Transposable elements

Paul Kalitsis

History

• Barbara McClintock 1940s

History

• Genetic loci could change position• Theory of mobile or controlling elements• Challenged the concept of a static

genome• Stopped publishing from 1953• Awarded the Nobel Prize in 1983

History cont’

• Identified in bacteria and yeast in the late 60s and early 70s

Junk or Selfish DNA

• No obvious role apart from self propagation

• Variations in genome size

Genome size

• C-value paradox• Maize 2,500 Mb• Arabidopsis 150 Mb• Lilium 35,000 Mb

Types of TEs

• DNA transposons• Retrotransposons• Endogenous retroviruses

Biemont & Vieira 2006 Nature

Lander 2001 Nature

genome.ucsc.edu

Function

• Development• Imprinting• Tissue differentiation• Evolution

Lilium henryiDavid SmythSchool of Biological SciencesMonash University

Dispersed repeat in L. henryi

• 3.5 x 1010 bp• Distributed throughout the genome• Retrotransposon 9.35 kb

gag RT RH INT

Selfish DNA

• Doolittle & Sapienza• Orgel & Crick (1980 Nature)

Genome defense

• Recombination and deletion• RNAi pathway

Epigenetic control

• Changes in DNA and/or protein• Gene expression• X-inactivation

Environment

• Stress• Nutrition• Chemicals

Morgan et. al. 1999 Waterland and Jirtle 2003

IAP

Avy

IAP

AvyMe Me

Biemont & Vieira 2006 Nature

Human disease

• 0.5 – 1%• Cancer• Haemophilia• Muscular dystrophy

Applications

• Mutagenesis• Gene delivery and therapy

Co-option

• Immune system• Placental development• Telomere maintenance• Centromere• Epilepsy• Early development

Acknowledgments

• Chromosome and Chromatin Group• Australian Research Council