Time-of-flight spin-echo small-angle neutron scattering applied to biological cell nuclei
E.G. Iashina (Petersburg Nuclear Physics Institute (PNPI), St. Petersburg State University)
W.G. Bouwman (TU Delft - RST/Neutron and Positron Methods in Materials)
C.P. Duif (TU Delft - RST/Technici Pool, TU Delft - RID/TS/Technici Pool)
Robert M. Dalgliesh (ISIS Neutron and Muon Source)
Elena Y. Varfolomeeva (Petersburg Nuclear Physics Institute (PNPI))
Rimma A. Pantina (Petersburg Nuclear Physics Institute (PNPI))
Roman A. Kovalev (Petersburg Nuclear Physics Institute (PNPI))
Natalia D. Fedorova (Petersburg Nuclear Physics Institute (PNPI))
S. V. Grigoriev (Petersburg Nuclear Physics Institute (PNPI), St. Petersburg State University)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
The organization of chromatin in the nuclei of rat lymphocyte was studied by time-of-flight spin-echo small-angle neutron scattering (ToF-SESANS). The procedures of the measurements in ToF and monochromatic SESANS modes were compared. It is shown that the sensitivity of the ToF method is significantly higher than that of the monochromatic mode. As a result, the SESANS correlation function can always be extracted from the ToF measurement of polarization, while this is not always the case with the monochromatic mode. The applicability of SESANS to fractal objects at the micrometre scale is demonstrated. The SESANS correlation function is well fitted by the exponential decay G(z) = exp(−z/ξ) with the correlation length ξ = 3.7 ± 0.1 µm. The exponential decay of the SESANS correlation function can be connected to the logarithmic correlation function γ(r) = ln(r/ξ) and the cubic law of the scattering intensity I(Q) = Q−3, which is in agreement with the concept of scattering from fractal objects. This finding is interpreted as evidence of a very specific logarithmic fractal structure of the large-scale organization of chromatin. The model of the logarithmic fractal is visualized as a hierarchical object obeying the volume-conservation principle at different scales.