Genome-wide compilation and analysis of poly(A) sites in Medicago truncatula
The library consisted of cDNA tags that include the mRNA-poly(A) tail junction.  These were prepared as described by Wu et a. (Proceedings of the National Academy of Sciences, USA 2011, 108(30):12533-12538.).  For this, RNA was isolated from roots, stems, and leaves of soil-grown M. truncatula.  A single library was prepared and submitted for sequencing.  This sample contains two sets of bar-coded tags.  The 5'-end (AHBG3_1_1 and AHBG3_1_2) tags possessed either a CATG or ACGT sequence at their ends, followed immediately by the cDNA sequence.  The 3'-end (AHBG3_2_1 and AHBG3_2_2) tags possess a code consisting of NNNGC, followed by an oligo-dT tract of up to 18 nts.