TELOMERIC REPEATS (TTAGGC)(N) ARE SUFFICIENT FOR CHROMOSOME CAPPING FUNCTION IN CAENORHABDITIS-ELEGANS

Telomeres are specialized structures located at the ends of linear euk aryotic chromosomes that ensure their complete replication and protect them from fusion and degradation, We report here the characterization of the telomeres of the nematode Caenorhabditis elegans, We show that the chromosomes terminate in 4-9 kb of tandem repeats of the sequence TTAGGC, Furthermore, we have isolated clones corresponding to 11 of t he 12 C. elegans telomeres, Their subtelomeric sequences are all diffe rent from each other, demonstrating that the terminal TTAGGC repeats a re sufficient for general chromosomal capping functions, Finally, we d emonstrate that the me8 meiotic mutant, which is defective in X chromo some crossing over and segregation, bears a terminal deficiency that w as healed by the addition of telomeric repeats, presumably by the acti vity of a telomerase enzyme. The 11 cloned telomeres represent an impo rtant advance for the completion of the physical map and for the deter mination of the entire sequence of the C. elegans genome.