Intracellular calcium signals display an avalanche-like behavior over multiple lengthscales.

Frontiers in Physiology

Lorena eSigaut¹  Lucía eLopez¹  Estefanía ePiegari¹  Silvina ePonce Dawson¹ 

[1] FCEyN, UBA;

关键词: Phase Transition;    Percolation;    self-organized criticality;    alcium signals;    puffs;    calcium signals;   

DOI  :  10.3389/fphys.2012.00350

来源: DOAJ

【 摘 要 】

Many natural phenomena display "self-organized criticality''(SOC). This refers to spatially extended systems forwhich patterns of activity characterized by different lengthscalescan occur with a probability density that follows a power law withpattern size. Differently from power laws at phase transitions,systems displaying SOC do not need the tuning of an externalparameter. Here we analyze intracellular calcium Ca2+signals, a key component of the signaling toolkit of almost any celltype. Ca2+ signals can either be spatially restricted (local)or propagate throughout the cell (global). Different models havesuggested that the transition from local to global signals issimilar to that of directed percolation. Directed percolation hasbeen associated, in turn, to the appearance of self-organizedcriticality. In this paper we discuss these issues within theframework of simple models of Ca2+ signal propagation.We alsoanalyze the size distribution of local signals ("puffs'') observedin immatureXenopus Laevis oocytes. The puff amplitudedistribution obtained from observed local signals is not Gaussianwith a noticeable fraction of large size events. The experimentaldistribution of puff areas in the spatio-temporal record of theimage has a long tail that is approximately log-normal.Thedistribution can also be fitted with a power law relationship albeitwith a smaller goodness of fit.The power law behavior isencountered within a simple model that includes some coupling amongindividual signals for a wide range of parameter values. An analysisof the model shows that a global elevation of the Ca2+ concentrationplays a major role in determining whether the puff size distributionis long-tailed or not. This suggests that Ca2+-clearing from thecytosol is key to determine whether IP3-mediated Ca2+ signals candisplay a SOC-like behavior or not.

【 授权许可】

Unknown