Multivariate statistical analysis of electron probe microanalytical data on cell nuclear constituents.

A multivariate statistical analysis (the principal component analysis) has been used to process electron probe microanalytical data from cell nuclei. Fifty-seven measurements from different areas of chromatin and nucleolus in follicular rat cells have been studied. The variables are the X-ray characteristic signals for P, S, Al, Fe, Cu and Zn. This method demonstrates three groups of individuals - the chromatin area which is associated with a stronger concentration of P and two groups of nucleolar areas, one of them being connected with a higher content in S, Al and Zn. This high degree of correlation between these three elements proves the chemical affinity of the metals with the protein, S being the signature for proteins.