The shape of mitochondria and the number of mitochondrial nucleoids during the cell cycle of Euglena gracilis

Abstract

The shape of mitochondria and the number of mitochondrial nucleoids in Euglena cells were examined throughout the cell cycle by fluorescence microscopy. Both photoheterotrophic and heterotrophic cells contained a network of mitochondria that did not divide into fragments at any stage of the cell cycle. Mitochondrial nucleoids could be clearly detected in the mitochondria by staining with ethidium bromide and with DAPI. Half of the mitochondrial nucleoids entered each daughter cell during cytokinesis. Nucleoids in the newly produced daughter cells increased in number as the cells increased in size. The number of nucleoids reached double the initial value in cells at the stage just prior to mitosis. The total length of the mitochondrial net was proportional to the cell volume.