represents the anterior–posterior line of the embryo. d Typical AFM force–distance curve measured in an upper region of a developing embryo sample. As shown in the inset, the force-indentation curve within 2 μm of the indentation depth δ followed the power law of 3/2, which corresponds to both conventional and modified Hertzian contact models (‘Methods’).