Convenient scoring of deoxyglucose resistance in Neurospora

V. C. Pollard and D. D. Perkins, Department of Biological Sciences, Stanford University, Stanford CA 94305-5020

Allen et al. (1989 J. Bacteriol. 171:53-58 and personal communication) have described scoring dgr mutants on media prepared by adding filter-sterilized fructose and deoxyglucose solutions to medium that has already been autoclaved. This is inconvenient if tests are to be made on tubed slants, as we prefer to do.

We are interested in dgr-1 because it is the closest marker to the nucleolus organizer. In scoring dgr-1, we have found it unnecessary to filter-sterilize the sugar. Autoclaving in the medium appears to have no adverse effect. 0.3% 2-deoxyglucose, 0.1% fructose, and 1.5% agar are added to Vogel's minimal salts and dispensed into 10 x 75 tubes, which are then plugged, autoclaved, and slanted. Tests on the slants are perfectly clear, with resistant strains fully grown and sensitives clearly negative. Growth is considerably faster on agar medium than on liquid, with tests on agar readable after two days at 34 deg. or three or four days at 25 deg..