Lethal consequences of simulated solar radiation on the nematode Caenorhabditis elegans in the presence and absence of photosensitizers

The partial destruction of the earth's protective ozone layer has raised concerns about the impact of increased UV radiation on the earth's biological systems. In this study, polychromatic light sources were employed to observe the biological responses of the soil nematode Caenorhabditis elegans to simulated solar UV. Using various filter combinations, action spectra were constructed that approximated those generated previously with mono-chromatic radiation. In both cases, a mutant strain (rad-3) progressively lost its hypersensitivity as shorter wave-lengths were filtered out. In addition, both wild type and radiation-sensitive (rad) mutants were irradiated with several combinations of filtered light sources in the presence and absence of two exogenous photosensitizers (ethidium bromide and bromodeoxyuridine). Treatment with either of the introduced photosensitizers increased photosensitivity to solar UV. Solar UV also induced a fluence-dependent reduction in fertility in wild-type animals. These experiments extend previous data and substantially expand our understanding of the biological responses of C. elegans to solar radiation.