Human Osteosarcoma Cellular Endosomes

Fluorescence emission intensity from a culture of human fetal bone osteosarcoma (U2OS line) epithelial cells that were transfected with a pEYFP-Endosome plasmid subcellular localization vector. Cells were transiently transfected and cultured in nutrient medium for a minimum of 24 hours before recording images. The enhanced yellow fluorescent protein gene used in these studies contains several important amino acid substitutions that shift the emission maximum of green fluorescent protein (GFP) by approximately 18 nanometers, from 509 to 527 nanometers. However, the fluorescence emission still appears green when observed in the microscope eyepieces. Note the fluctuating level of green fluorescence defining the endosomal network, which tends to exhibit a higher degree of signal in areas adjacent to the nucleus.