title: Identification of singlet oxygen photosensitizes in lambs drinking water in an alveld risk area in West Norway.
abstract: Alveld is a hepatogenous photosensitivity disorder in lambs. Although alveld has been known in Norway for more than 100years, there are still questions related to the cause of the disease. Phytoporphyrin has long been incriminated as the photosensitizer in hepatogenous photosensitivity diseases but previous findings suggest that the photosensitizing mechanism in alveld is more complex, possibly involving other co-factors. The current work investigates the presence of non-hepatogenous photosensitizers originating in lamb's drinking water from various sources. In addition samples of two of the predominent cyanobacteria found in a representative biofilm (i.e. aggregates of microbes) were identified and isolated in axenic (i.e. pure) cultures. Information from the absorption-, fluorescence emission-, and -excitation spectra and the action spectrum for the formation of singlet oxygen was combined in order to identify the chromophores responsible for the formation of singlet oxygen, e.g. phycocyanins from the cyanobacteria. The highest level of singlet oxygen formation was detected in lotic (i.e. flowing) water in the period consistent with the outbreak of the alveld disease in the area. Meteorological data indicate a warm and wet May with a high radiation exposure leading up to a colder and wet June with an even higher solar irradiance. The seasonal variation in the amount of photosensitizers in lamb's drinking water combined meteorological data can be important to predict the outbreak of alveld.
authors: School of Pharmacy, University of Oslo, P.O. Box 1068, Blindern, 0316 Oslo, Norway. h.h.tonnesen@farmasi.uio.no
authors: Hanne Hjorth
authors: HH
authors: Tønnesen
authors: Ivar
authors: I
authors: Mysterud
authors: Jan
authors: J
authors: Karlsen
authors: Olav M
authors: OM
authors: Skulberg
authors: Carl M M
authors: CM
authors: Laane
authors: Trond
authors: T
authors: Schumacher
mesh_terms: D000818:Animals; D018441:Biofilms; D000458:Cyanobacteria / Q000302:isolation & purification; D060766:Drinking Water / Q000032:analysis* / Q000737:chemistry / Q000382:microbiology*; D005453:Fluorescence; D008685:Meteorological Concepts; D009664:Norway; D017319:Photosensitizing Agents / Q000032:analysis* / Q000633:toxicity; D061005:Ponds; D012621:Seasons; D012756:Sheep; D012757:Sheep Diseases / Q000209:etiology*; D034561:Sheep, Domestic; D026082:Singlet Oxygen / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D060766:Drinking Water; D017319:Photosensitizing Agents; D026082:Singlet Oxygen