Differences in non-LTR retrotransposons within C. elegans and C. briggsae genomes

Mika Zagrobelny*, Daniel C. Jeffares, Peter Arctander

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


An exhaustive study of the Sam/Frodo family of non-LTR retrotransposons in the Caenorhabditis elegans and Caenorhabditis briggsae genomes demonstrated that C. briggsae contains 60 Sam/Frodo elements including a new subfamily designated Merry, while at least 1000 elements are present in C. elegans. In contrast to C. elegans, C. briggsae does not contain any other non-LTR retrotransposons. The Sam/Frodo/Merry sequences in C. briggsae are shorter and less complete than the Sam/Frodo sequences in C. elegans probably because they all lack a functional first open reading frame (ORF1) and because the genome only encodes one functional reverse transcriptase gene of a non-LTR retrotransposon. Evidence of purifying selection for a functional reverse transcriptase sequence in master/leader elements was found in both nematodes in spite of low copy numbers in C. briggsae. Sam elements in C. elegans are the most abundant Sam/Frodo/Merry family members. They contain the only functional ORF1 copies and, unlike Frodo and Merry members, have a higher GC content than the genomic regions in which they reside. This may indicate a higher transcription rate within this subfamily.

Original languageEnglish
Pages (from-to)61-66
Number of pages6
Issue number1-2
Publication statusPublished - 14 Apr 2004


  • CR1
  • Frodo
  • Merry
  • Non-Long Terminal Repeat
  • Non-LTR
  • Open reading frame
  • ORF
  • Sam

Cite this