Acid secretion by the gastric parietal cell is controlled through movement of vesicles containing the proton pump, the H(+)-K(+)-ATPase (HK). We have used latrunculin B (Lat B), which binds to monomeric actin, to investigate actin turnover in the stimulated parietal cell. In isolated gastric glands, relatively high concentrations of Lat B were required to inhibit acid accumulation (ED(50) appro...

The F-actin cytoskeleton of Cryptococcus neoformans is known to comprise actin cables, cortical patches and cytokinetic ring. Here, we describe a new F-actin structure in fungi, a perinuclear F-actin collar ring around the cell nucleus, by fluorescent microscopic imaging of rhodamine phalloidin-stained F-actin. Perinuclear F-actin rings form in Cryptococcus neoformans treated with the microtubu...

Functions of nuclear polymeric proteins such as lamin A/C and actin in transport of plasmid DNA were studied. The results show that the lamina plays an important role in plasmid DNA's entry into the cell nucleus from the cytoplasm. Selective disruption of lamin A/C led to a halt in plasmid DNA transport through the nuclear envelope. Inside the nucleus, plasmid DNA was frequently localized at si...

Plant cells expand by exocytosis of wall material contained in Golgi-derived vesicles. We examined the role of local instability of the actin cytoskeleton in specifying the exocytosis site in Arabidopsis root hairs. During root hair growth, a specific actin cytoskeleton configuration is present in the cell's subapex, which consists of fine bundles of actin filaments that become more and more fi...

Dendritic spines have long been known to contain contractile elements and have recently been shown to express apparent spontaneous motility. Using high-resolution imaging of dendritic spines of green-fluorescent protein (GFP)-expressing, patch-clamped hippocampal neurons in dissociated culture, we find that bursts of action potentials, evoked by depolarizing current pulses, cause momentary cont...

We performed a correlative epifluorescence and scanning electron microscopy study of the morphological alterations, both in the actin cytoskeleton organization and in the cellular shape and surface morphology of HeLa, NRK and Vero cells, caused by a variety of actin toxins. To this end, we used actin toxins that depolymerize (cytochalasin D, latrunculin B, and Clostridium botulinum C2 toxin) or...

The hypothesis that dynamic actin filaments participate in specific aspects of synaptic plasticity was investigated at the Schaffer-collateral-CA1 pyramidal cell synapse of mouse hippocampus. Low concentrations (0.01-1 microM) of compounds that inhibit actin filament assembly were bath applied to hippocampal slices during extracellular recording of field excitatory postsynaptic potentials. Cyto...

Cytokinesis is a dynamic and plastic process involving the co-ordinated regulation of many components. Accordingly, many proteins, including the putative scaffold protein anillin, localize to the cleavage furrow and are required for cytokinesis, but how they function together is poorly understood. Anillin can bind to numerous other furrow components, including F-actin, septins and myosin II, bu...

It is well established that higher eukaryotes use alternative splicing to increase proteome complexity. In contrast, Saccharomyces cerevisiae, a single-cell eukaryote, conducts predominantly regulated splicing through retention of nonfunctional introns. In this article we describe our discovery of a functional intron in the PTC7 (YHR076W) gene that can be alternatively spliced to create two mRN...

In many tissues, actin monomers polymerize into actin (thin) filaments of precise lengths. Although the exact mechanisms involved remain unresolved, it is proposed that "molecular rulers" dictate the lengths of the actin filaments. The giant nebulin molecule is a prime candidate for specifying thin filament lengths in striated muscle, but this idea has never been proven. To test this hypothesis...