Microscopic diffusion processes measured in living planarians

Abstract

Living planarian flatworms were probed using quasielastic neutron scattering to measure, on the pico-to-nanosecond time scale and nanometer length scale, microscopic diffusion of water and cell constituents in the planarians. Measurable microscopic diffusivities were surprisingly well defined in such a complex system as living animals. The overall variation in the microscopic diffusivity of cell constituents was found to be far lower than the variation in the microscopic diffusivity of water in planarians in a temperature range of 284.5 to 304.1 K.

Water dynamics in MCF-7 breast cancer cells: a neutron scattering descriptive study

“…Because the motions of purely bulk water molecules are usually too broad (fast) to be discernable from the background due to the instrumental design of BASIS, any bulk-like behavior observed in this descriptive study is likely attributable to water inside the cells, rather than extracellular water, whose dynamic properties are expected to be much closer to pure bulk behavior 20 .…”

“…While rotation of molecules do not show any clear Q-dependence in the QENS signal width, the same is not true for translational motions 18 . Also, by representing the QENS as the imaginary part of the susceptibility 19,20 :where n B ( T , E ) is the temperature Bose factor, different relaxation processes can be clearly separated; changes in peaks position, shape and/or intensity are good indications for Q-dependent processes, i.e. water diffusion.…”

Role of intracellular water in the normal-to-cancer transition in human cells—insights from quasi-elastic neutron scattering

“…Discrimination of the distinct dynamical processes taking place within heterogeneous cellular matrices relies on an accurate fitting of the experimental results. This was accomplished using one δ-function (elastic component) convoluted with the line shape of the instrument and Lorentzian functions to represent the quasi-elastic contributions, according to the model previously optimized by the authors for breast carcinoma cells 25 and already applied successfully to represent microscopic diffusion processes in osteosarcoma cells 27 and other biological systems (such as living planarians 43 ). Actually, as previously found, 25,27 these are too complex systems to be accurately reproduced with only two Lorentzian functions (Γ global and Γ local ): apart from Γ local that characterizes the fast localized dynamics of the biomolecules (e.g., DNA, proteins, and lipids, which cannot be discriminated) and the rotation of cytosolic water, two other Lorentzians are required to represent the intracellular water molecules, which have distinct dynamical regimes depending on their location—either in the cytoplasm (with a higher mobility, Γ global/cyt ) or in the constrained hydration layers around biomolecules (Γ global/hyd ).…”

Neutron scattering in the biological sciences: progress and prospects

“…Furthermore, it is possible that changes in dynamics can be probed in situ by employing mutants of the system under study lacking some of the components for comparison or through time separation in scattering experiments (Martinez et al, 2016). The evolution of dynamics of living cells under different external conditions can be monitored by neutron scattering techniques, taking advantage of the many possible sample environments (Stingaciu et al, 2016;Mamontov, 2017Mamontov, , 2018. QENS has mostly been used to probe picosecond and nanosecond motions in biomacromolecular systems (Shrestha et al, 2016).…”

“…Another important aspect is to understand how crowded biological systems respond to environmental changes. Indeed, macromolecular crowding is a crucial component that is needed to understand the energetics and kinetics of biological processes in living systems (Erlkamp et al, 2015;Stingaciu et al, 2016;Mamontov, 2017Mamontov, , 2018 and is a prerequisite for the design of industrially relevant enzymatic reactions (Gao et al, 2017). One interesting example is the study of the protective effects of osmolytes (or other co-solutes) in living cells against hostile conditions for life (Al-Ayoubi et al, 2017).…”