Number & Brightness analysis of rest fluorescence in Xenopus lævis oocytes reveals the differential ability of calcium dyes to detect intracellular signals.

ESTEFANÍA PIEGARI*, LUCÍA LOPEZ, EMILIANO PEREZ IPIÑA AND SILVINA PONCE DAWSON.

San Javier, Tucumán

Congreso; XLI Reunión Anual de la Sociedad Argentina de Biofísica; 2012

Sociedad Argentina de Biofísica

Calcium signaling is ubiquitous across cell types. Intracellular calciumsignals are observed in intact cells with a minimum disruption usingcalcium dyes. The most commonly used indicators fluoresce upon calciumbinding, thus providing information on the calcium-bound dyeconcentration. These dyes can also fluoresce in the absence of calciumalbeit with less intensity. This additional fluorescence affects thedetectability of calcium signals and can introduce a nonlinear relationshipbetween the observed fluorescence and the underlying calcium bound dyedistribution. In this work we combine experiments performed in oocytes ofXenopus laevis and numerical simulations to study in detail the behavior oftwo popular dyes, Fluo 4 and Rhod 2, under basal conditions. From thisanalysis we determine the fraction of the fluorescence that is due to free dyeand establish the conditions under which both dyes can detect calciumsignals with equivalent signal to noise ratios.