EFFECT OF CHRONIC HYPOXIA ON THE CHICK EMBRYO OPTIC TECTUM NEUROEPITHELIAL CELLS PROLIFERATION

DUARTE, SANTIAGO; RAPACIOLI, MELINA; RODRÍGUEZ CELÍN, ALEJANDRA; DI NÁPOLI, JENNIFER; TERUEL, LUISA; SANCHEZ, VIVIANA; SCICOLONE, GABRIEL; FLORES, VLADIMIR

Santa Cruz

Congreso; 5th International Meeting of the Latin American Society for Developmental Biology; 2010

Latin American Society for Developmental Biology

EFFECT OF CHRONIC HYPOXIA ON THE CHICK EMBRYO OPTIC TECTUM NEUROEPITHELIAL CELLS PROLIFERATION Santiago Duarte1,2, Melina Rapacioli1, Alejandra Rodríguez Celín1, Jennifer Di Napoli2, Luisa Teruel2, Viviana Sánchez2, Gabriel Scicolone2 and Vladimir Flores1,2 1 Interdisciplinary Group in Theoretical Biology, Depart. Biostructural Sciences, Favaloro University. 2 Lab. Developmental Neurobiology. Inst. Cell Biol. and Neurosci. “Prof. E. de Robertis”, FMed, UBA. vflores@favaloro.edu.ar   The present work analyzes hypoxia-induced changes on the neuroepithelial cells proliferation dynamics in the developing chick optic tectum. A 48h-aerogenic hypoxia (23% decrease PO2–32% increase PCO2), starting at E2 and E4 produced 23% and 50% reduction in mitotic density respectively. Clustering analyses of mitotic cells spatial organization reveals a power-law relationship between “number of clusters” vs. “inter-cluster gaps length” and a hierarchical organization (fractality) of mitotic cells. Over short range scales analyses (i.e. 5-16 µm) hypoxia produced a decrease in the slope of the log-log plot of the number of clusters vs. inter-cluster distance at both E4 and E6 (30% and 50% respectively). At larger scales hypoxia produced a shift to the right of the lines indicating an increase in the number of clusters separated by large distances. Interestingly, at each age there was a number of a typical inter-cluster length, i.e. segment occupied by interphasic cells, that remained unchanged under hypoxia. In fact, the number or clusters separated by 5-7 µm in E4 and 10-16 µm in E6 do not change under hypoxia suggesting that at short-range scales the decrease in mitotic cells occurs at the central region of the smaller clusters. The changes observed at long-range scales are due to the decrease in the mitotic density and increase in the number of larger inter-cluster gaps. Immunohistochemistry evaluation of Notch and NeuroD expression suggests that hypoxia alters the temporal shift between proliferation associated to neuroepithelial cell expansion and neuronogenic proliferation.   Grant sponsors: CONICET and Fundación Florencio Fiorini.