NfCR1, the first non-LTR retrotransposon characterized in the Australian lungfish genome, Neoceratodus forsteri, shows similarities to CR1-like elements
✍ Scribed by Nickolche Sirijovski; Catherine Woolnough; Jennifer Rock; Jean M. P. Joss
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 172 KB
- Volume
- 304B
- Category
- Article
- ISSN
- 1552-5007
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✦ Synopsis
Abstract
The genomes of lungfish, together with those of some urodele amphibians, are the largest of all vertebrate genomes. It has been assumed that the bulk of the DNA making up these large genomes has been derived from repeat elements, like the noncoding DNA of those genomes that have been sequenced (e.g., human). In an attempt to characterize repeat sequences in the lungfish genome, we have isolated, by restriction enzyme digestion of genomic DNA, sequences of a repeat element in Neoceratodus forsteri, the most primitive of the living lungfishes. The fragments sequenced from the __Eco__RI and __Bgl__II digests were used to perform genome walking PCR in order to obtain the full sequence of the repeat element. This element shares homology with the non‐LTR (LINE) element, Chicken Repeat 1 (CR1), described for several vertebrates and some invertebrates; we have called it N. forsteri CR1 (__Nf__CR1). __Nf__CR1 shares all the domains of other CR1 elements but it also has several unique features that suggest it may no longer be active in the lungfish genome. It occurs in both full‐length and 5′‐truncated versions and in its present “inactive” form represents ∼0.05% of the lungfish genome. J. Exp. Zool. (Mol. Dev. Evol.) 304B:1–10, 2005. © 2005 Wiley‐Liss, Inc.