Smarter ways with water

Abstract

In just a few months this year, abnormally low water levels in rivers led China to shut down factories and to floods in one-third of Pakistan, killing around 1,500 people and grinding the country to a halt. A dried-up Rhine River threatened to tip Germany's economy into recession, because cargo ships could not carry standard loads. And the Las Vegas strip turned into a river and flooded casinos, chasing customers away. It seems that such water disasters pepper the news daily now.Peru's water utility companies are protecting peat bogs because of their ability to hold water.

Cytoskeletal activation of NHE1 regulates mechanosensitive cell volume adaptation and proliferation

“…This hypothesis should be examined in future work, although we note that in HT1080 cells that lacks SVI, mitotic swelling is still present. In addition, a series of recent works showed that water flux driven by ion transport is responsible for cell migration in 1D confinement and 2D environments, and NHE is one of the central players activated by actomyosin dynamics ( 8, 10, 11, 17 ). These results hint that the cell volume dynamics is associated with cell migration, and the mechanical activation of NHE1 is another way for cells to generate protrusions and motility.…”

“…On the other hand, mitotic cells can swell and increase their volume by 10-20% in minutes without producing extra mass ( 4, 5 ). Moreover, short timescale cell volume changes can generate mechanical forces for cell rounding ( 4, 6 ), provide space for chromosome segregation ( 7 ), and also impact cell migration ( 8–11 ).…”

“…When the cell size and shape are steady, any hydraulic pressure gradient is mechanically balanced by tension in the cell membrane and the actomyosin cortex ( 14 ). As a consequence, cell volume is sensitive to both environmental physical and chemical variables, including extracellular osmolarity ( 1, 10, 15, 16 ), media viscosity ( 11, 17 ), substrate stiffness or geometry ( 18–21 ), hydraulic resistance ( 11, 22, 23 ), and confinement ( 24 ).…”

“…Ion “pump and leak” has been identified as a major mechanism in volume regulation ( 1, 25 ), involving Na + and K + fluxes through ion pumps, exchangers and channels such as sodium-potassium ATPases (NKA) and sodium-hydrogen exchanger (NHE). The latter has been shown to be involved in mitotic swelling and cell migration ( 5, 8, 11 ). Actomyosin contractile force has been proposed as another way to control cell volume ( 6, 12, 26, 27 ).…”