Using a large consortium of undergraduate students in an organized program at the University of California, Los Angeles (UCLA), we have undertaken a functional genomic screen in the Drosophila eye. In addition to the educational value of discovery-based learning, this article presents the first comprehensive genomewide analysis of essential genes involved in eye development. The data reveal the surprising result that the X chromosome has almost twice the frequency of essential genes involved in eye development as that found on the autosomes.

ThiobaciUus thiooxidans cells oxidized elemental sulfur to sulfite, with 1 mol of 02 consumption per mol of sulfur oxidized to sulfite, when the oxidation of sulfite was inhibited with 2-n-heptyl-4-hydroxyquinoline N-oxide.

Several soluble electron transfer proteins were isolated and characterized from the marine purple-sulfur bacterium Chromatium purpuratum. The C. purpuratum flavocytochrome c is similar in molecular mass (68 kDa) and isoelectric point (6.5) to flavocytochromes isolated from other phototrophs. Redox titrations of the flavocytochrome c hemes show two components with midpoint potential values of +15 and -120 mV, behavior similar to that observed with the flavocytochrome isolated from the thermophilic Chromatium tepidum. Moreover, N-terminal amino acid sequence analysis of both the flavin and the cytochrome subunit indicates substantial homology to the primary structure of the flavocytochrome c of Chromatium vinosum. In contrast, the C. purpuratum high-potential iron-sulfur protein (HiPIP) differs from those isolated from other photosynthetic bacteria in its relatively high midpoint potential (+390 mV) and the possibility that it exists as a dimer in solution. Two low molecular mass c-type cytochromes were also characterized. One appears to be a high-potential (+310 mV) c8-type cytochrome. Amino acid sequencing suggests that the second cytochrome may be a homologue of the low-potential cytochrome c-551, previously described in two species of Ectothiorhodospirillaceae.

Crystals of a carotenoid protein from the cyanobacterium Arthrospira maxima have been grown in space group C2 with unit-cell dimensions a = 219.6, b = 40.3, c --75.5 A and fl=95.5 °. The crystals diffract X-rays to 2.3 A resolution and display unusual optical properties in polarized light that suggest that all of the carotenoid molecules in the crystals are oriented similarly. A slight increase in the concentration of a crystallization additive in the mother liquor induces macroscopic twinning, which is also visible when the crystals are illuminated with polarized light.