Photomovement, Pigmentation and Uv‐b Sensitivity in Planaria

Abstract

Four differently pigmented species of planarians were examined for UV-B (i 7 320 280nm) tolerance and ability to detect and avoid CV-B-exposed areas. I t was found that lighter-pigmented species are more UV sensitive and that movement out of the UV-B is directly related to UV sensitivity. Three species showed positioning preference corresponding to their pigmentation; the darker the speclcs, the less avoidance of UV-B. The white (unpigmented) species showed exceptional and very sensitive behavior. IhTRODUCTlOh

RESPONSES OF THE PLANARIAN Dugesia dorotocephala TO ULTRAVIOLET RADIATION OR PHOTOSENSITIZED TREATMENTS

“…The shape of this survival curve (i.e. the value of Do relative to Dq) is similar to that published for UV-B irradiated D. dorotocephala (Barcelo, 1980). The finding that increasing UV exposures led to lysis at increasingly shorter times may be viewed as U V exposure leading to life shortening (Bond et al, 1965).…”

“…The lethal effects of one photosensitizing compound, eosin yellow, on Dugesia dorotocephala has been reported (Hinrichs, 1924). Other studies have shown that different species of planarians, including D. dorotocephala, are sensitive to very high exposures of germicidal ultraviolet radiation (Merker and Gilbert, 1932;Hinrichs, 1924) and to near-ultraviolet radiation (Spencer and Klein, 1979;Barcelo, 1980). Several species of planarian have been used by Lange (1968aLange ( , 1968b to study the cellular basis of x-radiation lethality.…”