latrunculin-a and rhodamine-phalloidin

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 microtubule inhibitor Nocodazole or with the drug solvent dimethyl sulfoxide (DMSO) or grown in yeast extract peptone dextrose (YEPD) medium, but they are absent in cells treated with Latrunculin A. Perinuclear F-actin rings may function as 'funicular cabin' for the cell nucleus, and actin cables as intracellular 'funicular' suspending nucleus in the central position in the cell and moving nucleus along the polarity axis along actin cables.

Topics: Actin Cytoskeleton; Actins; Bridged Bicyclo Compounds, Heterocyclic; Cell Nucleus; Cryptococcus neoformans; Dimethyl Sulfoxide; Free Radical Scavengers; Marine Toxins; Microscopy, Electron; Microscopy, Fluorescence; Microtubules; Nocodazole; Phalloidine; Rhodamines; Thiazolidines; Tubulin Modulators

In mammals, memory formation and stabilization requires polymerization of actin. Here, we show that, in the honeybee, inhibition of actin polymerization within the brain centres involved in memory formation, the mushroom bodies (MBs), enhances associative olfactory memory. Local application of inhibitors of actin polymerization (Cytochalasin D or Latrunculin A) to the MBs 1 h before induction of long-term memory increased memory retention 2 and 24 h after the onset of training. Post-training application of Cytochalasin D also enhanced retention, indicating that memory consolidation is facilitated by actin depolymerization. We conclude that certain aspects of memory mechanisms could have been established independently in mammals and insects.

Topics: Actins; Animals; Bees; Biological Evolution; Bridged Bicyclo Compounds, Heterocyclic; Conditioning, Psychological; Cytochalasin D; Memory, Long-Term; Microinjections; Mushroom Bodies; Phalloidine; Polymerization; Rhodamines; Smell; Thiazolidines