The Dynamic Genome Transposons. Transposable element (transposon) A sequence of DNA that is...
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Transcript of The Dynamic Genome Transposons. Transposable element (transposon) A sequence of DNA that is...
The Dynamic Genome
Transposons
Transposable element (transposon)A sequence of DNA that is competent to move from place to place within a genome
Ds Transposition
weedtowonder.org/jumpingGenes.html
Retrotransposon Content (million BP)
Transposon Caught in the Act (Burst)
• Most TEs are inactive molecular “fossils”.
• Active TEs evolved to insert into “safe-havens.”
• Host sequesters Tes and regulates their movement (RNAi-based mechanism).
• TEs can provide advantages. (A means to rapidly reorganize the genome in response to stress.)
How do organisms live with TEs?
MITE (Miniature -Inverted repeat TE)
Deletion-derivative of Ping: requires Ping transposase
Ping/mPing
OVER 1000 mPing copies
Japonica strains
mP
ing
cop
y n
um
ber
Naito et al PNAS (2006))
mPing
Over 1000 copies of mPing in 4 related strains….
Takatoshi Tanisaka lab (Kyoto University)
mPing copy number in O.japonica
Genomic Distribution of mPing
0
2
4
6
8
10
12
5'UTR exon intron 3'UTR
(%)
shared(n=926)
unshared(n=736)
expect.
UTR Exon UTR
Genic Distribution of mPing
Os02g0135500 (-41)
0
0.5
1
1.5
2
2.5
control cold salt dry
NBEG4 (mPing+)A123 (mPing+)A157
mPing Alters Gene Expression
Nipponbare EG4
mPing Confers Salt Tolerance
Naito et al, Nature, 2009
• Massive amplification largely benign• Subtle impact on the expression of many genes• Produces stress-inducible networks (cold, salt, others?)• Generates dominant alleles
Rapid mPing amplification (burst)
Transposons and Zapotec Oral Tradition
Virigina Walbot
• Fields of those who who steal Zapalote Chico maize will be poisened
• Transcription of intact Mutator transposase repressed by homozygous inhibitor
• Outbreeding releases repression• Mutator activation results in • sterility (hybrid dysgenesis)• Analogous to P elements in fruit flies
• (relatively) simple
• incredibly abundant
• evolve rapidly
• promote rapid genome evolution
• largely ignored (discovery)
TEs for Student Research Projects