Arrangement of chromatin in intact chicken erythrocyte nuclei was investigated by small angle neutron scattering. The scattering spectra have revealed that on the scales between 15 nm and 1.5 lm the interior of the nucleus exhibited properties of a mass fractal. The fractal dimension of the protein component of cell nucleus held constant at approximately 2.5, while the DNA organization was biphasic, with the fractal dimension slightly higher than 2 on the scales smaller than 300 nm and approaching 3 on the larger scales.

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Using small angle neutron scattering in combination with optical Raman spectroscopy, phase transitions in the micellar system tetradecyl-trimethylammonium bromide (TTAB) have been investigated in a wide range of temperatures, pressures and surfactant concentrations. Allowing for the sluggish kinetics of crystallisation, the phase diagram in the p-T-c space could be determined that is dominated by a pronounced two-phase region of coexisting liquid and solid phases at elevated pressures.

The ¢lament structures of the self-polymers of RecA proteins from Escherichia coli and Pseudomonas aeruginosa, their complexes with ATPQ QS, phage M13 single-stranded DNA (ssDNA) and the tertiary complexes RecA: :ATPQ QS: :ss-DNA were compared by small angle neutron scattering. A model was developed that allowed for an analytical solution for small angle scattering on a long helical ¢lament, making it possible to obtain the helical pitch and the mean diameter of the protein ¢lament from the scattering curves. The results suggest that the structure of the ¢laments formed by these two RecA proteins, and particularly their complexes with ATPQ QS, is conservative. ß

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