- 20% N-Lauroylsarcosine sodium salt solution (e.g., Sigma-
Aldrich). - Deoxycholic acid sodium salt (e.g., Thermo Fisher Scientific).
29.D-Biotin. - RNase cocktail enzyme mix (Ambion, cat. no. AM2286).
- RNase H (e.g., Enzymatics).
- DNA ladder, 25 bp.
- Denaturing PAGE loading buffer (e.g., Ambion Gel loading
buffer II). - SYBR Gold nucleic acid gel stain, 10,000 (e.g., Life
Technologies). - 40 w/v % acrylamide–bis solution, 29:1.
- CircLigase II ssDNA ligase (e.g., Epicentre, cat. no.
CL9025K). - Phusion high-fidelity (HF) PCR master mix with HF buffer
(e.g., NEB). - SYBR Green I nucleic acid gel stain, 10,000 (e.g., Life
Technologies).
2.2 Oligos Used
for Library Preparation
- Preadenylated and 3^0 -biotin blocked RNA adapter (PAGE pur-
ified): /5rApp/AGATC GGAAG AGCGG TTCAG/3Biotin/
. This designed adapter is important for efficient ligation on the
30 end of RNA. - RT-primer-1 (DNA, standard desalting purification). /5phos/
WWW NNN ATCACG NNNNN TACCC TTCGC TTCAC
ACACA AG/iSp18/GGATCC /iSp18/TACTG AACCGC,
W¼A/T and N¼A/T/G/C are used to discriminate PCR
duplicates, “ATCACG” is the specific experimental barcode, /
iSp18/ is a spacer to prevent PCR from forming concatemers).
The following is a list of 24 barcodes: 1. ATCACG, 2.
CGATGT, 3. TTAGGC, 4. TGACCA, 5. ACAGTG, 6.
GCCAAT, 7. CAGATC, 8. ACTTGA, 9. GATCAG, 10.
TAGCTT, 11. GGCTAC, 12. CTTGTA, 13. AGTCAA, 14.
AGTTCC, 15. ATGTCA, 16. CCGTCC, 17. GTCCGC, 18.
GTGAAA, 19. GTGGCC, 20. GTTTCG, 21. CGTACG, 22.
GAGTGG, 23. ACTGAT, 24. ATTCCT. The quality of the
oligonucleotide synthesis should be verified by polyacrylamide
gel electrophoresis; however, bulk PAGE purification before
use in RT reactions is not necessary. - P3Tall v4 primer (PAGE purified): GGCAT TCCTG CTGAA
CCGCT CTTCC GATCT. P6Tall v4 primer (PAGE purified):
CTCTT TCCCC TTGTG TGTGA AGCGA AGGGT.
62 Zhipeng Lu et al.