title: Vitamin D3 in Tilapia mossambica: relevance of photochemical synthesis.
abstract: The capability of fish to synthesize vitamin D on exposure to ultraviolet (UV) light was examined. Purposeful exposure of the freshwater fish Tilapia mossambica (Tilapia) to artificial UV light (300 nm) resulted in a significant increase of vitamin D3 with a concomitant decrease in provitamin D3 [7-dehydrocholesterol (7-DHC)], indicating that provitamin D3 was converted to vitamin D3. However, only 0.13% of the intraperitoneally injected 4-14C cholesterol was recovered in the vitamin D3 and 25-hydroxyvitamin D3 (25-OH-D3) fractions after 15 h of irradiation. Thus, although fish is capable of photosynthesizing vitamin D through constant, prolonged exposure to UV light of appropriate wavelength, the contribution of this mode of synthesis is unlikely to be of any significance in its natural habitat.
authors.affiliation: National Institute of Nutrition, Hyderabad, India.
authors.forename: D S
authors.initials: DS
authors.lastname: Rao
authors.forename: N
authors.initials: N
authors.lastname: Raghuramulu
mesh_terms: D000818:Animals; D002762:Cholecalciferol / Q000096:biosynthesis*; D002784:Cholesterol / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003684:Dehydrocholesterols / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D010777:Photochemistry; D012867:Skin / Q000378:metabolism; D017210:Tilapia / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D003684:Dehydrocholesterols; D002762:Cholecalciferol; D002784:Cholesterol; C016705:7-dehydrocholesterol