• Energy Research

AbstractThe implementation of probabilistic algorithms by deterministic hardware is demanding and requires hundreds of instructions to generate a pseudo‐random sequence of numbers. On the contrary, the dynamics at the molecular scale is physically governed by probabilistic laws because of the stochastic nature of thermally activated and quantum processes. By simulating the exciton transfer dynamics in a multi‐chromophoric system, we demonstrate the implementation of a random walk that samples the possible pathways of a traveler through a network and can be probed by time‐resolved fluorescence spectroscopy. The ability of controlling the spatial arrangement of the chromophores allows us to design the “landscape” in which the traveler is moving and therefore to program the molecular device.

Biomass composition of Chlamydomonas reinhardtii was studied during two consecutive cycles of 12h light/12h dark. As in our experimental conditions the two synchronized divisions were separated by 20h, it was possible to show that accumulation of dry weight, proteins, chlorophyll and fatty acids mainly depends on cell division, whereas starch accumulation depends on a circadian rhythm as reported previously. Our metabolomics analyses also revealed that accumulation of five (Ser, Val, Leu, Ile and Thr) of the nine free amino acids detected displayed rhythmicity, depending on cell division while Glu was 20-50 times more abundant than the other ones probably because this free amino acid serves not only for protein synthesis but also for biosynthesis of nitrogen compounds. In addition, we performed a thermodynamic-motivated theoretical approach known as 'surprisal analysis'. The results from this analysis showed that cells were close to a steady state all along the 48h of the experiment. In addition, calculation of free energy of cellular metabolites showed that the transition point, i.e. the state which immediately precedes cell division, corresponds to the most unstable stage of the cell cycle and that division is identified as the greatest drop in the free energy of metabolites.