2. The Nature of Transposons Chapter 11 pp 297-309

3. Outline Nature of Transposons Transposons –Prokaryotic –Eukaryotic: Dr. McClintock’s research Retrotransposons vs Retroviruses

4. Transposons Are mobile DNA sometimes referred to as “jumping genes”.

5. Common features associated with transposons 1. Direct repeats 2. Terminal Inverted repeats Common Features Are:

7. Transposable Elements in Bacteria

8. 1. Simple Bacterial Transposon INSERTION SEQUENCE

9. 2. COMPOSITE TRANSPOSON IS + any DNA segment

10. Dr. Barbara McClintock 1902-1992 Nobel Prize, 1983 Physiology or Medicine

11. “I don’t understand a word that she said, but if she says it is so, it must be so!” Alfred Sturtevant

18. “Ds Transposed out”

19. The Ds element often results in chromosomal breakage

20. Drosophilia melanogaster & DNA transposition “The P Element”

21. The P element Codes for Transposase Repressor of transposition

22. Offspring sterile Offspring normal Why the difference? Female P- and male P+ Female P+ and male P- Hybrid dysgenesis Non-hybrid dysgenesis

23. Remember the P element Codes for A Transposase AND A Repressor of transposition

24. Mite Science. 1991 Sep 6;253(5024):1125-8 Possible horizontal transfer of Drosophila genes by the mite Proctolaelaps regalis. Houck MA, Clark JB, Peterson KR, Kidwell MG. Houck MAClark JBPeterson KRKidwell MG D. melanogaster D. willistoni The P element took a ride on a That moved it onto ~50 yrs ago

25. Retrotransposons mRNA DNA

26. Examples of retrotransposons elements Ty Copia Alu Yeast Drosophila Humans

27. General Mechanism Of Retrotransposons Note: retrotransposons are not found in prokaryotes

28. Types of Retrotransposons Ty Copia Yeast Drosophila Humans Viral Non-Viral Alu

29. Non-viral Retrotransposons Humans Non-Viral LINES SINES AluExample:Line 1 and Line 2

30. ALU 300 bp Endonuclease cutting site: site5' AG/CT 3‘ Retrotransposon 1 million in genome Linked to variety of disorders

31. Alu has inserted in NF-1 gene Neurofibromatosis: autosomal dominant Growth of nodules mainly affecting nerves in the skin

32. Viral retrotransposons look a little like retroviruses—but are NOT the same !

33. Now we must compare a Viral RNA with a Viral Retrotransposon

34. VIRAL RNA

36. Infectious process

37. Now a viral retrotransposon

38. Here’s the Copia element of Drosophila Compare to the retrovirus Similar gag and pol sequences

39. Here’s the Ty element, again notice similarities to retroviruses Delta sequences function like LTR’s in viruses

40. Summary Table Viral and non-viral Ty and Copia viral retrotransposons Alu non viral retrotransposons

42. A topic of scientific discussion is what is a “prion”?

44. Blunt cut from donor

45. HUMAN IMMUNODEFICIENCY VIRUS Human Helper T Lymphocyte