we show that ( i ) uninfected cells do not contain rna sequences related to the visna virus genome , ( ii ) parental rna is rapidly transported to the nucleus of the infected cell , ( iii ) virus rna is synthesized in the nucleus and then transported to the cytoplasm ( iv ) synthesis of rna proceeds mostly exponentially to reach levels of about 4,000 copies per cell at the end of the growth cycle , ( v ) nuclear and cytoplasmic rna sediment in two size classes , 35s and 10-20s , ( vi ) viral mrna has the same polarity as genome rna and also sediments in two size classes of 35s and 10-20s .
C0007610
nucleus
C0007634
cell