Chapter 6: Membranes - Endnotes
Modified from Giese, A.C. 1964. Laboratory Manual in Cell
Physiology Revised ed., p 67-68. Boxwood Press, Pittsburgh.
Collect Amoeba by centrifugation three days prior to use, wash,
and resuspend without food. It is important that the Amoeba be
starved for this exercise.
If the dye is too strong, and the Amoeba are stained intensely
blue, dilute the dye 1/10 or even 1/100.
This material is readily available from local slaughter houses.
If there is not one convenient to your location, and a local
butcher will not help, rat brains can be substituted.
Quantities will need to be adjusted accordingly.
This solution is stable for about 5 days if refrigerated, and
can be prepared ahead and used for multiple lab sessions.
A salt bridge is simply a saturated KCl solution (in 2% (w/v)
agar) placed within glass, polyethylene, or teflon capillary
tubes and with platinum electrodes or commercially available
calomel electrodes immersed within the agar. Thus, they bridge
the gap between the solution being monitored and the rather
large wire connections of a recording electrode.
A suitable measurement can be made by using the millivolt
potential scale on a good pH meter. It may require some
assistance from the local physical chemist, or a physicist to
construct the proper electrodes.
Assume a thickness of 5 x 10
cm if it was not measured.
This will model the normal distribution of increased external
observed in vertebrate neurons. As the Na
diffuses into the center of the teflon cup, it will model the
influx of ions associated with an action potential.
Yields of myelin will vary depending upon the developmental age
of the animal and upon the species. Adult rat brains will yield
about 40-90 mg. of pure myelin per brain while the white matter
from bovine brain will yield about 100 mg of pure myelin per
gram of white matter. The purity will depend upon whether whole
brain is used or just the white matter, with the latter yielding
better results. Whole brains would contain a fair amount of
microsomal membranes isolated along with the myelin membranes,
and thus would have more impurities.
The pellet contains mitochondria and myelin vessicles.
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Cell Biology Laboratory Manual
Dr. William H. Heidcamp, Biology Department, Gustavus Adolphus College,
St. Peter, MN 56082 -- firstname.lastname@example.org