The role of ultraviolet-adaptation of a marine diatom in photoenhanced toxicity of acridine.
Cultures of the marine diatom Phaeodactylum tricornutum were grown under laboratory light with a different fraction of ultraviolet radiation (UV) to study the potential role of photoadaptation in determining the sensitivity to photoenhanced toxicity of acridine. In short-term experiments, a higher acridine concentration was needed to inhibit the photosynthetic electron flux, monitored with chlorophyll a fluorescence, in algae exposed to fluorescent light (low UV) than to mercury light (high UV), consistent with the expected role of UV. The two types of light in long-term exposures led to changes in the pigment composition and photosystem I (PS I) to photosystem II (PS II) stoichiometry to optimize the utilization of fluorescent and mercury light. Despite the adaptation of the photosynthetic apparatus to a small fraction of UV, long-term exposure to mercury light did show a constant sensitivity of the photosynthetic efficiency of P. tricornutum to the phototoxic acridine. It is concluded that the prime receptor of photoenhanced toxicity may be unrelated to the photosynthetic machinery.
Wiegman
Saskia
S
Department of Aquatic Ecology and Ecotoxicology, Faculty of Science, Universiteit van Amsterdam, Kruislaan 320, 1098 SM Amsterdam, The Netherlands. wiegman@science.uva.nl
Barranguet
Christiane
C
Spijkerman
Elly
E
Kraak
Michiel Harm Steven
MH
Admiraal
Wim
W
D000166:Acridines / Q000633:toxicity*; D002734:Chlorophyll / Q000032:analysis; D000077194:Chlorophyll A; D017377:Diatoms / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects*; D004305:Dose-Response Relationship, Drug; D010788:Photosynthesis / Q000502:physiology / Q000528:radiation effects; D013997:Time Factors; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D000166:Acridines; D014874:Water Pollutants, Chemical; D002734:Chlorophyll; D000077194:Chlorophyll A