Worm Breeder's Gazette 13(2): 78 (February 1, 1994)

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.

CLONING OF THE RIBOSOMAL PROTEIN S19 IN CAENORHABDITIS ELEGANS.

Vincent Bernard, Adrian Etter, Heinz Tobler, Fritz MŸller, Institute of Zoology, University of Fribourg, 1700 Fribourg (Switzerland).

The nematode Ascaris lumbricoides undergoes chromatin diminution which causes a loss of about 25% of the total genomic DNA from all somatic cells. We have identified a ribosomal protein (rp) gene (coding for ALEP1 = Ascaris lumbricoides eliminated protein 1) which is located within the germ-line specific material. ALEP1 shows strong homologies with the eukaryotic ribosomal protein S19 family ( rpS19 ).2D-gel electrophoresis on germ-line and somatic purified ribosome fractions shows that the ALEP1 protein ( rpS19 )is present only in the germ-line ribosomes. In the rat, rpS19 has been localized at the tip of the small ribosomal subunit.

What is the function of rpS19 ?Since Ascaris is not suitable for genetic analyses, we have isolated rpS19 from the nematode Caenorhabditis elegans. We used RT-PCR with degenerate oligonucleotides to amplify an 81 nucleotide long fragment. The Barstead cDNA library was screened with this fragment and positive clones were isolated and sequenced.

The C. elegans rpS19 cDNA shows only 65% homology at the nucleic acid level. The transcript is trans-spliced with the splice leader SL1 .The deduced amino acid sequence predicts a protein of 150 amino acids with a molecular weight of 17 Kd. The C. elegans rpS19 protein shows perfect homology with other eukaryotic rpS19 proteins in the conserved regions. Overall, the R pS19 protein from C. elegans has 80% homology with Ascaris ALEPl. R pS19 is located on the C. elegans chromosome IV. Experiments are in progress to clone the C. elegans R pS19 gene. The identification of a rpS19 mutant in C. elegans might indicate its function.