Exploring vitreous cryo-section-induced compression at the macromolecular level using electron cryo-tomography; 80S yeast ribosomes appear unaffected.

Vitreous cryo-section-induced compression influences the interpretation and the reliability of electron microscopy images and tomographic reconstructions. Previous studies of this deformation have been focused at the cellular level where considerable compression occurs, yet the degree of possible intracellular macromolecular deformation has remained unclear. Here, electron cryo-tomographic reconstructions of vitreous cryo-sections show that 80S ribosomes, both intracellular and in an isolated state, appear able to resist section-induced compression.

TEM study of locally coated nanopore fabricated by ion-beam-induced deposition in a thin membrane.

We studied the formation of locally coated sub-10-nm nanopores fabricated by ion-beam milling and ion-beam-induced deposition (IBID) in a thin silicon nitride membrane. Two typical precursor gases representing conductive ((CH(3))(3)Pt(CpCH(3)), CPC for short) and insulating (tetra ethyl oxysilane, TEOS for short) material deposition are used. Three-dimensional electron tomography, EDX and EELS analysis are used to measure the changes in chemical composition and shape of the pores after their formation and at various stages of pore shrinkage.

Control of shape and material composition of solid-state nanopores.

Solid-state nanopores fabricated by a high-intensity electron beam in ceramic membranes can be fine-tuned on three-dimensional geometry and composition by choice of materials and beam sculpting conditions. For similar beam conditions, 8 nm diameter nanopores fabricated in membranes containing SiO(2) show large depletion areas (70 nm in radius) with small sidewall angles (55 degrees ), whereas those made in SiN membranes show small depletion areas (40 nm) with larger sidewall angles (75 degrees ). Three-dimensional electron tomograms of nanopores fabricated in a SiO(2)/SiN/SiO(2) membrane show a biconical shape with symmetric top and bottom and indicate a mixing of SiN and SiO(2) layers up to 30 nm from the edge of nanopore, with Si-rich particles throughout the membrane.

Three-dimensional architecture of hair-bundle linkages revealed by electron-microscopic tomography.

The senses of hearing and balance rest upon mechanoelectrical transduction by the hair bundles of hair cells in the inner ear. Located at the apical cellular surface, each hair bundle comprises several tens of stereocilia and a single kinocilium that are interconnected by extracellular proteinaceous links. Using electron-microscopic tomography of bullfrog saccular sensory epithelia, we examined the three-dimensional structures of basal links, kinociliary links, and tip links.

Influence of charged surfaces on the morphology of DNA condensed with multivalent ions.

DNA in solution can be condensed into dense aggregates by multivalent counterions. Here we investigate the effect of a nearby surface on the morphology of DNA condensates. We show that, contrary to what has often been assumed, interactions between DNA condensates and the surface can strongly influence the observed morphology.