Beating
Myocyte Movie
(Birren Lab) |
The movie shows a co-culture
of rat sympathetic neurons and cardiac myocytes. In
the animal, sympathetic innervation of the heart plays
a key role in the modulation of cardiac function. This
can also be seen in culture where the spontaneous beating
of cardiac myocytes is altered by electrical stimulation
of a connected sympathetic neuron. Neuronal stimulation
results in the release of neurotransmitter from the
neuron and the activation of myocyte receptors. By monitoring
the beat rate of the cultured myocyte during neuronal
stimulation we are able to use this culture system to
investigate the role of neurotrophic factors in regulating
the release of neurotransmitter from the sympathetic
neurons. |
QM/MM Calculations
Triose
Phosphate Isomerase (TIM)
reaction movie (13 MB)
(Ringe-Petsko
Lab)
|
The sequence of events in this movie are:
Diffusion
of substrate DHAP into the active site of the enzyme
- Transfer of a proton from the methylene group
of DHAP to Glu 165 of TIM
- His 95 facilitates proton transfer between two
oxygens of the substrate
- Final proton transfer and diffusion away from
the enzyme
|
This movie shows an experiment from:
"Chi-sequence Recognition and DNA Translocation
by Single RecBCD Helicase/Nuclease Molecules"
K. Dohoney and J. Gelles (2001)
Nature 409, pp. 370 - 374.
Windows video (.avi) format
Quicktime
(.mov) format
The video is real time; the frame size is 6.5 µm
wide by 6.6 µm tall. |
The
movie shows a bead-labeled RecBCD molecule translocating
along a single DNA molecule. Initially, the free diffusion
of beads in solution is seen. After a few seconds,
one of the bead-labeled enzyme molecules attaches
to the end of a DNA molecule at the center of the
field (arrows); attachment is detected as the cessation
of free diffusion and the commencement of characteristic
tethered-particle Brownian motion in the vicinity
of a single point on the microscope slide. Subsequent
translocation of the enzyme along the DNA molecule
is visualized as a gradual decrease in the spatial
range of the Brownian motion; this decrease continues
until the beads ceases visible movement altogether.
This experiment was performed as shown in Fig. 1 of
the paper, except that the ATP concentration was reduced
to 10 µM to slow translocation.
|
|
Early Drosophila embryos undergo
drastic changes in their transparency during just a
few hours. At first, they are completely opaque, then
the periphery turns transparent, but later clouds up
again. These changes in opacity are due to large scale
transport of yolk storage organelles: cytoplasm filled
with these organelles is opaque, cytoplasm depleted
of them is clear. This property allows us to monitor
the global distribution of organelles in living embryos. |
|
In the periphery of early
Drosophila embryos, lipid droplets show bi-directional
motion along microtubules. They reverse direction every
few seconds, alternately employing minus- and plus-end
directed motors. Individual droplets can be followed
in real time, and their motion can be analyzed with
nanometer-scale precision. |