Sensory perception and transduction of UV-B radiation by the ciliate Blepharisma japonicum

A key question to answer studying the biological effects of ultraviolet radiation on planktonic micro-organisms is whether they can perceive UV-B radiation as a sensory signal, likewise they do with visible light. We have faced this problem performing an individual-cell analysis of Blepharisma japonicum photomotile responses to UV-B stimuli. Our results on spectral responsiveness and on the effects of a photoresponse inhibitor indicate that B. japonicum is capable to perceive and transduce UV-B radiation as an environmental sensory stimulus, which it escapes from gathering in shadowed areas. Similar UV-B avoidance motile reactions could serve as a behavioural defence mechanism contributing to avoid harmful overexposure to UV-B.