Homologous   recombination
   during meiosis.
<lI> Two DNA duplexes that share homologous sequence are paired.
<lI> Endonuclease  nicking  produces  single-stranded cuts at identical
positions.
<lI> The  single  strands are displaced and pair with their complements
on the opposite duplex.
<lI> A   ligase   seals  the  loose  ends,  creating  heteroduplex  DNA
molecules.

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