both bacteriophage pbs1 deoxyribonucleic acid ( dna ) ( in which all the thymine residues are replaced by uracil ) and phage phiw-14 dna [ in which half the thymine residues are replaced by 5- ( aminobutylaminomethyl ) uracil or 5-putrescinylthymine ] exhibit comparable competing abilities for uptake of homologous dna in a bacillus subtilis competent system .
C0040087
thymine
C0041917
uracil