Architecture of the cytoplasmic face of the nuclear pore.

INTRODUCTION The subcellular compartmentalization of eukaryotic cells requires selective transport of folded proteins and protein-nucleic acid complexes. Embedded in nuclear envelope pores, which are generated by the circumscribed fusion of the inner and outer nuclear membranes, nuclear pore complexes (NPCs) are the sole bidirectional gateways for nucleocytoplasmic transport. The ~110-MDa human NPC is an ~1000-protein assembly that comprises multiple copies of ~34 different proteins, collectively termed nucleoporins.

High-Resolution Imaging and Analysis of Individual Nuclear Pore Complexes.

Field emission scanning electron microscopy (FESEM) is a well-established technique for acquiring three-dimensional surface images of nuclear pore complexes (NPCs). We present an optimized protocol for the exposure of mammalian cell nuclei and direct surface imaging of nuclear envelopes by FESEM, allowing for a detailed morphological comparison of individual NPCs, without the need for averaging techniques. This provides a unique high resolution tool for studying the effects of cellular stress, specific genetic manipulations and inherited diseases on the ultrastructure of human NPCs.

The cellular environment shapes the nuclear pore complex architecture.

Nuclear pore complexes (NPCs) create large conduits for cargo transport between the nucleus and cytoplasm across the nuclear envelope (NE). These multi-megadalton structures are composed of about thirty different nucleoporins that are distributed in three main substructures (the inner, cytoplasmic and nucleoplasmic rings) around the central transport channel. Here we use cryo-electron tomography on DLD-1 cells that were prepared using cryo-focused-ion-beam milling to generate a structural model for the human NPC in its native environment.

New Imaging Tools to Analyze Mitochondrial Morphology in Caenorhabditis elegans.

Mitochondria are highly dynamic organelles that constantly fuse and divide. This process is essential as several neurodegenerative diseases have been associated with defects in mitochondrial fusion or fission. Several tools have been developed over the years to visualize mitochondria in organisms such as Caenorhabditis elegans.

Age-dependent changes in mitochondrial morphology and volume are not predictors of lifespan.

Mitochondrial dysfunction is a hallmark of skeletal muscle degeneration during aging. One mechanism through which mitochondrial dysfunction can be caused is through changes in mitochondrial morphology. To determine the role of mitochondrial morphology changes in age-dependent mitochondrial dysfunction, we studied mitochondrial morphology in body wall muscles of the nematodeC.