CHROMATIN PATTERN BY VARIOGRAM ANALYSIS

Many cytological processes such as cell proliferation, differentiation , transformation, apoptosis, etc., are accompanied by specific chromat in changes, usually identified on the basis of the relative content of euchromatin and heterochromatin. In order to achieve a quantitative, non-subjective evaluation of the chromatin pattern, two different appr oaches may be undertaken, one consisting in the analysis of the severa l morphological features of chromatin grains (size, shape, density, ar rangement, and distribution), and the second consisting in the analysi s of the chromatin globally considered as a coherent texture. Although the second approach appears to be simpler and more suitable, methods of texture analysis-including those specifically designed for the anal ysis of the chromatin pattern-are rarely applied due mainly to the uns uitability of sampling procedures and the excessive crypticism of resu lts. As an alternative to traditional texture analysis, we suggest a m ethod supported by a sound mathematical theory and approximately 30 ye ars of applications in the field of geostatistics. The method, called variogram, analyzes the intrinsic structure of data sampled at differe nt distance intervals and directions, and outputs easily understandabl e results. Recently, variogram analysis has successfully been exported from geostatistics to other fields (for example, ecology and epidemio logy) that make use of spatially referenced variables. Based on the fa ct that pixels represent a perfect array of data ordered at regular di stance intervals and directions, the variogram can be adopted to explo re nuclear images and recognize chromatin patterns. Variograms of diff erent nuclei can be summarized by multivariate methods without the nee d of previous standardization of data. This allows comparison and disc rimination of chromatin patterns from mixed cell populations. Prelimin ary data obtained from young neurons undergoing massive apoptosis reve al a self-consistent map of nuclear changes correlated to the degenera tive process. (C) 1997 Wiley-Liss, Inc. <INF>