both viruses ( termed rat leukemia virus , ralv ) were released spontaneously from rat embryo cells , have a density of 1.14 to 1.15 g/cm ( 3 ) based on equilibrium sedimentation in sucrose gradients , contain 60-70s rna , rna-directed dna polymerase , and rat type c virus-specific 30,000 molecular-weight-protein determinants .
C0034693
rat
C1335665
rat