Effects of deuterium oxide on cell growth and vesicle speed in RBL-2H3 cells

Abstract

For the first time we show the effects of deuterium oxide on the cell growth and vesicle transport in rat basophilic leukemia (RBL-2H3) cells. RBL-2H3 cells cultured with 15 moles/L deuterium showed decreased cell growth which was attributed to cells not doubling their DNA content. Experimental observations also showed an increase in vesicle speed for cells cultured in deuterium oxide. This increase in vesicle speed was not observed in deuterium oxide cultures treated with a microtubule-destabilizing drug suggesting that deuterium oxide affects microtubule-dependent vesicle transport. PrePrints INTRODUCTIONRoughly 70% of Earth's surface and animal bodies are made out of water (H 2 O). Very few, if any, biological systems or reactions will function without water and one may conclude that the properties of H 2 O are essential for life on Earth. In recent years research has indicated that water plays an active role in how biomolecules recognize and bind to each other (Ball, 2011). For example, in a biological system when a protein binds its ligand, associates with another protein, or folds into its functional form, the surrounding solvent must get out of the way. How water may act as a versatile intermediary and facilitator during these processes is still under investigation (Ball, 2011).To study the effect of water (H 2 O), one must find ways to change the properties of H 2 O. This can be accomplished by substituting hydrogen (H) by its heavier deuterium (D) isotope resulting in deuterium oxide (D 2 O), also known as heavy water or heavy-hydrogen water. All naturally-occurring water contains approximately 150 parts per million D and therefore, D 2 O may be essential for some life forms (Lewis, 1934). Deuterium contains one proton and one neutron and bonds to oxygen (O) much stronger than H (one proton and no neutron) in H 2 O. This results in small differences in the length of the covalent H-O-bonds and the angles between them, thus making D 2 O roughly 11% denser and 25% more viscous than H 2 O at 20 o C (Hardy and Cottington, 1949). Due to the natural occurrence of D 2 O and differences in chemical structure and physical properties compared to H 2 O, researchers have used D 2 O to study the effects of water on biomolecules and cells. Studies include effects of D 2 O on tobacco seed growth (Lewis, 1934), IgE-Mediated histamine release from human leukocytes (Gillespie and Lichtenstein, 1972), actin filament velocities (Chaen et al., 2001), protein flexibility (Cioni and Strambini, 2002), human pancreatic tumor cells (Hartmann et al., 2005), phospholipid membranes (Beranova et al., 2012), kinesin-1 gliding assay (Maloney et al., 2014), and stabilization of tubulin as observed previously in microtubule gliding assays (Panda et al., 2000) and in biochemical experiments on isolated tubulin proteins from beef brain (Houston et al., 1974) and goat brain (Das et al., 2008). Microtubules are polarized polymers of α/β tubulin heterodimers and undergo alternating phases of growth and shrinkage with sudden transitions betwe...