Cellular communication through light

Abstract

Information transfer is a fundamental of life. A few studies have reported that cells use photons (from an endogenous source) as information carriers. This study finds that cells can have an influence on other cells even when separated with a glass barrier, thereby disabling molecule diffusion through the cell-containing medium. As there is still very little known about the potential of photons for intercellular communication this study is designed to test for non-molecule-based triggering of two fundamental properties of life: cell division and energy uptake. The study was performed with a cellular organism, the ciliate Paramecium caudatum. Mutual exposure of cell populations occurred under conditions of darkness and separation with cuvettes (vials) allowing photon but not molecule transfer. The cell populations were separated either with glass allowing photon transmission from 340 nm to longer waves, or quartz being transmittable from 150 nm, i.e. from UV-light to longer waves. Even through glass, the cells affected cell division and energy uptake in neighboring cell populations. Depending on the cuvette material and the number of cells involved, these effects were positive or negative. Also, while paired populations with lower growth rates grew uncorrelated, growth of the better growing populations was correlated. As there were significant differences when separating the populations with glass or quartz, it is suggested that the cell populations use two (or more) frequencies for cellular information transfer, which influences at least energy uptake, cell division rate and growth correlation. Altogether the study strongly supports a cellular communication system, which is different from a molecule-receptor-based system and hints that photon-triggering is a fine tuning principle in cell chemistry.

Figure 1. Transmission of electromagnetic waves through 1.5 mm of cuvette material.

The graph shows the wavelengths where transmission through glass differs from transmission through quartz.

Figure 2. Vertical section of an experimental unit of small and large cuvettes.

Arrows pointing at the inner cuvette show the molecule barrier. Arrows going through the inner cuvette refer to photon transmission.

Figure 3. Mutual effects on growth between optically coupled cell populations.

The graph shows in the upper row the sizes of the larger outer populations and in the lower row those of the smaller inner populations. The filled squares refer to treatments using glass cuvettes, the open squares to those with quartz cuvettes. The x-axis shows the three treatment groups: paired are the combined (outer and inner) populations; C1 refers to the controls using medium instead of a second population and C2 is the control with demineralised water.

Figure 4. Effects from cells in the inner cuvette to cells in the outer cuvette.

The graph shows the combined effects of material and presence or absence of cells in the inner cuvette on cell growth in the outer population. Filled squares refer to separation by glass and open squares to separation by quartz.

Figure 5. The coupling of growth between outer and inner population.

The upper graph represents the significantly better growing paired populations separated by glass while the lower graph refers to the reduced growth of paired populations separated by quartz (compare fig 4, right half).

Figure 6. Effects of neighbouring cells on vacuole formation (energy uptake).

The population size in the outer cuvette reflected either the size of the population in the inner cuvette (15 or 20) or a 20-fold of it (300 or 400). Filled squares refer to separation with glass, open squares to separation with quartz.