EFFECT OF UV-B RADIATION ON CILIATED PROTOZOA - Environmental UV Radiation: Impact on Ecosystems and Human Health and Predictive Models - page 226

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Figure 1. Action spectra of UV-induced photokilling of Tetrahymena as a function of different
postirradiation treatments. Squares: no treatment; circles: 20 min photoreactivation; triangles:
suspension medium containing 0.02% caffeine. The dotted line represents an “average DNA” action
spectrum (from ref. 11).

Probably, but this is not certain yet, these dark reactions are correlated with the
repair mechanisms, and, in particular the photo-repair mechanisms, which operate only
in the presence of visible light 12 . These findings suggest that UV can affect several
different physiological functions; this may happen in a not very specific way, since
radiation can affect both proteins and nucleic acids; some researchers, however, have
tried to investigate the existence of specific UV receptors in ciliates 11,13-16 . In particular,
they tried to characterize the UV sensitivity of some organisms (included little
crustaceans), in order to establish if there is a photoreceptor absorbing in the UV region.