Worm Breeder's Gazette 9(2): 32
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.
224 cosmid clones, representing about one tenth of the Caenorhabditis strain CB1392 H nuc001 (e1392) X ), were screened for the presence of repetitive sequences using as probe total nick-translated genomic DNA. Eighteen clones showed-up as positive in this screening, among these, two were proved to cross- hybridize to the known transposable element Tc1, another represented a ribosomal DNA clone. We have begun to analyze different features of the remaining fifteen clones: none of them shows homology with the MSP gene family and only one, cos repM7, contains a sequence homologous, at low stringency, to the col-1 gene but not in the major repetitive band; none of the clones shows homology to pCe2, pCe5, pCe17 and pCe1006, repetitive DNA clones from S. W. Emmons Laboratory. Two of our clones belong to the same repetitive family we have named B1. The B1 together with other three families, namely C9,F10, and S5 were tested for restriction-sites polymorphisms in genomic DNAs from independently isolated C. elegans wild type strains. They all show polymorphisms for each enzyme used, nevertheless no polymorphisms were detected among laboratory strains derived from N2. They all prove to be abundant in all the strains (more than 50 copies per genome for B1, C9 and the S5, less in the case of F10 that however is of unusual size: more than 20kb). Unlike Tc1, our repetitive families code for abundant transcripts.