Ultra-violet time lapse motion picture observations of mitosis in newt cells

Abstract

These data indicate that it is quite feasible to take time lapse motion pictures of the ultra-violet absorption images of living cells as they pass through mitosis. The use of the ultra-violet flying spot television microscope for this purpose makes it possible to reduce the amount of ultra-violet irradiation required to levels which produce no evidence of irradiation damage in the majority of instances. One possible evidence of ultra-violet irradiation damage which was observed, was the development of a pronounced chromosomal bridge persisting entirely through telophase. One change which was questionably related to ultra-violet irradiation was marked accentuation of telophase bubbling. In occasional instances one entire new chromosomal mass was extruded into such a bubble. These phenomena did not, however, appear to be related to the length of time of the ultra-violet scanning as identical findings were observed to occur in similar cells illuminated by visible light and in cells which were displaying these changes at the time ultra-violet scanning began during mitosis. When the chromosomes were physically separated by some distance from each other they were easily individually resolved. When they were in close physical proximity to each other, such as during metaphase, they appeared as a large densely absorbing mass. At no time during mitosis did the absorption of individual chromosomes appear to change. Nuclear reconstruction following telophase was soon followed by a generalized decrease in nuclear absorption but cells were not followed to a complete interphase state.