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It was shown that a reversible endothermic association of TMV protein subunits (A protein) can take place at pH values below the isoelectric point as well as at pH 6.5. The polymerization occurring below the isoelectric point was found to be more complex than that at pH 6.5 probably because products other than the usual TMV-like rods were formed in addition to those rods and also because side-to-side aggregation of the rods took place readily. Kinetic studies indicated that polymerization can be treated as a second-order linear condensation. The rate of polymerization was found to be a critical function of pH, having a maximum value near pH 4.3. This behavior is at variance with the hypothesis that hydrogen-bonded carboxyl pairs play a dominant rate-determining role in the association of subunits. The dependence of the rate on pH was interpreted to indicate that electrostatic forces between subunits are a significant controlling factor in the polymerization of TMV protein.

It has been shown that when concentration of solute is expressed as amount per unit volume of gel-solvent-solute system, Fick's laws for diffusion in a gel take the same form as for diffusion in solvent alone, except that the usual coefficient must be replaced by a new coefficient, D', equal to D(1 - alphaphi)/(1 - phi), where phi is the effective volume fraction of the gel substance and alpha is a coefficient of obstruction equal to 5/3 if the gel substance can be considered to be made up of randomly oriented rods. An equation was derived for the total amount of solute entering the gel, which is analogous to but not identical with the equation for the total amount of solute crossing the initial boundary in free diffusion. The effect of slice thickness was investigated by a mathematical procedure involving the solutions of approximate differential equations. It was shown that even for slices so thick that 95 per cent of the solute in the gel is contained in the first two, a correction factor equal to the square of the slice thickness divided by 48D't permits one to obtain accurate measurement of D' from the mean concentration and the position of the midplane of the slice.

The sedimentation rates of the mouse infectivity principles of the PR8 and the F12 strains of influenza A virus were shown by studies in the separation cell to have values which are not significantly different from sedimentation rates of the principal components of purified preparations. It was shown further that the bulk of the chicken red blood cell agglutinating activity and of the chick embryo infectivity of PR8 influenza virus preparations sediments at the same rate as that of the 100 mmicro. component. Some activity was shown to be associated with aggregates. These results lend strong support to the assumption that the three biological activities are associated with the particles characterized as spheres with a diameter of about 100 mmicro.

Adsorption and one-step growth experiments performed with blue-green algal virus (BGAV) LPP-1 under normal conditions revealed a slow adsorption rate, in comparison with bacteriophage systems, followed by a 7-hour latent period. The burst size was approximately 100 virus particles per cell. The molecular weight of the virus obtained from sedimentation and diffusion measurements was 51 +/- 3 x 10(6) daltons, and the hydration was calculated to be 0.37 g of H2O per gram of virus. Phosphorus analysis indicated a DNA content of 40% w/w, while amino acid analysis revealed all the common amino acids to be present. At reduced magnesium concentrations, the virus breaks apart, liberating its DNA, which then can be separated from the protein by sedimentation in a CsCl density gradient. A protein component was obtained as ghosts. Neutralization experiments with BGAV antiserum established no relationship to bacteriophages T1, T2, or T3.