The mitochondrion in mitotic and starved cells of Bullera alba

Abstract

Bullera alba is an imperfect yeast-like fungus in which mitosis has been studied ( Taylor and Wells, 1979a , Taylor and Wells, 1979b , Protoplasma, in press). This study correlates mitochondrial behavior with nuclear and cell division and compares mitochondria of starved and growing cells. Light microscopy and computer reconstructions of electron micrographs of serially sectioned cells were used to determine the morphology, anatomy, and volume of mitochondria. Polarographic measurement of oxygen consumption was used to assay mitochondrial activity. One large mitochondrion was found in starved and premitotic cells and one, two, or three mitochondria were found in mitotic cells of B. alba. The morphology of mitochondria from starved and growing cells was similar. The fine structure of mitochondria in starved cells was different from that of growing cells, and the volume of the mitochondrion compared to the volume of the total cytoplasm was lower in starved cells than in growing cells. Also, starved cells respired at much lower levels than growing cells. This difference was partially reduced by the addition of substrate to starved cells and completely erased after 7 h in fresh substrate.