The saturation values for ribosomal RNA hybridization have been determined for DNA from diploid and polytene tissues of Drosophila melanogaster. These values have been measured in XO and XX larvae which have, respectively, one and two nucleolus organizers in the diploid chromosome set. The results show that (1) in diploid cells the ribosomal (r)DNA is present in amounts proportional to the numb...

Creating a good schedule for a large conference such as CHI requires taking into account the preferences and constraints of organizers, authors, and attendees. Traditionally, the onus of planning is placed entirely on the organizers and involves only a few individuals. Cobi presents an alternative approach to conference scheduling that engages the entire community to take active roles in the pl...

Rex-induced mitotic recombination was used to determine whether nucleolus organizers can pair in both inverted and noninverted orientations. Two target chromosomes, each duplicated for the rDNA region, were exposed to maternal Rex activity. Recombination in one orientation should yield deletion of the material between the two nucleolus organizers, recombination in the other orientation should y...