Oscillations In Yeast Cells Research Articles

A Nonlinear Delay Model for Metabolic Oscillations in Yeast Cells

A Nonlinear Delay Model for Metabolic Oscillations in Yeast Cells

Promotion and inhibition of synchronous glycolytic oscillations in yeast by chitosan.

Synchronous rhythmic activities play crucial roles in diverse biological systems. Glycolytic oscillations in yeast cells have been studied for 50 years with the aim of elucidating the mechanisms underlying the intracellular oscillations and their synchronization. We investigated the effects of chemical disturbances on the individual and collective glycolytic oscillations in yeast cells encapsulated in alginate microparticles, and demonstrated that the addition of chitosan, an antimicrobial agent, decreased the duration of these oscillations. In contrast, the periods and the synchronicity states showed two different responses to the chitosan treatments. The periods were shown to be prolonged following the treatment with 5-50 mg·L-1 and shortened at 75 mg·L-1 of chitosan. Collective oscillations became more synchronized at 5 mg·L-1 of chitosan, and desynchronized at 25-75 mg·L-1 of this compound. These findings can be explained by the balance between two chitosan features, increasing cell membrane permeability and acetaldehyde scavenging. At low concentrations, chitosan presumably acts as a synchronization promoter that does not mediate the synchronization itself but induces an increase in intercellular coupling. We believe that our findings may provide new insights into the synchronous rhythmic activities in biological systems.

Collective and individual glycolytic oscillations in yeast cells encapsulated in alginate microparticles.

Yeast cells were encapsulated into alginate microparticles of a few hundred micrometers diameter using a centrifuge-based droplet shooting device. We demonstrate the first experimental results of glycolytic oscillations in individual yeast cells immobilized in this way. We investigated both the individual and collective oscillatory behaviors at different cell densities. As the cell density increased, the amplitude of the individual oscillations increased while their period decreased, and the collective oscillations became more synchronized, with an order parameter close to 1 (indicating high synchrony). We also synthesized biphasic-Janus microparticles encapsulating yeast cells of different densities in each hemisphere. The cellular oscillations between the two hemispheres were entrained at both the individual and population levels. Such systems of cells encapsulated into microparticles are useful for investigating how cell-to-cell communication depends on the density and spatial distribution of cells.

Electrical stimulation of the energy metabolism in yeast cells using a planar Ti-Au-Electrode interface

We report on the influence of dielectric pulse injection on the energy metabolism of yeast cells with a planar interdigitated electrode interface. The energy metabolism was measured via NADH fluorescence. The application of dielectric pulses results in a distinct decrease of the fluorescence, indicating a response of the energy metabolism of the yeast cells. The reduction of the NADH signal significantly depends on the pulse parameters, i.e., amplitude and width. Furthermore, the interface is used to detect electrical changes in the cell-electrolyte system, arising from glucose-induced oscillations in yeast cells and yeast extract, by dielectric spectroscopy at 10 kHz. These dielectric investigations revealed a beta(1)-dispersion for the system electrolyte/yeast cells as well as for the system electrolyte/yeast extract. In agreement with control measurements we obtained a glycolytic period of 45 s for yeast cells and of 11 min for yeast extract.

Oscillations in Biochemical Systems

AbstractThe general requirements for the occurence of oscillations in a number of various biochemical systems are reviewed. Experimental demonstration of oscillating states in mitochondria, in intact yeast and slime mould cells are given. To demonstrate the minimum requirements for a biochemical oscillator the mechanism of glycolytic oscillations in yeast cells under homogeneous and nonhomogeneous conditions in space is described together with an example of a model subjected to numerical analysis. The general significance of instable states for the creation of domains in time and space is stressed.

Metabolite Concentrations and Phase Relations in d‐Fructose Induced Glycolytic Oscillations

AbstractThe frequency of glycolytic oscillations in yeast cells is only slightly modified by the consumption rate of either glucose or fructose, but it is reduced to 1 /2 to 2/3 if the ketohexose is the only substrate.Phase relations between NADH, adenine nucleotides and sugar phosphates (G‐6‐P, F‐6‐P, FDP, DAP) are independent of the hexose fermented.With fructose as a substrate the amplitudes of adenylates and hexose phosphates are distinctly smaller than with glucose. The maximum of G‐6‐P is higher with glucose and the minimum concentration of FDP is higher with fructose.In the transition to anaerobiosis FDP, adenosine 5′‐diphosphate and adenosine 5′‐phosphate are extremely high, whereas G‐6‐P, F‐6‐P and ATP concentrations are lower if fructose is the substrate fermented.The results are indicative for different control characteristics of the phosphofructokinase step, but on their basis it cannot be distinguished between a direct interaction of fructose (or one of its derivatives) on the phosphofructokinase kinetics or the existence of a bypass for fructose which might be able to withdraw a part of the substrate from the control point at the phosphofructokinase.