The Insertional History of an Active Family of L1 Retrotransposons in Humans (original) (raw)
- Stéphane Boissinot1,3,
- Ali Entezam1,
- Lynn Young2,
- Peter J. Munson2, and
- Anthony V. Furano1,4
- 1 Section on Genomic Structure and Function, Laboratory of Molecular and Cellular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
- 2 Analytical Biostatistics Section, Mathematical and Statistical Computing Laboratory, Division of Computational Biosciences, Center for Information Technology, National Institutes of Health, Bethesda, Maryland 20892, USA
Abstract
As humans contain a currently active L1 (LINE-1) non-LTR retrotransposon family (Ta-1), the human genome database likely provides only a partial picture of Ta-1-generated diversity. We used a non-biased method to clone Ta-1 retrotransposon-containing loci from representatives of four ethnic populations. We obtained 277 distinct Ta-1 loci and identified an additional 67 loci in the human genome database. This collection represents ∼90% of the Ta-1 population in the individuals examined and is thus more representative of the insertional history of Ta-1 than the human genome database, which lacked ∼40% of our cloned Ta-1 elements. As both polymorphic and fixed Ta-1 elements are as abundant in the GC-poor genomic regions as in ancestral L1 elements, the enrichment of L1 elements in GC-poor areas is likely due to insertional bias rather than selection. Although the chromosomal distribution of Ta-1 inserts is generally a function of chromosomal length and gene density, chromosome 4 significantly deviates from this pattern and has been much more hospitable to Ta-1 insertions than any other chromosome. Also, the intra-chromosomal distribution of Ta-1 elements is not uniform. Ta-1 elements tend to cluster, and the maximal gaps between Ta-1 inserts are larger than would be expected from a model of uniform random insertion.
Footnotes
[Supplemental material is available online at www.genome.org.\]
Article and publication are at http://www.genome.org/cgi/doi/10.1101/gr.2326704\. Article published online before print in June 2004.
↵3 Present address: Department of Biology, Queens College, City University of New York, Flushing, New York 11367, USA.
↵4 Corresponding author. E-MAIL avf{at}helix.nih.gov; FAX (301) 402-0053.
- Accepted March 17, 2004.
- Received December 30, 2003.
Cold Spring Harbor Laboratory Press