Characterization and Developmental Expression of a Drosophila ras Oncogene

Abstract

We cloned a Drosophila melanogaster ras gene (Dmras64B) on the basis of its homology to the ras oncogen from Harvey murine sarcoma virus. This gene mapped at chromosomal position 64B on the left arm of the third chromosome. Sequencing of Dmras64B revealed extensive amino acid homology with the proteins encoded by the human and Saccharomyces cerevisiae ras genes. The coding region of the Drosophila gene is interrupted by two introns located in different positions with respect to its human counterpart. Dmras64B encodes three different RNAs (1.6, 2.1, and 2.6 kilobases long) that are constantly expressed throughout the development of the fly.

Drosophila CtBP: a Hairy-interacting protein required for embryonic segmentation and Hairy-mediated transcriptional repression

“…In addition, a 3.5 kb transcript is detected predominantly in adult females and 0–24 h embryos. ras was used as a loading control (Mozer et al ., 1985). The relative stages and developmental times are listed for each lane.…”

“…Oligo(dT)‐selected mRNA was prepared from 0–4 h embryos as described previously (Mozer et al ., 1985). Random‐primed cDNA was generated using the Timesaver cDNA synthesis kit (Pharmacia) then ligated to linkers containing both Not I (internal) and Bam HI (external) sites.…”

“…Developmentally staged RNAs were prepared as described previously (Mozer et al ., 1985). Northern production and hybridization were as described (Mozer et al ., 1985), using 5 μg of poly(A) + ‐selected mRNA per lane and Magnagraph membrane (Micro Separations Inc.). Dras is expressed ubiquitously during development and was used as a loading control (Mozer et al ., 1985).…”

The Drosophila Suppressor of Sable Gene Encodes a Polypeptide with Regions Similar to Those of RNA-Binding Proteins

“…The presence of a single 5-kb message is consistent with the identical splicing pattern observed in all cDNAs. As a loading control, an identically prepared filter was probed with the Drosophila ras gene (bottom panel), because ras is expressed at nearly constant levels throughout the life cycle (27). Examination of the ras panel indicates that the amounts of poly(A)+ RNA loaded varied somewhat from stage to stage.…”

“…Northern (RNA) blots were run with 10 ptg of poly(A)+ RNA per lane. The Drosophila ras gene, which is expressed nearly constantly throughout the life cycle (27), was used as a loading standard. Then an identical Northern blot was run and probed with a probe from within su(s) that hybridized only with the su(s) message.…”