title: Poly-G/poly-C tracts in the genomes of Caenorhabditis.
abstract: BACKGROUND
  In the genome of Caenorhabditis elegans, homopolymeric poly-G/poly-C tracts (G/C tracts) exist at high frequency and are maintained by the activity of the DOG-1 protein. The frequency and distribution of G/C tracts in the genomes of C. elegans and the related nematode, C. briggsae were analyzed to investigate possible biological roles for G/C tracts.
  
  
  RESULTS
  In C. elegans, G/C tracts are distributed along every chromosome in a non-random pattern. Most G/C tracts are within introns or are close to genes. Analysis of SAGE data showed that G/C tracts correlate with the levels of regional gene expression in C. elegans. G/C tracts are over-represented and dispersed across all chromosomes in another Caenorhabditis species, C. briggsae. However, the positions and distribution of G/C tracts in C. briggsae differ from those in C. elegans. Furthermore, the C. briggsae dog-1 ortholog CBG19723 can rescue the mutator phenotype of C. elegans dog-1 mutants.
  
  
  CONCLUSIONS
  The abundance and genomic distribution of G/C tracts in C. elegans, the effect of G/C tracts on regional transcription levels, and the lack of positional conservation of G/C tracts in C. briggsae suggest a role for G/C tracts in chromatin structure but not in the transcriptional regulation of specific genes.
authors.affiliation: Department of Medical Genetics, University of British Columbia, Life Sciences Centre, Room 1364 - 2350 Health Sciences Mall, Vancouver, BC, V6T1Z3, Canada. yzhaocn@interchange.ubc.ca
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhao
authors.forename: Nigel J
authors.initials: NJ
authors.lastname: O'Neil
authors.forename: Ann M
authors.initials: AM
authors.lastname: Rose
mesh_terms: D000818:Animals; D002107:Caenorhabditis / Q000235:genetics*; D017173:Caenorhabditis elegans / Q000235:genetics; D029742:Caenorhabditis elegans Proteins / Q000235:genetics; D002875:Chromosomes / Q000235:genetics; D004265:DNA Helicases / Q000235:genetics; D017238:Genes, Helminth / Q000235:genetics; D049751:Genome, Helminth; D007438:Introns / Q000235:genetics; D011066:Poly C / Q000235:genetics*; D011068:Poly G / Q000235:genetics*
chemical_list: D029742:Caenorhabditis elegans Proteins; D011068:Poly G; D011066:Poly C; D004265:DNA Helicases; C464789:Dog-1 protein, C elegans