Modify Tagment DNA buffer recipe in sciprep.md

Updated the Tagment DNA buffer recipe to include 8% PEG-8000 instead of dimethylformamide.

Author: chaichontat

scirnaseq3/sciprep.md

@@ -137,7 +137,7 @@ The annealed N7 oligos are Tn5-N7 (<span class="sequence">5'-GTCTCGTGGGCTCGGAGAT
 To 20 μl of Tn5, add 20 μl of annealed N7 oligos. Place in a thermomixer and shake at 350 rpm and 23 °C for 30 min. Add 20 μl of glycerol. Store at -20 °C for &le;6 months.
 
 - <span class="buffer">Tagment DNA buffer (2×)</span><br>
-To 38.75 ml of nuclease-free water, add 1ml of 1M Tris pH7.6, 250μl of 2M MgCl<sub>2</sub> and 10 ml of dimethylformamide. The final volume is 50 ml. Make 550 μl aliquots and store them at -20 °C for &le;6 months.
+To 38.75 ml of nuclease-free water, add 1ml of 1M Tris pH7.6, 250μl of 2M MgCl<sub>2</sub> and 8% PEG-8000. The final volume is 50 ml. Make 550 μl aliquots and store them at -20 °C for &le;6 months.
 
 - <span class="buffer">Indexed primer plates</span><br>
 Primers for reverse transcription, ligation and PCR indexing steps are ordered at 100 μM. Working dilutions are made to 10 μM in EB (10 mM Tris-Cl pH 8.5) and kept at 4 °C for &le;6 months.
@@ -160,4 +160,4 @@ Add 7 ml of water to a bottle of lyophilized Qiagen protease (Qiagen, cat. no. 1
 
 <aside>
 <span class="critical">CRITICAL:</span>  This must be the specified protease, not proteinase K.
-</aside>
+</aside>