Biological Recombination

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Biological Recombination

• In genomes, in genes, in proteins

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Preface Fu et al 02

• Transposon? Ac and Ds?
• Retrotransposon?
• Genetic length vs. physical length?
• Recombination higher among genes?

?
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What Ill Cover

• Reasons and mechanisms
• Rates and sites
• Within-protein

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Why recombine?

• Cui bono?

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Kondrashovs Theory of Sex
X
X
X

X
Kondrashov, A. S., Nature 336, 435-441 (1988).
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DSB model
See Szostak et al, Cell 33, 25-33 (1983).
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DSB model
Limited crossover
Full crossover
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Transposons cut and paste
Davies et al, Science 289 (2000)
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Retrotransposons copy and paste
Yeast Ty element, 6 kb
gag
prot
DR 334
DR 334
int
rt
cDNA
mRNA
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Measuring recombination

• 1911 Alfred Sturtevant invents the map unit
• A story every graduate student
• should remember.

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Where does recombination occur?
Thuriaux, P., Nature 268, 460-462 (1977).
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Rates in gene-rich regions
0.25 cM, 11.6 kb
bz
Ac6058
0.24 cM 6.7 kb
Ac6087
Ac2094
Ac6067
0.32 cM 6.5 kb
0.06 cM, 108 kb
100kb transposon nest
Fu et al, PNAS 992, 1082-1087 (2002)
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Variability of Recomb. Rates
McKim, K., Ann. Rev. Gen. 36, 205-32 (2002).
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Recombination inside genes

• Alternative splicing
• Mobile introns
• And a gene that will blow your mind.

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Alternative splicing
Roberts et al, Curr. Op. Chem. Bio. 6, 375-383
(2002).
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Intron mobility

• Some introns home
• Introns are gained and lost constantly
• Introns define exons
• Are exons domains?
• Selective pressure?

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jingwei the Frankengene
Llopart et al, PNAS, 9912, 8121-8126 (2002).
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Acknowledgments

• Recombination group and Frances
• Chris Adami
• Shoulders of various giants

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And theres more

• Immune-system domain shuffling
• Inteins

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