RESUMO
The influence of actin and tubulin cytoskeletons on the shape, division and on intracellular motility of mitochondria was studied in eggs and embryos of the sea urchin Paracentrotus lividus. Depolymerization of actin filaments and microtubules was induced by specific inhibitors as cytochalasin D (CytD) and colcemid respectively. The quantitative analysis of the mitochondrial population shows that: 1) the chondriome of an egg consists of numerous (about 15,000) discrete mitochondrial clusters uniformly distributed throughout the cytoplasm, each cluster containing 10 to 20 mitochondria of spherical or rod-like shape; 2) fertilization induces cluster break-down and mitochondrial division within 15 min after insemination; at 100 min after fertilization mitochondria become evenly distributed throughout the cytoplasm and the population of mitochondria doubles; 3) in embryos obtained from eggs inseminated after treatment with CytD clusters break-down and mitochondriokinesis are blocked; 4) when added 15 min after insemination, CytD uncouples coordinated invagination of outer and inner membranes in dividing mitochondria thus bringing about abnormal mitochondriokinesis; 5) the treatment of the eggs with colcemid does not affect the normal embryonic mitochondriokinesis.
