Worm Breeder's Gazette 5(1): 35
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
We have isolated C. elegans DNA sequences cloned in phage vectors to use as probes for messenger RNA's in the worm. A clone library of C. elegans DNA fragments generated by complete digestion with endonuclease EcoRI has been constructed with the phage vehicle Charon 3. This phage can accept worm DNA fragments up to 12.3 kilobases in length. Recombinant phage carrying worm genes are detected by hybridization to cDNA copied from various RNA preparations. RNA populations tested so far are from adult worms, early embryos (less than 30-cell) and late embryos (lima bean to hatching). All are enriched for poly-A-containing RNA's by chromatography on oligo-dT- cellulose or poly-U-sepharose. Over one hundred clones containing transcribed sequences have been isolated and retested against all three cDNA sets. The responses of the cloned DNA's fall into the following categories: [See Figure 1] The distribution of cloned DNA's among these categories may be biased for several reasons. First, only adult and early embryo cDNA's were used to select these clones from the library; late embryo- specific genes might have been missed. Second, negative results do not indicate complete absence of the transcript, but only a concentration too low to give a significant signal in filter hybridization. The majority of the cloned sequences are present in the RNA of all stages tested, but some of the transcripts clearly vary in abundance during development. Because we isolated over 100 cloned genes by screening at most one sixth of the sequences of the C. elegans genome, we estimate that these clones are representative of the 600-1000 most abundant transcripts in adult worms or early embryos. Although some repeated genes may be duplicated in the collection, the ribosomal RNA and collagen genes are not included. However, class (1) includes four clones that hybridize to sea urchin histone genes.