Sci Rep. 2017 Feb 2;7:41769. doi:10.1038/srep41769

Ohtsubo Y, Nagata Y, Tsuda M.

Efficient N-tailing of blunt DNA ends by Moloney murine leukemia virus reverse transcriptase.

Specific tailing of first-strand cDNAs is robustly enhanced by the complementary dNMP (C enhanced by dGMP, etc.). A-tailing is not enhanced, perhaps because it is already very strong. Reactions made in presence of manganese; not tested with only magnesium.