Skip Navigation

American Zoologist 1999 39(3):471-486; doi:10.1093/icb/39.3.471
© 1999 by The Society for Integrative and Comparative Biology
This Article
Right arrow FREE Full Text (PDF) Freely available
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Request Permissions
Google Scholar
Right arrow Articles by WANG, S. Y.
Right arrow Articles by SKINNER, D. M.
Right arrow Search for Related Content
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Toward an Understanding of Satellite DNA Function in Crustacea1

SHIAO Y. WANG2,3, PATRICIA M. BIESIOT2,3 and DOROTHY M. SKINNER
Life Sciences Division, Oak Ridge National Laboratory Oak Ridge, Tennessee 37831 Department of Biophysics, East Tennessee State University Johnson City, Tennessee 37614

Correspondence: 2E-mail: Shiao.Wang{at}usm.edu; Patricia.Biesion{at}usm.edu

A G+C-rich satellite DNA (stDNA) in Gecarcinus lateralis with a repeat unit of 2.1 kbp makes up approximately 3% (16,000 copies/nucleus) of the land crab genome. We used sequences from conserved domains of the repeat unit to construct probes for exploring the possibility of the repeat units being transcribed into RNA, their distribution in genomic DNA, and their methylation status. A transcription product hybridizing with TRU-EXON, a region of the satellite bordered by possible exon splice junctions, was found 3'END, a 368 bp fragment at the 3'-end of the satellite, were also found in several other crustaceans. Transcription products that hybridized to AMPL-3, a probe from an amplified segment of the satellite, were not found in land crabs but were found in lobsters. In land crabs, several poly(A)+RNA transcripts that hybridized to 3'END were specific for DNA strand, tissue, and intermolt stage. The diversity of transcripts suggests that transcription of the satellite is related to the organization of the repeated DNA in the crab genome, and that some satellite domains may be transcribed because of their position relative to functional genes. This observation is supported by the additional observation that the satellite is differentially methylated. Repeats organized in tandem in the satellite are methylated, whereas those interspersed in main component DNA (mcDNA) are not. Because DNA methylation is a means of silencing transcription, our results suggest that satellite sequences that are transcribed are those interpersed in mcDNA. DNA methylation patterns are also tissue-specific; of the seven tissues examined (gill, claw muscle, body muscle, limb buds, midgut gland, testis, and ovary), gill stDNA is the least methylated. The observed differences inmethylation levels are not attributable to stage in the intermolt cycle or to sex. This is the first report indicating the presence of 5-methylcytosine (m5C) in a crustacean.


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer:
Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.