Organism	Tissue	Adenine	Thymine	Guanine	Cytosine	AT/GC
Escherichia coli (K12)	NA	26.0	23.9	24.9	25.2	1.00
Diplococcus pneumoniae 	NA	29.8	31.6	20.5	18.0	1.59
Mycobacterium tuberculosis 	NA	15.1	14.6	34.9	35.4	0.42
Yeast	NA	31.3	32.9	18.7	17.1	1.79
Paracentrotus lividus	Sperm	32.8	32.1	17.7	18.4	1.85
Herring	Sperm	27.8	27.5	22.2	22.6	1.23
Rat	Bone marrow	28.6	28.4	21.4	21.5	1.33
Human	Thymus	30.9	29.4	19.9	19.8	1.52
Human	Liver	30.3	30.3	19.5	19.9	1.53
Human	Sperm	30.7	31.2	19.3	18.8	1.62