Transposons

Transposons
jumping genes

1. Transposons

2. Outline Discovery Types Mechanism of transposition Role Evolution Gene therapy

3. Junk DNA Selfish DNA Spam DNA Jumping genes Genomic parasite

4. Some transposable elements are introns Not all introns are TE.

5. Transposable elements are DNA sequences that move from one location on the genome to another.

6. Maize / Corn

7. Why are these kernels spotted ?

8. 10

9. 11

10. 12

11. Somatic Excision of Ds from C Fig. 23.9 Sectoring Wild type

12. Ds is derived from Ac by internal deletions Ds is not autonomous, requires Ac to move Ac encodes a protein that promotes movement - Transposase

13. Thanks to transposons

14. genes have fixed location genes can move

15. After 40 long years

16. Types of Transposons Type II Type I

17. Diversity of transposons

18. Mechanism Of DNA Transposons

19. Mechanism Of DNA Transposons

20. How does copy number increase ?

21. How does copy number increase ?

22. How does copy number increase ?

23. Can reach high numbers in the genome because of replicative movement. Retro-Transposons Type I

24. Our genome is NOT only ours ! Our genome contains virus !!!!!!

25. HERV - K

26. LINES & SINES LINES-Long Interspersed Nuclear Elements About 868,000 in human genome 6,500 base pairs long including LTRs Encode reverse transcriptase and integrase Copy-paste mechanism to insert elsewhere SINES-Short Interspersed Nuclear Elements Millions in human genome 100-400 bases long Often contain RNA polymerase III promoters but no genes ALUs- The most common SINE 1,500,000 copies = 11% of human genome 350 base pairs in length Contain an RNA Polymerase III promoter, Alu site Appear to evolve from 7S RNA signal recognition particle

27. LINE

28. LINE

29. LINE

30. LINE

31. SINE needs LINE

32. Sorghum 700 Mb Barley 5,000 Mb Maize 2,500 Mb Oats ~20,000 Mb Wheat 20,000 Mb Rice 450 Mb Variation in cereal genomes - transposons & genome duplications

33. Most TEs are inactive - fossils How do organisms live with TEs?

34. How do organisms live with TEs? Active TEs evolved to insert into safe sites.

35. Alu within the Alu Full Alu sequence ½ Alu sequence ½ Alu sequence

36. Host modulation of TE movement Methylation Heterochromatin formation piRNA How do organisms live with TEs?

37. SINEs – short interspersed nuclear elements (eg Alu) Transposable element (TE) content of human genome Alu repeats: ~300 bp long with AluI restriction site, > 1 million copies in human genome SVA composite retroelement (SINE, VNTR & Alu ) LINEs – long interspersed nuclear elements ( eg L1)

38. Alu family

39. Target primed reverse transcription (TPRT)

40. TEs can provide advantages and can be exploited by an organism like human for his use ! How do organisms live with TEs?

41. Evolution of Placental Mammals

42. Obstacle is xenotransplantation

43. Methods for detecting transposons insertions

44. Transposon tagging