Isolation and characterization of ultraviolet light-sensitive mutants of the blue-green alga Anacystis nidulans.

Three independently isolated ultraviolet light-sensitive (uvs) mutants of Anacystis nidulans were characterized. Strain uvs-1 was most sensitive to UV in the absence of photoreactivation. Pretreatment with caffeine suppressed the dark-survival curve of strain uvs-1, indicating the presence of excision enzymes involved in dark repair. Under "black" and "white" illumination, strain uvs-1 displays photoreactivation properties nearly comparable to wild-type culture. Mutants uvs-35 and uvs-88 appeared to have partial photorecovery capacities. Upon pretreatment with chloramphenicol, photoreactivation properties of strains uvs-1 and uvs-88 were not evident although the partial photoreactivation characteristics of strain uvs-35 remained the same. Data indicate that strains uvs-1, uvs-35, and uvs-88 are probably genetically distinct UV-sensitive mutants.