SAXS data for suspended melanosomes from C57BL/6J (B6) and DBA/2J (D2) mice.

<p>Melanosomes were exposed to photons at <i>E</i> = 12.8 keV for 10 s. (A) Comparison of scattering intensities for both phenotypes, in the range of 0.05 to 4.5 nm⁻¹. (B) Analysis of B6 melanosome structure by fitting a model of independent scatterers to the <i>q</i>-interval 0.07 nm⁻¹<<i>q</i><0.27 nm⁻¹. The resulting fitting parameters in the power law are <i>p</i>₁ = 4.034±0.001 (small <i>q</i>-values), <i>p</i>₂ = 3.887±0.118 (high <i>q</i>-values) und <i>R</i>_B6 = 22.57±5.57 nm (radius of gyration of melanosomal subunits). (C) Analysis of D2 melanosome structure by fitting a model of dependent scatterers to data within the <i>q</i>-interval 0.05 nm⁻¹<<i>q</i><0.27 nm⁻¹. The determined parameters are <i>p</i>₁ = 2.56 (modified power law at small <i>q</i>-values), <i>p</i>₂ = 3.60 (power law at high <i>q</i>-values) and <i>R</i>_D2 = 31.32±1.71 nm (radius of gyration of melanosomal subunits). In (B) and (C) the terms that contribute to the fit model used are labeled A1, A2 and A3. The analyzed data points are shown in green.</p

Correlation of maps generated by optical phase-contrast microscopy, cryo microscopy and darkfield cryo-STXM.

<p>Melanosomes of the genotypes C57BL/6J (B6) and DBA/2J (D2) are shown in tiles (A–C) and (D–F), respectively. In both cases, the sample is embedded in an amorphous ice matrix. The optical micrographs, recorded at 100 K, are superimposed with a semi-transparent (B and E) and an opaque (C and F) STXM map. Note that despite the fact that melanosome density is comparable in the two samples, the STXM images feature significant differences in signal intensity as well as the spatial distribution of that signal, revealing structural differences between the melanosomes of the two genotypes. The area of the scanned regions is 20.4×20.4 µm².</p

SEM images of freeze-dried C57BL/6J (B6) and DBA/2J (D2) melanosomes.

<p>The left column contains images recorded in the in-lens detector configuration (IL) and the right column shows micrographs acquired in the out-lens configuration (OL). A direct comparison shows that B6 melanosomes (A and B) have a rather smooth and featureless surface, whereas the D2 organelles (C and D) have an irregular surface. The samples were subjected to the identical preparation protocol. All scale bars represent 500 nm.</p

X-ray scattering data for cryogenically prepared melanosomes from C57BL/6J (B6) and DBA/2J (D2) mice.

<p>(A) Normalized intensity histograms derived from darkfield STXM maps of B6 and D2 samples like those shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090884#pone-0090884-g002" target="_blank">Fig. 2</a>. The intensity of scatter for the D2 melanosomes is higher and has a broader distribution, than that for the B6 sample. The photon energy was 7.9 keV. (B) Sum of 13 background-corrected scattering events, i.e. <i>hits</i>, for a B6 sample. The scattering pattern is anisotropic. (C) Sum of 13 background-corrected scattering events for a D2 sample. The scattering pattern is isotropic. In (B) and (C), intensity is color-coded on a logarithmic scale. The horizontal bars in (B) and (C), which are devoid of signal, correspond to insensitive regions of the PILATUS, and separate the three detector modules. The artificial look of the regions in the centers is due to the stacking of two semi-transparent beamstops.</p