Proliferative activity during development studied as stochastic point process.

MAZZEO J; RAPACIOLI M; SANCHEZ V; SCICOLONE G; DATTELLIS C; FLORES V

Buenos Aires, Argentina

Congreso; XII Congreso Latinoamericano y 1ro IberoAmericano de Cs Fisiológicas.; 2006

Asociacion Latinoamericana de Ciencias Fisiologicas y Sociedad Argentina de Fisiologia.

Proliferative activity during development studied as stochastic point process. J Mazzeo, M Rapacioli, V. Sanchez, G. Scicolone, C. D’Attellis, V Flores Interdisciplinary Group in Theoretical Biology, Favaloro University. The generation of complex histological patterns during development requires the organized operation of several developmental cell behaviors, one of them is cell proliferation. Our goal is to design a mathematical model which could help to understand the specific role of proliferation in the CNS morphogenesis. Classical approaches analyze cell proliferation by computing the mitotic index (rate between the number of proliferating cells and the total cell count in a given area) disregarding the local variability On this work we, alternatively, record proliferative activity on a cell by cell basis. We analyze these records as stochastic point processes as a function of space (cephalic-caudal axis) and time (stages of development). Fractal characteristics (self-similarity) were explored by means of DFA, Fano Factor and PSD. As a general rule, results reveal temporal and spatial organization. We evaluated the impact of changes in the spatial resolution of experimental records on the estimation of the scaling index. This was accomplished by processing both experimental and simulated records. Scaling index estimators such as DFA, Fano Factor and PSD were studied.  The results of our simulations show that even when resolution changes in several orders of magnitude no significant changes in the estimation of the scaling index is observed. However, if change in resolution exceeds a defined threshold level, the estimates substantially deviate from the original values. Sensitivity to changes in resolution is different for each one of the algorithms. We also processed experimental records which were built with different spatial resolution. Results agree with predictions provided by simulations. This study emphasizes the fact that the proliferation activity displays a temporal and a spatial organization that cannot be described with classical methods based on the mitotic index. Supported by grants from CONICET and UBACYT (Argentina)