Figure 4

Filtering results on the tomograms of unstained specimens. (a) small unilamellar liposomes with integrin; (b) Vaccinia virion, (c) HIV-1 virions. The original tomograms (left), the results with TOMOBFLOW (centre), and the results with three iterations of the median filtering (right) are shown. Only a representative slice of the tomograms is presented. The number of iterations of TOMOBFLOW were (a) 100, (b) 50 and (c) 70. The datasets (a) and (c) were taken from the Electron Microscopy Data Bank (EMDB) at the European Bioinformatics Institute (accession codes 1487 and 1155, respectively). The dataset (b) comes from a previous work [24]. The behaviour of the methods are similar to that shown for unstained specimens. In general, TOMOBFLOW smoothens the background better than the median filtering and allows better identification of fine structural details (see for instance the areas pointed by the arrows, e.g. the spikes of the core of the Vaccinia virion or the membranes of the HIV-1 virions).