Piezotolerance of the cytoskeletal structure in cultured deep-sea fish cells using DNA transfection and protein introduction techniques.

We used DNA transfection and protein introduction techniques to investigate the pressure tolerance of cytoskeletal structures in pectoral fin cells derived from the deep-sea fish Simenchelys parasiticus (habitat depth, 366–2,630 m). The deep-sea fish cells have G418 resistance. The cell number increased until day 6 of cultivation and all cells had died by day 35 when cultured in 35-mm Petri dishes in medium containing G418. Enhanced yellow fluorescent protein-tagged human β-actin (EYFP-actin) was stably expressed by 1 in 100,000 deep-sea fish cells. Because almost none of the EYFP-actin was incorporated into actin filaments of the cells, we replaced the relatively large EYFP tag with a chemical fluorescent compound and succeeded in incorporating fluorescently labeled rabbit actins into the deep-sea fish actin filaments. Most of the filament structure in the cells with rabbit actin inserted underwent depolymerization when subjected to pressure of 100 MPa for 20 min, in contrast to control cells. There were no differences in the tubulin filament structure between control cells and deep-sea fish cells with fluorescein-labeled bovine tubulin inserted after the application of pressure ranging from 40 to 100 MPa for 20 min.