| photo- | Phot- Light. Origin: G. Phos (phot-) (05 Mar 2000) |
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| photo-electrotype | An electrotype plate formed in a mold made by photographing on prepared gelatine, etc. Source: Websters Dictionary (01 Mar 1998) |
| photo-engraving | The process of obtaining an etched or engraved plate from the photographic image, to be used in printing; also, a picture produced by such a process. Origin: Photo- + engraving. Source: Websters Dictionary (01 Mar 1998) |
| photo-epinasty | <botany> A disproportionately rapid growth of the upper surface of dorsiventral organs, such as leaves, through the stimulus of exposure to light. See: Photo-, and Epinastic. Source: Websters Dictionary (01 Mar 1998) |
| photo-patch test | A test of contact photosensitization: after application of a patch with the suspected sensitiser for 48 hours to two sites, if there is no reaction one area is exposed to a weak erythema dose of sunlight or ultraviolet light; if positive, a more severe reaction with vesiculation develops at the exposed patch area than the nonexposed skin patch site. (05 Mar 2000) |
| photo cell | A light-detecting electronic device; the device that measures X-ray transmission through a patient for automatic termination of the exposure. (05 Mar 2000) |
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| deoxyribodipyrimidine photo-lyase | <enzyme> An enzyme in yeast that is activated by light, whereupon it can reverse a previous photochemical reaction by cleaving the cyclobutane ring of the thymine dimer. It catalyses the reactivation by light of UV-irradiated DNA and cleaves two carbon-carbon bonds in pyrimidine dimers in DNA. Synonym: dipyrimidine photolyase, photoreactivating enzyme. Chemical name: Deoxyribocyclobutadipyrimidine pyrimidine-lyase Registry number: EC 4.1.99.3 (21 Jun 2000) |