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Many human L1 elements are capable of retrotransposition
D M Sassaman1, B A Dombroski, J V Moran
1Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
Nature Genetics
|May 1, 1997
Summary
Researchers identified active human LINE-1 (L1) elements, finding that eight of thirteen newly isolated elements showed reverse transcriptase activity and three could retrotranspose. Previously known active L1 elements also showed high activity, suggesting 30-60 active L1s exist in the human genome.
Area of Science:
- Molecular Biology
- Genetics
- Genomics
Background:
- LINE-1 (L1) elements are retrotransposons that can move within the human genome.
- Understanding the activity and prevalence of human L1 elements is crucial for studying genome dynamics and evolution.
- Previous research has identified some active L1 elements, but a comprehensive characterization remains incomplete.
Purpose of the Study:
- To identify and characterize novel active full-length human LINE-1 (L1) elements.
- To assess the reverse transcriptase (RT) activity and retrotransposition capability of newly isolated L1 elements.
- To estimate the total number of active L1 elements in the human genome.
Main Methods:
- A selective screening strategy was employed to isolate full-length L1 elements from a human genomic library.
- The reverse transcriptase (RT) activity of isolated L1 elements was measured.
- Retrotransposition ability of L1 elements was tested in HeLa cells.
Main Results:
- Thirteen full-length L1 elements were isolated.
- Eight of the 13 newly isolated L1 elements exhibited RT activity.
- Three of the newly isolated L1 elements demonstrated retrotransposition capability in HeLa cells.
- Previously characterized L1 elements (L1.3 and L1.4) showed high RT activity and retrotransposition frequencies.
- The number of characterized active human L1 elements increased to seven.
- An estimation suggests 30-60 active L1 elements are present in the average diploid human genome.
Conclusions:
- Several novel active human L1 elements have been identified and characterized.
- Active L1 elements, including previously known ones, possess significant RT activity and retrotransposition potential.
- The findings contribute to our understanding of L1 element prevalence and activity in the human genome.
- The estimated number of active L1 elements has implications for genome stability and evolution.