Phycoerythrin synthesis is induced by solar UV-B in the cyanobacterium Nostoc

Solar UV-B (280-315 nm) induces the synthesis of phycoerythrin (PE) in a No stoc species isolated from the Andean high altitude lake Yanaqocha. The out door experiments were carried out in a small lake in Erlangen, Germany, usi ng natural conditions. After 2- and 4-h exposure to solar radiation, the im munodetection signal using monoclonal antibodies anti-PE was lower in contr ol cells (exposed to PAR + UV-A) than in cells exposed to total solar radia tion (PAR + UV-A + UV-B). Cells exposed at depths in which no UV-B penetrat ed showed no differences from control cells regarding PE content. When expo sed to monochromatic radiation of 280, 300 or 360 nm, purified PE was photo degraded in a wavelength dependent manner resulting in different polypeptid e fragments carrying chromophore groups. Immunodetection revealed active sy nthesis of PE in parallel to photodamage by solar UV-B indicating that PE i s important for photoadaptation to shorter wavelengths in the cyanobacteriu m Nostoc sp. (C) Elsevier, Paris.