A New Analytical Method for Calcium Quantification in Danio rerio Scales

The scale of Danio rerio is an ossified tissue which can be analyzed histologically, biochemically and immunohistochemically. In this paper we describe and characterize the validation of a new colorimetric procedure for the quantification of the calcified component of the fish scale. This method is based on the use of ARS that specifically binds the calcium of the bone matrix and of the EDTA, a chelating agent that competes with ARS for the binding of calcium. The release of the ARS from the scale can be quantified measuring the absorbance of the alizarin red contained  in the EDTA extraction solution  since it is proportional to scale calcium content, then it can be considered an index of the degree of mineralization of the scale itself. This new method is proved to be accurate, precise, based on linear regression and allows a greatcharacterization of scale mineral content. Then, it can be very helpful to evaluate the mineral alterations induced by different pathologies in bone metabolism studies.