Mutations at the flightless-I locus (flit) of Drosophila melanogaster cause flightiessness or, when severe, incomplete ceilularization during early embryogenesis, with subsequent abnormalities in mesoderm invagination and in gastrulation. After chromosome walking, deficiency mapping, and transgenic analysis, we have isolated and characterized Oightless-I cDNAs, enabling prediction of the complete amino acid sequence of the 1256-residue protein. Data base searches revealed a homologous gene in Caenorhabditis ekgans, and we have isolated and characterized corresponding cDNAs. By using the polymerase chain reaction with nested sets of degenerate oligonucleotide primers based on conserved regions of the C. elegans and D. melanogaster proteins, we have doned a homologous human cDNA. The predicted C. ekgans and human proteins are, respectively, 49% and 58% identical to the D. melanogaster protein. The predicted proteins have signifilcant sequence similarity to the actin-binding protein gelsolin and related proteins and, in addition, have an N-terminal domain consisting of a repetitive amphipathic leucine-rich motif. This repeat is found in D. melanogaster, Saccharomyces cerevisiae, and mammalian proteins known to be involved in cell adhesion and in binding to other proteins. The structure of the maternally expressed flightless-I protein suggests that it may play a key role in embryonic cellularization by interacting with both the cytoskeleton and other cellular components. The presence of a highly conserved homologue in nematodes, flies, and humans is indicative of a fundamental role for this protein in many metazoans.

Certain gene mutations in Drosophila melanogaster cause sluggish motor activity. We have localized the

The narrow-leafed lupin possesses valuable traits for environment-friendly agriculture and for the production of unconventional agricultural products. Despite various genetic and environmental studies, the breeding of improved cultivars has been slow due to the limited knowledge of its genomic structure. Further advances in genomics require, among other things, the availability of a genomic DNA library with large inserts. We report here on the construction of the first DNA library cloned in a BAC (bacterial artificial chromosome) vector from diploid Lupinus angustifolius L. cv. Sonet. The high molecular weight DNA used for its preparation was isolated from interphase nuclei that were purified by flow cytometry. The library comprises 55,296 clones and is ordered in 144×384-well microtitre plates. With an average insert size of 100 kb, the library represents six haploid genome equivalents. Thanks to the purification of the nuclei by flow cytometry, contamination with chloroplast DNA and mitochondrial DNA was negligible. The availability of a BAC library opens avenues for the development of a physical contig map and positional gene cloning, as well as for the analysis of the plant’s genome structure and evolution.