The virus-like particles (VLPs) produced by the yeast retrotransposon Ty1 are functionally related to retroviral cores. These particles are unusual in that they have variable radii. A paired mass-radius analysis of VLPs by scanning transmission electron microscopy showed that many of these particles form an icosahedral T-number series. Three-dimensional reconstruction to 38-Å resolution from cryo-electron micrographs of T‫3؍‬ and T‫4؍‬ shells revealed that the single structural protein encoded by the TYA gene assembles into spiky shells from trimeric units.

With few exceptions, a single primary cllium is associated with virtually all vertebrate cell types. These cilia are often located adjacent to the nucleus and possess a 9+0 axonemal microtubule pattern which is generated by the “eldest” or “parent” centriole. Despite their ubiquity, the in vivo properties of primary cilia are largely unknown, primarily because their orientation perpendicular to the dorsal cell surface (and parallel to the optical axis) makes them difficult to observe by LM. To circumvent this problem, we have developed novel methods for imaging primary cilia in vivo and for examining selected cilia at the EM level.Kidney epithelial cells (PtK, MDCK, BSC) are grown to confluency on 22 x 40mm solvent-cast Formvar films (0.5 μm thick). A side view of the mono-layer is obtained by folding the film, cell-side out, and sandwiching it in a simple coverslip chamber.