Heterologous double-stranded complexe

In fact, all of the heterologous double-stranded complexes which have been tested react to different extents with anti-poly A poly U antibodies. Among these complexes, poly rG poly rC precipitates the smallest amount of antibodies and the reactivity differs not only from that of poly rl poly rC but also from that of the equivalent double-helical polydeoxyribonucleotide complex containing guanine and cytosine residues, poly dG - poly dC (Fig. 5). Thus the homologous antigen precipitates 219.7 [xg/ml of antibodies (expressed as N), poly rl poly rC precipitates almost the same amount, 209.5 (J-g/ml, and poly rG poly rC precipitates only 20.3 [xg/ml, whereas poly dG poly dC shows an intermediate reactivity and precipitates 77.8 (xg/ml of antibodies of the same anti-poly A poly U serum. 

The double helical complex poly A poly U adsorbed onto MBSA has been used as immunogen in Fauve de Bourgogne rabbits (Nahon et al., I967) and in New Zealand White rabbits (Schwartz and Stollar, 1969). In both cases antibodies reacting specifically with poly A poly U were induced. These antibodies react also with the heterologous double-helical complex poly I poly C although they do not react with the separate homopolyribonucleotides poly I or poly C. In addition, the reaction is abolished if the complex is heated in the presence of formaldehyde. It is thus possible to conclude that these antibodies are specific for the double-stranded structure. 

Moreover, it must be emphasized that the fundamental principle of the base-pairing copy of a DNA fibre for RNA synthesis has been firmly established by the technique of molecular hybridization (Spiegelman. 1961). In this method thermally denatured DNA is mixed with RNA and renaturation is allowed to occur slowly. When RNAs homologous to DNA sequences are used, specific double-stranded DNA-RNA complexes are formed, while no hybrid formation occurs with heterologous RNAs. 

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