These are various movies of exocytosis in sea urchin eggs. The general
principle is that cortical granule exocytosis leaves an exocytotic pit
which can be labeled by extracellular fluorescent markers. This is
illustrated in a simple animation (7K). The first
five movies are from J. Cell Sci 108: 2293 (1995) "Visualization of
exocytosis during sea urchin egg fertilization using confocal microscopy"
abstract
1. Texas red ovalbumin was put into the sea water. The exocytotic
pits are labeled as discs. Time interval between frames is 1 sec. movie (253K)
2. FM 1-43, a water soluble molecule that becomes fluorescent when it
partitions into a membrane and does not cross membranes, was put into the
sea water. The exocytotic pits are labeled as rings. Time interval
between frames is 1 sec. movie (671K) To see a web
page with java animation of this movie click here
3. Simultaneous imaging of FM 1-43 (left) and texas red ovalbumin
(right) shows that both fluorescent markers are labeling the same
structure. Time interval between frames is 1 sec. movie (423K).
4. Simultaneous imaging of FM 1-43 and cortical granules by scanning
DIC shows that the FM 1-43 labeling corresponds to disappearance of the
cortical granule. This demonstrates that the initial labeling by FM 1-43
corresponds to exocytosis. movie (539K)
5. Simultaneous imaging of Ca green dextran inside the egg (left) and
rh dextran in the sea water (right) shows that Ca increases before
exocytosis begins. Time interval between frames is 1 sec. movie (605K)
Simultaneous imaging of an egg at fertilization by phase contrast (left)
and Ca Green fluorescence (right). The fertilizing sperm can be seen
at upper right contacting the egg. There is a Ca action potential
around the entire egg surface (5th frame), then several seconds later,
the Ca
wave starts at the site of sperm entry. The Ca wave triggers cortical
granule exocytosis, leading to the formation of the fertilization
envelope. The fertilization cone (primarily actin filaments) develops
later at the sperm entry point. The first six frames of this sequence
are at 0.5 sec intervals, while the remainder are at 1 sec intervals. movie (2321K). You can also download a compressed version of this movie (358K), where
the fertilizing sperm cannot be seen.
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