Laboratoire Matière et Systèmes Complexes, UMR 7057, Université Paris Diderot, Sorbonne Paris Cité, Paris, France.
Biophys J. 2012 Jan 4;102(1):1-9. doi: 10.1016/j.bpj.2011.11.4004. Epub 2012 Jan 3.
Mechanical properties of the extracellular matrix (ECM) play a key role in tissue organization and morphogenesis. Rheological properties of jellyfish ECM (mesoglea) were measured in vivo at the cellular scale by passive microrheology techniques: microbeads were injected in jellyfish ECM and their Brownian motion was recorded to determine the mechanical properties of the surrounding medium. Microrheology results were compared with macrorheological measurements performed with a shear rheometer on slices of jellyfish mesoglea. We found that the ECM behaved as a viscoelastic gel at the macroscopic scale and as a much softer and heterogeneous viscoelastic structure at the microscopic scale. The fibrous architecture of the mesoglea, as observed by differential interference contrast and scanning electron microscopy, was in accord with these scale-dependent mechanical properties. Furthermore, the evolution of the mechanical properties of the ECM during aging was investigated by measuring microrheological properties at different jellyfish sizes. We measured that the ECM in adult jellyfish was locally stiffer than in juvenile ones. We argue that this stiffening is a consequence of local aggregations of fibers occurring gradually during aging of the jellyfish mesoglea and is enhanced by repetitive muscular contractions of the jellyfish.
细胞外基质（ECM）的力学性能在组织和形态发生中起着关键作用。通过被动微流变技术在细胞尺度上测量了水母 ECM（中胶层）的流变特性：将微珠注入水母 ECM 中，并记录它们的布朗运动，以确定周围介质的力学性质。将微流变学结果与通过剪切流变仪在水母中胶层切片上进行的宏观流变测量进行了比较。我们发现，在宏观尺度上，ECM 表现为粘弹性凝胶，而在微观尺度上，它表现为更软且异质的粘弹性结构。中胶层的纤维结构，如相差和扫描电子显微镜观察到的，与这些依赖于尺度的力学性质一致。此外，通过测量不同大小水母的微流变特性，研究了 ECM 在老化过程中的力学性质演变。我们测量到成年水母的 ECM 局部比幼年水母的更硬。我们认为，这种变硬是水母中胶层老化过程中纤维局部聚集逐渐发生的结果，并且受到水母肌肉反复收缩的增强。
