\! Project Title: 16, Molecular and Cellular Radiobiology Storage and Transfer of the Genetic Méssage Technical Progress in FY 1973: RX-03-02-(d) (Cont'd,) As part of the program of complexing polynucleotide complexes with other molecules, e.g. histones, to decrease their biodegradability in vivo and hence potentially increase their biological effectiveness, double-helical polynucleotide molecules were complexed with histones and with the basic polypeptides poly-L-lysine and poly-L-arginine. For some time it has been clear that nucleohistone in its native state is in a contracted form. One interpretation of x-ray diffraction studies of nucleohistone suggests that it has a supercoiled structure; electron-microscope studies on chromatin support the idea of such structures,: But the x-ray data are not unequivocal; DNA complexed to histone is presumably in the B conformation and diffraction patterns are therefore not overly sharp or detailed. Moreover soluble preparations of such complexes needed for x-ray diffraction studies of fibers of nucleohistone are extremely difficult to prepare (see below), ‘For these reasons, if superstructures were induced in synthetic polyribonucleotides which are in the A conformation (giving sharper and more detailed x-ray - patterns), by complexing with simpler model molecules, e.g. basic polypeptides, x-ray diffraction studies of such model complexes could throw light on supercoiling in nucleohistones and the structure of chromosomes, Complexing of double-helical polynucleotides with histones most frequently gives rise to an insoluble precipitated complex. Only occasionally, by adjusting the concentration of histones relative to polynucleotides, : by complexing in high salt concentration, and then by gradual and careful dialysis of these complexes has it been possible to retain complexes that remained soluble at physiological salt concentration needed for the therapeutic trial and x-ray diffraction studies of such complexes. Soluble complexes have been obtained more reproducibly from complexing poly(rI-rC) . with polylysine or polyarginine in a 10:1 ratio, Such complexes have shown significant increases in their melting temperature (TM) and also in resistance to ribonuclease digestion as compared with poly(rlerC) alone, Preliminary x-ray patterns of fibers of complexes of poly(rlI-rC) and polyarginine show signs of sharper reflections near the centers of the patterns and suggest that there is, in fact, superstructure in these synthetic RNA complexes. These studies continue. In studies here and in collaboration with Dr. Chester Southam (Jefferson Medical College of Thomas Jefferson University, Philadelphia), the biological effects of various. complexes of synthetic polynucleotides by thems@jyes and complexed with other molecules have been tested against Semig#@ Forest virus (SFV) infection in mice and in human cells in culture. SFV fia mosquito-borne (RNA) virus (arbovirus group A) of the same anti- genic group as Eastern, Western and Venezuelan Equine Encephalitis viruses (EEE, WEE, VEE). [It causes lethal encephalitis in adult mice when inoculated intraperitoneally (ip) or intracerebrally (ic) and has a cytopathogenic effect (CPE) on human cells in culture, It can cause encephalitis in man (See Continuation Sheet) 4199315 RX-255