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Old 03-12-2019, 11:06 AM   #2
lydsmith
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Location: Berkeley, CA

Join Date: Jul 2012
Posts: 3
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Hi adamcarol. I can say that the original formulation of home-made SPRI beads as published in Rohland & Reich 2012 (who Faircloth & Glenn do properly credit in their own protocol) work terribly below a ratio of 0.9X or so. I had a lot of problems getting double-sided selections of 0.55x/0.7x to work properly until I came across this alternative recipe from Philippe Jolivet and Joseph W. Foley:
https://openwetware.org/wiki/SPRI_bead_mix

Their recipe has some differences, but the bead mix components end up being the same as Rohland & Reich except that 1) PEG is increased from 18% to 20% and 2) NaCl is increased from 0.5M to 2.5M. The latter seems to be key since I have made hybrid beads (18% PEG / 2.5M NaCl) which approximate commercial ones best of all.
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