In this study we focus on the physical properties of Xenopus laevis PGCs during their transition from the passive to the active migratory state.
As scombrids are active migratory fishes with high Mb, this suggests the existence of a further independent origin for Mb deficit.
This demonstration of active migratory behaviour in δ-opioid receptor-OE keratinocytes confirms and provides functional evidence for δ-opioid receptor-mediated cell migration.
In the context of this study, we investigated the adhesive and dynamic behavior of Xenopus laevis PGCs before and after their transition to the active migratory state.
To quantify the formation of bleb-like protrusions during PGC migration, we investigated cellular dynamics of PGCs before and after transition to the active migratory state using electric cell-substrate impedance sensing (ECIS), in conjunction with time-lapse image analysis.
We conclude that the overall adhesiveness of pre-migratory PGCs is higher compared to PGCs in the active migratory state (supplementary material Table S2), particularly regarding their interaction with the extracellular matrix protein fibronectin.
This is indeed also reflected in our single-cell force spectroscopy experiments monitoring a decline in the maximum adhesion force of about 18% after PGCs reach the active migratory stage.
The mechanisms by which the small micromeres make their way to the coelomic pouch is a topic of debate: one paper cites an active migratory event while another a passive translocation during gastrulation (Yajima and Wessel, 2012; Campanale et al., 2014).
